A Bifunctional Microporous In(III)-MOF for SF₆ Separation and Reverse Adsorption of C₂H₄/C₂H₆

The adsorption-separation process is important to the purification of gas components due to its high efficiency and low energy consumption, but the selection of adsorbents is quite challenging. Herein, a microporous In(III)-MOF (HBU-25) was synthesized by the reaction of L (L: 1,1,2,2-Tetra(4-carboxylphenyl)ethylene) ligand and In(NO₃)₃·4H₂O. It shows a large Brunauer-Emmett-Teller (BET) specific surface area (788.4 m² g^-1) and a suitable pore environment, exhibiting excellent gas separation performance. The adsorption capacity of SF₆ is 47.9 cm³ g^-1 at ambient conditions, which is higher than that of CO₂ (39.6 cm³ g^-1) and N₂ (3.4 cm³ g^-1). The IAST selectivity of SF₆/N₂ achieves 97.2. More interestingly, it also can preferentially adsorb C₂H₆ (67.9 cm³ g^-1) instead of C₂H₄ (62.3 cm³ g^-1), and the IAST selectivity of C₂H₆/C₂H₄ (10:90) is calculated as 1.97. Furthermore, breakthrough experiments prove that HBU-25 can separate SF₆ from the SF₆/CO₂/N₂ mixture and achieve reverse adsorption of C₂H₄/C₂H₆.