Elucidation of Diffusivity of Hydrogen Isotopes in Flexible MOFs by Quasi-Elastic Neutron Scattering
Elucidation of Diffusivity of Hydrogen Isotopes in Flexible MOFs by Quasi-Elastic Neutron Scattering
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DOI：
10.1002/adma.202007412
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发表时间：
2021-04-06
影响因子：
29.4
通讯作者：
Oh, Hyunchul
中科院分区：
文献类型：
--
作者：
Jung, Minji;Park, Jaewoo;Oh, Hyunchul
在柔性多孔材料中，动力学量子筛分辅助的H-2：D-2分离比目前使用的用于同位素分离的能量密集型低温蒸馏和环带状硫化物过程更有效。据信，材料的柔性导致在外部刺激的影响下的孔呼吸现象，这有助于调节孔径，并在气体分离的每个阶段产生最佳的量子筛分现象。然而，只有少数研究已经调查了动力学量子筛分辅助同位素分离使用柔性多孔材料。此外，在动态相变条件下分离过程中同位素分子输运的微观观察尚未见报道。在这里，一个显着更快的扩散氘比氢在一个灵活的孔隙结构，即使在高温下，通过准弹性中子散射的实验观察，报告。与刚性结构不同，提取的氢同位素在柔性框架内的扩散动力学表明，同位素之间的扩散差异随着温度的升高而增加。由于这种独特的反向趋势，提出了一种新的策略，以实现更高的操作温度，有效的同位素分离利用灵活的金属有机框架系统。
Kinetic-quantum-sieving-assisted H-2:D-2 separation in flexible porous materials is more effective than the currently used energy-intensive cryogenic distillation and girdle-sulfide processes for isotope separation. It is believed that material flexibility results in a pore-breathing phenomenon under the influence of external stimuli, which helps in adjusting the pore size and gives rise to the optimum quantum-sieving phenomenon at each stage of gas separation. However, only a few studies have investigated kinetic-quantum-sieving-assisted isotope separation using flexible porous materials. In addition, no reports are available on the microscopic observation of isotopic molecular transportation during the separation process under dynamic transition. Here, the experimental observation of a significantly faster diffusion of deuterium than hydrogen in a flexible pore structure, even at high temperatures, through quasi-elastic neutron scattering, is reported. Unlike rigid structures, the extracted diffusion dynamics of hydrogen isotopes within flexible frameworks show that the diffusion difference between the isotopes increases with an increase in temperature. Owing to this unique inverse trend, a new strategy is suggested for achieving higher operating temperatures for efficient isotope separation utilizing a flexible metal-organic framework system.