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Vol. 48 N° 14 - Juillet 2009 [texte imprimé] . - 2009 . - p. 6453-6906 : ill. ; 28 cm. Chemical engineering Langues : Anglais (eng)
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Ajouter le résultat dans votre panierSpray combustor design/performance / Daniel E. Rosner in Industrial & engineering chemistry research, Vol. 48 N° 14 (Juillet 2009)
Titre : Spray combustor design/performance : chemical engineering contributions and the emergence of an “interacting population-balance” perspective Type de document : texte imprimé Auteurs : Daniel E. Rosner, Auteur Année de publication : 2009 Article en page(s) : pp. 6453–6464 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Spray combustors Chemical engineering contributions Résumé : Spray combustors are now widely used in many technologies, spanning commodity chemical synthesis (combustion of molten sulfur en route to sulfuric acid (H2SO4) and phosphorus en route to phosphoric acid (H3PO4), ...), and nanoparticle synthesis (eg., via “spray pyrolysis”), to energy conversion (oil-fired furnaces or boilers) and chemical propulsion (aircraft gas turbines and liquid-propellant rocket motors). While important space, weight, and pollutant constraints inevitably differ from application to application, spray-“fuel”-fed combustors share certain common performance characteristics, and there is a considerable economic incentive to develop rational yet tractable design methods for them. While this intrinsically interdisciplinary subject continues to evolve, here, we briefly review some of the principal contributions to these challenging goals published by chemical engineers since the inception of Industrial and Engineering Chemistry (I&EC). Not surprisingly, the earliest contributions focused on some of the important “unit processes” (e.g., isolated droplet evaporation rates, vapor micromixing rates in spatially homogeneous turbulent flows, and steady vapor-phase laminar diffusion flames). Chemical engineers introduced “continuous mixture theory” to economically address not only phase/chemical equilibria in multicomponent mixtures, but also spatially nonuniform (nonequilibrium) flows. More-recent studies have introduced diffusion “flamelet” concepts for vapor-phase nonpremixed combustion and statistical population-balance concepts to address evolving turbulence characteristics and/or droplet size distributions. Because of the wide range of operative (length and time) scales in the full problem, in the foreseeable future, clever asymptotic methods will continue to be required to capture the essential physicochemical phenomena but still make the associated numerical simulations manageable. In this regard, a fruitful unified perspective is now emerging—one quite natural to chemical engineers. This can perhaps be best described as an interacting “multi-phase, multi-environment” approach—or simply an “interacting multivariable population balance” approach. While much remains to be done, it is hoped that this 2008/2009 perspective, and highly selective “review” of but one class of multiphase chemical reactors, will stimulate further activity along this promising path. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900167h
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6453–6464[article] Spray combustor design/performance : chemical engineering contributions and the emergence of an “interacting population-balance” perspective [texte imprimé] / Daniel E. Rosner, Auteur . - 2009 . - pp. 6453–6464.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6453–6464
Mots-clés : Spray combustors Chemical engineering contributions Résumé : Spray combustors are now widely used in many technologies, spanning commodity chemical synthesis (combustion of molten sulfur en route to sulfuric acid (H2SO4) and phosphorus en route to phosphoric acid (H3PO4), ...), and nanoparticle synthesis (eg., via “spray pyrolysis”), to energy conversion (oil-fired furnaces or boilers) and chemical propulsion (aircraft gas turbines and liquid-propellant rocket motors). While important space, weight, and pollutant constraints inevitably differ from application to application, spray-“fuel”-fed combustors share certain common performance characteristics, and there is a considerable economic incentive to develop rational yet tractable design methods for them. While this intrinsically interdisciplinary subject continues to evolve, here, we briefly review some of the principal contributions to these challenging goals published by chemical engineers since the inception of Industrial and Engineering Chemistry (I&EC). Not surprisingly, the earliest contributions focused on some of the important “unit processes” (e.g., isolated droplet evaporation rates, vapor micromixing rates in spatially homogeneous turbulent flows, and steady vapor-phase laminar diffusion flames). Chemical engineers introduced “continuous mixture theory” to economically address not only phase/chemical equilibria in multicomponent mixtures, but also spatially nonuniform (nonequilibrium) flows. More-recent studies have introduced diffusion “flamelet” concepts for vapor-phase nonpremixed combustion and statistical population-balance concepts to address evolving turbulence characteristics and/or droplet size distributions. Because of the wide range of operative (length and time) scales in the full problem, in the foreseeable future, clever asymptotic methods will continue to be required to capture the essential physicochemical phenomena but still make the associated numerical simulations manageable. In this regard, a fruitful unified perspective is now emerging—one quite natural to chemical engineers. This can perhaps be best described as an interacting “multi-phase, multi-environment” approach—or simply an “interacting multivariable population balance” approach. While much remains to be done, it is hoped that this 2008/2009 perspective, and highly selective “review” of but one class of multiphase chemical reactors, will stimulate further activity along this promising path. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900167h Exemplaires
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Titre : Microstructured reactors for multiphase reactions : state of the art Type de document : texte imprimé Auteurs : Madhvanand N. Kashid, Auteur ; Lioubov Kiwi-Minsker, Auteur Année de publication : 2009 Article en page(s) : pp. 6465–6485 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Microstructured reactors Multiphase reactions Résumé : The manufacture of chemicals in microstructured reactors (MSR) has become recently a new branch of chemical reaction engineering focusing on process intensification and safety. MSR have an equivalent hydraulic diameter up to a few hundreds of micrometers and, therefore, provide high mass- and heat-transfer efficiency increasing the reactor performance drastically, compared to the conventional one. This article provides a comprehensive overview of the state of the art of the MSR applied for multiphase reactions. The reactions are classified based on the number of phases involved: fluid−fluid, fluid−solid, and three phase reactions. In the first part of the review, limitations of conventional reactors are discussed in brief. Furthermore, different types of MSR and their advantages with respect to their conventional counterparts are described. Particular attention is given to the identification of the parameters that control the flow pattern formed in microcapillaries regarding the mass-transfer efficiency. Case studies of various multiphase reactions carried out in MSR are discussed in detail. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017912
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6465–6485[article] Microstructured reactors for multiphase reactions : state of the art [texte imprimé] / Madhvanand N. Kashid, Auteur ; Lioubov Kiwi-Minsker, Auteur . - 2009 . - pp. 6465–6485.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6465–6485
Mots-clés : Microstructured reactors Multiphase reactions Résumé : The manufacture of chemicals in microstructured reactors (MSR) has become recently a new branch of chemical reaction engineering focusing on process intensification and safety. MSR have an equivalent hydraulic diameter up to a few hundreds of micrometers and, therefore, provide high mass- and heat-transfer efficiency increasing the reactor performance drastically, compared to the conventional one. This article provides a comprehensive overview of the state of the art of the MSR applied for multiphase reactions. The reactions are classified based on the number of phases involved: fluid−fluid, fluid−solid, and three phase reactions. In the first part of the review, limitations of conventional reactors are discussed in brief. Furthermore, different types of MSR and their advantages with respect to their conventional counterparts are described. Particular attention is given to the identification of the parameters that control the flow pattern formed in microcapillaries regarding the mass-transfer efficiency. Case studies of various multiphase reactions carried out in MSR are discussed in detail. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017912 Exemplaires
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Titre : Bases and basic materials in industrial and environmental chemistry : a review of commercial processes Type de document : texte imprimé Auteurs : Guido Busca, Auteur Année de publication : 2009 Article en page(s) : pp. 6486–6511 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solid bases Liquid Résumé : The practical application of liquids and solid bases in industrial and environmental processes is reviewed. Liquid bases include water solutions of metal hydroxides such as caustics and potash, amines, phosphorus compounds and other molecular bases, solutions and slurries of alkali and alkaline-earth carbonates, organic solutions of organometallics, and superbases. Solid bases include basic clays, alkaline-earth oxides, alkali metals containing oxides and zeolites, synthetic hydrotalcites, rare-earth oxides and mixed oxides, impregnated carbons, and supported alkali metals. Some health and safety considerations are discussed, together with process features. Conclusions about the future use of bases and the perspective of a more massive application of solid bases are offered. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801878d
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6486–6511[article] Bases and basic materials in industrial and environmental chemistry : a review of commercial processes [texte imprimé] / Guido Busca, Auteur . - 2009 . - pp. 6486–6511.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6486–6511
Mots-clés : Solid bases Liquid Résumé : The practical application of liquids and solid bases in industrial and environmental processes is reviewed. Liquid bases include water solutions of metal hydroxides such as caustics and potash, amines, phosphorus compounds and other molecular bases, solutions and slurries of alkali and alkaline-earth carbonates, organic solutions of organometallics, and superbases. Solid bases include basic clays, alkaline-earth oxides, alkali metals containing oxides and zeolites, synthetic hydrotalcites, rare-earth oxides and mixed oxides, impregnated carbons, and supported alkali metals. Some health and safety considerations are discussed, together with process features. Conclusions about the future use of bases and the perspective of a more massive application of solid bases are offered. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801878d Exemplaires
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Titre : Removal of carmine indigo dye with moringa oleifera seed extract Type de document : texte imprimé Auteurs : J. Beltrán-Heredia, Auteur ; J. Sánchez-Martín, Auteur ; A. Delgado-Regalado, Auteur Année de publication : 2009 Article en page(s) : pp. 6512–6520 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Moringa oleifera Carmine Indigo Résumé : Moringa oleifera has been tested as an active agent in removing various types of anionic dyes. Specially, removal of an indigoid dye, Carmine Indigo, has been tested. The fast kinetics of coagulant action and the high potential of this coagulant agent to treat wastewater from dyestuff has been revealed. Moringa oleifera is fully working in coagulation and flocculation process, and it achieves an average level of removal up to 80%. The pH does not affect the coagulant process, and temperature has a negative influence. By increasing initial dye concentration, lower dye percentage removal is achieved and higher q is presented. Coagulation and flocculation processes can be estimated by the Langmuir and Freundlich models, but the first one gives a better explanation of the coagulation and adsorption behavior (r2 equal to 0.97). Carmine Indigo removal presents an optimum q capacity at 343 mg·L−1 and 11.2 °C. Pilot plant installation gives a similar efficiency for dye removal. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004833
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6512–6520[article] Removal of carmine indigo dye with moringa oleifera seed extract [texte imprimé] / J. Beltrán-Heredia, Auteur ; J. Sánchez-Martín, Auteur ; A. Delgado-Regalado, Auteur . - 2009 . - pp. 6512–6520.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6512–6520
Mots-clés : Moringa oleifera Carmine Indigo Résumé : Moringa oleifera has been tested as an active agent in removing various types of anionic dyes. Specially, removal of an indigoid dye, Carmine Indigo, has been tested. The fast kinetics of coagulant action and the high potential of this coagulant agent to treat wastewater from dyestuff has been revealed. Moringa oleifera is fully working in coagulation and flocculation process, and it achieves an average level of removal up to 80%. The pH does not affect the coagulant process, and temperature has a negative influence. By increasing initial dye concentration, lower dye percentage removal is achieved and higher q is presented. Coagulation and flocculation processes can be estimated by the Langmuir and Freundlich models, but the first one gives a better explanation of the coagulation and adsorption behavior (r2 equal to 0.97). Carmine Indigo removal presents an optimum q capacity at 343 mg·L−1 and 11.2 °C. Pilot plant installation gives a similar efficiency for dye removal. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004833 Exemplaires
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Titre : Synthesis of a water-soluble siloxane copolymer and its application for antimicrobial coatings Type de document : texte imprimé Auteurs : L. Kou, Auteur ; J. Liang, Auteur ; X. Ren, Auteur Année de publication : 2009 Article en page(s) : pp. 6521–6526 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : N-halamine siloxane Quaternary ammonium salt Copolymers 5,5-dimethylhydantoin Trimethylamine Résumé : Copolymers of an N-halamine siloxane and a quaternary ammonium salt siloxane were prepared using 5,5-dimethylhydantoin and trimethylamine as functional groups. The solubility of this siloxane copolymer in water was dramatically improved over that of a hydantoinyl siloxane homopolymer developed earlier. The biocidal activity of cotton swatches coated with the copolymer was evaluated against S. aureus and E. coli O157:H7; the antimicrobial fabric with 0.23%−0.26% chlorine loading could inactivate 107 colony forming units (CFU) of bacteria within 1−5 min of contact. It was observed that a 1 wt % coating bath could provide a coating that could be chlorinated to greater than a 0.20% chlorine loading for a copolymer having a 9:1 ratio of hydantoin to quat moieties. The stability of the oxidative chlorine loading on the cotton swatches was not affected by the presence of the very hydrophilic quat functional group. Use of the copolymer in an antimicrobial coating application will be desirable because no organic solvent is needed for the preparation of a coating bath for textile materials. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017302
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6521–6526[article] Synthesis of a water-soluble siloxane copolymer and its application for antimicrobial coatings [texte imprimé] / L. Kou, Auteur ; J. Liang, Auteur ; X. Ren, Auteur . - 2009 . - pp. 6521–6526.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6521–6526
Mots-clés : N-halamine siloxane Quaternary ammonium salt Copolymers 5,5-dimethylhydantoin Trimethylamine Résumé : Copolymers of an N-halamine siloxane and a quaternary ammonium salt siloxane were prepared using 5,5-dimethylhydantoin and trimethylamine as functional groups. The solubility of this siloxane copolymer in water was dramatically improved over that of a hydantoinyl siloxane homopolymer developed earlier. The biocidal activity of cotton swatches coated with the copolymer was evaluated against S. aureus and E. coli O157:H7; the antimicrobial fabric with 0.23%−0.26% chlorine loading could inactivate 107 colony forming units (CFU) of bacteria within 1−5 min of contact. It was observed that a 1 wt % coating bath could provide a coating that could be chlorinated to greater than a 0.20% chlorine loading for a copolymer having a 9:1 ratio of hydantoin to quat moieties. The stability of the oxidative chlorine loading on the cotton swatches was not affected by the presence of the very hydrophilic quat functional group. Use of the copolymer in an antimicrobial coating application will be desirable because no organic solvent is needed for the preparation of a coating bath for textile materials. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017302 Exemplaires
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Titre : Preparation and properties of novel slow-release NPK agrochemical formulations based on poly(acrylic acid) hydrogels and liquid fertilizers Type de document : texte imprimé Auteurs : Mircea Teodorescu, Auteur ; Anamaria Lungu, Auteur ; Paul O. Stanescu, Auteur Année de publication : 2009 Article en page(s) : pp. 6527–6534 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Slow-release agrochemical formulation Poly(acrylic acid) hydrogels Liquid fertilizers Résumé : New slow-release agrochemical formulations based on cross-linked poly(acrylic acid) hydrogels and liquid fertilizers (LF) were prepared by free radical copolymerization of acrylic acid (AA) and N,N′-methylenebisacrylamide directly in the LF solution. Two NPK liquid fertilizer compositions containing urea and potassium and ammonium phosphates were employed. For comparison, AA was also polymerized under identical conditions in distilled water. The resulting products were characterized by FTIR spectroscopy and scanning electron microscopy, and their water absorption and slow-release properties were determined. The results showed that the swelling degree (SD) of the hydrogels synthesized depended on the overall concentration of reactants (monomers and initiator), LF composition and cross-linking agent, and initiator concentrations. By appropriately combining these reaction parameters, superabsorbent hydrogels with SDs in distilled water ranging from a few hundred to 1000 g of water/g of xerogel can be obtained. The fertilizer-containing hydrogels displayed slow-release properties in still distilled water at room temperature. These slow-release formulations will be tested in the future for their effect on corn and sunflower crops. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900254b
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6527–6534[article] Preparation and properties of novel slow-release NPK agrochemical formulations based on poly(acrylic acid) hydrogels and liquid fertilizers [texte imprimé] / Mircea Teodorescu, Auteur ; Anamaria Lungu, Auteur ; Paul O. Stanescu, Auteur . - 2009 . - pp. 6527–6534.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6527–6534
Mots-clés : Slow-release agrochemical formulation Poly(acrylic acid) hydrogels Liquid fertilizers Résumé : New slow-release agrochemical formulations based on cross-linked poly(acrylic acid) hydrogels and liquid fertilizers (LF) were prepared by free radical copolymerization of acrylic acid (AA) and N,N′-methylenebisacrylamide directly in the LF solution. Two NPK liquid fertilizer compositions containing urea and potassium and ammonium phosphates were employed. For comparison, AA was also polymerized under identical conditions in distilled water. The resulting products were characterized by FTIR spectroscopy and scanning electron microscopy, and their water absorption and slow-release properties were determined. The results showed that the swelling degree (SD) of the hydrogels synthesized depended on the overall concentration of reactants (monomers and initiator), LF composition and cross-linking agent, and initiator concentrations. By appropriately combining these reaction parameters, superabsorbent hydrogels with SDs in distilled water ranging from a few hundred to 1000 g of water/g of xerogel can be obtained. The fertilizer-containing hydrogels displayed slow-release properties in still distilled water at room temperature. These slow-release formulations will be tested in the future for their effect on corn and sunflower crops. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900254b Exemplaires
