Residue Upgrading by Hydroprocessing of Deasphalted Oil

Heavy oil cracking in most Japanese refineries adopts the residue fluid catalytic cracking (RFCC) process. The sulfur content of low sulfur fuel oil (LSFO) must be reduced to below 0.5 wt% to comply with new Interna-tional Maritime Organization (IMO) regulations. To achieve this, the residue hydrodesulfurization (RDS) unit must be operated under more severe conditions. In this study, an RDS catalyst system to treat deasphalted oil (DAO) from the solvent deasphalting (SDA) unit was developed. This system allows co-production of both RFCC feedstocks and LSFO from the vacuum residue (VR) fraction simultaneously and flexible refinery opera-tion. VR has much amount of vanadium and nickel. The SDA process selectively reduces large molecules con-taining vanadium and nickel, both catalyst poisoning materials. Such metal compounds in DAO are easy to remove, but due to their reactivity, the catalysts deactivate faster than conventional atmospheric residue (AR). Therefore, we developed a new RDS catalyst system for DAO treatment. This new system can suppress metal deactivation in the RDS unit and reduces the amount of nitrogen in the products, which in turn leads to increased RFCC conversion.