Screening of modified kaolin catalysts in the catalytic pyrolysis of waste high-density polyethylene: Kinetics and thermodynamic analysis, Artificial Neural Network prediction, batch pyrolysis study and characterization of liquid fuel

Plastic waste has become a major hurdle in achieving a pollution-free environment for humans to live in. So, recycling used plastic is essential to protect the environment from degrading further. High-density polyethylene is a widely available plastic among the several types of plastics used every day. In the present study, waste HDPE was catalytically pyrolyzed utilizing different acids and alkali-activated kaolin catalysts in batch pyrolysis studies to screen the catalyst and optimize temperature for greater condensable oil output. The HNO3-treated kaolin gives comparably highest oil output with the least reaction time among all catalysts used in the experiment. Kinetics and thermodynamics of HNO3-catalysed pyrolysis of waste HDPE were analyzed from the thermogravimetric data at three heating rates. ANN modelling accurately simulated the TGA data as the value of R2 was near to one. The liquid fuel produced from HNO3-treated kaolin was then analyzed for composition by FTIR, GCMS and fuel properties. The analysis report confirms the presence of saturated and unsaturated alicyclic hydrocarbons with carbon composition C10-C25. From the composition and fuel properties, it can be concluded that the oil obtained in the catalytic pyrolysis could be used as a feedstock to the petroleum refining industry for obtaining transportation-grade fuels.