| Citation: |
SHAO Yan，CHEN Xiaozhen，LI Yexi，et al. Raman spectroscopy characterization of structural evolution in middle-rank coals[J]. Coal Science and Technology，2023，51（8）：295−303. DOI: 10.13199/j.cnki.cst.2022-0718
|
The second coalification jump which occurred during the middle-rank led to abrupt changes of many physical and chemical properties of coal, and the change of the aggregate structure may be the fundamental reason. In order to investigate the structural evolution characteristics of middle-rank coal and its relation with the second coalification jump in detail, the structure characteristics of six middle-rank coals (Ro,max=1.10%−1.63%) that across the second coalification jump were studied by Raman spectroscopy, and the structural parameters were calculated by fitting the first-order and second-order Raman spectrum using the fitting software. The results indicated that the evolution of Raman structural parameters with Ro,max is not linear, reflecting the complexity of the structural evolution of coal. According to the evolution characteristics of Raman structural parameters, the coalification during the stage of Ro,max=1.10%−1.63% can be divided into three stages. The turning points are located near Ro,max=1.30% and Ro,max=1.50%, respectively, which are exactly equivalent to the positions of the second and the third coalification jump discovered in previous research. It indicated that the Raman structural parameters can reflect the occurrence of the coalification jump, moreover, Raman spectroscopy is an effective method to study the coal structure. The first stage is Ro,max=1.10%−1.30%, the long-chain aliphatic structures cracked and the remained shorter-chain aliphatic hydrocarbons and aliphatic substituted structures on the aromatic rings will form new alicyclic structures, which caused the branched degree increases and hindered the alignment of aromatic systems in coal. The order degree of aromatic system is thus reached the least near Ro,max=1.30%, with the smallest WG, the largest FG/D, the smallest AD/AG, the increase of AS/A1, and the significant decrease of A(2G)R/A2. In the second stage of Ro,max=1.30%−1.50%, the aromatization of the alicyclic structures formed in the previous stage resulted in an increase in the content of aromatic C—H structure and the least of amorphous carbon structure. Besides, the degree of aromatization and aromatic structural both increased, which showed that A(GR+VL+VR)/AD, A(GR+VL+VR)/AG and FG/D decreased significantly, AD/AG increased, WG and d(G-D) increased quickly. The last stage is Ro,max=1.50%−1.63%, the condensation reaction occurred between the aromatic rings formed in the second stage, leading to the reduction of A(2G)R/A2. Meanwhile, the various bridging bonds between aromatic ring systems continued to break, resulting in the formation of some small-scale aromatic structures, as evidenced by a decrease in A(2G)R/A2, a small decrease in WG, and an increase in A(GR+VL+VR)/AD and A(GR+VL+VR)/AG. These results are the basis for deeply understanding the mechanism of coalification jump and coalification.
| [1] |
STACH E, MACKOESKY M, TEICHMÜLLER M, et al. Stach’ s textbook of coal petrology[M]. Berlin, Germany: Gebrüder Borntraeger, 1982.
|
| [2] |
杨 起. 煤变质作用研究[J]. 现代地质,1992,6(4):437−443.
YANG Qi. The study of coal metamorphism[J]. Geoscience,1992,6(4):437−443.
|
| [3] |
侯慧敏,胡社荣,潘 响,亮,等. 腐植煤生油显微组分研究现状与进展[J]. 中国煤田地质,1997,9(2):24−29.
HOU Huimin,HU Sherong,PAN Xiangliang,et al. Research status and progress of micro-components of humic coal-derived oil[J]. Coal Geology of China,1997,9(2):24−29.
|
| [4] |
SHUI H F,ZHAO W,SHAN C,et al. Caking and coking properties of the thermal dissolution soluble fraction of a fat coal[J]. Fuel Processing Technology,2014,118:64−68. doi: 10.1016/j.fuproc.2013.08.013
|
| [5] |
BUSTIN R M,GUO Y. Abrupt changes (jumps) in reflectance values and chemical compositions of artificial charcoals and inertinite in coals[J]. International Journal of Coal Geology,1999,38:237−260. doi: 10.1016/S0166-5162(98)00025-1
|
| [6] |
IINO M. Network structure of coals and association behavior of coal-derived materials[J]. Fuel Processing Technology,2000,62(2/3):89−101.
|
| [7] |
GIRAY E S V,CHEN C,TAKANOHASHI T,et al. Increase of the extraction yields of coals by addition of aromatic amines[J]. Fuel,2000,79(12):1533−1538. doi: 10.1016/S0016-2361(99)00292-6
|
| [8] |
TAKANOHASHI T,KAWASHIMA H. Construction of a model structure for upper freeport coal using 13C NMR chemical shift calculations[J]. Energy & Fuels,2002,16:379−387.
|
| [9] |
冯 杰,王宝俊,叶翠平,等. 溶剂抽提法研究煤中小分子相结构[J]. 燃料化学学报,2004,32(2):160−164.
