Fluorinated Biphenyldicarboxylate-Based Metal-Organic Framework Exhibiting Efficient Propyne/Propylene Separation

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Chemical Engineering

Background:

• Metal-organic frameworks (MOFs) offer tunable porous structures for gas adsorption and separation.
• Fluorinated organic linkers can introduce specific host-guest interactions, enhancing selective adsorption.
• Efficient separation of propyne (C3H4) from propylene (C3H6) is crucial for petrochemical processes.

Purpose of the Study:

• To synthesize and characterize a novel fluorinated MOF for selective gas adsorption.
• To investigate the MOF's performance in separating propyne from propylene.
• To elucidate the mechanism behind the selective gas separation.

Main Methods:

• Synthesis of 3,3',5,5'-tetrafluorobiphenyl-4,4'-dicarboxylic acid (H2-TFBPDC) ligand and its terbium MOF (JXNU-6).
• Gas adsorption experiments and column-breakthrough studies using activated JXNU-6 (JXNU-6a).
• Computational modeling to understand host-guest interactions and binding sites.

Main Results:

• JXNU-6 features a 3D framework with 1D fluorine-lined channels.
• Activated JXNU-6a demonstrated distinct adsorption of propyne (C3H4) and propylene (C3H6).
• Effective removal of trace propyne from propylene was achieved at ambient conditions.
• Modeling revealed preferential binding of propyne to exposed fluorine atoms via C-H···F hydrogen bonds.

Conclusions:

• The fluorinated MOF JXNU-6a exhibits excellent performance in separating propyne from propylene.
• Selective separation is driven by strong C-H···F hydrogen bonding interactions.
• This study presents a viable strategy for designing MOFs for specific gas recognition using fluorinated ligands.