Clean Technology (청정기술)

The Korean Society of Clean Technology (한국청정기술학회)
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Effect of Isopropanol on CO2 Absorption by Diethylenetriamine Aqueous Solutions

이소프로판올을 포함한 디에틸렌트리아민 상분리 흡수제의 CO2 흡수 특성

  • Lee, Hwa Young (School of Chemical and Materials Engineering, Korea National University of Transportation) ;
  • Seok, Chang Hwan (School of Chemical and Materials Engineering, Korea National University of Transportation) ;
  • Hong, Yeon Ki (School of Chemical and Materials Engineering, Korea National University of Transportation)
  • 이화영 (한국교통대학교 응용화학에너지공학부 화공생물공학전공) ;
  • 석창환 (한국교통대학교 응용화학에너지공학부 화공생물공학전공) ;
  • 홍연기 (한국교통대학교 응용화학에너지공학부 화공생물공학전공)
  • Received : 2021.07.12
  • Accepted : 2021.08.06
  • Published : 2021.09.30
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Abstract

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.

아민 수용액을 이용한 CO2 포집 공정의 문제점은 재생에 따른 높은 에너지 요구량이다. 이러한 단점을 극복하기 위해서 본 연구에서는 디에틸렌트리아민(diethylenetriamine, DETA) 수용액에 이소프로판올(isopropanol, IPA)을 도입한 상분리 흡수제 적용에 따른 CO2 포집 특성을 고찰하였다. 20 wt% DETA 수용액에서 IPA 조성이 20 wt%를 이상이 되면 CO2를 흡수함에 따라 흡수제의 상이 CO2-농축상과 CO2-희박상으로 액-액 분리된다. 그 이유는 CO2와 DETA가 반응하여 형성된 염의 IPA에 대한 낮은 용해도 때문이다. DETA 수용액에서 IPA 조성이 증가하면 CO2-희박상의 부피에 대한 CO2-농축 상의 부피비가 증가하게 되고 이에 따라 CO2-희박상에서의 CO2 농축 정도가 높아지게 된다. 20 wt% DETA + IPA + 물 흡수제를 이용하여 흡수탑에서 CO2를 흡수한 결과 20 wt% DETA 수용액 흡수제에 비해 CO2 흡수능 및 흡수속도가 모두 높은 것으로 확인되었다. DETA + IPA + 물로 구성된 상분리 흡수제를 CO2 포집에 적용할 경우 상분리 따른 CO2 농축과 CO2-농축상의 부피 감소에 따른 재생에너지 저감을 기대할 수 있다.

Keywords

Acknowledgement

이 논문은 한국에너지기술연구원 2018년도 주요사업의 지원을 받아 수행된 연구임(B5-2436).

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