Novel Carborane Based Metal Organic Framework for Record Electronic Specialty Gas C ₂ F ₆ Purification via Molecular Sieving

Abstract

ABSTRACT The production of high‐purity perfluoroethane (C 2 F 6 ), an essential electronic specialty gas, requires the removal of its partially‐fluorinated analog, pentafluoroethane C 2 F 5 H. This separation is exceptionally challenging due to their similar physicochemical properties. Herein, we report a novel carborane‐based metal‐organic framework, ZNU‐23 (Ni‐CB‐HPBTA), engineered with a pearl‐chain‐like pore architecture to achieve unprecedented molecular sieving separation. The narrow pore channel and large cavity in ZNU‐23 facilitate the high and fast uptake of C 2 F 5 H (65.2 cm 3 ·g −1 at 298 K and 1 bar) while nearly completely excluding C 2 F 6 , leading to a record‐high IAST selectivity exceeding 5000 for a C 2 F 5 H/C 2 F 6 (1/99) mixture. Dynamic breakthrough experiments confirm its excellent separation performance across various mixture ratios, remarkable stability under humid and elevated‐temperature conditions, and superb recyclability. Mechanistic studies via GCMC simulations and DFT calculations attribute this performance to the multi‐site confinement of C 2 F 5 H within the pearl‐chain pores and the complete steric exclusion of the larger C 2 F 6 molecule. The potential C 2 F 5 H binding sites within the framework were further revealed by C 2 F 5 H‐loaded single crystal structure of ZNU‐23.