Lese, Henri K. (64 El Pavo Real Circle, San Rafael, CA, 94903, US)
Spars, Byron G. (251 Tamalpais Avenue, Mill Valley, CA, 94941, US)
Zakarian, John A. (83 Arlington Avenue, Kensington, CA, 94707, US)
Snyder, Thomas P. (1733 Allston Way, Berkeley, CA, 94703, US)
|1.||A process for preparing a dispersed Group VIB metal sulfide catalyst for hydrocarbon oil hydroprocessing comprises: (a) sulfiding an aqueous mixture of a Group VIB metal compound, with a gas containing hydrogen sulfide to a dosage greater than about 8 SCF of hydrogen sulfide per pound of Group VIB metal, to form a slurry; and (b) mixing said slurry with feed oil and a hydrogencontaining gas at elevated temperature and pressure. A process according to Claim 1 wherein said hydrogen sulfide dosage is about 814 SCF of hydrogen sulfide per pound of Group VIB metal. A process according to Claim 1 wherein said Group VIB metal is an oxide. A process according to Claim 1 wherein said Group VIB metal is molybdenum. A process according to Claim 1 wherein said Group VIB metal compound is molybdenum oxide. A process according to Claim 1 wherein said Group VIB metal compound is an ammoniated salt. A process according to Claim 1 wherein said Group VIB metal compound is an ammonium molybdate.|
|2.||8 A process according to Claim 1 wherein said Group VIB metal compound aqueous mixture is obtained by treating a Group VIB metal oxide with aqueous ammonia.|
|3.||9 A process according to Claim 1 wherein said Group VIB metal compound aqueous mixture is obtained by treating molybdenum oxide with aqueous ammonia.|
|4.||10 A process according to Claim 1 wherein said elevated temperature is at least about 350° F.|
|5.||11 A process according to Claim 1 wherein prior to mixing with feed oil, said slurry is in the incipient gel stage.|
|6.||12 A process according to Claim 1 wherein said sulfiding is performed with a gas containing a partial pressure of hydrogen and the dosage of hydrogen sulfide is in the range of about 12 to 14 SCF of hydrogen sulfide per pound of Group VIB metal.|
|7.||13 A process according to Claim 1 wherein said sulfiding is performed in the absence of hydrogen and the dosage of hydrogen sulfide is in the range of about 8 to 10 SCF of hydrogen sulfide per pound of Group VIB metal.|
|8.||14 A process for preparing a dispersed Group VIB metal sulfide catalyst for hydrocarbon oil hydroprocessing comprises: 1 (a) sulfiding ah aqueous mixture of a Group VIB metal 2 compound, with a gas containing hydrogen sulfide, 3 to a dosage of about 814 SCF of hydrogen sulfide 4 per pound of Group VIB metal, to form a slurry; 5 6 (b) adding a Group VIII metal compound to said slurry; 7 and 8 9 (c) mixing said slurry and Group VIII metal compound 0 with a feed oil and a hydrogencontaining gas at i x, elevated temperature and pressure. 2 3 15. A process according to Claim 14 wherein said slurry is . . at the incipient gel formation stage. 5 g 16. A process according to Claim 14 wherein said Group VIII 7 metal compound is added to said slurry at a slurry pH 8 less than about 8. 9 Q 17. A process according to Claim 14 wherein said Group VIII metal to Group VIB metal weight ratio is about 1:2 to 2 about 1:100. 3 « 18. A process according to Claim 14 wherein said Group VIB 2c metal is molybdenum. 6 27 19. A process according to Claim 14, 15, 16, 17 or 18 28 wherein said Group VIII metal is nickel. *& 29.|
|9.||A process according to Claim 14 wherein said Group VIII 31 metal compound is a sulfate, nitrate or carbonate. 32 33 21. A process according to Claim 14, 15, 16, 17 or 18 34 wherein said Group VIII metal is cobalt. 1 22. A process of hydroprocessing a heavy hydrocarbonaceous 2 feedstock comprises contacting said feedstock with the 3 catalyst of Claim 1 in the presence of hydrogen at 4 elevated temperature and pressure. 05 06 23. A process for the production of a high viscosity index 07 lubricating oil from a heavy oil comprises the steps 08 of: *& 09.|
|10.||10 (a) sulfiding an aqueous mixture of a Group VIB metal _.1 compound with a gas containing hydrogen sulfide to 2 a dosage of greater than 8 SCF of hydrogen sulfide _ per pound of Group VIB metal; *& 14.|
|11.||_ (b) contacting the product of step (a) with a heavy . oil feedstock and a hydrogencontaining gas at 17 elevated temperature and pressure, and at a 18 concentration of 0.01 wt.%, or greater, of Group VIB metal based on the weight of said 19 feedstock to form a product; 20 21 (c) separating from the product of step (b) a fraction 22 boiling above about 650°F; and 23 24 (d) dewaxing said fraction to produce said lubricating 25 oil. 26 27 24 A process according to Claim 23 wherein said heavy oil 28 feedstock is contacted with the product of step (a) at 29 a temperature of about 775°F, or greater, and at a 30 hydrogen partial pressure of about 7004500 psi. 31 32 33 34 25 The product in the lubricating oil range boiling range produced according to Claim 23 is hydrotreated prior to catalytic dewaxing.|
|12.||26 A process for the production of a high viscosity index lubricating oil from a heavy oil comprises the steps of: (a) sulfiding an aqueous mixture of a Group VIB metal compound with a gas containing hydrogen sulfide to a dosage of greater than 8 SCF of hydrogen sulfide per pound of Group VIB metal; (b) adding a Group VIII metal compound to the product of step (a); (c) contacting the product of step (b) with a heavy oil feedstock and a hydrogencontaining gas at elevated temperature and pressure and at a concentration of 0.01 wt.%, or greater, of Group VIB metal based on the weight of said feedstock, to form a product; (d) separating from the product of step (c) a fraction boiling above about 650°F; and (e) dewaxing said fraction to produce a lubricating oil.|
|13.||27 A process according to Claim 26 wherein the product of step (a) is in the incipient gel formation stage.|
