Solvent deasphalting of vacuum residue using carbon dioxide-toluene binary mixture

Abstract Solvent deasphalting of vacuum residue using carbon dioxide-toluene mixture was studied to assess the effect of the process parameters and mixture composition on the yield and composition of deasphalted oil (DAO) produced. An insignificant effect of the toluene content in the mixture on the DAO yield was found at a concentration above 30 wt.%, which was attributed to effective anti-solvent properties of carbon dioxide. At relatively low-pressure region, an increase in temperature and the transition of the mixture to the supercritical state led to a rapid decrease in the solvent density and the DAO yield. At the same time, at pressures providing a mixture density in the region above ∼0.6 g/mL, an increase in temperature above the mixture critical value was accompanied by increasing the DAO yield, even despite a noticeable decrease in the solvent density. However, conducting the extraction at temperatures near and beyond the mixture critical temperature reduces the separation selectivity at close the extraction yields due to increased solubility of metal-containing polar compounds. A proposed mixture in the single-phase liquid state can provide high DAO quality with metal and CCR removal efficiency of more than 90 and 80 wt.%, respectively.