Synthesis And Denitrogenation Of Imidazole-based Ionic Liquids

It is imperative to remove the organic nitrogen compounds(N-compound)in the fuel oil to meet the environmental regulations.Compared with other denitrogenation technologies,the removal of N-compound by ionic liquids(ILs)are favorable for the merits of mild denitrogenation conditions and simple synthesis process.In this thesis,imidazole-based ionic liquids and dicationic ionic liquids were synthesized,and the denitrogenation effect of different reaction conditions of ILs on quinoline and indole in simulated oil were investigated.Moreover,the recycling denitrogenation performance of ILs on commercial diesel was also studied.The main results are as follows:Six imidazole-based ILs were synthesized by using 1-benzyl-2-methylimidazole and vinyl-imidazole as raw materials,and their structures were characterized by nuclear magnetic resonance(¹H NMMR)and infrared spectra(IR).Afterwards,the denitrogenation processes of ILs on simulated oil and commercial diesel were investigated.It has shown that imidazole-based ILs with-SO₃H group possess good removal efficiency for quinoline,and those ILs with benzyl group show high removal efficiency for indole.Three Imidazole-based ILs were consequently selected to carry out the detailed denitrogenation to simulated oil study,such as mass ratio of IL to H₂O,reaction temperature,reaction time,and the mass ratio of ionic liquid.The experimental results show that these three ionic liquids have thesametrendsindenitrogenationtosimulatedoil.Taking1-[propylsulfonate]-2-methyl-3-benzylimidazolium hydrogensulfate(BMS HSO₄)as an example,the denitrogenation efficiency of BMS HSO₄ to quinoline and indole were 93.9%and 52.5%,under the condition of 40 ^oC for 20 min,with a 1:0.5 mass ratio of ionic liquid to H₂O and a 1:5 mass ratio of IL to simulated oil,respectively.It is inspired that the denitrogenation efficiency did not show significant decrease after repeated use for 5 times.Farther experiments indicate that a 50.3%of the denitrogenation efficiency of BMS HSO₄ on commercial diesel was obtained.Thirteen dicationic ionic liquids(DILs)were synthesized by the starting material of imidazole,2-ethylimidazole and 1-benzyl-2-methylimidazole,and their denitrogenation properties to simulated oil were successively examined,which revealed that?-?conjugation can improve the removal efficiency of ionic liquids for indole.Three DILs with p-toluenesulfonic(Ts O)as anion were selected to determine the effect of different reaction conditions.The denitrogenation efficiencies to1,2-bis(1-benzyl-2-methylimidazolium)ethane p-toluenesulfonate(C₂BM Ts O)to quinoline and indole in simulated oil were 96.5%and 94.5%,respectively,with a 1:1 of the mass ratio of DIL to H₂O,and1:10 of the mass ratio of DIL to oil at 25 ^oC for 10 min.The denitrogenation efficiency in simulated oil of C₂BM Ts O did not show significant decrease after repeated use for 5 times.Under the same condition,the denitrogenation efficiency of C₂BM Ts O to commercial diesel was 72.1%.This thesis succeeds to synthesize ILs with the advantages of easy synthesis,high yield,and recyclable usage for denitrogenation.DILs highlight to remove the N-compound from fuel oils for mild processing condition instead of unkind condition the hydrodenitrogenation process.It can be expected that the results of this thesis refer the ionic liquids application in the denitrogenation of fuel oil.