Journal / Book Title
Proceedings,1988 Eastern Oil Shale Symposium
Recent advances now permit the separation of coal into constituent macerals of high purity using density gradient centrifugation (DGC). With the availability of pure macerals, the chemical structure of each can be investigated separately, without the interactive interference of the other macerals or mineral matter. The present study is a preliminary effort applying these methods to the study of oil shale kerogen.
We have used a sample from the Huron Member of the Upper Devonian Ohio Shale from Logan County, Ohio. Whole rock petrographic examination revealed intact Tasmanites, telalginite of unknown derivation and a weakly fluorescing matrix. Pyrite is abundant, including framboidal and euhedral pyrite imbedded within macerals. The kerogen concentrate was subjected to DGC. The resulting profile shows a single, broad main peak, consisting of mixed telaginite, amorphinite and rare vitrinite. Variable amounts of entrapped minerals apparently account for the broad range of density within the peak, with the organic assemblage being fairly consistent. In future work, it is recommended that the kerogen be micronized prior to DOC to permit a cleaner separation.
In order to investigate the chemistry of macerals, pyrolysis is preferred over simple extraction, since soluble native bitumen is mobile and may migrate from the maceral of origin into a neighboring one, acting as a natural contaminant. Pyrolysis techniques assure that the data reflect the nature of indigenous material only. The Ohio Shale kerogen and 4 DGC fractions were subjected to micro-scale, anhydrous, in vitro pyrolysis, followed by GCMS of the saturate and aromatic LC fractions of the pyrolyzate. The 4 DGC fractions are nearly identical in both their saturate and aromatic molecular distributions, consistent with the petrographic observations. To further demonstrate the efficacy of the method, a pure sporinite isolated from a coal in the Pennsylvanian Brazil Formation of Indiana was also analyzed. The sporinite pyrolyzate can readily be distinguished from that of the Ohio Shale alginite by the distributions of n-alkanes, isoprenoids, phyllocladane derivatives, extended tricyclic terpanes, hopanes, moretanes, steranes, alkylbenzenes and thiophene derivatives. Py-LC-GCMS is an effective and versatile characterization tool, as it provides a great number of molecular parameters.
Institute for Mining and Minerals Research, Lexington, Kentucky
MSU Digital Commons Citation
Kruge, Michael A.; Rimmer, Susan M.; and Crelling, John C., "Organic Geochemical and Petrographic Analysis of Pure Macerals from the Ohio Shale" (1989). Department of Earth and Environmental Studies Faculty Scholarship and Creative Works. 93.
Kruge, M.A., Rimmer, S.M. and Crelling, J.C., 1989, Organic geochemical and petrographic analysis of pure macerals from the Ohio Shale. In, Lazar, D.J., ed., Proceedings,1988 Eastern Oil Shale Symposium, Institute for Mining and Minerals Research, Lexington, Kentucky, p. 411-417.