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4052383 
Journal Article 
Catalytic reforming of methane with carbon dioxide over nickel catalysts .2. Reaction 
Bradford, MCJ; Vannice, MA 
1996 
1 
Applied Catalysis A: General
ISSN: 0926-860X
EISSN: 1873-3875 
Elsevier 
142 
1 
97-122 
WOS:A1996UZ78000008 
The reforming of methane with carbon dioxide was studied over nickel supported on SiO2, TiO2, MgO and activated carbon. Specific activities on a turnover frequency basis were in the order: Ni/TiO2 > Ni/C > Ni/SiO2 > Ni/MgO. Interestingly, a 2-fold increase in activation energy for this reaction was observed over Ni/TiO2 after several hours time on stream. The reverse water-gas shift reaction was found to be close to thermodynamic equilibrium over all catalysts. Partial pressure dependencies were obtained with the Ni/C and Ni/SiO2 catalysts at 723 K for comparative purposes only, but a more thorough kinetic analysis was made with the Ni/MgO and Ni/TiO2 catalysts, which were shown previously to strongly inhibit carbon deposition. Partial pressure dependencies were obtained at 673, 698, and 723 K for Ni/TiO2 and at 773, 798, and 823 K for Ni/MgO. In situ DRIFTS studies clearly showed the presence of both Linear and bridged carbon monoxide adsorption on Ni/SiO2 under reaction conditions; however, adsorbed carbon monoxide could not be identified on Ni/TiO2. A reaction model for CH4-CO2 reforming, based on CH4 activation to form CHx and CHxO decomposition as the slow kinetic steps, successfully correlated the rate data. 
kinetics; methane; carbon dioxide; reforming; nickel; titania; silica; magnesium oxide; carbon