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Vol. 48 N° 18 - Septembre 2009 [texte imprimé] . - 2010 . - p. 8313-8766 : ill. ; 28 cm. Chemical engineering Langues : Français (fre)
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Ajouter le résultat dans votre panierInfluence of sodium dodecyl sulfate presence on esterification of propylene glycol with lauric acid / Halina Szelag in Industrial & engineering chemistry research, Vol. 48 N° 18 (Septembre 2009)
Titre : Influence of sodium dodecyl sulfate presence on esterification of propylene glycol with lauric acid Type de document : texte imprimé Auteurs : Halina Szelag, Auteur ; Elwira Sadecka, Auteur Année de publication : 2010 Article en page(s) : pp. 8313–8319 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Sodium dodecyl sulfate Esterification Propylene glycol Lauric acid Résumé : In this study, the influence of sodium dodecyl sulfate (SDS) on the direct esterification of 1,2-propanediol (propylene glycol, PG) with dodecanoic acid (lauric acid, LA) was investigated. It was stated that formation of a mixed interfacial film of the anionic surfactant and synthesized monoacylpropyleneglycol (PGML) emulsifier lowers the interfacial tension between phases to produce a transparent microemulsion. Therefore, SDS was found to be effective in increasing the contact between reagents and, as a consequence, accelerating the reaction progress. The obtained products were liquid and transparent substances at room temperature. The particle size distribution of the formed microemulsion systems range from about 25−45 nm, depending on the concentration of surfactant in the reaction mixture. The hydrophilic−lipophilic properties of synthesized products were also studied. The concentration of SDS in the reaction mixture influenced the hydrophile−lipophile balance (HLB) values of the obtained emulsifiers. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019449
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8313–8319[article] Influence of sodium dodecyl sulfate presence on esterification of propylene glycol with lauric acid [texte imprimé] / Halina Szelag, Auteur ; Elwira Sadecka, Auteur . - 2010 . - pp. 8313–8319.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8313–8319
Mots-clés : Sodium dodecyl sulfate Esterification Propylene glycol Lauric acid Résumé : In this study, the influence of sodium dodecyl sulfate (SDS) on the direct esterification of 1,2-propanediol (propylene glycol, PG) with dodecanoic acid (lauric acid, LA) was investigated. It was stated that formation of a mixed interfacial film of the anionic surfactant and synthesized monoacylpropyleneglycol (PGML) emulsifier lowers the interfacial tension between phases to produce a transparent microemulsion. Therefore, SDS was found to be effective in increasing the contact between reagents and, as a consequence, accelerating the reaction progress. The obtained products were liquid and transparent substances at room temperature. The particle size distribution of the formed microemulsion systems range from about 25−45 nm, depending on the concentration of surfactant in the reaction mixture. The hydrophilic−lipophilic properties of synthesized products were also studied. The concentration of SDS in the reaction mixture influenced the hydrophile−lipophile balance (HLB) values of the obtained emulsifiers. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019449 Exemplaires
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Titre : Roles of hydrogen donors and organic selenides in inhibiting solid deposits from thermal stressing of n-dodecane and chinese RP-3 jet fuel Type de document : texte imprimé Auteurs : Wei Guo, Auteur ; Xiangwen Zhang, Auteur ; Guozhu Liu, Auteur Année de publication : 2010 Article en page(s) : pp. 8320–8327 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hydrocarbon fuels Hydrogen donors Organic selenides Résumé : Use of hydrocarbon fuels as coolants for future high-Mach aircraft is challenged by the formation of carbonaceous deposits during thermal stressing at high temperatures (>500 °C). Three hydrogen donors, tetralin (THN), α-tetralone (THNone), and benzyl alcohol (BzOH), and two organic selenides, diphenyl selenide (Ph2Se) and diphenyl diselenide (Ph2Se2), as well as their mixtures, are selected as thermally stable additives to inhibit the deposition from the thermal stressing of n-dodecane and Chinese RP-3 (No. 3 jet fuel). It is found that the amount of solid deposits from thermal stressing of RP-3 is reduced by 77.0% with the additive of Ph2Se2/THN/THNone. The carbonaceous solid is further characterized using temperature-programmed oxidation (TPO), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). It is revealed that hydrogen donor THN/THNone and organic selenides possibly reduce the carbon deposits through retarding the thermal cracking rate, blocking surface catalysis, and depressing reactivity of sulfur with the surface metals, as well as their synergistic effect. The morphologies of deposits also dramatically change after adding organic selenides or hydrogen donors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900735c
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8320–8327[article] Roles of hydrogen donors and organic selenides in inhibiting solid deposits from thermal stressing of n-dodecane and chinese RP-3 jet fuel [texte imprimé] / Wei Guo, Auteur ; Xiangwen Zhang, Auteur ; Guozhu Liu, Auteur . - 2010 . - pp. 8320–8327.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8320–8327
Mots-clés : Hydrocarbon fuels Hydrogen donors Organic selenides Résumé : Use of hydrocarbon fuels as coolants for future high-Mach aircraft is challenged by the formation of carbonaceous deposits during thermal stressing at high temperatures (>500 °C). Three hydrogen donors, tetralin (THN), α-tetralone (THNone), and benzyl alcohol (BzOH), and two organic selenides, diphenyl selenide (Ph2Se) and diphenyl diselenide (Ph2Se2), as well as their mixtures, are selected as thermally stable additives to inhibit the deposition from the thermal stressing of n-dodecane and Chinese RP-3 (No. 3 jet fuel). It is found that the amount of solid deposits from thermal stressing of RP-3 is reduced by 77.0% with the additive of Ph2Se2/THN/THNone. The carbonaceous solid is further characterized using temperature-programmed oxidation (TPO), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). It is revealed that hydrogen donor THN/THNone and organic selenides possibly reduce the carbon deposits through retarding the thermal cracking rate, blocking surface catalysis, and depressing reactivity of sulfur with the surface metals, as well as their synergistic effect. The morphologies of deposits also dramatically change after adding organic selenides or hydrogen donors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900735c Exemplaires
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Titre : Pretreatment of miscanthus x giganteus using the ethanol organosolv process for ethanol production Type de document : texte imprimé Auteurs : Nicolas Brosse, Auteur ; Sannigrahi, Poulomi, Auteur ; Arthur Ragauskas, Auteur Année de publication : 2010 Article en page(s) : pp. 8328–8334 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Miscanthus x giganteus Aqueous-ethanol organosolv treatment Résumé : A two-step procedure involving a dilute-acid presoaking step and an aqueous-ethanol organosolv treatment has been evaluated and optimized for the conversion of Miscanthus x giganteus (MxG). This process allowed for the efficient fractionation of the raw material into a cellulose-rich residue, an ethanol organosolv lignin fraction, and a water-soluble fraction mainly containing hemicellulose sugars. It was found that the presoaking step not only allowed a better recovery of xylans, but also enhanced the dissolution of lignin in the aqueous ethanol and the digestibility of the remaining cellulose by enzymes. The optimized conditions yielded a solid residue containing about 95% of the initial glucans, from which 98% was recovered after 48 h of enzymatic hydrolysis. In addition, 71% of the lignin was recovered as ethanol organosolv lignin (EOL), and the recovery of the xylans was equivalent to 73% of the xylose present in the raw Miscanthus. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9006672
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8328–8334[article] Pretreatment of miscanthus x giganteus using the ethanol organosolv process for ethanol production [texte imprimé] / Nicolas Brosse, Auteur ; Sannigrahi, Poulomi, Auteur ; Arthur Ragauskas, Auteur . - 2010 . - pp. 8328–8334.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8328–8334
Mots-clés : Miscanthus x giganteus Aqueous-ethanol organosolv treatment Résumé : A two-step procedure involving a dilute-acid presoaking step and an aqueous-ethanol organosolv treatment has been evaluated and optimized for the conversion of Miscanthus x giganteus (MxG). This process allowed for the efficient fractionation of the raw material into a cellulose-rich residue, an ethanol organosolv lignin fraction, and a water-soluble fraction mainly containing hemicellulose sugars. It was found that the presoaking step not only allowed a better recovery of xylans, but also enhanced the dissolution of lignin in the aqueous ethanol and the digestibility of the remaining cellulose by enzymes. The optimized conditions yielded a solid residue containing about 95% of the initial glucans, from which 98% was recovered after 48 h of enzymatic hydrolysis. In addition, 71% of the lignin was recovered as ethanol organosolv lignin (EOL), and the recovery of the xylans was equivalent to 73% of the xylose present in the raw Miscanthus. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9006672 Exemplaires
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Titre : Kinetics of the reaction of iron blast furnace slag/hydrated lime sorbents with SO2 at low temperatures : effects of the presence of CO2, O2, and NOx Type de document : texte imprimé Auteurs : Liu, Chiung-Fang, Auteur ; Shin-Min Shih, Auteur Année de publication : 2010 Article en page(s) : pp. 8335–8340 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CO2 O2 NOx Flue gas Differential fixed-bed reactor Résumé : The effects of the presence of CO2, O2, and NOx in the flue gas on the kinetics of the sulfation of blast furnace slag/hydrated lime sorbents at low temperatures were studied using a differential fixed-bed reactor. When O2 and NOx were not present simultaneously, the reaction kinetics was about the same as that under the gas mixtures containing SO2, H2O, and N2 only, being affected mainly by the relative humidity. The sulfation of sorbents can be described by the surface coverage model and the model equations derived for the latter case. When both O2 and NOx were present, the sulfation of sorbents was greatly enhanced, forming a great amount of sulfate in addition to sulfite. The surface coverage model is still valid in this case, but the model equations obtained show a more marked effect of relative humidity and negligible effects of SO2 concentration and temperature on the reaction. The effect of sorbent composition on the reaction kinetics was entirely represented by the effects of the initial specific surface area (Sg0) and the Ca molar content (M−1) of sorbent. The initial conversion rate of sorbent increased linearly with increasing Sg0, and the ultimate conversion increased linearly with increasing Sg0M−1. The model equations obtained in this work are applicable to describe the kinetics of the sulfation of the sorbents in the low-temperature dry and semidry flue gas desulfurization processes either with an upstream NOx removal unit or without. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900379c
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8335–8340[article] Kinetics of the reaction of iron blast furnace slag/hydrated lime sorbents with SO2 at low temperatures : effects of the presence of CO2, O2, and NOx [texte imprimé] / Liu, Chiung-Fang, Auteur ; Shin-Min Shih, Auteur . - 2010 . - pp. 8335–8340.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8335–8340
Mots-clés : CO2 O2 NOx Flue gas Differential fixed-bed reactor Résumé : The effects of the presence of CO2, O2, and NOx in the flue gas on the kinetics of the sulfation of blast furnace slag/hydrated lime sorbents at low temperatures were studied using a differential fixed-bed reactor. When O2 and NOx were not present simultaneously, the reaction kinetics was about the same as that under the gas mixtures containing SO2, H2O, and N2 only, being affected mainly by the relative humidity. The sulfation of sorbents can be described by the surface coverage model and the model equations derived for the latter case. When both O2 and NOx were present, the sulfation of sorbents was greatly enhanced, forming a great amount of sulfate in addition to sulfite. The surface coverage model is still valid in this case, but the model equations obtained show a more marked effect of relative humidity and negligible effects of SO2 concentration and temperature on the reaction. The effect of sorbent composition on the reaction kinetics was entirely represented by the effects of the initial specific surface area (Sg0) and the Ca molar content (M−1) of sorbent. The initial conversion rate of sorbent increased linearly with increasing Sg0, and the ultimate conversion increased linearly with increasing Sg0M−1. The model equations obtained in this work are applicable to describe the kinetics of the sulfation of the sorbents in the low-temperature dry and semidry flue gas desulfurization processes either with an upstream NOx removal unit or without. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900379c Exemplaires
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Titre : Kinetics of ethylbenzene ethylation with ethanol over a ZSM-5-based catalyst in a riser simulator Type de document : texte imprimé Auteurs : S. M. Waziri, Auteur ; Al-Khattaf, S., Auteur Année de publication : 2010 Article en page(s) : pp. 8341–8348 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ethylbenzene Catalytic ethylation Fluidized-bed reactors Résumé : The catalytic ethylation of ethylbenzene with ethanol over ZSM-5 based catalyst has been investigated in a riser simulator that closely mimics the operation of fluidized-bed reactors. Experimental runs were conducted with a constant ethylbenzene to ethanol molar ratio of 1:1 over the temperature range of 300−500 °C and reaction times of 3−15 s. The effect of reaction conditions on the variation of ethylbenzene conversion, distribution of diethylbenzene isomers, and values of benzene/diethylbenzene ratios are reported. The results show that at low temperatures (300−400 °C) alkylation is the predominant reaction while at higher temperatures other competing reactions such as disproportionation and cracking are also important. On the basis of these observations, two mechanisms (one for low temperatures and the other for both low and high temperatures) were proposed to represent the ethylation of ethylbenzene with ethanol. The experimental results were modeled using a quasi-steady state approximation with catalyst deactivation function based on a time on stream (TOS) model. Kinetic parameters for ethylation of ethylbenzene with ethanol, disproportionation of ethylbenzene, and cracking of diethylbenzene were estimated by nonlinear regression analysis. The apparent activation energies were found to increase as follows: Ee En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900497d
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8341–8348[article] Kinetics of ethylbenzene ethylation with ethanol over a ZSM-5-based catalyst in a riser simulator [texte imprimé] / S. M. Waziri, Auteur ; Al-Khattaf, S., Auteur . - 2010 . - pp. 8341–8348.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8341–8348
Mots-clés : Ethylbenzene Catalytic ethylation Fluidized-bed reactors Résumé : The catalytic ethylation of ethylbenzene with ethanol over ZSM-5 based catalyst has been investigated in a riser simulator that closely mimics the operation of fluidized-bed reactors. Experimental runs were conducted with a constant ethylbenzene to ethanol molar ratio of 1:1 over the temperature range of 300−500 °C and reaction times of 3−15 s. The effect of reaction conditions on the variation of ethylbenzene conversion, distribution of diethylbenzene isomers, and values of benzene/diethylbenzene ratios are reported. The results show that at low temperatures (300−400 °C) alkylation is the predominant reaction while at higher temperatures other competing reactions such as disproportionation and cracking are also important. On the basis of these observations, two mechanisms (one for low temperatures and the other for both low and high temperatures) were proposed to represent the ethylation of ethylbenzene with ethanol. The experimental results were modeled using a quasi-steady state approximation with catalyst deactivation function based on a time on stream (TOS) model. Kinetic parameters for ethylation of ethylbenzene with ethanol, disproportionation of ethylbenzene, and cracking of diethylbenzene were estimated by nonlinear regression analysis. The apparent activation energies were found to increase as follows: Ee En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900497d Exemplaires
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Titre : Polypropylene and ethylene-propylene copolymer reactor alloys prepared by metallocene/ziegler-natta hybrid catalyst Type de document : texte imprimé Auteurs : Lie Lu, Auteur ; Hong Fan, Auteur ; Bo-Geng Li, Auteur Année de publication : 2010 Article en page(s) : pp. 8349–8355 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polypropylene Ethylene− propylene rubber reactor Propylene homopolymerization Metallocene activation copolymerization Résumé : Polypropylene/ethylene−propylene rubber (PP/EPR) reactor alloys were prepared with a metallocene/Ziegler−Natta hybrid catalyst system (rac-Et(Ind)2ZrCl2/TiCl4/MgCl2) using a process composed of three stages: propylene homopolymerization, metallocene activation, and ethylene−propylene copolymerization. A series of alloy samples were produced and characterized at various copolymerization conditions by varying the methylaluminoxane (MAO)/Zr ratio and monomer composition. It was shown that the metallocene/Ziegler−Natta hybrid system exhibited the features of both metallocene and Ziegler−Natta catalysts during copolymerization. The hybrid catalyst had better ability in incorporating α-olefin than the Ziegler−Natta catalyst owing to the action of metallocene active sites. DSC and IR analyses suggested that EPR in the alloys became random with increased MAO/Zr ratio. In addition, reducing the ethylene content in the feed decreased the activity and promoted the production of random copolymers. An operation window of reaction conditions was identified for the preparation of well-dispersed spherical PP/EPR reactor alloy particles containing up to about 40 wt % EPR. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900579h
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8349–8355[article] Polypropylene and ethylene-propylene copolymer reactor alloys prepared by metallocene/ziegler-natta hybrid catalyst [texte imprimé] / Lie Lu, Auteur ; Hong Fan, Auteur ; Bo-Geng Li, Auteur . - 2010 . - pp. 8349–8355.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8349–8355
Mots-clés : Polypropylene Ethylene− propylene rubber reactor Propylene homopolymerization Metallocene activation copolymerization Résumé : Polypropylene/ethylene−propylene rubber (PP/EPR) reactor alloys were prepared with a metallocene/Ziegler−Natta hybrid catalyst system (rac-Et(Ind)2ZrCl2/TiCl4/MgCl2) using a process composed of three stages: propylene homopolymerization, metallocene activation, and ethylene−propylene copolymerization. A series of alloy samples were produced and characterized at various copolymerization conditions by varying the methylaluminoxane (MAO)/Zr ratio and monomer composition. It was shown that the metallocene/Ziegler−Natta hybrid system exhibited the features of both metallocene and Ziegler−Natta catalysts during copolymerization. The hybrid catalyst had better ability in incorporating α-olefin than the Ziegler−Natta catalyst owing to the action of metallocene active sites. DSC and IR analyses suggested that EPR in the alloys became random with increased MAO/Zr ratio. In addition, reducing the ethylene content in the feed decreased the activity and promoted the production of random copolymers. An operation window of reaction conditions was identified for the preparation of well-dispersed spherical PP/EPR reactor alloy particles containing up to about 40 wt % EPR. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900579h Exemplaires
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Titre : Catalytic hydrogenation of aqueous nitrate over Pd−Cu/ZrO2 catalysts Type de document : texte imprimé Auteurs : Zhaoyi Xu, Auteur ; Liqiang Chen, Auteur ; Yun Shao, Auteur Année de publication : 2010 Article en page(s) : pp. 8356–8363 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : ZrO2 supports Aqueous nitrate Pd− Cu bimetallic catalysts Résumé : ZrO2 supports with different properties were prepared, and the hydrogenation of aqueous nitrate catalyzed by ZrO2 supported Pd−Cu bimetallic catalysts was investigated. The results showed that ZrO2 support calcined at 573 K was unstable during the preparation of the bimetallic catalyst. Increasing calcination temperature led to the increase of particle size of ZrO2 support. In addition, using ZrO2 calcined at 973 K as the support resulted in the increase of metal particle sizes and the increased content of bimetallic ensembles at the expense of monometallic Pd. The bimetallic catalyst with ZrO2 calcined at 773 K as the support exhibited higher catalytic activity and N2 selectivity for the reduction of aqueous nitrate as compared to the bimetallic catalyst with ZrO2 calcined at 573 or 973 K as the support. The activity and selectivity of ZrO2 supported bimetallic catalysts for nitrate reduction also depended on the Pd/Cu ratio. Decreasing Pd/Cu ratio led to the decrease of the amount of monometallic Pd sites and to the increase of the content of Pd−Cu ensembles. The bimetallic catalyst with Pd/Cu ratio of 4/1 showed the optimum activity and N2 selectivity for the reduction of aqueous nitrate. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005854
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8356–8363[article] Catalytic hydrogenation of aqueous nitrate over Pd−Cu/ZrO2 catalysts [texte imprimé] / Zhaoyi Xu, Auteur ; Liqiang Chen, Auteur ; Yun Shao, Auteur . - 2010 . - pp. 8356–8363.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8356–8363
Mots-clés : ZrO2 supports Aqueous nitrate Pd− Cu bimetallic catalysts Résumé : ZrO2 supports with different properties were prepared, and the hydrogenation of aqueous nitrate catalyzed by ZrO2 supported Pd−Cu bimetallic catalysts was investigated. The results showed that ZrO2 support calcined at 573 K was unstable during the preparation of the bimetallic catalyst. Increasing calcination temperature led to the increase of particle size of ZrO2 support. In addition, using ZrO2 calcined at 973 K as the support resulted in the increase of metal particle sizes and the increased content of bimetallic ensembles at the expense of monometallic Pd. The bimetallic catalyst with ZrO2 calcined at 773 K as the support exhibited higher catalytic activity and N2 selectivity for the reduction of aqueous nitrate as compared to the bimetallic catalyst with ZrO2 calcined at 573 or 973 K as the support. The activity and selectivity of ZrO2 supported bimetallic catalysts for nitrate reduction also depended on the Pd/Cu ratio. Decreasing Pd/Cu ratio led to the decrease of the amount of monometallic Pd sites and to the increase of the content of Pd−Cu ensembles. The bimetallic catalyst with Pd/Cu ratio of 4/1 showed the optimum activity and N2 selectivity for the reduction of aqueous nitrate. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005854 Exemplaires
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Titre : Steam reforming of methanol with Sm2O3−CeO2-supported palladium catalysts : influence of the thermal treatments of catalyst and support Type de document : texte imprimé Auteurs : Luisa M. Gómez-Sainero, Auteur ; Richard T. Baker, Auteur ; Arturo J. Vizcaíno, Auteur Année de publication : 2010 Article en page(s) : pp. 8364–8372 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Methanol Steam reforming Sm2O3− CeO2-supported palladium catalysts Thermal treatments Résumé : The design of new anode materials to promote the reforming of methanol is important for the development of intermediate temperature direct methanol solid oxide fuel cells. A previous study showed Pd/CeO2−Sm2O3 to be a good candidate. Here, the influence of the calcination pretreatment of the support and the reduction temperature of the catalyst on the steam reforming of methanol are investigated, as they can become key factors in the performance of the catalyst. Conversion, H2 yield, and TOF were considerably higher when the support was calcined at 800 °C (Pd/CS-800) instead of 1000 °C (Pd/CS-1000). Characterization results suggest a stronger interaction of Pd particles with the support in Pd/CS-1000, which hinders its accessibility to the gas atmosphere, and a less homogeneous distribution of Pd particles. In both cases, the activity increases on increasing the reduction temperature from 400 to 500 °C. In addition, these catalysts were highly resistant to deactivation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900630z
