Kernforschungszentrum Karlsruhe Gmbh

Gkss-forschungszentrum Geesthacht Gmbh

Ingo Pinnau

Jan Wind

Klaus V Peinemann

A method for producing an improved membrane for separating gases in mixtures including forming an integral, asymmetric polyether imide membrane, treating the membrane with at least one organic fluid which is a solvent or swelling agent for polyether imide, and removing the organic fluid from the membrane by evaporation to obtain a tubular, flat or hollow fiber membrane exhibiting significantly higher selectivity than an untreated membrane.

Process for increasing the selectivity of asymmetric membranes

A method of manufacturing an integral asymmetric membrane for separating gases from each other, wherewith a membrane-former, a solvent, and/or an agent which is not a solvent for the membrane-former are mixed, are spread out or otherwise extended over a greater area, and are contacted with a precipitation agent. The integral asymmetric membrane for gas separation is particularly suitable for CO.sub.2 /CH.sub.4 separation, has improved insensitivity to water and relatively high strength and durability, and has high separation throughput and selectivity (permeability of .gtoreq.=0.1 cu m/sq m/hr/bar for CO.sub.2, and CO.sub.2 /CH.sub.4 selectivity of about 30-40), which high separation throughput and selectivity are necessary for economical separation of materials. The integral asymmetric membrane is made from a polymer, particularly polyether sulfone, as a membrane-former, is mixed with a halogenated hydrocarbon, as a solvent, as well as with a non-solvent in the form of an aliphatic alcohol, which non-solvent may possibly comprise, in addition to the aliphatic alcohol, an aliphatic carboxylic acid or an alkylbenzene.

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Hamburg, Germany

Ingo Pinnau