Abstract: CeO2-ZrO2 and 10%WO3/CeO2-ZrO2 catalysts were characterized by NH3 temperature-programmed desorption, H2-temperature-programmed reduction, and X-ray photoelectron spectroscopy. Their activity in the selective catalytic reduction (SCR) of NOx with NH3 was compared. The results show that the promotion effect of WO3 may be related to the increase of acidity and redox properties of the catalyst. CeO2-ZrO2 shows less than 65% and 10%WO3/CeO2-ZrO2 shows more than 80%NOx conversion in the temperature range of 220-420 ℃ at NH3/NO=1 and space velocity of90000h-1. The addition of 10%H2O and 10%CO2 decreases the catalyst activity at low temperature by competitive adsorption on the catalyst surface and improves the NOx conversion at high temperature. The CeO2-ZrO2 catalyst shows less than 46% and the 10%WO3/CeO2-ZrO2 catalyst shows more than 80%NOx conversion in the temperature range of 230-500 ℃.

Key words: tungsta, ceria, zirconia, nitrogen oxide, ammonia, selective catalytic reduction