Highly Efficient Mesoporous V2O5/WO3–TiO2 Catalyst for Selective Catalytic Reduction of NOx: Effect of the Valence of V on the Catalytic Performance

Mesoporous WO3–TiO2 support was synthesized by hydrothermal method, mesoporous V2O5/WO3–TiO2 catalyst was synthesized by impregnation method and used for selective catalytic reduction (SCR) of NOx with a excellent NOx conversion at a wider operating temperature ranging from 200 to 460 °C. In the range of 260–440 °C, NOx conversion reached to 98.6%, and nearly a complete conversion. Even with the existence of 300 ppm SO2, NOx conversion was only a little decline. The catalyst was characterized by a series of techniques, such as XRD, BET, XPS, TEM, Raman and H2-TPR. It was concluded that V2O5/WO3–TiO2 catalyst was ascribe to antase TiO2, and also the high crystallinity of anatase TiO2 could improve the SCR performance. More interested, V2O5/WO3–TiO2 catalyst exhibited the typical mesoporous structure according to the BET results. In addition, the TEM results indicated that the active components of V and W were well-dispersed on the surface of TiO2, while the enhancement of dispersion could improve the activity of catalysts. More importantly, the concentration ratio of V4+/(V5+ + V4+ + V3+) performed the key role in improving the activity of V2O5/WO3–TiO2 catalyst.