Pyrolysis study of a waste plastic mixture through different kinetic models using isothermal and nonisothermal mechanism

Abstract

Pyrolysis can be a convenient way to produce oils and gases simultaneously, as well as hydrocarbons and even crude petrochemicals. It can also be used to produce energy from a waste plastic mixture (WPM). To ascertain the kinetics parameters at the heating rates of 5, 10, 20, and 50 °C min⁻¹, various kinetic models, including (a) model-fitting and (b) model-free, which are further separated into isothermal and non-isothermal categories, have been selected. The apparent activation energy (E_a) and pre-exponential factor (A_a) were calculated using the Friedman (model-free isothermal), KAS, FWO (model-free non-isothermal), and Coats–Redfern (model-fitting non-isothermal) approaches. The activation energy (E_a), pre-exponential component (A_a), and overall reaction order (n) were also calculated using a multi-linear regression methodology. In addition, the solid fuel characterization of WPM has been compared with previous literature results, as have the physico-chemical characteristics of pyrolytic oil. Finally, a brief mention of WPM's kinetic process has been included in this work. However, the results indicated two stages of thermal degradation and volatilization of the WPM zone during pyrolysis (410–510 °C, 510–770 °C). In the temperature range of 410–510 °C, 510–770 °C, two-stage thermal degradation zones are used to analyze the kinetic parameters for WPM. The result showed the average activation values obtained by the KAS, FWO, and Friedmam methods were 297.61, 295.25, and 267.26 kJ mol⁻¹. In the case of the Coats–Redfern methods, the lowest activation energy was obtained by the PT1 kinetic model at 22.56 kJ mol⁻¹, and the highest activation energy was found in the D3 kinetic model at 418.80 kJ mol⁻¹ in the temperature zone of 410–510 °C. The temperature zone with the lowest activation energy was found to be between 510 °C and 770 °C.