Thermal properties of carbonaceous oil shales from the Nagoorin and Condor deposits

Abstract

Infrared transmission spectrometry and thermoanalytical procedures were used to study the thermal behaviour of carbonaceous Nagoorin and Condor oil shales. Pyrolytic kerogen decomposition was monitored by measuring changes in the principal i.r. organic absorption bands. The results show that in the early stages, aliphatic components are removed preferentially leaving, at 50–60 wt% pyrolysis, a wholly aromatic residue. Subsequent decomposition entails carbonization of this residue. Although i.r. spectral changes show the same broad sequence of thermochemical events for each shale, important differences are found by comparing TG/DTG/EGA oxidative profiles. Comparison of each raw shale profile with those for a series of pyrolysed residues of the respective shale suggests that during the initial stages of pyrolysis of Nagoorin carbonaceous shale, polynuclear aromatic compounds break down extensively to yield smaller, more easily oxidized functionalities. However, this is not observed for Condor carbonaceous shale.