A relationship between the V(4+)/V(5+) ratio and the surface dispersion, surface acidity, and redox performance of V(2)O(5)–WO(3)/TiO(2) SCR catalysts

A series of V(2)O(5)–WO(3)/TiO(2) catalysts with different vanadium loading amounts were prepared by an impregnation method and were characterized by XRD, Raman spectroscopy, XPS, DRIFTS, Py-DRIFTS, NH(3)-TPD, H(2)-TPR, etc. The results show that the catalytic activity is related to the ratio of V(4+)/V(5+). The variation of the V(4+)/V(5+) 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 V(4+)/V(5+) ratio reaches the maximum value, the apparent activation energy (E(a)) required to form the transition state on the Brønsted acid sites is the lowest. Artificial regulation of vanadium loading to properly increase V(4+)/V(5+) content may affect the interactions between V, W, O and Ti atoms, which enhances NH(3)-SCR reaction performance.