CO2 Absorption in Mixed Aqueous Solution of MDEA and Cholinium Glycinate

A new mixed solvent system that consists of cholinium glycinate ([Cho][Gly]) and aqueous N -methyldiethanolamine (MDEA) solution was developed in this work to serve as CO 2 absorbent. The equilibrium absorption was carried out to investigate the effect of solution composition, pressure, and temperature on CO 2 absorption performance. The effect of CO 2 absorption on the viscosity of the aqueous solutions was studied, and the regeneration efficiency of the aqueous solutions was also investigated. The results showed that the CO 2 absorption loading decreased with increasing [Cho][Gly] concentration and temperature, and the absorption loading strongly depended on CO 2 partial pressure. The reactivity of MDEA was significantly enhanced with the addition of [Cho][Gly]. The aqueous solution with (10 wt % [Cho][Gly] + 20 wt % MDEA) showed an optimal CO 2 absorption and high regeneration efficiency. Furthermore, the CO 2 absorption mechanism in the aqueous [Cho][Gly]-MDEA solution was explored by 13 C nuclear magnetic resonance, which indicated that the CO 2 absorption in the aqueous [Cho][Gly]-MDEA solution was a zwitterion mechanism.