An organic-inorganic heterogeneous catalyst based on Keplerate polyoxometalates for oxidation of dibenzothiophene derivatives with Hydrogen peroxide

An organic-inorganic material (NH4)(2)(MimAM)(40)[Mo132O372(CH3COO)(30)(H2O)(72)] have been synthesized by reacting [(NH4)(42)[Mo-72(VI) (Mo60O372)-O-V(CH3COO)(30)(H2O)(72)] with the ionic liquid 3-Aminoethyl-1-methylimidazolium bromide. The catalyst showed remarkably a high catalytic performance in the oxidation of dibenzothiophene (DBT) derivatives with H2O2 35% as a safe and green oxidant. The main parameters affecting the process including catalyst, acid additive, hydrogen peroxide amounts and temperature have been investigated in detail. Sulfur removal of DBT in n-heptane reached to 98.3% yield at 40 degrees C using 2.5mmol H2O2 and 100mg of (NH4)(2)(MimAM)(40)[Mo132O372(CH3COO)(30)(H2O)(72)] after 90min. Under the optimal conditions, BT (benzothiophene), DBT (dibenzothiophene) and 4,6-DMDBT (4,6-dimethyl-dibenzothiophene) achieved high desulfurization efficiency. Our results showed that the reactivity order of different model sulfur compounds are thiophene <4,6-dimethyl dibenzothiophene< dibenzothiophene. The catalysts could be easily separated from the reaction solution by simple filtration and recycled for several times without loss of activity.