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 Jt 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.
A method is proposed which, in principle, permits resolution of complex TG curves into elementary curves. The method is based on appropriate preheating of the substrate. In fact, the method represents partial differential thermogravimetric analysis (PDTG). In this paper it was used, together with IR spectroscopy, for analysis of the precipitated acids obtained by partial oxidation of the kerogen from an oil shale. The precipitated acids were found to consist of five components, characterized by similar thermal properties. General qualitative and quantitative characteristics of the individual components are suggested.
The chemical nature of the kerogen from Aleksinac (Yugoslavia) oil shale was studied by thermal analysis of a kerogen concentrate and the partially degraded kerogen concentrates obtained as intermediates in ~ts stepwise alkaline permanganate oxidation. The initial kerogen concentrate decomposed in the range 200-550Oc and the DTG profile consisted of several overlapping peaks. The partially degraded kerogen concentrates were thermally more stable. Their thermograms consisted of two distinct parts: the low-(150-4200C) and the hightemperature (420-650~ part. Each of them was complex, involving two or more components. On the basis of IR data, it was suggested that the low-temperature part corresponded to the thermal degradation of aliphatic, and the high-temperature part to the degradation of aromatic components.
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