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Comparison of nanosized gold-based and copper-based catalysts for the low-temperature water-gas shift reaction / Diogo Mendes in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 430-439 Titre : Comparison of nanosized gold-based and copper-based catalysts for the low-temperature water-gas shift reaction Type de document : texte imprimé Auteurs : Diogo Mendes, Editeur scientifique ; Hermenegildo Garcia, Editeur scientifique ; V. B. Silva, Editeur scientifique Année de publication : 2009 Article en page(s) : P. 430-439 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Water-gas  Gold  and  copper  Electron  microscopy  CO2  and  H2 Résumé : In this paper the catalytic performances for the low-temperature water−gas shift reaction of Au/TiO2 type A (from World Gold Council), Au/CeO2 (developed at UPV-CSIC), CuO/Al2O3 (from BASF), and CuO/ZnO/Al2O3 (from REB Research & Consulting) have been compared. The catalysts were characterized by different techniques such as Raman spectroscopy, BET surface area measurements, temperature-programmed reduction, and high-resolution transmission electron microscopy, which gave additional information on the redox properties and textural and morphological structure of the investigated samples. The performances of these catalysts were evaluated in a wide range of operating conditions in a micro packed-bed reactor. It was observed that the presence of reaction products in the feed (CO2 and H2), as well as CO and H2O feed concentrations, have significant effects on the catalytic performances. With a typical reformate feed the Au/CeO2 catalyst reveals the highest CO conversion at the lowest temperature investigated (150 °C). However, while in the long tests performed the CuO/ZnO/Al2O3 catalyst showed a good stability for the entire range of temperatures tested (150−300 °C), the Au/CeO2 sample clearly showed two distinct behaviors: a progressive deactivation at lower temperatures and a good stability at higher ones. The selection of the best catalytic system is therefore clearly dependent upon the range of temperatures used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010676 [article] Comparison of nanosized gold-based and copper-based catalysts for the low-temperature water-gas shift reaction [texte imprimé] / Diogo Mendes, Editeur scientifique ; Hermenegildo Garcia, Editeur scientifique ; V. B. Silva, Editeur scientifique . - 2009 . - P. 430-439. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 430-439 Mots-clés : Water-gas  Gold  and  copper  Electron  microscopy  CO2  and  H2 Résumé : In this paper the catalytic performances for the low-temperature water−gas shift reaction of Au/TiO2 type A (from World Gold Council), Au/CeO2 (developed at UPV-CSIC), CuO/Al2O3 (from BASF), and CuO/ZnO/Al2O3 (from REB Research & Consulting) have been compared. The catalysts were characterized by different techniques such as Raman spectroscopy, BET surface area measurements, temperature-programmed reduction, and high-resolution transmission electron microscopy, which gave additional information on the redox properties and textural and morphological structure of the investigated samples. The performances of these catalysts were evaluated in a wide range of operating conditions in a micro packed-bed reactor. It was observed that the presence of reaction products in the feed (CO2 and H2), as well as CO and H2O feed concentrations, have significant effects on the catalytic performances. With a typical reformate feed the Au/CeO2 catalyst reveals the highest CO conversion at the lowest temperature investigated (150 °C). However, while in the long tests performed the CuO/ZnO/Al2O3 catalyst showed a good stability for the entire range of temperatures tested (150−300 °C), the Au/CeO2 sample clearly showed two distinct behaviors: a progressive deactivation at lower temperatures and a good stability at higher ones. The selection of the best catalytic system is therefore clearly dependent upon the range of temperatures used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010676

Determination of the low - temperature water − gas shift reaction kinetics using a cu - based catalyst / Diogo Mendes in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11269–11279 Titre : Determination of the low - temperature water − gas shift reaction kinetics using a cu - based catalyst Type de document : texte imprimé Auteurs : Diogo Mendes, Auteur ; Vania Chibante, Auteur ; Adelio Mendes, Auteur Année de publication : 2011 Article en page(s) : pp. 11269–11279 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Gas  Kinetics Résumé : An integral packed-bed reactor was used to determine the kinetics of the water−gas shift (WGS) reaction over a CuO/ZnO/Al2O3 catalyst, under operating conditions such that there was no film or intraparticle resistance. Experiments were carried out over a wide range of temperatures and space times using a typical reformate gas mixture (4.70% CO, 34.78% H2O, 28.70% H2, 10.16% CO2, balance N2). In the first part of the work, three different mechanistic-rate equations and two empirical kinetic models are proposed to describe the WGS kinetic data throughout the entire range of temperatures. To improve the independence of the parameters in using the Arrhenius and van’t Hoff equations, the temperature was centered. Good agreement was obtained between the Langmuir−Hinshelwood (LH) rate equations and the experimental results. Further, analysis using two different temperature ranges for parameter estimation revealed distinct rate-controlling mechanisms for each range. For temperatures of 180−200 °C, the associative (LH) mechanism was predominant, whereas the redox pathway showed the best fit to the experimental reaction rates in the range of 230−300 °C. Finally, an isothermal plug-flow reactor model was used to simulate the packed-bed tubular reactor for the WGS reaction using the composed kinetics. The reactor model was assessed against the experimental CO outlet concentration, and satisfactory agreement was found between the model predictions and the experimental results. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101137b [article] Determination of the low - temperature water − gas shift reaction kinetics using a cu - based catalyst [texte imprimé] / Diogo Mendes, Auteur ; Vania Chibante, Auteur ; Adelio Mendes, Auteur . - 2011 . - pp. 11269–11279. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11269–11279 Mots-clés : Gas  Kinetics Résumé : An integral packed-bed reactor was used to determine the kinetics of the water−gas shift (WGS) reaction over a CuO/ZnO/Al2O3 catalyst, under operating conditions such that there was no film or intraparticle resistance. Experiments were carried out over a wide range of temperatures and space times using a typical reformate gas mixture (4.70% CO, 34.78% H2O, 28.70% H2, 10.16% CO2, balance N2). In the first part of the work, three different mechanistic-rate equations and two empirical kinetic models are proposed to describe the WGS kinetic data throughout the entire range of temperatures. To improve the independence of the parameters in using the Arrhenius and van’t Hoff equations, the temperature was centered. Good agreement was obtained between the Langmuir−Hinshelwood (LH) rate equations and the experimental results. Further, analysis using two different temperature ranges for parameter estimation revealed distinct rate-controlling mechanisms for each range. For temperatures of 180−200 °C, the associative (LH) mechanism was predominant, whereas the redox pathway showed the best fit to the experimental reaction rates in the range of 230−300 °C. Finally, an isothermal plug-flow reactor model was used to simulate the packed-bed tubular reactor for the WGS reaction using the composed kinetics. The reactor model was assessed against the experimental CO outlet concentration, and satisfactory agreement was found between the model predictions and the experimental results. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101137b