Three Polyhedron-Based Metal-Organic Frameworks Exhibiting Excellent Acetylene Selective Adsorption

The separation of acetylene (C₂H₂) from ethylene (C₂H₄) and ethane (C₂H₆) is crucial for the production of high-purity C₂H₂ and the recovery of other gases. Polyhedron-based metal-organic frameworks (PMOFs) are characterized by their spacious cavities, which facilitate gas trapping, and cage windows with varying sizes that enable gas screening. In this study, we carefully selected a class of PMOFs based on V-type tetracarboxylic acid linker (JLU-Liu22 containing benzene ring, JLU-Liu46 containing urea group and recombinant reconstructed In/Cu CBDA on the basis of JLU-Liu46) to study the relationship between pore environment and C₂ adsorption and separation performance. Among the three compounds, JLU-Liu46 exhibits superior selectivity toward C₂H₂/C₂H₄ (2.06) as well as C₂H₂/C₂H₆ (2.43). Comparative structural analysis reveals that the exceptional adsorbed-C₂H₂ performance of JLU-Liu46 can be attributed to the synergistic effects arising from coordinatively unsaturated Cu sites combined with an optimal pore environment (matched pore size and polarity, urea functional group), resulting in a strong affinity between the framework and C₂H₂ molecules. Furthermore, transient breakthrough simulations of JLU-Liu46 confirmed its potential for separating C₂H₂ in ternary C₂ gas.