AROMATIC AND POLYCYCLIC AROMATIC HYDROCARBON FORMATION IN A LAMINAR PREMIXED N-BUTANE FLAME

Experimental and detailed chemical kinetic modeling work has been perf ormed to investigate aromatic and polycyclic aromatic hydrocarbon (PAH ) formation pathways in a premixed, rich, sooting, n-butane-oxygen-arg on burner stabilized flame. An atmospheric pressure, laminar flat flam e operated at an equivalence ratio of 2.6 was used to acquire experime ntal data for model validation. Gas composition analysis was conducted by an on-line gas chromatograph/mass spectrometer technique. Measurem ents were made in the main reaction and post-reaction zones for a numb er of low molecular weight species, aliphatics, aromatics and polycycl ic aromatic hyrdrocarbons (PAHs) ranging from two to five-fused aromat ic rings. Reaction flux and sensitivity analysis were used to help ide ntify the important reaction sequences leading to aromatic and PAH gro wth and destruction in the n-butane flame. Reaction flux analysis show ed the propargyl recombination reaction was the dominant pathway to be nzene formation. The consumption of propargyl by H atoms was shown to limit propargyl, benzene, and naphthalene formation in flames as exhib ited by the large negative sensitivity coefficients. Naphthalene and p henanthrene production was shown to be plausibly formed through reacti ons involving resonantly stabilized cyclopentadienyl and indenyl radic als.Many of the low molecular weight aliphatics, combustion by-product s, aromatics. branched aromatics, and PAHs were fairly well simulated by the model. Additional work is required to understand the formation mechanisms of phenyl acetylene, pyrene, and fluoranthene in the n-buta ne name. (C) 1998 by The Combustion Institute.