|14.||1 28. A process for the hydroprocessing of heavy 2 hydrocarbonaceous oil containing metal contaminants 3 comprises introducing said oil, an active catalyst 4 slurry and a hydrogencontaining gas at elevated 5 temperature and pressure into a fixed or ebullating bed 6 of hydrodesulfurizationhydrodemetalation catalyst at 07 temperatures greater than about 700°F: 08 09 wherein said active catalyst slurry is prepared by 0 sulfiding an aqueous mixture of a Group VIB metal 11 compound with a gas containing hydrogen sulfide to a dosage greater than 8 SCF of hydrogen sulfide per pound 12 of Group VIB metal. *& 13.|
|15.||14 29 A process for the hydroprocessing of heavy 15 lβ hydrocarbonaceous oil containing metal contaminants 17 comprises introducing said oil, an active catalyst slurry, porous contact particles, and a 18 hydrogencontaining gas at elevated temperatures and 19 pressures into in a fixed or ebullating bed of 20 hydrodesulfurizationhydrodemetalation catalyst at 21 temperatures greater than about 700°F: 22 23 wherein said active catalyst slurry is prepared by 24 sulfiding an aqueous mixture of a Group VIB metal 25 compound with a gas containing hydrogen sulfide to a 26 dosage greater than 8 SCF of hydrogen sulfide per pound 27 of Group VIB metal. 28 29 30 A process for the hydroprocessing of heavy 30 hydrocarbonaceous oil containing metal contaminants 31 comprises: 32 33 34 01 (a) contacting said oil in a first stage with an 02 active catalyst slurry and hydrogen at a 03 temperature and for a time sufficient to achieve 04 measurable thermal cracking in the product stream; 05 and 06 07 (b) in a second stage, contacting said product stream 08 with hydrogen in a fixed or ebullating bed of 09 hydrodesulfurizationhydrodemetalation catalyst at 10 temperatures greater than about 700°F: *& 11.|
|16.||_._ wherein said active catalyst slurry is prepared by 13 sulfiding an aqueous mixture of a Group VIB metal _.. compound with a gas containing hydrogen sulfide to ις a dosage greater than about 8 SCF of hydrogen _. _ sulfide per pound of Group VIB metal. *& 17.|
|17.||A process according to Claim 28, 29 or 30 wherein the 18 oil flow is upward through said fixed bed. 19 20 32 A process according to Claim 28, 29 or 30 wherein the 21 1000βF+ fraction conversion of said heavy oil is less 22 than 50%, the percent demetalation of nickel or 23 vanadium is greater than 30%, and the slurry catalyst 24 concentration is about 10010,000 ppm in said heavy 25 oil. 26 27 33 A process according to Claim 28, 29 or 30 wherein the 28 1000"F+ fraction conversion of said heavy oil is 29 greater than 50% and the coke yield is less than about 30 2.5% at a slurry catalyst concentration of about 31 10010,000 ppm in said heavy oil. 32 33 34.|
|18.||A process according to Claim 31 or 32 wherein the slurry catalyst concentration is less than about 500 ppm.|
|19.||A process according to Claim 31 or 32 wherein the slurry catalyst concentration is less than about ppm.|
|20.||A process according to Claim 28, 29 or 30 wherein to said slurry is added a Group VIII metal compound.|
12 continuation-in-part of U. S. Serial No. 527,414 filed
13 August 29, 1983 (now USP 4,557,821). This application is
14 also a continuation-in-part of U. S. Serial No. 252,839 ις filed September 30, 1988, which is a continuation-in-part of
16 U. S. Serial No. 941,456 filed December 15, 1986 (now
17 USP 4,857,496), which is a continuation-in-part of lβ U. S. Serial No. 767,767 filed August 21, 1985 (abandoned)
19 which is a continuation-in-part of U. S. Serial No. 527,414 20 filed August 29, 1983 (now USP 4,557,821). This application 21 is also a continuation-in-part of U. S. Serial No. 275,235
__ filed November 22, 1988, which is a continuation-in-part of
23 U. S. Serial No. 767,822 filed August 21, 1985 (abandoned) 24 which is a continuation-in-part of U. S. Serial No. 527,414 filed August 29, 1983 (now USP 4,557,821). Related 25 applications include U. S. Serial No. 767,760 filed 26 August 21, 1985 (now USP 4,824,821) also a continuation- 27 in-part of U. S. Serial No. 527,414 filed August 29, 1983; 28 U. S. Serial No. 767,768 filed August 21, 1985 (now 29 USP 4,710,486), also a continuation-in-part of U. S. Serial 30 No. 527,414 filed August 29, 1983; and U. S. Serial 31 No. 767,821 filed August 21, 1985 (now USP 4,762,812), also 32 a continuation-in-part of U..S. Serial No. 527,414 filed 33 34 August 29, 1983
01 BACKGROUND OF THE INVENTION 02 03 This invention relates to the catalytic hydroprocessing of 04 heavy hydrocarbon oils including crude oils, heavy crude 05 oils and residual oils as well as refractory heavy 06 distillates, including FCC decanted oils and lubricating 07 oils. It also relates to the hydroprocessing of shale oils, 08 oils from tar sands, and liquids derived from coals. The 09 invention relates to a catalyst for the hydroprocessing of 10 such hydrocarbonaceous feedstocks, the use of such 11 catalysts, and the preparation of such catalysts.
12 13 In U. S. Serial No. 527,414 filed August 29,1983 (now 14 USP 4,557,821), a parent application of the present application, a catalytic means of hydroprocessing heavy oils
_._ was revealed which employs a circulating slurry catalyst
17 The catalyst comprised a dispersed form of molybdenum ,_ disulfide prepared by reacting aqueous ammonia and
IB molybdenum oxide to form an aqueous ammonium molybdate which
19 was reacted with hydrogen sulfide to form a precursor 20 slurry. The precursor slurry was mixed with feed oil, 21 hydrogen and hydrogen sulfide and heated under certain 22 conditions. A variety of dosages of hydrogen sulfide 23 expressed as SCF of hydrogen sulfide per pound of molybdenum 24 were taught to be useful in forming the precursor slurry 25 (Column 3). From 2-8 SCF/LB were preferred (Column 4). It 26 was found to be necessary to mix the slurry with oil in the 27 presence of both hydrogen and hydrogen sulfide in order to 28 obtain a catalytically active slurry catalyst 29 (Columns 11-12). The oil-slurry mixture was then sulfided 30 with hydrogen and hydrogen sulfide at at least two 31 temperatures (Column 24) under certain conditions. The feed 32 and catalyst, with water added were charged to the 33 hydroprocessing reactor. Water introduction was deemed 34
beneficial (Columns 26-27) for certain purposes, as was nickel addition to the slurry catalyst (Columns 42-44).
