Keggin-structured polyoxometalate-based ionic liquid salts: Thermoregulated catalysts for rapid oxidation of sulfur-based compounds using H2O2 and extractive oxidation desulfurization of sulfur-containing model oil

A family of benign polyoxometalate-based ionic liquid salts (POM-ILs) was designed and prepared by combining Keggin-structured polyoxometalate inorganic anions with sulfonate functionalized organic cations. The resultant salts were characterized, and catalytically evaluated by oxidation of sulfur-based compounds. They exhibited good-to-high yields and selectivities for target sulfides in oxidation reaction. Cyclic voltammetry (CV) was used to investigate the redox behavior of these catalysts. Also, an extractive and catalytic oxidation desulfurization (ECOD) system composed of ionic liquid salt, hydrogen peroxide as the basic experiment was used for the removal of sulfur-containing compounds from the model oil at suitable temperature. The reaction system was homogeneous during the reaction and then became heterogeneous at lower temperature which could be easily recovered and reused. (C) 2014 Elsevier B.V. All rights reserved.