Gas phase photocatalytic removal of toluene effluents on sulfated titania

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• 作者：Elodie Barraud ; Florence Bosc ; David Edwards ; Nicolas Keller and Valé ; rie Keller
• 关键词：Titania ; Sulfates ; Photocatalysis ; Toluene ; Electron transfer ; Photogenerated charge recombination
• 刊名：Journal of Catalysis
• 出版年：2005
• 出版时间：2005
• 年：2005
• 卷：235
• 期：2
• 页码：318-326
• 全文大小：254 K

文摘

Photocatalytic removal of toluene in the gas phase was carried out over UV-illuminated sulfated titania materials in a cylinder-like continuous reactor. A series of –TiO₂ samples was obtained from the addition of H₂SO₄ on an amorphous titanium hydroxide gel synthesized according to a classical sol–gel procedure. The wide variety of materials led to varying photocatalytic behaviors depending strongly on the experimental synthesis parameters, having a determinant influence on the surface specific area, the crystallinity of the material, the crystallographic nature of TiO₂, and the sulfate surface content. Optimization of the experimental parameters, such as the molarity of the sulfation solution, varying in the range 0.25–5 M leading to surface sulfate coverage of 2.5–14 wt % , and the calcination temperature ranging from 400 to 800 °C, promoted enhanced photocatalytic performance toward toluene removal as compared with commercially available P25 TiO₂ and sulfate-free sol–gel TiO₂. The most efficient photocatalyst was obtained for a near-monolayer sulfate coverage corresponding to the presence of both TiO₂ and well-dispersed with optimized contact between and TiO₂ domains. Furthermore, a positive role of sulfates is attributed both to an electron transfer from titanium to sulfates, leading to a positive charge trap effect, and to better desorption of electron-rich sp²-bound carbon aromatic poisons, thus limiting deactivation.