Preparation of silicalite-1 and ZSM-5 zeolite/ceramic composite membranes

Silicalite-1 and ZSM-5 zeolite/ceramic composite membranes were made by in-situ synthesis. It was found that the sol prepared for zeolite synthesis exerted major influence on the successful preparation of the composite membranes and the thickness of the zeolite layer. Repeated syntheses were needed to prepare a gas-tight as-synthesized zeolite membrane. Less synthesis times were needed to prepare a good composite membrane on a dry substrate than on a wet one. Furthermore, the gas permeation experiments show that pure gas permeance of the membranes decreased with the increase of the kinetic diameters of the gases, indicating that the main pores in the membrane were zeolite pores.