Soak up CO₂ with sponges, says CSIRO

A football field in a gram

Australian science outfit the CSIRO is claiming a win, demonstrating a material it says offers a new approach to carbon capture: a sponge.

The idea of the “sponge” – really a material called a metal-organic framework – is very straightforward. It absorbs gases at the point of release, such as capturing flue gases in a power station, and releases captured CO2 on exposure to sunlight. If it can be scaled up, that means the gases can be captured in one place and released in a safe environment (for example, the storage facility) somewhere else.

In its release, the CSIRO explains that the MOF solves one of the challenges of carbon capture. Current technologies such as amine fluids, which capture flue gases quite efficiently, have to be heated to release the gases, a process the science agency says can use as much as 30 percent of a generator’s capacity.

The MOFs eliminate the “parasitic energy load of adsorbent regeneration”, because they release the as much as 64 percent of the captured carbon immediately on exposure to ultraviolet light.

Monash University’s Richelle Lyndon worked in the CSIRO team under Dr Matthew Hill, and is lead author of a paper (abstract) in Angewandte Chemie. She explains that the MOFs “are impregnated with light-responsive azobenzene molecules which react to UV light and trigger the release of CO₂.

“It is this reaction, and the material's ability to bend and flex, which makes the material we have created so unique,” she said.

The other important aspect of the MOFs is their internal structure: they have “the surface area of a football field in one gram”, giving the material a high absorption capacity relative to its weight.

As well as the CSIRO and Monash, the development of the materials used the powder diffraction beamline at the Australian Synchrotron. ®