Pd loaded on high silica beta support active for the total oxidation of diluted methane in the presence of water vapor

Total oxidation of diluted methane was carried out over palladium loaded on H-beta and H-ZSM-5 having different Al concentration in order to reveal the support effect of zeolites. It was found that the Al concentration had significant influence on the methane combustion activity of Pd. Especially, Pd loaded on H-beta having the lowest concentration of Al exhibited the most striking performance in that it showed superior durability and the highest activity in the presence of 10% water vapor. In marked contrast to the zeolite-supported Pd catalysts, Pd loaded on SiO2 was substantially inactive under the same reaction conditions. Based on the Pd K-edge EXAFS coupled with TG analysis, the reason for the superior nature of high silica H-beta was attributed to the hydrophobic character of supports and the formation of agglomerated PdO, which was active in the methane combustion.