Mechanism of Soot Formation in Preximed C2H2/O2 Flames

摘要

Neutral species in rich C2H2/O2 premixed flat flame stabilized under reduced pressure were analyzed by coupled molecular beam-mass spectrometry. In order to investigate whether particular variations are observed at the sooting limit (2.1) 6 flames of equivalence ratio 1.8, 2.0, 2.1, 2.2, 2.6 and 3.0 were studied. The roles played by polyacetylenic hydrocarbons and polycyclic aromatic hydrocarbons (PAH) in the mechanism of soot formation were compared. Profiles of mole fraction and mass fraction flux versus distance to the burner show that polyacetylenics cannot be considered as active intermediates. A strong reactivity is observed at the boundary between oxidation and soot formation zones for PAH. Variation of the profiles of mass fraction flux for species containing one to six carbon atoms, and the role played by deshydrogenation reactions were studied. Results suggest that C4H4 plays a major role in the first step of the mechanism of soot formation.