Xianfeng lignite (XL) was subjected to sequential thermal dissolution (TD) in cyclohexane at 200-320 °C. The yields of soluble portions (SPs) decreased with raising temperature from 200 to 260 °C, but then increased with further raising the temperature. The SPs were analyzed with a Fourier transform infrared spectrometer, gas chromatograph/mass spectrometer, and atmospheric pressure solid analysis probe/time-of-flight mass spectrometer (ASAP/TOF-MS). The results show that cyclohexane is effective for thermally extracting inherent hydrocarbons in XL without breaking the covalent bonds. Intermolecular interactions such as hydrogen bonds, π-hydrogen bonds, and π-π interactions can be destroyed at higher temperatures and thereby release arenes and arenols trapped in the capsule structure of XL. According to ASAP/TOF-MS analysis, the molecular mass of organic species in the SPs is smaller than 550 u and SPs from different TD temperatures have different molecular mass distributions. The organic species detected with ASAP/TOF-MS have double bond equivalent values ranging from 0 to 11 and carbon numbers from 3 to 35. A series of arenes and alkylarenols were also confirmed by ASAP/TOF-MS analysis.
Wang, T. M., Zong, Z. M., Liu, F. J., Liu, C., Lv, J. H., Liu, J., … Li, Y. (2015). Investigation on compositional and structural features of Xianfeng lignite through sequential thermal dissolution. Fuel Processing Technology, 138, 125–132. https://doi.org/10.1016/j.fuproc.2015.04.029