Functional distinction of different components in SmCeMn/Ti catalytic system for NH3-SCR

Abstract

Active components play different roles in improving catalytic performance due to their different physicochemical properties. In multicomponent catalysts, different components provide the possibility of multiple structures and catalytic feasibility, but the role played by specific components in improving performance becomes confusing. This work synthesized a series of SmCeMn/Ti catalysts with different metal components exposed on the outer surface to study their catalytic roles for NH3-SCR. For the contribution of different components to the catalytic activity, Mn contributes more B-acid sites and Mn4+, facilitating NO conversion. Ce generates a large amount of Mn4+ through a strong redox reaction with Mn3+ and generates abundant oxygen vacancies during the reaction process due to its strong oxygen storage-release capacity, and Sm acts as a sacrifice site for electron transfer with Mn to improve the sulfur resistance. Further investigations show that the three components have different adsorption behaviors for reactant gas and thus provide various catalytic feasibility. This work establishes a specific catalytic model for Sm, Ce, and Mn species, respectively, which provides experimental guidance to improve activity and sulfur resistance by active component control.