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8364–8372[article] Steam reforming of methanol with Sm2O3−CeO2-supported palladium catalysts : influence of the thermal treatments of catalyst and support [texte imprimé] / Luisa M. Gómez-Sainero, Auteur ; Richard T. Baker, Auteur ; Arturo J. Vizcaíno, Auteur . - 2010 . - pp. 8364–8372.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8364–8372
Mots-clés : Methanol Steam reforming Sm2O3− CeO2-supported palladium catalysts Thermal treatments Résumé : The design of new anode materials to promote the reforming of methanol is important for the development of intermediate temperature direct methanol solid oxide fuel cells. A previous study showed Pd/CeO2−Sm2O3 to be a good candidate. Here, the influence of the calcination pretreatment of the support and the reduction temperature of the catalyst on the steam reforming of methanol are investigated, as they can become key factors in the performance of the catalyst. Conversion, H2 yield, and TOF were considerably higher when the support was calcined at 800 °C (Pd/CS-800) instead of 1000 °C (Pd/CS-1000). Characterization results suggest a stronger interaction of Pd particles with the support in Pd/CS-1000, which hinders its accessibility to the gas atmosphere, and a less homogeneous distribution of Pd particles. In both cases, the activity increases on increasing the reduction temperature from 400 to 500 °C. In addition, these catalysts were highly resistant to deactivation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900630z Exemplaires
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Titre : Treatment of trichloroethylene by adsorption and persulfate oxidation in batch studies Type de document : texte imprimé Auteurs : Chenju Liang, Auteur ; Ya-Ting Lin, Auteur ; Wu-Hang Shih, Auteur Année de publication : 2010 Article en page(s) : pp. 8373–8380 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Trichloroethylene Activated carbon Résumé : For remediation of trichloroethylene (TCE) contaminated groundwater, activated carbon (AC) has been used to adsorb and reduce the TCE concentration and to manage contaminant migration. Additionally, AC may also act as an activator of the electron-transfer mediator in activating persulfate anion (S2O82−) to generate sulfate radical (SO4−·) for contaminant destruction. The objective of the present research was to examine the combined use of AC and persulfate to treat TCE. The degradation of persulfate in the presence of AC follows a first-order kinetic behavior, and the faster persulfate degradation is observed when elevated AC dosage is used. Higher initial persulfate concentration results in a decrease of the persulfate degradation rate. Upon persulfate oxidation, the AC surface properties are altered including: an increase in acidity of surface concentration, a decrease in pHzpc, and a slight decrease in the surface area. The results of a study of adsorption kinetics and isotherms suggest that the adsorption behavior for the original AC fits the pseudo-second-order kinetic model while the pseudo-first-order kinetic model is suitable for predicting oxidized AC performance. During the persulfate oxidation of TCE with AC as an activator, studies show that TCE removal can be a net result of adsorption and oxidation, in which a partial mineralization of TCE to release chloride occurs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900841k
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8373–8380[article] Treatment of trichloroethylene by adsorption and persulfate oxidation in batch studies [texte imprimé] / Chenju Liang, Auteur ; Ya-Ting Lin, Auteur ; Wu-Hang Shih, Auteur . - 2010 . - pp. 8373–8380.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8373–8380
Mots-clés : Trichloroethylene Activated carbon Résumé : For remediation of trichloroethylene (TCE) contaminated groundwater, activated carbon (AC) has been used to adsorb and reduce the TCE concentration and to manage contaminant migration. Additionally, AC may also act as an activator of the electron-transfer mediator in activating persulfate anion (S2O82−) to generate sulfate radical (SO4−·) for contaminant destruction. The objective of the present research was to examine the combined use of AC and persulfate to treat TCE. The degradation of persulfate in the presence of AC follows a first-order kinetic behavior, and the faster persulfate degradation is observed when elevated AC dosage is used. Higher initial persulfate concentration results in a decrease of the persulfate degradation rate. Upon persulfate oxidation, the AC surface properties are altered including: an increase in acidity of surface concentration, a decrease in pHzpc, and a slight decrease in the surface area. The results of a study of adsorption kinetics and isotherms suggest that the adsorption behavior for the original AC fits the pseudo-second-order kinetic model while the pseudo-first-order kinetic model is suitable for predicting oxidized AC performance. During the persulfate oxidation of TCE with AC as an activator, studies show that TCE removal can be a net result of adsorption and oxidation, in which a partial mineralization of TCE to release chloride occurs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900841k Exemplaires
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Titre : Reactor development for supercritical water gasification of 4.9 wt% glucose solution at 673 K by using computational fluid dynamics Type de document : texte imprimé Auteurs : Takuya Yoshida, Auteur ; Yukihiko Matsumura, Auteur Année de publication : 2010 Article en page(s) : pp. 8381–8386 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Supercritical water gasification Computational fluid dynamics Résumé : Supercritical water gasification is suitable for gasifying biomass with high moisture content. Although biomass material can be easily decomposed in supercritical water, it can polymerize to form char products, which may result in serious problems such as plugging of the reactor. To depress char formation during gasification of biomass material in supercritical water, a combination of reactors was proposed in our previous study. In this study, we have improved the system by means of computational fluid dynamics (CFD) and verified it through experiments. With the improved reactor, 4.9 wt% glucose solution was successfully gasified at 673 K and 25.4 MPa; the carbon gasification efficiency was greater than 0.94. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002188
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8381–8386[article] Reactor development for supercritical water gasification of 4.9 wt% glucose solution at 673 K by using computational fluid dynamics [texte imprimé] / Takuya Yoshida, Auteur ; Yukihiko Matsumura, Auteur . - 2010 . - pp. 8381–8386.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8381–8386
Mots-clés : Supercritical water gasification Computational fluid dynamics Résumé : Supercritical water gasification is suitable for gasifying biomass with high moisture content. Although biomass material can be easily decomposed in supercritical water, it can polymerize to form char products, which may result in serious problems such as plugging of the reactor. To depress char formation during gasification of biomass material in supercritical water, a combination of reactors was proposed in our previous study. In this study, we have improved the system by means of computational fluid dynamics (CFD) and verified it through experiments. With the improved reactor, 4.9 wt% glucose solution was successfully gasified at 673 K and 25.4 MPa; the carbon gasification efficiency was greater than 0.94. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002188 Exemplaires
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Titre : Multiplicity behavior of trickle flow liquid−solid mass transfer Type de document : texte imprimé Auteurs : Rita Joubert, Auteur ; Willie Nicol, Auteur Année de publication : 2010 Article en page(s) : pp. 8387–8392 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Multiplicity Liquid− solid mass transfer Résumé : Dissolution as well as electrochemical techniques confirmed the existence of multiplicity. The commonly accepted upper multiplicity branch (achieved by Kan liquid prewetting) outperformed the lower branch (achieved by Levec prewetting) by as much as 1.6 times in Sherwood numbers. Although similar trends were observed for the two measurement techniques, the dissolution measurements were significantly lower than the electrochemical measurements. It was further shown that the multiplicity behavior of liquid−solid mass transfer is not linked solely to liquid hold-up and wetting efficiency variations, indicating major differences in flow structures between the multiplicity modes employed. In addition, a decrease in Sherwood numbers with bed depth was observed for both multiplicity modes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002552
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8387–8392[article] Multiplicity behavior of trickle flow liquid−solid mass transfer [texte imprimé] / Rita Joubert, Auteur ; Willie Nicol, Auteur . - 2010 . - pp. 8387–8392.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8387–8392
Mots-clés : Multiplicity Liquid− solid mass transfer Résumé : Dissolution as well as electrochemical techniques confirmed the existence of multiplicity. The commonly accepted upper multiplicity branch (achieved by Kan liquid prewetting) outperformed the lower branch (achieved by Levec prewetting) by as much as 1.6 times in Sherwood numbers. Although similar trends were observed for the two measurement techniques, the dissolution measurements were significantly lower than the electrochemical measurements. It was further shown that the multiplicity behavior of liquid−solid mass transfer is not linked solely to liquid hold-up and wetting efficiency variations, indicating major differences in flow structures between the multiplicity modes employed. In addition, a decrease in Sherwood numbers with bed depth was observed for both multiplicity modes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002552 Exemplaires
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Titre : Phase holdups in three-phase semifluidized beds and the generalized bubble wake model Type de document : texte imprimé Auteurs : Markus Schubert, Auteur ; Faïçal Larachi, Auteur Année de publication : 2010 Article en page(s) : pp. 8393–8401 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas− liquid− solid semifluidized beds Pressure drop measurements Phase holdup Rector Résumé : A new experimental measurement methodology was proposed to characterize the hydrodynamics in gas−liquid−solid semifluidized beds. Using pressure drop measurements in the lower fluidized bed section and a tracer response technique in the upper fixed bed portion, the six phase holdup components of the reactor were determined simultaneously. Available models for macroscopic predictions of holdups, initially proposed for three-phase fluidization, were extended, and their applicability was discussed concerning semifluidized beds. Special attention was paid to the parameters of the generalized bubble wake model and their predictability with an artificial neural network. Phenomenological observations identified an additional interface region between both beds, which, viewed as an inchoate freeboard region determines the mechanisms of attachment and release of particles from the fluidized bed to the fixed bed portion. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900426f
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8393–8401[article] Phase holdups in three-phase semifluidized beds and the generalized bubble wake model [texte imprimé] / Markus Schubert, Auteur ; Faïçal Larachi, Auteur . - 2010 . - pp. 8393–8401.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8393–8401
Mots-clés : Gas− liquid− solid semifluidized beds Pressure drop measurements Phase holdup Rector Résumé : A new experimental measurement methodology was proposed to characterize the hydrodynamics in gas−liquid−solid semifluidized beds. Using pressure drop measurements in the lower fluidized bed section and a tracer response technique in the upper fixed bed portion, the six phase holdup components of the reactor were determined simultaneously. Available models for macroscopic predictions of holdups, initially proposed for three-phase fluidization, were extended, and their applicability was discussed concerning semifluidized beds. Special attention was paid to the parameters of the generalized bubble wake model and their predictability with an artificial neural network. Phenomenological observations identified an additional interface region between both beds, which, viewed as an inchoate freeboard region determines the mechanisms of attachment and release of particles from the fluidized bed to the fixed bed portion. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900426f Exemplaires
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Titre : Catalytic hydrocracking of fresh and used cooking oil Type de document : texte imprimé Auteurs : Stella Bezergianni, Auteur ; Spyros Voutetakis, Auteur ; Aggeliki Kalogianni, Auteur Année de publication : 2010 Article en page(s) : pp. 8402–8406 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Vegetable oils Hydrocracking Cracking Heteroatom removal and saturation reaction mechanisms Résumé : Hydrocracking of vegetable oils is a prominent technology for the production of biofuels. This work compares the product yields and quality of hydrocracking fresh and used cooking oil under nominal operating conditions. Cracking, heteroatom removal and saturation reaction mechanisms are evaluated for both feedstock types and for three typical hydrocracking temperatures. The assessment of both feedstocks indicates that they are both suitable for high diesel yields with smaller kerosene/jet and gasoline/naphtha yields. As temperature increases, diesel selectivity increases for both feedstock types. However, the used oil feedstock exhibits higher kerosene/jet and naphtha selectivity at low temperatures (350 °C) and lower at the highest hydrocracking temperature (390 °C). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900445m
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8402–8406[article] Catalytic hydrocracking of fresh and used cooking oil [texte imprimé] / Stella Bezergianni, Auteur ; Spyros Voutetakis, Auteur ; Aggeliki Kalogianni, Auteur . - 2010 . - pp. 8402–8406.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8402–8406
Mots-clés : Vegetable oils Hydrocracking Cracking Heteroatom removal and saturation reaction mechanisms Résumé : Hydrocracking of vegetable oils is a prominent technology for the production of biofuels. This work compares the product yields and quality of hydrocracking fresh and used cooking oil under nominal operating conditions. Cracking, heteroatom removal and saturation reaction mechanisms are evaluated for both feedstock types and for three typical hydrocracking temperatures. The assessment of both feedstocks indicates that they are both suitable for high diesel yields with smaller kerosene/jet and gasoline/naphtha yields. As temperature increases, diesel selectivity increases for both feedstock types. However, the used oil feedstock exhibits higher kerosene/jet and naphtha selectivity at low temperatures (350 °C) and lower at the highest hydrocracking temperature (390 °C). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900445m Exemplaires
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Titre : Pilot plant scale study of the influence of the operating conditions in the production of carbon nanofibers Type de document : texte imprimé Auteurs : Vicente Jiménez, Auteur ; Antonio Nieto-Márquez, Auteur ; José Antonio Díaz, Auteur Année de publication : 2010 Article en page(s) : pp. 8407–8417 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon nanofibers Pilot scale Fixed-bed reactor Résumé : In this paper, the optimization of typical reaction variables for a pilot scale synthesis of carbon nanofibers (CNFs) using a fixed-bed reactor has been carried out to provide a more economically viable large scale production of these materials. Using a Ni/SiO2 catalyst (10 wt % Ni) and ethylene as the carbon source, the optimum value of temperature, space velocity, and H2/C2H4 ratio (v/v) in terms of carbon yield was 600 °C, 10000 h−1, and 1:4, respectively. The modification of these variables caused a significant change in the type and amount of solid carbon recovered. Carbon product characterization demonstrated that CNFs with mesoporous character, large external surface, and good thermal stability and crystallinity were obtained. Finally, results demonstrated a successful scale-up by a factor of 45 in the pilot plant scale; a CNFs yield of 106 gCNFs/gcatalytic metal could be obtained at optimal conditions during a reaction time of 60 min at optimal conditions in the pilot plant scale. For the same reaction conditions, only 80 gCNFs/gcatalytic metal were obtained in the laboratory reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005386
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8407–8417[article] Pilot plant scale study of the influence of the operating conditions in the production of carbon nanofibers [texte imprimé] / Vicente Jiménez, Auteur ; Antonio Nieto-Márquez, Auteur ; José Antonio Díaz, Auteur . - 2010 . - pp. 8407–8417.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8407–8417
Mots-clés : Carbon nanofibers Pilot scale Fixed-bed reactor Résumé : In this paper, the optimization of typical reaction variables for a pilot scale synthesis of carbon nanofibers (CNFs) using a fixed-bed reactor has been carried out to provide a more economically viable large scale production of these materials. Using a Ni/SiO2 catalyst (10 wt % Ni) and ethylene as the carbon source, the optimum value of temperature, space velocity, and H2/C2H4 ratio (v/v) in terms of carbon yield was 600 °C, 10000 h−1, and 1:4, respectively. The modification of these variables caused a significant change in the type and amount of solid carbon recovered. Carbon product characterization demonstrated that CNFs with mesoporous character, large external surface, and good thermal stability and crystallinity were obtained. Finally, results demonstrated a successful scale-up by a factor of 45 in the pilot plant scale; a CNFs yield of 106 gCNFs/gcatalytic metal could be obtained at optimal conditions during a reaction time of 60 min at optimal conditions in the pilot plant scale. For the same reaction conditions, only 80 gCNFs/gcatalytic metal were obtained in the laboratory reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005386 Exemplaires
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Titre : Effect of hydrogen sulfide on chemical looping combustion of coal-derived synthesis gas over bentonite-supported metal−oxide oxygen carriers Type de document : texte imprimé Auteurs : Hanjing Tian, Auteur ; Thomas Simonyi, Auteur ; James Poston, Auteur Année de publication : 2010 Article en page(s) : pp. 8418–8430 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hydrogen sulfide Coal-derived synthesis gas Chemical looping combustionBentonite Résumé : The effect of hydrogen sulfide (H2S) on the chemical looping combustion of coal-derived synthesis gas with bentonite-supported metal oxides—such as iron oxide, nickel oxide, manganese oxide, and copper oxide—was investigated by thermogravimetric analysis, mass spectrometry, and X-ray photoelectron spectroscopy (XPS). During the reaction with synthesis gas containing H2S, metal−oxide oxygen carriers were first reduced by carbon monoxide and hydrogen, and then interacted with H2S to form metal sulfide, which resulted in a weight gain during the reduction/sulfidation step. The reduced/sulfurized compounds could be regenerated to form sulfur dioxide and oxides during the oxidation reaction with air. The reduction/oxidation capacities of iron oxide and nickel oxide were not affected by the presence of H2S, but both manganese oxide and copper oxide showed decreased reduction/oxidation capacities. However, the rates of reduction and oxidation decreased in the presence of H2S for all four metal oxides. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900638p
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8418–8430[article] Effect of hydrogen sulfide on chemical looping combustion of coal-derived synthesis gas over bentonite-supported metal−oxide oxygen carriers [texte imprimé] / Hanjing Tian, Auteur ; Thomas Simonyi, Auteur ; James Poston, Auteur . - 2010 . - pp. 8418–8430.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8418–8430
Mots-clés : Hydrogen sulfide Coal-derived synthesis gas Chemical looping combustionBentonite Résumé : The effect of hydrogen sulfide (H2S) on the chemical looping combustion of coal-derived synthesis gas with bentonite-supported metal oxides—such as iron oxide, nickel oxide, manganese oxide, and copper oxide—was investigated by thermogravimetric analysis, mass spectrometry, and X-ray photoelectron spectroscopy (XPS). During the reaction with synthesis gas containing H2S, metal−oxide oxygen carriers were first reduced by carbon monoxide and hydrogen, and then interacted with H2S to form metal sulfide, which resulted in a weight gain during the reduction/sulfidation step. The reduced/sulfurized compounds could be regenerated to form sulfur dioxide and oxides during the oxidation reaction with air. The reduction/oxidation capacities of iron oxide and nickel oxide were not affected by the presence of H2S, but both manganese oxide and copper oxide showed decreased reduction/oxidation capacities. However, the rates of reduction and oxidation decreased in the presence of H2S for all four metal oxides. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900638p Exemplaires
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Titre : CO2 capture from simulated syngas via cyclic carbonation/calcination for a naturally occurring limestone : pilot-plant testing Type de document : texte imprimé Auteurs : Robert T. Symonds, Auteur ; Dennis Y. Lu, Auteur ; Robin W. Hughes, Auteur Année de publication : 2010 Article en page(s) : pp. 8431–8440 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CO2 capture Fuidized bed reactor system Calcination Cyclic carbonation Résumé : Experiments were performed using a dual fluidized bed reactor system, operated in a batch mode, in order to investigate the effects of steam and simulated syngas on CO2 capture and sorbent conversion efficiency for a naturally occurring Polish calcitic limestone. In addition, the effect of high partial pressures of CO2 on the calcination process was examined using either oxygen-enriched air or oxy-fuel combustion in the calciner. As expected, calcination under oxy-fuel conditions resulted in decreased carbonation conversion due primarily to particle sintering and pore pluggage. On average there was a decrease in carbonation conversion of approximately 36.5 and 33.4% for carbonation with steam and steam/simulated syngas, respectively, compared to similar experiments using oxygen-enriched air. However, during the carbonation of the limestone with steam present in the feed gas, it was observed that the high CO2 capture efficiency period was significantly extended compared to carbonation with only CO2 present. This resulted in increased CaO conversion from approximately 16.1 to 29.7% for the initial carbonation cycle. A further increase in carbonation conversion, from 29.7 to 46.9%, was also observed when simulated syngas conditions (CO, H2) were used in the carbonator. Analysis of the outlet gases also confirmed that the calcined limestone catalyzes the water gas shift reaction, which we believe results in enhanced CO2 concentration levels at the grain surfaces of the sorbent. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900645x
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8431–8440[article] CO2 capture from simulated syngas via cyclic carbonation/calcination for a naturally occurring limestone : pilot-plant testing [texte imprimé] / Robert T. Symonds, Auteur ; Dennis Y. Lu, Auteur ; Robin W. Hughes, Auteur . - 2010 . - pp. 8431–8440.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8431–8440
Mots-clés : CO2 capture Fuidized bed reactor system Calcination Cyclic carbonation Résumé : Experiments were performed using a dual fluidized bed reactor system, operated in a batch mode, in order to investigate the effects of steam and simulated syngas on CO2 capture and sorbent conversion efficiency for a naturally occurring Polish calcitic limestone. In addition, the effect of high partial pressures of CO2 on the calcination process was examined using either oxygen-enriched air or oxy-fuel combustion in the calciner. As expected, calcination under oxy-fuel conditions resulted in decreased carbonation conversion due primarily to particle sintering and pore pluggage. On average there was a decrease in carbonation conversion of approximately 36.5 and 33.4% for carbonation with steam and steam/simulated syngas, respectively, compared to similar experiments using oxygen-enriched air. However, during the carbonation of the limestone with steam present in the feed gas, it was observed that the high CO2 capture efficiency period was significantly extended compared to carbonation with only CO2 present. This resulted in increased CaO conversion from approximately 16.1 to 29.7% for the initial carbonation cycle. A further increase in carbonation conversion, from 29.7 to 46.9%, was also observed when simulated syngas conditions (CO, H2) were used in the carbonator. Analysis of the outlet gases also confirmed that the calcined limestone catalyzes the water gas shift reaction, which we believe results in enhanced CO2 concentration levels at the grain surfaces of the sorbent. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900645x Exemplaires
