Sub-Product

DAO is obtained by means of a De-Asphalter, a Unit in a Crude Oil Refinery or Bitumen Upgrader that separates Asphalt from Crude Oil or Bitumen. The De-Asphalter Unit is usually placed after the Vacuum Distillation Tower. It is usually a Solvent De-Asphalter Unit, SDA. The SDA separates the Asphalt from the Feedstock because Light Hydrocarbons will dissolve Aliphatic Compounds but not Asphaltenes. The Output from the De-Asphalter unit is De-Asphalted Oil and Asphalt. DAO from Propane De-Asphalting has the highest Quality but lowest Yield, whereas using Pentane may double or triple the Yield from a Heavy Feed, but at the expense of Contamination by Metals and Carbon Residues that shorten the life of downstream Cracking Catalysts.