Oxidation desulfurization of fuel using pyridinium-based ionic liquids as phase-transfer catalysts

In this work, several ionic liquids based on pyridinium cations are prepared. The ionic liquids are employed as phase-transfer catalysts (PTCs) for phase-transfer catalytic oxidation of dibenzothiophene (DBT) dissolved in n-octane. The partition coefficients of DBT between ionic liquids and n-octane are investigated. Then H2O2–formic acid is used as an oxidant and ionic liquids are used as PTCs. The reaction turns to be heterogeneous and desulfurization rate of DBT increased apparently. When IL ([BPy]HSO4) is used as PTC, and the condition are: temperature is 60 °C, time is 60 min, H2O2/sulfur molar ratio (O/S) is 4, the desulfurization rate reaches the maximum (93.3%), and the desulfurization of the real gasoline is also investigated, 87.7% of sulfur contents are removed under optima reaction conditions. The PTC [BPy]HSO4 can be recycled for five times without significant decrease in activity.