Cryogenic Adsorption of Hydrogen Isotopes over Nano-Structured Materials

Porous materials such as zeolites, activated carbon, silica gels, alumina and a number of industrial catalysts are compared and ranked for hydrogen and deuterium adsorption at liquid nitrogen temperature. All samples show higher D₂ adsorption than that of H₂, in which HY zeolite has the greatest isotopic effect while 13X zeolite has the highest hydrogen uptake capacity. Material's moisture content has significant impact to its hydrogen uptake. A material without adequate drying could result in complete loss of its adsorption capacity. Even though some materials present higher H₂ adsorption capacity at full pressure, their adsorption at low vapor pressure may not be as good as others. Adsorption capacity in a dynamic system is much less than in a static system, as expected. The same type of material from different vendors or lots may behave differently.