Nos Abonnements
Ressources Électroniques
|
[n° ou bulletin]
[n° ou bulletin]
Vol. 48 N° 6 - Mars 2009 [texte imprimé] . - 2009 . - p. 2739-3260 : ill. ; 28 cm. Chemical engineering Langues : Anglais (eng)
|
Exemplaires
| Code-barres | Cote | Support | Localisation | Section | Disponibilité |
|---|---|---|---|---|---|
| aucun exemplaire | |||||
|
Dépouillements
Ajouter le résultat dans votre panierGuide to CO2 separations in imidazolium-based room-temperature ionic liquids / Jason E. Bara in Industrial & engineering chemistry research, Vol. 48 N° 6 (Mars 2009)
Titre : Guide to CO2 separations in imidazolium-based room-temperature ionic liquids Type de document : texte imprimé Auteurs : Jason E. Bara, Auteur ; Trevor K. Carlisle, Auteur ; Christopher J. Gabriel, Auteur Année de publication : 2009 Article en page(s) : pp. 2739–2751 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Room-temperature ionic liquids CO2 separations Supported liquid membranes Résumé : Room-temperature ionic liquids (RTILs) are nonvolatile, tunable solvents that have generated significant interest across a wide variety of engineering applications. The use of RTILs as media for CO2 separations appears especially promising, with imidazolium-based salts at the center of this research effort. The solubilities of gases, particularly CO2, N2, and CH4, have been studied in a number of RTILs. Process temperature and the chemical structures of the cation and anion have significant impacts on gas solubility and gas pair selectivity. Models based on regular solution theory and group contributions are useful to predict and explain CO2 solubility and selectivity in imidazolium-based RTILs. In addition to their role as a physical solvent, RTILs might also be used in supported ionic liquid membranes (SILMs) as a highly permeable and selective transport medium. Performance data for SILMs indicates that they exhibit large permeabilities as well as CO2/N2 selectivities that outperform many polymer membranes. Furthermore, the greatest potential of RTILs for CO2 separations might lie in their ability to chemically capture CO2 when used in combination with amines. Amines can be tethered to the cation or the anion, or dissolved in RTILs, providing a wide range of chemical solvents for CO2 capture. However, despite all of their promising features, RTILs do have drawbacks to use in CO2 separations, which have been overlooked as appropriate comparisons of RTILs to common organic solvents and polymers have not been reported. A thorough summary of the capabilities—and limitations—of imidazolium-based RTILs in CO2-based separations with respect to a variety of materials is thus provided. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016237
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2739–2751[article] Guide to CO2 separations in imidazolium-based room-temperature ionic liquids [texte imprimé] / Jason E. Bara, Auteur ; Trevor K. Carlisle, Auteur ; Christopher J. Gabriel, Auteur . - 2009 . - pp. 2739–2751.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2739–2751
Mots-clés : Room-temperature ionic liquids CO2 separations Supported liquid membranes Résumé : Room-temperature ionic liquids (RTILs) are nonvolatile, tunable solvents that have generated significant interest across a wide variety of engineering applications. The use of RTILs as media for CO2 separations appears especially promising, with imidazolium-based salts at the center of this research effort. The solubilities of gases, particularly CO2, N2, and CH4, have been studied in a number of RTILs. Process temperature and the chemical structures of the cation and anion have significant impacts on gas solubility and gas pair selectivity. Models based on regular solution theory and group contributions are useful to predict and explain CO2 solubility and selectivity in imidazolium-based RTILs. In addition to their role as a physical solvent, RTILs might also be used in supported ionic liquid membranes (SILMs) as a highly permeable and selective transport medium. Performance data for SILMs indicates that they exhibit large permeabilities as well as CO2/N2 selectivities that outperform many polymer membranes. Furthermore, the greatest potential of RTILs for CO2 separations might lie in their ability to chemically capture CO2 when used in combination with amines. Amines can be tethered to the cation or the anion, or dissolved in RTILs, providing a wide range of chemical solvents for CO2 capture. However, despite all of their promising features, RTILs do have drawbacks to use in CO2 separations, which have been overlooked as appropriate comparisons of RTILs to common organic solvents and polymers have not been reported. A thorough summary of the capabilities—and limitations—of imidazolium-based RTILs in CO2-based separations with respect to a variety of materials is thus provided. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016237 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Lowered emissions schemes for upgrading ultra heavy petroleum feeds Type de document : texte imprimé Auteurs : Edward Furimsky, Auteur Année de publication : 2009 Article en page(s) : pp. 2752–2769 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Petroleum feeds Pipelining Catalytic hydroprocessing Slurry bed hydrocracking Résumé : Several commercial processes have been successfully used for upgrading heavy petroleum feeds containing less than 300 ppm of V + Ni. For problematic petroleum feeds, metal content exceeds this level and may approach 1000 ppm of V + Ni. Frequently, the upgrading battery is located in remote locations in the proximity of the heavy crude producing wells. In this case, the objective of upgrading is a syncrude suitable for pipelining. The complexity of upgrading increases with increasing content of metals, resins, and asphaltenes. The database of processing parameters has to be established for selecting optimal upgrading schemes, e.g., catalytic versus noncatalytic routes. From a processing point of view, the information on the yield of syncrude, steam, and electricity requirements, as well as hydrogen and catalyst consumption, are of primary interest. The parameters determining the environmental impact on the upgrading schemes have to be considered as well. The processes suitable for upgrading problematic feeds under evaluation include catalytic hydroprocessing, slurry bed hydrocracking, and coking. Various combinations of these processes have been used as well. Deasphalting combined with catalytic processes may be an attractive route providing that the rejected asphalt can be efficiently utilized on site. Lowered emissions can be achieved by utilizing asphalt and other residues from upgrading on gasification island for production of hydrogen, carbon dioxide, steam, and electricity. Compared with combustion, an integrated gasification-combined cycle operates at higher overall thermal efficiency with all emissions being significantly lower. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800865k
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2752–2769[article] Lowered emissions schemes for upgrading ultra heavy petroleum feeds [texte imprimé] / Edward Furimsky, Auteur . - 2009 . - pp. 2752–2769.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2752–2769
Mots-clés : Petroleum feeds Pipelining Catalytic hydroprocessing Slurry bed hydrocracking Résumé : Several commercial processes have been successfully used for upgrading heavy petroleum feeds containing less than 300 ppm of V + Ni. For problematic petroleum feeds, metal content exceeds this level and may approach 1000 ppm of V + Ni. Frequently, the upgrading battery is located in remote locations in the proximity of the heavy crude producing wells. In this case, the objective of upgrading is a syncrude suitable for pipelining. The complexity of upgrading increases with increasing content of metals, resins, and asphaltenes. The database of processing parameters has to be established for selecting optimal upgrading schemes, e.g., catalytic versus noncatalytic routes. From a processing point of view, the information on the yield of syncrude, steam, and electricity requirements, as well as hydrogen and catalyst consumption, are of primary interest. The parameters determining the environmental impact on the upgrading schemes have to be considered as well. The processes suitable for upgrading problematic feeds under evaluation include catalytic hydroprocessing, slurry bed hydrocracking, and coking. Various combinations of these processes have been used as well. Deasphalting combined with catalytic processes may be an attractive route providing that the rejected asphalt can be efficiently utilized on site. Lowered emissions can be achieved by utilizing asphalt and other residues from upgrading on gasification island for production of hydrogen, carbon dioxide, steam, and electricity. Compared with combustion, an integrated gasification-combined cycle operates at higher overall thermal efficiency with all emissions being significantly lower. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800865k Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Thermal dealkylation of tri-n-octylborane : effect of Lewis bases on extent and regioselectivity Type de document : texte imprimé Auteurs : A. B. Mzinyati, Auteur ; D. Jaganyi, Auteur Année de publication : 2009 Article en page(s) : pp. 2770–2773 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Tri-n-octylborane Dealkylation Lewis base Résumé : The dealkylation of tri-n-octylborane in the absence of bulk solvent was investigated in the temperature range 50−200 °C. Results indicate a linear increase in liberation of olefin from the trialkylborane in this temperature range, though the extent of dealkylation is not significant. Investigation of the regioselectivity of the dealkylation reaction shows no thermal-induced back-isomerization on the addition of 10 mol % of Lewis base, though the addition of dimethylformamide, dimethyl sulfoxide, hexamethylphosphoric triamide, and trimethyl phosphate results in back-isomerization of the alkyl chain. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801303g
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2770–2773[article] Thermal dealkylation of tri-n-octylborane : effect of Lewis bases on extent and regioselectivity [texte imprimé] / A. B. Mzinyati, Auteur ; D. Jaganyi, Auteur . - 2009 . - pp. 2770–2773.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2770–2773
Mots-clés : Tri-n-octylborane Dealkylation Lewis base Résumé : The dealkylation of tri-n-octylborane in the absence of bulk solvent was investigated in the temperature range 50−200 °C. Results indicate a linear increase in liberation of olefin from the trialkylborane in this temperature range, though the extent of dealkylation is not significant. Investigation of the regioselectivity of the dealkylation reaction shows no thermal-induced back-isomerization on the addition of 10 mol % of Lewis base, though the addition of dimethylformamide, dimethyl sulfoxide, hexamethylphosphoric triamide, and trimethyl phosphate results in back-isomerization of the alkyl chain. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801303g Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Effect of order of impregnation of Mo and Ni on the hydrodenitrogenation activity of NiO-MoO3/AlMCM-41 catalyst Type de document : texte imprimé Auteurs : S. J. Sardhar Basha, Auteur ; P. Vijayan, Auteur ; C. Suresh, Auteur Année de publication : 2009 Article en page(s) : pp. 2774–2780 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : NiO MoO3 H-AlMCM-41 Hydrodenitrogenation Ni-Mo catalysts Résumé : The influence of order of the impregnation of NiO and MoO3 on the structure and catalytic behavior of H-AlMCM-41 supported Ni−Mo catalysts for hydrodenitrogenation (HDN) has been investigated. These catalysts were well characterized by TEM, XRD, N2 adsorption−desorption, XPS, and FT-IR spectra of CO adsorption and tested for hydrodenitrogenation (HDN) of o-toluidine and cyclohexylamine. It was found that the catalyst prepared by sequential impregnation of NiO and MoO3 was more active than the catalyst prepared by coimpregnation. Among the sequentially impregnated catalysts, the catalyst in which NiO deposited first followed by MoO3 shows high HDN activity. TEM, FT-IR spectra of CO adsorption, and estimation of total sulfur of sulfide catalyst results clearly show that the NiO and MoO3 are well dispersed over H-AlMCM-41 on reverse order impregnated catalyst. The very low activity of coimpregnated catalyst is attributed to poor dispersion of metal oxides as well as due to the formation of stable stoichiometric oxide and aggregates of metal particle over the support surface. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800932u
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2774–2780[article] Effect of order of impregnation of Mo and Ni on the hydrodenitrogenation activity of NiO-MoO3/AlMCM-41 catalyst [texte imprimé] / S. J. Sardhar Basha, Auteur ; P. Vijayan, Auteur ; C. Suresh, Auteur . - 2009 . - pp. 2774–2780.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2774–2780
Mots-clés : NiO MoO3 H-AlMCM-41 Hydrodenitrogenation Ni-Mo catalysts Résumé : The influence of order of the impregnation of NiO and MoO3 on the structure and catalytic behavior of H-AlMCM-41 supported Ni−Mo catalysts for hydrodenitrogenation (HDN) has been investigated. These catalysts were well characterized by TEM, XRD, N2 adsorption−desorption, XPS, and FT-IR spectra of CO adsorption and tested for hydrodenitrogenation (HDN) of o-toluidine and cyclohexylamine. It was found that the catalyst prepared by sequential impregnation of NiO and MoO3 was more active than the catalyst prepared by coimpregnation. Among the sequentially impregnated catalysts, the catalyst in which NiO deposited first followed by MoO3 shows high HDN activity. TEM, FT-IR spectra of CO adsorption, and estimation of total sulfur of sulfide catalyst results clearly show that the NiO and MoO3 are well dispersed over H-AlMCM-41 on reverse order impregnated catalyst. The very low activity of coimpregnated catalyst is attributed to poor dispersion of metal oxides as well as due to the formation of stable stoichiometric oxide and aggregates of metal particle over the support surface. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800932u Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : High-temperature conductivity measurements of concentrated NaCl-H2SO4-H2O solutions up to 250 °C Type de document : texte imprimé Auteurs : Ming Huang, Auteur ; Vladimiros G. Papangelakis, Auteur Année de publication : 2009 Article en page(s) : pp. 2781–2785 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Electrodeless conductivity cell NaCl-H2SO4-H2O solutions Ionic Résumé : An electrodeless conductivity cell was employed to investigate the electrical conductivity of concentrated NaCl−H2SO4−H2O solutions particularly at high temperatures. All solutions were measured from 25 to 250 °C at the equilibrium vapor pressures. The maximum measured concentrations of NaCl and H2SO4 were 0.40 and 0.45 m, respectively. At 250 °C and a fixed concentration of H2SO4, the conductivity of NaCl−H2SO4−H2O solutions increases with the increasing concentration of NaCl. Similarly, at 250 °C and a fixed concentration of NaCl, the conductivity of NaCl−H2SO4−H2O solutions increases with the increasing concentration of H2SO4. It was found that the ionic equivalent conductivity of H3O+ is a function of ionic strength at 250 °C and is independent of the solution speciation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801064v
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2781–2785[article] High-temperature conductivity measurements of concentrated NaCl-H2SO4-H2O solutions up to 250 °C [texte imprimé] / Ming Huang, Auteur ; Vladimiros G. Papangelakis, Auteur . - 2009 . - pp. 2781–2785.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2781–2785
Mots-clés : Electrodeless conductivity cell NaCl-H2SO4-H2O solutions Ionic Résumé : An electrodeless conductivity cell was employed to investigate the electrical conductivity of concentrated NaCl−H2SO4−H2O solutions particularly at high temperatures. All solutions were measured from 25 to 250 °C at the equilibrium vapor pressures. The maximum measured concentrations of NaCl and H2SO4 were 0.40 and 0.45 m, respectively. At 250 °C and a fixed concentration of H2SO4, the conductivity of NaCl−H2SO4−H2O solutions increases with the increasing concentration of NaCl. Similarly, at 250 °C and a fixed concentration of NaCl, the conductivity of NaCl−H2SO4−H2O solutions increases with the increasing concentration of H2SO4. It was found that the ionic equivalent conductivity of H3O+ is a function of ionic strength at 250 °C and is independent of the solution speciation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801064v Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Evaluation of loofah as a sorbent in the decolorization of basic dye contaminated aqueous system Type de document : texte imprimé Auteurs : N. A. Oladoja, Auteur ; C. O. Aboluwoye, Auteur ; A. O. Akinkugbe, Auteur Année de publication : 2009 Article en page(s) : pp. 2786–2794 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fibrovascular network Luffa cylindrica Sorption system Freundlich isotherm models Résumé : The hard fibrovascular network of the fruit of Luffa cylindrica, loofah, was used in a batch sorption system to remove methylene blue (MB) from aqueous solution. The effects of pH on the sorption of MB by loofah were studied using equilibrium isotherm experiment. The Langmuir sorption capacity (qm, mg/g) of the loofah increased with increase in pH. The Freundlich isotherm models favored the prediction of the theoretical sorption capacity more than the Langmuir isotherm models. The kinetics of the sorption process was studied at varying initial MB concentrations using pseudo-first-order and pseudo-second-order kinetic models. The pseudo-second-order kinetic model was found to fit the experimental data for the entire sorption period with high coefficient of determination (r2). The prospects of regenerating the loofah was studied using four different eluting solvents in batch desorption studies. The results of the batch desorption studies showed that both chemisorption and ion-exchange played prominent role in the sorption process. The elution curve obtained from the continuous desorption studies showed that the elution rate was very fast and high elution efficiency could be obtained with 0.1 M HCl as an eluting solvent. The IR analysis confirmed the presence of polar functional groups and established interactions between the MB molecules and these functional groups. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801207a
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2786–2794[article] Evaluation of loofah as a sorbent in the decolorization of basic dye contaminated aqueous system [texte imprimé] / N. A. Oladoja, Auteur ; C. O. Aboluwoye, Auteur ; A. O. Akinkugbe, Auteur . - 2009 . - pp. 2786–2794.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2786–2794
Mots-clés : Fibrovascular network Luffa cylindrica Sorption system Freundlich isotherm models Résumé : The hard fibrovascular network of the fruit of Luffa cylindrica, loofah, was used in a batch sorption system to remove methylene blue (MB) from aqueous solution. The effects of pH on the sorption of MB by loofah were studied using equilibrium isotherm experiment. The Langmuir sorption capacity (qm, mg/g) of the loofah increased with increase in pH. The Freundlich isotherm models favored the prediction of the theoretical sorption capacity more than the Langmuir isotherm models. The kinetics of the sorption process was studied at varying initial MB concentrations using pseudo-first-order and pseudo-second-order kinetic models. The pseudo-second-order kinetic model was found to fit the experimental data for the entire sorption period with high coefficient of determination (r2). The prospects of regenerating the loofah was studied using four different eluting solvents in batch desorption studies. The results of the batch desorption studies showed that both chemisorption and ion-exchange played prominent role in the sorption process. The elution curve obtained from the continuous desorption studies showed that the elution rate was very fast and high elution efficiency could be obtained with 0.1 M HCl as an eluting solvent. The IR analysis confirmed the presence of polar functional groups and established interactions between the MB molecules and these functional groups. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801207a Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Mixed platinum-manganese oxide catalysts for combustion of volatile organic compounds Type de document : texte imprimé Auteurs : Aguero, Fabiola N., Auteur ; Barbero, Bibiana P., Auteur ; Manuel Fernando R. Pereira, Auteur Année de publication : 2009 Article en page(s) : pp. 2795–2800 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Mixed platinum-manganese oxide catalysts Chloroplatinic acid solution Ethanol combustion Toluene Résumé : Mixed platinum−manganese oxide catalysts were prepared by impregnation of supported manganese oxide catalysts with a chloroplatinic acid solution. Supported manganese oxide catalysts used as bare catalysts were prepared from different manganese precursors (nitrate and acetate) and with two manganese loadings. Supported pure platinum catalysts were also prepared as a reference. The catalytic activity was evaluated in ethanol and toluene combustion. Considering the catalysts from the different manganese precursors separately, the catalytic activity increased with increasing platinum dispersion. The platinum dispersion was affected by the presence of basic sites on the surface. Furthermore, at least two different platinum active sites were found to exist on the surface. The sites corresponding to a direct platinum−Al2O3 interaction were more active than those corresponding to a platinum−manganese oxide interaction. Finally, the catalytic tests in the combustion of an ethanol−toluene mixture demonstrated that manganese plays a beneficial role in avoiding the inhibition of toluene combustion that is observed on pure platinum catalysts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801310t
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2795–2800[article] Mixed platinum-manganese oxide catalysts for combustion of volatile organic compounds [texte imprimé] / Aguero, Fabiola N., Auteur ; Barbero, Bibiana P., Auteur ; Manuel Fernando R. Pereira, Auteur . - 2009 . - pp. 2795–2800.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2795–2800
