Improvement of charcoal yield by two-step pyrolysis on eucalyptus wood: A thermogravimetric study

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• 作者：Khalid Elyounssi^a ; ^{k.younssi71@gmail.com} ; Franç ; ois-Xavier Collard^b ; Jean-aim&eacute ; Ngollo Mateke^b ; Joë ; l Blin^b ; ^c
• 关键词：Two-step pyrolysis ; Char yield ; Eucalyptus ; Wood constituents ; Interaction
• 刊名：Fuel
• 出版年：2012
• 期刊代码：33_00162361
• 类别：ce
• 出版时间：June, 2012
• 卷：96
• 期：Complete
• 页码：161-167
• 文件大小：500 K

摘要

In previous work, we showed that two-step biomass pyrolysis, consisting of a first low temperature step (T = 360 掳C, so a low actual heating rate) until the mass loss of the solid reached approximately 50%, followed rapidly by a high temperature step (T > 600 掳C, so a high actual heating rate) led to optimize charcoal yields with values of up to 40%. In this paper, we describe thermogravimetric analysis studies on eucalyptus wood and its three constituents, i.e. cellulose, xylan and lignin, in order to explain the phenomena behind these results. Two-step pyrolysis experiments were conducted in a TGA oven up to 900 掳C with a first slow pyrolysis step at a low heating rate of 2 掳C min^鈭?, followed by a fast pyrolysis step with a heating rate of 100 掳C min^鈭?. Char yields from eucalyptus wood were increased from 18.8%, for the simple 2 掳C min^鈭? pyrolysis, up to 22.8%when the heating rate change was operated at a temperature of 360 掳C. Char yield from cellulose was also increased, though only very slightly, when the heating rate was changed in the 330-360 掳C temperature range. Conversely, char yield obtained from xylan and lignin in two-step pyrolysis was always lower than that obtained by simple 2 掳C min^鈭? pyrolysis.

It appeared from this work that two-step pyrolysis of the eucalyptus sample could not be regarded and described as the result of the sum of the pyrolysis of its constituents. There was a matrix effect with interactions that promoted char formation during two-step pyrolysis.