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Titre : Nondeactivating nanosized ionic catalysts for water-gas shift reaction Type de document : texte imprimé Auteurs : Sudhanshu Sharma, Auteur ; Parag A. Deshpande, Auteur ; M. S. Hegde, Auteur Année de publication : 2009 Article en page(s) : pp. 6535–6543 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Water-gas shift reaction Nanosized catalysts X-ray diffraction photoelectron spectroscopy Résumé : The water−gas shift reaction (WGS) is an important reaction to produce hydrogen. In this study, we have synthesized nanosized catalysts where Pt ion is substituted in the +2 state in TiO2, CeO2, and Ce1−xTixO2−δ. These catalysts have been characterized by X-ray diffraction and X-ray photoelectron spectroscopy (XPS), and it has been shown that Pt2+ in these reducible oxides result in solid solutions like Ti0.99Pt0.01O2−δ, Ce0.83Ti0.15Pt0.02O2−δ, and Ce0.98Pt0.02O2−δ. These catalysts were tested for the water gas shift reaction both in the presence and absence of hydrogen. It was shown that Ti0.99Pt0.01O2−δ exhibited higher catalytic activity than Ce0.83Ti0.15Pt0.02O2−δ and Ce0.98Pt0.02O2−δ. Further, experiments were conducted to determine the deactivation of these catalysts. There was no sintering of Pt and no carbonate formation; therefore, the catalyst did not deactivate even after prolonged reaction. There was no carbonate formation because of the highly acidic nature of Ti4+ ions in the catalysts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900335k
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6535–6543[article] Nondeactivating nanosized ionic catalysts for water-gas shift reaction [texte imprimé] / Sudhanshu Sharma, Auteur ; Parag A. Deshpande, Auteur ; M. S. Hegde, Auteur . - 2009 . - pp. 6535–6543.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6535–6543
Mots-clés : Water-gas shift reaction Nanosized catalysts X-ray diffraction photoelectron spectroscopy Résumé : The water−gas shift reaction (WGS) is an important reaction to produce hydrogen. In this study, we have synthesized nanosized catalysts where Pt ion is substituted in the +2 state in TiO2, CeO2, and Ce1−xTixO2−δ. These catalysts have been characterized by X-ray diffraction and X-ray photoelectron spectroscopy (XPS), and it has been shown that Pt2+ in these reducible oxides result in solid solutions like Ti0.99Pt0.01O2−δ, Ce0.83Ti0.15Pt0.02O2−δ, and Ce0.98Pt0.02O2−δ. These catalysts were tested for the water gas shift reaction both in the presence and absence of hydrogen. It was shown that Ti0.99Pt0.01O2−δ exhibited higher catalytic activity than Ce0.83Ti0.15Pt0.02O2−δ and Ce0.98Pt0.02O2−δ. Further, experiments were conducted to determine the deactivation of these catalysts. There was no sintering of Pt and no carbonate formation; therefore, the catalyst did not deactivate even after prolonged reaction. There was no carbonate formation because of the highly acidic nature of Ti4+ ions in the catalysts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900335k Exemplaires
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Titre : Preparation and characterization of spherical mesoporous CeO2−Al2O3 composites with high thermal stability Type de document : texte imprimé Auteurs : Chao Gao, Auteur ; Lin, Yan-Jun, Auteur ; Yang Li, Auteur Année de publication : 2009 Article en page(s) : pp. 6544–6549 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Spherical mesoporous CeO2− Al2O3 composites Oil-drop sol− gel method Thermal stability Résumé : Spherical mesoporous CeO2−Al2O3 composites containing 2, 5, and 8 wt % ceria have been prepared by an oil-drop sol−gel method. A mixed alumina−ceria hydrosol and hexamethylenetetramine solution were mixed together and added dropwise into a hot oil column where spherical gel particles were formed due to surface tension. The spherical gel particles were then aged, washed, dried, and calcined at 600, 960, or 1200 °C. The resulting materials were characterized by X-ray diffraction, nitrogen adsorption−desorption, and temperature-programmed desorption of ammonia. At 1200 °C sintering of pure alumina is severe, whereas the presence of ceria prevents the alumina from sintering, so that the CeO2−Al2O3 composites have much larger BET surface areas than pure alumina. Addition of ceria also leads to an increase in the number of strong acid sites and the total number of acid sites compared with pure alumina. These results show that the spherical mesoporous CeO2−Al2O3 composites prepared in this way are suitable supports for high temperature catalytic processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9000508
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6544–6549[article] Preparation and characterization of spherical mesoporous CeO2−Al2O3 composites with high thermal stability [texte imprimé] / Chao Gao, Auteur ; Lin, Yan-Jun, Auteur ; Yang Li, Auteur . - 2009 . - pp. 6544–6549.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6544–6549
Mots-clés : Spherical mesoporous CeO2− Al2O3 composites Oil-drop sol− gel method Thermal stability Résumé : Spherical mesoporous CeO2−Al2O3 composites containing 2, 5, and 8 wt % ceria have been prepared by an oil-drop sol−gel method. A mixed alumina−ceria hydrosol and hexamethylenetetramine solution were mixed together and added dropwise into a hot oil column where spherical gel particles were formed due to surface tension. The spherical gel particles were then aged, washed, dried, and calcined at 600, 960, or 1200 °C. The resulting materials were characterized by X-ray diffraction, nitrogen adsorption−desorption, and temperature-programmed desorption of ammonia. At 1200 °C sintering of pure alumina is severe, whereas the presence of ceria prevents the alumina from sintering, so that the CeO2−Al2O3 composites have much larger BET surface areas than pure alumina. Addition of ceria also leads to an increase in the number of strong acid sites and the total number of acid sites compared with pure alumina. These results show that the spherical mesoporous CeO2−Al2O3 composites prepared in this way are suitable supports for high temperature catalytic processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9000508 Exemplaires
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Titre : One-step “green” synthesis of Pd nanoparticles of controlled size and their catalytic activity for trichloroethene hydrodechlorination Type de document : texte imprimé Auteurs : Feng He, Auteur ; Juncheng Liu, Auteur ; Christopher B. Roberts, Auteur Année de publication : 2009 Article en page(s) : pp. 6550–6557 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pd nanoparticles Controlled size One-step “green” approach Résumé : We present here a straightforward, one-step “green” approach for preparing Pd nanoparticles of controlled size and size distribution. The new catalysts were synthesized using a low-cost, biocompatible cellulose, sodium carboxymethyl cellulose (CMC), as a stabilizer and ascorbic acid as a reducing agent at temperatures ranging from 22 to 95 °C. The mean size and polydispersivity (expressed as standard deviation, SD) of the Pd nanoparticles was exponentially reduced by increasing the preparation temperature from 22 to 95 °C. At 95 °C, nearly monodisperse Pd nanoparticles were obtained with a mean diameter of 3.6 nm (SD = 0.5 nm). The Pd nanoparticles exhibited high catalytic reactivity when tested for hydrodechlorination of trichloroethene in the presence of H2. The observed pseudofirst-order reaction rate constant, kobs, was up to 692 L g−1 min−1, which is comparable to the Pd nanoparticles synthesized per the conventional borohydride reduction method. This new approach not only offers a simple way to manipulate particle size and size distribution but also eliminates the need of borohydride, which is much more costly and less environmentally friendly than the ascorbic acid used in this work. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801962f
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6550–6557[article] One-step “green” synthesis of Pd nanoparticles of controlled size and their catalytic activity for trichloroethene hydrodechlorination [texte imprimé] / Feng He, Auteur ; Juncheng Liu, Auteur ; Christopher B. Roberts, Auteur . - 2009 . - pp. 6550–6557.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6550–6557
Mots-clés : Pd nanoparticles Controlled size One-step “green” approach Résumé : We present here a straightforward, one-step “green” approach for preparing Pd nanoparticles of controlled size and size distribution. The new catalysts were synthesized using a low-cost, biocompatible cellulose, sodium carboxymethyl cellulose (CMC), as a stabilizer and ascorbic acid as a reducing agent at temperatures ranging from 22 to 95 °C. The mean size and polydispersivity (expressed as standard deviation, SD) of the Pd nanoparticles was exponentially reduced by increasing the preparation temperature from 22 to 95 °C. At 95 °C, nearly monodisperse Pd nanoparticles were obtained with a mean diameter of 3.6 nm (SD = 0.5 nm). The Pd nanoparticles exhibited high catalytic reactivity when tested for hydrodechlorination of trichloroethene in the presence of H2. The observed pseudofirst-order reaction rate constant, kobs, was up to 692 L g−1 min−1, which is comparable to the Pd nanoparticles synthesized per the conventional borohydride reduction method. This new approach not only offers a simple way to manipulate particle size and size distribution but also eliminates the need of borohydride, which is much more costly and less environmentally friendly than the ascorbic acid used in this work. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801962f Exemplaires
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Titre : Backmixing reduction of a bubble column by interruption of the global liquid circulation Type de document : texte imprimé Auteurs : Yang Wu, Auteur ; Zhen-Min Cheng, Auteur ; Zi-Bin Huang, Auteur Année de publication : 2009 Article en page(s) : pp. 6558–6563 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Backmixing reduction Bubble column Lliquid circulation route Résumé : The strong backmixing of the liquid phase which is prevalent in a bubble column should be ascribed to its global circulation which is upward in the central region while downward near the wall on the reactor scale. To suppress the backmixing behavior, interruption of the liquid circulation route should be effective. To verify this presumption, an investigation was conducted with a bubble column 550 cm in height and 50 cm in diameter, which was equipped with four channels of the same size installed at different heights so as to cut the downward motion of the liquid and therefore prevent the global circulation the liquid. It shows that although the radial velocity distribution of the liquid remains parabolic in the short column constituted by two neighbor channels, the velocity profile tends to be flat in the upward direction as the channel is approached. The residence time distribution analysis shows that the backmixing of liquid could be reduced by 60% when four channels 12 cm in diameter were applied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900128j
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6558–6563[article] Backmixing reduction of a bubble column by interruption of the global liquid circulation [texte imprimé] / Yang Wu, Auteur ; Zhen-Min Cheng, Auteur ; Zi-Bin Huang, Auteur . - 2009 . - pp. 6558–6563.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6558–6563
Mots-clés : Backmixing reduction Bubble column Lliquid circulation route Résumé : The strong backmixing of the liquid phase which is prevalent in a bubble column should be ascribed to its global circulation which is upward in the central region while downward near the wall on the reactor scale. To suppress the backmixing behavior, interruption of the liquid circulation route should be effective. To verify this presumption, an investigation was conducted with a bubble column 550 cm in height and 50 cm in diameter, which was equipped with four channels of the same size installed at different heights so as to cut the downward motion of the liquid and therefore prevent the global circulation the liquid. It shows that although the radial velocity distribution of the liquid remains parabolic in the short column constituted by two neighbor channels, the velocity profile tends to be flat in the upward direction as the channel is approached. The residence time distribution analysis shows that the backmixing of liquid could be reduced by 60% when four channels 12 cm in diameter were applied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900128j Exemplaires
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Titre : Mechanisms and kinetics of methane thermal conversion in a syngas Type de document : texte imprimé Auteurs : Anthony Dufour, Auteur ; Sylvie Valin, Auteur ; Pierre Castelli, Auteur Année de publication : 2009 Article en page(s) : pp. 6564–6572 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Biomass gasification Methane Reconstituted syngas Résumé : In order to optimize H2 and CO production from biomass gasification, the thermal decomposition of methane in a reconstituted syngas was investigated in a tubular reactor at 130 kPa, for a gas residence time of 2 s and as a function of temperature (1000−1400 °C), CH4 (7, 14%), H2 (16, 32%), and H2O (15, 25, 30%) initial mole fractions. H2 showed an inhibiting effect on CH4 conversion whereas H2O had few effects. Three detailed elementary mechanisms were used to predict the methane conversion rate and to identify the key reaction pathways. Flow rate analyses showed that carbon oxidation occurs mainly by addition of OH radicals on C2 compounds. OH radicals are mainly produced by CO2 (CO2 + H = CO + OH). The inhibiting role of H2 on CH4 conversion is explained by a competition between the OH radicals consumption channels (H2 + OH = H2O + H). The competition between thermal conversion of methane and reforming of unsaturated C2 explains the soot formation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900343b
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6564–6572[article] Mechanisms and kinetics of methane thermal conversion in a syngas [texte imprimé] / Anthony Dufour, Auteur ; Sylvie Valin, Auteur ; Pierre Castelli, Auteur . - 2009 . - pp. 6564–6572.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6564–6572
Mots-clés : Biomass gasification Methane Reconstituted syngas Résumé : In order to optimize H2 and CO production from biomass gasification, the thermal decomposition of methane in a reconstituted syngas was investigated in a tubular reactor at 130 kPa, for a gas residence time of 2 s and as a function of temperature (1000−1400 °C), CH4 (7, 14%), H2 (16, 32%), and H2O (15, 25, 30%) initial mole fractions. H2 showed an inhibiting effect on CH4 conversion whereas H2O had few effects. Three detailed elementary mechanisms were used to predict the methane conversion rate and to identify the key reaction pathways. Flow rate analyses showed that carbon oxidation occurs mainly by addition of OH radicals on C2 compounds. OH radicals are mainly produced by CO2 (CO2 + H = CO + OH). The inhibiting role of H2 on CH4 conversion is explained by a competition between the OH radicals consumption channels (H2 + OH = H2O + H). The competition between thermal conversion of methane and reforming of unsaturated C2 explains the soot formation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900343b Exemplaires
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Titre : Pt-Sn/MgAl2O4 as n-butane dehydrogenation catalyst in a two-zone fluidized-bed reactor Type de document : texte imprimé Auteurs : M. P. Lobera, Auteur ; C. Téllez, Auteur ; J. Herguido, Auteur Année de publication : 2009 Article en page(s) : pp. 6573–6578 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : n-Butane dehydrogenation Pt-Sn/MgAl2O4 catalyst Two-zone fluidized-bed reactor Résumé : n-Butane dehydrogenation over a Pt-Sn/MgAl2O4 catalyst has been carried out in a two-zone fluidized-bed reactor (TZFBR), where oxidation and reduction of this catalyst occurs in the same vessel but in separate zones. This allows working in a continuous mode with in situ catalyst regeneration, unlike traditional systems that require two different reactors or a single reactor with periodic operation. The effect of the main TZFBR operating variables was studied and its performance compared with that of a conventional fluidized-bed reactor loaded with the same catalyst and with other reactor + catalyst systems. Compared with a previous work in a similar reactor with another catalyst, the selectivity is improved because of the lower tendency to coke formation of the Pt-Sn/MgAl2O4 catalyst. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900381p
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6573–6578[article] Pt-Sn/MgAl2O4 as n-butane dehydrogenation catalyst in a two-zone fluidized-bed reactor [texte imprimé] / M. P. Lobera, Auteur ; C. Téllez, Auteur ; J. Herguido, Auteur . - 2009 . - pp. 6573–6578.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6573–6578
Mots-clés : n-Butane dehydrogenation Pt-Sn/MgAl2O4 catalyst Two-zone fluidized-bed reactor Résumé : n-Butane dehydrogenation over a Pt-Sn/MgAl2O4 catalyst has been carried out in a two-zone fluidized-bed reactor (TZFBR), where oxidation and reduction of this catalyst occurs in the same vessel but in separate zones. This allows working in a continuous mode with in situ catalyst regeneration, unlike traditional systems that require two different reactors or a single reactor with periodic operation. The effect of the main TZFBR operating variables was studied and its performance compared with that of a conventional fluidized-bed reactor loaded with the same catalyst and with other reactor + catalyst systems. Compared with a previous work in a similar reactor with another catalyst, the selectivity is improved because of the lower tendency to coke formation of the Pt-Sn/MgAl2O4 catalyst. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900381p Exemplaires
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Titre : Re-evaluation and modeling of a commercial diesel oxidation catalyst Type de document : texte imprimé Auteurs : Young-Deuk Kim, Auteur Année de publication : 2009 Article en page(s) : pp. 6579–6590 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Diesel oxidation catalyst Turbocharged diesel engine Angine-dynamometer system Résumé : A modeling approach to predict the performance of a commercial diesel oxidation catalyst (DOC) under actual vehicle operating conditions is presented in this study. Prior to completing this prediction, the performance characteristics of DOCs, as previously published, are examined to validate the currently developed in-house computational code. Steady-state experiments with DOCs mounted on a light-duty four-cylinder 2.0-L turbocharged diesel engine then are performed, using an engine-dynamometer system to calibrate the kinetic parameters such as activation energies and pre-exponential factors of heterogeneous reactions. The reaction rates for CO, HC, and NO oxidations over a fresh Pt/Al2O3 catalyst are determined in conjunction with a transient one-dimensional (1D) heterogeneous plug-flow reactor (PFR) model with diesel exhaust gas temperatures in the range of 150−450 °C and space velocities in the range of (1−5) × 105 h−1. To determine the kinetic parameters that best fit the experimental data, a two-step optimization procedure is introduced. First, the results from the conjugated gradient method (CGM) with individual temperatures for each species are plotted in an Arrhenius plot to generate proper intermediate guesses from initial guesses for all pre-exponential factors and activation energies. Here, the kinetic parameters for CO oxidation are calibrated to provide the best fits to the lowest temperature data with fixed initial activation energy without implementing the first-step tuning procedure, because of complete conversion of CO over the temperature range of 150−450 °C. Kinetic parameters for all species then are obtained simultaneously by searching the best fits to experimental data using the CGM from the intermediate guesses for all species. The prediction accuracy of the model through first step optimization procedure against experimental results is slightly improved by performing a second-step optimization procedure, and the simulation results of optimized kinetic parameters are compared to the experimental data obtained at both 1500 and 2000 rpm. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801509j
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6579–6590[article] Re-evaluation and modeling of a commercial diesel oxidation catalyst [texte imprimé] / Young-Deuk Kim, Auteur . - 2009 . - pp. 6579–6590.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6579–6590
