New zeolite-like RUB-5 and its related hydrous layer silicate RUB-6 structurally characterized by electron microscopy

• Main Authors: Yaşar Krysiak, Bernd Marler, Bastian Barton, Sergi Plana-Ruiz, Hermann Gies, Reinhard B. Neder, Ute Kolb
• Format: Article
• Language: English
• Published: International Union of Crystallography 2020-05-01
• Series: IUCrJ
• Subjects: 3d electron diffraction; exit wave reconstruction; diffuse scattering; stacking faults; electron crystallography; framework-structured solids; microporous materials; polymorph prediction; computational modelling; inorganic materials
• Online Access: http://scripts.iucr.org/cgi-bin/paper?S2052252520003991

This study made use of a recently developed combination of advanced methods to reveal the atomic structure of a disordered nanocrystalline zeolite using exit wave reconstruction, automated diffraction tomography, disorder modelling and diffraction pattern simulation. By applying these methods, it was possible to determine the so far unknown structures of the hydrous layer silicate RUB-6 and the related zeolite-like material RUB-5. The structures of RUB-5 and RUB-6 contain the same dense layer-like building units (LLBUs). In the case of RUB-5, these building units are interconnected via additional SiO4/2 tetrahedra, giving rise to a framework structure with a 2D pore system consisting of intersecting 8-ring channels. In contrast, RUB-6 contains these LLBUs as separate silicate layers terminated by silanol/siloxy groups. Both RUB-6 and RUB-5 show stacking disorder with intergrowths of different polymorphs. The unique structure of RUB-6, together with the possibility for an interlayer expansion reaction to form RUB-5, make it a promising candidate for interlayer expansion with various metal sources to include catalytically active reaction centres.