Advances in the pyrolysis of end-of-life tires: A critical review of reactor systems, process conditions and industrial applications

The growing environmental concerns and increasing volumes of end-of-life tires (ELT) have driven global interest in sustainable recycling solutions. Pyrolysis has emerged as a promising thermochemical process for converting waste tires into valuable materials, including tire pyrolysis oil (TPO), gas, and recovered carbon black. This review presents a comprehensive analysis of scientific literature and patents, focusing on reactor technologies, operating conditions, and innovations that influence product distribution and quality. The study explores key parameters – temperature, pressure, particle size, and residence time – highlighting their impact on pyrolysis efficiency and the characteristics of the resulting products. Particular attention is given to reactor design advancements, including fixed-bed, fluidized-bed, auger, rotary kiln, and stirred systems, as well as patent-driven innovations in heat transfer, mixing, and energy integration. Challenges related to the variability and quality of recovered carbon black and its integration into new tire manufacturing are critically assessed, with emphasis on the need for process optimization and post-treatment strategies to meet industrial carbon black standards and support circular tire manufacturing. • Review of ELT pyrolysis technologies, reactor types, and process parameters. • Optimal pyrolysis temperature (500–600 °C) maximizes oil yield and quality. • Short residence times favor oil yield, while longer times increase gas production. • Patent insights reveal trends in process zoning and energy integration. • Continuous operation and heat control remain major scale-up challenges.