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Titre : Catalytic activity of clay-based titanium silicalite-1 composite in cyclohexanone ammoximation Type de document : texte imprimé Auteurs : Alex C. K. Yip, Auteur ; Xijun Hu, Auteur Année de publication : 2010 Article en page(s) : pp. 8441–8450 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cyclohexanone ammoximation Catalyst External diffusion Internal Résumé : Following the recent report on the synthesis of a clay-based titanium silicalite-1 (TS-1) composite, this work provided important information on the catalytic activity of the catalyst developed for cyclohexanone ammoximation. Experimental works showed that the optimum molar ratio of cyclohexanone:H2O2:NH3 was 1:1.6:2.5. It was found that the cyclohexanone ammoximation over the clay-based catalytic composite gave the highest oxime yield when H2O2 and NH3 was continuously added and was evenly distributed in 5 doses, respectively, to the reaction mixture. The external and internal diffusions can be eliminated by using a water:t-butanol mixture as a solvent, with sufficiently fast agitation speed and having TS-1 crystal with size smaller than 500 nm. On the basis of the adsorption studies and the spectroscopic evidence, the mechanism of the cyclohexanone ammoximation over the catalyst developed are suggested to follow Langmuir−Hinshelwood and Eley−Rideal kinetics. The data acquired in this study is particularly essential for industrial reactor design. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900731s
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8441–8450[article] Catalytic activity of clay-based titanium silicalite-1 composite in cyclohexanone ammoximation [texte imprimé] / Alex C. K. Yip, Auteur ; Xijun Hu, Auteur . - 2010 . - pp. 8441–8450.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8441–8450
Mots-clés : Cyclohexanone ammoximation Catalyst External diffusion Internal Résumé : Following the recent report on the synthesis of a clay-based titanium silicalite-1 (TS-1) composite, this work provided important information on the catalytic activity of the catalyst developed for cyclohexanone ammoximation. Experimental works showed that the optimum molar ratio of cyclohexanone:H2O2:NH3 was 1:1.6:2.5. It was found that the cyclohexanone ammoximation over the clay-based catalytic composite gave the highest oxime yield when H2O2 and NH3 was continuously added and was evenly distributed in 5 doses, respectively, to the reaction mixture. The external and internal diffusions can be eliminated by using a water:t-butanol mixture as a solvent, with sufficiently fast agitation speed and having TS-1 crystal with size smaller than 500 nm. On the basis of the adsorption studies and the spectroscopic evidence, the mechanism of the cyclohexanone ammoximation over the catalyst developed are suggested to follow Langmuir−Hinshelwood and Eley−Rideal kinetics. The data acquired in this study is particularly essential for industrial reactor design. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900731s Exemplaires
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Titre : Wrong-way behavior of soot combustion in a planar diesel particulate filter Type de document : texte imprimé Auteurs : K. Chen, Auteur ; K. S. Martirosyan, Auteur ; D. Luss, Auteur Année de publication : 2010 Article en page(s) : pp. 8451–8456 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Diesel particulate filter Wrong-way behavior Résumé : Infrared imaging was used to study the impact of a sudden decrease in the exhaust temperature on the spatiotemporal temperature of a single layer planar diesel particulate filter (DPF). The experiments revealed that a sudden decrease in the feed temperature by 100 °C can lead to sudden temperature rise (wrong-way behavior) of about 50 °C above that obtained with the constant original temperature. The transient temperature rise highly depended on the position where the temperature shift was initiated, that is, the time that the moving temperature front stayed in the DPF before exiting it. The temperature excursion near the end of DPF was much higher than the temperature rise in middle or near the entrance. The experiments reveal that the DPF temperature during dynamic operation can exceed in a counterintuitive fashion that obtained under stationary (constant) operating conditions. This suggests that the reported melting of cordierite DPF may have been caused by rapid changes in the feed conditions due to a change in the driving mode, such as a sudden vehicle deceleration. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900848d
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8451–8456[article] Wrong-way behavior of soot combustion in a planar diesel particulate filter [texte imprimé] / K. Chen, Auteur ; K. S. Martirosyan, Auteur ; D. Luss, Auteur . - 2010 . - pp. 8451–8456.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8451–8456
Mots-clés : Diesel particulate filter Wrong-way behavior Résumé : Infrared imaging was used to study the impact of a sudden decrease in the exhaust temperature on the spatiotemporal temperature of a single layer planar diesel particulate filter (DPF). The experiments revealed that a sudden decrease in the feed temperature by 100 °C can lead to sudden temperature rise (wrong-way behavior) of about 50 °C above that obtained with the constant original temperature. The transient temperature rise highly depended on the position where the temperature shift was initiated, that is, the time that the moving temperature front stayed in the DPF before exiting it. The temperature excursion near the end of DPF was much higher than the temperature rise in middle or near the entrance. The experiments reveal that the DPF temperature during dynamic operation can exceed in a counterintuitive fashion that obtained under stationary (constant) operating conditions. This suggests that the reported melting of cordierite DPF may have been caused by rapid changes in the feed conditions due to a change in the driving mode, such as a sudden vehicle deceleration. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900848d Exemplaires
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Titre : Age-induced changes in the microstructure and selected properties of extruded starch films plasticized with glycerol and stearic acid Type de document : texte imprimé Auteurs : Heartwin A. Pushpadass, Auteur ; Milford A. Hanna, Auteur Année de publication : 2010 Article en page(s) : pp. 8457–8463 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Extruded starch films Water vapor permeability Thermoplastic Résumé : Aging of normal corn starch films processed by extrusion and stored at 20−22 °C and 50−56% RH was investigated over a period of 120 d. The changes in the structural, thermal, tensile, and water vapor permeability (WVP) properties of the films during aging were studied. The thermoplastic starch (TPS) just after extrusion processing (≈4 h) was nearly amorphous in character. However, aging above the Tg produced both B- and V-type crystalline structures in the TPS within 3 d of drying. The relative crystalline content of the TPS increased from 2.6 to 17.7%, depending on the glycerol content. Post-processing, the tensile strengths of the films increased by 39.3−134.1% while the tensile strains decreased by 48−81.1%. The rates of change in tensile strength and strain were faster during the first 30 d but stabilized thereafter. The biphasic transitions in the DSC thermograms suggested phase separation in the TPS. The Tg of glycerol-rich domains decreased while those of the starch-rich regions increased during storage. The band-narrowing and changes in peak styles and intensities in the 1400−800 cm−1 region of the Fourier transform infrared spectra suggested increases in the crystalline content of the TPS during aging. The WVP values tended to decrease with time as the crystallinity of starch increased and the free volume in the film network decreased. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801922z
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8457–8463[article] Age-induced changes in the microstructure and selected properties of extruded starch films plasticized with glycerol and stearic acid [texte imprimé] / Heartwin A. Pushpadass, Auteur ; Milford A. Hanna, Auteur . - 2010 . - pp. 8457–8463.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8457–8463
Mots-clés : Extruded starch films Water vapor permeability Thermoplastic Résumé : Aging of normal corn starch films processed by extrusion and stored at 20−22 °C and 50−56% RH was investigated over a period of 120 d. The changes in the structural, thermal, tensile, and water vapor permeability (WVP) properties of the films during aging were studied. The thermoplastic starch (TPS) just after extrusion processing (≈4 h) was nearly amorphous in character. However, aging above the Tg produced both B- and V-type crystalline structures in the TPS within 3 d of drying. The relative crystalline content of the TPS increased from 2.6 to 17.7%, depending on the glycerol content. Post-processing, the tensile strengths of the films increased by 39.3−134.1% while the tensile strains decreased by 48−81.1%. The rates of change in tensile strength and strain were faster during the first 30 d but stabilized thereafter. The biphasic transitions in the DSC thermograms suggested phase separation in the TPS. The Tg of glycerol-rich domains decreased while those of the starch-rich regions increased during storage. The band-narrowing and changes in peak styles and intensities in the 1400−800 cm−1 region of the Fourier transform infrared spectra suggested increases in the crystalline content of the TPS during aging. The WVP values tended to decrease with time as the crystallinity of starch increased and the free volume in the film network decreased. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801922z Exemplaires
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Titre : Influence of bitumen colloidal nature on the design of isocyanate-based bituminous products with enhanced rheological properties Type de document : texte imprimé Auteurs : Virginia Carrera, Auteur ; Pedro Partal, Auteur ; Moises Garcia-Morales, Auteur Année de publication : 2010 Article en page(s) : pp. 8464–8470 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Bitumen colloidal nature Rheological propertiesIsocyanate-based reactive polymers Résumé : This work deals with the influence that bitumen colloidal nature exerts on the rheological properties of bitumen samples modified by isocyanate-based reactive polymers. Shear rheology tests, modulated differential scanning calorimetry (MDSC), chemical characterization by TLC-FID, and AFM microstructural analysis were carried out on four different 150/200 penetration neat bitumen samples and the corresponding MDI-PPG (a low molecular weight polypropylene glycol functionalized with a polymeric 4,4′-diphenylmethane diisocyanate) modified binders. The results obtained demonstrate that the bitumen modification degree depends on bitumen reactivity and microstructure. Thus, the highest modification capability is obtained with neat bitumen samples that exhibit both a well-developed three-dimensional network and a high chemical reactivity with the isocyanate groups. The results obtained may be used to improve the performance of these materials, according to their final application. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004404
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8464–8470[article] Influence of bitumen colloidal nature on the design of isocyanate-based bituminous products with enhanced rheological properties [texte imprimé] / Virginia Carrera, Auteur ; Pedro Partal, Auteur ; Moises Garcia-Morales, Auteur . - 2010 . - pp. 8464–8470.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8464–8470
Mots-clés : Bitumen colloidal nature Rheological propertiesIsocyanate-based reactive polymers Résumé : This work deals with the influence that bitumen colloidal nature exerts on the rheological properties of bitumen samples modified by isocyanate-based reactive polymers. Shear rheology tests, modulated differential scanning calorimetry (MDSC), chemical characterization by TLC-FID, and AFM microstructural analysis were carried out on four different 150/200 penetration neat bitumen samples and the corresponding MDI-PPG (a low molecular weight polypropylene glycol functionalized with a polymeric 4,4′-diphenylmethane diisocyanate) modified binders. The results obtained demonstrate that the bitumen modification degree depends on bitumen reactivity and microstructure. Thus, the highest modification capability is obtained with neat bitumen samples that exhibit both a well-developed three-dimensional network and a high chemical reactivity with the isocyanate groups. The results obtained may be used to improve the performance of these materials, according to their final application. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004404 Exemplaires
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Titre : Preparation of ultrafine zeolite a crystals with narrow particle size distribution using a two-phase liquid segmented microfluidic reactor Type de document : texte imprimé Auteurs : Yichang Pan, Auteur ; Jianfeng Yao, Auteur ; Lixiong Zhang, Auteur Année de publication : 2010 Article en page(s) : pp. 8471–8477 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ultrafine zeolite A crystals X-ray diffraction Fourier transform Résumé : A method for synthesizing ultrafine zeolite A crystals with narrow particle size distribution (PSD) using a water−liquid paraffin two-phase segmented microfluidic device assembled by coaxial dual tubes is reported. The influence of the sizes of the outer tubes, the aging of the synthesis solution, and the reaction temperature was examined. As-synthesized zeolite crystals were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, dynamic light scattering, energy dispersive X-ray spectroscopy, scanning electron microscopy, and field-emission scanning electron microscope. Zeolite A crystals with mean particle sizes (MS) of 408 and 262 nm and PSDs of 150−620 and 100−420 nm were prepared in the segmented microfluidic reactor (inner tube i.d. of 0.6 mm, outer tube i.d. of 1 mm) at 80 °C for 20 min using the fresh synthesis solution and for 5 min using the aged synthesis solution, respectively. The MS and PSD of zeolite A can be controlled by adjusting the temperature and the sizes of the outer tube. The crystallization performance of zeolite A in the segmented microfluidic reactor was compared with those in the conventional and microwave-heated batch reactor and the single-phase microfluidic reactor at 90 °C. It was found that the rate of crystallization in the segmented microfluidic reactor was a bit slower than that in the microwave-heated batch reactor, but was much higher than those in the conventional batch reactor and single-phase microfluidic reactor. The MS and PSD of the resulting zeolite A synthesized in the segmented microfluidic device are smaller and narrower than those produced in the conventional batch reactor, single-phase microfluidic reactor, and microwave-heated reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900621y
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8471–8477[article] Preparation of ultrafine zeolite a crystals with narrow particle size distribution using a two-phase liquid segmented microfluidic reactor [texte imprimé] / Yichang Pan, Auteur ; Jianfeng Yao, Auteur ; Lixiong Zhang, Auteur . - 2010 . - pp. 8471–8477.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8471–8477
Mots-clés : Ultrafine zeolite A crystals X-ray diffraction Fourier transform Résumé : A method for synthesizing ultrafine zeolite A crystals with narrow particle size distribution (PSD) using a water−liquid paraffin two-phase segmented microfluidic device assembled by coaxial dual tubes is reported. The influence of the sizes of the outer tubes, the aging of the synthesis solution, and the reaction temperature was examined. As-synthesized zeolite crystals were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, dynamic light scattering, energy dispersive X-ray spectroscopy, scanning electron microscopy, and field-emission scanning electron microscope. Zeolite A crystals with mean particle sizes (MS) of 408 and 262 nm and PSDs of 150−620 and 100−420 nm were prepared in the segmented microfluidic reactor (inner tube i.d. of 0.6 mm, outer tube i.d. of 1 mm) at 80 °C for 20 min using the fresh synthesis solution and for 5 min using the aged synthesis solution, respectively. The MS and PSD of zeolite A can be controlled by adjusting the temperature and the sizes of the outer tube. The crystallization performance of zeolite A in the segmented microfluidic reactor was compared with those in the conventional and microwave-heated batch reactor and the single-phase microfluidic reactor at 90 °C. It was found that the rate of crystallization in the segmented microfluidic reactor was a bit slower than that in the microwave-heated batch reactor, but was much higher than those in the conventional batch reactor and single-phase microfluidic reactor. The MS and PSD of the resulting zeolite A synthesized in the segmented microfluidic device are smaller and narrower than those produced in the conventional batch reactor, single-phase microfluidic reactor, and microwave-heated reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900621y Exemplaires
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Titre : Preparation of ultrafine zeolite a crystals with narrow particle size distribution using a two-phase liquid segmented microfluidic reactor Type de document : texte imprimé Auteurs : Yichang Pan, Auteur ; Jianfeng Yao, Auteur ; Lixiong Zhang, Auteur Année de publication : 2010 Article en page(s) : pp. 8471–8477 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ultrafine zeolite A crystals X-ray diffraction Fourier transform Résumé : A method for synthesizing ultrafine zeolite A crystals with narrow particle size distribution (PSD) using a water−liquid paraffin two-phase segmented microfluidic device assembled by coaxial dual tubes is reported. The influence of the sizes of the outer tubes, the aging of the synthesis solution, and the reaction temperature was examined. As-synthesized zeolite crystals were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, dynamic light scattering, energy dispersive X-ray spectroscopy, scanning electron microscopy, and field-emission scanning electron microscope. Zeolite A crystals with mean particle sizes (MS) of 408 and 262 nm and PSDs of 150−620 and 100−420 nm were prepared in the segmented microfluidic reactor (inner tube i.d. of 0.6 mm, outer tube i.d. of 1 mm) at 80 °C for 20 min using the fresh synthesis solution and for 5 min using the aged synthesis solution, respectively. The MS and PSD of zeolite A can be controlled by adjusting the temperature and the sizes of the outer tube. The crystallization performance of zeolite A in the segmented microfluidic reactor was compared with those in the conventional and microwave-heated batch reactor and the single-phase microfluidic reactor at 90 °C. It was found that the rate of crystallization in the segmented microfluidic reactor was a bit slower than that in the microwave-heated batch reactor, but was much higher than those in the conventional batch reactor and single-phase microfluidic reactor. The MS and PSD of the resulting zeolite A synthesized in the segmented microfluidic device are smaller and narrower than those produced in the conventional batch reactor, single-phase microfluidic reactor, and microwave-heated reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900621y
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8471–8477[article] Preparation of ultrafine zeolite a crystals with narrow particle size distribution using a two-phase liquid segmented microfluidic reactor [texte imprimé] / Yichang Pan, Auteur ; Jianfeng Yao, Auteur ; Lixiong Zhang, Auteur . - 2010 . - pp. 8471–8477.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8471–8477
Mots-clés : Ultrafine zeolite A crystals X-ray diffraction Fourier transform Résumé : A method for synthesizing ultrafine zeolite A crystals with narrow particle size distribution (PSD) using a water−liquid paraffin two-phase segmented microfluidic device assembled by coaxial dual tubes is reported. The influence of the sizes of the outer tubes, the aging of the synthesis solution, and the reaction temperature was examined. As-synthesized zeolite crystals were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, dynamic light scattering, energy dispersive X-ray spectroscopy, scanning electron microscopy, and field-emission scanning electron microscope. Zeolite A crystals with mean particle sizes (MS) of 408 and 262 nm and PSDs of 150−620 and 100−420 nm were prepared in the segmented microfluidic reactor (inner tube i.d. of 0.6 mm, outer tube i.d. of 1 mm) at 80 °C for 20 min using the fresh synthesis solution and for 5 min using the aged synthesis solution, respectively. The MS and PSD of zeolite A can be controlled by adjusting the temperature and the sizes of the outer tube. The crystallization performance of zeolite A in the segmented microfluidic reactor was compared with those in the conventional and microwave-heated batch reactor and the single-phase microfluidic reactor at 90 °C. It was found that the rate of crystallization in the segmented microfluidic reactor was a bit slower than that in the microwave-heated batch reactor, but was much higher than those in the conventional batch reactor and single-phase microfluidic reactor. The MS and PSD of the resulting zeolite A synthesized in the segmented microfluidic device are smaller and narrower than those produced in the conventional batch reactor, single-phase microfluidic reactor, and microwave-heated reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900621y Exemplaires
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Titre : Copper promoted cobalt and nickel catalysts supported on ceria−alumina mixed oxide : structural characterization and CO oxidation activity Type de document : texte imprimé Auteurs : Benjaram M. Reddy, Auteur ; Komateedi N. Rao, Auteur ; Pankaj Bharali, Auteur Année de publication : 2010 Article en page(s) : pp. 8478–8486 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CoO, NiO, CuO− CoO CuO− NiO nanocrystalline Catalytic activity Résumé : Catalytic activity of CoO, NiO, CuO−CoO, and CuO−NiO nanocrystalline mono- and bimetallic catalysts over a thermally stable and high surface area ceria−alumina mixed oxide support was evaluated for oxidation of carbon monoxide at normal atmospheric pressure and lower temperatures. The content of Co or Ni in the respective monometallic catalysts was 10 wt % and the Cu-promoted samples contained 5 wt % each. These catalysts were prepared by a wet impregnation procedure and the CeO2−Al2O3 support was obtained by a deposition precipitation method. The synthesized catalysts were characterized by BET surface area, X-ray diffraction (XRD), energy dispersive X-ray microanalysis (EDX), temperature-programmed reduction (TPR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques. XRD patterns of 773 K calcined samples revealed the presence of metal oxide phases, namely, CeO2, CuO, NiO, and Co3O4 in the respective catalysts. However, after calcination at 1073 K, the XRD lines corresponding to CuO and NiO were absent. EDX results confirmed the actual amount of metal loadings in the respective catalysts. The H2-TPR results suggested that Cu-doping accelerates and decreases the onset reduction temperature of monometallic samples. Raman results of 773 K calcined samples showed a prominent broad peak at 461 cm−1 corresponding to the F2g Raman active mode of CeO2. The TEM studies confirmed the presence of nanosized composite oxides with narrow size distribution of metal oxide particles. The XPS results disclosed the presence of Cu1+ species along with Cu2+ and the promotional effect of Cu in Co-containing samples to suppress the formation of the CoAl2O4 phase. Among different catalysts, the copper promoted CuO−NiO/CeO2−Al2O3 sample exhibited better activity for CO oxidation at lower temperatures. The better activity of the catalyst is attributed to the formation of well-dispersed and highly reducible metal oxide species over the mixed oxide support. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900755b
