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May 2012

Enhanced CO2 Capture in Metal-Organic Frameworks

CO2 binding in BTT-type metal−organic framework: the highly porous MOF structure and, inset, detail of the CO2 binding site illustrating the affinity with organic linker molecule.

Led by the Molecular Foundry's Jeff Neaton, and in collaboration with Berend Smit in an Energy Frontier Research Center at UC-Berkeley, a team of researchers has identified a new mechanism by which CO2 binds to a nanoporous material with exceptional strength. Discovering this novel CO2 binding mechanism may help researchers design materials to capture and store anthropogenic carbon emissions.

Metal-organic frameworks (MOFs) are highly porous materials made of metal atoms linked by a network of organic molecules. Metal atoms in MOFs can selectively bind CO2 over other species common in exhaust gas, such as nitrogen, making MOFs desirable for carbon capture. The organic linker molecules, on the other hand, have been largely considered spectators in this process. In a user project at the Molecular Foundry, the researchers used ab initio calculations to discover that the affinity of certain MOFs for CO2 can be greatly enhanced via a new adsorption mechanism involving both the metal atoms and the organic molecules.

With the right linking molecules, CO2 binding increased by 50%. This discovery can lead to new routes to design MOFs with strong CO2 absorption by manipulating both the metal and the organic framework.

"Ligand-Assisted Enhancement of CO2 Capture in Metal−Organic Frameworks," R. Poloni, B. Smit and J. B. Neaton, J. Am. Chem. Soc 134, 6714 (2012).
This work was supported by the Center for Gas Separations Relevant to Clean Energy Technologies, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE- SC0001015. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231. Computational resources were provided by DOE (NERSC, LBNL Lawrencium).