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Vol. 47 n°12 - Juin 2008 [texte imprimé] . - 2008 . - p. 4029-4294 : ill. ; 28 cm. Chemical engineering Langues : Anglais (eng)
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Ajouter le résultat dans votre panierWaste tire pyrolysis / E. Aylón in Industrial & engineering chemistry research, Vol. 47 n°12 (Juin 2008)
Titre : Waste tire pyrolysis : comparison between fixed bed reactor and moving bed reactor Type de document : texte imprimé Auteurs : E. Aylón, Auteur ; A. Fernández-Colino, Auteur ; M. V. Navarro, Auteur Année de publication : 2008 Article en page(s) : p. 4029–4033 Note générale : Bibliogr. p. 4032-4033 Langues : Anglais (eng) Mots-clés : Waste tire pyrolysis Moving bed reactor Conversion Résumé : Waste tire pyrolysis has been performed in a fixed bed and a moving bed reactor, in order to know the influence of the reactor type on the yields and product characteristics. Typical pyrolysis conditions have been used in both reactors (600 °C and inert atmosphere). The moving bed reactor operates in continuous mode, and it is designed to process up to 15 kg/h of waste tire. An excellent process reproducibility and stability was observed. Moreover, when results obtained in the fixed bed and moving bed reactors are compared, it can be appreciated that total rubber conversion is achieved in both systems although solid residence time in the fixed bed is clearly longer than that in the moving bed reactor. In addition, a more severe cracking of the primary pyrolysis products occurs in the moving bed reactor due to the faster heating rate and the longer gas residence time. Regarding the pyrolysis products, the solid fraction is mostly constituted of carbon black, the liquid phase is a complex hydrocarbon mixture and the gas phase is a mixture of light hydrocarbons, carbon dioxide, carbon monoxide, hydrogen sulfide, and hydrogen. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071573o
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4029–4033[article] Waste tire pyrolysis : comparison between fixed bed reactor and moving bed reactor [texte imprimé] / E. Aylón, Auteur ; A. Fernández-Colino, Auteur ; M. V. Navarro, Auteur . - 2008 . - p. 4029–4033.
Bibliogr. p. 4032-4033
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4029–4033
Mots-clés : Waste tire pyrolysis Moving bed reactor Conversion Résumé : Waste tire pyrolysis has been performed in a fixed bed and a moving bed reactor, in order to know the influence of the reactor type on the yields and product characteristics. Typical pyrolysis conditions have been used in both reactors (600 °C and inert atmosphere). The moving bed reactor operates in continuous mode, and it is designed to process up to 15 kg/h of waste tire. An excellent process reproducibility and stability was observed. Moreover, when results obtained in the fixed bed and moving bed reactors are compared, it can be appreciated that total rubber conversion is achieved in both systems although solid residence time in the fixed bed is clearly longer than that in the moving bed reactor. In addition, a more severe cracking of the primary pyrolysis products occurs in the moving bed reactor due to the faster heating rate and the longer gas residence time. Regarding the pyrolysis products, the solid fraction is mostly constituted of carbon black, the liquid phase is a complex hydrocarbon mixture and the gas phase is a mixture of light hydrocarbons, carbon dioxide, carbon monoxide, hydrogen sulfide, and hydrogen. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071573o Exemplaires
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Titre : Rhodium supported Hβ zeolite for the hydrogenation of toluene Type de document : texte imprimé Auteurs : Kalpesh B. Sidhpuria, Auteur ; Parimal A. Parikh, Auteur ; Pratap Bahadur, Auteur ; Raksh V. Jasra, Auteur Année de publication : 2008 Article en page(s) : p. 4034–4042 Note générale : Bibliogr. p. 4041-4042 Langues : Anglais (eng) Mots-clés : Noble metal Rh Toluene -- hydrodearomatization Fourier transform infrared spectra Chemical analysis Résumé : Noble metal Rh supported on a large pore high acidic zeolite Hβ has been explored as a hydrodearomatization catalyst. The detail kinetic study of hydrodearomatization of toluene over a 1 wt % Rh/Hβ was done in a continuous-downflow stainless steel catalytic fixed bed reactor at varied space time, toluene feed rate, hydrogen partial pressure, hydrogen to toluene mole ratio, temperature, and in the presence of dibenzothiophene. The time on stream data and reaction order with respect to toluene were measured and was found to be of first order. Fourier transform infrared (FTIR) spectra and chemical analysis of fresh and spent catalyst suggested the presence of surface carbon species and weight percent carbon was found to be 4.43%. It was observed that toluene conversion was increased on increasing H2 partial pressure and H2/feed mole ratio. The conversion is dependent on temperature and shows a well-defined maximum. The decrease of the catalyst activity in the presence of dibenzothiophene is mainly attributed to the adsorption and decomposition of dibenzothiophene (DBT) on the metal sites, which results in a loss of metal surface available for the reaction to take place and a higher coke formation reducing the fraction of acid sites available for toluene hydrodearomatization. A nonlinear semiempirical kinetic model was also developed to have the best fit with 12% error. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8001793
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4034–4042[article] Rhodium supported Hβ zeolite for the hydrogenation of toluene [texte imprimé] / Kalpesh B. Sidhpuria, Auteur ; Parimal A. Parikh, Auteur ; Pratap Bahadur, Auteur ; Raksh V. Jasra, Auteur . - 2008 . - p. 4034–4042.
Bibliogr. p. 4041-4042
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4034–4042
Mots-clés : Noble metal Rh Toluene -- hydrodearomatization Fourier transform infrared spectra Chemical analysis Résumé : Noble metal Rh supported on a large pore high acidic zeolite Hβ has been explored as a hydrodearomatization catalyst. The detail kinetic study of hydrodearomatization of toluene over a 1 wt % Rh/Hβ was done in a continuous-downflow stainless steel catalytic fixed bed reactor at varied space time, toluene feed rate, hydrogen partial pressure, hydrogen to toluene mole ratio, temperature, and in the presence of dibenzothiophene. The time on stream data and reaction order with respect to toluene were measured and was found to be of first order. Fourier transform infrared (FTIR) spectra and chemical analysis of fresh and spent catalyst suggested the presence of surface carbon species and weight percent carbon was found to be 4.43%. It was observed that toluene conversion was increased on increasing H2 partial pressure and H2/feed mole ratio. The conversion is dependent on temperature and shows a well-defined maximum. The decrease of the catalyst activity in the presence of dibenzothiophene is mainly attributed to the adsorption and decomposition of dibenzothiophene (DBT) on the metal sites, which results in a loss of metal surface available for the reaction to take place and a higher coke formation reducing the fraction of acid sites available for toluene hydrodearomatization. A nonlinear semiempirical kinetic model was also developed to have the best fit with 12% error. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8001793 Exemplaires
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Titre : Steam catalysis in CaO carbonation under low steam partial pressure Type de document : texte imprimé Auteurs : Shaojun Yang, Auteur ; Yunhan Xiao, Auteur Année de publication : 2008 Article en page(s) : p. 4043–4048 Note générale : Bibliogr. p. 4047-4048 Langues : Anglais (eng) Mots-clés : CaO carbonation Steam partial pressure Thermogravimetric apparatus Résumé : CaO was widely used to capture CO2 in direct hydrogen production process, where steam always existed simultaneously. The effect of steam on CaO carbonation performance under low steam partial pressure was investigated using a pressurized thermogravimetric apparatus. The experimental results revealed that steam improved CaO carbonation performance significantly no matter whether Ca(OH)2 was produced or not. At 823 K and 0.5 MPa of steam partial pressure, effect of steam on CaO carbonation performance could not be attributed mainly to production of Ca(OH)2 because the hydration rate of CaO was very slow. The main reason was steam catalysis in CaO carbonation. Enhancement of steam on CaO carbonation performance without Ca(OH)2 production could not be attributed to improvement of steam on the physical property, but to catalytic effect of steam. Effects of CaO precursors, CO2 partial pressure, steam partial pressure, and temperature with steam addition on CaO carbonation performance were also investigated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8000265
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4043–4048[article] Steam catalysis in CaO carbonation under low steam partial pressure [texte imprimé] / Shaojun Yang, Auteur ; Yunhan Xiao, Auteur . - 2008 . - p. 4043–4048.
Bibliogr. p. 4047-4048
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4043–4048
Mots-clés : CaO carbonation Steam partial pressure Thermogravimetric apparatus Résumé : CaO was widely used to capture CO2 in direct hydrogen production process, where steam always existed simultaneously. The effect of steam on CaO carbonation performance under low steam partial pressure was investigated using a pressurized thermogravimetric apparatus. The experimental results revealed that steam improved CaO carbonation performance significantly no matter whether Ca(OH)2 was produced or not. At 823 K and 0.5 MPa of steam partial pressure, effect of steam on CaO carbonation performance could not be attributed mainly to production of Ca(OH)2 because the hydration rate of CaO was very slow. The main reason was steam catalysis in CaO carbonation. Enhancement of steam on CaO carbonation performance without Ca(OH)2 production could not be attributed to improvement of steam on the physical property, but to catalytic effect of steam. Effects of CaO precursors, CO2 partial pressure, steam partial pressure, and temperature with steam addition on CaO carbonation performance were also investigated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8000265 Exemplaires
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Titre : Catalytic wet oxidation of lactose Type de document : texte imprimé Auteurs : Yah Nan Chia, Auteur ; Michael P. Latusek, Auteur ; Joseph H. Holles, Auteur Année de publication : 2008 Article en page(s) : p. 4049–4055 Note générale : Bibliogr. p. 4054-4055 Langues : Anglais (eng) Mots-clés : Lactose -- catalytic wet oxidation BiPd/C catalyst Résumé : The catalytic wet oxidation of lactose to carbon dioxide/water and to a value-added product, lactobionic acid, has been demonstrated in a flow reactor. Lactose (milk sugar) is a low value byproduct of the dairy industry and makes up the largest part of the solids in cheese whey. Costs associated with cheese whey disposal are driving the need to develop alternative disposal methods. Pt/Al2O3, CeMn mixed-metal oxides, and Pt/CeMn catalysts have all been shown to effectively convert lactose to carbon dioxide and water at temperatures up to 443 K and pressures of 100 psig. Pt/CeMn demonstrated the lowest level of side-product formation. A BiPd/C catalyst was shown to convert essentially all lactose to lactobionic acid at similar temperature and pressure. Lactobionic acid selectivity was a strong function of oxygen concentration in the feed. The BiPd/C also produced a high yield of lactobionic acid at lower pH and higher temperatures than previously reported. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701779u
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4049–4055[article] Catalytic wet oxidation of lactose [texte imprimé] / Yah Nan Chia, Auteur ; Michael P. Latusek, Auteur ; Joseph H. Holles, Auteur . - 2008 . - p. 4049–4055.
