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Vol. 48 N° 8 - Avril 2009 [texte imprimé] . - 2009 . - p. 3703-4176 : ill. ; 28 cm. Chemical engineering Langues : Anglais (eng)
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Ajouter le résultat dans votre panierHydrogen generation from chemical hydrides / Eyma Y. Marrero-Alfonso in Industrial & engineering chemistry research, Vol. 48 N° 8 (Avril 2009)
Titre : Hydrogen generation from chemical hydrides Type de document : texte imprimé Auteurs : Eyma Y. Marrero-Alfonso, Auteur ; Amy M. Beaird, Auteur ; Thomas A. Davis, Auteur Année de publication : 2009 Article en page(s) : pp. 3703–3712 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Chemical hydrides Hydrogen Hydrolysis Résumé : Complex chemical hydrides can be used to store and deliver hydrogen gas to fuel cells, and thus are one of several candidate materials to be used in storage systems for the hydrogen economy. These hydrides have high native hydrogen content, and hydrogen can be released via several chemical pathways. This review summarizes the extensive literature on the kinetic and thermodynamic properties of the various reactions of chemical hydrides, with an emphasis on hydrolysis. These properties are significant because they affect all aspects of system design, as well as the recovery and recycle of the byproducts. Hydrolysis of chemical hydrides takes place at relatively low temperatures and gives promising theoretical hydrogen storage efficiencies. Complications include metastable kinetic pathways as well as inefficient utilization of water in the byproducts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016225
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3703–3712[article] Hydrogen generation from chemical hydrides [texte imprimé] / Eyma Y. Marrero-Alfonso, Auteur ; Amy M. Beaird, Auteur ; Thomas A. Davis, Auteur . - 2009 . - pp. 3703–3712.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3703–3712
Mots-clés : Chemical hydrides Hydrogen Hydrolysis Résumé : Complex chemical hydrides can be used to store and deliver hydrogen gas to fuel cells, and thus are one of several candidate materials to be used in storage systems for the hydrogen economy. These hydrides have high native hydrogen content, and hydrogen can be released via several chemical pathways. This review summarizes the extensive literature on the kinetic and thermodynamic properties of the various reactions of chemical hydrides, with an emphasis on hydrolysis. These properties are significant because they affect all aspects of system design, as well as the recovery and recycle of the byproducts. Hydrolysis of chemical hydrides takes place at relatively low temperatures and gives promising theoretical hydrogen storage efficiencies. Complications include metastable kinetic pathways as well as inefficient utilization of water in the byproducts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016225 Exemplaires
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Titre : Methods for pretreatment of lignocellulosic biomass for efficient hydrolysis and biofuel production Type de document : texte imprimé Auteurs : Parveen Kumar, Auteur ; Diane M. Barrett, Auteur ; Michael J. Delwiche, Auteur Année de publication : 2009 Article en page(s) : pp. 3713–3729 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Biofuels Lignocellulosic materials Pretreatment techniques Résumé : Biofuels produced from various lignocellulosic materials, such as wood, agricultural, or forest residues, have the potential to be a valuable substitute for, or complement to, gasoline. Many physicochemical structural and compositional factors hinder the hydrolysis of cellulose present in biomass to sugars and other organic compounds that can later be converted to fuels. The goal of pretreatment is to make the cellulose accessible to hydrolysis for conversion to fuels. Various pretreatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. During the past few years a large number of pretreatment methods have been developed, including alkali treatment, ammonia explosion, and others. Many methods have been shown to result in high sugar yields, above 90% of the theoretical yield for lignocellulosic biomasses such as woods, grasses, corn, and so on. In this review, we discuss the various pretreatment process methods and the recent literature that has reported on the use of these technologies for pretreatment of various lignocellulosic biomasses. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801542g#afn2
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3713–3729[article] Methods for pretreatment of lignocellulosic biomass for efficient hydrolysis and biofuel production [texte imprimé] / Parveen Kumar, Auteur ; Diane M. Barrett, Auteur ; Michael J. Delwiche, Auteur . - 2009 . - pp. 3713–3729.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3713–3729
Mots-clés : Biofuels Lignocellulosic materials Pretreatment techniques Résumé : Biofuels produced from various lignocellulosic materials, such as wood, agricultural, or forest residues, have the potential to be a valuable substitute for, or complement to, gasoline. Many physicochemical structural and compositional factors hinder the hydrolysis of cellulose present in biomass to sugars and other organic compounds that can later be converted to fuels. The goal of pretreatment is to make the cellulose accessible to hydrolysis for conversion to fuels. Various pretreatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. During the past few years a large number of pretreatment methods have been developed, including alkali treatment, ammonia explosion, and others. Many methods have been shown to result in high sugar yields, above 90% of the theoretical yield for lignocellulosic biomasses such as woods, grasses, corn, and so on. In this review, we discuss the various pretreatment process methods and the recent literature that has reported on the use of these technologies for pretreatment of various lignocellulosic biomasses. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801542g#afn2 Exemplaires
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Titre : Synthesis and characterization of imprinted polymers for radioactive waste reduction Type de document : texte imprimé Auteurs : Anupkumar Bhaskarapillai, Auteur ; Narasimhan V. Sevilimedu, Auteur ; Börje Sellergren, Auteur Année de publication : 2009 Article en page(s) : pp. 3730–3737 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Imprinted polymer Radioactive waste generated Nuclear reactors Résumé : A cobalt(II) imprinted polymer, that could lead to significant reduction in radioactive waste volume generated during decontamination of nuclear reactors, was synthesized using [N-(4-vinylbenzyl) imino]diacetic acid as the functional monomer through two different methods. The imprinted polymer was found to selectively trap cobalt(II) ions even when present in ppb levels from strong complexing medium against excess ferrous ions. It showed no uptake of ferrous ions under the conditions tested. Cobalt sorption and desorption were found to be rapid. The cobalt selectivity of the polymer was also demonstrated with radioactive cobaltous ions wherein it showed 55% reduction in cobalt activity from a complexing solution containing 2 μCi of radioactive cobalt along with excess ferrous ions. The selectivity of the polymer was compared to that of a commercial resin containing similar functional ligand. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801640b
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3730–3737[article] Synthesis and characterization of imprinted polymers for radioactive waste reduction [texte imprimé] / Anupkumar Bhaskarapillai, Auteur ; Narasimhan V. Sevilimedu, Auteur ; Börje Sellergren, Auteur . - 2009 . - pp. 3730–3737.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3730–3737
Mots-clés : Imprinted polymer Radioactive waste generated Nuclear reactors Résumé : A cobalt(II) imprinted polymer, that could lead to significant reduction in radioactive waste volume generated during decontamination of nuclear reactors, was synthesized using [N-(4-vinylbenzyl) imino]diacetic acid as the functional monomer through two different methods. The imprinted polymer was found to selectively trap cobalt(II) ions even when present in ppb levels from strong complexing medium against excess ferrous ions. It showed no uptake of ferrous ions under the conditions tested. Cobalt sorption and desorption were found to be rapid. The cobalt selectivity of the polymer was also demonstrated with radioactive cobaltous ions wherein it showed 55% reduction in cobalt activity from a complexing solution containing 2 μCi of radioactive cobalt along with excess ferrous ions. The selectivity of the polymer was compared to that of a commercial resin containing similar functional ligand. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801640b Exemplaires
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Titre : Biosurfactants from urban wastes as auxiliaries for textile dyeing Type de document : texte imprimé Auteurs : Piero Savarino, Auteur ; Enzo Montoneri, Auteur ; Stefano Bottigliengo, Auteur Année de publication : 2009 Article en page(s) : pp. 3738–3748 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Biosurfactants Urban wastes Cellulose acetate fabric Résumé : To promote biobased products for the industry, six biosurfactants isolated from green and food urban residues aged under aerobic digestion for 0−60 days were investigated for their potential to perform as auxiliaries for dyeing cellulose acetate fabric with water-insoluble dyes. The experimental plan included investigation of the chemical nature, surface activity, and power to enhance dye solubility in water, as well as dyeing test performed under a variety of experimental conditions presenting a range of challenge levels. For comparison, the same investigation was performed on commercial synthetic surfactants. The investigated biosurfactants exhibited chemical composition and surface activity properties presumably related to their different biomass sources. However, no significant performance differences in textile dyeing were evident among the biosurfactants and between biosurfactants and synthetic surfactants. The results encourage product and process development for exploitation of biomass residues as a source of chemicals to recycle to the industry. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801853x
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3738–3748[article] Biosurfactants from urban wastes as auxiliaries for textile dyeing [texte imprimé] / Piero Savarino, Auteur ; Enzo Montoneri, Auteur ; Stefano Bottigliengo, Auteur . - 2009 . - pp. 3738–3748.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3738–3748
Mots-clés : Biosurfactants Urban wastes Cellulose acetate fabric Résumé : To promote biobased products for the industry, six biosurfactants isolated from green and food urban residues aged under aerobic digestion for 0−60 days were investigated for their potential to perform as auxiliaries for dyeing cellulose acetate fabric with water-insoluble dyes. The experimental plan included investigation of the chemical nature, surface activity, and power to enhance dye solubility in water, as well as dyeing test performed under a variety of experimental conditions presenting a range of challenge levels. For comparison, the same investigation was performed on commercial synthetic surfactants. The investigated biosurfactants exhibited chemical composition and surface activity properties presumably related to their different biomass sources. However, no significant performance differences in textile dyeing were evident among the biosurfactants and between biosurfactants and synthetic surfactants. The results encourage product and process development for exploitation of biomass residues as a source of chemicals to recycle to the industry. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801853x Exemplaires
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Titre : Synthesis and characterization of polyol poly-12-hydroxy stearic acid : applications in preparing environmentally friendly overbased calcium oleate detergent Type de document : texte imprimé Auteurs : Yonglei Wang, Auteur ; Wumanjiang Eli, Auteur ; Ayixiamuguli Nueraimaiti, Auteur Année de publication : 2009 Article en page(s) : pp. 3749–3754 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Poly-12-hydroxy stearic acid Esterification Polyol polymeric hyperdispersant FT-IR analysis Résumé : In this study, the poly-12-hydroxy stearic acid (PTHSA) was synthesized and then modified by esterification with pentaerythritol to obtain a polyol polymeric hyperdispersant (polyol-PTHSA). Under suitable reaction conditions (molar ratio pentaerythritol/PTHSA, 1.2:1; reaction temperature, 453 K; and reaction time, 4−8 h), the polyol-PTHSA with acid value of 3 mg of KOH/g can be obtained. The structures were confirmed by FT-IR analysis. The polyol-PTHSA was subsequently used as a hyperdispersant in the process of preparing environmentally friendly overbased calcium oleate detergent to increase the total base number of the product. Reaction conditions including the polymerization catalyst, the catalyst amount, the amount of xylene, the polymerization temperature, the polymerization time, the polyol-PTHSA amount, and the acid value of the PTHSA were optimized. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016016
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3749–3754[article] Synthesis and characterization of polyol poly-12-hydroxy stearic acid : applications in preparing environmentally friendly overbased calcium oleate detergent [texte imprimé] / Yonglei Wang, Auteur ; Wumanjiang Eli, Auteur ; Ayixiamuguli Nueraimaiti, Auteur . - 2009 . - pp. 3749–3754.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3749–3754
Mots-clés : Poly-12-hydroxy stearic acid Esterification Polyol polymeric hyperdispersant FT-IR analysis Résumé : In this study, the poly-12-hydroxy stearic acid (PTHSA) was synthesized and then modified by esterification with pentaerythritol to obtain a polyol polymeric hyperdispersant (polyol-PTHSA). Under suitable reaction conditions (molar ratio pentaerythritol/PTHSA, 1.2:1; reaction temperature, 453 K; and reaction time, 4−8 h), the polyol-PTHSA with acid value of 3 mg of KOH/g can be obtained. The structures were confirmed by FT-IR analysis. The polyol-PTHSA was subsequently used as a hyperdispersant in the process of preparing environmentally friendly overbased calcium oleate detergent to increase the total base number of the product. Reaction conditions including the polymerization catalyst, the catalyst amount, the amount of xylene, the polymerization temperature, the polymerization time, the polyol-PTHSA amount, and the acid value of the PTHSA were optimized. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016016 Exemplaires
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Titre : Hydrogenation of oxidized wax and a process to produce olefins from paraffins by autoxidation, selective hydrogenation, and dehydration Type de document : texte imprimé Auteurs : F. H. A. Bolder, Auteur ; A. de Klerk, Auteur ; J. L. Visagie, Auteur Année de publication : 2009 Article en page(s) : pp. 3755–3760 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Oxidized wax Hydrogenation Résumé : Hydrogenation of oxidized wax to produce an oxidized wax enriched in sec-alcohols was investigated experimentally. Hydrogenation over copper chromite catalysts resulted in an alcohol yield of 50−55% at 180−190 °C, 10 MPa of hydrogen pressure, and liquid hourly space velocity of 0.4 h−1. Hydrogenation at temperatures above 200 °C resulted in significant overhydrogenation of the oxidized wax to paraffins. Copper chromite catalysts were also found to be active for the esterification of carboxylic acids with alcohols. The combination of copper chromite with Ru/C increased carboxylic acid conversion, but did not improve the overall alcohol yield. The results from the experimental work were employed in conjunction with previous studies to propose a process for the production of olefins from paraffins by autoxidation, selective hydrogenation, and alcohol dehydration. All of these processing steps can be performed at En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018092
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3755–3760[article] Hydrogenation of oxidized wax and a process to produce olefins from paraffins by autoxidation, selective hydrogenation, and dehydration [texte imprimé] / F. H. A. Bolder, Auteur ; A. de Klerk, Auteur ; J. L. Visagie, Auteur . - 2009 . - pp. 3755–3760.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3755–3760
Mots-clés : Oxidized wax Hydrogenation Résumé : Hydrogenation of oxidized wax to produce an oxidized wax enriched in sec-alcohols was investigated experimentally. Hydrogenation over copper chromite catalysts resulted in an alcohol yield of 50−55% at 180−190 °C, 10 MPa of hydrogen pressure, and liquid hourly space velocity of 0.4 h−1. Hydrogenation at temperatures above 200 °C resulted in significant overhydrogenation of the oxidized wax to paraffins. Copper chromite catalysts were also found to be active for the esterification of carboxylic acids with alcohols. The combination of copper chromite with Ru/C increased carboxylic acid conversion, but did not improve the overall alcohol yield. The results from the experimental work were employed in conjunction with previous studies to propose a process for the production of olefins from paraffins by autoxidation, selective hydrogenation, and alcohol dehydration. All of these processing steps can be performed at En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018092 Exemplaires
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Titre : Kinetics of the absorption of CO2 in aqueous solutions of N-methyldiethanolamine + triethylene tetramine Type de document : texte imprimé Auteurs : Jean-Marc G. Amann, Auteur ; Chakib Bouallou, Auteur Année de publication : 2009 Article en page(s) : pp. 3761–3770 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solvent CO2 capture N-methyldiethanolamine Triethylene tetramine Résumé : This work focuses on the development of a new solvent for CO2 capture. This new solvent is an aqueous solution with a blend of N-methyldiethanolamine (MDEA) and triethylene tetramine (TETA), an amine with four amino groups. CO2 absorption was investigated between 298 and 333 K using a Lewis cell with a constant interfacial area. Several concentrations of MDEA (17.5 and 40 wt %) and TETA (3 and 6 wt %) were assessed. The influence of the CO2 partial pressure on the absorption rate was pointed out. The addition of small amount of TETA leads to a high increase in the CO2 absorption rates. A numerical model based on the film theory was used to determine the rate coefficients between CO2 and TETA for the different solvents. The physicochemical parameters have a huge influence on the determination of the rate coefficients. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800414v
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3761–3770[article] Kinetics of the absorption of CO2 in aqueous solutions of N-methyldiethanolamine + triethylene tetramine [texte imprimé] / Jean-Marc G. Amann, Auteur ; Chakib Bouallou, Auteur . - 2009 . - pp. 3761–3770.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3761–3770
Mots-clés : Solvent CO2 capture N-methyldiethanolamine Triethylene tetramine Résumé : This work focuses on the development of a new solvent for CO2 capture. This new solvent is an aqueous solution with a blend of N-methyldiethanolamine (MDEA) and triethylene tetramine (TETA), an amine with four amino groups. CO2 absorption was investigated between 298 and 333 K using a Lewis cell with a constant interfacial area. Several concentrations of MDEA (17.5 and 40 wt %) and TETA (3 and 6 wt %) were assessed. The influence of the CO2 partial pressure on the absorption rate was pointed out. The addition of small amount of TETA leads to a high increase in the CO2 absorption rates. A numerical model based on the film theory was used to determine the rate coefficients between CO2 and TETA for the different solvents. The physicochemical parameters have a huge influence on the determination of the rate coefficients. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800414v Exemplaires
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Titre : Catalytic properties of Pt−Re/Al2O3 naphtha-reforming catalysts modified by germanium introduced by redox reaction at different pH values Type de document : texte imprimé Auteurs : Silvana A. D’Ippolito, Auteur ; Carlos R. Vera, Auteur ; Florence Epron, Auteur Année de publication : 2009 Article en page(s) : pp. 3771–3778 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pt− Re/Al2O3− Cl catalysts Cyclohexane dehydrogenation Cyclopentane hydrogenolysis FTIR spectroscopy Résumé : Ge was deposited by catalytic reduction on Pt−Re/Al2O3−Cl base catalysts prepared by coimpregnation. The nominal amounts of Ge incorporated from various impregnation media (H2O, HCl, or NH3) were 0.1, 0.3, 1.0, and 2.0 wt %. The catalysts were characterized by means of the test reactions of cyclohexane dehydrogenation and cyclopentane hydrogenolysis. The catalysts were further characterized by FTIR spectroscopy of adsorbed CO and adsorbed pyridine and by temperature-programmed desorption of pyridine. Blank treatments performed on the Pt−Re/Al2O3 base catalyst in the different media (without Ge addition) showed that the catalytic reduction method modified the properties of the parent catalyst depending on the pH of the solution. The Brønsted acidity decreased as the impregnation pH was increased, whereas the Lewis acidity of the catalyst was not substantially modified by any of the impregnation media. Catalysts with higher Pt−Re interactions were obtained after treatment in a solution of high pH (NH3 medium). The interaction between Ge and the active metal phase increased with increasing Ge content. This interaction resulted in a decrease of the metal activity in cyclohexane dehydrogenation and cyclopentane hydrogenolysis. Catalyst performances were evaluated in n-heptane (n-C7) reforming under pressure. The n-C7 tests showed that trimetallic catalysts obtained by impregnation of small quantities of Ge (≤0.3 wt %) using a neutral aqueous solution are the most active and toluene-selective, especially compared to those prepared using HCl or NH3 solution. Nevertheless, the use of ammonia in the impregnation medium allows one to decrease the amount of cracking products. Thus, the catalytic properties might be improved by using a slightly basic medium for the impregnation of Ge. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801158j
