Hydrogen Isotope Separation within the Metal–Organic Framework Cu(I)-MFU-4l

Hydrogen isotope separation within the metal–organic framework material known as Cu(I)-MFU-4 l is investigated using a combination of breakthrough analysis, equilibrium measurements, and infrared spectroscopy. Results confirm the expected large infrared frequency shift of the adsorbed H 2 vibrational mode and reveal an extremely high binding energy difference between H 2 and D 2 of 2.3 kJ/mol. Both static and dynamic measurements indicate that the material’s selectivity for D 2 over H 2 increases with decreasing temperature, reaching a maximum at ≈100 K, but then decreases for lower temperatures. These results indicate an activation barrier for the replacement of adsorbed H 2 by D 2 and place a limit on the material’s effectiveness for isotope separation at low temperature.