Flow Reactor Measurement of PAHs and PM Formed from Low Temperature Benzene Pyrolysis with and without Oxygen

The main component of PM (particulate matter) formed in the combustion field is soot, and its formation mechanism is hydrocarbon fuel pyrolysis, polymerization and partial oxidation. In this experimental research work, formation of PAHs(polycyclic aromatic hydrocarbons) and PM in a benzene-oxygen-nitrogen mixture were studied using a flow reactor. The effects of temperature and oxygen on PAHs and PM formations were investigated by independent control of temperature and oxygen concentration. In order to investigate the growth processes of PAHs, mass concentration fractions (relative mass fraction to initial benzene) of naphthalene, biphenyl, phenanthrene, anthracene, and pyrene were measured.As the result, it was found that mass concentration of biphenyl formed from benzene-N2mixture pyrolysis without oxygen was higher than naphthalene. Under the pyrolysis with oxygen, the mass concentration of naphthalene was higher than biphenyl. Mass concentrations of PAHs had two peaks at 1,190 K and 1,250 K in 2.3 vol% oxygen mixture but had only one peak of 1,190 K in no oxygen mixture. Large fraction of PAHs but small fractions of PM wereformed from benzene-N2 mixture pyrolysis without oxygen and PM concentration increased with addition of oxygen.There was PM formation valley at around 1,280 K. above 1,310 K, greater PM concentrations were measured. The conversion ratio from benzene to PM was over 20%, however this showed no statistical difference in the presence or absence of oxygen.