4 In U. S. Serial No. 941,456 filed December 15, 1986 5 (USP 4,857,496), a parent application of the present 6 application, is described a sulfiding process in which there 7 are two or three heating steps providing time-temperature 8 sequences to complete the preparation of the final catalyst 9 prior to flowing the feed to the higher temperature 0 hydroprocessing reactor zone. Each sulfiding step was .. operated at a temperature higher than its predecessor. - Ammonia was removed from an intermediate stage of catalyst preparation before the addition of feed oil and further sulfiding. 5 6 U. S. Serial No. 767,760 filed August 21, 1985 _ (USP 4,824,821) also a continuation-in-part of 8 U. S. Serial No. 527,414 filed August 29, 1983 describes the promotion of a Group VIB slurry catalyst by the addition of 9 a Group VIII metal such as nickel or cobalt, to the aqueous 0 ammonia compound after sulfiding is underway. 1 2
U. S. Serial No. 767,768 filed August 21, 1985 3 (USP 4,710,486) also a continuation-in-part of U. S. Serial 4 No. 527,414 filed August 29, 1983 describes the specific 5 regulation of the amount of sulfiding occurring in 6 intermediate temperature sulfiding steps by stoichiometric 7 replacement of oxygen associated with the Group VIB metal 8 with sulfur up to fifty to ninety-five percent replacement. 9 At least three stages of sulfiding were preferred with 0 additional replacement of oxygen by sulfur in the high 1 temperature step. 2 3 4
01 U. S. Serial No. 767,821 filed August 21, 1985 02 (USP 4,762,812) also a continuation-in-part of U. S. Serial 03 No. 527,414 filed August 29, 1983 described a process for 04 the recovery of spent molybdenum catalysts. 05 06 A parent application of the present application U. S. Serial 07 No. 275,235 filed November 22, 1988 described a Group VIB 08 metal sulfide slurry catalyst for hydroprocessing heavy oils 09 or residual oil which has a pore volume in the 10 10-300 angstrom radius pore size range of at least 0.1 cc/g.
_ In USP 4,376,037 and USP 4,389,301 a heavy oil is
1 _ hydrogenated in one or two stages by contacting the oil with
1 . hydrogen in the presence of added dispersed hydrogenation
15 catalysts suspended in the oil, as well as in the additional
16 presence of porous solid contact particles, in the x. - two-stage version, the normally liquid product of the first
18 stage is hydrogenated in a catalytic hydrogenation reactor. 19 The dispersed catalyst can be added as an oil/water emulsion 20 prepared by dispersing a water-soluble salt of one or more 21 transition elements in oil. The porous contact particles 22 are preferably inexpensive materials such as alumina, porous
__ silica gel, and naturally occurring or treated clays.
_. Examples of suitable transition metal compounds include _ (NH.) 2 MoO., ammonium heptamolybdate and oxides and sulfides
26 of iron, cobalt and nickel. The second reaction zone preferably contains a packed or fixed bed of catalysts, and 27 the entire feed to the second reaction zone preferably 28 passes upwardly through the second zone. 29 30
In USP 4,564,439 a heavy oil is converted to transportation' 31 fuel in a two-stage, close-coupled process, wherein the 32 first stage is a hydrothermal treatment zone for the 33 feedstock mixed with dispersed demetalizing contact 34
01 particles having coke-suppressing activity, and hydrogen; 02 and the second stage closely coupled to the first, is a 03 hydrocatalytic processing reactor. 04 05 The specifications of all of the foregoing U. S. Patent 06 applications are incorporated herein by reference as if 07 fully set forth in ipsis verbis. 08 09 FIELD OF THE INVENTION
.. Increasingly, petroleum refiners find a need to make use of
- 2 heavier or poorer quality crude feedstocks in their
- 3 processing. As that need increases the need also grows to
- 4 process the fractions of those poorer feedstocks boiling at
15 elevated temperatures, particularly those temperatures above
16 1000°F, and containing increasingly high levels of
..-. contaminants, such as undesirable metals, sulfur, and
18 coke-forming precursors. These contaminants significantly
-o interfere with the hydroprocessing of these heavier
20 fractions by ordinary hydroprocessing means. The most
21 common metal contaminants found in these hydrocarbon
22 fractions include nickel, vanadium, and iron. The various 2 _ metals deposit themselves on hydrocracking catalysts,
24 tending to poison or de-activate those catalysts.
2 _ Additionally, metals and asphalteneε, and coke-precursors
2fi can cause interstitial plugging of catalyst beds, reduce
2 _ catalyst life, and run length. Moreover, asphaltenes also
28 tend to reduce the susceptibility of hydrocarbons to 29 desulfurization processes. Such de-activated or plugged 30 catalyst beds are subject to premature replacement. 31 32 33 34
As a practical matter the run length in a fixed bed resid desulfurization process is limited by coke and/or metals loadings of the ca " talyst. Improved fixed bed performance, catalyst life and improved 1000°F+ conversions can be obtained by reducing the levels of metals and coke precursors which plug the pores and/or penetrate the catalyst pore volume containing active catalytic sites.
It would be advantageous to cure these problems with the least upset to conventional processing techniques and at the lowest cost. If, for example, dispersed, consumable catalysts are used, the catalyst should be effective at the lowest possible concentration to reduce the cost of catalytic treatment.
For the processing of heavy oils characterized by low hydrogen to carbon ratios (i.e. less than about 1/8 by weight) and high carbon residues, asphaltenes, nitrogen, sulfur and metal contaminant contents, it would be advantageous if the parameters for the preparation of a high activity slurry catalyst were known.
It would also be advantageous if the performance of existing fixed bed reactors could be increased by the use of slurry catalysts.
A lubricating oil base stock boils above about 500 β F and below about 1300 β F, and will generally have a kinematic viscosity greater than about 2cS (measured at 100 β C). A Viscosity Index of about 90 or greater is preferred (ASTM D 2270-86). The lubricating oil base stock may be recovered as a distillate or distillate fraction from an upgrading zone, involving processes such as hydrocracking or solvent extraction.
01 Generally, lubricating oil base stocks prepared from 02 hydrocarbon feedstocks boiling above 1000°F require 03 pretreatment prior to the upgrading zone. One such 04 pretreatment method is solvent deasphalting, which removes 05 heavy hydrocarbonaceous components which otherwise form 06 precipitates during lube oil processing. The use of these 07 pretreatment methods adds additional processing steps over 08 the process of this invention, and leads to low yields of 09 lubricating oil stocks.
