Pd (1 wt%)/LaMn0.4Fe0.6O3 Catalysts Supported Over Silica SBA-15: Effect of Perovskite Loading and Support Morphology on Methane Oxidation Activity and SO2 Tolerance

摘要

Catalysts of palladium (1 wt%) deposited over silica SBA-15 supported LaMn0.4Fe0.6O3 perovskite (with perovskite loading of 10, 30 and 40 wt%), characterized by several techniques (BET, SAXS, XRD, TPR) are tested in the combustion of methane. Bulk LaMn0.4Fe0.6O3 with the corresponding supported Pd catalyst are also considered for comparison purpose. Dispersing LaMn0.4Fe0.6O3 oxide over silica SBA-15 improves the activity of the supported palladium catalysts to an extent depending on the perovskite loading. After ageing at 600 °C for 14 h, Pd catalysts supported over SBA-15 loaded with 30 and 40 wt% of LaMn0.4Fe0.6O3, deactivate less as compared to Pd over bulk perovskite. Moreover, during catalytic tests carried out in the presence of 10 vol. ppm SO2 these catalysts exhibit better sulphur tolerance and higher regeneration capability as compared to the Pd/LaMn0.4Fe0.6O3. The superior performance of such catalysts is attributed to the good dispersion of the LaMn0.4Fe0.6O3 over the SBA-15, with consequent increase of the perovskite surface area with respect to bulk perovskite. In addition, the porous structure of the silica contributes to a better stabilization of the active species against sintering and acts as a chemical sink during the catalyst exposure to SO2.