Product Distribution Characteristics of Dongsheng Long-Flame Coal and Its Vitrinite-Enriched Fraction During Low-Temperature Pyrolysis

As an important type of power and domestic coal, long-flame coal plays a significant role in China’s energy structure. In this study, long-flame coal from Dongsheng, Inner Mongolia (DS) and its vitrinite-enriched fraction (DSV) prepared by organic solvent flotation separation method were selected as research objects. Simultaneous thermal analyzer (TGA), thermogravimetry-gas chromatography-mass spectrometry (TG-GC/MS), and Gray-King assay of coal were mainly employed to investigate their pyrolysis characteristics and differences in pyrolysis products. Results indicate that at the same final pyrolysis temperature, the CO2 content in the pyrolysis gas of DS is higher than that of DSV, while CO, CH4, and CmHn follow the order of DSV > DS. At 400−600 °C, pyrolysis tar mainly comprises monocyclic aromatic hydrocarbons (MAHs), polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons, phenols and other oxygen heteroatom-containing organics (OHCs). Except for aliphatic hydrocarbons and OHCs, the contents of other components reach their maximum values at 500 °C, with peak area intensities of 3.192 × 108, 5.841 × 108, and 8.562 × 108, respectively. In summary, when compared with DS, DSV exhibits more pronounced volatile release and higher reactivity.