Applicability of Pd–Cu alloy to self-developing gas chromatography of hydrogen isotopes

To develop a new material for hydrogen isotope separation, absorption and desorption isotherms of protium (H11) and deuterium (H12) were measured for five kinds of Pd–Cu alloys in the temperature range from 283 to 453 K. Thermodynamic parameters for the formation and decomposition of hydride and deuteride of the alloys, ΔH0 and ΔS0, were evaluated from the temperature dependence of equilibrium pressure in a plateau region of the isotherms for each Pd–Cu alloy. The thermodynamic parameters for Pd–15at.%Cu alloy were almost equivalent to those of the Pd–8at.%Pt alloy which showed good separation performance. Separation tests of the 50%H2–50%D2 mixture were carried out under various conditions by using Pd–15at.%Cu alloy, and significantly high separation efficiency was observed. It was suggested, therefore, that the Pd–Cu alloys are applicable to the separation of hydrogen isotopes near room temperature.