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This study aims to compare iso-rank vitrinite-rich and inertinite-rich coal samples to understand the impact of coal-forming processes on pyrolysis chemistry.A medium rank C bituminous coal was density-fractionated to create a vitrinite-rich and an inertinite-rich sub-sample.The vitrinite-rich sample has 83 vol％ total vitrinite (mineral-matter-free basis),whereas the inertinite-rich counterpart has 66 vol％ total inertinite.The vitrinite-rich sample is dominated by collotelinite and collodetrinite.Fusinite,semifusinite,and inertodetrinite are the main macerals of the inertinite-rich sample.Molecular chemistry was assessed using a pyrolysis gas chromatograph (py-GC) equipped with a thermal desorption unit coupled to a time of flight mass spectrometer (MS) (py-GC/MS) and solid-state nuclear magnetic resonance (13C CP-MAS SS NMR).The pyrolysis products of the coal samples are generally similar,comprised of low and high molecular weight alkanes,alkylbenzenes,alkylphenols,and alkyl-subtituted polycyclic aromatic hydrocarbons,although the vitrinite-rich sample is chemically more diverse.The lack of diversity exhibited by the inertinite-rich sample upon pyrolysis may be interpreted to suggest that major components were heated in their geologic history.Based on the 13C CP-MAS SS NMR analysis,the inertinite-rich sample has a greater fraction of phenolics,reflected in the py-GC/MS results as substituted and unsubstituted derivatives.The greater abundance of phenolics for the inertinite-rich sample may suggest a fire-related origin for the dominant macerals of this sample.The C2-alkylbenzene isomers (p-xylene and o-xylene) were detected in the pyrolysis products for the vitrinite-rich and inertinite-rich samples,though more abundant in the former.The presence of these in both samples likely reflects common source vegetation for the dominant vitrinite and inertinite acerals.