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Researchers have unveiled a groundbreaking porous material that effectively separates deuterium (D2) from hydrogen (H2) at a temperature of 120 K. This temperature is significant as it is above the liquefaction threshold for natural gas, opening doors for potential large-scale industrial uses. The innovation provides a promising avenue for economically producing D2 by utilizing the infrastructure associated with liquefied natural gas (LNG) production. The study, authored by a collaborative team from Ulsan National Institute of Science & Technology (UNIST), Korea, Helmholtz-Zentrum Berlin, Heinz Maier Leibnitz Zentrum (MLZ), and Soongsil University, has been published in Nature Communications.
Deuterium, a stable hydrogen isotope, is vital for enhancing the performance of semiconductors and display technology, in addition to its role as a fusion fuel in energy generation. Nonetheless, as the demand for D2 rises, its production poses several challenges, primarily due to the complexities involved in separating it from hydrogen, which typically requires cryogenic distillation at temperatures as low as 20 K (-253°C). Previous research into metal-organic frameworks (MOFs) for D2 separation faced limitations due to diminished efficiency at higher temperatures.
The current study introduces a copper-based zeolite imidazolate framework (Cu-ZIF-gis) that demonstrates remarkable performance in separating D2, even at 120 K (-153°C). While traditional MOFs generally function well around 23 K (-250°C), their effectiveness notably decreases as temperatures approach 77 K (-196°C). In contrast, the newly developed Cu-based MOF maintains its separation capabilities at elevated temperatures, representing a significant improvement in the field.
This research identifies for the first time that the exceptional performance of the material stems from the expansion of its lattice as temperature increases. At cryogenic temperatures, the framework’s pores are too small for H2 molecules to pass through. However, with rising temperatures, the lattice expands, increasing pore size and allowing gases to flow more freely. This phenomenon enables the separation of H2 and D2 due to the quantum sieving effect, where heavier molecules navigate through the pores more effectively at lower temperatures.
Confirmatory experiments, including in-situ X-ray diffraction (XRD) and quasi-elastic neutron scattering (QENS), were conducted at the Institut Laue-Langevin (ILL) in Grenoble, France. These experiments validated the expansion of the lattice and detailed the varying diffusivity of isotopes, even at higher temperatures. The Thermal Desorption Spectroscopy (TDS) analysis also substantiated the stable D2 separation achieved at these elevated temperatures.
Professor Oh noted that the newly developed material demonstrates considerably less energy consumption and improved separation efficiency compared to conventional methods operating at extreme low temperatures. Dr. Jitae Park emphasized the practical implications of these findings for creating sustainable isotope separation technologies that leverage existing cryogenic LNG infrastructures, highlighting its potential for significant industrial advancement.
Dr. Margarita Russina underscored the importance of QENS in the research process, stating: “Through QENS, we can observe the molecular movements of H2 and D2 within MOFs, which provides crucial insights into their diffusion behaviors and interactions with the porous materials. The stronger confinement of D2 compared to H2, a phenomenon occurring on a nanoscale, leads to notable effects on macroscopic properties, forming the groundwork for next-generation materials that enhance isotope separation efficiencies.”
The research team, led by Professor Hyunchul Oh from the UNIST Chemistry Department, Professor Jaheon Kim from Soongsil University, Dr. Jitae Park from MLZ at Technical University of Munich (TUM), and Dr. Margarita Russina from HZB in Berlin, announced these significant findings on March 19, 2025. Collaborators Minji Jung, Jaewoo Park, and Raeesh Muhammad from UNIST also contributed as co-first authors. The findings were officially published in Nature Communications on February 27, 2025. This study received funding from the National Research Foundation (NRF) of Korea and the Ministry of Science and ICT (MSIT), with beam time allocations from Institut Laue-Langevin (ILL) in Grenoble.
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