Comparative study of Ce-Nb-Ti oxide catalysts prepared by different methods for selective catalytic reduction of NO with NH3.

[Display omitted] • CeNbTi oxide catalysts were synthesized by impregnation, co-precipitation and solid process methods. • The CeNbTi catalyst prepared by impregnation showed the superior NH 3 -SCR activity and better resistance to K 2 O and SO 2. • The surface acidity and redox ability of the CeNbTi catalyst prepared by impregnation were enhanced. • CeNbTi catalyst prepared by impregnation could accelerate the reaction of pre-adsorbed NH 3 /NO x and pre-adsorbed NO x /NH 3. Ce-Nb-Ti metal oxide catalysts (CeNbTi) were synthesized for NH 3 -SCR by impregnation (IM), co-precipitation (CP) and solid process (SP) methods and characterized by various techniques. The results of NH 3 -SCR activity evaluations showed that CeNbTi-IM possessed the superior NH 3 -SCR performance in different gas hourly space velocity and better resistance to SO 2 and potassium. The characterization results showed that the CeNbTi-IM catalyst had relatively high concentrations of Ce3+ and chemisorbed oxygen, strong synergistic effect among different components and well dispersed active species. More importantly, the catalyst had stronger reduction capacity and a large number of Lewis acid sites, which contributed to its excellent catalytic performance. The in situ DRIFTS results revealed that the impregnation method was beneficial to the adsorption of weakly adsorbed NO 2 , bidentate nitrate and NH 3 species. In addition, it was revealed that the reaction paths over CeNbTi-IM, CeNbTi-CP and CeNbTi-SP obeyed both Langmuir-Hinshel wood and Eley-Rideal mechanisms, but the impregnation method could accelerate the reaction between pre-adsorbed ammonia/NO x species and NO x species/ammonia. [ABSTRACT FROM AUTHOR]