Slurry processes offer an attractive option to deal with heavy feeds, because they combine the advantages of the C-rejection technologies in terms of flexibility with the high performances peculiar of the H-addition processes. The use of an active catalyst contributes to reduce the severity of the process and to improve the quality of the products. The process solution, here proposed, is based on the slurry hydrotreatment of the feedstock at a relatively low temperature in the presence of thousands ppm of a molybdenum-based dispersed catalyst, which is recycled via solvent deasphalting (overall technology performances: HDS>75%, HDM>99% and HDCCR>90%). Part of the feedstock is directly converted to distillates, while the Vacuum GasOil and the deasphalted oil may represent interesting feedstock for conventional catalytic cracking processes such as Fluid Catalytic Cracking or Hydrocracking.
The process configuration is characterized by the possibility of performing the upgrading and the conversion of the residue in two separate and optimized stages. The main advantages of this process configuration are the following: feedstock flexibility (even the heaviest, highest metals content feedstocks can be upgraded), optimal hydrogen utilization/consumption, product slate flexibility (maximum gasoline from FCC or maximum high quality diesel oil from Hydrocracking), nearly complete conversion (> 95%) of the feedstock.
Furthermore, the high temperature favours condensation reactions between aromatic Declining demand for residual fuel oil clusters which lead to the formation of will force refiners to modify their present mesophase, and consequently coke. process configuration and convert this surplus An active dispersed catalyst/additive of petroleum residues into maximum distillate must be able to restrain the above mentioned transportation fuels. undesirable reactions, favouring instead the Among the various options available hydrogenation reactions and interfering with for upgrading bottom materials, slurry the coalescence of the mesophase as well. processes have an excellent potential, The chemical nature, catalytic activity particularly on high-metals feedstocks. and cost of these catalysts are the key However, the main limitations to their ingredients for the optimization and commercialization are the high investment and development of efficient hydroconversion operating costs necessitated by the severe processes. operating conditions and/or the catalyst make- As regards the balance between up. catalytic and thermal effects, the latter play a The hydroconversion processes for major role in the Exxon Microcat Process or in the upgrading of heavy oils
