Electrochemically Mediated CO2 Capture Using Aqueous Cu(II)/Cu(I) Imidazole Complexes

Jonathan Boualavong, Christopher A. Gorski

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6 Scopus citations

Abstract

A major goal of developing electrochemical CO2 capture technologies is to minimize the energy demand. One strategy for decreasing energy demands of electrochemical capture technologies is increasing the ratio of CO2 molecules captured per transferred electron. Here, we examined an electrochemical capture approach that has the potential to capture up to two CO2 molecules per electron, which is higher than many existing approaches. We used the Cu(II)/Cu(I) redox couple to control the aqueous availability of a CO2 sorbent, 1,2-dimethylimidazole (Me2Im, by transitioning between Cu(Me2Im)4(aq)2+ and Cu- (Me2Im)2(aq)+. As expected from equilibrium calculations, a solution containing reduced Cu(I) had a greater CO2 capacity than the oxidized Cu(II) state. In a bench-scale test, the energy demand for CO2 capture was 27 ± 6 kJe/mol C, despite operating at 7-11% energy efficiency due to a high experimentally-set cell voltage. We estimate that under market-ready concentration conditions and the same low energy efficiency, the energy demand will be approximately 65 ± 14 kJe/mol C, although it can only remove 60% of the CO2 from coal power plant flue gas (PCO2 = 0.15 atm) at equilibrium. To address this issue, we used an equilibrium model of the relevant chemical reactions to identify how altering the substituent groups on imidazole will influence the CO2 capture capacity and energy demand.

Original languageEnglish (US)
Pages (from-to)1084-1093
Number of pages10
JournalACS ES and T Engineering
Volume1
Issue number7
DOIs
StatePublished - Jul 9 2021

All Science Journal Classification (ASJC) codes

  • Chemical Engineering (miscellaneous)
  • Environmental Chemistry
  • Process Chemistry and Technology
  • Chemical Health and Safety

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