Reaction of Carbon with Nitric and Unified Mechanism for Oxidation Carbon Gasification

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ABSTRACT CTS-9523801 This is a study of the reaction between carbon and nitric oxide (forming nitrogen and carbon oxides), including an examination of a hypothetical surface oxygen complex which could be the basis for a unified mechanism for all oxidative gasification reactions of carbon. In the first part of this study, rates are measured for the reaction between carbon and nitric oxide using electron microscopy and single-crystal graphite for both uncatalyzed and catalyzed reactions. For the uncatalyzed system, measurements include the relative rates of reaction of oxygen and nitric oxide with carbon, the dependence of activation energy on temperature, the kinetics of abstraction of basal-plane atoms, kinetic effects of water and carbon monoxide, and surface nitrogen species. For catalyzed reactions, turnover frequency is determined from the monolayer channeling rate data on the basal plane of graphite; catalysts are selected from the transition metals, alkali metals, and alkaline earths. The second part of this study seeks better understanding of the oxygen intermediate suggested by molecular orbital theory; this species is the key to a unified mechanism. Four graphites with four gases (oxygen, nitric oxide, water, and carbon dioxide) are studied by temperature-programmed desorption (TPD). Spectroscopic analyses (Fourier-transform infrared, X-ray photoelectron, and carbon-13 nuclear magnetic resonance) are performed on graphite samples after interrupting TPD experiments at various temperatures to determine, if it exists, a correlation between surface oxygen species and carbon - monoxide desorption energies. The "gasification" of carbon is a key element in a large number of energy, chemical, and environmental processes. This, project examines one reaction (the fourth to be studied in this series) in the family of carbol gasification reactions and attempts to reduce the collected knowledge to a unified mechanism for the process. ***