Mots-clés : Diesel oxidation catalyst Turbocharged diesel engine Angine-dynamometer system Résumé : A modeling approach to predict the performance of a commercial diesel oxidation catalyst (DOC) under actual vehicle operating conditions is presented in this study. Prior to completing this prediction, the performance characteristics of DOCs, as previously published, are examined to validate the currently developed in-house computational code. Steady-state experiments with DOCs mounted on a light-duty four-cylinder 2.0-L turbocharged diesel engine then are performed, using an engine-dynamometer system to calibrate the kinetic parameters such as activation energies and pre-exponential factors of heterogeneous reactions. The reaction rates for CO, HC, and NO oxidations over a fresh Pt/Al2O3 catalyst are determined in conjunction with a transient one-dimensional (1D) heterogeneous plug-flow reactor (PFR) model with diesel exhaust gas temperatures in the range of 150−450 °C and space velocities in the range of (1−5) × 105 h−1. To determine the kinetic parameters that best fit the experimental data, a two-step optimization procedure is introduced. First, the results from the conjugated gradient method (CGM) with individual temperatures for each species are plotted in an Arrhenius plot to generate proper intermediate guesses from initial guesses for all pre-exponential factors and activation energies. Here, the kinetic parameters for CO oxidation are calibrated to provide the best fits to the lowest temperature data with fixed initial activation energy without implementing the first-step tuning procedure, because of complete conversion of CO over the temperature range of 150−450 °C. Kinetic parameters for all species then are obtained simultaneously by searching the best fits to experimental data using the CGM from the intermediate guesses for all species. The prediction accuracy of the model through first step optimization procedure against experimental results is slightly improved by performing a second-step optimization procedure, and the simulation results of optimized kinetic parameters are compared to the experimental data obtained at both 1500 and 2000 rpm. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801509j Exemplaires
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Titre : Kinetics of polycarbonate methanolysis by a consecutive reaction model Type de document : texte imprimé Auteurs : Dongpil Kim, Auteur ; Bo-kyung Kim, Auteur ; Youngmin Cho, Auteur Année de publication : 2009 Article en page(s) : pp. 6591–6599 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polycarbonate particles Methanol Bisphenol A Dimethyl carbonate Résumé : Polycarbonate (PC) particles were depolymerized by methanol to recover bisphenol A (BPA) and dimethyl carbonate (DMC) in the range of 160−220 °C without using a catalyst or toxic solvents. The effect of operation variables such as methanol/polycarbonate (MeOH/PC) weight ratio and the ethylene glycol/methanol (EG/MeOH) cosolvent system on reaction yields was examined to get better monomer yields. The product yield increased as the amount of methanol increased until the MeOH/PC molar ratio 71. However, the EG/MeOH cosolvent system did not improve the depolymerization yield. A novel kinetic model was proposed to explain the depolymerization reaction, which consists of a series of reactions: random scission from high molecular weight PC to its solid oligomer, dissolution from the solid oligomer to liquid oligomer, and homogeneous degradation from the oligomer to its monomers, BPA and DMC. Continuous distribution kinetics and shrinking core model were employed to describe random scission of PC and dissolution of PC solid particle in methanol solution. The predicted values by the proposed model were shown in good agreement with the experimental ones. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801893v
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6591–6599[article] Kinetics of polycarbonate methanolysis by a consecutive reaction model [texte imprimé] / Dongpil Kim, Auteur ; Bo-kyung Kim, Auteur ; Youngmin Cho, Auteur . - 2009 . - pp. 6591–6599.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6591–6599
Mots-clés : Polycarbonate particles Methanol Bisphenol A Dimethyl carbonate Résumé : Polycarbonate (PC) particles were depolymerized by methanol to recover bisphenol A (BPA) and dimethyl carbonate (DMC) in the range of 160−220 °C without using a catalyst or toxic solvents. The effect of operation variables such as methanol/polycarbonate (MeOH/PC) weight ratio and the ethylene glycol/methanol (EG/MeOH) cosolvent system on reaction yields was examined to get better monomer yields. The product yield increased as the amount of methanol increased until the MeOH/PC molar ratio 71. However, the EG/MeOH cosolvent system did not improve the depolymerization yield. A novel kinetic model was proposed to explain the depolymerization reaction, which consists of a series of reactions: random scission from high molecular weight PC to its solid oligomer, dissolution from the solid oligomer to liquid oligomer, and homogeneous degradation from the oligomer to its monomers, BPA and DMC. Continuous distribution kinetics and shrinking core model were employed to describe random scission of PC and dissolution of PC solid particle in methanol solution. The predicted values by the proposed model were shown in good agreement with the experimental ones. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801893v Exemplaires
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Titre : Effect of catalyst morphology on the performance of submerged nanocatalysis/membrane filtration system Type de document : texte imprimé Auteurs : Rizhi Chen, Auteur ; Yan Du, Auteur ; Qinqin Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 6600–6607 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nanocatalysis/membrane filtration system Tubular ceramic membrane Liquid-phase hydrogenation X-ray diffractometry Résumé : Coupling systems of nanocatalysis and membrane filtration (nanocatalysis/MF) are features of convenience for the in situ separation of nanocatalysts from the reaction mixture. In this work, a submerged nanocatalysis/MF system with a tubular ceramic membrane as the separation unit was developed for the liquid-phase hydrogenation of p-nitrophenol to p-aminophenol over nickel nanoparticles with various particle morphologies obtained by hydrogen annealing at different temperatures. We extensively characterized the nickel nanoparticles using X-ray diffractometry (XRD), nitrogen adsorption, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), and we determined that the annealing temperature significantly influenced the particle size, specific surface area, and crystalline morphology of the nickel nanoparticles. We then evaluated the catalytic performance and separation efficiency of the submerged nanocatalysis/MF system. The nickel nanoparticles annealed at different temperature showed remarkably different catalytic activity, because of their specific structural properties. There was an unexpected nonlinear relationship between the nickel particle size and the flux, which was due to the changed nature of the cake layer formed on the membrane surface and a pore blocking effect. The results from both aspects of catalysis and separation performance indicated that the nickel nanoparticles annealed at 100 °C displayed a best balanced catalytic performance and separation efficiency for the submerged nanocatalysis/MF system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900033m
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6600–6607[article] Effect of catalyst morphology on the performance of submerged nanocatalysis/membrane filtration system [texte imprimé] / Rizhi Chen, Auteur ; Yan Du, Auteur ; Qinqin Wang, Auteur . - 2009 . - pp. 6600–6607.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6600–6607
Mots-clés : Nanocatalysis/membrane filtration system Tubular ceramic membrane Liquid-phase hydrogenation X-ray diffractometry Résumé : Coupling systems of nanocatalysis and membrane filtration (nanocatalysis/MF) are features of convenience for the in situ separation of nanocatalysts from the reaction mixture. In this work, a submerged nanocatalysis/MF system with a tubular ceramic membrane as the separation unit was developed for the liquid-phase hydrogenation of p-nitrophenol to p-aminophenol over nickel nanoparticles with various particle morphologies obtained by hydrogen annealing at different temperatures. We extensively characterized the nickel nanoparticles using X-ray diffractometry (XRD), nitrogen adsorption, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), and we determined that the annealing temperature significantly influenced the particle size, specific surface area, and crystalline morphology of the nickel nanoparticles. We then evaluated the catalytic performance and separation efficiency of the submerged nanocatalysis/MF system. The nickel nanoparticles annealed at different temperature showed remarkably different catalytic activity, because of their specific structural properties. There was an unexpected nonlinear relationship between the nickel particle size and the flux, which was due to the changed nature of the cake layer formed on the membrane surface and a pore blocking effect. The results from both aspects of catalysis and separation performance indicated that the nickel nanoparticles annealed at 100 °C displayed a best balanced catalytic performance and separation efficiency for the submerged nanocatalysis/MF system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900033m Exemplaires
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Titre : Analytical solution for discrete lumped kinetic equations in hydrocracking of heavier petroleum fractions Type de document : texte imprimé Auteurs : P. C. Krishna, Auteur ; P. Balasubramanian, Auteur Année de publication : 2009 Article en page(s) : pp. 6608–6617 Note générale : chemical engineering Langues : Anglais (eng) Mots-clés : Stoichiometry Discrete lumped kinetic mode Carbon number basis Résumé : This paper provides a general analytical solution for the full stoichiometry based discrete lumped kinetic model. The reduced stoichiometry and carbon number basis are the subset of the full stoichiometry model. The exponential form of stoichiometric kernels is considered to study the product distribution for the full and reduced stoichiometry models. Here, full stoichiometry favors for the formation of heavier lumps, while the reduced stoichiometry favors for the formation of lighter lumps. The exact solution for the discrete lumped model is validated with the experimental data cited in the literature. The model validation reveals that the full stoichiometry is the best performing model for hydrocracking of heavier petroleum fractions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900178m
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6608–6617[article] Analytical solution for discrete lumped kinetic equations in hydrocracking of heavier petroleum fractions [texte imprimé] / P. C. Krishna, Auteur ; P. Balasubramanian, Auteur . - 2009 . - pp. 6608–6617.
chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6608–6617
Mots-clés : Stoichiometry Discrete lumped kinetic mode Carbon number basis Résumé : This paper provides a general analytical solution for the full stoichiometry based discrete lumped kinetic model. The reduced stoichiometry and carbon number basis are the subset of the full stoichiometry model. The exponential form of stoichiometric kernels is considered to study the product distribution for the full and reduced stoichiometry models. Here, full stoichiometry favors for the formation of heavier lumps, while the reduced stoichiometry favors for the formation of lighter lumps. The exact solution for the discrete lumped model is validated with the experimental data cited in the literature. The model validation reveals that the full stoichiometry is the best performing model for hydrocracking of heavier petroleum fractions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900178m Exemplaires
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Titre : Processing of acacia dealbata in aqueous media : first step of a wood biorefinery Type de document : texte imprimé Auteurs : Remedios Yáñez, Auteur ; Aloia Romaní, Auteur ; Gil Garrote, Auteur Année de publication : 2009 Article en page(s) : pp. 6618–6626 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Acacia dealbata Aqueous media Autohydrolysis Stability Résumé : In order to assess the suitability of autohydrolysis as a first biorefinery stage, Acacia dealbata wood samples were heated in aqueous media to a range of 170−240 °C. Under selected operational conditions (maximum temperature, 215 °C), 70% xylan was converted into xylooligosaccharides, whereas cellulose and lignin remained in solid phase with little alteration. The spent solids from treatments contained 65% cellulose (measured as glucan), 8% hemicelluloses, and 27% lignin. Kinetic models describing the Acacia dealbata wood solubilization as well as the autohydrolysis of the polysaccharide fractions (glucan, xylan, and arabinosyl and acetyl substituents of hemicelluloses) were developed. All the models considered sequential, first-order, pseudohomogeneous kinetics, with Arrhenius type dependence on temperature, and provided a satisfactory interpretation of experimental data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900233x
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6618–6626[article] Processing of acacia dealbata in aqueous media : first step of a wood biorefinery [texte imprimé] / Remedios Yáñez, Auteur ; Aloia Romaní, Auteur ; Gil Garrote, Auteur . - 2009 . - pp. 6618–6626.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6618–6626
Mots-clés : Acacia dealbata Aqueous media Autohydrolysis Stability Résumé : In order to assess the suitability of autohydrolysis as a first biorefinery stage, Acacia dealbata wood samples were heated in aqueous media to a range of 170−240 °C. Under selected operational conditions (maximum temperature, 215 °C), 70% xylan was converted into xylooligosaccharides, whereas cellulose and lignin remained in solid phase with little alteration. The spent solids from treatments contained 65% cellulose (measured as glucan), 8% hemicelluloses, and 27% lignin. Kinetic models describing the Acacia dealbata wood solubilization as well as the autohydrolysis of the polysaccharide fractions (glucan, xylan, and arabinosyl and acetyl substituents of hemicelluloses) were developed. All the models considered sequential, first-order, pseudohomogeneous kinetics, with Arrhenius type dependence on temperature, and provided a satisfactory interpretation of experimental data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900233x Exemplaires
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Titre : SO2 retention by CaO-based sorbent spent in CO2 looping cycles Type de document : texte imprimé Auteurs : Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur ; Davor Loncarevic, Auteur Année de publication : 2009 Article en page(s) : pp. 6627–6632 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CaO-based looping cycles Cyclical carbonation CO2 stream suitable SO2 capture Résumé : CaO-based looping cycles are promising processes for CO2 capture from both syngas and flue gas. The technology is based on cyclical carbonation of CaO and regeneration of CaCO3 in a dual fluidized-bed reactor to produce a pure CO2 stream suitable for sequestration. The main limitation of natural sorbents is the loss of carrying capacity with increasing number of reaction cycles, resulting in the need for extra sorbent, and subsequent spent sorbent waste. Use of spent sorbent from CO2 looping cycles for SO2 capture is investigated in this study. Three limestones were investigated: Kelly Rock (Canada), La Blanca (Spain), and Katowice (Poland, Upper Silesia). Carbonation/calcination cycles were performed in a tube furnace with both the original limestones and samples thermally pretreated for different times (i.e., sintered). The spent sorbent samples were sulfated in a thermogravimetric analyzer (TGA). The changes in the resulting sorbent pore structure were then investigated using mercury porosimetry. It has been shown that the sulfation rates of both thermally pretreated and spent sorbent samples are lower in comparison with those of the original samples. However, final conversions of both spent and pretreated sorbents after longer sulfation time were comparable or higher than those observed for the original sorbents under comparable conditions. Maximum sulfation levels strongly depend on sorbent porosity and pore surface area. The shrinkage of sorbent particles during calcination/carbonation cycling resulted in a loss of sorbent porosity on the order of ≤48%, which corresponds to maximum sulfation levels of ∼55% for spent Kelly Rock and Katowice. This is ∼10% higher than that seen with the original samples after 15 h of sulfation. By contrast, La Blanca limestone had more pronounced particle shrinkage during pretreatment and cycling, leading to porosities lower than 35%, which resulted in sulfation conversion of spent samples En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002365
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6627–6632[article] SO2 retention by CaO-based sorbent spent in CO2 looping cycles [texte imprimé] / Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur ; Davor Loncarevic, Auteur . - 2009 . - pp. 6627–6632.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6627–6632
Mots-clés : CaO-based looping cycles Cyclical carbonation CO2 stream suitable SO2 capture Résumé : CaO-based looping cycles are promising processes for CO2 capture from both syngas and flue gas. The technology is based on cyclical carbonation of CaO and regeneration of CaCO3 in a dual fluidized-bed reactor to produce a pure CO2 stream suitable for sequestration. The main limitation of natural sorbents is the loss of carrying capacity with increasing number of reaction cycles, resulting in the need for extra sorbent, and subsequent spent sorbent waste. Use of spent sorbent from CO2 looping cycles for SO2 capture is investigated in this study. Three limestones were investigated: Kelly Rock (Canada), La Blanca (Spain), and Katowice (Poland, Upper Silesia). Carbonation/calcination cycles were performed in a tube furnace with both the original limestones and samples thermally pretreated for different times (i.e., sintered). The spent sorbent samples were sulfated in a thermogravimetric analyzer (TGA). The changes in the resulting sorbent pore structure were then investigated using mercury porosimetry. It has been shown that the sulfation rates of both thermally pretreated and spent sorbent samples are lower in comparison with those of the original samples. However, final conversions of both spent and pretreated sorbents after longer sulfation time were comparable or higher than those observed for the original sorbents under comparable conditions. Maximum sulfation levels strongly depend on sorbent porosity and pore surface area. The shrinkage of sorbent particles during calcination/carbonation cycling resulted in a loss of sorbent porosity on the order of ≤48%, which corresponds to maximum sulfation levels of ∼55% for spent Kelly Rock and Katowice. This is ∼10% higher than that seen with the original samples after 15 h of sulfation. By contrast, La Blanca limestone had more pronounced particle shrinkage during pretreatment and cycling, leading to porosities lower than 35%, which resulted in sulfation conversion of spent samples En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002365 Exemplaires
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Titre : Effects of branching on the pressure-volume-temperature behaviors of PP/CO2 solutions Type de document : texte imprimé Auteurs : Y. G. Li, Auteur ; C. B. Park, Auteur Année de publication : 2009 Article en page(s) : pp. 6633–6640 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polymer/gas solutions Pressure-volume-temperature properties Linear polypropylene Branched Résumé : The pressure−volume−temperature (PVT) properties of polymer/gas solutions are characterized by determining their volume dilation at a known temperature and pressure. This paper presents the results of an experiment that measured the volume swelling of linear and branched polypropylene (PP) with CO2 using a new PVT measurement apparatus. The swellings and specific volumes for linear and branched PP/CO2 are compared. The swelling mechanism that occurred due to CO2 dissolution, and the effects of the branched structure on volume swelling are investigated and discussed. Due to its entangled branch structure, the branched PP underwent a lesser degree of volume swelling than did the linear PP. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015279
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6633–6640[article] Effects of branching on the pressure-volume-temperature behaviors of PP/CO2 solutions [texte imprimé] / Y. G. Li, Auteur ; C. B. Park, Auteur . - 2009 . - pp. 6633–6640.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6633–6640
Mots-clés : Polymer/gas solutions Pressure-volume-temperature properties Linear polypropylene Branched Résumé : The pressure−volume−temperature (PVT) properties of polymer/gas solutions are characterized by determining their volume dilation at a known temperature and pressure. This paper presents the results of an experiment that measured the volume swelling of linear and branched polypropylene (PP) with CO2 using a new PVT measurement apparatus. The swellings and specific volumes for linear and branched PP/CO2 are compared. The swelling mechanism that occurred due to CO2 dissolution, and the effects of the branched structure on volume swelling are investigated and discussed. Due to its entangled branch structure, the branched PP underwent a lesser degree of volume swelling than did the linear PP. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015279 Exemplaires
