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

Zhao, Xuteng, Yan, Yongyi, Mao, Lei, Fu, Maochen, Zhao, Hairui, Sun, Lvsheng, Xiao, Youhong, Dong, Guojun
RSC advances 2018 v.8 no.54 pp. 31081-31093
Bronsted acids, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, acidity, activation energy, catalysts, catalytic activity, vanadium
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.