Solid state C NMR studies of selected oil shales from Queensland, Australia

Solid state ¹³C NMR techniques of cross polarization with magic-angle spinning, and interrupted decoupling have been employed to examine the nature of the organic matter in eight kerogen concentrates representing five Tertiary deposits in Queensland, Australia. The NMR results show that five of the kerogens have high proportions of aliphatic carbon in their organic matter and correspond to Type I–II algal kerogens. Three of the kerogens, derived from carbonaceous shales, have a high proportion of aromatic carbon in their organic matter and correspond to Type III kerogens. The fractions of aliphatic carbon in all the kerogens, regardless of type, are shown to correlate with the conversion characteristics of the corresponding raw shales during Fischer assay. Interrupted decoupling NMR results show the presence of more oxygen-substituted carbon in the carbonaceous shales, which may account for the greater CO₂ evolution and phenolic materials found in the pyrolysis products of the carbonaceous shales.