Thermoanalytical characterization of precipitated acids obtained by alkaline permanganate degradation of the kerogen from Aleksinac (Yugoslavia) oil shale

The precipitated acids, obtained by partial stepwise oxidation of Aleksinac (Yugoslavia) shale kerogen, were studied by thermal analysis. Significant differences were observed in the weight loss and the shape of TG curves of precipitated acids from various degradation steps, indicating their structural differences and heterogeneity of the kerogen. The thermal curves of precipitated acids were found to consist of two distinct parts. From IR data it was found that the low-temperature part corresponded to thermal changes of aromatic, and the high-temperature part of aliphatic type structures. These results were in good agreement with chemical analysis (elemental analysis, atomic H/C ratio, total acidity) of the same acids.