Mots-clés : Mixed platinum-manganese oxide catalysts Chloroplatinic acid solution Ethanol combustion Toluene Résumé : Mixed platinum−manganese oxide catalysts were prepared by impregnation of supported manganese oxide catalysts with a chloroplatinic acid solution. Supported manganese oxide catalysts used as bare catalysts were prepared from different manganese precursors (nitrate and acetate) and with two manganese loadings. Supported pure platinum catalysts were also prepared as a reference. The catalytic activity was evaluated in ethanol and toluene combustion. Considering the catalysts from the different manganese precursors separately, the catalytic activity increased with increasing platinum dispersion. The platinum dispersion was affected by the presence of basic sites on the surface. Furthermore, at least two different platinum active sites were found to exist on the surface. The sites corresponding to a direct platinum−Al2O3 interaction were more active than those corresponding to a platinum−manganese oxide interaction. Finally, the catalytic tests in the combustion of an ethanol−toluene mixture demonstrated that manganese plays a beneficial role in avoiding the inhibition of toluene combustion that is observed on pure platinum catalysts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801310t Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Influence of EDC cracking severity on the marginal costs of vinyl chloride production Type de document : texte imprimé Auteurs : Reinhard Schirmeister, Auteur ; John Kahsnitz, Auteur ; Michael Träger, Auteur Année de publication : 2009 Article en page(s) : pp. 2801–2809 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : EDC cracking Vinyl chloride monomer Résumé : The selectivity of the EDC (1,2-dichloroethane) cracking process in vinyl chloride monomer (VCM) manufacturing strongly depends on the cracking severity and the EDC feed quality. A strong decline of selectivity is observed for EDC feed purities below 99.5 wt % or cracking rates above approximately 60%. The selectivity of the cracking process also deteriorates in the course of the plant’s operating time as a result of accelerated coke formation. Reduced selectivity in the process of EDC cracking results in increased marginal costs (additional costs per each additional tonne of VCM). This is especially relevant for a VCM plant running near full load. The marginal costs can be expressed as a function of the cracking rate and the resulting costs for processing the uncracked portion of EDC. With a new and simplified EDC cracking simulation model for the energy input and conversion, together with a simplified reaction model for the definition of the corresponding product spectrum, the cost impact of the aforementioned influences on the cracking process can be estimated in advance based on the current production rate and plant performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8006903
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2801–2809[article] Influence of EDC cracking severity on the marginal costs of vinyl chloride production [texte imprimé] / Reinhard Schirmeister, Auteur ; John Kahsnitz, Auteur ; Michael Träger, Auteur . - 2009 . - pp. 2801–2809.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2801–2809
Mots-clés : EDC cracking Vinyl chloride monomer Résumé : The selectivity of the EDC (1,2-dichloroethane) cracking process in vinyl chloride monomer (VCM) manufacturing strongly depends on the cracking severity and the EDC feed quality. A strong decline of selectivity is observed for EDC feed purities below 99.5 wt % or cracking rates above approximately 60%. The selectivity of the cracking process also deteriorates in the course of the plant’s operating time as a result of accelerated coke formation. Reduced selectivity in the process of EDC cracking results in increased marginal costs (additional costs per each additional tonne of VCM). This is especially relevant for a VCM plant running near full load. The marginal costs can be expressed as a function of the cracking rate and the resulting costs for processing the uncracked portion of EDC. With a new and simplified EDC cracking simulation model for the energy input and conversion, together with a simplified reaction model for the definition of the corresponding product spectrum, the cost impact of the aforementioned influences on the cracking process can be estimated in advance based on the current production rate and plant performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8006903 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Simultaneous free fatty acid esterification and triglyceride transesterification using a solid acid catalyst with in situ removal of water and unreacted methanol Type de document : texte imprimé Auteurs : Kaewta Suwannakarn, Auteur ; Edgar Lotero, Auteur ; Kanokwan Ngaosuwan, Auteur Année de publication : 2009 Article en page(s) : pp. 2810–2818 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Free fatty acids Simultaneous esterification Transesterification of triglycerides Waste grease Résumé : Waste greases used in biodiesel production contain high concentrations of free fatty acids (FFAs). To efficiently utilize these low-cost feedstocks for biodiesel synthesis, a preliminary acid-catalyzed esterification pretreatment is necessary to reduce their FFA contents. In this study, the use of a three-phase reaction has been investigated for the simultaneous esterification of FFAs and transesterification of triglycerides (TGs) using model mixtures of TGs and FFAs [0−25 wt % lauric acid (HLa) in tricaprylin (TCp)] to simulate waste grease and to permit easy distinction between the reactions. Trans/esterification with methanol was carried out using a commercial tungstated zirconia (WZ) solid catalyst in a well-stirred semibatch reactor at 130 °C operating at atmospheric pressure. Methanol was continuously charged to the reactor. Unreacted methanol and water produced during the reaction were continuously removed by vaporization, thereby favoring esterification. Esterification occurred 4 times faster than transesterification. Under our reaction conditions and in the presence of the catalyst, byproduct water was produced not only from HLa esterification but also from methanol dehydration. Because of the presence of this water, TGs were converted into the ester product by two routes: direct TG transesterification and TG hydrolysis followed by esterification. The catalyst, WZ, underwent 37% deactivation after three 2-h reaction cycles but completely recovered its original activity after a simple recalcination in flowing air. The feasibility of a continuous multiphase process for reducing FFAs in low-cost biodiesel feedstocks has been successfully demonstrated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800889w
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2810–2818[article] Simultaneous free fatty acid esterification and triglyceride transesterification using a solid acid catalyst with in situ removal of water and unreacted methanol [texte imprimé] / Kaewta Suwannakarn, Auteur ; Edgar Lotero, Auteur ; Kanokwan Ngaosuwan, Auteur . - 2009 . - pp. 2810–2818.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2810–2818
Mots-clés : Free fatty acids Simultaneous esterification Transesterification of triglycerides Waste grease Résumé : Waste greases used in biodiesel production contain high concentrations of free fatty acids (FFAs). To efficiently utilize these low-cost feedstocks for biodiesel synthesis, a preliminary acid-catalyzed esterification pretreatment is necessary to reduce their FFA contents. In this study, the use of a three-phase reaction has been investigated for the simultaneous esterification of FFAs and transesterification of triglycerides (TGs) using model mixtures of TGs and FFAs [0−25 wt % lauric acid (HLa) in tricaprylin (TCp)] to simulate waste grease and to permit easy distinction between the reactions. Trans/esterification with methanol was carried out using a commercial tungstated zirconia (WZ) solid catalyst in a well-stirred semibatch reactor at 130 °C operating at atmospheric pressure. Methanol was continuously charged to the reactor. Unreacted methanol and water produced during the reaction were continuously removed by vaporization, thereby favoring esterification. Esterification occurred 4 times faster than transesterification. Under our reaction conditions and in the presence of the catalyst, byproduct water was produced not only from HLa esterification but also from methanol dehydration. Because of the presence of this water, TGs were converted into the ester product by two routes: direct TG transesterification and TG hydrolysis followed by esterification. The catalyst, WZ, underwent 37% deactivation after three 2-h reaction cycles but completely recovered its original activity after a simple recalcination in flowing air. The feasibility of a continuous multiphase process for reducing FFAs in low-cost biodiesel feedstocks has been successfully demonstrated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800889w Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Preparation of nano-Pd/SiO2 by one-step flame spray pyrolysis and its hydrogenation activities : comparison to the conventional impregnation method Type de document : texte imprimé Auteurs : Okorn Mekasuwandumrong, Auteur ; Sirima Somboonthanakij, Auteur ; Piyasan Praserthdam, Auteur Année de publication : 2009 Article en page(s) : pp. 2819–2825 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nano-Pd/SiO2 catalysts Flame spray pyrolysis Conventional impregnation method Résumé : Characteristics and catalytic properties of the nano-Pd/SiO2 catalysts synthesized in one-step flame spray pyrolysis (FSP) were compared to those prepared on the flame-made SiO2 supports by conventional impregnation method. Pd0 metal particles/clusters En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012055
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2819–2825[article] Preparation of nano-Pd/SiO2 by one-step flame spray pyrolysis and its hydrogenation activities : comparison to the conventional impregnation method [texte imprimé] / Okorn Mekasuwandumrong, Auteur ; Sirima Somboonthanakij, Auteur ; Piyasan Praserthdam, Auteur . - 2009 . - pp. 2819–2825.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2819–2825
Mots-clés : Nano-Pd/SiO2 catalysts Flame spray pyrolysis Conventional impregnation method Résumé : Characteristics and catalytic properties of the nano-Pd/SiO2 catalysts synthesized in one-step flame spray pyrolysis (FSP) were compared to those prepared on the flame-made SiO2 supports by conventional impregnation method. Pd0 metal particles/clusters En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012055 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Hydrodechlorination of light organochlorinated compounds and their mixtures over Pd/TiO2-washcoated minimonoliths Type de document : texte imprimé Auteurs : Michael Bartoszek, Auteur ; Andreas Martin, Auteur Année de publication : 2009 Article en page(s) : pp. 2826–2835 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Catalytic hydrodechlorination Dichloromethane Tetrachloroethylene Chloroform Pd/TiO2-washcoated cordierite minimonoliths Résumé : The gas-phase catalytic hydrodechlorination (CHD) of dichloromethane (DCM), tetrachloroethylene (TTCE), and chloroform (CF) and their mixtures was studied over Pd/TiO2-washcoated cordierite minimonoliths. Experiments were carried out in a flow reactor at 120−300 °C, 1 bar, and 0.45 g min/mL. Catalytic runs with the pure compounds at 200 °C led to 60−100% conversion following the sequence CF > TTCE > DCM. Catalyst deactivation and regeneration were also examined. Lower conversions (between 30% and 95%) and catalyst deactivation were observed when mixtures of organochlorinated compounds where fed as reactants. DCM was the most affected when binary and ternary mixtures were used. Catalyst samples were characterized before and after reaction by various temperature-programmed studies (H2 TPR, He TPD, NH3 TPD, and TPO), H2 chemisorption, and XPS measurements. Most characterization studies were carried out using an online coupled mass spectrometer, thus allowing the parallel detection of different fragments and species corresponding to several hydrocarbons and HCl. In some experiments, a fast GC−ToF−MS system was used. The catalytic activity of spent samples was partially recovered by heating them in flowing air and then in 5% H2/N2. However, the initial reaction rate decreased by 62% over samples used in three consecutive runs when ternary mixtures were fed. Carbonaceous deposits of different nature and changes in the oxidation state of Pd (Pd0 to Pd2+ and Pd4+) appear to play key roles in catalyst deactivation, whereas acidity was found to remain almost the same for fresh and used catalyst samples. Carbonaceous deposits were removed by heating at temperatures lower than 400 °C in flowing air. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013742
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2826–2835[article] Hydrodechlorination of light organochlorinated compounds and their mixtures over Pd/TiO2-washcoated minimonoliths [texte imprimé] / Michael Bartoszek, Auteur ; Andreas Martin, Auteur . - 2009 . - pp. 2826–2835.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2826–2835
Mots-clés : Catalytic hydrodechlorination Dichloromethane Tetrachloroethylene Chloroform Pd/TiO2-washcoated cordierite minimonoliths Résumé : The gas-phase catalytic hydrodechlorination (CHD) of dichloromethane (DCM), tetrachloroethylene (TTCE), and chloroform (CF) and their mixtures was studied over Pd/TiO2-washcoated cordierite minimonoliths. Experiments were carried out in a flow reactor at 120−300 °C, 1 bar, and 0.45 g min/mL. Catalytic runs with the pure compounds at 200 °C led to 60−100% conversion following the sequence CF > TTCE > DCM. Catalyst deactivation and regeneration were also examined. Lower conversions (between 30% and 95%) and catalyst deactivation were observed when mixtures of organochlorinated compounds where fed as reactants. DCM was the most affected when binary and ternary mixtures were used. Catalyst samples were characterized before and after reaction by various temperature-programmed studies (H2 TPR, He TPD, NH3 TPD, and TPO), H2 chemisorption, and XPS measurements. Most characterization studies were carried out using an online coupled mass spectrometer, thus allowing the parallel detection of different fragments and species corresponding to several hydrocarbons and HCl. In some experiments, a fast GC−ToF−MS system was used. The catalytic activity of spent samples was partially recovered by heating them in flowing air and then in 5% H2/N2. However, the initial reaction rate decreased by 62% over samples used in three consecutive runs when ternary mixtures were fed. Carbonaceous deposits of different nature and changes in the oxidation state of Pd (Pd0 to Pd2+ and Pd4+) appear to play key roles in catalyst deactivation, whereas acidity was found to remain almost the same for fresh and used catalyst samples. Carbonaceous deposits were removed by heating at temperatures lower than 400 °C in flowing air. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013742 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Ethylbenzene transformation over a ZSM-5-based catalyst in a riser simulator Type de document : texte imprimé Auteurs : Al-Khattaf, S., Auteur ; N. M. Tukur, Auteur ; S. Rabiu, Auteur Année de publication : 2009 Article en page(s) : pp. 2836–2843 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ethylbenzene transformation ZSM-5-type catalyst Fluidized-bed reactor Cracking Résumé : The transformation of ethylbenzene has been studied over a ZSM-5-type catalyst in a riser simulator that mimics the operation of a fluidized-bed reactor. The study was conducted at 350, 375, 400, 450, and 500 °C for reaction times of 3, 5, 7, 10, 13, and 15 s. The effect of reaction conditions on the ratio of cracking to disproportionation products (C/D), the distribution of diethylbenzene (DEB) isomers (m-DEB and p-DEB), and the ratio of benzene/diethylbenzenes (B/DEB) are reported. The experimental results were modeled using quasi-steady-state approximation. Disproportionation was determined to dominate at low temperatures (350−400 °C), while cracking reaction becomes significant as higher temperatures (>400 °C). Thus, two mechanisms were postulated to represent the disappearance of ethylbenzene during the transformation reaction (one mechanism for low temperature, and another for the complete temperature range considered). Kinetic parameters that were used for the disappearance of ethylbenzene during the transformation reaction, and in its conversion into cracking and disproportionation products, were calculated using the catalyst activity decay function, based on the time-on-stream (TOS). The apparent activation energies were determined to decrease: Ecracking > Edisproportionation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801609x
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2836–2843[article] Ethylbenzene transformation over a ZSM-5-based catalyst in a riser simulator [texte imprimé] / Al-Khattaf, S., Auteur ; N. M. Tukur, Auteur ; S. Rabiu, Auteur . - 2009 . - pp. 2836–2843.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2836–2843
Mots-clés : Ethylbenzene transformation ZSM-5-type catalyst Fluidized-bed reactor Cracking Résumé : The transformation of ethylbenzene has been studied over a ZSM-5-type catalyst in a riser simulator that mimics the operation of a fluidized-bed reactor. The study was conducted at 350, 375, 400, 450, and 500 °C for reaction times of 3, 5, 7, 10, 13, and 15 s. The effect of reaction conditions on the ratio of cracking to disproportionation products (C/D), the distribution of diethylbenzene (DEB) isomers (m-DEB and p-DEB), and the ratio of benzene/diethylbenzenes (B/DEB) are reported. The experimental results were modeled using quasi-steady-state approximation. Disproportionation was determined to dominate at low temperatures (350−400 °C), while cracking reaction becomes significant as higher temperatures (>400 °C). Thus, two mechanisms were postulated to represent the disappearance of ethylbenzene during the transformation reaction (one mechanism for low temperature, and another for the complete temperature range considered). Kinetic parameters that were used for the disappearance of ethylbenzene during the transformation reaction, and in its conversion into cracking and disproportionation products, were calculated using the catalyst activity decay function, based on the time-on-stream (TOS). The apparent activation energies were determined to decrease: Ecracking > Edisproportionation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801609x Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Kinetic modeling of toxicity evolution during phenol oxidation Type de document : texte imprimé Auteurs : A. Santos, Auteur ; P. Yustos, Auteur ; S. Rodríguez, Auteur Année de publication : 2009 Article en page(s) : pp. 2844–2850 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Phenol oxidation Electrochemical treatment Photocatalysis Fenton’s reagent Catalytic wet Résumé : A previously proposed lumped pseudokinetic model has been improved and applied to analyze the literature toxicity evolution data for phenol oxidation using different abatement technologies, such as electrochemical (EC) treatment, photocatalysis (PC), Fenton’s reagent (FR), and catalytic wet oxidation (CWO). It has been considered that phenol, P, reacts to a lumped intermediate species I, and the latter reacts to a lumped species D. In this serial scheme, , all species can contribute to the toxicity of the aqueous sample. The literature toxicity data found for the oxidation of phenol were analyzed by this model considering first-order kinetics for both reactions in the serial scheme. The ratios of effective nominal concentrations, EC50(P)/EC50(I) and EC50(P)/EC50(D), were calculated from the fitting procedure. Values higher than unity were obtained in some cases, indicating that compounds more toxic than the parent pollutant are produced. Also, the pseudokinetic constants for the first and second reactions in the scheme were estimated. The lumping proposed adequately explains the literature data analyzed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801797q
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2844–2850[article] Kinetic modeling of toxicity evolution during phenol oxidation [texte imprimé] / A. Santos, Auteur ; P. Yustos, Auteur ; S. Rodríguez, Auteur . - 2009 . - pp. 2844–2850.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2844–2850
Mots-clés : Phenol oxidation Electrochemical treatment Photocatalysis Fenton’s reagent Catalytic wet Résumé : A previously proposed lumped pseudokinetic model has been improved and applied to analyze the literature toxicity evolution data for phenol oxidation using different abatement technologies, such as electrochemical (EC) treatment, photocatalysis (PC), Fenton’s reagent (FR), and catalytic wet oxidation (CWO). It has been considered that phenol, P, reacts to a lumped intermediate species I, and the latter reacts to a lumped species D. In this serial scheme, , all species can contribute to the toxicity of the aqueous sample. The literature toxicity data found for the oxidation of phenol were analyzed by this model considering first-order kinetics for both reactions in the serial scheme. The ratios of effective nominal concentrations, EC50(P)/EC50(I) and EC50(P)/EC50(D), were calculated from the fitting procedure. Values higher than unity were obtained in some cases, indicating that compounds more toxic than the parent pollutant are produced. Also, the pseudokinetic constants for the first and second reactions in the scheme were estimated. The lumping proposed adequately explains the literature data analyzed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801797q Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Cracking and coking behaviors of nascent volatiles derived from flash pyrolysis of woody biomass over mesoporous fluidized-bed material Type de document : texte imprimé Auteurs : Koji Kuramoto, Auteur ; Koichi Matsuoka, Auteur ; Takahiro Murakami, Auteur Année de publication : 2009 Article en page(s) : pp. 2851–2860 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Woody biomass gasification Dual-bubbling fluidized-bed system Catalytic porous γ -alumina Biomass pyrolysis/steam zoneChar/coke combustion zone Résumé : To increase the calorific value of the gaseous product from the woody biomass gasification process, a circulating dual-bubbling fluidized-bed gasification system based on the concept of physical separation of the combustion zone from the gasification zone has been proposed. To cope with the difficulty in control of the tar behavior, a catalytic porous γ-alumina has been considered as a bed material for the above process, which circulates between the biomass pyrolysis/steam gasification zone and the char/coke combustion zone, capturing tar vapor as coke on its surface catalytically in the gasifier. Preliminary process simulation clarified the minimum amount of carbonaceous portion (char and coke) in the biomass that must be burnt in the combustor for a thermally self-sustained process operation, suggesting that the coke derived from tar deposited over γ-alumina should be distributed to combustion and gasification zones by controlling the extent of the steam gasification of coke. To develop a method to control the tar conversion during pyrolysis and gasification, we examined the effects of porous γ-alumina on the tar behavior in the secondary reaction in a two-stage bubbling fluidized-bed reactor. Both gasification tests and Brunauer−Emmett−Teller analyses revealed that porous γ-alumina was markedly catalytic toward coking and dehydrogenation of the tar vapor, until a substantial amount of coke had deposited on the catalyst, thus occluding pores. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800760s
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2851–2860[article] Cracking and coking behaviors of nascent volatiles derived from flash pyrolysis of woody biomass over mesoporous fluidized-bed material [texte imprimé] / Koji Kuramoto, Auteur ; Koichi Matsuoka, Auteur ; Takahiro Murakami, Auteur . - 2009 . - pp. 2851–2860.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2851–2860
