'Crystalline sponge' can help capture CO2

Henry Fountain

To sequester carbon dioxide as part of any climate-change mitigation strategy, the gas first has to be captured from the flue at a power plant or  other source. The next step is just as important: the CO² has to be released from whatever captured it so that it can be pumped underground or otherwise stored for the long term.

That second step can be costly from an energy standpoint. Materials currently used to capture CO² have to be heated to release the gas.

But chemists at University of California, Los Angeles, say that a new class of materials they developed called metal-organic frameworks, or MOFs, hold promise for carbon capture. In the study, Omar Yaghi describes the performance of one MOF, which he says can free most of the CO² it captures at room temperature.

Yaghi described a metal-organic framework as a "crystalline sponge", a hybrid lattice of organic compounds and metal atoms that has a huge internal surface area where gas molecules can be absorbed. The MOF used in the study contains magnesium atoms, "which make just the right environment for binding carbon dioxide", he said.

In experiments, the material separated out CO² while allowing methane to pass. What was really surprising, though, was that at room temperature 87% of the CO² could be released.