Pyrolysis behavior of solvent-extracted group components from coking coal: Insights into volatile release and source contributions to coke formation

• The pyrolysis characteristics of group components were investigated via Py-TOF-MS. • HC serves as an inert skeleton supporting the coke structure. • DMC releases substantial amounts of 3–4 ring at lower temperatures. • PAHs exist as free phase in DMC and LMC, but are physically embedded in HC. The reactivity and coking properties of coking coal are fundamentally determined by its structural characteristics. A deep understanding of coking coal structure is crucial for scientifically evaluating its coking performance and achieving efficient utilization. Based on the theory of coal embedded structure model, this study comprehensively employed FTIR, Raman, high-temperature stage microscopy (HTSM), and in-situ Py-TOF-MS to investigate the release characteristics and source contributions of primary volatiles from different solvent-extracted group components of coking coal during the coking process. The results revealed significant differences in pyrolysis temperature ranges and behaviors among the group components (heavy component (HC), loose medium component (LMC), dense medium component (DMC)), leading to distinct contributions during the coking process. The HC exhibited a pyrolysis residue exceeding 80 % with minimal morphological change. The LMC showed no significant change below 300 °C but underwent drastic expansion with abundant bubble formation between 400–465 °C. The DMC began softening at 200 °C, displayed intense reactions and high fluidity between 350–460 °C, and experienced a weight loss exceeding 50 % in this stage. Structural characterization indicated that HC is rich in long aliphatic chains (CH 2 /CH 3 ) and minerals, possessing the highest structural order. LMC contained the highest concentration of oxygen-containing functional groups and exhibited the lowest structural order. DMC was enriched in low-condensed aromatic structures, showing the highest aromatic hydrogen ratio. Py-TOF-MS analysis further revealed that HC pyrolysis primarily generated phenolic compounds (phenol 0.66 %, methylphenol 0.79 %, dimethylphenol 0.69 %). In contrast, DMC released substantial amounts of polycyclic aromatic hydrocarbons (PAHs), with relative contents of C 1 –C 3 alkylphenanthrenes ( m / z : 192, 206, 220) reaching 1.46 %, 0.79 %, and 0.76 %, respectively. These PAHs existed predominantly in a free phase and were released primarily at lower temperatures (<300 °C).