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Vol. 48 N° 15 - Août 2009 [texte imprimé] . - 2009 . - p. 6907-7454 : ill. ; 28 cm. Chemical engineering Langues : Français (fre)
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Ajouter le résultat dans votre panierModeling the Soret effect in dense media mixtures / Kenneth Harstad in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009)
Titre : Modeling the Soret effect in dense media mixtures Type de document : texte imprimé Auteurs : Kenneth Harstad, Auteur Année de publication : 2009 Article en page(s) : pp. 6907–6915 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Soret effect Dense media Thermal diffusion coefficients Résumé : A basic aim of this paper is to provide, as much as possible, a comprehensive and unambiguous description of the Soret effect in dense media. To this end, the available literature was examined for unifying themes; the themes found are presented. Many trends in the behavior of thermal diffusion coefficients are found to be correlated to equation-of-state properties. The evolutionary paths of media undergoing heating have the essential constraint of positive entropy production, as expressed by the theoretical relations of nonequilibrium thermodynamics; these are summarized. Also given are the relations between thermodynamic forces that define the path attractor states of media mixtures under steady heating conditions. Data references are given; almost all the available data relates to these asymptotic steady attractor states. There is little or no data available corresponding to the transient paths that are explicitly more dependent on the species diffusive transport mechanisms (rates). The concept of “heats of transfer” to express the thermal diffusion factors is verified to be generally valid for a slight modification of the defining relation as commonly presented. The heats of transfer are equivalent to an extension of kinetic theory thermal diffusion ratios. A discussion on the perspectives needed to properly form generic thermal diffusion models that are valid for any particular situation is given. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900213z
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6907–6915[article] Modeling the Soret effect in dense media mixtures [texte imprimé] / Kenneth Harstad, Auteur . - 2009 . - pp. 6907–6915.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6907–6915
Mots-clés : Soret effect Dense media Thermal diffusion coefficients Résumé : A basic aim of this paper is to provide, as much as possible, a comprehensive and unambiguous description of the Soret effect in dense media. To this end, the available literature was examined for unifying themes; the themes found are presented. Many trends in the behavior of thermal diffusion coefficients are found to be correlated to equation-of-state properties. The evolutionary paths of media undergoing heating have the essential constraint of positive entropy production, as expressed by the theoretical relations of nonequilibrium thermodynamics; these are summarized. Also given are the relations between thermodynamic forces that define the path attractor states of media mixtures under steady heating conditions. Data references are given; almost all the available data relates to these asymptotic steady attractor states. There is little or no data available corresponding to the transient paths that are explicitly more dependent on the species diffusive transport mechanisms (rates). The concept of “heats of transfer” to express the thermal diffusion factors is verified to be generally valid for a slight modification of the defining relation as commonly presented. The heats of transfer are equivalent to an extension of kinetic theory thermal diffusion ratios. A discussion on the perspectives needed to properly form generic thermal diffusion models that are valid for any particular situation is given. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900213z Exemplaires
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Titre : Dispersion stability enhancement of titania nanoparticles in organic solvent using a bead mill process Type de document : texte imprimé Auteurs : I Made Joni, Auteur ; Agus Purwanto, Auteur ; Ferry Iskandar, Auteur Année de publication : 2009 Article en page(s) : pp. 6916–6922 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Titania nanoparticles Stable dispersion Organic solvent Diglyme Bead milling process Résumé : A stable dispersion of titania nanoparticles (primary size 15 nm) in an organic solvent of diethylene glycol dimethylether (diglyme) was successfully prepared using a bead milling process. In order to enhance dispersion stability of the solution, surface modification of dispersed titania particles was carried out during the centrifugal bead mill process. Surface modification was utilized with silane coupling agents, (3-acryl-oxypropyl)trimethoxysilane and trimethoxypropylsilane. The effects of surface modification at selected milling times on the morphology, mean particle size distribution, and degree of dispersion stability by means of zeta potential were investigated. The effect of titania concentration (1 wt %, 5 wt %, and 10 wt %) on the optical transmission properties was also examined. Finally, a solution with a high degree of dispersion stability with zeta potential up to 80 mV was obtained. The achievement of a decrease in average particle size to approximately the primary size of 15 nm and high dispersion stability has improved solution optical transparency at a corresponding concentration of titania particles. Surface-modified nanoparticles sustained their UV filter properties as desired in titania-based composites for optical applications. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801812f
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6916–6922[article] Dispersion stability enhancement of titania nanoparticles in organic solvent using a bead mill process [texte imprimé] / I Made Joni, Auteur ; Agus Purwanto, Auteur ; Ferry Iskandar, Auteur . - 2009 . - pp. 6916–6922.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6916–6922
Mots-clés : Titania nanoparticles Stable dispersion Organic solvent Diglyme Bead milling process Résumé : A stable dispersion of titania nanoparticles (primary size 15 nm) in an organic solvent of diethylene glycol dimethylether (diglyme) was successfully prepared using a bead milling process. In order to enhance dispersion stability of the solution, surface modification of dispersed titania particles was carried out during the centrifugal bead mill process. Surface modification was utilized with silane coupling agents, (3-acryl-oxypropyl)trimethoxysilane and trimethoxypropylsilane. The effects of surface modification at selected milling times on the morphology, mean particle size distribution, and degree of dispersion stability by means of zeta potential were investigated. The effect of titania concentration (1 wt %, 5 wt %, and 10 wt %) on the optical transmission properties was also examined. Finally, a solution with a high degree of dispersion stability with zeta potential up to 80 mV was obtained. The achievement of a decrease in average particle size to approximately the primary size of 15 nm and high dispersion stability has improved solution optical transparency at a corresponding concentration of titania particles. Surface-modified nanoparticles sustained their UV filter properties as desired in titania-based composites for optical applications. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801812f Exemplaires
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Titre : One step bio-oil upgrading through hydrotreatment, esterification, and cracking Type de document : texte imprimé Auteurs : Zhe Tang, Auteur ; Qiang Lu, Auteur ; Ying Zhang, Auteur Année de publication : 2009 Article en page(s) : pp. 6923–6929 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Crude bio-oil Supercritical ethanol Hydrogen atmosphere Pd/SO42− /ZrO2/SBA-15 catalyst Résumé : The crude bio-oil was upgraded in supercritical ethanol under hydrogen atmosphere by using Pd/SO42−/ZrO2/SBA-15 catalyst. This is a novel way to upgrade bio-oil with the combination of hydrotreatment, esterification, and cracking under supercritical conditions. The results indicated that the upgrading process performed effectively and the properties of the upgraded bio-oil were improved significantly. After the upgrading process, a trace amount of tar or coke was produced and most of the organic components were kept in the upgraded bio-oil. No phase separation was observed. The amount of aldehydes and ketones decreased evidently. In particular, aldehydes were almost completely removed. Most acids were converted into corresponding esters, and at the same time many new types of esters were produced. The results of TGA and DTA indicated that macromolecular compounds were decomposed and much more volatile compounds were produced after the upgrading process. The pH value and heating value of the upgraded bio-oil increased; meanwhile, the kinematical viscosity and density decreased compared to those of the crude bio-oil. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900108d
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6923–6929[article] One step bio-oil upgrading through hydrotreatment, esterification, and cracking [texte imprimé] / Zhe Tang, Auteur ; Qiang Lu, Auteur ; Ying Zhang, Auteur . - 2009 . - pp. 6923–6929.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6923–6929
Mots-clés : Crude bio-oil Supercritical ethanol Hydrogen atmosphere Pd/SO42− /ZrO2/SBA-15 catalyst Résumé : The crude bio-oil was upgraded in supercritical ethanol under hydrogen atmosphere by using Pd/SO42−/ZrO2/SBA-15 catalyst. This is a novel way to upgrade bio-oil with the combination of hydrotreatment, esterification, and cracking under supercritical conditions. The results indicated that the upgrading process performed effectively and the properties of the upgraded bio-oil were improved significantly. After the upgrading process, a trace amount of tar or coke was produced and most of the organic components were kept in the upgraded bio-oil. No phase separation was observed. The amount of aldehydes and ketones decreased evidently. In particular, aldehydes were almost completely removed. Most acids were converted into corresponding esters, and at the same time many new types of esters were produced. The results of TGA and DTA indicated that macromolecular compounds were decomposed and much more volatile compounds were produced after the upgrading process. The pH value and heating value of the upgraded bio-oil increased; meanwhile, the kinematical viscosity and density decreased compared to those of the crude bio-oil. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900108d Exemplaires
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Titre : Comparative studies on porous material-supported Pd catalysts for catalytic oxidation of benzene, toluene, and ethyl acetate Type de document : texte imprimé Auteurs : Chi He, Auteur ; Jinjun Li, Auteur ; Jie Cheng, Auteur Année de publication : 2009 Article en page(s) : pp. 6930–6936 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Molecular sieves-supported palladium catalysts Benzene elimination Toluene Ethyl acetate Résumé : The feasibility and mechanism of five molecular sieves-supported palladium catalysts in elimination of benzene, toluene, and ethyl acetate were investigated. The experimental results indicate that Pd particles are well dispersed on these porous supports with size of 2−10 nm, while mesoporous supports with a larger specific surface area and pore diameter lead to a better dispersion. The activity of freshly made catalysts obeys the following order: Pd/Beta > Pd/ZSM-5 > Pd/SBA-15 > Pd/MCM-48 > Pd/MCM-41. Although Pd/Beta has the highest activity for removal of these VOCs in the beginning, its activity quickly decreases. However, Pd/ZSM-5 and Pd/SBA-15 show a good stability, without activity loss in a 72 h test. Our research reveals that higher acidity can facilitate catalytic reaction and gives rise to higher activity, but it also enhances coke formation and decreases the catalyst stability. In addition, the porosity of supports has a certain impact on catalytic oxidation of VOCs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900412c
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6930–6936[article] Comparative studies on porous material-supported Pd catalysts for catalytic oxidation of benzene, toluene, and ethyl acetate [texte imprimé] / Chi He, Auteur ; Jinjun Li, Auteur ; Jie Cheng, Auteur . - 2009 . - pp. 6930–6936.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6930–6936
Mots-clés : Molecular sieves-supported palladium catalysts Benzene elimination Toluene Ethyl acetate Résumé : The feasibility and mechanism of five molecular sieves-supported palladium catalysts in elimination of benzene, toluene, and ethyl acetate were investigated. The experimental results indicate that Pd particles are well dispersed on these porous supports with size of 2−10 nm, while mesoporous supports with a larger specific surface area and pore diameter lead to a better dispersion. The activity of freshly made catalysts obeys the following order: Pd/Beta > Pd/ZSM-5 > Pd/SBA-15 > Pd/MCM-48 > Pd/MCM-41. Although Pd/Beta has the highest activity for removal of these VOCs in the beginning, its activity quickly decreases. However, Pd/ZSM-5 and Pd/SBA-15 show a good stability, without activity loss in a 72 h test. Our research reveals that higher acidity can facilitate catalytic reaction and gives rise to higher activity, but it also enhances coke formation and decreases the catalyst stability. In addition, the porosity of supports has a certain impact on catalytic oxidation of VOCs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900412c Exemplaires
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Titre : Phase diagram for the NH4NO3 + NaVO3 + NH4VO3 + NaNO3 + H2O System at 293 and 303 K Type de document : texte imprimé Auteurs : Mieczyslaw Trypuc, Auteur ; Sebastian Druzynski, Auteur Année de publication : 2009 Article en page(s) : pp. 6937–6942 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solubility isotherms NH4NO3 system NaVO3 NH4VO3 NaNO3 H2O Résumé : The solubility isotherms were determined for the NH4NO3 + NaVO3 + NH4VO3 + NaNO3 + H2O system at 293 and 303 K. Based on these isotherms, the maximum yields have been determined for the conversion of ammonium nitrate to ammonium meta-vanadate. The location of the triple points P1 and P2 has been determined on the equilibrium plots prepared as the planar projection, according to the Jänecke method. The results are necessary for determining the optimal conditions for utilization of post-filtration lye obtained from the soda−chloride−saltpeter (SCS) method of soda ash production. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004139
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6937–6942[article] Phase diagram for the NH4NO3 + NaVO3 + NH4VO3 + NaNO3 + H2O System at 293 and 303 K [texte imprimé] / Mieczyslaw Trypuc, Auteur ; Sebastian Druzynski, Auteur . - 2009 . - pp. 6937–6942.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6937–6942
Mots-clés : Solubility isotherms NH4NO3 system NaVO3 NH4VO3 NaNO3 H2O Résumé : The solubility isotherms were determined for the NH4NO3 + NaVO3 + NH4VO3 + NaNO3 + H2O system at 293 and 303 K. Based on these isotherms, the maximum yields have been determined for the conversion of ammonium nitrate to ammonium meta-vanadate. The location of the triple points P1 and P2 has been determined on the equilibrium plots prepared as the planar projection, according to the Jänecke method. The results are necessary for determining the optimal conditions for utilization of post-filtration lye obtained from the soda−chloride−saltpeter (SCS) method of soda ash production. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004139 Exemplaires
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Titre : Fractionation of poly(vinyl methyl ether) : comparison of two large-scale fractionation techniques Type de document : texte imprimé Auteurs : Simona Morariu, Auteur ; John Eckelt, Auteur ; Bernhard A. Wolf, Auteur Année de publication : 2009 Article en page(s) : pp. 6943–6948 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Continuous polymer fractionation spin Poly(vinyl methyl ether) Résumé : The efficiencies of two large-scale fractionation techniques namely continuous polymer fractionation (CPF) and continuous spin fractionation (CSF) are compared. To this end, we used a commercially available sample of poly(vinyl methyl ether). Both methods are suitable to reduce the nonuniformity of the sample below 0.6. The results demonstrate that CSF has a better fractionation performance than the progenitor method, CPF. A further advantage is the three times higher throughput of CSF. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900484g
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6943–6948[article] Fractionation of poly(vinyl methyl ether) : comparison of two large-scale fractionation techniques [texte imprimé] / Simona Morariu, Auteur ; John Eckelt, Auteur ; Bernhard A. Wolf, Auteur . - 2009 . - pp. 6943–6948.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6943–6948
Mots-clés : Continuous polymer fractionation spin Poly(vinyl methyl ether) Résumé : The efficiencies of two large-scale fractionation techniques namely continuous polymer fractionation (CPF) and continuous spin fractionation (CSF) are compared. To this end, we used a commercially available sample of poly(vinyl methyl ether). Both methods are suitable to reduce the nonuniformity of the sample below 0.6. The results demonstrate that CSF has a better fractionation performance than the progenitor method, CPF. A further advantage is the three times higher throughput of CSF. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900484g Exemplaires
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Titre : Synthesis of glycerol 1-monooleate by condensation of oleic acid with glycidol catalyzed by anion-exchange resin in aqueous organic polymorphic system Type de document : texte imprimé Auteurs : Zéphirin Mouloungui, Auteur ; Vony Rakotondrazafy, Auteur ; Romain Valentin, Auteur Année de publication : 2009 Article en page(s) : pp. 6949–6956 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Technical-grade oleic acid Glycidol Macroporous anion-exchange resin Résumé : The condensation of technical-grade oleic acid (OA) (65%, 85%, and 90% oleic acid) with glycidol (Gly) was carried out in an aqueous medium in the presence of a macroporous anion-exchange resin containing ammonium groups. The reaction was optimized by a unifactorial method and by a 2n−1 fractional factorial plan. The effects of the following main parameters were quantified from experiments based on a 2(5−1) = 24 factorial design: OA/Gly molar ratio, concentration (mmol of OA/mL of H2O), catalytic efficiency (mequiv of X/mmol of OA), and temperature. The conditions were optimized for a discontinuous process in a stirred reactor for selective synthesis of glycerol 1-monooleate (1-GMO) in a polymorphic system (solid resin/emulsion or microemulsion) consisting of OA/Gly/H2O/1-GMO. The catalytic role of the Ambersep 900−X resin was demonstrated by conducting the reaction using the resin in the different functional forms Ambersep 900−OH− and Ambersep 900−HCO3− and in the nonfunctionalized form Ambersep 900−Cl−. The highest yield of 1-GMO (97%) was obtained with the nonfunctionalized form Ambersep 900−Cl− at 70 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900101k
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6949–6956[article] Synthesis of glycerol 1-monooleate by condensation of oleic acid with glycidol catalyzed by anion-exchange resin in aqueous organic polymorphic system [texte imprimé] / Zéphirin Mouloungui, Auteur ; Vony Rakotondrazafy, Auteur ; Romain Valentin, Auteur . - 2009 . - pp. 6949–6956.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6949–6956
Mots-clés : Technical-grade oleic acid Glycidol Macroporous anion-exchange resin Résumé : The condensation of technical-grade oleic acid (OA) (65%, 85%, and 90% oleic acid) with glycidol (Gly) was carried out in an aqueous medium in the presence of a macroporous anion-exchange resin containing ammonium groups. The reaction was optimized by a unifactorial method and by a 2n−1 fractional factorial plan. The effects of the following main parameters were quantified from experiments based on a 2(5−1) = 24 factorial design: OA/Gly molar ratio, concentration (mmol of OA/mL of H2O), catalytic efficiency (mequiv of X/mmol of OA), and temperature. The conditions were optimized for a discontinuous process in a stirred reactor for selective synthesis of glycerol 1-monooleate (1-GMO) in a polymorphic system (solid resin/emulsion or microemulsion) consisting of OA/Gly/H2O/1-GMO. The catalytic role of the Ambersep 900−X resin was demonstrated by conducting the reaction using the resin in the different functional forms Ambersep 900−OH− and Ambersep 900−HCO3− and in the nonfunctionalized form Ambersep 900−Cl−. The highest yield of 1-GMO (97%) was obtained with the nonfunctionalized form Ambersep 900−Cl− at 70 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900101k Exemplaires
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Titre : Study of the lipase-catalyzed esterification of stearic acid by glycerol using in-line near-infrared spectroscopy Type de document : texte imprimé Auteurs : Marcelo Blanco, Auteur ; David Zamora, Auteur Année de publication : 2009 Article en page(s) : pp. 6957–6960 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Near-infrared spectroscopy Stearic acid Heterogeneous catalyst Résumé : The potential of near-infrared (NIR) spectroscopy for monitoring the esterification of stearic acid by glycerol in a laboratory reactor was assessed. The reaction was conducted in the presence of a heterogeneous catalyst that consisted of lipase from Candida antarctica immobilized on a macroporous resin (Novozyme 435). The reaction leads to a produce a mixture of monostearate and especially distearate; no formation of tristearate occurs. The process was monitored using a fiber-optic probe to record NIR spectra for the reaction mixture at variable times. The spectra thus obtained were used to construct and validate PLS calibration models for predicting the glycerin, stearic acid, and glycerol monostearate and distearate concentrations. The ensuing method allows concentration changes in the four compounds to be monitored in real time. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900406x
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6957–6960[article] Study of the lipase-catalyzed esterification of stearic acid by glycerol using in-line near-infrared spectroscopy [texte imprimé] / Marcelo Blanco, Auteur ; David Zamora, Auteur . - 2009 . - pp. 6957–6960.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6957–6960
Mots-clés : Near-infrared spectroscopy Stearic acid Heterogeneous catalyst Résumé : The potential of near-infrared (NIR) spectroscopy for monitoring the esterification of stearic acid by glycerol in a laboratory reactor was assessed. The reaction was conducted in the presence of a heterogeneous catalyst that consisted of lipase from Candida antarctica immobilized on a macroporous resin (Novozyme 435). The reaction leads to a produce a mixture of monostearate and especially distearate; no formation of tristearate occurs. The process was monitored using a fiber-optic probe to record NIR spectra for the reaction mixture at variable times. The spectra thus obtained were used to construct and validate PLS calibration models for predicting the glycerin, stearic acid, and glycerol monostearate and distearate concentrations. The ensuing method allows concentration changes in the four compounds to be monitored in real time. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900406x Exemplaires
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Titre : Carbonyl groups in sulfonated styrene-divinylbenzene macroporous resins Type de document : texte imprimé Auteurs : Muhammad Arif Malik, Auteur Année de publication : 2009 Article en page(s) : pp. 6961–6965 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbonyl groups Porous styrene− divinylbenzene copolymers Sulfonation Résumé : The generation of carbonyl groups during sulfonation of porous styrene−divinylbenzene copolymers is reported. The carbonyl groups and sulfonic acid groups were verified by infrared spectroscopy and quantified by acid−base titrations. A gradual change in sulfonation reaction conditions from 70 °C/30 min to 98 °C/60 min resulted in a gradual increase in sulfonic acid group concentration from ∼1.85 to ∼3.13 mol/kg and in the carboxylic acid group concentration from ∼0 to ∼0.34 mol/kg. Data on the swelling coefficients in water indicate a slight increase in cross-linking during sulfonation. Conversion of ethyl or residual vinyl groups to carboxylic acid groups, followed by conversion of some of the acid groups to cross-links through an acid-catalyzed acylation reaction, is proposed. The proposed reactions also explain the pH-dependent color change of the resins. Sulfonation of copolymers with varied cross-linkages further supports our assertion that, as the concentrations of ethyl and residual vinyl groups increase, the concentration of —COOH groups also increases and the resin color becomes darker. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900681n
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6961–6965[article] Carbonyl groups in sulfonated styrene-divinylbenzene macroporous resins [texte imprimé] / Muhammad Arif Malik, Auteur . - 2009 . - pp. 6961–6965.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6961–6965
Mots-clés : Carbonyl groups Porous styrene− divinylbenzene copolymers Sulfonation Résumé : The generation of carbonyl groups during sulfonation of porous styrene−divinylbenzene copolymers is reported. The carbonyl groups and sulfonic acid groups were verified by infrared spectroscopy and quantified by acid−base titrations. A gradual change in sulfonation reaction conditions from 70 °C/30 min to 98 °C/60 min resulted in a gradual increase in sulfonic acid group concentration from ∼1.85 to ∼3.13 mol/kg and in the carboxylic acid group concentration from ∼0 to ∼0.34 mol/kg. Data on the swelling coefficients in water indicate a slight increase in cross-linking during sulfonation. Conversion of ethyl or residual vinyl groups to carboxylic acid groups, followed by conversion of some of the acid groups to cross-links through an acid-catalyzed acylation reaction, is proposed. The proposed reactions also explain the pH-dependent color change of the resins. Sulfonation of copolymers with varied cross-linkages further supports our assertion that, as the concentrations of ethyl and residual vinyl groups increase, the concentration of —COOH groups also increases and the resin color becomes darker. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900681n Exemplaires
