Pore Space Partition within a Metal–Organic Framework for Highly Efficient C₂H₂/CO₂ Separation

Abstract

The pore space partition (PSP) approach has been employed to realize a novel porous MOF (FJU-90) with dual functionalities for the challenging C₂H₂/CO₂ separation under ambient conditions. By virtue of a triangular ligand (Tripp = 2,4,6-tris(4-pyridyl)pyridine), the cylindrical channels in the original FJU-88 have been partitioned into uniformly interconnected pore cavities, leading to the dramatically reduced pore apertures from 12.0 × 9.4 to 5.4 × 5.1 Ų. Narrowing down the pore sizes, the resulting activated FJU-90a takes up a very large amount of C₂H₂ (180 cm³ g^-1) but much less of CO₂ (103 cm³ g^-1) at 298 K and 1 bar, demonstrating it to be the best porous MOF material for this C₂H₂/CO₂ (50%:50%) separation in terms of the C₂H₂ gravimetric productivity. IAST calculations, molecular modeling studies, and simulated and experimental breakthrough experiments comprehensively demonstrate that the pore space partition strategy is a very powerful approach to constructing MOFs with dual functionality for challenging gas separation.