Product composition from the fast pyrolysis of polystyrene

Polystyrene has been pyrolysed in a fluidised bed pyrolysis reactor and the influence of pyrolysis temperature from 500 to 700 degrees C on the yield and composition of the derived products has been determined. The main produ cts from pyrolysis of polystyrene were a wax/oil product collected, as a co ndensed wax fraction and a separate oil fraction, using an industrial demis ter system. The oils and waxes were analysed by size exclusion chromatograp hy to determine their molecular weight distribution, by Fourier transform i nfra-red spectrometry to determine their functional group composition and b y gas chromatography to determine their detailed composition. The derived o ils had a molecular weight distribution from 60 to 200 Da, with higher mole cular weight material occurring in the wax fraction with a distribution of 60 to over 1000. Detailed analysis of the oils showed that the pyrolysis of polystyrene gave a mainly aromatic composition dominated by styrene and st yrene oligomers. The oils also contained polycyclic aromatic hydrocarbons w hich increased in concentration as the pyrolysis temperature was increased to 700 degrees C. Low concentrations of hydrocarbon gases consisting of hyd rogen, methane, ethane, ethene, propane, propene, butane and butene were al so formed. There was an increase in gas yield with increasing temperature o f pyrolysis.