Research Status and Development Trend of Macromolecular Structure and Model Construction of Different Coals

ABSTRACT Coal is a natural macromolecular substance composed of complex organic molecules and a small amount of minerals. Its chemical composition and microstructure are highly complex and variable, and no unified definition exists. This inherent structural complexity underscores the theoretical significance of constructing accurate macromolecular models to elucidate the multiphase reaction mechanisms involved in gasification, pyrolysis, and combustion processes. This paper provides a systematic review of the structural features and development trends of molecular models for representative coal ranks, including lignite, bituminous coal, and sub‐bituminous coal. Advanced multi‐scale structural features were characterized through a combination of techniques, such as solid‐state 13 C nuclear magnetic resonance ( 13 C‐NMR), X‐ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy; this study conducts a comprehensive analysis of key structural parameters in coal, such as the aromatic condensation degree, functional group distribution, and heteroatom occurrence. Based on simulation methods, the microscopic structure, physicochemical properties, and reaction mechanisms of coal can be systematically investigated. The rationality of coal molecular modeling can be further verified by vibrational spectroscopy simulation and covalent bond concentration correction. This paper provides theoretical support for scholars in the field to understand coal properties under different conditions and to carry out model construction and validation.