1 _. Distillates suitable for use as lubricating oil base stocks
_ may be further treated to meet specific quality
13 specifications. Wax may be removed to lower the pour point, 14 Dewaxing may be carried out by conventional means known in ις the art such as, for example, by solvent dewaxing or by
16 catalytic dewaxing. Distillates recovered from the 17 upgrading zone may also be further treated with a catalyst in the presence of hydrogen to remove hydrocarbonaceous 18 components which are subject to oxidation and formation of 19 color bodies during storage. 20 21
It would also be advantageous if a slurry catalyst process 22 produced a lubricating oil base stock with high viscosity 23 index from heavy oils. 24 25
SUMMARY OF THE INVENTION 26 27
The present invention provides a high activity catalyst 28 which is prepared by dispersing a slurry catalyst in a 29 hydrocarbonaceous oil for hydroprocessing. The present 30 process has the advantage over conventional processes of 31 achieving higher conversion of nitrogen, sulfur, metals and 32 bottoms than fixed bed resid desulfurization, thermal or 33 existing slurry processes. 34
01 The process comprises: sulfiding an aqueous mixture of a
02 Group VIB metal compound with a gas containing hydrogen
03 sulfide to a dosage greater than about 8, preferably from
04 greater than about 8 up to 14 SCF of hydrogen sulfide per
05 pound of Group VIB metal to form a slurry; and mixing the
06 slurry with feed oil and a hydrogen-containing gas at
07 elevated temperature and pressure. Twelve SCF hydrogen .
08 sulfide corresponds to about 1 mole of molybdenum per
09 3 moles of sulfur.
.... The invention also comprises the preparation of a dispersed
Group VIB metal sulfide catalyst by sulfiding an aqueous mixture of a Group VIB metal compound with a gas containing
_.. hydrogen and hydrogen sulfide, to a dosage from greater than
_._ about 8 to about 14 SCF of hydrogen sulfide per pound of
16 Group VIB metal to form a slurry; adding a Group VIII metal compound to the slurry; and mixing the slurry and Group VIII 17 18 metal compound with a feed oil and a hydrogen-containing gas at elevated temperature and pressure. The inclusion of 19
Group VIII metal compounds improves the denitrogenation 20 capability of the slurry catalyst. 21 22
A high viscosity index lubricating oil is produced from 23 heavy oils by using our high activity slurry catalyst 24 process. The lubricating oil which is produced is of 25 surprisingly high viscosity index and good viscosity. In 26 our process, the highly active Group VIB metal sulfide 27 catalyst slurry is contacted with feed oil and a hydrogen- 28 containing gas at elevated temperature and pressure; and 29 separating from the product an oil fraction boiling above 30 about 650 β F which is subsequently dewaxed. The process also 31 comprises adding a Group VIII metal compound to the slurry; 32 contacting the slurry catalyst containing the Group VIB and 33 34 the Group VIII metal with a feed oil and a hydrogen-
01 containing gas at elevated temperature and pressure to 02 effect hydroprocessing of said feed oil; and separating a 03 product lubricating oil base stock boiling above about 04 650°F, which is preferably subsequently dewaxed. 05 06 The lubricating oil fraction is of high viscosity index and 07 good viscosity characteristics for lubricating oil base 08 stock.
10 Another process using the active catalyst slurry comprises
_._. introducing the heavy oil, an active catalyst slurry and a
_._ hydrogen-containing gas at elevated temperature and pressure
-_ into a fixed or ebulating bed of particulate hydrodesulfurization- hydrodemetalation catalyst at a temperature greater than about 700°F, preferably in upflow 15
. relationship to said bed. Preferably a Group VIII metal
- compound is added to the slurry before mixing with the heavy feed oil. Separate porous contact particles can be added to
18 the heavy oil feedstock. 19 20
In a two-stage process embodiment of the present invention, 21 the heavy oil is contacted in a first-stage with the active 22 catalyst slurry and hydrogen at a temperature and for a time 23 sufficient to achieve measurable thermal cracking in the 24 product stream. Then the effluent of the first-stage is 25 contacted with a fixed or ebullated bed of 26 desulfurization-demetalation catalyst and hydrogen gas in a 27 second-stage. The second-stage catalyst bed may be graded 28 by catalyst activity and/or temperature profile to promote 29 uniform metal deposition, and preferably the effluent stream 30 flows upwardly through the second-stage catalyst bed. In 31 ebullating beds, the catalyst is graded by staged reactors. 32 In our process the metals are deposited on the slurry 33 catalyst and this catalyst provides the advantage of 34
01 demetalation at lower levels of conversion of the 1000°F+
02 fraction of the heavy oil.
04 Our process provides the advantage that when the 1000°F+
05 conversion of the heavy feed oil is less than 70%, the coke
06 yield is less than about 1.0%. Even at conversions as high
07 as 90%, and at low slurry catalyst concentrations
08 (100-1000 ppm) , the coke yield is less than 2.5%.
10 BRIEF DESCRIPTION OF THE DRAWINGS
- j Figure 1 shows the denitrogenation activity of various
_._ catalysts pretreated at essentially the same ammonia to Λ molybdenum ratio but sulfided to various extents. Figures
_._ 2-3 show the denitrogenation rate constant, and API gravity lβ increase as a function of the extent of sulfiding,
17 respectively. Figure 4 indicates the molybdenum sulfided
, β catalyst precursors which yield active catalysts are aqueous gels. Figure 5 shows the benefit of promoting the active
20 catalysts of this invention with a Group VIII metal.
21 Figure 6 graphs the amount of coke produced by the present
22 invention and the amount of coke produced by a competitive _. process, as coke yield (weight percent), versus the amount 24 of the 1000°F+ fraction of residua converted to lighter products, as volume percent.