Mots-clés : Woody biomass gasification Dual-bubbling fluidized-bed system Catalytic porous γ -alumina Biomass pyrolysis/steam zoneChar/coke combustion zone Résumé : To increase the calorific value of the gaseous product from the woody biomass gasification process, a circulating dual-bubbling fluidized-bed gasification system based on the concept of physical separation of the combustion zone from the gasification zone has been proposed. To cope with the difficulty in control of the tar behavior, a catalytic porous γ-alumina has been considered as a bed material for the above process, which circulates between the biomass pyrolysis/steam gasification zone and the char/coke combustion zone, capturing tar vapor as coke on its surface catalytically in the gasifier. Preliminary process simulation clarified the minimum amount of carbonaceous portion (char and coke) in the biomass that must be burnt in the combustor for a thermally self-sustained process operation, suggesting that the coke derived from tar deposited over γ-alumina should be distributed to combustion and gasification zones by controlling the extent of the steam gasification of coke. To develop a method to control the tar conversion during pyrolysis and gasification, we examined the effects of porous γ-alumina on the tar behavior in the secondary reaction in a two-stage bubbling fluidized-bed reactor. Both gasification tests and Brunauer−Emmett−Teller analyses revealed that porous γ-alumina was markedly catalytic toward coking and dehydrogenation of the tar vapor, until a substantial amount of coke had deposited on the catalyst, thus occluding pores. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800760s Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Solid-liquid catalytic reactions in a new two-impinging-jets reactor : experiment and modeling Type de document : texte imprimé Auteurs : Asghar Molaei Dehkordi, Auteur ; Iman Safari, Auteur ; Amir A. Ebrahimi, Auteur Année de publication : 2009 Article en page(s) : pp. 2861–2869 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Two-impinging-jets loop reactor Solid-liquid catalytic reactions d-glucose d-fructose Résumé : Novel type of two-impinging-jets loop reactor (TIJLR) has been proposed and tested successfully for the solid−liquid catalytic reactions. The TIJLR was tested using the catalytic reaction of isomerization of d-glucose to d-fructose by immobilized glucose isomerase catalyst as a typical model system of solid−liquid catalytic reactions. The TIJLR is characterized by a high intensity reaction chamber, which is separated by a perforated plate from other parts of the reactor. The perforated plate was used as a filter to keep the catalyst particles within the reaction chamber. A compartment model with two adjustable parameters was considered to describe the pattern of flow within the reaction chamber. The compartment model proposed was based on the observation made during the experimental work. The adjustable parameters of the proposed model were determined through the experimental data by minimizing the discrepancies between the model predictions and corresponding experimental data. The influences of various operating and design parameters such as jet Reynolds number, feed flow rate, initial feed concentration, catalyst loading, and the volume of the reaction chamber on the performance capability of the TIJLR were investigated. It was found that the jet Reynolds number plays an important role in the performance capability of the TIJLR. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801240q
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2861–2869[article] Solid-liquid catalytic reactions in a new two-impinging-jets reactor : experiment and modeling [texte imprimé] / Asghar Molaei Dehkordi, Auteur ; Iman Safari, Auteur ; Amir A. Ebrahimi, Auteur . - 2009 . - pp. 2861–2869.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2861–2869
Mots-clés : Two-impinging-jets loop reactor Solid-liquid catalytic reactions d-glucose d-fructose Résumé : Novel type of two-impinging-jets loop reactor (TIJLR) has been proposed and tested successfully for the solid−liquid catalytic reactions. The TIJLR was tested using the catalytic reaction of isomerization of d-glucose to d-fructose by immobilized glucose isomerase catalyst as a typical model system of solid−liquid catalytic reactions. The TIJLR is characterized by a high intensity reaction chamber, which is separated by a perforated plate from other parts of the reactor. The perforated plate was used as a filter to keep the catalyst particles within the reaction chamber. A compartment model with two adjustable parameters was considered to describe the pattern of flow within the reaction chamber. The compartment model proposed was based on the observation made during the experimental work. The adjustable parameters of the proposed model were determined through the experimental data by minimizing the discrepancies between the model predictions and corresponding experimental data. The influences of various operating and design parameters such as jet Reynolds number, feed flow rate, initial feed concentration, catalyst loading, and the volume of the reaction chamber on the performance capability of the TIJLR were investigated. It was found that the jet Reynolds number plays an important role in the performance capability of the TIJLR. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801240q Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Influence of templates on the overgrowth of MCM-41 over HY and the hydrodesulfurization performances of the supported Ni-Mo catalysts Type de document : texte imprimé Auteurs : Xiang Li, Auteur ; Feng Zhou, Auteur ; Anjie Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 2870–2877 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : MCM-41 HY zeolite Ni-Mo sulfides Hydrodesulfurization Résumé : Overgrowth of MCM-41 on HY zeolite was performed using different templates [cetyltrimethylammonium bromide (CTABr) and cetyltrimethylammonium chloride (CTACl)]. The hydrodesulfurization (HDS) performances of Ni−Mo sulfides supported over these synthesized composites were evaluated with dibenzothiophene (DBT) as the model sulfur-containing molecule. TEM and STEM images revealed that zeolite HY overgrown with an MCM-41 layer (less than 20 nm) was obtained using CTABr as the template [MY(Br)], and the MCM-41 pore channels were assumed to be oriented outward from the inner HY core. Nevertheless, for the samples synthesized using CTACl [MY(Cl)], the HY crystals were buried independently in the MCM-41 phase. Both Ni−Mo/MY(Br) and Ni−Mo/MY(Cl) showed higher HDS activity and reducibility than Ni−Mo/MCM-41. The hydrogenation activity of Ni−Mo/MCM-41 was enhanced more than the direct desulfurization activity by the introduction of HY zeolite. Ni−Mo/MY(Br) and Ni−Mo/MY(Cl) exhibited hydrocracking activities equivalent to that of Ni−Mo/MCM-41, indicating that the HDS of DBT predominantly takes place in the mesopores of Ni−Mo/MY(Br) and Ni−Mo/MY(Cl). Because the active species located in the mesopores cannot have close contact with the strong acid sites of the HY zeolite, it is suggested that the spillover hydrogen might play an essential role in the HDS reaction over the supported Ni−Mo sulfides. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801389w
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2870–2877[article] Influence of templates on the overgrowth of MCM-41 over HY and the hydrodesulfurization performances of the supported Ni-Mo catalysts [texte imprimé] / Xiang Li, Auteur ; Feng Zhou, Auteur ; Anjie Wang, Auteur . - 2009 . - pp. 2870–2877.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2870–2877
Mots-clés : MCM-41 HY zeolite Ni-Mo sulfides Hydrodesulfurization Résumé : Overgrowth of MCM-41 on HY zeolite was performed using different templates [cetyltrimethylammonium bromide (CTABr) and cetyltrimethylammonium chloride (CTACl)]. The hydrodesulfurization (HDS) performances of Ni−Mo sulfides supported over these synthesized composites were evaluated with dibenzothiophene (DBT) as the model sulfur-containing molecule. TEM and STEM images revealed that zeolite HY overgrown with an MCM-41 layer (less than 20 nm) was obtained using CTABr as the template [MY(Br)], and the MCM-41 pore channels were assumed to be oriented outward from the inner HY core. Nevertheless, for the samples synthesized using CTACl [MY(Cl)], the HY crystals were buried independently in the MCM-41 phase. Both Ni−Mo/MY(Br) and Ni−Mo/MY(Cl) showed higher HDS activity and reducibility than Ni−Mo/MCM-41. The hydrogenation activity of Ni−Mo/MCM-41 was enhanced more than the direct desulfurization activity by the introduction of HY zeolite. Ni−Mo/MY(Br) and Ni−Mo/MY(Cl) exhibited hydrocracking activities equivalent to that of Ni−Mo/MCM-41, indicating that the HDS of DBT predominantly takes place in the mesopores of Ni−Mo/MY(Br) and Ni−Mo/MY(Cl). Because the active species located in the mesopores cannot have close contact with the strong acid sites of the HY zeolite, it is suggested that the spillover hydrogen might play an essential role in the HDS reaction over the supported Ni−Mo sulfides. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801389w Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Catalyst deactivation of Rh-coated foam monolith for catalytic partial oxidation of methane Type de document : texte imprimé Auteurs : Shi Ding, Auteur ; Yiyang Yang, Auteur ; Yong Jin, Auteur Année de publication : 2009 Article en page(s) : pp. 2878–2885 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Rhodium-coated foam monolith Catalyst deactivation Methane oxidation Résumé : The catalyst deactivation behavior of rhodium-coated foam monolith was systematically investigated in order to understand the means to improve the durability of the rhodium catalyst applied for catalytic partial oxidation of methane (CPOM). The overall CPOM reactions on the foam structured catalyst have been acknowledged to take place first in an oxidation zone and thereafter in a reforming zone. Severe metal sintering near the entrance of the structured catalyst (i.e., in the oxidation zone) was identified to be responsible for the observed deactivation of rhodium catalyst in the course of a 1000 h time-on-stream test under quasi-adiabatic conditions. Further analyses on the deactivation process indicated that the reaction pathway in the oxidation zone near the entrance can be summarized by a mixed mechanism, that is, two oxidation reactions and one reforming reaction, where H2 is the indirect product of steam reforming of the unreacted CH4. Detailed studies on the dependence of the catalyst stability on the operating conditions and the catalyst designs showed that adding an inert gas to the reactant gases, increasing the metal loading and/or decreasing the pore size of the foam-structured catalyst in the oxidation zone, can improve the catalyst stability, while the catalyst modifications in the reforming zone has little effect on the overall behavior of the catalyst stability. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801500n
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2878–2885[article] Catalyst deactivation of Rh-coated foam monolith for catalytic partial oxidation of methane [texte imprimé] / Shi Ding, Auteur ; Yiyang Yang, Auteur ; Yong Jin, Auteur . - 2009 . - pp. 2878–2885.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2878–2885
Mots-clés : Rhodium-coated foam monolith Catalyst deactivation Methane oxidation Résumé : The catalyst deactivation behavior of rhodium-coated foam monolith was systematically investigated in order to understand the means to improve the durability of the rhodium catalyst applied for catalytic partial oxidation of methane (CPOM). The overall CPOM reactions on the foam structured catalyst have been acknowledged to take place first in an oxidation zone and thereafter in a reforming zone. Severe metal sintering near the entrance of the structured catalyst (i.e., in the oxidation zone) was identified to be responsible for the observed deactivation of rhodium catalyst in the course of a 1000 h time-on-stream test under quasi-adiabatic conditions. Further analyses on the deactivation process indicated that the reaction pathway in the oxidation zone near the entrance can be summarized by a mixed mechanism, that is, two oxidation reactions and one reforming reaction, where H2 is the indirect product of steam reforming of the unreacted CH4. Detailed studies on the dependence of the catalyst stability on the operating conditions and the catalyst designs showed that adding an inert gas to the reactant gases, increasing the metal loading and/or decreasing the pore size of the foam-structured catalyst in the oxidation zone, can improve the catalyst stability, while the catalyst modifications in the reforming zone has little effect on the overall behavior of the catalyst stability. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801500n Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Preparation and characterization of carbon membranes derived from poly(phthalazinone ether sulfone) for gas separation Type de document : texte imprimé Auteurs : Bing Zhang, Auteur ; Guoliang Shen, Auteur ; Yonghong Wu, Auteur Année de publication : 2009 Article en page(s) : pp. 2886–2890 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Poly(phthalazinone ether sulfone) Carbon membranes X-ray diffraction Résumé : A new polymeric precursor, poly(phthalazinone ether sulfone) (PPES), was used as precursor to prepare carbon membranes via stabilization and pyrolysis. The thermal stability of PPES was determined by thermogravimetry. The evolution of functional groups of membranes was monitored by ATR-FTIR during the formation process of carbon membranes. The carbon structure of the resultant carbon membranes was analyzed by X-ray diffraction technology. The gas permeation property of carbon membranes was tested by pure gases, H2, CO2, O2, and N2. The results show that PPES is a highly thermally stable polymer with the char yield of 38.2 wt % at 700 °C in nitrogen. The functional groups of PPES gradually disappeared by forming a graphite-like structure in the membrane matrix during pyrolysis. At the test condition of 0.1 MPa and 30 °C, the gas permeabilities of H2, CO2, O2, and N2 for carbon membranes prepared at the stabilization and pyrolytic temperature of 440 and 650 °C are 610.13, 439.90, 146.98, and 26.95 barrer (1 barrer = 10−10 cm3 (STP) cm/(cm2 s cmHg) = 3.35 × 10−16 mol m/(m2 s Pa)), together with the selectivities of gas pairs H2/N2, CO2/N2, and O2/N2 of 22.6, 16.3, and 5.5, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013583
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2886–2890[article] Preparation and characterization of carbon membranes derived from poly(phthalazinone ether sulfone) for gas separation [texte imprimé] / Bing Zhang, Auteur ; Guoliang Shen, Auteur ; Yonghong Wu, Auteur . - 2009 . - pp. 2886–2890.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2886–2890
Mots-clés : Poly(phthalazinone ether sulfone) Carbon membranes X-ray diffraction Résumé : A new polymeric precursor, poly(phthalazinone ether sulfone) (PPES), was used as precursor to prepare carbon membranes via stabilization and pyrolysis. The thermal stability of PPES was determined by thermogravimetry. The evolution of functional groups of membranes was monitored by ATR-FTIR during the formation process of carbon membranes. The carbon structure of the resultant carbon membranes was analyzed by X-ray diffraction technology. The gas permeation property of carbon membranes was tested by pure gases, H2, CO2, O2, and N2. The results show that PPES is a highly thermally stable polymer with the char yield of 38.2 wt % at 700 °C in nitrogen. The functional groups of PPES gradually disappeared by forming a graphite-like structure in the membrane matrix during pyrolysis. At the test condition of 0.1 MPa and 30 °C, the gas permeabilities of H2, CO2, O2, and N2 for carbon membranes prepared at the stabilization and pyrolytic temperature of 440 and 650 °C are 610.13, 439.90, 146.98, and 26.95 barrer (1 barrer = 10−10 cm3 (STP) cm/(cm2 s cmHg) = 3.35 × 10−16 mol m/(m2 s Pa)), together with the selectivities of gas pairs H2/N2, CO2/N2, and O2/N2 of 22.6, 16.3, and 5.5, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013583 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Buoyant photocatalyst with greatly enhanced visible-light activity prepared through a low temperature hydrothermal method Type de document : texte imprimé Auteurs : Hui Han, Auteur ; Renbi Bai, Auteur Année de publication : 2009 Article en page(s) : pp. 2891–2898 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Buoyant photocatalyst TiO2 One-step process Résumé : In this study, TiO2 was modified and immobilized on polypropylene (PP) granules to prepare buoyant photocatalyst with visible light activity. The TiO2 nano-sol was first prepared from titanium n-butoxide (Ti(OBu)4) in the presence of acetyl acetone (AcAc) or acetic acid (AcOH) as an inhibiting agent and subsequently treated with triethylamine (TEA) under the condition of room temperature. Then, a simple one-step process was utilized for the simultaneous crystallization and immobilization of the treated TiO2 nanoparticles on the PP substrate in a low temperature hydrothermal reactor (150 °C). It was found that the TEA-treated TiO2 nano-sol with AcAc as the inhibiting agent led to high visible light activity for the prepared photocatalyst from the low temperature hydrothermal process. The light absorption edge was up to 800 nm, and the visible light absorption rate reached 32 to 66%, depending on the TEA-treatment time. XRD analysis showed all the TiO2-based photocatalysts having the major crystal structure of anatase and minor of brookite. Raman spectroscopy, however, clearly revealed the existence of the nitrogen-doped composition (i.e., TiO2−xNx) in the photocatalyst with high visible light activity. Experiments conducted for decolorization of methyl orange (MO) dye solutions showed the effectiveness of the prepared novel photocatalyst under both the UV and the visible light. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801362a
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2891–2898[article] Buoyant photocatalyst with greatly enhanced visible-light activity prepared through a low temperature hydrothermal method [texte imprimé] / Hui Han, Auteur ; Renbi Bai, Auteur . - 2009 . - pp. 2891–2898.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2891–2898
Mots-clés : Buoyant photocatalyst TiO2 One-step process Résumé : In this study, TiO2 was modified and immobilized on polypropylene (PP) granules to prepare buoyant photocatalyst with visible light activity. The TiO2 nano-sol was first prepared from titanium n-butoxide (Ti(OBu)4) in the presence of acetyl acetone (AcAc) or acetic acid (AcOH) as an inhibiting agent and subsequently treated with triethylamine (TEA) under the condition of room temperature. Then, a simple one-step process was utilized for the simultaneous crystallization and immobilization of the treated TiO2 nanoparticles on the PP substrate in a low temperature hydrothermal reactor (150 °C). It was found that the TEA-treated TiO2 nano-sol with AcAc as the inhibiting agent led to high visible light activity for the prepared photocatalyst from the low temperature hydrothermal process. The light absorption edge was up to 800 nm, and the visible light absorption rate reached 32 to 66%, depending on the TEA-treatment time. XRD analysis showed all the TiO2-based photocatalysts having the major crystal structure of anatase and minor of brookite. Raman spectroscopy, however, clearly revealed the existence of the nitrogen-doped composition (i.e., TiO2−xNx) in the photocatalyst with high visible light activity. Experiments conducted for decolorization of methyl orange (MO) dye solutions showed the effectiveness of the prepared novel photocatalyst under both the UV and the visible light. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801362a Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Force fields and point charges for crystal structure modeling Type de document : texte imprimé Auteurs : Michael Svärd, Auteur ; Åke C. Rasmuson, Auteur Année de publication : 2009 Article en page(s) : pp. 2899–2912 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Molecular simulation Atomic point charges Gasteiger Integral Résumé : Molecular simulation is increasingly used by chemical engineers and industrial chemists in process and product development. In particular, the possibility to predict the structure and stability of potential polymorphs of a substance is of tremendous interest to the pharmaceutical and specialty chemicals industry. Molecular mechanics modeling relies on the use of parametrized force fields and methods of assigning point charges to the atoms in the molecules. In commercial molecular simulation software, a wide variety of such combinations are available, and there is a need for critical assessment of the capabilities of the different alternatives. In the present work, the performance of several molecular mechanics force fields combined with different methods for the assignment of atomic point charges have been examined with regard to their ability to calculate absolute crystal lattice energies and their capacity to identify the experimental structure as a minimum on the potential energy hypersurface. Seven small, aromatic monomolecular crystalline compounds are used in the evaluation. It is found that the majority of the examined methods cannot be used to reliably predict absolute lattice energies. The most promising results were obtained with the Pcff force field using integral charges, and the Dreiding force field using Gasteiger charges, both of which performed with an accuracy of the same order of magnitude as the variations in experimental lattice energies. Overall, it has been observed that the best results are achieved if the same force field method is used to relax the crystal structure and calculate the energy, and to optimize and calculate the energy of the gas phase molecule used for the correction for changes in molecular geometry. The Pcff and Compass force fields with integral charges have been found to predict relaxed structures closest to the experimental ones. In addition, five different methods for determining point charges fitted to the electrostatic potential (ESP charges), available in the same software, have been evaluated. For each method, the molecular geometries of 10 small, organic molecules were optimized, and ESP charges calculated and analyzed for linear correlation with a set of reference charges of an accepted standard method, HF/6-31G*. Dmol-3 gives charges that correlate well with the reference charge. The charges from Vamp are not linearly scalable to the HF/6-31G*-level, which is attributed partly to the geometry optimization but mainly to the calculation of the ESP and the subsequent charge fit. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800502m
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2899–2912[article] Force fields and point charges for crystal structure modeling [texte imprimé] / Michael Svärd, Auteur ; Åke C. Rasmuson, Auteur . - 2009 . - pp. 2899–2912.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2899–2912
