Evolution of VO x on TiO 2 -ZSM-5 Composite Supports upon K Poisoning and Its Effects on Ultralow Temperature NH 3 –SCR

作者：Jiaying Li, Kaihao Fan, Yingying Jin, Yaping Yang, Changlong Zheng, Yang Gao, Letong Yang, Xuesong Liu, Xiaodong Wu · 发表于：Langmuir · 年份：2025 · DOI：10.1021/acs.langmuir.4c05011 · 被引用次数：3 · 研究领域：Catalytic Processes in Materials Science、Catalysis and Oxidation Reactions、Industrial Gas Emission Control

Compared with V 2 O 5 /TiO 2, vanadia catalysts supported on TiO 2 -ZSM-5 composite support possess excellent resistance to potassium poisoning in the selective catalytic reduction of NO by NH 3 (NH 3 –SCR). Appropriate addition of ZSM-5 (10 wt %) enhances the low-temperature activity of NH 3 –SCR with more than 80% NO x conversion at 175–450 °C, as the combination of TiO 2 and ZSM-5 is conducive to the formation of more low-valent (polymeric) VO x preferentially deposited on TiO 2 . Compared with V 2 O 5 /TiO 2, the composite support catalysts effectively shield V 2 O 5 as the main active species from K poisoning by preferential ion-exchange of K + with Brønsted acid sites (Si–O(H)–Al) of ZSM-5. According to physicochemical characterizations, the mechanism of catalyst deactivation is mainly attributed to excessive aggregation of VO x to form inactive crystalline V 2 O 5 in addition to KVO 3 . In situ diffuse reflectance infrared Fourier transform spectroscopy indicates that the presence of K leads to the formation of inactive bidentate nitrates instead of active bridged nitrates. A novel vanadium-based catalyst with high alkali poisoning resistance for ultralow temperature (<200 °C) denitration was developed.