Engineering Supramolecular Binding Sites in an Ultrastable and Hydrophobic Metal–Organic Framework for C2H6/C2H4 Separation

The separation of ethane (C2H6) from ethylene (C2H4) is critical for obtaining polymer-grade C2H4. Adsorptive separation with C2H6-selective MOFs offers a viable alternative to energy-intensive cryogenic distillation, enabling the direct production of high-purity C2H4. In this study, we developed an ultrastable ethane-selective metal–organic framework, UiO-67-(CH3)2, which demonstrates enhanced C2H6 adsorption (4.10 mmol g–1 at 1 bar and 298 K), higher C2H6/C2H4 selectivity of 1.70, and an increased C2H6/C2H4 adsorption ratio of 1.53 compared to unmodified UiO-67. GCMC simulations demonstrate that C2H6 forms more C–H···π interactions with the surrounding benzene rings and more C–H···C interactions with methyl groups compared to C2H4, highlighting the synergistic effects of supramolecular interactions. Furthermore, the hydrophobic pore environment also minimizes water interference, with exceptionally low water uptake (0.019 g g–1 at 60% RH), ensuring robust separation capacity under high humid conditions. The introduction of methyl groups not only significantly enhances C2H6 adsorption performance and C2H6/C2H4 separation selectivity but also improves material’s hydrophobicity.