Polybenzimidazole-derived carbon molecular sieve hollow fiber membranes with tailored oxygen selective transport

Abstract

Polymer membrane carbonization is a promising strategy to obtain carbon molecular sieve (CMS) membrane materials with tailorable cavity size distributions for high gas selectivities beyond that attained from traditional polymer membrane materials. Despite their already demonstrated exceptional separation performance characteristics for several gas separation applications (e.g. CO2/CH4 and H2/CO2), further development of CMS membranes having high O2/N2 perm-selectivity for energy-efficient high-purity O2 production has proven challenging. Herein, we explore CMS hollow fiber membranes (HFMs) derived from highly rigid and tightly-packed polybenzimidazole (PBI) materials. Nearly defect-free PBI-derived CMS HFMs were fabricated and evaluated for O2/N2 separation performance for the first time. The micro-structural and O2 selective gas separation characteristics of PBI-CMS HFMs pyrolyzed at different pyrolysis conditions were intensively studied. With rigorous carbonization protocol optimization, we obtained highly O2 permselective PBI-CMS HFMs having O2/N2 selectivities approaching 14, enabling high purity O2 production. The PBI-CMS HFM O2/N2 separation performance dependence on operating conditions (e.g. temperature and feed pressure) are reported.