High-valent W-doped CeO₂ regulates Cu-Cd-SSZ-13 for enhancing NH₃-SCR performance

The design of highly active catalysts for the selective catalytic reduction of NO_x with NH₃ (NH₃-SCR) is necessary but challenging. Herein, a composite catalyst constructed by hexavalent W-doped CeO₂ oxide supported on Cu-Cd-SSZ-13 (W-CeO₂/Cu-Cd-SSZ-13) is synthesized using an in situ hydrothermal synthesis technique. The temperature range of NO conversion over 90% (T₉₀) for W-CeO₂/Cu-Cd-SSZ-13 is expanded to 160-610 °C, compared with 160-550 °C for Cu-Cd-SSZ-13. After the hydrothermal aging process, the NO conversion of W-CeO₂/Cu-Cd-SSZ-13-A is 25.2% and 74.5% at 100 °C and 640 °C, respectively, while that of Cu-Cd-SSZ-13-A is 6.8% and 49.4%. Thus, the NO conversion of W-CeO₂/Cu-Cd-SSZ-13-A is nearly 18.4% and 25.1% higher than that of Cu-Cd-SSZ-13 at 100 and 640 °C, respectively. Experimental results reveal that the introduction of W-doped CeO₂ significantly enhances the redox properties and acidity of Cu-Cd-SSZ-13, attributed to the presence of more Ce³⁺, isolated Cu²⁺ and adsorbed oxygen species. Notably, the loading of W-doped CeO₂ on Cu-Cd-SSZ-13 inhibits the dealumination of the zeolite framework and prevents the aggregation of Cu species, contributing to its excellent hydrothermal stability. This work provides insight into designing Cu-based zeolites with outstanding NH₃-SCR performance.