Figure 7 graphs the percent of vanadium metal removed from 27 residua by the present invention and a competitive process, 28 versus the 1000 β F+ fraction conversion of the residua. 29 30 31 32 33 34
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 3 4 The activity of the Group VIB metal slurry catalyst is a function of the preparation conditions. The preferred 5 6 Group VIB metal is molybdenum, but tungsten compounds are 7 also catalytically useful. Molybdenum is used herein for 8 purposes of exemplification and does not exclude other 9 Group VIB compounds. The high activity slurry catalyst used 0 in the present invention is described in U.S. Serial 1 No. 548,157, filed July 5, 1990, the disclosure of which has been incorporated herein by reference. 2 3 . In an improved process for the preparation of molybdenum 5 sulfide slurry catalyst, sulfiding of the aqueous solution 6 formed by pretreatment of molybdenum oxide with aqueous _ ammonia is carried out with a dosage of at least 8 SCF of fl hydrogen sulfide per pound of molybdenum. When this dosage of hydrogen sulfide is used, it is not necessary to have 9 hydrogen sulfide present in the recycled gas stream during 0 1 hydroprocessing. Furthermore, the activation of the catalyst appears independent of the ratio of ammonia to _ molybdenum used to form the aqueous mixture. 4
HIGH ACTIVITY CATALYST 5 6
We have found that the activity of the final Group VIB metal 7 catalyst is a special function of the activation conditions 8 used to transform the starting Group VIB compound to the 9 final, active catalyst. In the following we will by way of 0 exemplification and discussion refer to the preferred 1 Group VIB metal, molybdenum and its compounds as typical of 2 our slurry catalyst. However, the reference to molybdenum 3 is by way of preference and exemplification only, and is not 4
01 intended to exclude other Group VIB metals and compounds 02 thereof. 03 04 As an improvement of other methods of preparing the catalyst 05 of the present invention we have found that activation of 06 the catalyst occurs by sulfiding the aqueous solution formed 07 by pretreatment with aqueous ammonia to at least 8 SCF of 08 hydrogen sulfide per pound of molybdenum. With this degree
Q Q of sulfiding it is no longer necessary to have hydrogen
J Q sulfide present in the recycled gas stream during
.- hydroprocessing. Furthermore, the activation of the
. - catalyst is achieved relatively independent of the
- 3 ammonia-to-molybdenum ratio used to form the aqueous
« 4 mixture.
1 6 Sulfiding;
17 18 Catalyst activity is achieved when the extent of sulfiding 19 is from greater than about 8 up to about 14 SCF of hydrogen 20 sulfide per pound of molybdenum. This sulfiding dosage
21 produces a catalyst precursor characterized by a sulfur-
22 to-molybdenum mole ratio of about 3. The effect of
2g sulfiding on catalyst activation is demonstrated in the
24 first set of examples. In these examples, two types of
2c catalyst were prepared by first reacting molybdenum oxide
26 with aqueous ammonia at identical conditions and with the 27 same amount of ammonia. The aqueous mixture was then 28 sulfided in the absence of added oil. The catalysts differ 29 in the extent of sulfiding provided. The first type was 30 sulfided to a dosage of 2.7 SCF of hydrogen sulfide per
31 pound of molybdenum (SC-21). The second type of catalyst
32 was sulfided beyond 12 SCF of hydrogen sulfide per pound of
01 molybdenum (SC-25-2). The conditions used to pretreat with Q 2 ammonia and sulfide these catalysts are summarized below.
04 CATALYST PREPARATION: 05
Catalyst, SC: -21 -25-2 06 07 Pretreatment
NH,/Mo, lb/lb. 0.23 0.23
09 H 2 S/Mo,SCF/lb. 2.7 14.0 Temperature, °F 150 150
10 Pressure, psig. 30 400 • Sulfiding Gas:
12 H 2 S 8-10 8-10
13 Hydrogen 88-90 88-90
«c Tables IA-IB compare the results of two runs performed on
16 the same feedstock and at identical conditions with both the
27 undersulfided catalyst SC-21 and the catalyst, SC-25-2.
« o Catalyst activation is evident from the hydrogen
.g consumption, denitrogenation, desulfurization, demetalation
2 and 975 β F+ conversion results. Hydrogen consumption was
2 < increased from 584 to 1417 SCF per barrel, desulfurization
22 from 38 to 89 weight percent, denitrogenation from 21 to
23 84 weight percent, demetalation from 66 to 99 weight percent
24 and 975°F+ conversion from 77 to 92 volume percent.
25 26 27 28 29 30 31 32 33 34
TABLE IA OPERATING CONDITIONS
Feedstock < Hvy. Arabian > Catalyst SC-21 SC-25-2
Cat. to oil ratio 0.0213 0.0193
LHSV 0.59 0.56
Temperatures, F. Pretreater: 682. Reactor: 811. Pressures: Rx. Inlet, psig: 2748. H 2 partial pressures, psi 1498. H 2 S partial pressure, psi 365. Recycle gas: Gas rate, SCF/Bbl. 6650 5419.
TABLE IB CONVERSIONS
Feedstock <- Hvy. Arabian
Hydrogen Consumption, SCFB: 584. 1417. Conversion:
Vacuum Resid, % as 53.7 71.4
975°F+ vol %
Total 76.6 92.1 3 Desulfurization, wt. % 38. 89. 4 5 Denitrogenation, wt. % 21. 84. 6 Demetalation, wt. % 66. 99. 7
Nickel Removal, wt. % 61. 99. 8 9 Vanadium Removal, wt. % 67. 99. 0 1 Catalysts sulfided at higher sulfiding dosages than about 2 12-14 SCF of hydrogen sulfide per pound of molybdenum yield 3 neither higher nor lower catalyst activities when tested in 4 batch operations. Figure 1 shows the denitrogenation 5 activities various catalysts pretreated at essentially the 6 same ammonia to molybdenum ratio but presulfided with 7 various dosages of hydrogen sulfide. These pretreated and 8 sulfided catalysts were screened in a batch reactor with no g added hydrogen sulfide and with a feed that contained little Q sulfur. No further sulfiding was provided to the catalyst 1 aside from that performed in the presulfiding step in the 2 absence of oil. The results shown in Figure 1 illustrate 3 4
i the criticality of sulfiding this catalyst to greater than 2 8 SCF H-S per pound of molybdenum. 3 4 Ammonia Pretreatment: 5 6 The catalysts were pretreated over a wide range of ammonia 7 to molybdenum ratios, from materials prepared without 3 ammonia (0 ammonia to molybdenum ratio) to catalysts 9 pretreated to 0.35 pound of ammonia per pound of molybdenum. 0 The results indicate that catalyst activity is independent i of the ammonia to molybdenum ratio used to form the slurry 2 catalyst. Although a slight optimum when the ammonia to 3 molybdenum ratio was about 0.16 was observed, catalysts were produced even when aqueous slurries of molybdenum oxide were 5 appropriately sulfided without ammonia pretreatment. 6 However, pretreatment with ammonia is preferred because 7 better control of the particle size is achieved when the ø molybdenum oxide is dissolved in aqueous ammonia. 9 0 Hydrogen Sulfide Requirements During Hydroprocessing: 1 2 In prior work it was required to include the recycling of a 3 hydrogen-hydrogen sulfide stream separated from the 4 hydroprocessing zone wherein the hydrogen sulfide partial 5 pressure was at least 20 psi and the circulation of hydrogen sulfide was greater than 5 SCF per pound of molybdenum. 7 However, in the present invention, by increasing the 8 sulfiding dosage, in the absence of oil, to values of from 9 about greater than 8 to about 14 SCF of hydrogen sulfide per 0 pound of molybdenum, not only are active slurry catalysts 2 produced, but the need of having hydrogen sulfide present in 2 the recycled gas stream is eliminated. 3 4
02 Table II shows and compares various runs performed with both
02 undersulfided catalyst and the catalysts of this invention. 03 As can be observed, stable and high activity catalysts have 04 been obtained over a wide range of hydrogen sulfide partial 05 pressures and circulation rates at the reactor inlet. 06 Active catalysts, have been obtained at hydrogen sulfide 07 partial pressures from 271 psi to 3.5 and circulation rates 08 from 78 to as low as 5 SCF of hydrogen sulfide per pound of øg molybdenum.
