Patil Yogesh, Ku Xiaoke, Vasudev Vikul
Department of Engineering Mechanics, Zhejiang University, 310027 Hangzhou, China.
State Key Laboratory of Clean Energy Utilization, Zhejiang University, 310027 Hangzhou, China.
ACS Omega. 2023 Sep 15;8(38):34938-34947. doi: 10.1021/acsomega.3c04328. eCollection 2023 Sep 26.
Torrefaction influences the structural and physicochemical properties of biomass, thus further altering its thermal degradation behavior. In this study, the pyrolysis characteristics, reaction kinetics, and thermodynamic parameters of raw and torrefied Chinese fir (CF) were investigated. The torrefaction was conducted at 220 °C (mild) and 280 °C (severe), the pyrolysis was performed from ambient temperature to 600 °C, and four different heating rates (i.e., 5, 15, 25, and 35 °C/min) were adopted. The activation energy for pyrolysis was estimated by adopting three isoconversional methods. The master-plot method was employed to analyze the reaction mechanism. Furthermore, thermodynamic parameters, i.e., the enthalpy change (Δ), Gibbs free energy change (Δ), and entropy change (Δ), were calculated. The average activation energy increased with the torrefaction temperature, whose values estimated by using different methods ranged from 88.57 to 97.70, from 121.04 to 126.35, and from 167.51 to 179.74 kJ/mol for raw, mildly, and severely torrefied CF samples, respectively. A compensation effect between the activation energy and pre-exponential factor was observed for all samples. The degradation process was characterized as endothermic, involving the formation of activated complexes and requiring extra energy for torrefied samples.
烘焙会影响生物质的结构和物理化学性质，从而进一步改变其热降解行为。在本研究中，对未烘焙和烘焙后的杉木（CF）的热解特性、反应动力学和热力学参数进行了研究。烘焙在220℃（轻度）和280℃（重度）下进行，热解从室温进行到600℃，并采用了四种不同的加热速率（即5、15、25和35℃/分钟）。通过采用三种等转化率方法估算热解的活化能。采用主曲线法分析反应机理。此外，还计算了热力学参数，即焓变（Δ）、吉布斯自由能变（Δ）和熵变（Δ）。平均活化能随烘焙温度的升高而增加，使用不同方法估算的值分别为：未烘焙、轻度烘焙和重度烘焙的CF样品，其值范围分别为88.57至97.70、121.04至126.35和167.51至179.74kJ/mol。所有样品均观察到活化能和指前因子之间的补偿效应。降解过程的特征为吸热，涉及活化络合物的形成，并且烘焙样品需要额外的能量。
