DEMETALLIZATION BY DELAYED COKING AND GAS PHASE OXIDATIVE DESULFURIZATION OF DEMETALLIZED RESIDUAL OIL

Abstract

The invention is an integrated process for treating residual oil of a hydrocarbon feedstock. The oil is first subjected to delayed coking and then oxidative desulfurization. Additional, optional steps including hydrodesulfurization, and hydrocracking, may also be incorporated in to the integrated process.

Claims

1. An integrated process for removing metals and sulfur from a residual oil feedstock, comprising: (i) contacting said residual oil feedstock to a paraffinic solvent in a first vessel, under delayed coking conditions, to produce a gas fraction, a demetalized oil fraction, and coke; (ii) moving said demetalized oil fraction to a second vessel, said second vessel containing an oxidative desulphurization (ODS) catalyst; (iii) contacting said demetalized oil fraction and ODS catalyst with a gaseous oxidizing agent, to form SO.sub.2, gaseous, and liquid products in a gaseous ODS process; (iv) separating said gaseous and liquid products produced in (iii) from each other; (v) removing a portion of said gaseous products from total gaseous products, leaving a remainder; (vi) recycling said remainder to said second vessel, and; (vii) removing any liquid products.

2. The method of claim 1, further comprising gasifying said coke to produce hydrogen.

3. The method of claim 2, further comprising subjecting the liquid products of (iii) to hydrodesulfurization (HDS) with hydrogen and an HDS catalyst.

4. The method of claim 1, further comprising subjecting the demetalized oil fraction of (ii) to hydrocracking in the presence of hydrogen and hydrocracking catalysts before (iii).

5. An integrated process for removing metals and sulfur from a residual oil feedstock, comprising: (i) contacting said residual oil feedstock to a paraffinic solvent in a first vessel, under delayed coking conditions, to produce a first gas fraction, a demetalized oil fraction, and coke; (ii) subjecting said demetalized oil fraction to hydrodesulfurization (HDS) in a second vessel, in the presence of an HDS catalyst, to produce a first liquid fraction and a second gas fraction; (iii) contacting said first liquid fraction with an ODS catalyst, to form SO.sub.2 a third gaseous fraction and a second liquid fraction; (iv) separating gaseous and liquid fractions produced in (iii) from each other; (v) removing a portion of said gaseous fraction from the total gaseous fraction of (iv), leaving a remainder; (vi) recycling said remainder to said second vessel, and; (vii) removing liquid fractions.

6. The method of claim 5, further comprising gasifying said coke to produce hydrogen.

7. The method of claim 6, further comprising subjecting the demetalized oil fraction of (iii) to hydrodesulfurization (HDS) with hydrogen and a hydrocracking catalysts.

8. The method of claim 6, further comprising subjecting the first liquid fraction of (iii) to hydrocracking in presence of hydrogen and n hydrocracking catalysts.

9. The method of claim 5, wherein said paraffinic solvent is a C5-C8 alkane.

10. The method of claim 9, wherein said paraffinic solvent is pentane, hexane, or a mixture thereof.

11. The method of claim 1, wherein said ODS catalyst is in form of a fixed, ebullated, moving or fluidized bed.

12. The method of claim 1, comprising contacting said liquid/fraction, ODS catalyst and gaseous oxidizing agent at a temperature of from 300 C. to 600 C.

13. The method of claim 12, wherein said temperature is 400 C.-550 C.

14. The method of claim 1, comprising contacting said gaseous oxidizing agent to said liquid fraction at an O.sub.2/S ratio of from 20-30.

15. The method of claim 14, wherein said ratio is 25-30.

16. The method of claim 1, comprising contacting said gaseous oxidizing agent, ODS catalyst and liquid at a pressure of from 1 bar-20 bars.

17. The method of claim 16, wherein said pressure is 1-10 bars.

18. The method of claim 17, wherein said pressure is 1-5 bars.

19. The method of claim 1, comprising contacting said liquid fraction, ODS catalyst and gaseous oxidizing agent at a WHSV of 1-20 h.sup.1.

20. The method of claim 19, wherein said WHSV is 5-10 h.sup.1.

21. The method of claim 1, comprising contacting said demetalized oil fraction, ODS catalyst, and gaseous oxidizing agent at a GHSV of 1,000-20,000 h.sup.1.

22. The method of claim 21, wherein said GHSV is 5,000-15,000 h.sup.1.

23. The method of claim 22, wherein said GHSV is 5,000-10,000 h.sup.1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0040] FIG. 1 shows schematically, the broadest embodiment of the invention.

