In a report published recently in the journal Cell Reports Physical Science, researchers from MIT describe an elaborate new approach to enhance the efficiency of carbon capture systems. Current technologies of many carbon capture systems are limited by their high costs and inefficient rates of conversion. The new method, in turn, depends on catalytic surfaces that use electrochemical reactions to uptake atmospheric carbon and improve overall efficiency.
"Carbon dioxide sequestration is the challenge of our times," says MIT professor of mechanical engineering Kripa Varanasi. "The goal of our work was to understand what's the big bottleneck in this process, and to improve or mitigate that bottleneck," he says.
Varanasi collaborated with MIT postdoc Sami Khan, Ph.D., Professor Yang Shao-Horn, and Jonathan Hwang, Ph.D. in detecting that bottleneck. The team found that the limitation occurs during the delivery of the carbon dioxide to the catalytic surface that is meant to stimulate the desired chemical transformations.
They describe the two ways in which the catalytic system is inhibited: first, when the reaction occurs too quickly, depleting the supply of carbon dioxide reaching the catalyst faster than it can be replenished. And second, a consequence of this first event, the triggering of a reaction that splits water into hydrogen and oxygen and uses up the energy in the system.
Prior attempts to fix these problems were previously unsuccessful so the researchers decided to try introducing a gas-attracting surface to the catalyst material that would repel water while simultaneously allowing a layer of gas (known as a plastron) to form on its surface. The plastron works to optimize the carbon dioxide conversion reactions.
Indeed, the researchers showed that with the addition of the plastron, the carbon conversion reaction was almost two-fold and it was sustainable. Another perk of the system is that it generates high rates of ethylene, propanol, and ethanol, which can be used as fuels. The system also produces two new carbon compounds, acetone and acetate, that could potentially be used for other purposes.
Varanasi explains that their system is more efficient because they considered the limitations from a different angle. Speaking of other catalytic systems, Varanasi says, "We significantly outperform them all, because even though it's the same catalyst, it's how we are delivering the carbon dioxide that changes the game."