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Vol. 47 N° 13 - Juillet 2008 [texte imprimé] . - 2008 . - p. 4295–4560 : ill. ; 28 cm. Chemical engineering Langues : Anglais (eng)
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Ajouter le résultat dans votre panierHoneycomb CuO/Al2O3/cordierite catalyst for selective catalytic reduction of NO by NH3 / Junhua Su in Industrial & engineering chemistry research, Vol. 47 N° 13 (Juillet 2008)
Titre : Honeycomb CuO/Al2O3/cordierite catalyst for selective catalytic reduction of NO by NH3 : effect of Al2O3 coating Type de document : texte imprimé Auteurs : Junhua Su, Auteur ; Qingya Liu, Auteur ; Zhenyu Liu, Auteur ; Zhanggen Huang, Auteur Année de publication : 2008 Article en page(s) : p. 4295–4301 Note générale : Bibliogr. p. 4301 Langues : Anglais (eng) Mots-clés : Al2O3-coated cordierite Honeycomb Viscosity Grain size Résumé : Al2O3-coated cordierite has been widely used as a catalyst’s support. In this work, three Al2O3 precursors or alumina sols are studied to understand the effect of type, viscosity, and grain size of the sols and Cl− on properties and SCR activities of honeycomb CuO/Al2O3/cordierite catalysts. X-ray diffraction (XRD), N2 adsorption, scanning electron microscopy and energy dispersive X-ray (SEM-EDX) techniques are used for analyses. Results show that the viscosity and average grain size of the sol have significant influences on the amount and stability of the Al2O3 coating. The sol synthesized from AlCl3 and aluminum is the best among the three sols in terms of less coating cycle, stability of the coating, and selective catalytic reduction (SCR) activity. Cl1− introduced in preparation must be washed out because it deactivates the SCR activity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800105p
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4295–4301[article] Honeycomb CuO/Al2O3/cordierite catalyst for selective catalytic reduction of NO by NH3 : effect of Al2O3 coating [texte imprimé] / Junhua Su, Auteur ; Qingya Liu, Auteur ; Zhenyu Liu, Auteur ; Zhanggen Huang, Auteur . - 2008 . - p. 4295–4301.
Bibliogr. p. 4301
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4295–4301
Mots-clés : Al2O3-coated cordierite Honeycomb Viscosity Grain size Résumé : Al2O3-coated cordierite has been widely used as a catalyst’s support. In this work, three Al2O3 precursors or alumina sols are studied to understand the effect of type, viscosity, and grain size of the sols and Cl− on properties and SCR activities of honeycomb CuO/Al2O3/cordierite catalysts. X-ray diffraction (XRD), N2 adsorption, scanning electron microscopy and energy dispersive X-ray (SEM-EDX) techniques are used for analyses. Results show that the viscosity and average grain size of the sol have significant influences on the amount and stability of the Al2O3 coating. The sol synthesized from AlCl3 and aluminum is the best among the three sols in terms of less coating cycle, stability of the coating, and selective catalytic reduction (SCR) activity. Cl1− introduced in preparation must be washed out because it deactivates the SCR activity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800105p Exemplaires
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Titre : Effects of process variables on poly-aluminum chloride (PAC)-rosin sizing performance under neutral papermaking conditions Type de document : texte imprimé Auteurs : Yahya Hamzeh, Auteur ; Mohammad Hassan Ekhtera, Auteur ; Martin A. Hubbe, Auteur ; Soheila Izadyar, Auteur Année de publication : 2008 Article en page(s) : p. 4302–4307 Note générale : Bibliogr. p. 4307 Langues : Anglais (eng) Mots-clés : Poly-aluminum chloride-rosin Sizing variables Résumé : The effects of process variables, including poly-aluminum chloride (PAC) and rosin levels and equilibration time on PAC−rosin sizing performance, were investigated for three alternative sizing processes, include conventional, reverse sizing, and premixing under neutral papermaking conditions. The individual and interaction effects of sizing variables were determined. It was found that, in contrast to conventional sizing, the sizing efficiency increased with increasing equilibration time when reverse and premixing processes were used for the sizing treatment. In both processes, increasing equilibration time can lead to potential savings in PAC or rosin. Finally, the optimum conditions for more cost-effective sizing were determined for the three sizing processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800107x
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4302–4307[article] Effects of process variables on poly-aluminum chloride (PAC)-rosin sizing performance under neutral papermaking conditions [texte imprimé] / Yahya Hamzeh, Auteur ; Mohammad Hassan Ekhtera, Auteur ; Martin A. Hubbe, Auteur ; Soheila Izadyar, Auteur . - 2008 . - p. 4302–4307.
Bibliogr. p. 4307
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4302–4307
Mots-clés : Poly-aluminum chloride-rosin Sizing variables Résumé : The effects of process variables, including poly-aluminum chloride (PAC) and rosin levels and equilibration time on PAC−rosin sizing performance, were investigated for three alternative sizing processes, include conventional, reverse sizing, and premixing under neutral papermaking conditions. The individual and interaction effects of sizing variables were determined. It was found that, in contrast to conventional sizing, the sizing efficiency increased with increasing equilibration time when reverse and premixing processes were used for the sizing treatment. In both processes, increasing equilibration time can lead to potential savings in PAC or rosin. Finally, the optimum conditions for more cost-effective sizing were determined for the three sizing processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800107x Exemplaires
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Titre : Stochastic simulation and single events kinetic modeling : application to olefin oligomerization Type de document : texte imprimé Auteurs : Javad R. Shahrouzi, Auteur ; Denis Guillaume, Auteur ; Pierre Rouchon, Auteur ; Patrick Da Costa, Auteur Année de publication : 2008 Article en page(s) : p. 4308–4316 Note générale : Bibliogr. p. 4315-4316 Langues : Anglais (eng) Mots-clés : Stochastic tools Single event kinetic modeling Oligomerization network Résumé : In order to handle a tractable network for complex reaction systems such as oligomerization, stochastic tools are applied to reduce the reaction mechanism. The particularity of this work is that quantitative single event kinetic modeling constants are used to generate a network which correctly describes the dynamic behavior of the studied reacting system. By using the stochastic method, which is based on a probabilistic approach, we can avoid the generation of improbable reaction paths in order to reduce the network expansion. Comparison with a classical limited network shows that the proposed network generation technique can be more reliable. Alongside, the stochastic simulation algorithm can be used as a method of simulation instead of the deterministic method because of the huge size of the oligomerization network. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071215l
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4308–4316[article] Stochastic simulation and single events kinetic modeling : application to olefin oligomerization [texte imprimé] / Javad R. Shahrouzi, Auteur ; Denis Guillaume, Auteur ; Pierre Rouchon, Auteur ; Patrick Da Costa, Auteur . - 2008 . - p. 4308–4316.
Bibliogr. p. 4315-4316
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4308–4316
Mots-clés : Stochastic tools Single event kinetic modeling Oligomerization network Résumé : In order to handle a tractable network for complex reaction systems such as oligomerization, stochastic tools are applied to reduce the reaction mechanism. The particularity of this work is that quantitative single event kinetic modeling constants are used to generate a network which correctly describes the dynamic behavior of the studied reacting system. By using the stochastic method, which is based on a probabilistic approach, we can avoid the generation of improbable reaction paths in order to reduce the network expansion. Comparison with a classical limited network shows that the proposed network generation technique can be more reliable. Alongside, the stochastic simulation algorithm can be used as a method of simulation instead of the deterministic method because of the huge size of the oligomerization network. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071215l Exemplaires
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Titre : Kinetic modeling of propene hydroformylation with Rh/TPP and Rh/CHDPP catalysts Type de document : texte imprimé Auteurs : Andreas Bernas, Auteur ; Paivi Maki-Arvela, Auteur ; Juha Lehtonen, Auteur ; Tapio Salmi, Auteur Année de publication : 2008 Article en page(s) : p. 4317–4324 Note générale : Bibliogr. p. 4324 Langues : Anglais (eng) Mots-clés : Propene hydroformylation Solubility Rhodium/triphenylphosphine catalysts Résumé : Hydroformylation of propene to isobutyraldehyde and n-butyraldehyde was studied in the kinetic regime in a semibatch stainless steel reactor at 70−115 °C and 1−15 bar overpressure in 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate solvent with rhodium/cyclohexyl diphenylphosphine (Rh/CHDPP) and rhodium/triphenylphosphine (Rh/TPP) catalysts. The influence of process parameters such as Rh concentration (50−250 ppm), ligand mass fraction (0−10 wt %), H2-to-CO ratio, and stirring power was investigated and the influence of solvent concentration was studied by using mixtures of valeraldehyde and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate as solvent. The solubility of propene, H2, and CO in 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate was measured in the same reactor. Rh/CHDPP showed lower normal/isometric aldehyde ratio (n/i) than Rh/TPP. The rate was temperature and pressure dependent, while the Rh concentration or syngas composition did not have any significant impact. The n/i ratio was always independent of the conversion, but dependent on the ligand concentration: higher ligand concentration promoted isobutyraldehyde formation. Based on experimentally recorded kinetic data, a stoichiometric scheme was proposed and parameters of power-law rate models were determined by using nonlinear regression analysis. The experimental system was described as a perfectly mixed gas−liquid reactor. As showed by sensitivity analysis, the kinetic parameters were well identified and physically reasonable and they were in accordance with qualitative observations. The kinetic models with a degree of explanation of more than 0.9 described the formation of the products with satisfying accuracy. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071401r
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4317–4324[article] Kinetic modeling of propene hydroformylation with Rh/TPP and Rh/CHDPP catalysts [texte imprimé] / Andreas Bernas, Auteur ; Paivi Maki-Arvela, Auteur ; Juha Lehtonen, Auteur ; Tapio Salmi, Auteur . - 2008 . - p. 4317–4324.
Bibliogr. p. 4324
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4317–4324
Mots-clés : Propene hydroformylation Solubility Rhodium/triphenylphosphine catalysts Résumé : Hydroformylation of propene to isobutyraldehyde and n-butyraldehyde was studied in the kinetic regime in a semibatch stainless steel reactor at 70−115 °C and 1−15 bar overpressure in 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate solvent with rhodium/cyclohexyl diphenylphosphine (Rh/CHDPP) and rhodium/triphenylphosphine (Rh/TPP) catalysts. The influence of process parameters such as Rh concentration (50−250 ppm), ligand mass fraction (0−10 wt %), H2-to-CO ratio, and stirring power was investigated and the influence of solvent concentration was studied by using mixtures of valeraldehyde and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate as solvent. The solubility of propene, H2, and CO in 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate was measured in the same reactor. Rh/CHDPP showed lower normal/isometric aldehyde ratio (n/i) than Rh/TPP. The rate was temperature and pressure dependent, while the Rh concentration or syngas composition did not have any significant impact. The n/i ratio was always independent of the conversion, but dependent on the ligand concentration: higher ligand concentration promoted isobutyraldehyde formation. Based on experimentally recorded kinetic data, a stoichiometric scheme was proposed and parameters of power-law rate models were determined by using nonlinear regression analysis. The experimental system was described as a perfectly mixed gas−liquid reactor. As showed by sensitivity analysis, the kinetic parameters were well identified and physically reasonable and they were in accordance with qualitative observations. The kinetic models with a degree of explanation of more than 0.9 described the formation of the products with satisfying accuracy. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071401r Exemplaires
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Titre : Wet air oxidation of benzene Type de document : texte imprimé Auteurs : Basim A. Abussaud, Auteur ; Nilgun Ulkem, Auteur ; Dimitrios Berk, Auteur ; George J. Kubes, Auteur Année de publication : 2008 Article en page(s) : p. 4325–4331 Note générale : Bibliogr. p. 4330-4331 Langues : Anglais (eng) Mots-clés : Benzene Wet air oxidation Résumé : The wet air oxidation of benzene has been studied in a 1.24 L stainless steel autoclave at a temperature in the range of 190−260 °C. The oxygen partial pressure was varied from 0.69 to 1.72 MPa. The initial C6H6 concentration was 5.63 mmol/L. The influence of the pH was studied, and the main reaction intermediates were determined. It was found that the temperature has a great influence on the wet air oxidation of benzene. The effect of the oxygen partial pressure was significant only at the beginning of the reaction. Decrease of the initial pH of the reaction results in a considerable increase in the benzene degradation rate, especially at the lower temperature. The main intermediates were found to be acetic acid and formic acid. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800162j
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4325–4331[article] Wet air oxidation of benzene [texte imprimé] / Basim A. Abussaud, Auteur ; Nilgun Ulkem, Auteur ; Dimitrios Berk, Auteur ; George J. Kubes, Auteur . - 2008 . - p. 4325–4331.
