Spontaneous Cooling Absorption of CO2 by a Polymeric Ionic Liquid for Direct Air Capture

Tao Wang; Chenglong Hou; Kun Ge; Klaus Lackner; Xiaoyang Shi; Jun Liu; Mengxiang Fang; Zhongyang Luo

doi:10.1021/acs.jpclett.7b01726

Spontaneous Cooling Absorption of CO₂ by a Polymeric Ionic Liquid for Direct Air Capture

Tao Wang, Chenglong Hou, Kun Ge, Klaus Lackner, Xiaoyang Shi, Jun Liu, Mengxiang Fang, Zhongyang Luo

Research output: Contribution to journal › Article › peer-review

29 Scopus citations

Abstract

A polymeric ionic liquid (PIL), with quaternary ammonium ions attached to the polymer matrix, displays CO₂ affinity controlled by moisture. This finding led to the development of moisture swing absorption (MSA) for direct air capture of CO₂. This work aims to elucidate the role of water in MSA. For some humidity range, CO₂ absorption is an endothermic process associated with concurrent dehydration of the sorbent. The thermodynamic behavior of water indicates a decreased hydrophilicity of the PIL as the mobile anion transforms from CO₃^2- to HCO₃^- during CO₂ absorption. The decrease in hydrophilicity drives water out of the PIL, carrying heat away. The mechanism is elucidated by molecular modeling based on density functional theory. The finding of spontaneous cooling during absorption and its mechanism in the PIL opens new possibilities for designing an air capture sorbent with a strong CO₂ affinity but low absorption heat.

Original language	English (US)
Pages (from-to)	3986-3990
Number of pages	5
Journal	Journal of Physical Chemistry Letters
Volume	8
Issue number	17
DOIs	https://doi.org/10.1021/acs.jpclett.7b01726
State	Published - Sep 7 2017

ASJC Scopus subject areas

Materials Science(all)
Physical and Theoretical Chemistry

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title = "Spontaneous Cooling Absorption of CO2 by a Polymeric Ionic Liquid for Direct Air Capture",

abstract = "A polymeric ionic liquid (PIL), with quaternary ammonium ions attached to the polymer matrix, displays CO2 affinity controlled by moisture. This finding led to the development of moisture swing absorption (MSA) for direct air capture of CO2. This work aims to elucidate the role of water in MSA. For some humidity range, CO2 absorption is an endothermic process associated with concurrent dehydration of the sorbent. The thermodynamic behavior of water indicates a decreased hydrophilicity of the PIL as the mobile anion transforms from CO32- to HCO3- during CO2 absorption. The decrease in hydrophilicity drives water out of the PIL, carrying heat away. The mechanism is elucidated by molecular modeling based on density functional theory. The finding of spontaneous cooling during absorption and its mechanism in the PIL opens new possibilities for designing an air capture sorbent with a strong CO2 affinity but low absorption heat.",

author = "Tao Wang and Chenglong Hou and Kun Ge and Klaus Lackner and Xiaoyang Shi and Jun Liu and Mengxiang Fang and Zhongyang Luo",

note = "Funding Information: This study is supported by the National Natural Science Foundation of China (No. 51676169) and the Fundamental Research Funds for the Central Universities. Publisher Copyright: {\textcopyright} 2017 American Chemical Society.",

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doi = "10.1021/acs.jpclett.7b01726",

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AU - Wang, Tao

AU - Hou, Chenglong

AU - Ge, Kun

AU - Lackner, Klaus

AU - Shi, Xiaoyang

AU - Liu, Jun

AU - Fang, Mengxiang

AU - Luo, Zhongyang

N1 - Funding Information: This study is supported by the National Natural Science Foundation of China (No. 51676169) and the Fundamental Research Funds for the Central Universities. Publisher Copyright: © 2017 American Chemical Society.

PY - 2017/9/7

Y1 - 2017/9/7

N2 - A polymeric ionic liquid (PIL), with quaternary ammonium ions attached to the polymer matrix, displays CO2 affinity controlled by moisture. This finding led to the development of moisture swing absorption (MSA) for direct air capture of CO2. This work aims to elucidate the role of water in MSA. For some humidity range, CO2 absorption is an endothermic process associated with concurrent dehydration of the sorbent. The thermodynamic behavior of water indicates a decreased hydrophilicity of the PIL as the mobile anion transforms from CO32- to HCO3- during CO2 absorption. The decrease in hydrophilicity drives water out of the PIL, carrying heat away. The mechanism is elucidated by molecular modeling based on density functional theory. The finding of spontaneous cooling during absorption and its mechanism in the PIL opens new possibilities for designing an air capture sorbent with a strong CO2 affinity but low absorption heat.

AB - A polymeric ionic liquid (PIL), with quaternary ammonium ions attached to the polymer matrix, displays CO2 affinity controlled by moisture. This finding led to the development of moisture swing absorption (MSA) for direct air capture of CO2. This work aims to elucidate the role of water in MSA. For some humidity range, CO2 absorption is an endothermic process associated with concurrent dehydration of the sorbent. The thermodynamic behavior of water indicates a decreased hydrophilicity of the PIL as the mobile anion transforms from CO32- to HCO3- during CO2 absorption. The decrease in hydrophilicity drives water out of the PIL, carrying heat away. The mechanism is elucidated by molecular modeling based on density functional theory. The finding of spontaneous cooling during absorption and its mechanism in the PIL opens new possibilities for designing an air capture sorbent with a strong CO2 affinity but low absorption heat.

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Spontaneous Cooling Absorption of CO₂ by a Polymeric Ionic Liquid for Direct Air Capture

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