Deasphaltization and demetalling of heavy crude oils and distillation residues with CO₂

Deasphaltization of heavy crude oils and distillation residues may reduce the metal content of these oils to such an extend that the upgrading of deasphaltized oil in a catalytic process becomes economically feasible. Experimental results of deasphaltization of Boscan crude from Venezuela, using subcritical and supercritical carbon dioxide as deasphaltizing agent, are presented. Deasphaltization and demetalling with CO 2 in the supercritical state is more effective. Under favorable conditions, the deasphaltized oil contains practically no asphaltenes and the metal content is reduced by 690 wt‐%. The influence of n ‐heptane or n ‐pentane addition to the crude, which lowers viscosity and promotes flocculation, is also discussed. Furthermore, a multistage deasphaltization process is more efficient than a single stage process.