Comparative investigation of low temperature oxidized and pyrolyzed cokes from the inferior heavy oil: Structural feather, thermo-oxidation behavior, and kinetics

Abstract

It was crucial to study the low temperature coking process for the heavy oil, which affected the fuel availability and subsequent in-situ combustion progress. From this perspective, low temperature coking experiments with different atmospheres were accomplished for the inferior heavy oil to obtain oxidized (cokeLTO) and pyrolytic (cokeLTP) cokes, which were further employed to trace structural feathers via joint analysis of elemental analysis, Fourier transform infrared spectrophotometry (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra, and to characterize thermo-oxidative characteristics and kinetics via different thermal analyses (TG-DTG/DSC) and model-free methods. The results showed that a relatively less aliphatic and more aromatic structures were contained in cokeLTO with a relatively higher proportion of C-O, C = O, O-C = O groups and C/H ratio, implying that oxygen atom was served as the promoter to replace hydrogen atom and accelerate macromolecular structure formation. While the decomposition and conversion of N- and S- functional groups were complicated and insensitive to the coking atmosphere. Furthermore, cokeLTO had a more dominant thermo-oxidation behavior than cokeLTP with better exothermic characteristic and lower activation energy distribution. From this study, it could provide a vital piece of updated insights on the role of low temperature oxidation process in coke deposition and feature.