Comparison of chromatographic methods for hydrogen isotope separation by Pd beds

Comparison among three chromatographic separation methods, i.e. hydrogen-displacement chromatography, self-displacement chromatography and frontal chromatography, is made in an experimental way using several gas mixtures of hydrogen and deuterium. There is small difference in the height equivalent to a theoretical plate (HETP) based on the plate theory among the three chromatographic techniques. The HETP value for the self-displacement chromatography is 3.9 cm, and that for the frontal or H2-displacement chromatography is 3.0 cm at the same flow-rate. The self-displacement chromatography is more useful for the separation of a small amount of deuterium or tritium from other hydrogen isotopes under a moderate recovery ratio. Since the frontal chromatography uses no other gas than the sample, it is more convenient for the separation of deuterium from natural hydrogen even though a lower recovery ratio.