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Selective Photocatalytic Oxidation of Alcohols to Aldehydes in Water by TiO 2 Partially Coated with WO 3

2011; Wiley; Volume: 17; Issue: 35 Linguagem: Inglês

10.1002/chem.201100166

1521-3765

Daijiro Tsukamoto, Makoto Ikeda, Yasuhiro Shiraishi, Takayoshi Hara, Nobuyuki Ichikuni, Shunsuke Tanaka, Takayuki Hirai,

Advanced Photocatalysis Techniques

Abstract Semiconductor TiO 2 particles loaded with WO 3 (WO 3 /TiO 2 ), synthesized by impregnation of tungstic acid followed by calcination, were used for photocatalytic oxidation of alcohols in water with molecular oxygen under irradiation at λ >350 nm. The WO 3 /TiO 2 catalysts promote selective oxidation of alcohols to aldehydes and show higher catalytic activity than pure TiO 2 . In particular, a catalyst loading 7.6 wt % WO 3 led to higher aldehyde selectivity than previously reported photocatalytic systems. The high aldehyde selectivity arises because subsequent photocatalytic decomposition of the formed aldehyde is suppressed on the catalyst. The TiO 2 surface of the catalyst, which is active for oxidation, is partially coated by the WO 3 layer, which leads to a decrease in the amount of formed aldehyde adsorbed on the TiO 2 surface. This suppresses subsequent decomposition of the aldehyde on the TiO 2 surface and results in high aldehyde selectivity. The WO 3 /TiO 2 catalyst can selectively oxidize various aromatic alcohols and is reusable without loss of catalytic activity or selectivity.