Reforming of methane with carbon dioxide over Ni/Al2O3 catalysts: Effect of nickel precursor

The catalytic activities of Ni/gamma-Al2O3 catalysts prepared using different nickel precursor compounds were studied for the reaction of methane reforming with CO2. It is found that the nickel precursor employed in the catalyst preparation plays an important role. The catalyst based on nickel nitrate exhibited higher catalytic activity and stability over a 24-h test period than the other two catalysts derived from nickel chloride and nickel acetylacetonate. A comprehensive characterisation of the catalysts showed that the weak interaction between Ni particles and gamma-Al2O3 resulted in more active sites on Ni nitrate-derived Ni/gamma-Al2O3 catalyst. Coking studies showed that carbon deposition on Ni catalysts derived from inorganic precursors (nitrate and chloride) were more severe than on the organic precursor-derived catalyst. However, the Ni nitrate-derived catalyst was found to have the highest stability (or lowest deactivation rate) mainly due to the active carbon species (-C-C-) of the resulting graphitic structure and their close contact with the metal particles. In contrast, the carbon formed on Ni-AA catalyst (from Ni acetylacetonate) is dominated by inactive -CO-C- species, thus leading to a rapid accumulation of carbon in this catalyst and more severe deactivation. (C) 1998 Elsevier Science B.V