Oxidative desulfurization of fuels catalyzed by ammonium oxidative-thermoregulated bifunctional ionic liquids

• A series of oxidative-thermoregulated bifunctional ionic liquids have been developed.
• IL/toluene/n-octane or n-dodecane system has the property of thermoregulation.
• The thermoregulated system is used for H2O2 oxidative desulfurization of model fuels.
• The reaction and the separation are well integrated.

A series of developed ammonium oxidative-thermoregulated bifunctional ionic liquids (ILs) catalysts have been synthesized. The structures of these task-specific ionic liquids (TSILs) are characterized by FT-IR and 1H NMR. The thermoregulated properties of ILs in aqueous and common organic solvent are investigated. The prepared ionic liquid has the cloud point (CP) in aqueous, and has the minimum solubility in toluene. The ionic liquid has the corresponding critical solution temperature (CST) in toluene/n-octane or n-dodecane mixed solvents, which makes the system with the thermoregulated feature of “homogeneous at high temperature, heterogeneous at low temperature”. The developed thermoregulated system has been used for catalytic H2O2 oxidative desulfurization of model fuels to achieve an integration of homogeneous catalysis and heterogeneous separation. The recycle of the ionic liquid catalyst is easily achieved. The desulfurization rate only keeps a gradually slight drop during the recycles of the catalyst.