Thermogravimetric Analysis of Heavy Oil Oxidation in the Presence of Nickel Based Catalysts

Abstract

This study investigates the catalytic effects of Nickel-ligated catalysts derived from tall oil (NiTO) and sunflower oil (NiSFO) on the oxidation of heavy oil. Thermogravimetric (TG) analysis were employed to assess the thermal behavior and kinetics of heavy oil degradation. The Friedman isoconversional method provided the activation energies (Ea ), which were then used to derive thermodynamic parameters including changes in enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG). The TG analysis revealed that both NiTO and NiSFO influence the degradation kinetics of heavy oil. Moreover, NiTO exhibited a consistent catalytic effect across a wide range of conversions, lowering the onset temperature of degradation and promoting faster degradation rates, which suggests a rapid breakdown at lower temperatures. Conversely, NiSFO demonstrated a substantial decrease in activation energy at mid-range conversions, indicating a highly efficient catalysis during these stages. In addition, thermodynamic analysis indicated that both catalysts alter the energetic profile of the reaction. Notably, NiSFO reduced ΔG significantly at lower conversions, enhancing the spontaneity of the reaction, while NiTO was associated with lower ΔG values across most conversions, implying a more favorable reaction throughout the process. The findings suggest that the choice of catalyst can be tailored based on the desired conversion range and reaction spontaneity in industrial heavy oil processing. These insights could be crucial for optimizing thermal treatments in heavy oil upgrading, offering potential improvements in the efficiency of in-situ combustion and enhanced oil recovery technologies.