Engineering Pore Chemistry and Environment in Robust Metal–Organic Frameworks for One-Step C₂H₄ Purification from Ternary Mixtures

Purification of C₂H₄ from ternary C₂H₂/C₂H₆/C₂H₄ mixtures via one-step separation strategies remains a challenge but is of great importance in the petrochemical industry. Guided by reticular chemistry and pore engineering, we regulate the pore size and shape in line with disparate numbers of incorporated Lewis basic sites into two isomorphic MOFs for efficient one-step C₂H₄ isolation from ternary mixtures. Highly stable Zn-MOFs, modified from two functionalized amino groups to a single amino group, exhibit a structural shift from whistling-shaped to irregular pores. The larger and optimal irregular pore size, combined with Lewis basic amino groups, enhances the affinity for C₂H₂ and C₂H₆ over C₂H₄ and improves their sorption capacities. In contrast to the two-amino-functionalized Zn prototype, ZnatzOAC traps C₂H₂ up to 43 cm³ g^-1 along with a high C₂H₂ packing density of 266.9 g L^-1 at 298 K and 0.1 bar. Multiple-component dynamic breakthrough experiments further reveal that ZnatzOAC exhibits exceptional separation performance of ternary C₂H₂/C₂H₆/C₂H₄ mixtures with a polymer-grade purity of 99.95% for C₂H₄. Furthermore, theoretical calculations confirm that MOFs decorated with appropriate numbers of amino groups can suitably modify the pore environment and pore shape to provide strong multiple intermolecular interactions with C₂H₂ and C₂H₆ molecules over C₂H₄.