FTIR microspectroscopy of particular liptinite- (lopinite-) rich, Late Permian coals from Southern China

Abstract

The Late Permian coals from Southern China are unique in their high content of lopinite (liptinite) and elemental hydrogen and typically produce high yields of tar. Typical of the Late Permian coals of Southern China, the coals used in this study show special petrographic and chemical characteristics, as well as significant oil-producing potential. Studies of these coals and of their content of the lopinite maceral will help to explain the genesis of both the lopinite maceral and of the oil-producing potential of the coals. In this study, an FTIR spectrometer was used in the standard transmission mode to generate the IR spectra of the whole coal. An FTIR spectrometer, equipped with a microscope in the reflectance mode, was used to analyze the chemical structure of individual coal macerals, including lopinite, vitrinite, semifusinite and inertinite. The chemical structure of lopinite is characterized by its higher content of longer and less branched aliphatic side chains and distinct C=0 groups. The oil-producing potential of the coals is attributed to their higher content of lopinite.