Development of Catalytic Processes for the Transformation of Low Value Chemical Feedstocks to Value Added Chemicals
Lao, David B.
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Dwindling oil reserves have necessitated the shift to alternative sources for fuels and commodity chemicals. This thesis describes fundamental studies and development of catalytic processes for the transformation of abundant, low value chemical resources into value added chemicals. Chapter 1 of this work gives a brief overview of the motivation, challenges, prior work for the catalytic conversion of methane to methanol, methane to ethane and higher alkanes, and glycerol to 1,3-propanediol. Chapter 2 describes efforts to study the kinetics of methanol oxidation by aqueous sodium periodate. The presence of methane pressure in these reactions hinders the rate of methanol oxidation. These fundamental studies may provide novel strategies to prevent the over-oxidation of methane in gas-to-liquid conversion chemistry. The effect of methane pressure, ionic strength effects, and pH dependence on reaction kinetics was studied, but was complicated by the precipitation and thermal decomposition of sodium periodate. In addition, oxidation of cyclopropyl carbinol was studied to determine the mechanism of periodate oxidation. The lack of ring opening products mitigated against a radical chain mechanism. Chapter 3 discusses attempts to develop a complete catalytic cycle for methyl and aryl coupling using Pt and Pd complexes. These studies introduce potential new strategies for the utilization of methane as a chemical feedstock and catalytic aryl coupling. The formation of biphenyl from monophenyl-Pd<super>II</super> complexes was demonstrated. Attempts to achieve base assisted methane activation with a series of Pt complexes were complicated by ligand incompatibility with bases. Finally, Chapter 4 details the development of a homogeneous iridium pincer catalyst for the catalytic deoxygenation of glycerol, a waste stream from biodiesel production, to 1,3-propanediol and 1-propanol. The tandem catalytic sequence with acid catalyzed dehydration followed by metal catalyzed hydrogenation is a rare example of a homogeneous system that yields 1,3-propanediol from glycerol, albeit in lower yields than 1-propanol. Mechanistic studies suggest that an iridium dihydrogen hydride complex may be the active catalyst in these reactions.
- Chemistry