Thermogravimetric Characteristics and Pyrolysis Kinetics of Nigerian Oil Sands

In the present study, the pyrolysis behavior of Nigerian oil sands was investigated using thermogravimetric analysis. This was done with the aim of deriving kinetic models that can be relevant in the development of the natural resource. The effects of different heating rates (10, 20, and 30 degrees C/min) on oil sand pyrolysis were studied. The results of the study indicated that three regions comprising low-temperature oxidation, devolatilization, and high-temperature oxidation were obtained at all heating rates. The peak temperatures were observed to rise with an increasing heating rate, a phenomenon described as thermal hysteresis. Mineralogical analysis showed the presence of diffraction peaks corresponding to chlorite, quartz, aragonite, dolomite, calcite, and montmorillonite minerals and the notable absence of expandable clay minerals which are known to pose problems during tailing management and the aqueous bitumen extraction process. The kinetic analysis showed that the activation energy increased with the degree of conversion, with the highest activation energy of 14.682 kJ mol-1. The Coats-Redfern kinetic model gave the best model fit for oil sand pyrolysis.

Automated summary

The pyrolysis behavior of Nigerian oil sands was investigated using thermogravimetric analysis in order to develop relevant kinetic models for the natural resource. The study found that oil sand pyrolysis consisted of three regions: low-temperature oxidation, devolatilization, and high-temperature oxidation, at all heating rates examined. Thermal hysteresis was observed, with peak temperatures increasing as heating rates increased. Mineralogical analysis revealed the presence of various minerals but the absence of expandable clay minerals that can cause issues in tailing management and bitumen extraction processes. The kinetic analysis showed an increase in activation energy with degree of conversion, with a maximum activation energy of 14.682 kJ mol-1. The Coats-Redfern kinetic model provided the best fit for oil sand pyrolysis.