Abstract: 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 ℃, the T99of toluene is 210 ℃. The Y2O3 washcoat and the Pd/Y2O3 catalysts were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy,X-raydiffraction, 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 ℃), the crystallite size of the active species (PdO) increases, which possibly results in a decline in the catalytic activity.

Key words: yttria washcoat, cordierite monolithic catalyst, palladium, toluene, ethyl acetate, catalytic combustion