Low-temperature oxidation of Lloydminster heavy oil: Kinetic study and product sequence estimation

Low-temperature oxidation (LTO) of Lloydminster heavy oil samples was investigated for a basic understanding of the reaction kinetics and an estimation of the product sequence. Ramped temperature oxidation experiments and isothermal experiments at seven different temperatures from 50 to 350 °C were performed to observe the thermal oxidation behavior of this heavy oil and to find kinetic parameters of the oxidation during LTO. The results reveal that there were four different subzones within the LTO zone. This is similar to previous findings for an Alaska heavy oil. The first and third subzones had positive activation energies, whereas the second and fourth subzones had negative activation energies. Compared to the sample from Alaska, the Lloydminster heavy oil exhibited higher derivative weight loss values, a higher order of reaction and lower activation energy. From each isothermal experiment, an elemental analysis conducted on the residue suggested that aldehyde is a major LTO product in the first subzone; alcohols and ketones are the major products in the second subzone; hydroperoxide and carboxylic acids dominate the third subzone; and, ketones and hydroperoxide are the major products of the fourth subzone.