Adsorption of Propane on the Magnesium Oxide (100) Surface and Synthesis of Anodized Aluminum Oxide
Date of Award
Doctor of Philosophy
John Z. Larese
T. Ffrancon Williams, George Kabalka, Norman Mannella
This work is divided into two parts: the adsorption of propane on the magnesium oxide (100) surface and the synthesis of anodized aluminum oxide. The adsorption properties of propane on the MgO (100) surface were investigated using high-resolution volumetric isotherm techniques and a computational study was accomplished using Materials Studio. From the adsorption work, the two-dimensional isothermal compressibility, the isosteric heat of adsorption, the differential enthalpy, and the differential entropy of adsorption can be calculated. Three distinct layers of propane were observed to form on the MgO (100) surface and it was determined that a phase transition occurs at 162 K. The simulation study showed that the propane molecule adsorbs on the surface, centered over magnesium, at a distance of 3.18 Angstroms. The molecule is oriented such that the carbon backbone is parallel to the surface and is rotated so that three hydrogen atoms are close to the surface. The calculated minimum energy of this system is 13.70 kcal/mol.
The second part of this study focuses on the synthesis and characterization of well defined, close packed, high aspect ratio cylindrical channels in an aluminum oxide matrix. These materials have been systematically produced using a two-step anodization process that provides the ability to tune the pore diameter (<10 nm to 100 nm) while retaining the long-range hexagonal pattern. The effect of varying the type and concentration of the electrolyte was investigated. The synthesized materials were characterized using a scanning electron microscope, an atomic force microscope, and a high-resolution volumetric isotherm station to obtain adsorption and desorption measurements. It was found that these three techniques compliment each other nicely. The SEM results give a quick overview of the topography of the surface, AFM gives a more complete profile of the surface, and the isotherm measurements provide an overall pore distribution. These materials have the potential to be used in the study of gas storage, quantum confinement, and nanowire growth.
Felty, Michael John, "Adsorption of Propane on the Magnesium Oxide (100) Surface and Synthesis of Anodized Aluminum Oxide. " PhD diss., University of Tennessee, 2008.