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 V2O5-WO3 (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)(2)-Ti4+ 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 N-2 selectivity in the NH3-SCR reaction. In the future study, this specific edge shared Fe3+-(O)(2)-Ti4+ 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. (C) 2012 Elsevier B. V. All rights reserved.