Stacking disorders in zeolites and open-frameworks – structure elucidation and analysis by electron crystallography and X-ray diffraction

Abstract

Abstract. Intergrowth and stacking disorders are often found in minerals and synthetic zeolites and inorganic openframeworks. Structure elucidation of stacking disorders in these materials have been difficult and structure solution of stacking disorders in unknown zeolites and open-frameworks has been challenging. There exist no standard methods for structure analysis of such disordered materials. In this review we present various stacking disorders and intergrowth in a number of representative zeolite families containing stacking disorders. These include zeolite beta, SSZ-26/SSZ-33, ITQ-39, ABC-6, ZSM-48, SSZ-31, UTD-1, faujasite FAU/EMT, pentasil ZSM-5/ZSM-11, ITQ-13/ITQ-34, ITQ-22/ITQ-38 etc. Stacking disorders in open-frameworks containing mixed coordinations, including titanosilicates ETS-10 and ETS-4, and the silicogermanate SU-JU-14 are also described. Various crystallographic methods used for solving disordered structures are summarized. The methods include powder X-ray diffraction (PXRD), electron diffraction, high resolution transmission electron microscopy (HRTEM), and single-crystal X-ray diffraction. Examples of model building combined with simulations of PXRD and single crystal X-ray diffraction to verify the structure models are given.

Polytype distributions in low-defect zeolite beta crystals synthesized without an organic structure-directing agent

“…2a), consistent with the crystals containing roughly equal proportions of BEA and BEB polytypes. 19,26 After complete dehydration, the intensity of this peak decreases in comparison to the higher angle peaks as the strongly X-ray absorbing adsorbed H 2 O is lost (Fig. 2b).…”

Genetic engineering of inorganic functional modular materials

“… 45 – 51 Many zeolite structures can be described by the stacking of layer modules. 52 – 56 In the days when computers were not popular, many unknown zeolite structures were predicted by manipulating the stacking of several of the most frequently observed layer modules. 57 – 61 On the other hand, synthetic chemists recently discovered that new zeolite structures, even those deemed “unfeasible” according to conventional evaluation criteria, could be realised by controlling the assembly, disassembly, and reassembly of some known layer modules of zeolites.…”

Structure Determination of Zeolites by Electron Crystallography

“…Knowing the various types of stacking disorders in zeolites and the characteristic features in the corresponding diffraction patterns is therefore important for solving unknown zeolites containing stacking disorders. A recent review by us summarized the structure elucidation and analysis of stacking disorders in zeolites and open frameworks by electron crystallography and X-ray diffraction [103]. Zeolite beta has a heavily faulted structure which inhibited structure determination of the material for more than 20 years.…”