Structural Model Construction and Optimal Characterization of High-Volatile Bituminous Coal Molecules

Abstract

The structural characteristics of coal at the molecular level are important for its efficient use. Bituminous coal from the Baozigou Coal Mine is investigated, using elemental analysis, 13 C nuclear magnetic resonance, X-ray photoelectron spectroscopy, and Fourier transform infrared. The molecular structure was determined. The aromatic compounds of bituminous coal molecules are primarily two- and three-ring structures, and the aliphatic structures are primarily in the form of methyl, ethyl side chains, and naphthenic hydrocarbons. The ratio of aromatic bridge carbon to peripheral carbon in the molecular structure is 0.279. Oxygen atoms in the form of carbonyl, phenolic hydroxyl and C–O, and nitrogen atoms in pyrroles. Thus, the average structure model of bituminous coal macromolecules was constructed; the molecular formula was C 169 H 128 O 10 N 2 S, and the molecular weight was 2378. The aromatic structural units in the macromolecular structure of coal include four naphthalenes, three anthracenes, two tetracenes, and heteroatoms in the form of three carbonyl groups, one phenolic hydroxyl group, one pyrrole, and one pyridine. The structure optimization and annealing kinetic simulation of a single macromolecular structure model were performed. Chemical bonds such as bridge bonds and aliphatic bonds were found to be twisted, and π–π interactions between the aromatic sheets in the molecule produced adjacent aromatic sheets. This arrangement tends to be approximately parallel, and the total energy decreases from 6713.401 to 2667.595 kJ/mol, among which the bond stretching energy and van der Waals energy dominate. We used 20 bituminous coal macromolecular models to construct aggregated structural models. After optimization by molecular dynamics simulation, the macromolecules were constrained by the surrounding molecules, and the sheet-like aromatic carbon structures that were originally approximately parallel were distorted. The macromolecular structure model of bituminous coal constructed in this study provides a theoretical model basis for the optimal surfactant.

Construction of Macromolecular Structural Models of Coal and Simulation of Adsorption under Acidification

“…The ratio of aromatic bridge carbon to peripheral carbon ( X BP ) in the 13 C NMR structural parameters is a significant parameter for analyzing the size of aromatic clusters and is often used to characterize the average degree of polycondensation of aromatic structures in coal macromolecular structures. X BP can be calculated using eq . , According to Table , the X BP values of the coal samples and the acidified samples were 0.0946 and 0.1292, respectively. X BP = normalf normala B / false( normalf normala H + normalf normala P + normalf normala S false) …”

“…X BP can be calculated using eq 1. 31,32 According to Table 4, the X BP values of the coal samples and the acidified samples were 0.0946 and 0.1292, respectively.…”

In silico Characterization of Natural Blending Agents in Conjunction with Polyhydroxybutyrate (PHB) to Solicit Biopolymer film with Improved Thermal Stability

“…Before starting the simulation, the energy of the system's computational cell needs to be minimized. The "Smart Minimizer" method is a computational technique used to find the lowest-energy configuration of the system (Jing et al, 2022) . Here is the image of pop-up which appears when geometry optimization completes.…”

Molecular Dynamics Simulation of Methane Adsorption and Diffusion: A Case Study of Low-Rank Coal in Fukang Area, Southern Junggar Basin

“…(2) the absorption peaks of coal at 1000~1800 cm −1 are an oxygen-containing functional group; (3) the range from 2800 to 3000 cm −1 is the stretching vibration absorption band of aliphatic hydrocarbon CH x ; and (4) the hydroxyl group has an absorption peak between 3000 and 3600 cm −1 [53].…”