Article abstract
Nature Materials 8, 959 - 965 (2009)
Published online: 20 September 2009 | doi:10.1038/nmat2530
Subject Categories: Catalytic materials | Porous materials | Characterisation and analytical techniques
Morphology-dependent zeolite intergrowth structures leading to distinct internal and outer-surface molecular diffusion barriers
Lukasz Karwacki1,9, Marianne H. F. Kox1,9, D. A. Matthijs de Winter2, Martyn R. Drury3, Johannes D. Meeldijk1, Eli Stavitski1, Wolfgang Schmidt4, Machteld Mertens5, Pablo Cubillas6, Neena John6, Ally Chan7, Norma Kahn7, Simon R. Bare7, Michael Anderson6, Jan Kornatowski4,8 & Bert M. Weckhuysen1
Abstract
Zeolites play a crucial part in acid–base heterogeneous catalysis. Fundamental insight into their internal architecture is of great importance for understanding their structure–function relationships. Here, we report on a new approach correlating confocal fluorescence microscopy with focused ion beam–electron backscatter diffraction, transmission electron microscopy lamelling and diffraction, atomic force microscopy and X-ray photoelectron spectroscopy to study a wide range of coffin-shaped MFI-type zeolite crystals differing in their morphology and chemical composition. This powerful combination demonstrates a unified view on the morphology-dependent MFI-type intergrowth structures and provides evidence for the presence and nature of internal and outer-surface barriers for molecular diffusion. It has been found that internal-surface barriers originate not only from a 90° mismatch in structure and pore alignment but also from small angle differences of 0.5°–2° for particular crystal morphologies. Furthermore, outer-surface barriers seem to be composed of a silicalite outer crust with a thickness varying from 10 to 200 nm.
- Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Faculty of Science, Utrecht University, 3584 CA Utrecht, The Netherlands
- Cellular Architecture and Dynamics, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, 3508 TA Utrecht, The Netherlands
- Max-Planck-Institut für Kohlenforschung, D 45470 Mülheim an der Ruhr, Germany
- ExxonMobil Chemical Europe Inc., Belgian Branch, Hermeslaan 2, 1831 Machelen, Belgium
- Centre for Nanoporous Materials, School of Chemistry, University of Manchester, Manchester M13 9LP, UK
- UOP LLC, a Honeywell Company, 25 East Algonquin Road, Des Plaines, Illinois 60017, USA
- Nicholas Copernicus University, 87-100 Torun, Poland
- These authors contributed equally to this work
Correspondence to: Bert M. Weckhuysen1 e-mail: b.m.weckhuysen@uu.nl
