Vacuum pressure swing adsorption-based Ar separation from air on a single adsorbent

Abstract

Due to their inert nature, radioactive noble gases are key for verifying the nuclear character of underground explosions. 37Ar sampling and detection is considered as an important technique for on-site inspections (OSI) for CTBT verification. Compared to radioxenon, 37Ar has a longer half-life and remains detectable for a longer time. For the detection of 37Ar, high purity Ar needs to be recovered from subsoil or atmospheric air. Less energy intensive alternatives, than current systems using at least a cryocooled adsorbent, for recovering Ar from air are sought for. In this context, research on Ar separation in adsorbents operating near room temperature for OSI is led by CTBTO. SCK CEN was contracted to verify the potential of a silver-exchanged molecular sieve (Ag ETS 10) for separating Ar from air by Vacuum Pressure Swing Adsorption (VPSA) at room temperature. In this project, we confirmed for instance its preferential adsorption of Ar over O2, with a 1.4 selectivity, through air-breakthrough measurements. Ar purity against yield was determined from separations in VPSA mode. Additional research was performed outside the project to investigate Ar separation in a larger set of conditions. These results will be discussed in the framework of Ar separation for CTBT verification.