Kinetic study of thermal processing of glycerol by thermogravimetry
Kinetic study of thermal processing of glycerol by thermogravimetry
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DOI：
10.1007/s10973-011-1730-3
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发表时间：
2011-06
影响因子：
4.4
通讯作者：
Margarida L. Castelló;J. Dweck;D. Aranda
中科院分区：
文献类型：
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作者：
Margarida L. Castelló;J. Dweck;D. Aranda
在过去的几年里，巴西生物柴油的产量显著增加，因为它在汽车用柴油的成分中被强制使用。因此，在最普通的生产过程中，每生产10亿升生物柴油就会产生10万吨甘油作为副产品。甘油已经被广泛研究。尽管如此，今天生产的数量需要新的用途，比如燃料。为此，作者研究了甘油的热加工动力学。本研究采用热重法（TG）、导数热重法（DTG）和差热分析法（DTA）提供实验数据。采用Kissinger方法计算了样品在开式和密封坩埚（带小孔）中从室温加热至600°C期间观察到的整体过程的动力学参数。采用Ozawa-Flynn-Wall和Blazejowski方法测定了加热过程中不同等转化条件下的热重数据。结果表明，甘油在常压下从30℃加热到600℃，不会发生简单的挥发。用这些方法计算的不同转化率下的活化能表明，只有当甘油的质量损失低于40%时才会发生挥发，而当转化率较高时，甘油还会发生部分热分解和/或解离。用Blazejowski基于范霍夫方程的另一种方法估计的挥发焓也证实了这些事实。
Over the past years, the production of biodiesel has significantly increased in Brazil due to its obligatory use in the composition of diesel for vehicle use. As a result, in the most ordinary processes, a hundred thousand tons of glycerol is produced as by-product per 1 billion liters of biodiesel. Glycerol has already been widely studied. Nonetheless, the quantity produced today demands new proposals for uses, such as a fuel. In this aim, the authors studied the kinetics of the thermal processing of glycerol. In this research, thermogravimetry (TG), derivative thermogravimetry (DTG), and differential thermal analysis (DTA) were used to provide the experimental data. Kinetic parameters were calculated by Kissinger method for the global process observed during the heating of the samples from the room temperature up to 600 °C, both in open and in sealed crucibles (with a little hole). Kinetic data were also determined at different isoconversion conditions during heating, by applying Ozawa–Flynn–Wall and Blazejowski methods to TG data. Results show that glycerol heated from 30 to 600 °C, under normal pressure, does not experience simple volatilization. The activation energies calculated at different conversion degrees by these methods show that only volatilization occurs when the mass loss of glycerol is lower than 40% and that for higher conversion degrees, partial thermal decomposition and/or dissociation of glycerol are occurring as well. These facts are also confirmed by the volatilization enthalpies estimated using another method developed by Blazejowski based on Van’t Hoff equation.