Screening Of Ionic Liquids As Extractants For Fuel Desulfurization Process And Mechanism Research

The traditional desulfurization methods cannot reach a satisfactory effect in deep desulfurization of gasoline and have a lot of disadvantages such as high operating cost,large investment,harsh reaction conditions and using harmful volatile solvents.The extraction desulfurization with ionic liquids,which has many advantages such as simple process,mild conditions,removal thiophenic sulfur easily without changing the components of gasoline,etc,shows promising as an technique for the deep desulfurization of gasoline.This paper chose ionic liquids as desulfurization solvent,proposed a screening model,and researched the desulfurization mechanism by Gaussian calculation.The main contents are as follows:1.Based on the COSMO-SAC model molecular design method and semi-empirical physical prediction method,a screening model of ionic liquids extractant was established,which considered the parameters of thermodynamic properties(selectivity coefficient,solubility),the structural characteristics of ionic liquid and the affect of physical properties(such as viscosity and melting point)on the separation process.The screening model increase the feasibility of screening of ionic liquids rapidly,which has more practical value.2.Analyzed the effect of the removal of three thiophenes by the anions and cations.It is considered that the cation has a strong effect on the removal of benzothiophene,and the anion has a strong effect on the removal of thiophene.After screening,22 kinds of ionic liquid extractants were selected from 2400 ionic liquids for fuel desulfurization.3.The interaction between ionic liquids,benzothiophene and n-octane was studied by Gaussian.For a detailed analysis of the sources of interaction,NBO analysis,charge analysis,AIM and RDG method were used.NBO analysis shows that,besides the electrostatic interaction,the interaction between IL,BT and OC mainly include hydrogen-bonding interaction,?-? and Van der Waals forces.By charge analysis,AIM and RDG analysis,the interaction was analyzed in detail.4.By liquid-liquid extraction experiment,the desulphurization effect of five ionic liquids was studied.The Gaussian calculation can be a powerful supplement to the ionic liquid screening model based on COSMO,which makes the ionic liquid screening model more practical and provides a reliable basis for the screening of ionic liquids.And the possible causes of defects in the COSMO screening model were revealedIn conclusion,the screening model proposed and mechanism research in this paper provide theoretical guidance for the desulfurization process of ionic liquid as extractant.