Growth of ZSM-5 films on alumina and other surfaces

Growth of ZSM-5 films on porous alpha-Al2O3 and other substrates was studied with the main focus on the effect of the substrate on surface gel formation and zeolitization. The films formed on the substrate and the powders that settled at the bottom of the autoclave were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Adsorption of Ar and iso-butane was used to estimate the crystalline fraction of the product formed on and in the pores of the substrate. The presence of alumina substrates accelerated bulk zeolitization for certain solution compositions. Aluminum added to the solution had dual effects, to induce gel layer formation on the substrate surface and to retard zeolitization of that layer as well as retard zeolitization in the bulk of the solution. (C) 2000 Elsevier Science B.V. All rights reserved.