Study on coal pyrolysis characteristics by combining different pyrolysis reactors

• Combining TG, Py-GC/MS, and Gray-King assay reveals distinct coke yield trends: G-K > TG > Py, with secondary reactions contributing significantly to G-K coke yield. • Fast pyrolysis exhibits stronger coal molecular fracture, yielding more oxygenated compounds, mono-ring aromatics, and aliphatics, with phenolics increasing from 15.49% to 35.17%. • Multi-ring aromatics decrease dramatically from 23.13% to 2.36% in fast pyrolysis, indicating enhanced cracking of heavy aromatic structures. • Secondary reactions in slow pyrolysis (G-K) include alkane/ester cleavage, condensation of mono-ring aromatics with alkenes, ring opening, isomerization, and hydrogenation, informing reactor design for tar upgrading.