Kinetic analysis of the thermal decomposition of Colombian vacuum residua by thermogravimetry

Five different Colombian vacuum residues were thermally decomposed in a thermogravimetric analyzer. Three heating rates were employed to heat the sample up to 650 °C. The kinetic analysis was performed by the Coats-Redfern method to describe the non-isothermal pyrolysis of the residua. A reaction model where the reaction order gradually increases from first to second order is proposed, resulting on an excellent agreement of the experimental with the calculated data. The results also indicate that the pyrolysis of a vacuum residue cannot be modeled by a single reaction mechanism