Thermochemical liquefaction of thermoplastic into fuel using toluene: Product distribution and behaviour

Abstract

The escalating accumulation of plastic waste presents a critical environmental challenge due to its resistance to degradation. Liquefaction, a thermochemical conversion process, emerges as a promising solution to convert plastic waste into valuable resources like fuel. The objective of this study was to investigate the behaviour of plastic polymer degradation in solvothermal liquefaction. This study comprehensively examines the liquefaction processes HDPE, LDPE, PS, and PP under 350–400 °C conditions and 30–90 min reaction times, using toluene as a solvent in an autoclave batch reactor. The results indicate that temperature significantly impacts liquefaction efficiency, with the following sequence: PS > PP > LDPE > HDPE. The liquefied products exhibit high heating values (HHV) of 40–44 MJ/kg, with viscosity and density comparable to gasoline and diesel. GC–MS and FTIR analyses reveal a composition rich in olefins, paraffins, and aromatics, producing carbon chain lengths from C₆ to C₂₀, aligning with conventional fuel. Finally, the mechanism of liquefaction for the polymers is proposed based on the chemical components found.