Distributed Activation Energies Modeling of Athabasca Vacuum Residue Pyrolysis

Abstract

The kinetics of the thermal decomposition of Athabasca vacuum residue (AVR) has been studied by thermogravimetric analysis. Three heating rates of 0.5, 10 and 25 K/min were used to investigate the consistency of kinetic parameters. The Weibull and Gaussian distribution functions were found to be the best distribution functions for fitting the curve of differential of conversion with respect to time. The effect of pre-oxidation at low temperature with and without goethite α-FeO(OH) as a catalyst for oxidation was investigated in closed reactor. A three lump reaction network modeled the thermal cracking and the kinetics of AVR. Based on the obtained activation energies, it was found that goethite has a negligible effect as a catalyst during pre-oxidation. The difference among the calculated activation energies indicated that pre-oxidation resulted in the polymerization the vacuum residue molecules, The resulting pre-oxidized material was subsequently more resistant to thermal cracking than the unreacted feed.