Diffusion Flame Studies of the Chemical and Physical Mechanisms of Soot Formation from Aromatic and Substituted Aromatic Fuels: Final Report for the Period February 16, 1984-February 15, 1988

摘要

Benzene was found to be the first product formed in the shock-tube pyrolysis of toluene in the temperature range from 1100 to 1700/degree/K. The yield of benzene peaked at 1425/degree/K. The production of benzene, acetylene and methane were modelled by a set of nine chemical reactions, using rate constants reported in the literature. Benzene was shock-heated in the temperature range from 1100 to 1700/degree/K and biphenyl, phenanthrene, pyrene and p-terphenyl were detected with the liner residue method. This is the first time these species have been observed in shock-tube pyrolysis. These results suggest that in the initial stages of soot formation phenyl rings and acetylenic fragments are required. From the chemical probing of a sooting pre-mixed methane oxygen, it is shown that the growth of soot particles is largely due to surface addition of acetylenic fragments. Premixed methane/oxygen flames and benzene-doped methane/oxygen flames were optically probed to determine the soot volume fraction and the soot particle size. The maximum flame temperature and C/O were held constant. As the benzene concentration was increased, the soot volume fraction increased at early times in the flames. However, the ultimate soot volume fraction was unaffected by the substitution of benzene for methane. 21 refs., 21 figs., 6 tabs.