Kinetic study of the catalytic partial oxidation of methane to synthesis gas over Ni/La2O3 catalyst

The kinetic behavior of the Ni/La2O3 catalyst in the partial oxidation of methane was investigated as a function of temperature and of partial pressures of CH4 and O-2. It has been found that CPO reaction over the Ni/La2O3 catalyst follows mainly the sequence of total oxidation of CH4 to CO2 and H2O, followed by reforming reactions to synthesis gas, while CO formation via the direct route is possible at low oxygen partial pressures, and depends on the oxidation state of the Ni crystallites. Hysteresis phenomena, which were also observed, suggest that multiple states of the nickel surface can exist depending on the history of the catalyst. It is proposed that the reaction mechanism over the Ni/La2O3 catalyst involves adsorption of methane and oxygen on different sites, while the decomposition of CH4 into C and H and the reaction of adsorbed C and O towards CO are suggested as the rate determining steps (RDS).