Gas-Permeable Carbon Molecular Sieve Membranes Fabricated from a Norbornene-Functionalized Polyimide–Polyhedral Oligomeric Silsesquioxane Composite

Lawal Sulaiman O.

Watanabe Kenta

Uchino Ryohei

Moriyama Norihiro

Nagasawa Hiroki

Tsuru Toshinori

Kanezashi Masakoto

Industrial & Engineering Chemistry Research

Polyhedral oligomeric silsesquioxanes (POSSs) are a promising family of regularly structured silsesquioxanes with resilient cage-like configurations and exterior edges that can be functionalized with various organic groups. In this study, POSS was functionalized with a polyimide–phenylene (PI–Ph) unit, which yielded POSS–PI–Ph to fabricate carbonized-POSS membranes (denoted as carbon-POSS) via inert pyrolysis. Replacing some PI–Ph units with norbornene (NB) increased the amount of residual carbon formed in the carbon-POSS structure. X-ray photoelectron spectroscopy and 29Si nuclear magnetic resonance analysis revealed that residual sp2-hybridized carbon atoms were connected to the POSS cage after pyrolysis at 700 °C. Analysis of single-gas permeation at 200 °C with the carbon-POSS membranes pyrolyzed at different temperatures (200–800 °C) indicated that the permeance of all investigated gases (He, H2, CO2, N2, CH4, CF4, and SF6) increased with increasing membrane pyrolysis temperature. Notably, the early onset of the decline in permeance of large-molecule gases such as CF4 and SF6 at 600 °C ensured a high N2 permeance and ideal N2/SF6 selectivity of 10–6 mol m–2 s–1 Pa–1 and 100, respectively. Overall, this study demonstrates the feasibility of preparing high-performance carbon-POSS-derived membranes by optimizing the NB functionality and the POSS content of the hybrid copolymer precursor.

eng

American Chemical Society

This document is the Accepted Manuscript version of a Published Work that appeared in final form in INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.iecr.3c03605

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[DOI] https://doi.org/10.1021/acs.iecr.3c03605 isVersionOf