Key Takeaways & Executive Findings
- •• • Fraser-Suzuki deconvolution resolves waste tire pyrolysis into four pseudo-components with activation energies of 118.21, 202.60, 231.98, and 251.97 kJ/mol, enabling precise temperature-zone control in reactor design. • • The asymmetric peak-fitting capability of Fraser-Suzuki achieves R²=0.998, significantly outperforming symmetric functions (Gaussian, Lorentzian, Weibull) for complex overlapping reactions, ensuring reliable kinetic parameter extraction. • • Pyrolysis primarily occurs in the 573–773 K range, with higher heating rates inducing a thermal lag effect (TG/DTG shift to higher temperatures), critical for scaling up from lab to industrial reactors. • • Overall and stage-wise kinetic methods fail to capture the complexity of waste tire pyrolysis; Fraser-Suzuki deconvolution provides a mechanistic breakdown essential for optimizing product yields (e.g., oil up to 41.10%) and char quality.
Abstract
Waste tire pyrolysis has emerged as a leading treatment technology due to its broad applicability, high resource recovery efficiency, and low environmental pollution. This study employs thermogravimetric analysis to investigate the influence of heating rate on pyrolysis characteristics and systematically analyzes reaction kinetics across three scales: overall reaction, weight-loss stages, and Fraser-Suzuki deconvolution. The Fraser-Suzuki function, with its asymmetric peak-fitting capability, outperforms conventional methods in describing the complex continuous reaction, achieving superior fit accuracy (R²=0.998). Deconvolution resolves the pyrolysis into four pseudo-components: additives, natural rubber, synthetic rubber, and high-temperature residual reactants, with average activation energies of 118.21, 202.60, 231.98, and 251.97 kJ/mol, respectively. The study provides critical theoretical support for temperature-zone control and reactor design optimization in waste tire pyrolysis technologies.
1. Introduction
Waste tire accumulation poses a severe environmental challenge, with annual production exceeding 3.3 billion units (over 10 million tons) in China alone, growing at 6–8% per year. Conventional disposal methods—landfilling, incineration, and direct reuse—are increasingly untenable due to space constraints, pollutant emissions, and low resource recovery. Pyrolysis, conducted under oxygen-free conditions, offers a promising alternative by converting organic components into valuable products: pyrolysis gas, bio-oil, and carbon black. Recent studies demonstrate that fluidized-bed pyrolysis can achieve liquid yields up to 41.10%, enriching high-value chemicals like D-limonene and isoprene, while producing char with potential to replace commercial carbon black. However, the inherent complexity of tire composition—natural rubber, synthetic rubbers (SBR, BR), carbon black, and additives like sulfur and zinc oxide—results in overlapping, non-homogeneous reactions that challenge conventional kinetic analysis.
Existing kinetic models often oversimplify the process, treating it as a single overall reaction or discrete weight-loss stages, leading to inaccurate predictions and suboptimal reactor design. Advanced deconvolution techniques, particularly the Fraser-Suzuki function, address this bottleneck by separating overlapping reactions into individual pseudo-components. This study systematically applies multi-scale kinetic analysis—overall, stage-wise, and deconvoluted—to waste tire pyrolysis, demonstrating that Fraser-Suzuki deconvolution provides superior fit accuracy (R²=0.998) and yields distinct activation energies for each pseudo-component. These findings enable precise temperature-zone control and reactor optimization, directly supporting the engineering scale-up of waste tire pyrolysis technologies.
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WU Rui, LUO Guanqun, MA Ruoyu, TAO Xuan (2026). Multi-scale reaction kinetic characteristics of waste tire pyrolysis. Journal of Environmental Engineering Technology. https://doi.org/10.13205/j.hjgc.202607008
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Frequently Asked Questions
How does the Fraser-Suzuki deconvolution method handle overlapping reactions compared to symmetric functions, and what is the practical impact on kinetic parameter accuracy?
Fraser-Suzuki's asymmetric peak shape captures shoulder and tailing peaks that symmetric functions (Gaussian, Lorentzian, Weibull) miss, achieving R²=0.998 versus lower fits for symmetric functions. This precision yields distinct activation energies for each pseudo-component (118.21–251.97 kJ/mol), enabling accurate prediction of reaction behavior across temperature zones, which is critical for reactor design and process control.
What is the thermal lag effect observed at higher heating rates, and how does it influence industrial reactor operation?
As heating rate increases, TG and DTG curves shift to higher temperatures, indicating thermal lag. This means that in industrial reactors, faster heating may require higher set-point temperatures to achieve the same conversion, affecting energy consumption and product distribution. The study identifies the main pyrolysis zone as 573–773 K, guiding optimal temperature programming.
How do the activation energies of individual pseudo-components compare to the overall activation energy, and why is this distinction important?
The overall activation energy (207–228 kJ/mol) is an average that masks the distinct behaviors of additives (118.21 kJ/mol), natural rubber (202.60 kJ/mol), synthetic rubber (231.98 kJ/mol), and high-temperature residuals (251.97 kJ/mol). This distinction is crucial for designing staged pyrolysis processes to selectively recover high-value products or optimize char properties.
What are the limitations of the Fraser-Suzuki deconvolution method, and how might they affect industrial application?
The method assumes independent pseudo-components and ignores interactions between them, which may not hold in real tire mixtures. This simplification could lead to inaccuracies in predicting product yields or char composition. Future work should incorporate detailed sample characterization and mechanistic studies to refine the model.
How does this study support the scale-up of waste tire pyrolysis from laboratory to industrial scale?
By providing activation energies and kinetic models for each pseudo-component, the study enables reactor design with precise temperature control, ensuring complete decomposition of all components. The thermal lag data guide heating rate selection to balance throughput and energy efficiency, while the deconvolution approach can be integrated into process simulation software for predictive modeling.
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