Characterisation of some Australian oil shale using thermal, X-ray and IR techniques

Thermogravimetric analysis (TGA), Diffuse Reflectance Infrared Fourier Transforms Spectroscopy (DRIFTS) and X-ray diffraction (XRD) were used in conjunction to characterise oil shale samples from an Australian Tertiary oil shale deposit. Results from these techniques were compared with conventional Modified Fisher Assay (MFA) data. DRIFTS and TGA results showed clear correlations with each other as well as with the MFA values. DRIFTS results indicated that most of the kerogen is in aliphatic hydrocarbon form. It was evident from TGA analysis that the weight loss in the 450-550 °C temperature region has a strong and direct correlation with the amount of oil in the samples, as determined by the MFA method. Calibration curves were generated in which oil content can be predicted from TGA and DRIFTS data. The combination of TGA and DRIFTS is mostly useful in examining organic matter in oil shale while DRIFTS and XRD combination is useful in examining the minerals phases. XRD and DRIFTS showed good agreement in identifying the presence of minerals such as quartz, clay and carbonates. Combination of these three techniques can provide an alternative and inexpensive method to the MFA analysis in determining the kerogen content, while overcoming the limitations of each other.