Degree Type

Dissertation

Date of Award

2005

Degree Name

Doctor of Philosophy

Department

Chemical and Biological Engineering

First Advisor

Brent H. Shanks

Abstract

In the work, mesoporous aluminas were produced by nonionic supramolecular templating and characterized to determine the stability of their physical structure during extended calcination at elevated temperatures. The effect of synthesis temperature on the physical structure of these materials and the resulting thermal evolution from synthesized aluminum hydroxide to transitional alumina was studied using thermogravimetric analysis. A high resolution multiple quantum magic angle spinning NMR spectroscopy method was used to determine quantitatively the evolution of the aluminum coordination during the thermal processing. The mesoporous alumina exhibited high stability upon prolonged heating, which is essential for their future applications in catalytic chemistry.;Using surfactant-mediated synthesis, aluminas with hierarchical nanopores were produced. The structures were found to be stable to the thermal removal of the surfactant. Synthesis factors affecting the morphology of hierarchically structured alumina material were discussed and a parameter space in which macropores could be obtained was determined. Based on the results from a parameter study and the similarity of the process to the macropore formation on anodized aluminum surface, a mechanism in which the interaction of water and aluminum alkoxide droplet played a important role was proposed to explain the structural organization for the material at multiple length scales.

DOI

https://doi.org/10.31274/rtd-180813-8755

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu

Copyright Owner

Weihua Deng

Language

en

Proquest ID

AAI3172207

File Format

application/pdf

File Size

115 pages

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