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Titre : The importance of oscillatory structural forces in the sedimentation of a binary hard-sphere colloidal suspension Type de document : texte imprimé Auteurs : Jan Sudaporn Vesaratchanon, Auteur ; Alex Nikolov, Auteur ; Darsh Wasan, Auteur Année de publication : 2009 Article en page(s) : pp. 6641–6651 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Colloidal dispersions Hard-sphere suspension Oscillatory structural forces Monte Carlo simulations Stochastic particle dynamics methods Sedimentation experiments Résumé : Concentrated colloidal dispersions are complex systems comprised of colloidal particles of various sizes. This paper summarizes recent experimental and theoretical findings on understanding the interactions between microspheres in the presence of submicrometer particles; the submicrometer particles can be solvent molecules, surfactant micelles, or other nanometer-sized particles. In a hard-sphere suspension containing microspheres in the presence of submicrometer particles, oscillatory structural (entropic) forces between large particles, caused by small particles, arise as a result of the collective particle−particle interactions. The magnitude of the oscillatory structural forces is theoretically estimated based on the statistical mechanics approach, Monte Carlo simulations, and stochastic particle dynamics methods. Also, sedimentation experiments using spherical low-charged, binary hard-sphere particle suspensions with a large size ratio are presented to elucidate the importance of the oscillatory structural forces (i.e., attractive depletion and repulsive structural forces) in particle dispersion stability. Micronmeter-sized, low-charge latex particle concentration profiles in the presence of nanoparticles (nonionic micelles) were monitored using a nondestructive Kossel diffraction technique. To rationalize the experimental observations, the particle settling dynamics were simulated by considering the hydrodynamic interactions, structural forces, and Brownian motion in a gravity field. The theoretical predictions were determined to be in satisfactory agreement with the experimental observations. The effect of the particle size ratio (i.e., micrometer to submicrometer) on interparticle interaction energy is highlighted. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019856
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6641–6651[article] The importance of oscillatory structural forces in the sedimentation of a binary hard-sphere colloidal suspension [texte imprimé] / Jan Sudaporn Vesaratchanon, Auteur ; Alex Nikolov, Auteur ; Darsh Wasan, Auteur . - 2009 . - pp. 6641–6651.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6641–6651
Mots-clés : Colloidal dispersions Hard-sphere suspension Oscillatory structural forces Monte Carlo simulations Stochastic particle dynamics methods Sedimentation experiments Résumé : Concentrated colloidal dispersions are complex systems comprised of colloidal particles of various sizes. This paper summarizes recent experimental and theoretical findings on understanding the interactions between microspheres in the presence of submicrometer particles; the submicrometer particles can be solvent molecules, surfactant micelles, or other nanometer-sized particles. In a hard-sphere suspension containing microspheres in the presence of submicrometer particles, oscillatory structural (entropic) forces between large particles, caused by small particles, arise as a result of the collective particle−particle interactions. The magnitude of the oscillatory structural forces is theoretically estimated based on the statistical mechanics approach, Monte Carlo simulations, and stochastic particle dynamics methods. Also, sedimentation experiments using spherical low-charged, binary hard-sphere particle suspensions with a large size ratio are presented to elucidate the importance of the oscillatory structural forces (i.e., attractive depletion and repulsive structural forces) in particle dispersion stability. Micronmeter-sized, low-charge latex particle concentration profiles in the presence of nanoparticles (nonionic micelles) were monitored using a nondestructive Kossel diffraction technique. To rationalize the experimental observations, the particle settling dynamics were simulated by considering the hydrodynamic interactions, structural forces, and Brownian motion in a gravity field. The theoretical predictions were determined to be in satisfactory agreement with the experimental observations. The effect of the particle size ratio (i.e., micrometer to submicrometer) on interparticle interaction energy is highlighted. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019856 Exemplaires
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Titre : Steady-state operational degrees of freedom with application to refrigeration cycles Type de document : texte imprimé Auteurs : Jørgen Bauck Jensen, Auteur ; Sigurd Skogestad, Auteur Année de publication : 2009 Article en page(s) : pp. 6652–6659 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Freedom Refrigeration cyclesLiquified natural gas C3MR process Mixed fluid cascade Résumé : An important issue for optimal operation and plantwide control is to find the degrees of freedom available for optimal operation. A previously published systematic approach to determine the steady state degrees of freedom is expanded to take into account the active charge as a possible degree of freedom in cyclic processes. Additional degrees of freedom related to the composition of the circulating refrigerant are also discussed. Two liquified natural gas (LNG) processes of current interest, the C3MR process from Air Products and the mixed fluid cascade (MFC) process developed by Statoil-Linde LNG Technology Alliance, are studied with respect to operational degrees of freedom. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800565z
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6652–6659[article] Steady-state operational degrees of freedom with application to refrigeration cycles [texte imprimé] / Jørgen Bauck Jensen, Auteur ; Sigurd Skogestad, Auteur . - 2009 . - pp. 6652–6659.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6652–6659
Mots-clés : Freedom Refrigeration cyclesLiquified natural gas C3MR process Mixed fluid cascade Résumé : An important issue for optimal operation and plantwide control is to find the degrees of freedom available for optimal operation. A previously published systematic approach to determine the steady state degrees of freedom is expanded to take into account the active charge as a possible degree of freedom in cyclic processes. Additional degrees of freedom related to the composition of the circulating refrigerant are also discussed. Two liquified natural gas (LNG) processes of current interest, the C3MR process from Air Products and the mixed fluid cascade (MFC) process developed by Statoil-Linde LNG Technology Alliance, are studied with respect to operational degrees of freedom. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800565z Exemplaires
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Titre : Parallel machine scheduling under the disruption of machine breakdown Type de document : texte imprimé Auteurs : Lixin Tang, Auteur ; Yanyan Zhang, Auteur Année de publication : 2009 Article en page(s) : pp. 6660–6667 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Scheduling problem Dealing Machine breakdown Résumé : This paper investigates the scheduling problem of dealing with disruption caused by machine breakdown under the environment of identical parallel machines. When a machine breakdown changes the scheduling environment, the original schedule cannot be executed according to the prescribed plan. The objective after disruption is to create a recovery schedule that minimizes the original objective function and the deviation from the original schedule. The original objective function is the total weighted completion time, and the deviation is the completion time of jobs from the planned one. The recovery scheduling problem is formulated as an integer programming model. A Lagrangian relaxation (LR) framework that relaxes the machine capacity constraints is proposed for solving the model. The subgradient method is used to update the values of Lagrangian multipliers. The extensive computational experiments are carried out, and the numerical results demonstrate that the proposed LR approach based on the developed model can provide an excellent recovery schedule solution in a timely manner. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801868f
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6660–6667[article] Parallel machine scheduling under the disruption of machine breakdown [texte imprimé] / Lixin Tang, Auteur ; Yanyan Zhang, Auteur . - 2009 . - pp. 6660–6667.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6660–6667
Mots-clés : Scheduling problem Dealing Machine breakdown Résumé : This paper investigates the scheduling problem of dealing with disruption caused by machine breakdown under the environment of identical parallel machines. When a machine breakdown changes the scheduling environment, the original schedule cannot be executed according to the prescribed plan. The objective after disruption is to create a recovery schedule that minimizes the original objective function and the deviation from the original schedule. The original objective function is the total weighted completion time, and the deviation is the completion time of jobs from the planned one. The recovery scheduling problem is formulated as an integer programming model. A Lagrangian relaxation (LR) framework that relaxes the machine capacity constraints is proposed for solving the model. The subgradient method is used to update the values of Lagrangian multipliers. The extensive computational experiments are carried out, and the numerical results demonstrate that the proposed LR approach based on the developed model can provide an excellent recovery schedule solution in a timely manner. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801868f Exemplaires
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Titre : Using life cycle assessment to guide catalysis research Type de document : texte imprimé Auteurs : Peter A. Holman, Auteur ; David R. Shonnard, Auteur ; Joseph H. Holles, Auteur Année de publication : 2009 Article en page(s) : pp. 6668–6674 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Life cycle assessment Catalyst development Acrylic acid Eco-indicator 99 method Résumé : The use of life cycle assessment (LCA) as a tool to guide catalyst development is demonstrated by comparing the environmental impact of acrylic acid production from propylene, the current commercial feedstock, to propane as an alternate feedstock. Acrylic acid is currently produced in a two-step process from propylene. Because of its lower cost, propane is an attractive alternative to propylene; however, no catalysts are currently available that can compete with the high yield of the propylene process. The LCA was performed using SimaPro, and impact assessment was determined using the Eco-Indicator 99 method. A comparison of the two feedstocks at the 87% yield of the current commercial propylene process demonstrated that switching to propane would decrease the environmental impact of the process by 20%. Determination of environmental impact as the yield from the potential propane process was varied predicts that, at yields exceeding 6%, the propane process will have a lower environmental impact than the current propylene process. By focusing on particular categories such as fossil fuels or climate change, the propane process will have a lower impact for yields exceeding 15 and 33%, respectively. The current catalyst yield of up to 48% for the propane process exceeds these values. If reaction and waste gas heat are converted to electricity instead of steam, yields in excess of 61% will result in a lower total impact for the propane process. On the basis of raw material costs, the economic break-even point for the propane process is 59% yield. The similar yields of ∼60% from propane required by economics and for a lower environmental impact represents a factor of 1.25 increase in yield over the current state-of-the-art propane catalyst compared to a factor of 1.81 increase in yield required to equal the current propylene yield. Thus, the proposed propane process may be much closer to viability than previously realized. This analysis provides an example of how LCA can compare chemical production from two different feedstocks, even if a catalyst for the reaction of interest has not been designed. The LCA analysis can also be used to determine target goals for catalysis research. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801934s
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6668–6674[article] Using life cycle assessment to guide catalysis research [texte imprimé] / Peter A. Holman, Auteur ; David R. Shonnard, Auteur ; Joseph H. Holles, Auteur . - 2009 . - pp. 6668–6674.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6668–6674
Mots-clés : Life cycle assessment Catalyst development Acrylic acid Eco-indicator 99 method Résumé : The use of life cycle assessment (LCA) as a tool to guide catalyst development is demonstrated by comparing the environmental impact of acrylic acid production from propylene, the current commercial feedstock, to propane as an alternate feedstock. Acrylic acid is currently produced in a two-step process from propylene. Because of its lower cost, propane is an attractive alternative to propylene; however, no catalysts are currently available that can compete with the high yield of the propylene process. The LCA was performed using SimaPro, and impact assessment was determined using the Eco-Indicator 99 method. A comparison of the two feedstocks at the 87% yield of the current commercial propylene process demonstrated that switching to propane would decrease the environmental impact of the process by 20%. Determination of environmental impact as the yield from the potential propane process was varied predicts that, at yields exceeding 6%, the propane process will have a lower environmental impact than the current propylene process. By focusing on particular categories such as fossil fuels or climate change, the propane process will have a lower impact for yields exceeding 15 and 33%, respectively. The current catalyst yield of up to 48% for the propane process exceeds these values. If reaction and waste gas heat are converted to electricity instead of steam, yields in excess of 61% will result in a lower total impact for the propane process. On the basis of raw material costs, the economic break-even point for the propane process is 59% yield. The similar yields of ∼60% from propane required by economics and for a lower environmental impact represents a factor of 1.25 increase in yield over the current state-of-the-art propane catalyst compared to a factor of 1.81 increase in yield required to equal the current propylene yield. Thus, the proposed propane process may be much closer to viability than previously realized. This analysis provides an example of how LCA can compare chemical production from two different feedstocks, even if a catalyst for the reaction of interest has not been designed. The LCA analysis can also be used to determine target goals for catalysis research. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801934s Exemplaires
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Titre : Optimal scheduling of refined products pipelines with multiple sources Type de document : texte imprimé Auteurs : Diego C. Cafaro, Auteur ; Jaime Cerdá, Auteur Année de publication : 2009 Article en page(s) : pp. 6675–6689 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pipelines Optimal scheduling Résumé : Most contributions on short-term planning of multiproduct pipeline operations deal with pipelines featuring a single input terminal. In common-carrier pipelines, however, several refineries located at different sites use the same trunk line for shipping refined petroleum products to downstream output terminals. They can be regarded as multiple-source pipelines with input facilities at nonorigin points. The operation of intermediate sources raises some new difficult issues. Pumping runs taking place at intermediate locations can either insert a new lot or increase the size of a batch in transit. Batches are no longer arranged in the line in the same order that they are injected, and tracking the batch sequence becomes a more complex task. This paper introduces a novel continuous formulation for the scheduling of multiple-source pipelines operating on fungible or segregated mode. A case study involving a single pipeline that transports three distillates from two input to three output terminals was successfully solved over a 10-day time horizon. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900015b
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6675–6689[article] Optimal scheduling of refined products pipelines with multiple sources [texte imprimé] / Diego C. Cafaro, Auteur ; Jaime Cerdá, Auteur . - 2009 . - pp. 6675–6689.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6675–6689
Mots-clés : Pipelines Optimal scheduling Résumé : Most contributions on short-term planning of multiproduct pipeline operations deal with pipelines featuring a single input terminal. In common-carrier pipelines, however, several refineries located at different sites use the same trunk line for shipping refined petroleum products to downstream output terminals. They can be regarded as multiple-source pipelines with input facilities at nonorigin points. The operation of intermediate sources raises some new difficult issues. Pumping runs taking place at intermediate locations can either insert a new lot or increase the size of a batch in transit. Batches are no longer arranged in the line in the same order that they are injected, and tracking the batch sequence becomes a more complex task. This paper introduces a novel continuous formulation for the scheduling of multiple-source pipelines operating on fungible or segregated mode. A case study involving a single pipeline that transports three distillates from two input to three output terminals was successfully solved over a 10-day time horizon. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900015b Exemplaires
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Titre : Stochastic modeling and simultaneous regulation of surface roughness and porosity in thin film deposition Type de document : texte imprimé Auteurs : Gangshi Hu, Auteur ; Gerassimos Orkoulas, Auteur ; Panagiotis D. Christofides, Auteur Année de publication : 2009 Article en page(s) : pp. 6690–6700 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Surface roughness Porosity Thin film deposition Kinetic Monte Carlo simulation Microscopic model Résumé : This work focuses on stochastic modeling and simultaneous regulation of surface roughness and porosity for a porous thin film deposition process modeled via kinetic Monte Carlo (kMC) simulation on a triangular lattice. The microscopic model of the thin film growth process includes adsorption and migration processes. Vacancies and overhangs are allowed inside the film for the purpose of modeling thin film porosity. The definition of the surface height profile is first introduced for a porous thin film deposition taking place in a triangular lattice. The dynamics of surface height of the thin film are described by an Edwards-Wilkinson (EW) type equation, which is a second-order linear stochastic partial differential equation (PDE). The root-mean-square (RMS) surface roughness is chosen as one of the controlled variables. Subsequently, an appropriate definition of film site occupancy ratio (SOR) is introduced to represent the extent of porosity inside the film and is chosen as the second to-be-controlled variable. A deterministic ordinary differential equation (ODE) model is postulated to describe the time evolution of the film SOR. The coefficients of the EW equation of surface height and of the deterministic ODE model of the film SOR are estimated on the basis of data obtained from the kMC simulator of the deposition process using least-squares methods, and their dependence on substrate temperature is determined. The developed dynamic models are used as the basis for the design of a model predictive control algorithm that includes a penalty on the deviation of the surface roughness square and film SOR from their respective set-point values. Simulation results demonstrate the applicability and effectiveness of the proposed modeling and control approach in the context of the deposition process under consideration. When simultaneous control of surface roughness and porosity is carried out, a balanced trade-off is obtained in the closed-loop system between the two control objectives of surface roughness and porosity regulation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900708v
