文献类型：期刊文献

中文题名：木质素与纤维素热解炭结构特性对其高温石墨化过程的影响机制

英文题名：The mechanism of the structural characteristic of the chars pyrolyzed from lignin and cellulose on their graphitization processes under high temperatures

作者：陈超[1] 杨梦梅[2] 孙康[1] 毕海明[3] 王傲[1] 刘颖[1] 徐茹婷[1]

第一作者：陈超

机构：[1]中国林业科学研究院林产化学工业研究所,生物质化学利用国家工程实验室,江苏省生物质能源与材料重点实验室,南京210042;[2]南京林业大学化学工程学院,南京210037;[3]千年舟新材科技集团股份有限公司,杭州311100

年份：2022

卷号：7

期号：6

起止页码：124-131

中文期刊名：林业工程学报

外文期刊名：Journal of Forestry Engineering

收录：CSTPCD;;北大核心:【北大核心2020】；CSCD:【CSCD_E2021_2022】；

基金：国家自然科学基金(31770629);江苏省生物质能源与材料重点实验室项目(JSBEM-S-202101)。

语种：中文

中文关键词：石墨化;纤维素;木质素;热解炭;结构重构建

外文关键词：graphitization;cellulose;lignin;pyrolytic char;structural reconstruction

分类号：TQ351;TQ424

摘要：通过对纤维素和木质素热解炭结构差异的研究发现,纤维素热解炭主要由碳微晶构成,木质素热解炭则包含部分原骨架结构;在氩气氛围中将热解炭于超高温下(1 600~2 800℃)进一步处理,并通过X射线衍射、拉曼光谱、X射线光电子能谱和高分辨率透射电镜等表征产物的结构与形貌,测试产物的导电性能,根据热解炭石墨化处理前后结构、形貌和导电性能的变化,研究高温条件下热解炭的结构重构建机制。结果表明:木质素热解炭经2 800℃处理后,产物中形成了大面积连续的高度石墨化区域,且缺陷较少,产物石墨化度可达89.53%,层间距为0.336 3 nm,于20 MPa压强下电导率可达105 S/cm;相同条件下纤维素产物的石墨化度为76.74%,层间距为0.337 4 nm,并包含较多结构缺陷,导致其在20 MPa压强下的电导率低于50 S/cm。分析可知,木质素热解炭中保留的骨架结构有利于其在高温下扩环重构建,进而形成大面积连续石墨化片层;而纤维素热解炭中碳微晶的交联状态在高温下难以转变,限制了石墨化区域的扩大,导致所得产物结构中存在较多缺陷。
In recent years, preparing graphitic carbon using lignocellulosic materials has been increasingly attractive due to its advantages of abundance, renewability, and high carbon content. However, such progress is of great challenge resulted from the complex structure of lignocellulosic biomass-based chars. Although some kinds of biomass-derived graphitic carbons have been successfully prepared, the mechanism of structural transformation during graphitization progress under high temperatures remains unclear. It is well-known that cellulose and lignin are the major components of biomass, and the chars derived from cellulose and lignin have totally different structures. Therefore, it is worthy to investigate the difference of char structure and graphitizing effect in order to get better knowledge of the mechanism of the structural transformation of chars derived from cellulose and lignin under ultra-high temperatures. By the author, through investigating the structural differences between pyrolytic charcoals originated from cellulose and lignin, it was discovered that the cellulose-originated char was primarily composed of carbon micro-crystallites, whereas lignin-ori-ginated char had partially preserved its original skeleton structures. The chars were further treated under ultra-high temperatures(1 600-2 800 ℃) in argon atmosphere, followed by characterizing the structure and morphology using the XRD, Raman spectra and high-resolution transparent electron microscopy, and the electrical conductivity of the pro-ducts was determined as well. According to the changes in the structure, morphology and electrical conductivity of chars before and after the graphitization, the mechanism of structure reconstruction of pyrolytic chars under high temperatures was investigated. The results illustrated that large continuous highly graphitized areas with little defect had formed in the pyrolytic char from lignin after being treated at 2 800 ℃. The graphitic degree was 89.53%, along with the interlayer spacing of 0.336 3 nm and electrical conductivity of 105 S/cm under 20 MPa. Cellulose-originated pro-ducts obtained under the same treating condition had graphitized degree of 76.74% and layer distance of 0.337 4 nm, and the existence of large quantities of structural defects had resulted to electrical conductivity of lower than 50 S/cm under 20 MPa. Combined with the results of structural analysis of charcoals, it was clarified that the preserved skeleton structure in lignin was the key factor for the ring-enlarging reconstruction and forming continuous graphitized layers with large areas. Meanwhile, the cross-linked micro-crystallites in cellulose-based char could hardly transform even at such high temperatures, restricting the expanding of graphitic areas and causing the formation of numerous defects in the product. This work is expected to supply an important theoretical support for the preparation of graphitized carbon from lignocellulosic resources.