Constructing a Core-Shell Cu-SSZ-13@High-Silica-SSZ-13 Catalyst via Surface Self-Assembly to Boost Activity and Hydrothermal Stability

Developing ammonia selective-catalytic-reduction (NH3-SCR) catalysts that combine excellent activity with hydrothermal stability remains a major challenge in controlling NOx emissions from diesel engines. In this study, a Cu-SSZ-13@high-silica-SSZ-13 catalyst with a core-shell structure was successfully synthesized via a simple surface self-assembly strategy. Characterization results confirmed that a high-silica SSZ-13 shell uniformly encapsulated the outer surface of the Cu-SSZ-13 core, with a thickness of approximately 50 nm. Performance evaluation demonstrated that CuZ@SSZ exhibited superior low-temperature NO conversion and remarkable hydrothermal stability after aging compared with Cu-SSZ-13. The core-shell catalyst contained a higher content of Z-CuOH species, which enhanced low-temperature NH3-SCR activity. Furthermore, the hydrophobic high-silica shell effectively shielded the catalyst core from water vapor attack, suppressing framework dealumination and preventing active copper aggregation into inactive CuOx species during hydrothermal aging. This study presents an effective homoepitaxial core-shell design strategy for highly efficient NH3-SCR catalysts.