摘要
我国低煤阶煤储量丰富,因此实现低煤阶煤的高效利用是当前我国能源产业发展的重要方向。近年来的研究发现,利用低煤阶煤制备石墨可能是低煤阶煤高效利用的途径之一,而低煤阶煤化学结构在线演化特征的深刻理解是低煤阶煤石墨化机制了解的基础。基于此,以伊敏煤为研究对象,对其进行了原位拉曼光谱(Raman)及热重/质谱联用(TG/MS)测试,并运用分峰拟合软件对各原位拉曼光谱谱图进行了分峰拟合,在此基础上计算了拉曼结构参数。结果表明,随温度升高,拉曼参数表现出明显的阶段性变化特征,而且与热解产物的生成密切相关。当热解温度低于300℃时,拉曼参数AS/AAll明显减小,A_((GR+VL+VR))/AG,FWHM-D,FWHM-G与AD/AG增加,这是由于煤热解在这一阶段以煤中物理吸附的水、气体的膨胀及氢键的断裂为主,导致大量无定形结构暴露,结构有序度降低;第2阶段为300~700℃,此阶段体系中发生剧烈的解聚和分解反应,CO_(2)及烃类产物大量生成,拉曼参数FWHM-D,FWHM-G,AS/AAll和AD/AG急剧减小,而A_((GR+VL+VR))/AD和A_((GR+VL+VR))/AG增大,表明芳香族取代基的脱落以及连接大芳香环间的各种桥键断裂导致大芳香环结构减少,而小芳环结构增多,同时因缺陷结构大量减少导致结构有序度增加;第3阶段发生在700℃后,FWHM-D,FWHM-G,A_((GR+VL+VR))/AD和A_((GR+VL+VR))/AG减小,AD/AG和AS/AAll值增加,该阶段煤热解以芳环缩聚脱氢为主,导致6个或6个以上稠环比例相对增加,交联密度增大,且由于缺陷结构的大量脱除,微晶结构定向排列明显增加,无定形碳结构向有序性转化。这些结果是深入理解低煤阶煤变质作用及石墨化作用机制的基础。
Lignite is abundant in China. Thus the high efficient utilization of low-rank coal is an important direction for the development of the energy industry. Recent researches show that the graphitization of low rank coal may be one of the ways to efficiently utilize the low-rank coal. A deep understanding of the structural evolution mechanism during metamorphism is the basis for the comprehension of graphitization mechanism of low-rank coal. Based on this, the Yimin lignite is selected as the research object and is examined by in-situ Raman and thermo-gravimetry coupled with mass spectrometry(TG/MS),and the in-situ Raman structural parameters are calculated based on the deconvolution results obtained by peak fitting software. The results indicate that the Raman parameters are closely related to the gaseous release characteristics and show three obvious stages with increasing temperature. When the pyrolysis temperature is lower than 300 ℃,AS/AAlldecreases obviously, while A(GR+VL+VR)/AG,FWHM-D,FWHM-G and AD/AGincrease in this stage. This is owing to that the expansion of physically absorbed water and gas, and the cracking of hydrogen bond cause a large number of qualitative amorphous carbon structures exposure and the degree reduction of the order of structure. From 300 ℃ to 700 ℃,the strong depolymerization and decomposition reactions occur and CH4,CO_(2)and hydrocarbon products are generated dramatically in this stage. The Raman parameters FWHM-D,FWHM-G,AS/AAlland AD/AGdecrease sharply, while A_((GR+VL+VR))/ADand A(GR+VL+VR)/AGincrease. This indicates that the loss of aromatic substituents and the breaking of various bridge bonds between large aromatic rings are responsible for the decrease of large aromatic rings and the rapid growth of small aromatic rings in coal. Meanwhile, the defect structures are greatly reduced and the order degree is increased in this stage. After 700 ℃,FWHM-D,FWHM-G,A_((GR+VL+VR))/ADand A(GR+VL+VR)/AGdecrease obviously, and AD/AGand AS/AAllincrease, and H2is the main pyrolysis prod
作者
李美芬
李晔熙
邵燕
陈小珍
崔曦
左家琦
蒋恒宇
LI Meifen;LI Yexi;SHAO Yan;CHEN Xiaozhen;CUI Xi;ZUO Jiaqi;JIANG Hengyu(College of Mining Engineering,Taiyuan University of Technology,Taiyuan030024,China;Shanxi Key Laboratory of Coal and Coal Measure Gas Geolo-gy,Taiyuan University of Technology,Taiyuan030024,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2022年第12期4313-4322,共10页
Journal of China Coal Society
基金
国家自然科学基金资助项目(U1910204,41772165,41572144)。
