Laser-Initiated Chain Reactions In The Partial Oxidation Of Methane

Using both thermal initiation and laser photolytic techniques, we have been studying important kinetic processes in the partial oxidation of methane. Prompt production of a relatively high concentration of free radicals via laser photolysis makes it possible to separate the thermal initiation step from the subsequent chain propagation steps. If a particular product such as methanol is desired, the conditions (temperature, pressure, and mixture composition) for rapid thermal initiation and optimum yield may differ and laser initiation of the chain provides an exciting potential application for laser-induced chemistry. We report our results on the partial oxidation of methane by oxygen at moderate temperatures and pressures. Using 193 nm photolysis of trace amounts of acetone as a source of methyl radicals, dramatic evidence of chain reaction processes is observed for laser initiation under experimental conditions where thermal initiation is not. significant. Details of the proposed mechanism are discussed as well as application of the technique to technologies for methane conversion to transportable fuels such as methanol.