pH swing cycle for CO2 capture electrochemically driven through proton-coupled electron transfer

2020 ◽  
Vol 13 (10) ◽  
pp. 3706-3722
Author(s):  
Shijian Jin ◽  
Min Wu ◽  
Roy G. Gordon ◽  
Michael J. Aziz ◽  
David G. Kwabi
Keyword(s):  
Electron Transfer ◽  
Co2 Capture ◽  
Redox Reactions ◽  
Organic Molecules ◽  
Aqueous Electrolyte ◽  
Energetic Cost ◽  
Proton Coupled Electron Transfer ◽  
Electrochemical Redox ◽  
Ph Swing

This study analyzes the energetic cost of CO2 separation using a pH swing created by electrochemical redox reactions of organic molecules involving PCET in aqueous electrolyte, and compares the experimental energetic cost to other methods.

scholarly journals pH Swing Cycle for CO2 Capture Electrochemically Driven through Proton-Coupled Electron Transfer

2019 ◽  
Author(s):  
Michael Aziz ◽  
David G. Kwabi
Keyword(s):  
Electron Transfer ◽  
Electrochemical Reduction ◽  
Flue Gas ◽  
Open Circuit ◽  
Solution Ph ◽  
Proton Coupled Electron Transfer ◽  
Work Input ◽  
Air Capture ◽  
Electrochemical Redox ◽  
Ph Swing

We propose and perform a thermodynamic analysis of the energetic costs of CO<sub>2</sub> separation from flue gas using a pH swing created by electrochemical redox reactions involving proton-coupled electron transfer from molecular species in aqueous electrolyte. Electrochemical reduction of these molecules results in the formation of alkaline solution, into which CO<sub>2</sub> is absorbed; subsequent electrochemical oxidation of the reduced molecules results in the acidification of the solution, triggering the release of pure CO<sub>2</sub> gas. We examined the effect of buffering from the CO<sub>2</sub>-carbonate system on the solution pH during this pH swing cycle, and thus on the open-circuit potential of a hypothetical electrochemical cell in a 4-step CO<sub>2</sub> capture-release cycle. The thermodynamic minimum work input varies from 16 to 75 kJ/mol<sub>CO2 </sub>as throughput increases, for both flue gas and direct air capture, with the potential to go substantially lower if CO<sub>2</sub> capture or release is performed simultaneously with electrochemical reduction or oxidation. These values are compared with those for other separation methods. We discuss the properties required of molecules that would be suitable for such a cycle.

scholarly journals pH Swing Cycle for CO2 Capture Electrochemically Driven through Proton-Coupled Electron Transfer

2019 ◽  
Author(s):  
Michael Aziz ◽  
David G. Kwabi
Keyword(s):  
Electron Transfer ◽  
Electrochemical Reduction ◽  
Flue Gas ◽  
Open Circuit ◽  
Solution Ph ◽  
Proton Coupled Electron Transfer ◽  
Work Input ◽  
Air Capture ◽  
Electrochemical Redox ◽  
Ph Swing

We propose and perform a thermodynamic analysis of the energetic costs of CO<sub>2</sub> separation from flue gas using a pH swing created by electrochemical redox reactions involving proton-coupled electron transfer from molecular species in aqueous electrolyte. Electrochemical reduction of these molecules results in the formation of alkaline solution, into which CO<sub>2</sub> is absorbed; subsequent electrochemical oxidation of the reduced molecules results in the acidification of the solution, triggering the release of pure CO<sub>2</sub> gas. We examined the effect of buffering from the CO<sub>2</sub>-carbonate system on the solution pH during this pH swing cycle, and thus on the open-circuit potential of a hypothetical electrochemical cell in a 4-step CO<sub>2</sub> capture-release cycle. The thermodynamic minimum work input varies from 16 to 75 kJ/mol<sub>CO2 </sub>as throughput increases, for both flue gas and direct air capture, with the potential to go substantially lower if CO<sub>2</sub> capture or release is performed simultaneously with electrochemical reduction or oxidation. These values are compared with those for other separation methods. We discuss the properties required of molecules that would be suitable for such a cycle.

Development of functionality of metal complexes based on proton-coupled electron transfer

2020 ◽  
Vol 49 (22) ◽  
pp. 7284-7293 ◽  
Author(s):  
Takahiko Kojima
Keyword(s):  
Electron Transfer ◽  
Metal Complexes ◽  
Redox Reactions ◽  
Proton Coupled Electron Transfer

Proton-coupled electron transfer (PCET) is ubiquitous and fundamental in many kinds of redox reactions. In this paper, are described PCET reactions in metal complexes to highlight their useful and unique properties and functionalities.

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