Deep catalytic oxidative desulfurization of fuels by novel Lewis acidic ionic liquids

In this work, novel Lewis acidic ionic liquids [ODBU]Cl/nZnCl2 (n = 1, 2, 3, 4 and 5) with alkylated 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) cation and ZnCl2-based complex anion have been developed and utilized in extraction combined with oxidative desulfurization (ECODS) of both model oil and diesel fuel with hydrogen peroxide (H2O2, 30 wt%) as an oxidant. It was observed that the ECODS performance could be effectively optimized by the change of ZnCl2 proportion. Some important reaction parameters such as reaction temperature, molar ratio of O/S, mass ratio of IL/oil and sulfide species were systematically investigated. Furthermore, the ILs could be reused for at least six cycles without noticeable changes in desulfurization performance as well as its chemical structure, thus revealing its good reusability. Finally, [ODBU]Cl/3ZnCl2 was employed in the ECODS of a hydrogenated diesel, the S-content could be reduced from 559.7 ppm to 4.8 ppm with 99.2% sulfur removal via a one-step process under mild conditions.