FLASH PYROLYSIS-GAS CHROMATOGRAPHY OF THE KEROGEN AND ASPHALTENE FRACTIONS-ISOLATED FROM A SEQUENCE OF OIL SHALES

Molecular characterization of the kerogen and asphaltene fractions isolated from three oil shales taken at increasing depth from the same deposit was carried out by means of flash pyrolysis-gas chromatography. Pyrolysis products were detected by simultaneous flame ionization detection and sulphur-selective flame photometric detection using a stream splitter at the end of the capillary column. n-Alkanes, n-alk-1-enes and sulphur compounds represent the major pyrolysis products of both kerogen and asphaltene fractions. Organosulphur compounds were only detected in the kerogen fractions and were completely absent from the asphaltene fractions. A sequential removal of thiophenes was observed in the set of kerogens. It is suggested that breakdown of sulphur-sulphur and carbon-sulphur bonds may occur preferentially in the kerogen macromolecule rather than the breakdown of carbon-carbon bonds to give rise to the asphaltenes.