Temperature-dependent molecular sieving of fluorinated propane/propylene mixtures by a flexible-robust metal-organic framework

Abstract

The electronics industry necessitates highly selective adsorption separation of hexafluoropropylene (C 3 F 6 ) from perfluoropropane (C 3 F 8 ), which poses a challenge due to their similar physiochemical properties. In this work, we present a microporous flexible-robust metal-organic framework (Ca-tcpb) with thermoregulatory gate opening, a rare phenomenon that allows tunable sieving of C 3 F 8 /C 3 F 6 . Remarkably, the temperature-dependent adsorption behavior enhances the discrimination between the larger C 3 F 8 and the smaller C 3 F 6 , resulting in unprecedented C 3 F 6 /C 3 F 8 selectivity (over 10,000) compared to other well-known porous materials at an optimal temperature (298 K). Dynamic breakthrough experiments demonstrate that high-purity C 3 F 8 (over 99.999%) could be obtained from a C 3 F 6 /C 3 F 8 (10:90) mixture under ambient conditions. The unique attributes of this material encompass exceptional adsorption selectivity, remarkable structural stability, and outstanding separation performance, positioning it as a highly promising candidate for C 3 F 6 /C 3 F 8 separation. Single-crystal structural analysis of C 3 F 6 -loaded Ca-tcpb and theoretical calculations elucidate the host-guest interaction via multiple intermolecular interactions.