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Titre : Modeling study of the sorption-enhanced reaction process for CO2 capture. I. model development and validation Type de document : texte imprimé Auteurs : Hendricus Th. J. Reijers, Auteur ; Jurriaan Boon, Auteur ; Gerard D. Elzinga, Auteur Année de publication : 2009 Article en page(s) : pp. 6966–69740 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : One-dimensional reactor model Sorption-enhanced steam-methane reforming Water− gas shift Résumé : A one-dimensional reactor model has been developed to describe the performance of a sorption-enhanced steam-methane reforming and water−gas shift reactor. In part I of this paper, the model is verified using the analytical solution for the breakthrough curve and validated using the results of laboratory-scale CO2 sorption-only experiments. Langmuir and Freundlich isotherms are fitted to an experimentally derived adsorption isotherm, while a linear driving force model is used to describe the sorption kinetics. The breakthrough profile is accurately described using the Freundlich isotherm. This holds also when the purge flow or duration of the desorption step are decreased, provided the mass transfer coefficient is changed accordingly during the desorption step. A sensitivity analysis shows that the breakthrough profile is sensitive to the adopted isotherm model and its parameters. The molecular diffusion coefficient affects the slope of the breakthrough curve, while particle size and heat of adsorption show hardly any effect. In part II, the model will be applied to laboratory-scale sorption-enhanced steam-methane reforming experiments. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801319q
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6966–69740[article] Modeling study of the sorption-enhanced reaction process for CO2 capture. I. model development and validation [texte imprimé] / Hendricus Th. J. Reijers, Auteur ; Jurriaan Boon, Auteur ; Gerard D. Elzinga, Auteur . - 2009 . - pp. 6966–69740.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6966–69740
Mots-clés : One-dimensional reactor model Sorption-enhanced steam-methane reforming Water− gas shift Résumé : A one-dimensional reactor model has been developed to describe the performance of a sorption-enhanced steam-methane reforming and water−gas shift reactor. In part I of this paper, the model is verified using the analytical solution for the breakthrough curve and validated using the results of laboratory-scale CO2 sorption-only experiments. Langmuir and Freundlich isotherms are fitted to an experimentally derived adsorption isotherm, while a linear driving force model is used to describe the sorption kinetics. The breakthrough profile is accurately described using the Freundlich isotherm. This holds also when the purge flow or duration of the desorption step are decreased, provided the mass transfer coefficient is changed accordingly during the desorption step. A sensitivity analysis shows that the breakthrough profile is sensitive to the adopted isotherm model and its parameters. The molecular diffusion coefficient affects the slope of the breakthrough curve, while particle size and heat of adsorption show hardly any effect. In part II, the model will be applied to laboratory-scale sorption-enhanced steam-methane reforming experiments. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801319q Exemplaires
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Titre : Modeling study of the sorption-enhanced reaction process for CO2 capture. II. application to steam-methane reforming Type de document : texte imprimé Auteurs : Hendricus Th. J. Reijers, Auteur ; Jurriaan Boon, Auteur ; Gerard D. Elzinga, Auteur Année de publication : 2009 Article en page(s) : pp. 6975–6982 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Reactor model Sorption-enhanced reaction process Steam-methane reforming Résumé : In this paper, the reactor model introduced in part I will be verified using the results of an analytical solution for the increase of CH4 conversion over the bed and validated using the results of sorption-enhanced steam-methane reforming laboratory-scale experiments. An experimentally derived rate equation for the steam-methane reforming reaction is used, a literature rate equation for the water−gas shift reaction. An overview of modeling work on the sorption-enhanced reaction process for steam-methane reforming performed by other groups is presented. The CH4 and CO2 profiles obtained from laboratory-scale experiments are quite satisfactorily described using a Freundlich isotherm. A sensitivity analysis shows that both the CH4 and CO2 profiles are sensitive to the adopted isotherm model and its parameters. In addition to that, the CH4 and CO2 profiles are sensitive to the diffusion coefficient. Neither profile is sensitive to the particle size or the heat of adsorption. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013204
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6975–6982[article] Modeling study of the sorption-enhanced reaction process for CO2 capture. II. application to steam-methane reforming [texte imprimé] / Hendricus Th. J. Reijers, Auteur ; Jurriaan Boon, Auteur ; Gerard D. Elzinga, Auteur . - 2009 . - pp. 6975–6982.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6975–6982
Mots-clés : Reactor model Sorption-enhanced reaction process Steam-methane reforming Résumé : In this paper, the reactor model introduced in part I will be verified using the results of an analytical solution for the increase of CH4 conversion over the bed and validated using the results of sorption-enhanced steam-methane reforming laboratory-scale experiments. An experimentally derived rate equation for the steam-methane reforming reaction is used, a literature rate equation for the water−gas shift reaction. An overview of modeling work on the sorption-enhanced reaction process for steam-methane reforming performed by other groups is presented. The CH4 and CO2 profiles obtained from laboratory-scale experiments are quite satisfactorily described using a Freundlich isotherm. A sensitivity analysis shows that both the CH4 and CO2 profiles are sensitive to the adopted isotherm model and its parameters. In addition to that, the CH4 and CO2 profiles are sensitive to the diffusion coefficient. Neither profile is sensitive to the particle size or the heat of adsorption. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013204 Exemplaires
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Titre : Dynamic simulation of gas hydrate formation in a three- phase slurry reactor Type de document : texte imprimé Auteurs : Shahrzad Hashemi, Auteur ; Arturo Macchi, Auteur ; Phillip Servio, Auteur Année de publication : 2009 Article en page(s) : pp. 6983–6991 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Dynamic hydrate formation model Interphase heat and mass transfer rates System hydrodynamics Résumé : A dynamic hydrate formation model that incorporates growth kinetics as well as system hydrodynamics and interphase heat and mass transfer rates is presented. Supersaturation ratios and gas consumption rates were evaluated as a function of time for different gas and liquid superficial velocities. The effects of temperature and pressure were also investigated based on available kinetic information in the literature. Finally, the influence of interphase mass transfer resistance relative to kinetic resistance was also discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801674e
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6983–6991[article] Dynamic simulation of gas hydrate formation in a three- phase slurry reactor [texte imprimé] / Shahrzad Hashemi, Auteur ; Arturo Macchi, Auteur ; Phillip Servio, Auteur . - 2009 . - pp. 6983–6991.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6983–6991
Mots-clés : Dynamic hydrate formation model Interphase heat and mass transfer rates System hydrodynamics Résumé : A dynamic hydrate formation model that incorporates growth kinetics as well as system hydrodynamics and interphase heat and mass transfer rates is presented. Supersaturation ratios and gas consumption rates were evaluated as a function of time for different gas and liquid superficial velocities. The effects of temperature and pressure were also investigated based on available kinetic information in the literature. Finally, the influence of interphase mass transfer resistance relative to kinetic resistance was also discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801674e Exemplaires
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Titre : CFD modeling of nucleation, growth, aggregation, and breakage in continuous precipitation of barium sulfate in a stirred tank Type de document : texte imprimé Auteurs : Jingcai Cheng, Auteur ; Chao Yang, Auteur ; Zai-Sha Mao, Auteur Année de publication : 2009 Article en page(s) : pp. 6992–7003 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Barium sulfate (BaSO4) Continuous stirred tank reactor Single-phase Reynolds Navier− Stokes equations Résumé : In this work, the precipitation of barium sulfate (BaSO4) in a continuous stirred tank reactor (CSTR) is modeled. The flow field is obtained through solving the single-phase Reynolds averaged Navier−Stokes equations with a standard single-phase k−ε turbulence model. The population balance equation is solved through the standard method of moments (SMM) and the quadrature method of moments (QMOM) both with and without aggregation and breakage terms. In the cases of precipitation simulation without aggregation and breakage, the results predicted from 2-node QMOM, 3-node QMOM, and SMM are very close. Thus, 2-node QMOM could replace SMM and be well-incorporated into an in-house CFD code to simulate the precipitation in CSTR with acceptable accuracy. The predicted area-averaged crystal size d32 decreases almost linearly with increasing feed concentration, and the deviation from experimental data becomes significant at high feed concentration. Numerical simulation using 2-node QMOM with the Brownian motion and shear-induced aggregation kernels as well as a power-law breakage kernel indicates that the predicted d32 shows good qualitative agreement with experimental results, and the quantitative agreement is achieved when the appropriate breakage rate equation is adopted. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004282
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6992–7003[article] CFD modeling of nucleation, growth, aggregation, and breakage in continuous precipitation of barium sulfate in a stirred tank [texte imprimé] / Jingcai Cheng, Auteur ; Chao Yang, Auteur ; Zai-Sha Mao, Auteur . - 2009 . - pp. 6992–7003.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6992–7003
Mots-clés : Barium sulfate (BaSO4) Continuous stirred tank reactor Single-phase Reynolds Navier− Stokes equations Résumé : In this work, the precipitation of barium sulfate (BaSO4) in a continuous stirred tank reactor (CSTR) is modeled. The flow field is obtained through solving the single-phase Reynolds averaged Navier−Stokes equations with a standard single-phase k−ε turbulence model. The population balance equation is solved through the standard method of moments (SMM) and the quadrature method of moments (QMOM) both with and without aggregation and breakage terms. In the cases of precipitation simulation without aggregation and breakage, the results predicted from 2-node QMOM, 3-node QMOM, and SMM are very close. Thus, 2-node QMOM could replace SMM and be well-incorporated into an in-house CFD code to simulate the precipitation in CSTR with acceptable accuracy. The predicted area-averaged crystal size d32 decreases almost linearly with increasing feed concentration, and the deviation from experimental data becomes significant at high feed concentration. Numerical simulation using 2-node QMOM with the Brownian motion and shear-induced aggregation kernels as well as a power-law breakage kernel indicates that the predicted d32 shows good qualitative agreement with experimental results, and the quantitative agreement is achieved when the appropriate breakage rate equation is adopted. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004282 Exemplaires
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Titre : Effect of distributor design on the bottom zone hydrodynamics in a fluidized bed dryer using 1-D X-ray densitometry imaging Type de document : texte imprimé Auteurs : Michael Wormsbecker, Auteur ; Todd Pugsley, Auteur ; J. Ruud van Ommen, Auteur Année de publication : 2009 Article en page(s) : pp. 7004–7015 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fluidized-bed dryer Porous plate distributors One-dimensional X-ray densitometry imaging Résumé : The hydrodynamics near the base of a 15 cm i.d. fluidized-bed dryer having perforated, punched, and porous plate distributors have been studied using one-dimensional X-ray densitometry imaging. The time-averaged solids concentration profiles of dry pharmaceutical granule and wet granule undergoing drying were compared. The porous plate creates good gas distribution over the bed cross section with dry granule but results in defluidization at the distributor level when the granule is wet. The perforated and punched plates exhibit different solids concentration profiles with dry granule; however, the presence of moisture results in similar hydrodynamics between the plates during drying. Standard deviation analysis of the high-frequency solids concentration data was used to corroborate the results of the time-averaged solids concentration measurements. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900025n
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7004–7015[article] Effect of distributor design on the bottom zone hydrodynamics in a fluidized bed dryer using 1-D X-ray densitometry imaging [texte imprimé] / Michael Wormsbecker, Auteur ; Todd Pugsley, Auteur ; J. Ruud van Ommen, Auteur . - 2009 . - pp. 7004–7015.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7004–7015
Mots-clés : Fluidized-bed dryer Porous plate distributors One-dimensional X-ray densitometry imaging Résumé : The hydrodynamics near the base of a 15 cm i.d. fluidized-bed dryer having perforated, punched, and porous plate distributors have been studied using one-dimensional X-ray densitometry imaging. The time-averaged solids concentration profiles of dry pharmaceutical granule and wet granule undergoing drying were compared. The porous plate creates good gas distribution over the bed cross section with dry granule but results in defluidization at the distributor level when the granule is wet. The perforated and punched plates exhibit different solids concentration profiles with dry granule; however, the presence of moisture results in similar hydrodynamics between the plates during drying. Standard deviation analysis of the high-frequency solids concentration data was used to corroborate the results of the time-averaged solids concentration measurements. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900025n Exemplaires
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Titre : Performance of a novel synthetic Ca-based solid sorbent suitable for desulfurizing flue gases in a fluidized bed Type de document : texte imprimé Auteurs : Roberta Pacciani, Auteur ; Christoph R. Müller, Auteur ; John F. Davidson, Auteur Année de publication : 2009 Article en page(s) : pp. 7016–7024 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Dolomite Limestone Carbonation Sulfation Résumé : The extent and mechanism of sulfation and carbonation of limestone, dolomite, and chalk, were compared with a novel, synthetic sorbent (85 wt % CaO and 15 wt % Ca12Al14O33), by means of experiments undertaken in a small, electrically heated fluidized bed. The sorbent particles were used either (i) untreated, sieved to two particle sizes and reacted with two different concentrations of SO2, or (ii) after being cycled 20 times between carbonation, in 15 vol % CO2 in N2, and calcination, in pure N2, at 750 °C. The uptake of untreated limestone and dolomite was generally low (0.5 gSO2/gsorbent) and essentially independent of the particle size. Here, comparisons are made on the basis of the sorbents in the calcined state. Hg-intrusion porosimetry, performed on calcined sorbents, revealed that the pore volume of limestone and dolomite was distributed almost entirely across small pores, which were easily plugged and hindered the diffusion of SO2 through the particle; this was confirmed by EDS analysis. Conversely, the pore size distribution of calcined chalk and fresh synthetic sorbent revealed the presence of pore volume also in the macroporous region; these bigger pores were not prematurely blocked by the newly formed CaSO4 and therefore allowed sulfation to proceed uniformly throughout the particle. It was also found that the uptake of SO2 by limestone, dolomite, and chalk was substantially lower when the particles had been subjected to cycles of calcination and carbonation in CO2 prior to sulfation; this was attributed to the loss in pore volume in the small pores with cycles of carbonation and calcination, as confirmed by Hg-intrusion porosimetry. The uptake of the synthetic sorbent, on the other hand, was much closer to that achieved when the sorbent was used untreated, because its pore volume in large pores was not lost with cycling. The capacities for the uptake of SO2, on a basis of unit mass of calcined sorbent, were comparable for the chalk and the synthetic sorbent. However, previous work has demonstrated the ability of the synthetic sorbent to retain its capacity for CO2 over many cycles of carbonation and calcination: much more so than natural sorbents such as chalk and limestone. Accordingly, the advantage of the synthetic sorbent is that it could be used to remove CO2 from flue gases and, at the end of its life, to remove SO2 on a once-through basis. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900181y
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7016–7024[article] Performance of a novel synthetic Ca-based solid sorbent suitable for desulfurizing flue gases in a fluidized bed [texte imprimé] / Roberta Pacciani, Auteur ; Christoph R. Müller, Auteur ; John F. Davidson, Auteur . - 2009 . - pp. 7016–7024.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7016–7024
Mots-clés : Dolomite Limestone Carbonation Sulfation Résumé : The extent and mechanism of sulfation and carbonation of limestone, dolomite, and chalk, were compared with a novel, synthetic sorbent (85 wt % CaO and 15 wt % Ca12Al14O33), by means of experiments undertaken in a small, electrically heated fluidized bed. The sorbent particles were used either (i) untreated, sieved to two particle sizes and reacted with two different concentrations of SO2, or (ii) after being cycled 20 times between carbonation, in 15 vol % CO2 in N2, and calcination, in pure N2, at 750 °C. The uptake of untreated limestone and dolomite was generally low (0.5 gSO2/gsorbent) and essentially independent of the particle size. Here, comparisons are made on the basis of the sorbents in the calcined state. Hg-intrusion porosimetry, performed on calcined sorbents, revealed that the pore volume of limestone and dolomite was distributed almost entirely across small pores, which were easily plugged and hindered the diffusion of SO2 through the particle; this was confirmed by EDS analysis. Conversely, the pore size distribution of calcined chalk and fresh synthetic sorbent revealed the presence of pore volume also in the macroporous region; these bigger pores were not prematurely blocked by the newly formed CaSO4 and therefore allowed sulfation to proceed uniformly throughout the particle. It was also found that the uptake of SO2 by limestone, dolomite, and chalk was substantially lower when the particles had been subjected to cycles of calcination and carbonation in CO2 prior to sulfation; this was attributed to the loss in pore volume in the small pores with cycles of carbonation and calcination, as confirmed by Hg-intrusion porosimetry. The uptake of the synthetic sorbent, on the other hand, was much closer to that achieved when the sorbent was used untreated, because its pore volume in large pores was not lost with cycling. The capacities for the uptake of SO2, on a basis of unit mass of calcined sorbent, were comparable for the chalk and the synthetic sorbent. However, previous work has demonstrated the ability of the synthetic sorbent to retain its capacity for CO2 over many cycles of carbonation and calcination: much more so than natural sorbents such as chalk and limestone. Accordingly, the advantage of the synthetic sorbent is that it could be used to remove CO2 from flue gases and, at the end of its life, to remove SO2 on a once-through basis. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900181y Exemplaires
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Titre : Kinetic and mechanistic investigations of oxidation of pentoxifylline drug by alkaline permanganate Type de document : texte imprimé Auteurs : Rajesh N. Hegde, Auteur ; Nagaraj P. Shetti, Auteur ; Sharanappa T. Nandibewoor, Auteur Année de publication : 2009 Article en page(s) : pp. 7025–7031 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hemorheologic drug Pentoxifylline Alkaline permanganate Résumé : The kinetics of oxidation of a hemorheologic drug, pentoxifylline by permanganate in alkaline medium at a constant ionic strength of 0.10 mol dm−3 was studied spectrophotometrically using a rapid kinetic HI-TECH SFA-12 accessory. The reaction between permanganate and pentoxifylline in alkaline medium exhibits 1:2 stoichiometry (pentoxifylline/permanganate). The reaction is of first order in [permanganate ion] and less than unit order dependence each in [PTX] and [OH−]. However, the orders in [PTX] and [OH−] changes from first order to zero order as their concentrations increase. A decrease in the dielectric constant of the medium increases the rate of the reaction. The effect of added products and ionic strength of the reaction medium have been investigated. The oxidation reaction in alkaline medium has been shown to proceed via a permanganate-pentoxifylline complex, which decomposes slowly in a rate-determining step followed by a fast step to give the products. A suitable mechanism is proposed. The main products were identified by TLC and spectral studies including LC−MS. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed and thermodynamic quantities are also determined. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004145
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7025–7031[article] Kinetic and mechanistic investigations of oxidation of pentoxifylline drug by alkaline permanganate [texte imprimé] / Rajesh N. Hegde, Auteur ; Nagaraj P. Shetti, Auteur ; Sharanappa T. Nandibewoor, Auteur . - 2009 . - pp. 7025–7031.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7025–7031
Mots-clés : Hemorheologic drug Pentoxifylline Alkaline permanganate Résumé : The kinetics of oxidation of a hemorheologic drug, pentoxifylline by permanganate in alkaline medium at a constant ionic strength of 0.10 mol dm−3 was studied spectrophotometrically using a rapid kinetic HI-TECH SFA-12 accessory. The reaction between permanganate and pentoxifylline in alkaline medium exhibits 1:2 stoichiometry (pentoxifylline/permanganate). The reaction is of first order in [permanganate ion] and less than unit order dependence each in [PTX] and [OH−]. However, the orders in [PTX] and [OH−] changes from first order to zero order as their concentrations increase. A decrease in the dielectric constant of the medium increases the rate of the reaction. The effect of added products and ionic strength of the reaction medium have been investigated. The oxidation reaction in alkaline medium has been shown to proceed via a permanganate-pentoxifylline complex, which decomposes slowly in a rate-determining step followed by a fast step to give the products. A suitable mechanism is proposed. The main products were identified by TLC and spectral studies including LC−MS. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed and thermodynamic quantities are also determined. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004145 Exemplaires
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Titre : Production of (S)-1-benzyl-3-diazo-2-oxopropylcarbamic acid tert-butyl ester, a diazoketone pharmaceutical intermediate, employing a small scale continuous reactor Type de document : texte imprimé Auteurs : Pamela Pollet, Auteur ; Elizabeth D. Cope, Auteur ; Michelle K. Kassner, Auteur Année de publication : 2009 Article en page(s) : pp. 7032–7036 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : N-Boc-(1S)-benzylhydroxy-3-chloropropylamine Small scale continuous reactor Résumé : N-Boc-(1S)-benzylhydroxy-3-chloropropylamine (6) is a precursor to pharmaceutically active compounds that act as human immunodeficiency virus (HIV) protease inhibitors. It is currently being produced via a batch process which includes a homologation step with diazomethane. This article considers the challenges faced when converting a traditional batch process to a continuous flow system for the production of the key intermediate (S)-1-benzyl-3-diazo-2-oxopropylcarbamic acid tert-butyl ester (4). A continuous flow reactor was designed, built, and used to carry out a two step reaction sequence: the formation of a temperature sensitive mixed anhydride intermediate (3) and the subsequent reaction of that intermediate (3) with trimethylsilyldiazomethane (8) to yield the diazoketone intermediate (4). By modifying the chemistry and maximizing the mixing and heat transfer, the batch process was successfully converted to a continuous flow process. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801885y
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7032–7036[article] Production of (S)-1-benzyl-3-diazo-2-oxopropylcarbamic acid tert-butyl ester, a diazoketone pharmaceutical intermediate, employing a small scale continuous reactor [texte imprimé] / Pamela Pollet, Auteur ; Elizabeth D. Cope, Auteur ; Michelle K. Kassner, Auteur . - 2009 . - pp. 7032–7036.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7032–7036