Mots-clés : Molecular simulation Atomic point charges Gasteiger Integral Résumé : Molecular simulation is increasingly used by chemical engineers and industrial chemists in process and product development. In particular, the possibility to predict the structure and stability of potential polymorphs of a substance is of tremendous interest to the pharmaceutical and specialty chemicals industry. Molecular mechanics modeling relies on the use of parametrized force fields and methods of assigning point charges to the atoms in the molecules. In commercial molecular simulation software, a wide variety of such combinations are available, and there is a need for critical assessment of the capabilities of the different alternatives. In the present work, the performance of several molecular mechanics force fields combined with different methods for the assignment of atomic point charges have been examined with regard to their ability to calculate absolute crystal lattice energies and their capacity to identify the experimental structure as a minimum on the potential energy hypersurface. Seven small, aromatic monomolecular crystalline compounds are used in the evaluation. It is found that the majority of the examined methods cannot be used to reliably predict absolute lattice energies. The most promising results were obtained with the Pcff force field using integral charges, and the Dreiding force field using Gasteiger charges, both of which performed with an accuracy of the same order of magnitude as the variations in experimental lattice energies. Overall, it has been observed that the best results are achieved if the same force field method is used to relax the crystal structure and calculate the energy, and to optimize and calculate the energy of the gas phase molecule used for the correction for changes in molecular geometry. The Pcff and Compass force fields with integral charges have been found to predict relaxed structures closest to the experimental ones. In addition, five different methods for determining point charges fitted to the electrostatic potential (ESP charges), available in the same software, have been evaluated. For each method, the molecular geometries of 10 small, organic molecules were optimized, and ESP charges calculated and analyzed for linear correlation with a set of reference charges of an accepted standard method, HF/6-31G*. Dmol-3 gives charges that correlate well with the reference charge. The charges from Vamp are not linearly scalable to the HF/6-31G*-level, which is attributed partly to the geometry optimization but mainly to the calculation of the ESP and the subsequent charge fit. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800502m Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Emulsion catastrophic inversion from abnormal to normal morphology. 8. Effect of formulation on the inversion produced by continuous stirring Type de document : texte imprimé Auteurs : Marianna Rondón-González, Auteur ; Luis F. Madariaga, Auteur ; Veronique Sadtler, Auteur Année de publication : 2009 Article en page(s) : pp. 2913–2919 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Water-oil-surfactant system Hydrophilic-lipophilic difference Continuous stirring Résumé : This paper deals with the influence of the global formulation of a water−oil−surfactant system, expressed by the hydrophilic−lipophilic difference (HLD), on the emulsion inversion produced just by the continuous stirring of an abnormal system, without any internal phase addition or any composition change. Evidence confirms that, under stirring, a w/O/W multiple emulsion is formed by the continuous inclusion of the external water phase inside the dispersed drops, which results in an increase of the effective dispersed phase volume until a critical value at which the inversion is triggered. Results suggest that the stability of the most internal emulsion determines the kinetics of inclusion and the stirring time required to induce inversion. However, it is the stability of both internal (w/O) and external (O/W) emulsions which determines the dispersed phase fraction at which the inversion is triggered. When different water fractions are used, the change of the critical dispersed phase fraction reveals that this process is affected by the partitioning of the surfactant mixture species between phases and results confirm that the critical dispersed phase fraction is a property related to the interfacial formulation of the system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801225h
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2913–2919[article] Emulsion catastrophic inversion from abnormal to normal morphology. 8. Effect of formulation on the inversion produced by continuous stirring [texte imprimé] / Marianna Rondón-González, Auteur ; Luis F. Madariaga, Auteur ; Veronique Sadtler, Auteur . - 2009 . - pp. 2913–2919.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2913–2919
Mots-clés : Water-oil-surfactant system Hydrophilic-lipophilic difference Continuous stirring Résumé : This paper deals with the influence of the global formulation of a water−oil−surfactant system, expressed by the hydrophilic−lipophilic difference (HLD), on the emulsion inversion produced just by the continuous stirring of an abnormal system, without any internal phase addition or any composition change. Evidence confirms that, under stirring, a w/O/W multiple emulsion is formed by the continuous inclusion of the external water phase inside the dispersed drops, which results in an increase of the effective dispersed phase volume until a critical value at which the inversion is triggered. Results suggest that the stability of the most internal emulsion determines the kinetics of inclusion and the stirring time required to induce inversion. However, it is the stability of both internal (w/O) and external (O/W) emulsions which determines the dispersed phase fraction at which the inversion is triggered. When different water fractions are used, the change of the critical dispersed phase fraction reveals that this process is affected by the partitioning of the surfactant mixture species between phases and results confirm that the critical dispersed phase fraction is a property related to the interfacial formulation of the system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801225h Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Effect of surface oxygen groups in carbons on hydrogen storage by spillover Type de document : texte imprimé Auteurs : Lifeng Wang, Auteur ; Frances H. Yang, Auteur ; Ralph T. Yang, Auteur Année de publication : 2009 Article en page(s) : pp. 2920–2926 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon materials Hydrogen adsorption Pd nanoparticles Résumé : Hydrogen adsorption properties of two different carbon materials (superactivated carbon, AX-21, and graphite oxide) doped with Pd nanoparticles have been studied. The effect of surface oxygen groups in AX-21 on hydrogen storage was investigated, and the results showed Pd supported on oxygen-modified AX-21 (Pd/AX-21-O) had a higher hydrogen storage capacity than Pd supported on unmodified AX-21 (Pd/AX-21). Overall heats of adsorption were obtained from the temperature dependence of the isotherms, and higher values were shown on the oxygen-modified AX-21 sample than the unmodified one, showing that the surface oxygen groups were favorable for hydrogen adsorption. Furthermore, a sample comprising Pd supported on graphite oxide with more surface oxygen (Pd/graphite oxide) was studied. The hydrogen adsorption on this sample showed a hydrogen storage capacity of 0.95 wt % at 100 atm and 298 K. Normalized by the BET surface area, the Pd/graphite oxide exhibited 2.8× the storage capacity of Pd/AX-21-O and 3.4× that of the Pd/AX-21 sample. Molecular orbital calculations showed that the presence of oxygen groups increased the binding energies of the spiltover H on graphite, which is consistent with the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014507
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2920–2926[article] Effect of surface oxygen groups in carbons on hydrogen storage by spillover [texte imprimé] / Lifeng Wang, Auteur ; Frances H. Yang, Auteur ; Ralph T. Yang, Auteur . - 2009 . - pp. 2920–2926.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2920–2926
Mots-clés : Carbon materials Hydrogen adsorption Pd nanoparticles Résumé : Hydrogen adsorption properties of two different carbon materials (superactivated carbon, AX-21, and graphite oxide) doped with Pd nanoparticles have been studied. The effect of surface oxygen groups in AX-21 on hydrogen storage was investigated, and the results showed Pd supported on oxygen-modified AX-21 (Pd/AX-21-O) had a higher hydrogen storage capacity than Pd supported on unmodified AX-21 (Pd/AX-21). Overall heats of adsorption were obtained from the temperature dependence of the isotherms, and higher values were shown on the oxygen-modified AX-21 sample than the unmodified one, showing that the surface oxygen groups were favorable for hydrogen adsorption. Furthermore, a sample comprising Pd supported on graphite oxide with more surface oxygen (Pd/graphite oxide) was studied. The hydrogen adsorption on this sample showed a hydrogen storage capacity of 0.95 wt % at 100 atm and 298 K. Normalized by the BET surface area, the Pd/graphite oxide exhibited 2.8× the storage capacity of Pd/AX-21-O and 3.4× that of the Pd/AX-21 sample. Molecular orbital calculations showed that the presence of oxygen groups increased the binding energies of the spiltover H on graphite, which is consistent with the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014507 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Optimal design of shell-and-tube heat exchangers using particle swarm optimization Type de document : texte imprimé Auteurs : Mauro A. S. S. Ravagnani, Auteur ; Aline P. Silva, Auteur ; Evaristo C. Biscaia Jr., Auteur Année de publication : 2009 Article en page(s) : pp. 2927–2935 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Shell-and-tube heat exchangers Particle swarm optimization Bell− Delaware method Résumé : In this paper, the shell-and-tube heat exchangers design is formulated as an optimization problem and solved with particle swarm optimization (PSO). The objective is to minimize the global cost including area cost and pumping cost or just area minimization, depending on data availability, rigorously following the standards of the Tubular Exchanger Manufacturers Association and respecting pressure drops and fouling limits. Given fluids temperatures, flow rates, physical properties (density, heat capacity, viscosity, and thermal conductivity), pressure drop and fouling limits, and area cost data, the proposed methodology calculates the optimal mechanical and thermal-hydraulic variables. The Bell−Delaware method is used for the shell-side calculations. Some literature cases are studied and results show that in this type of problem, with a very large number of nonlinear equations, the PSO algorithm presents better results, avoiding local minima. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800728n
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2927–2935[article] Optimal design of shell-and-tube heat exchangers using particle swarm optimization [texte imprimé] / Mauro A. S. S. Ravagnani, Auteur ; Aline P. Silva, Auteur ; Evaristo C. Biscaia Jr., Auteur . - 2009 . - pp. 2927–2935.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2927–2935
Mots-clés : Shell-and-tube heat exchangers Particle swarm optimization Bell− Delaware method Résumé : In this paper, the shell-and-tube heat exchangers design is formulated as an optimization problem and solved with particle swarm optimization (PSO). The objective is to minimize the global cost including area cost and pumping cost or just area minimization, depending on data availability, rigorously following the standards of the Tubular Exchanger Manufacturers Association and respecting pressure drops and fouling limits. Given fluids temperatures, flow rates, physical properties (density, heat capacity, viscosity, and thermal conductivity), pressure drop and fouling limits, and area cost data, the proposed methodology calculates the optimal mechanical and thermal-hydraulic variables. The Bell−Delaware method is used for the shell-side calculations. Some literature cases are studied and results show that in this type of problem, with a very large number of nonlinear equations, the PSO algorithm presents better results, avoiding local minima. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800728n Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Process analysis by means of focused beam reflectance measurements Type de document : texte imprimé Auteurs : Norbert Kail, Auteur ; Marquardt, Wolfgang, Auteur ; Heiko Briesen, Auteur Année de publication : 2009 Article en page(s) : pp. 2936–2946 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Process analytical technology In situ particle characterization Focused Beam Reflectance Measurement Chord-length distribution Particle size Résumé : Especially for the production of active pharmaceutical ingredients, the use of process analytical technology (PAT) is highly encouraged by the U.S. Food and Drug Administration. In crystallization and granulation processes, in situ particle characterization is the most important PAT. The technique of Focused Beam Reflectance Measurement (FBRM) is very well-suited for in situ particle characterization. A large community of users successfully applies FBRM technology for monitoring, fault detection, and quality control of dynamic processes. However, FBRM measurements are not easy to interpret, because the measured chord-length distribution (CLD) is different from any type of particle size distribution (PSD). For monitoring purposes, moments of the PSD are usually correlated empirically to moments of the CLD. Alternatively, process phenomena such as secondary nucleation and particle growth can be attributed to the time evolution of the number of chords detected in a length interval. To the authors’ knowledge, no publication has examined the accuracy of such correlations or presented a methodology to set the boundaries for the chord-length intervals. In this work, a mathematical method is presented with which a set of measured CLDs can be reduced to a small number of chord length classes, so that the class boundaries are chosen in an optimal way. A reconstruction of PSDs from FBRM data is not used for process monitoring in this work, because such a reconstruction may lack accuracy, as shown in earlier work [Kail et al. Chem. Eng. Sci. 2009]. The method presented in this work relies either on a simulation using the optical FBRM model presented in earlier work [Kail et al. Powder Technol. 2008, 185 (3), 211−222] or on reference experiments. With the presented methods, a batch crystallization of α-lactose monohydrate is analyzed. In addition, measurement artifacts observed in FBRM data are explained and discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800839s
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2936–2946[article] Process analysis by means of focused beam reflectance measurements [texte imprimé] / Norbert Kail, Auteur ; Marquardt, Wolfgang, Auteur ; Heiko Briesen, Auteur . - 2009 . - pp. 2936–2946.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2936–2946
Mots-clés : Process analytical technology In situ particle characterization Focused Beam Reflectance Measurement Chord-length distribution Particle size Résumé : Especially for the production of active pharmaceutical ingredients, the use of process analytical technology (PAT) is highly encouraged by the U.S. Food and Drug Administration. In crystallization and granulation processes, in situ particle characterization is the most important PAT. The technique of Focused Beam Reflectance Measurement (FBRM) is very well-suited for in situ particle characterization. A large community of users successfully applies FBRM technology for monitoring, fault detection, and quality control of dynamic processes. However, FBRM measurements are not easy to interpret, because the measured chord-length distribution (CLD) is different from any type of particle size distribution (PSD). For monitoring purposes, moments of the PSD are usually correlated empirically to moments of the CLD. Alternatively, process phenomena such as secondary nucleation and particle growth can be attributed to the time evolution of the number of chords detected in a length interval. To the authors’ knowledge, no publication has examined the accuracy of such correlations or presented a methodology to set the boundaries for the chord-length intervals. In this work, a mathematical method is presented with which a set of measured CLDs can be reduced to a small number of chord length classes, so that the class boundaries are chosen in an optimal way. A reconstruction of PSDs from FBRM data is not used for process monitoring in this work, because such a reconstruction may lack accuracy, as shown in earlier work [Kail et al. Chem. Eng. Sci. 2009]. The method presented in this work relies either on a simulation using the optical FBRM model presented in earlier work [Kail et al. Powder Technol. 2008, 185 (3), 211−222] or on reference experiments. With the presented methods, a batch crystallization of α-lactose monohydrate is analyzed. In addition, measurement artifacts observed in FBRM data are explained and discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800839s Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Novel unified modeling approach for short-term scheduling Type de document : texte imprimé Auteurs : Munawar A. Shaik, Auteur ; Christodoulos A. Floudas, Auteur Année de publication : 2009 Article en page(s) : pp. 2947–2964 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Short-term scheduling Unit-specific event-based formulations Three-index binary variables Continuous Résumé : Unit-specific event-based continuous time models have gained significant attention in the past decade for their advantages of requiring less number of event points, smaller problem size, and hence, a better computational performance. In the literature, different models had been proposed for short-term scheduling problems involving with and without resource constraints using unit-specific event-based formulations. For scheduling problems involving no resource constraints, generally the unit-specific event-based models do not allow tasks to continue over multiple events unlike in models that account for resource constraints explicitly. In this work, we emphasize the necessity for allowing tasks to take place over multiple event points even for simpler scheduling problems involving no resource constraints. We propose a novel short-term scheduling model using three-index binary and continuous variables that efficiently merges both the problems involving resources and no resource constraints into a unified, generic common framework. The proposed approach is based on state-task-network (STN) representation and is suitable for both batch and continuous plants, although we focus only on batch plants in this paper. Detailed computational case studies are presented to demonstrate the efficacy of the proposed model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010726
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2947–2964[article] Novel unified modeling approach for short-term scheduling [texte imprimé] / Munawar A. Shaik, Auteur ; Christodoulos A. Floudas, Auteur . - 2009 . - pp. 2947–2964.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2947–2964
Mots-clés : Short-term scheduling Unit-specific event-based formulations Three-index binary variables Continuous Résumé : Unit-specific event-based continuous time models have gained significant attention in the past decade for their advantages of requiring less number of event points, smaller problem size, and hence, a better computational performance. In the literature, different models had been proposed for short-term scheduling problems involving with and without resource constraints using unit-specific event-based formulations. For scheduling problems involving no resource constraints, generally the unit-specific event-based models do not allow tasks to continue over multiple events unlike in models that account for resource constraints explicitly. In this work, we emphasize the necessity for allowing tasks to take place over multiple event points even for simpler scheduling problems involving no resource constraints. We propose a novel short-term scheduling model using three-index binary and continuous variables that efficiently merges both the problems involving resources and no resource constraints into a unified, generic common framework. The proposed approach is based on state-task-network (STN) representation and is suitable for both batch and continuous plants, although we focus only on batch plants in this paper. Detailed computational case studies are presented to demonstrate the efficacy of the proposed model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010726 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Life cycle cost minimization of a total wastewater treatment network system Type de document : texte imprimé Auteurs : Seong-Rin Lim, Auteur ; Haewoo Lee, Auteur ; Jong Moon Park, Auteur Année de publication : 2009 Article en page(s) : pp. 2965–2971 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Wastewater treatment plants network system Life cycle cost Superstructure mode Résumé : Distributed wastewater treatment plants (WTPs) have been synthesized to reduce costs associated with wastewater treatment. This study developed a mathematical optimization model to synthesize existing distributed and terminal WTPs into an economical total wastewater treatment network system (TWTNS) from the perspective of life cycle cost (LCC). The objective function was formulated from the principal cost contributors in the construction, operations and maintenance, and disposal stages. The mass balances were formulated on the basis of the superstructure model, and the constraints were formulated to reflect real situations. A case study compared the LCC-minimized TWTNS (LNS) generated with this model to a conventional wastewater treatment system (CWTS) operated in a plant and to the TWTNS (FNS) generated by minimizing a total flowrate of wastewater treated in distributed WTPs. The LCC of the LNS was 12% less than that of the CWTS and was 27% less than that of the FNS, which validated the effectiveness of the model. This model can be used to practically retrofit existing WTPs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010897
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2965–2971[article] Life cycle cost minimization of a total wastewater treatment network system [texte imprimé] / Seong-Rin Lim, Auteur ; Haewoo Lee, Auteur ; Jong Moon Park, Auteur . - 2009 . - pp. 2965–2971.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2965–2971
