Abstract: The TiO₂-SiO₂ composite supports with different SiO2 doping amount were prepared by co-precipitation method, and then the active components V₂O₅ and MoO₃ were loaded on these composite supports by impregnation method to prepare V-Mo/TiO₂-SiO₂ catalysts (VMTS). The physical and chemical properties of the catalysts were characterized by XRD, SEM, BET, H₂-TPR techniques. The results showed that with the increase of SiO₂ doping amount, the XRD spectra of the VMTS catalysts not only presented SiO₂ diffraction peak, but also the diffraction peak of Anatase TiO₂. The active components, V₂O₅ and MoO₃, were in the form of amorphous or microcrystalline because of relatively low content. The reduction peak of SiO₂-doped catalyst moved toward the low temperature direction in H₂-TPR graph, the specific surface area and pore volume increased while the pore diameter decreased. Compared with the other catalysts, the VMTS-(0.2∶1)with the mass ratio of SiO₂/TiO2 of 0.2 catalyst had the lowest reduction peak temperature and the largest reduction peak area as well as the best redox capacity. The results of denitration efficiency evaluation showed that VMTS-(0.2:1) catalyst had the best denitration efficiency for the flue gas. When SO₂ was introduced into the flue gas, the decrease range of denitration efficiency of V-Mo/TiO₂-SiO₂ catalyst was lower than that of the undoped catalyst and all other tested catalysts with SiO₂ doped, indicating that doping SiO₂ is beneficial to the improvement of sulfur resistance of the catalyst.

Key words: denitration, vanadium, moiybdenum, titanium oxide, silicon oxide, sulfur dioxide