Synthesis of Hierarchical‐Porous Fluorinated Metal–Organic Frameworks with Superior Toluene Adsorption Properties

Abstract

Constructing metal–organic frameworks (MOFs) with high volatile organic compounds (VOCs) adsorption capacity and excellent water resistance remain challenging. Herein, a monocarboxylic acid‐assisted mixed ligands strategy was designed to synthesize a novel fluorinated MOFs, MIL‐53 (Al). The monocarboxylic acid promoted crystallization and produced abundant crystal defects, which increased pore volume. Moreover, the competitive coordination between tetrafluoroterephthalic acid and 1,4‐dicarboxybenzene was moderated by monocarboxylic modulators, significantly improving the hydrophobicity. The toluene uptake of the optimal sample reached 254.85 mg g−1 under humid conditions, increased by 33.56 % of MIL‐53(Al), and the QWet/QDry (the ratio of adsorption quality under wet to adsorption quality under dry) was 0.92, remarkably surpassing that of origin MIL‐53 (0.72). The recycle experiment showed superior reusability with no performance degradation after 10 recycle under RH=50 % (relative humidity). The adsorptive kinetic and thermodynamic analysis proves that the adsorption process is controlled by surface mono‐layer adsorption and pore diffusion. The fluorine group affects the internal diffusion, which weakens the transfer rate. This strategy opens a new prospect of obtaining hierarchical functional MOFs for meeting the VOCs uptake under the practical application.

Recent advances in the chemistry and applications of fluorinated metal–organic frameworks (F-MOFs)

“…The use of the modulator led to the formation of instable Al complexes replaced by the F 4 BDC groups thus forming the uorinated MOF. 59 The direct synthesis of the peruorinated MIL-53 MOF based on H 2 -F 4 BDC was carried out by our group via a solvent-free synthetic route. succinate (TFS) as linker which also afforded another MOF with MOF-801 structure type (PF-MOF-2) in which both fumarate and TFS are included in the framework thanks to post synthetic modication (PSM).…”

“…The use of the modulator led to the formation of instable Al complexes replaced by the F 4 BDC groups thus forming the fluorinated MOF. 59 The direct synthesis of the perfluorinated MIL-53 MOF based on H 2 -F 4 BDC was carried out by our group via a solvent-free synthetic route. F 4 -MIL-53(Al) has formula Al(OH)(F 4 BDC)·0.4H 2 O and it is constituted of infinite 1D inorganic chains made of Al octahedra linked each other by the perfluorinated linker thus designing rhombic channels of about 10.5 × 9 Å size and possessing a BET surface area higher than 1000 m 2 g −1 .…”