Evidence for semi-regularly ordered sequences of mirror and inversion symmetry planes in ZSM-5/ZSM-11 shape-selective zeolitic catalysts

Abstract

The combined use of high-resolution electron microscopic imaging, electron diffraction, optical diffraction and computer graphics for characterizing intergrowth structures of ZSM-5 and ZSM-11 is described. In particular, a specific preparation is shown to consist mainly of the ZSM-5 framework structure but with single insertions of strips of ZSM-11 at an average spacing of ca. 66 Å along [100]. Evidence is also presented for the occurrence of an intergrowth in which one slab of ZSM-5 is related to an adjoining slab such that one of these is rotated through 90° around a [001] axis. An idealized atomic model for this intergrowth is proposed.