published_or_final_version / abstract / Mechanical Engineering / Doctoral / Doctor of Philosophy

No description available.

Thesis (M.S.)--Mississippi State University. Department of Chemical Engineering. / Title from title screen. Includes bibliographical references.

No description available.

No description available.

This thesis describes research carried out to explore the use of mixed metal alkoxides as precursors of materials with catalytic activity in synthesis-gas chemistry. The alkoxide derived catalyst materials are compared against catalysts prepared by traditional co-precipitation methods. A discussion of the project objectives introduces the work and Chapter 1 includes a chronological survey of the literature up to the present day. A brief discussion of the commercial uses of alkoxides is given. Chapter 2 describes the general methods of synthesis and the properties of simple and bimetallic alkoxides; M(OR)(_x) and M[M'(OR)(_n)](_x) respectively. A more detailed treatment of the alkoxides of the first row transition elements is given, with emphasis on the properties and characteristics responsible for their possible potential as catalyst precursors. Chapter 3 deals with the catalytic aspects of ammonia and methanol synthesis. The preparation of industrial, heterogeneous catalysts has traditionally been carried out by co-precipitation of, for example, basic carbonates. The catalytic materials obtained may display catalytic activities which vary markedly (and not always controllably) with the precipitation, ageing, calcinations and/or reduction conditions employed. A discussion of the reaction mechanisms involved in ammonia and methanol syntheses is included. Several mixed metal alkoxides have been prepared from metals known to have catalytic activity in synthesis-gas chemistry (i.e. Mn, Fe, Co, Cu, Zn and Al). These metal alkoxides (e.g. Cu[Al(OPr(^1) (_4)](_2) ) have been characterised and found to compare well with literature data. Analyses, Infra-red and Mass-spectra are reported. After conversion to catalytic materials the alkoxide derived compounds were examined for surface properties ( oxide phases present, copper surface area, crystallite size, pore size distributions and pore volumes). The alkoxide materials compared quite well with the precipitated analogues and there was a difference in the properties of materials derived from different alkoxy groups. These studies were limited to the copper-aluminium alkoxides. The formation of a nickel (II) chloride, HMPA adduct is reported.

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

No description available.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010. / Committee Co-Chair: Haynes, Comas; Committee Co-Chair: Wepfer, William; Committee Member: Jeter, Sheldon. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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