Selective Oxidation of Hydrocarbons with Hydrogen Peroxide Catalyzed by Iron-substituted Silicotungstates

Abstract

The Keggin-type di-iron-substituted silicotungstate, γ-SiW10{Fe(OH2)}2O386−, can catalyze the selective oxidation of various alkanes including methane with hydrogen peroxide. The tetrabutylammonium salt catalytically oxidized cyclohexane, n-hexane, n-pentane, and adamantane in acetonitrile. Even lower alkanes such as methane, ethane, propane, and n-butane were catalytically oxidized. It is remarkable that the efficiency of hydrogen peroxide utilization to oxygenated products reached up to ca. 100% for the oxidation of cyclohexane and adamantane. The efficiency and activity for the utilization of hydrogen peroxide greatly depended on the iron centers and di-iron-substituted γ-SiW10{Fe(OH2)}2O386− showed the highest efficiency of hydrogen peroxide utilization and conversion. Such a structure dependency of the catalysis is significant and the remarkable catalytic performance of di-iron-substituted polyoxometalate may be related to the catalysis by methane monooxygenase. It was also demonstrated that the water-soluble potassium salt catalytically oxidized the lower alkanes with hydrogen peroxide in water.