Synthesis of ZSM-5 films at elevated gravity

Abstract

ZSM-5 zeolite films, with a thickness from 100 to 1,000 μm, have been synthesized in a colloidal silica-TPABr gel system without a support and under elevated gravity (16 G). Under high gravity, the films obtained were completely crystallized and were stronger than those produced under normal gravity. Parameters that influence the film crystallization process such as water content(H 2 O/SiO 2 ratio), alumina to silica ratio, and the reaction gel alkalinity were investigated. The optimum value of the water content was found to be approximately 33 in the synthesis of these films. The film growth became difficult with increasing aluminum content in the reaction mixture. The alkalinity of the reaction gel had to be increased at a higher aluminum content to form a continuous film. The alkalinity of the synthesis mixture was also used to control the thickness of the film. In zeolite film formation, the effect of providing seeds in the reaction mixture was also investigated. The thickness of the resulting films varied with the configuration of seeds used. In addition, thick zeolite films were produced when a vycor glass plate treated by a leaching and an unconsolidating process was used as a support.