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6690–6700[article] Stochastic modeling and simultaneous regulation of surface roughness and porosity in thin film deposition [texte imprimé] / Gangshi Hu, Auteur ; Gerassimos Orkoulas, Auteur ; Panagiotis D. Christofides, Auteur . - 2009 . - pp. 6690–6700.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6690–6700
Mots-clés : Surface roughness Porosity Thin film deposition Kinetic Monte Carlo simulation Microscopic model Résumé : This work focuses on stochastic modeling and simultaneous regulation of surface roughness and porosity for a porous thin film deposition process modeled via kinetic Monte Carlo (kMC) simulation on a triangular lattice. The microscopic model of the thin film growth process includes adsorption and migration processes. Vacancies and overhangs are allowed inside the film for the purpose of modeling thin film porosity. The definition of the surface height profile is first introduced for a porous thin film deposition taking place in a triangular lattice. The dynamics of surface height of the thin film are described by an Edwards-Wilkinson (EW) type equation, which is a second-order linear stochastic partial differential equation (PDE). The root-mean-square (RMS) surface roughness is chosen as one of the controlled variables. Subsequently, an appropriate definition of film site occupancy ratio (SOR) is introduced to represent the extent of porosity inside the film and is chosen as the second to-be-controlled variable. A deterministic ordinary differential equation (ODE) model is postulated to describe the time evolution of the film SOR. The coefficients of the EW equation of surface height and of the deterministic ODE model of the film SOR are estimated on the basis of data obtained from the kMC simulator of the deposition process using least-squares methods, and their dependence on substrate temperature is determined. The developed dynamic models are used as the basis for the design of a model predictive control algorithm that includes a penalty on the deviation of the surface roughness square and film SOR from their respective set-point values. Simulation results demonstrate the applicability and effectiveness of the proposed modeling and control approach in the context of the deposition process under consideration. When simultaneous control of surface roughness and porosity is carried out, a balanced trade-off is obtained in the closed-loop system between the two control objectives of surface roughness and porosity regulation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900708v Exemplaires
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Titre : New continuous-time scheduling formulation for continuous plants under variable electricity cost Type de document : texte imprimé Auteurs : Pedro M. Castro, Auteur ; Iiro Harjunkoski, Auteur ; Ignacio E. Grossmann, Auteur Année de publication : 2009 Article en page(s) : pp. 6701–6714 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Continuous plants Scheduling Time-dependent electricity pricing Discrete-time formulation Continuous-time Résumé : This work addresses the scheduling of continuous plants subject to energy constraints related to time-dependent electricity pricing and availability. Discrete- and continuous-time formulations are presented that can address these issues together with multiple intermediate due dates. Both formulations rely on the resource−task network process representation. Their computational performance is compared for the objective of total electricity minimization with the results favoring the discrete-time model due to the more natural way of handling such a wide variety of discrete events. In particular, it can successfully handle problems of industrial size. Nevertheless, the new continuous-time model is a major breakthrough since it is the first model of its type that is able to effectively incorporate time-variable utility profiles. When compared to a simple manual scheduling procedure, the proposed scheduling approaches can lead to potential electricity savings around 20% by switching production from periods of high to low electricity cost. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900073k
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6701–6714[article] New continuous-time scheduling formulation for continuous plants under variable electricity cost [texte imprimé] / Pedro M. Castro, Auteur ; Iiro Harjunkoski, Auteur ; Ignacio E. Grossmann, Auteur . - 2009 . - pp. 6701–6714.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6701–6714
Mots-clés : Continuous plants Scheduling Time-dependent electricity pricing Discrete-time formulation Continuous-time Résumé : This work addresses the scheduling of continuous plants subject to energy constraints related to time-dependent electricity pricing and availability. Discrete- and continuous-time formulations are presented that can address these issues together with multiple intermediate due dates. Both formulations rely on the resource−task network process representation. Their computational performance is compared for the objective of total electricity minimization with the results favoring the discrete-time model due to the more natural way of handling such a wide variety of discrete events. In particular, it can successfully handle problems of industrial size. Nevertheless, the new continuous-time model is a major breakthrough since it is the first model of its type that is able to effectively incorporate time-variable utility profiles. When compared to a simple manual scheduling procedure, the proposed scheduling approaches can lead to potential electricity savings around 20% by switching production from periods of high to low electricity cost. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900073k Exemplaires
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Titre : Stage difference equation and its application in distillation synthesis Type de document : texte imprimé Auteurs : Wende Tian, Auteur ; Suli Sun, Auteur ; Qingjie Guo, Auteur Année de publication : 2009 Article en page(s) : pp. 6715–6722 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Distillation synthesis Stage difference equation Résumé : This paper introduces the stage difference equation (SDE) for distillation synthesis, which yields a series of liquid composition profiles for a plate tower. SDE is derived from mass balance through one common column section and identifies the relationship between two joined sections by its parameters. As these parameters need to be determined at first before applying SDE, their relations between composition and reflux ratio are then examined. SDE is used in nonreactive distillation and reactive distillation synthesis where the reactive stage difference equation (RSDE) is proposed based on reaction and variable transformations. Application case studies to nonreactive and reactive distillations indicate that these equations can facilitate the determination of operating regime and conveniently produce optimal synthesis solutions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015158
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6715–6722[article] Stage difference equation and its application in distillation synthesis [texte imprimé] / Wende Tian, Auteur ; Suli Sun, Auteur ; Qingjie Guo, Auteur . - 2009 . - pp. 6715–6722.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6715–6722
Mots-clés : Distillation synthesis Stage difference equation Résumé : This paper introduces the stage difference equation (SDE) for distillation synthesis, which yields a series of liquid composition profiles for a plate tower. SDE is derived from mass balance through one common column section and identifies the relationship between two joined sections by its parameters. As these parameters need to be determined at first before applying SDE, their relations between composition and reflux ratio are then examined. SDE is used in nonreactive distillation and reactive distillation synthesis where the reactive stage difference equation (RSDE) is proposed based on reaction and variable transformations. Application case studies to nonreactive and reactive distillations indicate that these equations can facilitate the determination of operating regime and conveniently produce optimal synthesis solutions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015158 Exemplaires
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Titre : An extended ant colony optimization algorithm for integrated process and control system design Type de document : texte imprimé Auteurs : Martin Schlüter, Auteur ; Jose A. Egea, Auteur ; Luis T. Antelo, Auteur Année de publication : 2009 Article en page(s) : pp. 6723–6738 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Integrated process and control system Mixed integer nonlinear programming problem Optimization algorithm Résumé : The problem of integrated process and control system design is discussed in this paper. We formulate it as a mixed integer nonlinear programming problem subject to differential-algebraic constraints. This class of problems is frequently nonconvex and, therefore, local optimization techniques usually fail to locate the global solution. Here we propose a global optimization algorithm, based on an extension of the ant colony optimization metaheuristic, in order to solve this challenging class of problems in an efficient and robust way. The ideas of the methodology are explained and, on the basis of different full-plant case studies, the performance of the approach is evaluated. The first set of benchmark problems deal with the integrated design and control of two different wastewater treatment plants, consisting on both NLP and MINLP formulations. The last case study is the well-known Tennessee Eastman process. Numerical experiments with our new method indicate that we can achieve an improved performance in all cases. Additionally, our method outperforms several other recent competitive solvers for the challenging case studies considered. En ligne : An Extended Ant Colony Optimization Algorithm for Integrated Process and Control [...]
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6723–6738[article] An extended ant colony optimization algorithm for integrated process and control system design [texte imprimé] / Martin Schlüter, Auteur ; Jose A. Egea, Auteur ; Luis T. Antelo, Auteur . - 2009 . - pp. 6723–6738.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6723–6738
Mots-clés : Integrated process and control system Mixed integer nonlinear programming problem Optimization algorithm Résumé : The problem of integrated process and control system design is discussed in this paper. We formulate it as a mixed integer nonlinear programming problem subject to differential-algebraic constraints. This class of problems is frequently nonconvex and, therefore, local optimization techniques usually fail to locate the global solution. Here we propose a global optimization algorithm, based on an extension of the ant colony optimization metaheuristic, in order to solve this challenging class of problems in an efficient and robust way. The ideas of the methodology are explained and, on the basis of different full-plant case studies, the performance of the approach is evaluated. The first set of benchmark problems deal with the integrated design and control of two different wastewater treatment plants, consisting on both NLP and MINLP formulations. The last case study is the well-known Tennessee Eastman process. Numerical experiments with our new method indicate that we can achieve an improved performance in all cases. Additionally, our method outperforms several other recent competitive solvers for the challenging case studies considered. En ligne : An Extended Ant Colony Optimization Algorithm for Integrated Process and Control [...] Exemplaires
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Titre : Toward polymer product design. I. dynamic optimization of average molecular weights and polydispersity index in batch free radical polymerization Type de document : texte imprimé Auteurs : Xi Chen, Auteur ; Chen, Li, Auteur ; Jian Feng, Auteur Année de publication : 2009 Article en page(s) : pp. 6739–6748 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polymer products Molecular weight distribution Polydispersity index Stickler− Panke− Hamielec model Résumé : In the polymer industry, product quality is usually determined by the molecular weight distribution of polymer products. We propose a comprehensive study of polymer product design through dynamic optimization of average molecular weights and the polydispersity index in batch free radical polymerization. After analyzing and validating the modified Stickler−Panke−Hamielec (SPH) model, this paper extends the model to achieve product design with a specified polymer molecular weight distribution for various optimization goals. Conversion maximization under isothermal conditions was studied first. We concluded that dynamic optimization is useful to obtain desired products. However, some specifications of polymer molecular weight distribution cannot be achieved under isothermal conditions. Therefore, optimization with piecewise constant temperature profiles was also studied to extend the range of product specifications. Considering the practical requirement for productivity in engineering applications, reaction time minimization with specified conversion was studied with various temperature profiles. Besides the strategy of optimizing the temperature profile, dynamic optimization of initiator feed profiles is also presented. The results show that polymer product design with a specified polymer molecular weight distribution can be achieved using dynamic optimization of the temperature and initiator profiles in a batch reaction. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801844u
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6739–6748[article] Toward polymer product design. I. dynamic optimization of average molecular weights and polydispersity index in batch free radical polymerization [texte imprimé] / Xi Chen, Auteur ; Chen, Li, Auteur ; Jian Feng, Auteur . - 2009 . - pp. 6739–6748.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6739–6748
Mots-clés : Polymer products Molecular weight distribution Polydispersity index Stickler− Panke− Hamielec model Résumé : In the polymer industry, product quality is usually determined by the molecular weight distribution of polymer products. We propose a comprehensive study of polymer product design through dynamic optimization of average molecular weights and the polydispersity index in batch free radical polymerization. After analyzing and validating the modified Stickler−Panke−Hamielec (SPH) model, this paper extends the model to achieve product design with a specified polymer molecular weight distribution for various optimization goals. Conversion maximization under isothermal conditions was studied first. We concluded that dynamic optimization is useful to obtain desired products. However, some specifications of polymer molecular weight distribution cannot be achieved under isothermal conditions. Therefore, optimization with piecewise constant temperature profiles was also studied to extend the range of product specifications. Considering the practical requirement for productivity in engineering applications, reaction time minimization with specified conversion was studied with various temperature profiles. Besides the strategy of optimizing the temperature profile, dynamic optimization of initiator feed profiles is also presented. The results show that polymer product design with a specified polymer molecular weight distribution can be achieved using dynamic optimization of the temperature and initiator profiles in a batch reaction. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801844u Exemplaires
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Titre : Efficient optimization-based design of distillation processes for homogeneous azeotropic mixtures Type de document : texte imprimé Auteurs : Korbinian Kraemer, Auteur ; Sven Kossack, Auteur ; Marquardt, Wolfgang, Auteur Année de publication : 2009 Article en page(s) : pp. 6749–6764 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Complex distillation processes Azeotropic multicomponent mixture Outstanding robustness Résumé : Rigorous optimization is a valuable tool that can support the engineer to tap the full economic potential of a distillation process. Unfortunately, the solution of these large-scale discrete-continuous optimization problems usually suffers from a lack of robustness, long computational times, and a low reliability toward good local optima. In this paper, the rigorous optimization of complex distillation processes for azeotropic multicomponent mixtures is achieved with outstanding robustness, reliability, and efficiency through progress on two levels. First, the integration within a process synthesis framework allows a reduction of the complexity of the optimization superstructure and provides an excellent initialization by shortcut evaluation with the rectification body method. Second, the reformulation as a purely continuous optimization problem enables a solution with reliable and efficient NLP solvers. Moreover, the continuous reformulation considers a particular tight column model formulation such that the introduction of special nonlinear constraints to force integer decisions could be largely avoided. A careful initialization phase and a stepwise solution procedure with gradually tightened bounds facilitate a robust and efficient solution. Different superstructures for the tray optimization of distillation columns are tested. The methods are illustrated by three demanding case studies. The first case study considers the conceptual design as well as the rigorous optimization of a curved boundary process for the complete separation of an azeotropic four-component mixture. The rigorous optimization of a pressure swing process for the separation of a highly nonideal five component mixture is presented in the second case study. Finally, the third case study covers the rigorous optimization of an extractive separation within a complex column system. All case studies could be robustly solved due to the favorable initialization phase. The continuously reformulated problems required significantly less computational time and identified local optima of better quality as compared to the mixed-integer nonlinear programming techniques (MINLP) solution. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900143e
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6749–6764[article] Efficient optimization-based design of distillation processes for homogeneous azeotropic mixtures [texte imprimé] / Korbinian Kraemer, Auteur ; Sven Kossack, Auteur ; Marquardt, Wolfgang, Auteur . - 2009 . - pp. 6749–6764.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6749–6764
Mots-clés : Complex distillation processes Azeotropic multicomponent mixture Outstanding robustness Résumé : Rigorous optimization is a valuable tool that can support the engineer to tap the full economic potential of a distillation process. Unfortunately, the solution of these large-scale discrete-continuous optimization problems usually suffers from a lack of robustness, long computational times, and a low reliability toward good local optima. In this paper, the rigorous optimization of complex distillation processes for azeotropic multicomponent mixtures is achieved with outstanding robustness, reliability, and efficiency through progress on two levels. First, the integration within a process synthesis framework allows a reduction of the complexity of the optimization superstructure and provides an excellent initialization by shortcut evaluation with the rectification body method. Second, the reformulation as a purely continuous optimization problem enables a solution with reliable and efficient NLP solvers. Moreover, the continuous reformulation considers a particular tight column model formulation such that the introduction of special nonlinear constraints to force integer decisions could be largely avoided. A careful initialization phase and a stepwise solution procedure with gradually tightened bounds facilitate a robust and efficient solution. Different superstructures for the tray optimization of distillation columns are tested. The methods are illustrated by three demanding case studies. The first case study considers the conceptual design as well as the rigorous optimization of a curved boundary process for the complete separation of an azeotropic four-component mixture. The rigorous optimization of a pressure swing process for the separation of a highly nonideal five component mixture is presented in the second case study. Finally, the third case study covers the rigorous optimization of an extractive separation within a complex column system. All case studies could be robustly solved due to the favorable initialization phase. The continuously reformulated problems required significantly less computational time and identified local optima of better quality as compared to the mixed-integer nonlinear programming techniques (MINLP) solution. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900143e Exemplaires
