Influence of Calcination Temperature on Dechlorination Performance of V2O5/CNTs-TiO2 Catalysts

Carbon nanotubes (CNTs) pretreated with concentrated HNO3 and tetrabutyl titanate were used as raw materials to prepare CNTs-TiO2 composite supports by the sol-gel method. Vanadium was then dipped into the CNTs-TiO2 composite support to synthesize the V2O5/CNTs-TiO2 catalyst. The influence of calcination temperature on the active species of the catalyst and the catalytic oxidation performance for degradation of hexachlorobenzene (HCB) were investigated. The synthesized catalysts were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and ultraviolet-visible (UV-Vis) spectroscopy. The surface chemical properties were analyzed by X-ray photoelectron spectroscopy (XPS). The results indicated that the modified carbon nanotubes have high purity and graphitization degree. The effect of calcination temperature on the active components and the activity of the catalyst were investigated. The results showed that calcination at 450 degrees C favored the dispersion of the active species of the catalyst and the formation of catalytic oxidation valences of V5+ and Ti4+ in the V2O5/CNTs-TiO2 catalyst. The presence of V5+ and Ti4+ increased the concentration of the surface oxygen of the catalyst, resulting in a higher catalytic activity because of promotion of the electron mobility and oxygen transfer: 94.78% of HCB can be conversed with a loading of 0.2 g of the catalyst in an atmosphere of N-2 (80%) + O-2 (20%) at 250 degrees C. The conversion of HCB remained above 90% during a 24 h batch test, which showed a stable catalytic performance.