Abstract: A novel CeO2-Y2O3 (denoted as CeY) washcoat adhered to the cordierite honeycomb was prepared. The preparation technique, using nano-sized CeO2 and yttrium citrate as precursors, was friendly to environment because no deleterious products were formed during the operation. The CeY washcoat support and Pd/CeY catalysts were characterized using scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray fluorescence (XRF) spectrometer, and Raman spectroscopy. The results showed that the washcoat had sufficient adhesion and high adsorption efficiency for active species and was suitable for supporting Pd catalysts. For the catalysts, most of Y2O3 entered into the channel of the cordierite honeycomb, whereas CeO2 and Pd enriched on the surface. Furthermore, model reactions for the catalytic combustion of CO, toluene, and ethyl acetate were carried out to evaluate the performance of the Pd/CeY catalyst. It exhibited fairly good catalytic activity and thermal stability. For those catalysts calcined at 500℃, the T99 (the lowest reaction temperature when the conversion is 99%) of CO, toluene, and ethyl acetate was 150, 220, and 310 ℃, respectively, whereas for those catalysts calcined at 1050 ℃, the T99 of CO, toluene, and ethyl acetate was 180, 250, and 330 ℃, respectively. Catalysts calcined at higher temperature, the crystallite size of active species (PdO) increases, which possibly results in a decline in the catalytic activity.

Key words: CeO2-Y2O3 washcoat, Pd catalyst, Cordierite honeycomb substrate, Catalytic combustion