Electrostatic Potential Matching in an Anion-Pillared Framework for Benchmark Hexafluoroethane Purification from...

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Hexafluoroethane (CF₃CF₃) is essential in semiconductor manufacturing.
• Separating CF₃CF₃ from mixtures like CF₃CH₂F/CF₃CHF₂/CF₃CF₃ is challenging due to its inertness.
• Existing porous materials struggle to create specific recognition sites for efficient separation.

Purpose of the Study:

• To develop a novel material for the efficient one-step purification of CF₃CF₃.
• To investigate the use of anion-pillared metal-organic frameworks (MOFs) for separating fluorinated electronic gases.
• To achieve benchmark separation performance for CF₃CH₂F/CF₃CHF₂/CF₃CF₃ mixtures.

Main Methods:

• Utilized SIFSIX-1-Cu, an anion-pillared MOF with bipolar pores.
• Employed electrostatic potential matching for selective gas adsorption.
• Conducted one-step breakthrough experiments with a CF₃CH₂F/CF₃CHF₂/CF₃CF₃ mixture (5/5/90).
• Performed theoretical calculations to understand adsorption mechanisms.

Main Results:

• SIFSIX-1-Cu demonstrated the highest adsorption capacity for CF₃CH₂F and CF₃CHF₂ at 0.01 bar.
• Achieved the highest IAST selectivity for CF₃CH₂F/CF₃CF₃ and CF₃CHF₂/CF₃CF₃.
• Obtained high-purity CF₃CF₃ (≥ 99.995%) with record productivity (882.9 L kg⁻¹).
• Theoretical calculations confirmed strong anchoring of CF₃CH₂F and CF₃CHF₂ via multiple supramolecular interactions.

Conclusions:

• Anion-pillared MOFs, specifically SIFSIX-1-Cu, are effective for separating fluorinated electronic gases.
• The unique bipolar pore structure of SIFSIX-1-Cu enables selective adsorption through electrostatic potential matching.
• This work presents a significant advancement in achieving high-purity CF₃CF₃ production for industrial applications.