Investigation of the possible role of fatty acids and alcohols as precursors of normal hydrocarbons generated during vacuum pyrolysis of a young kerogen

Significant amounts of fatty acids and alcohols, in addition to straight-chain hydrocarbons, were observed in the vacuum pyrolysate of a young kerogen isolated from a fresh-water sediment. The amounts and the distribution patterns of fatty acids and alcohols were compared with those indigenous to the original kerogen, as determined by solvent extraction followed by saponification extraction. Straight-chain fatty acids in the pyrolysate were 12.7 mg/g kerogen, while those extracted from the original kerogen were 10.5 mg/g. The amounts of fatty alcohols in the pyrolysate and in the extracts were 1.31 and 1.10 mg/g. respectively. The excess amounts in the pyrolysate were explained by the release of a strictly bound form of fatty acids and alcohols, which were left in the kerogen matrix even after the saponification extraction. The results indicated that most fatty acids and alcohols were not decomposed as a result of the vacuum pyrolysis and that neither fatty acids nor fatty alcohols should be viewed as the prime precursors of the straigth-chain hydrocarbons (4.6 mg/g) simultaneously generated during vacuum pyrolysis.