Modeling of molecular and properties of anthracite base on structural accuracy identification methods

Molecular model construction is essential for the study of the energy conversion process, the combustion reaction mechanism and the clean utilization of coal. In this study, an anthracite molecular structure of GBW(E)110031 was constructed based on the structural accuracy identification methods, such as C-13 nuclear magnetic resonance spectroscopy (C-13 NMR), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and quantitative chemical analysis. The C-13 NMR spectrum was registered to analyze the carbon skeleton structure of the anthracite and twelve characteristic parameters of coal structures. The aromaticity, hydrogen aromaticity, and average aromatic nuclear size of the anthracite were calculated. These data were utilized to construct 17 basic structural units of aromatic carbon. The vibration modes of the carbon skeleton, several association forms of oxygen, and different types of functional group were confirmed based on the ATR-FTIR collected spectra. The content of functional groups and unsaturated aliphatic carbon alkenyl were determined by the calcium ion exchange method, the pyridine hydroxylamine hydrochloride oximation method and the bromine addition method. Based on these experimental data, a C(202)H(104)O(21)N(2)S(2)anthracite molecular structure model was constructed. In the molecular structure model, benzene and naphthalene structures accounted for 70% of the mass of aromatic compounds, while aliphatic structures existed in the form of side chains and rings. Carbonyl group (C=O) accounted for 85% of the oxygen atoms, while others existed in the form of carboxyl and hydroxyl groups. The nitrogen atoms presented in the structures of pyridine and pyrrole, and the sulfur atoms presented in the structures of thiophene. The theoretical analysis matched well with C-13 NMR spectra interpretation, which was verified the reliability and rationality of the molecular structure model and analytical method. (C) 2019 Published by Elsevier B.V.