[0041] FIG. 2 shows an embodiment of the invention in which hydrodesulfurization (HDS), follows the ODS step.

[0042] FIG. 3 shows an embodiment of the invention in which ODS is followed by hydrocracking.

[0043] FIG. 4 shows an embodiment of the invention where an H-IDS step precedes the ODS step.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0044] Referring now to the figures, FIG. 1 shows the invention in its broadest embodiment. Residual fuel oil 1 is added to a first vessel 2, and treated under standard delayed coking conditions. The result is coke 3, which is separated for further processing, such as gasification. Also produced via the delayed coking are a liquid phase and a gas phase, which move to separation zone 4. Gases 5 are separated to a separate vessel 6, demetallized oil 7 precipitates from the delayed coking residual oil (the first liquid) is moved to a second vessel 8 for gas phase ODS. A source of Oxygen 9 is provided to vessel 8, which contains an ODS catalyst. This liquid is subject to ODS, producing a second liquid and gas, which are separated from each other in separation zone 10. Gases are separated to zone 11, while the second liquid can now be used in other processes, such as being added to fuels.

[0045] The gas moved to zone 11 is voluminous. A portion of it is removed (bled), while any residual oxygen is recycled to the ODS phase.

[0046] FIG. 2 shows optional additional steps, which can be carried out in the second liquid product of FIG. 1. To elaborate, the desulfurized oil moves to a third vessel 12, for HDS. A source of hydrogen 13 is provided. Again, a liquid and a gas are formed, which are separated in separation zone 14. Again, a portion of the gas is removed after separation to zone 15, and residual hydrogen can be recycled to the HDS process.

[0047] In FIG. 3, an embodiment is shown where, rather than subjecting the product of ODS to HDS, it is hydrocracked, in the presence of hydrogen and hydrocracking catalysts.

[0048] FIG. 3 shows hydrocracking vessel 16, and also illustrated as 17, is the distillate from the hydrocracked oil, previously subjected to ODS.

[0049] FIG. 4 shows an embodiment of the invention, where, intermediate to delayed coking, the coked oil is subjected to HDS, prior to ODS. It will be seen that all steps and apparatus are in fact the same as in FIGS. 1-3, but simply have had positions changed.

[0050] FIGS. 2 and 3 could logically, follow FIG. 4, as FIGS. 5 and 6, and these new figures would be unchanged.

Example

[0051] A demetalized oil sample was introduced into a first vessel which served as a coking unit. The coking took place at a temperature of 496 C., and atmospheric pressure. The demetalized oil had an API gravity of 14.10, sulfur content of 2.9 wt %, MCR of 7.32 wt %, IBP of 355 C., MBP of 614 C., 85 C. point of 690 C. and a sulfur content of 2.9 wt %.

[0052] Among the products of the coking step, was a liquid, which contained 2.37 wt % sulfur and coke, containing 6.6 wt % sulfur. The liquid was moved to a second vessel for ODS. The second vessel was a fluidized bed reactor, containing 1B+5MoO.sub.3/CuZnAl catalyst. The ODS reaction took place at a temperature of 500 C., a pressure of 1 bar, weight liquid hourly space velocity of 6 h.sup.1, and an oxygen:sulfur atom ratio of 26.

[0053] The liquid which resulted from the delayed coking contained 2.37 wt % sulfur. Following ODS, the sulfur content was 1.26 wt %.

[0054] The foregoing description and examples set forth the invention, which is an integrated process for demetallization and desulfurization of the residual oil fraction of a hydrocarbon feedstock. This is accomplished by integrating a delayed coking step, and an oxidative desulfurization step. Optionally, this integrated process may include one or more hydrodesulfurization and/or hydrocracking steps. These optional steps are carried out in the presence of hydrogen and an appropriate catalyst or catalysts, as known in the art.

[0055] In practice, a residual oil hydrocarbon feedstock is introduced or contacted to a first vessel, together with a paraffinic alkyl solvent, such as propane, or any pure paraffinic solvent, preferably one or more C5-C8 alkanes, most preferably pentane, hexane, or a mixture of these in the form of, e.g., light naphtha, as well as mixture of these under conditions which may include the addition of hydrogen, to form a demetalized liquid fraction, a gas fraction, and coke.

