Soot Formation During Pyrolysis of Aromatic Hydrocarbons (Modeling, Shock-Tube, Acetylene, Butadiene).

Abstract

A study combining experimental, empirical modeling, and detailed modeling techniques has been conducted to develop a better understanding of the chemical reactions involved in soot formation during the high-temperature pyrolysis of aromatic and other unsaturated hydrocarbons. The experiments were performed behind reflected shock waves in a conventional shock-tube with soot formation monitored via attenuation of a laser beam at 633nm. Soot-formation measurements were conducted with toluene-argon and benzene-argon mixtures. Detailed kinetic models of soot formation were developed for pyrolyzing acetylene, butadiene, ethylene and benzene. The computational results indicate the importance of compact, fused polycyclic aromatic hydrocarbons as soot intermediates and the importance of the reactivation of these intermediates by hydrogen atoms to form aromatic radicals. The overshoot by hydrogen atoms of their equilibrium concentration provides a driving kinetic force for soot formation. The results with ethylene and butadiene indicate that acetylene is an important growth species for soot formation for these fuels. The benzene model suggests that reactions between aromatic species may be important for soot formation from aromatic fuels.