Non-catalytic and catalytic pyrolysis of polystyrene, polypropylene, and polyethylene for liquid fuel production using a reactor integrated with a fractionation column

Abstract

The increasing accumulation of plastic waste, particularly from polystyrene (PS), polypropylene (PP), and polyethylene (PE), necessitates effective valorisation strategies. This study investigates the potential of non-catalytic and catalytic pyrolysis for converting these plastics into liquid fuel using a reactor integrated with a fractionation column. The effect of temperature (350–650 °C) and the presence of an HZSM-5 catalyst on fuel yield and quality was examined to optimize the pyrolysis process. The results indicate that higher temperatures and catalytic pyrolysis significantly enhance the production of lighter hydrocarbon fractions. Among the tested plastics, PS exhibited the highest calorific value, followed by PP and PE. The introduction of HZSM-5 catalyst notably increased API gravity, signifying the formation of lighter, fuel-grade hydrocarbons. The liquid products displayed varying colours and compositions across different fractionation trays, with fractions ranging from brownish yellow to pitch-black, indicating differences in carbon content. The heaviest fractions, accumulating in Tray IV, primarily consisted of high-carbon-content hydrocarbons and solid black tar. GC-MS analysis confirmed the presence of C₁–C₁₃ aromatic compounds, essential components of fuel oil. These findings highlight the potential of optimized catalytic pyrolysis in transforming plastic waste into valuable liquid fuels that closely align with commercial fuel standards. Furthermore, an economic feasibility assessment suggests promising prospects for the large-scale implementation of this pyrolysis technology.