Kinetic modeling study of toluene pyrolysis at low pressure

A detailed kinetic model, consisting of 137 species and 530 reactions, was developed to simulate toluene pyrolysis at low pressure within the temperature range from 1270 to 1870 K. The mole fraction profiles predicted for pyrolysis species up to phenanthrene were in good agreement with the experiment. The decomposition pathways of toluene and the growth pathways to polycyclic aromatic hydrocarbons (PAHs) were discussed from reaction flux analysis. Toluene decomposes through the reaction sequence C6H5CH3 → C6H5CH2 → C7H6 → c-C5H5 → C3H3, which also has a predominant contribution to the production of acetylene. Furthermore, sensitivity analysis showed that the primary decomposition reactions of toluene, C6 H5CH3 = C6H5CH2 + H and C6H5CH3 = C6H5 + CH3, have great influences on the formation of small molecules, such as phenyl radical, benzyl radical, C2- and C3-species, which are critical to the formation of PAHs in the pyrolysis of toluene.