Divergent Adsorption Regulation in Metal-Organic Frameworks for Highly Efficient CF₄/C₂F₆ Separation.

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Traditional methods for separating low-concentration perfluorocarbons (PFCs) like hexafluoroethane (C2F6) and tetrafluoromethane (CF4) face challenges due to trade-offs between adsorption capacity and selectivity.
• Efficient purification of PFCs is critical for the electronics industry, particularly for producing high-purity CF4.

Purpose of the Study:

• To develop a divergent regulation strategy for significantly improving the separation efficiency of low-concentration C2F6 from CF4.
• To achieve enhanced C2F6 adsorption and selectivity for high-purity CF4 production.

Main Methods:

• Utilizing an electron-deficient ligand-based pore environment with selective shielding of open metal sites and modulated channel geometry.
• Employing solid-state MAS nuclear magnetic resonance (SSNMR), molecular simulations, and comparative experiments to elucidate the separation mechanism.

Main Results:

• Achieved simultaneous enhancement of C2F6 adsorption and reduction of CF4 adsorption, leading to record-high low-pressure C2F6 uptake and C2F6/CF4 selectivity.
• Demonstrated benchmark C2F6/CF4 separation performance with unprecedented electronic-grade CF4 productivity (over 99.999%) from a relevant mixture.
• Exhibited excellent water, air, and heat stability, along with recyclability of the separation material.

Conclusions:

• The divergent regulation strategy effectively overcomes the limitations of traditional thermodynamic approaches for PFC separation.
• The developed material and method offer a promising solution for the efficient and cost-effective purification of CF4 in the electronics industry.