Bibliogr. p. 4054-4055
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4049–4055
Mots-clés : Lactose -- catalytic wet oxidation BiPd/C catalyst Résumé : The catalytic wet oxidation of lactose to carbon dioxide/water and to a value-added product, lactobionic acid, has been demonstrated in a flow reactor. Lactose (milk sugar) is a low value byproduct of the dairy industry and makes up the largest part of the solids in cheese whey. Costs associated with cheese whey disposal are driving the need to develop alternative disposal methods. Pt/Al2O3, CeMn mixed-metal oxides, and Pt/CeMn catalysts have all been shown to effectively convert lactose to carbon dioxide and water at temperatures up to 443 K and pressures of 100 psig. Pt/CeMn demonstrated the lowest level of side-product formation. A BiPd/C catalyst was shown to convert essentially all lactose to lactobionic acid at similar temperature and pressure. Lactobionic acid selectivity was a strong function of oxygen concentration in the feed. The BiPd/C also produced a high yield of lactobionic acid at lower pH and higher temperatures than previously reported. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701779u Exemplaires
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Titre : Deactivation and coke formation on nickeltungsten supported on silica-alumina catalysts Type de document : texte imprimé Auteurs : Yacine Rezgui, Auteur ; Miloud Guemini, Auteur Année de publication : 2008 Article en page(s) : p. 4056–4062 Note générale : Bibliogr. p. 4061-4062 Langues : Anglais (eng) Mots-clés : Nickel− tungsten supported Silica-alumina catalysts Coke Temperatureprogrammed oxidation Résumé : Nickel−tungsten oxides supported on silica−alumina catalysts were submitted to the coking reaction with n-octane at 150, 250, and 300 °C. The characteristics of deposited coke with different times on stream were studied using the temperature-programmed oxidation (TPO) technique. The results revealed that the strength and density of acid sites as well as the reaction temperature affect the nature of the coke formed: at 300 °C, it was observed that for the WT7 catalyst, the most acidic solid, there were two peaks corresponding to two kinds of coke recorded in TPO profiles, while at 150 °C only one peak was observed. On the other hand, for the WT4 catalyst, the less acidic sample, only the soft coke was observed. In addition, the oxidation temperature of coke shifted to higher values with high medium acid sites concentration and high temperature values with the increase of coke deposits. Besides, coke molecules interacted preferentially with the most acidic sites, which was confirmed by the strong deactivation in the first reaction stages, especially for the WT7 catalyst. For the regeneration tests, the collected data suggested that the coked WT4 catalyst showed a good combustion behavior; it was regenerated at 500 °C for 1 h, whereas the coked WT7 could not be regenerated at this temperature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071407g
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4056–4062[article] Deactivation and coke formation on nickeltungsten supported on silica-alumina catalysts [texte imprimé] / Yacine Rezgui, Auteur ; Miloud Guemini, Auteur . - 2008 . - p. 4056–4062.
Bibliogr. p. 4061-4062
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4056–4062
Mots-clés : Nickel− tungsten supported Silica-alumina catalysts Coke Temperatureprogrammed oxidation Résumé : Nickel−tungsten oxides supported on silica−alumina catalysts were submitted to the coking reaction with n-octane at 150, 250, and 300 °C. The characteristics of deposited coke with different times on stream were studied using the temperature-programmed oxidation (TPO) technique. The results revealed that the strength and density of acid sites as well as the reaction temperature affect the nature of the coke formed: at 300 °C, it was observed that for the WT7 catalyst, the most acidic solid, there were two peaks corresponding to two kinds of coke recorded in TPO profiles, while at 150 °C only one peak was observed. On the other hand, for the WT4 catalyst, the less acidic sample, only the soft coke was observed. In addition, the oxidation temperature of coke shifted to higher values with high medium acid sites concentration and high temperature values with the increase of coke deposits. Besides, coke molecules interacted preferentially with the most acidic sites, which was confirmed by the strong deactivation in the first reaction stages, especially for the WT7 catalyst. For the regeneration tests, the collected data suggested that the coked WT4 catalyst showed a good combustion behavior; it was regenerated at 500 °C for 1 h, whereas the coked WT7 could not be regenerated at this temperature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071407g Exemplaires
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Titre : Ammonia decomposition on tungsten-based catalysts in the absence and presence of syngas Type de document : texte imprimé Auteurs : Sourabh S. Pansare, Auteur ; James G. GoodwinJr., Auteur Année de publication : 2008 Article en page(s) : p. 4063–4070 Note générale : Bibliogr. p. 4069-4070 Langues : Anglais (eng) Mots-clés : Ammonia decomposition Tungsten carbide Tungstated zirconia Résumé : Synthesis gas produced from biomass gasification can serve as a starting point for producing electricity, low-to-medium energy fuels, and even hydrogen for fuel cells. The major barrier in commercialization of biomass gasification is the presence of impurities such as NH3, tars, and H2S in the gas products that are detrimental to downstream processes. This paper reports the results of a study of NH3 decomposition to N2 and H2 on tungsten-based catalysts, tungsten carbide (WC) and tungstated zirconia (WZ), for a gasification gas cleanup strategy that involves removal of tars first followed by NH3 decomposition. The effects of the presence of H2 and CO on the behavior of these catalysts are also reported. At the NH3 decomposition reaction conditions used in the present study (1 atm, 465−650 °C, 4000 ppm), both WC and WZ showed an induction period. The main reason for this induction period is hypothesized to be a restructuring of the catalyst surface by NH3 so that the surface is more favorable for reaction. Both WC and WZ displayed superior activity compared to a commercial Fe-based NH3 synthesis catalyst (Amomax-10). At 600 °C and in the presence of syngas, no conversion was observed on WC while ca. 20% and 10% conversions were observed on WZ and Amomax-10, respectively, at steady state for the reaction conditions used. This corresponds to intrinsic rates of 1.2 μmol/g cat./s and 0.53 μmol/g cat./s (0.021 μmol/m2 cat./s and 3.1 μmol/m2 cat./s), respectively, for WZ and Amomax-10. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800077p
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4063–4070[article] Ammonia decomposition on tungsten-based catalysts in the absence and presence of syngas [texte imprimé] / Sourabh S. Pansare, Auteur ; James G. GoodwinJr., Auteur . - 2008 . - p. 4063–4070.
Bibliogr. p. 4069-4070
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4063–4070
Mots-clés : Ammonia decomposition Tungsten carbide Tungstated zirconia Résumé : Synthesis gas produced from biomass gasification can serve as a starting point for producing electricity, low-to-medium energy fuels, and even hydrogen for fuel cells. The major barrier in commercialization of biomass gasification is the presence of impurities such as NH3, tars, and H2S in the gas products that are detrimental to downstream processes. This paper reports the results of a study of NH3 decomposition to N2 and H2 on tungsten-based catalysts, tungsten carbide (WC) and tungstated zirconia (WZ), for a gasification gas cleanup strategy that involves removal of tars first followed by NH3 decomposition. The effects of the presence of H2 and CO on the behavior of these catalysts are also reported. At the NH3 decomposition reaction conditions used in the present study (1 atm, 465−650 °C, 4000 ppm), both WC and WZ showed an induction period. The main reason for this induction period is hypothesized to be a restructuring of the catalyst surface by NH3 so that the surface is more favorable for reaction. Both WC and WZ displayed superior activity compared to a commercial Fe-based NH3 synthesis catalyst (Amomax-10). At 600 °C and in the presence of syngas, no conversion was observed on WC while ca. 20% and 10% conversions were observed on WZ and Amomax-10, respectively, at steady state for the reaction conditions used. This corresponds to intrinsic rates of 1.2 μmol/g cat./s and 0.53 μmol/g cat./s (0.021 μmol/m2 cat./s and 3.1 μmol/m2 cat./s), respectively, for WZ and Amomax-10. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800077p Exemplaires
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Titre : Silicotungstic acid impregnated MCM-41-like mesoporous solid acid catalysts for dehydration of ethanol Type de document : texte imprimé Auteurs : Dilek Varisli, Auteur ; Timur Dogu, Auteur ; Gulsen Dogu, Auteur Année de publication : 2008 Article en page(s) : p. 4071–4076 Note générale : Bibliogr. p. 4076 Langues : Anglais (eng) Mots-clés : Mesoporous solid acid Impregnation Ethanol dehydration Résumé : In this study, mesoporous nanocomposite silicotungstic acid (STA) incorporated MCM-41 and mesoporous aluminosilicate catalysts with narrow pore size distributions, in the range of 2.5–3.5 nm, were successfully synthesized following different impregnation procedures. Results showed that the catalyst preparation procedure had significant influence on its activity as well as the product distribution in ethanol dehydration. STAMCM41C catalyst, which was prepared by the impregnation of STA into calcined MCM-41 containing a W/Si ratio of 0.24, and STAMAS catalyst, which was prepared by the impregnation of STA into mesoporous aluminosilicate, showed very high activities in dehydration of ethanol. Ethylene yield showed an increasing trend with temperature, reaching to about 100% above 250 °C. In contrast to ethylene, DEE was formed at lower temperatures, reaching to a yield value of about 70% at 180 °C with STAMCM41C. DEE formation at lower temperatures was concluded to be due to the presence of Bronsted acid sites of this catalyst. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800192t
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4071–4076[article] Silicotungstic acid impregnated MCM-41-like mesoporous solid acid catalysts for dehydration of ethanol [texte imprimé] / Dilek Varisli, Auteur ; Timur Dogu, Auteur ; Gulsen Dogu, Auteur . - 2008 . - p. 4071–4076.
Bibliogr. p. 4076
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4071–4076
Mots-clés : Mesoporous solid acid Impregnation Ethanol dehydration Résumé : In this study, mesoporous nanocomposite silicotungstic acid (STA) incorporated MCM-41 and mesoporous aluminosilicate catalysts with narrow pore size distributions, in the range of 2.5–3.5 nm, were successfully synthesized following different impregnation procedures. Results showed that the catalyst preparation procedure had significant influence on its activity as well as the product distribution in ethanol dehydration. STAMCM41C catalyst, which was prepared by the impregnation of STA into calcined MCM-41 containing a W/Si ratio of 0.24, and STAMAS catalyst, which was prepared by the impregnation of STA into mesoporous aluminosilicate, showed very high activities in dehydration of ethanol. Ethylene yield showed an increasing trend with temperature, reaching to about 100% above 250 °C. In contrast to ethylene, DEE was formed at lower temperatures, reaching to a yield value of about 70% at 180 °C with STAMCM41C. DEE formation at lower temperatures was concluded to be due to the presence of Bronsted acid sites of this catalyst. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800192t Exemplaires
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Titre : Toluene decomposition in the presence of hydrogen on tungsten-based catalysts Type de document : texte imprimé Auteurs : Sourabh S. Pansare, Auteur ; James G. GoodwinJr., Auteur ; Santosh Gangwal, Auteur Année de publication : 2008 Article en page(s) : p. 4077–4085 Note générale : Bibliogr. p. 4084-4085 Langues : Anglais (eng) Mots-clés : Toluene Tungstated zirconia Tungsten carbide Résumé : Removal of NH3, tars, and H2S from biomass gasification gas represents a significant step in the commercial use of biomass gasification as a source of hydrogen, syngas, and electricity. This paper reports the results of an investigation into the use of W-based catalysts [tungsten carbide (WC), tungstated zirconia (WZ), and platinum supported on tungstated zirconia (PtWZ)] for catalytic tar removal. In this study, toluene was used as a model compound for tars. In the case of WZ, the effect of calcination temperature on the activity of toluene decomposition was also investigated. The toluene decomposition reaction was conducted at 1 atm, in the temperature range of 300−800 °C, and in the presence of 10% H2. CH4 and benzene were the only detectable products of toluene decomposition on all the catalysts. Incorporation of 5 wt % Pt with WZ was found to give the most effective catalyst considering initial rates of product formation. WC, WZ, and PtWZ each showed an initial partial deactivation for both CH4 and benzene formation due to coke deposition on active sites. Pt incorporation had a significant effect on the steady-state activity of WZ for toluene decomposition at temperatures below 600 °C; however, at temperatures above 700 °C, the effect was nullified. All W-based catalysts showed comparable performance to that of a commercial cracking catalyst (ultra-stable Y zeolite) above 700 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8002864
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4077–4085[article] Toluene decomposition in the presence of hydrogen on tungsten-based catalysts [texte imprimé] / Sourabh S. Pansare, Auteur ; James G. GoodwinJr., Auteur ; Santosh Gangwal, Auteur . - 2008 . - p. 4077–4085.
