Genggeng Qi says the technology could be used on a smaller scale—such as in greenhouses, where the captured carbon dioxide can be used to enhance plant growth. (Credit: iStockphoto)

carbon dioxide

New ‘sponges’ capture carbon in a powder

Carbon capture—chemically trapping carbon dioxide before it ends up in the atmosphere—is gaining momentum in the fight against global warming. The standard methods, though, are plagued with toxicity, corrosiveness, and inefficiency.

Now, materials scientists have invented low-toxicity, highly effective carbon-trapping “sponges” that could make the technology more popular.

silica support and amine sorbent
Above left, a scanning electron microscopy image shows a pristine silica support before the amine is added. Above right, the amine sorbent. (Credit: Genggeng Qi)

A research team has invented a powder that performs as well or better than industry benchmarks for carbon capture. A paper with their results appears in Nature Communications.

Used in natural gas and coal-burning plants, the most common carbon capture method today is called amine scrubbing, in which post-combustion, carbon dioxide-containing flue gas passes through liquid vats of amino compounds, or amines, which absorb most of the carbon dioxide.

The carbon-rich gas is then pumped away—sequestered—or reused. The amine solution is extremely corrosive and requires capital-intensive containment.

Dipping the scaffold

The researchers have been working on a better, safer carbon-capture method since about 2008, and they have gone through several versions. Their latest consists of a silica scaffold, the sorbent support, with nanoscale pores for maximum surface area.

They dip the scaffold into liquid amine, which soaks into the support like a sponge and partially hardens. The finished product is a stable, dry white powder that captures carbon dioxide even in the presence of moisture.

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Solid amine sorbents are used in carbon capture, but the supports are usually only physically impregnated with the amines, says team leader Emmanuel Giannelis, a professor of engineering at Cornell University. Over time some of the amine is lost, decreasing effectiveness and increasing cost.

The researchers instead grew their amine onto the sorbent surface, which causes the amine to chemically bond to the sorbents, meaning very little amine loss over time.

Coauthor Genggeng Qi, a postdoctoral associate, says the next steps are to optimize the sorbent and to eventually demonstrate it for industry, possibly at Cornell for retrofitting its power plant. He also says the technology could be used on a smaller scale—such as in greenhouses, where the captured carbon dioxide can be used to enhance plant growth.

King Abdullah University of Science and Technology (KAUST) and Qatar University supported the work. The researchers used the Cornell Center for Materials Research, funded by the National Science Foundation. They performed scaling-up experiments at the prototyping and testing facility of the KAUST-Cornell Center for Energy and Sustainability.

Source: Cornell University

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