Reaction kinetics of methane oxidation over LaCr1-xNixO3 perovskite catalysts

Ternary perovskite oxides LaCr1-xNixO3, (x = 0 to 1.0) were evaluated as methane oxidation catalysts over the temperature range 300-500 degrees C and as a function of the partial pressures of oxygen and methane (12-90 kPa). All catalysts are stable in oxygen containing atmospheres, while oxygen starvation causes destructive reduction to Ni metal for x > 0.5. The catalytic activity increases monotonically with the value of x. The nonseparable (composition, temperature) kinetics behavior is well correlated by an oxidation-reduction mechanism for all catalysts. Based on the observed nonlinear increase in catalytic activity with nickel content, Ni-O-Ni ensembles are proposed as the key surface reagent. (C) 1997 Academic Press.