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