Bibliogr. p. 4330-4331
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4325–4331
Mots-clés : Benzene Wet air oxidation Résumé : The wet air oxidation of benzene has been studied in a 1.24 L stainless steel autoclave at a temperature in the range of 190−260 °C. The oxygen partial pressure was varied from 0.69 to 1.72 MPa. The initial C6H6 concentration was 5.63 mmol/L. The influence of the pH was studied, and the main reaction intermediates were determined. It was found that the temperature has a great influence on the wet air oxidation of benzene. The effect of the oxygen partial pressure was significant only at the beginning of the reaction. Decrease of the initial pH of the reaction results in a considerable increase in the benzene degradation rate, especially at the lower temperature. The main intermediates were found to be acetic acid and formic acid. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800162j Exemplaires
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Titre : Multiscale simulation of the indirect internal reforming unit (IIR) in a molten carbonate fuel cell (MCFC) Type de document : texte imprimé Auteurs : Matthias Pfafferodt, Auteur ; Peter Heidebrecht, Auteur ; Kai Sundmacher, Auteur ; Uwe Würtenberger, Auteur Année de publication : 2008 Article en page(s) : p. 4332–4341 Note générale : Bibliogr. p. 4341 Langues : Anglais (eng) Mots-clés : Indirect internal reforming Heat transport Molten carbonate fuel cell Résumé : This paper studies the coupled mass and heat transport as well as the reactions in an indirect internal reforming (IIR) unit of a molten carbonate fuel cell (MCFC). The aims of the work are first to identify the dominating transport processes for a specific design. Because the temperature field is one major issue in MCFCs, the second aim is to predict the spatially distributed temperature field within the unit. In a first step, several variants of a microscale model, describing only a small detail of the IIR unit, are created. The governing equations and the boundary conditions of this model are given. The results of these simulations, especially the temperature and concentration distributions, are discussed. They show that the gas phase is divided into a reactive and a nonreactive zone in the actual design of the IIR and the reforming process is dominated by mass transfer between these zones. In a second step, a macroscale model of the entire IIR unit is presented. It considers a simplified geometry, but it incorporates the two gas zones identified by the microscale model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800290h
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4332–4341[article] Multiscale simulation of the indirect internal reforming unit (IIR) in a molten carbonate fuel cell (MCFC) [texte imprimé] / Matthias Pfafferodt, Auteur ; Peter Heidebrecht, Auteur ; Kai Sundmacher, Auteur ; Uwe Würtenberger, Auteur . - 2008 . - p. 4332–4341.
Bibliogr. p. 4341
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4332–4341
Mots-clés : Indirect internal reforming Heat transport Molten carbonate fuel cell Résumé : This paper studies the coupled mass and heat transport as well as the reactions in an indirect internal reforming (IIR) unit of a molten carbonate fuel cell (MCFC). The aims of the work are first to identify the dominating transport processes for a specific design. Because the temperature field is one major issue in MCFCs, the second aim is to predict the spatially distributed temperature field within the unit. In a first step, several variants of a microscale model, describing only a small detail of the IIR unit, are created. The governing equations and the boundary conditions of this model are given. The results of these simulations, especially the temperature and concentration distributions, are discussed. They show that the gas phase is divided into a reactive and a nonreactive zone in the actual design of the IIR and the reforming process is dominated by mass transfer between these zones. In a second step, a macroscale model of the entire IIR unit is presented. It considers a simplified geometry, but it incorporates the two gas zones identified by the microscale model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800290h Exemplaires
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Titre : Thermal decomposition kinetics of the aviation turbine fuel jet A Type de document : texte imprimé Auteurs : Jason A Widegren, Auteur ; Thomas J. Bruno, Auteur Année de publication : 2008 Article en page(s) : p. 4342–4348 Note générale : Bibliogr. p.4347-4348 Langues : Anglais (eng) Mots-clés : Aviation turbine fuel jet A Decomposition Kinetic data Résumé : As part of a large-scale thermophysical property measurement project, the global decomposition kinetics of the aviation turbine fuel Jet A was investigated. Decomposition reactions were performed at 375, 400, 425, and 450 °C in stainless steel ampule reactors. At each temperature, the extent of decomposition was determined as a function of time by gas chromatography. These data were used to derive global pseudo-first-order rate constants that approximate the overall decomposition rate of the mixture. Decomposition rate constants ranged from 5.9 × 10−6 s−1 at 375 °C to 4.4 × 10−4 s−1 at 450 °C. These rate constants are useful for planning property measurements at high temperatures. On the basis of the amount of time required for 1% of the sample to decompose (t0.01), we found that allowable instrument residence times ranged from about 0.5 h at 375 °C to less than 1 min at 450 °C. The kinetic data were also used to derive Arrhenius parameters of A = 4.1 × 1012 s−1 and Ea = 220 kJ·mol−1. In addition to the decomposition kinetics, we have also done a GC-MS analysis of the vapor phase that is produced during the thermal decomposition measurements. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8000666
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4342–4348[article] Thermal decomposition kinetics of the aviation turbine fuel jet A [texte imprimé] / Jason A Widegren, Auteur ; Thomas J. Bruno, Auteur . - 2008 . - p. 4342–4348.
Bibliogr. p.4347-4348
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4342–4348
Mots-clés : Aviation turbine fuel jet A Decomposition Kinetic data Résumé : As part of a large-scale thermophysical property measurement project, the global decomposition kinetics of the aviation turbine fuel Jet A was investigated. Decomposition reactions were performed at 375, 400, 425, and 450 °C in stainless steel ampule reactors. At each temperature, the extent of decomposition was determined as a function of time by gas chromatography. These data were used to derive global pseudo-first-order rate constants that approximate the overall decomposition rate of the mixture. Decomposition rate constants ranged from 5.9 × 10−6 s−1 at 375 °C to 4.4 × 10−4 s−1 at 450 °C. These rate constants are useful for planning property measurements at high temperatures. On the basis of the amount of time required for 1% of the sample to decompose (t0.01), we found that allowable instrument residence times ranged from about 0.5 h at 375 °C to less than 1 min at 450 °C. The kinetic data were also used to derive Arrhenius parameters of A = 4.1 × 1012 s−1 and Ea = 220 kJ·mol−1. In addition to the decomposition kinetics, we have also done a GC-MS analysis of the vapor phase that is produced during the thermal decomposition measurements. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8000666 Exemplaires
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Titre : Catalytic carbon dioxide reforming of methane to synthesis gas over activated carbon catalyst Type de document : texte imprimé Auteurs : Qilei Song, Auteur ; Rui Xiao, Auteur ; Yanbing Li, Auteur ; Laihong Shen, Auteur Année de publication : 2008 Article en page(s) : p. 4349–4357 Note générale : Bibliogr. p. 4357 Langues : Anglais (eng) Mots-clés : Methane Catalytic activity Kinetics Résumé : The catalytic activity and kinetic behavior of catalytic reforming of methane with carbon dioxide over activated carbon were investigated as a function of reaction temperature, gas hourly space velocity (GHSV), and partial pressures of CH4 and CO2. The CH4 and CO2 conversions were greatly influenced by the reaction temperature in the range of 850−1050 °C. The apparent activation energies for CH4 and CO2 consumption and CO and H2 production were 32.63 ± 1.06, 25.54 ± 1.79, 24.81 ± 3.06, and 32.99 ± 2.58 kcal/mol, respectively. The curves of reaction rates versus GHSV showed various trends at different temperatures and indicated 7500 mL/h·g-cat was sufficient for operation in the kinetic regime. The reaction rate of methane and carbon dioxide over activated carbon was affected significantly by the partial pressures. Under a higher CO2 pressure, the excess CO2 reacted with H2 through the reverse water−gas shift (RWGS) reaction. The predictions of the CH4 and CO2 reaction rates based on a semiexperimental formula fitted satisfactorily with the experiments data. The results of mass balance, BET, XRD, and SEM studies in the deactivation test indicated that the catalyst deactivation was mainly attributed to the carbon deposition and might be alleviated at high temperatures. On the basis of the experimental results and Langmuir−Hinshelwood mechanism in the literature, a reaction mechanism was proposed. The overall reaction pathway involves the adsorption and cracking of methane and CO2 adsorption and gasification with carbon cracked. The RWGS reaction occurs simultaneously. Overall, a derived semitheoretical kinetic equation satisfactorily predicted the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800117a
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4349–4357[article] Catalytic carbon dioxide reforming of methane to synthesis gas over activated carbon catalyst [texte imprimé] / Qilei Song, Auteur ; Rui Xiao, Auteur ; Yanbing Li, Auteur ; Laihong Shen, Auteur . - 2008 . - p. 4349–4357.
Bibliogr. p. 4357
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4349–4357
Mots-clés : Methane Catalytic activity Kinetics Résumé : The catalytic activity and kinetic behavior of catalytic reforming of methane with carbon dioxide over activated carbon were investigated as a function of reaction temperature, gas hourly space velocity (GHSV), and partial pressures of CH4 and CO2. The CH4 and CO2 conversions were greatly influenced by the reaction temperature in the range of 850−1050 °C. The apparent activation energies for CH4 and CO2 consumption and CO and H2 production were 32.63 ± 1.06, 25.54 ± 1.79, 24.81 ± 3.06, and 32.99 ± 2.58 kcal/mol, respectively. The curves of reaction rates versus GHSV showed various trends at different temperatures and indicated 7500 mL/h·g-cat was sufficient for operation in the kinetic regime. The reaction rate of methane and carbon dioxide over activated carbon was affected significantly by the partial pressures. Under a higher CO2 pressure, the excess CO2 reacted with H2 through the reverse water−gas shift (RWGS) reaction. The predictions of the CH4 and CO2 reaction rates based on a semiexperimental formula fitted satisfactorily with the experiments data. The results of mass balance, BET, XRD, and SEM studies in the deactivation test indicated that the catalyst deactivation was mainly attributed to the carbon deposition and might be alleviated at high temperatures. On the basis of the experimental results and Langmuir−Hinshelwood mechanism in the literature, a reaction mechanism was proposed. The overall reaction pathway involves the adsorption and cracking of methane and CO2 adsorption and gasification with carbon cracked. The RWGS reaction occurs simultaneously. Overall, a derived semitheoretical kinetic equation satisfactorily predicted the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800117a Exemplaires
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Titre : Reaction of NO2 with activated carbon at ambient temperature Type de document : texte imprimé Auteurs : Wei-Jun Zhang, Auteur ; Andrey Bagreev, Auteur ; Firooz Rasouli, Auteur Année de publication : 2008 Article en page(s) : p. 4358–4362 Note générale : Bibliogr. p. 4362 Langues : Anglais (eng) Mots-clés : NO2 Activated carbon Adsorption times Résumé : NO2 adsorption on activated carbons at ambient temperature was studied. The adsorbed species after various adsorption times were examined by analyzing the evolution of NO, NO2, CO, CO2, and O2 during thermal desorption. Emission of NO but not NO2 was observed during the early stage of NO2 adsorption. From the nitrogen and oxygen balance data, we conclude that NO2 adsorption involves the reduction of NO2 to NO driven by oxidation of the carbon surface. The formed NO is either adsorbed on the carbon surface or released as exhaust gas depending on the surface conditions. The adsorbed NO species are released along with O2 and a small amount of CO2 and CO at temperatures below 150 °C during heating. NO2 becomes stable when the carbon surface has been extensively oxidized. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800249s
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4358–4362[article] Reaction of NO2 with activated carbon at ambient temperature [texte imprimé] / Wei-Jun Zhang, Auteur ; Andrey Bagreev, Auteur ; Firooz Rasouli, Auteur . - 2008 . - p. 4358–4362.
