The morphology and structure of intercalated and pillared clays
Duong, Loc V. (2008) The morphology and structure of intercalated and pillared clays. PhD thesis, Queensland University of Technology.
This thesis is submitted in a format of published papers by the candidate. Advanced methods of electron microscopy and X-ray spectroscopy have been used to study the relationship between the pillars and the silicate structure ranging from Al13 and Ga13 complexes to the final products Al- and Ga-pillared clays. The Al13 and Ga13 pillared montmorillonites have been prepared by conventional and ultrasonic methods. The ultrasonic method has been proven to be effective and showed very good catalytically activity. Transmission electron microscopy combined with elemental mapping by EDS showed the distribution of the Ga and Al pillars in the clay structure. The use of gallium allowed the independent observation of the Ga pillar distribution from the Al distribution in the clay structure.
XPS spectra of the Ga13 pillared montmorillonites showed that the pillars has been changed from the original Keggin structure with a 7+ charge to something more stable with a lower charge upon intercalation. No direct evidence of the inverted silicon tetrahedron structure bonding to the pillar structure, as suggested by Plee in his original thesis, was observed. For comparative reasons the major aluminium hydroxide minerals in bauxite (gibbsite, bayerite and (pseudo-) boehmite) were studied.
Detailed information about the Al13 structure was obtained by studying the basic sulphate and nitrate salts with XPS. The XPS results of a set of starting clays in comparison to the pillared clays indicated that small changes in the binding energy could explain the changes in the pillar structure and the formation of chemical bonds to the clay tetrahedral sheets during the calcination leading to the final products.
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|Item Type:||QUT Thesis (PhD)|
|Supervisor:||Kloprogge, Jacob& Frost, Raymond|
|Keywords:||Intercalated clays, Pillared clays, morphology and structure|
|Divisions:||Past > QUT Faculties & Divisions > Faculty of Science and Technology|
Past > Schools > School of Physical & Chemical Sciences
|Institution:||Queensland University of Technology|
|Deposited On:||11 Feb 2009 11:38|
|Last Modified:||29 Oct 2011 05:51|
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