Preparation of zeolite A and faujasite membranes from a clear solution

Zeolite A and faujasite- (FAU-)type zeolite membranes were prepared under identical conditions from solutions of the same composition, with the only difference being the seed crystal used. The zeolite A membrane was formed on a substrate seeded with zeolite A crystals, while the FAU membrane was formed with zeolite Y seeds. The induction period of clear solution was used to prevent the influence of precipitated crystals that will eventually form in the clear solution and to keep the composition of the synthesis solution constant. Zeolite crystals increased in size with synthesis time and formed a continuous membrane on a porous substrate. Selectivity in a liquid mixture separation by pervaporation increased as crystals grew, indicating a decrease in intercrystalline region size.