Bibliogr. p. 4084-4085
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4077–4085
Mots-clés : Toluene Tungstated zirconia Tungsten carbide Résumé : Removal of NH3, tars, and H2S from biomass gasification gas represents a significant step in the commercial use of biomass gasification as a source of hydrogen, syngas, and electricity. This paper reports the results of an investigation into the use of W-based catalysts [tungsten carbide (WC), tungstated zirconia (WZ), and platinum supported on tungstated zirconia (PtWZ)] for catalytic tar removal. In this study, toluene was used as a model compound for tars. In the case of WZ, the effect of calcination temperature on the activity of toluene decomposition was also investigated. The toluene decomposition reaction was conducted at 1 atm, in the temperature range of 300−800 °C, and in the presence of 10% H2. CH4 and benzene were the only detectable products of toluene decomposition on all the catalysts. Incorporation of 5 wt % Pt with WZ was found to give the most effective catalyst considering initial rates of product formation. WC, WZ, and PtWZ each showed an initial partial deactivation for both CH4 and benzene formation due to coke deposition on active sites. Pt incorporation had a significant effect on the steady-state activity of WZ for toluene decomposition at temperatures below 600 °C; however, at temperatures above 700 °C, the effect was nullified. All W-based catalysts showed comparable performance to that of a commercial cracking catalyst (ultra-stable Y zeolite) above 700 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8002864 Exemplaires
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Titre : Kinetics and Reactor modeling of a high temperature water-gas shift reaction (WGSR) for hydrogen production in a packed bed tubular reactor (PBTR) Type de document : texte imprimé Auteurs : Prashant Kumar, Auteur ; Enefiok Akpan, Auteur ; Hussam Ibrahim, Auteur ; Ahmed Aboudheir, Auteur Année de publication : 2008 Article en page(s) : p. 4086–4097 Note générale : Bibliogr. p. 4096-4097 Langues : Anglais (eng) Mots-clés : Water− gas shift reaction Packed bed tubular reactor Reactor modeling Résumé : Kinetic, experimental, modeling, and simulation studies of a catalytic high temperature (673−873 K) water−gas shift reaction (WGSR) were performed in a packed bed tubular reactor (PBTR) at several values of W/FA0 (ratio of the mass of the catalyst to the mass flow rate of CO, g(cat)·h/mol of CO) over a new Ni−Cu/CeO2−ZrO2 (UFR-C) catalyst. Out of the kinetic models evaluated, the one that best predicted the experimental rates was based on the Langmuir−Hinshelwood (LH) formulation, assuming that the rate determining step (RDS) was the surface reaction between molecularly adsorbed carbon monoxide and water to give a formate intermediate and atomically adsorbed hydrogen. Reactor modeling was performed using a comprehensive numerical model consisting of two-dimensional coupled material and energy balance equations. The best mechanistic kinetic model developed was incorporated in the reactor model, which also contained the axial dispersion term, and was solved using the finite elements method. The validity of the reactor model was tested against the experimental data and a satisfactory agreement between the model prediction and measured results were obtained. In addition, the predicted concentration and temperature profiles for our process in both axial and radial direction indicate that the assumption of plug flow isothermal behavior is justified within certain kinetic operating conditions. Moreover, the well-known criteria for neglecting the axial dispersion term have been met in this case and it can conclusively be recommended to be eliminated from the model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071547q
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4086–4097[article] Kinetics and Reactor modeling of a high temperature water-gas shift reaction (WGSR) for hydrogen production in a packed bed tubular reactor (PBTR) [texte imprimé] / Prashant Kumar, Auteur ; Enefiok Akpan, Auteur ; Hussam Ibrahim, Auteur ; Ahmed Aboudheir, Auteur . - 2008 . - p. 4086–4097.
Bibliogr. p. 4096-4097
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4086–4097
Mots-clés : Water− gas shift reaction Packed bed tubular reactor Reactor modeling Résumé : Kinetic, experimental, modeling, and simulation studies of a catalytic high temperature (673−873 K) water−gas shift reaction (WGSR) were performed in a packed bed tubular reactor (PBTR) at several values of W/FA0 (ratio of the mass of the catalyst to the mass flow rate of CO, g(cat)·h/mol of CO) over a new Ni−Cu/CeO2−ZrO2 (UFR-C) catalyst. Out of the kinetic models evaluated, the one that best predicted the experimental rates was based on the Langmuir−Hinshelwood (LH) formulation, assuming that the rate determining step (RDS) was the surface reaction between molecularly adsorbed carbon monoxide and water to give a formate intermediate and atomically adsorbed hydrogen. Reactor modeling was performed using a comprehensive numerical model consisting of two-dimensional coupled material and energy balance equations. The best mechanistic kinetic model developed was incorporated in the reactor model, which also contained the axial dispersion term, and was solved using the finite elements method. The validity of the reactor model was tested against the experimental data and a satisfactory agreement between the model prediction and measured results were obtained. In addition, the predicted concentration and temperature profiles for our process in both axial and radial direction indicate that the assumption of plug flow isothermal behavior is justified within certain kinetic operating conditions. Moreover, the well-known criteria for neglecting the axial dispersion term have been met in this case and it can conclusively be recommended to be eliminated from the model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071547q Exemplaires
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Titre : Preferential oxidation of carbon monoxide in hydrogen stream over Au/MgOx-TiO2 catalysts Type de document : texte imprimé Auteurs : Li-Hsin Chang, Auteur ; Chen, Yu-Wen, Auteur ; Natarajan Sasirekha, Auteur Année de publication : 2008 Article en page(s) : p. 4098–4105 Note générale : Bibliogr. p. 4104-4105 Langues : Anglais (eng) Mots-clés : Au/MgOx− TiO2 -- catalytic activity Carbon monoxide Impregnation method Aqueous solutions Deposition− precipitation Résumé : A series of Au/MgOx−TiO2 with various Mg/Ti molar ratios was prepared to study its catalytic activity for preferential oxidation of carbon monoxide in hydrogen-rich stream (PROX). An incipient wetness impregnation method was used to prepare the MgOx−TiO2 support, using aqueous solutions of Mg(NO3)2 on TiO2 calcined at 300 °C. A deposition−precipitation (DP) method was utilized to prepare Au/MgOx−TiO2, using HAuCl4 as the starting material. Au/MgOx and Au/TiO2 were also included for comparison. Investigation was carried out to study the effect of Mg/Ti molar ratio on the catalytic properties of gold supported catalysts. The catalysts were characterized by inductively couple plasma-mass spectrometry, X-ray diffraction, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. TEM results revealed the presence of nanosized gold particles and narrow particle size distribution on all the catalysts. MgOx was deposited on the TiO2 surface in the form of thin islands without definite shape. MgOx was mainly present as Mg(OH)2. Au particles were deposited on the surface of TiO2 in intimate contact with MgOx. The gold particle size was around 2.5 nm and was smaller than the MgOx particles. Since the surface area of TiO2 was small and the MgOx concentration was comparatively higher than Au concentration, Au should be in intimate contact with MgOx on the TiO2 surface. However, the exact status depends upon the Mg/Ti ratio and pH value during DP process to deposit gold. Au/MgOx−TiO2 with suitable amount of MgOx has higher CO conversion and higher selectivity of O2 to CO oxidation in the PROX reaction than Au/MgO and Au/TiO2. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071590d
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4098–4105[article] Preferential oxidation of carbon monoxide in hydrogen stream over Au/MgOx-TiO2 catalysts [texte imprimé] / Li-Hsin Chang, Auteur ; Chen, Yu-Wen, Auteur ; Natarajan Sasirekha, Auteur . - 2008 . - p. 4098–4105.
Bibliogr. p. 4104-4105
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4098–4105
Mots-clés : Au/MgOx− TiO2 -- catalytic activity Carbon monoxide Impregnation method Aqueous solutions Deposition− precipitation Résumé : A series of Au/MgOx−TiO2 with various Mg/Ti molar ratios was prepared to study its catalytic activity for preferential oxidation of carbon monoxide in hydrogen-rich stream (PROX). An incipient wetness impregnation method was used to prepare the MgOx−TiO2 support, using aqueous solutions of Mg(NO3)2 on TiO2 calcined at 300 °C. A deposition−precipitation (DP) method was utilized to prepare Au/MgOx−TiO2, using HAuCl4 as the starting material. Au/MgOx and Au/TiO2 were also included for comparison. Investigation was carried out to study the effect of Mg/Ti molar ratio on the catalytic properties of gold supported catalysts. The catalysts were characterized by inductively couple plasma-mass spectrometry, X-ray diffraction, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. TEM results revealed the presence of nanosized gold particles and narrow particle size distribution on all the catalysts. MgOx was deposited on the TiO2 surface in the form of thin islands without definite shape. MgOx was mainly present as Mg(OH)2. Au particles were deposited on the surface of TiO2 in intimate contact with MgOx. The gold particle size was around 2.5 nm and was smaller than the MgOx particles. Since the surface area of TiO2 was small and the MgOx concentration was comparatively higher than Au concentration, Au should be in intimate contact with MgOx on the TiO2 surface. However, the exact status depends upon the Mg/Ti ratio and pH value during DP process to deposit gold. Au/MgOx−TiO2 with suitable amount of MgOx has higher CO conversion and higher selectivity of O2 to CO oxidation in the PROX reaction than Au/MgO and Au/TiO2. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071590d Exemplaires
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Titre : Conversion of glucose to hydrogen-rich gas by supercritical water in a microchannel reactor Type de document : texte imprimé Auteurs : Aron K. Goodwin, Auteur ; Gregory L. Rorrer, Auteur Année de publication : 2008 Article en page(s) : p. 4106–4114 Note générale : Bibliogr. p. 4113-4114 Langues : Anglais (eng) Mots-clés : Microchannel reactors Glucose -- gasification Supercritical water Résumé : Microchannel reactors offer the intensification of heat transfer to endothermic chemical reactions. Microchannel reactors consist of a parallel array of micron-scale channels that are integrated into one device using microfabrication techniques. The gasification of glucose by supercritical water was studied in a stainless-steel microchannel reactor at 250 bar and 650−750 °C. The microchannel reactor architecture consisted of a parallel array of 21 rectangular microchannels (75 µm × 500 µm), each of 100 cm length, that were packaged into a serpentine pattern of 25 layers. At 750 °C, glucose was completely converted to gas products within a 2.0 s residence time, yielding an average gas composition of 53% H2, 35% CO2, 10% CH4, and 0.5% CO and a H2 yield of 5.7 ± 0.3 mol H2/mol glucose. At 650 °C, the intermediate products from the decomposition of glucose prior to their gasification and reforming were characterized. Routes for glucose transformation included the decomposition to acetic and propanoic acids, acid-catalyzed dehydration to 5-hydroxymethylfurfural and 2,5-hexanedione, and conversion to phenol. This study has shown that microchannel reactors have considerable promise for intensifying the thermochemical conversion of biomass constituents to useful chemicals and fuels. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701725p
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4106–4114[article] Conversion of glucose to hydrogen-rich gas by supercritical water in a microchannel reactor [texte imprimé] / Aron K. Goodwin, Auteur ; Gregory L. Rorrer, Auteur . - 2008 . - p. 4106–4114.
