Investigation of CO2 capture efficiency and mechanism in 2-methylimidazole-glycol solution

Here, we report the fabrication of a stable CO2 capture medium by dissolving 2-methylimidazole in glycol. It was found that 2-methylimidazole dissolved in glycol well, and their mixture showed good flowability. For single CO2 absorption in the 10 wt% 2-methylimidazole-glycol solution, the molar ratio between CO2 and 2-methylimidazole molecules reached 0.79 at 293.15 K and 18.73 bar. It was supposed that an alkylcarbonate salt formed upon contact between 2-methylimidazole, glycol and CO2. This CO2 absorption mechanism was further characterized by using the Fourier-transform infrared technology. For CO2/N2 (20.65/79.36 mol%) gas mixture separation in the 30 wt% 2-methylimidazole-glycol solution, the equilibrium partial pressure of CO2 in the gas phase could be decreased to as low as 0.10 bar with the selectivity of CO2 over N2 reaching 239 at 293.15 K and 4.55 bar. More importantly, the CO2 uptake in 2-methylimidazole-glycol solution was reversible, CO2 was readily desorbed from the solution through vacuuming at room temperature and with no apparent liquid loss. This work opens up the possibility of applying imidazole-alcohols mixtures to CO2 capture.