(347e) Exploiting Dynamic Opening of Apertures in Partially Fluorinated MOF for Enhancing H2 Desorption Temperature and Isotope Separation

Deuterium has been recognized as an irreplaceable element in industrial and scientific research. However, hydrogen isotope separation still remains a huge challenge due to the identical physicochemical properties of the isotopes. In this paper, a partially fluorinated metal-organic framework (MOF) with copper, so-called FMOFCu, was investigated to determine the separation efficiency and capacity of the framework for deuterium extraction from hydrogen isotope mixture. The unique structure of this porous material consists of a tri-modal pore system with large tubular cavities connected through a smaller cavity with bottleneck apertures with the size of 3.6 Å plus a third hidden cavity connected by an even smaller aperture of 2.5 Å. Depending on temperature these two apertures show a gate opening effect and the cavities get successively accessible for hydrogen with increasing temperature. The thermal desorption spectroscopy (TDS) measurements indicate that the locally flexible MOF can separate D2 from isotope mixture efficiently, with a selectivity of 14 at 25 K and 4 at 77 K.