Bibliogr. p. 4113-4114
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4106–4114
Mots-clés : Microchannel reactors Glucose -- gasification Supercritical water Résumé : Microchannel reactors offer the intensification of heat transfer to endothermic chemical reactions. Microchannel reactors consist of a parallel array of micron-scale channels that are integrated into one device using microfabrication techniques. The gasification of glucose by supercritical water was studied in a stainless-steel microchannel reactor at 250 bar and 650−750 °C. The microchannel reactor architecture consisted of a parallel array of 21 rectangular microchannels (75 µm × 500 µm), each of 100 cm length, that were packaged into a serpentine pattern of 25 layers. At 750 °C, glucose was completely converted to gas products within a 2.0 s residence time, yielding an average gas composition of 53% H2, 35% CO2, 10% CH4, and 0.5% CO and a H2 yield of 5.7 ± 0.3 mol H2/mol glucose. At 650 °C, the intermediate products from the decomposition of glucose prior to their gasification and reforming were characterized. Routes for glucose transformation included the decomposition to acetic and propanoic acids, acid-catalyzed dehydration to 5-hydroxymethylfurfural and 2,5-hexanedione, and conversion to phenol. This study has shown that microchannel reactors have considerable promise for intensifying the thermochemical conversion of biomass constituents to useful chemicals and fuels. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701725p Exemplaires
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Titre : Production of bio-oil from alfalfa stems by fluidized-bed fast pyrolysis Type de document : texte imprimé Auteurs : Akwasi A. Boateng, Auteur ; Charles A. Mullen, Auteur ; Neil Goldberg, Auteur ; Kevin B. Hicks, Auteur Année de publication : 2008 Article en page(s) : p. 4115–4122 Note générale : Bibliogr. p. 4122 Langues : Anglais (eng) Mots-clés : Alfalfa stem material Bio-oil Pyrolysis Résumé : This study focused on the production of bio-oil from alfalfa stem material. Two alfalfa maturity stages, harvested at the early bud and full flower stages of development, were examined to evaluate the impact of variation in cell wall polysaccharide and lignin content on pyrolysis oil yields, production efficiency, and bio-oil and char quality, in terms of their use as combustion fuel and for chemicals. Findings included a lower-than-average yield of bio-oil and a higher-than-average yield of charcoal from alfalfa stems, compared to previous results for other biomass feedstocks. The bio-oil showed a decrease in oxygen content from the alfalfa stems, leading to a higher-than-average energy content in the bio-oil. Bio-oil yields were slightly higher for the more-mature alfalfa, which had higher levels of cell wall cellulose and lignin. Overall, when all the pyrolysis products were considered, energy recovery was better for the more-mature alfalfa stems.
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4115–4122[article] Production of bio-oil from alfalfa stems by fluidized-bed fast pyrolysis [texte imprimé] / Akwasi A. Boateng, Auteur ; Charles A. Mullen, Auteur ; Neil Goldberg, Auteur ; Kevin B. Hicks, Auteur . - 2008 . - p. 4115–4122.
Bibliogr. p. 4122
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4115–4122
Mots-clés : Alfalfa stem material Bio-oil Pyrolysis Résumé : This study focused on the production of bio-oil from alfalfa stem material. Two alfalfa maturity stages, harvested at the early bud and full flower stages of development, were examined to evaluate the impact of variation in cell wall polysaccharide and lignin content on pyrolysis oil yields, production efficiency, and bio-oil and char quality, in terms of their use as combustion fuel and for chemicals. Findings included a lower-than-average yield of bio-oil and a higher-than-average yield of charcoal from alfalfa stems, compared to previous results for other biomass feedstocks. The bio-oil showed a decrease in oxygen content from the alfalfa stems, leading to a higher-than-average energy content in the bio-oil. Bio-oil yields were slightly higher for the more-mature alfalfa, which had higher levels of cell wall cellulose and lignin. Overall, when all the pyrolysis products were considered, energy recovery was better for the more-mature alfalfa stems. Exemplaires
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Titre : Molecular design of Fe3O4-containing polyimide as a route to nanomagnetic materials Type de document : texte imprimé Auteurs : Süleyman Köytepe, Auteur ; Turgay Seçkin, Auteur Année de publication : 2008 Article en page(s) : p. 4123–4130 Note générale : Bibliogr. p. 4129-4130 Langues : Anglais (eng) Mots-clés : Fe3O4-containing polyimide Magnetic properties X-ray diffraction Scanning electron microscopy Résumé : γ-Fe3O4 doped polyimide films with different weight percentages (1, 5, and 10 wt % of Fe3O4) have been prepared and the effect of nonmagnetic γ-Fe3O4 content on the structural and magnetic properties has been studied. X-ray diffraction (XRD) studies revealed that the nanopowders obtained are magnetite. The calculated grain sizes from XRD data have been verified using scanning electron microscopy (SEM). SEM micrographs show that the powders consist of nanometer-sized grains. Magnetic hysteresis loops were measured at room temperature with a maximum applied magnetic field. As the γ-Fe3O4 content increases, the measured magnetic hysteresis curves become more and more narrow and the saturation magnetization and remanent magnetization both decreased. The prepared nanocomposites were identified in terms of their structure, morphology, and magnetic and thermal properties. These studies showed that the particles seem to be dispersed randomly, although the particles do appear to form aggregates at increasing particle loadings. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701690w
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4123–4130[article] Molecular design of Fe3O4-containing polyimide as a route to nanomagnetic materials [texte imprimé] / Süleyman Köytepe, Auteur ; Turgay Seçkin, Auteur . - 2008 . - p. 4123–4130.
Bibliogr. p. 4129-4130
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4123–4130
Mots-clés : Fe3O4-containing polyimide Magnetic properties X-ray diffraction Scanning electron microscopy Résumé : γ-Fe3O4 doped polyimide films with different weight percentages (1, 5, and 10 wt % of Fe3O4) have been prepared and the effect of nonmagnetic γ-Fe3O4 content on the structural and magnetic properties has been studied. X-ray diffraction (XRD) studies revealed that the nanopowders obtained are magnetite. The calculated grain sizes from XRD data have been verified using scanning electron microscopy (SEM). SEM micrographs show that the powders consist of nanometer-sized grains. Magnetic hysteresis loops were measured at room temperature with a maximum applied magnetic field. As the γ-Fe3O4 content increases, the measured magnetic hysteresis curves become more and more narrow and the saturation magnetization and remanent magnetization both decreased. The prepared nanocomposites were identified in terms of their structure, morphology, and magnetic and thermal properties. These studies showed that the particles seem to be dispersed randomly, although the particles do appear to form aggregates at increasing particle loadings. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701690w Exemplaires
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Titre : Macroporous gel particles as novel sorbent materials : rational design Type de document : texte imprimé Auteurs : Fatima M. Plieva, Auteur ; Bo Mattiasson, Auteur Année de publication : 2008 Article en page(s) : p. 4131–4141 Note générale : Bibliogr. p. 4140-4141 Langues : Anglais (eng) Mots-clés : Macroporous gels Cu(II)-ions Résumé : A novel design approach to form macroporous gels is presented. Macroporous gels (MGs), known as cryogels (or gels prepared at subzero temperatures), were prepared inside a protective plastic core (so-called, housing), thus making them resistant to shear forces at stirring. MGs are highly elastic polymeric materials with pore sizes up to 100 µm and spongelike morphology. Design of MGs inside a protective plastic core (defined as macroporous gel particles, MGPs) allows for expanding the potential applications of such polymeric materials, even to processes in well-stirred bioreactors. MGPs are resistant to attrition caused by continuous stirring at 400 rpm, while the MGs (prepared under the same conditions) were completely crushed within 1–2 h of stirring. MGPs with a different functionality were prepared and used in the model sorption experiments. Thus, polyacrylamide-based MGPs of different porosities and bearing metal-chelate ligand, iminodiacetate (IDA), were used for capture of Cu(II)-ions at low concentration from water. Because of the large size of interconnected pores in the MGPs, targets of different sizes (low molecular weight targets as Cu(II)-ions and particulate targets as yeast cells) can be captured on the MGPs (bearing specific ligands to the targets) from a complex mixture. The MGPs can be dried, stored in the dried state, and reswollen when required. The open permeable porous structure of MGPs and high stability at stirring together with ease of preparation make the MGPs a very attractive, novel, robust sorbent medium for different biotechnological applications. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071406o
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4131–4141[article] Macroporous gel particles as novel sorbent materials : rational design [texte imprimé] / Fatima M. Plieva, Auteur ; Bo Mattiasson, Auteur . - 2008 . - p. 4131–4141.
Bibliogr. p. 4140-4141
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4131–4141
Mots-clés : Macroporous gels Cu(II)-ions Résumé : A novel design approach to form macroporous gels is presented. Macroporous gels (MGs), known as cryogels (or gels prepared at subzero temperatures), were prepared inside a protective plastic core (so-called, housing), thus making them resistant to shear forces at stirring. MGs are highly elastic polymeric materials with pore sizes up to 100 µm and spongelike morphology. Design of MGs inside a protective plastic core (defined as macroporous gel particles, MGPs) allows for expanding the potential applications of such polymeric materials, even to processes in well-stirred bioreactors. MGPs are resistant to attrition caused by continuous stirring at 400 rpm, while the MGs (prepared under the same conditions) were completely crushed within 1–2 h of stirring. MGPs with a different functionality were prepared and used in the model sorption experiments. Thus, polyacrylamide-based MGPs of different porosities and bearing metal-chelate ligand, iminodiacetate (IDA), were used for capture of Cu(II)-ions at low concentration from water. Because of the large size of interconnected pores in the MGPs, targets of different sizes (low molecular weight targets as Cu(II)-ions and particulate targets as yeast cells) can be captured on the MGPs (bearing specific ligands to the targets) from a complex mixture. The MGPs can be dried, stored in the dried state, and reswollen when required. The open permeable porous structure of MGPs and high stability at stirring together with ease of preparation make the MGPs a very attractive, novel, robust sorbent medium for different biotechnological applications. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071406o Exemplaires
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Titre : Microencapsulation of limonene for textile application Type de document : texte imprimé Auteurs : Sofia N. Rodrigues, Auteur ; Isabel Fernandes, Auteur ; Isabel M. Martins, Auteur ; Vera G. Mata, Auteur Année de publication : 2008 Article en page(s) : p. 4142–4147 Note générale : Bibliogr. p. 4246-4247 Langues : Anglais (eng) Mots-clés : Polyurethane− urea microcapsules -- textile applications Limonene Polymerization Résumé : Polyurethane−urea microcapsules with limonene oil as the active agent were produced by interfacial polymerization, and their suitability for textile applications was studied. Experimental conditions for the textile substrates impregnation were based on industrial requirements and set up at laboratory scale using a mini-foulard. The success of the polymerization reaction leading to the formation of the polyurethane−urea shell was checked by Fourier transform infrared spectroscopy. Particle size distributions and morphology of the microcapsules were studied using a particle size analyzer (Coulter LS230), optical microscopy, and scanning electron microscopy. The effectiveness of the textiles impregnation and the durability of the impregnation effect were evaluated by scanning electron microscopy and by headspace/GC/FID. Under the present research, a product was developed and its performance, in regard to industrial requirements, was successfully tested. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800090c
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4142–4147[article] Microencapsulation of limonene for textile application [texte imprimé] / Sofia N. Rodrigues, Auteur ; Isabel Fernandes, Auteur ; Isabel M. Martins, Auteur ; Vera G. Mata, Auteur . - 2008 . - p. 4142–4147.