[0056] The gas and coke fractions will be addressed infra; however, the liquid fraction, now with reduced metal and sulfur content is removed to a second vessel, where it is subjected to gas phase oxidative desulfurization, in presence of an oxidative desulfurization catalyst. The catalyst can be present in the form of, e.g., a fixed, ebullated, moving or fluidized bed. The gaseous phase ODS takes place at a temperature of from 300 C. to 600 C., preferably from 400 C.-550 C., and with an oxidative gas, such as pure oxygen, where a ratio of O.sub.2 to sulfur (calculated in the liquid), is from 20-30, preferably 25-30.

[0057] Additional parameters of the reaction include a pressure of 1-20 bars, preferably 1-10 bars, and most preferably, 1-5 bars. A WHSV of 1-20 h.sup.1, preferably 5-10 h.sup.1, and a GHSV of from 1,000-20,000 h.sup.1, preferably 5-15,000 h.sup.1, and even more preferably, 5-10,000 h.sup.1 are used.

[0058] As noted, supra, during the delayed coking phase, coke is produced. The resulting coke can be removed and gasified, to produce hydrogen gas. The hydrogen gas can be returned to the first vessel or when an optional HDS or cracking step is used, be channeled to the vessels in which these reactions take place.

[0059] The gas produced via delayed coking is separated, and can be stored, separated into component fractions, or otherwise used in art known processes.

[0060] Prior to, or after the ODS step, the liquid may be hydrodesulfurized, using methods known in the art, using hydrogen and an H-IDS catalysts. Whether this HDS step is done before or after ODS, the resulting hydrocarbon product which results at the end of the process contains very low amounts to sulfur, and de minimis quantities of metals.

[0061] The product of ODS may also be hydrocracked, in the presence of hydrogen and hydrocracking catalysts, either before or after an optional HDS step, again resulting in a product with very low sulfur and metal content.

[0062] As noted, supra, a gaseous oxidizing agent, such as pure O.sub.2, or air containing O.sub.2, is added to the ODS vessel. The products of ODS are a liquid and a gas. The liquid, as discussed supra, can be used, e.g., as fuel oil. The gas is separated and oxygen can be recycled to the ODS vessel, if desired.

[0063] Various ODS catalysts useful in gaseous ODS are known. Preferred are catalysts which comprise oxides of copper, zinc, and aluminum, i.e.: [0064] 10-50 wt % CuO [0065] 5->20 wt % ZnO [0066] 20-70 wt % Al.sub.2O.sub.3 [0067] which also contain a highly dispersed spinel oxide phase. While the catalyst itself can be represented by the formula:

CuZnAlO

[0068] The aforementioned spinel phase is better represented by:

Cu.sub.xZn.sub.xAl.sub.2O.sub.4

[0069] where x is from 0 to 1, preferably 0.1 to 0.6, and most preferably from 0.2 to 0.5.

[0070] The catalyst can be granular, or in forms such as a cylinder, a sphere, a trilobe, or a quatrolobe, with the granules having diameters ranging from 1 mm to 4 mm. The catalysts have a specific surface area of from 10 m.sup.2/g to 100 m.sup.2/g, more preferably 50 m.sup.2/g to 100 m.sup.2/g, pores from 8 to 12 nm, and most preferably 8 nm to 10 nm, and a total pore volume of from 0.1 cm.sup.3/g to 0.5 cm.sup.3/g.

[0071] In a more preferred embodiment, the composition is: [0072] 20-45 wt % CuO [0073] 10->20 wt % ZnO [0074] 20-70 wt % Al.sub.2O.sub.3

[0075] and even more preferably: [0076] 30-45 wt % CuO [0077] 12->20 wt % ZnO [0078] 20-40 wt % Al.sub.2O.sub.3.

[0079] Especially preferred are catalysts of the type described supra, containing a mixed oxide promoter, such as one or more oxides of Mo, W, Si, B, or P. The example used such a catalyst, with a mixture of Mo and B oxides.

[0080] The catalysts can be on a zeolite support, such as an H form zeolite, e.g., HZSM-5, HY, HX, H-mordenite, H-, MF1, FAU, BEA, MOR, or FER. The H forms can be desilicated, and/or contain one or more transition metals, such as La or Y. When used, the H form zeolite is present at from 5-50 wt % of the catalyst composition, and a silicate module of from 2 to 90.

[0081] Other features of the invention will be clear to the skilled artisan and need not be reiterated here.

[0082] The terms and expression which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expression of excluding any equivalents of the features shown and described or portions thereof, it being recognized that various modifications are possible within the scope of the invention.