Morphological Characterization of the Microcrystalline Structure of Tectonic Coal and Its Intrinsic Connection with Ultra-micropore Evolution
Morphological Characterization of the Microcrystalline Structure of Tectonic Coal and Its Intrinsic Connection with Ultra-micropore Evolution
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构造煤微晶结构形态表征及其与超微孔隙演化的内在联系
DOI：
10.1021/acs.energyfuels.1c03950
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发表时间：
2022-01
期刊：
影响因子：
--
通讯作者：
Wei Li
中科院分区：
文献类型：
--
作者：
Kaizhong Zhang;Aoao Zou;Liang Wang;Yuanping Cheng;Chun Liu;Wei Li
系统地了解煤的物理和化学微结构对于更好地理解天然气的储存和运移是必不可少的，而煤的微晶形态结构的变化在分子尺度上对超微孔的发育有着重要的影响。然而，变质作用和构造作用对大分子结构中超微孔演化的响应机制仍需进一步研究。通过X射线衍射、拉曼光谱和CO2(273K)吸附等手段，研究了原煤和构造煤的微晶形态结构及其与超微孔演化的本质关系。结果表明，与低变质原煤相比，高变质构造煤的X射线衍射谱具有更锐利且右移的002谱带，构造变形因素可能影响煤的微晶结构发育特征。高变质构造煤中高岭石相对含量增加，石英相对含量降低，构造作用对硅酸盐矿物组成影响较大。随着变质作用和构造作用的加强，芳香族化合物的层间距从0.3651 nm减小到0.3482 nm，而层高Lc和芳香族片层间距分别增加了60.7%和68.6%，从而促进了芳香化程度和石墨化程度。构造作用进一步推动了上述结构参数的演化。此外，拉曼光谱的峰位差G-D_1对变质作用和构造作用具有灵敏的响应。峰值强度比Id1/IgS与变质作用成正负相关，构造作用进一步降低。在这种情况下，基本结构单元的结晶度增加，晶体中的大规模缺陷程度降低，有助于不同变质程度的原煤和构造煤形成发育良好的微孔结构。变质作用促进了大分子结构在芳构化和缩聚上的有序演化，随后构造作用导致了微晶结构的密集复合、堆积、缩合和芳构化。因此，这种组合可能导致大分子结构从无序到有序的演化，从而从根本上改变构造煤的化学结构。上述结果对揭示煤层气的吸附和扩散行为以及煤层气的生成、储存和运移机制具有指导意义。
A systematic knowledge of the physical and chemical microstructure of coal is indispensable for better understanding gas storage and migration, and the variations of coal microcrystalline morphological structures have significant impacts on the ultra-micropore development at the molecular scale. However, the response mechanism of metamorphism and tectonism on ultra-microporous evolution in the macromolecular structure still needs further study. In this work, the microcrystalline morphological structure of original and tectonic coals and its essential relation with ultra-micropore evolution were investigated via XRD, Raman spectroscopy, and CO2(273 K) adsorption. The results demonstrate that the XRD patterns of high-rank tectonic coals have sharper and right-shifted 002 bands compared to those of lower-rank original coals, and tectonic deformation factors may affect the development characteristics of coal microcrystalline structures. The relative content of kaolinite in high-rank tectonic coals increases, whereas that of quartz decreases; tectonism has a great influence on the composition of silicate minerals. With the enhancement of metamorphism and tectonism, the aromatic interlayer spacingd002decreases from 0.3651 to 0.3482 nm, while the stacking heightLcand the aromatic slicesNaveincrease by 60.7 and 68.6%, respectively, promoting the degree of aromatizationfaand degree of graphitizationg. Tectonism further advances the evolution of the above structural parameters. In addition, the peak position differenceG–D1of Raman spectrum has a sensitive response to metamorphism and tectonism. The peak intensity ratioID1/IGis directly negatively correlated with metamorphism, and tectonism brings about a further decrease. In this case, the degree of crystallinity in the basic structural units increases, and the degree of large-scale defects in the crystal decreases, contributing to the well-developed microporous structure of original and tectonic coals with different ranks. Metamorphism facilitates the ordered macromolecular structural evolution on aromatization and condensation, and subsequently, tectonism results in the intensive recombination, stacking, condensation, and aromatization of microcrystalline structures in advance. Thus, this combination may lead to the macromolecular structure evolution from disordering to ordering and then essentially alter the chemical structure of tectonic coal. The aforementioned results have guiding significance for revealing the gas sorption and diffusion behaviors as well as the mechanism of coalbed methane generation, storage, and migration.
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影响因子：
5.6
作者：
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