炭化温度对木材生物炭结构和化学组成的影响  

Effects of carbonization temperature on the structure and chemical composition of woody biochar

作　　者：汪文庆 代博仁 夏重阳 石江涛 WANG Wenqing;DAI Boren;XIA Chongyang;SHI Jiangtao(College of Materials Science and Engineering,Nanjing Forestry University,Nanjing 210037,Jiangsu,China)

机构地区：[1]南京林业大学材料科学与工程学院,江苏南京210037

出　　处：《湖南林业科技》2023年第3期12-19,共8页Hunan Forestry Science & Technology

基　　金：江苏省林业科技创新与推广项目(LYKJ[2020]20)。

摘　　要：为了探究木材厚壁管胞与薄壁木纤维的炭化规律,为木材的炭化利用提供理论依据,本文以火炬松和轻木分别作为厚壁管胞与薄壁木纤维的木材代表,设置220、375、600、900℃四组炭化温度,利用扫描电镜(SEM)、傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)技术分别分析了两种类型木材细胞炭化前后的细胞结构和化学组成。SEM结果表明薄壁木纤维在375℃时开始出现光滑的无定形结构,而厚壁管胞出现同样无定形结构的温度为900℃。炭化后细胞双层细胞壁厚度减小,减小程度随炭化温度增加而增加;与厚壁管胞相比,薄壁木纤维双层细胞壁厚度缩减得更快更多。红外光谱曲线随炭化温度的升高变化明显,薄壁木纤维和厚壁管胞红外光谱分别在220℃和375℃后失去吸收峰。综纤维素相对含量、木质素相对含量的差异反映出两种类型细胞不同的热降解过程。X射线衍射分析发现,在220~375℃时,薄壁木纤维的纤维素相对结晶度下降至结晶态完全消失;而厚壁管胞则在600℃时出现结晶态完全消失现象。以上结果表明薄壁木纤维与厚壁管胞具有不同的炭化过程,前者的细胞结构更易发生热降解,相同温度下热降解更剧烈。In order to provide a theoretical basis for the carbonization of wood,the carbonization pattern of thick-walled tracheids and thin-walled wood fibers in wood was investigated by takeing Pinus taeda and Ochroma lagopus as the wood representatives.Four carbonization temperatures of 220℃,375℃,600℃,and 900℃were set,scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),and X-ray diffraction(XRD)were used to analyze the cell structure and chemical composition of two types of wood cells before and after carbonization.The SEM results showed that smooth amorphous structures of thin-walled wood fibers were observed at 375℃,compared to 900℃for thick-walled tracheids.The double cell wall thickness(DCWT)decreased after carbonization,while the degree of reduction increased with the carbonization temperature.The DCWT of thin-walled wood fibers decreased faster,and higher than that of thick-walled tracheids.The FTIR varied significantly with the carbonization temperature,with the absorption peaks of thick-walled tracheids and thin-walled wood fibers disappeared above 220℃and 375℃,respectively.The difference of relative contents of holocellulose and lignin between the two types of cells reflected the different thermal degradation processes.XRD showed that the relative crystallinity of cellulose decreased to complete loss of the crystalline state between 220℃and 375℃in thin-walled wood fibers,while the crystalline state of the thick-walled tracheids completely disappeared at 600℃.The above results showed that thin-walled wood fibers had different carbonization process to thick-walled tracheids with the former being more susceptible to thermal degradation,which was more intense at the same temperature.

关 键 词：木材炭化 细胞壁 热降解 相对结晶度 

分 类 号：S785[农业科学—林学]