Shuai Wang  Jin Kyu Lee  Jong Kyun You  Yeon Ki Hong

Vol. 30,  No. 4, pp. 337-344, Dec.  2024
10.7464/ksct.2024.30.4.337

CO2 capture Biphasic absorbent EAE DEGDEE

PDF

A water-lean biphasic absorbent was used in order to reduce the energy required for absorbent regeneration in the conventional aqueous amine-based CO2 capture process. Secondary amines, EAE (2-(ethylamino) ethanol) and BAE (2-(butylamino) ethanol), were used as the main absorbents, and seven ether-based organic solvents with different logP were tested as phase-separation inducers. An absorbent that exists as a single phase before CO2 absorption but undergoes liquid-liquid phase separation after CO2 absorption was selected because its high CO2 absorption performance and viscosity were suitable for practical application. The absorbent composed of EAE/DEGDEE (diethylene glycol diethyl ether)/water was evaluated for its CO2 absorption performance based on the concentration of the organic solvent. For the 5 M EAE/20 wt% DEGDEE/water absorbent, the cyclic CO2 absorption capacity was 110 gCO2/Lsolvent, which was 1.8 times more than the cyclic absorption capacity of the conventional MEA (monoethanolamine) aqueous solution. This can be attributed to the CO2 enrichment effect that results from phase separation due to the low solubility of carbamate in the organic solvent as well as the reduced stability of the carbamate formed after CO2 absorption. 13C NMR analyses revealed that the CO2-lean phase primarily contained organic solvents, while the CO2-rich phase consisted of active amine, EAE carbamate, and protonated EAE.