Highly efficient NH3-SCR of NOx over MnFeW/Ti catalyst at low temperature: SO2 tolerance and reaction mechanism. (1st January 2022)

• Record Type: Journal Article
• Authors: Liu, Lijun; Su, Sheng; Chen, Dezhi; Shu, Tao; Zheng, Xiaotao; Yu, Jiuyang; Feng, Yu; Wang, Yi; Hu, Song; Xiang, Jun
• Is Part Of: Fuel. Volume 307(2022)
• Publication Date: 2022-01-01
• Subjects: MnFeW/Ti catalyst -- NH3-SCR of NOx -- Low temperature -- SO2 resistance -- Reaction mechanism; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2021.121805
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: The facile transport of oxygen and electron is due to the formation of Mn-O-W and Fe-O-W bonds. The appropriate surface acidity and redox property was achieved. The SCR reaction mechanism is changed due to the variation of surface acidity. The transfer of electrons from SO2 to Mn 4+ and Fe 3+ was inhibited. SO2 adsorption was suppressed due to the competitive adsorption of NH3 . Abstract: The W modified MnFe/Ti composite oxide catalyst was proposed and tested for low-temperature SCR of NO x by NH3, which possesses excellent SCR activity, N2 selectivity and SO2 tolerance compared with MnFe/Ti catalyst. The physicochemical properties of MnFeW/Ti catalyst were comprehensively characterized by N2 physisorption, XRD, Raman, XPS, NH3 -TPD and H2 -TPR. The transport of oxygen and electron became more facile during SCR reaction as a result of the formation of Mn-O-W and Fe-O-W bonds, which was beneficial to maintain the Mn 4+, Fe 3+ and chemisorbed oxygen at high relative concentrations and thus accelerated the SCR reaction rate. The appropriate acidity and redox property improved NO x conversion and N2 selectivity. The in situ DRIFTS results suggested that the surface acidity was tuned via the W doping, leading to that the SCR reaction obeys only Eley − Rideal mechanism. The TG-MS results and DRIFTS spectra revealed that the oxidation of SO2 can be inhibited by restraining the transfer of electrons from SO2 to Mn 4+ and Fe 3+, which reduced the formation of metal sulfates. Therefore, the MnFeW/Ti catalyst exhibits strong SO2 tolerance at low temperature.