Pyrosynthesis of PAH in a Diesel Engine Operated on Kerosene

The objective was to investigate PAH emissions in diesel particulates using a kerosene fuel that had a PAH content that was predominantly two ring. Higher PAH were two orders of magnitude lower in concentration in the fuel than for diesel, but the two ring PAH were a higher proportion of the fuel than for diesel. Pyrosynthesis of higher PAH in the particulate from the two ring PAH would thus be easier to detect for kerosene. Fresh PAH free lubricating oil was used throughout in an attempt to eliminate additional sources of PAH. The kerosene results showed that emissions of higher PAH were an order of magnitude lower than with diesel. However, these PAH emissions were compatible with an unburnt fuel source, as the n-alkane results showed that the higher MW fuel components had a much greater survivablity than for diesel. A contribution to PAH and n-alkane emissions from the exhaust pipe deposits was also identified. No significant source of higher PAH by pyrosynthesis from lower PAH could be identified. However, compounds such as benzo-a-pyrene could not be measured in kerosene and a mass balance could not be established. Thus, pyrosynthesis of some important PAH may still be significant.