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PhD - Science / Gold has been regarded as being inert and catalytically inactive for many years compared with for example the platinum group metals. However, for the past decade gold has attracted a growing attention as both a heterogeneous and homogeneous catalyst and it has been shown that it can catalyze a wide range of reactions such as oxidation, hydrogenation, reduction, etc. This project entails the synthesis, characterization and testing of a suitable gold catalyst for the oxidation of carbon monoxide (CO), and some hydrocarbons (methane). In this project 2 wt% Au/TiO2; Au/TiO2-ZrO2; Au/TiO2-CeO2 catalysts were prepared by both deposition-precipitation and co-precipitation methods. Different synthesis conditions such as pH, catalyst ageing, and catalyst pretreatment were investigated in order to find suitable conditions for the preparation of catalyst that would be more active at lower temperature range (25 oC – 100 oC). The techniques used for catalyst characterization include, TGA, XRD, BET, XPS, TPR, XANES, HRTEM etc. in order to elucidate the catalyst surface structure and its suitability in affecting adsorption and subsequently catalytic activity. Carbon monoxide and methane oxidation reactions were undertaken in a tubular glass flow reactor. It was observed that when gold is well dispersed on a suitable support, it can catalyze total oxidation of CO at room temperature, provided that certain preparation and pretreatment conditions are followed. An uncalcined catalyst was found to be more active than the catalyst calcined at higher temperatures. This is due to the agglomeration of gold particles on the surface of the support according to our High Resolution Transmission Electron Microscopy results. With Mössbauer spectroscopy, it was observed that the addition of the second support metal oxide such as zirconia resulted in the decrease in agglomeration of gold particles. In such iv catalysts, a considerable amount of ionic species were preserved even after calcination at 400 oC resulting in the higher activity. With Au/TiO2, a batch of uncalcined catalyst dried at 120 oC overnight was leached with cyanide to remove the bulk metallic gold particles, supposedly leaving mostly ionic, small, and well dispersed gold particles and the activity of such leached catalyst was higher than that of the unleached sample. Methane oxidation was found to be very difficult compared with carbon monoxide, and only 8% conversion was achieved at 450 oC whereas a total CO oxidation was achieved at lower temperatures with the same catalyst. It is conclusive that small, ionic well dispersed gold species are necessary for CO oxidation and the adsorption and the active sites for this reaction may be different from those involved in methane oxidation.

This work is an experimental and theoretical analysis of factors and conditions affecting smoke and carbon monoxide (CO) production in corridor-like enclosure fires. Thirty eight experiments were performed in a three metre long corridor-like enclosure having a cross section 0.5 m x 0.5 m, door-like openings in the front panel and a propane gas burner located near the closed end. Measurements of smoke and carbon monoxide concentrations were performed at locations inside the enclosure and also in the exhaust duct of a hood collecting the combustion products. The main conclusion of this work is that smoke production depends not only on the fuel and Global Equivalence Ratio (GER) - as is reported in the literature - but also on the temperatures and residence time inside the enclosure, at least for the experimental conditions examined in this study. Additionally, it was found that the smoke concentration inside the enclosure was increasing during the ventilation controlled regime even after external burning started. Such increase was verified by temperature, smoke and velocity measurements inside the enclosure. The increase was due to reverse flow behind the flames travelling along the corridor. Namely, the gases reversed direction behind the flames with hot gases travelling in the upper layer backwards towards the closed end of the corridor in contrast to hot gas movements towards the opening in front of the flames. This recirculation was confirmed by velocity and oxygen concentration measurements in the upper and lower layers inside the enclosure. In addition, the present results show that the relationship reported in the literature between smoke and carbon monoxide production during overventilated conditions yco/ys ≈ constant, is no longer valid during an underventilated enclosure fire. The ratio yco/ys increases for the Global Equivalence Ratios of the enclosure greater than one. The obtained results are useful for CFD validation and specifically applicable for assessing smoke hazards in corridor fires in buildings where smoke concentrations can be much larger than anticipated owing to leakage to adjacent rooms behind travelling flames.

published_or_final_version / Chemistry / Master / Master of Philosophy

No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 101-103). Also available via the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 218-220).

Thesis (M.S.)--Brigham Young University. Dept. of Chemical Engineering, 2007. / Includes bibliographical references (p. 83-86).

. The kinetics of the absorption of carbon monoxide by basic solutions was studied at 80°C and carbon monoxide pressures up to 30 atmospheres. The reaction was followed by the rate of decrease of carbon monoxide pressure in a closed system. The observed kinetics in potassium hydroxide solutions yield a rate law of the form (formula omitted) No influence from Li⁺, Na⁺, K⁺ ions was detected and no catalytic effect from Ag(I),- Cu(II), T1(I), N0₃⁻, Mn0₄⁻ was observed. The kinetics are consistent with a mechanism which includes the insertion of a carbon monoxide molecule into the hydroxyl bond,viz. (formula omitted) The rate-controlling step above 90°C was found to be the mass transfer of carbon monoxide from the gas phase into the liquid phase under the conditions involved in this study. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate