Aleksinac oil shale

This paper presents data on isolation and identification of the following types of geolipids from the Aleksinac oil shale, a Miocene lake sediment n-al-kanes, iso- and/or anteiso-alkanes, aliphatic iso-prenoid alkanes, polycyclic isoprenoid alkanes, aromatic hydrocarbons, saturated unbranched, aliphatic isoprenoid, hopanoic, and aromatic mono- and poly-carboxylic acids, fatty acid methyl esters, aliphatic y- and 6-lactones, cyclic y-lactones, aliphatic methyl- and isoprenoid ketones, and the triterpenoid ketone adiantone. Possible origin of the identified compound classes is discussed, particularly of those which had not been identified previously as geolipids. 

The composition and distribution of identified3geolipids suggest (a) that the Aleksinac oil shale is a relatively immature sediment (high content of oxygen compounds with unchanged biolipid molecules, n-alkane CPI values between 1.5 and 2.0, predominance... 

An atmospheric residue of shale oil originating from Aleksinac oil shale (Yugoslavia). 

K (Fig. 4-119). This proves that the model is not suitable for all types of oil shales. Sample K has a relatively high bitumen content, and somewhat different behavior during pyrolysis, compared with samples E and KOR. Most of its organic substance is pyrolyzed at temperatures above 773 K (500 °C) whereas in the case of samples E and KOR and Aleksinac oil shale (sample A) most of the organic material is pyrolyzed at 673-773 K (400-500 °C). 

Most of the geolipids so far identified in the oil shale from Aleksinac represent well known and ubiquitous constituents of sediments n-alkanes, iso- and anteiso-alkanes, aliphatic and cyclic isoprenoid alkanes including steranes, triterpanes and tetrater-panes, aromatic hydrocarbons, and aliphatic, hopanoic and aromatic acids. Moreover, several classes of compounds were identified which were also known as constituents of some ancient sediments but were not found to be ubiquitous, such as aliphatic isoprenoid ketones, aliphatic methyl ketones and the triterpenoid ketone adi-antone. 

The bitumen from oil shale Aleksinac (sample A-B) has two regions of different slopes of the straight line in the plot ln[-ln (l-a)]/I versus 1/T, which result in two different pairs of the Arrhenius coefficients, below and above 420 °C (693 K). The low values of E and log A for the region below 420 °C indicate that evaporation takes place. 

The values of E and log A from the DSC experiments considerably exceed those from TGA. The DSC pyrolysis of oil shale Aleksinac has two endothermal peak maxima. Depending upon the heating rates (j8= 5, 10, 20 K/min) the first peak maxima appear at temperatures of 457 °C, 467 °C, and 477 °C, whereas the second peak maxima appears at 550 °C, 568 °C, and 583 °C. The kerogen concentrate srunple A-K behaves in a similar fashion, whereas the bitumen A-B-773 exhibits only one maximum at temperatures of 148 °C, 454 °G, and 469 C. 

These differences in pyrolysis behavior of the oil shales can be explained by structural differences in the corresponding kerogen types. The kerogens of oil shales Aleksinac, Estonia, and Korea are associated with type I, which is of predominantly paraffinic nature. Oil shale Knjazevac is associated with kerogen type HI, which is of predominantly aromatic nature. Thus the multi-step model appears to be suitable for simulating the pyrolysis of oil shales with kerogen type I, but cannot be properly adjusted for the other kerogen types. 

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