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8478–8486[article] Copper promoted cobalt and nickel catalysts supported on ceria−alumina mixed oxide : structural characterization and CO oxidation activity [texte imprimé] / Benjaram M. Reddy, Auteur ; Komateedi N. Rao, Auteur ; Pankaj Bharali, Auteur . - 2010 . - pp. 8478–8486.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8478–8486
Mots-clés : CoO, NiO, CuO− CoO CuO− NiO nanocrystalline Catalytic activity Résumé : Catalytic activity of CoO, NiO, CuO−CoO, and CuO−NiO nanocrystalline mono- and bimetallic catalysts over a thermally stable and high surface area ceria−alumina mixed oxide support was evaluated for oxidation of carbon monoxide at normal atmospheric pressure and lower temperatures. The content of Co or Ni in the respective monometallic catalysts was 10 wt % and the Cu-promoted samples contained 5 wt % each. These catalysts were prepared by a wet impregnation procedure and the CeO2−Al2O3 support was obtained by a deposition precipitation method. The synthesized catalysts were characterized by BET surface area, X-ray diffraction (XRD), energy dispersive X-ray microanalysis (EDX), temperature-programmed reduction (TPR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques. XRD patterns of 773 K calcined samples revealed the presence of metal oxide phases, namely, CeO2, CuO, NiO, and Co3O4 in the respective catalysts. However, after calcination at 1073 K, the XRD lines corresponding to CuO and NiO were absent. EDX results confirmed the actual amount of metal loadings in the respective catalysts. The H2-TPR results suggested that Cu-doping accelerates and decreases the onset reduction temperature of monometallic samples. Raman results of 773 K calcined samples showed a prominent broad peak at 461 cm−1 corresponding to the F2g Raman active mode of CeO2. The TEM studies confirmed the presence of nanosized composite oxides with narrow size distribution of metal oxide particles. The XPS results disclosed the presence of Cu1+ species along with Cu2+ and the promotional effect of Cu in Co-containing samples to suppress the formation of the CoAl2O4 phase. Among different catalysts, the copper promoted CuO−NiO/CeO2−Al2O3 sample exhibited better activity for CO oxidation at lower temperatures. The better activity of the catalyst is attributed to the formation of well-dispersed and highly reducible metal oxide species over the mixed oxide support. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900755b Exemplaires
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Titre : Effect of surface treatment on titania-modified PET fiber using polyethylene nanoparticles Type de document : texte imprimé Auteurs : Yung-Pin Huang, Auteur ; Jing-Wen Tang, Auteur ; Fen-Mei Chang, Auteur Année de publication : 2010 Article en page(s) : pp. 8487–8492 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polyethylene nanoparticles Poly(ethylene terephthalate) fibers Résumé : Polyethylene (PE) nanoparticles were newly prepared by a combination of ultrasonication and low-temperature-induced crystallization in poly(ethylene glycol). These PE particles were formulated into spin finishes and applied to the surface of titania-modified poly(ethylene terephthalate) (PET) fibers that had a higher relative concentration of titania (TiO2) nanoparticles at the fiber surface than in the interior core as evidenced by SEM/EDX mapping studies. Aggregations of TiO2 nanoparticles were found to appear on the surface of such fibers, which led to a decreased contact area and, thus, an increased contact pressure between the sliding fiber and its encountered surface. The effect of plowing by the sliding fiber on its counterpart was observed and studied as a function of the PE nanoparticle size, and the corresponding data on the friction force among three values of fiber fineness were also obtained. We found that the fiber friction force decreased and the plowing effect on its counterpart increased when the fiber fineness decreased. In addition, we found that the minimum plowing effect was obtained when the size of the PE nanoparticles was comparable to the size of the TiO2 aggregations that appeared on the surface of the titania-modified PET fibers. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900811r
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8487–8492[article] Effect of surface treatment on titania-modified PET fiber using polyethylene nanoparticles [texte imprimé] / Yung-Pin Huang, Auteur ; Jing-Wen Tang, Auteur ; Fen-Mei Chang, Auteur . - 2010 . - pp. 8487–8492.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8487–8492
Mots-clés : Polyethylene nanoparticles Poly(ethylene terephthalate) fibers Résumé : Polyethylene (PE) nanoparticles were newly prepared by a combination of ultrasonication and low-temperature-induced crystallization in poly(ethylene glycol). These PE particles were formulated into spin finishes and applied to the surface of titania-modified poly(ethylene terephthalate) (PET) fibers that had a higher relative concentration of titania (TiO2) nanoparticles at the fiber surface than in the interior core as evidenced by SEM/EDX mapping studies. Aggregations of TiO2 nanoparticles were found to appear on the surface of such fibers, which led to a decreased contact area and, thus, an increased contact pressure between the sliding fiber and its encountered surface. The effect of plowing by the sliding fiber on its counterpart was observed and studied as a function of the PE nanoparticle size, and the corresponding data on the friction force among three values of fiber fineness were also obtained. We found that the fiber friction force decreased and the plowing effect on its counterpart increased when the fiber fineness decreased. In addition, we found that the minimum plowing effect was obtained when the size of the PE nanoparticles was comparable to the size of the TiO2 aggregations that appeared on the surface of the titania-modified PET fibers. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900811r Exemplaires
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Titre : Nanonization of megestrol acetate by liquid precipitation Type de document : texte imprimé Auteurs : Zhi-Bing Zhang, Auteur ; Zhi-Gang Shen, Auteur ; Jie-Xin Wang, Auteur Année de publication : 2010 Article en page(s) : pp. 8493–8499 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Megestrol acetate nanoparticles Liquid precipitation technique Résumé : The purpose of this study was to prepare megestrol acetate (MA) nanoparticles via a liquid precipitation technique. Several experimental parameters, such as the stabilizer combination, the volume ratio of antisolvent to drug solution, the temperature, the stirring speed, and the drying method were investigated. The as-prepared MA particles had a mean size of 208 nm, and 90% of the particles were distributed in the range of 100−300 nm, whereas the raw MA had a mean particle size of about 3.02 μm, ranging widely from 0.2 μm to 30 μm. X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) analysis indicated that MA nanoparticles exhibited decreased crystallinity and unchanged chemical group structure after precipitation. The freeze-dried MA nanoparticles exhibited improved wettability as demonstrated by the contact angle measurement result proving that particles were covered by a hydrophilic layer. In dissolution rate tests, the nanoparticles achieved 100% drug dissolution within 5 min, while the raw MA did not dissolve completely after 120 min, suggesting that the dissolution property of MA nanoparticles was significantly enhanced. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900944y
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8493–8499[article] Nanonization of megestrol acetate by liquid precipitation [texte imprimé] / Zhi-Bing Zhang, Auteur ; Zhi-Gang Shen, Auteur ; Jie-Xin Wang, Auteur . - 2010 . - pp. 8493–8499.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8493–8499
Mots-clés : Megestrol acetate nanoparticles Liquid precipitation technique Résumé : The purpose of this study was to prepare megestrol acetate (MA) nanoparticles via a liquid precipitation technique. Several experimental parameters, such as the stabilizer combination, the volume ratio of antisolvent to drug solution, the temperature, the stirring speed, and the drying method were investigated. The as-prepared MA particles had a mean size of 208 nm, and 90% of the particles were distributed in the range of 100−300 nm, whereas the raw MA had a mean particle size of about 3.02 μm, ranging widely from 0.2 μm to 30 μm. X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) analysis indicated that MA nanoparticles exhibited decreased crystallinity and unchanged chemical group structure after precipitation. The freeze-dried MA nanoparticles exhibited improved wettability as demonstrated by the contact angle measurement result proving that particles were covered by a hydrophilic layer. In dissolution rate tests, the nanoparticles achieved 100% drug dissolution within 5 min, while the raw MA did not dissolve completely after 120 min, suggesting that the dissolution property of MA nanoparticles was significantly enhanced. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900944y Exemplaires
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Titre : Efficient conversion of thermal energy into hydrogen : comparing two methods to reduce exergy losses in a sulfuric acid decomposition reactor Type de document : texte imprimé Auteurs : Leen V. van der Ham, Auteur ; Joachim Gross, Auteur ; Ad Verkooijen, Auteur Année de publication : 2010 Article en page(s) : pp. 8500–8507 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Thermal energy Hydrogen Optimal control theory Reactor length Résumé : Two methods for increasing the exergy efficiency of thermochemical processes for the production of hydrogen from water and high temperature thermal energy are presented and compared. Increasing the exergy efficiency is equivalent to reducing the entropy production. Starting from a reference reactor for the decomposition of sulfuric acid, two new reactor designs are developed that both reduce the entropy production by 26%. The first design uses optimal control theory to obtain a more uniform distribution of the entropy production. As a result of this functional optimization we obtain optimal temperature profiles over the reactor length. This optimized design is found to perform the best, but it requires significant changes in the heating equipment in order to approximately realize the optimal temperature profiles. A second design is obtained by increasing the reactor length. This leads to a higher pressure drop and requires additional compressor duty. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801585e
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8500–8507[article] Efficient conversion of thermal energy into hydrogen : comparing two methods to reduce exergy losses in a sulfuric acid decomposition reactor [texte imprimé] / Leen V. van der Ham, Auteur ; Joachim Gross, Auteur ; Ad Verkooijen, Auteur . - 2010 . - pp. 8500–8507.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8500–8507
Mots-clés : Thermal energy Hydrogen Optimal control theory Reactor length Résumé : Two methods for increasing the exergy efficiency of thermochemical processes for the production of hydrogen from water and high temperature thermal energy are presented and compared. Increasing the exergy efficiency is equivalent to reducing the entropy production. Starting from a reference reactor for the decomposition of sulfuric acid, two new reactor designs are developed that both reduce the entropy production by 26%. The first design uses optimal control theory to obtain a more uniform distribution of the entropy production. As a result of this functional optimization we obtain optimal temperature profiles over the reactor length. This optimized design is found to perform the best, but it requires significant changes in the heating equipment in order to approximately realize the optimal temperature profiles. A second design is obtained by increasing the reactor length. This leads to a higher pressure drop and requires additional compressor duty. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801585e Exemplaires
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Titre : Characterization of particle fluidization pattern in a gas solid fluidized bed based on acoustic emission (AE) measurement Type de document : texte imprimé Auteurs : Wang Jingdai, Auteur ; Ren Congjing, Auteur ; Yongrong Yang, Auteur Année de publication : 2010 Article en page(s) : pp. 8508–8514 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fluidized bed Acoustic emission measurement Résumé : Flow pattern of the fluidized bed is a key factor for heat transfer and the design of a new reactor. It is important to comprehend the fluidization conditions because the complex correlation between particle−particle and particle−environment in the reactor. In this study, we applied acoustic emission (AE) measurement in monitoring the particle fluidization pattern in a gas−solid bed fluidized with different sorts of particles classified by Geldart. With AE axial time average energy analysis, the flow structure of polyethylene particles was investigated both in the laboratory and plant apparatus. The results showed that the fluidization pattern in the bed is multicirculation, including the main-circulation zone, subcirculation zone, and the stagnant zone. Moreover, the influence of operating variables, such as particle size, superficial gas velocity, static bed height, and particle sorts had also been considered. It was found that the particle size, gas velocity, and particle sorts have significant impacts to the fluidization pattern. In contrast, the height of the stagnant zone did not show direct relation to the static bed height. AE measurement was proved to be reliable for understanding the dynamical features that affect the behavior of the fluidized bed. This can be useful guidance for an industrial process and help improve the process operation and the design of the new reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018774
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8508–8514[article] Characterization of particle fluidization pattern in a gas solid fluidized bed based on acoustic emission (AE) measurement [texte imprimé] / Wang Jingdai, Auteur ; Ren Congjing, Auteur ; Yongrong Yang, Auteur . - 2010 . - pp. 8508–8514.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8508–8514
Mots-clés : Fluidized bed Acoustic emission measurement Résumé : Flow pattern of the fluidized bed is a key factor for heat transfer and the design of a new reactor. It is important to comprehend the fluidization conditions because the complex correlation between particle−particle and particle−environment in the reactor. In this study, we applied acoustic emission (AE) measurement in monitoring the particle fluidization pattern in a gas−solid bed fluidized with different sorts of particles classified by Geldart. With AE axial time average energy analysis, the flow structure of polyethylene particles was investigated both in the laboratory and plant apparatus. The results showed that the fluidization pattern in the bed is multicirculation, including the main-circulation zone, subcirculation zone, and the stagnant zone. Moreover, the influence of operating variables, such as particle size, superficial gas velocity, static bed height, and particle sorts had also been considered. It was found that the particle size, gas velocity, and particle sorts have significant impacts to the fluidization pattern. In contrast, the height of the stagnant zone did not show direct relation to the static bed height. AE measurement was proved to be reliable for understanding the dynamical features that affect the behavior of the fluidized bed. This can be useful guidance for an industrial process and help improve the process operation and the design of the new reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018774 Exemplaires
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Titre : Characterization of particle fluidization pattern in a gas solid fluidized bed based on acoustic emission (AE) measurement Type de document : texte imprimé Auteurs : Wang Jingdai, Auteur ; Ren Congjing, Auteur ; Yongrong Yang, Auteur Année de publication : 2010 Article en page(s) : pp. 8508–8514 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fluidized bed Acoustic emission measurement Résumé : Flow pattern of the fluidized bed is a key factor for heat transfer and the design of a new reactor. It is important to comprehend the fluidization conditions because the complex correlation between particle−particle and particle−environment in the reactor. In this study, we applied acoustic emission (AE) measurement in monitoring the particle fluidization pattern in a gas−solid bed fluidized with different sorts of particles classified by Geldart. With AE axial time average energy analysis, the flow structure of polyethylene particles was investigated both in the laboratory and plant apparatus. The results showed that the fluidization pattern in the bed is multicirculation, including the main-circulation zone, subcirculation zone, and the stagnant zone. Moreover, the influence of operating variables, such as particle size, superficial gas velocity, static bed height, and particle sorts had also been considered. It was found that the particle size, gas velocity, and particle sorts have significant impacts to the fluidization pattern. In contrast, the height of the stagnant zone did not show direct relation to the static bed height. AE measurement was proved to be reliable for understanding the dynamical features that affect the behavior of the fluidized bed. This can be useful guidance for an industrial process and help improve the process operation and the design of the new reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018774
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8508–8514[article] Characterization of particle fluidization pattern in a gas solid fluidized bed based on acoustic emission (AE) measurement [texte imprimé] / Wang Jingdai, Auteur ; Ren Congjing, Auteur ; Yongrong Yang, Auteur . - 2010 . - pp. 8508–8514.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8508–8514
Mots-clés : Fluidized bed Acoustic emission measurement Résumé : Flow pattern of the fluidized bed is a key factor for heat transfer and the design of a new reactor. It is important to comprehend the fluidization conditions because the complex correlation between particle−particle and particle−environment in the reactor. In this study, we applied acoustic emission (AE) measurement in monitoring the particle fluidization pattern in a gas−solid bed fluidized with different sorts of particles classified by Geldart. With AE axial time average energy analysis, the flow structure of polyethylene particles was investigated both in the laboratory and plant apparatus. The results showed that the fluidization pattern in the bed is multicirculation, including the main-circulation zone, subcirculation zone, and the stagnant zone. Moreover, the influence of operating variables, such as particle size, superficial gas velocity, static bed height, and particle sorts had also been considered. It was found that the particle size, gas velocity, and particle sorts have significant impacts to the fluidization pattern. In contrast, the height of the stagnant zone did not show direct relation to the static bed height. AE measurement was proved to be reliable for understanding the dynamical features that affect the behavior of the fluidized bed. This can be useful guidance for an industrial process and help improve the process operation and the design of the new reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018774 Exemplaires
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Titre : A novel priority-slot based continuous-time formulation for crude-oil scheduling problems Type de document : texte imprimé Auteurs : Sylvain Mouret, Auteur ; Ignacio E. Grossmann, Auteur ; Pierre Pestiaux, Auteur Année de publication : 2010 Article en page(s) : pp. 8515–8528 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Crude-oil operations Optimal scheduling Continuous-time formulation Single-operation sequencing (SOS) model Résumé : The optimal scheduling of crude-oil operations in refineries has been studied by various groups during the past decade leading to different mixed integer linear programming (MILP) or mixed integer nonlinear programming (MINLP) formulations. This paper presents a new continuous-time formulation, called single-operation sequencing (SOS) model, which can be used to solve a crude-oil operations problem introduced in previous publications. It is different from previous formulations as it requires to postulate the number of priority-slots in which operations take place, instead of specifying the number of time intervals or event points to be used in the schedule. This MINLP model is also based on the representation of a crude-oil schedule by a single sequence of transfer operations. It allows breaking symmetries involved in the problem, thus enormously reducing the computational times (all instances can be solved within 2 min). A simple two step MILP-NLP procedure has been used to solve the nonconvex MINLP model leading to an optimality gap lower than 4% in all cases. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019592
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8515–8528[article] A novel priority-slot based continuous-time formulation for crude-oil scheduling problems [texte imprimé] / Sylvain Mouret, Auteur ; Ignacio E. Grossmann, Auteur ; Pierre Pestiaux, Auteur . - 2010 . - pp. 8515–8528.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8515–8528
Mots-clés : Crude-oil operations Optimal scheduling Continuous-time formulation Single-operation sequencing (SOS) model Résumé : The optimal scheduling of crude-oil operations in refineries has been studied by various groups during the past decade leading to different mixed integer linear programming (MILP) or mixed integer nonlinear programming (MINLP) formulations. This paper presents a new continuous-time formulation, called single-operation sequencing (SOS) model, which can be used to solve a crude-oil operations problem introduced in previous publications. It is different from previous formulations as it requires to postulate the number of priority-slots in which operations take place, instead of specifying the number of time intervals or event points to be used in the schedule. This MINLP model is also based on the representation of a crude-oil schedule by a single sequence of transfer operations. It allows breaking symmetries involved in the problem, thus enormously reducing the computational times (all instances can be solved within 2 min). A simple two step MILP-NLP procedure has been used to solve the nonconvex MINLP model leading to an optimality gap lower than 4% in all cases. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019592 Exemplaires
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Titre : Local thermodynamic models networks for dynamic process simulation Type de document : texte imprimé Auteurs : Pedro Rafael Bolognese Fernandes, Auteur ; Jorge Otávio Trierweiler, Auteur Année de publication : 2010 Article en page(s) : pp. 8529–8541 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Local thermodynamic models networks Simulating processes K-values Résumé : This paper presents the local thermodynamic models networks (LTMN), a new technique aimed at reducing the time spent in simulating processes that are based on phase equilibrium. The LTMN shown in this work approximate K-values as generated by a conventional property method, with a sensible reduction of the computer burden. The LTMN combine the local thermodynamic models technique and the concepts of multiple modeling to provide a valid approximation on the entire domain of the independent thermodynamic state variables. The paper discusses topics from the local models employed in the LTMN and the division of the space to the interpolation algorithm. Additionally, a new polynomial-time algorithm for the calculation of the bubble point temperature is developed on the basis of the form of the thermodynamic local models. The methods presented are tested in the dynamic simulation of distinct separation processes, for two distinct multicomponent mixtures, with time savings up to 90%. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9001469
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8529–8541[article] Local thermodynamic models networks for dynamic process simulation [texte imprimé] / Pedro Rafael Bolognese Fernandes, Auteur ; Jorge Otávio Trierweiler, Auteur . - 2010 . - pp. 8529–8541.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8529–8541
Mots-clés : Local thermodynamic models networks Simulating processes K-values Résumé : This paper presents the local thermodynamic models networks (LTMN), a new technique aimed at reducing the time spent in simulating processes that are based on phase equilibrium. The LTMN shown in this work approximate K-values as generated by a conventional property method, with a sensible reduction of the computer burden. The LTMN combine the local thermodynamic models technique and the concepts of multiple modeling to provide a valid approximation on the entire domain of the independent thermodynamic state variables. The paper discusses topics from the local models employed in the LTMN and the division of the space to the interpolation algorithm. Additionally, a new polynomial-time algorithm for the calculation of the bubble point temperature is developed on the basis of the form of the thermodynamic local models. The methods presented are tested in the dynamic simulation of distinct separation processes, for two distinct multicomponent mixtures, with time savings up to 90%. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9001469 Exemplaires
