Construction of Fluorinated Propane-Trap in Metal-Organic Frameworks for Record Polymer-Grade Propylene Production under High Humidity Conditions.

Abstract

Propane/propene (C3 H8 /C3 H6 ) separation is essential in the petrochemical industry but challenging because of their similar physical and chemical properties. Adsorptive separation with C3 H8 -selective porous materials can energy-efficiently produce high-purity C3 H6 , which is highly promising for replacing conventional cryogenic distillation but suffers from unsatisfactory performance. Herein, through the precise incorporation of fluorinated functional groups into the confined pore space, a new fluorinated metal-organic framework(FDMOF-2) featuring the unique and strong C3 H8 -trap is successfully constructed. FDMOF-2 exhibits an unprecedented C3 H8 capture capacity of 140 cm3 cm-3 and excellent C3 H8 /C3 H6 (1:1, v/v) selectivity up to 2.18 (298 K and 1bar), thus setting new benchmarks for all reported porous materials. Single-crystal X-ray diffraction studies reveal that the tailored pore confinement in FDMOF-2 provides stronger and multiple attractive interactions with C3 H8 , enabling excellent binding affinities. Breakthrough experiments demonstrate that C3 H8 can be directly extracted from various C3 H8 /C3 H6 mixtures with FDMOF-2, affording an outstanding C3 H6 production (501mmol L-1 ) with over 99.99% purity. Benefiting from the robust framework and hydrophobic ligands, the separation performance of FDMOF-2 can be well maintained even under 70% relative humidity conditions.