Direct Observation of Xe and Kr Adsorption in a Xe-Selective Microporous Metal鈥揙rganic Framework

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• 作者：Xianyin Chen ; Anna M. Plonka ; Debasis Banerjee ; Rajamani Krishna ; Herbert T. Schaef ; Sanjit Ghose ; Praveen K. Thallapally ; John B. Parise
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：June 10, 2015
• 年：2015
• 卷：137
• 期：22
• 页码：7007-7010
• 全文大小：281K
• ISSN：1520-5126

文摘

The cryogenic separation of noble gases is energy-intensive and expensive, especially when low concentrations are involved. Metal鈥搊rganic frameworks (MOFs) containing polarizing groups within their pore spaces are predicted to be efficient Xe/Kr solid-state adsorbents, but no experimental insights into the nature of the Xe鈥搉etwork interaction are available to date. Here we report a new microporous MOF (designated SBMOF-2) that is selective toward Xe over Kr under ambient conditions, with a Xe/Kr selectivity of about 10 and a Xe capacity of 27.07 wt % at 298 K. Single-crystal diffraction results show that the Xe selectivity may be attributed to the specific geometry of the pores, forming cages built with phenyl rings and enriched with polar 鈭扥H groups, both of which serve as strong adsorption sites for polarizable Xe gas. The Xe/Kr separation in SBMOF-2 was investigated with experimental and computational breakthrough methods. These experiments showed that Kr broke through the column first, followed by Xe, which confirmed that SBMOF-2 has a real practical potential for separating Xe from Kr. Calculations showed that the capacity and adsorption selectivity of SBMOF-2 are comparable to those of the best-performing unmodified MOFs such as NiMOF-74 or Co formate.