Experimental and kinetic modeling study of para-xylene chemistry in laminar premixed flames

Abstract

The chemistry of para-xylene oxidation in laminar premixed flames has been analyzed using new experimental data on flame propagation at atmospheric pressure and flame structure of low-pressure stoichiometric flame. Atmospheric pressure laminar burning velocities of para-xylene + air flames were determined using the heat flux method at initial temperatures of 328 and 353 K over the equivalence ratio range of ϕ = 0.7–1.4 and of ϕ = 0.7–1.3, respectively. Temperature and mole fraction profiles of reactants, final products, and reactive and stable intermediate species have been measured in laminar premixed CH4/O2/N2 and CH4/1.5%C8H10/O2/N2 flames at low pressure (40 Torr) using thermocouple, molecular beam/mass spectrometry, and gas chromatography/mass spectrometry techniques. These new experimental results have been modeled with our previous model including sub-mechanisms for aromatics (benzene up to p-xylene) and aliphatic (C1 up to C7) oxidation. Good agreement has been observed for the profiles of the main species analyzed. Moreover, chemical pathways for common species in methane flame with and without 1.5% of benzene or 1.5% toluene investigated earlier under similar conditions were analysed and compared to the present flame doped with para-xylene. Key reactions of aromatics degradation in CH4/O2/N2 flames were identified and discussed. Burning velocities of para-xylene + air flames were also reproduced by the kinetic model.