Pursuing the End-of-Life Tire Circularity: An Outlook toward the Production of Secondary Raw Materials from Tire Pyrolysis Oil

Pyrolysis is perceived as the missing link between the management of end-of-life tires (ELTs) and the tire industry because it strikes directly in the transition from a linear to a circular economy model and toward the defossilization of diverse economic sectors. Tire pyrolysis oil (TPO) is one of the most valuable and interesting fractions derived from the pyrolysis of ELTs. It contains valuable chemicals including, among others, benzene, toluene, ethylbenzene, and xylene, as well as limonene, which are some of the building blocks of the petrochemical industry. Within the circular economy framework, traditional practices such as the direct use of TPO in combustion systems seem to exhibit a low circularity degree. Instead, the production of secondary raw materials that can be reused for multiple purposes associated with the petrochemical industry is getting special attention. Based on the above, this work aims at reviewing different pathways currently explored in the scientific community to produce various value-added products from TPO. Due to the similarity of its properties with those of petroleum streams, the coprocessing of TPO using existing units in conventional refineries exhibits a massive potential. In this manner, the properties of the derived products can be fine-tuned according to the hydrocarbons and petrochemical market requirements. As such, discussed are the advantages, recent progress, and challenges in the implementation of conventional refinery practices such as distillation, fluid catalytic cracking (FCC), hydroprocessing, and steam cracking for TPO post-treatment. These processes are seen as the path to integrate TPO in the current hydrocarbon/petrochemical market.