Synergistic catalytic removals of NO, CO and HC over CeO₂ modified Mn-Mo-W-O_x/TiO₂-SiO₂ catalyst

A series of Mn-Mo-W-O_x/TiO₂-SiO₂ catalysts was modified with CeO₂ using an extrusion molding method. The catalytic activities of the obtained catalysts were tested for the synergistic catalytic removals of CO, NO and C₃H₈. The ratio of catalyst composition on catalytic activities for NH₃-SCR was optimized, which reveals that the molar ratio of Ti/Si was 9:1 and the catalyst containing 1.5 wt% CeO₂ and 12 wt% Mn-Mo-W-O_x exhibits the best catalytic performances. These samples were characterized by XRD, N₂-BET, Py-IR, NH₃-TPD, SEM/element mapping, H₂-TPR and XPS, respectively. Results show that the optimal catalyst exhibits more than 99% NO conversion, 86% CO conversion and 100% C₃H₈ conversion under GHSV of 5000 h⁻¹. In addition, the GHSV has little influence on removal of NO when it is less than 15,000 h⁻¹. Furthermore, the addition of CeO₂ will enhance the surface acidity, increase Mn⁴⁺ concentration and inhibit the grain growth, which are favorable for the excellent catalytic performance. Anyway, the 1.5 wt% CeO₂-12 wt% Mn-Mo-W-O_x/TiO₂-SiO₂ possesses outstanding redox properties, abundant acid sites and high Mn⁴⁺ concentration, which provide a guarantee for synergistic catalytic removal of CO, NO and HC.