Kerogen production from

Kerogens isolated from the Fig Tree cherts produced very complex mixtures of pyrolysis products, dominated by a series of methyl branched alkenes with each member of the series having 3 carbon atoms more than the previous member. At each carbon number a highly complex mixture of branched alkanes and alkenes plus various substituted aromatic compounds was found. The highly branched structures may have actually incorporated isoprenoids originally present in the Precambrian microorganisms (Philp Van DeMent, 1983)6>. 

It has been recently shown that the most abundant sulfur-containing pyrolysis products of kerogens isolated from immature organic-rich... 

Pyrolysates. The quantities of products from the pyrolysis experiments on the two kerogen samples, along with elements and isotope analysis... 

Increased knowledge of the molecular transformations which occur during oil shale pyrolysis (retorting) is essential for maximizing the yield and quality of products from this vast source of hydrocarbons. Compared to other sources such as petroleum and coal, there is little known about the molecular structure of the insoluble organic material (kerogen) in oil shale. There is... 

The toluene-soluble products from each reacted kerogen were subjected to SARA analysis (saturates, aromatics, resins, asphaltenes) (22). The B toluene solubles gave almost 91% asphaltenes. The C kerogen toluene solubles were almost 81% asphaltenes. The C toluene solubles were more difficult to handle 14.5% of the material was unrecovered from the chromatographic column. 

TABLE 17.8 Percent Elemental Composition by Weight of Kerogen and Products from Retorting of Oil Shale ... 

Fig. 23. Rate of gas production from oil shale (open points) and kerogen (shaded points), o, H2 a, CO o, CH4 v, C2H ...

The model results discussed above express only the effects time and temperature on organic acid production from kerogen, and the effect of porosity on organic acid concentrations. They do not account for the effects of time and temperature on organic acid decarboxylation. Therefore, the results are best applied to Neogene and source rocks where the field data discussed earlier indicate that decarboxylation effects on total acetate concentrations are small, where temperatures do not exceed approximately 150 C. 

Synthetic fuels derived from shale or coal will have to supplement domestic suppHes from petroleum someday, and aircraft gas turbine fuels producible from these sources have been assessed. Shale-derived fuels can meet current specifications if steps are taken to reduce the nitrogen levels. However, extracting kerogen from shale rock and denitrogenating the jet fuel are energy-intensive steps compared with petroleum refining it has been estimated that shale jet fuel could be produced at about 70% thermal efficiency compared with 95% efficiency for petroleum (25). Such a difference represents much higher cost for a shale product. 

Recently, researchers have detected 2,5-dimethylfuran and 2-methylfuran and normal alkanes in kerogen of the 2.7 x 109 year old Belingwe, Rhodesia stromatolites, by the method of pyrolysis/ GC/MS [26]. They concluded that although furans could probably be derived from many compounds, their probable origin is in bacterial and algal sugars, and that the alkanes are either products of decarboxylation of fatty acids or unaltered constituents of ancient organisms. 

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