Synthesis Of Non-chlorine Acidic Deep Eutectic Solvents And Its Oxidative Desulfurization Performance

With the increasingly strict regulations of environmental protection,the sulfur content requirements in fuel oil have become more and more strict.Although hydrodesulfurization technology is already mature technology,it has poor effect on the removal of thiophene sulfides.Oxidative desulfurization can achieve efficient removal of thiophene sulfides under warm reaction conditions.This paper uses non-chlorine acidic deep eutectic solvent as catalyst and extractant for desulfurization,which not only has low cost,but also has a high desulfurization rate.Non-chlorine acidic deep eutectic solvents have the more environmentally advantage.Under the condition of hydrogen peroxide as an oxidant,the purpose of efficiently removing thiophene sulfides can be achieved,which further solves the difficult problem of removing thiophene sulfides in fuel oil.This paper systematically studies the desulfurization of non-chloric acid deep eutectic solvents.In this paper,three types of non-chlorine acidic deep eutectic solvents are synthesized by simple stirring methods and applied into oxidative desulfurization.?1?Deep eutectic solvents C₆H₁₁NO/n CF₃SO₃H?n=0.25,0.5,1?were synthesized by simply heating and stirring the mixture of caprolactam(C₆H₁₁NO)and trifluoromethanesulfonic acid?CF₃SO₃H?.The structural characteristics of C₆H₁₁NO/n CF₃SO₃H were determined by infrared spectroscopy?FT-IR?and hydrogen spectroscopy?¹H NMR?.The experimental results indicated that the desulfurization rates of DBT,4,6-DMDBT,BT and real oil were 99.4%,98.6%,83.6%and 61.6%,respectively under the optimum conditions of V?Oil?5 m L,n?CF₃SO₃H?:n(C₆H₁₁NO)=0.5,reaction temperature=60°C,O/S=6,V?DESs?=1.0 m L.The stability of deep eutectic solvent was studied by infrared spectroscopy of recovered C₆H₁₁NO/0.5CF₃SO₃H.The stronger interaction between DBT and DESs was analyzed by infrared spectroscopy of DBT,DESs and DBT-DESs.This interaction promotes the process of oxidative desulfurization.After five recycling runs,its desulfurization rate was still as high as 91.9%,indicating that C₆H₁₁NO/0.5CF₃SO₃H has high catalytic desulfurization activity and stability.?2?[HMIM]BF₄/x C₉H₁₀O₂?x=0.5,1,2?types acidic deep eutectic solvents were synthesized using N-Methylimidazoliun fluoroborate?[HMIM]BF₄?and phenylpropionic acid(C₉H₁₀O₂)as raw materials;The DESs were characterized by FT-IR,¹H NMR and TGA.The experimental results indicated that the desulfurization rates of dibenzothiophene?DBT?,4,6-dimethyl-dibenzothiophene?4,6-DMDBT?and benzothiophene?BT?were98.4%,93%and 89.6%,respectively in the 5 m L oil under optimal condition of n(C₉H₁₀O₂)/n?[HMIM]BF₄?=0.5,reaction temperature of 60°C,reaction time of 180 min,n?H₂O₂?/n?S?of 8,V?DESs?of 1.0 m L.Infrared spectroscopy analysis showed a strong interaction between DBT and deep eutectic solvents?DESs?,which can cause the structure of DBT to be distorted and oxized.After 5 cycles of reaction,the desulfurization rate was still as high as 90.2%,indicating that[HMIM]BF₄/0.5C₉H₁₀O₂has high stability.?3?A series of[EMIM]DEP/n C₃H₄O₄?n=1,2,3?deep eutectic solvents?DESs?were synthesized by heating and stirring the mixture of1-ethyl-3-methylimidazolium diethylphosphate?[EMIM]DEP?and propanedioic acid?C₃H₄O₄?.[EMIM]DEP/2C₃H₄O₄was characterized by Fourier transform infrared?FT-IR?,¹H nuclear magnetic resonance?¹H NMR?and Thermogravimetric analysis?TGA?.Dibenzothiophene?DBT?in model oil was removed using the DESs as extractant and catalyst,and H₂O₂as oxidant.The experimental results show that removal rate of DBT can attach to98.2%.FT-IR analysis of DBT,DESs and the mixture?DBT-DESs?show that there is an interaction between DBT and DESs.The interaction leads to DBT more easily to be oxized,it further increase removal rate of DBT.