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

Abstract

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.