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 degr ees C and as a function of the partial pressures of oxygen and methane (12-90 kPa). All catalysts are stable in oxygen containing atmosphere s, while oxygen starvation causes destructive reduction to Ni metal fo r x > 0.5. The catalytic activity increases monotonically with the val ue of x. The nonseparable (composition, temperature) kinetics behavior is well correlated by an oxidation-reduction mechanism for all cataly sts. Based on the observed nonlinear increase in catalytic activity wi th nickel content, Ni-O-Ni ensembles are proposed as the key surface r eagent. (C) 1997 Academic Press.