Synthesis Of Amide-based Deep Eutectic Solvent For Extractive Desulfurization Of Fuel Oil

With the rapid development of modern industry and the rapid growth of motor vehicles,the resulting problems such as vehicle exhaust emissions have become urgent issues that need to be resolved.The gas pollutants in the exhaust gas are closely related to the sulfur content in the fuel.The emission of harmful gases causes serious harm to the environment,and at the same time endangers human health.In order to protect the environment and achieve green and sustainable development of energy,governments of various countries have successively promulgated strict standards for the sulfur content of light fuel oil.In recent years,a large amount of high-sulfur crude oil imported by our country from abroad has made the sulfur content in the produced fuel oil higher,so fuel desulfurization is very important.In particular,the deep removal of organic sulfur compounds in fuel oil is currently the focus of research in the field of desulfurization.At present,industrial hydrodesulfurization(HDS)is difficult to remove thiophene organic sulfur compounds,so other technologies that replace hydrodesulfurization have become the focus of research.Among them,extractive desulfurization(EDS)has attracted the attention of scientists due to its simple operation,low operating cost and better desulfurization efficiency.In recent years,as an analog of ionic liquids,eutectic solvents(DES)have been rapidly developed as a new type of extractant.In this paper,a series of amide-based eutectic solvents have been successfully synthesized and applied to extractive desulfurization.1.In this work,using amide organics and metal chlorides as raw materials,a series of amide-based IV type deep eutectic solvents were synthesized by a one-step method and successfully applied to EDS.The successful preparation of DES was proved by means of FT-IR,¹H NMR and theoretical chemical calculations,and the extraction desulfurization experiment was carried out using it as the extractant.Through the types of metal chlorides and amides and the ratio of the two,DES(Zn Cl₂/MFA=1,MFA=N-methylformanilide)was finally selected as the best research object.The experimental results of condition optimization show that at T=60^oC,t=30 min,m(DES)=1 g,m(oil)=5 g,the removal rate of sulfide DBT can reach 32.5%,desulfurization after 6-stage extraction The rate can reach 85.7%.Not only that,DES(Zn Cl₂/MFA)is not sensitive to changes in the initial sulfur content in the simulated oil,and its extraction and desulfurization capabilities for high-sulfur model oil and low-sulfur model oil remain basically unchanged.Among three sulfides of DBT,4-MDBT and 4,6-DMDBT,DES has the best effect on the removal of DBT.Through experiments and theoretical calculations,the mechanism of EDS with DES(Zn Cl₂/MFA)as the extractant is discussed.The results show that the presence of MFA in DES is the key to extractive desulfurization.The?···?interaction and C-H···?interaction between it and the sulfide DBT enable DES to effectively remove DBT from the simulated oil.2.Choosing caprolactam(CPL)and quaternary ammonium salt as raw materials,a series of CPL-based deep eutectic solvents were synthesized by a one-step method and successfully applied to EDS.The successful preparation of DES was proved by means of FT-IR,¹H NMR and theoretical chemical calculations,and the extraction desulfurization experiment was carried out with it.Choosing DES(CPL/TBABr=2:1,TBABr=Tetrabutylammonium Bromide)as the best research object,the optimization results show that at T=30^oC,t=20 min,m(DES)=1 g,m(oil)=1 g,the removal rate of sulfide DBT can reach 81%,and it can reach 96.6%after two-stage extraction.At the same time,under the above-mentioned optimal experimental conditions,the desulfurization efficiency of DES for oils with different sulfur content is basically the same.Among three sulfides of DBT,4-MDBT and 4,6-DMDBT,DES has the best effect on the removal of DBT.The experimental mechanism of the EDS process is discussed through experiments and theoretical calculations.The results show that it is the hydrogen bonds and van der Waals forces that enable DES to effectively remove DBT from the simulated oil.