Optimizing Multivariate Metal–Organic Frameworks for Efficient C 2 H 2 /CO 2 Separation

Adsorptive separation of acetylene (C 2 H 2 ) from carbon dioxide (CO 2 ) promises a practical way to produce high-purity C 2 H 2 required for industrial applications. However, challenges exist in the pore environment engineering of porous materials to recognize two molecules due to their similar molecular sizes and physical properties. Herein, we report a strategy to optimize pore environments of multivariate metal–organic frameworks (MOFs) for efficient C 2 H 2 /CO 2 separation by tuning metal components, functionalized linkers, and terminal ligands. The optimized material UPC-200(Al)-F-BIM, constructed from Al 3+ clusters, fluorine-functionalized organic linkers, and benzimidazole terminal ligands, demonstrated the highest separation efficiency (C 2 H 2 /CO 2 uptake ratio of 2.6) and highest C 2 H 2 productivity among UPC-200 systems. Experimental and computational studies revealed the contribution of small pore size and polar functional groups on the C 2 H 2 /CO 2 selectivity and indicated the practical C 2 H 2 /CO 2 separation of UPC-200(Al)-F-BIM.