Oxidative desulfurization of model diesel using [(C4H9)4N]6Mo7O24 as a catalyst in ionic liquids

An extraction and catalytic oxidation desulfurization (ECODS) system, composed of an Anderson-type catalyst [(C4H9)4N]6Mo7O24, model diesel, 30% H2O2 and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6), was conducted under mild conditions. The sulfur-containing compounds, such as benzothiophene (BT), dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT), were extracted into ionic liquid (IL) from the model oil and oxidized to corresponding sulfones using H2O2 as oxidant in the presence of the [(C4H9)4N]6Mo7O24. In the case of ECODS, the sulfur removal of DBT can reach 99.0%, which was superior to that of the simple extraction with IL or the chemical oxidation. The amounts of ILs and oxidant dosage play vital roles in ECODS. The reactivity of sulfur-containing compounds in the ECODS was followed: DBT > 4-MDBT > 4,6-DMDBT > BT. This ECODS system could be recycled six times without a significant decrease in activity.