Modeling of PAHs in low pressure sooting premixed methane flame

A detailed chemical kinetic modeling has been developed to investigate aromatic and first polyaromatic hydrocarbons formation pathways in sooting methane premixed flames operating at two equivalence ratios (2.05; 2.32) and various pressures (0.211- 0.263 atm). The model validation is performed by comparing modeled and quantitative experimental profiles of low molecular weight aromatic species ranging from benzene to pyrene. Experiments were carried out using jet-cooled laser-induced fluorescence performed after microprobe sampling. Temperature profiles were obtained using two-line atomic fluorescence (TLAF). The kinetic mechanism proposed in this work is an extension of our previous mechanism validated on a large number of reactive systems including saturated and unsaturated hydrocarbons under very large conditions in terms of pressure and equivalence ratio, but never in conditions producing soot particles. With the new proposed mechanism, it is possible to predict the formation/consumption of the studied PAHs in the reaction zone and in the post flame region where soot particles are produced. This last point is a challenge for the main literature combustion mechanisms. We also identified and discussed here the main reaction pathways responsible for this behavior. It was also shown that the relative importance of reactions determining benzene, naphthalene and pyrene formation may vary considerably from one literature mechanism to another.