Abstract
The complex effects of highly sorbing feed gas contaminants such as toluene and n-heptane on performance of both annealed and non-annealed Matrimid® asymmetric fibers relevant to CO2/CH4 separation are reported. Membrane performance was quantified both during contaminant exposure and after removal of the contaminant from the feed stream. Exposure to either toluene or n-heptane during permeation reduces carbon dioxide permeance and the carbon dioxide/methane selectivity in non-annealed fibers. After exchange with a contaminant-free feed containing only CO2 and CH4 mixed gas, the carbon dioxide permeance and carbon dioxide/methane selectivity were affected, indicating a glassy state conditioning effect due to the prior contaminant exposure. Interestingly, the conditioning effect after simultaneous exposure to toluene and n-heptane (284 ppm toluene and 504 ppm n-heptane) was less than the conditioning observed for either toluene (293 ppm) or n-heptane (505 ppm) individually. Sub-Tg annealing reduced carbon dioxide permeance during actual contaminant exposure more severely than in non-annealed fibers. On the other hand, except for exposure to the highest n-heptane contaminant feed (2003 ppm), annealing significantly reduced the post-exposure conditioning observed in carbon dioxide permeance and carbon dioxide/methane selectivity. It appears that annealing allows the consolidation of segmental packing which stabilized the glassy matrix against swelling. At sufficiently high activities of even a relatively non-interacting penetrant like n-heptane, the annealing-induced stabilization can be reversed. © 2010 Elsevier B.V. All rights reserved.
Original language | English (US) |
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Pages (from-to) | 232-241 |
Number of pages | 10 |
Journal | Journal of Membrane Science |
Volume | 350 |
Issue number | 1-2 |
DOIs | |
State | Published - Mar 15 2010 |
Externally published | Yes |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledged KAUST grant number(s): KUS-I1-011-21
Acknowledgements: The authors would like to acknowledge financial support from The Coca Cola Company, Air Liqude, and Award no. KUS-I1-011-21 made by King Abdullah University of Science and Technology (KAUST).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.