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Titre : Fuzzy model-based predictive hybrid control of polymerization processes Type de document : texte imprimé Auteurs : Nádson M. Nascimento Lima, Auteur ; Flavio Manenti, Auteur ; Rubens Maciel Filho, Auteur Année de publication : 2010 Article en page(s) : pp. 8542–8550 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fuzzy model-based predictive hybrid controller Polymerization processes Nonlinear behaviors Résumé : This paper presents a fuzzy model-based predictive hybrid controller (FMPHC) for polymerization processes based on Takagi−Sugeno models and moving horizon methodology. Such processes are characterized by strongly nonlinear behaviors, which may either require significant effort to tune model-based controllers or render them ineffective. The proposed FMPHC is a promising integrated approach to handle nonlinearities and control issues. An industrial copolymerization process of ethylene and 1-butene is adopted to validate the proposed approach and to compare it to the most widespread advanced multivariable control. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900352d
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8542–8550[article] Fuzzy model-based predictive hybrid control of polymerization processes [texte imprimé] / Nádson M. Nascimento Lima, Auteur ; Flavio Manenti, Auteur ; Rubens Maciel Filho, Auteur . - 2010 . - pp. 8542–8550.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8542–8550
Mots-clés : Fuzzy model-based predictive hybrid controller Polymerization processes Nonlinear behaviors Résumé : This paper presents a fuzzy model-based predictive hybrid controller (FMPHC) for polymerization processes based on Takagi−Sugeno models and moving horizon methodology. Such processes are characterized by strongly nonlinear behaviors, which may either require significant effort to tune model-based controllers or render them ineffective. The proposed FMPHC is a promising integrated approach to handle nonlinearities and control issues. An industrial copolymerization process of ethylene and 1-butene is adopted to validate the proposed approach and to compare it to the most widespread advanced multivariable control. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900352d Exemplaires
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Titre : Sequential methodology for scheduling of heat-integrated batch plants Type de document : texte imprimé Auteurs : Iskandar Halim, Auteur ; Rajagopalan Srinivasan, Auteur Année de publication : 2010 Article en page(s) : pp. 8551–8565 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Heat integration Scheduling Sequential framework Résumé : Optimal scheduling of tasks to be performed in different unit operations is of paramount importance in the batch processes. The pressure toward sustainable operation has warranted more attentions to be paid to the issues of heat integration to reduce the utility consumption. This paper presents a new approach for incorporating heat integration in batch process scheduling. The method is based on a sequential framework, where the overall problem is decomposed into two sequentially solved problems of scheduling and heat integration. First, the schedule is optimized to meet the economic objective such as makespan or profit. Next, alternate schedules are generated through a stochastic search-based integer cut procedure that adds further constraints to the scheduling formulation. Such schedules may be the alternate optima of the scheduling problem. Finally, heat integration analysis coupled with the time average model (TAM) and time slice model (TSM) is applied to each of the resulting schedules to establish the minimum utility targets. The approach is based on the precept that opportunities for heat integration between tasks are higher in near-optimal schedules where tasks are temporally clustered together. The method differs from other sequential approaches published in the literature in that the heat integration problem is solved with the intent to retain the optimality of the scheduling solution. The proposed method has the ability to handle problems too complex to be solved using simultaneous optimization approaches. It has been applied to two literature case studies. The first one involves profit maximization as the objective function. The second one entails a more complex scenario involving makespan and utilities. The results from both case studies demonstrate the effectiveness of the approach. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900367j
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8551–8565[article] Sequential methodology for scheduling of heat-integrated batch plants [texte imprimé] / Iskandar Halim, Auteur ; Rajagopalan Srinivasan, Auteur . - 2010 . - pp. 8551–8565.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8551–8565
Mots-clés : Heat integration Scheduling Sequential framework Résumé : Optimal scheduling of tasks to be performed in different unit operations is of paramount importance in the batch processes. The pressure toward sustainable operation has warranted more attentions to be paid to the issues of heat integration to reduce the utility consumption. This paper presents a new approach for incorporating heat integration in batch process scheduling. The method is based on a sequential framework, where the overall problem is decomposed into two sequentially solved problems of scheduling and heat integration. First, the schedule is optimized to meet the economic objective such as makespan or profit. Next, alternate schedules are generated through a stochastic search-based integer cut procedure that adds further constraints to the scheduling formulation. Such schedules may be the alternate optima of the scheduling problem. Finally, heat integration analysis coupled with the time average model (TAM) and time slice model (TSM) is applied to each of the resulting schedules to establish the minimum utility targets. The approach is based on the precept that opportunities for heat integration between tasks are higher in near-optimal schedules where tasks are temporally clustered together. The method differs from other sequential approaches published in the literature in that the heat integration problem is solved with the intent to retain the optimality of the scheduling solution. The proposed method has the ability to handle problems too complex to be solved using simultaneous optimization approaches. It has been applied to two literature case studies. The first one involves profit maximization as the objective function. The second one entails a more complex scenario involving makespan and utilities. The results from both case studies demonstrate the effectiveness of the approach. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900367j Exemplaires
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Titre : Framework for consumer-integrated optimal product design Type de document : texte imprimé Auteurs : Beverly V. Smith, Auteur ; Marianthi Ierapepritou, Auteur Année de publication : 2010 Article en page(s) : pp. 8566–8574 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Comprehensive framework Multiobjective optimization approach Résumé : The need for rapid product design, resulting from time to market pressure, is accompanied by an increasing demand for product differentiation. In order to meet these demands, firms are seeking more efficient ways to integrate consumer’s input into the product design process. Furthermore, appropriate integration of consumer influence yields the tangible benefit of increased probability of product acceptance in the marketplace. The objective of this paper is to introduce a comprehensive framework that integrates consumer’s influence into the design space using a multiobjective optimization approach. We formulate the problem as a biobjective mixed-integer problem, for which the compromised solution is represented as a set of efficient points. A case study involving optimal design of an under eye cream product was used to illustrate the application of the framework. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900377e
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8566–8574[article] Framework for consumer-integrated optimal product design [texte imprimé] / Beverly V. Smith, Auteur ; Marianthi Ierapepritou, Auteur . - 2010 . - pp. 8566–8574.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8566–8574
Mots-clés : Comprehensive framework Multiobjective optimization approach Résumé : The need for rapid product design, resulting from time to market pressure, is accompanied by an increasing demand for product differentiation. In order to meet these demands, firms are seeking more efficient ways to integrate consumer’s input into the product design process. Furthermore, appropriate integration of consumer influence yields the tangible benefit of increased probability of product acceptance in the marketplace. The objective of this paper is to introduce a comprehensive framework that integrates consumer’s influence into the design space using a multiobjective optimization approach. We formulate the problem as a biobjective mixed-integer problem, for which the compromised solution is represented as a set of efficient points. A case study involving optimal design of an under eye cream product was used to illustrate the application of the framework. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900377e Exemplaires
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Titre : Combined quadrature method of moments and method of characteristics approach for efficient solution of population balance models for dynamic modeling and crystal size distribution control of crystallization processes Type de document : texte imprimé Auteurs : E. Aamir, Auteur ; Z. K. Nagy, Auteur ; C. D. Rielly, Auteur Année de publication : 2010 Article en page(s) : pp. 8575–8584 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Crystal size distribution Quadrature method of moments Method characteristics Crystallization processes Résumé : The paper presents a novel methodology for the estimation of the shape of the crystal size distribution (CSD) during a crystallization process. The approach, based on a combination of the quadrature method of moments (QMOM) and the method of characteristics (MOCH), provides a computationally efficient solution of the population balance equation (PBE) and hence a fast prediction of the dynamic evolution of the CSD for an entire batch. Furthermore, under the assumption that for supersaturation-controlled crystallization the main phenomenon is growth, an analytical CSD estimator is derived for generic size-dependent growth kinetics. These approaches are evaluated for the crystallization of potassium alum in water. The model parameters are identified on the basis of industrial experimental data, obtained using an efficient implementation of supersaturation control. The proposed methods are able to predict and reconstruct the dynamic evolution of the CSD during the batch. The QMOM−MOCH solution approach is evaluated in a model-based dynamic optimization study, which aims to obtain the optimal temperature profiles required to achieve desired target CSDs. The technique can serve as a soft sensor for predicting the CSD, or as a computationally efficient algorithm for off-line design or online adaptation of operating policies based on knowledge of the full CSD data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900430t
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8575–8584[article] Combined quadrature method of moments and method of characteristics approach for efficient solution of population balance models for dynamic modeling and crystal size distribution control of crystallization processes [texte imprimé] / E. Aamir, Auteur ; Z. K. Nagy, Auteur ; C. D. Rielly, Auteur . - 2010 . - pp. 8575–8584.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8575–8584
Mots-clés : Crystal size distribution Quadrature method of moments Method characteristics Crystallization processes Résumé : The paper presents a novel methodology for the estimation of the shape of the crystal size distribution (CSD) during a crystallization process. The approach, based on a combination of the quadrature method of moments (QMOM) and the method of characteristics (MOCH), provides a computationally efficient solution of the population balance equation (PBE) and hence a fast prediction of the dynamic evolution of the CSD for an entire batch. Furthermore, under the assumption that for supersaturation-controlled crystallization the main phenomenon is growth, an analytical CSD estimator is derived for generic size-dependent growth kinetics. These approaches are evaluated for the crystallization of potassium alum in water. The model parameters are identified on the basis of industrial experimental data, obtained using an efficient implementation of supersaturation control. The proposed methods are able to predict and reconstruct the dynamic evolution of the CSD during the batch. The QMOM−MOCH solution approach is evaluated in a model-based dynamic optimization study, which aims to obtain the optimal temperature profiles required to achieve desired target CSDs. The technique can serve as a soft sensor for predicting the CSD, or as a computationally efficient algorithm for off-line design or online adaptation of operating policies based on knowledge of the full CSD data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900430t Exemplaires
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Titre : Multiway gaussian mixture model based multiphase batch process monitoring Type de document : texte imprimé Auteurs : Jie Yu, Auteur ; S. Joe Qin, Auteur Année de publication : 2010 Article en page(s) : pp. 8585–8594 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gaussian mixture model Monitoring approach Résumé : A novel batch process monitoring approach is proposed in this article to handle batch processes with multiple operation phases. The basic idea is to combine the Gaussian mixture model (GMM) with hybrid unfolding of a multiway data matrix to partition all the sampling points into different clusters. Then, two sequential cluster alignments are used to adjust clusters so that each of them only contains consecutive sampling instants, and all the training batches at the same sampling time belong to the same cluster. The identified multiple clusters correspond to different operation phases in the batch process. Further, a localized probability index is defined to examine each sampling point of a monitored batch relative to its corresponding operation phase. Subsequently, the occurrence and duration of process faults can be detected in this way. The proposed batch monitoring approach is applied to a simulated penicillin fermentation process and compared with the conventional multiway principal component analysis (MPCA). The comparison of monitoring results demonstrates that the multiphase based approach is superior to the global MPCA method in detecting different types of faults in batch processes with a much higher detection rate and fault sensitivity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900479g
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8585–8594[article] Multiway gaussian mixture model based multiphase batch process monitoring [texte imprimé] / Jie Yu, Auteur ; S. Joe Qin, Auteur . - 2010 . - pp. 8585–8594.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8585–8594
Mots-clés : Gaussian mixture model Monitoring approach Résumé : A novel batch process monitoring approach is proposed in this article to handle batch processes with multiple operation phases. The basic idea is to combine the Gaussian mixture model (GMM) with hybrid unfolding of a multiway data matrix to partition all the sampling points into different clusters. Then, two sequential cluster alignments are used to adjust clusters so that each of them only contains consecutive sampling instants, and all the training batches at the same sampling time belong to the same cluster. The identified multiple clusters correspond to different operation phases in the batch process. Further, a localized probability index is defined to examine each sampling point of a monitored batch relative to its corresponding operation phase. Subsequently, the occurrence and duration of process faults can be detected in this way. The proposed batch monitoring approach is applied to a simulated penicillin fermentation process and compared with the conventional multiway principal component analysis (MPCA). The comparison of monitoring results demonstrates that the multiphase based approach is superior to the global MPCA method in detecting different types of faults in batch processes with a much higher detection rate and fault sensitivity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900479g Exemplaires
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Titre : Multiway gaussian mixture model based multiphase batch process monitoring Type de document : texte imprimé Auteurs : Jie Yu, Auteur ; S. Joe Qin, Auteur Année de publication : 2010 Article en page(s) : pp. 8585–8594 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gaussian mixture model Monitoring approach Résumé : A novel batch process monitoring approach is proposed in this article to handle batch processes with multiple operation phases. The basic idea is to combine the Gaussian mixture model (GMM) with hybrid unfolding of a multiway data matrix to partition all the sampling points into different clusters. Then, two sequential cluster alignments are used to adjust clusters so that each of them only contains consecutive sampling instants, and all the training batches at the same sampling time belong to the same cluster. The identified multiple clusters correspond to different operation phases in the batch process. Further, a localized probability index is defined to examine each sampling point of a monitored batch relative to its corresponding operation phase. Subsequently, the occurrence and duration of process faults can be detected in this way. The proposed batch monitoring approach is applied to a simulated penicillin fermentation process and compared with the conventional multiway principal component analysis (MPCA). The comparison of monitoring results demonstrates that the multiphase based approach is superior to the global MPCA method in detecting different types of faults in batch processes with a much higher detection rate and fault sensitivity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900479g
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8585–8594[article] Multiway gaussian mixture model based multiphase batch process monitoring [texte imprimé] / Jie Yu, Auteur ; S. Joe Qin, Auteur . - 2010 . - pp. 8585–8594.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8585–8594
Mots-clés : Gaussian mixture model Monitoring approach Résumé : A novel batch process monitoring approach is proposed in this article to handle batch processes with multiple operation phases. The basic idea is to combine the Gaussian mixture model (GMM) with hybrid unfolding of a multiway data matrix to partition all the sampling points into different clusters. Then, two sequential cluster alignments are used to adjust clusters so that each of them only contains consecutive sampling instants, and all the training batches at the same sampling time belong to the same cluster. The identified multiple clusters correspond to different operation phases in the batch process. Further, a localized probability index is defined to examine each sampling point of a monitored batch relative to its corresponding operation phase. Subsequently, the occurrence and duration of process faults can be detected in this way. The proposed batch monitoring approach is applied to a simulated penicillin fermentation process and compared with the conventional multiway principal component analysis (MPCA). The comparison of monitoring results demonstrates that the multiphase based approach is superior to the global MPCA method in detecting different types of faults in batch processes with a much higher detection rate and fault sensitivity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900479g Exemplaires
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Titre : Model-based insulin therapy scheduling : a mixed-integer nonlinear dynamic optimization approach Type de document : texte imprimé Auteurs : Cheng-Liang Chen, Auteur ; Hong-Wen Tsai, Auteur Année de publication : 2010 Article en page(s) : pp. 8595–8604 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Insulin injection scheduling strategy Mixed-integer nonlinear dynamic program Résumé : This article aims at developing a better insulin injection scheduling strategy for diabetes. For this purpose, the subcutaneous (sc) absorption behaviors of available insulin and the overall glucose−insulin dynamics for diabetes are investigated at first. Therein several sets of clinical data from literature are applied to verify the overall glucose−insulin dynamic models through parametric estimation. The problem of searching the optimal injected time, type, and dosage of insulin are then formulated as a mixed-integer nonlinear dynamic program (MINDP). The optimal injection schedules are consequently found for a 24 h cycle in three scenarios by adjusting either the insulin injection times, or insulin types, or insulin dosage, or other combinations of these factors. The corresponding improvement in glycemia control in each scenario is demonstrated. The robustness of suggested therapy schedules to inconsistency of scheduled situations is finally exemplified. It is expected that the proposed optimal therapy scheduling can serve as a valuable reference for physicians and patients to take better glucose control on a daily basis. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005673
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8595–8604[article] Model-based insulin therapy scheduling : a mixed-integer nonlinear dynamic optimization approach [texte imprimé] / Cheng-Liang Chen, Auteur ; Hong-Wen Tsai, Auteur . - 2010 . - pp. 8595–8604.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8595–8604
Mots-clés : Insulin injection scheduling strategy Mixed-integer nonlinear dynamic program Résumé : This article aims at developing a better insulin injection scheduling strategy for diabetes. For this purpose, the subcutaneous (sc) absorption behaviors of available insulin and the overall glucose−insulin dynamics for diabetes are investigated at first. Therein several sets of clinical data from literature are applied to verify the overall glucose−insulin dynamic models through parametric estimation. The problem of searching the optimal injected time, type, and dosage of insulin are then formulated as a mixed-integer nonlinear dynamic program (MINDP). The optimal injection schedules are consequently found for a 24 h cycle in three scenarios by adjusting either the insulin injection times, or insulin types, or insulin dosage, or other combinations of these factors. The corresponding improvement in glycemia control in each scenario is demonstrated. The robustness of suggested therapy schedules to inconsistency of scheduled situations is finally exemplified. It is expected that the proposed optimal therapy scheduling can serve as a valuable reference for physicians and patients to take better glucose control on a daily basis. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005673 Exemplaires
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Titre : Recovery of actinides and lanthanides from high-level waste using hollow-fiber supported liquid membrane with TODGA as the carrier Type de document : texte imprimé Auteurs : Seraj A. Ansari, Auteur ; Prasanta K. Mohapatra, Auteur ; Vijay K. Manchanda, Auteur Année de publication : 2010 Article en page(s) : pp. 8605–8612 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Trivalent actinides/lanthanides Hollow-fiber supported liquid membrane Normal paraffinic hydrocarbon Résumé : Transport behavior of trivalent actinides/lanthanides from nitric acid solutions into distilled water was investigated using polypropylene hollow-fiber supported liquid membrane (HFSLM) technique. A mixture of 0.1 M TODGA (N,N,N′,N′-tetraoctyl diglycolamide) + 0.5 M DHOA (N,N-dihexyl octanamide) dissolved in normal paraffinic hydrocarbon (NPH) was optimized as a suitable carrier. The permeability of the transported metal species was calculated with the help of various diffusional parameters. The permeation of metal ions increased with the feed acidity; however, their transport rates were significantly affected at higher acidity (>3 M HNO3) owing to carrier-aided co-transport of nitric acid. Mass transfer coefficients were calculated on the basis of the described model, whose success was verified by excellent matching of the membrane diffusion coefficient values calculated by the given model and Wilke−Chang equation. Quantitative transport of trivalent actinides and lanthanides was achieved in 30 min from pressurized heavy water reactor simulated high-level nuclear waste. The stability of the HFSLM system was found to be satisfactory in eight successive runs. The results suggested the possible application of TODGA-HFSLM system for the recovery of actinides from high-level wastes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900265y
