Production and Characterization of Recovered Carbon Black (rCB) by Waste Tire Pyrolysis as a Potential Carbon Black (CB) Substitute

Abstract

Recovered Carbon Black (rCB) from scrap tire pyrolysis offers a potential alternative to fossil-based virgin Carbon Black (CB) in the context of a circular economy. This study investigated the influence of pyrolysis process parameters on rCB yield and quality at laboratory and semi-industrial scales. The resulting rCBs were characterized and found to have surface and structural properties comparable to N500 and N600 series CBs, but with higher mineral and volatile contents. The quality of rCB is influenced by the feedstock composition, particularly the ratio of organic to inorganic components as well as key process parameters such as heating rate, pyrolysis temperature and residence time. Higher heating rates accelerate degradation and shift product distribution toward increased oil yield and reduced rCB formation, while higher pyrolysis temperatures lead to lower volatile content in rCB. Additionally, reactor and process design affect heat distribution, transfer efficiency, and mixing behavior, further shaping rCB properties. However, further testing is required to evaluate the actual in-rubber properties of rCBs. Therefore, additional tests are planned, incorporating rCB into butyl and nitrile rubber-based elastomer compounds, which will be addressed in a follow-up study. In addition, data from the current experiments will support a comprehensive Life Cycle Assessment (LCA) to evaluate the environmental impacts of tire pyrolysis and rCB production compared to other recycling methods, with details to follow in a future publication.

Keywords

Recycling / Chemical recycling / Waste tires / Recovered Carbon Black (rCB) / Carbon Black (CB) / Pyrolysis / Sustainability / Circular economy

Acknowledgments

We would like to express our sincere thanks to the team at the Metabolon Institute, especially for operating the experimental facilities that were essential for this study. We would also like to acknowledge the support of the Materials Laboratory team at TH Köln, whose contribution was crucial throughout the research process.

Author Contributions

S.B. led the conceptualization, original draft preparation and review & editing, with contributions from C.M. and D.K.-K. in conceptualization and supervision. Methodology, validation, formal analysis, investigation, data curation, and visualization were conducted by S.B., with assistance from E.K. Project administration and supervision were led by C.M. and D.K.-K.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

All data generated or analyzed during this study are available from the corresponding author upon reasonable request.

Funding

This research was conducted in collaboration with the Teaching and Research Centre metabolon, a joint initiative of TH Köln (University of Applied Sciences) and the Bergischer Abfallwirtschaftsverband (BAV). The research project “Pilot Bergische Rohstoffschmiede” was funded by the European Union’s European Regional Development Fund (ERDF) under the EFRE.NRW 2021–2027 program.

Declaration of Competing Interest

Sebastian Bogdahn reports a relationship with Schwalbe—Ralf Bohle GmbH that includes: employment. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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