Tunable π-Basic Platforms in Porous Crystals for Enhanced C₂H₂/CO₂ Separation at Elevated Temperature.

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Adsorptive separation of acetylene (C2H2) from carbon dioxide (CO2) is crucial for energy savings in industrial processes.
• High-temperature separations present challenges due to reduced adsorption affinities and selectivities.

Purpose of the Study:

• To engineer a porous coordination polymer (PCP) with tunable pore chemistry for selective acetylene adsorption.
• To achieve efficient C2H2/CO2 separation at elevated temperatures (353 K) using a novel material.

Main Methods:

• Systematic ligand functionalization of a soft framework (NTU-65) with π-conjugated units.
• Utilizing a dual chelation mode for selective C2H2 confinement within the engineered pores.
• Employing computational modeling and in situ spectroscopy to verify the adsorption mechanism.

Main Results:

• The optimal material, NTU-65-th, demonstrated C2H2-specific gate-opening behavior.
• A dual chelation mechanism involving π-systems and electronegative anions selectively trapped C2H2.
• Achieved high C2H2 uptake and promising C2H2/CO2 separation at 353 K with facile regeneration.

Conclusions:

• Precise pore chemistry modulation in PCPs can overcome the affinity-selectivity trade-off at high temperatures.
• NTU-65-th offers a viable route for energy-efficient acetylene/carbon dioxide separation.
• This study advances the design principles for advanced separation materials.