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

Lewis or Bronsted 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.