Mots-clés : N-Boc-(1S)-benzylhydroxy-3-chloropropylamine Small scale continuous reactor Résumé : N-Boc-(1S)-benzylhydroxy-3-chloropropylamine (6) is a precursor to pharmaceutically active compounds that act as human immunodeficiency virus (HIV) protease inhibitors. It is currently being produced via a batch process which includes a homologation step with diazomethane. This article considers the challenges faced when converting a traditional batch process to a continuous flow system for the production of the key intermediate (S)-1-benzyl-3-diazo-2-oxopropylcarbamic acid tert-butyl ester (4). A continuous flow reactor was designed, built, and used to carry out a two step reaction sequence: the formation of a temperature sensitive mixed anhydride intermediate (3) and the subsequent reaction of that intermediate (3) with trimethylsilyldiazomethane (8) to yield the diazoketone intermediate (4). By modifying the chemistry and maximizing the mixing and heat transfer, the batch process was successfully converted to a continuous flow process. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801885y Exemplaires
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Titre : Hydrogenation of p-chloronitrobenzene over mo-modified NiCoB nanoalloy catalysts : effect of Mo content Type de document : texte imprimé Auteurs : Ming-Hung Lin, Auteur ; Bin Zhao, Auteur ; Chen, Yu-Wen, Auteur Année de publication : 2009 Article en page(s) : pp. 7037–7043 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : p-chloronitrobenzene HydrogenationNiCoB alloy catalyst Résumé : NiCoB alloy catalyst has been reported to be a good catalyst for the hydrogenation of p-chloronitrobenzene to p-chloroaniline. The objective of this study was to investigate the effects of Mo content on the catalytic properties of NiCoB in the hydrogenation of p-chloronitrobenzene. A series of Mo-doped NiCoB nanoalloy catalysts with various Mo contents were prepared by chemically reacting nickel acetate, cobalt acetate, ammonium heptamolybdate, and sodium borohydride in a 50 vol % water/methanol solution at 298 K under an N2 gas curtain with vigorous stirring. The Ni/Co atomic ratio was fixed at 10. An excess amount of NaBH4 was used [B/(Ni + Co) atomic ratio = 3] to fully reduced Ni and Co cations. The catalysts were characterized with nitrogen sorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalysts were tested for liquid-phase hydrogenation of p-chloronitrobenzene at 353 K and 1.2 MPa H2 pressure. Even adding a small amount of Mo had significant effect on activity and selectivity of NiCoB. The activity increased with an increase of Mo content until a Mo/Ni atomic ratio of 0.6 and then decreased. The catalyst with the atomic ratio of Mo/Ni = 0.6 had the highest surface area and the highest activity and selectivity of p-chloroaniline. The particle size of Mo−NiCoB decreased with an increase of Mo content. The crystallization temperature extended upward with the increase in Mo content, indicating that the molybdenum species suppressed the growth of the crystalline structure of NiCoB and helped the NiCoB catalyst maintain its amorphous state. Molybdenum was mainly in the form of hydroxide and acted as a spacer to prevent NiCoB from aggregation/agglomeration. Adding the proper amount of molybdenum in NiCoB catalysts increased the surface area, activity, and selectivity. An overdose of molybdenum had an opposite effect on the NiCoB catalyst. The optimum atomic ratio of Mo/Ni was 0.6. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900019d
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7037–7043[article] Hydrogenation of p-chloronitrobenzene over mo-modified NiCoB nanoalloy catalysts : effect of Mo content [texte imprimé] / Ming-Hung Lin, Auteur ; Bin Zhao, Auteur ; Chen, Yu-Wen, Auteur . - 2009 . - pp. 7037–7043.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7037–7043
Mots-clés : p-chloronitrobenzene HydrogenationNiCoB alloy catalyst Résumé : NiCoB alloy catalyst has been reported to be a good catalyst for the hydrogenation of p-chloronitrobenzene to p-chloroaniline. The objective of this study was to investigate the effects of Mo content on the catalytic properties of NiCoB in the hydrogenation of p-chloronitrobenzene. A series of Mo-doped NiCoB nanoalloy catalysts with various Mo contents were prepared by chemically reacting nickel acetate, cobalt acetate, ammonium heptamolybdate, and sodium borohydride in a 50 vol % water/methanol solution at 298 K under an N2 gas curtain with vigorous stirring. The Ni/Co atomic ratio was fixed at 10. An excess amount of NaBH4 was used [B/(Ni + Co) atomic ratio = 3] to fully reduced Ni and Co cations. The catalysts were characterized with nitrogen sorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalysts were tested for liquid-phase hydrogenation of p-chloronitrobenzene at 353 K and 1.2 MPa H2 pressure. Even adding a small amount of Mo had significant effect on activity and selectivity of NiCoB. The activity increased with an increase of Mo content until a Mo/Ni atomic ratio of 0.6 and then decreased. The catalyst with the atomic ratio of Mo/Ni = 0.6 had the highest surface area and the highest activity and selectivity of p-chloroaniline. The particle size of Mo−NiCoB decreased with an increase of Mo content. The crystallization temperature extended upward with the increase in Mo content, indicating that the molybdenum species suppressed the growth of the crystalline structure of NiCoB and helped the NiCoB catalyst maintain its amorphous state. Molybdenum was mainly in the form of hydroxide and acted as a spacer to prevent NiCoB from aggregation/agglomeration. Adding the proper amount of molybdenum in NiCoB catalysts increased the surface area, activity, and selectivity. An overdose of molybdenum had an opposite effect on the NiCoB catalyst. The optimum atomic ratio of Mo/Ni was 0.6. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900019d Exemplaires
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Titre : Nonisothermal degradation of Zetaplus impression material : kinetic aspects Type de document : texte imprimé Auteurs : Bojan Jankovic, Auteur Année de publication : 2009 Article en page(s) : pp. 7044–7053 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nonisothermal degradation process Zetaplus impression material Thermogravimetric measurements Differential thermal analysis Résumé : Kinetic analysis of the nonisothermal degradation process of Zetaplus impression material has been performed. Kinetic data for the investigated degradation process were obtained from the thermogravimetric (TG) and differential thermal analysis (DTA) measurements conducted at the three different heating rates (β = 10, 20, and 25 °C min−1) in an air atmosphere. For determination of the kinetic model function (f(α) or g(α)), the isoconversional and Master-plot methods were used. It was found that the first degradation stage of Zetaplus impression material can be described by the three-dimensional diffusion (D3) and with the following values of kinetic parameters: Ea = 99.5 kJ mol−1 and A = 1.05 × 108 min−1. Kinetic analysis shows that the first degradation stage corresponds to the bond cleavages and polydimethylsiloxane thermal volatilization, which is contolled by the rate of diffusion and evaporation of oligomers produced on decomposition. The observed second degradation step is more complex; it includes two parallel independent reactions with different values of the apparent activation energy. By applying the nonlinear regression (NLR) method, it was found that the second degradation stage can be described by two independent parallel first-order reactions (nth-order reaction model). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900104b
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7044–7053[article] Nonisothermal degradation of Zetaplus impression material : kinetic aspects [texte imprimé] / Bojan Jankovic, Auteur . - 2009 . - pp. 7044–7053.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7044–7053
Mots-clés : Nonisothermal degradation process Zetaplus impression material Thermogravimetric measurements Differential thermal analysis Résumé : Kinetic analysis of the nonisothermal degradation process of Zetaplus impression material has been performed. Kinetic data for the investigated degradation process were obtained from the thermogravimetric (TG) and differential thermal analysis (DTA) measurements conducted at the three different heating rates (β = 10, 20, and 25 °C min−1) in an air atmosphere. For determination of the kinetic model function (f(α) or g(α)), the isoconversional and Master-plot methods were used. It was found that the first degradation stage of Zetaplus impression material can be described by the three-dimensional diffusion (D3) and with the following values of kinetic parameters: Ea = 99.5 kJ mol−1 and A = 1.05 × 108 min−1. Kinetic analysis shows that the first degradation stage corresponds to the bond cleavages and polydimethylsiloxane thermal volatilization, which is contolled by the rate of diffusion and evaporation of oligomers produced on decomposition. The observed second degradation step is more complex; it includes two parallel independent reactions with different values of the apparent activation energy. By applying the nonlinear regression (NLR) method, it was found that the second degradation stage can be described by two independent parallel first-order reactions (nth-order reaction model). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900104b Exemplaires
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Titre : Advanced bioreduction of commercially important azo dyes : modeling and correlation with electrochemical characteristics Type de document : texte imprimé Auteurs : Gergo Mezohegyi, Auteur ; Azael Fabregat, Auteur ; Josep Font, Auteur Année de publication : 2009 Article en page(s) : pp. 7054–7059 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Anaerobic biodegradability Upflow stirred packed-bed reactors Biological activated carbon Résumé : The anaerobic biodegradability of some commercially important colorants was investigated in upflow stirred packed-bed reactors (USPBR) containing biological activated carbon (BAC) system. Decolorization with very high reduction rates took place in the case of azo dyes. At least 80% of conversion was achieved for these dyes at a space time (τ) of 2.0 min or higher corresponding to a residence time of about 1.8 min at the most. On the contrary, nonazo xanthene dye was not converted in the anaerobic bioreactor system. A simple model was proposed to predict azo dye decolorization involving both heterogeneous catalysis and biological degradation. Adsorption studies for the dyes revealed that their adsorption affinity to activated carbon is not the key factor in the reduction process. Results from voltammetric experiments show that a correlation exists between electrochemical characteristic and anaerobic biodegradability of different azo dyes in the continuous USPBR-BAC catalytic system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9003893
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7054–7059[article] Advanced bioreduction of commercially important azo dyes : modeling and correlation with electrochemical characteristics [texte imprimé] / Gergo Mezohegyi, Auteur ; Azael Fabregat, Auteur ; Josep Font, Auteur . - 2009 . - pp. 7054–7059.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7054–7059
Mots-clés : Anaerobic biodegradability Upflow stirred packed-bed reactors Biological activated carbon Résumé : The anaerobic biodegradability of some commercially important colorants was investigated in upflow stirred packed-bed reactors (USPBR) containing biological activated carbon (BAC) system. Decolorization with very high reduction rates took place in the case of azo dyes. At least 80% of conversion was achieved for these dyes at a space time (τ) of 2.0 min or higher corresponding to a residence time of about 1.8 min at the most. On the contrary, nonazo xanthene dye was not converted in the anaerobic bioreactor system. A simple model was proposed to predict azo dye decolorization involving both heterogeneous catalysis and biological degradation. Adsorption studies for the dyes revealed that their adsorption affinity to activated carbon is not the key factor in the reduction process. Results from voltammetric experiments show that a correlation exists between electrochemical characteristic and anaerobic biodegradability of different azo dyes in the continuous USPBR-BAC catalytic system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9003893 Exemplaires
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Titre : Effect of flow rate of a biphasic reaction mixture on limonene hydrogenation in high pressure CO2 Type de document : texte imprimé Auteurs : Ewa Bogel-Lukasik, Auteur ; Rafal Bogel-lukasik, Auteur ; Manuel Nunes da Ponte, Auteur Année de publication : 2009 Article en page(s) : pp. 7060–7064 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Overall flow rate Biphasic reaction mixture Limonene hydrogenation Résumé : In this work the effect of the overall flow rate of the biphasic reaction mixture on hydrogenation distribution products is reported. As it was already presented by us, the reaction rate strongly correlates with the phase equilibrium existing in the system. On the other hand, carbon dioxide is nonreactive; nevertheless by its presence it changes the energy balance. The catalytic performance in four kinds of overall flow rate conditions (1.3, 3.3, 5.3, and 7.3 mL/min) was compared under fixed hydrogen (2.5 MPa) and total pressure (12.5 MPa). The appearance of isomers of limonene and partially hydrogenated products significantly rely upon the flow rate used in the reaction. The 1% Pd SCN catalyst used in the reaction gave the final products trans- and cis-p-menthane in a 2/3 to 1/3 molar ratio. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900450m
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7060–7064[article] Effect of flow rate of a biphasic reaction mixture on limonene hydrogenation in high pressure CO2 [texte imprimé] / Ewa Bogel-Lukasik, Auteur ; Rafal Bogel-lukasik, Auteur ; Manuel Nunes da Ponte, Auteur . - 2009 . - pp. 7060–7064.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7060–7064
Mots-clés : Overall flow rate Biphasic reaction mixture Limonene hydrogenation Résumé : In this work the effect of the overall flow rate of the biphasic reaction mixture on hydrogenation distribution products is reported. As it was already presented by us, the reaction rate strongly correlates with the phase equilibrium existing in the system. On the other hand, carbon dioxide is nonreactive; nevertheless by its presence it changes the energy balance. The catalytic performance in four kinds of overall flow rate conditions (1.3, 3.3, 5.3, and 7.3 mL/min) was compared under fixed hydrogen (2.5 MPa) and total pressure (12.5 MPa). The appearance of isomers of limonene and partially hydrogenated products significantly rely upon the flow rate used in the reaction. The 1% Pd SCN catalyst used in the reaction gave the final products trans- and cis-p-menthane in a 2/3 to 1/3 molar ratio. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900450m Exemplaires
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Titre : Methanol conversion to dimethyl ether over H-SAPO-34 catalyst Type de document : texte imprimé Auteurs : Grigore Pop, Auteur ; Grigore Bozga, Auteur ; Rodica Lipsa, Auteur Année de publication : 2009 Article en page(s) : pp. 7065–7071 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Methanol conversion Dimethyl ether H-SAPO-34 molecular sieve Catalyst Résumé : The process of methanol conversion to dimethyl ether over an H-SAPO-34 molecular sieve was studied, using the catalyst as synthesized or formulated in an alumina matrix. The experiments were performed on the temperature interval 100−250 °C, liquid space velocities of 1−5 h−1, and pressures between 1 and 10 bar. The results evidenced a high catalytic activity of the H-SAPO-34 molecular sieve, providing in these conditions a practically total methanol transformation to dimethyl ether. Also, a special run, performed at 180 °C, with an output composition close to chemical equilibrium, showed no significant change of catalyst activity during an on-stream time of 50 h, this proving a good stability and resistance to deactivation. A published rate expression for the methanol dehydration reaction was selected and adapted to describe the experimentally observed process kinetics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900532y
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7065–7071[article] Methanol conversion to dimethyl ether over H-SAPO-34 catalyst [texte imprimé] / Grigore Pop, Auteur ; Grigore Bozga, Auteur ; Rodica Lipsa, Auteur . - 2009 . - pp. 7065–7071.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7065–7071
Mots-clés : Methanol conversion Dimethyl ether H-SAPO-34 molecular sieve Catalyst Résumé : The process of methanol conversion to dimethyl ether over an H-SAPO-34 molecular sieve was studied, using the catalyst as synthesized or formulated in an alumina matrix. The experiments were performed on the temperature interval 100−250 °C, liquid space velocities of 1−5 h−1, and pressures between 1 and 10 bar. The results evidenced a high catalytic activity of the H-SAPO-34 molecular sieve, providing in these conditions a practically total methanol transformation to dimethyl ether. Also, a special run, performed at 180 °C, with an output composition close to chemical equilibrium, showed no significant change of catalyst activity during an on-stream time of 50 h, this proving a good stability and resistance to deactivation. A published rate expression for the methanol dehydration reaction was selected and adapted to describe the experimentally observed process kinetics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900532y Exemplaires
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Titre : Activation of hydrogen peroxide by an Fe-TAML complex in strongly alkaline aqueous solution : homogeneous oxidation catalysis with industrial significance Type de document : texte imprimé Auteurs : Evan S. Beach, Auteur ; Jennifer L. Duran, Auteur ; Sujin K. Horwitz, Auteur Année de publication : 2009 Article en page(s) : pp. 7072–7076 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hydrogen peroxide Fe-TAML catalysts Aqueous solutions Résumé : Hydrogen peroxide is activated by homogeneous Fe-TAML catalysts in aqueous solutions containing very high levels of sodium hydroxide, sodium aluminate, and other inorganic salts. Under these conditions, the Fe-TAML catalyst system facilitates oxidation of humic and humic-derived compounds under ambient conditions and efficiently uses catalyst and oxidant. Darkly colored process liquor from aluminum refining (Bayer liquor) is decolorized by 40−70% (in the wavelength range 450−650 nm) in just 5 min. Humic substances and phenolic species were targeted by the oxidation process. In addition to color reduction, Fe-TAML/H2O2 in 5 M NaOH can also extensively degrade the five- or six-carbon polyols, mannitol, sorbitol, dulcitol, xylitol, and adonitol. This is the first time Fe-TAML catalysts have been shown to activate degradation of carbohydrate alcohols. We show that mannitol, a nuisance contaminant in alumina production, can be oxidized at millimolar levels in process liquor containing a wide variety of other organic components at high background concentrations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005723
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7072–7076[article] Activation of hydrogen peroxide by an Fe-TAML complex in strongly alkaline aqueous solution : homogeneous oxidation catalysis with industrial significance [texte imprimé] / Evan S. Beach, Auteur ; Jennifer L. Duran, Auteur ; Sujin K. Horwitz, Auteur . - 2009 . - pp. 7072–7076.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7072–7076
Mots-clés : Hydrogen peroxide Fe-TAML catalysts Aqueous solutions Résumé : Hydrogen peroxide is activated by homogeneous Fe-TAML catalysts in aqueous solutions containing very high levels of sodium hydroxide, sodium aluminate, and other inorganic salts. Under these conditions, the Fe-TAML catalyst system facilitates oxidation of humic and humic-derived compounds under ambient conditions and efficiently uses catalyst and oxidant. Darkly colored process liquor from aluminum refining (Bayer liquor) is decolorized by 40−70% (in the wavelength range 450−650 nm) in just 5 min. Humic substances and phenolic species were targeted by the oxidation process. In addition to color reduction, Fe-TAML/H2O2 in 5 M NaOH can also extensively degrade the five- or six-carbon polyols, mannitol, sorbitol, dulcitol, xylitol, and adonitol. This is the first time Fe-TAML catalysts have been shown to activate degradation of carbohydrate alcohols. We show that mannitol, a nuisance contaminant in alumina production, can be oxidized at millimolar levels in process liquor containing a wide variety of other organic components at high background concentrations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005723 Exemplaires
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Titre : Gelation modification of soy protein isolate by a naturally occurring cross-linking agent and its potential biomedical application Type de document : texte imprimé Auteurs : Fei Song, Auteur ; Li-Ming Zhang, Auteur Année de publication : 2009 Article en page(s) : pp. 7077–7083 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Soy protein isolate Gelation Naturally occurring genipin Résumé : The gelation modification of soy protein isolate (SPI) was carried out in aqueous system using naturally occurring genipin as the cross-linking agent. By means of a controlled-stress rheometer, the time-sweep and frequency-sweep analyses were performed to investigate the gelation kinetics and extent. With the increase of genipin amount, the initial gelation time decreased, and the stability of the cross-linked SPI gel was improved. Moreover, a suitable increase in the reaction temperature was found to be favorable for the gelation of aqueous SPI system in the presence of genipin. FTIR analyses, ninhydrin assays, and SEM observation confirmed the cross-linking reaction between SPI and genipin. By investigating the swelling characteristics and the in vitro release behavior of a model protein drug (bovine serum albumin) in simulated gastric and intestinal media, the resultant SPI gel was found to have a potential biomedical application for site-specific drug delivery in the intestine. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801372f
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7077–7083[article] Gelation modification of soy protein isolate by a naturally occurring cross-linking agent and its potential biomedical application [texte imprimé] / Fei Song, Auteur ; Li-Ming Zhang, Auteur . - 2009 . - pp. 7077–7083.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7077–7083
Mots-clés : Soy protein isolate Gelation Naturally occurring genipin Résumé : The gelation modification of soy protein isolate (SPI) was carried out in aqueous system using naturally occurring genipin as the cross-linking agent. By means of a controlled-stress rheometer, the time-sweep and frequency-sweep analyses were performed to investigate the gelation kinetics and extent. With the increase of genipin amount, the initial gelation time decreased, and the stability of the cross-linked SPI gel was improved. Moreover, a suitable increase in the reaction temperature was found to be favorable for the gelation of aqueous SPI system in the presence of genipin. FTIR analyses, ninhydrin assays, and SEM observation confirmed the cross-linking reaction between SPI and genipin. By investigating the swelling characteristics and the in vitro release behavior of a model protein drug (bovine serum albumin) in simulated gastric and intestinal media, the resultant SPI gel was found to have a potential biomedical application for site-specific drug delivery in the intestine. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801372f Exemplaires
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Titre : Seed-induced crystallization of nanosized Na-ZSM-5 crystals Type de document : texte imprimé Auteurs : Gerardo Majano, Auteur ; Ali Darwiche, Auteur ; Svetlana Mintova, Auteur Année de publication : 2009 Article en page(s) : pp. 7084–7091 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : ZSM-5 nanocrystals Nanosized tetrapropylammonium Seed pretreatment Résumé : ZSM-5 nanocrystals were synthesized from organic-template-free gel systems containing 0.1, 1.0, and 3.0 wt % of 80 nm silicalite-1 seeds. The syntheses were performed at 100, 120, 150, and 170 °C for periods of time ranging between 3 and 190 h. Physicochemical characteristics derived from XRD, NMR, TG/DTA, SEM/TEM, DLS, N2 adsorption and chemical analyses of Na-ZSM-5 nanocrystals were compared with those of the nanosized tetrapropylammonium (TPA)-promoted counterpart. Crystalline yield and colloidal stability of ZSM-5 nanosized materials obtained under different conditions (seed content, crystallization temperature, and time) were also studied. Another issue of interest in the framework of this study was the effect of seed pretreatment (drying, calcination) on the characteristics of crystalline product. Thus, factors controlling seeded growth of nanosized zeolite particles were established and the mechanism of formation, including parameters governing the formation of single or aggregated crystals, revealed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017252
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7084–7091[article] Seed-induced crystallization of nanosized Na-ZSM-5 crystals [texte imprimé] / Gerardo Majano, Auteur ; Ali Darwiche, Auteur ; Svetlana Mintova, Auteur . - 2009 . - pp. 7084–7091.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7084–7091
Mots-clés : ZSM-5 nanocrystals Nanosized tetrapropylammonium Seed pretreatment Résumé : ZSM-5 nanocrystals were synthesized from organic-template-free gel systems containing 0.1, 1.0, and 3.0 wt % of 80 nm silicalite-1 seeds. The syntheses were performed at 100, 120, 150, and 170 °C for periods of time ranging between 3 and 190 h. Physicochemical characteristics derived from XRD, NMR, TG/DTA, SEM/TEM, DLS, N2 adsorption and chemical analyses of Na-ZSM-5 nanocrystals were compared with those of the nanosized tetrapropylammonium (TPA)-promoted counterpart. Crystalline yield and colloidal stability of ZSM-5 nanosized materials obtained under different conditions (seed content, crystallization temperature, and time) were also studied. Another issue of interest in the framework of this study was the effect of seed pretreatment (drying, calcination) on the characteristics of crystalline product. Thus, factors controlling seeded growth of nanosized zeolite particles were established and the mechanism of formation, including parameters governing the formation of single or aggregated crystals, revealed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017252 Exemplaires