Bibliogr. p. 4362
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4358–4362
Mots-clés : NO2 Activated carbon Adsorption times Résumé : NO2 adsorption on activated carbons at ambient temperature was studied. The adsorbed species after various adsorption times were examined by analyzing the evolution of NO, NO2, CO, CO2, and O2 during thermal desorption. Emission of NO but not NO2 was observed during the early stage of NO2 adsorption. From the nitrogen and oxygen balance data, we conclude that NO2 adsorption involves the reduction of NO2 to NO driven by oxidation of the carbon surface. The formed NO is either adsorbed on the carbon surface or released as exhaust gas depending on the surface conditions. The adsorbed NO species are released along with O2 and a small amount of CO2 and CO at temperatures below 150 °C during heating. NO2 becomes stable when the carbon surface has been extensively oxidized. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800249s Exemplaires
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Titre : Investigation into photocatalytic degradation of gaseous ammonia in CPCR Type de document : texte imprimé Auteurs : Qijin Geng, Auteur ; Qingjie Guo, Auteur ; Changqing Cao, Auteur ; Yunchen Zhang, Auteur Année de publication : 2008 Article en page(s) : p. 4363–4368 Note générale : Bibliogr. p. 4368 Langues : Anglais (eng) Mots-clés : Ammonia Circulated photocatalytic reactor Photocatalytic degradation Résumé : Addition of urea-based antifreeze admixtures during cement mixing in construction of buildings has led to increasing indoor air pollution because of continuous transformation and emission of urea to gaseous ammonia on indoor concrete walls. To control ammonia pollution from indoor concrete walls, a circulated photocatalytic reactor (CPCR) was designed to intensify the performance for the decomposition of gaseous ammonia in the present study and TiO2 film photocatalysts were prepared by the sol−gel method and coating onto the inner wall of this reactor using a bonder of polyacrylic ester emulsion, which was characterized by FTIR, TEM, and SEM. In particular, the influences of initial concentration of ammonia on the degradation conversion (Dp), apparent reaction rate constants (kr), initial degradation rate (r), deactivation, and regeneration of catalyst in CPCR were investigated. Furthermore, a designed equation of surface catalytic kinetics was developed for describing the decomposition of ammonia in CPCR. The total number of adsorption sites available for the gas molecules NT and the adsorption equilibrium constant Kads values were determined through a linear-fitting method. Finally, undesirable NO2− and NO3− were detected as the intermediates in the process of photodegradation at different initial concentration of ammonia, which was detected by catalytic kinetic spectrophotometry. The results indicated that the degradation conversion (Dp), initial degradation rate (r), degraded products, and half-life (t1/2) were closely correlated to the initial concentration of ammonia. It was found that the reaction kinetics fixed the pseudofirst-order kinetic equation of photocatalytic degradation of gaseous ammonia in CPCR, and the kinetic results are discussed in terms of adsorption of ammonia and products degraded. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800274g
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4363–4368[article] Investigation into photocatalytic degradation of gaseous ammonia in CPCR [texte imprimé] / Qijin Geng, Auteur ; Qingjie Guo, Auteur ; Changqing Cao, Auteur ; Yunchen Zhang, Auteur . - 2008 . - p. 4363–4368.
Bibliogr. p. 4368
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4363–4368
Mots-clés : Ammonia Circulated photocatalytic reactor Photocatalytic degradation Résumé : Addition of urea-based antifreeze admixtures during cement mixing in construction of buildings has led to increasing indoor air pollution because of continuous transformation and emission of urea to gaseous ammonia on indoor concrete walls. To control ammonia pollution from indoor concrete walls, a circulated photocatalytic reactor (CPCR) was designed to intensify the performance for the decomposition of gaseous ammonia in the present study and TiO2 film photocatalysts were prepared by the sol−gel method and coating onto the inner wall of this reactor using a bonder of polyacrylic ester emulsion, which was characterized by FTIR, TEM, and SEM. In particular, the influences of initial concentration of ammonia on the degradation conversion (Dp), apparent reaction rate constants (kr), initial degradation rate (r), deactivation, and regeneration of catalyst in CPCR were investigated. Furthermore, a designed equation of surface catalytic kinetics was developed for describing the decomposition of ammonia in CPCR. The total number of adsorption sites available for the gas molecules NT and the adsorption equilibrium constant Kads values were determined through a linear-fitting method. Finally, undesirable NO2− and NO3− were detected as the intermediates in the process of photodegradation at different initial concentration of ammonia, which was detected by catalytic kinetic spectrophotometry. The results indicated that the degradation conversion (Dp), initial degradation rate (r), degraded products, and half-life (t1/2) were closely correlated to the initial concentration of ammonia. It was found that the reaction kinetics fixed the pseudofirst-order kinetic equation of photocatalytic degradation of gaseous ammonia in CPCR, and the kinetic results are discussed in terms of adsorption of ammonia and products degraded. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800274g Exemplaires
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Titre : Simultaneous determination of the surface tension and density of polystyrene in supercritical nitrogen Type de document : texte imprimé Auteurs : H. Park, Auteur ; C. B. Park, Auteur ; C. Tzoganakis, Auteur ; K. H. Tan, Auteur Année de publication : 2008 Article en page(s) : p. 4369–4373 Note générale : Bibliogr. p. 4373 Langues : Anglais (eng) Mots-clés : Polymers -- polystyrene Density Surface tension Résumé : In this paper we present a simple procedure for calculating the mass density of polymers at high temperature and pressure conditions. The proposed method entails the integration of a pendant drop volume from an axisymmetric drop image profile; this same pendant drop profile can be used to determine the surface tension using axisymmetric drop shape analysis (ADSA). Our approach yields both density and surface tension data simultaneously and is advantageous since it does not require any additional procedure or module to calculate the density of polymers in a fluid. This integration method provides a set of density data for the sample polymer, polystyrene, in supercritical fluid nitrogen, which is similar to the data derived from the empirical Tait equation and the semiempirical Sanchez−Lacombe equation of state when the temperature is above the polymer glass transition point. The results corroborate the use of all three approaches in determining the mass density of polymers at high temperatures. The comparable surface tension data are obtained at temperatures above the glass transition temperature of polymer with the densities generated by the three density determination approaches. We expect that the approach based on ADSA in conjunction with the mass density determination by the current integration method can be applied to the surface tension measurements of many other polymer melts in various fluid environments. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071472q
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4369–4373[article] Simultaneous determination of the surface tension and density of polystyrene in supercritical nitrogen [texte imprimé] / H. Park, Auteur ; C. B. Park, Auteur ; C. Tzoganakis, Auteur ; K. H. Tan, Auteur . - 2008 . - p. 4369–4373.
Bibliogr. p. 4373
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4369–4373
Mots-clés : Polymers -- polystyrene Density Surface tension Résumé : In this paper we present a simple procedure for calculating the mass density of polymers at high temperature and pressure conditions. The proposed method entails the integration of a pendant drop volume from an axisymmetric drop image profile; this same pendant drop profile can be used to determine the surface tension using axisymmetric drop shape analysis (ADSA). Our approach yields both density and surface tension data simultaneously and is advantageous since it does not require any additional procedure or module to calculate the density of polymers in a fluid. This integration method provides a set of density data for the sample polymer, polystyrene, in supercritical fluid nitrogen, which is similar to the data derived from the empirical Tait equation and the semiempirical Sanchez−Lacombe equation of state when the temperature is above the polymer glass transition point. The results corroborate the use of all three approaches in determining the mass density of polymers at high temperatures. The comparable surface tension data are obtained at temperatures above the glass transition temperature of polymer with the densities generated by the three density determination approaches. We expect that the approach based on ADSA in conjunction with the mass density determination by the current integration method can be applied to the surface tension measurements of many other polymer melts in various fluid environments. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071472q Exemplaires
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Titre : Synthesis of La0.9K0.1CoO3 fibers and the catalytic properties for diesel soot removal Type de document : texte imprimé Auteurs : Cairong Gong, Auteur ; Chonglin Song, Auteur ; Yiqiang Pei, Auteur ; Lv Gang, Auteur Année de publication : 2008 Article en page(s) : p. 4374–4378 Note générale : Bibliogr. p. 4378 Langues : Anglais (eng) Mots-clés : La0.9K0.1CoO3 fibers Calcination process Scanning electron microscopy Résumé : La0.9K0.1CoO3 perovskite type oxide fibers have been prepared by a sol−gel process combined with electrospinning procedure. The reactions during the calcination process of fibers have been tracked and characterized by TG, IR, and XRD. The prepared La0.9K0.1CoO3 fibers are composed of nanoparticles and the BET surface area is 7.1 m2/g. The scanning electron microscopy (SEM) results indicate that each individual fiber is uniform in cross section, and the average diameter of this sample is 600 nm. The catalytic activity for the combustion of soot particulate is evaluated by the technique of the temperature-programmed reaction, and the combustion temperature of carbon is indeed significantly lower than that of noncatalytic combustion under loose contact conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071599f
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4374–4378[article] Synthesis of La0.9K0.1CoO3 fibers and the catalytic properties for diesel soot removal [texte imprimé] / Cairong Gong, Auteur ; Chonglin Song, Auteur ; Yiqiang Pei, Auteur ; Lv Gang, Auteur . - 2008 . - p. 4374–4378.
Bibliogr. p. 4378
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4374–4378
Mots-clés : La0.9K0.1CoO3 fibers Calcination process Scanning electron microscopy Résumé : La0.9K0.1CoO3 perovskite type oxide fibers have been prepared by a sol−gel process combined with electrospinning procedure. The reactions during the calcination process of fibers have been tracked and characterized by TG, IR, and XRD. The prepared La0.9K0.1CoO3 fibers are composed of nanoparticles and the BET surface area is 7.1 m2/g. The scanning electron microscopy (SEM) results indicate that each individual fiber is uniform in cross section, and the average diameter of this sample is 600 nm. The catalytic activity for the combustion of soot particulate is evaluated by the technique of the temperature-programmed reaction, and the combustion temperature of carbon is indeed significantly lower than that of noncatalytic combustion under loose contact conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071599f Exemplaires
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Titre : Temperature profile analysis of the citrate-nitrate combustion system Type de document : texte imprimé Auteurs : Marjan Marinšek, Auteur ; Jana Kemperl, Auteur ; Blaž Likozar, Auteur ; Jadran Macek, Auteur Année de publication : 2008 Article en page(s) : p. 4379–4386 Note générale : Bibliogr. p. 4385-4386 Langues : Anglais (eng) Mots-clés : Citrate− nitrate combustion Combustion system Résumé : The citrate−nitrate combustion reaction was used for mixed NiO−YSZ (yttria-stabilized zirconia) preparation. This system was chosen because of its nonviolent nature and its potential use in nanosized YSZ-based cermets and in some electrocatalytic applications such as fuel cells. The kinetic and thermodynamic parameters of the combustion system were studied using wave velocity analysis, the Boddington method, and the Freeman−Carroll method. The calculated activation energies of the combustion system using these three kinetic analysis approaches were 65.4, 61.4, and 60.6 kJ/mol, respectively. The obtained thermodynamic and kinetic parameters of the citrate−nitrate system were also used for a computer simulation of the combustion temperature profiles and the apparent conversion profiles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800296m
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4379–4386[article] Temperature profile analysis of the citrate-nitrate combustion system [texte imprimé] / Marjan Marinšek, Auteur ; Jana Kemperl, Auteur ; Blaž Likozar, Auteur ; Jadran Macek, Auteur . - 2008 . - p. 4379–4386.
