ZSM-5 FILMS PREPARED FROM TEMPLATE FREE PRECURSORS

Thin continuous films of zeolite ZSM-5 were synthesized on quartz subs trates. The substrates were first surface modified and covered by a mo nolayer of colloidal silicalite-1 seed crystals. These crystals were g rown into continuous films with thicknesses in the range 230-3500 nm b y hydrothermal treatment in a synthesis gel free from organic template s. The preferential orientation of the crystals constituting the film was initially one with the c-axis close to parallel to the substrate s urface. During the course of crystallization this orientation changed to one with most of the crystals having the c-axes directed approximat ely 35 degrees from perpendicular to the substrate surface; A mechanis m explaining this behavior is proposed. The final thickness of the fil m was controlled by the synthesis time but also by the addition of see d crystals to the synthesis gel. Films prepared according to this meth od may be of great value for the development of zeolite based membrane s.