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3771–3778[article] Catalytic properties of Pt−Re/Al2O3 naphtha-reforming catalysts modified by germanium introduced by redox reaction at different pH values [texte imprimé] / Silvana A. D’Ippolito, Auteur ; Carlos R. Vera, Auteur ; Florence Epron, Auteur . - 2009 . - pp. 3771–3778.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3771–3778
Mots-clés : Pt− Re/Al2O3− Cl catalysts Cyclohexane dehydrogenation Cyclopentane hydrogenolysis FTIR spectroscopy Résumé : Ge was deposited by catalytic reduction on Pt−Re/Al2O3−Cl base catalysts prepared by coimpregnation. The nominal amounts of Ge incorporated from various impregnation media (H2O, HCl, or NH3) were 0.1, 0.3, 1.0, and 2.0 wt %. The catalysts were characterized by means of the test reactions of cyclohexane dehydrogenation and cyclopentane hydrogenolysis. The catalysts were further characterized by FTIR spectroscopy of adsorbed CO and adsorbed pyridine and by temperature-programmed desorption of pyridine. Blank treatments performed on the Pt−Re/Al2O3 base catalyst in the different media (without Ge addition) showed that the catalytic reduction method modified the properties of the parent catalyst depending on the pH of the solution. The Brønsted acidity decreased as the impregnation pH was increased, whereas the Lewis acidity of the catalyst was not substantially modified by any of the impregnation media. Catalysts with higher Pt−Re interactions were obtained after treatment in a solution of high pH (NH3 medium). The interaction between Ge and the active metal phase increased with increasing Ge content. This interaction resulted in a decrease of the metal activity in cyclohexane dehydrogenation and cyclopentane hydrogenolysis. Catalyst performances were evaluated in n-heptane (n-C7) reforming under pressure. The n-C7 tests showed that trimetallic catalysts obtained by impregnation of small quantities of Ge (≤0.3 wt %) using a neutral aqueous solution are the most active and toluene-selective, especially compared to those prepared using HCl or NH3 solution. Nevertheless, the use of ammonia in the impregnation medium allows one to decrease the amount of cracking products. Thus, the catalytic properties might be improved by using a slightly basic medium for the impregnation of Ge. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801158j Exemplaires
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Titre : Sensitivity analysis and kinetic parameter estimation in a three way catalytic converter Type de document : texte imprimé Auteurs : S. Koteswara Rao, Auteur ; Rayees Imam, Auteur ; Karthik Ramanathan, Auteur Année de publication : 2009 Article en page(s) : pp. 3779–3790 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Three way catalytic converter Kinetics Genetic-algorithm-based optimization Résumé : A heterogeneous one-dimensional model is used to simulate a three way catalytic converter (TWC). The mathematical model consists of mass and energy balance equations in the gas and solid phases and accounts for 15 heterogeneous chemical reactions. Langmuir−Hinshelwood type kinetics is used to represent most of the reaction rates. In this work, the kinetic parameters of the various reactions occurring in a TWC are estimated using vehicle data based on a genetic-algorithm-based optimization. The method uses the test data to estimate the reaction kinetic parameters by minimizing the deviation between the model predictions and experimental observations. It is found that the objective function based on the cumulative mass of a species that leaves the reactor until a certain time instant is a preferred performance measure for the optimization. The sensitivity of the exit concentration of various species to various kinetic parameters was found. This is used to identify the subset of reactions which have a significant effect on the various species concentrations in the effluent stream and is used to determine the set of kinetic parameters for optimizing the reactor performance. Single parameter and multiple parameters tuning using genetic algorithm have been demonstrated successfully for a TWC application. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801244w
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3779–3790[article] Sensitivity analysis and kinetic parameter estimation in a three way catalytic converter [texte imprimé] / S. Koteswara Rao, Auteur ; Rayees Imam, Auteur ; Karthik Ramanathan, Auteur . - 2009 . - pp. 3779–3790.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3779–3790
Mots-clés : Three way catalytic converter Kinetics Genetic-algorithm-based optimization Résumé : A heterogeneous one-dimensional model is used to simulate a three way catalytic converter (TWC). The mathematical model consists of mass and energy balance equations in the gas and solid phases and accounts for 15 heterogeneous chemical reactions. Langmuir−Hinshelwood type kinetics is used to represent most of the reaction rates. In this work, the kinetic parameters of the various reactions occurring in a TWC are estimated using vehicle data based on a genetic-algorithm-based optimization. The method uses the test data to estimate the reaction kinetic parameters by minimizing the deviation between the model predictions and experimental observations. It is found that the objective function based on the cumulative mass of a species that leaves the reactor until a certain time instant is a preferred performance measure for the optimization. The sensitivity of the exit concentration of various species to various kinetic parameters was found. This is used to identify the subset of reactions which have a significant effect on the various species concentrations in the effluent stream and is used to determine the set of kinetic parameters for optimizing the reactor performance. Single parameter and multiple parameters tuning using genetic algorithm have been demonstrated successfully for a TWC application. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801244w Exemplaires
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Titre : A two-phase reactor model for the hydrocracking of Fischer-Tropsch-derived wax Type de document : texte imprimé Auteurs : Klaus Möller, Auteur ; Philip le Grange, Auteur ; Carlo Accolla, Auteur Année de publication : 2009 Article en page(s) : pp. 3791–3801 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Two-phase reactor model Fischer− Tropsch-derived wax Hydrocracking kinetics Vapor− liquid equilibrium Fixed-bed Résumé : A two-phase reactor model that describes the hydrocracking of Fischer−Tropsch-derived wax (≤C80) has been developed that combines elementary hydrocracking kinetics and vapor−liquid equilibrium (VLE) with the design equations for an ideal fixed-bed reactor. The kinetics of the reaction considers each carbon number as an independent species in which all structural isomers and (de)hydrogenation steps are in chemical equilibrium. β-Scission cracking is rate-controlling for each carbon number; thus, an increase in reaction rate with increasing carbon number is observed. The VLE is described by a Peng−Robinson equation of state, and phase equilibrium is maintained at all locations down the reactor by simultaneous solution of the VLE within the reactor design equations. The model has only one adjustable rate constant: the β-scission rate constant, which controls the conversion. Meanwhile, the selectivity has no adjustable parameters and is controlled completely by the kinetic model and VLE. Results show that the VLE is responsible for the improved selectivity to diesel (C10−C20) with increasing temperature, decreasing pressure, and increasing H2:hydrocarbon feed ratio. These results are supported by experimental two-phase data. The model is able to predict the product distribution of a typical hydrocracking feed to the Shell Middle Distillate Process qualitatively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801350p
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3791–3801[article] A two-phase reactor model for the hydrocracking of Fischer-Tropsch-derived wax [texte imprimé] / Klaus Möller, Auteur ; Philip le Grange, Auteur ; Carlo Accolla, Auteur . - 2009 . - pp. 3791–3801.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3791–3801
Mots-clés : Two-phase reactor model Fischer− Tropsch-derived wax Hydrocracking kinetics Vapor− liquid equilibrium Fixed-bed Résumé : A two-phase reactor model that describes the hydrocracking of Fischer−Tropsch-derived wax (≤C80) has been developed that combines elementary hydrocracking kinetics and vapor−liquid equilibrium (VLE) with the design equations for an ideal fixed-bed reactor. The kinetics of the reaction considers each carbon number as an independent species in which all structural isomers and (de)hydrogenation steps are in chemical equilibrium. β-Scission cracking is rate-controlling for each carbon number; thus, an increase in reaction rate with increasing carbon number is observed. The VLE is described by a Peng−Robinson equation of state, and phase equilibrium is maintained at all locations down the reactor by simultaneous solution of the VLE within the reactor design equations. The model has only one adjustable rate constant: the β-scission rate constant, which controls the conversion. Meanwhile, the selectivity has no adjustable parameters and is controlled completely by the kinetic model and VLE. Results show that the VLE is responsible for the improved selectivity to diesel (C10−C20) with increasing temperature, decreasing pressure, and increasing H2:hydrocarbon feed ratio. These results are supported by experimental two-phase data. The model is able to predict the product distribution of a typical hydrocracking feed to the Shell Middle Distillate Process qualitatively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801350p Exemplaires
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Titre : Preparation, characterization, and performance of HMS-supported Ni catalysts for hydrodechlorination of chorobenzene Type de document : texte imprimé Auteurs : Jixiang Chen, Auteur ; Jianjun Zhou, Auteur ; Rijie Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 3802–3811 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : HMS-supported Ni catalysts Hydrodechlorination N2 adsorption X-ray diffraction Résumé : HMS-supported Ni catalysts were prepared by the direct synthesis and the impregnation method. In the direct synthesis, the effect of nickel content and pH value of the preparation system on the catalyst structure and hydrodechlorination performance was systematically investigated. The physicochemical properties of the catalysts were characterized by means of N2 adsorption, hydrogen temperature-programmed reduction, low- and wide-angle X-ray diffraction, hydrogen chemisorption, hydrogen temperature-programmed desorption, transmission electron microscope, and atomic absorption spectroscopy. The catalyst activity in the hydrodechlorination of chlorobenzene was evaluated in a fixed-bed reactor at atmospheric pressure. For the n%Ni(m%)-HMS samples prepared by the direct synthesis method, BET surface area, pore volume, and the pore (2∼5 nm) diameter decrease with increasing Ni content, and the mesostructures becomes worse. When the nickel content exceeds 7.0 wt%, the sample with mesostructures cannot be prepared. This is attributed to the decrease of pH value in the preparation system and the embedment of Ni2+ in the SiO2 matrix. Ni2+ ions highly disperse in the n%Ni(m%)-HMS samples and mainly exist as nickel silicate. After reduction at 450∼650 °C, the metallic nickel particles in n%Ni(m%)-HMS uniformly distribute at about 3 nm. However, for the im−4.1%Ni/HMS sample prepared by the impregnation method, the metallic nickel particles are much larger than those of n%Ni(m%)-HMS. In the hydrodechlorination of chlorobenzene, the n%Ni(m%)-HMS samples show higher activities than im−4.1%Ni/HMS, which can be attributed to the strong interaction between small metallic nickel particles and the support, a greater amount of spilt-over hydrogen, and the acidity of nickel silicate. When the nickel content exceeds 5.9 wt % and the reduction temperature is above 450 °C, there is no remarkable difference in chlorobenzene conversion for n%Ni(m%)-HMS samples. This is perhaps related to the intraparticle mass transfer limitation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801792h
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3802–3811[article] Preparation, characterization, and performance of HMS-supported Ni catalysts for hydrodechlorination of chorobenzene [texte imprimé] / Jixiang Chen, Auteur ; Jianjun Zhou, Auteur ; Rijie Wang, Auteur . - 2009 . - pp. 3802–3811.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3802–3811
Mots-clés : HMS-supported Ni catalysts Hydrodechlorination N2 adsorption X-ray diffraction Résumé : HMS-supported Ni catalysts were prepared by the direct synthesis and the impregnation method. In the direct synthesis, the effect of nickel content and pH value of the preparation system on the catalyst structure and hydrodechlorination performance was systematically investigated. The physicochemical properties of the catalysts were characterized by means of N2 adsorption, hydrogen temperature-programmed reduction, low- and wide-angle X-ray diffraction, hydrogen chemisorption, hydrogen temperature-programmed desorption, transmission electron microscope, and atomic absorption spectroscopy. The catalyst activity in the hydrodechlorination of chlorobenzene was evaluated in a fixed-bed reactor at atmospheric pressure. For the n%Ni(m%)-HMS samples prepared by the direct synthesis method, BET surface area, pore volume, and the pore (2∼5 nm) diameter decrease with increasing Ni content, and the mesostructures becomes worse. When the nickel content exceeds 7.0 wt%, the sample with mesostructures cannot be prepared. This is attributed to the decrease of pH value in the preparation system and the embedment of Ni2+ in the SiO2 matrix. Ni2+ ions highly disperse in the n%Ni(m%)-HMS samples and mainly exist as nickel silicate. After reduction at 450∼650 °C, the metallic nickel particles in n%Ni(m%)-HMS uniformly distribute at about 3 nm. However, for the im−4.1%Ni/HMS sample prepared by the impregnation method, the metallic nickel particles are much larger than those of n%Ni(m%)-HMS. In the hydrodechlorination of chlorobenzene, the n%Ni(m%)-HMS samples show higher activities than im−4.1%Ni/HMS, which can be attributed to the strong interaction between small metallic nickel particles and the support, a greater amount of spilt-over hydrogen, and the acidity of nickel silicate. When the nickel content exceeds 5.9 wt % and the reduction temperature is above 450 °C, there is no remarkable difference in chlorobenzene conversion for n%Ni(m%)-HMS samples. This is perhaps related to the intraparticle mass transfer limitation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801792h Exemplaires
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Titre : Influence of supports on structure and performance of nickel phosphide catalysts for hydrodechlorination of chlorobenzene Type de document : texte imprimé Auteurs : Jixiang Chen, Auteur ; Shaojun Zhou, Auteur ; Donghui Ci, Auteur Année de publication : 2009 Article en page(s) : pp. 3812–3819 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Phosphide catalysts N2 adsorption− desorption Hydrogen temperature-programmed reduction X-ray diffraction photoelectron spectroscopy Résumé : SiO2, TiO2, γ-Al2O3, and HY zeolite supported phosphide catalysts were prepared by the hydrogen temperature-programmed reduction method from phosphate precursors. The physicochemical properties of the catalysts were characterized by means of N2 adsorption−desorption, hydrogen temperature-programmed reduction, X-ray diffraction, X-ray photoelectron spectroscopy, hydrogen temperature-programmed desorption, inductively coupled plasma atomic emission spectroscopy, energy-dispersion X-ray spectroscopy, and thermal gravimetric analysis. The catalyst performance in the hydrodechlorination of chlorobenzene was evaluated in a fixed-bed reactor at atmospheric pressure. It has been found that the support property remarkably affects the formation of nickel phosphides. With the same Ni/P molar ratio (about 0.7) in the precursors, Ni2P is prepared on SiO2 and TiO2; however, Ni and Ni3P form on γ-Al2O3 and Ni and Ni12P5 form on HY. This phenomenon is attributed to some phosphorus reacting with γ-Al2O3 and HY to form AlPO4, and the phosphorus reacting with nickel is scarce. Under identical reaction conditions, the hydrodechlorination performance of the catalysts decrease in the order of SiO2-supported N2P, γ-Al2O3-supported Ni−Ni3P, TiO2-supported N2P, and HY-supported Ni−Ni12P5. The catalyst performance is closely related to the properties of active phases and hydrogen species. Nickel phosphides have better performance than metallic nickel due to the electron deficiency of nickel, and the spilt-over hydrogen species also contribute to the hydrogenolysis of C−Cl bond. The chlorobenzene conversion exceeds 99% over SiO2-supported Ni2P during 130 h at 573 K. The excellent performance is ascribed to the strong poison resistance of Ni2P to chlorine and the abundant hydrogen species. TiO2-supported N2P and HY-supported Ni−Ni12P5 have good initial activities; however, their deactivation is remarkable, especially HY-supported Ni−Ni12P5. Their deactivation is mainly owing to the carbonous deposition. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018643
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3812–3819[article] Influence of supports on structure and performance of nickel phosphide catalysts for hydrodechlorination of chlorobenzene [texte imprimé] / Jixiang Chen, Auteur ; Shaojun Zhou, Auteur ; Donghui Ci, Auteur . - 2009 . - pp. 3812–3819.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3812–3819
Mots-clés : Phosphide catalysts N2 adsorption− desorption Hydrogen temperature-programmed reduction X-ray diffraction photoelectron spectroscopy Résumé : SiO2, TiO2, γ-Al2O3, and HY zeolite supported phosphide catalysts were prepared by the hydrogen temperature-programmed reduction method from phosphate precursors. The physicochemical properties of the catalysts were characterized by means of N2 adsorption−desorption, hydrogen temperature-programmed reduction, X-ray diffraction, X-ray photoelectron spectroscopy, hydrogen temperature-programmed desorption, inductively coupled plasma atomic emission spectroscopy, energy-dispersion X-ray spectroscopy, and thermal gravimetric analysis. The catalyst performance in the hydrodechlorination of chlorobenzene was evaluated in a fixed-bed reactor at atmospheric pressure. It has been found that the support property remarkably affects the formation of nickel phosphides. With the same Ni/P molar ratio (about 0.7) in the precursors, Ni2P is prepared on SiO2 and TiO2; however, Ni and Ni3P form on γ-Al2O3 and Ni and Ni12P5 form on HY. This phenomenon is attributed to some phosphorus reacting with γ-Al2O3 and HY to form AlPO4, and the phosphorus reacting with nickel is scarce. Under identical reaction conditions, the hydrodechlorination performance of the catalysts decrease in the order of SiO2-supported N2P, γ-Al2O3-supported Ni−Ni3P, TiO2-supported N2P, and HY-supported Ni−Ni12P5. The catalyst performance is closely related to the properties of active phases and hydrogen species. Nickel phosphides have better performance than metallic nickel due to the electron deficiency of nickel, and the spilt-over hydrogen species also contribute to the hydrogenolysis of C−Cl bond. The chlorobenzene conversion exceeds 99% over SiO2-supported Ni2P during 130 h at 573 K. The excellent performance is ascribed to the strong poison resistance of Ni2P to chlorine and the abundant hydrogen species. TiO2-supported N2P and HY-supported Ni−Ni12P5 have good initial activities; however, their deactivation is remarkable, especially HY-supported Ni−Ni12P5. Their deactivation is mainly owing to the carbonous deposition. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018643 Exemplaires
