Thermal reactions of kerogen with added water, heavy water and pure organic substances

Finely divided samples of the Messel shale that had first been extracted with organic solvents were subjected to pyrolysis at 330°C for 3 days in the presence of excess water or heavy water and also with added pure organic substances. About 8% of the organic carbon was converted into an assemblage of saturated hydrocarbons that closely resembled petroleum hydrocarbons. No olefins were observed in the products. When the reaction was performed in heavy water, extensive deuteration occurred. The extent of substitution and the position of heavy hydrogen in a variety of hydrocarbon structural types were measured by mass spectrometry. A control experiment in which a saturated hydrocarbon was added showed that this deuterium substitution was not due to simple homogeneous exchange.A mechanism for the production of polydeuterated hydrocarbons is advanced, based on a model wherein the molecular fossils that are chemically bonded into kerogen matrix are released as free radicals. During the subsequent chain reactions, migration of olefinic bonds in intermediates and attack by deuterium free radicals result in multiple deuteration with retention of the carbon skeleton of the molecular fossil.