POLYCYCLIC AROMATIC-HYDROCARBONS FROM THE HIGH-TEMPERATURE PYROLYSIS OF PYRENE

The formation of polycyclic aromatic hydrocarbons (PAHs) from solid fuels is a complicated phenomenon involving many physical and chemical processes. In order to gain a better understanding of the types of reactions taking place during high-temperature PAH production, we carried out a pure compound pyrolysis program between 1200 and 1500 K. In this work, which deals with pyrene pyrolysis in a laminar flow drop tube furnace, we identified four classes of condensed phase reaction products-bipyrenes, their condensation or cyclodehydrogenation products, pyrene fragmentation products and soot. Statistical and steric factors -accounted for qualitatively by the molecular topology of the reaction products-were used to rationalize the relative abundance of the different products in the first two categories. The absence of PAH species that might arise from a sequential acetylene addition pathway (like benzo[e]pyrene, benzo[hi]perylene, coronene, etc.) leads us to conclude that in our system the most important molecular weight growth channel involves direct polymerization of aromatics. Fragmentation products like triphenylene, cyclopenta[hi]acephenanthrylenes, and cyclopenta[cd]pyrene were also detected; however, based on evidence adduced from parallel studies, we think that high amounts of CPP in this and other studies result from isomerization rather than acetylene addition.