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Titre : Optimization of the methylation conditions of kraft cellulose pulp for its use as a thickener agent in biodegradable lubricating greases Type de document : texte imprimé Auteurs : J. E. Martin-Alfonso, Auteur ; R. Yañez, Auteur ; C. Valencia, Auteur Année de publication : 2009 Article en page(s) : pp. 6765–6771 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Kraft cellulose pulp Methylation conditions Thickener agent Résumé : This work evaluates the influence of the operating conditions used in the derivatization of commercial Kraft cellulose pulp (mercerization time (1−3 h) methylation process temperature (30−60 °C), methylation process time (1−4 h), (initial pulp)/(final wet alkali pulp) ratio (S/S) (1/7−1/12), and pulp/acetone ratio (S/L) concentration (1/3−1/12)) on the obtained methylcellulose pulp characteristics such as degree of polymerization of cellulose, substitution degree, water solubility, and viscosity of the resulting pulps in order to determine the best process conditions of this pulp for its use as a thickener agent in biodegradable lubricating grease formulations. Efficient use of the raw material (i.e., obtaining a degree of polymerization with suitable substitution degree) entailed using a 2.5 h methylation time and a 45 °C methylation temperature. The substitution degree (DS) and consistency index thus obtained are only 14.5% and 36.3% respectively lower than the optimum value, and an increment of 28.6% could be obtained for the degree of polymerization. Some methylcellulose-based oleogels display rheological properties very similar to those found in traditional lubricating greases. Methylcellulose with DS values of around 0.4 produces oleogels with better mechanical properties than highly derivatized cellulose and much better than the original Kraft cellulose pulp. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002766
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6765–6771[article] Optimization of the methylation conditions of kraft cellulose pulp for its use as a thickener agent in biodegradable lubricating greases [texte imprimé] / J. E. Martin-Alfonso, Auteur ; R. Yañez, Auteur ; C. Valencia, Auteur . - 2009 . - pp. 6765–6771.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6765–6771
Mots-clés : Kraft cellulose pulp Methylation conditions Thickener agent Résumé : This work evaluates the influence of the operating conditions used in the derivatization of commercial Kraft cellulose pulp (mercerization time (1−3 h) methylation process temperature (30−60 °C), methylation process time (1−4 h), (initial pulp)/(final wet alkali pulp) ratio (S/S) (1/7−1/12), and pulp/acetone ratio (S/L) concentration (1/3−1/12)) on the obtained methylcellulose pulp characteristics such as degree of polymerization of cellulose, substitution degree, water solubility, and viscosity of the resulting pulps in order to determine the best process conditions of this pulp for its use as a thickener agent in biodegradable lubricating grease formulations. Efficient use of the raw material (i.e., obtaining a degree of polymerization with suitable substitution degree) entailed using a 2.5 h methylation time and a 45 °C methylation temperature. The substitution degree (DS) and consistency index thus obtained are only 14.5% and 36.3% respectively lower than the optimum value, and an increment of 28.6% could be obtained for the degree of polymerization. Some methylcellulose-based oleogels display rheological properties very similar to those found in traditional lubricating greases. Methylcellulose with DS values of around 0.4 produces oleogels with better mechanical properties than highly derivatized cellulose and much better than the original Kraft cellulose pulp. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002766 Exemplaires
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Titre : Adsorption behavior studies of picric acid on mesoporous MCM-41 Type de document : texte imprimé Auteurs : Hamid Sepehrian, Auteur ; Javad Fasihi, Auteur ; Mohamad Khayatzadeh Mahani, Auteur Année de publication : 2009 Article en page(s) : pp. 6772–6775 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Wastewater Mesoporous silicate MCM-41 Hydrothermal method XRD Résumé : The presence of nitrophenols in wastewater is of great environmental concern. In this paper, mesoporous silicate MCM-41 has been prepared by the hydrothermal method and characterized by XRD, the nitrogen adsorption isotherm, and elemental analysis. Adsorption behaviors of 2,4,6-trinitrophenol (picric acid) on the calcined and uncalcined mesoporous MCM-41 adsorbents were studied. The experimental adsorption isotherm was successfully described by the Langmuir model. The pH effect, adsorption kinetics, and breakthrough curves were studied by batch and column methods. The adsorption capacity of picric acid varied significantly with the pH of the solution. It was found that the adsorption capacity is very high in the pH range of 1.4−4.0 and adsorption decreases with increasing pH value. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801716k
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6772–6775[article] Adsorption behavior studies of picric acid on mesoporous MCM-41 [texte imprimé] / Hamid Sepehrian, Auteur ; Javad Fasihi, Auteur ; Mohamad Khayatzadeh Mahani, Auteur . - 2009 . - pp. 6772–6775.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6772–6775
Mots-clés : Wastewater Mesoporous silicate MCM-41 Hydrothermal method XRD Résumé : The presence of nitrophenols in wastewater is of great environmental concern. In this paper, mesoporous silicate MCM-41 has been prepared by the hydrothermal method and characterized by XRD, the nitrogen adsorption isotherm, and elemental analysis. Adsorption behaviors of 2,4,6-trinitrophenol (picric acid) on the calcined and uncalcined mesoporous MCM-41 adsorbents were studied. The experimental adsorption isotherm was successfully described by the Langmuir model. The pH effect, adsorption kinetics, and breakthrough curves were studied by batch and column methods. The adsorption capacity of picric acid varied significantly with the pH of the solution. It was found that the adsorption capacity is very high in the pH range of 1.4−4.0 and adsorption decreases with increasing pH value. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801716k Exemplaires
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Titre : Use of calorimetry model and batch control technique for scale-up of unseeded batch cooling crystallization of poly(hydroxybenzophenone) Type de document : texte imprimé Auteurs : Huiyong Kim, Auteur ; Yookyung Bang, Auteur ; Kwang Soon Lee, Auteur Année de publication : 2009 Article en page(s) : pp. 6776–6782 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Scale-up method Cooling crystallization Poly(hydroxybenzophenone) Crystallization Résumé : A scale-up method to design and implement a cooling profile for unseeded batch cooling crystallization has been investigated. The reduced ratio between the heat-transfer area and the volume during scale-up to a large crystallizer causes an increase in the temperature distribution in the reactor, which can trigger unwanted nucleation around the cold spots of the vessel wall. To address this problem, a method is proposed to design a cooling profile for a scaled-up crystallizer that can replicate the seed-generation stage of a small crystallizer by effectively suppressing the unwanted nucleation. The use of a batch control technique as method of implementing the cooling profile in a large crystallizer is also proposed. Experiments were conducted with a 100 mL reactor and a 5 L scaled-up reactor for the unseeded crystallization of poly(hydroxybenzophenone) (PHBP) to verify the performance of the proposed method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801039f
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6776–6782[article] Use of calorimetry model and batch control technique for scale-up of unseeded batch cooling crystallization of poly(hydroxybenzophenone) [texte imprimé] / Huiyong Kim, Auteur ; Yookyung Bang, Auteur ; Kwang Soon Lee, Auteur . - 2009 . - pp. 6776–6782.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6776–6782
Mots-clés : Scale-up method Cooling crystallization Poly(hydroxybenzophenone) Crystallization Résumé : A scale-up method to design and implement a cooling profile for unseeded batch cooling crystallization has been investigated. The reduced ratio between the heat-transfer area and the volume during scale-up to a large crystallizer causes an increase in the temperature distribution in the reactor, which can trigger unwanted nucleation around the cold spots of the vessel wall. To address this problem, a method is proposed to design a cooling profile for a scaled-up crystallizer that can replicate the seed-generation stage of a small crystallizer by effectively suppressing the unwanted nucleation. The use of a batch control technique as method of implementing the cooling profile in a large crystallizer is also proposed. Experiments were conducted with a 100 mL reactor and a 5 L scaled-up reactor for the unseeded crystallization of poly(hydroxybenzophenone) (PHBP) to verify the performance of the proposed method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801039f Exemplaires
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Titre : Ethanol dehydration by adsorption with starchy and cellulosic materials Type de document : texte imprimé Auteurs : Julian A. Quintero, Auteur ; Carlos A. Cardona, Auteur Année de publication : 2009 Article en page(s) : pp. 6783–6788 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Starchy materials Cellulosic Ethanol dehydration Adsorption Résumé : Adsorption with starchy and cellulosic materials was evaluated as an energy efficient technology for ethanol dehydration. Corn (Zea mays), upright elephant ear (Alocasia macrorrhiza), cassava (Manihot esculenta), and sugar cane bagasse (Saccharum), were used as sources of starch and cellulosic fibers and further used as adsorbents for water removal. Enzymes (α-amylase and cellulase for starch and cellulose, respectively) were evaluated as modifying agents with the aim of increasing water adsorption capacity. Native and enzyme-treated materials were examined with SEM, XRD, and BET analysis to determine the hydrolysis influence on structure and superficial area. Partial hydrolysis was obtained under operation conditions evaluated, as was shown by the SEM micrographs. Crystallinity increased with the enzymatic hydrolysis for all materials. For all materials, superficial area was not increased with enzymatic hydrolysis but water adsorption capacity was improved reaching an anhydrous product with enzyme-treated materials. Water adsorption capacity ranges from 4 to 19 g/ 100 g adsorbent were found for evaluated materials. Corn starch had the highest water adsorption capacity (19 g/ 100 g ads) while upright elephant ear starch presented the lowest (4.2 g/ 100 g ads). Tested materials showed affinity with water for both native and enzyme-treated cases. This allowed water to adsorb from the feed for obtaining anhydrous ethanol. It was suggested that water adsorption capacity was increased because of the more exposed hydroxyl groups from the polymeric structures evaluated (starch and cellulose). Applicability of these materials was oriented to small scale ethanol production plants in developing countries where rural areas are the objective and small productions are expected. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015736
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6783–6788[article] Ethanol dehydration by adsorption with starchy and cellulosic materials [texte imprimé] / Julian A. Quintero, Auteur ; Carlos A. Cardona, Auteur . - 2009 . - pp. 6783–6788.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6783–6788
Mots-clés : Starchy materials Cellulosic Ethanol dehydration Adsorption Résumé : Adsorption with starchy and cellulosic materials was evaluated as an energy efficient technology for ethanol dehydration. Corn (Zea mays), upright elephant ear (Alocasia macrorrhiza), cassava (Manihot esculenta), and sugar cane bagasse (Saccharum), were used as sources of starch and cellulosic fibers and further used as adsorbents for water removal. Enzymes (α-amylase and cellulase for starch and cellulose, respectively) were evaluated as modifying agents with the aim of increasing water adsorption capacity. Native and enzyme-treated materials were examined with SEM, XRD, and BET analysis to determine the hydrolysis influence on structure and superficial area. Partial hydrolysis was obtained under operation conditions evaluated, as was shown by the SEM micrographs. Crystallinity increased with the enzymatic hydrolysis for all materials. For all materials, superficial area was not increased with enzymatic hydrolysis but water adsorption capacity was improved reaching an anhydrous product with enzyme-treated materials. Water adsorption capacity ranges from 4 to 19 g/ 100 g adsorbent were found for evaluated materials. Corn starch had the highest water adsorption capacity (19 g/ 100 g ads) while upright elephant ear starch presented the lowest (4.2 g/ 100 g ads). Tested materials showed affinity with water for both native and enzyme-treated cases. This allowed water to adsorb from the feed for obtaining anhydrous ethanol. It was suggested that water adsorption capacity was increased because of the more exposed hydroxyl groups from the polymeric structures evaluated (starch and cellulose). Applicability of these materials was oriented to small scale ethanol production plants in developing countries where rural areas are the objective and small productions are expected. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015736 Exemplaires
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Titre : Adsorptive preconcentration of uranium in hydrogels from seawater and aqueous solutions Type de document : texte imprimé Auteurs : Sadananda Das, Auteur ; Ashok K. Pandey, Auteur ; T. Vasudevan, Auteur Année de publication : 2009 Article en page(s) : pp. 6789–6796 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cross-linked hydrogels Bulk polymerization Seawater samples Aqueous solutions Adsorption Résumé : Cross-linked hydrogels containing poly(ethylene glycol methacrylate phosphate) (EGMP), poly(2-acrylamido-2-methyl-1-propane sulfonate) (AMPS), poly(acrylamidoxime) (AO), and AO along with different acidic (acrylic acid (AA), methacrylic acid (MAA), AMPS, and EGMP) and basic (3-(acrylamido propyl) trimethylammonium chloride (APTAC)) comonomers were prepared by UV-initiated bulk polymerization. These hydrogels were characterized in terms of their chemical structure and U(VI)-uptake behavior from aqueous and seawater samples. Except AMPS hydrogel, all these hydrogels were found to sorb U(VI) quantitatively (≈90%) from the seawater. The U(VI)-sorption kinetics in EGMP and AO+MAA (60:40) hydrogels were found to be faster than other hydrogels under seawater conditions. The presence of a strong acid (−SO3H) comonomer with AO retards the overall kinetics involve in the U(VI) sorption from seawater. It was also observed that the U(VI) sorption kinetics was highly dependent on the composition of the acidic and AO groups in the hydrogel. The uptake of U(VI) from acidic solution in AO+MAA hydrogel was found to be dependent on the acidity of the feed solution, and there was no uptake of U(VI) in this hydrogel from solution containing 1 mol L−1 HNO3. Contrary to this, EGMP hydrogel could sorb the U(VI) from solution containing high concentration of HNO3. This indicated that EGMP hydrogel can also be used for U(VI) preconcentration from the nuclear waste. U(VI) complexed in EGMP hydrogel and AO+MAA could be desorbed by their equilibration with 0.5 mol L−1 Na2CO3 and 1 mol L−1 HCl/HNO3, respectively. The mechanism of sorption of U(VI) in the hydrogels was studied to understand the factors that control the U(VI) sorption from seawater. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801912n
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6789–6796[article] Adsorptive preconcentration of uranium in hydrogels from seawater and aqueous solutions [texte imprimé] / Sadananda Das, Auteur ; Ashok K. Pandey, Auteur ; T. Vasudevan, Auteur . - 2009 . - pp. 6789–6796.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6789–6796
Mots-clés : Cross-linked hydrogels Bulk polymerization Seawater samples Aqueous solutions Adsorption Résumé : Cross-linked hydrogels containing poly(ethylene glycol methacrylate phosphate) (EGMP), poly(2-acrylamido-2-methyl-1-propane sulfonate) (AMPS), poly(acrylamidoxime) (AO), and AO along with different acidic (acrylic acid (AA), methacrylic acid (MAA), AMPS, and EGMP) and basic (3-(acrylamido propyl) trimethylammonium chloride (APTAC)) comonomers were prepared by UV-initiated bulk polymerization. These hydrogels were characterized in terms of their chemical structure and U(VI)-uptake behavior from aqueous and seawater samples. Except AMPS hydrogel, all these hydrogels were found to sorb U(VI) quantitatively (≈90%) from the seawater. The U(VI)-sorption kinetics in EGMP and AO+MAA (60:40) hydrogels were found to be faster than other hydrogels under seawater conditions. The presence of a strong acid (−SO3H) comonomer with AO retards the overall kinetics involve in the U(VI) sorption from seawater. It was also observed that the U(VI) sorption kinetics was highly dependent on the composition of the acidic and AO groups in the hydrogel. The uptake of U(VI) from acidic solution in AO+MAA hydrogel was found to be dependent on the acidity of the feed solution, and there was no uptake of U(VI) in this hydrogel from solution containing 1 mol L−1 HNO3. Contrary to this, EGMP hydrogel could sorb the U(VI) from solution containing high concentration of HNO3. This indicated that EGMP hydrogel can also be used for U(VI) preconcentration from the nuclear waste. U(VI) complexed in EGMP hydrogel and AO+MAA could be desorbed by their equilibration with 0.5 mol L−1 Na2CO3 and 1 mol L−1 HCl/HNO3, respectively. The mechanism of sorption of U(VI) in the hydrogels was studied to understand the factors that control the U(VI) sorption from seawater. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801912n Exemplaires
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Titre : Determination of tribromo-neopentyl alcohol micelle distribution coefficients in single and mixture solutions for evaluation of micellar enhanced ultrafiltration feasibility in treating contaminated groundwater Type de document : texte imprimé Auteurs : M. Krivorot, Auteur ; Y. Oren, Auteur ; Y. Talmon, Auteur Année de publication : 2009 Article en page(s) : pp. 6797–6804 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Micellar enhanced ultrafiltration Contaminated groundwater Résumé : To evaluate the potential of micellar enhanced ultrafiltration (MEUF) for treating groundwater contaminated with organics in northern Negev, Israel, the partition coefficient, KTBNPA, of tribromo-neopentyl alcohol (TBNPA) between aqueous and micellar phases was determined for nonionic surfactants. Two methods were used for the determination: the MEUF method using centrifugal UF equipped with 10 kDa MWCO regenerated cellulose and the solid phase matrix extraction (SPME) method using gas chromatography (GC) analysis. The distribution coefficient of TBNPA for nonionic surfactant Brij 58 (C16EO20) was ∼630 M−1 and fairly constant over a wide range of loadings (mole fraction of TBNPA in micelle from 0.07−0.45) when determined by centrifugal MEUF; but is was only ∼340−400 M−1 when determined by SPME. This difference is attributed to concentration polarization of the micelles in the UF measurements. The partition coefficient was reduced about 10% in the presence of 1% NaCl. The presence of toluene in samples containing TBNPA increases the solubility of TBNPA in the micellar phases of Brij 58 and Igepal CO-720, as determined by SPME. This phenomenon is explained by assuming that toluene (a nonpolar molecule) dissolves in the hydrocarbon core of the micelles resulting in expansion of the micelle and increase of the distance between polar groups in the palisade layer. As a result, the micelle can incorporate more of the polar TBNPA molecules in that layer. Cryogenic-temperature transmission electron microscopy observations of micelles loaded with TBNPA showed that TBNPA loading did not significantly change micelle size, consistent with TBNPA concentrating in the palisade layer. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011352
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6797–6804[article] Determination of tribromo-neopentyl alcohol micelle distribution coefficients in single and mixture solutions for evaluation of micellar enhanced ultrafiltration feasibility in treating contaminated groundwater [texte imprimé] / M. Krivorot, Auteur ; Y. Oren, Auteur ; Y. Talmon, Auteur . - 2009 . - pp. 6797–6804.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6797–6804
