Structural determination of heteroatom-containing compounds in an anthracite coal

The chemical constituent and aromaticity of organic matters well correlate with the known compositional and geochemical information of coals. Heteroatom-containing compounds in Zhijin coal, an anthracite, with similar characteristics such as polarity were enriched by sequential extraction with six organic solvents. Components in each extract were well characterised at the molecular level using an orbitrap mass spectrometer coupled with an electrospray ion source. Double bond equivalence of unsaturated heteroatom-containing compounds shows that nitrogen atom may be predominant in the form of N-heterocyclic aromatic rings, including pyridine, quinoline and pyrrole, oxygen atom may exist as ketones, furans and pyrans, and sulphur atom are likely in the forms of sulfoxide, sulfone and thiophenic compounds. For the saturated heteroatom-containing compounds, nitrogen, oxygen and sulphur atoms are mainly presented as amino group, alkoxy and thioether, respectively. Details of such molecular structures provide evidence to optimise catalytic pathways for deoxygenation, denitrogenation and desulphurisation of Zhijin anthracite.