Molecular Characterization of Henan Anthracite Coal

A type of Chinese anthracite coal was analyzed by several analytical techniques such as Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectroscopy (XPS), solid-state C-13 nuclear magnetic resonance spectrum (NMR), and high-resolution transmission electron microscopy (HRTEM). Combining the experimental data, a reasonable macromolecular model of anthracite coal (C258H172O12N4S) was proposed. HRTEM results showed that the anthracite coal mainly contained aromatic laminates with different lattice sizes, with the length distribution characterized as 35.0% (<5.5 angstrom), 17.5% (5.5-7.4 angstrom), 22.5% (7.5-11.4 angstrom), and 10% (11.5-14.4 angstrom). The FTIR analysis suggested that ether, hydroxyl, and carbonyl groups were the main oxygenated functionalities. The ratio of these groups was approximately 4:3:3, which was consistent with the results of the XPS. On the basis of the rich analytical data, a three-dimensional molecular representation of the anthracite coal was constructed. Then, the properties of the model like NMR were simulated and exhibited a good agreement with the experimental spectrum in peak ranges and composition. The molecular model obtained in this work is useful for further studying the reaction mechanisms during the anthracite utilization processes, and the methodology adopted here can be extrapolated to other coal representations.