Investigation on the pyrolysis and oxidation of toluene over a wide range conditions. I. Flow reactor pyrolysis and jet stirred reactor oxidation

The pyrolysis of toluene was studied in a flow reactor at pressures from 5 to 760 Torr and temperatures from 1100 to 1730 K using synchrotron vacuum ultraviolet photoionization mass spectrometry. The pyrolysis species and intermediates, including some radicals, isomers and large PAHs, were identified and their mole fraction profiles were evaluated as the function of heating temperature. The oxidation of toluene was investigated in a jet stirred reactor (JSR) at the pressure of 10 atm, residence time of 0.6 s, equivalence ratios of 0.5, 1.0 and 1.5, and temperatures from 950 to 1200 K using gas chromatography combined with flame ionization detector, thermal conductivity detector and mass spectrometry. The concentration profiles of oxidation products as the function of heating temperature were measured. Based on recent theoretical progresses, a detailed kinetic model of toluene combustion with 272 species and 1698 reactions was developed to reproduce the decomposition of toluene and growth of aromatics in both the flow reactor pyrolysis and JSR oxidation. The rate of production analysis and the sensitivity analysis reveal that benzyl and fulvenallenyl radicals play crucial roles in the decomposition of toluene and formation of polycyclic aromatic hydrocarbons (PAHs).