Decomposition and carbonisation of wood biopolymers - a microstructural study of softwood pyrolysis
Decomposition and carbonisation of wood biopolymers - a microstructural study of softwood pyrolysis
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DOI：
10.1016/j.carbon.2004.08.034
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发表时间：
2005-01-01
期刊：
影响因子：
10.9
通讯作者：
Zickler, GA
中科院分区：
文献类型：
--
作者：
Paris, O;Zollfrank, C;Zickler, GA
在298 K ~ 1673 K的温度范围内，对针叶木（云杉和松木）的热解进行了研究。2 K/min的加热速率和薄木材的使用使人们能够完全保留原始的蜂窝状木材结构，而不会形成裂缝。利用广角X射线散射、小角X射线散射和拉曼光谱研究了木材生物聚合物的热降解以及碳质材料的原子/分子和介观结构的演变。各向同性和几乎无结构的材料标记了580 K和620 K之间的明显过渡区域，其中纤维素微纤丝的晶体结构完全降解，并且基于纤维素微纤丝和多糖/木质素之间的密度差的散射对比度完全消失。在木材纳米复合材料结构完全分解后，炭化过程开始形成芳香族结构，并且在小角度处强烈增加的散射信号指示纳米孔的形成和生长。相对于材料的定向蜂窝结构，发展中的石墨烯片显示出轻微的优选取向。它的结论是独特的纤维素在天然木材细胞壁中的微纤维取向可能会影响碳质材料，在最近的预测在文献中。(C)2004 Elsevier Ltd.保留所有权利。
Pyrolysis of softwood (spruce and pine) is investigated in the temperature range between 298 K and 1673 K within narrow intervals. A heating rate of 2 K/min and the use of thin wood sections allow one to fully preserve the original cellular wood structure without the formation of cracks. Thermal degradation of the wood biopolymers and evolution of the atomic/molecular and mesoscopic structure of the carbonaceous material is studied by wide-angle X-ray scattering, small-angle X-ray scattering and Raman spectroscopy. An isotropic and almost structureless material marks a clear transition region between 580 K and 620 K, where the crystal structure of the cellulose microfibrils is completely degraded and the scattering contrast based on the density difference between cellulose microfibrils and polyoses/lignin has fully disappeared. After the complete decomposition of the wood nanocomposite structure, the charring process commences with the formation of aromatic structures, and a strongly increasing scattering signal at small angles indicates the formation and growth of nanopores. The developing graphene sheets show a slight preferred orientation with respect to the oriented cellular structure of the material. It is concluded that the unique microfibril orientation of cellulose in the native wood cell wall might affect the carbonaceous material, in agreement with recent predictions in the literature. (C) 2004 Elsevier Ltd. All rights reserved.