Interface Engineering of a Bifunctional Cu-SSZ-13@CZO Core-Shell Catalyst for Boosting Potassium Ion and SO2 Tolerance

The poisoning of sulfur oxides and alkali metals emitted from diesel exhaust to active sites of copper ion-exchanged chabazite (Cu-CHA) catalysts is still present and remains a formidable challenge in practical application. Herein, a bifunctional core-shell structural Cu-SSZ-13@Ce0.75Zr0.25O2 (Cu-SSZ-13@CZO) catalyst was designed and fabricated via a hydrothermally induced self-assembly protocol, and the catalytic activity of Cu-SSZ-13@CZO for selective catalytic reduction (SCR) of nitrogen oxides (NOx) with ammonia was systematically investigated. It unveils that Cu-SSZ-13@CZO features Cu-SSZ-13 as the core and dispersed CZO as the shell and that the CZO shell could not only serve as a sacrificial site protecting the Cu-SSZ-13 active core from SO2 poisoning by the formation of Ce-2(SO4)(3), which could further act as adsorption sites capturing the K+ through the strong interaction between K+ and cerium sulfate, but also render additional Bronsted acid sites functioning as sacrificial sites to trap K+, thereafter inhibiting the adsorption of K+ directly on active Cu species in the Cu-SSZ-13 core. As a result, the as-constructed Cu-SSZ-13@ CZO catalyst, therefore, exhibits perceptibly enhanced coresistance to sulfur and potassium ion poisoning with almost 100% NOx conversion in the temperature window of 275-475 ? as compared to 350-450 ?on pristine Cu-SSZ-13. The finding here may contribute to the fundamental understanding of the coresistance to sulfur oxides and alkali metal poison and thereafter inspire the advancement of a highly efficient NH3-SCR catalyst in the future.

Automated summary

A bifunctional core-shell Cu-SSZ-13@CZO catalyst was designed and fabricated, which showed enhanced resistance to sulfur and potassium ion poisoning compared to pristine Cu-SSZ-13. The Cu-SSZ-13 core was protected from poisoning by the CZO shell, resulting in improved catalytic activity for selective catalytic reduction of nitrogen oxides.