Liu Hewu
State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui University of Science and Technology, Huainan 232001, China.
School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China.
ACS Omega. 2022 Sep 29;7(40):35942-35950. doi: 10.1021/acsomega.2c04737. eCollection 2022 Oct 11.
The dynamic metamorphism of tectonically deformed coals (TDCs) is closely correlated with the occurrence of coalbed methane. Here, a Raman detection technique was used to characterize two primary coals and 14 TDCs sampled from the Huaibei coalfield, allowing for profound insight into the dynamic metamorphism caused by tectonic stress in coals. A nine-peak curve fitting method was applied to deconvolute the first-order Raman spectra, and six structural parameters were used to characterize the hierarchical evolution of TDC molecules. The lower / and / ratios in TDCs indicate that the cross-links in secondary and aggregated (outer) structures are cleaved by tectonic stress. Once the aromatic structures are released through the cleavage of cross-links, the outer structures can be rearranged into a more ordered configuration, as indicated by the higher / ratio in TDCs. Additionally, the basic structural units (including aromatic structures and side chains) in TDC are also altered by stress. The increasing values of / and / illustrate that the size of aromatic structures and the ratio of small aromatic structures both increase with increasing coal deformation intensity. The value of / decreases with increasing deformation intensity, indicating that oxygen functional groups are disassociated by tectonic stress. However, as the basic structural units are commonly rigid and cannot be altered as readily as the outer structures, the evolution of basic structural units is not always obvious in weakly deformed coals (such as cataclastic, mortar, and schistose types) but is more significant in strongly deformed coals (such as granulitic, scaly, and wrinkle types).
构造变形煤（TDCs）的动态变质作用与煤层气的赋存密切相关。在此，采用拉曼检测技术对采自淮北煤田的两种原生煤和14种构造变形煤进行了表征，从而深入了解煤中构造应力引起的动态变质作用。应用九峰曲线拟合方法对一阶拉曼光谱进行反褶积，并使用六个结构参数来表征构造变形煤分子的分级演化。构造变形煤中较低的 / 和 / 比值表明，次生结构和聚集（外部）结构中的交联键被构造应力切断。一旦芳香结构通过交联键的断裂而释放，外部结构就可以重新排列成更有序的构型，这在构造变形煤中较高的 / 比值中得到体现。此外，构造变形煤中的基本结构单元（包括芳香结构和侧链）也会受到应力的影响。 / 和 / 值的增加表明，芳香结构的尺寸和小芳香结构的比例均随着煤变形强度的增加而增加。 / 值随着变形强度的增加而降低，表明氧官能团被构造应力解离。然而，由于基本结构单元通常是刚性的，不像外部结构那样容易改变，因此基本结构单元的演化在弱变形煤（如碎裂状、砂浆状和片理状类型）中并不总是明显，但在强变形煤（如粒状、鳞片状和皱纹状类型）中更为显著。
