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 D-2-responsive third sorption step was revealed, and consequently, a noticeable difference was observed in the uptakes of D-2 and H-2. This may have resulted from the additional space created for D-2 due to its dense packing, as DFT calculations revealed that cobalt formate possesses 2.26 kJ/mol higher binding strength for D-2 than for H-2. The exploitation of this D-2-responsive third sorption step renders a promising separation performance, with a D-2/H-2 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.