Synthesis, Characterization And Application Of Imidazole Ionic Liquid For Extractive Desulfurization Of Model Oil

Preparation methods and desulfurization abilities of imidazolium ionic liquids for model oil were systematically studied aiming at the disadvantages of traditional desulfurization methods such as HDS as well as unique physical and chemical properties of imidazolium ionic liquids.Three kinds of [Cnmim]Cl?n=4,6,8?intermediates were firstly prepared with N-methyl imidazole and halogenated alkane through nucleophilic addition reaction,then series of imidazolium ionic liquids were synthesized with intermediates and several inorganic salts,and the products were applied in desulfurization process for model oil.The influences of temperature,time and solvent on the yield of imidazolium ionic liquids were investigated with single factor experiments,the optimum reaction conditions of hydrophilic ionic liquids such as [Bmim]BF₄ were as follows: reaction temperature was 40 oC,reaction time was 20 h,methanol as solvent;best reaction conditions of hydrophobic ionic liquids such as [Bmim]PF₆ were as follows: reaction temperature was 40 oC,reaction time was 2 h,deionized water as solvent;then series of Fe???-containing imidazolium ionic liquids were prepared using the intermediates and anhydrous Fe Cl₃,and the products were characterized by UV,FT-IR,1HNMR,13 CNMR and GC-MS methods,results showed high purity of the prepared ionic liquid and the structure was in conformity with our demand,laying a good foundation for the coming desulfurization research of model oil.The influences of extraction time,extraction temperature,volume ratio of ionic liquids and model oil,different sulfur-containing compounds,extraction stages were investigated in the extraction desulfurization?EDS?experiments.Anions had great influence on desulfurization efficiency of ionic liquids with the same cation,the desulfurization ability order was as follows: [Bmim]PF₆ < [Bmim]BF₄;removal possibility of different sulfur components in model oil was related to their electron density and the order was as follows: T < BT < DBT;desulfurization efficiency increased obviously with the increase of extraction stages,such as [Bmim]PF₆: the removal efficiency of DBT rate could reach as high as 97.6% after 4 extraction stages.Using hydrogen peroxide?H2O2?as oxidant,desulfurization performance of Fe???-containing imidazolium in EDS as well as extractive-oxidative coupled desulfurization system was investigated through series of single factor experiments,we got the optimal desulfurization conditions.The effects of adding H2O2 in other ionic liquids were furtherly investigated,results showed that ionic liquids had better desulfuration ability with longer alkyl in the side chain;the desulfuration efficiency could be significantly improved by adding H2O2 in other ionic liquids.DBT could be completely removed in these extractive-oxidative coupled desulfurization systems.DBT was oxidized in the ionic liquids phase as it was extracted from the oil phase in a combination of extraction and oxidzation system.DBT could be oxidized to its sulfoxide and sulfone,which kept in ionic liquid phase due to their high polarities and promote desulfurization efficiency.The regeneration and the reusability of imidazolium ionic liquids were studied considering the cost for desulfurization and post process.The ionic liquids by reversed extraction followed by vacuum distillation were recycled according to different properties of different ionic liquids.FT-IR results showed that the structure of ionic liquids were not much changed before and after regeneration.The desulfurization performance of the ionic liquids had no significant decrease after repeated use,which provided theoretical basis for industrial application.