Low-Dose Element-Doped CeCrM/TiO₂ (M = La, Cu, Fe, LaCu, LaFe) Catalyst for Low-Temperature NH₃-SCR Process:...

A series of CeCrM/TiO₂ (M = La, Cu, Fe, LaCu, LaFe) catalysts were prepared via impregnation method and are employed as low-temperature NH₃-SCR catalysts. The present study investigates the low-dose element doping on the TiO₂-supported catalyst to improve the NH₃-SCR performance. And CeCrLaCu/TiO₂ exhibited the best catalytic performance (NO conversion approaching 100% at 260-420 °C). The characterization results show that the synergistic effect of LaCu and LaFe on the catalytic performance was more obvious than that of Cu, Fe, and La alone. The doping of LaCu/LaFe decreased the specific surface area of the catalyst but increased the dispersion, surface acidity, and reducibility of the catalyst. Moreover, LaCu/LaFe promoted the formation of valence state distribution and oxygen vacancy content on the surface of the catalyst. There were more Ce³⁺, Cr⁶⁺, Cu⁺, and oxygen adsorbed on the surface of the CeCrLaCu/TiO₂ catalyst. H₂-TPR analysis showed that the synergistic effect of LaCu was more likely to promote the reduction of Cr and Cu and increase the reduction degree of metal oxides. However, Fe is easier to coordinate with La, thus improving the redox performance of the catalyst. Compared with CeCrLaFe/TiO₂, the ammonia adsorption capacity of CeCrLaCu/TiO₂ is better. Therefore, the synergistic effect of LaCu can promote the reaction performance of NH₃-SCR better.