Bibliogr. p. 4385-4386
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4379–4386
Mots-clés : Citrate− nitrate combustion Combustion system Résumé : The citrate−nitrate combustion reaction was used for mixed NiO−YSZ (yttria-stabilized zirconia) preparation. This system was chosen because of its nonviolent nature and its potential use in nanosized YSZ-based cermets and in some electrocatalytic applications such as fuel cells. The kinetic and thermodynamic parameters of the combustion system were studied using wave velocity analysis, the Boddington method, and the Freeman−Carroll method. The calculated activation energies of the combustion system using these three kinetic analysis approaches were 65.4, 61.4, and 60.6 kJ/mol, respectively. The obtained thermodynamic and kinetic parameters of the citrate−nitrate system were also used for a computer simulation of the combustion temperature profiles and the apparent conversion profiles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800296m Exemplaires
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Titre : Alternate cycles process for municipal WWTPs upgrading : ready for widespread application? Type de document : texte imprimé Auteurs : Paolo Battistoni, Auteur ; Francesco Fatone, Auteur ; Emanuela Cola, Auteur ; Paolo Pavan, Auteur Année de publication : 2008 Article en page(s) : p. 4387–4393 Note générale : Bibliogr. p. 4393 Langues : Anglais (eng) Mots-clés : Alternating systems Municipal WWTPs’ upgrading Résumé : The interest in the biological alternating anoxic/oxic reactors to upgrade existing wastewater treatment plants has been recently renewed, thanks to the use of reliable automatic control systems. To discuss the treatment capabilities of the alternating systems, with particular relation to the municipal WWTPs’ upgrading, this study exploits the experience gained in this field through numerous years of R&D. At first a pilot plant study and then a full scale alternating plant were used to supply experimental data that support the final schematic of methodology. The pilot experimentation was based in the real loading conditions of the italian municipal WWTPs. Real municipal sewage was used to feed the plant in six steady-state periods, applying nitrogen loading rates ranging from 0.03 to 0.1 kg N m−3 d−1. Major problems with the nitrogen removal performances occurred in the case of overaeration of the activated sludge tank, corresponding to influent low-loaded wastewater. The experimental durations per day of the anoxic and oxic phases were in good agreement with a simplified mathematical model, which was validated by full scale data and was finally considered useful for the upgrading design. The maximum treatment capacity of the process in terms of nitrogen loading rates was estimated in the range 0.10−0.16 kg N m−3 d−1 according to the different rates for biological nitrification and denitrification, which influence the oxic and anoxic durations per day. Moreover, the reliability of the control device used for the experimentation was proved through the statistic analyses of the performed cycles, which were in agreement with the actual nitrogen removal performances. Finally, the schematic of methodology shows how easy and consolidated the upgrading of existing wastewater treatment plants by the alternate cycles process could be. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070109g
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4387–4393[article] Alternate cycles process for municipal WWTPs upgrading : ready for widespread application? [texte imprimé] / Paolo Battistoni, Auteur ; Francesco Fatone, Auteur ; Emanuela Cola, Auteur ; Paolo Pavan, Auteur . - 2008 . - p. 4387–4393.
Bibliogr. p. 4393
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4387–4393
Mots-clés : Alternating systems Municipal WWTPs’ upgrading Résumé : The interest in the biological alternating anoxic/oxic reactors to upgrade existing wastewater treatment plants has been recently renewed, thanks to the use of reliable automatic control systems. To discuss the treatment capabilities of the alternating systems, with particular relation to the municipal WWTPs’ upgrading, this study exploits the experience gained in this field through numerous years of R&D. At first a pilot plant study and then a full scale alternating plant were used to supply experimental data that support the final schematic of methodology. The pilot experimentation was based in the real loading conditions of the italian municipal WWTPs. Real municipal sewage was used to feed the plant in six steady-state periods, applying nitrogen loading rates ranging from 0.03 to 0.1 kg N m−3 d−1. Major problems with the nitrogen removal performances occurred in the case of overaeration of the activated sludge tank, corresponding to influent low-loaded wastewater. The experimental durations per day of the anoxic and oxic phases were in good agreement with a simplified mathematical model, which was validated by full scale data and was finally considered useful for the upgrading design. The maximum treatment capacity of the process in terms of nitrogen loading rates was estimated in the range 0.10−0.16 kg N m−3 d−1 according to the different rates for biological nitrification and denitrification, which influence the oxic and anoxic durations per day. Moreover, the reliability of the control device used for the experimentation was proved through the statistic analyses of the performed cycles, which were in agreement with the actual nitrogen removal performances. Finally, the schematic of methodology shows how easy and consolidated the upgrading of existing wastewater treatment plants by the alternate cycles process could be. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070109g Exemplaires
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Titre : Online identification and control of pH in a neutralization system Type de document : texte imprimé Auteurs : Salih Obut, Auteur ; Canan Özgen, Auteur Année de publication : 2008 Article en page(s) : p. 4394–4404 Note générale : Bibliogr. p. 4404 Langues : Anglais (eng) Mots-clés : PH control Wastewater -- neutralization system Online identification technique Résumé : pH control of a neutralization system for wastewater, where the input waste stream has variable properties in terms of acid concentration and flow rate, is investigated with different control algorithms utilizing an online identification technique. Performances of the designed controllers (model predictive (MPC), fuzzy logic (FLC), and conventional PI controller) are tested and compared mainly for disturbance rejection, set-point tracking, and robustness issues theoretically and experimentally on a laboratory-scale pH neutralization system. Additional experiments are done with original wastewater samples taken from an electronic-circuits manufacturing plant. All controllers’ performances are found to be close, while adaptive MPC can be considered better compared to others due its constraint handling capabilities and FLC can be preferred because it can be used without an identification step. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070492p
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4394–4404[article] Online identification and control of pH in a neutralization system [texte imprimé] / Salih Obut, Auteur ; Canan Özgen, Auteur . - 2008 . - p. 4394–4404.
Bibliogr. p. 4404
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4394–4404
Mots-clés : PH control Wastewater -- neutralization system Online identification technique Résumé : pH control of a neutralization system for wastewater, where the input waste stream has variable properties in terms of acid concentration and flow rate, is investigated with different control algorithms utilizing an online identification technique. Performances of the designed controllers (model predictive (MPC), fuzzy logic (FLC), and conventional PI controller) are tested and compared mainly for disturbance rejection, set-point tracking, and robustness issues theoretically and experimentally on a laboratory-scale pH neutralization system. Additional experiments are done with original wastewater samples taken from an electronic-circuits manufacturing plant. All controllers’ performances are found to be close, while adaptive MPC can be considered better compared to others due its constraint handling capabilities and FLC can be preferred because it can be used without an identification step. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070492p Exemplaires
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Titre : Steam system network synthesis using process integration Type de document : texte imprimé Auteurs : Sternberg W. A. Coetzee, Auteur ; Thokozani Majozi, Auteur Année de publication : 2008 Article en page(s) : p. 4405–4413 Note générale : Bibliogr. p. 4413 Langues : Anglais (eng) Mots-clés : Steam system Network synthesis Résumé : Steam boilers are used to generate steam in order to meet the duty requirements of cold process streams. The most common heat exchanger network layout associated with the boiler is a completely parallel design, where the duty of each cold process stream is met by an external hot utility stream. This observation suggests that the flow rate of steam needed for the system can be reduced, while maintaining the required duty, simply by introducing series connections to the layout of the network (Kim, J. K.; Smith, R. Cooling water system design. Chem. Eng. Sci. 2001, 56, 3641−3658). Phase change of saturated steam to saturated liquid plays a vital role in the targeting method as well as the design of the network layout, since the saturated liquid (and resulting reuse liquid) is also used to meet the cold process duty requirements. A hybrid graphical and mathematical technique for targeting and network synthesis is presented. The main objective of the technique is to reduce steam flow rate without compromising the duty requirements of the process heat exchangers. In order to assess the advantage of a hybrid technique, a case study is used where a steam savings of 29.6% is obtained, compaired with using just saturated steam. We further present a complete mathematical technique to demonstrate the advantage of the graphical targeting concept in solution time improvement. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071195n
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4405–4413[article] Steam system network synthesis using process integration [texte imprimé] / Sternberg W. A. Coetzee, Auteur ; Thokozani Majozi, Auteur . - 2008 . - p. 4405–4413.
Bibliogr. p. 4413
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4405–4413
Mots-clés : Steam system Network synthesis Résumé : Steam boilers are used to generate steam in order to meet the duty requirements of cold process streams. The most common heat exchanger network layout associated with the boiler is a completely parallel design, where the duty of each cold process stream is met by an external hot utility stream. This observation suggests that the flow rate of steam needed for the system can be reduced, while maintaining the required duty, simply by introducing series connections to the layout of the network (Kim, J. K.; Smith, R. Cooling water system design. Chem. Eng. Sci. 2001, 56, 3641−3658). Phase change of saturated steam to saturated liquid plays a vital role in the targeting method as well as the design of the network layout, since the saturated liquid (and resulting reuse liquid) is also used to meet the cold process duty requirements. A hybrid graphical and mathematical technique for targeting and network synthesis is presented. The main objective of the technique is to reduce steam flow rate without compromising the duty requirements of the process heat exchangers. In order to assess the advantage of a hybrid technique, a case study is used where a steam savings of 29.6% is obtained, compaired with using just saturated steam. We further present a complete mathematical technique to demonstrate the advantage of the graphical targeting concept in solution time improvement. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071195n Exemplaires
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Titre : Immobilization of ionic liquid [BMIM][PF6] by spraying suspension dispersion method Type de document : texte imprimé Auteurs : Hongshuai Gao, Auteur ; Jianmin Xing, Auteur ; Xiaochao Xiong, Auteur ; Yuguang Li, Auteur Année de publication : 2008 Article en page(s) : p. 4414–4417 Note générale : Bibliogr. p. 4417 Langues : Anglais (eng) Mots-clés : Ionic liquid -- immobilization Spraying suspension dispersion Nitrogen gas pressure Résumé : A novel method of immobilizing ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] by spraying suspension dispersion was proposed. The oil phase, composed of [BMIM][PF6], polysulfone, and dichloromethane, was sprayed into the 0.2 wt % gelatin aqueous solution using nitrogen gas pressure to form droplets. As dichloromethane evaporated completely, polysulfone microcapsules, containing the [BMIM][PF6], were obtained. In order to select a suitable shell material and dispersant, several parallel experiments were also carried out, which proved that that polysulfone and gelatin are suitable shell material and dispersant, respectively. The polysulfone microcapsules enclosing ionic liquid were examined using a scanning electron microscope and thermogravimetric analyzer. The results showed that the microcapsules have an average diameter of 70 μm with narrow size distribution and smooth surface, and the encapsulation capacity of microcapsules is 29%. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701702n
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4414–4417[article] Immobilization of ionic liquid [BMIM][PF6] by spraying suspension dispersion method [texte imprimé] / Hongshuai Gao, Auteur ; Jianmin Xing, Auteur ; Xiaochao Xiong, Auteur ; Yuguang Li, Auteur . - 2008 . - p. 4414–4417.
