Preparation and Morphology of Pyramidal MFI Single-Crystal Segments

Single-crystal segments of tetra-n-propylammonium-templated Silicalite-1 and ZSM-5 were prepared by
postsynthetic treatment of twinned MFI prisms. Microwave irradiation of the parent crystallites in alkaline
solution containing hydrogen peroxide, followed by ultrasound treatment, led to disintegration of the zeolite
prisms. The resulting wedge-shaped crystal segments proved to be single crystals of excellent crystallinity as
shown by optical and X-ray investigations. The hydroxyl ions, compensating the positive charges of the
tetrapropylammonium cations, were located by single-crystal structure refinement in template-containing
Silicalite-1 and ZSM-5 but absent from the calcined samples.