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8605–8612[article] Recovery of actinides and lanthanides from high-level waste using hollow-fiber supported liquid membrane with TODGA as the carrier [texte imprimé] / Seraj A. Ansari, Auteur ; Prasanta K. Mohapatra, Auteur ; Vijay K. Manchanda, Auteur . - 2010 . - pp. 8605–8612.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8605–8612
Mots-clés : Trivalent actinides/lanthanides Hollow-fiber supported liquid membrane Normal paraffinic hydrocarbon Résumé : Transport behavior of trivalent actinides/lanthanides from nitric acid solutions into distilled water was investigated using polypropylene hollow-fiber supported liquid membrane (HFSLM) technique. A mixture of 0.1 M TODGA (N,N,N′,N′-tetraoctyl diglycolamide) + 0.5 M DHOA (N,N-dihexyl octanamide) dissolved in normal paraffinic hydrocarbon (NPH) was optimized as a suitable carrier. The permeability of the transported metal species was calculated with the help of various diffusional parameters. The permeation of metal ions increased with the feed acidity; however, their transport rates were significantly affected at higher acidity (>3 M HNO3) owing to carrier-aided co-transport of nitric acid. Mass transfer coefficients were calculated on the basis of the described model, whose success was verified by excellent matching of the membrane diffusion coefficient values calculated by the given model and Wilke−Chang equation. Quantitative transport of trivalent actinides and lanthanides was achieved in 30 min from pressurized heavy water reactor simulated high-level nuclear waste. The stability of the HFSLM system was found to be satisfactory in eight successive runs. The results suggested the possible application of TODGA-HFSLM system for the recovery of actinides from high-level wastes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900265y Exemplaires
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Titre : Simulation of flash separation in polyethylene industrial processing : comparison of SRK and SL equations of state Type de document : texte imprimé Auteurs : G. M. N. Costa, Auteur ; Y. Guerrieri, Auteur ; S. Kislansky, Auteur Année de publication : 2010 Article en page(s) : pp. 8613–8628 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Soave-Redlich-Kwong Sanchez and Lacombe equations Polyethylene industrial separators Résumé : The Soave−Redlich−Kwong (SRK) and the Sanchez and Lacombe (SL) equations of state are applied to the flash simulation of polyethylene industrial separators, specifically low-density polyethylene (eight resins) and linear low-density polyethylene (25 resins). Three mixing rules are used in the SRK equation: van der Waals (VDW) one-fluid, Wong−Sandler, and LCVM (linear combination of the Vidal and Michelsen mixing rules). The latter two mixing rules incorporate the Bogdanic and Vidal activity coefficient model. All these models involve two adjustable parameters. The results indicate that SL is the best model to simulate the flash separation of polyethylene under industrial conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801652q
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8613–8628[article] Simulation of flash separation in polyethylene industrial processing : comparison of SRK and SL equations of state [texte imprimé] / G. M. N. Costa, Auteur ; Y. Guerrieri, Auteur ; S. Kislansky, Auteur . - 2010 . - pp. 8613–8628.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8613–8628
Mots-clés : Soave-Redlich-Kwong Sanchez and Lacombe equations Polyethylene industrial separators Résumé : The Soave−Redlich−Kwong (SRK) and the Sanchez and Lacombe (SL) equations of state are applied to the flash simulation of polyethylene industrial separators, specifically low-density polyethylene (eight resins) and linear low-density polyethylene (25 resins). Three mixing rules are used in the SRK equation: van der Waals (VDW) one-fluid, Wong−Sandler, and LCVM (linear combination of the Vidal and Michelsen mixing rules). The latter two mixing rules incorporate the Bogdanic and Vidal activity coefficient model. All these models involve two adjustable parameters. The results indicate that SL is the best model to simulate the flash separation of polyethylene under industrial conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801652q Exemplaires
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Titre : Effects of design and operating parameters on CO2 absorption in microchannel contactors Type de document : texte imprimé Auteurs : Haining Niu, Auteur ; Liwei Pan, Auteur ; Hongjiu Su, Auteur Année de publication : 2010 Article en page(s) : pp. 8629–8634 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Microchannel contactors CO2 absorption Résumé : This study provides experimental data on the performance of microchannel contactors for CO2 absorption. An aqueous solution of piperazine (PZ) activated N-methyldiethanolamine (MDEA) and a mixture of CO2/N2 were selected as the working fluids. Three different sizes of microchannels, with hydraulic diameters of 0.5, 1, and 2 mm and the same length of 180 mm, served as the contactors. With a decrease in the hydraulic diameter the larger surface to volume ratio can be achieved. The mass transfer rates increased considerably, and the size effect of mass transfer was observed. Various operating parameters, including the activator, the temperature of gas and liquid flow, the inlet CO2 molar fraction, the superficial gas and liquid velocities, and the operating pressure were also evaluated. The results obtained illustrated a great potential of microchannel contactors when they were applied to the separation of CO2. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018966
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8629–8634[article] Effects of design and operating parameters on CO2 absorption in microchannel contactors [texte imprimé] / Haining Niu, Auteur ; Liwei Pan, Auteur ; Hongjiu Su, Auteur . - 2010 . - pp. 8629–8634.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8629–8634
Mots-clés : Microchannel contactors CO2 absorption Résumé : This study provides experimental data on the performance of microchannel contactors for CO2 absorption. An aqueous solution of piperazine (PZ) activated N-methyldiethanolamine (MDEA) and a mixture of CO2/N2 were selected as the working fluids. Three different sizes of microchannels, with hydraulic diameters of 0.5, 1, and 2 mm and the same length of 180 mm, served as the contactors. With a decrease in the hydraulic diameter the larger surface to volume ratio can be achieved. The mass transfer rates increased considerably, and the size effect of mass transfer was observed. Various operating parameters, including the activator, the temperature of gas and liquid flow, the inlet CO2 molar fraction, the superficial gas and liquid velocities, and the operating pressure were also evaluated. The results obtained illustrated a great potential of microchannel contactors when they were applied to the separation of CO2. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018966 Exemplaires
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Titre : Synthesis of distillation column sequences for nonsharp separations Type de document : texte imprimé Auteurs : Javad Ivakpour, Auteur ; Norollah Kasiri, Auteur Année de publication : 2010 Article en page(s) : pp. 8635–8649 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Distillation column c components m multicomponent Nonsharp separation Résumé : In this paper an algorithm to generate all possible distillation column sequences for a nonsharp separation of c components to m multicomponent as well as pure desired products, based on the product specifications, is presented. Each desired product is defined by the minimum and maximum acceptable values of product rates as well as the concentration of each component. The possible sequences are generated by the introduction of a separation matrix. In the proposed algorithm each sequence can include between 1 and c − 1 simple and/or complex distillation columns and bypass streams. The sequences with less than c − 1 distillation columns can be generated systematically by the proposed algorithm. Also, a design strategy has been proposed for the optimization of the sequences. This algorithm has been used for a nonsharp separation example. A sequence with less than c − 1 number of distillation columns and bypass streams is selected as the optimum structure for this example. This optimum sequence can cause significant savings of up to 22% in TAC relative to the traditional sequences with simple distillation columns. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie802013r
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8635–8649[article] Synthesis of distillation column sequences for nonsharp separations [texte imprimé] / Javad Ivakpour, Auteur ; Norollah Kasiri, Auteur . - 2010 . - pp. 8635–8649.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8635–8649
Mots-clés : Distillation column c components m multicomponent Nonsharp separation Résumé : In this paper an algorithm to generate all possible distillation column sequences for a nonsharp separation of c components to m multicomponent as well as pure desired products, based on the product specifications, is presented. Each desired product is defined by the minimum and maximum acceptable values of product rates as well as the concentration of each component. The possible sequences are generated by the introduction of a separation matrix. In the proposed algorithm each sequence can include between 1 and c − 1 simple and/or complex distillation columns and bypass streams. The sequences with less than c − 1 distillation columns can be generated systematically by the proposed algorithm. Also, a design strategy has been proposed for the optimization of the sequences. This algorithm has been used for a nonsharp separation example. A sequence with less than c − 1 number of distillation columns and bypass streams is selected as the optimum structure for this example. This optimum sequence can cause significant savings of up to 22% in TAC relative to the traditional sequences with simple distillation columns. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie802013r Exemplaires
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Titre : Behavior of inorganic nanoparticles in silver polymer electrolytes and their effects on silver ion activity for facilitated olefin transport Type de document : texte imprimé Auteurs : Sang Wook Kang, Auteur ; Wanki Bae, Auteur ; Jong Hak Kim, Auteur Année de publication : 2010 Article en page(s) : pp. 8650–8654 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : TiO2 nanoparticles Al2O3 Silver polymer electrolytes Résumé : TiO2 and Al2O3 nanoparticles having different chemical properties were introduced into a poly(2-ethyl-2-oxazoline) (POZ) membrane to make inactive AgNO3 chemically more active in olefin complexation, resulting in facilitated olefin transport. The interaction schemes were particularly emphasized to understand the activation of AgNO3 for facilitated olefin transport. The separation performances were similar in both cases, consistent with similar changes in the binding energy of silver ions and the relative concentrations of the added ionic species. However, the bond strength of C═O in POZ increased with TiO2 whereas it decreased with Al2O3, as confirmed by FT-IR spectroscopy. This difference was explained in terms of the difference in the zeta potential: TiO2 and Al2O3 displayed zeta potentials of −18 and +6.5 mV at pH 4, respectively. On the basis of these, the following interaction scheme was proposed: the TiO2 nanoparticles predominantly interact with silver cations, whereas the Al2O3 nanoparticles preferentially interact with NO3−. As a result, both nanoparticles help to loosen the bond strength between Ag+ and NO3−, resulting in the activation of the silver cations in olefin complexation; consequently, olefin transport is facilitated, which results in improved separation performance in the separation of propylene/propane mixtures. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9000103
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8650–8654[article] Behavior of inorganic nanoparticles in silver polymer electrolytes and their effects on silver ion activity for facilitated olefin transport [texte imprimé] / Sang Wook Kang, Auteur ; Wanki Bae, Auteur ; Jong Hak Kim, Auteur . - 2010 . - pp. 8650–8654.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8650–8654
Mots-clés : TiO2 nanoparticles Al2O3 Silver polymer electrolytes Résumé : TiO2 and Al2O3 nanoparticles having different chemical properties were introduced into a poly(2-ethyl-2-oxazoline) (POZ) membrane to make inactive AgNO3 chemically more active in olefin complexation, resulting in facilitated olefin transport. The interaction schemes were particularly emphasized to understand the activation of AgNO3 for facilitated olefin transport. The separation performances were similar in both cases, consistent with similar changes in the binding energy of silver ions and the relative concentrations of the added ionic species. However, the bond strength of C═O in POZ increased with TiO2 whereas it decreased with Al2O3, as confirmed by FT-IR spectroscopy. This difference was explained in terms of the difference in the zeta potential: TiO2 and Al2O3 displayed zeta potentials of −18 and +6.5 mV at pH 4, respectively. On the basis of these, the following interaction scheme was proposed: the TiO2 nanoparticles predominantly interact with silver cations, whereas the Al2O3 nanoparticles preferentially interact with NO3−. As a result, both nanoparticles help to loosen the bond strength between Ag+ and NO3−, resulting in the activation of the silver cations in olefin complexation; consequently, olefin transport is facilitated, which results in improved separation performance in the separation of propylene/propane mixtures. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9000103 Exemplaires
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Titre : Intensification of mass transfer in hollow fiber modules by adding solid particles Type de document : texte imprimé Auteurs : Zhang, Weidong, Auteur ; Geng Chen, Auteur ; Jiang Li, Auteur Année de publication : 2010 Article en page(s) : pp. 8655–8662 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hollow fiber contactor Absorption performance Shell side absorbent Ultrasound Résumé : A method of improving the absorption performance in hollow fiber contactor by adding a third solid phase into the shell side absorbent is proposed. Powdered kieselgur, graphite, and BaSO4 are chosen as the additives to intensify the absorption process of the CO2/NaOH(aq) system. Ultrasound is used in this work as an approach to make the solid particles suspend in the liquid absorbent. The mass-transfer rate is enhanced about 40% by adding solid particles into the absorbent liquid in the presence of ultrasound. As for different types of particles, the smaller the density difference between the absorbent and the solid, the higher enhancement factor obtained. The enhancement factor is a function of the solids loading as well as the liquid velocity in the shell side of the module. The mass-transfer coefficient and enhancement factor remain almost the same with increasing pH from 7 to 11; as pH further increases, both the mass-transfer coefficient and the enhancement factor are increasing dramatically. The results also indicate that the enhancement factors increase with an increase of the packing density. The residence time distribution (RTD) curves are measured to observe the flow status in the shell side; the results demonstrate that addition of solid particles can improve the flow conditions in the shell side. A mathematical model for the intensification process based on surface renewal theory is developed; the calculated results have a good agreement with the experimental results under the present experimental conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004964
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8655–8662[article] Intensification of mass transfer in hollow fiber modules by adding solid particles [texte imprimé] / Zhang, Weidong, Auteur ; Geng Chen, Auteur ; Jiang Li, Auteur . - 2010 . - pp. 8655–8662.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8655–8662
Mots-clés : Hollow fiber contactor Absorption performance Shell side absorbent Ultrasound Résumé : A method of improving the absorption performance in hollow fiber contactor by adding a third solid phase into the shell side absorbent is proposed. Powdered kieselgur, graphite, and BaSO4 are chosen as the additives to intensify the absorption process of the CO2/NaOH(aq) system. Ultrasound is used in this work as an approach to make the solid particles suspend in the liquid absorbent. The mass-transfer rate is enhanced about 40% by adding solid particles into the absorbent liquid in the presence of ultrasound. As for different types of particles, the smaller the density difference between the absorbent and the solid, the higher enhancement factor obtained. The enhancement factor is a function of the solids loading as well as the liquid velocity in the shell side of the module. The mass-transfer coefficient and enhancement factor remain almost the same with increasing pH from 7 to 11; as pH further increases, both the mass-transfer coefficient and the enhancement factor are increasing dramatically. The results also indicate that the enhancement factors increase with an increase of the packing density. The residence time distribution (RTD) curves are measured to observe the flow status in the shell side; the results demonstrate that addition of solid particles can improve the flow conditions in the shell side. A mathematical model for the intensification process based on surface renewal theory is developed; the calculated results have a good agreement with the experimental results under the present experimental conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004964 Exemplaires
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Titre : Intensification of mass transfer in hollow fiber modules by adding solid particles Type de document : texte imprimé Auteurs : Zhang, Weidong, Auteur ; Geng Chen, Auteur ; Jiang Li, Auteur Année de publication : 2010 Article en page(s) : pp. 8655–8662 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hollow fiber contactor Absorption performance Shell side absorbent Ultrasound Résumé : A method of improving the absorption performance in hollow fiber contactor by adding a third solid phase into the shell side absorbent is proposed. Powdered kieselgur, graphite, and BaSO4 are chosen as the additives to intensify the absorption process of the CO2/NaOH(aq) system. Ultrasound is used in this work as an approach to make the solid particles suspend in the liquid absorbent. The mass-transfer rate is enhanced about 40% by adding solid particles into the absorbent liquid in the presence of ultrasound. As for different types of particles, the smaller the density difference between the absorbent and the solid, the higher enhancement factor obtained. The enhancement factor is a function of the solids loading as well as the liquid velocity in the shell side of the module. The mass-transfer coefficient and enhancement factor remain almost the same with increasing pH from 7 to 11; as pH further increases, both the mass-transfer coefficient and the enhancement factor are increasing dramatically. The results also indicate that the enhancement factors increase with an increase of the packing density. The residence time distribution (RTD) curves are measured to observe the flow status in the shell side; the results demonstrate that addition of solid particles can improve the flow conditions in the shell side. A mathematical model for the intensification process based on surface renewal theory is developed; the calculated results have a good agreement with the experimental results under the present experimental conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004964
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8655–8662[article] Intensification of mass transfer in hollow fiber modules by adding solid particles [texte imprimé] / Zhang, Weidong, Auteur ; Geng Chen, Auteur ; Jiang Li, Auteur . - 2010 . - pp. 8655–8662.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8655–8662
Mots-clés : Hollow fiber contactor Absorption performance Shell side absorbent Ultrasound Résumé : A method of improving the absorption performance in hollow fiber contactor by adding a third solid phase into the shell side absorbent is proposed. Powdered kieselgur, graphite, and BaSO4 are chosen as the additives to intensify the absorption process of the CO2/NaOH(aq) system. Ultrasound is used in this work as an approach to make the solid particles suspend in the liquid absorbent. The mass-transfer rate is enhanced about 40% by adding solid particles into the absorbent liquid in the presence of ultrasound. As for different types of particles, the smaller the density difference between the absorbent and the solid, the higher enhancement factor obtained. The enhancement factor is a function of the solids loading as well as the liquid velocity in the shell side of the module. The mass-transfer coefficient and enhancement factor remain almost the same with increasing pH from 7 to 11; as pH further increases, both the mass-transfer coefficient and the enhancement factor are increasing dramatically. The results also indicate that the enhancement factors increase with an increase of the packing density. The residence time distribution (RTD) curves are measured to observe the flow status in the shell side; the results demonstrate that addition of solid particles can improve the flow conditions in the shell side. A mathematical model for the intensification process based on surface renewal theory is developed; the calculated results have a good agreement with the experimental results under the present experimental conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004964 Exemplaires
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Titre : Enhancement of gas selectivities of hexafluoroisopropylidene-based polyimides with poly(methylmethacrylate) blending Type de document : texte imprimé Auteurs : Hyungu Im, Auteur ; Hyomi Kim, Auteur ; Chang Keun Kim, Auteur Année de publication : 2010 Article en page(s) : pp. 8663–8669 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Poor gas selectivity Polyimides Hexafluoroisopropylidene diphthalic anhydride diamine Diaminobenzoic acid Résumé : To enhance poor gas selectivity of polyimides based on hexafluoroisopropylidene diphthalic anhydride (6FDA), such as 6FDA−4,4′-hexafluoroisopropylidene diamine (6FDA−6FpDA) and 6FDA−6FpDA:diaminobenzoic acid (6FDA−6FpDA:DABA), membranes were fabricated from their blends with poly(methylmethacrylate) (PMMA). The resulting polyimides formed homogeneous mixtures with PMMA, regardless of the blend compositions. The miscible blends underwent phase separation upon heating due to the lower critical solution temperature phase behavior. The phase separation temperature of the 6FDA−6FpDA/PMMA blend was greater than that of the 6FDA−6FpDA:DABA/PMMA when the composition was fixed. Adding a small amount of PMMA dramatically increased the gas selectivity of the membrane. In addition, the gas selectivity of most blends was better than that of pure PMMA. The membranes showed performance advantages for the trade-off trend between gas permeability coefficient and selectivity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900643p
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8663–8669[article] Enhancement of gas selectivities of hexafluoroisopropylidene-based polyimides with poly(methylmethacrylate) blending [texte imprimé] / Hyungu Im, Auteur ; Hyomi Kim, Auteur ; Chang Keun Kim, Auteur . - 2010 . - pp. 8663–8669.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8663–8669
Mots-clés : Poor gas selectivity Polyimides Hexafluoroisopropylidene diphthalic anhydride diamine Diaminobenzoic acid Résumé : To enhance poor gas selectivity of polyimides based on hexafluoroisopropylidene diphthalic anhydride (6FDA), such as 6FDA−4,4′-hexafluoroisopropylidene diamine (6FDA−6FpDA) and 6FDA−6FpDA:diaminobenzoic acid (6FDA−6FpDA:DABA), membranes were fabricated from their blends with poly(methylmethacrylate) (PMMA). The resulting polyimides formed homogeneous mixtures with PMMA, regardless of the blend compositions. The miscible blends underwent phase separation upon heating due to the lower critical solution temperature phase behavior. The phase separation temperature of the 6FDA−6FpDA/PMMA blend was greater than that of the 6FDA−6FpDA:DABA/PMMA when the composition was fixed. Adding a small amount of PMMA dramatically increased the gas selectivity of the membrane. In addition, the gas selectivity of most blends was better than that of pure PMMA. The membranes showed performance advantages for the trade-off trend between gas permeability coefficient and selectivity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900643p Exemplaires
