Pyrolysis of polystyrene waste in a fluidized-bed reactor to obtain styrene monomer and gasoline fraction

A specially designed laboratory fluidized-bed reactor apparatus was developed for the pyrolysis of polystyrene (PS) waste in the range 450–700°C with nitrogen as the carrier gas and 20–40 mesh quartz sand as the fluidization medium, operating isothermally at atmospheric pressure. The yield of styrene monomer reached a maximum of 78.7 wt.% at a pyrolysis temperature of 600°C. Some monoaromatics with boiling point lower than 200°C could also be obtained as high-octane gasoline fraction. Styrene monomer with 99.6 wt.% purity was obtained after vacuum distillation of the liquid products, which could be used as the raw material to produce high-quality PS. The attempt to increase the yields of styrene monomer and other monoaromatics by recycling the higher boiling point fraction to the reactor during pyrolysis is also discussed.