Molecular Model Construction of the Dense Medium Component Scaffold in Coal for Molecular Aggregate Simulation

Abstract

Coal as an important fossil energy has been comprehensively studied in terms of its structure, reactivity, and application. However, there are few publications reported about the formation mechanism of coal. In order to explore the molecular mechanism of the formation of the dense medium component (DMC) aggregate, which is extracted from coal, the molecular model of the DMC scaffold (DMC-S) was constructed based on a number of X-ray photoelectron spectroscopy, 13 C NMR, and ultimate analysis. Then, DMC-S was further optimized, and the periodic boundary condition was added for molecular mechanics and molecular dynamics simulation. The DMC-S molecule model with a density of 1.05 g/cm 3 and a different number of unit cells was obtained after the aforementioned experiments and simulations. When the unit cell contained 12 DMC-S molecules, the absolute value of electrostatic energy significantly increased and the peripheral branch chains in DMC-S interlaced with each other, forming a compact aggregate. The density and macrosize calculated values are all slightly lower than the true relative values because the presence of minerals or small molecules was not included in the model construction. Despite some unavoidable defects, the comparison between the simulated and experimental results validates the DMC-S aggregate model and lays a solid foundation for an in-depth study of DMC and its reactivity.

Research on CO2/CH4/N2 competitive adsorption characteristics of anthracite coal from Shanxi Sihe coal mine

“…The 13 C NMR peak positions and chemical shi assignments refer to the research results reported in the literature. [17][18][19] As can be seen from Fig. 1, the 13 C NMR peak tting curve of anthracite is divided into 11 peaks, corresponding to the type and content of carbon functional groups.…”

Pore morphology changes and quantitative analysis and evaluation of high‐rank coal samples after impact

“…In this instance, the original, regular, and round pores will become rough and irregular because the impact force will crack and destroy them, decreasing their roundness 21 . The coal skeleton supports the pores of the coal body, 25,26 and has a certain strength 27 , so the integrity of the coal skeleton will not be affected under the action of small loads. However, when excessive impact loads affect the coal body, a large amount of energy acts on the coal skeleton, resulting in the deformation or fracture of the coal skeleton.…”

“…In the directions of vertical and oblique bedding, the plane porosity and roundness become greater following the impact, while the roundness was reduced in the parallel bedding, indicating the strong impact anisotropy of the micro–nano‐pore structure of high‐rank coal. The impact load changes the pore morphology and size distribution of the coal body, improves the face ratio and roundness of the coal body, increases the pore diameter and depth, and stimulates the pore to become rounded and smooth. However, excessive impact load will cause small molecular compounds in the coal matrix to block the large pores, and also crack and destroy the original regular and smooth pores, thereby reducing the face rate and roundness value of the coal body 23–27 …”

Structural Characterization and Molecular Model Construction of High-Ash Coal from Northern China

“…Understanding the microstructure of coal is conducive to comprehending its reactivity and to exploring its diversity and discrepancy [ 9 , 10 ]. Famous coal models such as those by Wiser, Given, Shinn, and Wender have been used to exhibit the macromolecular structure of raw coal [ 11 , 12 , 13 ].…”