A sponge for carbon

Scientists in the UK pioneer a porous material that can't get enough CO2.

Scientists in the UK have developed a metallic sponge with a vast internal surface area which can absorb and retain carbon dioxide, according to a report published in Nature Materials. The development comes out of a collaborative research project into gas storage solutions, by the Universities of Nottingham and Newcastle. The team hopes it will play a key role in reducing global emissions through carbon capture. 

The ‘sponge’, named NOTT-202a, belongs to a class of materials called metal-organic frameworks [MOFs]. These are lattices of organic compounds and metal atoms, giving an internal surface area so vast that a single gram could cover half a football field.

MOFs were first developed 15 years ago, and since then government agencies have funded research into their potential to reduce the emissions of power plants and store natural gas in vehicles. “The potential scope of the research is enormous”, says carbon capture specialist Hongcai (‘Joe’) Zhou of Texas A&M University.

To date, MOFs have been limited by their lack of selectivity: their inability to discriminate between the various gases they might absorb. This is what makes NOTT-202a stand out: it is the first that preferentially captures CO2, while releasing other gases. How? The secret’s in the structure: two different frameworks slot together incompletely, leaving tiny gaps that are precisely suited to gathering its particular molecules.

This selectivity has the potential to reduce the high costs of carbon capture. “When regulators decide it’s no longer acceptable to release unlimited CO2, this may provide a low-cost, low-energy way to gather it”, says chemist Jeffrey Long of the University of California-Berkeley.

But, it may be a few years before MOFs line industrial flues. “That’s the ultimate goal”, says Long. “But right now scientists are making these materials in grams. We need to test how they work in tonnes.” – Katherine Rowland

Photo: hemera/thinkstock