Metal Node Guided Pore Engineering in Carborane‐Based MOFs for Efficient C ₂ H ₂ /CO ₂ and C ₂ H ₂ /C ₂ H ₄ Separations

Abstract

ABSTRACT The efficient separation of C 2 H 2 from C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 mixtures is essential for the preparation of high‐purity C 2 H 2 and C 2 H 4 , but challenged by the trade‐off between the capacity and selectivity. In this work, we report a node guided pore engineering strategy in carborane‐based metal‐organic frameworks (MOFs), leading to the partitioned dual cage system in Co‐CB‐HPBTA in contrast to its analogue Zn‐CB‐HPBTA with one‐dimensional channels. This structural evolution endows Co‐CB‐HPBTA with a high C 2 H 2 adsorption capacity of 103.2 cm 3 /g (4.61 mmol/g) at 298 K and 1 bar, along with superior selectivity for C 2 H 2 /CO 2 (10.6) and C 2 H 2 /C 2 H 4 (13.3). Breakthrough experiments confirm its excellent separation performance for both mixtures under varied conditions, demonstrating efficient recovery of high‐purity C 2 H 2 and C 2 H 4 with remarkable cyclic stability and humidity tolerance. The separation mechanism is elucidated by DFT calculations and in situ single‐crystal‐ray diffraction, which reveal enhanced binding interactions within the partitioned cages through multiple van der Waals contacts, rationalizing the high selectivity.