Kinetics of scrap tyre pyrolysis under fast heating conditions

The kinetics of scrap tyre pyrolysis has been studied by means of thermogravimetry (runs at constant temperature and following temperature ramps) and using a fast heating microreactor. The advantages of the microreactor for obtaining kinetic data at higher temperatures (in the 773-973 K range) than those corresponding to thermogravimetry and under conditions similar to those of continuous large-scale reactor are clearly shown. The validity of the kinetic parameters determined (E = 98.6 kJ mol−1 and k0 = 7.35 × 104 s−1) will only be restricted by unavoidable heat and mass transfer limitations, which have been minimized by using a particle size smaller than 0.2 mm. The kinetic results are evidence, on the one hand, of the limitations of these laboratory techniques for the kinetic study and, on the other, of the inherent heat and mass limitations of this material. Through monitoring by gas chromatography, the kinetics of formation of hydrocarbon products has been determined. These products are interesting as raw materials for petrochemistrical industry (mainly light olefins and aromatics) and for the synthesis of basic materials in tyre manufacturing (isoprene and 1,3-butadiene).