Investigation Of Reaction Performance Over Modified Ce-Ti Mixed Oxide Catalysts For Selective Catalytic Reduction Of NO

With the rapid development of China's economy and the acceleration of industrialization, the consumption of fossil fuel continues to increase, and the emission of NOx increases year by year. Ammonia Selective catalytic reduction (NH3-SCR) is considered as the most effective technology for removal of NOx. Therefore, how to synthesis catalysts with low toxicity, high activity and a wide temperature window has arised increasingly attention in the field of denitration. Different molar ratios of Mo and Al doped Ce-Ti catalysts have been prepared by co-precipitation and impregnation method. Activity and physical chemical properties of catalysts were investigated through Brunauer-Emmertt-Teller (BET), X-ray Photoelectron Spectroscopy (XPS), H2-Temperature Program (H2-TPR) and In situ FTIR characterization. The research results are as follows:(1) The Mo-Ce-Ti mixed oxide catalysts were synthesized by wet impregnation method, and the influence of Mo content on NH3-SCR activity was also investigated. The NOx conversion of 2.5%Mo-Ce-Ti was above 90% in the temperature range of 200?440?. Compared with Ce-Ti catalyst, the Mo doping to Ce-Ti increased the redox ability and the amount of adsorbed oxygen species on the catalyst surface, thus promoted the NH3-SCR activity.(2) Under the condition of proper reaction temperature, In situ FTIR was used to investigate the NH3-SCR reaction mechanism of Mo-Ce-Ti catalyst. the Mo doping to Ce-Ti increased the amount of NH3 on Lewis and Br(?)nsted acid sites and adsorbed NH2 on catalyst surface. NH2 reacted with NO to form NH2NO, which finally transformed into N2 and H2O. The mechanism on the 2.5%Mo-Ce-Ti catalyst mainly followed the E-R mechanism.(3) The Ce-Al-Ti mixed oxide catalysts were synthesized by impregnation and coprecipitation method. By comparison, the NOx conversion of Ce/Al1Ti3 was above 95% in the temperature range of 200?475?. The Al doping to Ce-Ti increased the surface area, the amount of surface oxygen and redox activity sites, which was facilitated to the reaction.(4) Under the condition of proper reaction temperature, In situ FTIR was used to investigate the NH3-SCR reaction mechanism of Ce/Al1Ti3 catalyst. The Al doping to Ce-Ti increased the amount of NH3 on Br(?)nsted acid sites, which easily increased ammonia adsorption on the catalyst surface. The bidentate nitrate and the intermediate (-NH2) were the main active species in the NH3-SCR reaction. This reaction pathway makes a significant contribution to improve NO conversion for the Al doping to Ce-Ti. The mechanism on the Ce/Al1Ti3 catalyst followed E-R mechanism.