Acid pretreatment effect on the physicochemical property and catalytic performance of CeO2 for NH3-SCR

A series of CeO2 pretreated with different acids (i.e., CH3COOH (HAc), HNO3, HCl, H3PO4, and H2SO4) were prepared with the purpose of exploring the influence of acid pretreatment on the physicochemical property and catalytic performance of CeO2 for NH3-SCR. And then, these catalysts were characterized by means of XRD, Raman, N-2-physisorption, H-2-TPR, NH3-TPD, in situ DRIFTS, XPS, and NH3-SCR reaction. The obtained results indicate that different acids pretreatment has different influence on the structure, texture, reduction behavior, surface acidity, surface property, and catalytic performance of CeO2. Especially, the sample pretreated by H2SO4 (Le., CeO2-S catalyst) exhibits the best catalytic performance for NH3-SCR reaction at high temperature among these catalysts due to the largest amount of surface acid sites (especially B acid sites) and Ce3+, as well as the increase of defect sites (such as oxygen vacancy) and the most abundant reducible species. Furthermore, CeO2-S catalyst also exhibits excellent catalytic performance (Le., above 80% NO conversion) during the whole test of H2O + SO2 resistance, which indicates that it has the potential to be applied in the practical denitration process.