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Titre : On the introduction of a qualitative variable to the neural network for reactor modeling : feed type Type de document : texte imprimé Auteurs : Maryam Ghadrdan, Auteur ; Hamid Mehdizadeh, Auteur ; Ramin Bozorgmehry Boozarjomehry, Auteur Année de publication : 2009 Article en page(s) : pp. 3820–3824 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Reactor feed type Hydrocarbons Neural networks Résumé : Thermal cracking of hydrocarbons converts them into valuable materials in the petrochemical industries. Multiplicity of the reaction routes and complexity of the mathematical approach has led us use a kind of black-box modeling—artificial neural networks. Reactor feed type plays an essential role on the product qualities. Feed type is a qualitative character. In this paper, a method is presented to introduce a range of petroleum fractions to the neural network. To introduce petroleum cuts with final boiling points of 865 °F maximum to the neural network, a real component substitute mixture is made from the original mixture. Such substitute mixture is fully defined, it has a chemical character, and physical properties can be simply retrieved from databases. The mixture compositions are defined with the aid of an optimization algorithm−interval method. The obtained TBP curves of substitute mixture are in good agreement with the experimentally obtained curves. Nine single carbon structural increments will be the representative of 93 real component compositions in order to make the topology of the neural network smaller and hence to have a less complex model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800794n
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3820–3824[article] On the introduction of a qualitative variable to the neural network for reactor modeling : feed type [texte imprimé] / Maryam Ghadrdan, Auteur ; Hamid Mehdizadeh, Auteur ; Ramin Bozorgmehry Boozarjomehry, Auteur . - 2009 . - pp. 3820–3824.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3820–3824
Mots-clés : Reactor feed type Hydrocarbons Neural networks Résumé : Thermal cracking of hydrocarbons converts them into valuable materials in the petrochemical industries. Multiplicity of the reaction routes and complexity of the mathematical approach has led us use a kind of black-box modeling—artificial neural networks. Reactor feed type plays an essential role on the product qualities. Feed type is a qualitative character. In this paper, a method is presented to introduce a range of petroleum fractions to the neural network. To introduce petroleum cuts with final boiling points of 865 °F maximum to the neural network, a real component substitute mixture is made from the original mixture. Such substitute mixture is fully defined, it has a chemical character, and physical properties can be simply retrieved from databases. The mixture compositions are defined with the aid of an optimization algorithm−interval method. The obtained TBP curves of substitute mixture are in good agreement with the experimentally obtained curves. Nine single carbon structural increments will be the representative of 93 real component compositions in order to make the topology of the neural network smaller and hence to have a less complex model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800794n Exemplaires
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Titre : Experimental and modeling analysis of methane partial oxidation : transient and steady-state behavior of rh-coated honeycomb monoliths Type de document : texte imprimé Auteurs : Alessandra Beretta, Auteur ; Gianpiero Groppi, Auteur ; Matteo Lualdi, Auteur Année de publication : 2009 Article en page(s) : pp. 3825–3836 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Rh-coated honeycomb monoliths Methane partial oxidation Steady state Résumé : The present study consists of an experimental and theoretical study of the performance of Rh-coated honeycomb monoliths for methane partial oxidation. The thermal behavior of Rh-coated honeycomb monoliths was studied under representative operating conditions, at steady state and during light-off. Model analysis (based on a dynamic heterogeneous reactor model that incorporates a kinetic scheme of the process independently developed, and well-assessed correlations for heat and mass transfer) provided a key for interpreting the observed effects. The comprehension of how transport phenomena and surface kinetics affect the reactor behavior leads to the conclusion that the feasibility of small-scale production of syngas via CH4 catalytic partial oxidation relies on thermal management of the short contact time reactor and not the obtainment of high syngas yields (which is not a challenging task). Severe operating conditions (and high surface temperatures) can deplete the catalyst activity and cause unstable reactor operation. Guidelines for optimal reactor design are proposed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017143
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3825–3836[article] Experimental and modeling analysis of methane partial oxidation : transient and steady-state behavior of rh-coated honeycomb monoliths [texte imprimé] / Alessandra Beretta, Auteur ; Gianpiero Groppi, Auteur ; Matteo Lualdi, Auteur . - 2009 . - pp. 3825–3836.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3825–3836
Mots-clés : Rh-coated honeycomb monoliths Methane partial oxidation Steady state Résumé : The present study consists of an experimental and theoretical study of the performance of Rh-coated honeycomb monoliths for methane partial oxidation. The thermal behavior of Rh-coated honeycomb monoliths was studied under representative operating conditions, at steady state and during light-off. Model analysis (based on a dynamic heterogeneous reactor model that incorporates a kinetic scheme of the process independently developed, and well-assessed correlations for heat and mass transfer) provided a key for interpreting the observed effects. The comprehension of how transport phenomena and surface kinetics affect the reactor behavior leads to the conclusion that the feasibility of small-scale production of syngas via CH4 catalytic partial oxidation relies on thermal management of the short contact time reactor and not the obtainment of high syngas yields (which is not a challenging task). Severe operating conditions (and high surface temperatures) can deplete the catalyst activity and cause unstable reactor operation. Guidelines for optimal reactor design are proposed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017143 Exemplaires
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Titre : Influence of the conditions of zincate on the electroless brass plating of steel Type de document : texte imprimé Auteurs : Carlos Dominguez-Rios, Auteur ; Georgina Gardea-Hernández, Auteur ; Roal Torres-Sanchez, Auteur Année de publication : 2009 Article en page(s) : pp. 3837–3843 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Zinc flash Steel Electroless brass plating Résumé : In this work, we report that zinc flash film must be applied on a substrate of steel in order to activate the surface for electroless brass plating and the effect of this layer on the final properties of brass film. It was established that the color of the brass film is highly dependent on the conditions of the application of the zinc flash. We found that the mechanism of electroless brass deposition begins with the partial dissolution of the zinc flash film. It was also found that a brass coating with good adhesion properties is obtained when the conditions of the zinc flash bath are as follows: current density of 10 A/dm2, immersion time of 30−45 s, and bath temperature of 40 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014445
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3837–3843[article] Influence of the conditions of zincate on the electroless brass plating of steel [texte imprimé] / Carlos Dominguez-Rios, Auteur ; Georgina Gardea-Hernández, Auteur ; Roal Torres-Sanchez, Auteur . - 2009 . - pp. 3837–3843.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3837–3843
Mots-clés : Zinc flash Steel Electroless brass plating Résumé : In this work, we report that zinc flash film must be applied on a substrate of steel in order to activate the surface for electroless brass plating and the effect of this layer on the final properties of brass film. It was established that the color of the brass film is highly dependent on the conditions of the application of the zinc flash. We found that the mechanism of electroless brass deposition begins with the partial dissolution of the zinc flash film. It was also found that a brass coating with good adhesion properties is obtained when the conditions of the zinc flash bath are as follows: current density of 10 A/dm2, immersion time of 30−45 s, and bath temperature of 40 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014445 Exemplaires
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Titre : Modeling sorption kinetics of carbon dioxide in glassy polymeric films using the nonequilibrium thermodynamics approach Type de document : texte imprimé Auteurs : Vito Carlà, Auteur ; Yazan Hussain, Auteur ; Christine Grant, Auteur Année de publication : 2009 Article en page(s) : pp. 3844–3854 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Glassy polymers Nonequilibrium thermodynamics One-dimensional transport model Carbon dioxide Sorption− diffusion− relaxation Résumé : The nonequilibrium thermodynamics of glassy polymers (NET-GP) approach ( Macromolecules 2005, 38, 10299.) has been applied to the development of a one-dimensional transport model aimed at describing the kinetics of sorption and dilation of polymeric films in supercritical carbon dioxide. The NET-GP model was combined with a simple rheological constitutive equation to build a sorption−diffusion−relaxation model able to describe mass uptake and swelling kinetics of polymeric films in contact with carbon dioxide over a wide range of pressures and temperatures. The model calculations are compared with data on mass sorption kinetics for CO2 in supported glassy poly(methyl methacrylate) (PMMA) films, measured in a high-pressure quartz crystal microbalance (QCM). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800655w
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3844–3854[article] Modeling sorption kinetics of carbon dioxide in glassy polymeric films using the nonequilibrium thermodynamics approach [texte imprimé] / Vito Carlà, Auteur ; Yazan Hussain, Auteur ; Christine Grant, Auteur . - 2009 . - pp. 3844–3854.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3844–3854
Mots-clés : Glassy polymers Nonequilibrium thermodynamics One-dimensional transport model Carbon dioxide Sorption− diffusion− relaxation Résumé : The nonequilibrium thermodynamics of glassy polymers (NET-GP) approach ( Macromolecules 2005, 38, 10299.) has been applied to the development of a one-dimensional transport model aimed at describing the kinetics of sorption and dilation of polymeric films in supercritical carbon dioxide. The NET-GP model was combined with a simple rheological constitutive equation to build a sorption−diffusion−relaxation model able to describe mass uptake and swelling kinetics of polymeric films in contact with carbon dioxide over a wide range of pressures and temperatures. The model calculations are compared with data on mass sorption kinetics for CO2 in supported glassy poly(methyl methacrylate) (PMMA) films, measured in a high-pressure quartz crystal microbalance (QCM). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800655w Exemplaires
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Titre : Factors affecting bubble size on foamed polymer-paperboard composites Type de document : texte imprimé Auteurs : Sriram K. Annapragada, Auteur ; Sujit Banerjee, Auteur Année de publication : 2009 Article en page(s) : pp. 3855–3859 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Foamed paperboard Pressure bubbles Vaporization Résumé : Foamed paperboard is a composite material with applications in the consumer products industry. The composite comprises a layer of paperboard sandwiched between two polymer films. One film foams upon heating while the other acts as a barrier. Foaming is caused by the vaporization of the small amount of moisture present in the board. The resulting increase in pressure bubbles the heat-softened polymer. During growth, the vapor driving force, which depends on the rate of vaporization, overcomes the opposing sheet resistance. Upon continued heating, the vapor escapes through the molten polymer film and from the sides of the board. Less than 2% of the total initial moisture accumulates inside the foam. The average bubble size is about five times lower than the maximum possible bubble size because of moisture losses. The final bubble size and foam thickness are dictated by the degree of bubble coalescence. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015413
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3855–3859[article] Factors affecting bubble size on foamed polymer-paperboard composites [texte imprimé] / Sriram K. Annapragada, Auteur ; Sujit Banerjee, Auteur . - 2009 . - pp. 3855–3859.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3855–3859
Mots-clés : Foamed paperboard Pressure bubbles Vaporization Résumé : Foamed paperboard is a composite material with applications in the consumer products industry. The composite comprises a layer of paperboard sandwiched between two polymer films. One film foams upon heating while the other acts as a barrier. Foaming is caused by the vaporization of the small amount of moisture present in the board. The resulting increase in pressure bubbles the heat-softened polymer. During growth, the vapor driving force, which depends on the rate of vaporization, overcomes the opposing sheet resistance. Upon continued heating, the vapor escapes through the molten polymer film and from the sides of the board. Less than 2% of the total initial moisture accumulates inside the foam. The average bubble size is about five times lower than the maximum possible bubble size because of moisture losses. The final bubble size and foam thickness are dictated by the degree of bubble coalescence. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015413 Exemplaires
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Titre : Reduction of chemical reaction mechanism for halide-assisted silicon carbide epitaxial film deposition Type de document : texte imprimé Auteurs : Rong Wang, Auteur ; Ronghui Ma, Auteur ; Michael Dudley, Auteur Année de publication : 2009 Article en page(s) : pp. 3860–3866 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas-phase composition Halide-assisted chemical vapor deposition Silicon carbide film growth Three-dimensional simulation Résumé : Simulation of gas-phase and surface chemistry is an essential part in numerical study of chemical vapor deposition for film growth. When integrated with a model for transport processes such as gas flow, heat transfer, and mass transfer, it allows the prediction of gas-phase composition, film deposition rate, and film uniformity. For halide-assisted chemical vapor deposition of silicon carbide film growth, three-dimensional simulation of the deposition process can be time-consuming due to the large number of chemical reactions involved. In this study, a simplified chemical reaction mechanism was developed for silicon carbide growth with silicon tetrachloride and propane as precursors. After model validation, the reduced reaction steps were implemented into a three-dimensional simulation of halide-assisted chemical vapor deposition to predict the distributions of gas velocity, temperature, concentration of the intermediate reactants, and film deposition rate. Specifically, the effects of deposition pressure on the film growth were investigated. The integrated model for chemistry and transport process demonstrated the capability of modeling a deposition process with reasonable computing time. We envision that this model will provide a useful tool for design, test, and optimization of the deposition process for growing silicon carbide films or bulk crystals by use of halide-assisted chemical vapor deposition process. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017093
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3860–3866[article] Reduction of chemical reaction mechanism for halide-assisted silicon carbide epitaxial film deposition [texte imprimé] / Rong Wang, Auteur ; Ronghui Ma, Auteur ; Michael Dudley, Auteur . - 2009 . - pp. 3860–3866.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3860–3866
Mots-clés : Gas-phase composition Halide-assisted chemical vapor deposition Silicon carbide film growth Three-dimensional simulation Résumé : Simulation of gas-phase and surface chemistry is an essential part in numerical study of chemical vapor deposition for film growth. When integrated with a model for transport processes such as gas flow, heat transfer, and mass transfer, it allows the prediction of gas-phase composition, film deposition rate, and film uniformity. For halide-assisted chemical vapor deposition of silicon carbide film growth, three-dimensional simulation of the deposition process can be time-consuming due to the large number of chemical reactions involved. In this study, a simplified chemical reaction mechanism was developed for silicon carbide growth with silicon tetrachloride and propane as precursors. After model validation, the reduced reaction steps were implemented into a three-dimensional simulation of halide-assisted chemical vapor deposition to predict the distributions of gas velocity, temperature, concentration of the intermediate reactants, and film deposition rate. Specifically, the effects of deposition pressure on the film growth were investigated. The integrated model for chemistry and transport process demonstrated the capability of modeling a deposition process with reasonable computing time. We envision that this model will provide a useful tool for design, test, and optimization of the deposition process for growing silicon carbide films or bulk crystals by use of halide-assisted chemical vapor deposition process. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017093 Exemplaires
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Titre : Application of FT-IR-ATR spectroscopy to evaluate the penetration of surface sizing agents into the paper structure Type de document : texte imprimé Auteurs : Paulo J. Ferreira, Auteur ; José A. Gamelas, Auteur ; Isabel M. Moutinho, Auteur Année de publication : 2009 Article en page(s) : pp. 3867–3872 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fourier transform infrared spectroscopy Paper surface sizing Résumé : It is widely recognized that the surface properties of paper depend on the fibrous matrix and the final surface treatment applied to the paper. Regarding chemical paper surface treatments, an important issue is the evaluation of the penetration of chemical compounds into the fibrous matrix, as the chemicals can potentially cause changes in the intrinsic properties of paper. The work presented here aimed to use Fourier transform infrared (FT-IR) spectroscopy to study paper surface sizing, namely, the penetration of the sizing chemicals into the paper structure. Two different surface sizing formulations were applied to paper produced from Eucalyptus globulus bleached pulp (reference paper): both contain 90% (w/w) cationic starch, but one contains 10% (w/w) poly(styrene-co-maleic anhydride) whereas the other contains 10% (w/w) poly(styrene-co-butyl acrylate). The surface-sized paper sheets were further manually delaminated, so that the top surfaces as well as the internal layers could be analyzed by FT-IR spectroscopy. A non-surface-sized sample was taken as the reference. From the spectroscopic results, it was possible to detect the presence of the copolymers on the paper top surfaces, despite the application of only small amounts of these chemicals in the surface sizing. However, the chemicals were not found in the layers closest to the surface (30−40 μm from the top), leading to the conclusion that the penetration of the sizing formulations into the fibrous matrix was insignificant (at least up to this distance). Infrared spectroscopy data also showed that the calcium carbonate added as a filler was always present at higher concentration in the analyzed inner layers than at the top surface, for the reference paper as well as the sized papers. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801765c
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3867–3872[article] Application of FT-IR-ATR spectroscopy to evaluate the penetration of surface sizing agents into the paper structure [texte imprimé] / Paulo J. Ferreira, Auteur ; José A. Gamelas, Auteur ; Isabel M. Moutinho, Auteur . - 2009 . - pp. 3867–3872.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3867–3872
Mots-clés : Fourier transform infrared spectroscopy Paper surface sizing Résumé : It is widely recognized that the surface properties of paper depend on the fibrous matrix and the final surface treatment applied to the paper. Regarding chemical paper surface treatments, an important issue is the evaluation of the penetration of chemical compounds into the fibrous matrix, as the chemicals can potentially cause changes in the intrinsic properties of paper. The work presented here aimed to use Fourier transform infrared (FT-IR) spectroscopy to study paper surface sizing, namely, the penetration of the sizing chemicals into the paper structure. Two different surface sizing formulations were applied to paper produced from Eucalyptus globulus bleached pulp (reference paper): both contain 90% (w/w) cationic starch, but one contains 10% (w/w) poly(styrene-co-maleic anhydride) whereas the other contains 10% (w/w) poly(styrene-co-butyl acrylate). The surface-sized paper sheets were further manually delaminated, so that the top surfaces as well as the internal layers could be analyzed by FT-IR spectroscopy. A non-surface-sized sample was taken as the reference. From the spectroscopic results, it was possible to detect the presence of the copolymers on the paper top surfaces, despite the application of only small amounts of these chemicals in the surface sizing. However, the chemicals were not found in the layers closest to the surface (30−40 μm from the top), leading to the conclusion that the penetration of the sizing formulations into the fibrous matrix was insignificant (at least up to this distance). Infrared spectroscopy data also showed that the calcium carbonate added as a filler was always present at higher concentration in the analyzed inner layers than at the top surface, for the reference paper as well as the sized papers. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801765c Exemplaires
