Study On Deep Desulfurization Of Fuel Oil By Functionalized Ionic Liquid Tetraethyl Ammonium Vanadate

Thiophene sulfide is a kind of inert and trace component in gasoline and diesel,the effect of traditional hydrodesulfurization(HDS)is poor in ultra-deep desulfurization.Thus,in recent years,a variety of new deep desulfurization processes has been developed.The oxidation desulfurization had beed well studied in the deep desulfurization because of its high selectivity and high removal.In particular,ionic liquids containing variable valence metals have become a research highlight in recent years.These ionic liquids can achieve deep desulfurization through catalytic oxidation desulfurization.In this paper,we focus on synthesize a kind functionalized ionic liquid TEAVO3 for deep desulfurization,then explored the effect of deep desulfurization under different reaction conditions.By adjusting the acidity,vanadium-containing functional ionic liquid catalytic oxidation and direct oxidation systems were obtained.The main work and conclusions are the follows:(1)The functionalized ionic liquid of tetraethyl ammonium vanadate(TEAVO3)was prepared,added organic acid,used BmimBF4as extractant to form a catalytic oxidation system for deep desulfurization of gasoline:The effects of acid type,acid dosage,TEAVO3 dosage,oxidant H2O2 dosage,temperature and the type of thiophene sulfur-containing compounds on deep desulfurization were investigated.The results showed that with the increase of acidity,the catalytic oxidation effect increased first and then decreased,the best removal effect can be achieved at pH=2.98.Under the optimal conditions,the model oil with 500 ppm sulfur content could achieve to 99.24%DBT removal rate within 2h.The DBT removal rate still remained at 96.7%after six cycles of desulfurization and regeneration,indicating that the TEAVO3 ionic liquid had a good regeneration performance.In addition,the mechanism of catalytic oxidation desulfurization was proposed through GC-MS,UV-Vis,51VNMR and other characterize methods:in acidic environment,through the catalysis of TEAVO3,oxidant H2O2 oxidizes thiophene sulfur compounds in the ionic liquid phase to sulfone products.(2)The organic acids in the catalytic oxidation system were replaced by inorganic acid sulfuric acid,then the direct oxidation of sulfide was carried out.The effects of acid dosage,TEAVO3 dosage,temperature and the type of sulfide on the deep desulfurization were investigated.The results show that with the increase of hydrogen ion concentration,the oxidation capacity of pentavalent vanadium increases,and the direct oxidation desulfurization efficiency increases.When c(H+)=3.68mol/L,the DBT removal rate of model oil can reach 99.03%within 2h.The direct oxidation desulfurization mechanism was obtained by GC-MS,UV-Vis,51V-NMR and other methods:vanadium in the direct oxidation system existed in the form of VO2+,thiophene sulfur-containing compounds in the ionic liquid phase were oxidized to the corresponding sulfone products,which themselves are reduced to tetravalent,and finally existed in the form of VO2+.