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

Propyne/propylene (C 3 H 4 /C 3 H 6 ) separation is an important but challenging industrial process to produce polymer-grade C 3 H 6 and recover high-purity C 3 H 4 . Herein, we report an ultrastable TiF 6 2- anion cross-linked metal-organic framework (ZNU-2) with precisely controlled pore size, shape and functionality for benchmark C 3 H 4 storage (3.9/7.7 mmol g -1 at 0.01/1.0 bar and 298 K) and record high C 3 H 4 /C 3 H 6 (10/90) separation potential (31.0 mol kg -1 ). The remarkable C 3 H 4 /C 3 H 6 (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 C 3 H 6 from a 1/99 C 3 H 4 /C 3 H 6 mixture. A modelling study revealed that the symmetrical spatial distribution of six TiF 6 2- on the icosahedral cage surface provides two distinct binding sites for C 3 H 4 adsorption: one serves as a tailored single C 3 H 4 molecule trap and the other boosts C 3 H 4 accommodation by cooperative host-guest and guest-guest interactions.