Methane combustion on La2O3-based catalysts has been studied by Toops et al. [46]. With a 4% Sr-promoted La2O3 catalyst (2:5m2g-1) operating between 773 and 973 K, 0:5 -5 Torr CH4 and 3 _ 23 Torr O2 (760 Torr 1 atm) under differential reactor conditions, an apparent activation energy of 29 kcal mole-1 for CO2 formation was observed. Near 900 K, selectivity to CO2, rather than CO, was about 75% or higher, and the reaction orders from a power rate law are given in Table 1. Propose a L-Htype model for CO2 formation with a sequence of elementary steps that results in a derived rate expression consistent with these results. It can be assumed that only the adsorbed reactants and products need be included in the site balance, and dissociative O2 adsorption occurs. Under low-conversion conditions, the surface concentrations of the products can be ignored, so what is the form of the rate equation? Fitting this latter equation to the data produced the optimized rate parameters listed in Table 2, where k0 is the lumped apparent rate constant. Evaluate them to determine if they are consistent and state why.