Proton coupled electrochemical co2 capture system
AssigneePresident and Fellows of Harvard College
InventorsMichael J. AZIZ, David Gator KWABI
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Abstract
The invention provides an electrochemical CO2 capture device and methods employing proton-coupled redox active species, e.g., a quinone, phenazine, alloxazine, isoalloxazine, or polyoxometalate, whose protonation and deprotonation can be controlled electrochemically to modify the pH of an aqueous solution or aqueous suspension. This change in pH can be used to sequester and release CO2. The CO2 capture device can be used to sequester gaseous CO2 from a point source, such as flue gas, or from ambient air.
Claims20
A device for capturing CO2 comprising a liquid flow path comprising:
- a) a first region comprising a first inlet and a first outlet and an aqueous solution or suspension comprising a proton-coupled redox active species, wherein the first region is configured to receive a gas comprising CO2 via the first inlet, allow the gas to contact the aqueous solution or suspension, and to release the gas depleted of CO2 via the first outlet;
- b) a second region fluidically connected to the first region and comprising at least one electrode;
- c) a third region fluidically connected to the second region and comprising a second outlet, wherein the third region is configured to release CO2 outgassing from the aqueous solution or suspension via the second outlet;
- and
- d) a fourth region fluidically connected to the first and third regions and comprising at least one electrode,
- wherein oxidation of the proton-coupled redox active species releases one or more protons to decrease the pH of the aqueous solution or suspension and reduction of the proton-coupled redox active species takes up one or more protons to increase the pH of the aqueous solution or suspension.
A method of capturing CO2, the method comprising the steps of:
- a) providing an aqueous solution or suspension comprising a proton-coupled redox active species and having a first pH;
- b) allowing a gas comprising CO2 to contact the aqueous solution or suspension under conditions for the CO2 to dissolve into the aqueous solution or suspension;
- c) converting the pH of the aqueous solution or suspension to a second pH by oxidizing the proton-coupled redox active species;
- d) allowing the dissolved CO2 to outgas from the aqueous solution or suspension;
- and
- e) converting the pH of the aqueous solution or suspension to a third pH by reducing the proton-coupled redox active species.
Dependencies are inferred from the claim text.