Filling behaviour of small molecules in the dense medium component of coal: molecular dynamics simulations based on a novel embedded structure model

ABSTRACT

Dense medium component (DMC) is a group component of coal, which is composed of macromolecular skeleton aggregate embedded by small molecules. Previously, the dense medium component skeleton (DMC-S) aggregate model was established. In this paper, the DMC-S aggregate model was characterised and the behaviour of small organic molecules filling the DMC-S aggregate was investigated by Molecular dynamics (MD) method. The energy change was the largest when olefins were filled into the DMC-S aggregate, followed by alkanes and aromatics, because most of the small olefin molecules were embedded into the DMC-S aggregate in a network-embedded state that depends on intermolecular hydrogen bonds and π-σ hyperconjugation. In contrast, aromatic molecules were relatively incompatibility with the DMC-S aggregate and primarily presented in a free state on the surface of the macromolecular network. The simulation results are in good agreement with the studies on the leaching behaviour of olefins, aromatics, and alkanes in the coal extraction process, indicating that the molecular dynamics simulation technique is a useful method in the field of coal structure.

KEYWORDS:

• DMC-S aggregate
• small organic molecules
• filling
• molecular dynamics simulation

Disclosure statement

No potential conflict of interest was reported by the authors().

Additional information

Funding

This work was financial supported by National Science Foundation of China (No. 51674260).