Electro-swing adsorption separates CO2 from mixed gases at any concentration
By Scott Jenkins |
Effectively separating carbon dioxide from combustion exhaust or directly from air is essential for realizing net reductions in greenhouse-gas emissions, but existing technologies for CO2 capture (such as CO2-scrubbing with amines), involve parasitic energy losses, which make carbon-capture economics unfavorable. To address this, researchers from the laboratory of T. Alan Hatton at the Massachusetts Institute of Technology (MIT; Cambridge, Mass.; www.mit.edu) Department of Chemical Engineering have demonstrated the first voltage-dependent separation of CO2 from mixed-gas using electro-swing adsorption (ESA).
MIT’s device is an electrochemical cell that selectively captures CO2 when current is applied in one direction, and releases CO2 when the current is reversed. The ESA system takes advantage of the fact that the molecule quinone, in its two reduced forms, reacts with CO2 in a nucleophilic addition, but has no affinity for CO2 in its oxidized form, explains Sahag Voskian, a post-doctoral researcher at MIT. “It is this binary nature of the affinity of quinone to CO2 at its different oxidation states which makes this system unique,” Voskian notes.
The researchers synthesized cathode material by polymerizing quinone and suspending…