In situ DRIFTS FT-IR and DFT study on Fe-V-W/Ti removal of NOx and VOCs

作者：Chen, Zhuofan; Liao, Yanfen^*; Chen, Yin; Ma, Xiaoqian

来源：Environmental Science and Pollution Research, 2022, 29(54): 81571-81582.

DOI：10.1007/s11356-022-21244-4

• SCR catalyst
• DFT
• NO
• In situ FT-IR

Nitrogen oxides (NO R ) and volatile organic compounds (VOCs) are generated during the coal-fired power plant's combustion. They can be simultaneously removed in SCR (selective catalytic reduction) region. Herein, the performance of V-W/Ti and Fe-V-W/Ti synthesized by wet impregnation in removing NOx and VOCs was evaluated. XPS (X-ray photoelectron spectroscopy) result indicated that a redox cycle of Fe2+ + V5+ (sic) Fe3+ + V4+ could form electron vacancy through electron transfer. Besides, the mechanisms of NH3-SCR and VOCs catalytic oxidation were explored with in situ DRIFTS experience and DFT calculation. On Fe-V-W/Ti, in situ DRIFTS study found more absorption sites of NH3, and different intermediates during simultaneously removal process. DFT calculation demonstrated that absorption energy of O-2 was decreased and O=O bond was lengthened with Fe doped. Both V-W/Ti and Fe-V-W/Ti followed the L-H mechanism and shared a common 1 NH4 (ads) NH3-SCR pathway: NO(g) + 1/2 O-2 (g) + e(-) -> NO2- (ads) ->( NH4+(ads)) NH4NO2(ads) -> N-2(g) + H2O(g). However, the bidentate nitrate and monodentate nitrate were also revealed on Fe-V-W/Ti, which combined with NH4+ and decomposed into N-2 and H2O, or N2O and H2O, respectively. The detected NH2 species combined with NO on the Fe-V-W/Ti, following the E-R mechanism. As for VOCs, the intermediates of benzene and toluene were revealed by in situ DRIFTS study, and detailed Mars-van Krevelen mechanism was discovered.