Continuous monitoring of the oxidation of algal- and humic-type kerogen in a heated FTIR flow cell

Changes in the IR spectra of algal- and humic-type kerogens was studied during experimental oxidation of self-supported rock pellets in a mixed nitrogen/oxygen (1:1) stream over a period of 10 h at a temperature of 190°C. This new method has the advantage that it enables the study of organic materials, with high ash contents, to be made during a short oxidation period. It was found that in the oxidation of algal-type kerogen, three times more alkyl species were consumed to produce the same integral intensity of the oxygen-containing species compared with humic-type kerogen. A detailed analyses of the complex overlapping 1500–1900 cm−1 bands of the IR spectra, using Fourier self-deconvolution and/or second derivative mode and separation of the individual bands, has shown a preferential increase in the number of phenyl ester groups compared with aryl–alkyl ketone and ester groups with increasing time of oxidation in both types of kerogen.