Experimental and computational investigation of the structure of a sooting C2H2-O2-Ar flame

Abstract

Mole fraction profiles have been measured by molecular beam-mass spectrometer technique in a sooting C2H2-O2-Ar flame (27.5%-27.5%-45%) stabilized under reduced pressure (2.6 kPa) on a flat flame burner. Emphasis was put on the detection and concentration measurement of the intermediate species which play a role in the formation of the first aromatic rings. In addition to the major products and the radicals usually involved in acetylene oxidation mechanisms, C2H, C2H3, C3, C4 species and benzene have been measured. The mole fraction profiles have been compared with predictions from a simulation model. Care was taken to use as much as possible a detailed mechanism known to model acetylene oxidation in a wide range of experimental conditions. The mechanism proposed by Warnatz23, for the oxidation of alkanes and recently checked by Westmoreland38 for the modelling of a rich C2H2/O2 flame was adopted as a starting point. This tested mechanism was complemented by formation and consumption reactions for C4H3, C4H4, C4H5 and benzene. The satisfactory agreement between calculated and measured profiles was turned to account to specify the main steps in the route to benzene.