Bibliogr. p. 4246-4247
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4142–4147
Mots-clés : Polyurethane− urea microcapsules -- textile applications Limonene Polymerization Résumé : Polyurethane−urea microcapsules with limonene oil as the active agent were produced by interfacial polymerization, and their suitability for textile applications was studied. Experimental conditions for the textile substrates impregnation were based on industrial requirements and set up at laboratory scale using a mini-foulard. The success of the polymerization reaction leading to the formation of the polyurethane−urea shell was checked by Fourier transform infrared spectroscopy. Particle size distributions and morphology of the microcapsules were studied using a particle size analyzer (Coulter LS230), optical microscopy, and scanning electron microscopy. The effectiveness of the textiles impregnation and the durability of the impregnation effect were evaluated by scanning electron microscopy and by headspace/GC/FID. Under the present research, a product was developed and its performance, in regard to industrial requirements, was successfully tested. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800090c Exemplaires
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Titre : Robust optimization for process scheduling under uncertainty Type de document : texte imprimé Auteurs : Zukui Li, Auteur ; Marianthi G. Ierapetritou, Auteur Année de publication : 2008 Article en page(s) : p. 4148–4157 Note générale : Bibliogr. p. 4157 Langues : Anglais (eng) Mots-clés : Process scheduling Robust optimization Stochastic programming method Résumé : This paper addresses the uncertainty problem in process scheduling using robust optimization. Compared to the traditional-scenario-based stochastic programming method, robust counterpart optimization method has a unique advantage, in that the scale of the corresponding optimization problem does not increase exponentially with the number of the uncertain parameters. Three robust counterpart optimization formulations―including Soyster’s worst-case scenario formulation, Ben-Tal and Nemirovski’s formulation, and a formulation proposed by Bertsimas and Sim―are studied and applied to uncertain scheduling problems in this paper. The results show that the formulation proposed by Bertsimas and Sim is the most appropriate model for uncertain scheduling problems, because it has the following advantages: (i) the model has the same size as the other formulations, (ii) it preserves its linearity, and (iii) it has the ability to control the degree of conservatism for every constraint and guarantees feasibility for the robust optimization problem. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071431u
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4148–4157[article] Robust optimization for process scheduling under uncertainty [texte imprimé] / Zukui Li, Auteur ; Marianthi G. Ierapetritou, Auteur . - 2008 . - p. 4148–4157.
Bibliogr. p. 4157
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4148–4157
Mots-clés : Process scheduling Robust optimization Stochastic programming method Résumé : This paper addresses the uncertainty problem in process scheduling using robust optimization. Compared to the traditional-scenario-based stochastic programming method, robust counterpart optimization method has a unique advantage, in that the scale of the corresponding optimization problem does not increase exponentially with the number of the uncertain parameters. Three robust counterpart optimization formulations―including Soyster’s worst-case scenario formulation, Ben-Tal and Nemirovski’s formulation, and a formulation proposed by Bertsimas and Sim―are studied and applied to uncertain scheduling problems in this paper. The results show that the formulation proposed by Bertsimas and Sim is the most appropriate model for uncertain scheduling problems, because it has the following advantages: (i) the model has the same size as the other formulations, (ii) it preserves its linearity, and (iii) it has the ability to control the degree of conservatism for every constraint and guarantees feasibility for the robust optimization problem. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071431u Exemplaires
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Titre : Time-optimal control of startup distillation columns by iterative dynamic programming Type de document : texte imprimé Auteurs : Alexandru Woinaroschy, Auteur Année de publication : 2008 Article en page(s) : p. 4158–4169 Note générale : Bibliogr. p. 4169 Langues : Anglais (eng) Mots-clés : Distillation startup time Dynamic programming Iterative algebraic equation Résumé : Iterative dynamic programming employing randomly chosen candidates for admissible control is applied to the minimization of distillation startup time. The solution of this high-dimensional problem was facilitated mainly by avoiding iterative algebraic equation solving inside a rigorous dynamic distillation model, thereby reducing the computation time. Several illustrative applications of various complexity degrees are presented. The control variables are the reflux ratio, the reboiler heat duty, or both. Both piecewise constant control and piecewise linear control strategies were employed. The decrease of the startup times and heat consumption is high, having an appreciable economic significance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0713745
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4158–4169[article] Time-optimal control of startup distillation columns by iterative dynamic programming [texte imprimé] / Alexandru Woinaroschy, Auteur . - 2008 . - p. 4158–4169.
Bibliogr. p. 4169
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4158–4169
Mots-clés : Distillation startup time Dynamic programming Iterative algebraic equation Résumé : Iterative dynamic programming employing randomly chosen candidates for admissible control is applied to the minimization of distillation startup time. The solution of this high-dimensional problem was facilitated mainly by avoiding iterative algebraic equation solving inside a rigorous dynamic distillation model, thereby reducing the computation time. Several illustrative applications of various complexity degrees are presented. The control variables are the reflux ratio, the reboiler heat duty, or both. Both piecewise constant control and piecewise linear control strategies were employed. The decrease of the startup times and heat consumption is high, having an appreciable economic significance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0713745 Exemplaires
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Titre : Process flexibility for multivariable systems Type de document : texte imprimé Auteurs : Sau M. Lai, Auteur ; Chi-Wai Hui, Auteur Année de publication : 2008 Article en page(s) : p. 4170–4183 Note générale : Bibliogr. p. 4182-4182 Langues : Anglais (eng) Mots-clés : Process flexibility FIV evaluation Internal process External process Résumé : Process flexibility is important to ensure that an operation can be both profitable and manipulative to changes in internal or external process parameters. A new flexibility metric (FIV) is defined based on the hypervolume ratio of the feasible region and the region containing all combinations of expected uncertain parameters. The FIV evaluation requires a hypervolume determination which may not be straightforward for multidimensional systems or systems with nonconvex feasible regions. Thus, an auxiliary vector approach is developed to estimate the feasible space’s size. Compared to the existing methodologies, this new method is able to provide a reliable and facile flexibility evaluation. In addition, this approach can also offer indications of the possible future changes to enhance the overall flexibility. This information is useful for making reasonable and rational engineering decisions to retrofit the designs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070183z
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4170–4183[article] Process flexibility for multivariable systems [texte imprimé] / Sau M. Lai, Auteur ; Chi-Wai Hui, Auteur . - 2008 . - p. 4170–4183.
Bibliogr. p. 4182-4182
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4170–4183
Mots-clés : Process flexibility FIV evaluation Internal process External process Résumé : Process flexibility is important to ensure that an operation can be both profitable and manipulative to changes in internal or external process parameters. A new flexibility metric (FIV) is defined based on the hypervolume ratio of the feasible region and the region containing all combinations of expected uncertain parameters. The FIV evaluation requires a hypervolume determination which may not be straightforward for multidimensional systems or systems with nonconvex feasible regions. Thus, an auxiliary vector approach is developed to estimate the feasible space’s size. Compared to the existing methodologies, this new method is able to provide a reliable and facile flexibility evaluation. In addition, this approach can also offer indications of the possible future changes to enhance the overall flexibility. This information is useful for making reasonable and rational engineering decisions to retrofit the designs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070183z Exemplaires
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Titre : A Karhunen-Loève decomposition-based Wiener modeling approach for nonlinear distributed parameter processes Type de document : texte imprimé Auteurs : Chenkun Qi, Auteur ; Han-Xiong Li, Auteur Année de publication : 2008 Article en page(s) : p. 4184–4192 Note générale : Bibliogr. p. 4191-4192 Langues : Anglais (eng) Mots-clés : Spatio-temporal modeling problem Wiener modeling Karhunen− Loève decomposition Résumé : The spatio-temporal modeling problem from the input and output measurements for distributed parameter processes under unknown circumstances is investigated. The traditional Wiener modeling is extended to nonlinear distributed parameter systems with the help of the Karhunen−Loève (KL) decomposition. The input is a finite-dimensional temporal variable, whereas the spatio-temporal output of the system is measured at a finite number of spatial locations. First, the measured output is used to construct a finite dimensional approximation of the system output which is expanded in terms of KL spatial basis functions. Subsequently, the temporal coefficients are used to identify a Wiener model. The identification algorithm is based on the least-squares estimation and the instrumental variables method. The simulations for parabolic and hyperbolic systems are presented to show the effectiveness of this spatio-temporal modeling method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0710869
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4184–4192[article] A Karhunen-Loève decomposition-based Wiener modeling approach for nonlinear distributed parameter processes [texte imprimé] / Chenkun Qi, Auteur ; Han-Xiong Li, Auteur . - 2008 . - p. 4184–4192.
