Deep Extractive Desulfurization Of Fuel Tuned By Water-Based Deep Eutectic Solvents

SOx produced by fuel combustion is one of the main sources of environmental pollution,which can cause acid rain,haze and a series of bad weather,thus,the ecological environment is greatly damaged.Therefore,the standard of sulfur compounds in fuels is becoming more and more stringent in many countries.And now,clean fuels with sulfur content less than 10 ppm is required.For desulfurization technology,hydrodesulfurization has always been the main method for desulfurization in industry,but it is not efficient for the removal of heterocyclic sulfur components.That is to say,this method is difficult to reduce the total sulfur content to less than 10 ppm.As for many non-hydrodesulfurization methods,the extraction desulfurization process with deep eutectic solvents(DESs)has been extensively studied due to its mild conditions,simple operation process and environmental protection.This work screened many DESs through experiments and the DES with the best performance was obtained,which is formed by tetrabutylphosphine bromide(TPBP)and water.Based on this DES,a water-driven extractive desulfurization process for model oil with.dibenzothiophene(DBT)as sulfur compound was proposed.Firstly,the effects of water content on DES formation,desulfurization performance of DES and solubility of DBT in DES were determined by experiments.The result shows,a DES consisting of TBPB and water in a molar ratio of 1:2 give the highest desulfurization efficiency,namely 70.4%,in one extraction stage.DES regeneration can be achieved by increasing the water content of DES phase to 1:50(molar ratio of TBPB to water)after extraction.Then,the mechanism of this process was studied by FT-IR and 1H NMR characterization and molecular dynamics simulation.The result shows,the DES is formed by hydrogen-bonding interactions between the Br-anions and the water.The extraction is driven by hydrogen bonding of Br-anions with DBT and the CH-? interactions of TBP+cations with DBT.In the regeneration process,excessive water in DES phase weakens the interactions of TBPB with DBT.This facilitates DBT aggregation and therefore promotes regeneration.