Thesis (Ph.D.) OGI School of Science & Engineering at OHSU, January 2007. / Abstract: leaf x. Includes bibliographical references (leaves 124-138).

Thesis (Ph. D.)--Columbia University, 1933. / Vita. Bibliography: p. 29.

No description available.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 165-177). Also available via the Internet.

No description available.

A dissertation submitted to the faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering – Chemical Engineering Johannesburg, 2017 / In this research, the C, H and O bond equivalent diagram was used to design processes for DME synthesis using natural gas as a feed. This research proposes alternative ways of producing DME using natural gas (a cleaner gas) compared to the traditional routes. The different feed combinations were assessed for the production of syngas. The crucial step is the H2:CO ratio in each feed which determines the DME synthesis process route and yield. The syngas process was developed under equilibrium and non-equilibrium conditions (assuming 100% methane conversion). The region of operation on the ternary bond diagram was limited by mass and energy balance and carbon deposition boundaries. The feed composition was as follows, (1) Feed 1: methane, steam and oxygen (2) Feed 2: methane, oxygen and carbon dioxide (3) Feed 3: methane, oxygen, carbon dioxide and water. Feed (2) had the highest DME yield. The most optimal reaction route produced DME via the JFE reaction route (H2:CO =1). The yield of DME was 0.67 moles of DME per mole methane processed under non-equilibrium conditions. The proposed route does not emit CO2, excess CO2 is recycled back to the reforming reactor. Under equilibrium, the yield of DME was 0.25 mole DME per mole methane processed. The results indicate that a combination of partial oxidation and dry reforming produces a syngas composition which results in a high DME yield compared to (1) and (3). / MT2017

Mycobacterium vaccae JOB5 and Graphium sp. were studied to evaluate their ability to cometabolize methyl tert-butyl ether (MTBE) and its metabolites after growth on two different alkanes, propane and iso-pentane. Both cultures were capable of cometabolizing MTBE and the metabolites, tert-butyl formate (TBF) and tert-butyl alcohol (TBA). MTBE, TBF, and TBA did not support growth of either microbe. Higher degradation rates were obtained in the bacterial system when the cultures were grown on iso-pentane. Nonlinear least squares regression and direct linear plot methods were used to estimate kinetic coefficients and provided comparable results. The enzymes from Mycobacterium vaccae JOB5 and Graphium sp. that promote the cometabolism of MTBE and its metabolites exhibited similar kinetics and substrate inhibition. The presence of the substrate decreased the degradation rate of MTBE and TBA suggesting competitive inhibition and preference for the substrate. Blockage experiment with acetylene suggested the presence of an alkane monooxygenase for the metabolism of MTBE and TBA, and a hydrolytic enzyme for the degradation of TBF. The presence of a hydrolase enzyme was supported by the fact that TBF was degraded to TBA under either aerobic or anaerobic conditions and was not inhibited by the presence of acetylene, propane, or isopentane. Measured rates of abiotic hydrolysis of TBF were significantly less than biodegradation rates. Acetylene acted as a reversible inhibitor for both cultures when tested in the presence of the growth media and as an inactivator when tested in the presence of a phosphate solution for the bacterial system. Growth-batch reactor experiments were conducted to compare the degradation of iso-pentane and MTBE with the predicted degradation rates based upon kinetic constants determined from single and dual-compound experiments. Experimental data was modeled with Monod kinetics and STELLA�� software. Reasonable predictions of reactor performance were achieved when Monod maximum utilization rates were increased compared to single and dual-compound experiments. / Graduation date: 2002

No description available.

Thesis (Ph. D.)--Columbia University, 1928. / Vita. Bibliography: p. 23.

Thesis (Ph. D.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.