Hydrocarbon combustion: The best technique for large scale production of fullerenes.

The fullerenes are a new family of spherical carbon molecules (denoted Cn). They represent the third form of carbon after diamond and graphite. The synthesis of fullerenes in large quantities and at low prices is an industrial and commercial matter of utmost interest. In this study, we demonstrate that the technique of fullerenes synthesis by hydrocarbon combustion in rich mixture is the best technique for the fullerenes production at industrial scale. In an attempt to optimize fullerenes synthesis by hydrocarbon combustion, we investigated 185 flames by systematically varying all flame parameters such as: pressure, gas velocity, nature and percentage of inert gas, C/O richness and nature of hydrocarbon. Modifying these parameters allowed us to thoroughly analyze the profiles of fullerenes production rate, fullerenes yields (%Cn) in the soot, C70/C60 mass ratio and concentration of heavier fullerenes (Cn>) in flames. These profiles enabled us to completely describe the effect of flame temperature on fullerenes formation by hydrocarbon combustion. These profiles indicate that C60 is largely formed in the region where the flame temperature is higher. Another result shows that fullerenes of higher molecular weight (C70, C76, C78, C80, C84, C86 and C90) are formed mainly under low flame temperature conditions.