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

Authors: 
Qiu, W., Georgia Institute of Technology
Vaughn, J. T., Aramco
Liu, G., Nanjing Tech University
Xu, L., The Dow Chemical Company
Brayden, M., The Dow Chemical Company
Martinez, M., The Dow Chemical Company
Fitzgibbonsb, T., Dow Chemicals
Wenz, G., Mosaic Materials
Koros, W., Georgia Tech
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.