Jia Zhimin, Yan Zhaotong, Zhang Jie, Zou Yingdi, Qi Yue, Li Xiaofeng, Li Yang, Guo Xinghua, Yang Chuting, Ma Lijian
College of Chemistry, Key Laboratory of Radiation Physics & Technology, Ministry of Education, Sichuan University, No. 29 Wangjiang Road, Chengdu 610064, P.R. China.
Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, P.R. China.
ACS Appl Mater Interfaces. 2021 Jan 13;13(1):1127-1134. doi: 10.1021/acsami.0c14610. Epub 2020 Dec 28.
Among various fission products generated in nuclear reactors, xenon and krypton are two important fission gases with high flow, diffusivity, and radioactivity. Moreover, xenon isolated from these products is an expensive industrial resource with wide applications in medicine and lighting, which makes the development of efficient methods for separation of xenon/krypton significant. However, it is usually difficult for xenon/krypton to be adsorbed by chemical adsorbents due to their inert gas properties, and sub-nanoporous adsorbents proven to be workable for the separation of xenon/krypton are still hard to prepare and regulate the pore size. Herein, we report two novel sub-nanoporous covalent organic frameworks (COFs), which were applied to the sieving of xenon/krypton for the first time. The sub-nanoporous COFs were synthesized aldehyde-amine polycondensation reactions and the subsequent pore size regulation and homogenization process by using a facile, operational, and efficient multiple-site alkylation strategy. Impressively, the as-prepared sub-nanoporous COFs realized the efficient adsorption and sieving of xenon/krypton owing to their slightly larger pore sizes (∼7 Å) than the dynamic diameters of xenon/krypton and their larger pore volumes. The maximum adsorption capacity for xenon is up to 85.6 cm/g, and the xenon/krypton selectivity can reach to 9.7. Moreover, the as-prepared COFs possess good γ-ray irradiation stability, which endows them with great potentials for the sieving of radioactive xenon/krypton in the practical application. The multiple-site alkylation strategy proposed in this study provides a valuable approach for the pore construction and control of the porous materials, especially the sub-nanoporous adsorption materials.
在核反应堆产生的各种裂变产物中，氙和氪是两种重要的裂变气体，具有高流动性、扩散性和放射性。此外，从这些产物中分离出的氙是一种昂贵的工业资源，在医学和照明领域有广泛应用，这使得开发高效的氙/氪分离方法具有重要意义。然而，由于氙/氪的惰性气体性质，它们通常很难被化学吸附剂吸附，而且已被证明可用于氙/氪分离的亚纳米孔吸附剂仍然难以制备和调节孔径。在此，我们报道了两种新型的亚纳米孔共价有机框架（COF），它们首次被应用于氙/氪的筛分。通过一种简便、可操作且高效的多位点烷基化策略，利用醛-胺缩聚反应以及随后的孔径调节和均匀化过程合成了亚纳米孔COF。令人印象深刻的是，所制备的亚纳米孔COF由于其孔径（约7 Å）略大于氙/氪的动态直径且孔体积较大，实现了对氙/氪的高效吸附和筛分。氙的最大吸附容量高达85.6 cm/g，氙/氪选择性可达9.7。此外，所制备的COF具有良好的γ射线辐照稳定性，这使其在实际应用中对放射性氙/氪的筛分具有巨大潜力。本研究中提出的多位点烷基化策略为多孔材料，特别是亚纳米孔吸附材料的孔结构构建和控制提供了一种有价值的方法。
