Effects of Pyrolysis Temperature and Simulated Formation Stress on Tar Yield and Composition of Tar-Rich Coal

To clarify the effects of pyrolysis temperature and simulated formation stress on the tar yield and composition of Baishihu tar-rich coal, lump coal pyrolysis experiments were conducted using coal from the Baishihu Mine in the Naomaohu mining area, Xinjiang, at pyrolysis temperatures of 200–700 °C under no external stress and 15 MPa simulated formation stress conditions. Product yields were analyzed, and the chemical composition of tar was characterized using gas chromatography–mass spectrometry (GC–MS), with component abundances expressed as normalized relative peak areas. The results showed that the maximum tar yields were obtained at 400 °C under both stress conditions, reaching 9.53% and 8.81%, respectively. With increasing temperature, tar composition exhibited a stagewise evolution: oxygen-containing compounds were relatively enriched at low temperatures; aliphatic hydrocarbons showed a high relative peak area proportion at 400 °C; monocyclic aromatic hydrocarbons became significantly enriched at 500 °C; and the tar composition further evolved toward polycyclic aromatic structures at high temperatures. The 15 MPa simulated formation stress decreased the tar yield at 400 °C but altered the internal component distribution of tar, resulting in the relative enrichment of aromatic components. The results indicate that pyrolysis temperature and simulated formation stress jointly influence tar composition evolution of Baishihu tar-rich coal, and 400–500 °C represents a temperature range of particular interest for Baishihu tar-rich coal pyrolysis.