CHARACTERIZATION OF PYROLYTIC LIGHT NAPHTHA FROM VACUUM PYROLYSIS OF USED TIRES - COMPARISON WITH PETROLEUM NAPHTHA

Used tyres were thermally decomposed under vacuum in a process develop ment unit. At 510 degrees C and total pressure 2-20 kPa, the process y ielded 50 wt% oil, 25 wt% carbon black, 9 wt% steel, 5 wt% fibres and 11 wt% gas. Distillation of the pyrolytic oil yielded similar to 20 wt % light naphtha (i.b.p. 160 degrees C), 6.8 wt% heavy naphtha (160-204 degrees C), 30.7 wt% middle distillate (204-350 degrees C) and 42.5 w t% of bottom residue (>350 degrees C). D,L-Limonene was one of the maj or chemicals in the naphtha fraction, with a concentration of similar to 7 wt%. The naphtha also had high contents of aromatics, olefins and iso-alkanes (45, 22 and 15 vol. % respectively). Its relatively high levels of sulfur, nitrogen, olefinic and diolefinic compounds would ma ke it unsuitable as a blending component for gasoline without hydrofin ing and reforming. However, similar to 2 vol. % Of the naphtha could b e blended with hydrofiner feedstock without significantly affecting th e process requirements. Approximately 71.1 and 68 wt% of the pyrolytic and petroleum light naphthas respectively were quantified.