Abstract: High performance cellulose acetate butyrate gas separation membranes are prepared from a casting solution containing from about 10 to 30 percent polymer, 35 to 70 percent solvent, and 15 to 30 percent pore-forming agents. A film casting solution is cast onto a substantially flat support surface and a dense layer is formed on the exposed film surface. The film is gelled, washed, and dried to produce a particularly useful gas separation membrane. The cellulose acetate polymers used in this preparation have molecular weights of at least about 20,000, and have about 10 to about 45% butyryl groups, about 2 to about 35% acetyl groups, and about 0.8 to about 2 percent hydroxyl groups, by weight. The membranes may be used for separating a feed gas into a permeate fraction and a residual fraction, and are particularly useful for separating gases in the purge gas stream of ammonia plants to recover a permeate which is relatively rich in hydrogen.

Abstract: An asymmetric membrane and a method for its preparation is disclosed. The membrane is suitable for gas separation, reverse osmosis and pervaporation applications and is characterized in that it is based on a fully imidized 5(6)-amino-1-(4'-aminophenyl)-1,3-trimethylindane polymer having pore diameters of less than 20 .ANG. units, CO.sub.2 /CH.sub.4 selectivity of at least 20 and CO.sub.2 permeability of at least 1.0 SCFH/ft.sup.2 at 100 p.s.i.

Abstract: An improved method is disclosed for coupling membrane elements of a fluid separation module in series. The improvement comprises providing flexible coupling members having two open ends and a passage between said ends; and securing the first end of a coupling member to the residual end of each membrane element (with the optional exception of the last in the series) and securing the second end of the coupling member to the feed end of the next membrane element in the series if any. Fluid from the residual end of each membrane element except the last may thus be directed to the feed end of the next membrane element. An improved fluid separation module employing such couplings is disclosed; as is an improved membrane element having a coupling member secured thereto.

Abstract: A cellulose acetate membrane is provided, capable of separating gaseous hydrogen from a gaseous mixture of hydrogen and hydrocarbon, by casting a 0.02 to 0.05 cm cellulose acetate film into an atmosphere at 20.degree. to 40.degree. C. and a relative humidity of 30 to 70%, from a casting solution at 0.degree. to 20.degree. C. and comprising 10 to 20 wt % cellulose acetate, 60 to 80 wt % acetone, 0.5 to 0.2 wt % magnesium perchlorate, balance water, then evaporating the solvent to form a membrane from the film, then gelling the membrane in ice cold water, then shrinking the membrane at 60.degree. to 90.degree. C. to produce a water wet membrane having an average pore radius less than 7 .ANG., then replacing the water in the membrane sequentially at the laboratory temperature (about 20.degree. to 25.degree. C.