Valorisation of Waste Tyre via Pyrolysis: Advances and Perspectives

Abstract

This paper first reviews the serious environmental concerns and waste management due to the rapid increase in the vast quantity of waste tyre globally. It then articulates the importance of pyrolysis as an attractive technical route for valorising waste tyre. A systematic summarisation on pyrolysis reaction chemistry is presented, including those for both waste tyre and its individual components. The key factors, including feedstock properties, reactor configurations, and reaction conditions that influence the properties and distribution of pyrolysis products and transformation and fate of impurities, are discussed. Such knowledge is essential to selecting operating parameters for optimal pyrolysis products and process performance. Potential applications of waste tyre pyrolysis products (i.e., char, oil, and gas) are subsequently surveyed and summarised. The important roles of key impurities (especially sulfur) and their derivatives, which are major constraints for commercialisation of waste tyre pyrolysis technologies, are also discussed. Remediation strategies of these impurities in pyrolysis products are summarised, compared, and benchmarked. The recent progress in process development, techno-economic analysis, and life cycle analysis of waste tyre pyrolysis processes is also covered. In closing, the remaining challenges and research gaps in the field of waste tyre pyrolysis are identified and future research perspectives are outlined.