Mesoporous CoO-supported palladium nanocatalysts with high performance for o-xylene combustion

Abstract

The Pd-based catalysts have been widely studied for the combustion of volatile organic compounds, in which the roles of the Pd and the support are still not known clearly. In this study, mesoporous Co₃O₄ and CoO (i.e., meso-Co₃O₄ and meso-CoO) were prepared and used as support for the loading of Pd nanoparticles (NPs). The supported Pd samples performed much better than the supports for o-xylene combustion, in which the Pd/meso-CoO sample showed the best catalytic activity (T_90% = 173 °C), giving rise to reaction rates at 170 °C 3.5 and 84 times higher than those over the Pd/meso-Co₃O₄ and meso-CoO samples, respectively. It has been established that the meso-CoO sample possessed strong ability to activate oxygen molecules to the active oxygen species, the loaded Pd NPs in a metallic Pd phase was beneficial for o-xylene adsorption, and the adsorbed o-xylene species could immediately react with the active oxygen species at the interface between Pd NPs and meso-CoO. Therefore, we conclude that the excellent catalytic performance of the Pd/meso-CoO sample was associated with its highly active Pd–CoO interface.