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

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.