To mitigate climate change, direct air capture of carbon dioxide (CO₂) from the atmosphere has emerged as an increasingly attractive option for limiting global warming. But scaling up systems to remove and safely store enough CO₂ faces major obstacles, according to researchers at the Georgia Tech School of Chemical and Biomolecular Engineering (ChBE).

They cite climate models estimating that limiting global warming to less than 2 degrees Celsius could require removing approximately 10 billion metric tons of carbon dioxide from the atmosphere annually by 2050, increasing to 20 billion tons per year by 2100. Current DAC systems remove only thousands of tons of CO₂ annually.

One challenge is improving the solid sorbents that capture CO₂ from ambient air. In collaboration with CarbonCapture Inc., researchers in ChBE have shown that a simple, one-step modification can upgrade a commercial amine resin into a more efficient and durable sorbent for CO₂ capture. They published their findings in Science Advances.

“Achieving economically viable DAC demands major improvements in solid sorbent design and performance,” said study author Professor Christopher W. Jones of ChBE, who noted that the benefits of DAC include its potential scalability, modest land-use requirements, flexibility in plant locations, and access to extensive geological reservoirs for long-term CO₂ storage.

Improving a Commercial Sorbent

Jones and his collaborators found a way to improve the performance of Lewatit VP OC 1065, a commercially available resin already considered a benchmark in the DAC field. The material works for DAC because it’s studded with amine groups, which are chemical sites that grab CO₂ molecules as air passes through the resin.

Rather than design a new sorbent, the researchers built on previous Georgia Tech studies with PPI (poly(propyleneimine)), a polymer that has shown advantages in both CO₂ capture and durability. They developed a simple grafting process that grows PPI directly from amine sites already present on the commercial resin, increasing its ability to capture CO₂.

The process involved soaking the resin in a small, inexpensive molecule called azetidine along with a small amount of acid, and then heating the mixture for two days.

The researchers found the upgraded resin captured about 75 percent more CO₂ than the untreated version under dry conditions that mimic open air, where CO₂ makes up only about 400 parts per million of the surrounding gas.

The material also performed well under simulated industrial flue-gas conditions, where CO₂ is far more concentrated, capturing more than 50 percent more than the untreated resin. 

The team also tested the resin across temperatures ranging from 25 degrees Celsius down to -20 degrees Celsius and across a wide range of humidity levels. In humid air, the modified resin outperformed the original at every temperature tested, though its advantage disappeared in very cold, dry conditions.

Enhancing Durability

Sorbents used in DAC need to survive repeated use, cycling between capturing CO₂ and being heated to release it. Amine-based materials are known to degrade over time when exposed to oxygen. But the branched bPPI chains added by the researchers to the sorbent reduced oxidative degradation by about half.

In tests that simulated 150 rounds of capture and release from industrial exhaust, the modified resin held up significantly better than the original material, the researchers found.

“These commercial resins are already leading candidates for large-scale carbon capture deployment,” said Arkaprabha Giri, a former postdoctoral researcher in Jones’ lab who is the study’s lead author. “If we can meaningfully boost their performance with a process this simple, that’s a real opportunity to speed up deployment without waiting on an entirely new generation of materials.”

Study co-author Omid Ghaffari Nik, Ph.D., vice president of materials science and process at CarbonCapture Inc., said that bringing down the steep cost of DAC is a crucial goal.

“The U.S. Department of Energy has set a target of atmospheric CO₂ capture and storage at less than $100 per net metric ton, emphasizing the need for innovation in sorbent-based DAC systems,” Nik said.

The use of an existing commercial resin and readily available chemicals could offer advantages in eventually scaling up the process, the researchers said. They successfully applied the same method to a second commercial resin, Purolite A110, suggesting the approach isn't limited to one product.

The team has filed a provisional patent and is now working to extend the technique to other amine-based materials, with the aim of scaling the process from lab quantities to the industrial scale.

CITATION: Arkaprabha Giri, UnJin Ryu, Jiaqi Zhang, Opeyemi Ojelade, Wenyang Zhao, Jacob Hoffman, Mark Robertson, Jordi Espín, Madison Nichols, Surya Parker, Omid Ghaffari Nik, and Christopher W. Jones, "In situ azetidine polymerization elevates the performance of commercial polymer resin sorbents in carbon dioxide capture," Science Advances, 2026

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