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Titre : Determination of water-in-oil emulsion viscosity in porous media Type de document : texte imprimé Auteurs : Mohamed Arhuoma, Auteur ; Mingzhe Dong, Auteur ; Daoyong Yang, Auteur Année de publication : 2009 Article en page(s) : pp. 7092–7102 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Water-in-oil emulsions Porous media Résumé : Experiments have been conducted to determine the viscosities of water-in-oil (W/O) emulsions in porous media. W/O emulsions were first prepared for different volume fractions of the dispersed phase and then characterized for their properties and rheological parameters including flow index and consistency constant. All prepared W/O emulsions with volume fractions between 6.78% and 33.48% were found to behave as non-Newtonian shear-thinning fluids at fairly high viscosities. The viscosities of the emulsions were measured during emulsion flow in three types of sandpacks. A correlation of the viscosities of the W/O emulsions in porous media was developed by performing a regression on the experimentally measured data. The newly developed correlation was validated, and a sensitivity analysis was performed to examine the effects of tortuosity and emulsion quality. The emulsion quality has a dominant effect on the viscosity of the W/O emulsions and has been included in the correlation for the first time to achieve accurate predictions of the viscosities of W/O emulsions in porous media. The existing correlations for oil-in-water (O/W) emulsions provide underestimated predictions for the viscosities of W/O emulsions, whereas the droplet size distribution does not have a significant impact on the viscosity of the W/O emulsions tested in this study. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801818n
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7092–7102[article] Determination of water-in-oil emulsion viscosity in porous media [texte imprimé] / Mohamed Arhuoma, Auteur ; Mingzhe Dong, Auteur ; Daoyong Yang, Auteur . - 2009 . - pp. 7092–7102.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7092–7102
Mots-clés : Water-in-oil emulsions Porous media Résumé : Experiments have been conducted to determine the viscosities of water-in-oil (W/O) emulsions in porous media. W/O emulsions were first prepared for different volume fractions of the dispersed phase and then characterized for their properties and rheological parameters including flow index and consistency constant. All prepared W/O emulsions with volume fractions between 6.78% and 33.48% were found to behave as non-Newtonian shear-thinning fluids at fairly high viscosities. The viscosities of the emulsions were measured during emulsion flow in three types of sandpacks. A correlation of the viscosities of the W/O emulsions in porous media was developed by performing a regression on the experimentally measured data. The newly developed correlation was validated, and a sensitivity analysis was performed to examine the effects of tortuosity and emulsion quality. The emulsion quality has a dominant effect on the viscosity of the W/O emulsions and has been included in the correlation for the first time to achieve accurate predictions of the viscosities of W/O emulsions in porous media. The existing correlations for oil-in-water (O/W) emulsions provide underestimated predictions for the viscosities of W/O emulsions, whereas the droplet size distribution does not have a significant impact on the viscosity of the W/O emulsions tested in this study. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801818n Exemplaires
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Titre : Utilizing polystyrene microspheres as confined space to help TiO2 nanocrystals formation with assistance of supercritical CO2 Type de document : texte imprimé Auteurs : Aping Niu, Auteur ; Yan Li, Auteur ; Jiafu Chen, Auteur Année de publication : 2009 Article en page(s) : pp. 7103–7109 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Titania nanocrystals Tetrabutyl titanate Polystyrene microspheres Résumé : Titania nanocrystals were prepared by a particular way: first, supercritical CO2 (SC CO2) carried precursor tetrabutyl titanate (TBT) into the confined space of polystyrene (PS) microspheres; second, hydrolysis of TBT was controlled by the confined space of PS microspheres, which had a restraining effect on the hydrolysis rate of TBT; finally, TiO2 nanocrystals were obtained by calcining PS@TiO2 composite microspheres. The products obtained after hydrolysis and calcination, that is, PS@TiO2 composite microspheres and the finally obtained TiO2 nanocrystals, were characterized by transmission electron microscope and scanning electron microscope, respectively. Further high-resolution transmission electron microscopy and X-ray diffraction (XRD) indicated that the obtained TiO2 nanocrystals had fine crystalline structure. Additionally, the XRD pattern verified the presence of anatase and rutile in TiO2. The nucleation mechanism of TiO2 nanocrystals in the confined space of PS microspheres was also proposed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900204y
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7103–7109[article] Utilizing polystyrene microspheres as confined space to help TiO2 nanocrystals formation with assistance of supercritical CO2 [texte imprimé] / Aping Niu, Auteur ; Yan Li, Auteur ; Jiafu Chen, Auteur . - 2009 . - pp. 7103–7109.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7103–7109
Mots-clés : Titania nanocrystals Tetrabutyl titanate Polystyrene microspheres Résumé : Titania nanocrystals were prepared by a particular way: first, supercritical CO2 (SC CO2) carried precursor tetrabutyl titanate (TBT) into the confined space of polystyrene (PS) microspheres; second, hydrolysis of TBT was controlled by the confined space of PS microspheres, which had a restraining effect on the hydrolysis rate of TBT; finally, TiO2 nanocrystals were obtained by calcining PS@TiO2 composite microspheres. The products obtained after hydrolysis and calcination, that is, PS@TiO2 composite microspheres and the finally obtained TiO2 nanocrystals, were characterized by transmission electron microscope and scanning electron microscope, respectively. Further high-resolution transmission electron microscopy and X-ray diffraction (XRD) indicated that the obtained TiO2 nanocrystals had fine crystalline structure. Additionally, the XRD pattern verified the presence of anatase and rutile in TiO2. The nucleation mechanism of TiO2 nanocrystals in the confined space of PS microspheres was also proposed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900204y Exemplaires
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Titre : Porous carbon obtained by carbonization of PET mixed with basic magnesium carbonate : pore structure and pore creation mechanism Type de document : texte imprimé Auteurs : Jacek Przepiórski, Auteur ; Justyna Karolczyk, Auteur ; Kazuhiro Takeda, Auteur Année de publication : 2009 Article en page(s) : pp. 7110–7116 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Porous carbon PET [poly(ethylene terephtalate)]Magnesium carbonate mixture Gas flow Résumé : Porous carbon materials were prepared by heating of a PET [poly(ethylene terephtalate)] and magnesium carbonate (3MgCO3·Mg(OH)2·3H2O) mixture under Ar gas flow, followed by acid washing. The inorganic component of the mixture underwent thermal decomposition with formation of MgO and evolution of gaseous products including CO2 and H2O. Influence of the magnesium compound mixed with PET, and carbonization temperature on the pore structure of carbonaceous material is presented. As found, porosity of prepared materials depended on magnesium carbonate loading in the starting mixture and on heating temperature. The impact of CO2 and H2O evolved during heating on the pore structure is discussed, and a mechanism of pore formation is proposed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801694t
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7110–7116[article] Porous carbon obtained by carbonization of PET mixed with basic magnesium carbonate : pore structure and pore creation mechanism [texte imprimé] / Jacek Przepiórski, Auteur ; Justyna Karolczyk, Auteur ; Kazuhiro Takeda, Auteur . - 2009 . - pp. 7110–7116.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7110–7116
Mots-clés : Porous carbon PET [poly(ethylene terephtalate)]Magnesium carbonate mixture Gas flow Résumé : Porous carbon materials were prepared by heating of a PET [poly(ethylene terephtalate)] and magnesium carbonate (3MgCO3·Mg(OH)2·3H2O) mixture under Ar gas flow, followed by acid washing. The inorganic component of the mixture underwent thermal decomposition with formation of MgO and evolution of gaseous products including CO2 and H2O. Influence of the magnesium compound mixed with PET, and carbonization temperature on the pore structure of carbonaceous material is presented. As found, porosity of prepared materials depended on magnesium carbonate loading in the starting mixture and on heating temperature. The impact of CO2 and H2O evolved during heating on the pore structure is discussed, and a mechanism of pore formation is proposed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801694t Exemplaires
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Titre : Solubility and diffusivity of carbon dioxide in solid-state isotactic polypropylene by the pressure−decay method Type de document : texte imprimé Auteurs : Da-chao Li, Auteur ; Tao Liu, Auteur ; Ling Zhao, Auteur Année de publication : 2009 Article en page(s) : pp. 7117–7124 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon dioxide Solid-state isotactic polypropylene Pressure− decay method Résumé : The solubility and diffusivity of carbon dioxide (CO2) in the solid-state isotactic polypropylene (iPP) were studied by using the pressure−decay method at temperatures of 373.15, 398.15, and 423.15 K and pressures ranging from 1 to 15 MPa. The solubilities of CO2 in the solid-state and amorphous regions of iPP were both obtained. They increased almost linearly with increasing pressure and decreased with increasing temperature. The Sanchez−Lacombe equation of state (S-L EOS) correlated the solubility in the amorphous regions of the solid-state iPP within 3% average relative deviation in conjunction with a temperature-dependent interaction parameter. The diffusion coefficient of CO2 in the solid-state iPP showed a weak concentration dependence and had an order of magnitude of 10−10−10−9 m2/s in the solid-state iPP. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019483
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7117–7124[article] Solubility and diffusivity of carbon dioxide in solid-state isotactic polypropylene by the pressure−decay method [texte imprimé] / Da-chao Li, Auteur ; Tao Liu, Auteur ; Ling Zhao, Auteur . - 2009 . - pp. 7117–7124.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7117–7124
Mots-clés : Carbon dioxide Solid-state isotactic polypropylene Pressure− decay method Résumé : The solubility and diffusivity of carbon dioxide (CO2) in the solid-state isotactic polypropylene (iPP) were studied by using the pressure−decay method at temperatures of 373.15, 398.15, and 423.15 K and pressures ranging from 1 to 15 MPa. The solubilities of CO2 in the solid-state and amorphous regions of iPP were both obtained. They increased almost linearly with increasing pressure and decreased with increasing temperature. The Sanchez−Lacombe equation of state (S-L EOS) correlated the solubility in the amorphous regions of the solid-state iPP within 3% average relative deviation in conjunction with a temperature-dependent interaction parameter. The diffusion coefficient of CO2 in the solid-state iPP showed a weak concentration dependence and had an order of magnitude of 10−10−10−9 m2/s in the solid-state iPP. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019483 Exemplaires
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Titre : Carbon molecular sieves prepared from polymeric precursors : porous structure and hydrogen adsorption properties Type de document : texte imprimé Auteurs : Ana Ma Silvestre-Albero, Auteur ; Anass Wahby, Auteur ; Joaquín Silvestre-Albero, Auteur Année de publication : 2009 Article en page(s) : pp. 7125–7131 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon molecular sieves Polymer precursors N2 adsorption CO2 Résumé : The textural characterization of a series of carbon molecular sieves (CMS) prepared from different polymer precursors has been investigated using N2 adsorption at 77 K and CO2 adsorption at 273 K, together with immersion calorimetry into liquids of different molecular dimensions. Experimental results show that the carbon molecular sieves cover a wide range of porosity, from pure microporous CMS (pore diameter below 0.56 nm) to CMS combining larger micropores (above 0.7 nm) together with a certain proportion of mesoporosity. H2 adsorption measurements on these CMS at cryogenic temperature (77 K) and ambient pressure (0.1 MPa) show that the hydrogen adsorption capacity exhibits a linear correlation with the volume of narrow micropores (Vn). Furthermore, these results confirm experimentally the necessity of a tailored micropore size in order to achieve an optimum packing density of the adsorbed hydrogen molecules (micropore size around 0.6 nm). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900091n
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7125–7131[article] Carbon molecular sieves prepared from polymeric precursors : porous structure and hydrogen adsorption properties [texte imprimé] / Ana Ma Silvestre-Albero, Auteur ; Anass Wahby, Auteur ; Joaquín Silvestre-Albero, Auteur . - 2009 . - pp. 7125–7131.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7125–7131
Mots-clés : Carbon molecular sieves Polymer precursors N2 adsorption CO2 Résumé : The textural characterization of a series of carbon molecular sieves (CMS) prepared from different polymer precursors has been investigated using N2 adsorption at 77 K and CO2 adsorption at 273 K, together with immersion calorimetry into liquids of different molecular dimensions. Experimental results show that the carbon molecular sieves cover a wide range of porosity, from pure microporous CMS (pore diameter below 0.56 nm) to CMS combining larger micropores (above 0.7 nm) together with a certain proportion of mesoporosity. H2 adsorption measurements on these CMS at cryogenic temperature (77 K) and ambient pressure (0.1 MPa) show that the hydrogen adsorption capacity exhibits a linear correlation with the volume of narrow micropores (Vn). Furthermore, these results confirm experimentally the necessity of a tailored micropore size in order to achieve an optimum packing density of the adsorbed hydrogen molecules (micropore size around 0.6 nm). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900091n Exemplaires
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Titre : Cellulose/soy protein isolate blend films prepared via room-temperature ionic liquid Type de document : texte imprimé Auteurs : Rong-Lan Wu, Auteur ; Xiu-Li Wang, Auteur ; Yu-Zhong Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 7132–7136 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ionic liquid AmimCl Soy protein isolate Fourier transform infrared spectrum Résumé : An ionic liquid (IL), 1-ally-3-methylimidazolium chloride (AmimCl), was used as cosolvent for cellulose and soy protein isolate (SPI) to prepare different compositions of cellulose/SPI blend films, which were coagulated under a nonsolvent condition. The structures of the blend films were investigated by Fourier transform infrared (FTIR) spectrum, X-ray diffraction (XRD), scanning electron microscope (SEM), and transparence analysis, and the physical properties of the films such as mechanical properties, water resistance, water vapor permeability, gas permeability, and thermal stability were also examined. The results indicate that cellulose/SPI blends have excellent miscibility in all weight ratios of cellulose to SPI. With the increase of cellulose content in blend films, the tensile strength, elongation at break, water resistance, and thermal stability of the cellulose/SPI blend films all increase. The addition of the cellulose results in a decrease in the water vapor permeability values. In addition, all films have high gas barrier capacities. These films appear to have the potential as packing and/or coating materials, replacing synthetic polymer films. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9001052
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7132–7136[article] Cellulose/soy protein isolate blend films prepared via room-temperature ionic liquid [texte imprimé] / Rong-Lan Wu, Auteur ; Xiu-Li Wang, Auteur ; Yu-Zhong Wang, Auteur . - 2009 . - pp. 7132–7136.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7132–7136
Mots-clés : Ionic liquid AmimCl Soy protein isolate Fourier transform infrared spectrum Résumé : An ionic liquid (IL), 1-ally-3-methylimidazolium chloride (AmimCl), was used as cosolvent for cellulose and soy protein isolate (SPI) to prepare different compositions of cellulose/SPI blend films, which were coagulated under a nonsolvent condition. The structures of the blend films were investigated by Fourier transform infrared (FTIR) spectrum, X-ray diffraction (XRD), scanning electron microscope (SEM), and transparence analysis, and the physical properties of the films such as mechanical properties, water resistance, water vapor permeability, gas permeability, and thermal stability were also examined. The results indicate that cellulose/SPI blends have excellent miscibility in all weight ratios of cellulose to SPI. With the increase of cellulose content in blend films, the tensile strength, elongation at break, water resistance, and thermal stability of the cellulose/SPI blend films all increase. The addition of the cellulose results in a decrease in the water vapor permeability values. In addition, all films have high gas barrier capacities. These films appear to have the potential as packing and/or coating materials, replacing synthetic polymer films. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9001052 Exemplaires
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Titre : Input-output pairing using effective relative energy array Type de document : texte imprimé Auteurs : N. Monshizadeh-Naini, Auteur ; A. Fatehi, Auteur ; A. Khaki-Sedigh, Auteur Année de publication : 2009 Article en page(s) : pp. 7137–7144 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pairing criterion Gain array Steady state gain Bandwidth information Résumé : This paper provides an extended pairing criterion based on the effective relative gain array. The extension is achieved in two steps. First, an energy based compromise between steady state gain and bandwidth information of the plant is proposed. Then, it is argued that the best pairing may depend on the closed-loop specifications. Thus, to make this extension practical and precise, a simple solution to take into account the bandwidth of the desired closed-loop plant is introduced. To show the effectiveness of the proposed method, several examples are discussed. These examples include the cases where the conventional ERGA leads to an appropriate result and is in agreement with the proposed pairing criterion. They also include the cases where the original ERGA leads to an improper pairing while the proposed method achieves the acceptable pairs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801667s
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7137–7144[article] Input-output pairing using effective relative energy array [texte imprimé] / N. Monshizadeh-Naini, Auteur ; A. Fatehi, Auteur ; A. Khaki-Sedigh, Auteur . - 2009 . - pp. 7137–7144.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7137–7144
Mots-clés : Pairing criterion Gain array Steady state gain Bandwidth information Résumé : This paper provides an extended pairing criterion based on the effective relative gain array. The extension is achieved in two steps. First, an energy based compromise between steady state gain and bandwidth information of the plant is proposed. Then, it is argued that the best pairing may depend on the closed-loop specifications. Thus, to make this extension practical and precise, a simple solution to take into account the bandwidth of the desired closed-loop plant is introduced. To show the effectiveness of the proposed method, several examples are discussed. These examples include the cases where the conventional ERGA leads to an appropriate result and is in agreement with the proposed pairing criterion. They also include the cases where the original ERGA leads to an improper pairing while the proposed method achieves the acceptable pairs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801667s Exemplaires
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Titre : Graphical analysis of process changes for water minimization Type de document : texte imprimé Auteurs : Xiao Feng, Auteur ; Yang Liu, Auteur ; Long Huang, Auteur Année de publication : 2009 Article en page(s) : pp. 7145–7151 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Water-using process Freshwater consumption Wastewater generation Inlet/outlet concentrations Résumé : The effective changes in a water-using process can reduce freshwater consumption and wastewater generation. The main effects of process changes include the increment of limiting inlet/outlet concentrations of water-using processes and the reduction of the contaminant load of those processes. Because the water pinch of a water system is the bottleneck to limit the freshwater consumption, in this paper a water pinch diagram is used to explore the impact of process changes on the pinch point. Process changes which can move the pinch point upward and/or leftward can reduce freshwater consumption in the system. To further save freshwater in a water system, a process change which can increase limiting concentrations should be executed to an across-pinch process, and a process change which can reduce contaminant load should be executed below the pinch. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900094m
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7145–7151[article] Graphical analysis of process changes for water minimization [texte imprimé] / Xiao Feng, Auteur ; Yang Liu, Auteur ; Long Huang, Auteur . - 2009 . - pp. 7145–7151.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7145–7151
Mots-clés : Water-using process Freshwater consumption Wastewater generation Inlet/outlet concentrations Résumé : The effective changes in a water-using process can reduce freshwater consumption and wastewater generation. The main effects of process changes include the increment of limiting inlet/outlet concentrations of water-using processes and the reduction of the contaminant load of those processes. Because the water pinch of a water system is the bottleneck to limit the freshwater consumption, in this paper a water pinch diagram is used to explore the impact of process changes on the pinch point. Process changes which can move the pinch point upward and/or leftward can reduce freshwater consumption in the system. To further save freshwater in a water system, a process change which can increase limiting concentrations should be executed to an across-pinch process, and a process change which can reduce contaminant load should be executed below the pinch. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900094m Exemplaires
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Titre : Evolution of resource allocation networks Type de document : texte imprimé Auteurs : Ashish K. Das, Auteur ; Uday V. Shenoy, Auteur ; Santanu Bandyopadhyay, Auteur Année de publication : 2009 Article en page(s) : pp. 7152–7167 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Resource allocation network Graph theoryProcess integration Résumé : It is often desirable to evolve a resource allocation network (RAN) into a simpler one for improved controllability, operability, and ease of implementation. In this paper, a methodology, based on the concept of graph theory and process integration, is proposed to evolve a preliminary RAN into a simpler one involving fewer interconnections (matches) by incurring the minimum resource penalty. The proposed methodology is essentially based on four evolution strategies: loop breaking without violation, two-loop relaxation, loop breaking with path relaxation, and direct path elimination. The procedure is applied to various RANs such as water allocation, hydrogen allocation, and material allocation in a reuse network. The evolved networks are compared with results obtained from a new mathematical optimization formulation involving mixed integer linear programming. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9003392
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7152–7167[article] Evolution of resource allocation networks [texte imprimé] / Ashish K. Das, Auteur ; Uday V. Shenoy, Auteur ; Santanu Bandyopadhyay, Auteur . - 2009 . - pp. 7152–7167.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7152–7167
Mots-clés : Resource allocation network Graph theoryProcess integration Résumé : It is often desirable to evolve a resource allocation network (RAN) into a simpler one for improved controllability, operability, and ease of implementation. In this paper, a methodology, based on the concept of graph theory and process integration, is proposed to evolve a preliminary RAN into a simpler one involving fewer interconnections (matches) by incurring the minimum resource penalty. The proposed methodology is essentially based on four evolution strategies: loop breaking without violation, two-loop relaxation, loop breaking with path relaxation, and direct path elimination. The procedure is applied to various RANs such as water allocation, hydrogen allocation, and material allocation in a reuse network. The evolved networks are compared with results obtained from a new mathematical optimization formulation involving mixed integer linear programming. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9003392 Exemplaires
