Aluminum-based microporous metal–organic framework for noble gas separation

Abstract

Obtaining pure Xe from Xe/Kr mixture arising from various sources (nuclear accidents, advanced reactors, reprocessing of used nuclear fuel, air etc) is of environmental and industrial importance. We evaluated the Xe/Kr separation performance of aluminum-based MOF (Al-SDB) constructed with a V-shaped organic linker. The Al-SDB has a high Xe capacity of 1.6 mmol/g at 100 kPa and 298 K, while exhibiting a low affinity for Kr. In addition, it shows a high working capacity (0.6 mmol/g) compared to other metal based SDB MOFs, confirming its potential for PSA process and role of metal nodes in noble gas adsorption. The Al-SDB also exhibited an IAST Xe/Kr selectivity of 14.2, which is a relatively high Xe/Kr selectivity compared to reported MOFs under similar conditions. To further evaluate the utility of Al-SDB for Xe/Kr separation from gas mixture under flow conditions, the breakthrough experiment was carried out using Al-SDB-filled column under dynamic flow condition. Remarkably, the breakthrough curves of Al-SDB shows that Xe/Kr mixture can be separated efficiently. These results indicated that Al-SDB can be regarded as a potential adsorbent to replace cryogenic distillation for the separation of Xe/Kr mixtures.