Metal Incorporated Mesoporous Silica for Hydrogen Isotope Gas Separation Application in Heavy Water Nuclear Power Plant

The separation of hydrogen isotopologues, such as protium (H₂), deuterium (D₂) and tritium, is necessary for the stable and consistent operation of heavy water nuclear power plants, where deuterium oxide is used as both moderator and coolant. As conventional processes, cryogenic distillation and catalytic exchange are widely applied for hydrogen isotopologues separation. However, those techniques have been encountered the intrinsic limitations including high energy consumption, slow reaction rates and large facility expenses. As an alternative, separation techniques based on the mechanism of chemical affinity quantum sieving have been studied to separate isotopes at temperate ranging from liquid nitrogen (N ₂ ) temperature (77 K) to upwards through differences in adsorption. In this study, mesoporous silica modified with silver or copper (Cu) was prepared and applied for hydrogen isotopologues separation at 77 K. Their structural, morphological and surface chemical properties were analyzed using X-ray diffraction, scanning electron microscopy, N ₂ physisorption, X-ray photoelectron spectroscopy and solid-state magic angle spinning silicon-29 nuclear magnetic resonance spectroscopy. Single gas adsorption isotherms of H ₂ and D ₂ were measured and binary separation performance was evaluated using equilibrium modeling. Cu-incorporated mesoporous silica showed the highest D ₂ over H ₂ selectivity, reaching 5.52 under the D ₂ diluted conditions (1:99). This is attributed to the dispersed Cu oxide species in the silica framework as well as the silanol rich domains of mesoporous silica which both enhance interaction with D ₂ . These results suggest that isotope selectivity (D ₂ /H ₂ ) can be tuned by adjusting the surface structure, property and pore network of mesoporous silica, offering a practical approach for hydrogen isotopologues separation in nuclear facility.