Abstract

Oriented zeolite MFI films were synthesized by solid-state transformation using tetrapropylammonium hydroxide (TPAOH) as a template and a silica–alumina sol as a silica–alumina source. Three factors in the preparation processes were found to be the keys to obtaining an oriented MFI film: the stirring time after adding TPAOH to a silica–alumina sol solution, the drying temperature of the coated film and the heating temperature of the dried film in an autoclave. XRD patterns of the films showed only reflections ascribed to (0k0) faces, indicating that the films were oriented. SEM analysis of the films in the drying and heating processes showed that oriented crystals were grown in two stages. In the first stage, oriented MFI crystals grew to an average size of 1.4 µm, which was the same as the size of the gel particles in the dried film; after interruption of growth for 2 h, oriented crystals grew again in the second stage to a size of 3.0 µm.