Purpose: This work aimed to elucidate molecular-level information on low- and medium-rank coals (LMRCs) and to develop precise, controllable conversion routes for upgrading coal from an energy resource to a chemical and functional-material resource.
Main materials and methods: Raw LMRCs, coal-based solid wastes (coal gasification coarse slag, CGCS; coal slime), and coal/straw blends were used. Coal molecular structures were characterized by advanced mass spectrometry, including source-induced collision dissociation, spectrum stitching, and high-energy collision-induced dissociation, combined with machine learning and big-data analysis. Controllable thermochemical conversion was used to prepare functional materials: CeO₂/MnO₂-loaded CGCS catalysts by an impregnation–hydrothermal method; hierarchical porous carbon from coal and straw by co-thermal dissolution and KOH/ZnO template activation; and porous activated carbon from coal slime by one-step KHCO₃ activation at 900 °C. DFT calculations, adsorption tests, and electrochemical measurements were also employed.
Main results: Mass spectrometry provided chemical information on aliphatic chains, aromatic rings, heteroatom positioning, and heteroatom removal during catalytic hydrogenation; machine-learning reclassification helped optimize raw-coal selection and mild conversion parameters. The CGCS-based catalyst achieved 81.7% COD removal in real coal-chemical wastewater, outperforming a commercial catalyst (72.9%), and remained stable after 20 cycles; DFT revealed a two-step phenol oxidation mechanism with aromatic ring opening as the rate-determining step (0.84 eV). Coal/straw-derived hierarchical porous carbon had a specific surface area of 2185 m²/g, heteroatom doping, and a supercapacitor capacitance of 355 F/g with excellent cycling stability. Coal-slime-derived activated carbon had 3D interconnected pores, a surface area of 1557 m²/g, and a phenol adsorption capacity of 327.4 mg/g via π–π interactions, hydrogen bonding, and pore filling.
Main conclusions: Molecular-level characterization combined with big-data-guided and directed thermochemical conversion enables the fine conversion of LMRCs into high-performance catalysts, energy-storage carbons, and adsorbents. The results clarify the relationships among precursor composition, thermal-conversion conditions, and material performance, providing a theoretical and technical basis for the controllable preparation and scaled application of coal-based functional materials.

Low- and medium-rank coal; Fine conversion; Molecular characterization; Thermochemical conversion; Coal-based functional materials.