Prepare Of Task-Specific Ionic Liquids And Their Application In CO₂ Fixation

The weather is getting warmer and warmer, and everybody in the world is doing his best to reduce CO2 emission. Due to this situation, this paper carried out a series of research. At first, this paper tried to design and synthesize a kind of amino-functional ionic liquids, and then it tested the performance of these ionic liquids in CO2 fixation.In this paper, one-step method was used to prepare intermediate ionic liquid [emim]Br and [bmim]Br. The purity, yield and NMR spectra of products were tested to analyse the influence factors on their synthesis, and the results of experiment show as follows:[emim]Br was synthesized in ethyl acetate from N-methylimidazole and bromethyl at 35℃for 12h, and the mole fraction of excess bromethyl was 50%. Additionally, the purity of [emim]Br reached 94%. Furthermore, at 70℃[bmim]Br was obtained from N-methyl imidazole and bromo-butane at 1:1.1 molar ratio with ethyl acetate as the solvent reacting for 12h, and the purity was 98%.Amino-functional ionic liquids were prepared by using dynamic ion exchange & amino acids neutralization process, besides, intermediate ionic liquids and natural amino acids (glycine, alanine, lysine) were raw materials. In this research, single solvent methed was adopted to wash crude product, and static ion exchange method was carried out to solve the problem of waste water and time in dynamic method. Moreover, structure of the resulting liquid was confirmed by 1H NMR and IR. This research also tested density, viscosity, hygroscopicity, melting point, and electrochemical window of the products, and found that [emin]Gly with the shortest chain length of ions has a maximum density value of 1.152 g/cm3 and a minimum viscosity value of 103.43cP. However, [bmim]Lys with the longest chain length exhibited an opposite situation that the density and viscosity respectively were 1.067 g/cm3 and 517.13cP.In the last part of this paper, these amino-functional ionic liquids were applied to fix CO2. At first, they were directy used for CO2 fixation, then they were configured for different concentrations of aqueous absorption and then used for CO2 fixation. The experiments show that those functional ionic liquids can be used for CO2 fixation and had excellent reusable performance. Among these ionic liquids, [bmim]Gly had the largest direct absorption capacity of 0.467 molCO2/molIL due to unit amino. In addition, low concentration help CO2 fixation, and 0.5mol/L [emim]Lys was the best absorbent of 1.054 molCO2/molIL.