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Titre : Time-optimal control of startup distillation of nonideal mixtures Type de document : texte imprimé Auteurs : Alexandru Woinaroschy, Auteur Année de publication : 2009 Article en page(s) : pp. 3873–3879 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Startup distillation columns Time-optimal control Nonideal mixtures Iterative dynamic programming Résumé : In this work, the time-optimal control of startup distillation columns by iterative programming proposed by Woinaroschy [ Ind. Eng. Chem. Res. 2008, 47, 4158.] is extended to the case of nonideal mixtures. The minimization of distillation startup time is performed by iterative dynamic programming employing randomly chosen candidates for admissible control. The control variables are the reflux ratio and/or the reboiler heat duty. The dynamic distillation model proposed by the author in the mentioned work is applied with a preliminary computation of suitable correlation relations for equilibrium constants. An illustrative application for separation of a propene−propane mixture at plant scale is presented. Because of the small relative volatility of this mixture and respective high reflux ratio, the decrease of the reboiler heat consumption corresponding to the minimization of the startup time is significant. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801490r
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3873–3879[article] Time-optimal control of startup distillation of nonideal mixtures [texte imprimé] / Alexandru Woinaroschy, Auteur . - 2009 . - pp. 3873–3879.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3873–3879
Mots-clés : Startup distillation columns Time-optimal control Nonideal mixtures Iterative dynamic programming Résumé : In this work, the time-optimal control of startup distillation columns by iterative programming proposed by Woinaroschy [ Ind. Eng. Chem. Res. 2008, 47, 4158.] is extended to the case of nonideal mixtures. The minimization of distillation startup time is performed by iterative dynamic programming employing randomly chosen candidates for admissible control. The control variables are the reflux ratio and/or the reboiler heat duty. The dynamic distillation model proposed by the author in the mentioned work is applied with a preliminary computation of suitable correlation relations for equilibrium constants. An illustrative application for separation of a propene−propane mixture at plant scale is presented. Because of the small relative volatility of this mixture and respective high reflux ratio, the decrease of the reboiler heat consumption corresponding to the minimization of the startup time is significant. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801490r Exemplaires
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Titre : Advanced control strategies for the regulation of hypnosis with propofol Type de document : texte imprimé Auteurs : Yelneedi Sreenivas, Auteur ; Lakshminarayanan Samavedham, Auteur ; G.P. Rangaiah, Auteur Année de publication : 2009 Article en page(s) : pp. 3880–3897 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hypnosis Propofol Bispectral index Nonlinear PK− PD representation Résumé : Anesthesia implies maintaining a triad of hypnosis, analgesia, and neuromuscular blockade by infusing several drugs which specifically act on each of the above aspects. This work focuses on controlling the hypnosis by automatic infusion of propofol using bispectral index (BIS) as the primary controlled variable. A fourth-order nonlinear pharmacokinetic (PK)−pharmacodynamic (PD) representation is used for the hypnosis dynamics of patients. A reliable PK−PD model with associated parameters is obtained from the literature and the closed-loop responses of four types of control strategies (model predictive control, internal model control, controller with modeling error compensation, and proportional-integral-derivative (PID) control) are compared. Robust performance of the four controllers is tested for a broad range of patients by considering variability in PK−PD parameters. Also, the relative performance of the four controllers is studied for different set-points, noise, and disturbances in BIS signal. Numerical simulations show that all the advanced controllers performed better than the PID controller with the model predictive controller showing the best performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800695b
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3880–3897[article] Advanced control strategies for the regulation of hypnosis with propofol [texte imprimé] / Yelneedi Sreenivas, Auteur ; Lakshminarayanan Samavedham, Auteur ; G.P. Rangaiah, Auteur . - 2009 . - pp. 3880–3897.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3880–3897
Mots-clés : Hypnosis Propofol Bispectral index Nonlinear PK− PD representation Résumé : Anesthesia implies maintaining a triad of hypnosis, analgesia, and neuromuscular blockade by infusing several drugs which specifically act on each of the above aspects. This work focuses on controlling the hypnosis by automatic infusion of propofol using bispectral index (BIS) as the primary controlled variable. A fourth-order nonlinear pharmacokinetic (PK)−pharmacodynamic (PD) representation is used for the hypnosis dynamics of patients. A reliable PK−PD model with associated parameters is obtained from the literature and the closed-loop responses of four types of control strategies (model predictive control, internal model control, controller with modeling error compensation, and proportional-integral-derivative (PID) control) are compared. Robust performance of the four controllers is tested for a broad range of patients by considering variability in PK−PD parameters. Also, the relative performance of the four controllers is studied for different set-points, noise, and disturbances in BIS signal. Numerical simulations show that all the advanced controllers performed better than the PID controller with the model predictive controller showing the best performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800695b Exemplaires
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Titre : Rolling operation algorithm for solving complex scheduling problems Type de document : texte imprimé Auteurs : Barbara Czuczai, Auteur ; Tivadar Farkas, Auteur ; Endre Rev, Auteur Année de publication : 2009 Article en page(s) : pp. 3898–3908 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Large-scale problems Rolling operation” algorithm Résumé : Large-scale scheduling problems have remained difficult to solve despite the intense research in the area and many successful algorithms. In this paper, a new decomposition algorithm is presented which finds a good feasible solution even for large-scale problems in a reasonable time. In each iteration, a maximum allowed number of operations is first assigned to available units, then the algorithm alternates between a production quantity maximization step and a production time minimization step in each iteration. The performance of the “rolling operation” algorithm is illustrated using an industrial example. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801037k
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3898–3908[article] Rolling operation algorithm for solving complex scheduling problems [texte imprimé] / Barbara Czuczai, Auteur ; Tivadar Farkas, Auteur ; Endre Rev, Auteur . - 2009 . - pp. 3898–3908.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3898–3908
Mots-clés : Large-scale problems Rolling operation” algorithm Résumé : Large-scale scheduling problems have remained difficult to solve despite the intense research in the area and many successful algorithms. In this paper, a new decomposition algorithm is presented which finds a good feasible solution even for large-scale problems in a reasonable time. In each iteration, a maximum allowed number of operations is first assigned to available units, then the algorithm alternates between a production quantity maximization step and a production time minimization step in each iteration. The performance of the “rolling operation” algorithm is illustrated using an industrial example. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801037k Exemplaires
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Titre : Comprehensive simulation of an intensified process for H2 production from steam gasification of biomass Type de document : texte imprimé Auteurs : Peijun Ji, Auteur ; Wei Feng, Auteur ; Biaohua Chen, Auteur Année de publication : 2009 Article en page(s) : pp. 3909–3920 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Biomass gasification Hydrogen Bubbling fluidized bed gasifier Steam reformer H2-membrane water-gas-shift reactor Résumé : For producing pure hydrogen from biomass gasification with steam as the gasifying agent, an intensified process is proposed. In the process, a bubbling fluidized bed gasifier is used for the steam gasification of biomass, a steam reformer is used for upgrading the biosyngas, and an H2-membrane water-gas-shift (HMWGS) reactor is used for converting the carbon monoxide and separating the hydrogen. Pure hydrogen is the product of the process. High-purity CO2 can be produced and taken as a coproduct. To better simulate the proposed process, models for the steam-blown fluidized bed gasifier and catalytic steam reformer have been developed. The simulation results have been compared with the experimental data, and good agreement has been obtained. The analysis of the proposed process is carried out in terms of the amount of pure hydrogen per kilogram of biomass and the overall thermodynamic efficiency of the process. Factors affecting the pure hydrogen production and thermodynamic efficiency have been studied and discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801191g
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3909–3920[article] Comprehensive simulation of an intensified process for H2 production from steam gasification of biomass [texte imprimé] / Peijun Ji, Auteur ; Wei Feng, Auteur ; Biaohua Chen, Auteur . - 2009 . - pp. 3909–3920.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3909–3920
Mots-clés : Biomass gasification Hydrogen Bubbling fluidized bed gasifier Steam reformer H2-membrane water-gas-shift reactor Résumé : For producing pure hydrogen from biomass gasification with steam as the gasifying agent, an intensified process is proposed. In the process, a bubbling fluidized bed gasifier is used for the steam gasification of biomass, a steam reformer is used for upgrading the biosyngas, and an H2-membrane water-gas-shift (HMWGS) reactor is used for converting the carbon monoxide and separating the hydrogen. Pure hydrogen is the product of the process. High-purity CO2 can be produced and taken as a coproduct. To better simulate the proposed process, models for the steam-blown fluidized bed gasifier and catalytic steam reformer have been developed. The simulation results have been compared with the experimental data, and good agreement has been obtained. The analysis of the proposed process is carried out in terms of the amount of pure hydrogen per kilogram of biomass and the overall thermodynamic efficiency of the process. Factors affecting the pure hydrogen production and thermodynamic efficiency have been studied and discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801191g Exemplaires
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Titre : Enhancing abnormal events management by the use of quantitative process hazards analysis results Type de document : texte imprimé Auteurs : Ignacio Yélamos, Auteur ; Aarón Bojarski, Auteur ; Girish Joglekar, Auteur Année de publication : 2009 Article en page(s) : pp. 3921–3933 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Abnormal events management Process hazards analysis Dynamic integration Résumé : Thorough process abnormal events management (AEM) requires accurate fault diagnosis and also a complete supporting system for making correct decisions. In this work, an effective and dynamic integration of AEM and process hazards analysis (PHA) is carried out. In the integrated system, the HAZOP analysis is extended for its use as a supporting tool when facing online abnormal situations. Thus, the extended HAZOP analysis includes quantitative information, in the form of key variables thresholds, and incorporates a set of corrective actions (CAs) to mitigate the harmful considered consequences. The dynamic integration is achieved by generating a protocol where CAs are ranked by the seriousness and urgency of the consequences that they mitigate. The supporting system is developed in a Matlab and Aspen Dynamics integrated framework. An industrial sour water stripping plant is used as case study. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800405n
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3921–3933[article] Enhancing abnormal events management by the use of quantitative process hazards analysis results [texte imprimé] / Ignacio Yélamos, Auteur ; Aarón Bojarski, Auteur ; Girish Joglekar, Auteur . - 2009 . - pp. 3921–3933.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3921–3933
Mots-clés : Abnormal events management Process hazards analysis Dynamic integration Résumé : Thorough process abnormal events management (AEM) requires accurate fault diagnosis and also a complete supporting system for making correct decisions. In this work, an effective and dynamic integration of AEM and process hazards analysis (PHA) is carried out. In the integrated system, the HAZOP analysis is extended for its use as a supporting tool when facing online abnormal situations. Thus, the extended HAZOP analysis includes quantitative information, in the form of key variables thresholds, and incorporates a set of corrective actions (CAs) to mitigate the harmful considered consequences. The dynamic integration is achieved by generating a protocol where CAs are ranked by the seriousness and urgency of the consequences that they mitigate. The supporting system is developed in a Matlab and Aspen Dynamics integrated framework. An industrial sour water stripping plant is used as case study. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800405n Exemplaires
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Titre : Multilinear model control of Hammerstein-like systems based on an included angle dividing method and the MLD-MPC strategy Type de document : texte imprimé Auteurs : Jingjing Du, Auteur ; Chunyue Song, Auteur ; Li Ping, Auteur Année de publication : 2009 Article en page(s) : pp. 3934–3943 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hammerstein-like systems Multilinear model control Closed-loop simulations Résumé : This article introduces the multilinear model control approach to SISO Hammerstein-like systems. An included angle dividing method is proposed to decompose the operating spaces and determine linear model banks for SISO Hammerstein-like systems through measuring the nonlinearity of the static IO curves. On the basis of the linear model bank, the MLD-MPC strategy is employed for set-point tracking control. Two chemical processes are studied using the proposed included angle dividing method and MLD-MPC strategy. Closed-loop simulations demonstrate that the proposed dividing method is useful and effective for the multilinear model approach and the MLD-MPC strategy is excellent for nonlinear systems. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8009395
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3934–3943[article] Multilinear model control of Hammerstein-like systems based on an included angle dividing method and the MLD-MPC strategy [texte imprimé] / Jingjing Du, Auteur ; Chunyue Song, Auteur ; Li Ping, Auteur . - 2009 . - pp. 3934–3943.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3934–3943
Mots-clés : Hammerstein-like systems Multilinear model control Closed-loop simulations Résumé : This article introduces the multilinear model control approach to SISO Hammerstein-like systems. An included angle dividing method is proposed to decompose the operating spaces and determine linear model banks for SISO Hammerstein-like systems through measuring the nonlinearity of the static IO curves. On the basis of the linear model bank, the MLD-MPC strategy is employed for set-point tracking control. Two chemical processes are studied using the proposed included angle dividing method and MLD-MPC strategy. Closed-loop simulations demonstrate that the proposed dividing method is useful and effective for the multilinear model approach and the MLD-MPC strategy is excellent for nonlinear systems. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8009395 Exemplaires
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Titre : MPC constraint analysis : Bayesian approach via a continuous-valued profit function Type de document : texte imprimé Auteurs : Seyi Akande, Auteur ; Biao Huang, Auteur ; Kwan Ho Lee, Auteur Année de publication : 2009 Article en page(s) : pp. 3944–3954 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Model predictive control Bayesian probabilistic framework Résumé : Model predictive control (MPC) is one of the most studied modern control technologies. Among the various subjects investigated, controller performance assessment of MPC has received considerable attention in recent time. Various approaches and algorithms have been proposed for the assessment of MPCs. In this work, we propose a novel approach to MPC constraint analysis by considering the economic objective function as a continuous-valued function within a Bayesian probabilistic framework. The analysis involves inference of the effect of a decision to adjust the limits of the constrained variables with regards to the achievable profits (decision evaluation) as well as inference of constraint limits that should be adjusted so as to achieve a specified profit value (decision making). The benefits of this approach include a more generalized definition of quality variables, the development of a more rigorous formulation of the problem to address linear and quadratic objective functions and thereby obtaining closed form solutions, and maximum-likelihood location determination of the quality variables in the decision making process. The approach is illustrated with the use of simulations and a pilot-scale experiment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011566
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3944–3954[article] MPC constraint analysis : Bayesian approach via a continuous-valued profit function [texte imprimé] / Seyi Akande, Auteur ; Biao Huang, Auteur ; Kwan Ho Lee, Auteur . - 2009 . - pp. 3944–3954.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3944–3954
Mots-clés : Model predictive control Bayesian probabilistic framework Résumé : Model predictive control (MPC) is one of the most studied modern control technologies. Among the various subjects investigated, controller performance assessment of MPC has received considerable attention in recent time. Various approaches and algorithms have been proposed for the assessment of MPCs. In this work, we propose a novel approach to MPC constraint analysis by considering the economic objective function as a continuous-valued function within a Bayesian probabilistic framework. The analysis involves inference of the effect of a decision to adjust the limits of the constrained variables with regards to the achievable profits (decision evaluation) as well as inference of constraint limits that should be adjusted so as to achieve a specified profit value (decision making). The benefits of this approach include a more generalized definition of quality variables, the development of a more rigorous formulation of the problem to address linear and quadratic objective functions and thereby obtaining closed form solutions, and maximum-likelihood location determination of the quality variables in the decision making process. The approach is illustrated with the use of simulations and a pilot-scale experiment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011566 Exemplaires
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Titre : Multifactor statistical analysis of H2O2-enhanced photodegradation of nicotine and phosphamidon Type de document : texte imprimé Auteurs : Amanda M. Nienow, Auteur ; Inez Hua, Auteur ; Irene C. Poyer, Auteur Année de publication : 2009 Article en page(s) : pp. 3955–3963 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Aqueous nicotine Phosphamidon Indirect photolysis Résumé : Direct and indirect photolysis (λ = 254 nm) of aqueous nicotine and phosphamidon were studied. A central composite design was used to explore the effects of initial [H2O2] (0−10 mM), pH (2.8−11.2), and ionic strength (Ic = 0.02−0.71 M) on the rate constants of nicotine and phosphamidon separately dissolved in a surface water surrogate matrix. Five levels of each factor were included in the design. For nicotine, the fastest predicted photochemical oxidation rate constant (k = 0.43 min−1) occurred under the following conditions: pH = 7.5, [H2O2] = 7.5 mM, and Ic = 0.02 M. This rate constant predicts that 90% of the nicotine will react within 5.4 min under these conditions. In general, the photochemical oxidation of nicotine is more rapid at lower ionic strength and near-neutral pH values. For phosphamidon, the fastest predicted oxidation rate constant (k = 0.65 min−1) occurred at a pH of 7.1 and [H2O2] of 5 mM. Under these conditions, 90% of the phosphamidon would react within 3.5 min of treatment. Like nicotine, the photochemical oxidation of phosphamidon is more rapid at near-neutral pH values. Ionic strength has no significant effect on the photochemical oxidation of phosphamidon. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801311f
