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

Abstract

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.