Formation and growth of dispersed carbon particles during pyrolysis of ethylene, benzene, and naphthalene in a reflected shock wave

The formation and growth rates of dispersed carbon particles were determined experimentally for pyrolysis of ethylene, benzene, and naphthalene in a reflected shock wave at temperatures of 1920–2560 K and hydrocarbon concentrations in argon of 1.8–20%. The diameter of the particles formed was estimated (30–600 $\mathring{\mathrm{A}}$). The maximum rate of particle formation at various temperatures [(0.7–96) $\cdot$ 10$^{16}$ cm$^{-3}$ $\cdot$ sec$^{-1}$] and the particle growth rate (0.002–0.036 cm $\cdot$ sec$^{-1}$) were determined from results of measurements of reaction (residence) times. For pyrolysis of benzene, the activation energy of the overall process of particle formation is 410 kJ/mole, and for all hydrocarbons studied, the activation energy of the overall process of particle growth is 5–50 kJ/mole. The surface average particle diameter increases with increasing concentration of the initial hydrocarbon at a constant temperature.