Spectral Dependence of Absorbance of the Medium in the UV and Visible Ranges during the Formation of Soot and Polycyclic Aromatic Hydrocarbons in Hydrocarbon Pyrolysis

The temperature profiles of absorbance, reflecting the formation of polycyclic aromatic hydrocarbons and condensed soot particles during shock-wave pyrolysis of methane, ethylene, acetylene, and benzene mixtures with argon, have been obtained at wavelengths of 313, 405, and 633 nm in the temperature range 1500–2600 K and pressures of 3.5–6.4 bar. The contribution of the condensed phase to absorption at wavelengths of 313 and 405 nm is evaluated. The temperature ranges of the most intensive formation of polycyclic aromatic hydrocarbons and soot during the pyrolysis of the studied mixtures are determined. The highest yield of polycyclic aromatic hydrocarbons and soot has been observed during the pyrolysis of benzene, while the lowest yield has been observed during the pyrolysis of methane and ethylene. It has been noted that the maximum yield of polycyclic aromatic hydrocarbons and soot in the case of acetylene pyrolysis is significantly shifted in temperature relative to other hydrocarbons, indicating a difference in the kinetic mechanism of soot formation in the case of acetylene pyrolysis.