22 Effect of Hydrogen Partial Pressure During Sulfiding:
13 In the examples given above all the catalysts were sulfided
14 with hydrogen sulfide contained in a hydrogen gas. I have 2 5 now demonstrated that active molybdenum sulfide catalysts 2g can be produced when the sulfiding step is performed in the 27 absence of hydrogen. To study this effect a series of
18 catalysts were prepared at various sulfiding dosages with a ιg gas containing no hydrogen. The catalysts were prepared
20 using conventional sulfiding techniques described in the
22 background section, except that the sulfiding gas stream
22 contained no hydrogen. The sulfiding gas consisted of 20%
23 by mole of hydrogen sulfide and 80% nitrogen. The resulting
24 catalysts were tested in a batch microactivity unit for 2ς their denitrogenation, hydrogenation, and desulfurization j .. activities. The catalysts were tested at typical catalyst 27 conditions with the gas charge consisting of pure hydrogen.
28 The results from this study were compared to those obtained 29 with catalysts sulfided under hydrogen partial pressure.
_- Figures 2-3 show the denitrogenation rate constant, and API
_ 2 gravity increase as a function of the extent of sulfiding. 33 Also contained in these figures are similar results obtained _ 4 with catalysts sulfided with a hydrogen sulfide and hydrogen
01 gas mixture having the same hydrogen sulfide composition as 02 that used in this study. From the denitrogenation results, 03 it is evident that active catalysts were obtained regardless 04 of the hydrogen partial pressure. 05 06 Although in both cases active catalysts were produced, 07 activation of the slurry catalyst occurred at a lower 08 sulfiding dosage, i.e. at 8-10 SCF hydrogen sulfide per 09 pound of molybdenum, when the catalysts were produced under 10 no hydrogen partial pressure. This value was slightly lower _.- than that sulfiding dosage required to activate the catalyst - 2 when it is activated under hydrogen partial pressure, ._ i.e. at 12-14 SCF of hydrogen sulfide per pound of 14 molybdenum. Higher API gravities and amounts of hydrogen ις used to upgrade the liquid product were obtained with lβ catalysts sulfided under hydrogen partial pressure.
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
01 SLURRY CATALYTIC PROCESSING OF RESIDS WITH HIGH ACTIVITY SLURRY SYSTEMS
Run Hour 173 150 173 341 150
03 Feedstock Heavy Arabian 650 F+ > <- Hondo 650°F+ ->
04 Heavy Feed: 100. 100. 100. 100. 100. 100. 91.25
Surfactant: 0.00 0.00 0.00 0.00 0.00 0.00 8.75
05 Catalys SC-21-1 SC-25-2 SC-27-3 SC-27-3 SC-27-3 SC-28-3 SC-28-3
06 SC-28-3 Operating Conditions
07 Cat. to Oil Ratio
«H -a- σ -~ u-ι n
N Λ VO CO N σ> f-
σ, o H is « * * m β I s co <~ m ~ e O iH r-l S CM r-j
01 Effect of Sulfiding On Continuous Operations: 02 03 We have demonstrated that activation of the slurry catalyst 04 occurs by sulfiding aqueous solutions or mixtures of ammonia 05 molybdate and molybdenum oxides. Activity increases as the 06 extent of sulfiding is increased. Maximum activity is 07 obtained when the extent of sulfiding is about 12 SCF of 08 hydrogen sulfide per pound of molybdenum. Catalyst 09 precursors sulfided at higher sulfiding dosages than about 10 14 SCF of hydrogen sulfide per pound of molybdenum produce xs xs neither higher nor lower activities when tested in batch
12 operations. Because the difference between batch and
13 continuous operations is important, the effect of sulfiding .. dosage on the activity of the system was studied in
15 continuous operation on heavy oil feeds. Similar to the j results in batch operations, maximum catalyst activation , 7 occurred when the catalyst was sulfided to a value of about 18 12 SCF of hydrogen sulfide per pound of molybdenum. But ιg unlike the results obtained in batch reactor studies, the 2 Q activity of the catalyst system in continuous operations was 21 found to decrease as the catalyst precursor was sulfided __ above about 14 SCF of hydrogen sulfide per pound of 23 molybdenum dosage.
25 For catalyst pretreated at an ammonia to molybdenum weight
2β ratio of 0.23, incipient gel formation occurs at a sulfiding 27 dosage of about 12-14 SCF of hydrogen sulfide per pound of
28 molybdenum. The effect of increasing the sulfiding dosage 29 beyond this dose is to thicken the catalyst precursor 30 aqueous gel. No further sulfur uptake is believed to be
31 achieved by increasing the sulfiding process beyond this
32 dosage. While we do not endorse nor intend to be limited by ,- any theory, the loss of activity observed in the continuous _. operation at higher sulfiding dosages is believed to be
01 caused by the larger particles produced at higher sulfiding 02 dosages. Consequently, catalyst activity loss at higher 03 sulfiding dosages is believed to be due both to the decrease 04 in reactive volume caused by catalyst build-up and by the 05 lower surface area of the larger catalyst particles. 06 07 Composition of Matter:
08 go Although the active catalyst precursor is characterized by
20 a sulfur to molybdenum mole ratio of about 3, the final ., catalyst is believed to be an active form of molybdenum
12 disulfide. Decomposition of the catalyst precursor to the
13 final catalyst occurs at conditions typical of the heavy oil .. feed preheaters conventionally used, and requires no further _.- sulfiding for activation. Furthermore, equilibrium
16 calculations indicate that at the reactor conditions
-- employed in slurry operations, molybdenum disulfide is the lβ favored species.
