tert-Butyl Functionalized Ultra-Microporous Three-Dimensional Covalent Organic Framework for Efficient SF₆/N₂...

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Sulfur hexafluoride (SF₆) is a potent greenhouse gas with significant environmental impact.
• Efficient capture and recycling of SF₆ are vital for the electronics industry and climate change mitigation.
• Current separation technologies face challenges in selectivity and efficiency.

Purpose of the Study:

• To develop a novel material for efficient SF₆ capture and recovery from SF₆/N₂ mixtures.
• To investigate the potential of ultra-microporous covalent organic frameworks (COFs) for gas separation.
• To demonstrate pore surface engineering for enhanced greenhouse gas separation.

Main Methods:

• Synthesis of a novel ultra-microporous 3D COF, CPOF-12, functionalized with tert-butyl groups.
• Characterization of CPOF-12 using Brunauer-Emmett-Teller (BET) analysis for surface area and pore size determination.
• Gas adsorption measurements to evaluate SF₆ uptake and SF₆/N₂ selectivity using ideal adsorbed solution theory (IAST).

Main Results:

• CPOF-12 exhibits a BET surface area of 1,140 m² g^-1 and a pore volume of 0.66 cm³ g^-1.
• The material possesses a uniform pore size of 0.59 nm, ideal for SF₆ (0.52 nm kinetic diameter) adsorption.
• High SF₆ uptake (2.20 mmol g^-1) and exceptional SF₆/N₂ selectivity (149.4) were achieved at 298 K and 1 bar.

Conclusions:

• CPOF-12 demonstrates superior performance in SF₆ capture and separation.
• Pore surface engineering in COFs is a highly effective strategy for selective greenhouse gas separation.
• This research contributes to sustainable practices in the electronics industry and environmental protection.