Bibliogr. p. 4191-4192
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4184–4192
Mots-clés : Spatio-temporal modeling problem Wiener modeling Karhunen− Loève decomposition Résumé : The spatio-temporal modeling problem from the input and output measurements for distributed parameter processes under unknown circumstances is investigated. The traditional Wiener modeling is extended to nonlinear distributed parameter systems with the help of the Karhunen−Loève (KL) decomposition. The input is a finite-dimensional temporal variable, whereas the spatio-temporal output of the system is measured at a finite number of spatial locations. First, the measured output is used to construct a finite dimensional approximation of the system output which is expanded in terms of KL spatial basis functions. Subsequently, the temporal coefficients are used to identify a Wiener model. The identification algorithm is based on the least-squares estimation and the instrumental variables method. The simulations for parabolic and hyperbolic systems are presented to show the effectiveness of this spatio-temporal modeling method. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0710869 Exemplaires
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Titre : Separation and purification of schisandrin B from fructus schisandrae Type de document : texte imprimé Auteurs : Ka F. Luk, Auteur ; Kam M. Ko, Auteur ; Ka M. Ng, Auteur Année de publication : 2008 Article en page(s) : p. 4193–4201 Note générale : Bibliogr. p. 4201 Langues : Anglais (eng) Mots-clés : Schisandrin B Fructus Schisandrae Solid–liquid extraction Adsorption-desorption Résumé : Schisandrin B (Sch B) is the most abundant and biologically active dibenzocyclooctadiene lignan present in Fructus Schisandrae (FS). It is a highly desirable ingredient for a dietary supplement. While Sch B has been isolated from FS in the laboratory, the experimental procedure was usually lengthy and the yield was relatively low. The objective of this study is to develop a process that is amenable to large-scale recovery of Sch B from FS. The process starts with solid–liquid extraction of FS by petroleum ether to yield a Sch B-containing extract, which is then purified by removing the relatively nonpolar substances, mostly fatty oils, by an adsorption–desorption step. This is followed by a chromatographic process to isolate the Sch B-enriched fraction that is then used to yield Sch B by crystallization. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071317b
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4193–4201[article] Separation and purification of schisandrin B from fructus schisandrae [texte imprimé] / Ka F. Luk, Auteur ; Kam M. Ko, Auteur ; Ka M. Ng, Auteur . - 2008 . - p. 4193–4201.
Bibliogr. p. 4201
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4193–4201
Mots-clés : Schisandrin B Fructus Schisandrae Solid–liquid extraction Adsorption-desorption Résumé : Schisandrin B (Sch B) is the most abundant and biologically active dibenzocyclooctadiene lignan present in Fructus Schisandrae (FS). It is a highly desirable ingredient for a dietary supplement. While Sch B has been isolated from FS in the laboratory, the experimental procedure was usually lengthy and the yield was relatively low. The objective of this study is to develop a process that is amenable to large-scale recovery of Sch B from FS. The process starts with solid–liquid extraction of FS by petroleum ether to yield a Sch B-containing extract, which is then purified by removing the relatively nonpolar substances, mostly fatty oils, by an adsorption–desorption step. This is followed by a chromatographic process to isolate the Sch B-enriched fraction that is then used to yield Sch B by crystallization. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071317b Exemplaires
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Titre : Optimization of batch operating policies. Part II. incorporating process constraints and industrial applications Type de document : texte imprimé Auteurs : Salvador García-Muñoz, Auteur ; John F. MacGregor, Auteur ; Debashis Neogi, Auteur ; Bruce E. Latshaw, Auteur Année de publication : 2008 Article en page(s) : p. 4202–4208 Note générale : Bibliogr. p. 4208 Langues : Anglais (eng) Mots-clés : Partial least squares Batch data Résumé : In the first part of this series [Ind. Eng. Chem. Res. 2006, 45, 7856−7866], data-driven approaches, based on partial least squares (PLS) models built from historical batch data, were used to find optimal batch operating trajectories that would yield a desired vector of final product quality attributes. The method allowed for the inclusion of univariate and multivariate constraints on the set of desired final product quality attributes and presented approaches for handling multiple solutions. In this paper, the technology is further extended to include constraints in the process operating trajectories themselves. The methodology is successfully applied to an industrial batch polymerization process where the batch trajectories are designed to achieve specific properties of the final polymer while consuming the minimal amount of time for the batch run. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071437j
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4202–4208[article] Optimization of batch operating policies. Part II. incorporating process constraints and industrial applications [texte imprimé] / Salvador García-Muñoz, Auteur ; John F. MacGregor, Auteur ; Debashis Neogi, Auteur ; Bruce E. Latshaw, Auteur . - 2008 . - p. 4202–4208.
Bibliogr. p. 4208
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4202–4208
Mots-clés : Partial least squares Batch data Résumé : In the first part of this series [Ind. Eng. Chem. Res. 2006, 45, 7856−7866], data-driven approaches, based on partial least squares (PLS) models built from historical batch data, were used to find optimal batch operating trajectories that would yield a desired vector of final product quality attributes. The method allowed for the inclusion of univariate and multivariate constraints on the set of desired final product quality attributes and presented approaches for handling multiple solutions. In this paper, the technology is further extended to include constraints in the process operating trajectories themselves. The methodology is successfully applied to an industrial batch polymerization process where the batch trajectories are designed to achieve specific properties of the final polymer while consuming the minimal amount of time for the batch run. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071437j Exemplaires
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Titre : Self-organizing self-clustering network : a strategy for unsupervised pattern classification with its application to fault diagnosis Type de document : texte imprimé Auteurs : Bharat Bhushan, Auteur ; Jose A. Romagnoli, Auteur Année de publication : 2008 Article en page(s) : p. 4209–4219 Note générale : Bibliogr. p. 4219 Langues : Anglais (eng) Mots-clés : Unsupervised pattern classification Self-organizing network Self-clustering network Résumé : In this work, we propose a method for unsupervised pattern classification called self-organizing self-clustering network. This method incorporates the concept of fuzzy clustering into the learning strategy of the self-organizing map. The number of nodes in the network is determined incrementally during the training. The advantage of the proposed strategy over other existing clustering techniques is its ability to determine network size and the number of clusters in data sets automatically. Since the methodology is based on learning, it is computationally less expensive, and the result is not affected by the initial guess. A data set with Gaussian distribution is used to illustrate this method, and results are compared with fuzzy C-mean clustering. Furthermore, the proposed strategy is applied for the fault detection and diagnosis of a twin-continuous tank reactor virtual plant. The result shows that this strategy can be used as a process-monitoring tool in an industrial environment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071549a
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4209–4219[article] Self-organizing self-clustering network : a strategy for unsupervised pattern classification with its application to fault diagnosis [texte imprimé] / Bharat Bhushan, Auteur ; Jose A. Romagnoli, Auteur . - 2008 . - p. 4209–4219.
Bibliogr. p. 4219
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4209–4219
Mots-clés : Unsupervised pattern classification Self-organizing network Self-clustering network Résumé : In this work, we propose a method for unsupervised pattern classification called self-organizing self-clustering network. This method incorporates the concept of fuzzy clustering into the learning strategy of the self-organizing map. The number of nodes in the network is determined incrementally during the training. The advantage of the proposed strategy over other existing clustering techniques is its ability to determine network size and the number of clusters in data sets automatically. Since the methodology is based on learning, it is computationally less expensive, and the result is not affected by the initial guess. A data set with Gaussian distribution is used to illustrate this method, and results are compared with fuzzy C-mean clustering. Furthermore, the proposed strategy is applied for the fault detection and diagnosis of a twin-continuous tank reactor virtual plant. The result shows that this strategy can be used as a process-monitoring tool in an industrial environment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071549a Exemplaires
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Titre : Plantwide fault isolation using nonlinear feedback control Type de document : texte imprimé Auteurs : Benjamin J. Ohran, Auteur ; Johnny Rau, Auteur ; Panagiotis D. Christofides, Auteur ; James F. Davis, Auteur Année de publication : 2008 Article en page(s) : p. 4220–4229 Note générale : Bibliogr. p. 4229 Langues : Anglais (eng) Mots-clés : Plantwide fault isolation Multiunit chemical process Nonlinear model-based control Résumé : Accurate detection and isolation of faults is a critical component of a reliable and efficient plantwide fault-tolerant control system. In a recent work (Ohran et al. AIChE J. 2008, 54, 223), we demonstrated that using a nonlinear controller to enforce a specific structure in the closed-loop system allows data-based detection and isolation of certain faults that would otherwise not be isolable using data-based techniques that do not impose the necessary closed-loop system structure. In this work, it is demonstrated through a multiunit chemical process example how this approach can be applied in a plantwide setting. By using nonlinear, model-based control laws to decouple certain states from faults of interest, unique fault responses in the state trajectories are obtained in the closed-loop system. On the basis of the unique responses, fault isolation becomes possible using data-based statistical process monitoring methods. The effectiveness of the method was tested through an extensive Monte Carlo simulation study of 500 runs for each of four fault scenarios and through comparison with a conventional (proportional−integral) feedback control law. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071548i
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4220–4229[article] Plantwide fault isolation using nonlinear feedback control [texte imprimé] / Benjamin J. Ohran, Auteur ; Johnny Rau, Auteur ; Panagiotis D. Christofides, Auteur ; James F. Davis, Auteur . - 2008 . - p. 4220–4229.
Bibliogr. p. 4229
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4220–4229
Mots-clés : Plantwide fault isolation Multiunit chemical process Nonlinear model-based control Résumé : Accurate detection and isolation of faults is a critical component of a reliable and efficient plantwide fault-tolerant control system. In a recent work (Ohran et al. AIChE J. 2008, 54, 223), we demonstrated that using a nonlinear controller to enforce a specific structure in the closed-loop system allows data-based detection and isolation of certain faults that would otherwise not be isolable using data-based techniques that do not impose the necessary closed-loop system structure. In this work, it is demonstrated through a multiunit chemical process example how this approach can be applied in a plantwide setting. By using nonlinear, model-based control laws to decouple certain states from faults of interest, unique fault responses in the state trajectories are obtained in the closed-loop system. On the basis of the unique responses, fault isolation becomes possible using data-based statistical process monitoring methods. The effectiveness of the method was tested through an extensive Monte Carlo simulation study of 500 runs for each of four fault scenarios and through comparison with a conventional (proportional−integral) feedback control law. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071548i Exemplaires
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Titre : Continuous biosorption in rotating packed-bed contactor Type de document : texte imprimé Auteurs : Aivi Das, Auteur ; Avijit Bhowal, Auteur ; Siddhartha Datta, Auteur Année de publication : 2008 Article en page(s) : p. 4230–4235 Note générale : Bibliogr. p. 4235 Langues : Anglais (eng) Mots-clés : Continuous biosorption Rotating packed-bed contactor Copper(II) ion adsorption Résumé : Biosorption process has been studied in fixed-bed contactors where terrestrial gravity dictates attainable mass transfer rates. This work explored the mass transfer characteristics of continuous biosorption under centrifugal acceleration (many times earth’s gravity) in a rotating packed-bed (RPB) contactor. The system studied was copper(II) ion adsorption on the packing of the contactor constituted by scales of Catla catla fish. Experiments were performed by continuously recycling a fixed volume of solution through the bed. The uptake of copper by the biosorbent increases with centrifugal force and liquid flow rate, but compaction of the bed negates the advantages of using high values of these. A low-packing-density bed demonstrated comparable efficiency in adsorbing copper as a bed nearly twice its packing density. Mass transfer rate per unit volume of packed bed was enhanced in the RPB by about 2.4 times compared to the fixed bed. A simple mass transfer model predicted the continuous biosorption experimental data in RPB fairly well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070679g
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4230–4235[article] Continuous biosorption in rotating packed-bed contactor [texte imprimé] / Aivi Das, Auteur ; Avijit Bhowal, Auteur ; Siddhartha Datta, Auteur . - 2008 . - p. 4230–4235.
