Boosting SO<sub>2</sub>-Resistant NO<sub><i>x</i></sub> Reduction by Modulating Electronic Interaction of Short-Range Fe–O Coordination over Fe<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> Catalysts
Xiangyu Liu, Penglu Wang, Yongjie Shen, Lirong Zheng, Lupeng Han, Jiang Deng, Jianping Zhang, Aiyong Wang, Wei Ren, Feng Gao, Dengsong Zhang
Abstract
SO2-resistant selective catalytic reduction (SCR) of NOx remains a grand challenge for eliminating NOx generated from stationary combustion processes. Herein, SO2-resistant NOx reduction has been boosted by modulating electronic interaction of short-range Fe–O coordination over Fe2O3/TiO2 catalysts. We report a remarkable SO2-tolerant Fe2O3/TiO2 catalyst using sulfur-doped TiO2 as the support. Via an array of spectroscopic and microscopic characterizations and DFT theoretical calculations, the active form of the dopant is demonstrated as SO42– residing at subsurface TiO6 locations. Sulfur doping exerts strong electronic perturbation to TiO2, causing a net charge transfer from Fe2O3 to TiO2 via increased short-range Fe–O coordination. This electronic effect simultaneously weakens charge transfer from Fe2O3 to SO2 and enhances that from NO/NH3 to Fe2O3, resulting in a remarkable “killing two birds with one stone” scenario, that is, improving NO/NH3 adsorption that benefits SCR reaction and inhibiting SO2 poisoning that benefits catalyst long-term stability.