Raman-Validated Macromolecular Model of SG Coking Coal: ESP–FMO Mapping Unravels Site-Selective Oxidation in Combustion

Based on comprehensive experimental datasets—proximate/ultimate analyses, XPS, solid-state 13C NMR, and Raman spectroscopy—we constructed and optimized a compositionally faithful macromolecular model of SG coking coal. Using density-functional theory (DFT) calculations, we simulated electrostatic-potential (ESP) fields and frontier molecular orbitals (FMO) to probe elementary oxidation steps relevant to combustion, and focused on how heteroatom speciation and carbon ordering govern site-selective reactivity. Employing multi-peak deconvolution and parameter synthesis, we obtained an aromatic fraction fa = 76.56%, a bridgehead-to-periphery ratio XBP = 0.215, and Raman indices ID1/IG ≈ 1.45 (area) with FWHM(G) ≈ 86.7 cm−1; the model composition C190H144N2O21S and its predicted 13C NMR envelope validated the structural assignment against experiment. ESP–FMO synergy revealed electron-rich hotspots at phenolic/ether/carboxyl and thiophenic domains and electron-poor belts at H-terminated edges/aliphatic bridges, rationalizing carbon-end oxidation of CO, weak electrostatic steering by O2/CO2, and a benzylic H-abstraction → edge addition → O-insertion/charge-transfer sequence toward CO2/H2O, with thiophenic sulfur comparatively robust. We quantified surface functionalities (C–O 65.46%, O–C=O 24.51%, C=O 10.03%; pyrrolic/pyridinic N dominant; thiophenic-S with minor oxidized S) and determined a naphthalene-dominant, stacked-polyaromatic architecture with sparse alkyl side chains after Materials Studio optimization. The findings are significant for mechanistic understanding and control of coking-coal oxidation, providing actionable hotspots and a reproducible workflow (multi-probe constraints → model building/optimization → DFT reactivity mapping → spectral back-validation) for blend design and targeted oxidation-inhibition strategies.