Unveiling H <sub>2</sub> O <sub>2</sub> ‐optimized NO <sub> <i>x</i> </sub> adsorption‐selective catalytic reduction (AdSCR) performance of WO <sub>3</sub> /CeZrO <sub>2</sub> catalyst
Yan Huang, Shuang Liu, Mingming Pei, Jiayi Li, Haidi Xu, Yaoqiang Chen
Abstract
Abstract Recently, NO x emissions in the cold‐start period have been a great challenge in eliminating diesel vehicle exhaust. In this study, a type of NO x adsorption‐selective catalytic reduction (AdSCR) bifunctional catalyst was developed to remove NO x in the cold‐start period by constructing additional NO x adsorption sites on the surface of the selective catalytic reduction of NO x with NH 3 catalyst. The AdSCR catalyst exhibited both NO x adsorption–storage performance and NH 3 ‐SCR activity. The amount of oxygen vacancies directly affected the adsorption performance of NO x on the catalyst surface. In this study, H 2 O 2 with different pH values was employed to adjust the electronic structure of the CeZrO 2 support and construct oxygen vacancies on the surface of CeZrO 2 , which contributed to improving NO x adsorption and storage on the WO 3 /CeZrO 2 (W/CZ) catalyst below 200 °C. The catalytic performance results show that CZ supports modified by alkaline H 2 O 2 rather than acidic and neutral H 2 O 2 significantly improve the NO x adsorption capacity without decreasing the NH 3 ‐SCR activity. The characterization results show that the CZ support modified by alkaline H 2 O 2 possesses more surface oxygen vacancies and chemisorbed oxygen than CZ supports modified by acidic and neutral H 2 O 2 . Oxygen vacancies are not only the active sites of NH 3 ‐SCR, but also the active sites of NO x adsorption. Therefore, the W/CZ catalyst modified by alkaline H 2 O 2 exhibited an excellent AdSCR performance. This study proposes a novel perspective to address the issue of NO x emissions from diesel vehicles during the cold start period.