Patent ID: 8435400

Claim:
A process for hydroprocessing a heavy oil feedstock, the process employing at least three contacting zones and at least two separation zones, wherein at least one separation zone comprises an interstage flash separator (ISF) interposed between two contacting zones, the process comprising: combining the heavy oil feedstock, a hydrogen containing gas, and a slurry catalyst in a first contacting zone under hydrocracking conditions to convert at least a portion of the heavy oil feedstock to upgraded products comprising lower boiling hydrocarbons, and form a mixture comprising the upgraded products comprising lower boiling products, the slurry catalyst, the hydrogen containing gas, and an unconverted portion of the heavy oil feedstock; sending the mixture comprising the upgraded products comprising lower boiling products, the slurry catalyst, the hydrogen containing gas, and the unconverted portion of the heavy oil feedstock to the ISF to separate, as an overhead stream, the upgraded products comprising lower boiling products and the hydrogen containing gas and, as a first non-volatile stream, the slurry catalyst and the unconverted portion of the heavy oil feedstock; wherein the first non-volatile stream is sent to a subsequent contacting zone other than the first contacting zone, which subsequent contacting zone is maintained under hydrocracking conditions with an additional hydrogen containing gas feed, to convert at least a portion of the unconverted portion of the heavy oil feedstock to lower boiling hydrocarbons and form additional upgraded products comprising lower boiling hydrocarbons; sending a mixture comprising the additional upgraded products, the slurry catalyst, the hydrogen containing gas, the additional hydrogen containing gas, and unconverted heavy oil feedstock from the subsequent contacting zone to at least a separation zone, whereby the additional upgraded products are removed with the additional hydrogen containing gas as an overhead stream, and the slurry catalyst and the unconverted heavy oil feedstock are removed as an additional non-volatile stream; recycling at least a portion of the additional non-volatile stream in an amount between 2 to 50 wt. % of the heavy oil feedstock to at least one of the contacting zones as a recycled catalyst stream, wherein the slurry catalyst comprises a recycled slurry catalyst and a fresh slurry catalyst, wherein at least a portion of the fresh slurry catalyst is fed into a contacting zone other than the first contacting zone, and wherein the number of contacting zones in operation is equal or greater than the number of separation zone(s) in operation.