Effect of Ti~(4+) and Sn~(4+) co-incorporation on the catalytic performance of CeO_2-MnO_x catalyst for low temperature NH_3-SCR

摘要

A novel Ti4+ and Sn4- co-incorporated CeO2-MnOx based catalyst was synthesized by an inverse co-precipitation method with the purpose of inhibiting the formation of N2O and enhancing the NOx conversion of CeO2-MnOx catalyst for NH3-SCR at low temperature. The obtained catalysts were characterized by a series of XRD, Raman, N-2-physisorption, NH3-TPD, H-2-TPR, XPS, and in situ DRIFTS techniques in details. The experiment results suggested that CeO2-MnOx-TiO2-SnO2 (Ce-Mn-Ti-Sn) catalyst displayed the optimal catalytic performance with an enhancement of 30% compared with CeO2-MnOx(Ce-Mn) in the range of 225-275 degrees C. Moreover, the N2O formation was inhibited remarkably compared to Ce-Mn (152 ppm), and there was no N2O (0 ppm) detected even at 250 degrees C. This is linked to moderate weakening of redox property, more generation of acid sites, enhancement of acidic strength, as well as large amount of Ce3+, oxygen vacancies, and absorbed oxygen species, which are contributed to improving the chemical property of Ce-Mn-Ti-Sn catalyst, and further enhancing the catalytic performance and inhibiting the generation of N2O.