Kinetic Separation of Hydrogen Isotopes in Metal-Organic Frameworks

Deuterium is a valuable hydrogen isotope with applications in NMR, nuclear power, and as a medical tracer. It constitutes less than 0.02% of naturally occurring hydrogen and is challenging to isolate. Current industrial separation techniques, which rely on tiny differences in the isotopes' chemical behavior, are expensive and energy intensive. Recently a new approach based on difference in the confined isotopes' zero-point energy has emerged. While these "quantum sieving" methods exhibit higher selectivity, many practical obstacles remain for them to replace the standard chemical approach. I will present data on a kinetics based separation within highly porous pellets of metal-organic frameworks (MOF). Mass spectroscopy with isotope mixtures shows breakthrough times that differ by more than three minutes. While these results are obtained at liquid nitrogen temperature, it is expected that planned experiments with the MOF known as Cu-MFU-4l should produce similar time differences at room temperature.