Methane conversion and SO 2 resistance of LaMn 1− xFe xO 3 ( x = 0.4, 0.5, 0.6, 1) perovskite catalysts promoted with palladium

Abstract

Lanthanum perovskites were synthesized by malic acid complexation and different amounts of palladium were added by dry-wet impregnation. Measurements of methane conversion on fresh and SO 2-treated perovskite catalysts were made between 25 and 500 °C. Methane conversion on fresh catalysts commenced at ∼300 °C, and the best activities were achieved with low loadings of palladium. The B-site metal combinations Mn 0.4Fe 0.6 and Mn 0.6Fe 0.4 showed better conversion activity than Mn 0.5Fe 0.5 and Fe. All fresh perovskite catalysts except those with 10% Pd gave 100% conversion of methane at 500 °C. The resistance of 10% Pd perovskite catalysts to sulfur was generally better than that of catalysts with low Pd loadings. This was due to the high Pd coverage on the perovskite surface. Fresh and SO 2-treated LaMn 0.4Fe 0.6O 3 perovskite catalysts promoted with 2 and 2.5% of palladium exhibited the highest activities for methane conversion.