Use of a solvent in the oxidative desulfurization of bitumen via autoxidation; effects on viscosity and oxidation

Abstract

This work describes the effect that including a solvent in the reaction media of the autoxidation of Cold Lake bitumen has on the viscosity and also on the oxidation degree reached. The comparison of viscosity was performed both in the basis of equal residence time and equal oxygen conversion showing that the solvent does not have a moderating effect on the viscosity increase of bitumen during autoxidation. Nevertheless, it is shown that the presence of a solvent greatly increases the oxidation rate. All the efforts made to oxidize sulfur compounds in bitumen are worthless if there is not a viable route to remove the oxidized species and release the sulfur as SO2. The release of SO2 from oxidized bitumen by pyrolysis and the effect on the desulfurization level reached is explored. Differential Scanning Calorimetry (DSC) was employed in the thermal analysis of reactions involving model compounds for autoxidation and pyrolysis.