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3955–3963[article] Multifactor statistical analysis of H2O2-enhanced photodegradation of nicotine and phosphamidon [texte imprimé] / Amanda M. Nienow, Auteur ; Inez Hua, Auteur ; Irene C. Poyer, Auteur . - 2009 . - pp. 3955–3963.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3955–3963
Mots-clés : Aqueous nicotine Phosphamidon Indirect photolysis Résumé : Direct and indirect photolysis (λ = 254 nm) of aqueous nicotine and phosphamidon were studied. A central composite design was used to explore the effects of initial [H2O2] (0−10 mM), pH (2.8−11.2), and ionic strength (Ic = 0.02−0.71 M) on the rate constants of nicotine and phosphamidon separately dissolved in a surface water surrogate matrix. Five levels of each factor were included in the design. For nicotine, the fastest predicted photochemical oxidation rate constant (k = 0.43 min−1) occurred under the following conditions: pH = 7.5, [H2O2] = 7.5 mM, and Ic = 0.02 M. This rate constant predicts that 90% of the nicotine will react within 5.4 min under these conditions. In general, the photochemical oxidation of nicotine is more rapid at lower ionic strength and near-neutral pH values. For phosphamidon, the fastest predicted oxidation rate constant (k = 0.65 min−1) occurred at a pH of 7.1 and [H2O2] of 5 mM. Under these conditions, 90% of the phosphamidon would react within 3.5 min of treatment. Like nicotine, the photochemical oxidation of phosphamidon is more rapid at near-neutral pH values. Ionic strength has no significant effect on the photochemical oxidation of phosphamidon. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801311f Exemplaires
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Titre : Optimization and management of flotation deinking banks by process simulation Type de document : texte imprimé Auteurs : Davide Beneventi, Auteur ; Elisa Zeno, Auteur ; Patrice Nortier, Auteur Année de publication : 2009 Article en page(s) : pp. 3964–3972 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Flotation deinking banks Mixed tank/column cells Résumé : In this work, the contribution of flotation deinking banks design on ink removal efficiency, selectivity, and specific energy consumption was simulated using a semiempirical approach. Single-stage with mixed tank/column cells, two-stage, and three-stage configurations were evaluated, and the total number of flotation units in each stage and their interconnection were used as main variables. Explicit correlations between ink removal efficiency, selectivity, energy consumption, and line design were developed for each configuration. When considering a conventional two-stage configuration as reference, a decrease in the specific energy consumption for constant ink removal efficiency and selectivity was obtained with the single-stage bank with a stack of flotation columns at the front of the line, whereas an increase in ink removal selectivity for constant ink removal efficiency and specific energy consumption was obtained with the three-stage bank. The present results show that the performance of conventional flotation deinking banks can be improved by optimizing process design and implementing mixed tank/column technologies in the same deinking line. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801753j
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3964–3972[article] Optimization and management of flotation deinking banks by process simulation [texte imprimé] / Davide Beneventi, Auteur ; Elisa Zeno, Auteur ; Patrice Nortier, Auteur . - 2009 . - pp. 3964–3972.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3964–3972
Mots-clés : Flotation deinking banks Mixed tank/column cells Résumé : In this work, the contribution of flotation deinking banks design on ink removal efficiency, selectivity, and specific energy consumption was simulated using a semiempirical approach. Single-stage with mixed tank/column cells, two-stage, and three-stage configurations were evaluated, and the total number of flotation units in each stage and their interconnection were used as main variables. Explicit correlations between ink removal efficiency, selectivity, energy consumption, and line design were developed for each configuration. When considering a conventional two-stage configuration as reference, a decrease in the specific energy consumption for constant ink removal efficiency and selectivity was obtained with the single-stage bank with a stack of flotation columns at the front of the line, whereas an increase in ink removal selectivity for constant ink removal efficiency and specific energy consumption was obtained with the three-stage bank. The present results show that the performance of conventional flotation deinking banks can be improved by optimizing process design and implementing mixed tank/column technologies in the same deinking line. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801753j Exemplaires
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Titre : Selective extraction of neutral nitrogen-containing compounds from straight-run diesel feed using polymer-supported ionic liquid moieties Type de document : texte imprimé Auteurs : Li-Li Xie, Auteur ; Alain Favre-Reguillon, Auteur ; Xu-Xu Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 3973–3977 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polar compounds Hydrodesulfurization process Chloride-based ionic liquids Diesel feeds Résumé : The extraction of trace polar compounds, among them neutral nitrogen-containing compounds (N-compounds), has received much attention from refiners because of their inhibiting effect on the hydrodesulfurization (HDS) process. Recently, we have shown that chloride-based ionic liquids (ILs) can selectively extract N-compounds from straight-run diesel feeds. However, the measurable solubility of ILs in hydrocarbon fuel is not a desired outcome of the process. Thus, the covalent binding of ILs moieties on polymers was studied. Starting from Merrifield resin, three resins were prepared with imidazolium, pyridinium, and triethylammonium chloride functionality. The resins were evaluated using a synthetic solution with dibenzothiophene and carbazole as model compounds, and a high selectivity for N-compounds was found. Imidazolium and pyridinium resins were then further evaluated using straight-run diesel feed containing 13400 ppm S and 105 ppm N. The selectivity toward N-compounds was comparable to the selectivity observed with ILs. Moreover, the resins could be easily regenerated using a protic solvent like methanol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900142p
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3973–3977[article] Selective extraction of neutral nitrogen-containing compounds from straight-run diesel feed using polymer-supported ionic liquid moieties [texte imprimé] / Li-Li Xie, Auteur ; Alain Favre-Reguillon, Auteur ; Xu-Xu Wang, Auteur . - 2009 . - pp. 3973–3977.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3973–3977
Mots-clés : Polar compounds Hydrodesulfurization process Chloride-based ionic liquids Diesel feeds Résumé : The extraction of trace polar compounds, among them neutral nitrogen-containing compounds (N-compounds), has received much attention from refiners because of their inhibiting effect on the hydrodesulfurization (HDS) process. Recently, we have shown that chloride-based ionic liquids (ILs) can selectively extract N-compounds from straight-run diesel feeds. However, the measurable solubility of ILs in hydrocarbon fuel is not a desired outcome of the process. Thus, the covalent binding of ILs moieties on polymers was studied. Starting from Merrifield resin, three resins were prepared with imidazolium, pyridinium, and triethylammonium chloride functionality. The resins were evaluated using a synthetic solution with dibenzothiophene and carbazole as model compounds, and a high selectivity for N-compounds was found. Imidazolium and pyridinium resins were then further evaluated using straight-run diesel feed containing 13400 ppm S and 105 ppm N. The selectivity toward N-compounds was comparable to the selectivity observed with ILs. Moreover, the resins could be easily regenerated using a protic solvent like methanol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900142p Exemplaires
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Titre : Enhancing capacity of activated carbons for hydrogen purification Type de document : texte imprimé Auteurs : Filipe V. S. Lopes, Auteur ; Carlos A. Grande, Auteur ; Ana M. Ribeiro, Auteur Année de publication : 2009 Article en page(s) : pp. 3978–3990 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Steam methane reforming Pressure swing adsorption Activated carbon Résumé : The commercial technology for the separation of off-gases from steam methane reforming is pressure swing adsorption (PSA). To improve the performance of the PSA units, materials with enhanced capacity toward contaminants are required. In this work, a commercial activated carbon (AC) was used for the preparation of a new material with enhanced capacity toward contaminants (CO2, CH4, CO, and N2). Different samples were prepared by physical activation with CO2 under different operating conditions. The conditions where the sample with the highest microporosity was obtained were reproduced to prepare a scale-up of 400 g. Carbon dioxide, hydrogen, methane, carbon monoxide, and nitrogen adsorption equilibrium and kinetics were studied on the modified AC and compared to the original AC results. An improvement of CO2 adsorption capacity of 17.5% was observed at 303 K and 7 bar. Carbon dioxide micropore diffusivity of same order of magnitude (Dc/rc2 = ∼4 × 10−2 s−1 at 303 K) was observed for both adsorbents. Finally, ternary breakthrough curves (CO2−H2−CH4) were performed for the validation of the multicomponent adsorption equilibrium. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801132t
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3978–3990[article] Enhancing capacity of activated carbons for hydrogen purification [texte imprimé] / Filipe V. S. Lopes, Auteur ; Carlos A. Grande, Auteur ; Ana M. Ribeiro, Auteur . - 2009 . - pp. 3978–3990.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3978–3990
Mots-clés : Steam methane reforming Pressure swing adsorption Activated carbon Résumé : The commercial technology for the separation of off-gases from steam methane reforming is pressure swing adsorption (PSA). To improve the performance of the PSA units, materials with enhanced capacity toward contaminants are required. In this work, a commercial activated carbon (AC) was used for the preparation of a new material with enhanced capacity toward contaminants (CO2, CH4, CO, and N2). Different samples were prepared by physical activation with CO2 under different operating conditions. The conditions where the sample with the highest microporosity was obtained were reproduced to prepare a scale-up of 400 g. Carbon dioxide, hydrogen, methane, carbon monoxide, and nitrogen adsorption equilibrium and kinetics were studied on the modified AC and compared to the original AC results. An improvement of CO2 adsorption capacity of 17.5% was observed at 303 K and 7 bar. Carbon dioxide micropore diffusivity of same order of magnitude (Dc/rc2 = ∼4 × 10−2 s−1 at 303 K) was observed for both adsorbents. Finally, ternary breakthrough curves (CO2−H2−CH4) were performed for the validation of the multicomponent adsorption equilibrium. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801132t Exemplaires
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Titre : Characterization of surface-bound Zr(IV) and its application to removal of As(V) and As(III) from aqueous systems using phosphonic acid modified nanoporous silica polyamine composites Type de document : texte imprimé Auteurs : Varadharajan Kailasam, Auteur ; Edward Rosenberg, Auteur ; Daniel Nielsen, Auteur Année de publication : 2009 Article en page(s) : pp. 3991–4001 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Silica polyamine composites Phosphonic acid modified composite Mannich reaction Résumé : Silica polyamine composites (SPC) made from silanized amorphous nanoporous silica gel and poly(allylamine) (BP-1) were functionalized with phosphorus acid using the Mannich reaction, resulting in a phosphonic acid modified composite (BPAP). Successful immobilization of the phosphonic acid ligand was confirmed by mass gain, elemental analysis, IR, and solid-state NMR. The modified composite had a ligand loading of 1.5 mmol/g, corresponding to N/P ratio of 0.73. Zirconium(IV) was immobilized on BPAP with a loading of 1.12 mmol/g. Zirconium loading was analyzed by mass gain, ICP/AES, and SEM/EDX. Arsenate anions strongly adsorbed on the ZrBPAP composite in the pH range 2−8, while arsenite only adsorbed well at pH 10. The sorption mechanism is a chelation between arsenate or arsenite and Zr(IV)−phosphonic acid complex of BPAP. Adsorption isotherm data were found to be well modeled by the Langmuir equation for As(V) at pH 4 with Kads = 0.016 L/g and Qm = 98 mg/g; and at pH 6 with Kads = 0.018 L/g and Qm = 56 mg/g. Regeneration of the resin was carried out successfully for As(V) and As(III) using 2M-H2SO4. Four adsorption/desorption cycles were performed for As(V) at pH 4 without significant decrease in the uptake performance. ZrBPAP capture capacity and kinetics for arsenate were tested for longevity over 1000 cycles with only a marginal loss of performance. This composite is highly selective for arsenate over sulfate (As/SO42− = 50/1) and selenate (As/Se = 20/1); lower selectivity was observed with Fe(III) and Th(IV) loaded BPAP. The significance of the observed selectivity is discussed in terms of the chemical properties of the anion and the nature of the interactions with the immobilized metal site. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016362
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3991–4001[article] Characterization of surface-bound Zr(IV) and its application to removal of As(V) and As(III) from aqueous systems using phosphonic acid modified nanoporous silica polyamine composites [texte imprimé] / Varadharajan Kailasam, Auteur ; Edward Rosenberg, Auteur ; Daniel Nielsen, Auteur . - 2009 . - pp. 3991–4001.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3991–4001
Mots-clés : Silica polyamine composites Phosphonic acid modified composite Mannich reaction Résumé : Silica polyamine composites (SPC) made from silanized amorphous nanoporous silica gel and poly(allylamine) (BP-1) were functionalized with phosphorus acid using the Mannich reaction, resulting in a phosphonic acid modified composite (BPAP). Successful immobilization of the phosphonic acid ligand was confirmed by mass gain, elemental analysis, IR, and solid-state NMR. The modified composite had a ligand loading of 1.5 mmol/g, corresponding to N/P ratio of 0.73. Zirconium(IV) was immobilized on BPAP with a loading of 1.12 mmol/g. Zirconium loading was analyzed by mass gain, ICP/AES, and SEM/EDX. Arsenate anions strongly adsorbed on the ZrBPAP composite in the pH range 2−8, while arsenite only adsorbed well at pH 10. The sorption mechanism is a chelation between arsenate or arsenite and Zr(IV)−phosphonic acid complex of BPAP. Adsorption isotherm data were found to be well modeled by the Langmuir equation for As(V) at pH 4 with Kads = 0.016 L/g and Qm = 98 mg/g; and at pH 6 with Kads = 0.018 L/g and Qm = 56 mg/g. Regeneration of the resin was carried out successfully for As(V) and As(III) using 2M-H2SO4. Four adsorption/desorption cycles were performed for As(V) at pH 4 without significant decrease in the uptake performance. ZrBPAP capture capacity and kinetics for arsenate were tested for longevity over 1000 cycles with only a marginal loss of performance. This composite is highly selective for arsenate over sulfate (As/SO42− = 50/1) and selenate (As/Se = 20/1); lower selectivity was observed with Fe(III) and Th(IV) loaded BPAP. The significance of the observed selectivity is discussed in terms of the chemical properties of the anion and the nature of the interactions with the immobilized metal site. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016362 Exemplaires
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Titre : Organic-inorganic hybrid membranes : solving the trade-off phenomenon between permeation flux and selectivity in pervaporation Type de document : texte imprimé Auteurs : Mahadevappa Y. Kariduraganavar, Auteur ; Jolly G. Varghese, Auteur ; Santosh K. Choudhari, Auteur Année de publication : 2009 Article en page(s) : pp. 4002–4013 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Organic− inorganic hybrid membranes Chitosan TiO2 Fourier transform infrared spectroscopy Scanning electron microscopy Thermogravimetric analysis Résumé : To solve the trade-off phenomenon existing between permeation flux and selectivity of membranes in pervaporation, organic−inorganic hybrid membranes composed of chitosan and TiO2 were prepared using a solution technique. The resulting hybrid membranes were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Compared to pure chitosan membrane, the hybrid membranes exhibited high thermal stability and low crystallinity. These membranes were tested for their ability to separate water−isopropanol mixtures by pervaporation in the temperature range of 30−50 °C. The experimental results demonstrated that both flux and selectivity increased simultaneously with increasing TiO2 content in the membrane. The permeation flux of pure chitosan membrane increased dramatically from 3.06 to 12.17 × 10−2 kg/(m2 h) when 40 mass % of TiO2 was incorporated, and correspondingly its separation factor increased from 509 to 94 984 at 30 °C for 5 mass % of water in the feed. The total flux and flux of water were found to be almost overlapping particularly for hybrid membranes, suggesting that these membranes could be used effectively to break the azeotropic point of water−isopropanol mixtures. From the temperature dependent diffusion and permeation values, the Arrhenius activation parameters were estimated. The activation energy values obtained for water permeation (Epw) were significantly lower than those of isopropanol permeation (EpIPA), suggesting that the developed membranes have higher separation efficiency for water−isopropanol systems. The negative heat of sorption (ΔHS) values were observed in all the membranes, indicating that Langmuir’s mode of sorption is predominant. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016626
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4002–4013[article] Organic-inorganic hybrid membranes : solving the trade-off phenomenon between permeation flux and selectivity in pervaporation [texte imprimé] / Mahadevappa Y. Kariduraganavar, Auteur ; Jolly G. Varghese, Auteur ; Santosh K. Choudhari, Auteur . - 2009 . - pp. 4002–4013.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4002–4013
Mots-clés : Organic− inorganic hybrid membranes Chitosan TiO2 Fourier transform infrared spectroscopy Scanning electron microscopy Thermogravimetric analysis Résumé : To solve the trade-off phenomenon existing between permeation flux and selectivity of membranes in pervaporation, organic−inorganic hybrid membranes composed of chitosan and TiO2 were prepared using a solution technique. The resulting hybrid membranes were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Compared to pure chitosan membrane, the hybrid membranes exhibited high thermal stability and low crystallinity. These membranes were tested for their ability to separate water−isopropanol mixtures by pervaporation in the temperature range of 30−50 °C. The experimental results demonstrated that both flux and selectivity increased simultaneously with increasing TiO2 content in the membrane. The permeation flux of pure chitosan membrane increased dramatically from 3.06 to 12.17 × 10−2 kg/(m2 h) when 40 mass % of TiO2 was incorporated, and correspondingly its separation factor increased from 509 to 94 984 at 30 °C for 5 mass % of water in the feed. The total flux and flux of water were found to be almost overlapping particularly for hybrid membranes, suggesting that these membranes could be used effectively to break the azeotropic point of water−isopropanol mixtures. From the temperature dependent diffusion and permeation values, the Arrhenius activation parameters were estimated. The activation energy values obtained for water permeation (Epw) were significantly lower than those of isopropanol permeation (EpIPA), suggesting that the developed membranes have higher separation efficiency for water−isopropanol systems. The negative heat of sorption (ΔHS) values were observed in all the membranes, indicating that Langmuir’s mode of sorption is predominant. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016626 Exemplaires
