Immobilization of (n-Bu₄N)₄W₁₀O₃₂ on Mesoporous MCM-41 and Amorphous Silicas for Photocatalytic Oxidation of Cycloalkanes with Molecular Oxygen

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• 作者：Maldotti ; Andrea ; Molinari ; Alessandra ; Varani ; Graziano ; Lenarda ; Maurizio ; Storaro ; Loretta ; et. al.
• 关键词：photocatalysis ; polyoxotungstates ; mesoporous materials ; oxidative catalysis ; hydrocarbon oxidation
• 刊名：Journal of Catalysis
• 出版年：2002
• 出版时间：July 1, 2002
• 年：2002
• 卷：209
• 期：1
• 页码：210-216
• 全文大小：150 K

文摘

Heterogenization of (n-Bu₄N)₄W₁₀O₃₂ on amorphous and MCM-41 silicas by impregnation is a suitable method to prepare efficient and stable catalysts able to oxidize unactivated C–H bonds to the corresponding alcohols and ketones with molecular oxygen and near ultraviolet light. The thus-prepared catalysts were characterized by spectroscopic and N₂ adsorption–desorption experiments. A better dispersion of decatungstate was achieved with MCM-41, which also has the higher surface area. Results obtained in the model photooxidation of cyclohexane and cyclododecane confirm that the decatungstate heterogenized on the more ordered MCM-41 silica promotes the process with higher chemoselectivity (cyclohexanone/cyclohexanol molar RATIO=2.6). The photocatalytic efficiency of (n-Bu₄N)₄W₁₀O₃₂ is not reduced after heterogenization; moreover, decatungstate immobilized on amorphous silica oxidizes cyclododecane with a markedly higher efficiency than in the homogeneous phase. The supported photocatalysts can be used at least three times without any loss of activity.