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Titre : Predicting the citrate soluble loss of the dihydrate process Type de document : texte imprimé Auteurs : Mohammad Abutayeh, Auteur ; Scott W. Campbell, Auteur Année de publication : 2010 Article en page(s) : pp. 8670–8677 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Phosphate rock Phosphoric acid Dihydrate process Résumé : A thermodynamic model was developed to predict the distribution of phosphates between the liquid and the solid phases in a reactor used for extracting phosphoric acid from phosphate rock by the dihydrate process. Experimental data found in the literature for equilibrium constants were regressed and included in the model to obtain a more accurate representation of the thermodynamic equilibrium. In addition, the Edwards−Maurer−Newman−Prausnitz Pitzer-based model was used to represent the activity coefficients of all species, while published lime solubility data were used to find an expression for the self-interaction parameter of phosphoric acid. The model was validated by comparing its predictions to experimental citrate soluble loss data taken from earlier work and yielded very good results. Simulation results for ionic strength, solution acidity, lime solubility, and citrate soluble loss were used to analyze the effects of temperature and solution sulfate and phosphate content on the dihydrate process. Decreasing temperature and increasing sulfate levels were found to raise the acidity and the ionic strength of the solution as well as minimize the citrate soluble loss. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900183m
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8670–8677[article] Predicting the citrate soluble loss of the dihydrate process [texte imprimé] / Mohammad Abutayeh, Auteur ; Scott W. Campbell, Auteur . - 2010 . - pp. 8670–8677.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8670–8677
Mots-clés : Phosphate rock Phosphoric acid Dihydrate process Résumé : A thermodynamic model was developed to predict the distribution of phosphates between the liquid and the solid phases in a reactor used for extracting phosphoric acid from phosphate rock by the dihydrate process. Experimental data found in the literature for equilibrium constants were regressed and included in the model to obtain a more accurate representation of the thermodynamic equilibrium. In addition, the Edwards−Maurer−Newman−Prausnitz Pitzer-based model was used to represent the activity coefficients of all species, while published lime solubility data were used to find an expression for the self-interaction parameter of phosphoric acid. The model was validated by comparing its predictions to experimental citrate soluble loss data taken from earlier work and yielded very good results. Simulation results for ionic strength, solution acidity, lime solubility, and citrate soluble loss were used to analyze the effects of temperature and solution sulfate and phosphate content on the dihydrate process. Decreasing temperature and increasing sulfate levels were found to raise the acidity and the ionic strength of the solution as well as minimize the citrate soluble loss. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900183m Exemplaires
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Titre : Screening, selecting, and designing microreactors Type de document : texte imprimé Auteurs : Reddy Cherlo, Siva Kumar, Auteur ; Sreenath, K., Auteur ; S. Pushpavanam, Auteur Année de publication : 2010 Article en page(s) : pp. 8678–8684 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Microreactors Computational fluid dynamics approach Flow regimes Résumé : Microreactors can be used to carry out hazardous organic reactions like nitration of benzene and toluene safely. A theoretical analysis of the performance of these systems is usually based on using a computational fluid dynamics approach incorporating the effect of reactions. These simulations help us identify different flow regimes of the system as stratified flow, vortex flow, and engulfment flow. Though it provides realistic estimates of the performance this is a computationally intensive approach. In this work we discuss two strategies for modeling, which exploits the inherent features of single phase flows in microchannels. The first is based on a one-dimensional model where lateral mixing is incorporated using a “pseudo” mass transfer coefficient. In the second we use an effective dispersion coefficient to represent lateral mixing in microchannels. In both approaches we assume the fluid flows as a plug, that is, with a uniform velocity across the cross-section. We consider two different sets of reactions, (i) a set of parallel reactions and (ii) a set of series parallel reactions, and determine how the flow regime in the channel can be exploited to carry out reactions and simultaneously separate the products. The 1D results are compared with those of the 2D model where the transport in the lateral direction is modeled using a dispersion coefficient. The results of the two simplified models are compared with rigorous two-dimensional simulations using Fluent. The approach proposed here can be used to screen and analyze the performance of different reactions in microchannels and examine if the flow features can be used to carry out reactions and separate the products simultaneously. The promising candidates can then be analyzed rigorously for a realistic evaluation of the performance incorporating the prevailing flow structures using computational fluid dynamics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900306j
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8678–8684[article] Screening, selecting, and designing microreactors [texte imprimé] / Reddy Cherlo, Siva Kumar, Auteur ; Sreenath, K., Auteur ; S. Pushpavanam, Auteur . - 2010 . - pp. 8678–8684.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8678–8684
Mots-clés : Microreactors Computational fluid dynamics approach Flow regimes Résumé : Microreactors can be used to carry out hazardous organic reactions like nitration of benzene and toluene safely. A theoretical analysis of the performance of these systems is usually based on using a computational fluid dynamics approach incorporating the effect of reactions. These simulations help us identify different flow regimes of the system as stratified flow, vortex flow, and engulfment flow. Though it provides realistic estimates of the performance this is a computationally intensive approach. In this work we discuss two strategies for modeling, which exploits the inherent features of single phase flows in microchannels. The first is based on a one-dimensional model where lateral mixing is incorporated using a “pseudo” mass transfer coefficient. In the second we use an effective dispersion coefficient to represent lateral mixing in microchannels. In both approaches we assume the fluid flows as a plug, that is, with a uniform velocity across the cross-section. We consider two different sets of reactions, (i) a set of parallel reactions and (ii) a set of series parallel reactions, and determine how the flow regime in the channel can be exploited to carry out reactions and simultaneously separate the products. The 1D results are compared with those of the 2D model where the transport in the lateral direction is modeled using a dispersion coefficient. The results of the two simplified models are compared with rigorous two-dimensional simulations using Fluent. The approach proposed here can be used to screen and analyze the performance of different reactions in microchannels and examine if the flow features can be used to carry out reactions and separate the products simultaneously. The promising candidates can then be analyzed rigorously for a realistic evaluation of the performance incorporating the prevailing flow structures using computational fluid dynamics. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900306j Exemplaires
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Titre : Simultaneous computational fluid dynamics (CFD) simulation of the hydrodynamics and mass transfer in a partially aerated bubble column Type de document : texte imprimé Auteurs : Elena M. Cachaza, Auteur ; M. Elena Díaz, Auteur ; Francisco J. Montes, Auteur Année de publication : 2010 Article en page(s) : pp. 8685–8696 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Simultaneous hydrodynamics Mass-transfer computational fluid dynamics Aerated bubble column Résumé : In this work, simultaneous hydrodynamics and mass-transfer computational fluid dynamics (CFD) studies in a rectangular partially aerated bubble column were conducted. The proposed transient Eulerian−Eulerian model was applied to a two-phase flow composed of polydispersed air and water. Four different kl correlations were implemented in the CFD code, and the results were compared. At superficial gas velocity values ranging from 2.4 mm/s to 21.3 mm/s, the developed flow regimes were experimentally characterized by means of visual observations, global gas holdup, plume oscillation period, and Sauter mean bubble diameter measurements. Simultaneously, the transfer of oxygen from the disperse phase to the initially deoxygenized water was characterized by the measurement of the evolution of the dissolved oxygen concentration with time. Comparison between the experimental and simulated parameters previously mentioned allows for the validation of the computational model. According to the results presented in this work, experimental and simulated hydrodynamic and mass-transfer results show a remarkable agreement at all studied superficial gas velocity values. In addition, mass-transfer results reveal (1) no influence on the developed hydrodynamics, (2) the adequacy of the selected kl correlations obtained by an attentive simplification of mass-transfer equations, and (3) the enhancement of mass-transfer processes when using partially aerated bubble columns. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900314s
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8685–8696[article] Simultaneous computational fluid dynamics (CFD) simulation of the hydrodynamics and mass transfer in a partially aerated bubble column [texte imprimé] / Elena M. Cachaza, Auteur ; M. Elena Díaz, Auteur ; Francisco J. Montes, Auteur . - 2010 . - pp. 8685–8696.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8685–8696
Mots-clés : Simultaneous hydrodynamics Mass-transfer computational fluid dynamics Aerated bubble column Résumé : In this work, simultaneous hydrodynamics and mass-transfer computational fluid dynamics (CFD) studies in a rectangular partially aerated bubble column were conducted. The proposed transient Eulerian−Eulerian model was applied to a two-phase flow composed of polydispersed air and water. Four different kl correlations were implemented in the CFD code, and the results were compared. At superficial gas velocity values ranging from 2.4 mm/s to 21.3 mm/s, the developed flow regimes were experimentally characterized by means of visual observations, global gas holdup, plume oscillation period, and Sauter mean bubble diameter measurements. Simultaneously, the transfer of oxygen from the disperse phase to the initially deoxygenized water was characterized by the measurement of the evolution of the dissolved oxygen concentration with time. Comparison between the experimental and simulated parameters previously mentioned allows for the validation of the computational model. According to the results presented in this work, experimental and simulated hydrodynamic and mass-transfer results show a remarkable agreement at all studied superficial gas velocity values. In addition, mass-transfer results reveal (1) no influence on the developed hydrodynamics, (2) the adequacy of the selected kl correlations obtained by an attentive simplification of mass-transfer equations, and (3) the enhancement of mass-transfer processes when using partially aerated bubble columns. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900314s Exemplaires
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Titre : Valorization of waste agricultural polyethylene film by sequential pyrolysis and catalytic reforming Type de document : texte imprimé Auteurs : Guillermo San Miguel, Auteur ; David P. Serrano, Auteur ; José Aguado, Auteur Année de publication : 2010 Article en page(s) : pp. 8697–8703 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Agriculture film waste Sequential pyrolysis Catalytic reforming Résumé : This paper deals with the potential of using sequential pyrolysis and catalytic reforming for the conversion of agriculture film waste into useful hydrocarbon products. The experiments were conducted in a two-step reaction system consisting of a pyrolytic batch reactor (450 °C) connected in series to a secondary fixed bed reactor where the organic vapors were reformed at temperatures between 425 and 475 °C. Two conventional zeolites (HZSM-5 and Beta) and a mesostructured aluminosilicate Al-MCM-41 were used as catalysts in the reforming stage. Conversion values were not affected by the temperature in the reforming stage and remained fairly constant in all the experiments (89−92 wt %). In the absence of catalyst, the process generated a high proportion of hydrocarbons in the gasoline (C5−C12) and diesel (>C13) range (between 51 and 56 wt % and between 18 and 19 wt %, respectively) and a consequently lower amount of light hydrocarbon products (between 17 and 23 wt %), all of which consisted essentially of a mixture of n-paraffins and olefins. Catalytic reforming over HZSM-5 favored the formation of light hydrocarbons (up to 53 wt %) consisting primarily of C3 and C4 olefins. Catalytic reforming over HZSM-5 also favored the formation of aromatics (up to 12.7 wt %), iso-parafins (8.9 wt %), and naphthenes (4.0 wt %) in the gasoline (C5−C12) fraction. Owing to their weaker acid properties, zeolite Beta and Al-MCM-41 exhibited inferior reforming activities to zeolite HZSM-5, as evidenced by the lower proportion of light hydrocarbons products and the reduced concentration of nonparaffinic products in the heavier fractions. The influence of reforming temperature on product distribution was not significant in the range 425−475 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900776w
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8697–8703[article] Valorization of waste agricultural polyethylene film by sequential pyrolysis and catalytic reforming [texte imprimé] / Guillermo San Miguel, Auteur ; David P. Serrano, Auteur ; José Aguado, Auteur . - 2010 . - pp. 8697–8703.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8697–8703
Mots-clés : Agriculture film waste Sequential pyrolysis Catalytic reforming Résumé : This paper deals with the potential of using sequential pyrolysis and catalytic reforming for the conversion of agriculture film waste into useful hydrocarbon products. The experiments were conducted in a two-step reaction system consisting of a pyrolytic batch reactor (450 °C) connected in series to a secondary fixed bed reactor where the organic vapors were reformed at temperatures between 425 and 475 °C. Two conventional zeolites (HZSM-5 and Beta) and a mesostructured aluminosilicate Al-MCM-41 were used as catalysts in the reforming stage. Conversion values were not affected by the temperature in the reforming stage and remained fairly constant in all the experiments (89−92 wt %). In the absence of catalyst, the process generated a high proportion of hydrocarbons in the gasoline (C5−C12) and diesel (>C13) range (between 51 and 56 wt % and between 18 and 19 wt %, respectively) and a consequently lower amount of light hydrocarbon products (between 17 and 23 wt %), all of which consisted essentially of a mixture of n-paraffins and olefins. Catalytic reforming over HZSM-5 favored the formation of light hydrocarbons (up to 53 wt %) consisting primarily of C3 and C4 olefins. Catalytic reforming over HZSM-5 also favored the formation of aromatics (up to 12.7 wt %), iso-parafins (8.9 wt %), and naphthenes (4.0 wt %) in the gasoline (C5−C12) fraction. Owing to their weaker acid properties, zeolite Beta and Al-MCM-41 exhibited inferior reforming activities to zeolite HZSM-5, as evidenced by the lower proportion of light hydrocarbons products and the reduced concentration of nonparaffinic products in the heavier fractions. The influence of reforming temperature on product distribution was not significant in the range 425−475 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900776w Exemplaires
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Titre : Linear free energy relationship correlations for enthalpies of solvation of organic solutes into room-temperature ionic liquids based on the abraham model with ion-specific equation coefficients Type de document : texte imprimé Auteurs : Laura M. Sprunger, Auteur ; Sai S. Achi, Auteur ; William E. Acree Jr., Auteur Année de publication : 2010 Article en page(s) : pp. 8704–8709 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Mathematical correlations Organic solutesRoom-temperature ionic liquids Abraham general solvation model Résumé : Mathematical correlations have been developed for describing the enthalpy of solvation of organic solutes into room-temperature ionic liquids (RTILs) based on the Abraham general solvation model with ion-specific equation coefficients. The derived correlations contain six cation-specific and six anion-specific equation coefficients that were determined through regression analyses. The derived equations correlated the observed enthalpies of solvation data to within a standard deviation of about 1.7 kJ/mol. The nine sets of cation-specific and eight sets of anion-specific equation coefficients that have been calculated can be combined to yield equations capable of predicting the enthalpies of solvation of organic solutes and gases in 72 different RTILs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900788p
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8704–8709[article] Linear free energy relationship correlations for enthalpies of solvation of organic solutes into room-temperature ionic liquids based on the abraham model with ion-specific equation coefficients [texte imprimé] / Laura M. Sprunger, Auteur ; Sai S. Achi, Auteur ; William E. Acree Jr., Auteur . - 2010 . - pp. 8704–8709.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8704–8709
Mots-clés : Mathematical correlations Organic solutesRoom-temperature ionic liquids Abraham general solvation model Résumé : Mathematical correlations have been developed for describing the enthalpy of solvation of organic solutes into room-temperature ionic liquids (RTILs) based on the Abraham general solvation model with ion-specific equation coefficients. The derived correlations contain six cation-specific and six anion-specific equation coefficients that were determined through regression analyses. The derived equations correlated the observed enthalpies of solvation data to within a standard deviation of about 1.7 kJ/mol. The nine sets of cation-specific and eight sets of anion-specific equation coefficients that have been calculated can be combined to yield equations capable of predicting the enthalpies of solvation of organic solutes and gases in 72 different RTILs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900788p Exemplaires
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Titre : Linear free energy relationship correlations for enthalpies of solvation of organic solutes into room-temperature ionic liquids based on the abraham model with ion-specific equation coefficients Type de document : texte imprimé Auteurs : Laura M. Sprunger, Auteur ; Sai S. Achi, Auteur ; William E. Acree Jr., Auteur Année de publication : 2010 Article en page(s) : pp. 8704–8709 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Mathematical correlations Organic solutesRoom-temperature ionic liquids Abraham general solvation model Résumé : Mathematical correlations have been developed for describing the enthalpy of solvation of organic solutes into room-temperature ionic liquids (RTILs) based on the Abraham general solvation model with ion-specific equation coefficients. The derived correlations contain six cation-specific and six anion-specific equation coefficients that were determined through regression analyses. The derived equations correlated the observed enthalpies of solvation data to within a standard deviation of about 1.7 kJ/mol. The nine sets of cation-specific and eight sets of anion-specific equation coefficients that have been calculated can be combined to yield equations capable of predicting the enthalpies of solvation of organic solutes and gases in 72 different RTILs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900788p
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8704–8709[article] Linear free energy relationship correlations for enthalpies of solvation of organic solutes into room-temperature ionic liquids based on the abraham model with ion-specific equation coefficients [texte imprimé] / Laura M. Sprunger, Auteur ; Sai S. Achi, Auteur ; William E. Acree Jr., Auteur . - 2010 . - pp. 8704–8709.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8704–8709
Mots-clés : Mathematical correlations Organic solutesRoom-temperature ionic liquids Abraham general solvation model Résumé : Mathematical correlations have been developed for describing the enthalpy of solvation of organic solutes into room-temperature ionic liquids (RTILs) based on the Abraham general solvation model with ion-specific equation coefficients. The derived correlations contain six cation-specific and six anion-specific equation coefficients that were determined through regression analyses. The derived equations correlated the observed enthalpies of solvation data to within a standard deviation of about 1.7 kJ/mol. The nine sets of cation-specific and eight sets of anion-specific equation coefficients that have been calculated can be combined to yield equations capable of predicting the enthalpies of solvation of organic solutes and gases in 72 different RTILs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900788p Exemplaires
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Titre : Application of COSMO-RS type models to the prediction of excess enthalpies Type de document : texte imprimé Auteurs : Dana Constantinescu, Auteur ; Jürgen Rarey, Auteur ; Jürgen Gmehling, Auteur Année de publication : 2010 Article en page(s) : pp. 8710–8725 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : COSMO-SAC models COSMO-RS(Ol) Excess enthalpies Binary systems Résumé : This article presents a comparative study about the predictive capability of COSMO-SAC and COSMO-RS(Ol) models with respect to excess enthalpies of various binary systems. Results of the group contribution methods UNIFAC and modified UNIFAC (Do) are given for comparison. COSMO calculations were performed using σ profiles based on density functional theory (BP and B3LYP). These were generated by the quantum chemical programs Turbomole and Gaussian 03, with the basis sets used for the calculation being triple-ζ valence polarization (TZVP) for BP and 6-311G(d,p) in the case of B3LYP. All results are compared with experimental data stored in the Dortmund Data Bank for 10 851 binary data sets (5368 different binary mixtures) with over 165 000 experimental data points from nearly 2000 references and are analyzed according to the types of components in the mixture. As expected, the intensively trained mod. UNIFAC (Do) model performs best in predicting the excess enthalpy of binary systems in most cases, but also COSMO-RS type models often lead to astonishingly good results considering the very small number of parameters used. Overall, relative deviations for a common data set of 30.7% (mod. UNIFAC (Do)) and between 56.7% and 80.8% for the different COSMO-RS flavors were obtained. Whenever experimental data indicated a significant change of the excess enthalpy with temperature, the different COSMO-RS type models failed to reproduce this behavior. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900315p
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8710–8725[article] Application of COSMO-RS type models to the prediction of excess enthalpies [texte imprimé] / Dana Constantinescu, Auteur ; Jürgen Rarey, Auteur ; Jürgen Gmehling, Auteur . - 2010 . - pp. 8710–8725.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8710–8725
Mots-clés : COSMO-SAC models COSMO-RS(Ol) Excess enthalpies Binary systems Résumé : This article presents a comparative study about the predictive capability of COSMO-SAC and COSMO-RS(Ol) models with respect to excess enthalpies of various binary systems. Results of the group contribution methods UNIFAC and modified UNIFAC (Do) are given for comparison. COSMO calculations were performed using σ profiles based on density functional theory (BP and B3LYP). These were generated by the quantum chemical programs Turbomole and Gaussian 03, with the basis sets used for the calculation being triple-ζ valence polarization (TZVP) for BP and 6-311G(d,p) in the case of B3LYP. All results are compared with experimental data stored in the Dortmund Data Bank for 10 851 binary data sets (5368 different binary mixtures) with over 165 000 experimental data points from nearly 2000 references and are analyzed according to the types of components in the mixture. As expected, the intensively trained mod. UNIFAC (Do) model performs best in predicting the excess enthalpy of binary systems in most cases, but also COSMO-RS type models often lead to astonishingly good results considering the very small number of parameters used. Overall, relative deviations for a common data set of 30.7% (mod. UNIFAC (Do)) and between 56.7% and 80.8% for the different COSMO-RS flavors were obtained. Whenever experimental data indicated a significant change of the excess enthalpy with temperature, the different COSMO-RS type models failed to reproduce this behavior. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900315p Exemplaires
