Herstellung und ökologische Bewertung hochwertiger Karbonisate aus der Altreifen-Pyrolyse

In the context of the transition from a linear to a circular economy, this dissertation investigates the pyrolysis of scrap tires as a technically and environmentally viable recycling option. The primary objective is to quantify the substitution potential of the pyrolysis products coke and oil, as well as carbon black produced from pyrolysis oil, in comparison to conventional carbon black. In addition, the feasibility of pyrolysis as a complementary technology for expanding urgently needed recycling capacities is assessed from a technical, economic, and environmental perspective alongside established recovery pathways, including mechanical recycling, thermal treatment, and retreading.

As existing approaches to the environmental assessment of tire pyrolysis are not standardized and involve considerable uncertainties, an integrated modeling framework was developed that links a technology-specific process model of pyrolytic conversion with a life cycle assessment model. Based on validated primary data from semi-industrial experiments conducted in a rotary kiln at the :metabolon Institute of TH Köln, the assessment shows that pyrolysis coke can reduce greenhouse gas emissions by approximately 80 % compared to conventional carbon black. Carbon black produced from pyrolysis oil processing achieves a 3 % emission reduction compared to fossil-based carbon black and, due to its enhanced product quality, offers greater circularity potential than pyrolysis coke. From a recovery perspective, pyrolysis demonstrates the most favorable climate performance compared to mechanical recycling and thermal treatment, surpassed only by the hierarchically preferred retreading process.

The modeling results further indicate that a complete substitution of conventionally produced carbon black with pyrolysis coke could, in the long term, reduce the global emission level of the carbon black industry by up to 80 %. However, achieving this potential requires overcoming existing quality differences between pyrolysis coke, carbon black derived from pyrolysis oil, and conventional carbon black, which are already being addressed through targeted post-treatment processes for pyrolysis coke. In the interim, the use of blends comprising all three materials provides a practical strategy to significantly improve the overall greenhouse gas balance.

The developed integrated model provides a transferable methodological framework that demonstrates how the coupling of process and life cycle assessment models can serve as a basis for the environmental optimization of industrial systems within the circular economy.