Kinetics of Scrap Tire Pyrolysis in a Conical Spouted Bed Reactor

The kinetics of the pyrolysis of tire material has been studied in a conical spouted bed reactor (CSBR), in the range between 450 and 600 °C, for two particle size ranges (between 0.1 and 0.8 mm and between 0.8 and 4.0 mm). The kinetic results have been compared with those obtained for the same material with other technologies, namely, thermogravimetry and a fast heating microreactor. This comparison and the one carried out with the literature results for similar materials have permitted the analysis of the effect of the technology and of the experimental conditions of pyrolysis (especially particle size) on the kinetic results. It has been proven that the CSBR is especially suitable for the kinetic study of these materials, as it allows for obtaining an excellent gas−solid contact, which minimizes the limitations of heat and mass transfer and maintains bed isothermallity at high temperatures, within the temperature ranges and heating rates of interest for scaling-up. In the pyrolysis of small particles (between 0.1 and 0.8 mm), the apparent activation energy is 121.3 kJ mol^-1 and the corresponding frequency factor is 1.0 × 10⁶ s^-1. The effect of particle size is significant and shows the impossibility of totally avoiding the limitations of heat and mass transfer in the pyrolysis of these materials.