Multi-Component Behavior of Hydrogen Isotopes in Zeolite Packed-Beds Used for Cryogenic Pressure Swing Adsorption

Authors have been studying the adsorption or/and desorption behavior of H(2) or/and D(2) with synthetic zeolite packed-beds under the cryogenic condition of liquid nitrogen temperature, aiming at developing a pressure swing adsorption (PSA) process of hydrogen isotope separation useful for tritium processing in fusion fuel cycle and environmental tritium safety confinement, or convenient for deuterium production. We examined the mass transfer in the adsorption system of D(2) diluted in H(2) with zeolite packed-beds, experimentally and analytically. The results have been presented, where it is shown that the enrichment factor of D(2) in packed-beds matches with estimated from the isothermal adsorption characteristics and that the mass transfer is controlled in the macro-pore media of adsorbents. In this work, the behavior of tracer HD added in a H(2)-D(2) mixture with zeolite 5A and 13X packed-beds was experimentally investigated, and was analyzed by the curve-fitting as well as for the behavior of D(2). In this report, the experimental results demonstrate that the breakthrough curves of HD exhibit analogous to those of D(2) but reduced in the breakthrough time in comparison to the latter. The analytical results verify that the HD/H(2) separation factor in packed-beds agrees with predicted from the isothermal adsorption characteristics, and show that the isotope effect on the mass transfer depends on the molecular mass effect.