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A novel hydrogen atom source, involving the 193.3 nm photolysis of nitrous oxide in the presence of hydrogen, is described. The system is shown to provide a very clean source of hydrogen atoms, particularly at temperatures above 400K. The H + C₂H₄ addition reaction is studied as a function of pressure (50-750 Torr He) and temperature (285-604K). Resonance fluorescence was used to monitor hydrogen atom concentrations in real time, following excimer (ArF) photolysis of the N₂0/H₂ precursor. The data are analysed using the Troe factorisation method. A model is developed, which allows the accurate calculation of the rate constant for the H + C₂H₄ reaction over a wide range of temperature and pressure. The direct observation of equilibration in the H + C₂H₄ = C₂H₅ system is reported for the first time, at temperatures between 775 and 850K. Hydrogen atom concentrations were monitored by resonance fluorescence, following 193.3 nm photolysis of the ethylene substrate. The equilibrium constant for the system K_c is determined much more precisely than has previously been possible. The standard heat of formation of the ethyl radical, ΔH^o_f, ₂₉₈(C₂H₅), is evaluated from the measured values of K_c(T), using Third Law methods and the known molecular and atomic parameters of H, C₂H₄ and C₂H₅ giving ΔH^o_f ₂₉₈(C₂H₅) = 28.36 ± 0.40 kcalmol . The quoted errors refer to 95.45% confidence limits and include contributions from the scatter of the data and from estimates of possible systematic errors. An excimer laser flash photolysis/ gas chromatographic end product analysis apparatus is described. The design of the photolysis cell allows its entire contents to be transferred to the analysis column, and enables total C₃ hydrocarbon yields as low as 2.6x10¹² molecules to be detected. A study of the photolysis of acetone at 193.3 nm is presented. The dependence of product yields on pressure (10-500 Torr He), temperature (300,600K), laser pulse energy and the presence of radical scavengers (NO,C₂H₄) is described. Under all experimental conditions, methyl radicals account for >95% of the radical products of the photolysis. The ArF photolysis of acetone is demonstrated to provide a very clean source of methyl radicals, suitable for use in conventional laser flash photolysis /kinetic spectroscopy experiments, at temperatures of up to 825K. Experiments are described, in which ethane and ethane/propylene mixtures, diluted to ∿5% in nitrogen, were pyrolysed in a quartz jetstirred reactor. Temperatures and conversions comparable to those achieved in industrial pyrolysis were employed. A kinetic model of ethane pyrolysis is developed, which qualitatively reproduces the experimental results. It is shown that the model predictions are extremely sensitive to a number of poorly defined rate constants.

Hydrocarbon contamination of soil from accidental spills and negligence represents a major cause of sub-surface contamination. There are numerous physical, chemical and biological techniques available for contaminant remediation. However, many of these methods can be difficult to implement at sites where access to soils, or delivery of treatments, requires substantial excavation works and disruption (for example where contamination is located beneath or adjacent to building structures and underground services). An innovative technology that may provide a solution for the remediation of subsurface contamination without causing interim damage is that of electrokinetic remediation. Electrokinetic remediation is the application of a low voltage, direct current (of the order of mA/cm²) between electrodes placed in a contaminated soil system. The production of an electric field causes a number of electrically-induced processes to occur that can promote soil remediation, principally: electromigration, electroosmosis, electrophoresis, and electrolysis. This study examined the use of electrokinetics coupled with biodegradation to remediate kerosene and transformer oil from sub-surface soils. The principal investigations carried out within this study included: the use of electroosmosis as an in situ flushing technique; use of electrokinetics to deliver surfactants into the soil to promote mobilisation of contaminants within the sub-surface; and the use of electrokinetics to create optimum conditions for biodegradation by the delivery of nutrients and electron acceptors, the removal of toxic metabolites, and by controlling the pH and moisture content of the soil. As an integral part of the research, a field trial was designed and set up to determine whether electrokinetics could be used to promote the biodegradation of transformer oil from the subsurface. This was one of the first field trials in the UK for the electrokinetic remediation of hydrocarbon contaminants. The results of the study support the use of electrokinetics as a field tool for the enhancement of remediation in the sub-surface. Laboratory-scale studies showed the potential to mobilise the more soluble hydrocarbons (such as toluene and xylene) in the soil, to deliver enhancing agents (e.g. surfactants and nutrients) and to remove toxic metabolites. The field-scale experiment demonstrated the concept of a relatively low cost treatment cell on-site and provided some evidence that biodegradation of the transformer oil was promoted. Consequently, it is suggested that electrokinetics, with the correct engineering controls in place, provides a valuable method of optimising the biodegradation of hydrocarbons in the sub-surface.

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No description available.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1977. / Bibliography: leaves 100-102. / Microfiche. / x, 102 leaves ill

Dry/CO2 reforming is one the hydrocarbon processes that recently has been interesting due to it is ability of producing a lower synthesis gas ratio (H2/CO). This synthesis gas is a highly significant product since it costs more than 50% of the total capital cost of gas to liquid (GTL) process. However, since this reaction is thermodynamically limited, higher temperature or lower pressure is required to achieve higher conversion. Typically, reaction temperatures between 1073 and 1173 K are used for catalytic dry reforming reactions. Consequently, these extreme temperatures lead to a severe carbon deposition causing a catalyst deactivation which is the major difficulty related to CO2 reforming reaction. This has pushed the efforts to be focused mainly on the development of new catalysts. In fact, dry reforming of propane is an equilibrium-limited reaction which can be shifted to the product side by removing one of the products out of the system which can be achieved using a selective membrane reactor. This research is dedicated to investigate and study the catalytic performance of dry reforming of propane over cobalt-nickel catalyst under the temperature range of 773-973 K. This bimetallic catalyst supported on ??-Al2O3 has been utilized in this research since it exhibits better activity, selectivity, and deactivation resistance than monometallic catalysts. Based on this, the primary aims of this thesis are to examine this catalyst and to study the impact of using membrane reactor. In addition, the reaction mechanism and kinetic are investigated using a fixed-bed reactor. Experimental observations have exposed that the catalyst is offering good results under this reaction. The catalysts analysis has confirmed the presence of metal oxides in the catalyst. However, only at a lower carbon dioxide to propane ratio, i.e. lower than 3.5, a carbon signal has been reported. The activation energy study indicates that the process is unlimited by diffusion. The reaction order for propane and carbon dioxide has been found to be zero and 1.17 respectively. This in turn has indicated that C3H8 activation reaction is taking place rapidly and carbon dioxide is suggested to be involved in the rate determining step. In membrane reactor operation, the production rates for H2 and CO have been reported to increase as the sweep gas flow rate increases. The co-current mode offers higher production rate and more stability than counter-current mode over the range of feed ratio. On the other hand, fixed bed reactor shows stable performance and produces more CO and H2 for both modes.