Fluorine-engineered two-dimensional covalent organic frameworks for enhanced C₂H₂/CO₂ separation

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Efficient separation of acetylene (C2H2) from carbon dioxide (CO2) is challenging due to similar molecular properties.
• Developing selective adsorbents is critical for acetylene purification in industrial processes.

Purpose of the Study:

• To design and synthesize novel covalent organic frameworks (COFs) for enhanced C2H2/CO2 separation.
• To investigate the effect of fluorination on the separation performance of COFs.

Main Methods:

• Synthesis of two-dimensional isoreticular COFs (TP-TFPB-COF and TP-NFPB-COF) via [3+3] imine condensation.
• Gas adsorption and selectivity measurements (IAST) at 298 K and 1 bar.
• Grand canonical Monte Carlo (GCMC) simulations to understand adsorption mechanisms.

Main Results:

• TP-NFPB-COF, with higher fluorine content, demonstrated superior C2H2/CO2 selectivity (2.86) compared to TP-TFPB-COF (2.04).
• GCMC simulations indicated that increased pore polarity and C-H⋯F interactions enhance C2H2 affinity.
• The study successfully correlated framework fluorination with improved gas separation performance.

Conclusions:

• Fluorination is an effective strategy for tuning COF pore environments and enhancing acetylene separation.
• The reported COFs show promise as selective adsorbents for acetylene purification.
• This research advances the application of COFs in challenging gas separation processes.