Abstract:
Due to the similar physical and chemical properties of hydrogen isotopes, the separation of high-purity hydrogen isotopes has become one of the major problems in modern separation technology. The realization of high-purity hydrogen isotope separation can provide a large amount of fuel for future thermonuclear fusion reactors, which is expected to completely solve the energy crisis. Deuterium also has important application value in neutron moderator, isotope labeling, nuclear magnetic resonance hydrogen spectrum analysis, and pharmaceuticals. However, the current methods of industrial separation of hydrogen isotopes, such as low-temperature distillation and Girdler-Sulfide process, have the problems of low separation factor and high energy consumption. In recent years, researchers have found that the quantum sieving effect of microporous materials can be used to separate hydrogen isotopes at low temperatures. Among them, the metal-organic framework has the advantages of designable structure, adjustable pore size, diverse functional groups, large specific surface area, and good stability. It has broad application prospects in the separation of hydrogen isotopes by quantum sieving effect. In this paper, the principle of quantum sieving(QS) effect for hydrogen isotope separation in microporous materials is introduced, including kinetic quantum sieving(KQS) effect and chemical affinity quantum sieving(CAQS) effect. The calculation and experimental results of some metal-organic frameworks(MOFs) as microporous materials for hydrogen isotope separation are reviewed. Researchers have experimentally screened many highly selective materials, such as MOF-74 and its modified materials, MFU-4l and its modified materials, ZIF-type MOFs, etc., at a low temperature of 20-50 K. Many metal-organic frameworks(MOFs) materials achieve hydrogen isotope separation through kinetic quantum sieving effect. By introducing active metal sites, some MOFs exhibit excellent selectivity and adsorption capacity above liquid nitrogen temperature, reducing the low temperature limit on the separation of hydrogen isotopes by microporous materials. A small number of metal-organic frameworks(MOFs) can achieve the synergy of the two effects through modification, and it greatly improves the separation ability. With the accumulation of experimental data and the progress of measurement technology, researchers believe that temperature, pressure and pore size are the main factors affecting the dynamic quantum sieving effect of metal-organic frameworks(MOFs) materials. Temperature, the type and density of binding sites have an important influence on the chemical affinity quantum sieving effect. Modified metal-organic frameworks(MOFs) have obtained high selectivity factors, and researchers are also continuing to find materials with better separation effects. Up to now, due to the bottleneck of ultra-low temperature and the limitation of experimental technology of real hydrogen isotope mixture, the related experimental research has just begun. More content on the separation of hydrogen isotopes by quantum sieving effect needs further in-depth and systematic research.