Neutron scattering study of vitrinite: Insights into sub-micrometer inclusions in North American Carboniferous coals of bituminous rank

The higher-rank vitrinites contain much larger monodisperse inclusions having diameters of ~ 50 nm, concentrations of ~ 1014 cm− 3, large surface-to-volume ratios, and fuzzy interfaces with the organic matrix. Inclusions of a similar size and concentration are also present in the lowest-rank sample, but are much less frequent than the small inclusions. We provisionally interpret those objects as inclusions of mineral matter, most likely associated with original plant material. The internal specific surface area (SSA) calculated for the small mineral matter inclusions is ~ 100 m2/cm3 and for the large inclusions ~ 2 m2/cm3.