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, H-2-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 (E-a) required to form the transition state on the BrOnsted 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.