Effect of Ce doping into V2O5-WO3/TiO2 catalysts on the selective catalytic reduction of NOx by NH3

In this work, the effectiveness of VO-WO/TiOcatalysts modified with different CeOcontents by impregnation and co-precipitation methods on the selective catalytic reduction of NOxby NH3 have been studied comparatively by various experimental techniques. The results showed that the NO conversion of VO-WO/CeO-TiOcatalysts modified by co-precipitation method obviously increased with the Ce doping contents in the studied range below 20%(All Ce contents are in mass fractions), but the NO conversion of VO-WO/CeO/TiOcatalysts modified by impregnation methods was lower than VO-WO/CeO-TiOcatalysts especially beyond 2.5% Ce doping contents. The VO-WO/CeO-TiOcatalysts showed better SCR activity, wider reaction window, and higher sulfur and water resistance. The characterization results elucidated that the modified catalysts by co-precipitation method exhibited higher specific surface area, much better dispersity of Ce component, more Cespecies and more Br?nsted acid sites than that by impregnation. The vacancies caused by more Cespecies were favorable for more NO oxidation to NO, and the interaction between Ce species and WOxspecies generated more Br?nsted acid sites. It could be supposed that dispersed Ce Oxspecies and WOxspecies offered more second active centers respectively to adsorb oxygen and activate ammonia as co-catalysis to the primary active center of V ions, thus facilitated the better SCR activity of modified VO-WO/CeO-TiOcatalysts by coprecipitation methods. The co-precipitation methods with Ce component were more suitable for production of modified commercial VO-WO/TiOcatalysts.