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Titre : Bubble evolution through a submerged orifice using smoothed particle hydrodynamics : effect of different thermophysical properties Type de document : texte imprimé Auteurs : Arup K. Das, Auteur ; Prasanta K. Das, Auteur Année de publication : 2010 Article en page(s) : pp. 8726–8735 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas bubbles Submerged orifice Liquid pool Industrial applications Résumé : Formation of gas bubbles through an orifice under a liquid pool is important as a topic of fundamental research and is relevant in diverse industrial applications. This complex process is influenced by a large number of process parameters including the properties of the liquid and the gas phase. In the present work investigations have been made for bubble evolution at a submerged orifice using a computational simulation. Smoothed particle hydrodynamics is used to model the formation and detachment of the bubble from the orifice mouth. Using the advantage of this particle-based method, effects of density, viscosity, and surface tension of the liquid are investigated by noticing instantaneous bubble contour and the duration of bubble growth. The present simulation has been validated satisfactorily against published results. Finally, the process of neck formation and bubble pinch off has also been studied by varying the specific fluid properties individually. It has been noticed that the effect of surface tension and the effect of viscosity on bubble growth and necking are just the reverse of the effect of density on these processes. Moreover, compared to surface tension and density, the effect of viscosity on bubble evolution is marginal. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900350h#cor1
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8726–8735[article] Bubble evolution through a submerged orifice using smoothed particle hydrodynamics : effect of different thermophysical properties [texte imprimé] / Arup K. Das, Auteur ; Prasanta K. Das, Auteur . - 2010 . - pp. 8726–8735.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8726–8735
Mots-clés : Gas bubbles Submerged orifice Liquid pool Industrial applications Résumé : Formation of gas bubbles through an orifice under a liquid pool is important as a topic of fundamental research and is relevant in diverse industrial applications. This complex process is influenced by a large number of process parameters including the properties of the liquid and the gas phase. In the present work investigations have been made for bubble evolution at a submerged orifice using a computational simulation. Smoothed particle hydrodynamics is used to model the formation and detachment of the bubble from the orifice mouth. Using the advantage of this particle-based method, effects of density, viscosity, and surface tension of the liquid are investigated by noticing instantaneous bubble contour and the duration of bubble growth. The present simulation has been validated satisfactorily against published results. Finally, the process of neck formation and bubble pinch off has also been studied by varying the specific fluid properties individually. It has been noticed that the effect of surface tension and the effect of viscosity on bubble growth and necking are just the reverse of the effect of density on these processes. Moreover, compared to surface tension and density, the effect of viscosity on bubble evolution is marginal. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900350h#cor1 Exemplaires
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Titre : Online measurement of fiber diameter and temperature in the melt-spinning and melt-blowing processes Type de document : texte imprimé Auteurs : Vishnu T. Marla, Auteur ; Robert L. Shambaugh, Auteur ; Dimitrios V. Papavassiliou, Auteur Année de publication : 2010 Article en page(s) : pp. 8736–8744 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fiber temperature diameter Melt-spinning processe Melt-blowing Résumé : Online measurements of fiber temperature and diameter were made for both the melt-spinning and the melt-blowing processes. The fiber temperature was determined by infrared thermography, and the fiber diameter was determined by high-speed photography. These measurements were then compared with predictions made with mathematical models for melt spinning and melt blowing. There was good agreement between the models and the experimental results, and the agreement was best when heat-transfer correlations developed specifically for fine fibers (cylinders) were used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900615n
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8736–8744[article] Online measurement of fiber diameter and temperature in the melt-spinning and melt-blowing processes [texte imprimé] / Vishnu T. Marla, Auteur ; Robert L. Shambaugh, Auteur ; Dimitrios V. Papavassiliou, Auteur . - 2010 . - pp. 8736–8744.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8736–8744
Mots-clés : Fiber temperature diameter Melt-spinning processe Melt-blowing Résumé : Online measurements of fiber temperature and diameter were made for both the melt-spinning and the melt-blowing processes. The fiber temperature was determined by infrared thermography, and the fiber diameter was determined by high-speed photography. These measurements were then compared with predictions made with mathematical models for melt spinning and melt blowing. There was good agreement between the models and the experimental results, and the agreement was best when heat-transfer correlations developed specifically for fine fibers (cylinders) were used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900615n Exemplaires
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Titre : Online measurement of fiber diameter and temperature in the melt-spinning and melt-blowing processes Type de document : texte imprimé Auteurs : Vishnu T. Marla, Auteur ; Robert L. Shambaugh, Auteur ; Dimitrios V. Papavassiliou, Auteur Année de publication : 2010 Article en page(s) : pp. 8736–8744 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fiber temperature diameter Melt-spinning processe Melt-blowing Résumé : Online measurements of fiber temperature and diameter were made for both the melt-spinning and the melt-blowing processes. The fiber temperature was determined by infrared thermography, and the fiber diameter was determined by high-speed photography. These measurements were then compared with predictions made with mathematical models for melt spinning and melt blowing. There was good agreement between the models and the experimental results, and the agreement was best when heat-transfer correlations developed specifically for fine fibers (cylinders) were used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900615n
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8736–8744[article] Online measurement of fiber diameter and temperature in the melt-spinning and melt-blowing processes [texte imprimé] / Vishnu T. Marla, Auteur ; Robert L. Shambaugh, Auteur ; Dimitrios V. Papavassiliou, Auteur . - 2010 . - pp. 8736–8744.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8736–8744
Mots-clés : Fiber temperature diameter Melt-spinning processe Melt-blowing Résumé : Online measurements of fiber temperature and diameter were made for both the melt-spinning and the melt-blowing processes. The fiber temperature was determined by infrared thermography, and the fiber diameter was determined by high-speed photography. These measurements were then compared with predictions made with mathematical models for melt spinning and melt blowing. There was good agreement between the models and the experimental results, and the agreement was best when heat-transfer correlations developed specifically for fine fibers (cylinders) were used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900615n Exemplaires
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Titre : Online measurement of fiber diameter and temperature in the melt-spinning and melt-blowing processes Type de document : texte imprimé Auteurs : Vishnu T. Marla, Auteur ; Robert L. Shambaugh, Auteur ; Dimitrios V. Papavassiliou, Auteur Année de publication : 2010 Article en page(s) : pp. 8736–8744 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fiber temperature diameter Melt-spinning processe Melt-blowing Résumé : Online measurements of fiber temperature and diameter were made for both the melt-spinning and the melt-blowing processes. The fiber temperature was determined by infrared thermography, and the fiber diameter was determined by high-speed photography. These measurements were then compared with predictions made with mathematical models for melt spinning and melt blowing. There was good agreement between the models and the experimental results, and the agreement was best when heat-transfer correlations developed specifically for fine fibers (cylinders) were used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900615n
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8736–8744[article] Online measurement of fiber diameter and temperature in the melt-spinning and melt-blowing processes [texte imprimé] / Vishnu T. Marla, Auteur ; Robert L. Shambaugh, Auteur ; Dimitrios V. Papavassiliou, Auteur . - 2010 . - pp. 8736–8744.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8736–8744
Mots-clés : Fiber temperature diameter Melt-spinning processe Melt-blowing Résumé : Online measurements of fiber temperature and diameter were made for both the melt-spinning and the melt-blowing processes. The fiber temperature was determined by infrared thermography, and the fiber diameter was determined by high-speed photography. These measurements were then compared with predictions made with mathematical models for melt spinning and melt blowing. There was good agreement between the models and the experimental results, and the agreement was best when heat-transfer correlations developed specifically for fine fibers (cylinders) were used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900615n Exemplaires
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Titre : Study on the reaction mechanism and kinetics of the thermal decomposition of nitroethane Type de document : texte imprimé Auteurs : Qingsheng Wang, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur Année de publication : 2010 Article en page(s) : pp. 8745–8751 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nitroethane Thermal decomposition Density functional theory calculations Automatic pressure tracking adiabatic calorimeter measurements Gas chromatography analysis Résumé : Despite many theoretical and experimental advances in understanding the macroscopic properties of energetic materials, much work remains to be done to understand their microscale mechanism. In this work, the reaction mechanism and kinetics of thermal decomposition of nitroethane were studied by density functional theory (DFT) calculations, automatic pressure tracking adiabatic calorimeter (APTAC) measurements, and gas chromatography (GC) analysis. The APTAC results were used to determine Arrhenius parameters of A = 1013.5±0.2 and Ea = 46.2 ± 0.5 kcal/mol. The decomposition process includes three initial steps: concerted molecular elimination of HONO, nitro−nitrite isomerization, and rupture of C−NO2. Followed these initial reactions, a detailed mechanism that consists of 23 elementary steps was proposed. Numerical simulations of the proposed mechanism reproduce reasonably well the distributions of major products over the temperature range. It was found that the relative concentrations of NO and C2H4 depend on the reaction temperatures. Combining theoretical and experimental studies, it is concluded that elimination of HONO is predominant at low temperature and dissociation of C−NO2 becomes significant at high temperature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900849n
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8745–8751[article] Study on the reaction mechanism and kinetics of the thermal decomposition of nitroethane [texte imprimé] / Qingsheng Wang, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur . - 2010 . - pp. 8745–8751.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8745–8751
Mots-clés : Nitroethane Thermal decomposition Density functional theory calculations Automatic pressure tracking adiabatic calorimeter measurements Gas chromatography analysis Résumé : Despite many theoretical and experimental advances in understanding the macroscopic properties of energetic materials, much work remains to be done to understand their microscale mechanism. In this work, the reaction mechanism and kinetics of thermal decomposition of nitroethane were studied by density functional theory (DFT) calculations, automatic pressure tracking adiabatic calorimeter (APTAC) measurements, and gas chromatography (GC) analysis. The APTAC results were used to determine Arrhenius parameters of A = 1013.5±0.2 and Ea = 46.2 ± 0.5 kcal/mol. The decomposition process includes three initial steps: concerted molecular elimination of HONO, nitro−nitrite isomerization, and rupture of C−NO2. Followed these initial reactions, a detailed mechanism that consists of 23 elementary steps was proposed. Numerical simulations of the proposed mechanism reproduce reasonably well the distributions of major products over the temperature range. It was found that the relative concentrations of NO and C2H4 depend on the reaction temperatures. Combining theoretical and experimental studies, it is concluded that elimination of HONO is predominant at low temperature and dissociation of C−NO2 becomes significant at high temperature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900849n Exemplaires
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Titre : Study on the reaction mechanism and kinetics of the thermal decomposition of nitroethane Type de document : texte imprimé Auteurs : Qingsheng Wang, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur Année de publication : 2010 Article en page(s) : pp. 8745–8751 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nitroethane Thermal decomposition Density functional theory calculations Automatic pressure tracking adiabatic calorimeter measurements Gas chromatography analysis Résumé : Despite many theoretical and experimental advances in understanding the macroscopic properties of energetic materials, much work remains to be done to understand their microscale mechanism. In this work, the reaction mechanism and kinetics of thermal decomposition of nitroethane were studied by density functional theory (DFT) calculations, automatic pressure tracking adiabatic calorimeter (APTAC) measurements, and gas chromatography (GC) analysis. The APTAC results were used to determine Arrhenius parameters of A = 1013.5±0.2 and Ea = 46.2 ± 0.5 kcal/mol. The decomposition process includes three initial steps: concerted molecular elimination of HONO, nitro−nitrite isomerization, and rupture of C−NO2. Followed these initial reactions, a detailed mechanism that consists of 23 elementary steps was proposed. Numerical simulations of the proposed mechanism reproduce reasonably well the distributions of major products over the temperature range. It was found that the relative concentrations of NO and C2H4 depend on the reaction temperatures. Combining theoretical and experimental studies, it is concluded that elimination of HONO is predominant at low temperature and dissociation of C−NO2 becomes significant at high temperature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900849n
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8745–8751[article] Study on the reaction mechanism and kinetics of the thermal decomposition of nitroethane [texte imprimé] / Qingsheng Wang, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur . - 2010 . - pp. 8745–8751.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8745–8751
Mots-clés : Nitroethane Thermal decomposition Density functional theory calculations Automatic pressure tracking adiabatic calorimeter measurements Gas chromatography analysis Résumé : Despite many theoretical and experimental advances in understanding the macroscopic properties of energetic materials, much work remains to be done to understand their microscale mechanism. In this work, the reaction mechanism and kinetics of thermal decomposition of nitroethane were studied by density functional theory (DFT) calculations, automatic pressure tracking adiabatic calorimeter (APTAC) measurements, and gas chromatography (GC) analysis. The APTAC results were used to determine Arrhenius parameters of A = 1013.5±0.2 and Ea = 46.2 ± 0.5 kcal/mol. The decomposition process includes three initial steps: concerted molecular elimination of HONO, nitro−nitrite isomerization, and rupture of C−NO2. Followed these initial reactions, a detailed mechanism that consists of 23 elementary steps was proposed. Numerical simulations of the proposed mechanism reproduce reasonably well the distributions of major products over the temperature range. It was found that the relative concentrations of NO and C2H4 depend on the reaction temperatures. Combining theoretical and experimental studies, it is concluded that elimination of HONO is predominant at low temperature and dissociation of C−NO2 becomes significant at high temperature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900849n Exemplaires
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Titre : Experimental study on surface aerators stirred by triple impellers Type de document : texte imprimé Auteurs : Xiangyang Li, Auteur ; Gengzhi Yu, Auteur ; Chao Yang, Auteur Année de publication : 2010 Article en page(s) : pp. 8752–8756 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Stirred vessel Gas-liquid mass transfer Triple-impeller Surface aeration Résumé : In a stirred vessel with the aspect ratio of 2.4, the gas−liquid mass transfer characteristics of triple-impeller configurations with surface aeration have been studied. The way by adding one or more impellers below the aerating impeller could not overcome the problem of poor gas dispersion in the region close to the bottom of the gas−liquid vessel stirred only by a surface aerator. With the combination of surface aeration and sparger aeration, gas dispersion is greatly improved. Triple-impeller configurations and volumetric gas flow rates are optimized based on the volumetric mass transfer coefficient per power consumption. It is found that the sparging gas has only a little effect on the surface aeration, because the vessel is stirred by the triple-impeller configuration and with a larger aspect ratio. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900623m
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8752–8756[article] Experimental study on surface aerators stirred by triple impellers [texte imprimé] / Xiangyang Li, Auteur ; Gengzhi Yu, Auteur ; Chao Yang, Auteur . - 2010 . - pp. 8752–8756.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8752–8756
Mots-clés : Stirred vessel Gas-liquid mass transfer Triple-impeller Surface aeration Résumé : In a stirred vessel with the aspect ratio of 2.4, the gas−liquid mass transfer characteristics of triple-impeller configurations with surface aeration have been studied. The way by adding one or more impellers below the aerating impeller could not overcome the problem of poor gas dispersion in the region close to the bottom of the gas−liquid vessel stirred only by a surface aerator. With the combination of surface aeration and sparger aeration, gas dispersion is greatly improved. Triple-impeller configurations and volumetric gas flow rates are optimized based on the volumetric mass transfer coefficient per power consumption. It is found that the sparging gas has only a little effect on the surface aeration, because the vessel is stirred by the triple-impeller configuration and with a larger aspect ratio. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900623m Exemplaires
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Titre : Diol-functionalized imidazolium-based room-temperature ionic liquids with bis(trifluoromethanesulfonimide) anions that exhibit variable water miscibility Type de document : texte imprimé Auteurs : Andrew L. LaFrate, Auteur ; Jason E. Bara, Auteur ; Douglas L. Gin, Auteur Année de publication : 2010 Article en page(s) : pp. 8757–8759 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : 1-(2,3-dihydroxypropyl)-3-alkylimidazolium Bis(trifluoromethanesulfonimide) Room-temperature ionic liquids Water miscibility Résumé : The synthesis and characterization of a new class of 1-(2,3-dihydroxypropyl)-3-alkylimidazolium bis(trifluoromethanesulfonimide) room-temperature ionic liquids (RTILs) with tunable water miscibility are reported. The presence of a vicinal diol substituent on these RTILs allows for variable water miscibility, depending on the nature of the alkyl substituent on the cation. Water-miscible, imidazolium-based RTILs with the bis(trifluoromethanesulfonimide) anion are unprecedented. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900460r
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8757–8759[article] Diol-functionalized imidazolium-based room-temperature ionic liquids with bis(trifluoromethanesulfonimide) anions that exhibit variable water miscibility [texte imprimé] / Andrew L. LaFrate, Auteur ; Jason E. Bara, Auteur ; Douglas L. Gin, Auteur . - 2010 . - pp. 8757–8759.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8757–8759
Mots-clés : 1-(2,3-dihydroxypropyl)-3-alkylimidazolium Bis(trifluoromethanesulfonimide) Room-temperature ionic liquids Water miscibility Résumé : The synthesis and characterization of a new class of 1-(2,3-dihydroxypropyl)-3-alkylimidazolium bis(trifluoromethanesulfonimide) room-temperature ionic liquids (RTILs) with tunable water miscibility are reported. The presence of a vicinal diol substituent on these RTILs allows for variable water miscibility, depending on the nature of the alkyl substituent on the cation. Water-miscible, imidazolium-based RTILs with the bis(trifluoromethanesulfonimide) anion are unprecedented. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900460r Exemplaires
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Titre : Hybrid method to predict melting points of organic compounds using group contribution + neural network + particle swarm algorithm Type de document : texte imprimé Auteurs : Juan A. Lazzús, Auteur Année de publication : 2010 Article en page(s) : pp. 8760–8766 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Organic compounds Group contribution method Artificial neural network Résumé : The melting points of organic compounds were estimated using a hybrid method that includes a simple group contribution method (GCM) implemented in an artificial neural network (ANN) replacing standart backpropagation with particle swarm optimization (PSO). A total of 439 compounds have been used to train the network developed using MatLab. Then, the melting points of 100 other compounds have been predicted and results compared to experimental data and other models availables in the literature. The study shows that the proposed GCM + ANN + PSO model represents an excellent alternative for the estimation of melting points of organic compounds (average absolute relative deviation (AARD) = 7%) from the knowledge of the molecular structure. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900431f
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8760–8766[article] Hybrid method to predict melting points of organic compounds using group contribution + neural network + particle swarm algorithm [texte imprimé] / Juan A. Lazzús, Auteur . - 2010 . - pp. 8760–8766.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8760–8766
Mots-clés : Organic compounds Group contribution method Artificial neural network Résumé : The melting points of organic compounds were estimated using a hybrid method that includes a simple group contribution method (GCM) implemented in an artificial neural network (ANN) replacing standart backpropagation with particle swarm optimization (PSO). A total of 439 compounds have been used to train the network developed using MatLab. Then, the melting points of 100 other compounds have been predicted and results compared to experimental data and other models availables in the literature. The study shows that the proposed GCM + ANN + PSO model represents an excellent alternative for the estimation of melting points of organic compounds (average absolute relative deviation (AARD) = 7%) from the knowledge of the molecular structure. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900431f Exemplaires
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