title: Gas separation performance of carbon molecular sieve membranes based on 6FDA-mPDA/DABA (3:2) polyimide.
abstract: 6FDA-mPDA/DABA (3:2) polyimide was synthesized and characterized for uncross-linked, thermally crosslinked, and carbon molecular sieve (CMS) membranes. The membranes were characterized with thermogravimetric analysis, FTIR spectroscopy, wide-angle X-ray diffraction, and gas permeation tests. Variations in the d spacing, the formation of pore structures, and changes in the pore sizes of the CMS membranes were discussed in relation to pyrolysis protocols. The uncross-linked polymer membranes showed high CO2 /CH4 selectivity, whereas thermally crosslinked membranes exhibited significantly improved CO2 permeability and excellent CO2 plasticization resistance. The CMS membranes showed even higher CO2 permeability and CO2 /CH4 selectivity. An increase in the pyrolysis temperature resulted in CMS membranes with lower gas permeability but higher selectivity. The 550 °C pyrolyzed CMS membranes showed CO2 permeability as high as 14 750 Barrer with CO2 /CH4 selectivity of approximately 52. Even 800 °C pyrolyzed CMS membranes still showed high CO2 permeability of 2610 Barrer with high CO2 /CH4 selectivity of approximately 118. Both polymer membranes and the CMS membranes are very attractive in aggressive natural gas purification applications.
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 778 Atlantic Drive, Atlanta, GA 30332-0100 (USA).
authors.forename: Wulin
authors.initials: W
authors.lastname: Qiu
authors.forename: Kuang
authors.initials: K
authors.lastname: Zhang
authors.forename: Fuyue Stephanie
authors.initials: FS
authors.lastname: Li
authors.forename: Ke
authors.initials: K
authors.lastname: Zhang
authors.forename: William J
authors.initials: WJ
authors.lastname: Koros
mesh_terms: D062365:Aminobenzoates / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry / Q000302:isolation & purification*; D008567:Membranes, Artificial; D010539:Permeability; D010655:Phenylenediamines / Q000737:chemistry*; D010796:Phthalic Anhydrides / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013696:Temperature; D005465:Fluorocarbon Polymers
chemical_list: D062365:Aminobenzoates; D002244:Carbon; D002245:Carbon Dioxide; D008567:Membranes, Artificial; D010655:Phenylenediamines; D010796:Phthalic Anhydrides; D011108:Polymers; C103195:2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride; D005465:Fluorocarbon Polymers; C017856:3,5-diaminobenzoic acid; C008381:3-phenylenediamine
keywords: carbon molecular sieves; crosslinking; membranes; natural gas separation; polymers