Quinone Reduction in Ionic Liquids for Electrochemical CO2 Separation

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• 作者：Burcu Gurkan ; Fritz Simeon ; T. Alan Hatton
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2015
• 出版时间：July 6, 2015
• 年：2015
• 卷：3
• 期：7
• 页码：1394-1405
• 全文大小：624K
• ISSN：2168-0485

文摘

We report the redox activity of quinone materials, in the presence of ionic liquids, with the ability to bind reversibly to CO₂. The reduction potential at which 1,4-naphthoquinone transforms to the quinone dianion depends on the strength of the hydrogen-bonding characteristics of the ionic liquid solvent; under CO₂, this transformation occurs at much lower potentials than in a CO₂-inert environment. In the absence of CO₂, two consecutive reduction steps are required to form first the radical anion and then the dianion, but with the quinones considered here, a single two-electron wave reduction with simultaneous binding of CO₂ occurs. In particular, the 1,4-napthoquinone and 1-ethyl-3-methylimidazolium tricyanomethanide, [emim][tcm], system reported here shows a higher quinone solubility (0.6 and 1.9 mol路L^鈥? at 22 and 60 掳C, respectively) compared to other ionic liquids and most common solvents. The high polarity determined through the Kamlet鈥揟aft parameters for [emim][tcm] explains the measured solubility of quinone. The achieved high quinone solubility enables effective CO₂ separation from the dilute gas mixture that is contact with the cathode by overcoming back-diffusive transport of CO₂ from the anodic side.