LAUSR

Thermal pyrolysis of scrap truck tires was carried out in a semi-batch fixed reactor at 500 °C. The pyrolysis mechanism and product yields were investigated in this study. We aimed to elucidate the effects of key parameters including the evolution of intern reactor temperature, volatile products residence time and reactor free volume on the quantity and quality of liquid products, which has been rarely discussed in the literature. Upon use of carrier gas, the pyrolysis liquid yield was improved considerably, showing a decreased extent for secondary cracking of primary volatiles however bigger empty volume and longer residence time promote its extending. High value-added products such as d-limonene, p-cymene, and BTX were identified in the pyrolysis liquid. Subsequently, the formation mechanisms of these compounds of interest via Diels–Alder mechanism involving cyclization, aromatization, and dehydrogenation reactions were characterized. However, the most abundant product was d-limonene, which had been competed with the p-cymene regardless of the degradation pathway and secondary reactions extent.