Mots-clés : Wastewater treatment plants network system Life cycle cost Superstructure mode Résumé : Distributed wastewater treatment plants (WTPs) have been synthesized to reduce costs associated with wastewater treatment. This study developed a mathematical optimization model to synthesize existing distributed and terminal WTPs into an economical total wastewater treatment network system (TWTNS) from the perspective of life cycle cost (LCC). The objective function was formulated from the principal cost contributors in the construction, operations and maintenance, and disposal stages. The mass balances were formulated on the basis of the superstructure model, and the constraints were formulated to reflect real situations. A case study compared the LCC-minimized TWTNS (LNS) generated with this model to a conventional wastewater treatment system (CWTS) operated in a plant and to the TWTNS (FNS) generated by minimizing a total flowrate of wastewater treated in distributed WTPs. The LCC of the LNS was 12% less than that of the CWTS and was 27% less than that of the FNS, which validated the effectiveness of the model. This model can be used to practically retrofit existing WTPs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010897 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Synthesis and optimization of an ammonia-water absorption refrigeration cycle considering different types of heat exchangers by application of mixed-integer nonlinear programming Type de document : texte imprimé Auteurs : Luz María Chávez-Islas, Auteur ; Christopher L. Heard, Auteur ; Ignacio E. Grossmann, Auteur Année de publication : 2009 Article en page(s) : pp. 2972–2990 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ammonia-water absorption Refrigeration system Heat-exchangers Mixed-integer nonlinear programming Résumé : Optimization of the operating conditions and process scheme of an ammonia−water absorption refrigeration system, minimizing operating and annualized capital costs, is described. Various heat-exchanger technologies, the effect of the evaporator purge, and the thermodynamic restrictions of the system are taken into account. The objective is to make optimum use of various heat-exchange technologies to reduce the capital cost and meet the process refrigeration service requirements. A procedure to take account of the film coefficients and pressure drops of the different types of heat exchangers considered is proposed, which gives a solid basis for making decisions regarding the use of industrial ammonia−water absorption refrigeration. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801309h
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2972–2990[article] Synthesis and optimization of an ammonia-water absorption refrigeration cycle considering different types of heat exchangers by application of mixed-integer nonlinear programming [texte imprimé] / Luz María Chávez-Islas, Auteur ; Christopher L. Heard, Auteur ; Ignacio E. Grossmann, Auteur . - 2009 . - pp. 2972–2990.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2972–2990
Mots-clés : Ammonia-water absorption Refrigeration system Heat-exchangers Mixed-integer nonlinear programming Résumé : Optimization of the operating conditions and process scheme of an ammonia−water absorption refrigeration system, minimizing operating and annualized capital costs, is described. Various heat-exchanger technologies, the effect of the evaporator purge, and the thermodynamic restrictions of the system are taken into account. The objective is to make optimum use of various heat-exchange technologies to reduce the capital cost and meet the process refrigeration service requirements. A procedure to take account of the film coefficients and pressure drops of the different types of heat exchangers considered is proposed, which gives a solid basis for making decisions regarding the use of industrial ammonia−water absorption refrigeration. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801309h Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : A disjunctive programming model for simultaneous synthesis and detailed design of cooling networks Type de document : texte imprimé Auteurs : José María Ponce-Ortega, Auteur ; Medardo Serna-González, Auteur ; Arturo Jimenez-Gutierrez, Auteur Année de publication : 2009 Article en page(s) : pp. 2991–3003 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cooling networks Disjunctive programming formulation Optimum cooling network configuration Mechanical design Thermal-hydraulic variables Résumé : This paper presents a model that simultaneously considers synthesis and detailed design aspects of cooling networks. The model is based on a generalized disjunctive programming formulation that is transformed into a mixed-integer nonlinear program. The objective function is to minimize the total annual cost, which accounts for the cold utility consumption cost, the capital cost for the coolers and pumps, and the pumping costs. The model uses a stagewise superstructure that allows combinations of cooler arrangements in series or in parallel, as well as bypass, mixing, and splitting of the cold utility. The model also incorporates several constraints to meet some specified design codes. In addition to the optimum cooling network configuration, the solution provides the details on the mechanical design features and thermal−hydraulic variables of each cooler unit. Three example problems are presented to show the application of the proposed model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015494
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2991–3003[article] A disjunctive programming model for simultaneous synthesis and detailed design of cooling networks [texte imprimé] / José María Ponce-Ortega, Auteur ; Medardo Serna-González, Auteur ; Arturo Jimenez-Gutierrez, Auteur . - 2009 . - pp. 2991–3003.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2991–3003
Mots-clés : Cooling networks Disjunctive programming formulation Optimum cooling network configuration Mechanical design Thermal-hydraulic variables Résumé : This paper presents a model that simultaneously considers synthesis and detailed design aspects of cooling networks. The model is based on a generalized disjunctive programming formulation that is transformed into a mixed-integer nonlinear program. The objective function is to minimize the total annual cost, which accounts for the cold utility consumption cost, the capital cost for the coolers and pumps, and the pumping costs. The model uses a stagewise superstructure that allows combinations of cooler arrangements in series or in parallel, as well as bypass, mixing, and splitting of the cold utility. The model also incorporates several constraints to meet some specified design codes. In addition to the optimum cooling network configuration, the solution provides the details on the mechanical design features and thermal−hydraulic variables of each cooler unit. Three example problems are presented to show the application of the proposed model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015494 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Enhancing a smelter off-gas system using a plant-wide control design Type de document : texte imprimé Auteurs : Antonio C. B. De Araujo, Auteur ; Helen Shang, Auteur Année de publication : 2009 Article en page(s) : pp. 3004–3013 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Off-gas treatment system Smelter roaster processes Systematic control design Steady-state analysis Résumé : An off-gas treatment system is a vital component of smelter roaster processes as it ensures operation is in accordance with environmental regulations in terms of hazardous emissions. It is, therefore, paramount that a well-designed control structure be incorporated into the system. Analysis of the off-gas treatment processes for a roaster using a systematic control design procedure to provide the necessary verification to current industrial practices for controlling these processes was carried out. We approached this by conducting a top-down (steady-state) analysis based on an available nonlinear model of the process. The results provide insight into, and potential improvement of, the control of the off-gas system. Through designing the bottom-up structure, a feedback control structure was developed to give robust and effective control in terms of disturbance rejection capabilities. The proposed control structure provides for improved performance in an easy form to implement. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800254s
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3004–3013[article] Enhancing a smelter off-gas system using a plant-wide control design [texte imprimé] / Antonio C. B. De Araujo, Auteur ; Helen Shang, Auteur . - 2009 . - pp. 3004–3013.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3004–3013
Mots-clés : Off-gas treatment system Smelter roaster processes Systematic control design Steady-state analysis Résumé : An off-gas treatment system is a vital component of smelter roaster processes as it ensures operation is in accordance with environmental regulations in terms of hazardous emissions. It is, therefore, paramount that a well-designed control structure be incorporated into the system. Analysis of the off-gas treatment processes for a roaster using a systematic control design procedure to provide the necessary verification to current industrial practices for controlling these processes was carried out. We approached this by conducting a top-down (steady-state) analysis based on an available nonlinear model of the process. The results provide insight into, and potential improvement of, the control of the off-gas system. Through designing the bottom-up structure, a feedback control structure was developed to give robust and effective control in terms of disturbance rejection capabilities. The proposed control structure provides for improved performance in an easy form to implement. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800254s Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Extensions of a multistart clustering algorithm for constrained global optimization problems Type de document : texte imprimé Auteurs : José-Oscar H. Sendín, Auteur ; Banga, Julio R., Auteur ; Tibor Csendes, Auteur Année de publication : 2009 Article en page(s) : pp. 3014–3023 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nonlinear programming problems Multistart clustering algorithm Résumé : Here, we consider the solution of constrained global optimization problems, such as those arising from the fields of chemical and biosystems engineering. These problems are frequently formulated (or can be transformed to) nonlinear programming problems (NLPs) subject to differential−algebraic equations (DAEs). In this work, we extend a popular multistart clustering algorithm for solving these problems, incorporating new key features including an efficient mechanism for handling constraints and a robust derivative-free local solver. The performance of this new method is evaluated by solving a collection of test problems, including several challenging case studies from the (bio)process engineering area. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800319m
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3014–3023[article] Extensions of a multistart clustering algorithm for constrained global optimization problems [texte imprimé] / José-Oscar H. Sendín, Auteur ; Banga, Julio R., Auteur ; Tibor Csendes, Auteur . - 2009 . - pp. 3014–3023.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3014–3023
Mots-clés : Nonlinear programming problems Multistart clustering algorithm Résumé : Here, we consider the solution of constrained global optimization problems, such as those arising from the fields of chemical and biosystems engineering. These problems are frequently formulated (or can be transformed to) nonlinear programming problems (NLPs) subject to differential−algebraic equations (DAEs). In this work, we extend a popular multistart clustering algorithm for solving these problems, incorporating new key features including an efficient mechanism for handling constraints and a robust derivative-free local solver. The performance of this new method is evaluated by solving a collection of test problems, including several challenging case studies from the (bio)process engineering area. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800319m Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Proactive scheduling strategy applied to decoking operations of an industrial naphtha cracking furnace system Type de document : texte imprimé Auteurs : Heejin Lim, Auteur ; Jaein Choi, Auteur ; Matthew Realff, Auteur Année de publication : 2009 Article en page(s) : pp. 3024–3032 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Decoking operations Scheduling Naphtha cracking furnace system Résumé : The scheduling of decoking operations in a naphtha cracking furnace system is an important issue to ethylene producers, because excessive coke deposits inside the furnace coils can negatively impact plant safety and productivity. For optimal scheduling, accurate online estimation of the thickness of the deposited coke is essential. In practice, the coke thickness can be estimated from various furnace operating variables, but measurement errors and unexpected changes in the coke growth rate cause significant uncertainties in the estimation. Errors in the coke thickness estimate manifest themselves as gaps between the model prediction and actual measured values of key operating variables such as the pressure drop and the tube temperature. To handle the potential conflicts in an established schedule caused by the uncertainties, we propose to use a “proactive” scheduling strategy. In “reactive” scheduling, rescheduling is performed whenever an unexpected operational problem causes an unscheduled decoking operation, thus making a standing schedule no longer viable. On the other hand, in the “proactive” scheduling strategy, model information, as well as measurement information, are used to determine appropriate rescheduling points before actual operational problems arise. Under the proposed proactive scheduling strategy, the model predictions of the pressure drop and the tube temperature are compared against their measurements while the plant is operating according to a current decoking schedule. Whenever the gap between the model prediction and the measurement is larger than a given threshold value, the model is updated based on the measurements and the scheduling problem is solved again with the updated model information. The new scheduling solution is applied to the operation until the next scheduling point is found. This proactive scheduling procedure is applied to a simulated system of multiple furnaces. The advantages of the proactive scheduling strategy, in terms of productivity and risk management, are shown by comparing it with a reactive scheduling strategy and a heuristic decoking strategy over a large number of scenarios. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800331z
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3024–3032[article] Proactive scheduling strategy applied to decoking operations of an industrial naphtha cracking furnace system [texte imprimé] / Heejin Lim, Auteur ; Jaein Choi, Auteur ; Matthew Realff, Auteur . - 2009 . - pp. 3024–3032.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3024–3032
Mots-clés : Decoking operations Scheduling Naphtha cracking furnace system Résumé : The scheduling of decoking operations in a naphtha cracking furnace system is an important issue to ethylene producers, because excessive coke deposits inside the furnace coils can negatively impact plant safety and productivity. For optimal scheduling, accurate online estimation of the thickness of the deposited coke is essential. In practice, the coke thickness can be estimated from various furnace operating variables, but measurement errors and unexpected changes in the coke growth rate cause significant uncertainties in the estimation. Errors in the coke thickness estimate manifest themselves as gaps between the model prediction and actual measured values of key operating variables such as the pressure drop and the tube temperature. To handle the potential conflicts in an established schedule caused by the uncertainties, we propose to use a “proactive” scheduling strategy. In “reactive” scheduling, rescheduling is performed whenever an unexpected operational problem causes an unscheduled decoking operation, thus making a standing schedule no longer viable. On the other hand, in the “proactive” scheduling strategy, model information, as well as measurement information, are used to determine appropriate rescheduling points before actual operational problems arise. Under the proposed proactive scheduling strategy, the model predictions of the pressure drop and the tube temperature are compared against their measurements while the plant is operating according to a current decoking schedule. Whenever the gap between the model prediction and the measurement is larger than a given threshold value, the model is updated based on the measurements and the scheduling problem is solved again with the updated model information. The new scheduling solution is applied to the operation until the next scheduling point is found. This proactive scheduling procedure is applied to a simulated system of multiple furnaces. The advantages of the proactive scheduling strategy, in terms of productivity and risk management, are shown by comparing it with a reactive scheduling strategy and a heuristic decoking strategy over a large number of scenarios. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800331z Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Potential of hyperspectral imaging for quality control of polymer blend films Type de document : texte imprimé Auteurs : Ryan Gosselin, Auteur ; Denis Rodrigue, Auteur ; Rubén González-Núñez, Auteur Année de publication : 2009 Article en page(s) : pp. 3033–3042 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hyperspectral imaging sensor Polymer film blends Multiresolutional multivariate image analysis Résumé : A visible−near-infrared (VIS-NIR) hyperspectral imaging sensor is proposed for online nondestructive monitoring of polymer film blends produced by extrusion blowing. Such a sensor provides a much higher spatial resolution of analysis compared to probes or probe arrays, which should help in detecting smaller localized defects inducing poor film quality (mechanical, optical, barrier properties) at a macroscopic scale. Multiresolutional multivariate image analysis (MR-MIA) was used to extract those spectral and textural features from images that are the most highly correlated to film composition distribution and mechanical properties. When applied to a low-density polyethylene/polystyrene (LDPE/PS) blend produced under various operating conditions, the imaging sensor was able to monitor the two dominant effects on mechanical properties: (1) the effect of film composition (raw materials) and (2) the stretching effect caused by postextrusion conditions (process). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800997x
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3033–3042[article] Potential of hyperspectral imaging for quality control of polymer blend films [texte imprimé] / Ryan Gosselin, Auteur ; Denis Rodrigue, Auteur ; Rubén González-Núñez, Auteur . - 2009 . - pp. 3033–3042.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3033–3042
Mots-clés : Hyperspectral imaging sensor Polymer film blends Multiresolutional multivariate image analysis Résumé : A visible−near-infrared (VIS-NIR) hyperspectral imaging sensor is proposed for online nondestructive monitoring of polymer film blends produced by extrusion blowing. Such a sensor provides a much higher spatial resolution of analysis compared to probes or probe arrays, which should help in detecting smaller localized defects inducing poor film quality (mechanical, optical, barrier properties) at a macroscopic scale. Multiresolutional multivariate image analysis (MR-MIA) was used to extract those spectral and textural features from images that are the most highly correlated to film composition distribution and mechanical properties. When applied to a low-density polyethylene/polystyrene (LDPE/PS) blend produced under various operating conditions, the imaging sensor was able to monitor the two dominant effects on mechanical properties: (1) the effect of film composition (raw materials) and (2) the stretching effect caused by postextrusion conditions (process). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800997x Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Nonlinear MPC using an identified LPV model Type de document : texte imprimé Auteurs : Zuhua Xu, Auteur ; Jun Zhao, Auteur ; Jixin Qian, Auteur Année de publication : 2009 Article en page(s) : pp. 3043–3051 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nonlinear model predictive control Linear parameter-varying Résumé : A method of nonlinear model predictive control based on an identified LPV model is proposed. In process identification, a linear parameter varying (LPV) model approach is used. First, typical working-points are selected and linear models are identified using data sets at various working-points; then the LPV model is identified by interpolating the linear models using total data that include transition test data. Further, nonlinear model predictive control based on the LPV model is proposed. The control action is computed via a multistep linearization method of nonlinear optimization problem. The method uses low cost tests and can reach higher control performance than linear MPC. Simulation studies are used to verify the effectiveness of the method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801057q
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3043–3051[article] Nonlinear MPC using an identified LPV model [texte imprimé] / Zuhua Xu, Auteur ; Jun Zhao, Auteur ; Jixin Qian, Auteur . - 2009 . - pp. 3043–3051.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3043–3051
Mots-clés : Nonlinear model predictive control Linear parameter-varying Résumé : A method of nonlinear model predictive control based on an identified LPV model is proposed. In process identification, a linear parameter varying (LPV) model approach is used. First, typical working-points are selected and linear models are identified using data sets at various working-points; then the LPV model is identified by interpolating the linear models using total data that include transition test data. Further, nonlinear model predictive control based on the LPV model is proposed. The control action is computed via a multistep linearization method of nonlinear optimization problem. The method uses low cost tests and can reach higher control performance than linear MPC. Simulation studies are used to verify the effectiveness of the method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801057q Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Incremental modeling of nonlinear distributed parameter processes via spatiotemporal kernel series expansion Type de document : texte imprimé Auteurs : Han-Xiong Li, Auteur ; Chenkun Qi, Auteur Année de publication : 2009 Article en page(s) : pp. 3052–3058 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Incremental modeling Nonlinear distributed parameter systems Spatiotemporal Volterra kernels Time-space separation Résumé : In this article, an incremental modeling approach is proposed to model nonlinear distributed parameter systems, with the help of the newly constructed spatiotemporal Volterra kernels. The complex spatiotemporal process is first decomposed into a series of spatiotemporal kernels, upon which the time−space separation can be further conducted with the spatial Karhunen−Loève and temporal Laguerre basis function expansions. These two decompositions can gradually separate the nonlinear time/space coupled dynamics. Finally, the kernels in the spatiotemporal model are estimated from the experimental data incrementally, which can easily achieve satisfactory modeling performance. Simulations of two transport−reaction processes demonstrate the effectiveness of the proposed modeling approach. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801184a
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3052–3058[article] Incremental modeling of nonlinear distributed parameter processes via spatiotemporal kernel series expansion [texte imprimé] / Han-Xiong Li, Auteur ; Chenkun Qi, Auteur . - 2009 . - pp. 3052–3058.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3052–3058
