Shredded scrap automotive tyres were pyrolysed in a static batch react
or in a stream of nitrogen. The products were passed directly to a sec
ond heated reactor, where secondary reactions of the pyrolysis vapours
occurred. The condensed tyre pyrolysis oil, after secondary reaction,
was analysed for the content of polycyclic aromatic hydrocarbons (PAH
). The concentration of PAH in the oil was high, reaching over 10% of
the total mass of derived oil. Individual PAH of known carcinogenic or
mutagenic activity, for example benzo[a]pyrene, benzo[e]pyrene, chrys
ene and fluoranthene, were present in significant concentrations. The
concentration of PAH were found to increase with increasing secondary
reaction temperature, the formation of PAH occurring via a Diels-Alder
type reaction involving the aromatization of olefinic compounds. The
derived tyre pyrolysis oil represents a significant health hazard.