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Titre : Germanium(IV) adsorption from aqueous solution using a kelex-100 functional adsorbent Type de document : texte imprimé Auteurs : Hyung-Jun Park, Auteur ; Lawrence L. Tavlarides, Auteur Année de publication : 2009 Article en page(s) : pp. 4014–4021 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Germanium Acid solution systems Kelex-100 Sol− gel adsorbent Aqueous Résumé : The removal of germanium from acid solution systems using a Kelex-100 [7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline] functional sol−gel adsorbent was investigated. Kelex-100 has been used for separating metals such as Ga(III), Co(II), Cd(II), Pb(II), and Cu(II) from aqueous solution by solvent extraction and liquid membranes. The goal of this work was to demonstrate that elutable mesoporous organo-ceramic adsorbents based on Kelex-100 can be synthesized for the selective separation of germanium from simulated leachate solution. The speciation diagram of Ge(IV) in an aqueous system with varying pH was prepared and evaluated by analysis of the equilibrium equations. The Langmuir adsorption isotherm was found to provide a satisfactory fit of the adsorption data, and the uptake capacity at pH 6.0 was found to be 0.33 mmol/g (23 mg/g). A kinetics study conducted on a germanium(IV) solution in a batch reactor at different pH values showed a high rate of adsorption relative to other adsorbents [Inukai et al. Anal. Sci.2001, 1, 1117−1120; Marco et al. Carbon2007, 45 (13), 2519−2528; Pokrovsky et al. Geochim. Cosmochim. Acta2006, 70, 3325−3341]. The adsorbent exhibited a high selectivity toward Ge(IV) and negligible adsorption of As(II), Sb(II), Ni(II), and Zn(II). Adsorption tests in a fixed-bed column showed a sharp breakthrough curve. Stripping of the germanium-loaded column bed was achieved using 1 M HCl. Eleven cycles of the adsorption and desorption process were performed with this Kelex-100 functional adsorbent, named SOL-KELEX. The adsorbent maintained 70% of its original capacity through six cycles and lost 50% of its capacity through 11 cycles of operation. The Kelex-100 functional adsorbent was found to be an effective sorbent material for the separation of germanium(IV) from aqueous solutions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801733d
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4014–4021[article] Germanium(IV) adsorption from aqueous solution using a kelex-100 functional adsorbent [texte imprimé] / Hyung-Jun Park, Auteur ; Lawrence L. Tavlarides, Auteur . - 2009 . - pp. 4014–4021.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4014–4021
Mots-clés : Germanium Acid solution systems Kelex-100 Sol− gel adsorbent Aqueous Résumé : The removal of germanium from acid solution systems using a Kelex-100 [7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline] functional sol−gel adsorbent was investigated. Kelex-100 has been used for separating metals such as Ga(III), Co(II), Cd(II), Pb(II), and Cu(II) from aqueous solution by solvent extraction and liquid membranes. The goal of this work was to demonstrate that elutable mesoporous organo-ceramic adsorbents based on Kelex-100 can be synthesized for the selective separation of germanium from simulated leachate solution. The speciation diagram of Ge(IV) in an aqueous system with varying pH was prepared and evaluated by analysis of the equilibrium equations. The Langmuir adsorption isotherm was found to provide a satisfactory fit of the adsorption data, and the uptake capacity at pH 6.0 was found to be 0.33 mmol/g (23 mg/g). A kinetics study conducted on a germanium(IV) solution in a batch reactor at different pH values showed a high rate of adsorption relative to other adsorbents [Inukai et al. Anal. Sci.2001, 1, 1117−1120; Marco et al. Carbon2007, 45 (13), 2519−2528; Pokrovsky et al. Geochim. Cosmochim. Acta2006, 70, 3325−3341]. The adsorbent exhibited a high selectivity toward Ge(IV) and negligible adsorption of As(II), Sb(II), Ni(II), and Zn(II). Adsorption tests in a fixed-bed column showed a sharp breakthrough curve. Stripping of the germanium-loaded column bed was achieved using 1 M HCl. Eleven cycles of the adsorption and desorption process were performed with this Kelex-100 functional adsorbent, named SOL-KELEX. The adsorbent maintained 70% of its original capacity through six cycles and lost 50% of its capacity through 11 cycles of operation. The Kelex-100 functional adsorbent was found to be an effective sorbent material for the separation of germanium(IV) from aqueous solutions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801733d Exemplaires
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Titre : Effect of ammonia on the absorption kinetics of carbon dioxide into aqueous 2-amino-2-methyl-1-propanol solutions Type de document : texte imprimé Auteurs : Won-Joon Choi, Auteur ; Byoung-Moo Min, Auteur ; Jong-Beom Seo, Auteur Année de publication : 2009 Article en page(s) : pp. 4022–4029 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Aqueous 2-amino-2-methyl-1-propanol Carbon dioxide Absorption rates Stirred-cell reactor Résumé : Reaction rate constants of aqueous 2-amino-2-methyl-1-propanol (AMP)/ammonia (NH3) solutions with carbon dioxide (CO2) were determined by measuring their absorption rates. The CO2 absorption characteristics of an NH3 solution added to AMP were investigated using a stirred-cell reactor. The CO2 absorption rates into aqueous blended amine solutions were measured at different pressures (pA = 5, 10, and 15 kPa) and temperatures (293, 303, 313, and 323 K). Additive concentrations of 1, 3, and 5 wt % NH3 were added for each 30 wt % AMP solution. The results showed that the addition of NH3 to AMP significantly increased the CO2 absorption rates of AMP by 144%. In addition, the reaction rate constant for a blend of AMP and NH3 with CO2 as a function of temperature was 1.6- to 2.4-fold higher than that of AMP without NH3. The reaction rate constants were k2,AMP = 1.543 × 107 exp(−3019.92/T) and k2,NH3 = 1.847 × 1010 exp(−4954.25/T). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018438
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4022–4029[article] Effect of ammonia on the absorption kinetics of carbon dioxide into aqueous 2-amino-2-methyl-1-propanol solutions [texte imprimé] / Won-Joon Choi, Auteur ; Byoung-Moo Min, Auteur ; Jong-Beom Seo, Auteur . - 2009 . - pp. 4022–4029.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4022–4029
Mots-clés : Aqueous 2-amino-2-methyl-1-propanol Carbon dioxide Absorption rates Stirred-cell reactor Résumé : Reaction rate constants of aqueous 2-amino-2-methyl-1-propanol (AMP)/ammonia (NH3) solutions with carbon dioxide (CO2) were determined by measuring their absorption rates. The CO2 absorption characteristics of an NH3 solution added to AMP were investigated using a stirred-cell reactor. The CO2 absorption rates into aqueous blended amine solutions were measured at different pressures (pA = 5, 10, and 15 kPa) and temperatures (293, 303, 313, and 323 K). Additive concentrations of 1, 3, and 5 wt % NH3 were added for each 30 wt % AMP solution. The results showed that the addition of NH3 to AMP significantly increased the CO2 absorption rates of AMP by 144%. In addition, the reaction rate constant for a blend of AMP and NH3 with CO2 as a function of temperature was 1.6- to 2.4-fold higher than that of AMP without NH3. The reaction rate constants were k2,AMP = 1.543 × 107 exp(−3019.92/T) and k2,NH3 = 1.847 × 1010 exp(−4954.25/T). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018438 Exemplaires
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Titre : Effect of H2S on the performance and long-term stability of Pd/Cu membranes Type de document : texte imprimé Auteurs : Natalie Pomerantz, Auteur ; Yi Hua Ma, Auteur Année de publication : 2009 Article en page(s) : pp. 4030–4039 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pd/Cu alloy top layer Palladium membranes H2S Electroless deposition method Résumé : The objective of this work was to fabricate palladium membranes with a Pd/Cu alloy top layer and to investigate the performance and long-term stability of the membranes in small concentrations of H2S. The Pd/Cu alloy membranes with compositions of 8, 18, and 19 wt % copper were fabricated using the electroless deposition method on porous Inconel supports and characterized for several thousand hours in H2, helium, and 45−55 ppm H2S/H2 mixtures in the temperature range of 350−500 °C. Upon exposure to the H2S/H2 mixture at 500 °C, the Pd/Cu membranes lost ∼80% of the hydrogen permeance, because of the H2S forming surface sulfides and blocking H2 adsorption sites, with the amount of permeance lost increasing with decreasing temperature. Reintroducing pure H2 recovered some of the hydrogen permeance, showing that some of the H2S poisoning was irreversible. The amount of irreversible poisoning increased as the H2S exposure time increased and the exposure temperature decreased, because of the exothermic nature of H2S adsorption. The helium leak rate of the Pd/Cu membranes decreased after the poisoning experiments, possibly because of sulfur that segregated to the grain boundaries of the Pd/Cu deposits. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801947a
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4030–4039[article] Effect of H2S on the performance and long-term stability of Pd/Cu membranes [texte imprimé] / Natalie Pomerantz, Auteur ; Yi Hua Ma, Auteur . - 2009 . - pp. 4030–4039.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4030–4039
Mots-clés : Pd/Cu alloy top layer Palladium membranes H2S Electroless deposition method Résumé : The objective of this work was to fabricate palladium membranes with a Pd/Cu alloy top layer and to investigate the performance and long-term stability of the membranes in small concentrations of H2S. The Pd/Cu alloy membranes with compositions of 8, 18, and 19 wt % copper were fabricated using the electroless deposition method on porous Inconel supports and characterized for several thousand hours in H2, helium, and 45−55 ppm H2S/H2 mixtures in the temperature range of 350−500 °C. Upon exposure to the H2S/H2 mixture at 500 °C, the Pd/Cu membranes lost ∼80% of the hydrogen permeance, because of the H2S forming surface sulfides and blocking H2 adsorption sites, with the amount of permeance lost increasing with decreasing temperature. Reintroducing pure H2 recovered some of the hydrogen permeance, showing that some of the H2S poisoning was irreversible. The amount of irreversible poisoning increased as the H2S exposure time increased and the exposure temperature decreased, because of the exothermic nature of H2S adsorption. The helium leak rate of the Pd/Cu membranes decreased after the poisoning experiments, possibly because of sulfur that segregated to the grain boundaries of the Pd/Cu deposits. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801947a Exemplaires
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Titre : Experimental study of shell-side heat transfer coefficient and pressure drop for an integrally helical baffled heat exchanger combined with different enhanced tubes Type de document : texte imprimé Auteurs : Zhengguo Zhang, Auteur ; Changshun Wu, Auteur ; Xiaoming Fang, Auteur Année de publication : 2009 Article en page(s) : pp. 4040–4044 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Shell-side heat transfer coefficient Pressure drop Helical baffle exchanger Enhanced tubes Résumé : Experiments were performed to compare the shell-side heat transfer coefficient and pressure drop of an integrally helical baffle heat exchanger with rib-shaped fin tubes to those of that with low-fin tubes for oil cooling using water as a coolant. The experimental results showed that for the heat exchanger with rib-shaped fin tubes, the shell-side Nusselt and Euler numbers were augmented by 90−130% and 10%, respectively. The increase in heat transfer is significantly greater than that in pressure drop for rib-shaped fin tubes. Correlations have been suggested for both the shell-side Nusselt and Euler numbers for the two heat exchangers with different tube types and give very good agreement with experimental results. It is a promising route to use rib-shaped fin tubes instead of low-fin tubes for improving the performance of an integrally helical baffle heat exchanger. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801339s
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4040–4044[article] Experimental study of shell-side heat transfer coefficient and pressure drop for an integrally helical baffled heat exchanger combined with different enhanced tubes [texte imprimé] / Zhengguo Zhang, Auteur ; Changshun Wu, Auteur ; Xiaoming Fang, Auteur . - 2009 . - pp. 4040–4044.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4040–4044
Mots-clés : Shell-side heat transfer coefficient Pressure drop Helical baffle exchanger Enhanced tubes Résumé : Experiments were performed to compare the shell-side heat transfer coefficient and pressure drop of an integrally helical baffle heat exchanger with rib-shaped fin tubes to those of that with low-fin tubes for oil cooling using water as a coolant. The experimental results showed that for the heat exchanger with rib-shaped fin tubes, the shell-side Nusselt and Euler numbers were augmented by 90−130% and 10%, respectively. The increase in heat transfer is significantly greater than that in pressure drop for rib-shaped fin tubes. Correlations have been suggested for both the shell-side Nusselt and Euler numbers for the two heat exchangers with different tube types and give very good agreement with experimental results. It is a promising route to use rib-shaped fin tubes instead of low-fin tubes for improving the performance of an integrally helical baffle heat exchanger. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801339s Exemplaires
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Titre : Measurements of hydrate dissociation temperature of methane, ethane, and CO2 in the absence of any aqueous phase and prediction with the cubic plus association equation of state Type de document : texte imprimé Auteurs : Z. Youssef, Auteur ; A. Barreau, Auteur ; P. Mougin, Auteur Année de publication : 2009 Article en page(s) : pp. 4045–4050 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas hydrate formation Equilibrium cell Water measurement Karl Fischer coulometer Résumé : Gas hydrate formation is undesired in processing and gas distribution. Therefore, it is important to have a thermodynamic model that predicts correctly gas hydrate formation. Hydrate formation is very well studied in the literature in the presence of liquid water, and hydrate thermodynamic models predict correctly its formation. However, only very little information can be found concerning gas hydrate formation without an aqueous phase. A new experimental procedure combining an equilibrium cell with a water measurement by a Karl Fischer coulometer was developed. The water content of the vapor phase is measured as a function of the temperature, and the hydrate dissociation temperature is determined by the slope change of the curve. In the first step, the dissociation temperatures of methane hydrate, ethane hydrate, and carbon dioxide hydrate were determined at different pressures and for different water amounts. In the second step, the obtained results were compared with the literature data and with the calculated values using the classical Platteeuw and van der Waals model associated with the Soave−Redlich−Kwong and the cubic plus association equations of state to calculate the water fugacity in the vapor phase. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801351e
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4045–4050[article] Measurements of hydrate dissociation temperature of methane, ethane, and CO2 in the absence of any aqueous phase and prediction with the cubic plus association equation of state [texte imprimé] / Z. Youssef, Auteur ; A. Barreau, Auteur ; P. Mougin, Auteur . - 2009 . - pp. 4045–4050.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4045–4050
Mots-clés : Gas hydrate formation Equilibrium cell Water measurement Karl Fischer coulometer Résumé : Gas hydrate formation is undesired in processing and gas distribution. Therefore, it is important to have a thermodynamic model that predicts correctly gas hydrate formation. Hydrate formation is very well studied in the literature in the presence of liquid water, and hydrate thermodynamic models predict correctly its formation. However, only very little information can be found concerning gas hydrate formation without an aqueous phase. A new experimental procedure combining an equilibrium cell with a water measurement by a Karl Fischer coulometer was developed. The water content of the vapor phase is measured as a function of the temperature, and the hydrate dissociation temperature is determined by the slope change of the curve. In the first step, the dissociation temperatures of methane hydrate, ethane hydrate, and carbon dioxide hydrate were determined at different pressures and for different water amounts. In the second step, the obtained results were compared with the literature data and with the calculated values using the classical Platteeuw and van der Waals model associated with the Soave−Redlich−Kwong and the cubic plus association equations of state to calculate the water fugacity in the vapor phase. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801351e Exemplaires
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Titre : Solubility of carbon dioxide and hydrogen sulfide in aqueous n-methyldiethanolamine solutions Type de document : texte imprimé Auteurs : P. J. G. Huttenhuis, Auteur ; N. J. Agrawal, Auteur ; G. F. Versteeg, Auteur Année de publication : 2009 Article en page(s) : pp. 4051–4059 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : H2S CO2 Aqueous N-methyldiethanol amine solutions Methane pressures Electrolyte equation of state Résumé : In this work, 72 new experimental solubility data points for H2S and CO2 mixtures in aqueous N-methyldiethanol amine (MDEA) solutions at different methane partial pressures (up to 69 bara) are presented. They are correlated using an electrolyte equation of state (E-EOS) thermodynamic model. This model has already been used to estimate the CO2 solubility in aqueous MDEA (Huttenhuis et al. Fluid Phase Equilib. 2008, 264, 99−112) and the H2S solubility in aqueous MDEA (Huttenhuis et al. Int. J. Oil, Gas Coal Technol. 2008, 1, 399−424). Here, the model is further extended to predict the behavior of CO2 and H2S when they are present simultaneously in aqueous MDEA. The application of an equation of state is a new development for this type of system, i.e., of acid-gas−amine systems. The molecular interactions are described by Schwarzentruber et al.’s modification of the Redlich−Kwong−Soave equation of state, with terms added to account for ionic interactions in the liquid phase. The model is used to describe acid-gas solubility data for the CO2−H2S−MDEA−H2O system reported in the open literature and experimental data reported here for the CO2−H2S−MDEA−H2O−CH4 system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801336j
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4051–4059[article] Solubility of carbon dioxide and hydrogen sulfide in aqueous n-methyldiethanolamine solutions [texte imprimé] / P. J. G. Huttenhuis, Auteur ; N. J. Agrawal, Auteur ; G. F. Versteeg, Auteur . - 2009 . - pp. 4051–4059.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4051–4059
Mots-clés : H2S CO2 Aqueous N-methyldiethanol amine solutions Methane pressures Electrolyte equation of state Résumé : In this work, 72 new experimental solubility data points for H2S and CO2 mixtures in aqueous N-methyldiethanol amine (MDEA) solutions at different methane partial pressures (up to 69 bara) are presented. They are correlated using an electrolyte equation of state (E-EOS) thermodynamic model. This model has already been used to estimate the CO2 solubility in aqueous MDEA (Huttenhuis et al. Fluid Phase Equilib. 2008, 264, 99−112) and the H2S solubility in aqueous MDEA (Huttenhuis et al. Int. J. Oil, Gas Coal Technol. 2008, 1, 399−424). Here, the model is further extended to predict the behavior of CO2 and H2S when they are present simultaneously in aqueous MDEA. The application of an equation of state is a new development for this type of system, i.e., of acid-gas−amine systems. The molecular interactions are described by Schwarzentruber et al.’s modification of the Redlich−Kwong−Soave equation of state, with terms added to account for ionic interactions in the liquid phase. The model is used to describe acid-gas solubility data for the CO2−H2S−MDEA−H2O system reported in the open literature and experimental data reported here for the CO2−H2S−MDEA−H2O−CH4 system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801336j Exemplaires
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Titre : A coupled DEM and CFD simulation of flow field and pressure drop in fixed bed reactor with randomly packed catalyst particles Type de document : texte imprimé Auteurs : Hua Bai, Auteur ; Jörg Theuerkauf, Auteur ; Paul A. Gillis, Auteur Année de publication : 2009 Article en page(s) : pp. 4060–4074 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Discrete element method Computational fluid dynamics Fixed bed reactor Random packing structure Résumé : Packed bed unit operations are required for many commercial chemical processes. The ability to a priori predict void fraction and pressure drop in a packed bed would significantly improve reactor design as well as allow for optimization around catalyst performance, catalyst design, and the resulting process pressure drop. Traditionally, the packed bed reactor designs are based on a homogeneous model with averaged empirical correlations. These correlations are often inapplicable for low tube-to-particle diameter ratios (D/d En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801548h
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4060–4074[article] A coupled DEM and CFD simulation of flow field and pressure drop in fixed bed reactor with randomly packed catalyst particles [texte imprimé] / Hua Bai, Auteur ; Jörg Theuerkauf, Auteur ; Paul A. Gillis, Auteur . - 2009 . - pp. 4060–4074.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4060–4074
