Highly Active And Stable Palladium Catalysts Supported On Surface-Modified Ceria Nanowires For Lean Methane Combustion

An efficient strategy was presented to synthesize highly active palladium catalyst supported on ceria nanowires modified by organosilanes (abbreviated as Pd/CeO(2)NWs@SiO2) for lean methane combustion. It is found that such a surface-modified strategy can significantly improve the dispersion of surface palladium species and strengthen the concentration of active surface-adsorbed oxygen species via reconstructing the surface microenvironment, invoking an efficient performance for methane oxidation. Under the space velocity of 60,000 mLg(-1)h(-1), 0.5 wt% Pd/CeO(2)NWs@SiO2 displayed extraordinary catalytic activity with 90 % conversion rate at a temperature of around 327 degrees C, far lower than that of pristine Pd/CeO(2)NWs (378 degrees C) under the same conditions. What's more, unexpected stability was observed under high temperature and the presence of water vapor conditions owing to the intense metal support interaction of Pd/CeO(2)NWs@SiO2 catalyst. The possible reaction mechanism of lean methane oxidation was probed by in situ DRIFT spectra. It is observed that the pivotal intermediate products (carbonate and carbon oxygenates) generated on Pd/CeO(2)NWs@SiO2 surface are more readily decomposed into CO2. Importantly, the silicon hydroxyl groups (Si-OH) formed during the reaction can efficiently restrict the generation of the stable Pd(OH)(x) phase and release more active sites to facilitate the catalytic performance. This study provides a convenient method to design the highly reactive and durable palladium-based catalyst for methane combustion.