Elaborating the Key Role of Oxygen Vacancies for Enhancing the Reactivity and So2 Resistance of Cew/Fe-Tio2 Catalysts in Low-Temperature Nh3-Scr Reaction

Abstract

At present, the low temperature reactivity and against SO2 poisoning performance of environmentally friendly Ce-based catalysts in NH3-SCR reaction is still the main factor for practical application. Herein, in this work, Fe3+ was introduced into the TiO2 lattice with hydrothermal method and substituted for part of Ti4+ to form oxygen deficient structure in the Fe-TiO2 carrier, and active species CeW were loaded onto this defective carrier to test its catalytic performance. It was demonstrated that CeW/Fe-TiO2 catalyst with higher oxygen vacancy content exhibited better low temperature catalytic activity and superior resistance against SO2 poisoning in NH3-SCR reaction. On the one hand, Ov was able to optimize the electronic structure of the catalyst with electron enrichment in the Fe-Ov-Ti structural unit and electron transfer to surface Ce atom via oxygen vacancies, thus improving the chemical environment around Ce species. On the other hand, Ov effectively adsorbed and activated oxygen and reactant molecule, and the NH3-SCR reaction proceeded through L-H pathway, thus improving the low temperature performance of the CeW/Fe-TiO2 catalyst. Eventually, DFT results confirmed at the molecular level that the construction of oxygen vacancy defective structures effectively activated the reactant molecules and thus improved the catalyst efficiency.

Keywords: Electron enrichment, Activate reactant molecules, Regulate electronic structures, NH3-SCR reaction