Preparation of Al/TiO2 nanometer photo-catalyst film and the effect of H2O addition on photo-catalytic performance for benzene removal Original Research Article

The nanometer particles of TiO2 and Al/TiO2 (1.0, 5.0, and 10.0 wt.%) were obtained by a sol–gel method. The TiO2 and Al/TiO2 particles were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), DLS, TG-DSC, and UV-Vis spectroscopy. The TiO2 and Al/TiO2 particles exhibited a uniform anatase structure with particle size below 100–150 nm. Obtained Al/TiO2 particles absorbed wavelengths above 270 nm. The absorption band was shifted to longer wavelength (red shift). In addition, the surface area of 10.0 wt.% Al/TiO2 was very large (290 m2/g), compared with that of pure TiO2 (50–70 m2/g). From XRD results, we suggested that a new structure connected by AlOTi framework was generated. In particular, for Al/TiO2, the anatase structure was stable after thermal treatment at 800 °C, while pure TiO2 was easily transferred to the rutile type after thermal treatment above 700 °C. On the other hand, the conversion of benzene was higher in pure TiO2 than in Al/TiO2 without H2O addition during reaction; however, the conversion surprisingly enhanced about 40% over 10.0 wt.% Al/TiO2 catalyst with 10 mol-wt.% H2O addition in a continuous photo-reaction system. In addition, no photo-catalytic deactivation was found over 10.0 wt.% Al/TiO2 until 10 h, when 10 mol-wt.% H2O was added during the benzene decomposition reaction.