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, H-2-TPR, NH3-TPD, TG and XPS. It indicated that doping Nb2O5 could effectively enhance the SCR performance and N-2 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.

Automated summary

This study found that doping Nb2O5 can enhance the SCR performance and sulfur resistance of Zn-Mn-Ce/AC catalyst, form new acidic sites by preferentially reacting with SO2, promote NH3 adsorption and inhibit SO2 adsorption, which hinders the reaction between NH3 and SO2 and slows the formation of ammonium sulfate channels on the catalyst.