Methane combustion over palladium catalysts with manipulated aggregation on zirconia support

Zirconia supported palladium catalysts were synthesized in the inert solvent by an in-situ reduction route. The preparative parameters, such as the reducing agents and the way of pre-nucleation, were regulated for the purpose of tuning the interaction between the support and the active metal (SMI). When a high dispersion of palladium is obtained by reducing agent of 1,2-hexadecanediol, a strong SMI between the active metal and zirconia is built up. This depresses the catalytic performance of the Pd/PdOx composite active phase for methane combustion. Conversely, the ratio of palladium species (Pd/PdOx) is apt to be optimized in the case of sample reduced by 2,5-di-tert-butyl-p-diphenol (DTBHQ). Furthermore, the catalysts involved a pre-nucleation step will result in a much weaker SMI, which leads to a decrease of catalytic activity for methane combustion. It is proved that an appropriate SMI is a key factor for the oxidation activity of supported palladium catalysts. The reduction of palladium component by 2,5-di-tert-butyl-p-diphenol (DTBHQ) launched until 200 °C. This would result in an active phase (Pd/PdOx) with less strong metal-support interaction (SMSI). Therefore, the ignition temperature of the methane oxidation is lowered by 100 °C.