Abstract

Polycyclic aromatic hydrocarbons (PAHs) are important precursors of particulate matter (PM) emitted from combustion, but the detailed reaction mechanism for the PAHs formation is not known enough. To experimentally confirm a chemical role of acetylene on the formation of PAHs from benzene, the pyrolysis for the mixture of deuterium-substituted benzene with acetylene was investigated in an atmospheric-pressure and high-temperature reaction flow tube coupled with laser ionization time-of-flight mass spectrometer (TOFMS), and was compared with that for the mixture of normal benzene. The difference in mass numbers of PAHs observed between the C6H6 and C6D6 mixtures showed that acetylene added to benzene assisted the formation of PAHs at the temperatures less than 950 C. Above 1000 C, the reaction mechanism became very complicated, and the hydrocarbon fragments formed through the thermal decomposition of benzene also contributed to another path of the PAHs formation.