Process for the production of low-sulfur-content hydrocarbon mixtures

A process for producing a low-sulfur hydrocarbon mixture by desulfurizing a hydrocarbon feedstock, said feedstock being a reduced-crude obtained from a whole crude having a sulfur content of at least about 1 weight percent, which comprises:

• 1. separating said feedstock into a vacuum gas oil and a vacuum residuum fraction;
• 2. producing a sulfur-reduced vacuum residuum by contacting at least a portion of said vacuum residuum with a first hydrodesulfurization catalyst and hydrogen in a first hydrodesulfurization zone under vacuum residuum hydrodesulfurizing conditions comprising a temperature in the range 600.degree. to 850.degree. F., a pressure in the range 1000 to 2500 psig, a liquid hourly space velocity in the range below about 1 and the use of a hydrogen-containing gas having a hydrogen content of at least about 75 volume percent, said catalyst comprising a sulfided composite of a Group VIII metal, a Group VIA metal and a catalyst base comprising alumina, said catalyst having a pore volume in the range from 0.3 to 1 cc per gram, the pores of said catalyst having a diameter in the range 0 to about 3000 Angstroms and an average pore diameter in the range 80 to 150 Angstroms, the 80 to 150 Angstrom diameter pores of said catalyst contributing at least 70 volume percent of said pore and wherein an amount in the range from about 0.2 to 3 percent of said pore volume is contributed by macropores.
• 3. a 350.degree. F.-1050.degree. F. boiling range hydrocarbon fraction is separated from said sulfur-reduced vacuum residuum from step (2) and combined with at least a portion of said vacuum gas oil, thereby producing a VGO-VRDS composite;
• 4. producing said low-sulfur content hydrocarbon mixture by contacting said VGO-VRDS composite with a second hydrodesulfurization catalyst and hydrogen gas in a second hydrodesulfurization zone under a hydrogen partial pressure in the range 300 to 800 psig and a temperature in the range 550 to 850.degree. F., said catalyst comprising a sulfided composite of a Group VIII metal, a Group VIA metal and a catalyst base comprising alumina, said catalyst having a pore volume in the range from 0.3 to 1 cc per gram, the pores of said catalyst having a diameter in the range 0 to about 3000 Angstroms and an average pore diameter in the range 80 to 150 Angstroms, the pores of 80 to 150 Angstrom diameter contributing at least 70 percent of said pore volume.

A process for producing a low-sulfur hydrocarbon mixture by desulfurizing a hydrocarbon feedstock, said feedstock being a reduced-crude obtained from a whole crude oil having a sulfur content of at least about 1 weight percent, which comprises:

• 1. separating said feedstock into a vacuum gas oil fraction and a vacuum residuum fraction;
• 2. a sulfur-reduced residuum is produced by contacting at least a portion of said vacuum residuum with a first hydrodesulfurization catalyst under vacuum residuum hydrodesulfurization conditions in a first hydrodesulfurization zone, said catalyst comprising a sulfide composite of a Group VIII metal, a Group VIA metal and a catalyst comprising alumina, said catalyst having a pore volume in the range from 0.3 to 1 cc per gram, said pores having a diameter in the range of 0 to about 3000 Angstroms and an average pore diameter in the range 80 to 150 Angstroms, the 80 to 150 Angstrom diameter pores contributing at least 70 volume percent of said pore volume and wherein an amount in the range from about 0.2 to 3 volume percent of said pore volume is contributed by macropores;
• 3. passing at least a portion of said sulfur-reduced residuum from step (2) to a coker fractionator;
• 4. a bottoms fraction is withdrawn from said coker fractionator and passed to a coker;
• 5. a metallurgical-grade coke is withdrawn from said coker;
• 6. an overhead fraction is withdrawn from said coker fractionator;
• 7. producing a composite mixture by combining at least a portion of said vacuum gas oil fraction with at least a portion of said coker fractionator overhead fraction from step (6);
• and
• 8. producing said low-sulfur hydrocarbon mixture by contacting said composite mixture from step (7) with a second hydrodesulfurization catalyst and hydrogen gas in a second hydrodesulfurization zone under a hydrogen partial pressure in the range 300 to 800 psig and a temperature in the range 550 to 850.degree. F., said catalyst comprising a sulfided composite of a Group VIII metal, a Group VIA metal and a catalyst base comprising alumina, said catalyst having a pore volume in the range from 0.3 to 1 cc per gram, said pores having a diameter in the range 0 to about 3000 Angstroms and an average pore diameter in the range 80 to 150 Angstroms, said 80 to 150 Angstrom diameter pores contributing at least 70 volume percent of said pore volume;
• 9. withdrawing from said second hydrodesulfurization zone said low-sulfur hydrocarbon mixture, the 350.degree. F.+ portion thereof having a sulfur content below 0.2 weight percent, calculated as elemental sulfur.

A process for producing a low-sulfur hydrocarbon mixture by desulfurizing a hydrocarbon feedstock, said feedstock being a reduced-crude obtained from a whole crude having a sulfur content of at least about 1 weight percent, which comprises:

• 1. separating said feedstock into a vacuum gas oil (VGO) and a vacuum residuum fraction, said residuum fraction containing asphalt;
• 2. producing an asphalt-reduced fraction by separating in an asphalt removal unit at least a portion of said vacuum residuum fraction into an asphalt fraction and an asphalt-reduced residuum;
• 3. producing a hydrocarbon composite by combining said asphalt-reduced residuum from step (2);
• with at least a portion of said vacuum gas oil;
• 4. producing said low-sulfur hydrocarbon mixture by contacting said hydrocarbon composite from step (3) with a hydrodesulfurization catalyst and hydrogen gas in a hydrodesulfurization zone under a hydrogen partial pressure in the range 300 to 800 psig and at a temperature in the range 550 to 850.degree. F., said catalyst consisting essentially of a sulfided composite of alumina, molybdenum, phosphorus and a metal selected from the group consisting of cobalt and nickel, said catalyst having a pore volume in the range from 0.3 to 1 cc per gram, the pores in said catalyst having a diameter in the range 0 to 3000 A. and an average pore diameter in the range 80 to 150 A., the 80 to 150 A. diameter pores contributing at least 70 percent of said pore volume.