Mots-clés : Discrete element method Computational fluid dynamics Fixed bed reactor Random packing structure Résumé : Packed bed unit operations are required for many commercial chemical processes. The ability to a priori predict void fraction and pressure drop in a packed bed would significantly improve reactor design as well as allow for optimization around catalyst performance, catalyst design, and the resulting process pressure drop. Traditionally, the packed bed reactor designs are based on a homogeneous model with averaged empirical correlations. These correlations are often inapplicable for low tube-to-particle diameter ratios (D/d En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801548h Exemplaires
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Titre : Mass transfer and solubility of CO and H2 in ionic liquid. Case of [Bmim][PF6] with gas-inducing stirrer reactor Type de document : texte imprimé Auteurs : Amit Sharma, Auteur ; Carine Julcour, Auteur ; Ashutosh A. Kelkar, Auteur Année de publication : 2009 Article en page(s) : pp. 4075–4082 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ionic liquids Solubility Gas− liquid mass transfer Carbon monoxide Hydrogen Résumé : Since the past decade, ionic liquids have gained significant importance as alternative solvents for catalysis applications. Many of the reactions evaluated in ionic liquids employ gases as substrates, and therefore it is important to know their solubility and mass transfer characteristics. This work reports for the first time both the solubility and volumetric gas−liquid mass transfer coefficient kLa for hydrogen and carbon monoxide in 1-n-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) at three temperatures (293, 323, and 373 K) in relevance to hydroformylation reaction. The experimental data on the volumetric gas−liquid mass transfer coefficient are described by a dimensionless correlation for the bench-scale stirred tanks with gas-inducing impeller. kLa values have also been evaluated for different [Bmim][PF6]−decane emulsions at 373 K. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801584p
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4075–4082[article] Mass transfer and solubility of CO and H2 in ionic liquid. Case of [Bmim][PF6] with gas-inducing stirrer reactor [texte imprimé] / Amit Sharma, Auteur ; Carine Julcour, Auteur ; Ashutosh A. Kelkar, Auteur . - 2009 . - pp. 4075–4082.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4075–4082
Mots-clés : Ionic liquids Solubility Gas− liquid mass transfer Carbon monoxide Hydrogen Résumé : Since the past decade, ionic liquids have gained significant importance as alternative solvents for catalysis applications. Many of the reactions evaluated in ionic liquids employ gases as substrates, and therefore it is important to know their solubility and mass transfer characteristics. This work reports for the first time both the solubility and volumetric gas−liquid mass transfer coefficient kLa for hydrogen and carbon monoxide in 1-n-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) at three temperatures (293, 323, and 373 K) in relevance to hydroformylation reaction. The experimental data on the volumetric gas−liquid mass transfer coefficient are described by a dimensionless correlation for the bench-scale stirred tanks with gas-inducing impeller. kLa values have also been evaluated for different [Bmim][PF6]−decane emulsions at 373 K. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801584p Exemplaires
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Titre : Fire extinction using carbon dioxide hydrate Type de document : texte imprimé Auteurs : Takashi Hatakeyama, Auteur ; Eisuke Aida, Auteur ; Takeshi Yokomori, Auteur Année de publication : 2009 Article en page(s) : pp. 4083–4087 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fire extinguishing Hydrate crystals Carbon dioxide Résumé : Clathrate hydrates formed with nonflammable gases may be suitable for use as fire extinguishing agents because the dissociation of the hydrates decreases the temperature in the flame base and the nonflammable gases released from the dissociated hydrates prevent the supply of oxygen to the flame base. In the present study, we performed experiments to extinguish pool flames using the hydrate crystals formed with carbon dioxide. From the experimental result, the critical mass of CO2 hydrate to extinguish the flame was found to increase when the size of the pool flame is increased. The critical mass to extinguish the same size flame of ordinary ice and dry ice was also measured. These results showed that the CO2 hydrate can extinguish the pool flame with less water as compared to ordinary ice and less releasing of the CO2 as compared to the dry ice. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019533
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4083–4087[article] Fire extinction using carbon dioxide hydrate [texte imprimé] / Takashi Hatakeyama, Auteur ; Eisuke Aida, Auteur ; Takeshi Yokomori, Auteur . - 2009 . - pp. 4083–4087.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4083–4087
Mots-clés : Fire extinguishing Hydrate crystals Carbon dioxide Résumé : Clathrate hydrates formed with nonflammable gases may be suitable for use as fire extinguishing agents because the dissociation of the hydrates decreases the temperature in the flame base and the nonflammable gases released from the dissociated hydrates prevent the supply of oxygen to the flame base. In the present study, we performed experiments to extinguish pool flames using the hydrate crystals formed with carbon dioxide. From the experimental result, the critical mass of CO2 hydrate to extinguish the flame was found to increase when the size of the pool flame is increased. The critical mass to extinguish the same size flame of ordinary ice and dry ice was also measured. These results showed that the CO2 hydrate can extinguish the pool flame with less water as compared to ordinary ice and less releasing of the CO2 as compared to the dry ice. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019533 Exemplaires
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Titre : A model to predict the concentration of dispersed solid particles in an aqueous medium confined inside horizontal cylindrical channels Type de document : texte imprimé Auteurs : Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur Année de publication : 2009 Article en page(s) : pp. 4088–4093 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cylindrical channels Solid particles Two-dimensional convective-dispersive model Résumé : The deposition of solid particles in cylindrical channels has received considerable attention, because of its direct application in industry. However, an adequate mathematical expression that studies the separation and suspension of dispersed particles present in horizontal cylindrical channels is still missing. In this paper, we developed and solved a time-dependent, two-dimensional convective-dispersive model that simulates the deposition and suspension of dispersed particles immersed in a fluid medium inside the cross section of a horizontal cylindrical channel in a stagnant situation. The results of the modeling are compared with a series of experiments that permit one to know the concentration of the particles in different points in the cross section of a horizontal cylinder. These experiments were performed using particles in the micrometer range dispersed in an aqueous medium. The conditions that permit to control the suspension and deposition of the particles inside a liquid medium with cylindrical geometry are unveiled by the presented model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801518p
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4088–4093[article] A model to predict the concentration of dispersed solid particles in an aqueous medium confined inside horizontal cylindrical channels [texte imprimé] / Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur . - 2009 . - pp. 4088–4093.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4088–4093
Mots-clés : Cylindrical channels Solid particles Two-dimensional convective-dispersive model Résumé : The deposition of solid particles in cylindrical channels has received considerable attention, because of its direct application in industry. However, an adequate mathematical expression that studies the separation and suspension of dispersed particles present in horizontal cylindrical channels is still missing. In this paper, we developed and solved a time-dependent, two-dimensional convective-dispersive model that simulates the deposition and suspension of dispersed particles immersed in a fluid medium inside the cross section of a horizontal cylindrical channel in a stagnant situation. The results of the modeling are compared with a series of experiments that permit one to know the concentration of the particles in different points in the cross section of a horizontal cylinder. These experiments were performed using particles in the micrometer range dispersed in an aqueous medium. The conditions that permit to control the suspension and deposition of the particles inside a liquid medium with cylindrical geometry are unveiled by the presented model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801518p Exemplaires
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Titre : A model to predict the concentration of submicrometer solid particles in viscous media confined inside horizontal cylindrical channels Type de document : texte imprimé Auteurs : Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur Année de publication : 2009 Article en page(s) : pp. 4094–4100 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ultradispersed particles Cylindrical channel Viscosity Dispersion coefficient Résumé : As light oil reserves dwindle, the extraction and processing of heavy crude oils are becoming increasingly important. The use of ultradispersed catalysts (nanometric catalytic particles dispersed in the oil) is considered to be a promising way to upgrade these materials. To simulate such processes, mass transfer of the ultradispersed particles must be estimated. However, an adequate mathematical expression to describe the motion of these particles through viscous media in a horizontal cylindrical channel is still missing. In this paper, we developed and solved a time-dependent, two-dimensional convective−dispersive model, which simulates the transient deposition and suspension of ultradispersed particles immersed in a viscous medium, inside the cross section of a horizontal cylindrical channel in a stagnant situation. The results of the modeling are compared with a series of experiments that permit knowledge of the concentration of the ultradispersed particles inside a horizontal cylinder. These experiments were performed using particles in the submicrometer range (average sizes of 198 nm) and fluid media with diverse densities and viscosities. The effect of the fluid medium properties and the initial particle concentration in the calculation of the dispersion coefficient was also studied. The conditions needed to maintain the solid particles suspended in the liquid medium, contained in a vessel with cylindrical geometry, are also unveiled by the presented model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801519e
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4094–4100[article] A model to predict the concentration of submicrometer solid particles in viscous media confined inside horizontal cylindrical channels [texte imprimé] / Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur . - 2009 . - pp. 4094–4100.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4094–4100
Mots-clés : Ultradispersed particles Cylindrical channel Viscosity Dispersion coefficient Résumé : As light oil reserves dwindle, the extraction and processing of heavy crude oils are becoming increasingly important. The use of ultradispersed catalysts (nanometric catalytic particles dispersed in the oil) is considered to be a promising way to upgrade these materials. To simulate such processes, mass transfer of the ultradispersed particles must be estimated. However, an adequate mathematical expression to describe the motion of these particles through viscous media in a horizontal cylindrical channel is still missing. In this paper, we developed and solved a time-dependent, two-dimensional convective−dispersive model, which simulates the transient deposition and suspension of ultradispersed particles immersed in a viscous medium, inside the cross section of a horizontal cylindrical channel in a stagnant situation. The results of the modeling are compared with a series of experiments that permit knowledge of the concentration of the ultradispersed particles inside a horizontal cylinder. These experiments were performed using particles in the submicrometer range (average sizes of 198 nm) and fluid media with diverse densities and viscosities. The effect of the fluid medium properties and the initial particle concentration in the calculation of the dispersion coefficient was also studied. The conditions needed to maintain the solid particles suspended in the liquid medium, contained in a vessel with cylindrical geometry, are also unveiled by the presented model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801519e Exemplaires
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Titre : Study on systems based on coal and natural gas for producing dimethyl ether Type de document : texte imprimé Auteurs : Li Zhou, Auteur ; Shanying Hu, Auteur ; Dingjiang Chen, Auteur Année de publication : 2009 Article en page(s) : pp. 4101–4108 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Dimethyl ether Coal Recycling ratios Résumé : China is a coal-dependent country and will remain so for a long time. Dimethyl ether (DME), a potential substitute for liquid fuel, is a kind of clean diesel motor fuel. The production of DME from coal is meaningful and is studied in this article. Considering the C/H ratios of coal and natural gas (NG), the cofeed (coal and NG) system (CFS), which does not contain the water gas shift process, is studied. It can reduce CO2 emission and increase the conversion rate of carbon, producing more DME. The CFS is simulated and compared with the coal-based and NG-based systems with different recycling ratios. The part of the exhaust gas that is not recycled is burned, producing electricity. On the basis of the simulation results, the thermal efficiency, economic index, and CO2 emission ratio are calculated separately. The CFS with a 100% recycling ratio has the best comprehensive evaluation index, while the energy, economy, and environment were considered at the same time. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8006177
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4101–4108[article] Study on systems based on coal and natural gas for producing dimethyl ether [texte imprimé] / Li Zhou, Auteur ; Shanying Hu, Auteur ; Dingjiang Chen, Auteur . - 2009 . - pp. 4101–4108.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4101–4108
Mots-clés : Dimethyl ether Coal Recycling ratios Résumé : China is a coal-dependent country and will remain so for a long time. Dimethyl ether (DME), a potential substitute for liquid fuel, is a kind of clean diesel motor fuel. The production of DME from coal is meaningful and is studied in this article. Considering the C/H ratios of coal and natural gas (NG), the cofeed (coal and NG) system (CFS), which does not contain the water gas shift process, is studied. It can reduce CO2 emission and increase the conversion rate of carbon, producing more DME. The CFS is simulated and compared with the coal-based and NG-based systems with different recycling ratios. The part of the exhaust gas that is not recycled is burned, producing electricity. On the basis of the simulation results, the thermal efficiency, economic index, and CO2 emission ratio are calculated separately. The CFS with a 100% recycling ratio has the best comprehensive evaluation index, while the energy, economy, and environment were considered at the same time. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8006177 Exemplaires
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Titre : Modeling of aqueous biomolecules using a new free-volume group contribution model Type de document : texte imprimé Auteurs : G. R. Pazuki, Auteur ; V. Taghikhani, Auteur ; M. Vossoughi, Auteur Année de publication : 2009 Article en page(s) : pp. 4109–4118 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Biomolecules Aqueous solutions FV model Résumé : In this article, a new group contribution model is suggested for obtaining the thermodynamic properties of biomolecules in aqueous solutions. Accordingly, a Freed-FV model has been applied for the combinatorial free-volume term. The activity coefficients, solubilities, densities, and vapor pressures of amino acids and simple peptides in aqueous solutions were correlated, using the proposed group contribution model. Group interaction parameters of the proposed model were obtained by use of experimental data from amino acids available in the literature. The results demonstrate that the group contribution model can accurately correlate activity coefficient, solubility, density, and vapor pressure data for aqueous amino acid and peptide solutions. Furthermore, the osmotic pressures of aqueous solutions containing lysozyme and ammonium sulfate were calculated at ionic strengths of 1 and 3 M and pH values of 4, 6, and 8. The results obtained from the suggested model were compared with those obtained from the virial osmotic model. Also, the model was coupled with the Debye−Hückel model to correlate partition coefficients of biomolecules in polymer−salt aqueous two-phase systems. The results showed that the new group contribution model can accurately correlate partition coefficients of biomolecules in polymer−salt aqueous two-phase systems. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8009389
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4109–4118[article] Modeling of aqueous biomolecules using a new free-volume group contribution model [texte imprimé] / G. R. Pazuki, Auteur ; V. Taghikhani, Auteur ; M. Vossoughi, Auteur . - 2009 . - pp. 4109–4118.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4109–4118
Mots-clés : Biomolecules Aqueous solutions FV model Résumé : In this article, a new group contribution model is suggested for obtaining the thermodynamic properties of biomolecules in aqueous solutions. Accordingly, a Freed-FV model has been applied for the combinatorial free-volume term. The activity coefficients, solubilities, densities, and vapor pressures of amino acids and simple peptides in aqueous solutions were correlated, using the proposed group contribution model. Group interaction parameters of the proposed model were obtained by use of experimental data from amino acids available in the literature. The results demonstrate that the group contribution model can accurately correlate activity coefficient, solubility, density, and vapor pressure data for aqueous amino acid and peptide solutions. Furthermore, the osmotic pressures of aqueous solutions containing lysozyme and ammonium sulfate were calculated at ionic strengths of 1 and 3 M and pH values of 4, 6, and 8. The results obtained from the suggested model were compared with those obtained from the virial osmotic model. Also, the model was coupled with the Debye−Hückel model to correlate partition coefficients of biomolecules in polymer−salt aqueous two-phase systems. The results showed that the new group contribution model can accurately correlate partition coefficients of biomolecules in polymer−salt aqueous two-phase systems. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8009389 Exemplaires
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Titre : Unsteady state heat transfer from cylinders to air in normal and parallel flow Type de document : texte imprimé Auteurs : Vishnu T. Marla, Auteur ; Robert L. Shambaugh, Auteur ; Dimitrios V. Papavassiliou, Auteur Année de publication : 2009 Article en page(s) : pp. 4119–4126 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Air flow Cylinders Nusselt number Résumé : Transient temperature measurements were made to determine the Nusselt number for both normal and parallel air flow over cylinders. The cylinders were fine polymer fibers, and the temperatures were determined with an infrared camera. The experimental results for normal flow agree with the well-established correlation of McAdams. For parallel flow, the results lie between the predictions of previous researchers. Unlike the work described herein, previous investigators used equilibrium conditions as a basis for determining Nusselt numbers. Our transient measurements showed that the Nusselt number is not strongly dependent on the transient character of temperature difference. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800946a
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4119–4126[article] Unsteady state heat transfer from cylinders to air in normal and parallel flow [texte imprimé] / Vishnu T. Marla, Auteur ; Robert L. Shambaugh, Auteur ; Dimitrios V. Papavassiliou, Auteur . - 2009 . - pp. 4119–4126.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4119–4126
Mots-clés : Air flow Cylinders Nusselt number Résumé : Transient temperature measurements were made to determine the Nusselt number for both normal and parallel air flow over cylinders. The cylinders were fine polymer fibers, and the temperatures were determined with an infrared camera. The experimental results for normal flow agree with the well-established correlation of McAdams. For parallel flow, the results lie between the predictions of previous researchers. Unlike the work described herein, previous investigators used equilibrium conditions as a basis for determining Nusselt numbers. Our transient measurements showed that the Nusselt number is not strongly dependent on the transient character of temperature difference. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800946a Exemplaires