Mots-clés : Incremental modeling Nonlinear distributed parameter systems Spatiotemporal Volterra kernels Time-space separation Résumé : In this article, an incremental modeling approach is proposed to model nonlinear distributed parameter systems, with the help of the newly constructed spatiotemporal Volterra kernels. The complex spatiotemporal process is first decomposed into a series of spatiotemporal kernels, upon which the time−space separation can be further conducted with the spatial Karhunen−Loève and temporal Laguerre basis function expansions. These two decompositions can gradually separate the nonlinear time/space coupled dynamics. Finally, the kernels in the spatiotemporal model are estimated from the experimental data incrementally, which can easily achieve satisfactory modeling performance. Simulations of two transport−reaction processes demonstrate the effectiveness of the proposed modeling approach. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801184a Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Fault detection and identification using modified bayesian classification on PCA subspace Type de document : texte imprimé Auteurs : Jialin Liu, Auteur ; Ding-Sou Chen, Auteur Année de publication : 2009 Article en page(s) : pp. 3059–3077 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Bayesian classification Monitoring method Principal component analysis subspace Résumé : A novel process monitoring method based on modified Bayesian classification on PCA subspace is proposed. Fault detection and identification are the major steps to diagnose root causes of a process fault. However, before the faulty variables from the abnormal operations are identified, the different operating states need to be clustered from the historical data. The proposed approach modifies the Bayesian classification method to cluster data into groups. Therefore, a new fault identification index is derived based on cluster center and covariance. An industrial compressor process is used to demonstrate the effectiveness of the proposed approach. In the example, process-insight-based variables were monitored along with the measured variables. The capability of fault diagnosis has been improved, since the fault identification indices are directly related to the variables with process characteristics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801243z
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3059–3077[article] Fault detection and identification using modified bayesian classification on PCA subspace [texte imprimé] / Jialin Liu, Auteur ; Ding-Sou Chen, Auteur . - 2009 . - pp. 3059–3077.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3059–3077
Mots-clés : Bayesian classification Monitoring method Principal component analysis subspace Résumé : A novel process monitoring method based on modified Bayesian classification on PCA subspace is proposed. Fault detection and identification are the major steps to diagnose root causes of a process fault. However, before the faulty variables from the abnormal operations are identified, the different operating states need to be clustered from the historical data. The proposed approach modifies the Bayesian classification method to cluster data into groups. Therefore, a new fault identification index is derived based on cluster center and covariance. An industrial compressor process is used to demonstrate the effectiveness of the proposed approach. In the example, process-insight-based variables were monitored along with the measured variables. The capability of fault diagnosis has been improved, since the fault identification indices are directly related to the variables with process characteristics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801243z Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Stochastic programming approach for the planning of offshore oil or gas field infrastructure under decision-dependent uncertainty Type de document : texte imprimé Auteurs : Bora Tarhan, Auteur ; Ignacio E. Grossmann, Auteur ; Vikas Goel, Auteur Année de publication : 2009 Article en page(s) : pp. 3078–3097 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Offshore oil Multistage stochastic programming model Decisiondependent uncertainty Résumé : The planning of offshore oil or gas field infrastructure under uncertainty is addressed in this article. The main uncertainties considered are in the initial maximum oil or gas flowrate, the recoverable oil or gas volume, and the water breakthrough time of the reservoir, which are represented by discrete distributions. Furthermore, it is assumed that these uncertainties are not immediately realized, but are gradually revealed as a function of design and operation decisions. To account for these decision-dependent uncertainties, we propose a multistage stochastic programming model that captures the complex economic objectives and nonlinear reservoir behavior and simultaneously optimizes the investment and operating decisions over the entire planning horizon. The proposed solution algorithm relies on a duality-based branch-and-bound method involving subproblems as nonconvex mixed-integer nonlinear programs. Several examples involving nonlinear reservoir models are presented to illustrate the application of the proposed method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013549
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3078–3097[article] Stochastic programming approach for the planning of offshore oil or gas field infrastructure under decision-dependent uncertainty [texte imprimé] / Bora Tarhan, Auteur ; Ignacio E. Grossmann, Auteur ; Vikas Goel, Auteur . - 2009 . - pp. 3078–3097.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3078–3097
Mots-clés : Offshore oil Multistage stochastic programming model Decisiondependent uncertainty Résumé : The planning of offshore oil or gas field infrastructure under uncertainty is addressed in this article. The main uncertainties considered are in the initial maximum oil or gas flowrate, the recoverable oil or gas volume, and the water breakthrough time of the reservoir, which are represented by discrete distributions. Furthermore, it is assumed that these uncertainties are not immediately realized, but are gradually revealed as a function of design and operation decisions. To account for these decision-dependent uncertainties, we propose a multistage stochastic programming model that captures the complex economic objectives and nonlinear reservoir behavior and simultaneously optimizes the investment and operating decisions over the entire planning horizon. The proposed solution algorithm relies on a duality-based branch-and-bound method involving subproblems as nonconvex mixed-integer nonlinear programs. Several examples involving nonlinear reservoir models are presented to illustrate the application of the proposed method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013549 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Enhanced control of unstable cascade processes with time delays using a modified smith predictor Type de document : texte imprimé Auteurs : S. Uma, Auteur ; M. Chidambaram, Auteur ; A. Seshagiri Rao, Auteur Année de publication : 2009 Article en page(s) : pp. 3098–3111 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cascade controller Smith predictor structure Unstable cascade Direct synthesis method Internal model control Résumé : This paper presents a simple cascade controller in the enhanced modified Smith predictor structure for control of open loop unstable cascade processes with/without zero. The proposed structure consists of two control loops, a secondary inner loop and a primary outer loop. The method has totally three controllers of which the secondary loop has one controller and the primary loop has two controllers. The secondary loop controller is designed using the internal model control (IMC) technique. The primary loop set point tracking and disturbance rejection controllers are designed using the direct synthesis method. The primary set point tracking controller is designed as a proportional, integral, and derivative (PID) controller with lag filter and the primary disturbance rejection controller is designed as a PID with lead−lag filter. Simulation studies have been carried out on various cascade unstable processes with/without zero. The present method gives significant disturbance rejection both in the inner and outer loops. Also, the proposed method shows significant improvement when compared to the recently reported methods in the literature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801590e
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3098–3111[article] Enhanced control of unstable cascade processes with time delays using a modified smith predictor [texte imprimé] / S. Uma, Auteur ; M. Chidambaram, Auteur ; A. Seshagiri Rao, Auteur . - 2009 . - pp. 3098–3111.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3098–3111
Mots-clés : Cascade controller Smith predictor structure Unstable cascade Direct synthesis method Internal model control Résumé : This paper presents a simple cascade controller in the enhanced modified Smith predictor structure for control of open loop unstable cascade processes with/without zero. The proposed structure consists of two control loops, a secondary inner loop and a primary outer loop. The method has totally three controllers of which the secondary loop has one controller and the primary loop has two controllers. The secondary loop controller is designed using the internal model control (IMC) technique. The primary loop set point tracking and disturbance rejection controllers are designed using the direct synthesis method. The primary set point tracking controller is designed as a proportional, integral, and derivative (PID) controller with lag filter and the primary disturbance rejection controller is designed as a PID with lead−lag filter. Simulation studies have been carried out on various cascade unstable processes with/without zero. The present method gives significant disturbance rejection both in the inner and outer loops. Also, the proposed method shows significant improvement when compared to the recently reported methods in the literature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801590e Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Estimating dosing rates and energy consumption for electrocoagulation using iron and aluminum electrodes Type de document : texte imprimé Auteurs : Zheng Gu, Auteur ; Zhaohui Liao, Auteur ; Matthew Schulz, Auteur Année de publication : 2009 Article en page(s) : pp. 3112–3117 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Aluminum electrodes Iron Electrocoagulation reactor Chemical corrosion Résumé : The effect of current density on dosing rates and energy requirements for iron and aluminum electrodes in a bench-scale electrocoagulation (EC) reactor have been investigated. Dissolution rates of the iron and aluminum anodes were independent of bulk solution pH values. Iron dosing rates followed Faraday’s law, but aluminum dosing rates averaged 83% greater than those predicted by Faraday’s law. Chemical corrosion of both the anode and cathode contributed to the extra-faradaic aluminum dosing. A method was developed to determine the faradaic power consumption as a function of the current density. An equation describing power dissipation by ohmic and faradaic mechanisms was derived and used to estimate energy consumption per unit coagulant dose for EC reactors operating over a wide range of conditions. The derived equation can be used to compare the operational costs for EC with those using chemical additives, such as alum or ferric chloride. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801086c
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3112–3117[article] Estimating dosing rates and energy consumption for electrocoagulation using iron and aluminum electrodes [texte imprimé] / Zheng Gu, Auteur ; Zhaohui Liao, Auteur ; Matthew Schulz, Auteur . - 2009 . - pp. 3112–3117.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3112–3117
Mots-clés : Aluminum electrodes Iron Electrocoagulation reactor Chemical corrosion Résumé : The effect of current density on dosing rates and energy requirements for iron and aluminum electrodes in a bench-scale electrocoagulation (EC) reactor have been investigated. Dissolution rates of the iron and aluminum anodes were independent of bulk solution pH values. Iron dosing rates followed Faraday’s law, but aluminum dosing rates averaged 83% greater than those predicted by Faraday’s law. Chemical corrosion of both the anode and cathode contributed to the extra-faradaic aluminum dosing. A method was developed to determine the faradaic power consumption as a function of the current density. An equation describing power dissipation by ohmic and faradaic mechanisms was derived and used to estimate energy consumption per unit coagulant dose for EC reactors operating over a wide range of conditions. The derived equation can be used to compare the operational costs for EC with those using chemical additives, such as alum or ferric chloride. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801086c Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Liquid membrane process for the selective recovery of uranium from industrial leach solutions Type de document : texte imprimé Auteurs : P. S. Kulkarni, Auteur ; S. Mukhopadhyay, Auteur ; S. K. Ghosh, Auteur Année de publication : 2009 Article en page(s) : pp. 3118–3125 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Leach liquor Uranium Emulsion liquid membrane Résumé : Leach liquor of uranium concentrates are generated at Uranium Corporation of India Limited (UCIL), Jaduguda, India. Application of the emulsion liquid membrane (ELM) technique was tested for the efficient recovery of uranium from the leach liquor, in the presence of metal ions such as Fe, Ca, Mg, and Mn. The liquid membrane employed consisted of a diluent (light and heavy paraffin), a surfactant (Span 80), and an extractant (Alamine 336), and sodium carbonate was used as the stripping solution. Initially, the ELM process parameters were optimized by using synthetic leach liquor as the feed phase. The role of the acidic feed-phase pH, which enhances the cotransport of H+ ions along with uranium inside the emulsion globules, was found to be significant, as it helped in achieving the complete extraction and stripping of uranium. The best optimized parameters were directly used for the separation and concentration of uranium from industrial leach solutions. In one step, in the presence of various metal ions, the selective permeation of uranyl ions through the liquid membrane was observed to be greater than 90%, and the concentration of uranium inside the strip phase was observed to be nearly 7 times higher. Separation factors of uranium with respect to Fe, Mg, Ca, and Mn were experimentally found to be 129, 781, 43, and 1462, respectively, in 12 min. Finally, application of the process in uranium ore processing is demonstrated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800819q
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3118–3125[article] Liquid membrane process for the selective recovery of uranium from industrial leach solutions [texte imprimé] / P. S. Kulkarni, Auteur ; S. Mukhopadhyay, Auteur ; S. K. Ghosh, Auteur . - 2009 . - pp. 3118–3125.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3118–3125
Mots-clés : Leach liquor Uranium Emulsion liquid membrane Résumé : Leach liquor of uranium concentrates are generated at Uranium Corporation of India Limited (UCIL), Jaduguda, India. Application of the emulsion liquid membrane (ELM) technique was tested for the efficient recovery of uranium from the leach liquor, in the presence of metal ions such as Fe, Ca, Mg, and Mn. The liquid membrane employed consisted of a diluent (light and heavy paraffin), a surfactant (Span 80), and an extractant (Alamine 336), and sodium carbonate was used as the stripping solution. Initially, the ELM process parameters were optimized by using synthetic leach liquor as the feed phase. The role of the acidic feed-phase pH, which enhances the cotransport of H+ ions along with uranium inside the emulsion globules, was found to be significant, as it helped in achieving the complete extraction and stripping of uranium. The best optimized parameters were directly used for the separation and concentration of uranium from industrial leach solutions. In one step, in the presence of various metal ions, the selective permeation of uranyl ions through the liquid membrane was observed to be greater than 90%, and the concentration of uranium inside the strip phase was observed to be nearly 7 times higher. Separation factors of uranium with respect to Fe, Mg, Ca, and Mn were experimentally found to be 129, 781, 43, and 1462, respectively, in 12 min. Finally, application of the process in uranium ore processing is demonstrated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800819q Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Impact of conventional water treatment coagulants on mineral scaling in RO desalting of brackish water Type de document : texte imprimé Auteurs : Myung-man Kim, Auteur ; James Au, Auteur ; Anditya Rahardianto, Auteur Année de publication : 2009 Article en page(s) : pp. 3126–3135 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Coagulants Brackish water Bulk crystallization Reverse osmosis membrane Résumé : The potential impact of coagulants on mineral scaling in reverse osmosis (RO) feed treatment of brackish water was assessed experimentally, with respect to calcium sulfate and barium sulfate scaling potential, via a bulk crystallization and membrane scaling tests. The scale suppression effectiveness of six commercial antiscalants was first ranked based on measured observed bulk crystallization induction times. Bulk crystallization tests with three standard coagulants (ACH, FeCl3, and polyDADMAC), when used independently, demonstrated retardation of the observed crystallization induction time. However, along with an antiscalant dosing, antiscalant scale suppression was significantly reduced and scaling occurred at the same or greater severity relative to the additive-free feed solution. RO membrane scaling tests also indicated that, when the coagulants were present, antiscalant effectiveness was significantly reduced, consistent with the expectation based on bulk crystallization tests. Although the coagulants demonstrated a slight scale suppression quality in bulk crystallization tests at low dosages ( En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800937c
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3126–3135[article] Impact of conventional water treatment coagulants on mineral scaling in RO desalting of brackish water [texte imprimé] / Myung-man Kim, Auteur ; James Au, Auteur ; Anditya Rahardianto, Auteur . - 2009 . - pp. 3126–3135.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3126–3135
Mots-clés : Coagulants Brackish water Bulk crystallization Reverse osmosis membrane Résumé : The potential impact of coagulants on mineral scaling in reverse osmosis (RO) feed treatment of brackish water was assessed experimentally, with respect to calcium sulfate and barium sulfate scaling potential, via a bulk crystallization and membrane scaling tests. The scale suppression effectiveness of six commercial antiscalants was first ranked based on measured observed bulk crystallization induction times. Bulk crystallization tests with three standard coagulants (ACH, FeCl3, and polyDADMAC), when used independently, demonstrated retardation of the observed crystallization induction time. However, along with an antiscalant dosing, antiscalant scale suppression was significantly reduced and scaling occurred at the same or greater severity relative to the additive-free feed solution. RO membrane scaling tests also indicated that, when the coagulants were present, antiscalant effectiveness was significantly reduced, consistent with the expectation based on bulk crystallization tests. Although the coagulants demonstrated a slight scale suppression quality in bulk crystallization tests at low dosages ( En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800937c Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Antifouling property of a weak polyelectrolyte membrane based on poly(acrylonitrile) during protein ultrafiltration Type de document : texte imprimé Auteurs : Su, Yanlei, Auteur ; Chunxia Mu, Auteur ; Chao Li, Auteur Année de publication : 2009 Article en page(s) : pp. 3136–3141 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Weak polyelectrolyte membrane Poly(acrylonitrile) Bovine serum albumin Lysozyme Antifouling property Résumé : The permeability of a weak polyelectrolyte ultrafiltration membrane based on poly(acrylonitrile and 2-dimethylaminoethyl methacrylate) (PAN-DMAEMA) copolymer was measured at various conditions of solution pH and ionic strength. Bovine serum albumin (BSA) and lysozyme were used as model proteins to investigate the antifouling property of PAN-DMAEMA ultrafiltration membrane. Electrostatic interactions, the conformation of PDMAEMA chains, and the nature of protein play important roles in enhancing the antifouling property of PAN-DMAEAM membrane. During BSA ultrafiltration, BSA rejection ratio is decreased, flux recovery ratio is remarkably increased, and the total membrane fouling and irreversible membrane fouling are decreased at higher pH value and ionic strength. During lysozyme ultrafiltration, the PAN-DMAEAM membrane displays excellent antifouling property in a broad range of pH and ionic strength. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801393z
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3136–3141[article] Antifouling property of a weak polyelectrolyte membrane based on poly(acrylonitrile) during protein ultrafiltration [texte imprimé] / Su, Yanlei, Auteur ; Chunxia Mu, Auteur ; Chao Li, Auteur . - 2009 . - pp. 3136–3141.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3136–3141
Mots-clés : Weak polyelectrolyte membrane Poly(acrylonitrile) Bovine serum albumin Lysozyme Antifouling property Résumé : The permeability of a weak polyelectrolyte ultrafiltration membrane based on poly(acrylonitrile and 2-dimethylaminoethyl methacrylate) (PAN-DMAEMA) copolymer was measured at various conditions of solution pH and ionic strength. Bovine serum albumin (BSA) and lysozyme were used as model proteins to investigate the antifouling property of PAN-DMAEMA ultrafiltration membrane. Electrostatic interactions, the conformation of PDMAEMA chains, and the nature of protein play important roles in enhancing the antifouling property of PAN-DMAEAM membrane. During BSA ultrafiltration, BSA rejection ratio is decreased, flux recovery ratio is remarkably increased, and the total membrane fouling and irreversible membrane fouling are decreased at higher pH value and ionic strength. During lysozyme ultrafiltration, the PAN-DMAEAM membrane displays excellent antifouling property in a broad range of pH and ionic strength. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801393z Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Experimental investigation of methane gas production from methane hydrate Type de document : texte imprimé Auteurs : Yue Zhou, Auteur ; Marco J. Castaldi, Auteur ; Tuncel M. Yegulalp, Auteur Année de publication : 2009 Article en page(s) : pp. 3142–3149 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Large-scale reactor vessel Methane gas hydrates Pure methane Deionized water Résumé : A 72 L large-scale reactor vessel was designed, manufactured, and built to investigate the gas production from methane gas hydrates. Methane hydrates were successfully formed within the reactor using pure methane gas and deionized water in a sand matrix with grain sizes between 100 and 500 μm. Hydrate formation tests resulted in formation at 2.2 °C around 600 psi. Mass balance calculations show that 11% of the pore space volume was occupied by hydrate. Measurements and simulations suggest that hydrate was initially formed at the top section of the reactor followed by formation within the lower part of the sediment. A cooling effect was observed during the dissociation via depressurization experiments, caused by the endothermic dissociation reaction. The observed temperature decrease of the system was between 4.0 and 0.8 °C. During the hydrate dissociation tests, a transition regime showing an increased gas production from 9.5 to 13 L/min within a very narrow range of temperature between −1.6 and −1.2 °C and pressure between 310 and 360 psi was recorded. In addition, the temperature was observed to jump to 0 °C in an extremely short time period. The interpretation of this phenomenon is ice formation in the transition regime where hydrate decomposes to gas and ice instead of gas and liquid. This is the first experimental observation of this phenomenon. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801004z
