Temperature-Programmed Desorption for Isotope Separation in Nanoporous Materials

Hydrogen isotope separation based on differences in quantum zero-point energy was investigated using a novel temperature-programmed desorption approach. Spectra obtained as a function of hydrogen concentration reveal multiple distinct binding sites that correlate with the crystallographic structure of the particular material. In each case, the higher mass isotope desorbs at a characteristic temperature higher than that of the lower mass counterpart. Materials with greater binding energy exhibit a larger difference in characteristic temperature between D-2 and H-2 but also a broader desorption profile. Simulations based on the standard Polanyi-Wigner equation reveal this broadening to be an intrinsic property present in all higher binding energy materials. As such, the key factor in temperature desorption separation is not the absolute difference in binding energy of the two species but rather the fractional difference.