Intergrowth structure of zeolite crystals and pore orientation of individual subunits revealed by electron backscatter diffraction /focused ion beam experiments

Zeolites are of tremendous scientific and technological importance, since a number of processes in modern chemical industry, such as crude oil refining, rely on their unique combination of catalytic activity and shape selectivity.[1–3] Consequently, significant efforts have been directed at obtaining in-depth insight into the molecular processes taking place within zeolite pores during catalysis.[4–6] A popular strategy is to investigate large zeolite crystallites, which are well-defined, ordered, and reproducible and can be used as model systems for diffusion and catalysis studies.[7–15] However, this taskis complicated by the complex structure of zeolite crystals comprising several intergrown building blocks. The interfaces of these subunits may constitute diffusion boundaries due to potential mismatch in the alignment of the microporous network,[16] and this can render certain regions of the zeolite crystals inaccessible for reactant molecules and consequently affect the catalytic activity of the material.[8, 10, 17]