CH3OH-induced structural optimization of ZIF-9 for efficient C3H6/C3H8 separation.

The efficient separation of C3H6 and C3H8 is a challenging industrial process. In this study, flexible ZIF-9 was modified by methanol solvent exchange to improve C3H6/C3H8 separation. The framework topology remained intact, while solvent-induced effects optimized the micropore size distribution, enhanced structural flexibility and enabled guest-responsive pore opening. Dynamic breakthrough tests showed that modified ZIF-9-II exhibited a significantly improved separation window, enabling effective separation in both propylene-rich and propane-rich mixtures with good cycling stability. This work demonstrates that methanol-mediated solvent exchange is an effective strategy to modulate the ZIF-9 pore structure and boost C3H6/C3H8 separation performance.