Exploiting the Specific Isotope-Selective Adsorption of Metal–Organic Framework for Hydrogen Isotope Separation

Abstract

Adsorptive separation using narrow-micropore adsorbents has demonstrated the potential to separate hydrogen isotopes. In this work, we employed an isotope-responsive separation using cobalt formate. A D2-responsive third sorption step was revealed, and consequently, a noticeable difference was observed in the uptakes of D2 and H2. This may have resulted from the additional space created for D2 due to its dense packing, as DFT calculations revealed that cobalt formate possesses 2.26 kJ/mol higher binding strength for D2 than for H2. The exploitation of this D2-responsive third sorption step renders a promising separation performance, with a D2/H2 selectivity of up to 44 at 25 K/1 bar. Lastly, cobalt formate was synthesized on a gram scale here, which makes it a prospect for commercialization.

Hydrogen Isotope Separation Using a Metal–Organic Cage Built from Macrocycles

“…With increasing exposure temperature, gases can penetrate deeper into the crystals, and the desorption peaks in TDS spectra shift to higher temperatures. The gas molecules can finally penetrate the MOC crystals at T exp =100 K. These temperature‐dependent TDS spectra agree with the observation from pure gas isotherms, which is related to the temperature‐dependent gate‐opening behaviour [11b] . In contrast, 2β shows different desorption spectra under identical conditions, as shown in Figure 5b.…”

A Microporous MOF Constructed by Cross-Linking Helical Chains for Efficient Purification of Natural Gas and Ethylene

“…Emerging as relatively new kinds of porous materials, metal–organic frameworks (MOFs coined by Yaghi, also known as porous coordination polymers (PCPs) by Kitagawa and porous coordination networks (PCNs) by Zhou) consisting of inorganic nodes bridged by organic connectors exhibit a promising potential for mixture separation and purification that stems from their desirable physical and chemical properties such as high surface area, rich structural and compositional diversity, and an unprecedented adjustable capacity in terms of pore size and surface chemistry. To date, a number of MOFs have been developed to address diversified challenges pertaining to industrially important mixture separations such as olefin/paraffin − and alkyne/alkene − containing the same carbon numbers, C 2 H 2 /CO 2 , − D 2 /H 2 , Xe/Kr, and xylene and hexane isomer separations. In the context of NG purification, Chen et al employed framework interpenetration to construct the MOF UTSA-36 with a pore size of 3.1–4.8 Å, which is comparable to the kinetic diameters of C 1–2 hydrocarbons (3.3–4.4 Å) .…”

High Efficiency of Na- and Ca-Exchanged Chabazites in D2/H2 Separation by Quantum Sieving

“…These parameters make Na-CHA the most efficient material for D 2 /H 2 separation at this temperature reported so far. Thus, the value of 26 was also reported for selectivity in the Co formate MOF material, but it was obtained at 25 K and at 7 mmol/g loading . The selectivity of 24 was found for HKUST-1 MOF at 20 K (loading18.2 mmol/g) .…”

“…Thus, recently, a number of metal–organic framework (MOF) phases have been shown to be efficient in D 2 –H 2 quantum sieving through different approaches. High selectivity has been achieved by using the open metal sites, − by tuning the pore geometry, − or through exploiting the flexibility of the MOF structure. − …”