Pyrolysis kinetics

What is it about?

The development of polymer recycling is supported by research of degradation kinetics, pyrolysis products, and even reaction mechanisms. In this research, non-isothermal kinetic methods were used to estimate activation energies and to select the best fitting reaction models for high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS). Pyrolysis is thermal heating of materials without oxygen and conversion into gas, liquid, and solid products. To perform an optimum pyrolysis, the degradation kinetics of plastic materials need to be studied. Fourier Transform Infra-Red Spectroscopy (FTIR) was used for characterization of initial materials and Thermogravimetry (TGA) was used to determine the degradation kinetics. Based on the results of the TGA, the optimal degradation temperature for plastic and mixed waste was determined from 380 to 500°C for each selected material. The kinetic method used is Coats-Redfern. From the results of the analysis, the activation energy range for thermal decomposition is 200–300 kJ/mol. This can indicate the minimum energy necessary for the pyrolysis process.

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Photo by Haneen Krimly on Unsplash

Photo by Haneen Krimly on Unsplash

Why is it important?

Study of pyrolysis by model kinetics from Coast-Redfern with first order mechanism shows that activation energy from plastics waste can be determined from thermogravimetric analysis. The complexity of composition and presence of impurities in plastics waste play an important role during the pyrolysis.