Mots-clés : Micellar enhanced ultrafiltration Contaminated groundwater Résumé : To evaluate the potential of micellar enhanced ultrafiltration (MEUF) for treating groundwater contaminated with organics in northern Negev, Israel, the partition coefficient, KTBNPA, of tribromo-neopentyl alcohol (TBNPA) between aqueous and micellar phases was determined for nonionic surfactants. Two methods were used for the determination: the MEUF method using centrifugal UF equipped with 10 kDa MWCO regenerated cellulose and the solid phase matrix extraction (SPME) method using gas chromatography (GC) analysis. The distribution coefficient of TBNPA for nonionic surfactant Brij 58 (C16EO20) was ∼630 M−1 and fairly constant over a wide range of loadings (mole fraction of TBNPA in micelle from 0.07−0.45) when determined by centrifugal MEUF; but is was only ∼340−400 M−1 when determined by SPME. This difference is attributed to concentration polarization of the micelles in the UF measurements. The partition coefficient was reduced about 10% in the presence of 1% NaCl. The presence of toluene in samples containing TBNPA increases the solubility of TBNPA in the micellar phases of Brij 58 and Igepal CO-720, as determined by SPME. This phenomenon is explained by assuming that toluene (a nonpolar molecule) dissolves in the hydrocarbon core of the micelles resulting in expansion of the micelle and increase of the distance between polar groups in the palisade layer. As a result, the micelle can incorporate more of the polar TBNPA molecules in that layer. Cryogenic-temperature transmission electron microscopy observations of micelles loaded with TBNPA showed that TBNPA loading did not significantly change micelle size, consistent with TBNPA concentrating in the palisade layer. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011352 Exemplaires
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Titre : Nafion-117 behavior during cation separation from spent chromium plating solutions Type de document : texte imprimé Auteurs : M. Elmuntasir I. Ahmed, Auteur ; Kuo-Lin Huang, Auteur ; Thomas M. Holsen, Auteur Année de publication : 2009 Article en page(s) : pp. 6805–6810 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nafion-117 ion-exchange membranes Spent chromium plating solutions Résumé : This study investigated the behavior of Nafion-117 ion-exchange membranes that are commonly used as the separator in electrolytic regeneration of spent chromium plating solutions. In the co-presence of Cu2+, Ni2+, and Fe3+ impurities (∼0.01−0.1 M) in ∼0.5−2.0 M H2CrO4, the exchange equivalents of Ni2+ by Nafion-117 was double that of Cu2+ (0.02 mmol of H+/(g of Nafion)) but smaller than that (∼0.03−0.15 mmol of H+/(g of Nafion)) of Fe3+, exhibiting the order Fe3+ ≥ Ni2+ ≥ Cu2+ in Nafion affinity. The water content (∼41%) of a Nafion-117 membrane soaked in 2 M H2CrO4 was greater than those (∼35−38%) in the contaminated 2 M chromic acid solutions, whereas the porosity (0.24) of the former was smaller than those (0.29−0.37) of the latter. For the Nafion-117 in 2 M chromic acid solutions with/without cation impurities, (1) the tortuosity coefficient of Fe3+ was about 1.8 times that of Cu2+ or Ni2+, (2) the calculated pore radius was 3.2 nm for a multiimpurity case (0.1 M Cu(II), Fe(III), Ni(II), and Cr(III) each) based on the Gierke’s model, and (3) the cation impurities did not significantly influence the numbers of water molecules in Nafion clusters. The Nafion-117 withstood the pH En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900149a
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6805–6810[article] Nafion-117 behavior during cation separation from spent chromium plating solutions [texte imprimé] / M. Elmuntasir I. Ahmed, Auteur ; Kuo-Lin Huang, Auteur ; Thomas M. Holsen, Auteur . - 2009 . - pp. 6805–6810.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6805–6810
Mots-clés : Nafion-117 ion-exchange membranes Spent chromium plating solutions Résumé : This study investigated the behavior of Nafion-117 ion-exchange membranes that are commonly used as the separator in electrolytic regeneration of spent chromium plating solutions. In the co-presence of Cu2+, Ni2+, and Fe3+ impurities (∼0.01−0.1 M) in ∼0.5−2.0 M H2CrO4, the exchange equivalents of Ni2+ by Nafion-117 was double that of Cu2+ (0.02 mmol of H+/(g of Nafion)) but smaller than that (∼0.03−0.15 mmol of H+/(g of Nafion)) of Fe3+, exhibiting the order Fe3+ ≥ Ni2+ ≥ Cu2+ in Nafion affinity. The water content (∼41%) of a Nafion-117 membrane soaked in 2 M H2CrO4 was greater than those (∼35−38%) in the contaminated 2 M chromic acid solutions, whereas the porosity (0.24) of the former was smaller than those (0.29−0.37) of the latter. For the Nafion-117 in 2 M chromic acid solutions with/without cation impurities, (1) the tortuosity coefficient of Fe3+ was about 1.8 times that of Cu2+ or Ni2+, (2) the calculated pore radius was 3.2 nm for a multiimpurity case (0.1 M Cu(II), Fe(III), Ni(II), and Cr(III) each) based on the Gierke’s model, and (3) the cation impurities did not significantly influence the numbers of water molecules in Nafion clusters. The Nafion-117 withstood the pH En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900149a Exemplaires
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Titre : Measurements and modeling of wetting efficiency in trickle-bed reactors : liquid viscosity and bed packing effects Type de document : texte imprimé Auteurs : Carine Julcour-Lebigue, Auteur ; Frédéric Augier, Auteur ; Harold Maffre, Auteur Année de publication : 2009 Article en page(s) : pp. 6811–6819 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Liquid viscosity Wetting efficiency Résumé : An experimental parametric study on wetting efficiency is reported which evaluates the influence of liquid viscosity, as well as the effect of particle size(/shape) and bed porosity (εB), separately. A 10-fold increase of liquid viscosity improves slightly catalyst wetting (by about 10%), while an increase of either bed porosity or particle size has the opposite effect. Wetting efficiency is reduced by about 0.1 for an increase of εB from 0.38 and 0.40 due to a change of particle size from 1.8 to 7 × 10−3 m while the decrease is only 0.05 for a similar variation of εB (0.38−0.41) with the same particles. The effect of particle shape (cylindrical/trilobe extrudates or spheres) appears very small in the investigated conditions. A new correlation for wetting efficiency is proposed, using a bounded function and only three dimensionless groups (liquid Froude and Morton numbers and bed porosity). This correlation is able to predict wetting efficiency with a very good precision on a large database, provided wetting liquids are used. Adding fines in the fixed bed is also examined, and its positive effect can be correlated with the size ratio between catalyst particles and fines. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002443
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6811–6819[article] Measurements and modeling of wetting efficiency in trickle-bed reactors : liquid viscosity and bed packing effects [texte imprimé] / Carine Julcour-Lebigue, Auteur ; Frédéric Augier, Auteur ; Harold Maffre, Auteur . - 2009 . - pp. 6811–6819.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6811–6819
Mots-clés : Liquid viscosity Wetting efficiency Résumé : An experimental parametric study on wetting efficiency is reported which evaluates the influence of liquid viscosity, as well as the effect of particle size(/shape) and bed porosity (εB), separately. A 10-fold increase of liquid viscosity improves slightly catalyst wetting (by about 10%), while an increase of either bed porosity or particle size has the opposite effect. Wetting efficiency is reduced by about 0.1 for an increase of εB from 0.38 and 0.40 due to a change of particle size from 1.8 to 7 × 10−3 m while the decrease is only 0.05 for a similar variation of εB (0.38−0.41) with the same particles. The effect of particle shape (cylindrical/trilobe extrudates or spheres) appears very small in the investigated conditions. A new correlation for wetting efficiency is proposed, using a bounded function and only three dimensionless groups (liquid Froude and Morton numbers and bed porosity). This correlation is able to predict wetting efficiency with a very good precision on a large database, provided wetting liquids are used. Adding fines in the fixed bed is also examined, and its positive effect can be correlated with the size ratio between catalyst particles and fines. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002443 Exemplaires
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Titre : Mixing with jets in cross-flow Type de document : texte imprimé Auteurs : Manoj T. Kandakure, Auteur ; Vivek C. Patkar, Auteur ; Ashwin W. Patwardhan, Auteur Année de publication : 2009 Article en page(s) : pp. 6820–6829 Note générale : Chemistry chemistry Langues : Anglais (eng) Mots-clés : Mixing Cross-flow Jets Computational fluid dynamics modeling Résumé : Mixing of gaseous species using jets in cross-flow is investigated with the help of computational fluid dynamics (CFD) modeling. This situation is encountered in a variety of industrial situations such as combustion, chemical vapor deposition, etc. Such operations are carried out in a specially designed chamber/mixer. For example, hydrocarbons are mixed with oxygen prior to oxidation reactions, in a specially designed oxygen mixer. In the present work, CFD simulations have been carried out for the mixing of two gaseous streams in a mixer. The model has been validated with experimental data reported in the past literature. The effects of different geometric configurations (hole diameter, number of holes) and operating conditions (velocity ratio) on the mixing process have been investigated. The model has helped in the identification of the key parameters in the design of such mixers. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801863a
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6820–6829[article] Mixing with jets in cross-flow [texte imprimé] / Manoj T. Kandakure, Auteur ; Vivek C. Patkar, Auteur ; Ashwin W. Patwardhan, Auteur . - 2009 . - pp. 6820–6829.
Chemistry chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6820–6829
Mots-clés : Mixing Cross-flow Jets Computational fluid dynamics modeling Résumé : Mixing of gaseous species using jets in cross-flow is investigated with the help of computational fluid dynamics (CFD) modeling. This situation is encountered in a variety of industrial situations such as combustion, chemical vapor deposition, etc. Such operations are carried out in a specially designed chamber/mixer. For example, hydrocarbons are mixed with oxygen prior to oxidation reactions, in a specially designed oxygen mixer. In the present work, CFD simulations have been carried out for the mixing of two gaseous streams in a mixer. The model has been validated with experimental data reported in the past literature. The effects of different geometric configurations (hole diameter, number of holes) and operating conditions (velocity ratio) on the mixing process have been investigated. The model has helped in the identification of the key parameters in the design of such mixers. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801863a Exemplaires
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Titre : Use of pressure fluctuations to determine online the regime of gas-solids suspensions from incipient fluidization to transport Type de document : texte imprimé Auteurs : Miloslav Hartman, Auteur ; Otakar Trnka, Auteur ; Karel Svoboda, Auteur Année de publication : 2009 Article en page(s) : pp. 6830–6835 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas-solids suspensions Pressure fluctuating signal Fluidization Résumé : A novel quantity, based on the concept of symmetry of the sampled pressure fluctuating signal, is developed and incorporated into our extended fluctuation model of fluidized gas−solid suspensions. The new measure of the signal symmetry makes it possible to define the transition from the final bubbling regime to the onset of turbulence in the bed. Experimental measurements were performed in a transparent glass, 6-m-tall column with an inner diameter (i.d.) of 0.08 m. Three different kinds of solids were employed in the experiments: ceramsite (particle size 1.0−1.25 mm; group D particles; spoutable particles), glass beads (particle size 0.8−1.00 mm; group D particles), and high-calcium, coarse-grained limestone (particle size 0.50−0.65 mm; group B powder; sandlike particles). It was discovered that also the different bubbling regimes and the starting point of dilute (entrainment) regimes can be identified with the aid of the proposed method. The development of the diluted beds is considerably influenced by the architecture and configuration of the top of the fluidization column. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900055x
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6830–6835[article] Use of pressure fluctuations to determine online the regime of gas-solids suspensions from incipient fluidization to transport [texte imprimé] / Miloslav Hartman, Auteur ; Otakar Trnka, Auteur ; Karel Svoboda, Auteur . - 2009 . - pp. 6830–6835.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6830–6835
Mots-clés : Gas-solids suspensions Pressure fluctuating signal Fluidization Résumé : A novel quantity, based on the concept of symmetry of the sampled pressure fluctuating signal, is developed and incorporated into our extended fluctuation model of fluidized gas−solid suspensions. The new measure of the signal symmetry makes it possible to define the transition from the final bubbling regime to the onset of turbulence in the bed. Experimental measurements were performed in a transparent glass, 6-m-tall column with an inner diameter (i.d.) of 0.08 m. Three different kinds of solids were employed in the experiments: ceramsite (particle size 1.0−1.25 mm; group D particles; spoutable particles), glass beads (particle size 0.8−1.00 mm; group D particles), and high-calcium, coarse-grained limestone (particle size 0.50−0.65 mm; group B powder; sandlike particles). It was discovered that also the different bubbling regimes and the starting point of dilute (entrainment) regimes can be identified with the aid of the proposed method. The development of the diluted beds is considerably influenced by the architecture and configuration of the top of the fluidization column. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900055x Exemplaires
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Titre : Prediction of vapor-liquid equilibrium at high pressure using a new excess free energy mixing rule coupled with the original UNIFAC method and the SRK equation of state Type de document : texte imprimé Auteurs : Zhen-hua Chen, Auteur ; Zhen Yao, Auteur ; Yan Li, Auteur Année de publication : 2009 Article en page(s) : pp. 6836–6845 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Low-pressure mixing rule UNIFAC method Soave-Redlich-Kwong equation EoS/GE predictive model Résumé : A new excess free energy mixing rule that employs a low-pressure reference state is proposed in this work. This new low-pressure mixing rule (LPMR), coupled with the original UNIFAC method and the Soave−Redlich−Kwong (SRK) equation of state (EoS), leads to an improved EoS/GE predictive model (LPMR−SRK model) that was applied to the high-pressure vapor−liquid phase equilibria of various systems including symmetric and asymmetric systems of n-alkanes with different gases (C2H6, C3H8, CO2, H2) and polar systems. The results are compared with those of other EoS/GE predictive models, such as the predictive Soave−Redlich−Kwong (PSRK), Chen-modified PSRK (MPSRK), volume-translated Peng−Robinson group contribution equation of state (VTPR), and linear combination of the Vidal and Michelsen rules (LCVM) models. It is demonstrated that LPMR−SRK method gives similar accuracy as the PSRK approach for symmetric or slightly asymmetric systems and gives better results than the MPSRK, VTPR, and LCVM models. For highly asymmetric nonpolar systems, the results indicate that the LPMR−SRK method has an accuracy similar to or slightly better than that of the MPSRK and VTPR models and gives a much better performance than the PSRK model. Furthermore, the LPMR−SRK approach is competitive with or better than the LCVM approach, except for some CO2/heavy alkane systems. In addition, although it is slightly inferior to the PSRK and LCVM approaches, the LPMR−SRK method can still provide satisfactory descriptions of polar systems that are more accurate than those of the MPSRK and VTPR models. Moreover, three ternary and one quaternary systems can also be predicted successfully by the LPMR−SRK method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900111h
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6836–6845[article] Prediction of vapor-liquid equilibrium at high pressure using a new excess free energy mixing rule coupled with the original UNIFAC method and the SRK equation of state [texte imprimé] / Zhen-hua Chen, Auteur ; Zhen Yao, Auteur ; Yan Li, Auteur . - 2009 . - pp. 6836–6845.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6836–6845
Mots-clés : Low-pressure mixing rule UNIFAC method Soave-Redlich-Kwong equation EoS/GE predictive model Résumé : A new excess free energy mixing rule that employs a low-pressure reference state is proposed in this work. This new low-pressure mixing rule (LPMR), coupled with the original UNIFAC method and the Soave−Redlich−Kwong (SRK) equation of state (EoS), leads to an improved EoS/GE predictive model (LPMR−SRK model) that was applied to the high-pressure vapor−liquid phase equilibria of various systems including symmetric and asymmetric systems of n-alkanes with different gases (C2H6, C3H8, CO2, H2) and polar systems. The results are compared with those of other EoS/GE predictive models, such as the predictive Soave−Redlich−Kwong (PSRK), Chen-modified PSRK (MPSRK), volume-translated Peng−Robinson group contribution equation of state (VTPR), and linear combination of the Vidal and Michelsen rules (LCVM) models. It is demonstrated that LPMR−SRK method gives similar accuracy as the PSRK approach for symmetric or slightly asymmetric systems and gives better results than the MPSRK, VTPR, and LCVM models. For highly asymmetric nonpolar systems, the results indicate that the LPMR−SRK method has an accuracy similar to or slightly better than that of the MPSRK and VTPR models and gives a much better performance than the PSRK model. Furthermore, the LPMR−SRK approach is competitive with or better than the LCVM approach, except for some CO2/heavy alkane systems. In addition, although it is slightly inferior to the PSRK and LCVM approaches, the LPMR−SRK method can still provide satisfactory descriptions of polar systems that are more accurate than those of the MPSRK and VTPR models. Moreover, three ternary and one quaternary systems can also be predicted successfully by the LPMR−SRK method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900111h Exemplaires
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Titre : Computational study of flow regimes in vertical pneumatic conveying Type de document : texte imprimé Auteurs : S. B. Kuang, Auteur ; A. B. Yu, Auteur ; Z. S. Zou, Auteur Année de publication : 2009 Article en page(s) : pp. 6846–6858 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pneumatic conveying Flow regimes Three-dimensional numerical study Résumé : Pneumatic conveying is an important technology in industries to transport bulk materials from one location to another. Different flow regimes have been observed in such a transportation process depending on operational conditions, but the underlying fundamentals are not clear. This paper presents a three-dimensional numerical study of vertical pneumatic conveying by a combined approach of discrete element model for particles and computational fluid dynamics for gas. The approach is verified by comparing the calculated and measured results in terms of particle flow pattern and gas pressure drop. It is shown that flow regimes usually encountered in vertical pneumatic conveying and their corresponding phase diagram can be reproduced. Then forces governing the behavior of particles, such as the particle−particle, particle−fluid, and particle−wall forces, are analyzed in detail. It is shown that the roles of these forces vary with flow regimes. A new phase diagram is proposed in terms of the key forces, which can successfully identify dilute-phase flow and dense-phase flow in vertical pneumatic conveying. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900230s
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6846–6858[article] Computational study of flow regimes in vertical pneumatic conveying [texte imprimé] / S. B. Kuang, Auteur ; A. B. Yu, Auteur ; Z. S. Zou, Auteur . - 2009 . - pp. 6846–6858.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6846–6858
Mots-clés : Pneumatic conveying Flow regimes Three-dimensional numerical study Résumé : Pneumatic conveying is an important technology in industries to transport bulk materials from one location to another. Different flow regimes have been observed in such a transportation process depending on operational conditions, but the underlying fundamentals are not clear. This paper presents a three-dimensional numerical study of vertical pneumatic conveying by a combined approach of discrete element model for particles and computational fluid dynamics for gas. The approach is verified by comparing the calculated and measured results in terms of particle flow pattern and gas pressure drop. It is shown that flow regimes usually encountered in vertical pneumatic conveying and their corresponding phase diagram can be reproduced. Then forces governing the behavior of particles, such as the particle−particle, particle−fluid, and particle−wall forces, are analyzed in detail. It is shown that the roles of these forces vary with flow regimes. A new phase diagram is proposed in terms of the key forces, which can successfully identify dilute-phase flow and dense-phase flow in vertical pneumatic conveying. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900230s Exemplaires
