Synthesis Of Triethylenediamine Dinucleic Acid Ionic Liquids And Their's Applicationin In Oil Denitrification

Fuel oil contains nitrogen compounds,which will generate NO_x after combustion and seriously pollute the environment.Moreover,the presence of nitrogen compounds will cause stability of oil to deteriorate and affect hydrodesulfurization process.Therefore,research on the effect of removal of nitrogen compounds on protection of the environment and fuel oil quality is very necessary.At present,the popular industrial denitrification method is hydrodenitrogenation,but it requires a large amount of hydrogen sources,harsh operating condition and difficult to obtain high denitrification efficiency.Not only because of increasingly stringent environmental regulations,but also the presence of nitrogen compounds will inhibit hydrodesulfurization process.In this context,it is very necessary to develop non-hydrodenitrogenation to purify fuels.Ionic liquids(ILs)as a new type of solvent,it has irreplaceable advantages of traditional solvents,such as non-volatile,designable structure and properties,wider liquid range,higher stability,and stronger dissolving ability.They have attracted extensive attention from scholars at home and abroad.In this paper,three different types of triethylenediamine ILs were synthesized from cheap triethylenediamine and used it for the first time in denitrification,which provided an efficient,environmentally friendly,economically feasible new way for denitrification.A series of sulfonated dinucleic acid ILs were synthesized form triethylenediamine and 1,3-propane sultone.The structure and properties of ILs were determined by ¹H NMR,FT-IR and UV-vis.Acidic strength order of ILs with different anionic structures was as follows:HSO₄^->CH₃SO₃^->H₂PO₄^->BF₄^->Cl^-.The mutual solubility of ILs with common organic solvents and the solubility of ILs were investigated.The sulfonated dinucleic acid ILs were applied to oil denitrification,and[DABCO-PS]HSO₄was obtained with better extraction effect of quinoline and indole.The optimal extraction conditions of quinoline were as follows:IL/oil mass ratio is 1:10,IL/H₂O mass ratio is 1:1,extraction temperature is 30?,extraction time is 1.0 h,and standing time is 15 min,the removal rate of quinoline is 93%.The optimal extraction conditions of indole were as follows:IL/oil mass ratio is 1:5,IL/H₂O mass ratio is 1:0,extraction temperature is 40?,extraction time is 1.0 h,and standing time is 20 min,the removal rate of indole is 84%.[DABCO-PS]HSO₄was reused five times,removal rate did not decrease significantly,and the FT-IR spectra of IL before and after reuse were almost identical.In order to obtain better denitrification effect of ILs,a series of alkylated dinucleic acid ILs were synthesized using triethylenediamine and bromoethane as raw materials.The structure of ILs was characterized and analyzed by ¹H NMR?FT-IR and UV-vis.Acidic strength order of ILs with different anionic structures was as follows:HSO₄^->CH₃SO₃^-?C₇H₇SO₃^->H₂PO₄^->Cl^-,acidity of alkylated binuclear acid ILs is relatively strong.The solubility of ILs and the mutual solubility of conventional organic solvents were measured.Using C₂H₅N(C₆H₁₂)NC₂H₅·2CH₃SO₃as extraction agent,under better extraction conditions:IL/oil mass ratio is 1:15,IL/H₂O mass ratio is 1:1,extraction temperature is 30?,extraction time is 1.5 h,and standing time is 0.5 h,the removal rate of quinoline is 99%;Using C₂H₅N(C₆H₁₂)NC₂H₅·2HSO₄ as extraction agent,under better extraction conditions:IL/oil mass ratio is 1:5,IL/H₂O mass ratio is 1:0,extraction temperature is 30?,extraction time of 1.0 h,and standing time of 1.5 h,the removal rate of indole is98%.ReusepropertiesofC₂H₅N(C₆H₁₂)NC₂H₅·2HSO₄and C₂H₅N(C₆H₁₂)NC₂H₅·2CH₃SO₃ was investigated.The results showed that removal rate of IL did not decrease significantly and FT-IR spectra of IL did not change before and after reuse.Deep eutectic solvents(DESs)are special IL analogues.Compared with ILs,synthesis process is simpler and cost is lower.Triethylenediamine DESs was synthesized by using triethylenediamine as the hydrogen bond acceptor and glacial acetic acid,ethylene glycol,acetamide,glycerol as hydrogen bond donors.Using triethylenediamine DESs to oil denitrification,and C₆H₁₂N₂-2C₂H₄O₂ as better extractant,removal efficiency of quinoline was 97%under the optimal extraction conditions of DES/oil mass ratio 1:10,DES/H₂O mass ratio 1:1,extraction temperature 40?,extraction time 1.0 h,standing time is 25 min;and removal efficiency of indole was 91%under the optimal extraction conditions of DES/oil mass ratio 1:5,DES/H₂O mass ratio 1:1,extraction temperature 20?,extraction time 1.5 h,standing time is 20 min.C₆H₁₂N₂-2C₂H₄O₂was characterized by ¹H NMR,FT-IR and TGA,structure and thermal stability before and after reuse were not damaged,and removal rate of C₆H₁₂N₂-2C₂H₄O₂ was reused for 5 times without significant decrease.As far as we know,the above fundamental studies have not been reported in the literature.