New material rapidly absorbs CO2 from the air: “Breakthrough in the fight against climate change” – Scientias

The Netherlands is five years behind on its climate goals, and we are certainly not alone in this. Greenhouse gas emissions must be reduced. And for this it is essential to capture and store CO2 from the air. Policy makers are also looking at science with concern. He has now developed a new type of material that makes carbon storage much easier and more efficient.

Current carbon capture technologies work particularly well with concentrated carbon sources, such as power plant emissions. These methods are less effective in capturing carbon dioxide from the air, where the concentration is hundreds of times lower. But direct air capture, also known as DAC, is needed to reduce rising CO2 levels. The level of carbon dioxide in the air continues to rise and is currently at 426 parts per million (ppm), an increase of 50 percent compared to pre-industrial levels. According to the IPCC, the UN climate panel, the use of DAC is essential to limit global warming to a maximum of 1.5 degrees.

On to net zero
A new type of absorbent material, developed by scientists at the University of California Berkeley, could help achieve ‘net zero’ or even negative emission values. This stuff, something called ‘covalent organic framework‘ (COF), to extract CO2 from the ambient air without being affected by water or other pollutants, the researchers write in Nature. This is a significant improvement over existing DAC technologies, which are often sensitive to these types of materials.

Omar Yaghi, professor of chemistry at UC Berkeley, enthusiastically talks about the achievements of his new discovery. “We took some of this material, put it in a tube, and let the outside air of Berkeley flow through the material. It completely removed the CO2 from the air, just everything,” he said. “This stuff will represent progress in the fight against climate change.” According to Yaghi, it’s easy to applying new material to existing carbon capture systems, such as the filter systems to capture CO2 from furnace emissions or to capture atmospheric CO2 for underground storage.

Strong game
Lead researcher Zihui Zhou explains that just 200 grams of the material can absorb as much CO2 as a tree – this is equivalent to around 20 kilos of CO2 per year. “Fuel gas capture can reduce climate change because it prevents CO2 from entering the atmosphere. Air trapping simply helps us return to the situation 100 years ago, when CO2 concentrations were much lower,” said the Berkeley scientist.

Yaghi is the inventor of both COFs and MOFs (metal-organic frameworks), both solid, crystalline structures with internal pores. These pores provide a large surface area for gases to adhere to. Some of the MOFs Yaghi developed can absorb water from the air and release it when heated, even under extremely dry conditions. Yaghi has been working on MOFs for carbon capture since the 1990s, when no one had heard of DACs.

A big challenge
“It is very difficult to remove CO2 from the air,” Yaghi makes clear. “You need a material with high capacity, to which CO2 binds and no other materials, which remains stable in water and oxygen rich environments, and which is also easily recycled. It also requires very little energy to produce the material and must be applicable on a large scale. That’s a big challenge.”

Yaghi’s team has spent the last two decades developing COFs strong enough to withstand contaminants such as water, acids and bases. In practice, many other porous materials are severely damaged by this. Their latest COF-999 is built from a skeleton of polyolefins – polymers based only on carbon and hydrogen – to which amino groups are attached. This ensures that each amino group is able to hold a CO2 molecule. When air with a CO2 concentration of 400 ppm is pumped through the COF, the material is saturated within two hours and can hold up to 2 millimoles of CO2 per gram. The CO2 is released by heating the material to exactly 60 degrees, after which it is ready for a new cycle.

Especially stable
The material is particularly stable, both chemically and thermally. It can easily be used more than a hundred times without losing capacity. “This is the best equipment currently available for direct air capture,” Yaghi said proudly. Artificial intelligence (AI) is sure to help develop even better COFs and MOFs for carbon capture and other applications. “We are very excited about the opportunities that AI offers to improve and accelerate our chemical innovations,” says the Berkeley researcher.