Molecular Separation

Engineering alkene affinity

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Science  06 Sep 2019:
Vol. 365, Issue 6457, pp. 996-997
DOI: 10.1126/science.365.6457.996-d

Metal-organic frameworks (MOFs) that have open sites on metals have potential applications for separating alkanes and alkenes through preferential adsorption. On the basis of density functional theory calculations, Mohamed et al. substituted Zn2+ with Cu+ to modify the MOF MFU-4l, in which Zn5Cl4(ta)6 nodes (where ta is triazolate) bridge long fused aromatic ring linkers. These open sites had greater alkene binding affinity and had minimal interactions with each other, so the binding energy was maintained even as more Cu+ sites were introduced. These materials maintained very high separation ratios for ethylene from ethane and propylene from propane separations in which the alkenes were retained from mixtures at room temperature and then released through thermal cycling.

J. Am. Chem. Soc. 141, 13003 (2019).

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