Preparation and Denitration Performance of V-W/TiO2-SiO2 Nanotube Catalysts
2018
Zheng, Kezhi | Yang, Guohua | Shen, Weijie | Xu, Qingtao | Hu, Fuxiang | Li, Zhen
TiO₂-SiO₂ nanotubes, with high specific surface area, were prepared by hydrothermal methods using tetraethyl orthosilicate and tetrabutyl titanate as precursors. These nanotubes were used as carriers to prepare a V₂O₅-WO₃/TiO₂-SiO₂ catalyst by an impregnation method. The deNO ₓ activity of catalysts used for selective catalytic reduction (SCR) was examined as a function of the silica-to-titania molar ratio, vanadium loading, and calcination temperature. The catalyst performance was also tested in the presence of sulfur and water. The experimental results showed that the nanotube catalyst loaded with 3 wt% vanadium and a SiO₂/TiO₂ molar ratio of 2:8 exhibited the best activity after calcination at 650 °C. The NO conversion efficiency reached 100% at a gas hourly space velocity (GHSV) of 100,000 h⁻¹ over the reaction temperature range of 300–500 °C. Characterization by Brunauer–Emmett–Teller measurements, X-ray diffraction, transmission electron microscopy, temperature-programmed reduction, and temperature-programmed desorption demonstrated that formation of the nanotube structure significantly increased the specific surface area of the catalyst and that the active components exhibited high degree of dispersion on the carrier. Moreover, SiO₂ doping enhanced the number of acidic sites on the catalyst surface while inhibiting anatase-to-rutile phase transformation, resulting in a wider temperature window for catalytic activity and higher NO ₓ conversion efficiency.
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