Zeolite membranes -: state of their development and perspective

An ideal zeolite membrane combines the general advantages of inorganic membranes (temperature stability, solvent resistance) with a perfect shape selectivity. Due to their molecular sieve function, zeolite membranes can principally discriminate the components of gaseous or liquid mixtures dependent on their molecular size. This molecular sieving principle requires a pinhole- and crack-free zeolite membrane. Remarkable separation effects can also be achieved by the interplay of mixture adsorption and mixture diffusion. This review focuses on composite membranes which consist of a zeolite top layer on a mesoporous ceramic or metal support. Special attention is given to supported MFI membranes. (C) 2000 Elsevier Science B.V. All rights reserved.