Effects of hydroxyl-functionalization and sub-Tg thermal annealing on high pressure pure- and mixed-gas CO2/CH4 separation by polyimide membranes based on 6FDA and triptycene-containing dianhydrides

Handle URI:
http://hdl.handle.net/10754/564031
Title:
Effects of hydroxyl-functionalization and sub-Tg thermal annealing on high pressure pure- and mixed-gas CO2/CH4 separation by polyimide membranes based on 6FDA and triptycene-containing dianhydrides
Authors:
Swaidan, Raja ( 0000-0002-9296-6501 ) ; Ghanem, Bader ( 0000-0002-2044-2434 ) ; Litwiller, Eric ( 0000-0001-5366-0967 ) ; Pinnau, Ingo ( 0000-0003-3040-9088 )
Abstract:
A sub-Tg thermally-annealed (250°C, 24h) ultra-microporous PIM-polyimide bearing a 9,10-diisopropyl-triptycene contortion center and hydroxyl-functionalized diamine (2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane, APAF) exhibited plasticization resistance up to 50bar for a 1:1 CO2/CH4 feed mixture, with a 9-fold higher CO2 permeability (30Barrer) and 2-fold increase in CO2/CH4 permselectivity (~50) over conventional dense cellulose acetate membranes at 10bar CO2 partial pressure. Interestingly, mixed-gas CO2/CH4 permselectivities were 10-20% higher than those evaluated under pure-gas conditions due to reduction of mixed-gas CH4 permeability by co-permeation of CO2. Gas transport, physisorption and fluorescence studies indicated a sieving pore-structure engaged in inter-chain charge transfer complexes (CTCs), similar to that of low-free-volume 6FDA-APAF polyimide. The isosteric heat of adsorption of CO2 as well as CO2/CH4 solubility selectivities varied negligibly upon replacement of OH with CH3 but CTC formation was hindered, CO2 sorption increased, CO2 permeability increased ~3-fold, CO2/CH4 permselectivity dropped to ~30 and CH4 mixed-gas co-permeation increased. These results suggest that hydroxyl-functionalization did not cause preferential polymer-gas interactions but primarily elicited diffusion-dominated changes owing to a tightened microstructure more resistant to CO2-induced dilations. Solution-processable hydroxyl-functionalized PIM-type polyimides provide a new platform of advanced materials that unites the high selectivities of low-free-volume polymers with the high permeabilities of PIM-type materials particularly for natural gas sweetening applications.
KAUST Department:
Advanced Membranes and Porous Materials Research Center; Physical Sciences and Engineering (PSE) Division; Chemical and Biological Engineering Program
Publisher:
Elsevier BV
Journal:
Journal of Membrane Science
Issue Date:
Feb-2015
DOI:
10.1016/j.memsci.2014.10.046
Type:
Article
ISSN:
03767388
Sponsors:
The authors acknowledge KAUST funding for Prof. Ingo Pinnau, Dr. Youssef Belmabkhout is thanked for helpful discussions on sorption experiments. Dr. Osama Shekhah and Agnes Sweileh contributed to helpful discussions on fluorescence experiments.
Appears in Collections:
Articles; Advanced Membranes and Porous Materials Research Center; Physical Sciences and Engineering (PSE) Division; Chemical and Biological Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.authorSwaidan, Rajaen
dc.contributor.authorGhanem, Baderen
dc.contributor.authorLitwiller, Ericen
dc.contributor.authorPinnau, Ingoen
dc.date.accessioned2015-08-03T12:29:07Zen
dc.date.available2015-08-03T12:29:07Zen
dc.date.issued2015-02en
dc.identifier.issn03767388en
dc.identifier.doi10.1016/j.memsci.2014.10.046en
dc.identifier.urihttp://hdl.handle.net/10754/564031en
dc.description.abstractA sub-Tg thermally-annealed (250°C, 24h) ultra-microporous PIM-polyimide bearing a 9,10-diisopropyl-triptycene contortion center and hydroxyl-functionalized diamine (2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane, APAF) exhibited plasticization resistance up to 50bar for a 1:1 CO2/CH4 feed mixture, with a 9-fold higher CO2 permeability (30Barrer) and 2-fold increase in CO2/CH4 permselectivity (~50) over conventional dense cellulose acetate membranes at 10bar CO2 partial pressure. Interestingly, mixed-gas CO2/CH4 permselectivities were 10-20% higher than those evaluated under pure-gas conditions due to reduction of mixed-gas CH4 permeability by co-permeation of CO2. Gas transport, physisorption and fluorescence studies indicated a sieving pore-structure engaged in inter-chain charge transfer complexes (CTCs), similar to that of low-free-volume 6FDA-APAF polyimide. The isosteric heat of adsorption of CO2 as well as CO2/CH4 solubility selectivities varied negligibly upon replacement of OH with CH3 but CTC formation was hindered, CO2 sorption increased, CO2 permeability increased ~3-fold, CO2/CH4 permselectivity dropped to ~30 and CH4 mixed-gas co-permeation increased. These results suggest that hydroxyl-functionalization did not cause preferential polymer-gas interactions but primarily elicited diffusion-dominated changes owing to a tightened microstructure more resistant to CO2-induced dilations. Solution-processable hydroxyl-functionalized PIM-type polyimides provide a new platform of advanced materials that unites the high selectivities of low-free-volume polymers with the high permeabilities of PIM-type materials particularly for natural gas sweetening applications.en
dc.description.sponsorshipThe authors acknowledge KAUST funding for Prof. Ingo Pinnau, Dr. Youssef Belmabkhout is thanked for helpful discussions on sorption experiments. Dr. Osama Shekhah and Agnes Sweileh contributed to helpful discussions on fluorescence experiments.en
dc.publisherElsevier BVen
dc.subjectCarbon dioxide separationen
dc.subjectHydroxyl functionalityen
dc.subjectMicroporosityen
dc.subjectPolyimidesen
dc.subjectTriptyceneen
dc.titleEffects of hydroxyl-functionalization and sub-Tg thermal annealing on high pressure pure- and mixed-gas CO2/CH4 separation by polyimide membranes based on 6FDA and triptycene-containing dianhydridesen
dc.typeArticleen
dc.contributor.departmentAdvanced Membranes and Porous Materials Research Centeren
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentChemical and Biological Engineering Programen
dc.identifier.journalJournal of Membrane Scienceen
kaust.authorSwaidan, Rajaen
kaust.authorGhanem, Baderen
kaust.authorLitwiller, Ericen
kaust.authorPinnau, Ingoen
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