Inhibition of Cu-SSZ-13 for NH 3 Selective Catalytic Reduction by K/Na Poisoning

Cu/SSZ-13 is considered to be a promising material for NH 3 -SCR catalysts. However, in practical applications, Cu/SSZ-13 is inevitably exposed to alkali metal deposition. In this paper, Cu/SSZ-13 molecular sieve catalysts were prepared by the ion exchange method, catalysts with different degrees of alkali metal K/Na poisoning were prepared by the wet-impregnation method, and the SCR activity and N 2 selectivity of fresh and poisoned catalysts were compared. The effects of alkali ion (Na + and K + ) poisoning on the comprehensive properties of Cu/SSZ-13 were studied. The distribution and quantity of Cu 2+ active components in the catalyst before and after poisoning and the change of acidic sites were explored using NH 3 -TPO, NH 3 -TPD, H 2 -TPR, BET, and XRD. The characteristics of crystal structure, specific surface area, and pore structure revealed the influence of the loading of alkali metal K/Na on the adsorption performance, weakened redox characteristics, and a certain degree of structural damage of Cu/SSZ-13 molecular sieve catalyst. It explains that the reason for the decline in catalyst performance after poisoning is due to the decrease in the number of active sites caused by the ion-exchange between alkali metal ions and Cu 2+ and H + , the increase of Cu x O y species, the decrease of acidic sites, and pore blockage. This provides data support and theoretical basis for the design of highly resistant Cu/SSZ-13 catalysts. Graphical Abstract