Active sites adjustable phosphorus promoted CeO2/TiO2 catalysts for selective catalytic reduction of NOx by NH3

Highly-efficient CeO2/TiO2-based catalyst is an attractive alternative to traditional V2O5 -based catalysts for selective catalytic reduction of NOx by NH3 (NH3-SCR). Herein, we construct an efficient and stable P-doped CeO2/TiO2 (yCeTi-P-x) catalyst by dispersing CeO2 on strongly acidic and highly stable mesoporous P-doped TiO2 (Ti-P-x). The characteristic structure of Ti-P-x causes highly dispersed CeO2, strong active component-support interaction, and abundant surface active oxygen and acid sites on CeTi-P catalyst. Therefore, yCeTi-P-x catalyst exhibits much higher catalytic activity than yCeTi catalyst at temperature of 200-450 degrees C. The yCeTi-P-x catalysts show high activity in the presence of H2O and strong resistance to H2O + SO2 at medium-high temperature, implying that they have great industrial application prospects. Different P/Ti ratio and CeO2 loading content were investigated. Excessive P doping can block the Ce4+/Ce3+ redox couple, and suppress redox sites on yCeTi-P-x catalyst. Additionally, increasing CeO2 content can reduce the NH3 capacity of yCeTi-P-x catalyst. By controlling the P/Ti ratio and CeO2 loading content, surface acid sites and redox sites on yCeTi-P-x catalyst can be balanced to obtain the best catalytic activity. This work demonstrates a feasible method in adjusting acid sites and redox sites on CeTi catalyst, which ultimately contributes to the new design of CeO2/TiO2-based catalyst.