Ionic Liquid Synthesis And Application In Desulfurization Of Fuel Oil

Ionic liquids are composed of ions completely, and they are liquids at room temperature. So, they are also called low-temperature molten salt or ionic liquids. They are widely used in the fields of organic synthesis and industrial separation because of their so many advantages, such as low vapour pressure, wide liquid range, high thermal stability, etc. In recent years, ionic liquids are investigated widely in the application of desulfurization of oil.In this thesis, three conventional ionic liquids [Bmim]BF₄,[Bmim]NTf₂ and [C₄Py]NTf₂, two kinds of functionalized ionic liquids [EimC₄SO₃H]HSO₄ and [EimC₄SO₃H]NTf₂, and two protic ionic liquids DMHEEAP and DMCEAP are synthesized. And the purity of ionic liquids is characterized by NMR. The desulfurization efficiencies of the functionalized ionic liquids and protic ionic liquids are investigated.When the SO₃H-functionalized ionic liquids used as the extractant, the removal efficiencies of debenzothiophene(DBT) by ionic liquids were investigated systematically. And the oxidation-extraction desulfurization is chosen as the experimental method, while the NaClO and H2O2 are chosen as oxidants. The sulfur content of the model oil decreases from initial 1600 ppm to 20 ppm by the SO₃H-functionalized ionic liquids. And the extraction efficiency could reach up to 98%. Ionic liquids are recycled by washing with water. After 5 times recycling and reusing, the desulfurization efficiency has no obvious decrease. The oxidation product of DBT is separated and characterized by 1H NMR and MS, which indicates that the oxidation product is debenzothiophene sulphone (DBTO₂). At the same time, if different oxidant is chosen, the desulfurization will obey different mechanism.When the protic ionic liquids are chosen as the extractant, the removal efficiencies of debenzothiophene by ionic liquids were investigated systematically. And the direct extraction desulfurization is chosen as the experimental method. The sulfur concentration in the model oil decreases from initial 1600 ppm to 650 ppm by the protic ionic liquids for the first extraction process. The desulfurization efficiency reaches up to 60 %. After five times extraction, the sulfur content of model oil decreases to 20 ppm. Ionic liquids could be recycled by distillation method. The desulfurization efficiency of recycled protic ionic liquids has tiny change. And then, the desulfurization mechanism of protic ionic liquids is preliminarily discussed.