Catalytic partial oxidation of methane to synthesis gas over Ni-based catalysts - I. Catalyst performance characteristics

The catalytic partial oxidation of methane to synthesis gas was studied over various Ni-based catalysts. It was found that, in contrast to conventional Ni catalysts which show continuous deactivation with time on stream, the Ni/La2O3 catalyst exhibits good activity and excellent stability, using the stoichiometric ratio of CH4/O-2 (=2). Kinetic results indicate that the reaction over the Ni/La2O3 catalyst follows mainly the sequence of total oxidation to CO2 and H2O, followed by reforming reactions to synthesis gas, while CO formation via the direct route is observed at very low oxygen partial pressures. Chemisorption and FTIR studies show that the enhanced stability of the Ni/La2O3 catalyst is related to decoration of the Ni crystallites with lanthanum species, primarily oxycarbonates, which favor removal of excess carbon deposition and impart the catalyst its stability characteristics. (C) 1998 Academic Press.