FENG Jie,WANG Baojun,YE Cuiping,et al. Structure determination of small molecular phase in coal by solvent extraction[J]. Journal of Fuel Chemistry and Technology,2004,32(2):160−164.
|
| [10] |
张 卫,曾凡桂. 中等变质程度煤中羟基的红外光谱分析[J]. 太原理工大学学报,2005,36(5):545−547. doi: 10.16355/j.cnki.issn1007-9432tyut.2005.05.011
ZHANG Wei,ZENG Fangui. FTIR analysis of hydrogen bond in middle maturate coals[J]. Journal of Taiyuan University of Technology,2005,36(5):545−547. doi: 10.16355/j.cnki.issn1007-9432tyut.2005.05.011
|
| [11] |
郑庆荣,曾凡桂,张世同. 中变质煤结构演化的FTIR分析[J]. 煤炭学报,2011,36(3):481−486.
ZHENG Qingrong,ZENG Fangui,ZHANG Shitong. FTIR study on structure evolution of middle maturate coals[J]. Journal of China Coal Society,2011,36(3):481−486.
|
| [12] |
ROBERT A M. Coal structure [M]. New York - London - Paris-Toronto: Academic Press, 1982.
|
| [13] |
MATHEWS J P,CHAFFEE A L. The molecular representations of coal-A review[J]. Fuel,2012,96:1−14. doi: 10.1016/j.fuel.2011.11.025
|
| [14] |
ROBERTS M J,EVERSON R C,NEOMAGUS H W J P,et al. Influence of maceral composition on the structure, properties and behaviour of chars derived from South African coals[J]. Fuel,2015,142(15):9−20.
|
| [15] |
曾凡桂,谢克昌. 煤结构化学的理论体系与方法论[J]. 煤炭学报,2004,29(4):443−447. doi: 10.3321/j.issn:0253-9993.2004.04.015
ZENG Fangui,XIE Kechang. Theoretical system and methodology of coal structural chemistry[J]. Journal of China Coal Society,2004,29(4):443−447. doi: 10.3321/j.issn:0253-9993.2004.04.015
|
| [16] |
SHARMA A,KYOTANI T,TOMITA A. Direct observation of raw coals in lattice fringe mode using High-Resolution Transmission Electron Microscopy[J]. Energy & Fuels,2000,14:1219−1225.
|
| [17] |
KELEMEN S R,FANG H L. Maturity trends in Raman spectra from kerogen and coal[J]. Energy & Fuels,2001,15:653−658.
|
| [18] |
NIEKERK D V,MATHEWS J P. Molecular representations of Permian-aged vitrinite-rich and inertinite-rich South African coals[J]. Fuel,2010,89:73−82. doi: 10.1016/j.fuel.2009.07.020
|
| [19] |
ULYANOVA E V,MOLCHANOY A N,PROKHOROV I Y,et al. Fine structure of Raman spectra in coals of different rank[J]. International Journal of Coal Geology,2014,121:37−43. doi: 10.1016/j.coal.2013.10.014
|
| [20] |
ZHU H L,YU G S,GUO Q H,et al. In situ Raman spectroscopy study on catalytic pyrolysis of a bituminous coal[J]. Energy & Fuels,2017,31:5817−5827.
|
| [21] |
LI X J,HAYASHI J I,LI C Z. FT-Raman spectroscopic study of the evolution of char structure during the pyrolysis of a Victorian brown coal[J]. Fuel,2006,85:1700−1707. doi: 10.1016/j.fuel.2006.03.008
|
| [22] |
XU J,TANG H,SU S,et al. A study of the relationships between coal structures and combustion characteristics: The insights from micro-Raman spectroscopy based on 32 kinds of Chinese coals[J]. Applied Energy,2018,212:46−56. doi: 10.1016/j.apenergy.2017.11.094
|
| [23] |
苏现波,司 青,宋金星. 煤的拉曼光谱特征[J]. 煤炭学报,2016,41(5):1197−1202. doi: 10.13225/j.cnki.jccs.2015.1157
SU Xianbo,SI Qing,SONG Jinxing. Characteristics of coal Raman spectrum[J]. Journal of China Coal Society,2016,41(5):1197−1202. doi: 10.13225/j.cnki.jccs.2015.1157
|
| [24] |
XU J,TANG H,SU S,et al. Micro-Raman spectroscopy study of 32 kinds of Chinese coals: second-order Raman spectrum and its correlations with coal properties[J]. Energy & Fuels,2017,31:7884−7893.
|
| [25] |
XU J,LIU J W,ZHANG X,et al. Chemical imaging of coal in micro-scale with Raman mapping technology[J]. Fuel,2020,264(15):116826.
|
| [26] |
XU J,XIANG X R,XU K,et al. Developing micro-Raman spectroscopy for char structure characterization in the scale of micro- and bulk: A case study of Zhundong coal pyrolysis[J]. Fuel,2021,219:120168.
|
| [27] |
SHENG C D. Char structure characterised by Raman spectroscopy and its correlations with combustion reactivity[J]. Fuel,2007,86(15):2316−2324. doi: 10.1016/j.fuel.2007.01.029
|
| [28] |
赵云刚,李美芬,曾凡桂,等. 伊敏褐煤不同化学组分结构特征的红外光谱研究[J]. 煤炭学报,2018,43(2):546−554.
