Catalytic decomposition and kinetic study of mixed plastic waste

Pyrolysis is a promising technology for the valorisation of plastic waste by converting it into valuable products, such as fuels and chemicals. This study aims to assess the thermogravimetric behaviour and kinetic parameters of the real-world plastic waste mixture with added nickel- and iron-based catalysts on gamma-aluminium oxide as support. Thermogravimetric measurements were carried out in a nitrogen atmosphere over a set of heating rates (5, 10, 15 and 20 °C/min) within a temperature range 40–600 °C. Kinetic analysis was performed through a combined approach by using the model-free isoconversional Friedman method and regression methods (linear and multivariate nonlinear). The kinetic analysis results showed a complex decomposition mechanism of the real-world plastic waste mixture. The average apparent activation energy for the real-world plastic waste mixture (22% high-density polyethylene, 31% low-density polyethylene, 35% polypropylene, 12% polystyrene) was 205 kJ/mol. The initial value decreased by 15.6% with the addition of iron-based gamma-aluminium oxide catalyst and only 9.8% with nickel-based gamma-aluminium oxide catalyst.