Catalytic Upgrading of Pyrolysis Products from End-of-Life Mining Tires: A Systematic Review of Research Gaps, Process Integration Challenges, and Future Directions

End-of-life mining tires represent a major waste management challenge due to their large mass, high sulfur content, and complex construction. This review critically evaluates catalytic upgrading strategies for pyrolysis products derived from mining and heavy-duty tires, with emphasis on sulfur chemistry, catalyst deactivation, process integration, and commercialization barriers. A systematic literature review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) framework was conducted using Scopus, Web of Science, ScienceDirect, SpringerLink, and Google Scholar, covering publications from 2000 to 2026. The analysis demonstrates that mining tires differ substantially from passenger tires in sulfur content, steel reinforcement, ash-forming additives, and thermal behavior, resulting in more severe catalyst poisoning, heat-transfer limitations, and upgrading requirements. Current studies predominantly focus on short-term improvements in product quality while neglecting catalyst stability, regeneration, sulfur tolerance, and industrial operating conditions. Ex situ catalytic vapor upgrading shows greater potential than upgrading because of improved catalyst protection, operational flexibility, and scalability. The review identifies critical research gaps in sulfur-resistant catalyst development, long-duration catalyst stability assessment, reactor–catalyst integration, pilot-scale validation, techno-economic analysis, and life-cycle sustainability evaluation. Based on these findings, a future research framework is proposed comprising five strategic pillars: (i) development of sulfur-tolerant and regenerable catalyst systems, (ii) long-term catalytic performance and deactivation studies under industrially relevant conditions, (iii) integrated reactor and upgrading system optimization, (iv) pilot-scale demonstration of continuous processing technologies, and (v) comprehensive techno-economic and environmental assessments. Future lines of enquiry should focus on sulfur transformation pathways, catalyst regeneration mechanisms, advanced desulfurization strategies, heat and mass transfer optimization in mining tire reactors, and circular economy integration through the simultaneous recovery of fuels, chemicals, recovered carbon black, steel, and sulfur-containing products. Collectively, these research priorities provide a roadmap for advancing sustainable mining tire valorization and accelerating the commercialization of catalytic pyrolysis technologies within a circular economy framework.