Desulfurization of fuel oils by extraction with ionic liquids

Four N-alkyl-pyridinium-based ionic liquids, N-ethyl-pyridinium hexafluorophosphate, N-butyl-pyridinium hexafluorophosphate,4-methyl-1-ethyl-pyridinium hexafluorophosphate, and 4-methyl-1- butyl -pyridinium hexafluorophosphate were synthetized by microwave method. The simulated gasoline was prepared by mixing n-hexane, n-heptane,toluene and thiophene. Effect of extraction temperature, the ratio of solvents and diverse ionic liquids are investigated with extraction equilibrium experiment. The best conditions of transport desulfurization are discussed. The result showed that the partition ratio of [MBPy]PF6 to the thiophene could exceed 1.3 at temperature 45 degrees C, the ionic liquid composition in raffinates was undetectable, [MBPy]PF6 has the best effect on the selective removal of sulfur-containing compounds from gasoline among these ionic liquids. When temperature is 50 degrees C and desulfurization agent to fuel oil is 1:1, the extraction efficiency can reach over 90% only three-step extraction for gasoline.