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Glycerol steam reforming over bimetallic Co − Ni / Al2O3 / Cheng Chin Kui in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10804–10817 Titre : Glycerol steam reforming over bimetallic Co − Ni / Al2O3 Type de document : texte imprimé Auteurs : Cheng Chin Kui, Auteur ; Say Yei Foo, Auteur ; Adesoji A. Adesina, Auteur Année de publication : 2011 Article en page(s) : pp. 10804–10817 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Glycerol  Bimetallic Résumé : Glycerol steam reforming has been performed in a fixed-bed microreactor containing bimetallic Co−Ni/Al2O3 catalyst using a wide range of steam-to-glycerol ratios (3 ≤ STGR ≤ 12) for reaction temperatures between 773 and 823 K at atmospheric pressure. Physicochemical characterization revealed the presence of both Lewis and Brönsted acid sites on the catalyst although the catalyst appears to have a net surface acidity (acid:basic site concentration ratio = 9.0). Co and Ni oxides as well as the metal aluminates were identified from XRD pattern with crystallite size (131.5 nm) similar to that obtained from H2 chemisorption experiments (136.0 nm). Glycerol consumption rate data analysis implicates fractional orders with respect to both glycerol (0.25) and steam (0.36) with an activation energy of 63.3 kJ mol−1. Similar treatment for H2, CO2, CO, and CH4 production rate evinced positive fractional orders for both reactants with the exception of CO which has mild inhibition by steam (−0.065). Mechanistic considerations and associated Langmuir−Hinshelwood and Eley−Rideal kinetic models were derived for both single- and dual-site adsorption modes. However, statistical discrimination as well as thermodynamic evaluation of the associated parameter estimates suggest that the most adequate representation involved molecular adsorption of glycerol and steam on two different sites with surface reaction as the rate-controlling step consistent with the presence of both Brönsted acid and basic sites on the catalyst. Carbon deposition during reaction appeared to be responsible for the loss in surface area and pore volume of the used catalysts. However, these attributes were nearly recovered after regeneration (>90%) using TPR−TPO−TPR−TPO cycles. Significantly, carbon deposition is a strong function of glycerol partial pressure but somewhat insensitive to the presence of steam, suggesting that the carbon residue was probably unreactive with steam under the reaction conditions. Indeed, temperature-programmed heat treatment (TPO−TPR−TPO−TPR and TPR−TPO−TPR−TPO) revealed at least two types of carbonaceous deposits. However, one of these carbon pools was resistant to removal with H2. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100462t [article] Glycerol steam reforming over bimetallic Co − Ni / Al2O3 [texte imprimé] / Cheng Chin Kui, Auteur ; Say Yei Foo, Auteur ; Adesoji A. Adesina, Auteur . - 2011 . - pp. 10804–10817. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10804–10817 Mots-clés : Glycerol  Bimetallic Résumé : Glycerol steam reforming has been performed in a fixed-bed microreactor containing bimetallic Co−Ni/Al2O3 catalyst using a wide range of steam-to-glycerol ratios (3 ≤ STGR ≤ 12) for reaction temperatures between 773 and 823 K at atmospheric pressure. Physicochemical characterization revealed the presence of both Lewis and Brönsted acid sites on the catalyst although the catalyst appears to have a net surface acidity (acid:basic site concentration ratio = 9.0). Co and Ni oxides as well as the metal aluminates were identified from XRD pattern with crystallite size (131.5 nm) similar to that obtained from H2 chemisorption experiments (136.0 nm). Glycerol consumption rate data analysis implicates fractional orders with respect to both glycerol (0.25) and steam (0.36) with an activation energy of 63.3 kJ mol−1. Similar treatment for H2, CO2, CO, and CH4 production rate evinced positive fractional orders for both reactants with the exception of CO which has mild inhibition by steam (−0.065). Mechanistic considerations and associated Langmuir−Hinshelwood and Eley−Rideal kinetic models were derived for both single- and dual-site adsorption modes. However, statistical discrimination as well as thermodynamic evaluation of the associated parameter estimates suggest that the most adequate representation involved molecular adsorption of glycerol and steam on two different sites with surface reaction as the