ZHAO Yungang,LI Meifen,ZENG Fangui,et al. FTIR study of structural characteristics of different chemical components from Yimin Lignite[J]. Journal of China Coal Society,2018,43(2):546−554.
|
| [29] |
WANG S Q,CHENG H F,JIANG D,et al. Raman spectroscopy of coal component of Late Permian coals from Southern China[J]. Spectrochimica Acta Part A. Molecular & Biomolecular Spectroscopy,2014,132:767−770.
|
| [30] |
ZHANG Y L,LI Z S. Raman spectroscopic study of chemical structure and thermal maturity of vitrinite from a suite of Australia coals[J]. Fuel,2019,241:188−198. doi: 10.1016/j.fuel.2018.12.037
|
| [31] |
WANG S,LI T T,WU L P,et al. Second-order Raman spectroscopy of char during gasification[J]. Fuel Processing Technology,2015,135:105−111. doi: 10.1016/j.fuproc.2014.11.002
|
| [32] |
CHEN H,WANG S Q,DENG J S,et al. Petrologic characteristics and chemical structures of macerals in a suite of thermally altered coals by confocal Raman[J]. ACS Omega,2021,6:33409−33418. doi: 10.1021/acsomega.1c03922
|
| [33] |
李美芬,曾凡桂,齐福辉,等. 不同煤级煤的Raman谱特征及与XRD结构参数的关系[J]. 光谱学与光谱分析,2009,29(9):2446−2449.
LI Meifen,ZENG Fangui,QI Fuhui,et al. Raman spectroscopic characteristics of different rank coals and the relation with XRD structural parameters[J]. Spectroscopy and Spectral Analysis,2009,29(9):2446−2449.
|
| [34] |
李 霞,曾凡桂,王 威,等. 低中煤级煤结构演化的拉曼光谱表征[J]. 煤炭学报,2016,41(9):2298−2304.
LI Xia,ZENG Fangui,WANG Wei,et al. Raman characterization of structural evolution in the low-middle rank coals[J]. Journal of China Coal Society,2016,41(9):2298−2304.
|
| [35] |
李 霞,曾凡桂,王 威,等. 低中煤级煤结构演化的FTIR表征[J]. 煤炭学报,2015,40(12):2900−2908.
LI Xia,ZENG Fangui,WANG Wei,et al. FTIR characterization of structural evolution in low-middle rank coals[J]. Journal of China Coal Society,2015,40(12):2900−2908.
|
| [36] |
ZHOU S D,LIU D M,KARPYN Z T,et al. Effect of coalification jumps on petrophysical properties of various metamorphic coals from different coalfields in China[J]. Journal of Natural Gas Science and Engineering,2018,60:63−76. doi: 10.1016/j.jngse.2018.10.004
|
| [37] |
刘冬冬,高继慧,吴少华,等. 热解过程煤焦微观结构变化的XRD和Raman表征[J]. 哈尔滨工业大学学报,2016,48(7):39−45. doi: 10.11918/j.issn.0367-6234.2016.07.006
LIU Dongdong,GAO Jihui,WU Shaohua,et al. XRD and Raman characterization of microstructure changes of char during pyrolysis[J]. Journal of Harbin Institute of Technology,2016,48(7):39−45. doi: 10.11918/j.issn.0367-6234.2016.07.006
|
| [38] |
ANTUNES E F,LOBO A O,CORAT E J,et al. Comparative study of first- and second-order Raman spectra of MWCNT at visible and infrared laser excitation[J]. Carbon,2006,44(11):2202−2211. doi: 10.1016/j.carbon.2006.03.003
|
| [39] |
COLANGELI L,MENNELLA V,BARATTA G A,et al. Raman and infrared spectra of polycyclic aromatic hydrocarbon molecules of possible astrophysical interest[J]. Astrophysical Journal,1992,396(1):369−377.
|
| [40] |
ZAIDA A,BAR-ZIV E,RADOVIC L R,et al. Further development of Raman Microprobe spectroscopy for characterization of char reactivity[J]. Proceedings of the Combustion Institute,2007,31(2):1881−1887. doi: 10.1016/j.proci.2006.07.011
|
| [41] |
WANG S Q,TANG Y G,SCHOBERT H H,et al. FTIR and 13C NMR investigation of coal component of Late Permian coals from Southern China[J]. Energy & Fuels,2011,25:5672−5677.
|
| [42] |
张 爽,姚素平,尹宏伟. 煤成烃反应机制的红外光谱证据[J]. 石油实验地质,2018,40(4):538−544. doi: 10.11781/sysydz201804538
ZHANG Shuang,YAO Suping,YIN Hongwei. FTIR study of hydrocarbon generation reactions of coal[J]. Petroleum geology & Experiment,2018,40(4):538−544. doi: 10.11781/sysydz201804538
|
Supported by: Beijing Renhe Information Technology Co., Ltd. 
DownLoad: