| 摘要 |
Non-porous polymeric membranes 1-32 microns thick coated on porous glass or polymeric tubes are used to separate mixtures of gases and liquids by diffusion. Preferred embodiments use a plurality of capillary tubes mounted in apparatus as in Specification 1,019,881 and in C. J. Walters, Petroleum Refiner, May 1959, pages 147-150. Porous glass capillaries are obtained by vitrification by heating followed by acid leaching while porous polymer capillaries may be made by a variety of processes including melt and solution extrusion, followed by removal of the solvent, the extrudate containing e.g. a plasticizer, diluent, or inorganic solvent which may afterwards by leached away, or they may be obtained by sintering processes. Preferred capillaries are 20-250 microns in outside diameter. The membrane may be applied to either the inside or outside surface of the tube and may e.g. by applied by continuous coating of a capillary as it is drawn, by application of a very dilute solution to a prepared capillary, or by in situ polymerization or precipitation. In examples cellulose acetate is applied to porous glass as a 5% solution in acetone, and a polymeric phosphine oxide prepared from isoprene and dichlorophosphine according to U.S.A. Specification 2,671,080 as a solution in methanol. Other specified polymers include regenerated cellulose, cellulose acetate, polyethyleneterephthalate, polystyrene, PVC, polyvinylidene chloride, nylon 66, polyvinylpyrrolidone, polyvinyl alcohol, and copolymers of ethylene, propylene, vinylidene fluoride and hexafluoropropylene. |
