Patent ID: 7790020

Claim:
A process for producing low sulfur diesel having a high cetane number, the process comprising: providing a diesel boiling range hydrocarbon stream with a sulfur content, a cetane number, and an aromatic content; converting the diesel boiling range hydrocarbon stream in at least a hydrotreating zone having at least a hydrodesulfurization catalyst at hydrotreating conditions effective to produce a hydrotreating zone effluent having a reduced sulfur content relative to the sulfur content of the diesel boiling range hydrocarbon stream; taking at least a portion of the hydrotreating zone effluent as a hydroprocessing feed; admixing hydrogen with the hydroprocessing feed in an amount and in a form available for substantially consistent consumption in the liquid-phase continuous hydroprocessing reaction zone; and reacting the hydroprocessing feed substantially undiluted with another hydrocarbon stream in the substantially liquid-phase continuous hydroprocessing zone over a catalyst and at conditions effective to saturate at least a portion of the aromatic content therein to provide a liquid-phase continuous hydroprocessing zone effluent having an increased cetane number relative to the diesel boiling range hydrocarbon stream.