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Titre : Compositional polydispersity in linear low density polyethylene Type de document : texte imprimé Auteurs : Aleksandra Dominik, Auteur ; Walter G. Chapman, Auteur ; Robert D. Swindoll, Auteur Année de publication : 2009 Article en page(s) : pp. 4127–4135 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Linear low density polyethylene Short-chain branching distribution polymers Résumé : A study of the effect of a short-chain branching distribution (SCBD) on the phase behavior of linear low density polyethylene (LLDPE) was conducted. The perturbed chain-SAFT equation of state was the underlying thermodynamic model chosen for the study; the branched polyolefins were described using a simple modeling concept previously proposed by Dominik and Chapman.(1) To isolate the effect of the SCBD on phase behavior, the copolymer systems were considered monodisperse in molecular weight. The study revealed that, in the case of low to moderate values of the polydispersity index of the SCBD, the compositional polydispersity affected the phase behavior at low polymer concentrations only. When the polydispersity index of the SCBD is high, or, in other words, when the difference in branch content between the components of the distribution is significant, additional phases appear. The formation of multiple phases results from the incompatibility of branched and linear polymers. Similar observations were made on the basis of experimental studies in the case of polymer blends. The SCBD of LLDPE was determined by the chemistry of the polymerization reaction. A broad SCBD was found to significantly affect the phase behavior of LLDPE solutions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800982z
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4127–4135[article] Compositional polydispersity in linear low density polyethylene [texte imprimé] / Aleksandra Dominik, Auteur ; Walter G. Chapman, Auteur ; Robert D. Swindoll, Auteur . - 2009 . - pp. 4127–4135.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4127–4135
Mots-clés : Linear low density polyethylene Short-chain branching distribution polymers Résumé : A study of the effect of a short-chain branching distribution (SCBD) on the phase behavior of linear low density polyethylene (LLDPE) was conducted. The perturbed chain-SAFT equation of state was the underlying thermodynamic model chosen for the study; the branched polyolefins were described using a simple modeling concept previously proposed by Dominik and Chapman.(1) To isolate the effect of the SCBD on phase behavior, the copolymer systems were considered monodisperse in molecular weight. The study revealed that, in the case of low to moderate values of the polydispersity index of the SCBD, the compositional polydispersity affected the phase behavior at low polymer concentrations only. When the polydispersity index of the SCBD is high, or, in other words, when the difference in branch content between the components of the distribution is significant, additional phases appear. The formation of multiple phases results from the incompatibility of branched and linear polymers. Similar observations were made on the basis of experimental studies in the case of polymer blends. The SCBD of LLDPE was determined by the chemistry of the polymerization reaction. A broad SCBD was found to significantly affect the phase behavior of LLDPE solutions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800982z Exemplaires
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Titre : Rheological modification of lubricating greases with pecycled polymers from different plastics waste Type de document : texte imprimé Auteurs : J. E. Martin-Alfonso, Auteur ; C. Valencia, Auteur ; M. C. Sánchez, Auteur Année de publication : 2009 Article en page(s) : pp. 4136–4144 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Lubricating greases Recycled polymers Plastics waste Small-amplitude oscillatory shear Viscous flow measurements Résumé : There is a growing interest on the development of new materials based on recycled polymers from plastics waste, since the use of such plastics represents a low-cost source of raw material. The purpose of the present work is to evaluate, from a comparative point of view, the effect that different waste and virgin polymers, used as viscosity modifier additives, exert on the rheological properties of standard lithium lubricating greases. Grease formulations containing diverse polymers, differing in nature and/or origin, were manufactured and rheologically characterized. Particularly, the influences of the type of polymer, the molecular weight and the presence of carbon black, used as filler in recycled polymers, have been evaluated. Small-amplitude oscillatory shear (SAOS) and viscous flow measurements were carried out, as well as calorimetric and thermogravimetric analysis. In general, recycled polymers induce a more important rheological modification than virgin polymers of the same nature. Thus, the addition of some recycled polymers such as HDPE, LDPE, PP, and EVA copolymer to lithium lubricating grease significantly increases the values of the rheological parameters analyzed. The crystallinity degree, mainly dependent on the nature of the polymer, and the carbon black content of recycled polymers have been pointed out as the most highly influencing parameters on the rheology of the lubricating greases studied. However, an apparent loss in mechanical stability for lubricating greases containing recycled polymers has been found when they were submitted to a severe mechanical treatment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801359g
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4136–4144[article] Rheological modification of lubricating greases with pecycled polymers from different plastics waste [texte imprimé] / J. E. Martin-Alfonso, Auteur ; C. Valencia, Auteur ; M. C. Sánchez, Auteur . - 2009 . - pp. 4136–4144.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4136–4144
Mots-clés : Lubricating greases Recycled polymers Plastics waste Small-amplitude oscillatory shear Viscous flow measurements Résumé : There is a growing interest on the development of new materials based on recycled polymers from plastics waste, since the use of such plastics represents a low-cost source of raw material. The purpose of the present work is to evaluate, from a comparative point of view, the effect that different waste and virgin polymers, used as viscosity modifier additives, exert on the rheological properties of standard lithium lubricating greases. Grease formulations containing diverse polymers, differing in nature and/or origin, were manufactured and rheologically characterized. Particularly, the influences of the type of polymer, the molecular weight and the presence of carbon black, used as filler in recycled polymers, have been evaluated. Small-amplitude oscillatory shear (SAOS) and viscous flow measurements were carried out, as well as calorimetric and thermogravimetric analysis. In general, recycled polymers induce a more important rheological modification than virgin polymers of the same nature. Thus, the addition of some recycled polymers such as HDPE, LDPE, PP, and EVA copolymer to lithium lubricating grease significantly increases the values of the rheological parameters analyzed. The crystallinity degree, mainly dependent on the nature of the polymer, and the carbon black content of recycled polymers have been pointed out as the most highly influencing parameters on the rheology of the lubricating greases studied. However, an apparent loss in mechanical stability for lubricating greases containing recycled polymers has been found when they were submitted to a severe mechanical treatment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801359g Exemplaires
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Titre : Linear free energy relationship correlations for room temperature ionic liquids : revised cation-specific and anion-specific equation coefficients for predictive applications covering a much larger area of chemical space Type de document : texte imprimé Auteurs : Laura M. Sprunger, Auteur ; Jennifer Gibbs, Auteur ; Amy Proctor, Auteur Année de publication : 2009 Article en page(s) : pp. 4145–4154 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ion-specific equation coefficients RTIL partition Abraham model Résumé : Previously reported ion-specific equation coefficients for both the Abraham general solvation model and Goss modified Abraham model are updated using recently measured activity coefficient, gas chromatographic retention factor, and solubility data for solutes dissolved in room temperature ionic liquids (RTILs). Reported for the first time are equation coefficients for 1-propyl-2,3-dimethylimidazolium cation, and octylsulfate and thiocyanate anions. In total nine sets of cation-specific and eight sets of anion-specific equation coefficients have been determined for each model. The derived correlations describe the 976 experimental gas-to-RTIL partition coefficients to within a standard deviation of 0.12 log units and the 955 experimental water-to-RTIL partitions to within a standard deviation of 0.15 log units. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801898j
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4145–4154[article] Linear free energy relationship correlations for room temperature ionic liquids : revised cation-specific and anion-specific equation coefficients for predictive applications covering a much larger area of chemical space [texte imprimé] / Laura M. Sprunger, Auteur ; Jennifer Gibbs, Auteur ; Amy Proctor, Auteur . - 2009 . - pp. 4145–4154.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4145–4154
Mots-clés : Ion-specific equation coefficients RTIL partition Abraham model Résumé : Previously reported ion-specific equation coefficients for both the Abraham general solvation model and Goss modified Abraham model are updated using recently measured activity coefficient, gas chromatographic retention factor, and solubility data for solutes dissolved in room temperature ionic liquids (RTILs). Reported for the first time are equation coefficients for 1-propyl-2,3-dimethylimidazolium cation, and octylsulfate and thiocyanate anions. In total nine sets of cation-specific and eight sets of anion-specific equation coefficients have been determined for each model. The derived correlations describe the 976 experimental gas-to-RTIL partition coefficients to within a standard deviation of 0.12 log units and the 955 experimental water-to-RTIL partitions to within a standard deviation of 0.15 log units. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801898j Exemplaires
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Titre : Technology for processing ammonium rhodanide of coking plants into high-purity ammonium thiocyanate and thiourea Type de document : texte imprimé Auteurs : Farit Kh. Urakaev, Auteur Année de publication : 2009 Article en page(s) : pp. 4155–4159 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Isomerization Ammonium thiocyanate (NH4NCS) Thiourea (NH2)2CS) Reverse reaction Résumé : The regularities of the reversible reaction of isomerization of ammonium thiocyanate (NH4NCS) into thiourea (NH2)2CS), and the reverse reaction, were analyzed. An ecologically clean and highly efficient method for the extraction, purification, separation, and production of isomers from the coal byproduct ammonium thiocyanate was developed based on the measured volatilities of NH4NCS and (NH2)2CS. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800880h
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4155–4159[article] Technology for processing ammonium rhodanide of coking plants into high-purity ammonium thiocyanate and thiourea [texte imprimé] / Farit Kh. Urakaev, Auteur . - 2009 . - pp. 4155–4159.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4155–4159
Mots-clés : Isomerization Ammonium thiocyanate (NH4NCS) Thiourea (NH2)2CS) Reverse reaction Résumé : The regularities of the reversible reaction of isomerization of ammonium thiocyanate (NH4NCS) into thiourea (NH2)2CS), and the reverse reaction, were analyzed. An ecologically clean and highly efficient method for the extraction, purification, separation, and production of isomers from the coal byproduct ammonium thiocyanate was developed based on the measured volatilities of NH4NCS and (NH2)2CS. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800880h Exemplaires
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Titre : Neural network prediction of interfacial tension at crystal/solution interface Type de document : texte imprimé Auteurs : K. Vasanth Kumar, Auteur Année de publication : 2009 Article en page(s) : pp. 4160–4164 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Interfacial tension Crystal/liquid interface oSL Crystal growth kinetics Neural network Résumé : Interfacial tension at the crystal/liquid interface is a crucial and important parameter in crystal growth kinetics. The objective of the present study is to develop a neural network that is simple to use for predicting this important parameter using only from the information of solubility, molecular weight, and density of the studied systems. A three-layer feed-forward neural network was constructed and tested to predict the interfacial tension at the crystal/solution interface. The concentration of solute in liquid phase, concentration of solute in solid phase, temperature, density and molecular weight of crystal were used as inputs to predict the interfacial tension at the crystal/liquid interface (σSL). The network was trained using the solubility information for 28 systems to predict the σSL value and was validated with 29 new systems. Despite the limited number of data used for training, the neural network was capable of predicting σSL successfully for the new inputs, which are kept unaware during the training process. The σSL value that is predicted by the artificial neural network during the training and testing process was compared with σSL predicted from the widely used empirical expression. For most of the systems, ANN better predicts σSL, when compared to empirical correlation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801666u
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4160–4164[article] Neural network prediction of interfacial tension at crystal/solution interface [texte imprimé] / K. Vasanth Kumar, Auteur . - 2009 . - pp. 4160–4164.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4160–4164
Mots-clés : Interfacial tension Crystal/liquid interface oSL Crystal growth kinetics Neural network Résumé : Interfacial tension at the crystal/liquid interface is a crucial and important parameter in crystal growth kinetics. The objective of the present study is to develop a neural network that is simple to use for predicting this important parameter using only from the information of solubility, molecular weight, and density of the studied systems. A three-layer feed-forward neural network was constructed and tested to predict the interfacial tension at the crystal/solution interface. The concentration of solute in liquid phase, concentration of solute in solid phase, temperature, density and molecular weight of crystal were used as inputs to predict the interfacial tension at the crystal/liquid interface (σSL). The network was trained using the solubility information for 28 systems to predict the σSL value and was validated with 29 new systems. Despite the limited number of data used for training, the neural network was capable of predicting σSL successfully for the new inputs, which are kept unaware during the training process. The σSL value that is predicted by the artificial neural network during the training and testing process was compared with σSL predicted from the widely used empirical expression. For most of the systems, ANN better predicts σSL, when compared to empirical correlation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801666u Exemplaires
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Titre : Variable molecular connectivity indices for predicting the diamagnetic susceptibilities of organic compounds Type de document : texte imprimé Auteurs : Lailong Mu, Auteur ; Hongmei He, Auteur ; Weihua Yang, Auteur Année de publication : 2009 Article en page(s) : pp. 4165–4175 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Molar diamagnetic susceptibilities Organic compounds Average absolute deviation Multivariate linear regression Résumé : For predicting the molar diamagnetic susceptibilities of organic compounds, a variable molecular connectivity index mχ′ and its converse index mχ′′ based on the adjacency matrix of molecular graphs and the variable atomic valence connectivity index δi′ were proposed. The optimal values of parameters a, b, and y included in definition of δi′, mχ′ and mχ′′ can be found by optimization methods. When a = 1.10, b = 2.8, and y = 0.36, a good five-parameter model can be constructed from mχ′ and mχ′′ by using the best subsets regression analysis method for the molar diamagnetic susceptibilities of organic compounds. The correlation coefficient r, standard error s, and average absolute deviation (AAD) of the multivariate linear regression (MLR) model are 0.9930, 4.99, and 3.72 cgs, respectively, for the 720 organic compounds (training set). The AAD of predicted values of the molar diamagnetic susceptibility of another 361 organic compounds (test set) is 4.37 cgs for the MLR model. The results show that the current method is more effective than literature methods for estimating the molar diamagnetic susceptibility of an organic compound. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801252j
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4165–4175[article] Variable molecular connectivity indices for predicting the diamagnetic susceptibilities of organic compounds [texte imprimé] / Lailong Mu, Auteur ; Hongmei He, Auteur ; Weihua Yang, Auteur . - 2009 . - pp. 4165–4175.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4165–4175
Mots-clés : Molar diamagnetic susceptibilities Organic compounds Average absolute deviation Multivariate linear regression Résumé : For predicting the molar diamagnetic susceptibilities of organic compounds, a variable molecular connectivity index mχ′ and its converse index mχ′′ based on the adjacency matrix of molecular graphs and the variable atomic valence connectivity index δi′ were proposed. The optimal values of parameters a, b, and y included in definition of δi′, mχ′ and mχ′′ can be found by optimization methods. When a = 1.10, b = 2.8, and y = 0.36, a good five-parameter model can be constructed from mχ′ and mχ′′ by using the best subsets regression analysis method for the molar diamagnetic susceptibilities of organic compounds. The correlation coefficient r, standard error s, and average absolute deviation (AAD) of the multivariate linear regression (MLR) model are 0.9930, 4.99, and 3.72 cgs, respectively, for the 720 organic compounds (training set). The AAD of predicted values of the molar diamagnetic susceptibility of another 361 organic compounds (test set) is 4.37 cgs for the MLR model. The results show that the current method is more effective than literature methods for estimating the molar diamagnetic susceptibility of an organic compound. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801252j Exemplaires
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Titre : Group contribution method for predicting melting points of imidazolium and benzimidazolium ionic liquids Type de document : texte imprimé Auteurs : Yan Huo, Auteur ; Shuqian Xia, Auteur ; Yan Zhang, Auteur Année de publication : 2009 Article en page(s) : p. 4176 Note générale : Chemical engineering Langues : Anglais (eng) Note de contenu : Additions and corrections of the same article in volume 48 n° 4 in pages: 2212-2217 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900347d
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - p. 4176[article] Group contribution method for predicting melting points of imidazolium and benzimidazolium ionic liquids [texte imprimé] / Yan Huo, Auteur ; Shuqian Xia, Auteur ; Yan Zhang, Auteur . - 2009 . - p. 4176.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - p. 4176
Note de contenu : Additions and corrections of the same article in volume 48 n° 4 in pages: 2212-2217 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900347d Exemplaires
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Titre : Group contribution method for predicting melting points of imidazolium and benzimidazolium ionic liquids Type de document : texte imprimé Auteurs : Yan Huo, Auteur ; Shuqian Xia, Auteur ; Yan Zhang, Auteur Année de publication : 2009 Article en page(s) : p. 4176 Note générale : Chemical engineering Langues : Anglais (eng) Note de contenu : Additions and corrections of the same article in volume 48 n° 4 in pages: 2212-2217 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900347d
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - p. 4176[article] Group contribution method for predicting melting points of imidazolium and benzimidazolium ionic liquids [texte imprimé] / Yan Huo, Auteur ; Shuqian Xia, Auteur ; Yan Zhang, Auteur . - 2009 . - p. 4176.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - p. 4176
Note de contenu : Additions and corrections of the same article in volume 48 n° 4 in pages: 2212-2217 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900347d Exemplaires
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