A relationship between the V4+/V5+ ratio and the surface dispersion, surface acidity, and redox performance of V2O5–WO3/TiO2 SCR catalysts

A series of V2O5–WO3/TiO2 catalysts with different vanadium loading amounts were prepared by an impregnation method and were characterized by XRD, Raman spectroscopy, XPS, DRIFTS, Py-DRIFTS, NH3-TPD, H2-TPR, etc. The results show that the catalytic activity is related to the ratio of V4+/V5+. The variation of the V4+/V5+ ratio caused by the different dispersion states of vanadia oxide leads to changes in the surface acidity and redox properties of the catalysts. As the V4+/V5+ ratio reaches the maximum value, the apparent activation energy (Ea) required to form the transition state on the Brønsted acid sites is the lowest. Artificial regulation of vanadium loading to properly increase V4+/V5+ content may affect the interactions between V, W, O and Ti atoms, which enhances NH3-SCR reaction performance.