Trapping carbon dioxide

A team of researchers synthesized a solid material that can specifically bind and remove carbon dioxide (CO₂) from gaseous mixtures, which is highly stable, and easy to regenerate.

CO₂ selection has important applications in reducing greenhouse gas emissions, as well as purifying natural gas (methane) from contaminating CO₂. Historically, aqueous solutions of amines were used for this purpose in a process known as “scrubbing”. Being highly uneconomic, however, its unsuitability for industrial application caused its popularity to plummet.

Instead, research focused on identifying and designing solid porous materials with the capacity to selectively adsorb CO₂ on their surfaces.

Several such materials were found promising, but the problem of regenerating them when fouled by contaminants endured.

Now, a team of researchers devised a clever trick to circumvent the fouling problem. They designed a porous polymer whose pores can selectively bind CO₂ and that is also soluble in the organic solvent DMSO, but not in most other aqueous or organic solvents.

This makes the polymer easy to prepare and allows for both dissolving and reproducing it when it fouls to get rid of contaminants adsorbed on its surface.

Their polymer comprised rigid ladder chains of hydrocarbons forming a porous backbone, supporting rings similar to the bases found in DNA, which can form hydrogen bonds to CO₂ to capture it on the polymer.

The team of researchers, from the King Abdullah University of Science and Technology in Saudi Arabia, published their design in Advanced Materials. They went on to demonstrate, that, not only can their polymer demonstrate high selectivity for CO₂ in CO₂/N₂ and CO₂/CH₄ mixtures, but it is also highly stable in various environments and at higher temperatures.

Zhiping Lai, who lead the research team, believes that such materials as their organic polymer is the way forward, “Adsorbents has been a territory of inorganic materials for a long time. It is now the time to think about organic and hybrid materials.”

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