Analysis of products from the pyrolysis and liquefaction of single plastics and waste plastic mixtures

Waste plastics in the form of two examples of real world municipal solid waste plastics and a simulated mixture of municipal waste plastics were pyrolysed and liquefied under moderate temperature and pressure in a batch autoclave reactor. In addition, the five main polymers which constitute the majority of plastics occurring in European municipal solid waste comprising, polyethylene, polypropylene, polystyrene, polyethylene terephthalate and polyvinyl chloride were also reacted. The plastics were reacted under both a nitrogen (pyrolysis) and hydrogen pressure (liquefaction) and the yield and composition of products are reported. The hydrocarbon gases produced were mainly methane, ethane, propane and lower concentrations of alkene gases. A mainly oil product was produced with the mixed plastic waste with significant concentrations of aromatic compounds, including single ring aromatic compounds. The composition of the oils and gases suggested that there was significant interaction of the plastics when they were pyrolysed and liquefied as a mixture compared to the results expected from reactions of the single plastics.