Targeted pretreatment and selective ring opening in liquid-full reactors
A process for hydroprocessing hydrocarbons in a combined targeted pretreatment and selective ring-opening unit wherein the targeted pretreatment comprises at least two stages in a single liquid recycle loop. The process operates as a liquid-full process, wherein all of the hydrogen dissolves in the liquid phase. Heavy hydrocarbons and light cycle oils can be converted in the process to provide a liquid product having over 50% in the diesel boiling range, with properties to meet use in low sulfur diesel.
1. A process for hydroprocessing a hydrocarbon feed, which comprises
(a) contacting a hydrocarbon feed having a density of at least 0.910 g/ml at a temperature of 15.6° C., an end boiling point in the range of from about 375° C. to about 650° C., an API gravity in the range of about 24 to about 0, a sulfur content in the range from 1500 to 25000 wppm, and a nitrogen content of more than 500 wppm, with (i) a diluent and (ii) hydrogen, to produce a feed/diluent/hydrogen mixture, wherein the hydrogen is dissolved in the mixture to provide a liquid feed;
(b) contacting the feed/diluent/hydrogen mixture with a first catalyst in a first treatment zone, to produce a first product effluent;
(c) contacting the first product effluent with a second catalyst in a second treatment zone, to produce a second product effluent; and
(d) recycling a portion of the second product effluent as a recycle product stream for use in the diluent in step (a)(i) at a recycle ratio of from about 1 to about 8 without separating ammonia and hydrogen sulfide and remaining hydrogen from said portion of the second product effluent,
wherein hydrogen is recycled with the recycle product stream, wherein the first treatment zone comprises at least two stages, wherein the first catalyst is a hydrotreating catalyst and the second catalyst is a ring opening catalyst, the first and second treatment zones are liquid-full reaction zones, and the total amount of hydrogen fed to the process is greater than 100 normal liters of hydrogen per liter of feed, and wherein there is no separation of ammonia, hydrogen sulfide and remaining hydrogen from the first product effluent prior to feeding the first product effluent to the second treatment zone.
2. The process of claim 1 wherein the hydrocarbon feed is a heavy hydrocarbon.
3. The process of claim 1 wherein the hydrocarbon feed is a light cycle oil.
4. The process of claim 1 wherein the total amount of hydrogen fed to the process is 200-530 l/l (1125-3000 scf/bbl).
5. The process of claim 1 wherein the total amount of hydrogen fed to the process is 250-360 l/l (1300-2000 scf/bbl).
6. The process of claim 1 wherein both the first treatment zone and the second treatment zone have a temperature from about 300° C. to about 450° C., pressure from about 3.45 MPa (34.5 bar) to 17.3 MPa (173 bar), and a hydrocarbon feed rate to provide a liquid hourly space velocity (LHSV) of from about 0.1 to about 10 hr −1 .
7. The process of claim 6 wherein both the first treatment zone and the second treatment zone have a temperature from about 350° C. to about 400° C., pressure from about 6.9 MPa (69 bar) to 13.9 MPa (139 bar), and a hydrocarbon feed rate to provide a liquid hourly space velocity (LHSV) of from about 0.4 to about 4 hr −1 .
8. The process of claim 1 wherein the diluent comprises an organic liquid selected from the group consisting of light hydrocarbons, light distillates, naphtha, diesel and combinations of two or more thereof.
9. The process of claim 1 wherein the first treatment zone comprises at least two catalyst beds in one reactor, wherein the beds are physically separated by a catalyst-free zone.
10. The process of claim 1 wherein the first treatment zone comprises at least two reactors each reactor containing one catalyst bed and wherein the reactors are separated by a catalyst-free zone.
11. The process of claim 9 or 10 wherein fresh hydrogen is added between the catalyst beds to the catalyst-free zone.
12. The process of claim 9 wherein the reactor comprises both the first treatment zone and the second treatment zone.
13. The process of claim 12 wherein fresh hydrogen is added between the catalyst beds to the catalyst-free zone.
14. The process of claim 13 wherein the feed/diluent/hydrogen mixture and product effluents are fed from bed to bed in a downflow mode.
15. The process of claim 13 wherein the feed/diluent/hydrogen mixture and product effluents are fed from bed to bed in an upflow mode.
16. The process of claim 1 wherein the first catalyst comprises a metal and an oxide support, wherein the metal is selected from the group consisting of nickel and cobalt, and combinations thereof combined with molybdenum and/or tungsten, and the oxide support is selected from the group consisting of alumina, silica, titania, zirconia, kieselguhr, silica-alumina and combinations of two or more thereof.
17. The process of claim 16 wherein the first catalyst support is alumina.
18. The process of claim 1 wherein the second catalyst comprises a metal and an oxide support, wherein the metal is selected from the group consisting of nickel and cobalt, and combinations thereof combined with molybdenum and/or tungsten and the oxide support is a zeolite, amorphous silica, or a combination thereof.
19. The process of claim 1 wherein the first and second catalysts each comprise a metal which is a combination of metals selected from the group consisting of nickel-molybdenum (NiMo), cobalt-molybdenum (CoMo), nickel-tungsten (NiW) and cobalt-tungsten (CoW).
20. The process of claim 1 wherein the first and second catalysts are sulfided.
21. The process of claim 1 wherein liquid portion of the second product effluent comprises less than 50% by weight of naphtha product and at least 50% by weight of diesel product.
22. The process of claim 21 wherein the diesel product has a sulfur content less than 50 wppm and a nitrogen content less than 10 wppm.
23. The process of claim 1 wherein liquid portion of the second product effluent comprises less than 25% by weight of naphtha product and at least 75% by weight of diesel product.
24. The process of claim 21 wherein the diesel product has a cetane index of at least 12 points higher than the hydrocarbon feed.
25. The process of claim 21 wherein the diesel product has a density of about 0.860 g/ml or less at a temperature of 15.6° C., a sulfur content of less than 50 wppm, and a cetane index of at least 12 points higher than the hydrocarbon feed.
26. The process of claim 1 wherein the first product effluent comprises a nitrogen content of no more than 50 wppm.