Relation between the deposition and petrology of Shanxi coals and the composition of their extracts

The soluble organic material present in a set of 12 coal samples representing three major episodes of coal deposition in Shanxi Province, North China, has been examined. Shanxi coals, like those from Gondwanaland, contain little liptinite and accordingly the material extracted by pyridine yields only small quantities of n-hexane soluble n-alkanes, steranes and hopanes identifiable by gas-chromatography/mass spectrometry. The distribution of the n-alkanes is characteristic of the environment from which each of the Shanxi coals was formed but the distribution of the branched alkanes is generally determined by the dia- and catagenesis each coal experienced. Aromatic compounds identified in the extracts typify the small molecules present within the vitrinite lattice. Technologically significant benzene–methanol extracts deriving from vitrinite–inertinite have been characterised by proton NMR spectroscopy and partially separated by HPLC.

► Describes the three different depositions of the important Shanxi coals. ► Reveals n-alkanes as biomarkers of the original vegetation in the depositions. ► Demonstrates branched alkane distributions to be determined by catagenesis. ► Identifies industrially important extractable aromatic compounds within the vitrinite. ► Shows benzene–methanol extracts to be resolvable by HPLC.