Bibliogr. p. 4235
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4230–4235
Mots-clés : Continuous biosorption Rotating packed-bed contactor Copper(II) ion adsorption Résumé : Biosorption process has been studied in fixed-bed contactors where terrestrial gravity dictates attainable mass transfer rates. This work explored the mass transfer characteristics of continuous biosorption under centrifugal acceleration (many times earth’s gravity) in a rotating packed-bed (RPB) contactor. The system studied was copper(II) ion adsorption on the packing of the contactor constituted by scales of Catla catla fish. Experiments were performed by continuously recycling a fixed volume of solution through the bed. The uptake of copper by the biosorbent increases with centrifugal force and liquid flow rate, but compaction of the bed negates the advantages of using high values of these. A low-packing-density bed demonstrated comparable efficiency in adsorbing copper as a bed nearly twice its packing density. Mass transfer rate per unit volume of packed bed was enhanced in the RPB by about 2.4 times compared to the fixed bed. A simple mass transfer model predicted the continuous biosorption experimental data in RPB fairly well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070679g Exemplaires
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Titre : Synthesis and modeling of charged ultrafiltration membranes of poly(styrene-co-divinyl benzene) for the separation of chromium(VI) Type de document : texte imprimé Auteurs : Sonny Sachdeva, Auteur ; Anil Kumar, Auteur Année de publication : 2008 Article en page(s) : p. 4236–4250 Note générale : Bibliogr. p. 4249-4250 Langues : Anglais (eng) Mots-clés : Polystyrene composite membrane Gas-phase nitration Amination Quaternization Chromium(VI) Résumé : A ceramic supported cross-linked polystyrene (PS) composite membrane has been prepared from its monomers using a dual initiator system, and it has been chemically modified by gas-phase nitration (using NOx), amination using hydrazine hydrate, and quaternization using dichloroethane and triethylamine. The membranes (unmodified, aminated, and quaternized) have been used to study the rejection of chromium(VI) as a function of pressure, concentration, and pH of the feed solution, which was observed to be >90%. The experimental results have been fitted using a space charge model (SCM) to obtain the membrane wall potential and membrane surface concentration. The transport through the membrane capillaries has been described by a two-dimensional model, using the Nernst−Planck equation for ion transport, the Navier−Stokes equation to describe the flow, and the Poisson−Boltzmann equation for the radial distribution of potential. A semianalytical series solution to the highly nonlinear Poisson−Boltzmann equation has been developed, to reduce the computational time required to solve the set of coupled differential equations. The effective wall potential was determined to be 85.95 and 78.7 mV for the quaternized and aminated membranes, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070730g
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4236–4250[article] Synthesis and modeling of charged ultrafiltration membranes of poly(styrene-co-divinyl benzene) for the separation of chromium(VI) [texte imprimé] / Sonny Sachdeva, Auteur ; Anil Kumar, Auteur . - 2008 . - p. 4236–4250.
Bibliogr. p. 4249-4250
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4236–4250
Mots-clés : Polystyrene composite membrane Gas-phase nitration Amination Quaternization Chromium(VI) Résumé : A ceramic supported cross-linked polystyrene (PS) composite membrane has been prepared from its monomers using a dual initiator system, and it has been chemically modified by gas-phase nitration (using NOx), amination using hydrazine hydrate, and quaternization using dichloroethane and triethylamine. The membranes (unmodified, aminated, and quaternized) have been used to study the rejection of chromium(VI) as a function of pressure, concentration, and pH of the feed solution, which was observed to be >90%. The experimental results have been fitted using a space charge model (SCM) to obtain the membrane wall potential and membrane surface concentration. The transport through the membrane capillaries has been described by a two-dimensional model, using the Nernst−Planck equation for ion transport, the Navier−Stokes equation to describe the flow, and the Poisson−Boltzmann equation for the radial distribution of potential. A semianalytical series solution to the highly nonlinear Poisson−Boltzmann equation has been developed, to reduce the computational time required to solve the set of coupled differential equations. The effective wall potential was determined to be 85.95 and 78.7 mV for the quaternized and aminated membranes, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070730g Exemplaires
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Titre : Theoretical analysis of the adsorption effect on kinetic resolution of racemates catalyzed by immobilized enzymes in a batch reactor Type de document : texte imprimé Auteurs : Hongwei Yu, Auteur ; Chi Bun Ching, Auteur Année de publication : 2008 Article en page(s) : p. 4251–4255 Note générale : Bibliogr. p. 4255 Langues : Anglais (eng) Mots-clés : Adsorption Kinetic resolution Racemate catalyzed Résumé : Adsorption, a typical physical phenomenon, always neglected in the kinetic resolution of the racemate catalyzed by enzymes immobilized on the porous solid support, was theoretically analyzed. A concept that the adsorption effect plays an important role to affect the superficial performance of the enzyme which is often applied to evaluate the performance of the enzyme was described. Adsorption intensity, or so-called mass equilibrium constant (K), is the most important factor to affect the performance of the enzyme compared with adsorption rate coefficient (k) and adsorption equilibrium (adsorption isotherm) if the solid support with chiral selectivity is applied. The conclusion can be drawn that the solid support with a weak adsorption effect on the racemate may favorite the enzyme to exhibit a good performance in the kinetic resolution of the racemate. The adsorption phenomenon should be considered as an explanation to the performance changing of the enzyme after immobilized. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071300t
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4251–4255[article] Theoretical analysis of the adsorption effect on kinetic resolution of racemates catalyzed by immobilized enzymes in a batch reactor [texte imprimé] / Hongwei Yu, Auteur ; Chi Bun Ching, Auteur . - 2008 . - p. 4251–4255.
Bibliogr. p. 4255
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4251–4255
Mots-clés : Adsorption Kinetic resolution Racemate catalyzed Résumé : Adsorption, a typical physical phenomenon, always neglected in the kinetic resolution of the racemate catalyzed by enzymes immobilized on the porous solid support, was theoretically analyzed. A concept that the adsorption effect plays an important role to affect the superficial performance of the enzyme which is often applied to evaluate the performance of the enzyme was described. Adsorption intensity, or so-called mass equilibrium constant (K), is the most important factor to affect the performance of the enzyme compared with adsorption rate coefficient (k) and adsorption equilibrium (adsorption isotherm) if the solid support with chiral selectivity is applied. The conclusion can be drawn that the solid support with a weak adsorption effect on the racemate may favorite the enzyme to exhibit a good performance in the kinetic resolution of the racemate. The adsorption phenomenon should be considered as an explanation to the performance changing of the enzyme after immobilized. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071300t Exemplaires
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Titre : Modeling of effect of pH on mass transfer of copper(II) extraction by hollow fiber renewal liquid membrane Type de document : texte imprimé Auteurs : Zhongqi Ren, Auteur ; Zhang, Weidong, Auteur ; Yuan Dai, Auteur ; Yanqiang Yang, Auteur Année de publication : 2008 Article en page(s) : p. 4256–4262 Note générale : Bibliogr. p. 4262 Langues : Anglais (eng) Mots-clés : Copper extraction PH -- Mass transfer Acetate ion Résumé : In this paper, the effects of pH on the mass transfer of copper extraction with hollow fiber renewal liquid membrane (HFRLM), which is a new type of liquid membrane system based on the surface renewal theory, were investigated. The system of CuSO4 in acetate buffer solution + D2EHPA in kerosene + acidic aqueous solutions was used to study the effects of pH and acetate ion concentration in the feed phase and type and acidity of the stripping phase on the mass transfer performance of the HFRLM process. Results showed that the mass transfer flux and removal efficiency of copper increase with increasing pH in the feed phase, reach a maximum value at pH of 4.44, and then decrease; an addition of acetate buffer solution at a low acetate ion concentration in the feed phase is enough for maintaining the higher mass transfer flux and removal efficiency in the HFRLM process. The influence of the stripping phase on the mass transfer performance of the HFRLM process is weak in our ranges studied. The stripping phase at a low hydrogen concentration is enough for the extraction of copper by HFRLM. The mass transfer fluxes of copper ions from feed solutions with different stripping acids followed the order: Cl− > PO43− > SO42− > NO3−. And, a detailed mathematical model was developed based on the surface renewal theory. The calculated results have good agreement with experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0714798
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4256–4262[article] Modeling of effect of pH on mass transfer of copper(II) extraction by hollow fiber renewal liquid membrane [texte imprimé] / Zhongqi Ren, Auteur ; Zhang, Weidong, Auteur ; Yuan Dai, Auteur ; Yanqiang Yang, Auteur . - 2008 . - p. 4256–4262.
Bibliogr. p. 4262
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4256–4262
Mots-clés : Copper extraction PH -- Mass transfer Acetate ion Résumé : In this paper, the effects of pH on the mass transfer of copper extraction with hollow fiber renewal liquid membrane (HFRLM), which is a new type of liquid membrane system based on the surface renewal theory, were investigated. The system of CuSO4 in acetate buffer solution + D2EHPA in kerosene + acidic aqueous solutions was used to study the effects of pH and acetate ion concentration in the feed phase and type and acidity of the stripping phase on the mass transfer performance of the HFRLM process. Results showed that the mass transfer flux and removal efficiency of copper increase with increasing pH in the feed phase, reach a maximum value at pH of 4.44, and then decrease; an addition of acetate buffer solution at a low acetate ion concentration in the feed phase is enough for maintaining the higher mass transfer flux and removal efficiency in the HFRLM process. The influence of the stripping phase on the mass transfer performance of the HFRLM process is weak in our ranges studied. The stripping phase at a low hydrogen concentration is enough for the extraction of copper by HFRLM. The mass transfer fluxes of copper ions from feed solutions with different stripping acids followed the order: Cl− > PO43− > SO42− > NO3−. And, a detailed mathematical model was developed based on the surface renewal theory. The calculated results have good agreement with experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0714798 Exemplaires
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Titre : COSMO-RS-based extractant screening for phenol extraction as model system Type de document : texte imprimé Auteurs : Bernhard Burghoff, Auteur ; Earl L. V. Goetheer, Auteur ; Andre B. de Haan, Auteur Année de publication : 2008 Article en page(s) : p. 4263–4269 Note générale : Bibliogr. p. 4268-4269 Langues : Anglais (eng) Mots-clés : Phenol extraction COSMO-RS Molecular variations Résumé : The focus of this investigation is the development of a fast and reliable extractant screening approach. Phenol extraction is selected as the model process. A quantum chemical conductor-like screening model for real solvents (COSMO-RS) is combined with molecular design considerations. For this purpose, phenol distribution coefficients KD of known phenol extractants are determined experimentally and in silico. Molecular variations of different extractants are tested concerning their effect on KD to facilitate extractant improvement. It is shown that KD depends on the molecular structure of the extractant. Calculations with COSMO-RS provide a qualitative trend of simulated extraction efficiency and even a quantitatively correct description of KD. The simulations for alkylamine components are, however, not accurate, which is a well-known problem. During the screening process, phosphorus containing aliphatic substances, especially the trialkylphosphine oxide compound Cyanex 923, were determined as the most promising phenol extractants, which agrees with the state of the art. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie7017405
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4263–4269[article] COSMO-RS-based extractant screening for phenol extraction as model system [texte imprimé] / Bernhard Burghoff, Auteur ; Earl L. V. Goetheer, Auteur ; Andre B. de Haan, Auteur . - 2008 . - p. 4263–4269.
