Nb2O5-modified Mn-Ce/AC catalyst with high ZnCl2 and SO2 tolerance for low-temperature NH3-SCR of NO

Zinc salts and SO2 would cause Mn-Ce/AC catalyst poisoning, reducing the service life of the catalyst. In this study, the effects of Nb2O5 on the tolerance of ZnCl2 and SO2 over Mn-Ce/AC catalyst were studied by the characterization results of BET, SEM, XRD, H2-TPR, NH3-TPD, TG and XPS. It indicated that doping Nb2O5 could effectively enhance the SCR performance and N2 selectivity of Zn-Mn-Ce/AC catalyst. Meanwhile, Nb2O5 could significantly improve the SO2 poisoning resistance of Zn-Mn-Ce/AC catalyst when sulfur dioxide was added into the reaction system. Nb2O5 could react with SO2 in a preferential way to restrain the sulfuration of manganese and cerium oxides on the catalyst. More importantly, Nb2O5 reacted with SO2 to form Nb sulfate and then formed a new acidic site on the Zn-Mn-Ce/AC catalyst surface, which promoted the adsorption of NH3 and inhibited the adsorption of SO2, then restricted the reaction between NH3 and SO2 and hindered the formation of ammonium sulfate channels. [Display omitted] •Nb2O5 could effectively improve the SCR activity of Zn-Mn-Ce/AC catalyst.•Nb2O5 could effectively improve the N2 selectivity of Zn-Mn-Ce/AC catalyst.•Nb2O5 could improve anti-SO2 poisoning performance of Zn-Mn-Ce/AC catalyst.•Nb2O5 increased the redox ability, surface acidity, surface chemisorbed oxygen and Mn4+ content of Mn-Ce/AC catalyst.