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Titre : Global sensitivity analysis challenges in biological systems modeling Type de document : texte imprimé Auteurs : A. Kiparissides, Auteur ; S. S. Kucherenko, Auteur ; A. Mantalaris, Auteur Année de publication : 2009 Article en page(s) : pp. 7168–7180 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Biological systems modeling Sensitivity analysis techniques Résumé : Mammalian cell culture systems produce high-value biologics, such as monoclonal antibodies, which are increasingly being used clinically. A complete framework that interlinks model-based design of experiments (DOE) and model-based control and optimization to the actual industrial bioprocess could assist experimentation, hence reducing costs. However, high fidelity models have the inherent characteristic of containing a large number of parameters, which is further complicated by limitations in the current analytical techniques, thus resulting in the experimental validation of merely a small number of parameters. Sensitivity analysis techniques can provide valuable insight into model characteristics. Traditionally, the application of sensitivity analysis on models of biological systems has been treated more or less as a black box operation. In the present work, we elucidate the aspects of sensitivity analysis and identify, with reasoning, the most suitable group of sensitivity analysis methods for application to highly nonlinear dynamic models in the context of biological systems. Specifically, we perform computational experiments on antibody-producing mammalian cell culture models of different complexities and identify, as well as address, problems associated with such “real life” models. In conclusion, a novel global screening method (derivative based global sensitivity measures, DGSM) is proven to be the most time-efficient and robust alternative to the established variance-based Monte Carlo methods. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900139x
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7168–7180[article] Global sensitivity analysis challenges in biological systems modeling [texte imprimé] / A. Kiparissides, Auteur ; S. S. Kucherenko, Auteur ; A. Mantalaris, Auteur . - 2009 . - pp. 7168–7180.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7168–7180
Mots-clés : Biological systems modeling Sensitivity analysis techniques Résumé : Mammalian cell culture systems produce high-value biologics, such as monoclonal antibodies, which are increasingly being used clinically. A complete framework that interlinks model-based design of experiments (DOE) and model-based control and optimization to the actual industrial bioprocess could assist experimentation, hence reducing costs. However, high fidelity models have the inherent characteristic of containing a large number of parameters, which is further complicated by limitations in the current analytical techniques, thus resulting in the experimental validation of merely a small number of parameters. Sensitivity analysis techniques can provide valuable insight into model characteristics. Traditionally, the application of sensitivity analysis on models of biological systems has been treated more or less as a black box operation. In the present work, we elucidate the aspects of sensitivity analysis and identify, with reasoning, the most suitable group of sensitivity analysis methods for application to highly nonlinear dynamic models in the context of biological systems. Specifically, we perform computational experiments on antibody-producing mammalian cell culture models of different complexities and identify, as well as address, problems associated with such “real life” models. In conclusion, a novel global screening method (derivative based global sensitivity measures, DGSM) is proven to be the most time-efficient and robust alternative to the established variance-based Monte Carlo methods. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900139x Exemplaires
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Titre : Analysis of equipment performance in processes with complex serial-parallel structures Type de document : texte imprimé Auteurs : Francois Yacoub, Auteur ; John F. MacGregor, Auteur Année de publication : 2009 Article en page(s) : pp. 7181–7185 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Manufacturing processes Parallel equipment units Résumé : In manufacturing processes where material is processed through a series of stages and at each stage there are many parallel equipment units that can be used, a major difficulty is assessing whether or not any of the large number of equipment units is defective and is causing a problem with the final product. A procedure is introduced in this paper to analyze historical data from such processes to address this question. The method is based on the use of indicator variables and latent variable models. The assessment of the performance of the equipment units is easily done using simple plots available from the resulting latent variable model. The methodology is illustrated through its very successful application to a complex hollow fiber membrane manufacturing process. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801695f
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7181–7185[article] Analysis of equipment performance in processes with complex serial-parallel structures [texte imprimé] / Francois Yacoub, Auteur ; John F. MacGregor, Auteur . - 2009 . - pp. 7181–7185.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7181–7185
Mots-clés : Manufacturing processes Parallel equipment units Résumé : In manufacturing processes where material is processed through a series of stages and at each stage there are many parallel equipment units that can be used, a major difficulty is assessing whether or not any of the large number of equipment units is defective and is causing a problem with the final product. A procedure is introduced in this paper to analyze historical data from such processes to address this question. The method is based on the use of indicator variables and latent variable models. The assessment of the performance of the equipment units is easily done using simple plots available from the resulting latent variable model. The methodology is illustrated through its very successful application to a complex hollow fiber membrane manufacturing process. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801695f Exemplaires
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Titre : Reactive distillation for esterification of an alcohol mixture containing n-butanol and n-amyl alcohol Type de document : texte imprimé Auteurs : Hao-Yeh Lee, Auteur ; Ling-Ting Yen, Auteur ; Chien, I-Lung, Auteur Année de publication : 2009 Article en page(s) : pp. 7186–7204 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Alcohol mixtures Esterification Résumé : Manufacturing processes in the semiconductor and pharmaceutical industries often produce alcohol mixture byproducts. Therefore, the esterification of alcohol mixtures may be an important step in reusing wastes from these industries. There are two alternative methods for using the alcohol mixtures as feed for reactive distillation (RD). The first method separates this mixture into pure alcohols first and then follows with esterification using the RD column. The second method uses direct esterification of the alcohol mixture in a RD column, and then separates the mixed-ester products. This paper discusses the esterification of a n-butanol (BuOH) and n-amyl alcohol (AmOH) mixture with acetic acid (HAc). This study presents two important results based on optimizing the total annual cost (TAC). First, the mixed BuOH/AmOH system, with direct esterification with RD followed by product separation, is more economical than the system that first separates the mixture. Second, this study proposes a novel economical indirect-sequence design flowsheet with aqueous reflux. Another important issue in this study is the choice of the relative feed location, because the boiling point of acid lies between that of the two alcohols (i.e., BuOH En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801891q
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7186–7204[article] Reactive distillation for esterification of an alcohol mixture containing n-butanol and n-amyl alcohol [texte imprimé] / Hao-Yeh Lee, Auteur ; Ling-Ting Yen, Auteur ; Chien, I-Lung, Auteur . - 2009 . - pp. 7186–7204.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7186–7204
Mots-clés : Alcohol mixtures Esterification Résumé : Manufacturing processes in the semiconductor and pharmaceutical industries often produce alcohol mixture byproducts. Therefore, the esterification of alcohol mixtures may be an important step in reusing wastes from these industries. There are two alternative methods for using the alcohol mixtures as feed for reactive distillation (RD). The first method separates this mixture into pure alcohols first and then follows with esterification using the RD column. The second method uses direct esterification of the alcohol mixture in a RD column, and then separates the mixed-ester products. This paper discusses the esterification of a n-butanol (BuOH) and n-amyl alcohol (AmOH) mixture with acetic acid (HAc). This study presents two important results based on optimizing the total annual cost (TAC). First, the mixed BuOH/AmOH system, with direct esterification with RD followed by product separation, is more economical than the system that first separates the mixture. Second, this study proposes a novel economical indirect-sequence design flowsheet with aqueous reflux. Another important issue in this study is the choice of the relative feed location, because the boiling point of acid lies between that of the two alcohols (i.e., BuOH En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801891q Exemplaires
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Titre : Safe-parking of a styrene polymerization process Type de document : texte imprimé Auteurs : Rahul Gandhi, Auteur ; Dave Baldwin, Auteur ; Prashant Mhaskar, Auteur Année de publication : 2009 Article en page(s) : pp. 7205–7213 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nitroxide-mediated radical polymerization Styrene Lyapunov based model Monomer feed streams Résumé : This work considers the problem of control and fault-handling in living nitroxide-mediated radical polymerization (NMRP) of styrene subject to input constraints. First, a Lyapunov based model predictive controller is designed that allows for an explicit computation of the stability region. Next, a fault in one of the monomer feed streams is considered due to which operation of the reactor at the nominal operating point is no longer possible. It is shown that trying to continue nominal operation using the remaining functioning actuator drives the process to a point resulting in significantly off-spec product. A safe-parking framework is utilized to choose an operating point during fault rectification so that the styrene produced during fault rectification complies with the desired product specifications, and smooth resumption of nominal operation upon fault rectification is achieved. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019938
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7205–7213[article] Safe-parking of a styrene polymerization process [texte imprimé] / Rahul Gandhi, Auteur ; Dave Baldwin, Auteur ; Prashant Mhaskar, Auteur . - 2009 . - pp. 7205–7213.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7205–7213
Mots-clés : Nitroxide-mediated radical polymerization Styrene Lyapunov based model Monomer feed streams Résumé : This work considers the problem of control and fault-handling in living nitroxide-mediated radical polymerization (NMRP) of styrene subject to input constraints. First, a Lyapunov based model predictive controller is designed that allows for an explicit computation of the stability region. Next, a fault in one of the monomer feed streams is considered due to which operation of the reactor at the nominal operating point is no longer possible. It is shown that trying to continue nominal operation using the remaining functioning actuator drives the process to a point resulting in significantly off-spec product. A safe-parking framework is utilized to choose an operating point during fault rectification so that the styrene produced during fault rectification complies with the desired product specifications, and smooth resumption of nominal operation upon fault rectification is achieved. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019938 Exemplaires
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Titre : Operational planning of large-scale industrial batch plants under demand due date and amount uncertainty. I. robust optimization framework Type de document : texte imprimé Auteurs : Peter M. Verderame, Auteur ; Christodoulos A. Floudas, Auteur Année de publication : 2009 Article en page(s) : pp. 7214–7231 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Large-scale industrial batch plant Operational planning model Résumé : The operational planning of a large-scale industrial batch plant typically occurs over a time horizon of several months with the goal of providing daily production targets and raw material requirements for the plant in question. Due to the length of the time horizon, demand uncertainty should be taken into account in order to ensure that the operational planning model provides reliable production targets and/or raw material requirements. A robust novel operational planning model has been developed in order to address the objective of providing a reliable daily production profile which is immune to various forms of demand uncertainty. The ability of the proposed planning model to address the aforementioned objectives of an operational planning model has been validated through an industrial case study of a large-scale, multiproduct, and multipurpose batch plant having the capability of producing hundreds of different products over a time horizon of three months. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9001124
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7214–7231[article] Operational planning of large-scale industrial batch plants under demand due date and amount uncertainty. I. robust optimization framework [texte imprimé] / Peter M. Verderame, Auteur ; Christodoulos A. Floudas, Auteur . - 2009 . - pp. 7214–7231.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7214–7231
Mots-clés : Large-scale industrial batch plant Operational planning model Résumé : The operational planning of a large-scale industrial batch plant typically occurs over a time horizon of several months with the goal of providing daily production targets and raw material requirements for the plant in question. Due to the length of the time horizon, demand uncertainty should be taken into account in order to ensure that the operational planning model provides reliable production targets and/or raw material requirements. A robust novel operational planning model has been developed in order to address the objective of providing a reliable daily production profile which is immune to various forms of demand uncertainty. The ability of the proposed planning model to address the aforementioned objectives of an operational planning model has been validated through an industrial case study of a large-scale, multiproduct, and multipurpose batch plant having the capability of producing hundreds of different products over a time horizon of three months. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9001124 Exemplaires
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Titre : Energy efficiency limits for a recuperative bayonet sulfuric acid decomposition reactor for sulfur cycle thermochemical hydrogen production Type de document : texte imprimé Auteurs : Maximilian B. Gorensek, Auteur ; Thomas B. Edwards, Auteur Année de publication : 2009 Article en page(s) : pp. 7232–7245 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Recuperative bayonet reactor Sulfur-based thermochemical hydrogen cycle Energy efficiency Résumé : A recuperative bayonet reactor design for the high-temperature sulfuric acid decomposition step in sulfur-based thermochemical hydrogen cycles was evaluated using pinch analysis in conjunction with statistical methods. The objective was to establish the minimum energy requirement. Taking hydrogen production via alkaline electrolysis with nuclear power as the benchmark, the acid decomposition step can consume no more than 450 kJ/(mol of SO2) for sulfur cycles to be competitive. The lowest value of the minimum heating target, 320.9 kJ/(mol of SO2), was found at the highest pressure (90 bar) and peak process temperature (900 °C) considered, and at a feed concentration of 42.5 mol % H2SO4. This should be low enough for a practical water-splitting process, even including the additional energy required to concentrate the acid feed. Lower temperatures consistently gave higher minimum heating targets. The lowest peak process temperature that could meet the benchmark of 450 kJ/(mol of SO2) was 750 °C. If the decomposition reactor were to be heated indirectly by an advanced gas-cooled reactor heat source (50 °C temperature difference between the primary and secondary coolants, 25 °C minimum temperature difference between the secondary coolant and the process), then sulfur cycles using this concept could be competitive with alkaline electrolysis provided that the primary heat source temperature is at least 825 °C. The bayonet design will not be practical if the (primary heat source) reactor outlet temperature is below 825 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900310r
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7232–7245[article] Energy efficiency limits for a recuperative bayonet sulfuric acid decomposition reactor for sulfur cycle thermochemical hydrogen production [texte imprimé] / Maximilian B. Gorensek, Auteur ; Thomas B. Edwards, Auteur . - 2009 . - pp. 7232–7245.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7232–7245
Mots-clés : Recuperative bayonet reactor Sulfur-based thermochemical hydrogen cycle Energy efficiency Résumé : A recuperative bayonet reactor design for the high-temperature sulfuric acid decomposition step in sulfur-based thermochemical hydrogen cycles was evaluated using pinch analysis in conjunction with statistical methods. The objective was to establish the minimum energy requirement. Taking hydrogen production via alkaline electrolysis with nuclear power as the benchmark, the acid decomposition step can consume no more than 450 kJ/(mol of SO2) for sulfur cycles to be competitive. The lowest value of the minimum heating target, 320.9 kJ/(mol of SO2), was found at the highest pressure (90 bar) and peak process temperature (900 °C) considered, and at a feed concentration of 42.5 mol % H2SO4. This should be low enough for a practical water-splitting process, even including the additional energy required to concentrate the acid feed. Lower temperatures consistently gave higher minimum heating targets. The lowest peak process temperature that could meet the benchmark of 450 kJ/(mol of SO2) was 750 °C. If the decomposition reactor were to be heated indirectly by an advanced gas-cooled reactor heat source (50 °C temperature difference between the primary and secondary coolants, 25 °C minimum temperature difference between the secondary coolant and the process), then sulfur cycles using this concept could be competitive with alkaline electrolysis provided that the primary heat source temperature is at least 825 °C. The bayonet design will not be practical if the (primary heat source) reactor outlet temperature is below 825 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900310r Exemplaires
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Titre : Asymmetric framework for predicting liquid-liquid equilibrium of ionic liquid-mixed-solvent systems. 1. theory, phase stability analysis, and parameter estimation Type de document : texte imprimé Auteurs : Luke D. Simoni, Auteur ; Joan F. Brennecke, Auteur ; Mark A. Stadtherr, Auteur Année de publication : 2009 Article en page(s) : pp. 7246–7256 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Electrolyte/mixed-solvent systems Liquid− liquid equilibrium Ionic liquid Aqueous solution Résumé : A new approach for modeling liquid−liquid equilibrium in electrolyte/mixed-solvent systems is presented, with particular focus on systems involving a dilute aqueous solution of an ionic liquid (IL). This new approach involves an asymmetric framework in which different phases have different degrees of electrolyte dissociation, and are thus represented by different Gibbs free energy models. As a first case, we consider the situation in which the electrolyte is either completely dissociated or completely paired (molecular), with its state depending on the dielectric constant of the mixed solvent and on the concentration of the salt in the phase in question. The theory underlying this asymmetric framework is developed, and a rigorous approach for phase stability analysis is presented. It is explained how to formulate and solve the parameter estimation problem for determining model parameters from binary data, and this process is demonstrated using examples. An immediate goal is to use this approach to predict liquid−liquid equilibrium for ternary IL/solvent/water systems, using parameters obtained from binary and pure component data only. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900461j
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7246–7256[article] Asymmetric framework for predicting liquid-liquid equilibrium of ionic liquid-mixed-solvent systems. 1. theory, phase stability analysis, and parameter estimation [texte imprimé] / Luke D. Simoni, Auteur ; Joan F. Brennecke, Auteur ; Mark A. Stadtherr, Auteur . - 2009 . - pp. 7246–7256.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7246–7256
Mots-clés : Electrolyte/mixed-solvent systems Liquid− liquid equilibrium Ionic liquid Aqueous solution Résumé : A new approach for modeling liquid−liquid equilibrium in electrolyte/mixed-solvent systems is presented, with particular focus on systems involving a dilute aqueous solution of an ionic liquid (IL). This new approach involves an asymmetric framework in which different phases have different degrees of electrolyte dissociation, and are thus represented by different Gibbs free energy models. As a first case, we consider the situation in which the electrolyte is either completely dissociated or completely paired (molecular), with its state depending on the dielectric constant of the mixed solvent and on the concentration of the salt in the phase in question. The theory underlying this asymmetric framework is developed, and a rigorous approach for phase stability analysis is presented. It is explained how to formulate and solve the parameter estimation problem for determining model parameters from binary data, and this process is demonstrated using examples. An immediate goal is to use this approach to predict liquid−liquid equilibrium for ternary IL/solvent/water systems, using parameters obtained from binary and pure component data only. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900461j Exemplaires
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Titre : Asymmetric framework for predicting liquid-liquid equilibrium of ionic liquid-mixed-solvent systems. 2. prediction of ternary systems Type de document : texte imprimé Auteurs : Luke D. Simoni, Auteur ; Alexandre Chapeaux, Auteur ; Joan F. Brennecke, Auteur Année de publication : 2009 Article en page(s) : pp. 7257–7265 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Asymmetric framework Liquid− liquid equilibrium Electrolyte/mixed-solvent systems Résumé : A new asymmetric framework for modeling liquid−liquid equilibrium (LLE) in electrolyte/mixed-solvent systems is demonstrated, with focus on systems involving a dilute aqueous solution of an ionic liquid (IL). The extent to which this approach is able to predict ternary LLE, using parameters obtained from binary and pure-component data only, is evaluated. For this purpose, ternary IL/solvent/water systems are used as examples. Comparisons of predicted LLE are made to experimental data representing various types of ternary LLE behavior, as well as to predictions obtained from standard symmetric models. Results indicate that an asymmetric NRTL/eNRTL model provides better predictions of ternary LLE for systems containing ILs and water than standard symmetric models. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004628
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7257–7265[article] Asymmetric framework for predicting liquid-liquid equilibrium of ionic liquid-mixed-solvent systems. 2. prediction of ternary systems [texte imprimé] / Luke D. Simoni, Auteur ; Alexandre Chapeaux, Auteur ; Joan F. Brennecke, Auteur . - 2009 . - pp. 7257–7265.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7257–7265
Mots-clés : Asymmetric framework Liquid− liquid equilibrium Electrolyte/mixed-solvent systems Résumé : A new asymmetric framework for modeling liquid−liquid equilibrium (LLE) in electrolyte/mixed-solvent systems is demonstrated, with focus on systems involving a dilute aqueous solution of an ionic liquid (IL). The extent to which this approach is able to predict ternary LLE, using parameters obtained from binary and pure-component data only, is evaluated. For this purpose, ternary IL/solvent/water systems are used as examples. Comparisons of predicted LLE are made to experimental data representing various types of ternary LLE behavior, as well as to predictions obtained from standard symmetric models. Results indicate that an asymmetric NRTL/eNRTL model provides better predictions of ternary LLE for systems containing ILs and water than standard symmetric models. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004628 Exemplaires
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Titre : Application of preferential crystallization for different types of racemic compounds Type de document : texte imprimé Auteurs : Yinghong Lu, Auteur ; Xiujuan Wang, Auteur ; Chi Bun Ching, Auteur Année de publication : 2009 Article en page(s) : pp. 7266–7275 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Preferential crystallization Racemic-conglomerate-forming system Systematic approach Résumé : A systematic approach was developed and applied to the preferential crystallization of a racemic-conglomerate-forming system in our previous work. In this work, we extended and modified the strategy for two typical types of racemic-compound-forming systems, namely, mandelic acid and ketoprofen, taking into account the crucial different thermodynamics and crystal structure properties between a racemic compound and a conglomerate. System thermodynamic aspects such as binary melting-point phase diagram and ternary solubility phase diagram were measured. The metastable zone widths of mandelic acid with different compositions in water under different cooling rates were determined with a Lasentec focused beam reflectance (FBR) probe. The crystal nucleation and growth kinetics were measured by s-plane analysis. Based on the solubility and the metastable zone width diagram, the maximum limits of practicable operating ranges for conducting preferential crystallization to obtain enantiomerically pure products was defined. Different operating profiles were applied, and the solution supersaturation was analyzed for the crystallization processes. The optical purities, yields, and crystal size distributions of the final products were examined and compared. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801344s
