Characterization of nitrogen-containing species in Huadian shale oil by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

The nitrogen-containing compounds in Huadian shale oil (HDSO) produced by pyrolysis of Huadian oil shale at the final temperature of 520 °C in a fixed bed reactor were characterized in detail by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). We find that HDSO contains six basic nitrogen classes, but the other basic N2O1, N2O2, N3 and N3O1 classes determined in US Western shale oil (USSO) and Russian Slanet shale oil (RSSO) are not found in HDSO; while the neutral nitrogen classes are almost the same as those in USSO and RSSO. The basic Nx classes predominate in all basic classes in HDSO, and the relative abundance of the basic N1 class is much higher than that in USSO and RSSO. In HDSO most basic N1 and N1O1 class species consist of the nitrogen-polycyclic aromatic compounds with 1–7 aromatic rings and 0–42 carbon atoms of the alkyl side chains; while the major neutral N1 and N1O1 compounds identified contain 1–5 aromatic rings and 0–35 carbon atoms of the alkyl side chains. Furthermore, pyridines and tetrahydroquinolines which contain 15–28 and 11–24 carbon atoms of the alkyl side chains respectively are dominant in all basic nitrogen species; indoles and carbazoles are the most abundant in all neutral N1 species. The N1O1 species containing 1–4 aromatic rings and 1–24 carbon atoms of the alkyl side chains are relatively abundant. Most likely a substantial amount of the N2 class species identified in HDSO are azaindoles and azaquinlines series.