济南大学. 材料科学与工程学院，山东 济南 250022
胡勋，范梦娇. 热解温度和热解停留时间对半焦性质的影响［J］. 中国粉体技术，2025，31（4）：1-9.
HU Xun， FAN Mengjiao. Effects of pyrolysis temperature and residence time on char properties［J］. China Powder Science and Technology，2025，31（4）：1−9.
DOI：10.13732/j.issn.1008-5548.2025.04.013
收稿日期：2024-10-30，修回日期：2025-04-15，上线日期：2025-05-29。
基金项目：国家自然科学基金项目，编号：52276195。
第一作者简介：胡勋（1983—），男，教授，博士，博士生导师，泰山学者，研究方向为固废高值化利用。E-mail：Xun. Hu@outlook. com。
摘要：【目的】为了满足不同领域对半焦性能的需求，分析不同热解参数下半焦的理化性质，实现特定功能的半焦的定制。【方法】分别在热解温度为 250、350、450、550、650、750 ℃时对棉花纤维和桃木 2种原料进行热解，制备一系列半焦，以研究典型生物质衍生的半焦性质随热解温度变化的规律；固定热解温度为350 ℃，设置不同热解停留时间对2种原料进行热解，探究不同热解停留时间对半焦性质的影响。【结果】在热解温度为350 ℃时，棉花纤维和桃木2种原料会发生碳化作用，在此温度下延长热解停留时间可以促进原料中纤维素的热解但是无法破坏原料中木质素的共轭结构；棉花纤维和桃木中的有机物会在较高的热解温度下发生更剧烈的脱氧、脱氢以及芳构化反应，使制备得到的半焦的石墨化程度较高；原位红外结果表明，棉花纤维和桃木中的—OH官能团和脂肪族C—H官能团的强度在测试温度为300~400 ℃时达到最大值，随后 2种原料通过发生脱水和脱氢反应，促进了半焦中 C＝O，＝C—H，C＝C以及芳香族 C—O—C官能团的形成。【结论】半焦表面的官能团分布对热解温度以及热解停留时间有明显的响应，可以通过调控热解参数来选择性定制具有特定功能的半焦。
关键词：生物质衍生物；半焦；热解温度；热解停留时间
Objective Pyrolysis is an important way to convert biomass into char， but the complex reaction network of the pyrolysis process makes it challenging to control the properties of the resulting char. Studies have shown that temperature, among all the parameters, is the main factor affecting pyrolysis reactions, followed by residence time. This study focuses on the correlation between char properties and pyrolysis temperature and time by conducting pyrolysis experiments on cotton fiber and peach wood at temperatures from 250 to 750 ℃ and at 350 ℃ for various residence times.
Methods The synthesis of char was conducted in a fixed-bed reactor within a tube furnace under a nitrogen (N2) atmosphere, with a flow rate maintained at 60 mL/min. 2 g of biomass was placed in a quartz tube. Before heating, N2 was introduced to establish an inert environment within the reactor. The tube furnace was heated to 250, 350, 450, 550, 650, and 750 ℃ at a temperature ramping rate of 10 ℃/min, and then held at the target temperature for 30 min. Upon completion of the heating process, the reactor was immediately removed from the furnace and quenched. In addition, to further investigate the effects of residence time, the pyrolysis time was extended to 60, 90, 120, and 180 min at 350 ℃.
Results and Discussion The cracking of cellulose was observed at 350 ℃, while the rigid structure of lignin stayed stable at this temperature. X-ray diffraction (XRD) results showed that the char generated from the pyrolysis of cotton fiber and peach wood at both 350 ℃ or 650 ℃ was primarily amorphous carbon. The char derived from peach wood had a higher degree of graphitization. The original biological structure could be preserved even after extended exposure at 350 ℃, whereas increasing the temperature to 650 ℃ led to the fracture of the structural framework. Elemental analysis and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results indicated that high temperatures enhanced aromatization by promoting dehydration, dehydrogenation, and deoxygenation reactions. The abundance of —OH and aliphatic C—H groups reached a maximum at 300~400 ℃, then decreased monotonically via dehydration and dehydrogenation. This process accelerated the formation of C＝O, C—H, C＝C, and aromatic C—O—C bonds.
Conclusions and Prospects Extending the residence time at 350 ℃ can accelerate the carbonization process by promoting the cracking of oxygen-containing functional groups in cellulose. However, the temperature is insufficient to drive further condensation to form aromatic ring structures. Although 350 ℃ is not high enough to destroy the rigid structure of lignin, prolonging the exposure time at this temperature enhances the dehydrogenation reaction. Higher temperatures accelerate both carbonization and aromatization processes. This results in a continuous increase in the abundance of C＝C and C—O—C bonds at the expense of the —OH， C—H， and C＝O functional groups. The study provides theoretical guidance for customizing char with specific functional groups.
Keywords：biomass derivatives; char; pyrolysis temperature; residence time
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