(390au) Scalable Processing of Waste Tires Using Pyrolysis

The rapid growth of the automotive and transportation industry has significantly increased the production of waste tires (WTs). It has been reported that 1.5 billion WTs are produced worldwide per year. China and the United States are the two leading producers of WTs, together accounting for over half of the world total scrap tires [1]. In many countries, WTs generated are processed through material and energy recovery methods. However, significant quantities accumulate in landfills or open areas, which use significant land [2].

Pyrolysis is a promising thermochemical recycling alternative for WTs [3]. This thermochemical process enables production and recovery of components of WTs for reconversion into primary building blocks [4]. Specifically, synthetic and natural rubber can be degraded as hydrocarbon vapors, enabling their separation from the carbon black contained in the raw material. These components can be further processed to obtain value-added products. However, the operating conditions of the process and the type of WTs used strongly affect product yields and overall process economics [1].

A techno-economic analysis (TEA) of a WTs pyrolysis process has been previously reported in the literature [5]; the analysis assumed stable operational conditions, WTs with fixed compositions, and constant selling prices. In this work, we extend this analyses by broadening the system boundaries and considering a wider range of operating conditions to evaluate the feasibility of the process. To effectively address the significant uncertainties related to WT composition, technology scalability, pyrolysis product distributions, and fluctuations in market prices for recovered products (carbon black, diesel, and low fuel oil), we integrate rigorous process models and uncertainty/sensitivity analyses with a detailed TEA implemented in BioSTEAM, an open-source process simulation platform [6,7]. The framework quantifies the impact of myriad uncertainties through rigorous thermodynamic simulation and detailed kinetic modeling of the pyrolysis reactor [8,9], which has validated using real industrial data. Additionally, the pyrolysis process involves units with operating conditions that can pose safety concerns; as such, we also conducted a detailed safety analysis of the process.

The key findings reveal that the pyrolysis process can be a cost-effective and safer approach for producing activated carbon from WTs. This contrasts with traditional designs that prioritize maximizing the production of pyrolysis gas over solid products. The analysis also demonstrates that the process can be profitable amid various operational and market uncertainties, positioning it as a viable waste recycling method.

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(2) Martínez, J. D.; Sanchís, A.; Veses, A.; Kapf, A.; L ópez, J. M.; Callén, M. S.; García, T.; Murillo, R. Waste-based value-added feedstocks from tire pyrolysis oil distillation: defossilization of the petrochemical industry. Green Chem 2025, 27, 670–683, https://doi.org/10.1039/D4GC05185H.

(3) Campuzano, F.; Martínez, J. D.; Agudelo Santamaría, A. F.; Sarathy, S. M.; Roberts, W. L. Pursuing the end-of-life tire circularity: An outlook toward the production of secondary raw materials from tire pyrolysis oil. Energy & Fuels 2023, 37, 13, 8836–8866, https://doi.org/10.1021/acs.energyfuels.3c00847.

(4) Martínez, J. D.; Sanchís, A.; Veses, A.; Callén, M. S.; López, J. M.; García, T.; Murillo, R. Design and operation of a packed pilot scale distillation column for tire pyrolysis oil: Towards the recovery of value-added raw materials. Fue, 2024, 358, 130266. https://doi.org/10.1016/j.fuel.2023.130266

(5) Bi, R.; Zhang, Y.; Jiang, X.; Yang, H.; Yan, K.; Han, M.; Li, W.; Zhong, H.; Tan, X.; Xia, L.; Sun, X.; Xiang, S. Simulation and techno-economical analysis on the pyrolysis process of waste tire. Energy 2022, 260, 125039. https://doi.org/10.1016/j.energy.2022.125039

(6) Cortes-Peña, Y.; Kumar, D.; Singh, V.; Guest, J. S. BioSTEAM: A Fast and Flexible Platform for the Design, Simulation, and Techno-Economic Analysis of Biorefineries under Uncertainty. ACS Sustainable Chem. Eng. 2020, 8 (8), 3302–3310. https://doi.org/10.1021/acssuschemeng.9b07040.

(7) Cortés-Peña, Y. Thermosteam: BioSTEAM’s Premier Thermodynamic Engine. JOSS 2020, 5 (56), 2814. https://doi.org/10.21105/joss.02814.

(8) Cao, Y.; Taghvaie, A. N.; Sarkar, S. Modelling and simulation of waste tire pyrolysis process for recovery of energy and production of valuable chemicals (BTEX). Scientific Reports 2023, 13. https:// doi.org/ 10.1038/s41598-023-33336-3

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