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Straw Into Gold: New Way to Retrieve CO2 From Air and Recycle It Into Useful Products

December 16, 2015
by Maris Harmon

Turning an undesirable substance into something valuable seems like the plot of an old fable, but UC Berkeley researchers Chris Chang and Omar Yaghi may have done just that. Their invention, covalent organic frameworks, or COFs, can transform atmospheric carbon dioxide into a useful building block for biodegradable plastics, fuel, and more.

Chang likens COFs to TinkerToys, though at a nano scale. They consist of strings of carbon crystals that are special in their unique porosity, as they can be custom tailored to capture the chemical of choice.

Chang and Yaghi recently added cobalt to the COF formation, which enables the “tinkertoys” to extract an oxygen from CO2 using just electricity and water. The resulting product, carbon monoxide, is toxic in large quantities in the atmosphere but can be used to make many common materials, such as biodegradable plastics, pharmaceuticals, and synthetic fuels.

Although there are already carbon-absorbing entities out there, COFs are breaking ground in two important ways: First, instead of carbon sequestration, which buries captured carbon back into the earth, COFs transform the gas. Second, COFs use water to filtrate through the COF and extract carbon monoxide, rather than the toxic solvents required by other processes. To make the technology even greener, the required electricity can be sustainably generated.

The chemical process designed by Yaghi and Chang, which they have dubbed “reticular chemistry,” opens a realm of possibilities for chemical conversions. Although now they are experimenting with just CO2, Yaghi explains they have a “library of organic and inorganic units that can be stitched together” using the frameworks. Chang describes a “miniature factory where you turn one product into another product,” which implies the potential of turning many harmful chemicals into more desirable substances.

As for solving the world’s carbon conundrum, Yaghi spoke of his team’s work with BASF, a company based in Germany. The company has demonstrated that these materials can be scaled up economically. Yaghi says one such large-scale use could be in factories to control the emission of CO2 . The technology could then be used to transform the CO2 into carbon monoxide for fuels and other carbon-based products.

But Chang’s vision for the “tinkertoys” is more localized: He wants in-home COF devices to help people decrease their carbon footprint. The devices “would allow you to take CO2 and turn it into useful household products,” Chang explains, for instance natural gas or biodegradable plastic. Similarly, he says, small and portable COFs would be useful in developing countries where fuel sources and carbon absorption are wanting.

Chang maintains COFs alone will not be the solution, but they’ll “keep us from accelerating fossil fuel use.”

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