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-4l 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 approximate to 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.