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Titre : Mixing and dissolution times for a cowles disk agitator in large-scale emulsion preparation Type de document : texte imprimé Auteurs : Thomas L. Rodgers, Auteur ; Michael Cooke, Auteur ; Flor R. Siperstein, Auteur Année de publication : 2009 Article en page(s) : pp. 6859–6868 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Emulsions Viscous fluids Dissolution times Non-Newtonian highly viscous surfactant Résumé : During the preparation of emulsions, it is often desirable to dissolve highly viscous fluids, such as surfactants or other additives, into an aqueous phase. In this work we measure dissolution times for a non-Newtonian highly viscous surfactant (sodium laureth sulfate) in water using vessels of different diameter (D = 0.9 and D = 0.15 m) with high shear disk agitators (D/T = 1/3 and 0.62). To monitor the dissolution times, we use a volume averaged conductivity obtained by 3D electrical resistance tomography. We compare the validity of the method and highlight the difference between dissolution times for highly viscous fluids and blending times for tracers with the same viscosity as water. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900286s
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6859–6868[article] Mixing and dissolution times for a cowles disk agitator in large-scale emulsion preparation [texte imprimé] / Thomas L. Rodgers, Auteur ; Michael Cooke, Auteur ; Flor R. Siperstein, Auteur . - 2009 . - pp. 6859–6868.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6859–6868
Mots-clés : Emulsions Viscous fluids Dissolution times Non-Newtonian highly viscous surfactant Résumé : During the preparation of emulsions, it is often desirable to dissolve highly viscous fluids, such as surfactants or other additives, into an aqueous phase. In this work we measure dissolution times for a non-Newtonian highly viscous surfactant (sodium laureth sulfate) in water using vessels of different diameter (D = 0.9 and D = 0.15 m) with high shear disk agitators (D/T = 1/3 and 0.62). To monitor the dissolution times, we use a volume averaged conductivity obtained by 3D electrical resistance tomography. We compare the validity of the method and highlight the difference between dissolution times for highly viscous fluids and blending times for tracers with the same viscosity as water. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900286s Exemplaires
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Titre : Supercritical carbon dioxide drying of methanol-zinc borate mixtures Type de document : texte imprimé Auteurs : Gonen, Mehmet, Auteur ; Balkose, Devrim, Auteur ; Gupta, Ram B., Auteur Année de publication : 2009 Article en page(s) : pp. 6869–6876 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon dioxide drying Methanol-wetted zinc borates X-ray powder diffraction Thermo gravimetric analysis Fourier transform infrared spectroscopy Elemental Scanning electron microscopy Résumé : Supercritical carbon dioxide (CO2) drying of zinc borate species was investigated to evaluate possible chemical alterations in the product during the drying. Methanol-wetted zinc borates produced either from borax decahydrate and zinc nitrate hexahydrate (2ZnO·3B2O3·7H2O) or from zinc oxide and boric acid (2ZnO·3B2O3·3H2O) were dried by both conventional and supercritical carbon dioxide drying methods. Zinc borate samples dried by both techniques were characterized using analytical titration, X-ray powder diffraction (XRD), thermo gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, elemental analysis, and scanning electron microscopy (SEM). It was found that while zinc borate obtained from zinc oxide and boric acid did not have any chemical interaction with CO2, carbonates were formed on the surface of zinc borate obtained from borax decahydrate and zinc nitrate hexahydrate. The main factor for the carbonate formation during supercritical CO2 drying is anticipated as the structural differences of zinc borate species. CO2 is a nonpolar solvent, and it does not usually react with polar substances unless water is present in the medium. While 2ZnO·3B2O3·3H2O had three bound OH groups, 2ZnO·3B2O3·7H2O had five bound OH groups and one mole of water of crystallization. It is proposed that the water of crystallization reacts with CO2 forming carbonic acid. Then, carbonic acid, which is stronger than boric acid, substitutes borate ions from their zinc salts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9003046
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6869–6876[article] Supercritical carbon dioxide drying of methanol-zinc borate mixtures [texte imprimé] / Gonen, Mehmet, Auteur ; Balkose, Devrim, Auteur ; Gupta, Ram B., Auteur . - 2009 . - pp. 6869–6876.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6869–6876
Mots-clés : Carbon dioxide drying Methanol-wetted zinc borates X-ray powder diffraction Thermo gravimetric analysis Fourier transform infrared spectroscopy Elemental Scanning electron microscopy Résumé : Supercritical carbon dioxide (CO2) drying of zinc borate species was investigated to evaluate possible chemical alterations in the product during the drying. Methanol-wetted zinc borates produced either from borax decahydrate and zinc nitrate hexahydrate (2ZnO·3B2O3·7H2O) or from zinc oxide and boric acid (2ZnO·3B2O3·3H2O) were dried by both conventional and supercritical carbon dioxide drying methods. Zinc borate samples dried by both techniques were characterized using analytical titration, X-ray powder diffraction (XRD), thermo gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, elemental analysis, and scanning electron microscopy (SEM). It was found that while zinc borate obtained from zinc oxide and boric acid did not have any chemical interaction with CO2, carbonates were formed on the surface of zinc borate obtained from borax decahydrate and zinc nitrate hexahydrate. The main factor for the carbonate formation during supercritical CO2 drying is anticipated as the structural differences of zinc borate species. CO2 is a nonpolar solvent, and it does not usually react with polar substances unless water is present in the medium. While 2ZnO·3B2O3·3H2O had three bound OH groups, 2ZnO·3B2O3·7H2O had five bound OH groups and one mole of water of crystallization. It is proposed that the water of crystallization reacts with CO2 forming carbonic acid. Then, carbonic acid, which is stronger than boric acid, substitutes borate ions from their zinc salts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9003046 Exemplaires
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Titre : Tuning the interaction parameter for the soave-redlich-kwong equation of state using the critical end points Type de document : texte imprimé Auteurs : Yang, Quan, Auteur ; Yigui Li, Auteur ; Shenlin Zhu, Auteur Année de publication : 2009 Article en page(s) : pp. 6877–6881 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Heavy oil Catalytic cracking Phase behavior Résumé : In the petroleum industry, to solve problems such as the design of the catalytic cracking of heavy oil, correct knowledge of the phase behavior is essential. As a benchmark where the number of degrees of freedom for binary mixtures is zero, the critical end points can represent the type of phase behavior of the binary mixtures according to van Konynenburg and Scott’s classification scheme (van Konynenburg, P. H. and Scott, R. L. Philos. Trans. R. Soc. London A 1980, 298, 495−540). Calculating the phase behavior of binary mixtures using interaction parameters evaluated by other methods can cause wrong determinations of the type of phase behavior. The critical end points were employed to fit the interaction parameters for binary mixtures in the critical state at high pressure. The molar Gibbs energy of mixing was evaluated to locate the ranges of values for the interaction parameters where exploration for the critical end point would not fail. The phase behavior at the critical end point is rather complex. Based on the Soave−Redlich−Kwong equation of state, the method developed by Heidemann and Khalil for calculating critical properties (Heidemann, R. A. and Khalil, A. M. AIChE J. 1980, 26, 769−780) was used to compute the critical points. A technique for determining the equilibrium phase of the critical point and thus determining the critical end point, which was difficult to evaluate, using the tangent plane criterion was developed. The developed algorithm was found to be rather stable and to converge rather quickly. The critical end points of different nonpolar, polar, and associating binary mixtures were calculated employing this algorithm. According to the calculation results and the experimental data for the critical end points, the interaction parameters were fitted successfully. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900069t
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6877–6881[article] Tuning the interaction parameter for the soave-redlich-kwong equation of state using the critical end points [texte imprimé] / Yang, Quan, Auteur ; Yigui Li, Auteur ; Shenlin Zhu, Auteur . - 2009 . - pp. 6877–6881.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6877–6881
Mots-clés : Heavy oil Catalytic cracking Phase behavior Résumé : In the petroleum industry, to solve problems such as the design of the catalytic cracking of heavy oil, correct knowledge of the phase behavior is essential. As a benchmark where the number of degrees of freedom for binary mixtures is zero, the critical end points can represent the type of phase behavior of the binary mixtures according to van Konynenburg and Scott’s classification scheme (van Konynenburg, P. H. and Scott, R. L. Philos. Trans. R. Soc. London A 1980, 298, 495−540). Calculating the phase behavior of binary mixtures using interaction parameters evaluated by other methods can cause wrong determinations of the type of phase behavior. The critical end points were employed to fit the interaction parameters for binary mixtures in the critical state at high pressure. The molar Gibbs energy of mixing was evaluated to locate the ranges of values for the interaction parameters where exploration for the critical end point would not fail. The phase behavior at the critical end point is rather complex. Based on the Soave−Redlich−Kwong equation of state, the method developed by Heidemann and Khalil for calculating critical properties (Heidemann, R. A. and Khalil, A. M. AIChE J. 1980, 26, 769−780) was used to compute the critical points. A technique for determining the equilibrium phase of the critical point and thus determining the critical end point, which was difficult to evaluate, using the tangent plane criterion was developed. The developed algorithm was found to be rather stable and to converge rather quickly. The critical end points of different nonpolar, polar, and associating binary mixtures were calculated employing this algorithm. According to the calculation results and the experimental data for the critical end points, the interaction parameters were fitted successfully. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900069t Exemplaires
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Titre : Chemically modified chicken feather as sorbent for removing toxic chromium(VI) ions Type de document : texte imprimé Auteurs : Ping Sun, Auteur ; Zhao-Tie Liu, Auteur ; Zhong-Wen Liu, Auteur Année de publication : 2009 Article en page(s) : pp. 6882–6889 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Chromium(VI) ions Chicken feathers Résumé : To improve the sorption capacity of Cr(VI) ions, chicken feathers (CFs) were chemically treated by several methods: (1) To clarify the changes in the structure and morphology of CFs, CFs were treated with aqueous NaOH solutions of varying concentrations. The results suggest that reactions occur on the surface rather than in the interior of the CFs and that keratin fragments exfoliate from the CF surface layer by layer and then dissolve in aqueous solution. (2) Keratin fragments could be rejoined to the CF surface by cross-linking with epichlorohydrin (Epi) through a series of ring-opening, recyclization, and ring-opening reactions of Epi in aqueous NaOH solution, and Epi-modified CF (EpiCF) was obtained. (3) CFs were functionalized with ethylenediamine (EA) in aqueous NaOH solution by cross-linking with Epi (EAEpiCF). The structure and properties of chemically treated CFs were investigated by FT-IR spectroscopy, XRD, SEM, elemental analysis, and water contact-angle measurements. CFs treated with NaOH were found to be similar in structure and properties to each other and exhibited a relatively low sorption capacity for removal of Cr(VI) ions from water, but a higher capacity than raw CFs. EpiCF exhibited an excellent capacity for adsorbing relatively low concentrations (10 ppm) of Cr(VI) ions but a low sorption capacity for Cu(II) ions in water. EAEpiCF was found to be hydrophilic and to exhibit 90% efficiency for removing Cr(VI) ions in the concentration range of 10−80 ppm but to have a low sorption capacity for Cu(II) in water. Equilibrium sorption isotherms for the raw and chemically treated CFs fit the Freundlich and Dubinin−Radushkevich (D−R) isotherm models; however, the Langmuir model was not able to describe the sorption behavior. The values of the free sorption energy (E) were calculated. The E values of NaOH-treated CFs were found to be similar to each other and much larger than that of raw CFs for the sorption of Cr(VI), and the sorption processes were found to be physical. The process of EpiCF adsorbing Cr(VI) ions from water is chemisorption, and that for Cu(II) ions is physisorption. The free sorption energy of EAEpiCF sorption of Cr(VI) ions was close to 8 kJ·mol−1 (7.274 kJ·mol−1), so that chemical interactions might exist between EAEpiCF and Cr(VI), whereas for Cu(II), the sorption process is physical adsorption. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900106h
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6882–6889[article] Chemically modified chicken feather as sorbent for removing toxic chromium(VI) ions [texte imprimé] / Ping Sun, Auteur ; Zhao-Tie Liu, Auteur ; Zhong-Wen Liu, Auteur . - 2009 . - pp. 6882–6889.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6882–6889
Mots-clés : Chromium(VI) ions Chicken feathers Résumé : To improve the sorption capacity of Cr(VI) ions, chicken feathers (CFs) were chemically treated by several methods: (1) To clarify the changes in the structure and morphology of CFs, CFs were treated with aqueous NaOH solutions of varying concentrations. The results suggest that reactions occur on the surface rather than in the interior of the CFs and that keratin fragments exfoliate from the CF surface layer by layer and then dissolve in aqueous solution. (2) Keratin fragments could be rejoined to the CF surface by cross-linking with epichlorohydrin (Epi) through a series of ring-opening, recyclization, and ring-opening reactions of Epi in aqueous NaOH solution, and Epi-modified CF (EpiCF) was obtained. (3) CFs were functionalized with ethylenediamine (EA) in aqueous NaOH solution by cross-linking with Epi (EAEpiCF). The structure and properties of chemically treated CFs were investigated by FT-IR spectroscopy, XRD, SEM, elemental analysis, and water contact-angle measurements. CFs treated with NaOH were found to be similar in structure and properties to each other and exhibited a relatively low sorption capacity for removal of Cr(VI) ions from water, but a higher capacity than raw CFs. EpiCF exhibited an excellent capacity for adsorbing relatively low concentrations (10 ppm) of Cr(VI) ions but a low sorption capacity for Cu(II) ions in water. EAEpiCF was found to be hydrophilic and to exhibit 90% efficiency for removing Cr(VI) ions in the concentration range of 10−80 ppm but to have a low sorption capacity for Cu(II) in water. Equilibrium sorption isotherms for the raw and chemically treated CFs fit the Freundlich and Dubinin−Radushkevich (D−R) isotherm models; however, the Langmuir model was not able to describe the sorption behavior. The values of the free sorption energy (E) were calculated. The E values of NaOH-treated CFs were found to be similar to each other and much larger than that of raw CFs for the sorption of Cr(VI), and the sorption processes were found to be physical. The process of EpiCF adsorbing Cr(VI) ions from water is chemisorption, and that for Cu(II) ions is physisorption. The free sorption energy of EAEpiCF sorption of Cr(VI) ions was close to 8 kJ·mol−1 (7.274 kJ·mol−1), so that chemical interactions might exist between EAEpiCF and Cr(VI), whereas for Cu(II), the sorption process is physical adsorption. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900106h Exemplaires
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Titre : Critical properties of ionic liquids. revisited Type de document : texte imprimé Auteurs : José O. Valderrama, Auteur ; Roberto E. Rojas, Auteur Année de publication : 2009 Article en page(s) : pp. 6890–6900 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ionic liquids Group contribution method Résumé : The group contribution method proposed by Valderrama and Robles in 2007 and extended by Valderrama et al. in 2008 to estimate the critical properties of ionic liquids is revised and new groups have been included. The method originally proposed has been used by several authors in applications such as high pressure phase equilibrium, density correlations, heat capacity estimations, and consistency tests for mixture data. Therefore, it is important to have a consistent and reliable method so all applications consider the same assumptions and values for the critical properties. The values previously reported by the authors are recalculated, unifying criteria for the names of the ionic liquids, for the assignment of the groups forming the molecules, and for the equivalence of groups. Also, a spreadsheet file that allows any reader to calculate the critical properties of any ionic liquid containing the 44 groups defined by the method is provided as Supporting Information. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900250g
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6890–6900[article] Critical properties of ionic liquids. revisited [texte imprimé] / José O. Valderrama, Auteur ; Roberto E. Rojas, Auteur . - 2009 . - pp. 6890–6900.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6890–6900
Mots-clés : Ionic liquids Group contribution method Résumé : The group contribution method proposed by Valderrama and Robles in 2007 and extended by Valderrama et al. in 2008 to estimate the critical properties of ionic liquids is revised and new groups have been included. The method originally proposed has been used by several authors in applications such as high pressure phase equilibrium, density correlations, heat capacity estimations, and consistency tests for mixture data. Therefore, it is important to have a consistent and reliable method so all applications consider the same assumptions and values for the critical properties. The values previously reported by the authors are recalculated, unifying criteria for the names of the ionic liquids, for the assignment of the groups forming the molecules, and for the equivalence of groups. Also, a spreadsheet file that allows any reader to calculate the critical properties of any ionic liquid containing the 44 groups defined by the method is provided as Supporting Information. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900250g Exemplaires
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Titre : Comments on "Joule-Thomson inversion curves and third virial coefficients for pure fluids from molecular-based models" and "predicted inversion curve and third virial coefficients of carbon dioxide at high temperatures" Type de document : texte imprimé Auteurs : Daniela Espinoza, Auteur ; Hugo Segura, Auteur ; Jaime Wisniak, Auteur Année de publication : 2009 Article en page(s) : pp. 6901–6903 Note générale : Chemical engineering Langues : Anglais (eng) Note de contenu : Correspondence En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900275w
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6901–6903[article] Comments on "Joule-Thomson inversion curves and third virial coefficients for pure fluids from molecular-based models" and "predicted inversion curve and third virial coefficients of carbon dioxide at high temperatures" [texte imprimé] / Daniela Espinoza, Auteur ; Hugo Segura, Auteur ; Jaime Wisniak, Auteur . - 2009 . - pp. 6901–6903.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6901–6903
Note de contenu : Correspondence En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900275w Exemplaires
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