Molecular structure analysis of Jincheng anthracite coal

To have a more comprehensive understanding on the chemical structure, Jincheng anthracite are analyzed by using industrial analysis, elemental analysis, 13 C nuclear magnetic resonance (13C-NMR), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that the coal structure bridge carbon ratio is 0.46, the average structural unit molecular mass is 398. In addition, the condensation degree of aromatic nuclei in coal structure is high because most of aromatic layers are in the forms of benzo anthracene, benzo pyrene as well as larger aromatic ring. High degree of aromatic ring substitution was found from FTIR and XPS analysis. A small amount of nitrogen, in the forms of organic and inorganic nitrogen, is present in coal. Sulfur mainly exists in the form of organic sulfur and inorganic sulfur. However, the content of inorganic sulfur in coal sample is much less than organic sulfur. The content of oxygen element is low in coal and most of oxygen species are attributed to the pedant groups in aliphatic side chain which is short with a low branching degree. Based on the above information, an average structural unit molecular model of Jincheng anthracite was preliminarily constructed, and its average structural unit molecular formula is C30H15.5O0.5N0.5, which will provide a fundamental building block for the large scale molecular assembly model. © 2018, Editorial Office of Journal of China Coal Society. All right reserved.