Study On The Synthesis Of Eutectic Solvent And Its Extraction Desulfurization Mechanism

With the increasing awareness of environmental protection,Countries around the world have promulgated strict standards to sulfur content in automotive fuel oil and sulfur content is limited to a very low level.In China,environmental legislations have been imposed to restrict the sulfur content in motor gasoline to less than 50 ppm by 2014,and less than 10 ppm by 2017.The reported ionic liquid which provide an excellent extraction of thiophenic sulfur components.However,their use was limited by the relatively complex synthesis,high cost and large dosage.The aim of this work is to synthetic DESs containing arenium ion,also known as alternative to ILs,and investigate the application of DESs as extraction solvents for desulfurization of model oil and real oil.In this study,6 kinds of Deep eutectic solvents were synthesized by the mixture of AlCl3,polychloride(average molecular formula Cl5H26Cl6)and six aromatics,in detail,benzene,toluene,p-xylene,o-xylene,ethylbenzene,mesitylene and chlorobenzene.Abbreviated as DES-B,DES-T,DES-P,DES-O,DES-E,DES-C.The model sulfur compounds were trimethylthiophene(3-MT),benzothiophene(BT),or dibenzothiophene(DBT)respectively.DES-T was selected as the optimum extraction for extractive desulfurization taking into account the desulfurization rate and yield.The optimum condition for synthesis was molar ratios of AlCl3 to aromatic and Chlorinated paraffins-52 were 6:18:1,20℃,40min.DES-T was characterized by FTIR,1H NMR,27A1 NMR,UV-vis and stoichiometry for basic property and synthesis mechanism.The optimum conditions for extractive desulfurization were 30℃,10min and IL/oil mass ratio 0.06.The sulfur content of 3-MT,BT and DBT decreased from 500μg/g to 1.Oμg/g,1.8μg/g and 51.8μg/g,the desulfurization yield is 99.81%,99.65%and 89.64%,respectively.The desulfurization mechanism was speculated through UV-Vis,GC-MS and theoretical calculation.As follow,on the one hand,the π-πinteraction between thiophenic sulfur compounds and the aromatic rings of DES,on the other hand,the complexation of between thiophenic sulfur compounds and the anion of DES.The extractive desulfurization in real oil are carried out.To meet the National Standard V,the mass ratios of DES-T were 0.10 and 0.14 for distilled gasoline and diesel fuel respectively.In the process of extraction of FCC gasoline,olefin alkylation thiophenic sulfur were take place.So,in this paper,we suggests that after using a small amount of DES-T(e.g.mass ratio 0.06)extraction,Heavy fraction and light distillates was divided by distilled and National Standard IV or V were obtained.