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Polycyclic Aromatic Hydrocarbons in Flames, in Diesel Fuels, and in Diesel Emissions



R Dobbins, Robert A. Fletcher, Bruce A. Benner Jr., S Hoeft


Numerous chemical analyses of gaseous and particulate samples from laboratory flames provide a library of data on the polycyclic aromatic hydrocarbons (PAH) species found in diverse flame types burning fuels consisting of pure gaseous hydrocarbons. Diesel fuels utilized by the more complex combustion in compression ignition engines are composed of numerous hydrocarbons species. Mass spectroscopy by the laser microprobe and by gas chromatography were used in a complimentary manner to differentiate the PAHs originating in the fuel from those produced by engine combustion.The CxHy PAH products of premixed and diffusion flame processes, which also proceed in the highly unsteady diesel combustion, range in mass from 128 u (x=10, y=8) to beyond 350 u (x=28, y=14). The y vs. x graphs of the species found by many investigators of laboratory flames show these pyrogenic PAHs to lie on or near the staircase curve that describes the most stable, pericondensed, benzenoid PAHs. In contrast, diesel fuels from the UK [1] and the US [2, 3] contain petrogenic alkyl-PAHs with high hydrogen content.Diesel emissions from engines in use in the 1990s (a NIST SRM and samples from a diesel truck tunnel) display the full mass range of PAHs from 128 to 350 u including both the benzenoid PAHs and alkyl-PAHs. Thus diesel emissions, in general, may contain petrogenic fuel components ranging up to 206 u and also combustion-generated species including the prominent 252, 276, and 300 u mass sequence. The absence of petrogenic components larger than 206 u facilitates their detection and separation from pyrogenic PAHs by methods of chemical analysis.1. Williams, P. T., et al., Fuel 65, 1150 (1986).2. Schauer, J. J., et al., Environ. Sci. Technol. 33, 1578 (1999).3. Benner, B. A., Jr., NIST GCMS data, 9 Jan 2003.
Proceedings Title
University of Umea in Umea, Sweden June 17 -19, 2003.
Conference Dates
June 17-19, 2003
Conference Location
Umea, US
Conference Title
International Congress on Combustion By-Products Origin, Fate and Health Impacts


diesel emission, flames, gas chromatograph mass spectrometry, laser microprobe, mass spectrometry, PAH


Dobbins, R. , Fletcher, R. , Benner Jr., B. and Hoeft, S. (2005), Polycyclic Aromatic Hydrocarbons in Flames, in Diesel Fuels, and in Diesel Emissions, University of Umea in Umea, Sweden June 17 -19, 2003., Umea, US (Accessed April 18, 2024)
Created November 30, 2005, Updated October 12, 2021