Du Xin-Ming, Xiao Song-Tao, Wang Xin, Sun Xi, Lin Yu-Fei, Wang Qiang, Chen Guang-Hui
Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Shantou 515063, Guangdong, China.
Institute of Radiochemistry, China Institute of Atomic Energy (CIAE), Beijing 102413, PR China.
J Phys Chem B. 2023 Sep 28;127(38):8116-8130. doi: 10.1021/acs.jpcb.3c03139. Epub 2023 Sep 19.
Recycling Kr and Xe from used nuclear fuel (UNF) is conducive to regenerating economy and protecting the environment, and it is urgent to screen or design high-performance cutting-edge metal-organic framework (MOF) materials for Kr/Xe adsorption separation. After grand canonical Monte Carlo (GCMC) simulations of Kr/Xe adsorption separation on 11,000 frameworks in CoRE MOFs (2019), the important structure-adsorption property relationship (SAPR) was induced; that is, the porosity (φ) at 0.30-0.40, LCD/PLD at 1.00-1.49, density (ρ) range between 1.20 and 2.30 g/cm, and PLD at 2.40-3.38 Å can be utilized to screen for high-performance G-MOFs and hMOFs. In addition, the key "genes" (metal nodes and linkers) of MOFs determining the Kr/Xe adsorption separation were data-mined by a machine learning technique, which were assembled into novel MOFs. After comprehensive consideration of thermal stability and the adsorbent performance score (APS), eight promising MOFs on Kr/Xe separation with the APS more than 1290.89 were screened out and assembled, which are better than most of the reported frameworks. Note that the adsorption isotherms of these MOFs on Kr and Xe belong to type I curve with the thermodynamic equilibrium mechanism on Kr/Xe based on the confinement effect. Furthermore, according to the electronic structure calculations of the independent gradient model based on Hirshfeld partition (IGMH) and energy decomposition analysis, it is found that the interactions between guests and frameworks are vdW forces with dominant induction energy (Eind). In addition, the electrostatic potential gradients of frameworks are generally linearly negative correlated with Kr uptakes. Therefore, both the geometrical and electronic structures dominate the adsorption separation performance on Kr/Xe. Interestingly, these eight MOFs are also suitable for the separation of CH/H with considerable selectivities and CH uptakes of up to 2566.67 and 3.04 mmol/g, respectively. Herein, the accurately constructed SAPR and material genomics strategy should be helpful for the experimental discovery of novel MOFs on Kr/Xe separation experimentally.
从乏核燃料（UNF）中回收氪（Kr）和氙（Xe）有利于经济再生和环境保护，因此迫切需要筛选或设计用于Kr/Xe吸附分离的高性能前沿金属有机框架（MOF）材料。在对CORE MOFs（2019）中11000种框架进行Kr/Xe吸附分离的巨正则蒙特卡罗（GCMC）模拟后，归纳出了重要的结构-吸附性能关系（SAPR）；即，孔隙率（φ）在0.30 - 0.40、液晶/层间距（LCD/PLD）在1.00 - 1.49、密度（ρ）在1.20至2.30 g/cm之间以及层间距（PLD）在2.40 - 3.38 Å时，可用于筛选高性能的气体吸附MOF（G-MOF）和高孔隙率MOF（hMOF）。此外，通过机器学习技术挖掘了决定Kr/Xe吸附分离的MOF的关键“基因”（金属节点和连接体），并将其组装成新型MOF。综合考虑热稳定性和吸附剂性能评分（APS）后，筛选出并组装了8种APS大于1290.89的有望用于Kr/Xe分离的MOF，它们比大多数已报道的框架表现更好。需要注意的是，这些MOF对Kr和Xe的吸附等温线属于I型曲线，基于限域效应，在Kr/Xe上具有热力学平衡机制。此外，根据基于Hirshfeld划分的独立梯度模型（IGMH）的电子结构计算和能量分解分析，发现客体与框架之间的相互作用是具有主导诱导能（Eind）的范德华力。此外，框架的静电势梯度通常与Kr吸收量呈线性负相关。因此，几何结构和电子结构都对Kr/Xe的吸附分离性能起主导作用。有趣的是，这8种MOF也适用于CH₄/H₂的分离，选择性相当，CH₄吸收量分别高达2566.67和3.04 mmol/g。在此，准确构建的SAPR和材料基因组学策略应有助于通过实验发现用于Kr/Xe分离的新型MOF。
