MIT chemical engineers have developed a low-heat carbon capture method that could make it cheaper and easier for factories to trap their emissions. The approach uses a common chemical additive to boost efficiency and run on waste heat or sunlight.
A team of MIT chemical engineers has unveiled a simple twist on existing carbon capture technology that could make it far cheaper and easier for factories to trap their climate-warming emissions.
By adding a common lab chemical to standard capture solutions, the researchers found they could absorb much more carbon dioxide at room temperature and then release it using only mild heat. That low-temperature step is key, because it opens the door to running carbon capture systems on waste heat from industrial plants or even solar energy, instead of burning extra fuel.
Today, carbon capture and storage accounts for only a tiny fraction of global emissions reductions. Yet it is widely seen as one of the few tools available to slash pollution from hard-to-decarbonize industries such as cement, steel, fertilizers and petrochemicals.
The new MIT approach aims squarely at the biggest barrier: cost.
Conventional systems typically use chemicals called amines, which grab carbon dioxide from exhaust gases. Once the solution is saturated, it must be heated to more than 120 degrees Celsius (about 248 degrees Fahrenheit) to release a pure stream of carbon dioxide and regenerate the solvent. That high-temperature step is extremely energy intensive and expensive.
The MIT team instead focused on carbonate solutions, which are inexpensive, widely available and also able to capture acidic carbon dioxide. Their challenge was that as carbon dioxide dissolves into these solutions, it quickly lowers the pH, or acidity level, and sharply limits how much more gas can be absorbed.
To get around that, the researchers added a compound known as tris — short for tris(hydroxymethyl)aminomethane — which is already used in lab experiments, some cosmetics and COVID-19 mRNA vaccines. Tris acts as a pH buffer, helping the solution resist changes in acidity.
In the carbonate mixture, positively charged tris balances the negatively charged bicarbonate ions that form when carbon dioxide is absorbed. That stabilizes the pH and allows the solution to take up about three times as much carbon dioxide as carbonate alone.
The same additive also makes it much easier to get the carbon dioxide back out.
Tris is highly sensitive to temperature. When the carbon-loaded solution is heated only to about 60 degrees Celsius (140 degrees Fahrenheit), tris rapidly releases protons, the pH drops and the captured carbon dioxide bubbles out as a concentrated gas stream.
“At room temperature, the solution can absorb more CO2, and with mild heating it can release the CO2. There is an instant pH change when we heat up the solution a little bit,” lead author Youhong (Nancy) Guo, a former MIT postdoctoral researcher who is now an assistant professor of applied physical sciences at the University of North Carolina at Chapel Hill, said in a news release.
That relatively low regeneration temperature is a dramatic improvement over conventional amine-based systems. It means the process could be powered by low-grade heat that many industrial facilities currently waste, or by electricity and solar thermal energy, instead of dedicated fossil fuel burners.
To show that the concept can work in practice, the team built a continuous-flow reactor that mimics how a real industrial system would operate.
In their setup, exhaust gases containing carbon dioxide are first bubbled through a reservoir filled with the carbonate–tris solution, which soaks up the gas. The liquid is then pumped into a regeneration module, where it is warmed to about 60 degrees Celsius. The heat triggers the pH shift and releases a pure stream of carbon dioxide. Afterward, the cooled solution is cycled back to the first tank to capture more gas.
Because the process uses standard types of equipment and simply swaps one solution for another, the researchers say it should be relatively easy to retrofit into existing plants.
“It’s something that could be implemented almost immediately in fairly standard types of equipment,” added senior author T. Alan Hatton, the Ralph Landau Professor of Chemical Engineering Practice at MIT.
Hatton emphasized that the design is meant to be a practical upgrade, not a complete overhaul of how factories handle their emissions.
“One of the nice things about this is its simplicity, in terms of overall design. It’s a drop-in approach that allows you to readily change over from one kind of solution to another,” he said.
Once captured, carbon dioxide can be handled in several ways. A small share can be turned into useful products, such as fuels, building materials or chemicals. But Hatton noted that this route has limits.
“You can only use a small fraction of the captured CO2 for producing chemicals before you saturate the market,” he said.
For that reason, most captured carbon dioxide from large industrial sources is expected to be compressed and injected deep underground into geological formations, where it can be stored long term.
The MIT work does not change that reality, but it could make the first step — separating carbon dioxide from exhaust streams — much more affordable and flexible. Lowering the energy demand also reduces the risk that carbon capture systems will cancel out their own climate benefits by burning extra fuel.
Beyond this initial breakthrough, Guo is now exploring whether other additives could further speed up how quickly the solution absorbs carbon dioxide, potentially shrinking the size of equipment needed for a given factory.
The research, published in the journal Nature Chemical Engineering, was carried out under the MIT–Eni research framework, which supports work on low-carbon energy technologies.
As governments and industries race to meet climate targets, innovations like this one highlight a key theme: sometimes, big gains come not from exotic new machinery, but from smart chemistry that lets existing systems work in a cleaner, leaner way.