Almost of oxidative reactions using hydrogen peroxide (H2O2) have been focused solely on improving performance of oxidative catalysts, and little attention has been paid to conversion from H2O2 to peroxides possessing optimum oxidative property for efficient oxidative reactions. On the other hand, H2O2 possesses unique property generating peroxides of different oxidative properties by reactions of H2O2 and various inorganic anions species such as carbonates and sulfates. In this study, we challenged the design of composite catalysts combined inorganic anions species and a tungstate ion (WO42-), which is known to exert excellent catalytic performance in the oxidation of olefins and thiophenes, on an immobilization support of anions. A calcined product of Mg-Al typed layered double hydroxide (LDH) was selected as the immobilization support because of possessing excellent anion exchange property and chemical stability. The effects of inorganic anions species on an oxidative reaction of a tetrahydrothiophene (THT) were investigated using the composite catalysts (Calcined LDH-WO42- + Anion) for obtaining the design guide of novel catalyst capable of controlling the oxidative reaction property. The Calcined LDH-WO42- + Anion catalysts were prepared by the anion exchange method in an aqueous suspension containing the WO42-, inorganic anions species (Cl-, NO3-, SO42- or CO32-) and the calcined LDH (Mg:Al=3:1 (mol ratio)). The oxidative reaction of THT (1 mmol) was performed at 303 K for 30 min in an acetonitrile solvent containing 2.2 mmol of H2O2. The THT oxidative performance enhanced in order of CO32- &gt;&gt; Cl- ≈ NO3- &gt; SO42- ≈ without anion. The Calcined LDH-WO42- + CO32- catalyst exhibited significantly high oxidative reaction property in all tried catalysts, resulting that the conversion reached ca. 80% at 30 min whereas that on the Calcined LDH-WO42- without anion was ca. 46%. The specific phenomenon on the Calcined LDH-WO42- + CO32- catalyst might be produced by that the percarbonate species (e.g. HCO4-) possessing higher oxidation property than the H2O2 was generated on the composite catalyst. These results suggest that combining the oxidative catalyst and inorganic anion species can achieve to enhance the oxidative property using H2O2 as usage of reaction species.

Design of composite catalysts introduced tungstate and inorganic anions on calcined LDH for controlling oxidative reaction property using hydrogen peroxide

254th National Meeting (2017)

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