Truck Tyre Characterisation and Kinetic Mechanism Study for Valuable Chemicals Production

Waste tyre pyrolysis is a promising strategy for converting end-of-life tyres into valuable chemical feedstocks. This study investigates the thermal degradation behaviour of truck tyre (TT) crumbs and evaluates the selective production of high-value compounds, particularly limonene and indene, under varying pyrolysis conditions. A combined approach employing thermogravimetric analysis, kinetic modelling (both model-free and model-fitting methods), and analytical pyrolysis coupled with gas chromatography-mass spectrometry (Py-GC/MS) was used to elucidate the relationship between temperature, heating rate, and product selectivity. Activation energy estimates ranged from 122 to 145 kJ.mol-1 across different kinetic models, indicating a multi-step degradation mechanism. The highest limonene selectivity (64.2%) was achieved at 400°C, but this declined to 28.5% at 700°C due to secondary cracking and aromatisation reactions. Additionally, faster heating rates enhanced limonene yield, with selectivity increasing from 30.8 % at 20 °C /min to 42.7% at 100 °C /min. these results highlight the importance of optimising thermal parameters to favour the formation of target chemical and provide essential kinetic and chemical data for the design of tyre pyrolysis systems focussed on selective product recovery.