Evaluation and comparison of thermodynamic and kinetic parameters for oxidation and pyrolysis of Yarega heavy crude oil asphaltenes

The processes of pyrolysis in atmosphere of nitrogen and oxidation in air were compared for asphaltenes extracted from Yarega heavy crude oil and its atmospheric and vacuum residues. Thermogravimetry, differential scanning calorimetry and kinetic studies were applied to estimate kinetic parameters of the asphaltenes samples. Different stages of pyrolysis and oxidation were determined and their temperatures were estimated. The steps of pyrolysis and oxidation obtained through different methods were compared. The asphaltenes from atmospheric residue and heavy parent oil showed two pyrolysis stages. Only one stage was distinguished for vacuum residue asphaltenes. Three stages were described for oxidation process. The values of rate of mass loss, heat flow, heat consumption and activation energy were calculated for conversion stages. Data from conversion studies was interpreted through physical processes. The obtained results can contribute to the development of methods for asphaltenes processing in petroleum refineries.