Multi-component Adsorption Characteristics of Hydrogen Isotopes on Synthetic Zeolite 5A-type at 77.4K

Abstract

The pressure swing adsorption (PSA) method, operating rapid desorption, has become applied to medium-massive air-component separation. In this study, with the aim of applying the PSA method to a hydrogen isotope separation process, the multi-component adsorption characteristics of H2-D2 or H2-HD-D2 on a synthetic zeolite at the liquid nitrogen temperature 77.4 K are investigated by using a volumetric apparatus, where the system effects of thermal transpiration and diffusion are taken into account. The adsorption isotherms for pure H2 and D2 are shown in a wide pressure range between 10-2 and 105Pa. The isotherms are closely approximated by an error functional expression proposed here. The separation factors resulting in adsorption are measured in a wide range of amount adsorbed. The separation factors of D2/H2 are estimated in accordance with the ideal adsorbed solution theory using the adsorption isotherms for H2 and D2. The behavior of the estimated factors agrees with that of the experimental ones. The result suggests that values around 3 are expectable for the factors of D2/H2 at amounts adsorbed roughly between 0.01 and 1 mol/kg.