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.