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3142–3149[article] Experimental investigation of methane gas production from methane hydrate [texte imprimé] / Yue Zhou, Auteur ; Marco J. Castaldi, Auteur ; Tuncel M. Yegulalp, Auteur . - 2009 . - pp. 3142–3149.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3142–3149
Mots-clés : Large-scale reactor vessel Methane gas hydrates Pure methane Deionized water Résumé : A 72 L large-scale reactor vessel was designed, manufactured, and built to investigate the gas production from methane gas hydrates. Methane hydrates were successfully formed within the reactor using pure methane gas and deionized water in a sand matrix with grain sizes between 100 and 500 μm. Hydrate formation tests resulted in formation at 2.2 °C around 600 psi. Mass balance calculations show that 11% of the pore space volume was occupied by hydrate. Measurements and simulations suggest that hydrate was initially formed at the top section of the reactor followed by formation within the lower part of the sediment. A cooling effect was observed during the dissociation via depressurization experiments, caused by the endothermic dissociation reaction. The observed temperature decrease of the system was between 4.0 and 0.8 °C. During the hydrate dissociation tests, a transition regime showing an increased gas production from 9.5 to 13 L/min within a very narrow range of temperature between −1.6 and −1.2 °C and pressure between 310 and 360 psi was recorded. In addition, the temperature was observed to jump to 0 °C in an extremely short time period. The interpretation of this phenomenon is ice formation in the transition regime where hydrate decomposes to gas and ice instead of gas and liquid. This is the first experimental observation of this phenomenon. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801004z Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Flame retardancy and thermal degradation of intumescent flame retardant starch-based biodegradable composites Type de document : texte imprimé Auteurs : Kun Wu, Auteur ; Yuan Hu, Auteur ; Lei Song, Auteur Année de publication : 2009 Article en page(s) : pp. 3150–3157 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Biodegradable polyvinyl alcohol Thermoplastic starch Microencapsulated ammonium polyphosphate Microscale combustion calorimeter Résumé : Biodegradable PVA/glycerol-plasticized thermoplastic starch (TPS) and its intumescent flame retardant composites are prepared. Microencapsulated ammonium polyphosphate (MCAPP) was used not only to utilize the charring capacity of the polyhydric compounds but also to restrain the reaction between APP and starch during processing. The flame retardancy and thermal stability of TPS and TPS/MCAPP were characterized by LOI, UL 94, TG, and microscale combustion calorimeter (MCC). TPS/MCAPP composites with only 2 wt % MCAPP can pass V-0 in UL 94 test. However, neat TPS cannot pass any rating. The presence of MCAPP can reduce the total heat release of TPS sharply in MCC test. The thermal degradation and gas products of TPS and TPS/MCAPP were monitored by TG-FTIR and dynamic FTIR. XPS and SEM measurements were utilized to investigate the chemical structure, as well as the surface morphology of the residual char. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801230h
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3150–3157[article] Flame retardancy and thermal degradation of intumescent flame retardant starch-based biodegradable composites [texte imprimé] / Kun Wu, Auteur ; Yuan Hu, Auteur ; Lei Song, Auteur . - 2009 . - pp. 3150–3157.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3150–3157
Mots-clés : Biodegradable polyvinyl alcohol Thermoplastic starch Microencapsulated ammonium polyphosphate Microscale combustion calorimeter Résumé : Biodegradable PVA/glycerol-plasticized thermoplastic starch (TPS) and its intumescent flame retardant composites are prepared. Microencapsulated ammonium polyphosphate (MCAPP) was used not only to utilize the charring capacity of the polyhydric compounds but also to restrain the reaction between APP and starch during processing. The flame retardancy and thermal stability of TPS and TPS/MCAPP were characterized by LOI, UL 94, TG, and microscale combustion calorimeter (MCC). TPS/MCAPP composites with only 2 wt % MCAPP can pass V-0 in UL 94 test. However, neat TPS cannot pass any rating. The presence of MCAPP can reduce the total heat release of TPS sharply in MCC test. The thermal degradation and gas products of TPS and TPS/MCAPP were monitored by TG-FTIR and dynamic FTIR. XPS and SEM measurements were utilized to investigate the chemical structure, as well as the surface morphology of the residual char. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801230h Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Methodology for the screening of signal analysis methods for selective detection of hydrodynamic changes in fluidized bed systems Type de document : texte imprimé Auteurs : Malte Bartels, Auteur ; Bart Vermeer, Auteur ; Peter J. T. Verheijen, Auteur Année de publication : 2009 Article en page(s) : pp. 3158–3166 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Multiphase reactor systems Signal analysis methods Fluidized beds Résumé : Various multiphase reactor systems need to be monitored, e.g., for increasing efficiency or for avoiding catastrophic events such as defluidization, excessive foaming, and flooding. In addition to the commonly available average process variables, pressure fluctuation signals measured at a high sampling frequency have been shown to contain relevant information about the process state. There are many different analysis techniques available that can be used for the data analysis of such signals. However, only sufficiently selective methods will be suitable for an unambiguous detection of a specific change in the process, i.e., the identification of the cause. In this paper, a new methodology is presented for screening many different signal analysis methods in combination with various signal pretreatment methods with the goal to find those combinations that are selective toward a specific process change. This methodology can generally be applied for any specific process change; here we focus on the detection of agglomeration in fluidized beds. The presented methodology is illustrated with some fluidized bed data sets, demonstrating the validity and the benefit of this approach. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012105
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3158–3166[article] Methodology for the screening of signal analysis methods for selective detection of hydrodynamic changes in fluidized bed systems [texte imprimé] / Malte Bartels, Auteur ; Bart Vermeer, Auteur ; Peter J. T. Verheijen, Auteur . - 2009 . - pp. 3158–3166.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3158–3166
Mots-clés : Multiphase reactor systems Signal analysis methods Fluidized beds Résumé : Various multiphase reactor systems need to be monitored, e.g., for increasing efficiency or for avoiding catastrophic events such as defluidization, excessive foaming, and flooding. In addition to the commonly available average process variables, pressure fluctuation signals measured at a high sampling frequency have been shown to contain relevant information about the process state. There are many different analysis techniques available that can be used for the data analysis of such signals. However, only sufficiently selective methods will be suitable for an unambiguous detection of a specific change in the process, i.e., the identification of the cause. In this paper, a new methodology is presented for screening many different signal analysis methods in combination with various signal pretreatment methods with the goal to find those combinations that are selective toward a specific process change. This methodology can generally be applied for any specific process change; here we focus on the detection of agglomeration in fluidized beds. The presented methodology is illustrated with some fluidized bed data sets, demonstrating the validity and the benefit of this approach. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012105 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Dynamic thermodynamics with internal energy, volume, and amount of moles as states : application to liquefied gas tank Type de document : texte imprimé Auteurs : A. R. J. Arendsen, Auteur ; G. F. Versteeg, Auteur Année de publication : 2009 Article en page(s) : pp. 3167–3176 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Dynamic models Redlich-Kwong cubic equation of state Peng-Robinson Résumé : Dynamic models for process design, optimization, and control usually solve a set of heat and/or mass balances as a function of time and/or position in the process. To obtain more robust dynamic models and to minimize the amount of assumptions, internal energy, volume, and amount of moles are chosen as states for the conservation laws of the dynamic model. Temperature, pressure, and the amount and composition of the phases are calculated on the basis of these states at every time step. The Redlich−Kwong and Peng−Robinson (RK-PR) cubic equation of state is used as the thermodynamic model. This study describes the aspects of this approach and additionally gives a wide view over the whole internal energy and volume surface in specific phase diagrams. A complete separation between the dynamic balance model and the thermodynamic model is achieved. Several examples show the application of this approach for a liquefied gas tank and demonstrate that the method is applicable to one and two phases in a wide temperature and pressure range, from liquid and/or gas phase to supercritical conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801273a
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3167–3176[article] Dynamic thermodynamics with internal energy, volume, and amount of moles as states : application to liquefied gas tank [texte imprimé] / A. R. J. Arendsen, Auteur ; G. F. Versteeg, Auteur . - 2009 . - pp. 3167–3176.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3167–3176
Mots-clés : Dynamic models Redlich-Kwong cubic equation of state Peng-Robinson Résumé : Dynamic models for process design, optimization, and control usually solve a set of heat and/or mass balances as a function of time and/or position in the process. To obtain more robust dynamic models and to minimize the amount of assumptions, internal energy, volume, and amount of moles are chosen as states for the conservation laws of the dynamic model. Temperature, pressure, and the amount and composition of the phases are calculated on the basis of these states at every time step. The Redlich−Kwong and Peng−Robinson (RK-PR) cubic equation of state is used as the thermodynamic model. This study describes the aspects of this approach and additionally gives a wide view over the whole internal energy and volume surface in specific phase diagrams. A complete separation between the dynamic balance model and the thermodynamic model is achieved. Several examples show the application of this approach for a liquefied gas tank and demonstrate that the method is applicable to one and two phases in a wide temperature and pressure range, from liquid and/or gas phase to supercritical conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801273a Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Experimental and numerical study of hydrodynamics with heat transfer in a gas-solid fluidized-bed reactor at different particle sizes Type de document : texte imprimé Auteurs : Mahdi Hamzehei, Auteur ; Hassan Rahimzadeh, Auteur Année de publication : 2009 Article en page(s) : pp. 3177–3186 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nonreactive gas-solid fluidized-bed reactor Hydrodynamics Heat transfer Eulerian model Computational fluid dynamics Résumé : In this research, particle size effect on heat transfer and hydrodynamics of a nonreactive gas−solid fluidized-bed reactor were studied experimentally and computationally. A multifluid Eulerian model incorporating the kinetic theory for solid particles was applied to simulate the unsteady-state behavior of this reactor and momentum exchange coefficients were calculated by using the Syamlal−O’Brien drag functions. Simulation results were compared with the experimental data to validate the computational fluid dynamics (CFD) model. Pressure drops and temperature distribution predicted by the simulations at different particle sizes were in good agreement with experimental measurements at superficial gas velocity higher than the minimum fluidization velocity. Simulation results also indicated that small bubbles were produced at the bottom of the bed. These bubbles collided with each other as they moved upward forming larger bubbles. The influence of solid particles size on the gas temperature was studied. The results indicated that, for smaller particle size, due to a higher heat-transfer coefficient between the gas and solid phases, solid-phase temperature increases and mean gas temperature decrease, rapidly. Furthermore, this comparison showed that the model can predict hydrodynamic and heat-transfer behavior of gas−solid fluidized-bed reactors reasonably well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801413q
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3177–3186[article] Experimental and numerical study of hydrodynamics with heat transfer in a gas-solid fluidized-bed reactor at different particle sizes [texte imprimé] / Mahdi Hamzehei, Auteur ; Hassan Rahimzadeh, Auteur . - 2009 . - pp. 3177–3186.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3177–3186
Mots-clés : Nonreactive gas-solid fluidized-bed reactor Hydrodynamics Heat transfer Eulerian model Computational fluid dynamics Résumé : In this research, particle size effect on heat transfer and hydrodynamics of a nonreactive gas−solid fluidized-bed reactor were studied experimentally and computationally. A multifluid Eulerian model incorporating the kinetic theory for solid particles was applied to simulate the unsteady-state behavior of this reactor and momentum exchange coefficients were calculated by using the Syamlal−O’Brien drag functions. Simulation results were compared with the experimental data to validate the computational fluid dynamics (CFD) model. Pressure drops and temperature distribution predicted by the simulations at different particle sizes were in good agreement with experimental measurements at superficial gas velocity higher than the minimum fluidization velocity. Simulation results also indicated that small bubbles were produced at the bottom of the bed. These bubbles collided with each other as they moved upward forming larger bubbles. The influence of solid particles size on the gas temperature was studied. The results indicated that, for smaller particle size, due to a higher heat-transfer coefficient between the gas and solid phases, solid-phase temperature increases and mean gas temperature decrease, rapidly. Furthermore, this comparison showed that the model can predict hydrodynamic and heat-transfer behavior of gas−solid fluidized-bed reactors reasonably well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801413q Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Modeling of an industrial vibrating double-deck screen of a urea granulation circuit Type de document : texte imprimé Auteurs : Ivana M. Cotabarren, Auteur ; José Rossit, Auteur ; Verónica Bucalá, Auteur Année de publication : 2009 Article en page(s) : pp. 3187–3196 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Double-deck screens Urea granulation circuit Screening performance Résumé : A reliable mathematical model to predict the performance of double-deck screens from an industrial urea granulation circuit is provided in this work. The classification in each deck was described by the empirical model reported by Karra [Karra, V. K.Development of a Model for Predicting the Screening Performance of a Vibrating Screen. CIM Bull. 1979, 72, 804.] for the mining industry. The estimation of model parameters was based on industrial data collected from two large-scale double-deck screens belonging to a urea granulation plant. Prior to parameter fitting, data reconciliation of the solid streams was performed, with the aim of determining the unmeasured mass flows and the reconciled particle size distributions that fulfill the material balances for every size class. The results indicate that the fitted model reproduces in an accurate way the performance of the urea granules classification device. Thus, the screen mathematical representation can be used as a module of a plant simulator for many existing urea granulation circuits, which (independently of the technology) have similar industrial vibrating double-deck screens to attain the marketable product granulometry. In addition, the fitted model allows finding the optimal screen apertures to achieve the desired product attributes and recycle ratios. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800968y
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3187–3196[article] Modeling of an industrial vibrating double-deck screen of a urea granulation circuit [texte imprimé] / Ivana M. Cotabarren, Auteur ; José Rossit, Auteur ; Verónica Bucalá, Auteur . - 2009 . - pp. 3187–3196.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3187–3196
Mots-clés : Double-deck screens Urea granulation circuit Screening performance Résumé : A reliable mathematical model to predict the performance of double-deck screens from an industrial urea granulation circuit is provided in this work. The classification in each deck was described by the empirical model reported by Karra [Karra, V. K.Development of a Model for Predicting the Screening Performance of a Vibrating Screen. CIM Bull. 1979, 72, 804.] for the mining industry. The estimation of model parameters was based on industrial data collected from two large-scale double-deck screens belonging to a urea granulation plant. Prior to parameter fitting, data reconciliation of the solid streams was performed, with the aim of determining the unmeasured mass flows and the reconciled particle size distributions that fulfill the material balances for every size class. The results indicate that the fitted model reproduces in an accurate way the performance of the urea granules classification device. Thus, the screen mathematical representation can be used as a module of a plant simulator for many existing urea granulation circuits, which (independently of the technology) have similar industrial vibrating double-deck screens to attain the marketable product granulometry. In addition, the fitted model allows finding the optimal screen apertures to achieve the desired product attributes and recycle ratios. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800968y Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : First-principles predictions of vapor-liquid equilibria for pure and mixture fluids from the combined use of cubic equations of state and solvation calculations Type de document : texte imprimé Auteurs : Chieh-Ming Hsieh, Auteur ; Shiang-Tai Lin, Auteur Année de publication : 2009 Article en page(s) : pp. 3197–3205 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cubic equations of state Phase equilibria Pure fluids Mixture Résumé : A novel approach combining first-principles solvation calculations and cubic equations of state is proposed for the prediction of phase equilibria of both pure and mixture fluids. The temperature and composition dependence of the energy parameter, a(T,x), in the EOS is determined from the attractive contribution to the solvation free energy. The volume parameter, b(x), is estimated to be the mole-fraction-weighted average volume of the molecular solvation cavity. This approach does not require the input of any experimental data (e.g., critical properties or acentric factor) for pure components and does not presume any composition dependence of the energy parameter. The Peng−Robinson EOS combined with a solvation model based on COSMO-SAC calculations, denoted as PR+COSMOSAC, is used to illustrate the applicability of this approach. It is found that the relative error from PR+COSMOSAC is 48% in vapor pressure, 21% in liquid density at the normal boiling point, 10% in critical pressure, 4% in critical temperature, and 5% in critical volume for 1295 pure substances and 27.56% in pressure and 5.18% in vapor-phase composition for 116 binary mixtures in vapor−liquid equilibrium. The errors in binary mixtures can be reduced significantly to 6.24% and 2.25% if experimental vapor pressures are used to correct for any errors in the calculated charging free energies of pure species. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801118a
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3197–3205[article] First-principles predictions of vapor-liquid equilibria for pure and mixture fluids from the combined use of cubic equations of state and solvation calculations [texte imprimé] / Chieh-Ming Hsieh, Auteur ; Shiang-Tai Lin, Auteur . - 2009 . - pp. 3197–3205.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3197–3205