rate-controlling step consistent with the presence of both Brönsted acid and basic sites on the catalyst. Carbon deposition during reaction appeared to be responsible for the loss in surface area and pore volume of the used catalysts. However, these attributes were nearly recovered after regeneration (>90%) using TPR−TPO−TPR−TPO cycles. Significantly, carbon deposition is a strong function of glycerol partial pressure but somewhat insensitive to the presence of steam, suggesting that the carbon residue was probably unreactive with steam under the reaction conditions. Indeed, temperature-programmed heat treatment (TPO−TPR−TPO−TPR and TPR−TPO−TPR−TPO) revealed at least two types of carbonaceous deposits. However, one of these carbon pools was resistant to removal with H2. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100462t

Oxidative CO2 Reforming of Methane on Alumina-Supported Co−Ni Catalyst / Say Yei Foo in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10450-10458 Titre : Oxidative CO2 Reforming of Methane on Alumina-Supported Co−Ni Catalyst Type de document : texte imprimé Auteurs : Say Yei Foo, Auteur ; Chin Kui Cheng, Auteur ; Tuan-Huy Nguyen, Auteur Année de publication : 2011 Article en page(s) : pp. 10450-10458 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalyst  Reforming  Carbon  dioxide  Oxidation Résumé : CO2 reforming of CH4 in the presence of O2 in the feed has been investigated in a fixed bed reactor containing a Co-Ni catalyst. The reforming rate increased with O2 partial pressure before leveling out at O2:CH4 = 1I at temperature greater than 823 K. Although CO production decreased with O2 addition, H2 formation initially rose to a maximum before a slow decline. An expression relating the optimum O2 partial pressure for H2 production as a function of temperature was obtained as, PO2,max = 1.008 × 10―3e8420/T. The H2:CO product ratio increased from 0.9 for pure CO2 reforming and peaked at 1.73 as O2 partial pressure increased to an equimolar level in the feed. The increased reaction temperature resulted in lower H2:CO due to increased CO2 reforming kinetics. The complete consumption of O2 in the final product stream means that the oxidative CO2 reforming of CH4 may be used to generate nearly ideal syngas composition for Fischer-Tropsch synthesis if feed CO2:CH4 is unity. In particular, the overall heat demand for the reforming reaction could be reduced (or become exothermic) for a judicious combination of CO2/CH4/O2. The postreaction analysis revealed that even mild O2 dosing leads to negligible carbon deposition. Thus, this form of reactor operation is energetically attractive and provided efficient carbon utilization. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447937 [article] Oxidative CO2 Reforming of Methane on Alumina-Supported Co−Ni Catalyst [texte imprimé] / Say Yei Foo, Auteur ; Chin Kui Cheng, Auteur ; Tuan-Huy Nguyen, Auteur . - 2011 . - pp. 10450-10458. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10450-10458 Mots-clés : Catalyst  Reforming  Carbon  dioxide  Oxidation Résumé : CO2 reforming of CH4 in the presence of O2 in the feed has been investigated in a fixed bed reactor containing a Co-Ni catalyst. The reforming rate increased with O2 partial pressure before leveling out at O2:CH4 = 1I at temperature greater than 823 K. Although CO production decreased with O2 addition, H2 formation initially rose to a maximum before a slow decline. An expression relating the optimum O2 partial pressure for H2 production as a function of temperature was obtained as, PO2,max = 1.008 × 10―3e8420/T. The H2:CO product ratio increased from 0.9 for pure CO2 reforming and peaked at 1.73 as O2 partial pressure increased to an equimolar level in the feed. The increased reaction temperature resulted in lower H2:CO due to increased CO2 reforming kinetics. The complete consumption of O2 in the final product stream means that the oxidative CO2 reforming of CH4 may be used to generate nearly ideal syngas composition for Fischer-Tropsch synthesis if feed CO2:CH4 is unity. In particular, the overall heat demand for the reforming reaction could be reduced (or become exothermic) for a judicious combination of CO2/CH4/O2. The postreaction analysis revealed that even mild O2 dosing leads to negligible carbon deposition. Thus, this form of reactor operation is energetically attractive and provided efficient carbon utilization. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447937