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

Abstract

The design of highly active catalyst for selective catalytic reduction of NOx 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 created by in‑situ hydrothermal synthesis technique. The NO conversion of W-CeO2/Cu-Cd-SSZ-13 is 99.2% and 94.2% at 160 ℃ and 610 ℃, the temperature range of NO conversion over 90% for W-CeO2/Cu-Cd-SSZ-13 is expanded to 160-610 ℃. After hydrothermal aging process, the NO conversion of W-CeO2/Cu-Cd-SSZ-13-A is 25.2% and 74.5% at 100 ℃ and 640 ℃, while the Cu-Cd-SSZ-13-A is 6.8% and 49.4%, so the NO conversion of W-CeO2/Cu-Cd-SSZ-13-A is nearly 18.4% and 25.1% higher than Cu-Cd-SSZ-13 at 100 and 640 ℃. Experimental results reveal the introduction of W-doped CeO₂ significantly enhance the redox property and acidity of Cu-Cd-SSZ-13 attributed to the presence of more Ce3+, isolated Cu2+ and adsorbed oxygen species. Noteworthy, the loading of W-doped CeO2 on Cu-Cd-SSZ-13 inhibits the dealumination of zeolite framework and prevents the aggregation of Cu species, contributing to its excellent hydrothermal stability. This work provides an insight for designing Cu-based zeolite with outstanding NH3-SCR performance.