Comprehensive Pore Tuning in an Ultrastable Fluorinated Anion Cross-Linked Cage-Like MOF for Simultaneous Benchmark Propyne Recovery and Propylene Purification

Propyne/propylene (C3H4/C3H6) separation is an important but challenging industrial process to produce polymer-grade C3H6 and recover high-purity C3H4. Herein, we report an ultrastable TiF62- anion cross-linked metal-organic framework (ZNU-2) with precisely controlled pore size, shape and functionality for benchmark C3H4 storage (3.9/7.7 mmol g(-1) at 0.01/1.0 bar and 298 K) and record high C3H4/C3H6 (10/90) separation potential (31.0 mol kg(-1)). The remarkable C3H4/C3H6 (1/99, 10/90, 50/50) separation performance was fully demonstrated by simulated and experimental breakthroughs under various conditions with excellent recyclability and high productivity (42 mol kg(-1)) of polymer-grade C3H6 from a 1/99 C3H4/C3H6 mixture. A modelling study revealed that the symmetrical spatial distribution of six TiF62- on the icosahedral cage surface provides two distinct binding sites for C3H4 adsorption: one serves as a tailored single C3H4 molecule trap and the other boosts C3H4 accommodation by cooperative host-guest and guest-guest interactions.

Automated summary

In this study, a new metal-organic framework (ZNU-2) was developed for efficient separation of propyne and propylene. The performance of the framework was tested under different conditions through simulations and experiments, demonstrating excellent recyclability and high productivity.