The role of symmetry in building up zeolite frameworks from layered zeolite precursors having ferrierite and CAS layers

Abstract

Layered zeolite precursors represent an emerging class of materials that expand the zeolite field in a new direction and have already produced new intriguing discoveries. One is a new fundamental insight that a zeolite framework can assemble by two pathways, directly in 3-D and via a layered precursor. Also new types of materials such as pillared and delaminated zeolites have been synthesized. Starting with the discovery of MCM-22 precursor in 1990s, other framework structures have now been obtained by topotactic condensation, including classical zeolites such as sodalite and ferrierite. The recent structural diversity observed with FER and CAS layers, which were found to produce two frameworks each, i.e. FER/CDO and CAS/NSI, respectively, are herein rationalized as resulting from the absence of in-plane mirror symmetry. A systematic treatment is envisioned, such as consideration of translational and pseudo-translational interactions in condensation of elementary shapes into close-packed assemblies, providing a blueprint for a general approach to analyze new precursors in the future. Other already documented instances of structural diversity include the presence of both types of packing in one preparation (CAS and NSI) and incomplete pairing of silanols connecting FER layers in ESR-12.

Two-Dimensional Zeolite Materials: Structural and Acidity Properties

“…Due to its close structural relationship with CDO zeolite, the FER framework topology has been identified in a number of 2D layered precursors (Table 4 and 2D layer precursors of CDO in Table 2). The differences between the crystal structure among these related 2D FER precursors result from the stacking sequence of FER layers, i.e., the displacement of layers parallel to the a-b plane and/or interlayer distance [136], which is the consequence of incorporating different templates in syntheses. Among these FER precursors, the most prominent ones are PREFER, PLS-3, ICP (Instituto de Catálisis y Petroleoquímica)-2 and ERS (EniRicerche molecular Sieve)-12 (Table 4).…”

The ADOR synthesis of new zeolites: In silico investigation

“…In the organization phase the lamellae could be arranged in many ways -different relative positions of lamellae can lead to topologically different zeolites or disordered products. Although preparation of multiple zeolites by lamellae rearrangements was not achieved by ADOR yet, this possibility can be illustrated on the FER and CDO zeolites formed by different arrangements of the same lamellae [7]. After rearrangement the FER-type material was prepared from CDO precursor RUB-36 [8], however, a combination of swelling and deswelling and the use of a suitable SDA was necessary.…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 21, 2010) and the discipline

“…In the paper by Roth and Dorset [107], it is shown that the symmetry principles may govern and rationalize formation of different zeolite frameworks from corresponding layered zeolite precursors. Despite their seeming complexity as defined by the large number of atoms per formula unit, enthalpies of formation of zeolites are encouragingly wellunderstood [108].…”