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<p>The kinetic behavior and combustion characteristics of orange-tree pruning, olive-tree pruning, almond shell, pistachio shell, and pine-tree pruning, were investigated using thermogravimetric analysis (TGA) under inert and oxidative atmospheres at heating rates of 5–20&#xa0;°C/min. The study combined model-free kinetic methods (Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Friedman) with the Coats–Redfern reaction model to elucidate kinetic parameters and reaction mechanisms. Distinct thermal decomposition stages were observed, corresponding to the sequential degradation of hemicellulose, cellulose and lignin. The differences in the profiles were strongly linked to the lignocellulosic composition of the materials. Almond and pistachio shells, with higher hemicellulose contents, exhibited earlier devolatilization and marked peak of hemicellulose, while pine and orange and olive-tree pruning showed single, well-defined peaks around 320–380&#xa0;°C, reflecting the dominant decomposition of crystalline cellulose. The ignition and burnout temperatures of the selected materials were analyzed by using referencing methods, showing variations depending on the biomass type, heating rate and method used, with pistachio and almond shells demonstrating higher burnout temperatures compared to the other materials. Then, model-free methods (Flynn–Wall–Ozawa FWO, Kissinger–Akahira–Sunose KAS and Friedman FR) were used to determine activation energies, while the Coats-Redfern method provided insights into the reaction mechanism. In pyrolysis, activation energies (E<sub>a</sub>) increased with the conversion level (α), indicating a dependency on the decomposition stage; for example, for orange-tree pruning, E<sub>a</sub> rose from 77.88&#xa0;kJ&#xa0;mol<sup>−1</sup> at α = 0.1 to 246.58&#xa0;kJ&#xa0;mol<sup>−1</sup> at α = 0.9 (FWO). The application of the Coats-Redfern method reveals distinct reaction mechanisms across biomass components, with diffusional models (D-series) providing the best fit for moisture removal and hemicellulose decomposition, while F-series models effectively capture the complexity of cellulose and lignin degradation.</p>

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Thermal Decomposition of Various Biomass Samples in Inert and Oxidative Atmospheres: Kinetic Models and Process Parameters

  • 期刊论文

  • 发表日期：

    2025年12月17日

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  • E.J. Lozano,
  • M. A. Martín-Lara,
  • S. Pérez-Huertas,
  • M. Calero

摘要

The kinetic behavior and combustion characteristics of orange-tree pruning, olive-tree pruning, almond shell, pistachio shell, and pine-tree pruning, were investigated using thermogravimetric analysis (TGA) under inert and oxidative atmospheres at heating rates of 5–20 °C/min. The study combined model-free kinetic methods (Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Friedman) with the Coats–Redfern reaction model to elucidate kinetic parameters and reaction mechanisms. Distinct thermal decomposition stages were observed, corresponding to the sequential degradation of hemicellulose, cellulose and lignin. The differences in the profiles were strongly linked to the lignocellulosic composition of the materials. Almond and pistachio shells, with higher hemicellulose contents, exhibited earlier devolatilization and marked peak of hemicellulose, while pine and orange and olive-tree pruning showed single, well-defined peaks around 320–380 °C, reflecting the dominant decomposition of crystalline cellulose. The ignition and burnout temperatures of the selected materials were analyzed by using referencing methods, showing variations depending on the biomass type, heating rate and method used, with pistachio and almond shells demonstrating higher burnout temperatures compared to the other materials. Then, model-free methods (Flynn–Wall–Ozawa FWO, Kissinger–Akahira–Sunose KAS and Friedman FR) were used to determine activation energies, while the Coats-Redfern method provided insights into the reaction mechanism. In pyrolysis, activation energies (Ea) increased with the conversion level (α), indicating a dependency on the decomposition stage; for example, for orange-tree pruning, Ea rose from 77.88 kJ mol−1 at α = 0.1 to 246.58 kJ mol−1 at α = 0.9 (FWO). The application of the Coats-Redfern method reveals distinct reaction mechanisms across biomass components, with diffusional models (D-series) providing the best fit for moisture removal and hemicellulose decomposition, while F-series models effectively capture the complexity of cellulose and lignin degradation.