Fabrication of composite hollow fibers for air separation

Abstract

Abstract By using microporous polyacrylonitrile (PAN) hollow fibers as the substrate, we developed two types of composite fibers for air‐separation. One was a poly(4‐vinyl pyridine) (4‐PVP)/(hexafluoro propane dianhydride)–durene (6FDA)/PAN composite hollow fiber, and the other was a 6FDA–3,5‐diaminobenzonitrile/6FDA–durene/PAN composite hollow fiber. The asymmetric PAN fiber was prepared using dry‐jet wet‐spinning technology, and the deposition of a thin gutter layer of 6FDA–durene on PAN was carried out by prewetting PAN fibers with Fluorinert® before solution coating. The topcoating of a thin layer (200–300 Å) of PVP or 6FDA–3,5‐diaminobenzonitrile on PAN/6FDA–durene fibers was conducted using a conventional solution coating method. The selectivity of 0.7% 4‐PVP/2% 6F–durene/PAN composite fibers for O 2 /N 2 was 5.6 with an O 2 permeance of 32.2 × 10 −6 cc(STP)/cm 2 s cmHg, whereas the selectivity of 0.5% 6FDA–3,5‐diaminobenzonitrile/2% 6F–durene/PAN fibers was 5.1 with an O 2 permeance greater than 37.2 × 10 −6 cc(STP)/cm 2 s cmHg. Both fiber selectivities can be further improved by increasing the thicknesses of the selective layer. © 1994 John Wiley & Sons, Inc.