Mots-clés : Cubic equations of state Phase equilibria Pure fluids Mixture Résumé : A novel approach combining first-principles solvation calculations and cubic equations of state is proposed for the prediction of phase equilibria of both pure and mixture fluids. The temperature and composition dependence of the energy parameter, a(T,x), in the EOS is determined from the attractive contribution to the solvation free energy. The volume parameter, b(x), is estimated to be the mole-fraction-weighted average volume of the molecular solvation cavity. This approach does not require the input of any experimental data (e.g., critical properties or acentric factor) for pure components and does not presume any composition dependence of the energy parameter. The Peng−Robinson EOS combined with a solvation model based on COSMO-SAC calculations, denoted as PR+COSMOSAC, is used to illustrate the applicability of this approach. It is found that the relative error from PR+COSMOSAC is 48% in vapor pressure, 21% in liquid density at the normal boiling point, 10% in critical pressure, 4% in critical temperature, and 5% in critical volume for 1295 pure substances and 27.56% in pressure and 5.18% in vapor-phase composition for 116 binary mixtures in vapor−liquid equilibrium. The errors in binary mixtures can be reduced significantly to 6.24% and 2.25% if experimental vapor pressures are used to correct for any errors in the calculated charging free energies of pure species. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801118a Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Effect of electrolytes on CO-water mass transfer Type de document : texte imprimé Auteurs : Haiyang Zhu, Auteur ; Brent H. Shanks, Auteur ; Heindel, Theodore J., Auteur Année de publication : 2009 Article en page(s) : pp. 3206–3210 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Electrolytes CO-water mass transfer Mass-transfer coefficient MCM41 nanoparticles Résumé : The influence of various electrolytes such as sulfate, nitrate, and chloride on CO−water mass transfer was investigated in this study. The results indicate that the enhancement in the CO−water volumetric mass-transfer coefficient ranged from 1.5 to 4.7 times that of a baseline system without electrolytes, depending on electrolyte type and concentration. For those electrolytes with the same anions, copper-containing electrolytes provided stronger enhancement, whereas for those electrolytes with the same cations, sulfate-containing electrolytes showed stronger enhancement. By measuring both the CO−water volumetric mass-transfer coefficient (kLa) and the mass-transfer coefficient (kL), it was found that the electrolytes inhibit gas bubble coalescence. This leads to an increase in the gas−liquid interfacial area, resulting in CO−water mass-transfer enhancement. In contrast, when MCM41 nanoparticles with or without functionalized mercaptopropyl groups were added to water, the mass-transfer coefficient and CO−water interfacial area were both increased. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012924
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3206–3210[article] Effect of electrolytes on CO-water mass transfer [texte imprimé] / Haiyang Zhu, Auteur ; Brent H. Shanks, Auteur ; Heindel, Theodore J., Auteur . - 2009 . - pp. 3206–3210.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3206–3210
Mots-clés : Electrolytes CO-water mass transfer Mass-transfer coefficient MCM41 nanoparticles Résumé : The influence of various electrolytes such as sulfate, nitrate, and chloride on CO−water mass transfer was investigated in this study. The results indicate that the enhancement in the CO−water volumetric mass-transfer coefficient ranged from 1.5 to 4.7 times that of a baseline system without electrolytes, depending on electrolyte type and concentration. For those electrolytes with the same anions, copper-containing electrolytes provided stronger enhancement, whereas for those electrolytes with the same cations, sulfate-containing electrolytes showed stronger enhancement. By measuring both the CO−water volumetric mass-transfer coefficient (kLa) and the mass-transfer coefficient (kL), it was found that the electrolytes inhibit gas bubble coalescence. This leads to an increase in the gas−liquid interfacial area, resulting in CO−water mass-transfer enhancement. In contrast, when MCM41 nanoparticles with or without functionalized mercaptopropyl groups were added to water, the mass-transfer coefficient and CO−water interfacial area were both increased. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012924 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Structural changes of sewage sludge char during fixed-bed pyrolysis Type de document : texte imprimé Auteurs : Javier Ábrego, Auteur ; Jesús Arauzo, Auteur ; José Luis Sanchez, Auteur Année de publication : 2009 Article en page(s) : pp. 3211–3221 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Wastewater treatment plant Sewage sludge Fixed-bed reactor Heating rate Résumé : Undigested dried sewage sludge from a wastewater treatment plant was pyrolyzed at temperatures between 300 and 900 °C, with an additional hold time at the highest temperature. A fixed-bed reactor was used with a heating rate of 20 °C/min under an atmosphere of nitrogen. Pyrolysis product distribution, FTIR, XRD, BET, SEM, and ultimate and proximate analyses were used to gain a better understanding of the structural changes occurring during pyrolysis. At low to medium pyrolysis temperatures, major mass loss occurs, and most of the gaseous and liquid products are released with little porous development, whereas at temperatures between 700 and 900 °C, structural changes seem to be triggered by calcium carbonate decomposition. This leads to a second stage of gas evolution, as CaO promotes gasification of the char in the presence of iron sulfides. The subsequent release of CO runs parallel with an increase in the BET surface area. In addition, the aromatic character of the char increases with temperature, and nanotube-like tubular structures can be detected by SEM. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801366t
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3211–3221[article] Structural changes of sewage sludge char during fixed-bed pyrolysis [texte imprimé] / Javier Ábrego, Auteur ; Jesús Arauzo, Auteur ; José Luis Sanchez, Auteur . - 2009 . - pp. 3211–3221.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3211–3221
Mots-clés : Wastewater treatment plant Sewage sludge Fixed-bed reactor Heating rate Résumé : Undigested dried sewage sludge from a wastewater treatment plant was pyrolyzed at temperatures between 300 and 900 °C, with an additional hold time at the highest temperature. A fixed-bed reactor was used with a heating rate of 20 °C/min under an atmosphere of nitrogen. Pyrolysis product distribution, FTIR, XRD, BET, SEM, and ultimate and proximate analyses were used to gain a better understanding of the structural changes occurring during pyrolysis. At low to medium pyrolysis temperatures, major mass loss occurs, and most of the gaseous and liquid products are released with little porous development, whereas at temperatures between 700 and 900 °C, structural changes seem to be triggered by calcium carbonate decomposition. This leads to a second stage of gas evolution, as CaO promotes gasification of the char in the presence of iron sulfides. The subsequent release of CO runs parallel with an increase in the BET surface area. In addition, the aromatic character of the char increases with temperature, and nanotube-like tubular structures can be detected by SEM. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801366t Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Transient flow behavior of crude oil-alcoflood polymer emulsions Type de document : texte imprimé Auteurs : Mamdouh T. Ghannam, Auteur Année de publication : 2009 Article en page(s) : pp. 3222–3227 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Crude oil Alcoflood polymer emulsions Transient flow behavior Aqueous solutions Résumé : The transient flow behavior of crude oil−Alcoflood polymer emulsions is investigated in this study. A wide range of crude oil, 0−75 vol %, and polymer concentrations, 0−104 ppm, were employed to study the transient flow behavior in terms of viscosity and shear rate. Three different Alcoflood polymers were tested in this investigation, i.e., AF1235, AF1275, and AF1285. A 1 vol % Triton X100 was used as an emulsifying agent to form a stable emulsion of crude oil−Alcoflood polymer. Constant shear rates of 5, 25, and 50 s−1 were applied for 300 s to measure the emulsion viscosity of all examined samples. There was no transient response reported for polymer concentration of ≤1000 ppm. The polymer concentration and shear rate influenced the transient flow behavior of polymer aqueous solution. Aqueous solutions of AF1275 and AF1285 show rheopectic behavior, whereas the aqueous solution of AF1235 provides a slight thixotropic flow. The emulsion viscosity increases significantly with crude oil concentration without modifying the nature of the transient flow behavior and transient period of the polymer aqueous solutions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801388z
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3222–3227[article] Transient flow behavior of crude oil-alcoflood polymer emulsions [texte imprimé] / Mamdouh T. Ghannam, Auteur . - 2009 . - pp. 3222–3227.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3222–3227
Mots-clés : Crude oil Alcoflood polymer emulsions Transient flow behavior Aqueous solutions Résumé : The transient flow behavior of crude oil−Alcoflood polymer emulsions is investigated in this study. A wide range of crude oil, 0−75 vol %, and polymer concentrations, 0−104 ppm, were employed to study the transient flow behavior in terms of viscosity and shear rate. Three different Alcoflood polymers were tested in this investigation, i.e., AF1235, AF1275, and AF1285. A 1 vol % Triton X100 was used as an emulsifying agent to form a stable emulsion of crude oil−Alcoflood polymer. Constant shear rates of 5, 25, and 50 s−1 were applied for 300 s to measure the emulsion viscosity of all examined samples. There was no transient response reported for polymer concentration of ≤1000 ppm. The polymer concentration and shear rate influenced the transient flow behavior of polymer aqueous solution. Aqueous solutions of AF1275 and AF1285 show rheopectic behavior, whereas the aqueous solution of AF1235 provides a slight thixotropic flow. The emulsion viscosity increases significantly with crude oil concentration without modifying the nature of the transient flow behavior and transient period of the polymer aqueous solutions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801388z Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Deactivation by filamentous carbon formation on Co/aluminum phosphate during Fischer-Tropsch synthesis Type de document : texte imprimé Auteurs : Jong Wook Bae, Auteur ; Seung-Moon Kim, Auteur ; Seon-Ju Park, Auteur Année de publication : 2009 Article en page(s) : pp. 3228–3233 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Amorphous aluminum phosphate Cobalt catalysts Fischer-Tropsch synthesis Résumé : Amorphous aluminum phosphate (AlPO4)-supported cobalt catalysts, with and without Ru promotion, were evaluated to study CO hydrogenation activity during Fischer−Tropsch synthesis (FTS). The Ru-promoted catalyst (RuCo/AlPO4) exhibited higher CO conversion and C8+ selectivity than that of the unpromoted catalyst (Co/AlPO4) and Co/Al2O3 catalyst. Interestingly, filamentous carbon was formed, even at the mild FTS reaction conditions (T = 220−240 °C and P = 2.0 MPa), on Co/AlPO4, and it eventually accelerated catalyst deactivation. The presence of an Ru promoter restricted the formation of filamentous carbon and enhanced catalyst stability. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801956t
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3228–3233[article] Deactivation by filamentous carbon formation on Co/aluminum phosphate during Fischer-Tropsch synthesis [texte imprimé] / Jong Wook Bae, Auteur ; Seung-Moon Kim, Auteur ; Seon-Ju Park, Auteur . - 2009 . - pp. 3228–3233.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3228–3233
Mots-clés : Amorphous aluminum phosphate Cobalt catalysts Fischer-Tropsch synthesis Résumé : Amorphous aluminum phosphate (AlPO4)-supported cobalt catalysts, with and without Ru promotion, were evaluated to study CO hydrogenation activity during Fischer−Tropsch synthesis (FTS). The Ru-promoted catalyst (RuCo/AlPO4) exhibited higher CO conversion and C8+ selectivity than that of the unpromoted catalyst (Co/AlPO4) and Co/Al2O3 catalyst. Interestingly, filamentous carbon was formed, even at the mild FTS reaction conditions (T = 220−240 °C and P = 2.0 MPa), on Co/AlPO4, and it eventually accelerated catalyst deactivation. The presence of an Ru promoter restricted the formation of filamentous carbon and enhanced catalyst stability. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801956t Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Development of a scheduling model for polarizer manufacturing logistics Type de document : texte imprimé Auteurs : Kyung Tae Park, Auteur ; Jun-Hyung Ryu, Auteur ; Ho-Kyung Lee, Auteur Année de publication : 2009 Article en page(s) : pp. 3234–3243 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polarizer Liquid crystal displays Linear programming problem Résumé : Polaroid films, or the so-called “polarizer”, is an optical device that transforms natural light into some form of polarized light. When the form of films, it is widely used in thin display equipment, such as liquid crystal displays (LCDs). The polarizer manufacturing industry is under constant competition to lower its price with the continuous price reduction in LCD markets. This paper is particularly concerned with its logistics problems, with a focus on minimizing the cost for purchasing cores used in moving films in the process. The core movement for polarizer logistics is formulated into a linear programming (LP) problem by employing an event-based pull approach that has been proposed earlier by Karimi et al. [Karaimi, I. A.; Sharafali, M.; Mahalingam, H. AIChE J., 2004, 51, 178−197]. Two numerical examples are presented to illustrate the applicability of the proposed model, and some remarks also are made. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8009044
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3234–3243[article] Development of a scheduling model for polarizer manufacturing logistics [texte imprimé] / Kyung Tae Park, Auteur ; Jun-Hyung Ryu, Auteur ; Ho-Kyung Lee, Auteur . - 2009 . - pp. 3234–3243.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3234–3243
Mots-clés : Polarizer Liquid crystal displays Linear programming problem Résumé : Polaroid films, or the so-called “polarizer”, is an optical device that transforms natural light into some form of polarized light. When the form of films, it is widely used in thin display equipment, such as liquid crystal displays (LCDs). The polarizer manufacturing industry is under constant competition to lower its price with the continuous price reduction in LCD markets. This paper is particularly concerned with its logistics problems, with a focus on minimizing the cost for purchasing cores used in moving films in the process. The core movement for polarizer logistics is formulated into a linear programming (LP) problem by employing an event-based pull approach that has been proposed earlier by Karimi et al. [Karaimi, I. A.; Sharafali, M.; Mahalingam, H. AIChE J., 2004, 51, 178−197]. Two numerical examples are presented to illustrate the applicability of the proposed model, and some remarks also are made. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8009044 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Microwave-assisted preparation and hydrazine decomposition properties of nanostructured tungsten carbides on carbon nanotubes Type de document : texte imprimé Auteurs : Changhai Liang, Auteur ; Ling Ding, Auteur ; Aiqin Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 3244–3248 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon nanotubes Microwave organic chemical vapor deposition Fluidized bed reactor Résumé : Nearly monodispersed nanostructured tungsten carbide particles on carbon nanotubes (CNTs) have successfully been synthesized by microwave-assisted metal−organic chemical vapor deposition (MOCVD) at atmospheric pressure in a fluidized bed reactor. The results show that the tungsten carbide particles with 2−5 nm on CNTs can be formed several minutes and the particle sizes increase with the increase of microwave irradiation time. The preoxidation of CNTs is not necessary in the microwave-assisted MOCVD. The resulting materials are active catalysts for hydrazine decomposition and exhibit high selectivity to hydrogen, indicating that nanostructured tungsten carbides on CNTs is an inexpensive and promising alternative to the noble-metal catalysts for hydrazine decomposition. The microwave-assisted MOCVD is of great potential in the controlled synthesis of supported catalytic materials. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801591x
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3244–3248[article] Microwave-assisted preparation and hydrazine decomposition properties of nanostructured tungsten carbides on carbon nanotubes [texte imprimé] / Changhai Liang, Auteur ; Ling Ding, Auteur ; Aiqin Wang, Auteur . - 2009 . - pp. 3244–3248.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3244–3248
Mots-clés : Carbon nanotubes Microwave organic chemical vapor deposition Fluidized bed reactor Résumé : Nearly monodispersed nanostructured tungsten carbide particles on carbon nanotubes (CNTs) have successfully been synthesized by microwave-assisted metal−organic chemical vapor deposition (MOCVD) at atmospheric pressure in a fluidized bed reactor. The results show that the tungsten carbide particles with 2−5 nm on CNTs can be formed several minutes and the particle sizes increase with the increase of microwave irradiation time. The preoxidation of CNTs is not necessary in the microwave-assisted MOCVD. The resulting materials are active catalysts for hydrazine decomposition and exhibit high selectivity to hydrogen, indicating that nanostructured tungsten carbides on CNTs is an inexpensive and promising alternative to the noble-metal catalysts for hydrazine decomposition. The microwave-assisted MOCVD is of great potential in the controlled synthesis of supported catalytic materials. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801591x Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Kinetic analysis of solid-state reactions : a general empirical kinetic model Type de document : texte imprimé Auteurs : Junmeng Cai, Auteur ; Ronghou Liu, Auteur Année de publication : 2009 Article en page(s) : pp. 3249–3253 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Empirical kinetic model Heterogeneities Solid-state-reactions Résumé : In this research note, we presented a general empirical kinetic model that can fit any ideal kinetic model and even deviations produced by heterogeneities in particle shapes. The algebraic expression of the general empirical kinetic model is f(α) = αm(1 − qα)n. The kinetic model can be used for performing the kinetic analysis of experimental data without previous assumptions about the form of the reaction kinetic model. The empirical kinetic model has been evaluated from the theoretical and experimental data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018615
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3249–3253[article] Kinetic analysis of solid-state reactions : a general empirical kinetic model [texte imprimé] / Junmeng Cai, Auteur ; Ronghou Liu, Auteur . - 2009 . - pp. 3249–3253.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3249–3253
Mots-clés : Empirical kinetic model Heterogeneities Solid-state-reactions Résumé : In this research note, we presented a general empirical kinetic model that can fit any ideal kinetic model and even deviations produced by heterogeneities in particle shapes. The algebraic expression of the general empirical kinetic model is f(α) = αm(1 − qα)n. The kinetic model can be used for performing the kinetic analysis of experimental data without previous assumptions about the form of the reaction kinetic model. The empirical kinetic model has been evaluated from the theoretical and experimental data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018615 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Density of ionic liquids using group contribution and artificial neural networks Type de document : texte imprimé Auteurs : José O. Valderrama, Auteur ; Alfonso Reátegui, Auteur ; Roberto E. Rojas, Auteur Année de publication : 2009 Article en page(s) : pp. 3254–3259 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Artificial neural networks Ionic liquids network Résumé : Artificial neural networks and the concept of group contribution are simultaneously used to correlate and predict the density of ionic liquids. Different topologies of a multilayer feed forward artificial neural network were studied and the optimum architecture was determined. Density data from the literature for 103 ionic liquids with 399 data points have been used for training the network. To discriminate among the different substances, the molecular mass and the structure of the molecule, defined by the concepts of the classical group contribution methods, were given as input variables. The capabilities of the designed network were tested by predicting densities for situations not considered during the training process of the network (82 density data points for 24 ionic liquids). The results demonstrate that the chosen network and the group contribution method employed are able to estimate the density of ionic liquids with acceptable accuracy for engineering calculations. The program codes and the necessary input files to calculate the density for other ionic liquids are provided. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801113x
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3254–3259[article] Density of ionic liquids using group contribution and artificial neural networks [texte imprimé] / José O. Valderrama, Auteur ; Alfonso Reátegui, Auteur ; Roberto E. Rojas, Auteur . - 2009 . - pp. 3254–3259.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3254–3259
Mots-clés : Artificial neural networks Ionic liquids network Résumé : Artificial neural networks and the concept of group contribution are simultaneously used to correlate and predict the density of ionic liquids. Different topologies of a multilayer feed forward artificial neural network were studied and the optimum architecture was determined. Density data from the literature for 103 ionic liquids with 399 data points have been used for training the network. To discriminate among the different substances, the molecular mass and the structure of the molecule, defined by the concepts of the classical group contribution methods, were given as input variables. The capabilities of the designed network were tested by predicting densities for situations not considered during the training process of the network (82 density data points for 24 ionic liquids). The results demonstrate that the chosen network and the group contribution method employed are able to estimate the density of ionic liquids with acceptable accuracy for engineering calculations. The program codes and the necessary input files to calculate the density for other ionic liquids are provided. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801113x Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Estimation of the molar heat capacity change on melting of organic compounds Type de document : texte imprimé Auteurs : Min Wu, Auteur ; Samuel Yalkowsky, Auteur Année de publication : 2009 Article en page(s) : p. 3260 Note générale : Chemical engineering Langues : Anglais (eng) Note de contenu : Addition and correction of the same article in volume 48 N° 2 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900184v
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - p. 3260[article] Estimation of the molar heat capacity change on melting of organic compounds [texte imprimé] / Min Wu, Auteur ; Samuel Yalkowsky, Auteur . - 2009 . - p. 3260.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - p. 3260
Note de contenu : Addition and correction of the same article in volume 48 N° 2 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900184v Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