Bibliogr. p. 4417
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4414–4417
Mots-clés : Ionic liquid -- immobilization Spraying suspension dispersion Nitrogen gas pressure Résumé : A novel method of immobilizing ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] by spraying suspension dispersion was proposed. The oil phase, composed of [BMIM][PF6], polysulfone, and dichloromethane, was sprayed into the 0.2 wt % gelatin aqueous solution using nitrogen gas pressure to form droplets. As dichloromethane evaporated completely, polysulfone microcapsules, containing the [BMIM][PF6], were obtained. In order to select a suitable shell material and dispersant, several parallel experiments were also carried out, which proved that that polysulfone and gelatin are suitable shell material and dispersant, respectively. The polysulfone microcapsules enclosing ionic liquid were examined using a scanning electron microscope and thermogravimetric analyzer. The results showed that the microcapsules have an average diameter of 70 μm with narrow size distribution and smooth surface, and the encapsulation capacity of microcapsules is 29%. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701702n Exemplaires
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Titre : Frequency domain approach to computing loop phase margins of multivariable systems Type de document : texte imprimé Auteurs : Zhen Ye, Auteur ; Qing-Guo Wang, Auteur Année de publication : 2008 Article en page(s) : p. 4418–4424 Note générale : Bibliogr. p. 4424 Langues : Anglais (eng) Mots-clés : Loop phase margins Computing loop phase Multivariable systems Résumé : The loop phase margins of multivariable control systems are defined as the allowable individual loop phase perturbations within which stability of the closed-loop system is guaranteed. This paper presents a frequency domain approach to accurately computing these phase margins for multivariable systems. With the help of unitary mapping between two complex vector space, the MIMO phase margin problem is converted using the Nyquist stability analysis to the problem of some simple constrained optimization, which is then solved numerically with the Lagrange multiplier and Newton−Raphson iteration algorithm. The proposed approach can provide exact margins and thus improves the linear matrix inequalities (LMI) results reported before, which could be conservative. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701693j
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4418–4424[article] Frequency domain approach to computing loop phase margins of multivariable systems [texte imprimé] / Zhen Ye, Auteur ; Qing-Guo Wang, Auteur . - 2008 . - p. 4418–4424.
Bibliogr. p. 4424
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4418–4424
Mots-clés : Loop phase margins Computing loop phase Multivariable systems Résumé : The loop phase margins of multivariable control systems are defined as the allowable individual loop phase perturbations within which stability of the closed-loop system is guaranteed. This paper presents a frequency domain approach to accurately computing these phase margins for multivariable systems. With the help of unitary mapping between two complex vector space, the MIMO phase margin problem is converted using the Nyquist stability analysis to the problem of some simple constrained optimization, which is then solved numerically with the Lagrange multiplier and Newton−Raphson iteration algorithm. The proposed approach can provide exact margins and thus improves the linear matrix inequalities (LMI) results reported before, which could be conservative. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701693j Exemplaires
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Titre : Effect of solvent on controllability in extractive distillation Type de document : texte imprimé Auteurs : William L. Luyben, Auteur Année de publication : 2008 Article en page(s) : p. 4425–4439 Note générale : Bibliogr. p. 4439 Langues : Anglais (eng) Mots-clés : Acetone/methanol system Solvents Extractive distillation systems Résumé : There have been numerous books and papers dealing with the effect of solvent selection on the steady-state design of extractive distillation systems. Extractive distillation is widely used to separate homogeneous binary azeotropes by adding a higher-boiling solvent that attracts one of the components. These systems typically feature an extractive column and a solvent-recovery column. The two products are removed in the distillate streams from the two columns. The solvent is circulated from the base of the solvent recovery back to near the top of the extractive column. A recent paper by Kossack et al. (Chem. Eng. Res. Dev., in press) discusses in detail the steady-state economic design issues and presents several examples that use a variety of solvents for the separation of acetone and methanol. Some solvents drive the acetone overhead in the extractive column, while others drive the methanol overhead in the extractive column.This paper extends this work to compare the dynamic performance of the acetone/methanol system with different solvents. The numerical cases are based on those presented by Kossack et al. Three solvents are explored: water, dimethyl sulfur oxide, and chlorobenzene. The first and second solvents drive the acetone overhead in the extractive column. The last solvent drives the methanol overhead in the extractive column. Control structures are developed for each system. Dynamic simulation results show that all systems are controllable, but product quality variability is poorest when the methanol is driven overhead in the extractive column. One explanation for this difference is that methanol is higher boiling than acetone and preferentially wants to go out the bottom. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701757d
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4425–4439[article] Effect of solvent on controllability in extractive distillation [texte imprimé] / William L. Luyben, Auteur . - 2008 . - p. 4425–4439.
Bibliogr. p. 4439
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4425–4439
Mots-clés : Acetone/methanol system Solvents Extractive distillation systems Résumé : There have been numerous books and papers dealing with the effect of solvent selection on the steady-state design of extractive distillation systems. Extractive distillation is widely used to separate homogeneous binary azeotropes by adding a higher-boiling solvent that attracts one of the components. These systems typically feature an extractive column and a solvent-recovery column. The two products are removed in the distillate streams from the two columns. The solvent is circulated from the base of the solvent recovery back to near the top of the extractive column. A recent paper by Kossack et al. (Chem. Eng. Res. Dev., in press) discusses in detail the steady-state economic design issues and presents several examples that use a variety of solvents for the separation of acetone and methanol. Some solvents drive the acetone overhead in the extractive column, while others drive the methanol overhead in the extractive column.This paper extends this work to compare the dynamic performance of the acetone/methanol system with different solvents. The numerical cases are based on those presented by Kossack et al. Three solvents are explored: water, dimethyl sulfur oxide, and chlorobenzene. The first and second solvents drive the acetone overhead in the extractive column. The last solvent drives the methanol overhead in the extractive column. Control structures are developed for each system. Dynamic simulation results show that all systems are controllable, but product quality variability is poorest when the methanol is driven overhead in the extractive column. One explanation for this difference is that methanol is higher boiling than acetone and preferentially wants to go out the bottom. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701757d Exemplaires
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Titre : Molecular dynamics simulation of diffusion behavior of benzene/water in PDMS-calix[4]arene hybrid pervaporation membranes Type de document : texte imprimé Auteurs : Ben Li, Auteur ; Fusheng Pan, Auteur ; Zhiping Fang, Auteur ; Liang Liu, Auteur Année de publication : 2008 Article en page(s) : p. 4440–4447 Note générale : Bibliogr. p. 4446-4447 Langues : Anglais (eng) Mots-clés : Benzene/water -- diffusion behavior Molecular dynamics simulation PDMS membranes CA Résumé : Molecular dynamics (MD) simulation was employed to investigate diffusion behavior of small penetrants in rubbery-polymer-based hybrid membranes, using pervaporative removal of benzene from its dilute solution by poly(dimethylsiloxane) (PDMS) membranes filled with calix[4]arene (CA) as the model system. In our previous experimental investigation, the normalized permeation rate of benzene (NPRb) and separation factor (benzene/water) through PDMS−CA hybrid membranes did not follow the usual monotonous or single peak/valley change, but accompanied minimum and maximum values instead. In the present study, nonbonding interaction energy between PDMS and CA, mean-square displacement (MSD), free volume characteristics, and diffusion coefficients of benzene and water in pure PDMS and hybrid membranes were analyzed by molecular dynamics simulation. The simulation results revealed that MSD and fractional free volume (FFV) values were closely dependent on interaction energy. Diffusion coefficients of benzene and water at “infinite dilution” and saturated condition displayed the same changing tendency, although the values at saturated condition were a bit larger. Moreover, it was observed that diffusion coefficients were not only related to FFV but also affected by the interaction between CA and the penetrants. Overall, the MD results agreed well with the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0708935
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4440–4447[article] Molecular dynamics simulation of diffusion behavior of benzene/water in PDMS-calix[4]arene hybrid pervaporation membranes [texte imprimé] / Ben Li, Auteur ; Fusheng Pan, Auteur ; Zhiping Fang, Auteur ; Liang Liu, Auteur . - 2008 . - p. 4440–4447.
Bibliogr. p. 4446-4447
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4440–4447
Mots-clés : Benzene/water -- diffusion behavior Molecular dynamics simulation PDMS membranes CA Résumé : Molecular dynamics (MD) simulation was employed to investigate diffusion behavior of small penetrants in rubbery-polymer-based hybrid membranes, using pervaporative removal of benzene from its dilute solution by poly(dimethylsiloxane) (PDMS) membranes filled with calix[4]arene (CA) as the model system. In our previous experimental investigation, the normalized permeation rate of benzene (NPRb) and separation factor (benzene/water) through PDMS−CA hybrid membranes did not follow the usual monotonous or single peak/valley change, but accompanied minimum and maximum values instead. In the present study, nonbonding interaction energy between PDMS and CA, mean-square displacement (MSD), free volume characteristics, and diffusion coefficients of benzene and water in pure PDMS and hybrid membranes were analyzed by molecular dynamics simulation. The simulation results revealed that MSD and fractional free volume (FFV) values were closely dependent on interaction energy. Diffusion coefficients of benzene and water at “infinite dilution” and saturated condition displayed the same changing tendency, although the values at saturated condition were a bit larger. Moreover, it was observed that diffusion coefficients were not only related to FFV but also affected by the interaction between CA and the penetrants. Overall, the MD results agreed well with the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0708935 Exemplaires
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Titre : Removal of branched dibenzothiophenes from hydrocarbon mixtures via charge transfer complexes with a TAPA-functionalized adsorbent Type de document : texte imprimé Auteurs : Xiaolin Wei, Auteur ; Scott M. Husson, Auteur Année de publication : 2008 Article en page(s) : p. 4448–4454 Note générale : Bibliogr. p. 4454 Langues : Anglais (eng) Mots-clés : Dibenzothiophenes TAPA-functionalized adsorbent Adsorption capacity Résumé : A direct grafting method has been demonstrated to successfully incorporate the π-acceptor, 2,4,5,7-tetranitro-9-fluorenylideneaminooxy propionic acid (TAPA), onto silica. Adsorption isotherms were measured for complexation of 4,6-dimethyldibenzothiophene (4,6-DMDBT) from n-heptane onto the TAPA-functionalized silica adsorbent. At 25 °C, maximum adsorption capacity was measured to be 58.6 mg/g for binding 4,6-DMDBT, which is 4-fold higher than that of the nonfunctionalized, bare silica sample with a surface area of 480 m2/g. The results from batch studies suggest that adsorption occurs via a 1:1 complexation between 4,6-DMDBT and TAPA. Adsorption isotherm data were collected at 0, 25, and 40 °C; these data were used to develop a relationship between the Henry’s constant for adsorption and temperature. The molar enthalpy of adsorption was calculated to be ΔHads = −12.1 kJ/mol; this value is evidence for formation of π-electron acceptor−donor complexes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070818u
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4448–4454[article] Removal of branched dibenzothiophenes from hydrocarbon mixtures via charge transfer complexes with a TAPA-functionalized adsorbent [texte imprimé] / Xiaolin Wei, Auteur ; Scott M. Husson, Auteur . - 2008 . - p. 4448–4454.
