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Synthesis and characterization of pure silica zeolite beta obtained by an aging-drying method
Univ Antioquia, SIU, Environm Catalysis Res Grp, Medellin, Colombia.
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
Univ Antioquia, SIU, Environm Catalysis Res Grp, Medellin, Colombia.
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2011 (English)In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 143, no 1, 196-205 p.Article in journal (Refereed) Published
Abstract [en]

Pure silica zeolite beta materials were synthesized by an unconventional method of aging and drying the starting gels at room temperature followed by the conventional hydrothermal treatment. In addition, organic solvents were added to selected samples as complementary structure directing agents (SDA). The influence of the aging-drying method, complementary SDA addition and crystallization time upon the synthesis of pure silica zeolite beta were studied. Samples were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), thermogravimetric analyses (TGA) and nitrogen adsorption. Results revealed that the aging-drying process increased crystallization rate, produced crystals with unique morphology and scaled-surface and allowed polymorph A enrichments to about 68-70%. It was also found that addition of organic solvents during the thermal treatment tunes the crystal morphology but, does not affect the polymorphic enrichment.

Place, publisher, year, edition, pages
2011. Vol. 143, no 1, 196-205 p.
Keyword [en]
Al-Si-beta, Ti-Si-beta, Aging-drying method, Polymorphic enrichment, Fluoride medium
National Category
Chemical Sciences Physical Chemistry Materials Chemistry
Identifiers
URN: urn:nbn:se:su:diva-68900DOI: 10.1016/j.micromeso.2011.02.030ISI: 000291524700026OAI: oai:DiVA.org:su-68900DiVA: diva2:474039
Note
5Available from: 2012-01-09 Created: 2012-01-09 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Structural study of zeolites utilizing novel electron crystallographic methods: A voyage into the world of zeolite structures
Open this publication in new window or tab >>Structural study of zeolites utilizing novel electron crystallographic methods: A voyage into the world of zeolite structures
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electron crystallography has evolved as a powerful method for structural characterization of a wide range of materials. It has two significant advantages over other methods for structure determination, e.g. X-ray diffraction. Electrons interact much more strongly with matter compared to X-rays and they can be focused by electromagnetic lenses to form images with atomic resolution. These advantages make electron crystallography a unique tool for characterization of crystalline materials suffering from small crystal size and complex or disordered structures.

     Zeolites are a class of microporous materials with significance in several applications. They often possess complex and disordered structures, which demand large efforts in the structure determination.

     Over the last years, two new electron crystallographic methods have been developed; the rotation electron diffraction (RED) and the structure projection reconstruction from a through-focus series of high resolution transmission electron microscopy (HRTEM) images. In this thesis, they will be applied for structure determination of four new zeolite structures, including EMM-25 and EMM-23 with two ordered structures, and ITQ-39 and ITQ-38 with disordered structures. Each of the structure solutions have different challenges to overcome. The high silica borosilicate EMM-25 was solved by the RED method. The aluminosilicate EMM-23 was solved by a combination of HRTEM and RED. The structure solution of two materials with disordered structures, ITQ-39 and ITQ-38, will be described. For materials containing disorders, structure projection images are of utmost importance.

     Furthermore, the mesoporosity inside hierarchically porous ZSM-5 crystals was studied by a combination of focused ion beam (FIB) and HRTEM imaging. The last part of this thesis explores STEM imaging for use in structure determination from 3D reconstruction.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University, 2013. 104 p.
Keyword
Electron crystallography, zeolites, structure determination, disorder, electron microscopy
National Category
Inorganic Chemistry
Research subject
Structural Chemistry
Identifiers
urn:nbn:se:su:diva-95870 (URN)978-91-7447-810-5 (ISBN)
Public defence
2013-12-16, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defence the following papers were unpublished and had a status as follows: Papers 4 and 5: Manuscipts; Paper 10: Manuscript

Available from: 2013-11-24 Created: 2013-11-05 Last updated: 2013-11-26Bibliographically approved

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