Preparation and Catalytic Performance of Pd Monolithic Catalysts Supported by Y2O3 Washcoat

A novel Y2O3 washcoat adhered to the cordierite honeycomb was prepared using Y(NO3)3 as the precursor. The Y2O3 washcoat is suitable for supported Pd catalysts. Catalytic combustion of toluene and ethyl acetate was conducted as model reactions to evaluate the performance of Pd/Y2O3 catalysts. The catalysts exhibit fairly good catalytic activity and thermal stability. For the catalysts calcined at 500°C, the T99 of toluene is 210°C. The Y2O3 washcoat and the Pd/Y2O3 catalysts were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, and H2-temperature-programmed reduction. The results show that the washcoat has sufficient adhesion and high adsorption efficiency for active species. For the catalysts calcined at higher temperatures (700 and 900°C), the crystallite size of the active species (PdO) increases, which possibly results in a decline in the catalytic activity.