Bibliogr. p. 4454
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4448–4454
Mots-clés : Dibenzothiophenes TAPA-functionalized adsorbent Adsorption capacity Résumé : A direct grafting method has been demonstrated to successfully incorporate the π-acceptor, 2,4,5,7-tetranitro-9-fluorenylideneaminooxy propionic acid (TAPA), onto silica. Adsorption isotherms were measured for complexation of 4,6-dimethyldibenzothiophene (4,6-DMDBT) from n-heptane onto the TAPA-functionalized silica adsorbent. At 25 °C, maximum adsorption capacity was measured to be 58.6 mg/g for binding 4,6-DMDBT, which is 4-fold higher than that of the nonfunctionalized, bare silica sample with a surface area of 480 m2/g. The results from batch studies suggest that adsorption occurs via a 1:1 complexation between 4,6-DMDBT and TAPA. Adsorption isotherm data were collected at 0, 25, and 40 °C; these data were used to develop a relationship between the Henry’s constant for adsorption and temperature. The molar enthalpy of adsorption was calculated to be ΔHads = −12.1 kJ/mol; this value is evidence for formation of π-electron acceptor−donor complexes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070818u Exemplaires
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Titre : Highly attrition-resistant zinc oxide-based sorbents for H2S removal by spray-drying technique Type de document : texte imprimé Auteurs : Joong B. Lee, Auteur ; Jeom-In Baek, Auteur ; Chong K. Ryu, Auteur ; Chang K. Yi, Auteur Année de publication : 2008 Article en page(s) : p. 4455–4464 Note générale : Bibliogr. p. 4463-4464 Langues : Anglais (eng) Mots-clés : ZnO-based sorbent Spray-drying technique ZAC 32N 32SU Desulfurization Résumé : A ZnO-based sorbent, ZAC 32N, applicable to transport reactors was successfully prepared by the spray-drying technique. Another sorbent, ZAC 32SU, was prepared by scale-up preparation of ZAC 32N sorbent. The physical properties of the sorbents such as attrition resistance, specific surface area, pore volume, and particle size were extensively characterized and exhibited a good potential for use in transport applications. The chemical reactivity tested in the thermogravimetric analyzer and microreactor exhibited desirable characteristics for effective desulfurization of syngas streams in the range of 450−550 °C. Bench-scale tests for the sorbent ZAC 32SU were performed for a continuous 160 h with a steady solid circulation of 54.6 kg/h. The results showed 99.5%+ desulfurization at 500−550 °C and reasonable regenerability at 550−620 °C. Test results on the physical properties and chemical reactivity indicated that the performance of developed sorbents proved to be outstanding. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070962f
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4455–4464[article] Highly attrition-resistant zinc oxide-based sorbents for H2S removal by spray-drying technique [texte imprimé] / Joong B. Lee, Auteur ; Jeom-In Baek, Auteur ; Chong K. Ryu, Auteur ; Chang K. Yi, Auteur . - 2008 . - p. 4455–4464.
Bibliogr. p. 4463-4464
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4455–4464
Mots-clés : ZnO-based sorbent Spray-drying technique ZAC 32N 32SU Desulfurization Résumé : A ZnO-based sorbent, ZAC 32N, applicable to transport reactors was successfully prepared by the spray-drying technique. Another sorbent, ZAC 32SU, was prepared by scale-up preparation of ZAC 32N sorbent. The physical properties of the sorbents such as attrition resistance, specific surface area, pore volume, and particle size were extensively characterized and exhibited a good potential for use in transport applications. The chemical reactivity tested in the thermogravimetric analyzer and microreactor exhibited desirable characteristics for effective desulfurization of syngas streams in the range of 450−550 °C. Bench-scale tests for the sorbent ZAC 32SU were performed for a continuous 160 h with a steady solid circulation of 54.6 kg/h. The results showed 99.5%+ desulfurization at 500−550 °C and reasonable regenerability at 550−620 °C. Test results on the physical properties and chemical reactivity indicated that the performance of developed sorbents proved to be outstanding. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070962f Exemplaires
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Titre : Sodium-based dry regenerable sorbent for carbon dioxide capture from power plant flue gas Type de document : texte imprimé Auteurs : Joong B. Lee, Auteur ; Chong K. Ryu, Auteur ; Jeom-In Baek, Auteur ; Ji H. Lee, Auteur Année de publication : 2008 Article en page(s) : p. 4465–4472 Note générale : Bibliogr. p. 4471-4472 Langues : Anglais (eng) Mots-clés : Dry regenerable sorbent -- sodium Spray-drying techniques CO2 capture Résumé : Dry regenerable sorbent technology is one of the emerging technologies as a cost-effective and energy-efficient technology for CO2 capture from flue gas. Six sodium-based dry regenerable sorbents were prepared by spray-drying techniques. Their physical properties and reactivities were tested to evaluate their applicability to a fluidized-bed or fast transport-bed CO2 capture process. Each sorbents contained 20−50 wt% of Na2CO3 or NaHCO3. All sorbents except for Sorb NX30 were insufficient with either attrition resistance or reactivity, or both properties. Sorb NX30 sorbent satisfied most of the physical requirements for a commercial fluidized-bed reactor process along with good chemical reactivity. Sorb NX30 sorbent had a spherical shape, an average size of 89 μm, a size distribution of 38−250 μm, and a bulk density of approximately 0.87 g/mL. The attrition index (AI) of Sorb NX30 reached below 5% compared to about 20% for commercial fluidized catalytic cracking (FCC) catalysts. CO2 sorption capacity of Sorb NX30 was approximately 10 wt % (>80% sorbent utilization) in the simulated flue gas condition compared with 6 of 30 wt % MEA solution (33% sorbent utilization). All sorbents showed almost-complete regeneration at temperatures less than 120 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0709638
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4465–4472[article] Sodium-based dry regenerable sorbent for carbon dioxide capture from power plant flue gas [texte imprimé] / Joong B. Lee, Auteur ; Chong K. Ryu, Auteur ; Jeom-In Baek, Auteur ; Ji H. Lee, Auteur . - 2008 . - p. 4465–4472.
Bibliogr. p. 4471-4472
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4465–4472
Mots-clés : Dry regenerable sorbent -- sodium Spray-drying techniques CO2 capture Résumé : Dry regenerable sorbent technology is one of the emerging technologies as a cost-effective and energy-efficient technology for CO2 capture from flue gas. Six sodium-based dry regenerable sorbents were prepared by spray-drying techniques. Their physical properties and reactivities were tested to evaluate their applicability to a fluidized-bed or fast transport-bed CO2 capture process. Each sorbents contained 20−50 wt% of Na2CO3 or NaHCO3. All sorbents except for Sorb NX30 were insufficient with either attrition resistance or reactivity, or both properties. Sorb NX30 sorbent satisfied most of the physical requirements for a commercial fluidized-bed reactor process along with good chemical reactivity. Sorb NX30 sorbent had a spherical shape, an average size of 89 μm, a size distribution of 38−250 μm, and a bulk density of approximately 0.87 g/mL. The attrition index (AI) of Sorb NX30 reached below 5% compared to about 20% for commercial fluidized catalytic cracking (FCC) catalysts. CO2 sorption capacity of Sorb NX30 was approximately 10 wt % (>80% sorbent utilization) in the simulated flue gas condition compared with 6 of 30 wt % MEA solution (33% sorbent utilization). All sorbents showed almost-complete regeneration at temperatures less than 120 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0709638 Exemplaires
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Titre : Distribution ratios of lipase-catalyzed reaction products in ionic liquid supercritical CO2 systems : resolution of 2-octanol enantiomers Type de document : texte imprimé Auteurs : Rafat Bogel-Lukasik, Auteur ; Vesna Najdanovic-Visak, Auteur ; Susana Barreiros, Auteur Année de publication : 2008 Article en page(s) : p. 4473–4480 Note générale : Bibliogr. p. 4479-4480 Langues : Anglais (eng) Mots-clés : Vapor-liquid equilibrium CO2 systems Ionic liquid Résumé : This paper presents vapor−liquid equilibrium (VLE) data for systems containing high-pressure CO2, an ionic liquid, and products of an enzymatic reaction between succinic anhydride and (R,S)-2-octanol in the presence of a lipase. VLE experiments were used to calculate partition coefficients of reaction products between the ionic liquid-rich phase and the CO2-rich phase. Experiments of extraction with CO2 from an ionic liquid of (S)-2-octanol in conditions similar to those of the postreaction mixture were also carried out. The extraction at 11 MPa and 35 °C allows one to recover completely the unreacted enantiomer of 2-octanol with very high enantiomeric excess (98.42%). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0714100
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4473–4480[article] Distribution ratios of lipase-catalyzed reaction products in ionic liquid supercritical CO2 systems : resolution of 2-octanol enantiomers [texte imprimé] / Rafat Bogel-Lukasik, Auteur ; Vesna Najdanovic-Visak, Auteur ; Susana Barreiros, Auteur . - 2008 . - p. 4473–4480.
Bibliogr. p. 4479-4480
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4473–4480
Mots-clés : Vapor-liquid equilibrium CO2 systems Ionic liquid Résumé : This paper presents vapor−liquid equilibrium (VLE) data for systems containing high-pressure CO2, an ionic liquid, and products of an enzymatic reaction between succinic anhydride and (R,S)-2-octanol in the presence of a lipase. VLE experiments were used to calculate partition coefficients of reaction products between the ionic liquid-rich phase and the CO2-rich phase. Experiments of extraction with CO2 from an ionic liquid of (S)-2-octanol in conditions similar to those of the postreaction mixture were also carried out. The extraction at 11 MPa and 35 °C allows one to recover completely the unreacted enantiomer of 2-octanol with very high enantiomeric excess (98.42%). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0714100 Exemplaires
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Titre : Analysis of water transmembrane profiles and ionic transport during proton exchange membrane fuel cell transient behavior Type de document : texte imprimé Auteurs : Javier Parrondo, Auteur ; Arantxa Barrio, Auteur ; Jose Lombraña, Auteur ; Federico Mijangos, Auteur Année de publication : 2008 Article en page(s) : p. 4481–4489 Note générale : Bibliogr. p. 4488-4489 Langues : Anglais (eng) Mots-clés : Transmembrane water profiles Current− voltage curves Electrochemical reaction Résumé : A one-dimensional isothermal model is used to calculate transmembrane water profiles and current−voltage curves under different operating conditions. The mechanistic model solves the mass balance over the system, basically by considering the main source-sink terms and transport contributions: fuel and air humidity, water generated by the electrochemical reaction; water concentration−diffusion and the electro-osmotic drag of water caused by the hydration shield of protons. The model is used to analyze the transient behavior of a fuel cell and the dynamics of water inside the membrane as a consequence of changes in the load, voltage, or power released by the cell. The current−voltage transient responses are analyzed and explained in terms of the hydration of the membrane and the heterogeneity of water distribution over the membrane. Temporary changes in the power released by the cell operated at constant load are associated with wetting−drying processes. Wetting curves show an induction stage because initially the membrane is critically dehydrated. The estimations from the model suggest that local water contents lower than 2.4 mol of water per 1 mol of the sulfonic group act as a bottleneck for proton transport. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070740h
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4481–4489[article] Analysis of water transmembrane profiles and ionic transport during proton exchange membrane fuel cell transient behavior [texte imprimé] / Javier Parrondo, Auteur ; Arantxa Barrio, Auteur ; Jose Lombraña, Auteur ; Federico Mijangos, Auteur . - 2008 . - p. 4481–4489.
Bibliogr. p. 4488-4489
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4481–4489
Mots-clés : Transmembrane water profiles Current− voltage curves Electrochemical reaction Résumé : A one-dimensional isothermal model is used to calculate transmembrane water profiles and current−voltage curves under different operating conditions. The mechanistic model solves the mass balance over the system, basically by considering the main source-sink terms and transport contributions: fuel and air humidity, water generated by the electrochemical reaction; water concentration−diffusion and the electro-osmotic drag of water caused by the hydration shield of protons. The model is used to analyze the transient behavior of a fuel cell and the dynamics of water inside the membrane as a consequence of changes in the load, voltage, or power released by the cell. The current−voltage transient responses are analyzed and explained in terms of the hydration of the membrane and the heterogeneity of water distribution over the membrane. Temporary changes in the power released by the cell operated at constant load are associated with wetting−drying processes. Wetting curves show an induction stage because initially the membrane is critically dehydrated. The estimations from the model suggest that local water contents lower than 2.4 mol of water per 1 mol of the sulfonic group act as a bottleneck for proton transport. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070740h Exemplaires
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Titre : Investigation of vapor-liquid surface tension for carbon dioxide and hydrocarbon mixtures by perturbed-chain statistical associating fluid theory combined with density-gradient theory Type de document : texte imprimé Auteurs : Dong Fu, Auteur ; Yuanzhen Wei, Auteur Année de publication : 2008 Article en page(s) : p. 4490–4495 Note générale : Bibliogr. p. 4494-4495 Langues : Anglais (eng) Mots-clés : Carbon dioxide Hydrocarbon binary mixtures PC-SAFT theory Vapor− liquid equilibria Résumé : The perturbed-chain statistical associating fluid theory (PC-SAFT) and density-gradient theory (DGT) are used to construct an equation of state (EOS) applicable for the phase behaviors of supercritical carbon dioxide (CO2) and hydrocarbon binary mixtures. In the bulk phases, the nonuniform EOS reduces to PC-SAFT, which is able to accurately describe the vapor−liquid equilibria (VLE) below the critical region. In the vapor−liquid surface, this EOS is able to predict the surface tensions for binary mixtures with the bulk properties and the influence parameters of pure components as input. The surface tensions of CO2−butane, CO2−decane, CO2−benzene, CO2−cyclohexane, and CO2−tetradecane binary mixtures are predicted, and the results are satisfactory compared with the experimental data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0716520
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4490–4495[article] Investigation of vapor-liquid surface tension for carbon dioxide and hydrocarbon mixtures by perturbed-chain statistical associating fluid theory combined with density-gradient theory [texte imprimé] / Dong Fu, Auteur ; Yuanzhen Wei, Auteur . - 2008 . - p. 4490–4495.
