Two In-MOFs based on pore size control strategy for highly selective separation of SF6

Abstract

Efficient adsorption and separation of SF₆ is very important for the electrical industry. In the present work, two In-MOFs (In-MOF1, In-MOF2) have been synthesized and characterized. The compounds show three-dimensional coordination networks. And the BET surface areas of them reach 859.7 cm²/g and 971.1 cm²/g, respectively. More importantly, their averaged pore sizes are mainly 5.24 Å and 5.67 Å, which are well matched with the kinetic diameter of SF₆ (5.2 Å). The compounds show higher adsorption capacities of SF₆ (2.66 mmol/g for In-MOF1, 2.41 mmol/g for In-MOF2) at ambient temperature and pressure. And the excellent IAST selectivities of SF₆/N₂ (v/v: 10:90) up to 237.8 and 235.2 at 100 kPa. Their efficient adsorption and separation performance is mainly related to the appropriate pore size and stronger host–guest interactions. DFT calculations and theoretical simulations further support the experimental results. Furthermore, dynamic breakthrough experiments show that the actual separation coefficient can reach 262.2 and 340.8, exceeding the theoretical prediction results. The results will contribute to the design of efficient MOFs adsorbents for the selective capture of SF₆.