(716d) Tuning Carbon Molecular Sieve Hollow Fiber Membranes for Gas Separation through Hyperaging

We developed carbon molecular sieve (CMS) membranes using polyimide precursors, and used the CMS to recover hydrogen from mixtures of hydrogen with short-chain (C1-C3) hydrocarbons. A post-treatment method called “hyperaging” was invented to create highly selective CMS hollow fiber membranes. It was found hyperaging benefited small molecular such as hydrogen much more than larger molecular such as ethylene. Through the utilization of hyperaging method, H₂/C₂H₄ selectivity was significantly enhanced while H₂ permeance decreased moderately. Hyperaging conditions on CMS fiber separation properties were investigated, and hyperaging mechanism was discussed. Hyperaging temperature was found to be a primary factor to influence separation performance. The workable hyperaging temperature is beyond 90 ^oC but lower than 250 ^oC. Too high temperature causes an unrecoverable damage to fiber separation properties. The post-treatment using hyperaging can also stabilize CMS materials, and maintain separation performance for the hydrogen separation application over extended periods.