Character And Kinetics Of CO₂absorption In The Solution Of Imidazolium-based Functionalized Amino Acids Ionic Liquids [Hmim][Gly]

Carbon dioxide （CO₂）, a major greenhouse gas, exerts profound impacts onglobal climate change. Meanwhile, CO₂is also an important carbon source. Therefore,many scientists are interested in capturing and storing CO₂for various commercialapplications. An advanced aqueous amine solvent of1-hexyl-3-methylimidazoliumglycinate （[Hmim][Gly]） and the mixed solution of [Hmim][Gly]-AMP were used asthe absorbent. Physicochemical features of the absorbent were measured andcaculated. The absorption performance, the regeneration behavior and the absorptionkinetics were studied by using a double stirred cell absorber and bubbling absorber.In this work, the result demonstrated that the CO₂absorption rate into the[Hmim][Gly] solution was the fastest of MEA, DEA, AMP. Density, viscosity and pHof [Hmim][Gly] solution and [Hmim][Gly]-AMP solutions increased as theconcentration of the [Hmim][Gly] increased and decreased as the temperatureincreased. The solubility and diffusion coefficient of CO₂in the [Hmim][Gly] soltuonand [Hmim][Gly]-AMP solution decreased systematically as the concentration of[Hmim][Gly] increased, and the solubility of CO₂decreased with the increase oftemperature, but the diffusion coefficient of CO₂showed the opposite phenomenon.The absorption rate of CO₂into [Hmim][Gly] solution and [Hmim][Gly]-AMPsolution was investigated by using a double stirred-cell absorber. The effects of the[Hmim][Gly] concentration and temperature on the absorption rate of CO₂into theaqueous [Hmim][Gly] and [Hmim][Gly]-AMP were studied. It showed that both theCO₂absorption rate and the absorption amount increased as the [Hmim][Gly]concentration and temperature increased, but the CO₂loading in the [Hmim][Gly]solution decreased as the [Hmim][Gly] concentration increased. Temperature had aslightly influence on the CO₂absorption rate in the [Hmim][Gly] solution and[Hmim][Gly]-AMP solution between298to323K. The regeneration efficiency of theCO₂-loaded [Hmim][Gly] soltuon and [Hmim][Gly]-AMP solution were high, andincreased with the increase of the regeneration temperature and the regeneration timeunder0.095MPa. The optimum regeneration temperature and the optimumregeneration time of the CO₂-loaded [Hmim][Gly] solution were338K and90min, and the values of the CO₂-loaded [Hmim][Gly]-AMP solution were333K and90min,respectively. The regeneration efficiency of the CO₂-loaded [Hmim][Gly] solution inturn was96.7%,95.0%,88.8%for the first, the second, and the third cycle ofregeneration, and the values of the CO₂-loaded [Hmim][Gly]-AMP solution in turnwas96.73%,95.30%,94.07%, respectively.The kinetics study showed that the CO₂absorption into the [Hmim][Gly]solution and [Hmim][Gly]-AMP solution was the fast pseudo-first order reactionregime. E of the [Hmim][Gly] solution was linear with CIL1/2. The Arrheniusequations of the second-order rate constant, for the reaction of the [Hmim][Gly]solution and [Hmim][Gly]-AMP solution with CO₂, were obtained, and the activationenergy were25.36,28.00kJ·mol-1, respectively.