The Application Of Deacidification And Desulfurization Of Ionic Liquids In Petrochemical Area

This paper studied the application of deacidification and desulfurization of ionic liquids (ILs) in petrochemical area. A series of ionic liquids were synthesized, including1-alkyl-3-methylimidazolium hydroxide ILs [Cxmim]OH,1-alkyl-3-methylimidazolium tetrafluoroborate ILs [Cxmim]BF4,1-alkyl-3-methylimidazolium bromochloroaluminate ILs [Cxmim]Br-AlCl3. And the structure of these ionic liquids was tested by FT-IR, the results showed that the IR spectra of synthetic substances was consistent with the structural features of ionic liquids [Cxmim]OH,[Cxmim]BF4, and [Cxmim]Br-AlCl3.Removal of naphthenic acid from acidic oil by ionic liquids [Cxmim]OH was studied. The results showed that the longer the alkyl chain length of ionic liquids, the stronger the alkalinity, the higher the deacidification rate, i.e. deacidification performance of ionic liquid [C8mim]OH was the best. When using the ionic liquid [C8mim]OH to remove naphthenic acid, at the temperature of333K, the mass ratio of [C8mim]OH to oil was4%(wt/wt), deacidification rate could reach up to91.7%for reacting2h. The repetitive reaction experiments of [C8mim]OH showed that it could be reused to some extent. Deacidification mechanism was that the ionic liquids reacted with naphthenic acid to generate new ionic liquids and water to achieve the purpose of deacidification.Removal of sulfides from simulated oil consisting of n-octane and thiophene by ionic liquids [Cxmim]BF4was investigated. It was found that the results of oxidation-extraction were significantly better than direct extraction. Then factors influencing on desulfurization performance were studied by ionic liquids [Cxmim]BF4. The results showed that the optimum temperature was323K, the reaction got equilibrium for3h, when the mass ratio of [C4mim]BF4to simulated oil was0.8(wt/wt), the desulfurization rate of91.23%was obtained. In this case, v(H2O2)/m(oil) was0.4ml/g. And the desulfurization performance of ionic liquids [Cxmim]BF4was still efficient after reusing for three times.We also researched the desulfurization performance of ionic liquids [Cxmim]Br-AlCl3. The results showed that the longer the alkyl chain length, the higher the desulfurization rate, if molar ratio of AICI3to [C8mim]Br was2:1, molar ratio of1-hexene to thiophene in simulated oil was4:1, and mass ratio of [C8mim]Br-AlCl3to simulated oil was10%, at the temperature of333K, the desulfurization rate was100%for reacting15min. Through theoretical analysis coupled with characterization by GC-MS for ionic liquids [C8mim]Br-AlCl3before and after desulfurization, it could be inferred that sulfides was removed by two means, on the one hand, thiophene was extracted into ILs, on the other hand, thiophene was alkylated with1-hexene to form alkylates with high boiling point.