Structural Characterization and Molecular Simulation of Baoqing Lignite

Area of Science:

• Organic Geochemistry
• Coal Chemistry
• Materials Science

Background:

• Understanding lignite molecular structure is crucial for optimizing its utilization.
• Baoqing lignite's specific composition requires detailed characterization for targeted applications.

Purpose of the Study:

• To elucidate the intricate molecular structure of Baoqing lignite.
• To construct an accurate molecular model and validate it using computational methods.

Main Methods:

• Utilized ultimate analysis, FTIR, XRD, 13C NMR, and XPS for structural analysis.
• Developed a molecular model (C184H199O50N2S) based on experimental data.
• Employed density functional theory (DFT) with M06-2X for molecular configuration optimization.

Main Results:

• Determined lignite aromaticity at 27.64%, with dominant benzene and naphthalene structures.
• Identified aliphatic components as alkyl side chains and cycloalkanes.
• Characterized oxygen (phenol, ether, carbonyl, carboxyl), nitrogen (pyridine, pyrrole), and sulfur (sulfoxide) functional groups.
• Validated the molecular model through simulated FTIR spectra matching experimental data.
• The model revealed a high proportion of aliphatic structures and poorly condensed aromatic rings with irregular spatial arrangement.

Conclusions:

• The study provides a detailed molecular-level understanding of Baoqing lignite.
• The validated molecular model serves as a foundation for predicting lignite properties and behavior.
• Findings are essential for advancing lignite conversion technologies and resource utilization.