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

Abstract

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.

Thermoanalytical characterization of Aleksinac (Yugoslavia) oil shale kerogen

“…The resolution between two complex peaks was increased during chemical degradation and similar behaviour was found for precipitated acids [4,5]. The different thermal behaviour of KC-15 was probably a result of drastic chemical degradation.…”

“…2, in contrast with the f'mdings on the precipitated acids [4], did not fully confirm this observation, although all partially oxidized concentrates showed lower aromatic peaks in comparison with KC-0. 2, in contrast with the f'mdings on the precipitated acids [4], did not fully confirm this observation, although all partially oxidized concentrates showed lower aromatic peaks in comparison with KC-0.…”

“…The kerogen concentrate of Aleksinac (Yugoslavia) oil shale denoted KC-0 [4] was partially degraded by stepwise alkaline permanganate oxidation. The stepwise oxidation provided two related sets of solid degradation products, differing in the degree of degradation, a set of precipitated acids (from steps 1, 2-3, 4-6, 7-9, 10-12 and 13-15), which were studied earlier [4,5], and a set of partially degraded kerogen concentrates (originating from steps 1, 3, 6, 12 and 15) for inyestigation in this paper.…”

“…(a) thermally, the precipitated acids were more stable [4,5] than the precursor kerogen or its residue in the kerogen concentrates. A similar relationship was found between humic acids and their possible precursors, lignin and cellulose [9,10].…”

“…Five identical 3.34 g portions of KC-O were subjected separately to stepwise alkaline permanganate degradation according to the procedure described earlier [2][3][4][5]7]. The kerogen concentrates were dispersed in 100 cm 3 1.6% KOH and oxidized at 75 ~ with 0.50 g portions of KMnO4.…”