Dynamic separation of Xe and Kr by metal-organic framework and covalent-organic materials: a comparison with activated charcoal

We systematically investigate dynamic separation of Xe and Kr at room temperature using four representative porous materials(Cu-BTC, ZIF-8, COP-4 and activated carbon（AC）). Results indicate that among the four materials, Cu-BTC not only shows the highest retention volume per gram(V;=788 m L g;, which is 1.8 times of activated carbon(436 m L g;)) under flowing condition, but also can separate 350 ppm Xe from 35 ppm Kr mixture in air with a high Xe/Kr selectivity of 8.6 at room temperature and 200 k Pa, due to its suitable pore morphology, open metal sites, small side pockets in the framework. Moreover, the Cu-BTC also performs well on individual separation of Xe, Kr, CO;from five-component gas mixture（Xe:Kr:CO;:Ar:N;= 1:1:1:1:0.5, V/V） and has the longest retention time for Xe（20 min） in gas chromatographic separation, suggesting that it is a good candidate for potential applications as polymeric sieves.