Mechanisms of Fullerene Synthesis in Flames

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The primary focus of this research program is the quantitative investigation of the detailed mechanisms responsible for conversion of fuel carbon into highly symmetrical, low entropy fullerene compounds in flames. The project includes three main components: combustion experiments, molecular orbital modeling, and kinetic modeling. In the combustion experiments, laboratory data on rates of production and consumption of fullerenes, fullerene precursors, and other species and flame parameters will be collected. The flame properties to be measured include profiles of concentrations of stable species, fullerenes, fullerene intermediates, and polycyclic aromatic hydrocarbons (PAH) along with OH radicals and temperature through a low-pressure premixed flat flame; these measurements will be made at various operating pressures, cold-gas velocities, and feed compositions. Some key intermediates involved in fullerene production will not be experimentally observable due to their transient nature, so their thermodynamic properties will be estimated using molecular orbital modeling methods. This information will then be used in the last component of the program, mechanism development and kinetic modeling, along with the measured profiles, for development of a coherent, quantitative explanation of the steps involved in fullerene production, leading to definition of strategies for optimization of fullerene production via combustion synthesis. Considerable interest in fullerenes (also referred to sometimes as the third form of carbon, alongside graphite and diamond), has developed over the past few years. Potential uses for these compounds are just beginning to be defined; such definition and subsequent actual utilization are limited by a lack of material with which to work and its extraordinarily high price. Combustion synthesis of fullerenes offers a potentially attractive route (alternative to the currently more widely used electric arc method of fullerene production) for cost and scale-up reasons. Thus, development of an understanding of how fullerenes are formed in flames, leading to optimization (in terms of operating parameters and apparatus configuration) of combustion synthesis of these materials, is of major interest.