An XAFS study on the specific microstructure of active species in iron titanate catalyst for NH3-SCR of NOx

Environmental-friendly iron titanate (FeTiOx) catalyst is a potential candidate for the substitution of conventional V2O5WO3 (MoO3)/TiO2 catalyst for the selective catalytic reduction of NOx with NH3 (NH3-SCR) for the NOx elimination from stationary and mobile sources for environmental protection. To understand in-depth the nature of active structure in this FeTiOx catalyst for further catalyst redesign and activity improvement, the study of X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine-structure spectroscopy (EXAFS) combined with theoretical calculation is carefully performed. Different from the crystal structure of hematite Fe2O3, homogeneous edge shared Fe3+(O)2Ti4+ structure in FeTiOx catalyst prepared from Ti(SO4)2 precursor is obviously formed with crystallite phase, which shows the electronic inductive effect between Fe3+ and Ti4+ species, resulting in the high NO adsorption and oxidation ability of Fe3+ species and thus high catalytic activity and N2 selectivity in the NH3-SCR reaction. In the future study, this specific edge shared Fe3+(O)2Ti4+ structure can be stabilized onto certain catalyst supports with large surface area for practical use, such as the catalytic removal of NOx from flue gas and diesel engine exhaust.

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► Environmentally benign iron titanate catalyst FeTiOx for NH3-SCR of NOx.
► Specific microstructure of FeTiOx determined by XANES and EXAFS methods.
► Homogeneous Fe3+(O)2Ti4+ structure with edge shared linkage in crystallite phase.
► Electronic inductive effect between Fe3+ and Ti4+ species leading to higher oxidation ability of Fe3+.
► A promising catalyst for NOx removal from coal-fired power plants or diesel engine exhaust.