Pyrolysis of waste polystyrene into transportation fuel: Effect of contamination on oil yield and production at pilot scale

Abstract

This study investigated the pyrolysis of polystyrene (PS) packaging waste for transportation fuel application of the oil product, with a specific focus on the effect of contamination and the scale-up of the process. The oil yield and calorific value were optimised at bench scale in a semi-batch reactor with temperature and heating rate as input factors. The process was then scaled up to a semi-continuous rotary kiln reactor and the oil product was characterised in terms of fuel properties. Oil yields of 89.8–93.2 wt% with higher heating values (HHV) of 42.1 ± 0.5 MJ/kg were achieved at bench scale with virgin PS. Heavy meat juice contamination (15.9 wt% dry contamination) decreased the oil yield by 6.4 wt%, but did not affect the HHV significantly. Due to more losses at pilot scale, a lower oil yield of 82.5 ± 1.4 wt% was achieved and the gross energy recovered in the oil was 88.0 ± 2.6%. Fuel characterisation indicated that the oil contained substantially less inorganic and sulphur than the waste feedstock. However, for commercial use, blending with conventional fuel would be necessary to mitigate the aromatic content of the oil.