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Development of electron microscopy towards nano-structured porous materials: Focus on novel zeolites from layered silicates and chiral mesoporous nanotubes
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Three novel zeolites (M-IEZ-MWW, IEZ-FER and IEZ-CDO) have been successfully synthesised from the corresponding precursors. Structure characterisation of those materials was conducted by TEM. Our studies show that the structure of the new zeolites keeps identical layer to the corresponding known 3D zeolite, except for the distinct expansion of the layer spacing. Combining with results from XRD, N2 adsorption, IR and NMR, the expansion can be explained by the pillaring of T sites between the layers. Meanwhile, the intergrowth of 3D MWW and IEZ-MWW was observed in the Al-IEZ-MWW and Si-IEZ-MWW crystals, IEZ-CDO structure was found in the IEZ-FER crystals, and the intergrowth of CDO and new polymorph was observed in the CDS-1 crystal. Moreover, two new zeolites IM-5 and SSZ-57 were also studied by TEM. We found that the space group of IM-5 is non-centrosymmetrical, and in SSZ-57 the new structure with slightly larger c parameter was observed compared to MEL.

Chiral mesoporous silica nanotube and chiral mesoporous carbon nanotube were aslo investigated by TEM. We found that the former was synthesised by hollowing out process and it possesses chiral mesopores in the wall, the latter was synthesised by templating and seeding method. Electron tomography was first applied to study the handedness of the chiral mesoporous nanotube. Furthermore, TEM studies verified that bifunctional mesoporous silica has a Fm-3m structure, and mesoporous carbon FDU-16 has a Im-3m structure.

Place, publisher, year, edition, pages
Stockholm: Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi , 2008. , 125 p.
Keyword [en]
Transmission electron microscopy, Layered silicates, Chiral mesoporous nanotubes
Research subject
Structural Chemistry
Identifiers
URN: urn:nbn:se:su:diva-7439ISBN: 978-91-7155-602-8 (print)OAI: oai:DiVA.org:su-7439DiVA: diva2:198287
Public defence
2008-04-25, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 13:30 (English)
Opponent
Supervisors
Available from: 2008-04-03 Created: 2008-03-28 Last updated: 2010-04-14Bibliographically approved
List of papers
1. Delamination of Ti-MWW and high efficiency in epoxidation of alkenes with various molecular sizes
Open this publication in new window or tab >>Delamination of Ti-MWW and high efficiency in epoxidation of alkenes with various molecular sizes
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2004 In: Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 108, no 50, 19126-19131 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-24770 (URN)
Note
Part of urn:nbn:se:su:diva-7439Available from: 2008-04-03 Created: 2008-03-28Bibliographically approved
2. Structural elucidation of the highly active titanosilicate catalyst Ti-YNU-1
Open this publication in new window or tab >>Structural elucidation of the highly active titanosilicate catalyst Ti-YNU-1
2005 In: Angewandte Chemie (International ed.), ISSN 1433-7851, Vol. 44, no 41, 6719-6723 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-24771 (URN)
Note
Part of urn:nbn:se:su:diva-7439Available from: 2008-04-03 Created: 2008-03-28Bibliographically approved
3. A Novel Route for Synthesizing Silica Nanotubes with Chiral Mesoporous Wall Structures
Open this publication in new window or tab >>A Novel Route for Synthesizing Silica Nanotubes with Chiral Mesoporous Wall Structures
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2007 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 19, no 7, 1577-1583 p.Article in journal (Refereed) Published
Abstract [en]

Right- and left-handed excess chiral mesoporous silica nanotubes with a helical channel in the wall have been formed by the self-assembly of an achiral surfactant sodium dodecyl sulfate (SDS) in the presence of (R)-(+)- and (S)-(-)- 2-amino-3-phenyl-1-propanol ((R)-(+)- and (S)-(-)-APP) chiral molecules. Transmission electron microscopy combined with computer simulations confirmed the presence of ordered chiral channels winding around the central axis of the tubes of similar to 100 nm inner diameter. Furthermore, it has been found that these have been produced through a specific crystallization route that hollows out the chiral mesoporous silica rod, which is different from the tube synthesis pathways reported previously. The enantiomeric excess ee of chiral mesoporous silica has been increased from 0 to a maximum value of 32% with increasing (R)-(+)-APP/SDS molar ratios from 0 to 0.8.