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7266–7275[article] Application of preferential crystallization for different types of racemic compounds [texte imprimé] / Yinghong Lu, Auteur ; Xiujuan Wang, Auteur ; Chi Bun Ching, Auteur . - 2009 . - pp. 7266–7275.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7266–7275
Mots-clés : Preferential crystallization Racemic-conglomerate-forming system Systematic approach Résumé : A systematic approach was developed and applied to the preferential crystallization of a racemic-conglomerate-forming system in our previous work. In this work, we extended and modified the strategy for two typical types of racemic-compound-forming systems, namely, mandelic acid and ketoprofen, taking into account the crucial different thermodynamics and crystal structure properties between a racemic compound and a conglomerate. System thermodynamic aspects such as binary melting-point phase diagram and ternary solubility phase diagram were measured. The metastable zone widths of mandelic acid with different compositions in water under different cooling rates were determined with a Lasentec focused beam reflectance (FBR) probe. The crystal nucleation and growth kinetics were measured by s-plane analysis. Based on the solubility and the metastable zone width diagram, the maximum limits of practicable operating ranges for conducting preferential crystallization to obtain enantiomerically pure products was defined. Different operating profiles were applied, and the solution supersaturation was analyzed for the crystallization processes. The optical purities, yields, and crystal size distributions of the final products were examined and compared. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801344s Exemplaires
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Titre : Enhancement of colloidal filtration : a new combined approach based on cake and suspension destabilization Type de document : texte imprimé Auteurs : Sasanka Raha, Auteur ; Pradip, Auteur ; Prakash C. Kapur, Auteur Année de publication : 2009 Article en page(s) : pp. 7276–7282 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Vacuum filtration Pressure filtrationA16SG alumina Cake Suspension destabilization Résumé : Pressure and vacuum filtration experiments using A16SG alumina with and without homogenization of formed cake and suspension are carried out. Homogenization involving mixing of formed cake with the suspension on top of the cake enhances filtration process performance in terms of reduction in filtration time without any alteration in the equilibrium solids volume fraction. A model is developed and validated based on the Mean-Phi model of pressure filtration to simulate the filtration behavior in the presence of continuous and intermittent homogenization. It is demonstrated that a single batch pressure filtration experiment is sufficient to provide the necessary information to simulate an enhanced pressure filtration process involving homogenization. Simulations for situations involving increasing numbers of homogenization and continuous homogenization are also carried out. Advantages regarding time and equilibrium solids fraction can be availed where homogenization along with change in the state of suspension aggregation by using additive(s) or pH change is carried out. Under such a scheme, a filtration process should start with a flocculated/aggregated condition along with mixing. With progress of the process, the suspension should be gradually converted to dispersed type by modulating the slurry chemistry, to achieve a maximum equilibrium solids volume fraction. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801750w
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7276–7282[article] Enhancement of colloidal filtration : a new combined approach based on cake and suspension destabilization [texte imprimé] / Sasanka Raha, Auteur ; Pradip, Auteur ; Prakash C. Kapur, Auteur . - 2009 . - pp. 7276–7282.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7276–7282
Mots-clés : Vacuum filtration Pressure filtrationA16SG alumina Cake Suspension destabilization Résumé : Pressure and vacuum filtration experiments using A16SG alumina with and without homogenization of formed cake and suspension are carried out. Homogenization involving mixing of formed cake with the suspension on top of the cake enhances filtration process performance in terms of reduction in filtration time without any alteration in the equilibrium solids volume fraction. A model is developed and validated based on the Mean-Phi model of pressure filtration to simulate the filtration behavior in the presence of continuous and intermittent homogenization. It is demonstrated that a single batch pressure filtration experiment is sufficient to provide the necessary information to simulate an enhanced pressure filtration process involving homogenization. Simulations for situations involving increasing numbers of homogenization and continuous homogenization are also carried out. Advantages regarding time and equilibrium solids fraction can be availed where homogenization along with change in the state of suspension aggregation by using additive(s) or pH change is carried out. Under such a scheme, a filtration process should start with a flocculated/aggregated condition along with mixing. With progress of the process, the suspension should be gradually converted to dispersed type by modulating the slurry chemistry, to achieve a maximum equilibrium solids volume fraction. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801750w Exemplaires
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Titre : An assessment on the interaction of a hydrophilic ionic liquid with different sorbents Type de document : texte imprimé Auteurs : K. Vijayaraghavan, Auteur ; Thi Phuong Thuy Pham, Auteur ; Chul-Woong Cho, Auteur Année de publication : 2009 Article en page(s) : pp. 7283–7288 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ionic liquids 1-butyl-3-methylimidazolium chloride Sorption media Résumé : Ionic liquids have received an upsurge in interest as green solvents, primarily as replacements for conventional media in chemical processes. This growing interest may soon lead to their presence in the environment. To evaluate the environmental fate of ionic liquids, their sorption onto different media is an essential parameter. This study presents an experimental verification of the sorption of 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) onto different sorption media. The examined sorption media included two activated carbons (SPS-200 and SPC-100), an ion-exchange resin (IER), a fermentation waste (Corynebacterium glutamicum), and a dried activated sludge. Through HPLC and MS/MS analysis, [BMIM][Cl] was found to be stable only in the pH range 3 to 11. The experimental results reveal that removal of [BMIM][Cl] was only possible using IER and the two forms of activated carbon. The equilibrium solution pH was found to have no significant effect on the sorption ability of IER, whereas, both forms of activated carbon exhibited high sorption under strong alkaline conditions. No significant sorption of [BMIM] was observed with both C. glutamicum and the activated sludge. According to the Langmuir model, the IER can sorb as much as 179.4 mg [BMIM]/g, whereas those of SPS-200 and SPC-100 were 20.6 and 19.6 mg [BMIM]/g, respectively. The sorption kinetics was found to be rapid, with only 15 and 60 min required to attain equilibrium for IER and the two forms of activated carbon, respectively. Only IER exhibited significant sorption ability toward chloride ions which are an anionic part of the IL. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801825q
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7283–7288[article] An assessment on the interaction of a hydrophilic ionic liquid with different sorbents [texte imprimé] / K. Vijayaraghavan, Auteur ; Thi Phuong Thuy Pham, Auteur ; Chul-Woong Cho, Auteur . - 2009 . - pp. 7283–7288.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7283–7288
Mots-clés : Ionic liquids 1-butyl-3-methylimidazolium chloride Sorption media Résumé : Ionic liquids have received an upsurge in interest as green solvents, primarily as replacements for conventional media in chemical processes. This growing interest may soon lead to their presence in the environment. To evaluate the environmental fate of ionic liquids, their sorption onto different media is an essential parameter. This study presents an experimental verification of the sorption of 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) onto different sorption media. The examined sorption media included two activated carbons (SPS-200 and SPC-100), an ion-exchange resin (IER), a fermentation waste (Corynebacterium glutamicum), and a dried activated sludge. Through HPLC and MS/MS analysis, [BMIM][Cl] was found to be stable only in the pH range 3 to 11. The experimental results reveal that removal of [BMIM][Cl] was only possible using IER and the two forms of activated carbon. The equilibrium solution pH was found to have no significant effect on the sorption ability of IER, whereas, both forms of activated carbon exhibited high sorption under strong alkaline conditions. No significant sorption of [BMIM] was observed with both C. glutamicum and the activated sludge. According to the Langmuir model, the IER can sorb as much as 179.4 mg [BMIM]/g, whereas those of SPS-200 and SPC-100 were 20.6 and 19.6 mg [BMIM]/g, respectively. The sorption kinetics was found to be rapid, with only 15 and 60 min required to attain equilibrium for IER and the two forms of activated carbon, respectively. Only IER exhibited significant sorption ability toward chloride ions which are an anionic part of the IL. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801825q Exemplaires
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Titre : Extension of the mass transfer calculation for three-phase distillation in a packed column : nonequilibrium model based parameter estimation Type de document : texte imprimé Auteurs : Chen, Liang, Auteur ; Jens-Uwe Repke, Auteur ; Günter Wozny, Auteur Année de publication : 2009 Article en page(s) : pp. 7289–7300 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nonequilibrium modeling Three-phase distillation Packed column Résumé : Nonequilibrium (NEQ) modeling of three-phase (vapor−liquid−liquid) distillation in a packed column is still lacking of reliable correlations to calculate the interphase rate-based mass transfer. In this paper, extensions of the two most-used correlations [i.e., the Rocha correlation (Rocha, J. A.; Bravo, J. L.; Fair, J. R. Distillation Columns Containing Structured Packings: A Comprehensive Model for Their Performance. 2. Mass-Transfer Model. Ind. Eng. Chem. Res. 1996, 35, 1660) and the Billet and Schultes correlation (Billet, R.; Schultes, M. Prediction of Mass Transfer Columns with Dumped and Arranged Packings: Updated Summary of the Calculation Method of Billet & Schultes. Chem. Eng. Res. Des. 1999, 77, 498)] are proposed for mass transfer calculation of three-phase distillation in a packed column. Parameters used in the correlations are estimated on the basis of comprehensive experimental investigations on both two-phase (vapor−liquid) and three-phase distillation. The experimental database contains 150 different experiments of the 1-butanol/water/1-propanol system for different packings (Montz-Pak B1-350, Raschig Super-Ring 0.3, Rombopak 9M). The parameter estimation with multiple data sets and multipacking turns out to be a large-scale optimization problem subjected to a large number of nonlinear model equations. To reduce the problem dimension and remove coupling among the parameters, a hierarchical estimation strategy is proposed. The parameters are classified into packing-related and flow-related parameters, which are estimated using two-phase and three-phase distillation experimental data, respectively. In this way, the extension of mass transfer calculation for three-phase distillation is derived. Substantial improvements in the NEQ model prediction have been achieved. Compared with two-phase distillation, an increase of overall mass transfer ability is observed for the studied three-phase system. The extension of the mass transfer calculation can give a reasonable explanation for this observation, providing a better understanding of the intrinsic transfer phenomena inside three-phase packed columns. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900404p
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7289–7300[article] Extension of the mass transfer calculation for three-phase distillation in a packed column : nonequilibrium model based parameter estimation [texte imprimé] / Chen, Liang, Auteur ; Jens-Uwe Repke, Auteur ; Günter Wozny, Auteur . - 2009 . - pp. 7289–7300.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7289–7300
Mots-clés : Nonequilibrium modeling Three-phase distillation Packed column Résumé : Nonequilibrium (NEQ) modeling of three-phase (vapor−liquid−liquid) distillation in a packed column is still lacking of reliable correlations to calculate the interphase rate-based mass transfer. In this paper, extensions of the two most-used correlations [i.e., the Rocha correlation (Rocha, J. A.; Bravo, J. L.; Fair, J. R. Distillation Columns Containing Structured Packings: A Comprehensive Model for Their Performance. 2. Mass-Transfer Model. Ind. Eng. Chem. Res. 1996, 35, 1660) and the Billet and Schultes correlation (Billet, R.; Schultes, M. Prediction of Mass Transfer Columns with Dumped and Arranged Packings: Updated Summary of the Calculation Method of Billet & Schultes. Chem. Eng. Res. Des. 1999, 77, 498)] are proposed for mass transfer calculation of three-phase distillation in a packed column. Parameters used in the correlations are estimated on the basis of comprehensive experimental investigations on both two-phase (vapor−liquid) and three-phase distillation. The experimental database contains 150 different experiments of the 1-butanol/water/1-propanol system for different packings (Montz-Pak B1-350, Raschig Super-Ring 0.3, Rombopak 9M). The parameter estimation with multiple data sets and multipacking turns out to be a large-scale optimization problem subjected to a large number of nonlinear model equations. To reduce the problem dimension and remove coupling among the parameters, a hierarchical estimation strategy is proposed. The parameters are classified into packing-related and flow-related parameters, which are estimated using two-phase and three-phase distillation experimental data, respectively. In this way, the extension of mass transfer calculation for three-phase distillation is derived. Substantial improvements in the NEQ model prediction have been achieved. Compared with two-phase distillation, an increase of overall mass transfer ability is observed for the studied three-phase system. The extension of the mass transfer calculation can give a reasonable explanation for this observation, providing a better understanding of the intrinsic transfer phenomena inside three-phase packed columns. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900404p Exemplaires
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Titre : Adsorption behavior of a mixture of C13 isomers onto a fixed-bed of H-ZSM-5 Type de document : texte imprimé Auteurs : M. A. Uguina, Auteur ; Sotelo, J. L., Auteur ; J. A. Delgado, Auteur Année de publication : 2009 Article en page(s) : pp. 7301–7307 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Liquid-phase adsorption C13 Isomers Fixed bed H-ZSM-5 (Si/Al = 200) Breakthrough curves Résumé : Multicomponent liquid-phase adsorption of C13 paraffins (mainly monomethyldodecanes and tridecane) onto a fixed bed of H-ZSM-5 (Si/Al = 200) has been studied (428 K and 21 barg), obtaining complete breakthrough curves for all the solutes, in order to ensure that equilibrium between the liquid feed and the adsorbent was achieved. The concentration of adsorbates in the feed mixture has been varied by diluting a concentrated mixture of C13 paraffins with a nonadsorbing solvent (2,2,4-trimethylpentane) in different proportions. The relationship between the branching position of the isomer and its adsorption affinity has been studied. The following affinity order is obtained (estimated as adsorbed concentration/liquid concentration): 2-MC12 ≈ 3-MC12 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900419k
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7301–7307[article] Adsorption behavior of a mixture of C13 isomers onto a fixed-bed of H-ZSM-5 [texte imprimé] / M. A. Uguina, Auteur ; Sotelo, J. L., Auteur ; J. A. Delgado, Auteur . - 2009 . - pp. 7301–7307.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7301–7307
Mots-clés : Liquid-phase adsorption C13 Isomers Fixed bed H-ZSM-5 (Si/Al = 200) Breakthrough curves Résumé : Multicomponent liquid-phase adsorption of C13 paraffins (mainly monomethyldodecanes and tridecane) onto a fixed bed of H-ZSM-5 (Si/Al = 200) has been studied (428 K and 21 barg), obtaining complete breakthrough curves for all the solutes, in order to ensure that equilibrium between the liquid feed and the adsorbent was achieved. The concentration of adsorbates in the feed mixture has been varied by diluting a concentrated mixture of C13 paraffins with a nonadsorbing solvent (2,2,4-trimethylpentane) in different proportions. The relationship between the branching position of the isomer and its adsorption affinity has been studied. The following affinity order is obtained (estimated as adsorbed concentration/liquid concentration): 2-MC12 ≈ 3-MC12 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900419k Exemplaires
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Titre : Silica materials doped with bifunctional ionic liquid extractant for yttrium extraction Type de document : texte imprimé Auteurs : Yinghui Liu, Auteur ; Lili Zhu, Auteur ; Xiaoqi Sun, Auteur Année de publication : 2009 Article en page(s) : pp. 7308–7313 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Silica-based organic-inorganic hybrid materials Binary mixture Ionic liquids Résumé : Two new silica-based organic−inorganic hybrid materials (B104SGs and O104SGs) doped with a binary mixture of imidazolium and phosphonium ionic liquids have been synthesized and used as sorbents in batch system for rare earths (RE) separation. Imidazolium ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate (C4mim+PF6−) or 1-octyl-3-methylimidazolium hexafluorophosphate (C8mim+PF6−) acted as porogens to prepare porous materials and additives to stabilize extractant within silica gel. Trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate (Cyphos IL 104), a low-molecular-mass organic gelator, can encourage the formation of porous silica materials and increase the rate of aggregation. Cyphos IL 104 not only acted as an excellent template for the preparation of silica sorbents but also as a bifunctional ionic liquid extractant (bif-ILE) for RE(III) extraction. By the electrostatic attraction between the SiO- groups and phosphonium cations along the surfaces of the silica gel, stable silica sorbents with high extractant content were formed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900468c
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7308–7313[article] Silica materials doped with bifunctional ionic liquid extractant for yttrium extraction [texte imprimé] / Yinghui Liu, Auteur ; Lili Zhu, Auteur ; Xiaoqi Sun, Auteur . - 2009 . - pp. 7308–7313.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7308–7313
Mots-clés : Silica-based organic-inorganic hybrid materials Binary mixture Ionic liquids Résumé : Two new silica-based organic−inorganic hybrid materials (B104SGs and O104SGs) doped with a binary mixture of imidazolium and phosphonium ionic liquids have been synthesized and used as sorbents in batch system for rare earths (RE) separation. Imidazolium ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate (C4mim+PF6−) or 1-octyl-3-methylimidazolium hexafluorophosphate (C8mim+PF6−) acted as porogens to prepare porous materials and additives to stabilize extractant within silica gel. Trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate (Cyphos IL 104), a low-molecular-mass organic gelator, can encourage the formation of porous silica materials and increase the rate of aggregation. Cyphos IL 104 not only acted as an excellent template for the preparation of silica sorbents but also as a bifunctional ionic liquid extractant (bif-ILE) for RE(III) extraction. By the electrostatic attraction between the SiO- groups and phosphonium cations along the surfaces of the silica gel, stable silica sorbents with high extractant content were formed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900468c Exemplaires
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Titre : Hollow fiber adsorbents for CO2 removal from flue gas Type de document : texte imprimé Auteurs : Ryan P. Lively, Auteur ; Ronald R. Chance, Auteur ; B. T. Kelley, Auteur Année de publication : 2009 Article en page(s) : pp. 7314–7324 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hollow polymeric fibers Sorbent particles Porous fiber CO2 capture Rapid temperature swing adsorption system Résumé : The nation’s pulverized coal infrastructure is aging, and implementation of current retrofit postcombustion capture methods is extremely expensive. This paper describes a technology based on hollow polymeric fibers with sorbent particles embedded in the porous fiber wall to enable postcombustion CO2 capture via a rapid temperature swing adsorption (RTSA) system. The system takes advantage of the hollow fiber morphology by passing cooling water through the bores during sorption to maximize sorption capacities and steam through the bores during desorption to desorb CO2 efficiently. The thin-walled hollow fibers offer the advantage of rapid heat and mass transport. To avoid mass transfer between the core and the fiber sheath, a dense lumen layer is used on the interior of the fiber wall. This system has advantages over competing technologies. Specifically, the fiber sorbent contactor minimizes flue gas pressure drop across the bed, while maximizing sorption efficiencies via rapid thermal cycles and low regenerative thermal requirements. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005244
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7314–7324[article] Hollow fiber adsorbents for CO2 removal from flue gas [texte imprimé] / Ryan P. Lively, Auteur ; Ronald R. Chance, Auteur ; B. T. Kelley, Auteur . - 2009 . - pp. 7314–7324.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7314–7324
Mots-clés : Hollow polymeric fibers Sorbent particles Porous fiber CO2 capture Rapid temperature swing adsorption system Résumé : The nation’s pulverized coal infrastructure is aging, and implementation of current retrofit postcombustion capture methods is extremely expensive. This paper describes a technology based on hollow polymeric fibers with sorbent particles embedded in the porous fiber wall to enable postcombustion CO2 capture via a rapid temperature swing adsorption (RTSA) system. The system takes advantage of the hollow fiber morphology by passing cooling water through the bores during sorption to maximize sorption capacities and steam through the bores during desorption to desorb CO2 efficiently. The thin-walled hollow fibers offer the advantage of rapid heat and mass transport. To avoid mass transfer between the core and the fiber sheath, a dense lumen layer is used on the interior of the fiber wall. This system has advantages over competing technologies. Specifically, the fiber sorbent contactor minimizes flue gas pressure drop across the bed, while maximizing sorption efficiencies via rapid thermal cycles and low regenerative thermal requirements. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005244 Exemplaires
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Titre : Assessment of options for selective 1-butanol recovery from aqueous solution Type de document : texte imprimé Auteurs : Arjan Oudshoorn, Auteur ; Van der Wielen, Luuk A. M., Auteur ; Straathof, Adrie J. J., Auteur Année de publication : 2009 Article en page(s) : pp. 7325–7336 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : 1-butanol Butanol recovery methodsAqueous fermentation Efficient Résumé : The microbial production of 1-butanol occurs in aqueous fermentation broth, with up to ∼20 g/L of product. Efficient recovery of butanol from this dilute aqueous phase determines, to a large extent, the efficiency of the production process. Starting from the thermodynamic (phase) properties of butanol and water systems, this paper presents a structured approach to determine the key characteristics of various butanol recovery methods. Analysis of reported separations, combined with fundamental phase properties, has resulted in both the characterization of the selectivity of recovery and estimations of the energy requirement during product recovery for a variety of recovery methods. Energy-efficient systems for the recovery of butanol from aqueous solution are pervaporation- and adsorption-based techniques. The applied method predicts the recovery energy requirement for both techniques to be En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900537w
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7325–7336[article] Assessment of options for selective 1-butanol recovery from aqueous solution [texte imprimé] / Arjan Oudshoorn, Auteur ; Van der Wielen, Luuk A. M., Auteur ; Straathof, Adrie J. J., Auteur . - 2009 . - pp. 7325–7336.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7325–7336
Mots-clés : 1-butanol Butanol recovery methodsAqueous fermentation Efficient Résumé : The microbial production of 1-butanol occurs in aqueous fermentation broth, with up to ∼20 g/L of product. Efficient recovery of butanol from this dilute aqueous phase determines, to a large extent, the efficiency of the production process. Starting from the thermodynamic (phase) properties of butanol and water systems, this paper presents a structured approach to determine the key characteristics of various butanol recovery methods. Analysis of reported separations, combined with fundamental phase properties, has resulted in both the characterization of the selectivity of recovery and estimations of the energy requirement during product recovery for a variety of recovery methods. Energy-efficient systems for the recovery of butanol from aqueous solution are pervaporation- and adsorption-based techniques. The applied method predicts the recovery energy requirement for both techniques to be En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900537w Exemplaires
