Type Ⅰ kerogen-rich oil shale from the Democratic Republic of the Congo: mineralogical description and pyrolysis kinetics

作者：Rajaa Bouamoud; Ely Cheikh Moine; Raphaèl Mulongo.Masamba; Adnane El Hamidi; Mohammed Halim; Said Arsalane^*

来源：Petroleum Science, 2020, 17(01): 255-267.

The Democratic Republic of the Congo holds important reserves of oil shale which is still under geological status. Herein, the characterization and pyrolysis kinetics of type Ⅰ kerogen-rich oil shale of the western Central Kongo(CK) were investigated.X-ray diffraction, Fourier-transform infrared spectroscopy and thermal analysis(TG/DTA) showed that CK oil shale exhibits a siliceous mineral matrix with a consistent organic matter rich in aliphatic chains. The pyrolysis behavior of kerogen revealed the presence of a single mass loss between 300 and 550 °C, estimated at 12.5% and attributed to the oil production stage.Non-isothermal kinetics was performed by determining the activation energy using the iterative isoconversional model-free methods and exhibits a constant value with E = 211.5 ± 4.7 kJ mol.1. The most probable kinetic model describing the kerogen pyrolysis mechanism was obtained using the Coats–Redfern and Arrhenius plot methods. The results showed a unique kinetic triplet confirming the nature of kerogen, predominantly type Ⅰ and reinforcing the previously reported geochemical characteristics of the CK oil shale. Besides, the calculation of thermodynamic parameters(ΔH*, ΔS* and ΔG*) corresponding to the pyrolysis of type Ⅰ kerogen revealed that the process is non-spontaneous, in agreement with DTA experiments.