Detailed kinetic modeling of soot formation in shock tube pyrolysis and oxidation of toluene and n-heptane

A new detailed kinetic model of soot formation in shock tube pyrolysis and oxidation of aliphatic and aromatic hydrocarbons is proposed. The model is based on the comprehensive kinetic model of PAH formation and growth [H. Richter, J.B. Howard, Phys. Chem. Chem. Phys. 4 (2002) 2038–2055; H. Richter, S. Granata, W.H. Green, J.B. Howard, Proc. Combust. Inst. 30 (2005) 1397–1405; J. Appel, H. Bockhorn, M. Frenklach, Combust. Flame 121 (2000) 122–136; M. Frenklach, D.W. Clary, T. Yuan, W.C. Gardiner, Jr., S.E. Stein, Combust. Sci. Tech. 50 (1986) 79–115; M. Frenklach, J. Warnatz, Combust. Sci. Tech. 51 (1987) 265–283; M.S. Skjøth-Rasmussen, P. Glarborg, M. Østberg, J.T. Johannessen, H. Livbjerg, A.D. Jensen, T.S. Christensen, Combust. Flame 136 (2004) 91–128], on the new concepts of soot particle nucleation [A. Violi, Combust. Flame 139 (2004) 279–287; A. Violi, A.F. Sarofim, G.A. Voth, Combust. Sci. Tech. 176 (2004) 991–1005; A. D’Alessio, A. D’Anna, P. Minutolo, L.A. Sgro, A. Violi, Proc. Combust. Inst. 28 (2000) 2547–2554; A. D’Anna, A. Violi, A.D’Alessio, A.F. Sarofim, Combust. Flame 127 (2001) 1995–2003] and the traditional H-abstraction/C2H2-addition (HACA) route of PAH and soot particles surface growth [H. Wang, M. Frenklach, Combust. Flame 110 (1997) 173–221; J. Appel, H. Bockhorn, M. Frenklach, Combust. Flame 121 (2000) 122–136]. The gas-phase kinetic scheme was validated against the experimentally measured concentration profiles of the main gas-phase species formed during toluene pyrolysis and H and OH radicals during benzene and phenol pyrolysis and toluene oxidation behind reflected shock waves. The model describes the main characteristics of soot formation in pyrolysis and oxidation of toluene and n-heptane oxidation under conditions typical of shock tube experiments. Both hydrocarbons have the same number of carbon atoms but different structures, which causes different behavior of the systems. The discrete Galerkin technique was applied for direct counting of the mean number of active sites formed on the surface of soot precursors and soot particles in reactions of activation, deactivation, and surface growth.