Investigations on Hydrogen Isotope Separation Factor Employing Palladium-Based Solid Metallic Membranes

Abstract

At present, there are several methods for hydrogen isotope separation (in elemental form), the most important being cryogenic distillation, thermal diffusion, and gas chromatography. However, these methods have a series of drawbacks, namely, high complexity, high energy consumption, and associated costs. Taking into account these disadvantages, a promising separation method is the one based on solid metallic membranes because of its advantages like low energy consumption and reduced complexity. This method uses the difference between some of the isotopes’ properties, namely, solubility; diffusivity; and, implicitly, permeability. This work envisages the integration of an isotopic separation module, based on membrane permeation, on the exhaust gas line from the current experimental rigs employed at ICSI, to recover and store the hydrogen isotopes. We obtained a maximum separation factor of 5.66 for the lowest studied concentration of deuterium in the hydrogen isotopic mixture (0.05 atomic fraction). The results show that hydrogen isotope separation is possible using palladium/silver membranes. Still, the throughput of the permeated gas is very low, and a significant number of stages will be necessary to obtain the desired purity (above 99.5%).