SOOT FORMATION IN SHOCK-TUBE PYROLYSIS OF TOLUENE-N-HEPTANE AND TOLUENE-ISO-OCTANE MIXTURES

Soot formation during the pyrolysis of argon-diluted mixtures of tolue ne and n-heptane and of toluene and iso-octane in a reflected-shock tu be was studied. Soot induction times and rates of formation measured a t 632.8 nm by laser beam attenuation showed an Arrhenius dependence on reflected-shock temperature. The maximum in bell-shaped distribution of soot yield and concentration as a function of temperature decreased with increasing amount of n-heptane or iso-octane substituted for tol uene. A kinetic model was used to explain the experimental trends and gave reasonable prediction of the experimental observations. The reduc tion in soot yield and concentration was attributed to the faster deco mposition of the alkanes as well as to their decomposition products, w hich diverted the soot formation process from the more effective path of toluene pyrolysis to a slower route.