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Titre : An experimental study of the GAMS/AlphaECP MINLP solver Type de document : texte imprimé Auteurs : Toni Lastusilta, Auteur ; Michael R. Bussieck, Auteur ; Tapio Westerlund, Auteur Année de publication : 2009 Article en page(s) : pp. 7337–7345 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Mixed-integer nonlinear programming problems General algebraic modeling system GAMS/AlphaECP Résumé : The development of methods to solve mixed-integer nonlinear programming (MINLP) problems has given rise to new solvers and improved the current ones. In this Article, the focus is set on the MINLP solvers in the General Algebraic Modeling System (GAMS) and especially GAMS/AlphaECP. In this Article, a comprehensive comparison of the MINLP solvers is made. In June 2007, GAMS introduced new MINLP solvers: CoinBonmin, AlphaECP, and LINDOGlobal. A description of the improvements made in the second half of 2007 to AlphaECP is given, and the performance of the MINLP solvers in GAMS is examined. Furthermore, the performance of AlphaECP for both MINLP and nonlinear programming (NLP) problems is studied, in conjunction with different subsolvers. Two large collections of problems, MINLPLib and GLOBALLib, are used for all solver performance comparisons. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801378n
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7337–7345[article] An experimental study of the GAMS/AlphaECP MINLP solver [texte imprimé] / Toni Lastusilta, Auteur ; Michael R. Bussieck, Auteur ; Tapio Westerlund, Auteur . - 2009 . - pp. 7337–7345.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7337–7345
Mots-clés : Mixed-integer nonlinear programming problems General algebraic modeling system GAMS/AlphaECP Résumé : The development of methods to solve mixed-integer nonlinear programming (MINLP) problems has given rise to new solvers and improved the current ones. In this Article, the focus is set on the MINLP solvers in the General Algebraic Modeling System (GAMS) and especially GAMS/AlphaECP. In this Article, a comprehensive comparison of the MINLP solvers is made. In June 2007, GAMS introduced new MINLP solvers: CoinBonmin, AlphaECP, and LINDOGlobal. A description of the improvements made in the second half of 2007 to AlphaECP is given, and the performance of the MINLP solvers in GAMS is examined. Furthermore, the performance of AlphaECP for both MINLP and nonlinear programming (NLP) problems is studied, in conjunction with different subsolvers. Two large collections of problems, MINLPLib and GLOBALLib, are used for all solver performance comparisons. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801378n Exemplaires
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Titre : Optimization of enzymatic hydrolysis of wheat straw pretreated by alkaline peroxide using response surface methodology Type de document : texte imprimé Auteurs : Benkun Qi, Auteur ; Xiangrong Chen, Auteur ; Fei Shen, Auteur Année de publication : 2009 Article en page(s) : pp. 7346–7353 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Biomass-wheat straw Enzymatic saccharification process Alkaline peroxide Résumé : To optimize the enzymatic conversion of widely available lignocellulosic biomass-wheat straw (WS), pretreatment facilitating the enzymatic saccharification process was first performed by alkaline peroxide, resulting in a substrate consisting of 60.17% cellulose, 29.53% hemicelluloses, and 4.59% lignin. Using response surface methodology, the combined effects of enzyme loading, substrate concentration, surfactant concentration, and reaction time on hydrolysis yield from enzymatic saccharification of WS were further investigated. The results showed that both enzyme loading and substrate concentration had interactions with surfactant concentration. A quadratic polynomial equation for predicting the hydrolysis yield was developed. The experimental results were in good agreement with predicted values. Therefore, the model could be successfully used to identify the effective combinations of the four factors for predicting hydrolysis yield. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016863
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7346–7353[article] Optimization of enzymatic hydrolysis of wheat straw pretreated by alkaline peroxide using response surface methodology [texte imprimé] / Benkun Qi, Auteur ; Xiangrong Chen, Auteur ; Fei Shen, Auteur . - 2009 . - pp. 7346–7353.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7346–7353
Mots-clés : Biomass-wheat straw Enzymatic saccharification process Alkaline peroxide Résumé : To optimize the enzymatic conversion of widely available lignocellulosic biomass-wheat straw (WS), pretreatment facilitating the enzymatic saccharification process was first performed by alkaline peroxide, resulting in a substrate consisting of 60.17% cellulose, 29.53% hemicelluloses, and 4.59% lignin. Using response surface methodology, the combined effects of enzyme loading, substrate concentration, surfactant concentration, and reaction time on hydrolysis yield from enzymatic saccharification of WS were further investigated. The results showed that both enzyme loading and substrate concentration had interactions with surfactant concentration. A quadratic polynomial equation for predicting the hydrolysis yield was developed. The experimental results were in good agreement with predicted values. Therefore, the model could be successfully used to identify the effective combinations of the four factors for predicting hydrolysis yield. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016863 Exemplaires
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Titre : Partition coefficients of methyl methacrylate and acetone between polymer and compressed carbon dioxide phases by an in situ infrared spectroscopy method Type de document : texte imprimé Auteurs : Jun He, Auteur ; Bo Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 7354–7358 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Methyl methacrylate Acetone Polymer gaseous carbon dioxide phase Compressed Partition coefficients Fourier transform infrared spectroscopy method Résumé : Partition coefficients of methyl methacrylate and acetone between some polymer and compressed gaseous carbon dioxide phases were determined by an in situ Fourier transform infrared (FTIR) spectroscopy method with a special designed high pressure IR cell at 318.2 K and 2.0−7.0 MPa. At the same temperature and pressure, the partition coefficient for methyl methacrylate was higher than that for acetone between the same polymer and subcritical carbon dioxide. For most solute/polymer/CO2 systems, the partition coefficient of solute between the polymer and compressed gaseous carbon dioxide decreased with the pressure increase. Only for a methyl methacrylate/poly(methyl methacrylate)/CO2 system, the partiton coefficient was not sensitive to the pressure change at pressures lower than 3.9 MPa. A linear solvation free energy relationship was used to estimate the main tendency of the pressure dependency. With the pressure dependent polarizability−dipolarity parameter of carbon dioxide, the calculated results were in accord with some experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801824y
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7354–7358[article] Partition coefficients of methyl methacrylate and acetone between polymer and compressed carbon dioxide phases by an in situ infrared spectroscopy method [texte imprimé] / Jun He, Auteur ; Bo Wang, Auteur . - 2009 . - pp. 7354–7358.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7354–7358
Mots-clés : Methyl methacrylate Acetone Polymer gaseous carbon dioxide phase Compressed Partition coefficients Fourier transform infrared spectroscopy method Résumé : Partition coefficients of methyl methacrylate and acetone between some polymer and compressed gaseous carbon dioxide phases were determined by an in situ Fourier transform infrared (FTIR) spectroscopy method with a special designed high pressure IR cell at 318.2 K and 2.0−7.0 MPa. At the same temperature and pressure, the partition coefficient for methyl methacrylate was higher than that for acetone between the same polymer and subcritical carbon dioxide. For most solute/polymer/CO2 systems, the partition coefficient of solute between the polymer and compressed gaseous carbon dioxide decreased with the pressure increase. Only for a methyl methacrylate/poly(methyl methacrylate)/CO2 system, the partiton coefficient was not sensitive to the pressure change at pressures lower than 3.9 MPa. A linear solvation free energy relationship was used to estimate the main tendency of the pressure dependency. With the pressure dependent polarizability−dipolarity parameter of carbon dioxide, the calculated results were in accord with some experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801824y Exemplaires
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Titre : The temperature, cosolvent, and blending effects on the partitions between polymer and compressed carbon dioxide Type de document : texte imprimé Auteurs : Jun He, Auteur ; Bo Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 7359–7363 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Methyl methacrylate Poly(methyl methacrylate) Compressed gaseous carbon dioxide Cosolvent effect Résumé : In this work, the temperature influence and blending effect on the partition of methyl methacrylate between poly(methyl methacrylate) and compressed gaseous carbon dioxide were investigated; the cosolvent effect of ethanol on the partition of acetone between poly(carbonate biphenol A) and compressed gaseous carbon dioxide was also studied by using an in situ IR spectroscopy method at fluid pressure lower than 7.0 MPa. The temperature increase and the cosolvent addition decreased the partition coefficient of solute between polymer and compressed gaseous carbon dioxide. Interestingly the blending of the polymers increased the partition coefficient, and the distribution of methyl methacrylate between the poly(methyl methacrylate)/poly(vinylidene fluoride) complex and compressed gaseous CO2 was not a simple additive of the distribution of the two separate at a pressure lower than 6.0 MPa. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801832v
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7359–7363[article] The temperature, cosolvent, and blending effects on the partitions between polymer and compressed carbon dioxide [texte imprimé] / Jun He, Auteur ; Bo Wang, Auteur . - 2009 . - pp. 7359–7363.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7359–7363
Mots-clés : Methyl methacrylate Poly(methyl methacrylate) Compressed gaseous carbon dioxide Cosolvent effect Résumé : In this work, the temperature influence and blending effect on the partition of methyl methacrylate between poly(methyl methacrylate) and compressed gaseous carbon dioxide were investigated; the cosolvent effect of ethanol on the partition of acetone between poly(carbonate biphenol A) and compressed gaseous carbon dioxide was also studied by using an in situ IR spectroscopy method at fluid pressure lower than 7.0 MPa. The temperature increase and the cosolvent addition decreased the partition coefficient of solute between polymer and compressed gaseous carbon dioxide. Interestingly the blending of the polymers increased the partition coefficient, and the distribution of methyl methacrylate between the poly(methyl methacrylate)/poly(vinylidene fluoride) complex and compressed gaseous CO2 was not a simple additive of the distribution of the two separate at a pressure lower than 6.0 MPa. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801832v Exemplaires
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Titre : Incompatibility of fischer-tropsch diesel with petroleum and soybean biodiesel blends Type de document : texte imprimé Auteurs : George W. Mushrush, Auteur ; Heather D. Willauer, Auteur ; Joy W. Bauserman, Auteur Année de publication : 2009 Article en page(s) : pp. 7364–7367 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Middle distillate fuels Fischer-tropsch diesel Natural gas Coal Résumé : The Department of Defense is the largest consumer of middle distillate fuels. It has been recommended that alternative fuel sources be considered as replacements or blending stocks for middle distillate ground transportation and marine fuels. Therefore, the search for suitable replacements or blending stocks is earnestly continuing. Renewable agricultural crops such as soybeans and others are now in the forefront. Nonrenewable synthetic fuels such as those produced by Fischer−Tropsch, FT, synthesis from coal and natural gas have been suggested. It is probable that several of these substitutes would be simultaneously blended into a middle distillate petroleum based diesel fuel. Care must be employed when blending fuels so that fuel specifications and storage stability are not decreased. This paper compares the storage stability of a three-part mixture consisting of Fischer−Tropsch diesel, a petroleum diesel, and a 5% and 10% soy biodiesel under ambient conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801867t
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7364–7367[article] Incompatibility of fischer-tropsch diesel with petroleum and soybean biodiesel blends [texte imprimé] / George W. Mushrush, Auteur ; Heather D. Willauer, Auteur ; Joy W. Bauserman, Auteur . - 2009 . - pp. 7364–7367.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7364–7367
Mots-clés : Middle distillate fuels Fischer-tropsch diesel Natural gas Coal Résumé : The Department of Defense is the largest consumer of middle distillate fuels. It has been recommended that alternative fuel sources be considered as replacements or blending stocks for middle distillate ground transportation and marine fuels. Therefore, the search for suitable replacements or blending stocks is earnestly continuing. Renewable agricultural crops such as soybeans and others are now in the forefront. Nonrenewable synthetic fuels such as those produced by Fischer−Tropsch, FT, synthesis from coal and natural gas have been suggested. It is probable that several of these substitutes would be simultaneously blended into a middle distillate petroleum based diesel fuel. Care must be employed when blending fuels so that fuel specifications and storage stability are not decreased. This paper compares the storage stability of a three-part mixture consisting of Fischer−Tropsch diesel, a petroleum diesel, and a 5% and 10% soy biodiesel under ambient conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801867t Exemplaires
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Titre : Mechanistic studies in ultrasound-assisted adsorption for removal of aromatic pollutants Type de document : texte imprimé Auteurs : Venkata Rao Midathana, Auteur ; Vijayanand S. Moholkar, Auteur Année de publication : 2009 Article en page(s) : pp. 7368–7377 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Organic pollutants Ultrasound Adsorption Résumé : In this paper we try to discern the physical mechanism of enhancement of adsorption of organic pollutants with application of ultrasound. An attempt is made to discriminate between the contribution made by various physical effects of ultrasound and cavitation, viz., microstreaming, microturbulence, and acoustic (or shock) waves, which could generate convection in the medium and enhance the process of adsorption. A dual approach of coupling experimental results to the simulations of a bubble dynamics model has been adopted. Adsorption of three aromatic pollutants (viz., nitrobenzene, phenol, and p-nitrophenol) onto activated carbon has been chosen as a model process. Correlation of the experimental and simulation results reveals that the extent of adsorption in the presence of ultrasound shows an optimum with the intensity of convection generated in the medium by the cavitation bubbles. The microturbulence generated by cavitation bubbles makes a useful contribution to the enhancement of adsorption. This is attributed to the continuous nature of microturbulence with moderate liquid velocities. On the other hand, acoustic waves emitted by the cavitation bubbles render an adverse effect on the process. This is attributed to the discrete nature and high pressure amplitude of the waves, which create excessively high convection in the medium, causing desorption of the pollutant. The chemical nature of the pollutant is also found to influence the enhancement effect of ultrasound. For hydrophobic pollutants, the ultrasonic enhancement is more pronounced than for hydrophilic pollutants under otherwise similar conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900049e
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7368–7377[article] Mechanistic studies in ultrasound-assisted adsorption for removal of aromatic pollutants [texte imprimé] / Venkata Rao Midathana, Auteur ; Vijayanand S. Moholkar, Auteur . - 2009 . - pp. 7368–7377.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7368–7377
Mots-clés : Organic pollutants Ultrasound Adsorption Résumé : In this paper we try to discern the physical mechanism of enhancement of adsorption of organic pollutants with application of ultrasound. An attempt is made to discriminate between the contribution made by various physical effects of ultrasound and cavitation, viz., microstreaming, microturbulence, and acoustic (or shock) waves, which could generate convection in the medium and enhance the process of adsorption. A dual approach of coupling experimental results to the simulations of a bubble dynamics model has been adopted. Adsorption of three aromatic pollutants (viz., nitrobenzene, phenol, and p-nitrophenol) onto activated carbon has been chosen as a model process. Correlation of the experimental and simulation results reveals that the extent of adsorption in the presence of ultrasound shows an optimum with the intensity of convection generated in the medium by the cavitation bubbles. The microturbulence generated by cavitation bubbles makes a useful contribution to the enhancement of adsorption. This is attributed to the continuous nature of microturbulence with moderate liquid velocities. On the other hand, acoustic waves emitted by the cavitation bubbles render an adverse effect on the process. This is attributed to the discrete nature and high pressure amplitude of the waves, which create excessively high convection in the medium, causing desorption of the pollutant. The chemical nature of the pollutant is also found to influence the enhancement effect of ultrasound. For hydrophobic pollutants, the ultrasonic enhancement is more pronounced than for hydrophilic pollutants under otherwise similar conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900049e Exemplaires
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Titre : QSPR flash point prediction of solvents using topological indices for application in computer aided molecular design Type de document : texte imprimé Auteurs : Suhani J. Patel, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur Année de publication : 2009 Article en page(s) : pp. 7378–7387 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solvents Computer aided molecular design Quantitative structure property relationship Topological indices Résumé : Incorporating consideration for safety issues while selecting solvents for processes has become crucial in light of the chemical process accidents involving solvents that have taken place in recent years. Computer aided molecular design (CAMD) is a methodology that has been researched recently for designing compounds with required target properties and can be applied for selection of safer solvents as well. An important aspect of this methodology concerns the prediction of properties given the structure of the molecule. This paper utilizes one such emerging method for prediction of a hazardous property, flash point, which is indicative of the flammability of solvents. Quantitative structure property relationship (QSPR) and topological indices have been used in this paper to predict flash point properties of different classes of solvents. Multiple linear regression and back-propagation neural network analysis were used to model the flash point. The neural network model showed higher accuracy (training set, r = 0.948, R2 = 0.898). However, there are certain limitations associated with using QSPR in CAMD which have been discussed and need further work. This paper advances the “forward problem” of CAMD using QSPR which has not been researched extensively in the past. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9000794
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7378–7387[article] QSPR flash point prediction of solvents using topological indices for application in computer aided molecular design [texte imprimé] / Suhani J. Patel, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur . - 2009 . - pp. 7378–7387.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7378–7387
Mots-clés : Solvents Computer aided molecular design Quantitative structure property relationship Topological indices Résumé : Incorporating consideration for safety issues while selecting solvents for processes has become crucial in light of the chemical process accidents involving solvents that have taken place in recent years. Computer aided molecular design (CAMD) is a methodology that has been researched recently for designing compounds with required target properties and can be applied for selection of safer solvents as well. An important aspect of this methodology concerns the prediction of properties given the structure of the molecule. This paper utilizes one such emerging method for prediction of a hazardous property, flash point, which is indicative of the flammability of solvents. Quantitative structure property relationship (QSPR) and topological indices have been used in this paper to predict flash point properties of different classes of solvents. Multiple linear regression and back-propagation neural network analysis were used to model the flash point. The neural network model showed higher accuracy (training set, r = 0.948, R2 = 0.898). However, there are certain limitations associated with using QSPR in CAMD which have been discussed and need further work. This paper advances the “forward problem” of CAMD using QSPR which has not been researched extensively in the past. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9000794 Exemplaires
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Titre : Thermochemical and Ab initio studies of biodiesel fuel surrogates : 1,2,3-propanetriol triacetate, 1,2-ethanediol diacetate, and 1,2-ethanediol monoacetate Type de document : texte imprimé Auteurs : Sergey P. Verevkin, Auteur ; Vladimir N. Emel'yanenko, Auteur ; Alexey V. Tkachev, Auteur Année de publication : 2009 Article en page(s) : pp. 7388–7399 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ethanediol acetate Propanetriol Biodiesel FuelAb initio calculations Résumé : This work has been undertaken to obtain new thermochemical data for ethanediol and propanetriol acetates and to improve the group contribution methodology for the prediction of the thermodynamic properties of compounds relevant to biodiesel. Standard molar enthalpies of formation in the gaseous state of a series of 1,2-ethanediol monoacetate, 1,2-ethanediol diacetate, and 1,2,3-propanetriol triacetate have been obtained from combustion calorimetry and results from the temperature dependence of the vapor pressure measured by the transpiration method. To verify the experimental data, ab initio calculations of all compounds have been performed. Enthalpies of formation derived from the Gaussian 03 second-order Møller−Plesset (G3MP2) method are in good agreement with the experimental results. The strength of the hydrogen bond in 1,2-ethanediol monoacetate and in 1,2-ethanediol have been obtained using ab initio calculations and the group additivity method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900308u
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7388–7399[article] Thermochemical and Ab initio studies of biodiesel fuel surrogates : 1,2,3-propanetriol triacetate, 1,2-ethanediol diacetate, and 1,2-ethanediol monoacetate [texte imprimé] / Sergey P. Verevkin, Auteur ; Vladimir N. Emel'yanenko, Auteur ; Alexey V. Tkachev, Auteur . - 2009 . - pp. 7388–7399.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7388–7399
Mots-clés : Ethanediol acetate Propanetriol Biodiesel FuelAb initio calculations Résumé : This work has been undertaken to obtain new thermochemical data for ethanediol and propanetriol acetates and to improve the group contribution methodology for the prediction of the thermodynamic properties of compounds relevant to biodiesel. Standard molar enthalpies of formation in the gaseous state of a series of 1,2-ethanediol monoacetate, 1,2-ethanediol diacetate, and 1,2,3-propanetriol triacetate have been obtained from combustion calorimetry and results from the temperature dependence of the vapor pressure measured by the transpiration method. To verify the experimental data, ab initio calculations of all compounds have been performed. Enthalpies of formation derived from the Gaussian 03 second-order Møller−Plesset (G3MP2) method are in good agreement with the experimental results. The strength of the hydrogen bond in 1,2-ethanediol monoacetate and in 1,2-ethanediol have been obtained using ab initio calculations and the group additivity method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900308u Exemplaires
