Optimizing the Adsorptive Separation of Three‐Component C2 Hydrocarbons by Pore Environment Regulation in Metal–Organic Frameworks

One-step adsorptive purification of ethylene (C₂H₄) from C2 ternary hydrocarbon mixtures containing acetylene (C₂H₂) and ethane (C₂H₆) remains a fundamental challenge as it involves simultaneously selective adsorption of C₂H₆ over C₂H₄ and C₂H₂ over C₂H₄. Here, we report the successful practice of a Nanopore Environment Engineering approach within isoreticular metal-organic frameworks (MOFs) that enables optimal separation of C2 ternary mixtures. Using a pair of pyrimidine-bridged tetracarboxylate ligands bearing either methyl (─CH₃) or amino (─NH₂) groups, we synthesized two csq-type Zr-MOFs, HIAM-411 and HIAM-412, with modulated nanopore environments. While HIAM-411 displays selective adsorption of C₂H₂ and C₂H₆ over C₂H₄, its separation efficiency is largely restricted by the relatively low C₂H₂/C₂H₄ selectivity. In contrast, the amino-functionalized HIAM-412 exhibited significantly strengthened hydrogen bonding interactions with C₂H₂, achieving an approximately 3-fold enhancement in the productivity of the high-purity C₂H₄. Our study highlights the critical role of nanopore environment regulation in optimizing the multicomponent separation performance of C2 hydrocarbons.