Dynamic Quantum Sieving of a Hydrogen Isotope Mixture: Beyond the Limitations of Small Pore Sizes

Hydrogen isotope separation using porous materials under cryogenic conditions has primarily focused on the optimization of pore sizes for kinetic quantum sieving, with smaller pores (3.0–3.4 Å) generally being regarded as optimal for high selectivity under equilibrium conditions. However, when dynamic flow conditions are considered, such as those encountered in industrial applications, the interaction time between the isotopes and the adsorbent material is significantly reduced, limiting the effectiveness of small pores. This study investigates the performance of zeolite molecular sieves with pore sizes of 3.0, 4.0, and 5.0 Å under both equilibrium and dynamic flow conditions. While smaller pores excel in equilibrium-based calculations, experimental results from breakthrough analysis at cryogenic temperatures (77 and 115 K) demonstrate that larger pore sizes (4.0–5.0 Å) offer better separation efficiency under dynamic flow, suggesting a reevaluation of the optimal pore size for industrial hydrogen isotope separation.