Modulator Engineering of a MOF: Minimizing Defects to Boost Molecular‐Sieving C ₃ F ₈ Purification

ABSTRACT

Purification of perfluoropropane (C ₃ F ₈ ) by molecular sieving is highly desired, but nonideal crystallization and structural defects compromise sieving efficiency. In this study, a formic acid modulation strategy was developed to fabricate MOF‐801 with high crystallinity and minimized defects, enabling ideal molecular‐sieving C ₃ F ₆ /C ₃ F ₈ separation with negligible C ₃ F ₈ co‐adsorption. Satisfactorily, the optimized non‐defect ND‐MOF‐801 exhibits strong affinity for C ₃ F ₆ (62.4 cm ³ g ⁻¹ at 1 bar) but a record‐low C ₃ F ₈ uptake capacity of 0.26 cm ³ g ⁻¹ due to rigorous size exclusion, affording an unprecedented C ₃ F ₆ /C ₃ F ₈ uptake ratio of 240. Meanwhile, it selectively captures C ₂ F ₆ (48.2 cm ³ g ⁻¹ ) and CF ₄ (23.3 cm ³ g ⁻¹ ) over C ₃ F ₈ , achieving the first reported sieving separation of the ternary CF ₄ /C ₂ F ₆ /C ₃ F ₈ mixture. Dynamic breakthrough experiments confirm the efficient separation of both binary C ₃ F ₆ /C ₃ F ₈ and ternary CF ₄ /C ₂ F ₆ /C ₃ F ₈ mixtures, enabling one‐step purification of C ₃ F ₈ with ultra‐high purity (>99.999%). Notably, ND‐MOF‐801 can be easily scaled up to 100 g via a facile reflux method without loss of the superior sieving performance. Collectively, this work not only delivers a practical adsorbent for high‑purity C ₃ F ₈ production, but also highlights formic acid modulation as a versatile approach to engineer defect‑minimized, high‑crystallinity frameworks for ideal molecular sieving.