Preparation Of Deep Eutectic Solvents With Organic Acid As Hydrogen Bond Donor And Oxidation Desulfurization Performance

As environmental concerns grow around the world,countries are setting stringent standards for sulfides in fuel.In order to accord with international standards,national?standards were instituted in 2013,which require to reduce sulfur content to 10 ppm.Hydrodesulfurization is industrial mature technology,but the reaction conditions are harsh,and removal thiophene sulfide is ineffective.Non-hydrodesulfurization use combination of extraction and oxidative desulfurization.It become the focus of everybody's research due to its mild reaction conditions,low pollution,and the effective removal of thiophene sulfide.Several chlorine-free deep eutectic solvents?DESs?were prepared in this experiment to remove sulfides from the simulated oil.The research contents are as follows:1-ethyl-3-methyl ethyl sulfate imidazole ionic liquids?EMIES?and p-toluene sulfonic acid?p-TsOH?according to certain mole ratio were added into the 50 mL beaker with stirring until dissolved at 100?form a viscous liquid.The liquid is imidazole diethyl sulfate/p-toluene sulfonic acid eutectic solvent?EMIES/p-TsOH?.The structure characteristics were analyzed by infrared spectrum,hydrogen spectrum and thermogravimetry.Its removal performance of sulfide in simulated oil was researched to use EMIES/p-TsOH as catalyst and extraction agent,and H₂O₂ as oxidant.The effects of reaction temperature,n?H₂O₂?/n?S?ratio,DESs dose and different sulfides on desulfurization were investigated.After optimizing the reaction conditions,the removal rates of dibenzothiophene?DBT?,4,6-dimethyldibenzothiophene?4,6-DMDBT?and benzothiophene?BT?in the simulated oil were 96.2%,92.2%and 88.8%,respectively.After five cycles,the DBT removal rate still reached 93.6%.The apparent activation energy of the desulfurization system was 66.4 kJ/mol.C₆H₁₁NO/2TsOH deep eutectic solvents?DESs?was prepared by heating the mixture of caprolactam and p-toluene sulfonic acid.The DESs were analyzed by infrared spectrum and hydrogen spectrum.With C₆H₁₁NO/2TsOH as extraction agent and catalyst,and H₂O₂ as oxidant,the sulfide in the simulated oil was removed by catalytic oxidation.The effects of reaction temperature,n?H₂O₂?/n?S?,the amount of C₆H₁₁NO/2TsOH and different sulfide types on desulfurization were investigated.Experimental results show that benzene and thiophene?DBT?,4,6-dimethyl benzene and thiophene?4,6-DMDBT?and benzothiophene?BT?removal rate were97.2%,86.6%,77.8%under condition of the eutectic solvent amount of1.0 g,temperature of 60?,n?H₂O₂?/n?S?=4,simulated oil amount of 5 mL.The catalyst can be recycled for 5 times and its catalytic activity decrease slightly.A series of acid eutectic solvents EMIES/nC₉H₁₀O₂?n=0.25,0.5,1,2,4?were prepared by simply heating the mixture of1-ethyl-3-methylimidazole ethyl sulfate?EMIES?and 3-phenylpropionic acid(C₉H₁₀O₂).The structure of EMIES/nC₉H₁₀O₂ was determined by FTIR,¹H NMR and TGA.With the deep eutectic solvents as the catalyst and extraction agent,and H₂O₂ as the oxidant,the oxidization-extraction desulfurization system was composed to remove the sulfide in the simulated oil.Results show that removal rates of DBT,4,6-DMDBT and BT were94.8%,91.6%and 46.4%at the condition of EMIES and C₉H₁₀O₂ mole ratio of 1:1,the reaction temperature of 50?,O/S ratio of 8,the eutectic solvent amount of 1.5 g and simulated oil of 5 mL.The activity of eutectic solvent decrease slightly after 6 cycles.Equal mole ratio of polyethylene glycol 200?PEG-200?and p-toluene sulfonic acids were stirred at 100?until completely dissolved form a clear solution,it is eutectic solvent PEG-200/TsOH.At the same time,the PEG-200/TsOH were analyzed by infrared spectrum,hydrogen spectrum and thermogravimetric analysis,The reaction kinetics and oxidation desulfurization mechanism were studied.Through the experiment,removal rate of DBT in model oil was 98.0%at the reaction conditions of temperature of 60?,O/S ratio of 4,deep eutectic solvent amount of 1.5and simulated oil of 5 mL.