Effect of oxidation states of vanadium precursor solution in V2O5/TiO2 catalysts for low temperature NH3 selective catalytic reduction

Abstract

In this study, we aimed at finding the optimum condition to prepare V2O5/TiO2 catalyst for the selective catalytic reduction with NH3 (NH3-SCR) by changing oxidation states in vanadium precursor solution. Using three precursor solutions with different oxidation states (V3+, V4+ and V5+), TiO2 supported V2O5 catalysts (1, 3, 5 and 7wt%) were prepared by applying wet impregnation method. We utilized various analytical techniques, such as N2 adsorption–desorption with BET method, inductively coupled plasma (ICP), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS) and temperature programmed reduction with hydrogen (H2 TPR) to investigate the physicochemical properties of V2O5/TiO2 catalysts. In addition, the SCR reactivity of these catalysts was evaluated to obtain a structure-activity relationship. It was found that V2O5/TiO2 catalysts prepared from the precursor solution of V3+ oxidation state (VT(3+)) has good activity over wide temperature range and selective to N2 production, respectively. Also, they produced the least amount of N2O during SCR reaction, which is beneficial from the view point of greenhouse gas emission. The superiority of low temperature Such desirable reaction behavior of the VT(3+) catalyst is attributed to the formation of highly coordinated polymeric vanadyl species on the sample.