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.