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More Efficient Carbon Capture Method Revealed By MIT Scientists



September 12, 2023 - Scientists at the Massachusetts Institute of Technology (MIT) are trying to find more efficient carbon capture ways. In a study that appeared on September 5th in ACS Catalysis named Uncovering the Active Species in Amine-Mediated CO2 Reduction to CO on Ag, the researchers reveal the hidden until now functioning of how CO2 can be both captured and converted through a single electrochemical process. 

That electrochemical process can trap and release CO2 in liquid amine sorbents and involves using an electrode to attract carbon dioxide released from a sorbent. The process uses less energy than conventional methods but gathers the same amount of CO2 by weight. 

Usually, other methods involve using mostly amine-based sorbents to capture the carbon dioxide and then heat to separate the CO2 and amines, heat derived typically by burning fossil fuels.

The new method runs at ambient temperatures and pressures, which makes it cheaper than the reactors used to heat amines for CO2 release. According to Fang-Yu Kuo, a chemical engineering graduate student at the Massachusetts Institute of Technology, using renewable electricity would “make the carbon capture process more sustainable.” 



Credit: MIT

Similar demonstrations have been reported before, however, the mechanisms driving the electrochemical reaction have remained unclear. The MIT team carried out extensive experiments to determine the driver and found that, in the end, it came down to the partial pressure of carbon dioxide. In other words, the more pure carbon dioxide that makes contact with the electrode, the more efficiently the electrode can capture and convert the molecule.

That also means electrochemical systems would probably not work for very dilute environments like for direct air capture but they are suited to the highly concentrated CO2 emissions generated by industrial processes.

“We can and should switch to renewables for electricity production. But deeply decarbonizing industries like cement or steel production is challenging and will take a longer time… Even if we get rid of all our power plants, we need some solutions to deal with the emissions from other industries in the shorter term, before we can fully decarbonize them. That’s where we see a sweet spot, where something like this carbon capture system could fit,” explains study author Betar Gallant, the Class of 1922 Career Development Associate Professor at MIT. 

Lead authors of the research are postdoc Graham Leverick and graduate student Elizabeth Bernhardt, with participants Aisyah Illyani Ismail, Jun Hui Law, Arif Arifutzzaman, and Mohamed Kheireddine Aroua of Sunway University in Malaysia.