Study on Effect and Mechanism of Alkaline Earth Metal Poisoning on Cu/SSZ-13 Catalysts for Selective Catalytic Reduction of NO_<i>x</i> with NH₃

Abstract

In order to study the poisoning effect of the alkaline earth metal on Cu/SSZ-13 and reveal the poisoning mechanism, Cu/SSZ-13 zeolite catalysts were synthesized by the ion-exchange method and poisoned by different concentrations of Mg and Ca. The results of SCR tests and characterizations showed that the SCR activity of Cu/SSZ-13 catalysts decreased obviously after Mg or Ca poisoning, which is because Mg and Ca reduced the Cu2+ species and Brønsted acid sites in Cu/SSZ-13, while increasing the content of CuxOy. Furthermore, Mg and Ca on the catalyst surface could block the pores of the zeolite and then decrease the specific surface area of the catalysts, and Ca could further cause partial collapse of the zeolite skeleton. Through this article, the effect and mechanism of alkali earth metal poisoning of Cu/SSZ-13 were revealed, which provided data and theory support for the development of efficient Cu/SSZ-13 NH3-SCR catalysts with high alkali earth metal resistance.