Thesis (Ph.D.)--Aberdeen University, 1989. / Title from web page (viewed on Mar. 4, 2010). Includes bibliographical references.

Thesis (Ph.D.) - University of St Andrews, June 2009. / Restricted until 5th June 2011.

Thesis (Ph. D.)--Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2007. / Teja, Amyn, Committee Chair ; Kohl, Paul, Committee Member ; Liu, Meilin, Committee Member ; Nair,Sankar, Committee Member ; Rousseau, Ronald, Committee Member.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

No description available.

The penetration of thin aluminum oxide films by liquid bismuth was studied between 350 and 500°C. A correlation was sought between the type and thickness of the oxide film, and the time and nature of the attack. Mechanical and electropolished, and anodized films of different thicknesses were exposed to liquid bismuth either by immersing a plate in the liquid and measuring the contact angle or by melting a drop of bismuth on a specific area of a plate. Electropolished surfaces had no resistance to attack by the bismuth. Pitting and edge attack occurred with all other surface preparations. The anodized films often separated from the aluminum under thermal stresses and allowed the bismuth to spread under the film, sometimes removing it entirely. Attempts were made to control the number and nature of defects in the oxide film, but the difficulty of this is shown by the scatter in the results. No attack on aluminum oxide itself is likely and no diffusion of bismuth through the oxide was found at the temperatures used. The conclusion was reached that the bismuth penetrated the oxide film only at points where there was a high concentration in the film of some impurity oxide (such as nickel or copper oxides) that reacts with bismuth. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

An investigation into the effect of oxygen on the three ultraviolet optical absorption bands in magnesium oxide was carried out. These peaks were located at 5.75, 5.0 and 4.40 eV within the range 212 to 350 mu. The single crystal platelets were heated in air or oxygen for increasing times at various temperatures. It was found that the increase in peak height with time followed a diffusion relation. A mechanism of formation of the centers causing the 5.75 and 4.40 eV peaks was proposed. The mechanism was based on the oxidation of iron and manganese impurities and the diffusion of magnesium to the crystal surface. The absorbing center was defined as (Fe⁺³∙VMg⁺²). From this it was shown that the diffusion process governing both the 5.75 and the 4.40 eV peaks followed the same Arrhenius relation: D=1.7 X 10⁵ e -77,000/RT cm²/sec. over the temperature range of 800 to 1100° C. No similar conclusions could be drawn concerning the 5.0 eV peak. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

No description available.

Solid basic metal oxides have been extensively studied for biodiesel production via transesterification, researches are now focused on attaining high catalytic activity and durability towards one-step alkali transesterification, as well as high stability towards high free fatty acids (FFAs) and water content in oils for simultaneous esterification and transesterification, to enable their commercialization in industry. This work encompasses the design and characterization of three mixed metal oxide systems, with a detailed evaluation of their potential application in catalyzing transesterification of camelina oil to yield biodiesel. Na0.1Ca0.9TiO3 nanorods were synthesized via a simple alkaline hydrothermal pathway with ethanol as a co-solvent. Owing to their high basic strength of 11<H_<15, 92.7% biodiesel conversion was reached at mild reaction conditions. However, the catalyst showed poor recycle performance, probably attributed to the leaching of active species during transesterification, as revealed by X-ray photoelectron spectroscopy (XPS). A new class of mesoporous Zn/MgO catalyst was synthesized by a simple alkaline hydrothermal method. Zn/MgO calcinated at 600 ℃ exhibited 88.7% biodiesel conversion at 120 ℃ with 3% w/w catalyst, 24:1 methanol to oil molar ratio for 8 h. The catalyst could be reused for five runs without significant loss of activity (≥84.0% biodiesel conversion). The excellent catalyst performance is possibly attributed to its high surface area and large mesopores. The higher surface basic sites density as compared to mesoporous MgO, as indicated by higher total basicity determined from benzoic titration and an increased lattice O2- percentage as revealed from XPS, attributing to its superior catalytic activity. A series of nano-sized MgO-ZnO catalysts with precise stoichiometry were successfully prepared by a simple EDTA complexing approach. Mg0.5Zn0.5 calcinated at 600 ℃ gave a maximum biodiesel conversion of 89.3% at 120 ℃ with 3% w/w catalyst, 24:1 methanol to oil molar ratio for 8 h. Its superior catalytic performance to MgO is mainly associated with the high basic sites density as determined from benzoic titration and XPS. The biodiesel conversion retained over 83.0% for five runs. The enhanced catalyst activity and stability might be contributed by the incorporation of Zn2+ for Mg2+ in MgO lattice and a high homogeneous distribution of MgO particles on ZnO, with the formation of Mg-O-Zn bond as evidenced by Fourier transform infrared spectroscope (FTIR) and XPS. The catalyst also demonstrated high tolerance to FFAs (10% w/w) and water (2% w/w) content, which make it desirable for direct conversion of oils with high FFAs level to biodiesel in a single-step process. Lastly, a Zn/La2O3 catalyst was synthesized by a simple hydrothermal pathway. It exhibits a higher basic strength than La2O3, as evidenced by the slightly lower O1s binding energy determined by XPS, leading to a higher catalytic activity. The enhanced catalytic activity and stability is likely contributed by the incorporation of Zn2+ for La3+ in the lattice. Using 1% w/w Zn/La2O3 as catalyst, the highest biodiesel conversion of 92.7% was obtained at 120 ℃ for 16 h with 36:1 methanol to oil molar ratio. The effective catalyst displayed a biodiesel conversion greater than 84.0% for four runs. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.