High-performance carbon molecular sieve membranes for ethylene/ethane separation derived from an intrinsically microporous polyimide
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Type
ArticleKAUST Department
Advanced Membranes and Porous Materials Research CenterChemical Engineering Program
Physical Science and Engineering (PSE) Division
Date
2015-11-18Online Publication Date
2015-11-18Print Publication Date
2016-02Permanent link to this record
http://hdl.handle.net/10754/582485
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An intrinsically microporous polymer with hydroxyl functionalities, PIM-6FDA-OH, was used as a precursor for various types of carbon molecular sieve (CMS) membranes for ethylene/ethane separation. The pristine polyimide films were heated under controlled N2 atmosphere at different stages from 500 to 800 °C. All CMS samples carbonized above 600 °C surpassed the polymeric ethylene/ethane upper bound. Pure-gas selectivity reached 17.5 for the CMS carbonized at 800 °C with an ethylene permeability of about 10 Barrer at 2 bar and 35 °C, becoming the most selective CMS for ethylene/ethane separation reported to date. As expected, gravimetric sorption experiments showed that all CMS membranes had ethylene/ethane solubility selectivities close to one. The permselectivity increased with increasing pyrolysis temperature due to densification of the micropores in the CMS membranes, leading to enhanced diffusivity selectivity. Mixed-gas tests with a binary 50:50 v/v ethylene/ethane feed showed a decrease in selectivity from 14 to 8.3 as the total feed pressure was increased from 4 to 20 bar. The selectivity drop under mixed-gas conditions was attributed to non-ideal effects: (i) Competitive sorption that reduced the permeability of ethylene and (ii) dilation of the CMS that resulted in an increase in the ethane permeability.Citation
High-performance carbon molecular sieve membranes for ethylene/ethane separation derived from an intrinsically microporous polyimide 2015 Journal of Membrane SciencePublisher
Elsevier BVJournal
Journal of Membrane ScienceAdditional Links
http://linkinghub.elsevier.com/retrieve/pii/S037673881530315Xae974a485f413a2113503eed53cd6c53
10.1016/j.memsci.2015.11.013