Complete catalytic oxidation of methane and ethane over supported platinum, palladium and manganese oxide catalysts

Activities of Pt, Pd and Pt + Pd catalysts (metal concentrations less than or equal to 0.4%) supported on gamma-Al2O3 and on TiO2 (anatase) for the complete oxidation of methane (300 ppmv) in air have been measured as a function of temperature; values of T-10, T-50 and T-90 together with the Arrhenius parameters (activation energy and pre-exponential factor) are reported. Pt is less active than Pd when on TiO2, but more active when on gamma-Al2O3, contrary to literature reports, but on both supports the Pt + Pd mixture is much more active than either metal separately, T-10 for Pt + Pd/gamma-Al2O3 being as low as 228degreesC. Possible reasons for this are briefly considered. Activities of MnO2 on SnO2, gamma-Al2O3 and TiO2 (anatase) (similar to 7% Mn) and the supports alone for the complete oxidation of ethane (5000 ppmv) in air, together with Arrhenius parameters, have also been measured: MnO2/SnO2 shows the greatest activity, T-10 being only 256degreesC. The significance of the Arrhenius parameters, which for the metal containing catalysts exhibit compensation with increasing activation energy, and secure a more rapid increase in conversion from 0 to 100% as the temperature is raised.