Functional groups in kerogen

The Functional Marker Method (26) was developed with the specific goal to determining directly and specifically organic functional groups in kerogens. 

Oxygen Functional Groups in Green River Oil-Shale Kerogen and Trona Acids... 

Fester, J. I. and Robinson, W. E. (1966). Oxygen functional groups in Green River oil shale kerogen and trona acids. Coal. Sci. (Adv. Chem. Ser.) 55, 22-24. 

Fig. 4.14 Distribution of oxygen-containing functional groups in the three main types of kerogen with increasing maturity (after Behar Vandenbroucke 1987). See Fig. 4.15 for positions of samples on a van Krevelen diagram and Table 4.8 for additional compositional data.

In all of the functional group tests of kerogen, the inorganic material removed from the oil shale by attrition grinding was used as a mineral blank. Because pyrite was concentrated with the kerogen and was not separated with the mineral, pyrite equivalent to that present in the kerogen concentrate was added to the mineral blank. 

The similarity of kerogen and trona acids is indicated by their elemental compositions shown in Table I. In both materials the carbon to oxygen ratio indicates the presence of considerable quantities of oxygen functional groups. 

Infrared and Raman spectrophotometry have become established as worthwile tools in the study of metamorphosed chemofossils. The spectra show which functional groups predominate in immature kerogen and what changes occur during maturation (Fig. 15). 

Less explicit statements can be made concerning the origin of other sulfur-containing moieties (e.g., cyclic and acyclic (poly)sulfide moieties), since the Py-GC-MS method fails to properly characterise these functional groups. However, it is noteworthy that small amounts of alkylthiolanes and -thianes with linear carbon skeletons have been identified in kerogen pyrolysates (48), This suggests the presence of thiolane and thiane moieties in the kerogen... 

A partial characterization of the organic matter may be made -specially for the highly complicated macromolecules present in or-ganites, like the kerogen - through the characterization of functional groups. 

This method was used to determine the content of various organic functional groups (amines, alcohols, phenols, aldehydes, ketones, carboxyl, insaturation, allylic/benzylic sites) in kerogens of Brazilian oil shales. The results (26) indicate the Tremembe Formation as being the most functi.onatTzed while Irati is the least. This is in accordance with the accepted trend that functionalizations correlates with maturity. 

Infrared (I.R.) spectra of kerogens were obtained using thin (1 mm) discs of kerogendispersed in KBr. The resulting spectra were checked for the presence of absorbance bands due to various functional groups. 

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