Characterization of nitrogen-containing aromatics in Baiyinhua lignite and its soluble portions from thermal dissolution

Abstract Soluble portions (SPs) 1–4 (SP 1 -SP 4 ) were afforded from sequentially dissolution and alkanolyses of Baiyinhua lignite (BL) in cyclohexane, CH 3 OH, CH 3 CH 2 OH, and (CH 3 ) 2 CHOH at 300 °C. They were analyzed with a gas chromatograph/mass spectrometer and quadrupole exactive orbitrap mass spectrometer (QEOTMS) with an atmosphere pressure chemical ionization source in positive-ion mode, while BL was characterized with an X-ray photoelectron spectrometer (XRPES). The results show that the yields of SP 2 and SP 3 are much higher than those of SP 1 and SP 4 , and the total SP yield is ca. 39.0%. According to the results of the analysis with XRPES, pyrrolic nitrogens are the most abundant nitrogen existing forms in BL. Thousands of nitrogen-containing aromatics (NCAs) were resolved with QEOTMS and their molecular masses are mainly in the range of 200–450 u . The main NCAs are N 1 O 1 and N 1 O 2 class species with double bond equivalent values of 4–18 and carbon number of 7–30. The nitrogen atoms appear in pyridines, quinolines, benzoquinolines or acridine, and dibenzoquinolines or naphthoquinolines, while the oxygen atoms exist in methoxy and furan rings.