CO₂ Absorption Into The Mixed Aqueous Solution Of MDEA And Amino Acid Ionic Liquid

The rise of carbon dioxide concentration in the atmosphere is one of the most pressing environmental problems of our time. To develop an efficient and economic absorbent for the capture of carbon dioxide from coal-fired power plants is an important task for the control and reduction of carbon dioxide emissions. MDEA is now widely used in industry due to its excellent thermal stability, low oxidation degradation and regeneration energy. The focus of this paper is to optimize the synthesis process of a functional amino acid ionic liquid, and in MDEA aqueous solution. And the functional ionic liquid has been mixed with MDEA to improve the absorption rate of MDEA to make it more conducive to industrial application. The paper has obtained the following research results:(1) The synthesis of [C20Hmim]Cl and [C20Hmim]OH is the most important part in the synthesis of [C20Hmim]Gly, so the effect of different process parameters on the yield and purity of [C20Hmim]Cl and [C2OHmim]OH was investigated. And the result showed that when [C20Hmim]Cl was obtained with N-methyl imidazole and 2-chloride ethanol at the ratio of 1:1.3 at 70℃ for 24h under N2. Its yield is 98.3% and its purity is 95.04%. In the synthesis of [C2OHmim]OH, the time cost in the static method is 1/4 of that cost in the dynamic method. And the water used in the static method is 1/2 of that used in the dynamic method. And the transformation rate in the static method is 70% and that in the dynamic method is 90%. With the optimum synthesis process, the purity of the final product can reach 97.53%.(2) The mixed solution of MEA and [C20Hmim]Gly was used to absorb CO2. The absorption rate of the mixed solution was much improved compared with single MDEA solution. When the mole ratio of MDEA and [C2OHmim]Gly is 8:2, the absorption rate is 2.7 times much than that of the single MDEA solution. Meanwhile, the mixed solution had a good performance in thermal stability, low oxidation degradation and regeneration energy consumption.(3) The reaction mechanism of the CO2 absorption into the mixed solution of MDEA and [C20Hmim]Gly was clarified. Some important kinetic equation and parameters were obtained. At 323.15K, the mathematic relation between the enhancement factor and the concentration of [C20Hmim]Gly accorded with the following equation:E=-32.SC[C2OHmim][Gly]+76.85C[c2OHmim][Gly]+2.385. Besides, the mathematic relation between reaction rate constant of the mixed solution and the temperature accorded with the following equation:kmixed= 8.1 ×1011× exp(-7002.9/T)。...