7 _ The molybdenum sulfided catalyst precursors which yield
21 active catalysts are aqueous gels (Figure 4) which appear as 2 _ an elastic coherent mass consisting of an aqueous medium in 2 _ which ultramicroscopic particles are either dispersed or
_. arranged in a network. Furthermore, the catalyst activity
__ is independent of pH since the pH of the resulting aqueous
-_ precursor gels varies over a wide range.
2β Optimum catalyst activity occurs when the catalyst precursor is sulfided to the point of incipient gel formation.
29 30 Extending the sulfiding above this point produces thick gels
31 which are difficult to disperse into the oil. Thick gels
3 _ tend to yield large xerogels as the water is vaporized from
__ the gel and the catalyst is transferred to the oil. Large
_. xerogels tend to generate large solid particles when
compared with those xerogels prepared from materials produced at the incipient gel formation point. A xerogel is defined as a gel containing little or none of the dispersion medium used.
Promotion By Group VIII Metal:
As an enhancement of the denitrogenation activity of the active slurry catalyst of the present invention, it is preferred that a Group VIII metal compound be added to the slurry before mixing the slurry with feed oil and a hydrogen containing gas at elevated temperature and pressure. Such Group VIII metals are exemplified by nickel and cobalt. It is preferred that the weight ratio of nickel or cobalt to molybdenum range from about 1:100 to about 1:2. It is most preferred that the weight ratio of nickel to molybdenum range from about 1:25 to 1:10, i.e., promoter/ molybdenum of 4-10 weight percent. The Group VIII metal, exemplified by nickel, is normally added in the form of the sulfate, and preferably added to the slurry after sulfiding at a pH of about 10 or below and preferably at a pH of about 8 or below. Group VIII metal nitrates, carbonates or other compounds may also be used. The advances of Group VIII metal compound promotion are illustrated in the following examples. In view of the high activity of the slurry catalyst of the present invention the further promotion by Group VIII metal compounds is very advantageous.
To demonstrate the promotion effect of adding Group VIII metal to the sulfided catalyst, various amounts of nickel and cobalt were added to a molybdenum sulfided catalyst gel as soluble nickel or cobalt sulfate, and mixed.
The promoted catalysts were then tested for their hydrogenation/denitrogenation and desulfurization activity * by evaluating their ability to hydrotreat a high nitrogen and aromatic FCC cycle oil. The cycle oil is characterized by the following inspections:
FEEDSTOCK INSPECTIONS FCC Heavy Cycle Oil API Gravity 4.2 Sulfur, wt. % 0.54
Nitrogen, ppm 2928 Carbon, wt. % 90.24 Hydrogen, wt. % 8.64
Figure 5 shows the promotion achieved by nickel for the desulfurization and denitrogenation reactions.
Table III summarizes the operating conditions and results from nickel and cobalt promoted active slurry catalysts of my invention.
< pe Heavy Cycle Oil >
< 0 . 221b NH_./lb . Mo >
< 13 . 5 SCF H 2 S/lb . Mo >
< • ■ 1950 >
-0 > <- •725 β F >
Catalyst-to-Oil Molybdenum, -1 .2- wt. % fresh feed
Nickel as wt. % Mo Cobalt as wt. % Mo
Desulfurization, wt. % Denitrogenation, wt. % H- Consumption, SCF/Bbl. 1162 1155 1136 1300 1075
HEAVY OIL FEEDSTOCK:
The present invention also relates to the manufacture of lubricating oil base stock from heavy oils characterized by low hydrogen to carbon ratios (i.e., less than about 1:8 by weight) and high carbon residues, asphalteneε, nitrogen, sulfur and metal contents. Generally, a heavy oil is that portion of the crude oil boiling above about 650°F. Heavy oils are also those oils containing 5% or more of an oil fraction boiling above 1000°F. Examples of such heavy oils include atmospheric and vacuum residua, deasphalted oil and heavy gas oil.
CATALYST-TO-FEEDSTOCK OIL RATIO:
The catalyst slurry/gel is pumped to the hydroprocessing reactor section where it is contacted with the heavy oil and hydrogen gas. Catalyst in oil concentration of from about 0.05 to about 2.0 wt.% molybdenum based on weight of feedstock are preferred when using the high activity slurry catalyst system for lubricating oil production. A catalyst in oil concentration of from about 0.3 to 2.0% is more preferred, and most preferably a catalyst in oil concentration of about 1% is used.
The catalyst and heavy oil are contacted at elevated temperatures and pressures. The mixture is reacted at high temperatures and hydrogen partial pressures, normally at about 775 β F or greater and at a hydrogen partial pressure of about 700-4500 psi, preferably at about 830°F and 2000 psi, respectively. It is under these conditions that high levels of hydrogenation, demetalation, denitrogenation, desulfurization and conversion occur. The observed levels of conversion up to 100% are unexpected when compared to those attained in conventional fixed bed technology at equivalent catalyst to oil ratios. These levels of conversions, surprisingly, produce prime distillate products. In particular, it is surprising that the 650°F+ productε have unusually superior lubricating oil properties. From the product a lubricating oil fraction boiling above about 650°F is separated. This fraction, ideally suited to lubricating oil base stock manufacture, may be subsequently dewaxed. Additional denitrification of this fraction may also be recommended, in which event it may be subjected to further hydrofinishing using conventional techniques.
The product of the high activity catalyst hydroprocessing may contain too much wax to be a satisfactory lubricating oil base stock, i.e., have a low pour point, in which event an integral part of our process is a dewaxing step. Dewaxing may be carried out by conventional means such as solvent dewaxing or catalytic dewaxing. To facilitate catalytic dewaxing it may be necessary to remove additional nitrogen from the lubricating oil fraction, in which event the use of a hydrotreating or hydrofinishing step should be incorporated into the overall process prior to dewaxing.
It has been found that the final product of the process will have an extraordinarily high viscosity index, especially in view of the nature of the feedstocx. While traditionally, lubricating oil base stocks have a viscosity index of about 100, the present process is found to exceed that figure even when using heavy oil feedstocks.
