The purification and enrichment of deuterium have significant importance in nuclear fusion reactors, industrial and scientific research. However, its enrichment from isotope gas mixtures is extremely difficult because two isotopes share almost identical size, shape, and thermodynamic properties.

In a study published in Science China Chemistry, a research group led by Prof. YUAN Daqiang from Fujian Institute of Research on the Structure of Matter (FJIRSM) of the Chinese Academy of Sciences reported a physical adsorption method of low energy consumption, simple process and less investment with metal-organic frameworks M-MOF-74 (M=Ni, Co, Mg, Zn) as adsorbents to separate hydrogen isotope.

The researchers verified that breakthrough experiments in metal-organic frameworks M-MOF-74 (M=Ni, Co, Mg, Zn) bed enable the hydrogen isotope separation process via a low-cost and low-energy separation route.

Different from the ideal adsorbed solution theory (IAST) calculation results, among these four materials, Co-MOF-74 showed the best H₂/D₂ penetration performance, not only having the largest hydrogen isotope adsorption capacity, but also having the longest retention time of D₂.

In addition, the researchers revealed that hydrogen isotope concentration of mixed gas and temperature of the test would affect the breakthrough separation performance of materials with a different degree.

The sequence of deuterium breakthrough time is different for different concentrations of hydrogen isotope mixtures, mainly because the H₂/D₂ separation performance of materials is the result of the combination of equilibrium adsorption capacity, density of open metal sites and binding sites strength.

The breakthrough separation technology has a broad development prospect to solve the problem of hydrogen isotope separation and provides a direction for the synthesis of hydrogen isotope separation materials in the future.