Zhang, L.; Jee, S.; Park, J.; Jung, M.; Wallacher, D.; Franz, A.; Lee, W.; Yoon, M.; Choi, K.; Hirscher, M.; Oh, H.: Exploiting Dynamic Opening of Apertures in a Partially Fluorinated MOF for Enhancing H2 Desorption Temperature and Isotope Separation. Journal of the American Chemical Society 141 (2019), p. 19850-19858
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Deuterium has been recognized as an irreplace-able element in industrial and scientific research. However,hydrogen isotope separation still remains a huge challenge dueto the identical physicochemical properties of the isotopes. Inthis paper, a partiallyfluorinated metal−organic framework(MOF) with copper, a so-called FMOFCu, was investigated todetermine the separation efficiency and capacity of theframework for deuterium extraction from a hydrogen isotopemixture. The unique structure of this porous material consistsof a trimodal pore system with large tubular cavities connectedthrough a smaller cavity with bottleneck apertures with a sizeof 3.6 Å plus a third hidden cavity connected by an evensmaller aperture of 2.5 Å. Depending on the temperature,these two apertures show a gate-opening effect and the cavitiesget successively accessible for hydrogen with increasing temperature. Thermal desorption spectroscopy (TDS) measurementsindicate that the locallyflexible MOF can separate D2from anisotope mixture efficiently, with a selectivity of 14 at 25 K and 4 at 77 K.