Molecular Model Construction and Evaluation of Jincheng Anthracite

Despite
its importance, limited representations of the anthracite
models have been developed. The first molecular representation of
Chinese Jincheng anthracite with the incorporation of diverse molecular
structures was constructed based on the available analytical data.
Three hundred individual aromatic sheets were first built based on
the aromatic fringe distribution obtained from high-resolution transmission
electron microscopy. Alkyl chains and nitrogen, sulfur, and oxygen
heteroatoms were added in the aromatic skeletons to form diverse anthracite
structural units based on 13C NMR, X-ray photoelectron
spectroscopy, and ultimate analyses. Fifty-five different anthracite
molecules were formed by covalent cross-linking considering the constraint
imposed by the molecular weight distribution of the Jincheng anthracite
obtained from laser desorption time-of-flight mass spectrometry (LD-TOF
MS). These molecules were packed into a three-dimensional cell to
form a Jincheng anthracite model (C7730H3916O133N123S25). We showed that the
proposed model can provide a reasonable representation of the Jincheng
anthracite by comparing the simulated and experimental magnetic resonance
spectroscopy, LD-TOF MS, density, and X-ray diffraction data. Because
of the large, molecularly diverse structure, many anthracite behavioral
processes can be further explored using this model in the future.

尽管无烟煤模型的研究具有重要价值，但目前已开发的相关表征手段仍较为有限。本研究基于公开的分析数据，首次构建了包含多样分子结构的中国晋城无烟煤分子表征模型。研究首先基于高分辨透射电子显微镜（high-resolution transmission electron microscopy）得到的芳香片边缘分布特征，构建了300个独立的芳香片结构。结合碳-13核磁共振波谱（13C NMR）、X射线光电子能谱（X-ray photoelectron spectroscopy）以及元素分析结果，在芳香骨架中引入烷基链与氮、硫、氧杂原子，以此形成多样化的无烟煤结构单元。基于激光解吸飞行时间质谱（laser desorption time-of-flight mass spectrometry, LD-TOF MS）测得的晋城无烟煤分子量分布约束条件，通过共价交联得到55种不同的无烟煤分子。将这些分子填充至三维晶胞中，最终构建得到晋城无烟煤分子模型（C7730H3916O133N123S25）。通过对比模拟与实验得到的核磁共振波谱、LD-TOF MS、密度以及X射线衍射数据，本研究验证了所提出的模型可合理表征晋城无烟煤的结构特征。由于该模型具备分子结构多样且尺度较大的特点，未来可依托此模型进一步探究多种无烟煤相关的行为过程。