Chemistry of Intermediate Species in the Rich Combustion of Benzene

Abstract

The large potential importance of diesel engines and of synthetic fuels has led to a surge of interest in the associated problem ofsoot formation. It is well known1 that the formation of soot and polycyclic aromatic hydrocarbons (PAH) is strongly influenced by fuel type. Studies in gas turbine-type combustors2–4 and simple laboratory systems such as laminar diffusion flames5–9, premixed flames10–11 and well-stirred reactors2–13, have shown that aromatic fuels have a high propensity to form soot. Recent studies of soot formation in premixed flames using light scattering techniques14–15 have demonstrated the application of the laws of physical coagulation to the later stages of soot formation in flames of different fuels. These studies show that the important difference between fuels,and hence more generally a dominant factor in soot formation, is the mass of carbonaceous material that enters this coagulating system. Thus, it is important to understand the early stages of the chemistry of the fuel oxidation and pyrolysis, the pre-particle chemistry. Since previous studies suggest that the intact aromatic ring, not fragments thereof, is largely responsible for the marked propensity of aromatics to form soot16–19, a detailed study of the preservation or destruction of the ring in rich flames of benzene seems worthwhile.