Simultaneous improvement of permeance and permselectivity of 3,3{prime},4,4{prime}-biphenyltetracarboxylic dianhydride-4,4{prime}-oxydianiline polyimide membrane by carbonization
- Kyushu Univ., Fukuoka (Japan). Dept. of Chemical Science and Technology
A BPDA-ODA polyimide film was formed on the outer surface of a porous alumina support tube (outside diameter, 2.4 mm; inside diameter, 1.8 mm; void fraction, 0.48; average pore size, 140 nm). It was imidized and then carbonized at 500--900 C. Defects usually generated during carbonization were completely avoided by optimizing temperature profiles. Carbonization above 600 C remarkably increased the permeance of He, CO{sub 2}, CH{sub 4}, N{sub 2}, and C{sub 2}H{sub 6} without losing the high permselectivity of the polyimide. The ultimate micropore volume determined by CO{sub 2} sorption was also increased to 0.36 {times} 10{sup {minus}3} from 0.16 {times} 10{sup {minus}3} m{sup 3}/kg. However, the micropore volume was not a dominant factor. The increase in permeance, which was mainly controlled by effective diffusivity of permeating species in the membrane, was dependent on pore-size distribution. The CO{sub 2} permeance and CO{sub 2}/CH{sub 4} permselectivity of the carbonized membrane were 10{sup {minus}7} mol/m{sup 2} s{sup 1} Pa and 100, respectively, at 30 C.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 183093
- Journal Information:
- Industrial and Engineering Chemistry Research, Vol. 34, Issue 12; Other Information: PBD: Dec 1995
- Country of Publication:
- United States
- Language:
- English
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