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Titre : High reactivity and mechanical durability of NiO/NiAl2O4 and NiO/NiAl2O4/MgAl2O4 oxygen carrier particles used for more than 1000 h in a 10 kW CLC reactor Type de document : texte imprimé Auteurs : Alexander Shulman, Auteur ; Carl Linderholm, Auteur ; Tobias Mattisson, Auteur Année de publication : 2009 Article en page(s) : pp. 7400–7405 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Chemical-looping combustion Oxygen carrier materials Résumé : Chemical-looping combustion (CLC) is a promising technology for CO2 capture in the process of combustion of gaseous fossil fuels. Oxygen carrier materials based on Ni/NiO on NiAl2O4 and on NiAl2O4/MgAl2O4 support have previously shown high initial activity combined with high conversion of methane and low concentration of outgoing CO. The feasibility of the Ni/NiO system for CLC depends largely on the lifetime of the oxygen carrier particles in the reactor due to the high price of the material. Avoiding chemical and physical degradation of oxygen carriers is essential for long-term industrial-scale chemical-looping combustion operations, and the particles’ activity and mechanical durability have to remain high during long operation times. In this study, a series of oxygen carrier samples were collected from a 10 kW CLC combustor operated for a total of 1016 h using oxygen carrier materials based on NiO/NiAl2O4 (N-VITO) for 405 h and a mixture of used NiO/NiAl2O4 with fresh NiO/NiAl2O4/MgAl2O4 (N-VITOMg) for 611 h, respectively. These samples were collected after certain time intervals and analyzed in terms of reactivity with methane in a quartz batch reactor. Also, the structural and mechanical properties of these samples were investigated by means of powder XRD, BET surface area measurements, light and scanning electron microscopy, energy dispersive X-ray spectrometry, and crushing strength evaluation. It was shown that both N-VITO and N-VITO/N-VITOMg demonstrate high reactivity and mechanical durability after having been used for more than 1000 h in the CLC 10 kW reactor, which makes them excellent candidates for applications within the area of chemical-looping combustion. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900342f
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7400–7405[article] High reactivity and mechanical durability of NiO/NiAl2O4 and NiO/NiAl2O4/MgAl2O4 oxygen carrier particles used for more than 1000 h in a 10 kW CLC reactor [texte imprimé] / Alexander Shulman, Auteur ; Carl Linderholm, Auteur ; Tobias Mattisson, Auteur . - 2009 . - pp. 7400–7405.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7400–7405
Mots-clés : Chemical-looping combustion Oxygen carrier materials Résumé : Chemical-looping combustion (CLC) is a promising technology for CO2 capture in the process of combustion of gaseous fossil fuels. Oxygen carrier materials based on Ni/NiO on NiAl2O4 and on NiAl2O4/MgAl2O4 support have previously shown high initial activity combined with high conversion of methane and low concentration of outgoing CO. The feasibility of the Ni/NiO system for CLC depends largely on the lifetime of the oxygen carrier particles in the reactor due to the high price of the material. Avoiding chemical and physical degradation of oxygen carriers is essential for long-term industrial-scale chemical-looping combustion operations, and the particles’ activity and mechanical durability have to remain high during long operation times. In this study, a series of oxygen carrier samples were collected from a 10 kW CLC combustor operated for a total of 1016 h using oxygen carrier materials based on NiO/NiAl2O4 (N-VITO) for 405 h and a mixture of used NiO/NiAl2O4 with fresh NiO/NiAl2O4/MgAl2O4 (N-VITOMg) for 611 h, respectively. These samples were collected after certain time intervals and analyzed in terms of reactivity with methane in a quartz batch reactor. Also, the structural and mechanical properties of these samples were investigated by means of powder XRD, BET surface area measurements, light and scanning electron microscopy, energy dispersive X-ray spectrometry, and crushing strength evaluation. It was shown that both N-VITO and N-VITO/N-VITOMg demonstrate high reactivity and mechanical durability after having been used for more than 1000 h in the CLC 10 kW reactor, which makes them excellent candidates for applications within the area of chemical-looping combustion. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900342f Exemplaires
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Titre : New neural network group contribution model for estimation of lower flammability limit temperature of pure compounds Type de document : texte imprimé Auteurs : Farhad Gharagheizi, Auteur Année de publication : 2009 Article en page(s) : pp. 7406–7416 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Neural network method Pure compounds Lower flammability limit temperature Résumé : In the present study, a group contribution based neural network method is developed to predict the lower flammability limit temperature (LFLT) of pure compounds. The needed parameters of the model are the occurrences of 125 functional groups in every molecule. The average absolute deviation error obtained over 1429 pure compounds used in this study is 2.35%. Therefore, the model is an accurate model and can be used to predict the LFLT of a wide range of pure compounds. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9003738
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7406–7416[article] New neural network group contribution model for estimation of lower flammability limit temperature of pure compounds [texte imprimé] / Farhad Gharagheizi, Auteur . - 2009 . - pp. 7406–7416.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7406–7416
Mots-clés : Neural network method Pure compounds Lower flammability limit temperature Résumé : In the present study, a group contribution based neural network method is developed to predict the lower flammability limit temperature (LFLT) of pure compounds. The needed parameters of the model are the occurrences of 125 functional groups in every molecule. The average absolute deviation error obtained over 1429 pure compounds used in this study is 2.35%. Therefore, the model is an accurate model and can be used to predict the LFLT of a wide range of pure compounds. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9003738 Exemplaires
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Titre : Application of the Flory theory and of the Kirkwod-Buff formalism to the study of orientational effects in 1-alkanol + linear or cyclic monoether mixtures Type de document : texte imprimé Auteurs : Juan Antonio Gonzalez, Auteur ; Nicolás Riesco, Auteur ; Ismael Mozo, Auteur Année de publication : 2009 Article en page(s) : pp. 7417–7429 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Orientational effects 1-alkanols Cyclic monoethers Flory mode Kirkwood− Buff formalism Résumé : Orientational effects present in binary mixtures of 1-alkanols with linear or cyclic monoethers have been studied using the Flory model and the Kirkwood−Buff formalism. The alcohols considered are those from methanol to 1-decanol, and the ethers are the following: dimethylether (DME), diethylether (DEE), dipropylether (DPE), dibutylether (DBE), tetrahydrofuran (THF), and tetrahydropyran (THP). In terms of the Flory model, orientational effects have been investigated by analyzing the concentration dependence of the interaction parameter, X12, and comparing the deviations obtained between experimental molar excess enthalpies, HmE, and calculated values with an X12 parameter determined from HmE measurements at equimolar composition. Due to the facts that structural effects are relevant for many of the considered mixtures and their excess molar volumes, VmE, are negative, we have also determined the excess molar internal energies, UV,mE, and X12 parameters from these data. From the X12 variation with the alkanol size, we have shown than interactions between unlike molecules are nearly constant along a homologous series with a given ether. In the framework of the Kirkwood−Buff theory, the study has been developed through the Kirkwood−Buff integrals and related local mole fractions, obtained from vapor−liquid equilibria and VmE data available in the literature. Ideal compressibilities for the mixtures were assumed. Although the Flory model does not describe the complex structural effects present in the investigated mixtures and fails when predicting VmE, both theories provide consistent results on the orientational effects in these solutions. In addition, the results are in agreement with those previously obtained from the ERAS model. Systems involving linear monoethers are mainly characterized by orientational effects related to the self-association of the alcohol, in such way that the mentioned effects decrease when the size of the alcohol is increased in solutions with a given ether. Orientational effects become more relevant when the chain length of the linear monoether mixed with a fixed 1-alkanol increases. It has been shown that dispersive interactions merely differ by size effects for solutions of 1-alkanol (from 1-propanol) and DPE, or DBE. Systems with cyclic monoethers are characterized by a strengthening of dipolar interactions and a weakening of association effects. As a result, orientational effects are weaker in this type of solution. It is remarkable that mixtures with the longer 1-alkanols (from 1-hexanol) show a behavior close to random mixing. Random mixing is also observed when the temperature increases, as in the case of 1-propanol or 1-butanol + diethylether systems at 323.15 K. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004354
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7417–7429[article] Application of the Flory theory and of the Kirkwod-Buff formalism to the study of orientational effects in 1-alkanol + linear or cyclic monoether mixtures [texte imprimé] / Juan Antonio Gonzalez, Auteur ; Nicolás Riesco, Auteur ; Ismael Mozo, Auteur . - 2009 . - pp. 7417–7429.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7417–7429
Mots-clés : Orientational effects 1-alkanols Cyclic monoethers Flory mode Kirkwood− Buff formalism Résumé : Orientational effects present in binary mixtures of 1-alkanols with linear or cyclic monoethers have been studied using the Flory model and the Kirkwood−Buff formalism. The alcohols considered are those from methanol to 1-decanol, and the ethers are the following: dimethylether (DME), diethylether (DEE), dipropylether (DPE), dibutylether (DBE), tetrahydrofuran (THF), and tetrahydropyran (THP). In terms of the Flory model, orientational effects have been investigated by analyzing the concentration dependence of the interaction parameter, X12, and comparing the deviations obtained between experimental molar excess enthalpies, HmE, and calculated values with an X12 parameter determined from HmE measurements at equimolar composition. Due to the facts that structural effects are relevant for many of the considered mixtures and their excess molar volumes, VmE, are negative, we have also determined the excess molar internal energies, UV,mE, and X12 parameters from these data. From the X12 variation with the alkanol size, we have shown than interactions between unlike molecules are nearly constant along a homologous series with a given ether. In the framework of the Kirkwood−Buff theory, the study has been developed through the Kirkwood−Buff integrals and related local mole fractions, obtained from vapor−liquid equilibria and VmE data available in the literature. Ideal compressibilities for the mixtures were assumed. Although the Flory model does not describe the complex structural effects present in the investigated mixtures and fails when predicting VmE, both theories provide consistent results on the orientational effects in these solutions. In addition, the results are in agreement with those previously obtained from the ERAS model. Systems involving linear monoethers are mainly characterized by orientational effects related to the self-association of the alcohol, in such way that the mentioned effects decrease when the size of the alcohol is increased in solutions with a given ether. Orientational effects become more relevant when the chain length of the linear monoether mixed with a fixed 1-alkanol increases. It has been shown that dispersive interactions merely differ by size effects for solutions of 1-alkanol (from 1-propanol) and DPE, or DBE. Systems with cyclic monoethers are characterized by a strengthening of dipolar interactions and a weakening of association effects. As a result, orientational effects are weaker in this type of solution. It is remarkable that mixtures with the longer 1-alkanols (from 1-hexanol) show a behavior close to random mixing. Random mixing is also observed when the temperature increases, as in the case of 1-propanol or 1-butanol + diethylether systems at 323.15 K. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004354 Exemplaires
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Titre : Use of thermogravimetry/mass spectrometry analysis to explain the origin of volatiles produced during biomass pyrolysis Type de document : texte imprimé Auteurs : Agustín García Barneto, Auteur ; José Ariza Carmona, Auteur ; José E. Martín Alfonso, Auteur Année de publication : 2009 Article en page(s) : pp. 7430–7436 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Thermogravimetry coupled to mass spectrometry Pyrolysis Résumé : Pyrolysis of alternative biomasses, which contributes to the recovery of arid soils and does not compete with alimentary biomass, could increase use of biomass as feedstock in energy production facilities. In this sense, in order to optimize this thermal process and gain better insight the origin and evolution of the main produced volatiles, nonisothermal thermogravimetry coupled to mass spectrometry (TG/MS) has been applied for samples of two biomasses [Leucaena Leucocephala (Leucaena) and Chamaecytisus Palmensis (Tagasaste)], which find application as energy crops and contribute to soil restoration. In a first stage, autocatalytic kinetics has been used in order to obtain the mass loss rate profiles (DTG) of each biomass pseudocomponent (hemicellulose, cellulose, lignin, and extractives) during pyrolysis. In a second stage, the experimental mass spectrometry signals of the main volatiles (CO, CO2, and H2O) have been simulated using a linear combination of the previously calculated DTG profiles. The accurate fitting obtained, explains the origin of these volatiles from a simple volatization process, mainly from lignin. In a third stage, in order to simulate the hydrogen signal, it has been necessary to consider the char produced during the volatization process. According to the model, the charring process explains close to 77 wt % of the total hydrogen obtained during pyrolysis. Considering the specific char production of each biomass pseudocomponent, it is possible to measure their individual contributions to hydrogen production: hemicellulose, 27.5; cellulose, 9.7; and lignin, 60.9 wt %, for Leucaena. Taking into account the composition of the samples, the relation between the specific hydrogen productions of the single pseudocomponents (hemicellulose:cellulose:lignin) can be calculated: 3.4:1.0:7.6. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900453w
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7430–7436[article] Use of thermogravimetry/mass spectrometry analysis to explain the origin of volatiles produced during biomass pyrolysis [texte imprimé] / Agustín García Barneto, Auteur ; José Ariza Carmona, Auteur ; José E. Martín Alfonso, Auteur . - 2009 . - pp. 7430–7436.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7430–7436
Mots-clés : Thermogravimetry coupled to mass spectrometry Pyrolysis Résumé : Pyrolysis of alternative biomasses, which contributes to the recovery of arid soils and does not compete with alimentary biomass, could increase use of biomass as feedstock in energy production facilities. In this sense, in order to optimize this thermal process and gain better insight the origin and evolution of the main produced volatiles, nonisothermal thermogravimetry coupled to mass spectrometry (TG/MS) has been applied for samples of two biomasses [Leucaena Leucocephala (Leucaena) and Chamaecytisus Palmensis (Tagasaste)], which find application as energy crops and contribute to soil restoration. In a first stage, autocatalytic kinetics has been used in order to obtain the mass loss rate profiles (DTG) of each biomass pseudocomponent (hemicellulose, cellulose, lignin, and extractives) during pyrolysis. In a second stage, the experimental mass spectrometry signals of the main volatiles (CO, CO2, and H2O) have been simulated using a linear combination of the previously calculated DTG profiles. The accurate fitting obtained, explains the origin of these volatiles from a simple volatization process, mainly from lignin. In a third stage, in order to simulate the hydrogen signal, it has been necessary to consider the char produced during the volatization process. According to the model, the charring process explains close to 77 wt % of the total hydrogen obtained during pyrolysis. Considering the specific char production of each biomass pseudocomponent, it is possible to measure their individual contributions to hydrogen production: hemicellulose, 27.5; cellulose, 9.7; and lignin, 60.9 wt %, for Leucaena. Taking into account the composition of the samples, the relation between the specific hydrogen productions of the single pseudocomponents (hemicellulose:cellulose:lignin) can be calculated: 3.4:1.0:7.6. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900453w Exemplaires
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Titre : Facile synthesis of copper nanoparticles by ionic liquids and its application to facilitated olefin transport membranes Type de document : texte imprimé Auteurs : Jongho Kim, Auteur ; Sang Wook Kang, Auteur ; Sung Hyun Mun, Auteur Année de publication : 2009 Article en page(s) : pp. 7437–7441 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Copper nanoparticle Ionic liquids Olefin carrier Résumé : We suggest a facile synthesis method of copper nanoparticles, and this process is facilitated by 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM+BF4−) which was employed to dissociate the copper metal into nanosized copper particles. The formation of copper nanoparticles was confirmed by UV−vis spectrum analysis and transmission electron microscope (TEM) imaging, and the interaction of BMIM+BF4− with the copper metal was confirmed by Fourier transform (FT)-Raman spectroscopy. Moreover, the fabricated copper nanoparticles could be used as an olefin carrier for propylene/propane separation. While BMIM+BF4−/Cu (stirred for 0 h) nanocomposite showed a selectivity of 1.1 and a permeance of 4.7 GPU, the separation performance of the BMIM+BF4−/Cu (stirred for 24 h) nanocomposite membrane was significantly improved; the selectivity was found to be 5.2 with a mixed gas permeance of 4.0 GPU. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900150c
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7437–7441[article] Facile synthesis of copper nanoparticles by ionic liquids and its application to facilitated olefin transport membranes [texte imprimé] / Jongho Kim, Auteur ; Sang Wook Kang, Auteur ; Sung Hyun Mun, Auteur . - 2009 . - pp. 7437–7441.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7437–7441
Mots-clés : Copper nanoparticle Ionic liquids Olefin carrier Résumé : We suggest a facile synthesis method of copper nanoparticles, and this process is facilitated by 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM+BF4−) which was employed to dissociate the copper metal into nanosized copper particles. The formation of copper nanoparticles was confirmed by UV−vis spectrum analysis and transmission electron microscope (TEM) imaging, and the interaction of BMIM+BF4− with the copper metal was confirmed by Fourier transform (FT)-Raman spectroscopy. Moreover, the fabricated copper nanoparticles could be used as an olefin carrier for propylene/propane separation. While BMIM+BF4−/Cu (stirred for 0 h) nanocomposite showed a selectivity of 1.1 and a permeance of 4.7 GPU, the separation performance of the BMIM+BF4−/Cu (stirred for 24 h) nanocomposite membrane was significantly improved; the selectivity was found to be 5.2 with a mixed gas permeance of 4.0 GPU. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900150c Exemplaires
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Titre : Pt−sn-based SAPO-34 supported novel catalyst for n-butane dehydrogenation Type de document : texte imprimé Auteurs : Zeeshan Nawaz, Auteur ; Wei Fei, Auteur Année de publication : 2009 Article en page(s) : pp. 7442–7447 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pt− Sn/SAPO-34 novel catalyst n-butane dehydrogenation X-ray fluorescence diffraction Résumé : The performance of Pt−Sn/SAPO-34 novel catalyst was investigated for n-butane dehydrogenation. The catalyst was characterized by number of physiochemical techniques X-ray fluorescence (XRF), X-ray diffraction (XRD), ammonia temperature-programmed desorption (NH3-TPD), hydrogen temperature-programmed reduction (H2-TPR), temperature-programmed oxidation (TPO), transmission electron microscopy (TEM), and O2-pulse coke measurement. The metallic contents, structure, acidity, and metallic dispersion were determined in order to explain catalyst superiority and functionality using SAPO-34 as support. Pt−Sn-based SAPO-34 supported catalyst was parametrically characterized in order to obtain superior control of dehydrogenation reaction stereochemistry. Above 91% of total olefins with 80% butene was achieved over Pt−Sn/SAPO-34. The weight hourly space velocity 2.8 h−1 and temperature 585 °C were found to be optimum for the higher dehydrogenation activity. The catalysts also showed very good hydrothermal stability in continuous reaction−regeneration cycles. The coke formation was mainly related to catalyst activity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900801m
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7442–7447[article] Pt−sn-based SAPO-34 supported novel catalyst for n-butane dehydrogenation [texte imprimé] / Zeeshan Nawaz, Auteur ; Wei Fei, Auteur . - 2009 . - pp. 7442–7447.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7442–7447
Mots-clés : Pt− Sn/SAPO-34 novel catalyst n-butane dehydrogenation X-ray fluorescence diffraction Résumé : The performance of Pt−Sn/SAPO-34 novel catalyst was investigated for n-butane dehydrogenation. The catalyst was characterized by number of physiochemical techniques X-ray fluorescence (XRF), X-ray diffraction (XRD), ammonia temperature-programmed desorption (NH3-TPD), hydrogen temperature-programmed reduction (H2-TPR), temperature-programmed oxidation (TPO), transmission electron microscopy (TEM), and O2-pulse coke measurement. The metallic contents, structure, acidity, and metallic dispersion were determined in order to explain catalyst superiority and functionality using SAPO-34 as support. Pt−Sn-based SAPO-34 supported catalyst was parametrically characterized in order to obtain superior control of dehydrogenation reaction stereochemistry. Above 91% of total olefins with 80% butene was achieved over Pt−Sn/SAPO-34. The weight hourly space velocity 2.8 h−1 and temperature 585 °C were found to be optimum for the higher dehydrogenation activity. The catalysts also showed very good hydrothermal stability in continuous reaction−regeneration cycles. The coke formation was mainly related to catalyst activity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900801m Exemplaires
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Titre : Modeling of iron removal from spent passivation baths by ion exchange in fixed-bed operation Type de document : texte imprimé Auteurs : Alfredo Ortiz, Auteur ; Iñaki Fernández-Olmo, Auteur ; Urtiaga, Ane, Auteur Année de publication : 2009 Article en page(s) : pp. 7448–7452 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fixed-bed Ion exchange Iron separation Chromium(III) passivating baths Résumé : In this work the mathematical model that describes the kinetics of the fixed-bed ion exchange iron separation from chromium(III) passivating baths is presented. Passivation is a common step in the zinc electrodeposition galvanic process. The removal of iron species from the passivation baths allows the extention of their life, thus reducing the amount of waste to be managed and the consumption of raw materials. A commercial chelating resin, Purolite S-957, containing sulfonic and phosphonic acid functional groups was employed. Equilibrium experiments, carried out under isothermal conditions at 20 °C, were correlated to the Freundlich equation, with the following parameters KF = 25 700((mg(n−1)/n L1/n)/kgdry_resin) and n = 2.45. A simple mathematical model assuming a reversible chemical reaction as the rate-controlling step has been developed to describe the fixed-bed iron removal rate in the media solutions under study. The value of the unknown parameter, the rate coefficient for the forward reaction, kd = 10 660[(mg(n−1)/n L1/n)/(kgdry_resin h)] was obtained from experimental data of iron uptake employing parameter estimation software. The proposed model offers a satisfactory description of the behavior of the iron loading curves for three different types of real passivation baths under variable feed iron concentration and loading flow rate, using only one estimated parameter. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900407c
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7448–7452[article] Modeling of iron removal from spent passivation baths by ion exchange in fixed-bed operation [texte imprimé] / Alfredo Ortiz, Auteur ; Iñaki Fernández-Olmo, Auteur ; Urtiaga, Ane, Auteur . - 2009 . - pp. 7448–7452.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7448–7452
Mots-clés : Fixed-bed Ion exchange Iron separation Chromium(III) passivating baths Résumé : In this work the mathematical model that describes the kinetics of the fixed-bed ion exchange iron separation from chromium(III) passivating baths is presented. Passivation is a common step in the zinc electrodeposition galvanic process. The removal of iron species from the passivation baths allows the extention of their life, thus reducing the amount of waste to be managed and the consumption of raw materials. A commercial chelating resin, Purolite S-957, containing sulfonic and phosphonic acid functional groups was employed. Equilibrium experiments, carried out under isothermal conditions at 20 °C, were correlated to the Freundlich equation, with the following parameters KF = 25 700((mg(n−1)/n L1/n)/kgdry_resin) and n = 2.45. A simple mathematical model assuming a reversible chemical reaction as the rate-controlling step has been developed to describe the fixed-bed iron removal rate in the media solutions under study. The value of the unknown parameter, the rate coefficient for the forward reaction, kd = 10 660[(mg(n−1)/n L1/n)/(kgdry_resin h)] was obtained from experimental data of iron uptake employing parameter estimation software. The proposed model offers a satisfactory description of the behavior of the iron loading curves for three different types of real passivation baths under variable feed iron concentration and loading flow rate, using only one estimated parameter. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900407c Exemplaires
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