Abstract
Fine control of ultramicroporosity (<7 Å) in carbon molecular sieve (CMS) membranes is highly desirable for challenging gas separation processes. Here, a versatile approach is proposed to fabricate hybrid CMS (HCMS) membranes with unique textural properties as well as tunable ultramicroporosity. The HCMS membranes are formed by pyrolysis of a polymer nanocomposite precursor containing metal‐organic frameworks (MOFs) as a carbonizable nanoporous filler. The MOF‐derived carbonaceous phase displays good compatibility with the polymer‐derived carbon matrix due to the homogeneity of the two carbon phases, substantially enhancing the mechanical robustness of the resultant HCMS membranes. Detailed structural analyses reveal that the in situ pyrolysis of embedded MOFs induces more densified and interconnected carbon structures in HCMS membranes compared to those in conventional CMS membranes, leading to bimodal and narrow pore size distributions in the ultramicroporous region. Eventually, the HCMS membranes exhibit far superior gas separation performances with a strong size‐sieving ability than the conventional polymers and CMS membranes, especially for closely sized gas pairs (Δd < 0.5 Å) including CO2/CH4 and C3H6/C3H8 separations. More importantly, the developed HCMS material is successfully prepared into a thin‐film composite (TFC) membrane (≈1 µm), demonstrating its practical feasibility for use in industrial mixed‐gas operation conditions.
A novel carbon/carbon hybrid carbon molecular sieve (HCMS) membrane is fabricated by pyrolysis of a nanocomposite precursor containing metal‐organic frameworks (MOFs). The in situ carbonization of embedded MOFs induces more densified and interconnected carbon structures coupled with bimodal and narrow pore size distributions in the ultramicroporous region in resultant HCMS membranes, leading to excellent gas separation performances even under industrial operating conditions.