Thermal Analysis and Kinetic Study of Indian Almond Leaf by Model-Free Methods

ABSTRACT

Thermogravimetric analysis of Indian almond leaf was carried out at four different heating rates such as 5°C/min, 10°C/min, 15°C/min and 20°C/min. The kinetic study was performed using model free methods and the kinetic parameters were calculated by Kissinger, Friedman, KAS and FWO models. Thermogravimetric analysis resulted that the Indian almond leaf showed four stages of decomposition. Most of the mass loss occurred at stage II (188–460°C) owing to the simultaneous decomposition of cellulose, hemicellulose, and lignin. The shifting of pyrolysis curve occurred with increase of heating rate due to the limitation of heat transfer. The rate of mass loss decreased while increasing the heating rate due to the presence of more inert content i.e. ash and less volatile matters. The mean activation energy calculated by Kissinger, Friedman, KAS, and FWO showed as 52.67, 45.53, 73.73, and 72.28 kJ/mole. The mean activation energy of different leaves reported by earlier researcher was compared with the activation energy of Indian almond leaf and concluded that it stick to the range of activation energy of reported leaves.

摘要

在 5°C/min, 10°C/min, 15°C/min 和20°C/min 四种升温速率下对印度扁桃叶进行了热重分析. 动力学研究采用无模型方法,动力学参数采用 Kissinger, Friedman, KAS 和 FWO 模型计算. 热重分析结果表明,印度杏仁叶有四个阶段的分解. 由于纤维素, 半纤维素和木质素的同时分解,大部分质量损失发生在第二阶段(188°C-460°C). 由于传热的限制,热解曲线随升温速率的增大而发生移动. 由于存在更多的惰性成分,即灰分和较少的挥发性物质,随着加热速度的增加,质量损失率降低. Kissinger, Friedman, KAS 和FWO 计算的平均活化能分别为 52.67kj/摩尔, 45.53kj/ 摩尔, 73.73kj/ 摩尔和72.28kj/ 摩尔. 将前人报道的不同叶片的平均活化能与印度扁桃叶片的活化能进行了比较,得出结论:印度扁桃叶片的平均活化能符合报道的叶片活化能范围.

KEYWORDS:

• Thermal analysis
• kinetic study
• Indian almond leaf
• model-free methods
• thermogravimetric study
• pyrolysis

关键词::

• 热分析
• 动力学研究
• 印度杏仁叶
• 无模型方法
• 热重分析研究
• 热解

Nomenclature

TGThermogravimetry

DTGDerivative Thermogravimetry

KASKissinger – Akahira - Sonuse

FWOFlynn – Wall - Ozawa

APre-exponential factor

EActivation energy (kJ/mole)

RUniversal gas constant (J/mole K)

TAbsolute temperature (K)

T_mTemperature of maximum mass loss (K)

αFraction of conversion

βheating rate (°C/min)

m_iInitial mass (g)

m_aActual mass (g)

m_fFinal mass (g)