Improved surface acidity of CeO₂/TiO₂ catalyst by Cu doping to enhance the SCR catalytic activity

The catalyst is based on CeO₂ cannot be widely used in SCR reaction because of its poor NH₃ adsorption performance. In this study, Cu-doped CeTi catalyst was designed. The results show that the CeTiCu0.3 has a wide active temperature window of 200-450 °C in NH₃-SCR reaction, and NO conversion is > 80%. This is mainly due to the fact that Cu doping provides more acidic sites on the surface of CeTi catalyst, especially the increase of Lewis acid sites is more obvious. NH₃-TPD showed that CeTiCu0.3 had a large NH₃ adsorption capacity and was mainly adsorbed at Lewis acid sites. In situ DRIFTs results show that NH₃ first adsorbs on the Lewis acid site of catalyst in coordination state and reacts with gaseous NO_x, while NO_x adsorbed on catalyst surface has low reactivity. Therefore, the CeTiCu0.3 catalyst is mainly controlled by the Eley-Rideal mechanism. More Lewis acid sites, and abunda nt Cu²⁺/Cu⁺ and Ce⁴⁺/Ce³⁺ formed Cu²⁺, Ce³⁺ and surface reactive oxygen species are the main reasons for the excellent catalytic performance of CeTiCu.