Lee HY  Seok CH  Hong YK

Vol. 27,  No. 3, pp. 255-260, Sep.  2021
10.7464/ksct.2021.27.3.255

CO2 capture Biphasic absorbent Isopropanol Regeneration energy

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A drawback in the CO2 capture process using an aqueous amine solution is the high energy requirement for the regeneration process. In order to overcome this disadvantage, this study investigated CO2 capture characteristics using a biphasic absorbent in which isopropanol (IPA) was introduced into an aqueous solution of diethylenetriamine (DETA). When the IPA composition exceeded 20 wt% in 20 wt% DETA aqueous solution, the absorbent phase was liquid-liquid separated into a CO2-rich phase and a CO2-lean phase because of the low solubility of the salt formed by the reaction of CO2 with DETA in isopropanol. When the isopropanol composition in the DETA aqueous solution increased, the phase volume ratio of the CO2-rich phase to the volume of the CO2-lean phase increased; and, accordingly, the CO2 in the CO2-rich phase was more concentrated. The results of absorbing CO2 in a packed tower using 20 wt% DETA + IPA + water absorbent confirmed that both the CO2 absorption capacity and the absorption rate were higher than that of the 20 wt% DETA aqueous solution. When a biphasic absorbent composed of DETA + IPA + water is applied to CO2 capture, it can be expected to concentrate CO2 because of phase separation and thereby reduce regeneration energy owing to volume reduction of the CO2-rich phase.