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Low-Energy CO2 Capture through Cooperative Adsorption

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Top: CO2 is adsorbed via insertion into metal-amine bonds, as revealed by powder x-ray diffraction. 1D chains of ammonium carbamate are formed as the cooperative process propagates along the pore surfaces. Bottom: CO2 adsorption isotherms at 25, 40, 50, and 75 °C for Mg2 and CO2 show how the position of the step can be controlled by varying metal-amine bond strength.

Scientific Achievement
Revealed an unprecedented cooperative mechanism for CO2 capture via its insertion into metal–amine bonds of metal-organic frameworks (MOFs).

Significance and Impact
Understanding the mechanism enables us to design new MOF adsorbents that can significantly reduce the energy required for CO2 capture from a power plant flue gas.

Research Details

  • Step-shaped adsorption isotherms were observed upon appending diamine molecule to sponge-like solid MOFs
  • Through spectroscopic, diffraction, and computational methods, the isotherm step’s origin was shown to be insertion of CO2
  • Insertion of CO2 at one site facilitates insertion at a neighboring site, leading to formation of ammonium carbamate chains
  • The pressure at which the adsorption step occurs can be systematically tuned to minimize the energy used in CO2 separations

McDonald, Mason, Kong, Bloch, Gygi, Dani, Crocellà, Giordano, Odoh, Drisdell, Vlaisavljevich, Dzubak, Poloni, Schnell, Planas, Kyuho, Pascal, Prendergast, Neaton, Smit, Kortright, Gagliardi, Bordiga, Reimer, Long, Nature 2015, doi:10.1038/nature14327