Bibliogr. p. 4494-4495
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4490–4495
Mots-clés : Carbon dioxide Hydrocarbon binary mixtures PC-SAFT theory Vapor− liquid equilibria Résumé : The perturbed-chain statistical associating fluid theory (PC-SAFT) and density-gradient theory (DGT) are used to construct an equation of state (EOS) applicable for the phase behaviors of supercritical carbon dioxide (CO2) and hydrocarbon binary mixtures. In the bulk phases, the nonuniform EOS reduces to PC-SAFT, which is able to accurately describe the vapor−liquid equilibria (VLE) below the critical region. In the vapor−liquid surface, this EOS is able to predict the surface tensions for binary mixtures with the bulk properties and the influence parameters of pure components as input. The surface tensions of CO2−butane, CO2−decane, CO2−benzene, CO2−cyclohexane, and CO2−tetradecane binary mixtures are predicted, and the results are satisfactory compared with the experimental data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0716520 Exemplaires
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Titre : Predicting temperature-dependent properties by correlations based on similarities of molecular structures : application to liquid density Type de document : texte imprimé Auteurs : Shacham, Mordechai, Auteur ; Neima Brauner, Auteur ; Haim Shore, Auteur ; Diamanta Benson-Karhi, Auteur Année de publication : 2008 Article en page(s) : p. 4496–4504 Note générale : Bibliogr. p. 4504 Langues : Anglais (eng) Mots-clés : Molecular structures Temperature-dependent properties QS2PR Résumé : A novel method for predicting temperature-dependent properties is presented. The method involves the use of measured property values of predictive compounds that are structurally similar to the target compound, and molecular descriptor values. The quantitative structure−structure−property relationship (QS2PR) is used to model a linear relationship between property values of the target and the predictive compounds. Whenever necessary, response modeling methodology (RMM) can be employed to obtain a nonlinear regression model for representing property data of the predictive compounds. The application of the method is demonstrated under a variety of conditions by prediction of the temperature-dependent liquid-density variation of 1-butene, toluene, n-hexane, and n-heneicosane. It is shown that straightforward application of the proposed method provides predictions with accuracy within the experimental error level. An advantage of the proposed method over other similar prediction models is that it does not require measured property values of the target compound. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701766m
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4496–4504[article] Predicting temperature-dependent properties by correlations based on similarities of molecular structures : application to liquid density [texte imprimé] / Shacham, Mordechai, Auteur ; Neima Brauner, Auteur ; Haim Shore, Auteur ; Diamanta Benson-Karhi, Auteur . - 2008 . - p. 4496–4504.
Bibliogr. p. 4504
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4496–4504
Mots-clés : Molecular structures Temperature-dependent properties QS2PR Résumé : A novel method for predicting temperature-dependent properties is presented. The method involves the use of measured property values of predictive compounds that are structurally similar to the target compound, and molecular descriptor values. The quantitative structure−structure−property relationship (QS2PR) is used to model a linear relationship between property values of the target and the predictive compounds. Whenever necessary, response modeling methodology (RMM) can be employed to obtain a nonlinear regression model for representing property data of the predictive compounds. The application of the method is demonstrated under a variety of conditions by prediction of the temperature-dependent liquid-density variation of 1-butene, toluene, n-hexane, and n-heneicosane. It is shown that straightforward application of the proposed method provides predictions with accuracy within the experimental error level. An advantage of the proposed method over other similar prediction models is that it does not require measured property values of the target compound. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701766m Exemplaires
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Titre : Henry’s constants of 2-ketones in aqueous solutions containing inorganic or quaternary ammonium salts Type de document : texte imprimé Auteurs : James B. Falabella, Auteur ; Amyn S. Teja, Auteur Année de publication : 2008 Article en page(s) : p. 4505–4509 Note générale : Bibliogr. p. 4509 Langues : Anglais (eng) Mots-clés : Henry’s constants Inorganic salts Dilute solution theory Résumé : Henry’s constants of 2-propanone, 2-butanone, 2-pentanone, 2-hexanone, and 2-heptanone in aqueous solutions containing inorganic salts or quaternary ammonium salts were determined at temperatures between 313 and 343 K, and salt ionic strengths below 5.0. Our data show that inorganic salts generally salt-out the 2-ketones, whereas quaternary ammonium salts generally salt-in the 2-ketones. However, 2-propanone is salted-out by both types of salts. We have also extended a published model based on dilute solution theory to solutions containing two inorganic salts, as well as to solutions containing quaternary ammonium salts. We show that it is possible to correlate all data for salting-out behavior using a single salt-effect parameter for each system. Salting-in behavior can also be correlated with a single parameter, although agreement with experiment is not as good as in the case of salting-out behavior. This is because the model does not explicitly account for the role of dispersion forces in these systems, which may be inferred from the trends exhibited by the salt-effect parameter as the size of the 2-ketone increases in solutions containing quaternary ammonium salts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8000327
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4505–4509[article] Henry’s constants of 2-ketones in aqueous solutions containing inorganic or quaternary ammonium salts [texte imprimé] / James B. Falabella, Auteur ; Amyn S. Teja, Auteur . - 2008 . - p. 4505–4509.
Bibliogr. p. 4509
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4505–4509
Mots-clés : Henry’s constants Inorganic salts Dilute solution theory Résumé : Henry’s constants of 2-propanone, 2-butanone, 2-pentanone, 2-hexanone, and 2-heptanone in aqueous solutions containing inorganic salts or quaternary ammonium salts were determined at temperatures between 313 and 343 K, and salt ionic strengths below 5.0. Our data show that inorganic salts generally salt-out the 2-ketones, whereas quaternary ammonium salts generally salt-in the 2-ketones. However, 2-propanone is salted-out by both types of salts. We have also extended a published model based on dilute solution theory to solutions containing two inorganic salts, as well as to solutions containing quaternary ammonium salts. We show that it is possible to correlate all data for salting-out behavior using a single salt-effect parameter for each system. Salting-in behavior can also be correlated with a single parameter, although agreement with experiment is not as good as in the case of salting-out behavior. This is because the model does not explicitly account for the role of dispersion forces in these systems, which may be inferred from the trends exhibited by the salt-effect parameter as the size of the 2-ketone increases in solutions containing quaternary ammonium salts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8000327 Exemplaires
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Titre : Analytical solution of the mass conservation equations in gas-liquid systems : applicability to the evaluation of the volumetric mass transfer coefficient (kLa) Type de document : texte imprimé Auteurs : Elena M. Cachaza, Auteur ; M. Elena Díaz, Auteur ; Francisco J. Montes, Auteur ; Miguel A. Galán, Auteur Année de publication : 2008 Article en page(s) : p. 4510–4522 Note générale : Bibliogr. p. 4520-4522 Langues : Anglais (eng) Mots-clés : Mass conservation equations Gas-liquid systems Analytical solution Résumé : In the present work, a simple analytical solution of the simplified mass conservation equations applicable to the calculation of the volumetric mass transfer coefficient (kLa) in gas–liquid systems, named the absorption model (ABM), has been proposed and compared to the classical and less complete continuous stirred tank reactor model (CSTR). A partially aerated 2D bubble column has been used in order to study the hydrodynamics and mass transfer at varying superficial gas velocities and aspect ratios (H/W) and examine the benefits of the proposed model. In addition to its simplicity and on the contrary to the CSTR model, the ABM is able to capture the variation of kLa with H/W caused by the formation of additional liquid circulation cells as H/W is increased. Furthermore, the ABM kLa resulting values, that are comparable with previously reported ones, increase with increasing axial positions as a result of higher aeration at upper sections of the bubble column. Also, kL values, not frequently reported in the literature, were calculated. The results show that kL remains approximately constant (≈5.5 × 10−4 m/s) and, therefore, independent of UG in the considered range. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800135h
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4510–4522[article] Analytical solution of the mass conservation equations in gas-liquid systems : applicability to the evaluation of the volumetric mass transfer coefficient (kLa) [texte imprimé] / Elena M. Cachaza, Auteur ; M. Elena Díaz, Auteur ; Francisco J. Montes, Auteur ; Miguel A. Galán, Auteur . - 2008 . - p. 4510–4522.
Bibliogr. p. 4520-4522
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4510–4522
Mots-clés : Mass conservation equations Gas-liquid systems Analytical solution Résumé : In the present work, a simple analytical solution of the simplified mass conservation equations applicable to the calculation of the volumetric mass transfer coefficient (kLa) in gas–liquid systems, named the absorption model (ABM), has been proposed and compared to the classical and less complete continuous stirred tank reactor model (CSTR). A partially aerated 2D bubble column has been used in order to study the hydrodynamics and mass transfer at varying superficial gas velocities and aspect ratios (H/W) and examine the benefits of the proposed model. In addition to its simplicity and on the contrary to the CSTR model, the ABM is able to capture the variation of kLa with H/W caused by the formation of additional liquid circulation cells as H/W is increased. Furthermore, the ABM kLa resulting values, that are comparable with previously reported ones, increase with increasing axial positions as a result of higher aeration at upper sections of the bubble column. Also, kL values, not frequently reported in the literature, were calculated. The results show that kL remains approximately constant (≈5.5 × 10−4 m/s) and, therefore, independent of UG in the considered range. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800135h Exemplaires
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Titre : Development of an a priori ionic liquid design tool. 1. integration of a Novel COSMO-RS molecular descriptor on neural networks Type de document : texte imprimé Auteurs : José Palomar, Auteur ; José S. Torrecilla, Auteur ; Víctor R. Ferro, Auteur ; Francisco Rodríguez, Auteur Année de publication : 2008 Article en page(s) : p. 4523–4532 Note générale : Bibliogr. p. 4530-4532 Langues : Anglais (eng) Mots-clés : Ionic liquids Charge distribution COSMO-RS methodology Résumé : An innovative computational approach is proposed to design ionic liquids (ILs) based on a new a priori molecular descriptor of ILs, derived from quantum-chemical COSMO-RS methodology. In this work, the charge distribution on the polarity scale given by COSMO-RS is used to characterize the chemical nature of both the cations and anions of the IL structures, using simple molecular models in the calculations. As a result, a novel a priori quantum-chemical parameter, Sσ-profile, is defined for 45 imidazolium-based ILs, as a quantitative numerical indicator of their electronic structures and molecular sizes. Subsequently, neural networks (NNs) are successfully applied to establish a relationship between the electronic information given by the Sσ-profile molecular descriptor and the density properties of IL solvents. As a consequence, we develop here an a priori computational tool for screening ILs with required properties, using COSMO-RS predictions to NN design and optimization. Current methodology is validated following a classical quantitative structure−property relationship scheme, which is the main aim of this work. However, a second part of the current investigation will be devoted to a more useful design strategy, which introduces the desired IL properties as input into inverse NN, resulting in selections of counterions as output, i.e., directly designing ILs on the computer. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800056q
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4523–4532[article] Development of an a priori ionic liquid design tool. 1. integration of a Novel COSMO-RS molecular descriptor on neural networks [texte imprimé] / José Palomar, Auteur ; José S. Torrecilla, Auteur ; Víctor R. Ferro, Auteur ; Francisco Rodríguez, Auteur . - 2008 . - p. 4523–4532.
