Vicinal Functional-Group Engineering in Defect-Engineered MOFs for One-Step Ethylene Purification

The development of C2H6-selective adsorbents offers a promising strategy for energy-efficient C2H4 purification from C2H6/C2H4 mixtures. However, the similar physicochemical properties of C2H6 and C2H4 make it challenging to achieve preferential adsorption of C2H6. Herein, we propose a vicinal functional-group engineering strategy to construct C2H6-recognition domains, enabling efficient one-step C2H4 purification from C2H6/C2H4 mixtures. The adjacent functional groups on the modulators are introduced close to the defect sites of MOFs, constructing synergistic electrostatic-confinement microenvironments for C2H6 recognition. The fluorinated-defective MOF (UiO-66-(CF3)2) exhibits C2H6 preferential adsorption with an uptake of 2.2 mmol/g at 298 K and 100 kPa. Breakthrough experiments further confirm the dynamic separation performance of UiO-66-(CF3)2, achieving high-purity C2H4 (>99.99 %) with a productivity of 12.67 L/kg. Theoretical calculations further reveal that the adjacent functional groups in the ligands would induce electrostatic potential redistribution and confined pore structures, strengthening C2H6 adsorption on defective MOF over C2H4. This work establishes a vicinal functional-group engineering strategy for constructing synergistic electrostatic-confinement microenvironments toward C2H6 recognition in MOFs.