The oxidation of heavy oil: Thermogravimetric analysis and non-isothermal kinetics using the distributed activation energy model

• The kinetics parameters of oil oxidation from 30 to 550 °C were determined by DAEM.
• The activation energy vs. conversion curve follows similar pattern to the TG curve.
• The activation energy distribution curve resembles a multi-peak Gaussian pattern.
• TG curves calculated offer a good approach with the experimental data.

The oxidation behavior and kinetics parameters of heavy oil oxidation are highly required to understand the reactivity of crude oil and gain novel recovery routes. In this contribution, thermogravimetric analysis was employed to investigate the oxidation behaviors of one typical kind of Chinese heavy oil, and the distributed activation energy model (DAEM) was applied to obtain accurate kinetic parameters of oxidation reactions from 30 to 550 °C and to bring new insights on the complex reactions and mechanistic understanding. The three stage oxidation – low-temperature oxidation (200 to 320 °C), plateau section (320 to 350 °C), and high-temperature oxidation (above 350 °C) – was observed in the non-isothermal oxidation experiments. E vs. V/V⁎ curve of whole oil oxidation follows similar pattern to the thermogravimetric profile. Thus, low-temperature oxidation and high-temperature oxidation are regarded as two character zones of heavy oil oxidation. The apparent activation energies at low temperatures are around 100 kJ/mol, and at high temperatures are about 190–230 kJ/mol. The curves predicted from kinetic parameters afford a good approach with the experimental data demonstrating the reliability of the available kinetic parameters.

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