Enhanced activity of tungsten modified CeO2/TiO2 for selective catalytic reduction of NOx with ammonia

A series of W-doped CeO2/TiO2 catalysts prepared by different impregnation methods assisted with ultrasonic energy were investigated for the selective catalytic reduction (SCR) of NOx (NO and NO2) by NH3. The activity of the CeO2/TiO2 catalyst was enhanced by the addition of W with all the methods, while the promotional effect was pronounced for catalyst prepared by co-impregnation method. The catalytic activity of 10% CeO2/TiO2 (CeTi) was greatly enhanced by the addition of 6% WO3 in the broad temperature range of 200–500 °C. BET, XRD, XPS and TPD methods revealed that the co-impregnation method could make CeO2 and WO3 crystallites disperse better over the catalyst surface, and much stronger interaction happened between Ce and W for the more appearance of Ce3+. The addition of tungsten could bring more ad-NOx and ad-NH3 adsorption species, and simultaneously enhanced the catalytic activity for NH3-SCR of NOx.