Kinetic study of polyethylene terephthalate (PET) pyrolysis in a spouted bed reactor

A spouted bed reactor has been designed and constructed to study the kinetic of the pyrolysis of polyethylene terephthalate (PET), in the temperature range of 450-560 °C. The kinetic parameters were determined based on the weight change of the PET sample and were fitted successfully to a first-order kinetic model. Two particle sizes have been considered (0.1-1.0 mm and 1.0-3.0 mm) in order to study the role of heat and mass transfer limitations probably existed which affect the kinetic parameters. The results confirm a good performance of spouted bed in performing kinetic study of PET pyrolysis at high temperatures. The activation energy of 276.8 and 264.3 kJ/mol was determined for particle size ranges of 0.1-1.0 and 1.0-3.0 mm, respectively. The similarity between data for the different two particle size ranges revealed that the heat and mass transfer limitations in spouted bed reactors may have been minimized. The kinetic parameters for the pyrolysis of PET were evaluated applying isothermal thermogravimetric analysis (TGA). In such an analysis, the apparent activation energy observed were within the range of 245-292 kJ/mol, for different particle sizes studied. There is a good agreement between the data obtained in this study with the values reported in the literature.