Oxidative desulfurization of model oil in an organic biphasic system catalysed by Fe3O4@SiO2–ionic liquid

Abstract

Lewis or Brønsted acidic methylimidazolium ionic liquid-functionalized Fe₃O₄@SiO₂ nanoparticles were fabricated and applied as an efficient magnetic heterogeneous catalyst for dibenzothiophene (DBT) oxidation in a biphasic system using H₂O₂ as the oxidant. The structures of catalysts were characterized by SEM, TEM, XRD, TGA, FT-IR, VSM and EDX techniques. The magnetic catalysts showed high catalytic performance in the oxidation of DBT in an n-hexane/acetonitrile biphasic system using H₂O₂, and high conversions were obtained. The effects of contact time, temperature, amount of H₂O₂ and amount of catalyst on the DBT oxidative removal efficiency were investigated. The contact time of 60 min, 0.1 g catalyst, and 4 mL H₂O₂ at 313 K were found as optimal experimental conditions for an improved DBT oxidative removal process. The sulfur level could be lowered from 100 ppm to less than 7, 5, and 2 ppm under optimal conditions for Fe₃O₄@SiO₂–Mim-BF₄, Fe₃O₄@SiO₂–Mim-HSO₄, and Fe₃O₄@SiO₂–Mim–FeCl₄, respectively. These nanomagnetic heterogeneous catalysts could be easily separated from the reaction mixture by applying an external magnetic field and recycled several times.