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Carbon Capture Facilitated By Ionic Liquid’s Phase Change

ACS Meeting News: Technology could reduce the energy required to trap carbon dioxide

by Jyllian Kemsley
August 18, 2014 | A version of this story appeared in Volume 92, Issue 33

This week’s selections are from the ACS national meeting, which took place on Aug. 10–14 in San Francisco.

An ionic-liquid-based material that changes from solid to liquid upon reacting with carbon dioxide could lower the energy costs of capturing CO2 from power plant emissions, reported Joan F. Brennecke of the University of Notre Dame. The so-called phase-change ionic liquid (PCIL) is composed of a tetraethylphosphonium salt that is solid at normal postcombustion flue gas temperatures of 40 to 80 °C. CO2 reacts stoichiometrically and reversibly with an aprotic heterocyclic anion, reducing the melting point of the material and turning the solid into a liquid (Energy Fuels 2014, DOI: 10.1021/ef501374x). In the proposed process, a slurry of the solid PCIL and PCIL-CO2 would be used in an absorber to capture more CO2. The resulting liquid would be heated to drive off the CO2 for storage elsewhere while the PCIL is reused. The combined enthalpies of the CO2 binding and release reactions and the associated phase changes would reduce the external energy consumed by carbon capture to about 23% of the energy produced by a conventional coal power plant, compared with 28% for current carbon capture systems.

A phase-change ionic liquid changes from solid to liquid upon reaction with carbon dioxide.
Credit: Energy Fuels
A phase-change ionic liquid changes from solid to liquid upon reaction with CO2.


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