A general strategy for design SCR catalysts with enhanced resistance to multiple poisons through constructing highly dispersed paired acid-base sites

Abstract

The complex composition of solid waste in co-processing within industrial kilns leads to the coexistence of multiple poisons in flue gas, which accelerates the deactivation of SCR catalysts. In this work, solid superacid modified CeO₂ with highly dispersed acid-base sites was constructed, achieving the capture of acidic/basic poisons. Moreover, the designed catalyst retained active sites for the adsorption and activation of NH₃ after poisoning. The sulfated ZrO₂/CeO₂ exhibited 2.0, 1.1, 2.3, 1.2, and 2.6-fold increase of NO_x conversion than commercial V₂O₅-WO₃/TiO₂ when Pb, As, Zn, K, and Cd loading. The highly dispersed monodentate sulfate species on the catalyst surface provided abundant acid sites for the capture of basic poisons (e.g., Cd, Pb, K, Zn) and NH₃ adsorption. The basic CeO₂ doped with Zr captured acidic poisons (e.g., As) and promoted the activation of NH₃ due to the high capacity of Ce^3 + and oxygen vacancies. Spectroscopic characterization revealed that the highly dispersed acid-base sites along with more Ce³⁺ species on the catalyst surface facilitated the adsorption and activation of NH₃, crucial for the formation of the reaction intermediate NH₂NO. This work may provide an approach to develop efficient SCR catalysts with superior resistance to poisons and reduce the generation of waste catalysts.