Complete Catalytic Oxidation of Methane and Ethane Over Supported Platinum, Palladium and Manganese Oxide Catalysts

Abstract

Activities of Pt, Pd and Pt + Pd catalysts (metal concentrations ≤ 0.4%) supported on γ-A1₂O₃ and on TiO₂ (anatase) for the complete oxidation of methane (300 ppmv) in air have been measured as a function of temperature; values of T₁₀, T₅₀ and T₉₀ 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 γ-Al₂O3, contrary to literature reports, but on both supports the Pt + Pd mixture is much more active than either metal separately, T₁₀ for Pt + Pd/γ-Al₂O₃ being as low as 228°C. Possible reasons for this are briefly considered.

Activities of MnO₂ on SnO₂, y-Al₂O₃ and TiO₂ (anatase) (̃ 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, T₁₀ being only 256°C.

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.