Keyword
SOL-GEL TRANSCRIPTION; HELICAL SILICA; INTERNAL STRUCTURE; ORGANOGEL FIBERS; TUBULES; SURFACTANT; CREATION; SYSTEM; ARCHITECTURE; FABRICATION
National Category
Natural Sciences
Identifiers
urn:nbn:se:su:diva-24772 (URN)000245208100010 ()
Available from: 2008-04-03 Created: 2008-03-28 Last updated: 2011-09-09Bibliographically approved
4. Synthesis and Characterization of the Amphoteric Amino Acid Bifunctional Mesoporous Silica
Open this publication in new window or tab >>Synthesis and Characterization of the Amphoteric Amino Acid Bifunctional Mesoporous Silica
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2007 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 19, no 11, 2860-2867 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-19813 (URN)10.1021/cm0705845 (DOI)000246645100025 ()
Available from: 2007-11-28 Created: 2007-11-28 Last updated: 2010-04-14Bibliographically approved
5. Formation of chiral mesopores in conducting polymers by chiral lipid ribbon templating and “seeding” route
Open this publication in new window or tab >>Formation of chiral mesopores in conducting polymers by chiral lipid ribbon templating and “seeding” route
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2008 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 18, no 18, 2699-2707 p.Article in journal (Refereed) Published
Abstract [en]

Conducting polymer nanofibers with controllable chiral mesopores in the size, the shape, and handedness have been synthesized by chiral lipid ribbon templating and “seeding” route. Chiral mesoporous conducting poly(pyrrole) (CMPP) synthesized with very small amount of chiral amphiphilic molecules (usually < 3%) has helically twisted channels with well-defined controllable pore size of 5–20 nm in central axis of the twisted fibers. The structure and chirality of helical mesopores have been characterized by high-resolution transmission electron microscope (HRTEM), scanning electron microscope (SEM) and electron tomography. The average pore diameters of chiral mesopores were approximately estimated from the N2 adsorption–desorption data and calculated by the conversion calculation from helical ribbons to a rectangular straight tape. The pore size of CMPP has been controlled by choosing different alkyl chain lengths of chiral lipid molecules or precisely adjusting the H2O/EtOH volume ratio.

National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:su:diva-24774 (URN)10.1002/adfm.200701456 (DOI)000259933000007 ()
Available from: 2008-04-03 Created: 2008-03-28 Last updated: 2012-08-09Bibliographically approved
6. A novel methodology for synthesizing crystalline metallosilicates with expanded pore windows through molecular alkoxysilylation of zeolitic lamellar precursor
Open this publication in new window or tab >>A novel methodology for synthesizing crystalline metallosilicates with expanded pore windows through molecular alkoxysilylation of zeolitic lamellar precursor
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2008 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 130, no 26, 8178-8187 p.Article in journal (Refereed) Published
Abstract [en]

Postalkoxysilylation with diethoxydimethylsilane has been carried out on the zeolitic lamellar precursors of various topologies such as MWW, FER, CDO and MCM-47 aiming to construct new crystalline structures with expanded pore apertures between the layers. The silylation process and the crystalline and pore structures of the resulting materials have been investigated with the techniques of XRD, IR, 13C and 29Si MAS NMR, ICP, SEM, HRTEM, elemental analyses, and N2 adsorption. In contrast to forming known three-dimensional zeolite structures after direct calcination of the lamellar precursors, the silylation led to new crystalline structures with opener pores, as evidenced by the shift of layer-related diffractions to the lower-angle region in XRD patterns and the enlarged interlayer pores found by HRTEM images. After optimizing the treatment conditions, particularly the amount of silane agent, a maximum and homogeneous silylation was realized, which guaranteed the phase purity in interlayer expanded zeolites. The expanded structures were well preserved after calcination at 823 K or reflux in water for 1 to 2 weeks, indicating a high thermal stability and also a hydrothermal stability. The interlayer expanded zeolites prepared from the metallosilicate precursors of MWW topology exhibited higher catalytic activities in the redox and solid acid-catalyzed reactions of bulky molecules than that of their counterparts with conventional MWW topology.

Place, publisher, year, edition, pages
American Chemical Society, 2008
National Category
Chemical Sciences
Identifiers
urn:nbn:se:su:diva-24775 (URN)10.1021/ja0758739 (DOI)000257152800033 ()
Note
Part of urn:nbn:se:su:diva-7439Available from: 2008-04-03 Created: 2008-03-28 Last updated: 2010-12-01Bibliographically approved

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