Kinetics of catalytic oxidation of methane, ethane and propane over palladium oxide

Catalytic oxidation of methane, ethane and propane over a palladium oxide (PdO) surface was investigated experimentally by wire microcalorimetry. The oxidation rate was determined for each reactant at atmospheric pressure in the temperature range of 600-800. K. The apparent kinetic parameters were extracted from the experimental measurements. It is shown that the oxidation of these hydrocarbons over the PdO surface proceeds with a similar mechanism: they undergo dissociative adsorption followed by the conversion of surface fragments to final products. A detailed surface reaction model is proposed, and the kinetic parameters of the crucial reactions are deduced from the present experimental observations. The catalytic oxidation rates are found to increase in the order of methane, ethane and propane. This observation is consistent with density functional theory calculations and may be correlated with the C-H bond energies of the corresponding surface intermediates.