Abstract: This invention relates to a novel composition useful for preparing a semi-permeable cellulose ester gas separation membrane, which composition includes a mixture of a cellulose ester, a solvent selected from the group consisting essentially of glycerol acetate, glycerol diacetate, glycerol triacetate, and mixtures thereof, and optionally the non-solvent glycerol. This invention also relates to a process of fabricating a cellulose ester gas separation membrane from said composition.

Abstract: The invention is a process for separating hydrogen from gas mixtures using a semi-permeable membrane consisting predominantly of polycarbonates derived from tetrahalobisphenols such as tetrabromobisphenol.

Abstract: An improved process for drying water-wet, cellulose ester membranes is described. It has been found that by contacting one side of the membrane with a liquid mixture of a water-miscible, volatile C.sub.1 to C.sub.6 hydrocarbon and a water-immiscible organic compound, while an inert gas stream or vacuum is maintained on the other surface of the membrane, water can be displaced from the membrane economically, rapidly and without adversely affecting the structure of the membrane. A 1 to 1 volume mixture of isopropanol and isooctane is particularly preferred in this step. The essentially water-free membrane is then dried by applying reduced pressure or an inert gas stream to produce a membrane having exceptional separation characteristics.