Spectral characterization of asphaltene from direct liquefaction of Shengli lignite

A series of asphaltenes were prepared by the direct liquefaction of Shengli lignite under different conditions in this paper. Their structures and compositions were characterized by elemental analysis, FT-IR spectroscopy, UV-vis spectroscopy and Fluorescent spectroscopy. The influences of initial pressure of H₂ and liquefaction temperature on the structure of asphaltene were also discussed. The results indicate that Shengli lignite displays high conversion of liquefaction, and low yield of heavy intermediates such as asphaltene and preasphaltene. The aromatic systems mainly consist of 2~3 rings condensed nucleus and multi-phenyl compounds. To increase the initial pressure of H₂ can promote the hydro-cracking of coal matrix and the removal of hydroxyl group by hydrogenation. High temperature and high pressure of H₂ is favorable for the hydro-cracking of the substituent in AS. By contrast, the fluorescent spectroscopy is an effective technique to characterize the aromatic nucleus of asphaltne. The results characterized by the fluorescence spectra of asphaltene are relation with its H/C atomic ratio.