Characterization of heteroatom class species in asphaltenes from medium/low temperature coal tar

Abstract

ABSTRACT The classes, structures, and distributions of heteroatom compounds in asphaltenes from medium/low temperature coal tar (LCT) were characterized by using positive-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The NX, S1OX, S2OX, SX, S1N1OX, OX, N1OX, N2OX, N3OX, S1NX, and S2NX class species were identified in LCT asphaltenes. The O1 class species were the most abundant species of the total heteroatom class species, of which structures were likely furan derivatives or ketone oxides. There were mainly N1 class species of the basic nitrides, and the structures were likely pyridine derivatives with DBE of 16 − 25. The S1 class species were predominant of the sulfur-containing compounds, of which structures were likely thiophene derivatives or thioether derivatives with low degree of condensation. Nitrogen oxides of LCT asphaltenes mainly belong to N1O1 class species composed of 4 − 8 aromatic rings with a keto group and a pyridine ring. The sulfur oxides were mainly S1O1 class species consisted of 5 − 8 aromatic rings with a thiophene sulfoxide ring. The oxygen and sulfur heteroatoms in LCT were mainly concentrated in asphaltenes, which were mainly high-condensation compounds. The N1 class species in LCT asphaltenes have a higher degree of condensation, which occupied only smaller proportion in LCT.