An experimental study of the premixed benzene/oxygen/argon flame with tunable synchrotron photoionization

Abstract

A comprehensive experimental study of the premixed benzene/oxygen/argon flame at 4.0 kPa with a fuel equivalence ratio ( ϕ) of 1.78 has been performed with the tunable synchrotron photoionization and molecular-beam sampling mass spectrometry. Isomers of most observed species in the flame have been unambiguously identified by measurements of the photoionization efficiency spectra. Mole fraction profiles of species up to C 16H 10 have been measured at the selective photon energies near ionization thresholds, and the flame temperature profile is obtained using Pt/Pt–13%Rh thermocouple. Compared with previous studies on benzene flames by Bittner and Howard, and by Defoeux et al., a number of new species are observed in the present work. These new combustion intermediates should be included in the kinetic models of the growth of polycyclic aromatic hydrocarbons (PAHs) and benzene oxidation. Free radicals detected in the flame include CH 3, C 2H, C 2H 3, C 2H 5, C 3H, C 3H 3, C 3H 5, C 4H, C 4H 3, C 4H 5, C 4H 7, C 5H 3, C 5H 5, C 5H 7, C 6H 5, C 6H 5O, C 7H 7, and C 9H 7. More significantly, isomers of some PAHs have been identified, which should be of importance in understanding the mechanism of soot formation.