Effective Nitric Oxide Reduction Over Core-Shell Cu-SSZ-13@meso-MOx Catalysts with Significant Catalytic Activity and Hydrothermal Stability

Abstract

In this study, Cu-SSZ-13 zeolites are successfully coated with mesoporous metal oxides (CeO₂ , Fe₂ O₃ , TiO₂ and SiO₂ ) and prepared as core-shell Cu-SSZ-13@meso-MO_x samples with hierarchical pore structure. Compared with Cu-SSZ-13, the catalytic activity and hydrothermal stability of the Cu-SSZ-13@meso-MO_x have been greatly improved. The promoting effect of meso-MO_x shell on the catalytic activity of Cu-SSZ-13 is mainly attribute to the presence of both microporous and mesoporous structures, the formation of more active isolated Cu²⁺ ions and more L-acid sites, and the synergistic effect between Cu-SSZ-13 and meso-MO_x interaction. Moreover, all the Cu-SSZ-13@meso-MO_x catalysts maintain their activities to a greater extent after hydrothermal aging. The core-shell structure may play a protective role and greatly improve the hydrothermal stability of Cu-SSZ-13. More L-acidic sites and more isolated Cu²⁺ ions are preserved under the protection of mesoporous structure.

Keywords: core-shell structures; heterogeneous catalysis; mesoporous materials; microporous materials; zeolites.