본 연구에서는 이산화탄소(CO2)의 습식 포집 공정에서 흡수제 재생에 필요한 에너지 저감을 목표로 물 함량을 줄

인 저수계 상분리 흡수제를 개발하였다. 흡수제를 구성하는 주 흡수제로는 1차 및 2차 아민기를 모두 포함한 디에틸

렌트리아민(diethylenetriamine, DETA)을 사용했으며 물을 대체하고 상분리를 유도하는 유기용매로는 2-에톡시에탄

올(2-ethoxyethanol, 2-EE)을 도입하였다. 다양한 DETA 농도(1.5-2.5M)와 2-EE 함량(30-60 wt%)에 대해 CO2 흡수

에 따른 흡수제의 상분리 특성, CO2 흡수 용량 및 순환 용량을 평가하였다. CO2와 DETA와의 반응을 통해 형성된

탄산염은 물에 대한 용해도가 높지만 2-EE에 대해서는 용해도가 낮아, 결과적으로 CO2 농축상과 희박상으로 상분리

가 유도된다. 상분리에 따른 CO2 농축율과 흡수제의 점도를 고려했을 때 최적의 흡수제 조성은 1.5M DETA와 50

wt% 2-EE로 확인되었으며 이때 CO2 농축상에서의 CO2 흡수 용량은 321 gCO2/Lsolvent, 순환 흡수 용량은 142

gCO2/Lsolvent였다. 이는 기존의 30 wt% 모노에탄올아민 수용액 대비 각각 약 3배, 2배 이상 우수한 성능을 나타낸

다. 13C NMR 분석을 통해 CO2 흡수 생성물로 카바메이트, 바이카보네이트 및 양성자화 아민이 형성됨을 확인하였

으며 이들 종의 물과 2-EE 간 용해도 차이가 상분리의 주요 요인인 것으로 나타났다. 본 연구에서 개발한 흡수제는

상분리 기반의 높은 CO2 농축 및 재생 효율을 통해 저에너지 CO2 포집 공정에 효과적으로 적용할 수 있는 가능성

을 제시한다.

In this study, a water-lean biphasic solvent system was developed to reduce the energy demand for solvent

regeneration in post-combustion CO2 capture processes. Diethylenetriamine (DETA), a polyamine containing both

primary and secondary amine groups, was used as the primary absorbent, while 2-ethoxyethanol (2-EE), and ether-based

alcohol, was introduced as an organic solvent to replace water and induce phase splitting. The effect of varying DETA

concentrations (1.5~2.5 M) and 2-EE contents (30~60 wt%) on the phase separation behavior, CO2 loading, and cyclic

capacity were systematically evaluated. The carbamate species generated from CO2-DETA reaction showed high

solubility in water but poor solubility in 2-EE, thereby inducing phase splitting into a CO2-rich lower phase and a CO2-

lean upper phase. Considering both CO2 enrichment and manageable viscosity, the optimal solvent composition was

identified as 1.5M DETA with 50 wt% 2-EE. Under this condition, the CO2 loading in the rich phase reached 321 gCO2/

Lsolvent and the cyclic loading was 142 gCO2/Lsolvent, which are approximately three and two times higher, respectively,

than those of conventional 30 wt% monoethanolamine (MEA) aqueous solutions. 13C NMR analysis confirmed the

formation of carbamate, bicarbonate, and protonated amine species and their differential solubility in water and 2-EE

was found to be the primary cause of phase separation. The developed biphasic solvent demonstrates potential for application

in energy-efficient CO2 capture, offering both enhanced CO2 enrichment and improved regeneration performance via

liquid-liquid phase separation.

CO2 capture, Regeneration energy, Biphasic solvent, Diethylenetriamine, 2-Ethoxyethanol

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