Metal-Support Interactions within a Dual-Site Pd/YMn2O5 Catalyst during CH4 Combustion

Catalytic combustion is a promising technology forremoving unburnt CH4from natural gas vehicle exhaust gas underlean-burn conditions. Supported Pd catalysts are widely appliedand studied for use in CH4oxidation at <500-550 degrees C, with theiractivities significantly affected by the interactions between Pd andthe support, depending on the dispersion, Pd valence state, andproperties of the support. However, whether metal-supportinteractions are favorable in catalytic CH4oxidation is unclear.We therefore used YMn2O5as a catalytically active support toprepare a dual-site catalyst, Pd/YMn2O5, which shows high CH4catalytic activities in dry and wet atmospheres. Experimental anddensity functional theory studies reveal that the CH4adsorptionand lattice oxygen activity of the support are significantly enhanced due to the interactions between PdOxand YMn2O5. In situ X-rayphotoelectron spectroscopy shows that Pdx+(x= 2 and 4) and Mnx+(x= 3 and 4) species undergo changes during CH4oxidation.The PdOxsites are the main active sites, as the CH4activation barrier is much lower than those at other sites. YMn2O5and PdOxparticipate in CH4activation and oxidation via active oxygen transfer.

Automated summary

This study used YMn2O5 as a catalytically active support and prepared a dual-site catalyst, Pd/YMn2O5, which showed high CH4 catalytic activities in both dry and wet atmospheres. Experimental and theoretical studies revealed that the interactions between PdOx and YMn2O5 significantly enhanced the CH4 adsorption and lattice oxygen activity of the support.