Thermodynamic Separation of Hydrogen Isotopes Using Hofmann-Type Metal-Organic Frameworks with High-Density Open
Junsu Ha1, Minji Jung1, Jaewoo Park1
1Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
Abstract:
Hydrogen isotope separation with nanoporous materials is a very challenging yet promising approach. To overcome the limitation of the conventional isotope separation strategy, quantum sieving-based separation using nanoporous materials has been investigated recently. In this study, to see the thermodynamic deuterium separation phenomena attributed to the chemical affinity quantum sieving effect, we examine Hofmann-type metal-organic frameworks (MOFs), Co(pyz)[M(CN)4] (pyz = pyrazine, M = Pd2+, Pt2+, and Ni2+), which have microporosity (4.0 × 3.9 Å2) and an extraordinarily high density of open metal sites (∼9 mmol/cm3). Owing to the preferential adsorption of D2 over H2 at strongly binding open metal sites, the Hofmann-type MOF, Co(pyz)[Pd(CN)4] exhibited a high selectivity (SD) of 21.7 as well as a large D2 uptake of 10 mmol/g at 25 K. This is the first study of Hofmann-type MOFs to report high selectivity and capacity, both of which are important parameters for the practical application of porous materials toward isotope separation.
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