热解过程煤焦微观结构变化的XRD和Raman表征

XRD and Raman characterization of microstructure changes of char during pyrolysis

摘要:

为深入了解煤焦微观结构在热解过程的变化规律,对霍林河褐煤(HLH)、大同烟煤(DT)、鸡西烟煤(JX)和晋城无烟煤(JC)进行热解实验(25～1 600 ℃),采用X射线衍射(XRD)和拉曼光谱(Raman)获取煤焦微观结构信息,并对两者数据的关联性进行分析．结果表明,热解过程煤焦微观结构的变化存在明显的3个阶段,分别对应解聚与流动、热缩聚与芳构化、石墨化．当L_a＜3 nm, I_D1/I_G和I_D4/I_G随L_a的增大而增加;当L_a>3 nm,I_D1/I_G和I_D4/I_G随L_a的增大而减小,表明层片在不同尺寸内发生改变,其相互连接方式和缺陷数量也不相同．L_c分别与I_D3/I_G和Raman谱峰总积分面积成反比,表明无定形sp²碳原子多存在于芳香片层的夹层间,且与芳香结构活性有关．

Abstract:

To deeply understand the changes of char microstructure, the pyrolysis experiments of Huolinghe lignite(HLH), Jixi bituminous coal(JX), Datong bituminous coal (DT) and Jincheng anthracite (JC) were carried out at 25～1 600 ℃. The microstructure information of char was obtained by X-ray diffraction (XRD) and Raman spectroscopy (Raman), of which the relationship was studied. The result demonstrates that the microstructure changes of char have obvious three stages: depolymerization and liquidity, thermal condensation and aromatization, and graphitization. When L_a ＜3 nm, I_D1/I_G and I_D4/I_G increase with the increase of L_a; When L_a>3 nm, I_D1/I_G and I_D4/I_G decrease with the increase of L_a, indicating that the mode of connection and the number of defects are relate to the change of the size of aromatic layers at different scales. L_c is inversely proportional to I_D3/I_G and the total integrated area of Raman, indicating that the amorphous sp² carbon atoms exist in the interlayer of the aromatic layer, which is related to the activity of the aromatic structure.