The production of fullerenes via the thermal plasma dissociation of tetrachloroethylene

Fullerenes, the family of large, all-carbon, cage-like molecules, promise to launch an array of new products. However, the development of such products is hindered due to unavailability of large quantities of fullerenes and the present high cost of production. Fullerenes are produced commercially via the arc vaporization of graphite, a method which is limited to low production rates and low scale-up potential. In this work, a new process was developed in which fullerenes are produced via the thermal plasma dissociation of hydrocarbons. The process is attractive due to its potential for large scale fullerene production. Tetrachloroethylene (C2Cl4) was selected as the carbon source for fullerene synthesis, due to the instability of C-Cl bonds in the high temperature zone predicted for fullerene formation.; The effect of input electrical power, C2Cl4 feed rate and reactor pressure on fullerene formation and collection was studied. The temperature profile and its effect on the residence time of reactive species in the temperature zone required for fullerene formation was found to play a critical role in the production of fullerenes. With the present reactor configuration, an input power in excess of 55 kW was required for the treatment of up to 0.54 mol/min of C2Cl4. High C2Cl 4 feed rates resulted in a lower conversion of C2Cl 4 to fullerenes. Lower reactor pressures (200 and 300 torr) resulted in higher fullerene yields as compared to results obtained at 400 torr. The maximum concentration of fullerenes in soot was 5.3% and the maximum conversion of C2Cl4 to fullerenes was 2.8%, based on carbon input.; Fullerenes produced by the process were purified using conventional extractive and chromatographic techniques. Although successful, purification by chromatography proved to be difficult due to the presence of perchlorinated, aromatic by-products. Some of these perchlorinated aromatic by-products were identified and were found to have structures reminiscent of fullerene precursors, and thus, may provide clues as to how fullerenes form in this plasma process.