Mississippi State University
Estevez, L. Anotonio
Zappi, E. Mark
French, W. Todd
Date of Degree
Dissertation - Open Access
Doctor of Philosophy
James Worth Bagley College of Engineering
Dave C. Swalm School of Chemical Engineering
Efficient use of renewable feedstocks for production of chemicals and intermediates is necessary to reduce dependence upon petroleum. A large portion of these chemicals could be produced using lipids from renewable feedstocks such as vegetable oils, animal fats, and bacterial lipids. For example, many lipid sources contain unsaturated fatty acids, which can be oxidized to form a variety of products such as diacids and epoxides. These chemicals are used to formulate herbicides, detergents, plasticizers, lubricants, paints, and other useful products. One of the most common unsaturated fatty acids is oleic acid, and it can be oxidized with an ozone/oxygen mixture to produce azelaic acid and pelargonic acid. Since the ozone/oxygen mixture is a gas and oleic acid is a liquid under reaction conditions, mass transfer limitations exist. However, a reduction of the mass-transfer limitations can be achieved if the reactants coexist in a single phase. When supercritical carbon dioxide (SC-CO2) is used as the reaction medium, it is possible for both oleic acid and the ozone/oxygen mixture to both exist in the same phase at the same time. Use of supercritical carbon dioxide also provides the possibility of product fractionation, depending upon the solubility of the products in SC-CO2. The overall goal of this research was to determine if any advantages could be realized by conducting the oleic acid oxidation in a supercritical fluid medium. First, the solubility of azelaic acid and pelargonic acid in supercritical carbon dioxide was determined over a range of temperatures and pressures. Pelargonic acid was found to have a significantly higher solubility than azelaic acid, which indicated the potential for product separation with supercritical carbon dioxide. Second, the impact of the solvent medium on reaction kinetics and product formation was determined using two oxidizers: ozone and potassium permanganate. Due to experimental limitations, no reaction was observed in the case of ozone in supercritical carbon dioxide. However, oxidation of oleic acid with potassium permanganate in supercritical carbon dioxide resulted in higher oleic acid conversion and increased yields of azelaic acid and pelargonic acid compared to the oxidation without SC-CO2.
Sparks, Darrell Lynn, "Oxidation of lipids in a supercriticalluid medium" (2008). Theses and Dissertations. 3428.