Bibliogr. p. 4530-4532
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4523–4532
Mots-clés : Ionic liquids Charge distribution COSMO-RS methodology Résumé : An innovative computational approach is proposed to design ionic liquids (ILs) based on a new a priori molecular descriptor of ILs, derived from quantum-chemical COSMO-RS methodology. In this work, the charge distribution on the polarity scale given by COSMO-RS is used to characterize the chemical nature of both the cations and anions of the IL structures, using simple molecular models in the calculations. As a result, a novel a priori quantum-chemical parameter, Sσ-profile, is defined for 45 imidazolium-based ILs, as a quantitative numerical indicator of their electronic structures and molecular sizes. Subsequently, neural networks (NNs) are successfully applied to establish a relationship between the electronic information given by the Sσ-profile molecular descriptor and the density properties of IL solvents. As a consequence, we develop here an a priori computational tool for screening ILs with required properties, using COSMO-RS predictions to NN design and optimization. Current methodology is validated following a classical quantitative structure−property relationship scheme, which is the main aim of this work. However, a second part of the current investigation will be devoted to a more useful design strategy, which introduces the desired IL properties as input into inverse NN, resulting in selections of counterions as output, i.e., directly designing ILs on the computer. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800056q Exemplaires
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Titre : Comparing the use of gibbs ensemble and grand-canonical transition-matrix Monte Carlo methods to determine phase equilibria Type de document : texte imprimé Auteurs : Andrew S. Paluch, Auteur ; Vincent K. Shen, Auteur ; Jeffrey R. Errington, Auteur Année de publication : 2008 Article en page(s) : p. 4533–4541 Note générale : Bibliogr. p. 4541 Langues : Anglais (eng) Mots-clés : Gibbs ensemble GC-TMMC methods Molecular fluids Résumé : We present results from a computational study investigating the use of Gibbs ensemble and grand-canonical transition-matrix Monte Carlo (GC-TMMC) methods to determine the liquid−vapor phase coexistence properties of pure molecular fluids of varying degrees of complexity. The molecules used in this study were ethane, n-octane, cyclohexane, 2,5-dimethylhexane, 1-propanol, and water. We first show that the GC-TMMC method can reproduce Gibbs ensemble results found in the literature. Given the excellent agreement for each molecule, we then compare directly the performance of Gibbs ensemble and GC-TMMC simulations at both low and high reduced temperatures by monitoring the relative uncertainties in the saturation properties as a function of computational time. In general, we found that the GC-TMMC method yielded limiting uncertainties in the saturated vapor density and pressure that were significantly smaller, by an order of magnitude in some instances, than those of the Gibbs ensemble method. Limiting Gibbs ensemble uncertainties for these properties were generally in the 0.8−5.0% range. However, both methods yielded comparable limiting uncertainties in the saturated liquid density, which fell within the range of 0.1−1.0%. In the case of water at 300 K, we found that the Gibbs ensemble outperformed GC-TMMC. The relatively poor performance of the GC-TMMC method in this situation was tied to the slow convergence of the density probability distribution at this low temperature. We also discuss strategies for improving the convergence rate under these conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800143n
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4533–4541[article] Comparing the use of gibbs ensemble and grand-canonical transition-matrix Monte Carlo methods to determine phase equilibria [texte imprimé] / Andrew S. Paluch, Auteur ; Vincent K. Shen, Auteur ; Jeffrey R. Errington, Auteur . - 2008 . - p. 4533–4541.
Bibliogr. p. 4541
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4533–4541
Mots-clés : Gibbs ensemble GC-TMMC methods Molecular fluids Résumé : We present results from a computational study investigating the use of Gibbs ensemble and grand-canonical transition-matrix Monte Carlo (GC-TMMC) methods to determine the liquid−vapor phase coexistence properties of pure molecular fluids of varying degrees of complexity. The molecules used in this study were ethane, n-octane, cyclohexane, 2,5-dimethylhexane, 1-propanol, and water. We first show that the GC-TMMC method can reproduce Gibbs ensemble results found in the literature. Given the excellent agreement for each molecule, we then compare directly the performance of Gibbs ensemble and GC-TMMC simulations at both low and high reduced temperatures by monitoring the relative uncertainties in the saturation properties as a function of computational time. In general, we found that the GC-TMMC method yielded limiting uncertainties in the saturated vapor density and pressure that were significantly smaller, by an order of magnitude in some instances, than those of the Gibbs ensemble method. Limiting Gibbs ensemble uncertainties for these properties were generally in the 0.8−5.0% range. However, both methods yielded comparable limiting uncertainties in the saturated liquid density, which fell within the range of 0.1−1.0%. In the case of water at 300 K, we found that the Gibbs ensemble outperformed GC-TMMC. The relatively poor performance of the GC-TMMC method in this situation was tied to the slow convergence of the density probability distribution at this low temperature. We also discuss strategies for improving the convergence rate under these conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800143n Exemplaires
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Titre : Artificial neural approach for modeling the heat and mass transfer characteristics in three-phase fluidized beds Type de document : texte imprimé Auteurs : Farouq S. Mjalli, Auteur ; A. Al-Mfargi, Auteur Année de publication : 2008 Article en page(s) : p. 4542–4552 Note générale : Bibliogr. p. 4551-4552 Langues : Anglais (eng) Mots-clés : Fluidized bed three-phase reactors Heat transfer Mass Artificial neural network Résumé : The study of reactor design and modeling is conducted frequently both at the initial stage of equipment design as well as during further stages of equipment operation. Fluidized bed three-phase reactors have very complex behavior which relies to a high extent on the mass and heat transfer characteristics of the reaction constituents. Numerous previous experimental and theoretical based studies for modeling heat and mass transfer coefficients have the common shortcoming of low prediction efficiency compared to experimental data. In this work, an artificial neural network approach is used to capture the reactor characteristics in terms of heat and mass transfer based on published experimental data. The newly developed heat and mass transfer coefficients models proved to be of high prediction quality compared to experimental data and previous correlations. The new correlations will be used in a further study for the hybrid steady state and dynamic modeling of fluidized bed catalytic reactors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0715714
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4542–4552[article] Artificial neural approach for modeling the heat and mass transfer characteristics in three-phase fluidized beds [texte imprimé] / Farouq S. Mjalli, Auteur ; A. Al-Mfargi, Auteur . - 2008 . - p. 4542–4552.
Bibliogr. p. 4551-4552
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4542–4552
Mots-clés : Fluidized bed three-phase reactors Heat transfer Mass Artificial neural network Résumé : The study of reactor design and modeling is conducted frequently both at the initial stage of equipment design as well as during further stages of equipment operation. Fluidized bed three-phase reactors have very complex behavior which relies to a high extent on the mass and heat transfer characteristics of the reaction constituents. Numerous previous experimental and theoretical based studies for modeling heat and mass transfer coefficients have the common shortcoming of low prediction efficiency compared to experimental data. In this work, an artificial neural network approach is used to capture the reactor characteristics in terms of heat and mass transfer based on published experimental data. The newly developed heat and mass transfer coefficients models proved to be of high prediction quality compared to experimental data and previous correlations. The new correlations will be used in a further study for the hybrid steady state and dynamic modeling of fluidized bed catalytic reactors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0715714 Exemplaires
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Titre : Numerical analysis of a pilot-scale fixed-bed reactor for dimethyl ether (DME) synthesis Type de document : texte imprimé Auteurs : Daesung Song, Auteur ; Wonjun Cho, Auteur ; Gibaek Lee, Auteur ; Dal Keun Park, Auteur Année de publication : 2008 Article en page(s) : p. 4553–4559 Note générale : Bibliogr. p. 4559 Langues : Anglais (eng) Mots-clés : Dimethyl ether Reactor simulation Numerical analysis Résumé : Dimethyl ether (DME, CH3OCH3) is the simplest of ethers and is considered one of the leading candidates in the quest for a substitute for petroleum-based fuels. In this work, we analyzed the one-step synthesis of DME in a shell-and-tube type fixed-bed reactor. We have conducted simulations using a one-dimensional steady-state model of a heterogeneous catalyst bed. This model considered heat and mass transfer between the catalyst pellets and reactants and the effectiveness factor of the catalysts, together with the reactor cooling through the reactor tube wall. The reactor simulation was carried out under steady-state conditions. Thereafter, we compared the data of simulation results with the data obtained from the operation of a pilot-scale reactor and found acceptable agreement between the two data sets. Moreover, we analyzed effectiveness factors of the catalyst pellet and along the length of the reactor where we also analyzed temperature profiles and concentrations of the components. The analyses showed that complex reactions, when coupled with pore diffusion within the catalyst pellets, result in unusual values of the effectiveness factor along the length of the reactor. Given these results, the reactor demonstrated high performance for such variables as CO conversion and DME yield. On the contrary, operations over a high temperature range are unavoidable even though this type of reactor has been in general use. Eventually more effective cooling strategies in the operation of this type of reactor should be developed and studied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071589e
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4553–4559[article] Numerical analysis of a pilot-scale fixed-bed reactor for dimethyl ether (DME) synthesis [texte imprimé] / Daesung Song, Auteur ; Wonjun Cho, Auteur ; Gibaek Lee, Auteur ; Dal Keun Park, Auteur . - 2008 . - p. 4553–4559.
Bibliogr. p. 4559
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4553–4559
Mots-clés : Dimethyl ether Reactor simulation Numerical analysis Résumé : Dimethyl ether (DME, CH3OCH3) is the simplest of ethers and is considered one of the leading candidates in the quest for a substitute for petroleum-based fuels. In this work, we analyzed the one-step synthesis of DME in a shell-and-tube type fixed-bed reactor. We have conducted simulations using a one-dimensional steady-state model of a heterogeneous catalyst bed. This model considered heat and mass transfer between the catalyst pellets and reactants and the effectiveness factor of the catalysts, together with the reactor cooling through the reactor tube wall. The reactor simulation was carried out under steady-state conditions. Thereafter, we compared the data of simulation results with the data obtained from the operation of a pilot-scale reactor and found acceptable agreement between the two data sets. Moreover, we analyzed effectiveness factors of the catalyst pellet and along the length of the reactor where we also analyzed temperature profiles and concentrations of the components. The analyses showed that complex reactions, when coupled with pore diffusion within the catalyst pellets, result in unusual values of the effectiveness factor along the length of the reactor. Given these results, the reactor demonstrated high performance for such variables as CO conversion and DME yield. On the contrary, operations over a high temperature range are unavoidable even though this type of reactor has been in general use. Eventually more effective cooling strategies in the operation of this type of reactor should be developed and studied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071589e Exemplaires
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Titre : Synthesis of methyl N-phenyl carbamate from aniline and dimethyl carbonate over supported zirconia catalyst Type de document : texte imprimé Auteurs : Fang, Li, Auteur ; Jing Miao, Auteur ; Yanji Wang, Auteur ; Xinqiang Zhao, Auteur Année de publication : 2008 Article en page(s) : p. 4560–4560 Note générale : Bibliogr. p. 4560 Langues : Anglais (eng) Note de contenu : Additions and corrections of Volume 45 N° 14
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4560–4560[article] Synthesis of methyl N-phenyl carbamate from aniline and dimethyl carbonate over supported zirconia catalyst [texte imprimé] / Fang, Li, Auteur ; Jing Miao, Auteur ; Yanji Wang, Auteur ; Xinqiang Zhao, Auteur . - 2008 . - p. 4560–4560.
Bibliogr. p. 4560
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4560–4560
Note de contenu : Additions and corrections of Volume 45 N° 14 Exemplaires
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