Study on Effect and Mechanism of Alkaline Earth Metal Poisoning on Cu/SSZ-13 Catalysts for Selective Catalytic Reduction of NO _x with NH₃

In order to study the poisoning effect of the alkalineearth metalon Cu/SSZ-13 and reveal the poisoning mechanism, Cu/SSZ-13 zeolitecatalysts were synthesized by the ion-exchange method and poisonedby different concentrations of Mg and Ca. The results of SCR testsand characterizations showed that the SCR activity of Cu/SSZ-13 catalystsdecreased obviously after Mg or Ca poisoning, which is because Mgand Ca reduced the Cu2+ species and Bronsted acidsites in Cu/SSZ-13, while increasing the content of Cu x O y . Furthermore, Mg andCa on the catalyst surface could block the pores of the zeolite andthen decrease the specific surface area of the catalysts, and Ca couldfurther cause partial collapse of the zeolite skeleton. Through thisarticle, the effect and mechanism of alkali earth metal poisoningof Cu/SSZ-13 were revealed, which provided data and theory supportfor the development of efficient Cu/SSZ-13 NH3-SCR catalystswith high alkali earth metal resistance.