朱玉雯,王天阳,徐杨,等. 烟煤镜质组分性质及对活性炭结构特性的影响[J]. 煤炭学报,2024,49(5):2519−2528. DOI: 10.13225/j.cnki.jccs.2024.0148
引用本文: 朱玉雯,王天阳,徐杨,等. 烟煤镜质组分性质及对活性炭结构特性的影响[J]. 煤炭学报,2024,49(5):2519−2528. DOI: 10.13225/j.cnki.jccs.2024.0148
ZHU Yuwen,WANG Tianyang,XU Yang,et al. Properties of vitrinite in bituminous coal and their influence on the structural characteristics of activated carbon[J]. Journal of China Coal Society,2024,49(5):2519−2528. DOI: 10.13225/j.cnki.jccs.2024.0148
Citation: ZHU Yuwen,WANG Tianyang,XU Yang,et al. Properties of vitrinite in bituminous coal and their influence on the structural characteristics of activated carbon[J]. Journal of China Coal Society,2024,49(5):2519−2528. DOI: 10.13225/j.cnki.jccs.2024.0148

烟煤镜质组分性质及对活性炭结构特性的影响

Properties of vitrinite in bituminous coal and their influence on the structural characteristics of activated carbon

  • 摘要: 以大同烟煤和新疆烟煤为原料,采用密度离心分离法提取镜质组富集物,采用气体活化法制备活性炭。对比研究原煤及其镜质组的结构性质差异,以及经炭化和CO2活化后微晶及孔结构的特性变化。采用傅里叶变换红外光谱法对比分析了原煤及其镜质组芳香烃和脂肪烃结构的差异,采用X射线固体粉末衍射法全过程分析了原料、炭化料和活性炭的微晶结构参数及芳香度变化,采用N2吸附法研究了炭化料和活性炭的孔结构特性变化。结果表明:相比于原煤,镜质组富集物的微晶单元尺寸较小,脂肪链长度较短,且支链数量较多,有利于增强炭化过程的流动性。经热重分析法得到镜质组的炭化失重率较高,且失重峰较宽。上述结构性质及反应性差异影响了炭化料的结构特性。经过850 ℃炭化后,镜质组炭化料的微晶层片尺寸和堆积厚度均增加,原煤炭化料仅增加了层片尺寸,而堆积厚度有所降低,说明显微组分差异主要影响了炭化过程中芳香层片的纵向堆叠。同时相比于原煤炭化料,镜质组炭化料的芳香度较高,BET比表面积和总孔容积相对较大。经过CO2活化后,活性炭的微晶堆积厚度及层片尺寸均低于对应的炭化料,说明CO2活化烧蚀了微晶结构。同时,活化形成了以微孔为主的孔结构,其中镜质组活性炭的BET比表面积分别达到744.1和797.4 m2/g,显著高于原煤活性炭。镜质组活性炭的微孔和中孔容积也较高,其中微孔容积达到原煤活性炭的1.7~2.2倍。上述结果说明芳香度较高、初始孔结构较多的炭化料有利于活化形成更加丰富的微孔结构。

     

    Abstract: The vitrinite-rich concentrates were extracted respectively from the Datong bituminous coal and the Xinjiang bituminous coal by the density gradient centrifugation method. The activated carbons were prepared by physical activation with carbon dioxide using the above raw coals and vitrinite. The structural properties of vitrinite and the corresponding raw coals were compared, and the characteristics of crystallite and pore structure were analyzed after the carbonization and CO2 activation process. The differences of aromatic and aliphatic hydrocarbon structures of coal and its vitrinite samples were analyzed by Fourier transform infrared spectroscopy. Microcrystalline structure parameters and aromaticity index of coals, chars and activated carbons were analyzed by X-ray diffractometer. The pore structure parameters of chars and activated carbons were studied by the low-temperature nitrogen adsorption method. Compared with raw coals, the crystallite unit sizes of vitrinite were smaller, the length of aliphatic hydrocarbon chain was shorter, and the number of branch chains was larger than those of the corresponding coals, which was beneficial to enhance the fluidity in the carbonization process. Moreover, the weight loss rates of vitrinite were higher, and the weight loss peaks were wider than that of the coals during the carbonization process by thermogravimetric analyzer. The above differences of structural properties and carbonization reactivity of coal and its vitrinite samples could affect the structure characteristics of chars. The results showed that the crystallite lamella size and stacking thickness of vitrinite chars were both increased after carbonization at 850 ℃, while the stacking thickness of crystallite in coal chars was decreased, which indicated that the differences of maceral mainly affected the vertical stacking of crystallite lamella during carbonization. Meanwhile, it led to higher aromaticity and larger BET specific surface area of both vitrinite chars. After the CO2 activation process, the stacking thickness and lamella size of crystallite in activated carbons were lower than that of the corresponding chars, indicating that the crystallite unit got burnt by CO2 activation. The dominant micropore structures were obtained after activation process. The BET specific surface areas of activated carbons from vitrinite reached 744.1 and 797.4 m2/g, respectively, which were significantly higher than that of activated carbons from coals. The micropore and mesopore volumes of vitrinite-based activated carbons were both higher than that of coal-based activated carbons, and the micropore volumes were 1.7−2.2 times more than that of coal-based activated carbons. The above results indicated that the chars with higher aromaticity and more porosity were beneficial to generate micropore structure during activation process.

     

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