Bibliogr. p. 4268-4269
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4263–4269
Mots-clés : Phenol extraction COSMO-RS Molecular variations Résumé : The focus of this investigation is the development of a fast and reliable extractant screening approach. Phenol extraction is selected as the model process. A quantum chemical conductor-like screening model for real solvents (COSMO-RS) is combined with molecular design considerations. For this purpose, phenol distribution coefficients KD of known phenol extractants are determined experimentally and in silico. Molecular variations of different extractants are tested concerning their effect on KD to facilitate extractant improvement. It is shown that KD depends on the molecular structure of the extractant. Calculations with COSMO-RS provide a qualitative trend of simulated extraction efficiency and even a quantitatively correct description of KD. The simulations for alkylamine components are, however, not accurate, which is a well-known problem. During the screening process, phosphorus containing aliphatic substances, especially the trialkylphosphine oxide compound Cyanex 923, were determined as the most promising phenol extractants, which agrees with the state of the art. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie7017405 Exemplaires
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Titre : Temperature effects on gas dispersion and solid suspension in a three-phase stirred reactor Type de document : texte imprimé Auteurs : Yuyun Bao, Auteur ; Lei Chen, Auteur ; Zhengming Gao, Auteur ; Xinnian Zhang, Auteur Année de publication : 2008 Article en page(s) : p. 4270–4277 Note générale : Bibliogr. p. 4277 Langues : Anglais (eng) Mots-clés : Gas dispersion Solid suspension Impeller combination Stirred tank Résumé : Temperature effects on gas dispersion and solid suspension have been investigated in a fully baffled, dished-base stirred tank of 0.48 m diameter holding 0.145 m3 of liquid stirred by a triple-impeller combination. The impeller combination consisted of a half-elliptical disk turbine below two up-pumping wide-blade hydrofoils (WHU). This configuration is efficient for both gas dispersion and solid suspension. Power consumption, gas holdup, and the critical off-bottom just-suspension agitation speed have been measured at solid concentrations up to 21 vol % at six different temperatures ranging from 24 to 95 °C in increments of about 14 °C. The results confirm significant effects of temperature on the hydrodynamic characteristics. The relative power demand increases somewhat at increased temperature, although this effect is less when more solids are present. Gas holdup decreases significantly at higher temperatures, again an effect that is reduced at higher solid concentrations. The critical impeller speed for off-bottom just suspension (NJSG) increases with increasing gas rates over the whole temperature range of this work, though the effect of the gas rate on NJSG is less at higher temperatures. The effects of the temperature on power consumption, gas holdup, and NJSG have been quantified in a series of correlations that are relevant for the design and operation of hot-sparged three-phase reactors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701726e
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4270–4277[article] Temperature effects on gas dispersion and solid suspension in a three-phase stirred reactor [texte imprimé] / Yuyun Bao, Auteur ; Lei Chen, Auteur ; Zhengming Gao, Auteur ; Xinnian Zhang, Auteur . - 2008 . - p. 4270–4277.
Bibliogr. p. 4277
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4270–4277
Mots-clés : Gas dispersion Solid suspension Impeller combination Stirred tank Résumé : Temperature effects on gas dispersion and solid suspension have been investigated in a fully baffled, dished-base stirred tank of 0.48 m diameter holding 0.145 m3 of liquid stirred by a triple-impeller combination. The impeller combination consisted of a half-elliptical disk turbine below two up-pumping wide-blade hydrofoils (WHU). This configuration is efficient for both gas dispersion and solid suspension. Power consumption, gas holdup, and the critical off-bottom just-suspension agitation speed have been measured at solid concentrations up to 21 vol % at six different temperatures ranging from 24 to 95 °C in increments of about 14 °C. The results confirm significant effects of temperature on the hydrodynamic characteristics. The relative power demand increases somewhat at increased temperature, although this effect is less when more solids are present. Gas holdup decreases significantly at higher temperatures, again an effect that is reduced at higher solid concentrations. The critical impeller speed for off-bottom just suspension (NJSG) increases with increasing gas rates over the whole temperature range of this work, though the effect of the gas rate on NJSG is less at higher temperatures. The effects of the temperature on power consumption, gas holdup, and NJSG have been quantified in a series of correlations that are relevant for the design and operation of hot-sparged three-phase reactors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701726e Exemplaires
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Titre : Prediction of water solubility in biodiesel with the CPA equation of state Type de document : texte imprimé Auteurs : M. B. Oliveira, Auteur ; F. R. Varanda, Auteur ; I. M. Marrucho, Auteur ; A. J. Queimada, Auteur Année de publication : 2008 Article en page(s) : p. 4278–4285 Note générale : Bibliogr. p. 4284-4285 Langues : Anglais (eng) Mots-clés : Biodiesel Water solubility Cubic-plus-association equation of state Résumé : The recent growing interest in biofuels is due to the continuous increase in crude oil prices, limited resources of fossil energies, and environmental concerns. In what concerns road transportation, biodiesel is being considered a good alternative to conventional diesels. It consists of a blend of fatty acid esters, and its production and formulation needs to be optimized to ensure that the fuel quality complies with the legal standards. Although in various aspects biodiesel is superior to conventional diesel, it also poses some problems such as its poor behavior at low temperatures and higher hygroscopicity than conventional diesel. Up to now, little information is available about the water solubility in fatty acid methyl and ethyl esters and commercial biodiesels. To overcome this lack of data, water solubility measurements were carried out for 11 pure esters and 6 biodiesels in the temperature range 288.15−323.15 K. This new experimental data was successfully modeled with the cubic-plus-association (CPA) equation of state with global average deviations inferior to 7% for the ester systems, and predictions with deviations of 16% for commercial biodiesels were achieved. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800018x
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4278–4285[article] Prediction of water solubility in biodiesel with the CPA equation of state [texte imprimé] / M. B. Oliveira, Auteur ; F. R. Varanda, Auteur ; I. M. Marrucho, Auteur ; A. J. Queimada, Auteur . - 2008 . - p. 4278–4285.
Bibliogr. p. 4284-4285
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4278–4285
Mots-clés : Biodiesel Water solubility Cubic-plus-association equation of state Résumé : The recent growing interest in biofuels is due to the continuous increase in crude oil prices, limited resources of fossil energies, and environmental concerns. In what concerns road transportation, biodiesel is being considered a good alternative to conventional diesels. It consists of a blend of fatty acid esters, and its production and formulation needs to be optimized to ensure that the fuel quality complies with the legal standards. Although in various aspects biodiesel is superior to conventional diesel, it also poses some problems such as its poor behavior at low temperatures and higher hygroscopicity than conventional diesel. Up to now, little information is available about the water solubility in fatty acid methyl and ethyl esters and commercial biodiesels. To overcome this lack of data, water solubility measurements were carried out for 11 pure esters and 6 biodiesels in the temperature range 288.15−323.15 K. This new experimental data was successfully modeled with the cubic-plus-association (CPA) equation of state with global average deviations inferior to 7% for the ester systems, and predictions with deviations of 16% for commercial biodiesels were achieved. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800018x Exemplaires
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Titre : An inexpensive, digital instrument for surface tension, interfacial tension, and density determination Type de document : texte imprimé Auteurs : Darren L. Williams, Auteur ; Casie L. Jupe, Auteur ; Karl D. Kuklenz, Auteur Année de publication : 2008 Article en page(s) : p. 4286–4289 Note générale : Bibliogr. p. 4289 Langues : Anglais (eng) Mots-clés : Digital ring tensiometer Carver press Water-recirculation bath Résumé : This article outlines the construction of a large-capacity, digital ring tensiometer, using common laboratory equipment, and reports the validation of this instrument against National Institutes of Science and Technology (NIST) data. A Carver press is used as a hydraulically controlled platform that raises and lowers the temperature-controlled jacketed flask that contains the test solutions. The upper platen of the press supports a four-decimal-place scale with a Pt−Ir ring hanging from the underscale hook. The scale measures the pull on the ring as the solution interface is lowered by the press. The force measurements are transferred to a personal computer (PC) via RS-232 communications. Temperature is controlled via a water-recirculation bath. The experimental surface tension measurements for toluene and water at 13 different temperatures were, on average, 2.7% larger than the NIST data. The 25 °C surface tension measurements for water, 2-butanone, ethyl ethanoate, and toluene were, on average, 1.1% larger than those calculated using the Hansen solubility parameters. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800211a
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4286–4289[article] An inexpensive, digital instrument for surface tension, interfacial tension, and density determination [texte imprimé] / Darren L. Williams, Auteur ; Casie L. Jupe, Auteur ; Karl D. Kuklenz, Auteur . - 2008 . - p. 4286–4289.
Bibliogr. p. 4289
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4286–4289
Mots-clés : Digital ring tensiometer Carver press Water-recirculation bath Résumé : This article outlines the construction of a large-capacity, digital ring tensiometer, using common laboratory equipment, and reports the validation of this instrument against National Institutes of Science and Technology (NIST) data. A Carver press is used as a hydraulically controlled platform that raises and lowers the temperature-controlled jacketed flask that contains the test solutions. The upper platen of the press supports a four-decimal-place scale with a Pt−Ir ring hanging from the underscale hook. The scale measures the pull on the ring as the solution interface is lowered by the press. The force measurements are transferred to a personal computer (PC) via RS-232 communications. Temperature is controlled via a water-recirculation bath. The experimental surface tension measurements for toluene and water at 13 different temperatures were, on average, 2.7% larger than the NIST data. The 25 °C surface tension measurements for water, 2-butanone, ethyl ethanoate, and toluene were, on average, 1.1% larger than those calculated using the Hansen solubility parameters. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800211a Exemplaires
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Titre : Liquid-continuous distillation Type de document : texte imprimé Auteurs : A. Frank Seibert, Auteur ; J. Christopher Lewis, Auteur ; James R. Fair, Auteur Année de publication : 2008 Article en page(s) : p. 4290–4294 Note générale : Bibliogr. p. 4294 Langues : Anglais (eng) Mots-clés : Bubble columns Distillation Gas rates Résumé : Bubble columns, in which a gas is passed up through a head of liquid, have been limited to very low superficial gas velocities. Higher rates, such as those used in conventional distillation columns, have not previously been explored. In fact, higher gas rates have been thought to lead to dangerous operating conditions. In this paper, new data for high gas rates, under distillation conditions and at a semiworks scale, are presented for liquid-continuous operations. Both sieve trays and structured packing have been used as internals. Mass transfer and hydraulic data are included. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0709133
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4290–4294[article] Liquid-continuous distillation [texte imprimé] / A. Frank Seibert, Auteur ; J. Christopher Lewis, Auteur ; James R. Fair, Auteur . - 2008 . - p. 4290–4294.
Bibliogr. p. 4294
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4290–4294
Mots-clés : Bubble columns Distillation Gas rates Résumé : Bubble columns, in which a gas is passed up through a head of liquid, have been limited to very low superficial gas velocities. Higher rates, such as those used in conventional distillation columns, have not previously been explored. In fact, higher gas rates have been thought to lead to dangerous operating conditions. In this paper, new data for high gas rates, under distillation conditions and at a semiworks scale, are presented for liquid-continuous operations. Both sieve trays and structured packing have been used as internals. Mass transfer and hydraulic data are included. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0709133 Exemplaires
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