Lv Zhihui, Xu Guangyan, Wang Yingjie, Yu Yunbo, He Hong
State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
ACS Omega. 2024 Dec 23;10(1):358-367. doi: 10.1021/acsomega.4c06372. eCollection 2025 Jan 14.
Selective catalytic reduction of nitrogen oxides (NO ) by ammonia (NH-SCR) over supported vanadium catalysts is a commercial technology for NO abatement in combustion exhaust. The addition of tungsten oxide (WO) significantly enhances the performance of supported vanadium catalysts (VO/TiO), but the mechanism underlying this enhancement remains controversial. In this study, we employed combined operando spectroscopy (DRIFTS-UV-vis-MS) to investigate the dynamic state of active sites (acid sites and redox sites) on VO-WO/TiO during the NH-SCR reaction. Our findings confirmed that WO occupied the TiO surface and reduced the available surface sites for VO anchoring, thus promoting the agglomeration of vanadia species. This structural effect significantly improved the reducibility of VO on VO-WO/TiO catalysts, consequently enhancing the efficiency for NO reduction. The heightened reducibility rendered the reoxidation of vanadia species a rate-limiting step, resulting in the presence of vanadia species in a lower oxidation state (V) during the NH-SCR reaction.
在负载型钒催化剂上通过氨选择性催化还原氮氧化物（NO ）（NH-SCR）是一种用于减少燃烧废气中NO 的商业技术。添加氧化钨（WO）可显著提高负载型钒催化剂（VO/TiO）的性能，但其性能增强的机理仍存在争议。在本研究中，我们采用组合原位光谱（DRIFTS-UV-vis-MS）来研究NH-SCR反应过程中VO-WO/TiO上活性位点（酸性位点和氧化还原位点）的动态状态。我们的研究结果证实，WO占据了TiO表面并减少了VO锚定的可用表面位点，从而促进了钒物种的团聚。这种结构效应显著提高了VO-WO/TiO催化剂上VO 的可还原性，进而提高了NO 还原效率。增强的可还原性使钒物种的再氧化成为限速步骤，导致在NH-SCR反应过程中存在较低氧化态（V）的钒物种。
