Modulator Engineering of a MOF: Minimizing Defects to Boost Molecular-Sieving C₃F₈ Purification

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Molecular sieving is crucial for purifying perfluoropropane (C3F8), but existing methods are hindered by material defects.
• Metal-Organic Frameworks (MOFs) show promise for gas separation, yet controlling their crystallinity and defects remains a challenge.

Purpose of the Study:

• To develop a novel strategy for fabricating highly crystalline, defect-minimized MOF-801 for efficient C3F8 purification.
• To evaluate the performance of the engineered MOF-801 in separating C3F8 from other fluorocarbons, including C3F6, C2F6, and CF4.

Main Methods:

• A formic acid modulation technique was employed to synthesize MOF-801 with enhanced crystallinity and reduced structural defects.
• Gas adsorption isotherms and dynamic breakthrough experiments were conducted to assess separation capabilities for binary and ternary mixtures.
• The scalability of the synthesis method was investigated.

Main Results:

• The optimized ND-MOF-801 demonstrated exceptional C3F6/C3F8 separation with a high uptake ratio (240) and negligible C3F8 co-adsorption.
• Selective adsorption of C2F6 and CF4 over C3F8 was achieved, enabling the first reported sieving separation of a CF4/C2F6/C3F8 mixture.
• One-step purification of C3F8 to >99.999% purity was accomplished, and the material was successfully scaled up to 100g.

Conclusions:

• Formic acid modulation is an effective approach for creating defect-minimized MOFs with superior molecular sieving properties.
• The developed ND-MOF-801 offers a practical and scalable solution for producing high-purity C3F8.
• This study advances the field of gas separation using engineered crystalline materials.