To determine the suitability of the high activity slurry catalyst process to the production of lubricating oil base stocks, the process was applied to a Hondo atmospheric resid feedstock. The feedstock was processed at a catalyst in oil concentration of 1.1 wt.% molybdenum based on fresh feed. The catalyst was promoted with nickel at 10% by weight based on molybdenum. The products were distilled to yield a C5-650°F product and a 650°F+ product. The 650°F+ product was evaluated as a lubricating oil base stock. Table IV contains a summary of the operating conditions used and the yields obtained. Table V summarizes the feed and product
inspections. Table VI summarizes the results from the lubricating oil testing program.
HIGH ACTIVITY OPERATIONS OPERATING CONDITIONS AND YIELDS
Catalyst, Mo/Ni Promoted Cat. to oil concentration Molybdenum, wt./wt., % 1.11 Nickel, wt./wt., % .11 Operating conditions Water to oil ratio, wt./wt., % 12.6 LHSV, Vol.F.F./Hr./Vol.Rx. 0.202 Reactor Temperature, °F.,Avg. 826. H- Partial Pressure: Inlet, psi. 2235.8 Outlet, psi. 1948.4 Hydrogen Consumption, SCFB 2272 Yields, percent by wt.(vol.) F.F. Hydrogen -3.48 Hydrogen Sulfide 5, 80 Ammonia 1, 10
Total 100.00 (117.2)
Desulfurization, wt. % 98 Denitrification, wt. % 97 Demetalation, wt. % 100 Conversion of 1000°F+, % 100 Carbon Residue Conversion, % 100
HIGH ACTIVITY OPERATIONS FEED AND PRODUCT QUALITIES
HIGH ACTIVITY OPERATIONS LUBE OIL PROCESSING OF THE 650°F+ PRODUCT
Yields, wt. % Oil 75.2 Wax 24.8
Pour Point, β F Viscosity, cS: ~ 40 β C(104°F) 15.99 ~ 100°C(212°F) 3.789 Viscosity Index (VI) 130
It is noteworthy that there was 100% conversion to 1000°F- product. Analysis shows a high paraffinic and a low aromatics level. The nitrogen content indicates that the product would most likely need hydrofinishing to remove nitrogen and provide good stability. Upon removal of nitrogen the wax-rich oil is a good candidate for zeolitic dewaxing. Especially noteworthy was the high yield of dewaxed oil having a viscosity index of 130. This viscosity index is extremely high, especially because the viscosity of the oil is so light (i.e., 16cS @40°C). In general the VI scale severely underrates low viscosity oils.
An embodiment of the present invention is a two-stage process consisting of a slurry hydroprocessing stage followed by a fixed or ebullated bed desulfurization and demetalation process stage, the slurry hydroprocess is operated at temperatures above the incipient cracking temperature of the heavy oil, normally at temperatures above 700 β F, preferably 800 to 960°F, and most preferably 830-870°F. The second stage or desulfurization reactor is preferably operated in upflow mode to minimize the build-up of slurry catalyst in the bed. Superior performance is achieved in this process by bulk demetalation and carbon residue conversion in the slurry reactor or first stage prior to the heavy oil desulfurization process. Operation of the slurry reactor at temperatures above the incipient cracking temperature of the feed is preferred to achieve this demetalation and carbon residue reduction.
The first stage or slurry hydroprocessing can be achieved in bubble up-flow reactors, coil crackers or ebullated bed reactors. Slurry catalyst systems consist of either small particles, or soluble compounds which yield small particles at reactor conditions dispersed in a feedstock. We distinguish several important types of slurry systems in heavy oil hydroprocessing. Basically, the small solid particles (having a diameter less than 20-50 microns) used in slurry systems can be either catalytically active or inactive for aromatic carbon hydrogenation, or can be auto-catalytic for demetalation, or combinations of the above.
Inactive slurry systems are particles which are inactive for aromatic carbon hydrogenation and denitrogenation. Some examples of these materials are mineral wastes and spent FCC catalysts or fines. A known mineral waste material for use in slurry systems is "red mud". In another embodiment of the present invention, porous contact particles (i.e. inactive) are separately added to the heavy oil feedstock prior to hydroprocessing. Examples of such porous contact particles include spent FCC catalyst particles, or fines.
Slurry catalyst systems can be produced during hydroprocessing by either thermal decomposition or reaction with hydrogen/hydrogen sulfide gas mixtures. These systems consist of either oil or water-soluble metal compounds. The water-soluble compound can be either mixed directly into the oil or emulsified with added surfactants. Generally the water-soluble compounds are preferred due to their lower cost when compared to the organic compounds.
Auto-catalytic slurry systems for demetalation reactions are exemplified by such materials as nickel/vanadium oxides or sulfides or oxysulfides which act as demetalation catalysts and can thus be classified as auto-catalytic materials. Addition of nickel and vanadium sulfides to the oil not only increases the demetalation reactions but also initiates the auto-catalytic demetalation reaction.
However, the Group VIB metal activated slurry catalyst of the present invention, preferably promoted by Group VIII metal compounds, provides a substantial improvement to a slurry catalyst system's hydrogenation, denitrogenation, carbon residue conversion and demetalation performance. The catalyst precursors prepared by the methods used in this invention are characterized by extremely small particle size distributions. The bulk of these particles are in the sub-micron range.
An embodiment of the present invention operates in one or two stages. In one-stage operation the heavy oil is contacted with the active catalyst slurry and a hydrogen-containing gas at elevated temperatures and pressures and proceeds directly to a fixed or ebullated bed catalytic reactor with sufficient residence time in the catalytic reactor and at temperatures sufficient to achieve measurable thermal cracking rates. The process may be operated in two-stages where the first-stage comprises the contacting of the active catalyst slurry with the heavy oil and a hydrogen-containing gas with sufficient time and temperature in a thermal treatment reactor, such as a thermal coil or a bubble up-flow column or an ebullated reactor, to achieve reasonable thermal cracking rates. Such
01 temperatures for heavy oil feedstocks are normally above 02 about 700°F, preferably above 750°F. 03 04 The concentration of the active slurry catalyst in the heavy oil is normally from about 100 to 10,000 ppm expressed as 05 weight of metal (molybdenum) to weight of heavy oil 06 feedstock. Demetalation of the heavy oil to the extent of 07 08 greater than 30% metals removal can be obtained even with 09 less than 50% conversion of the 1000°F+ fraction when the 10 catalyst concentration is in this range, and surprisingly,
- x. even when the catalyst concentration is less than about
500 ppm, or even 200 ppm. If the 1000°F+ conversion of the
12 heavy oil is less than 70% the coke yield can be maintained 13 at less than about 1%, and surprisingly, even at conversions 14 as high as 90% and at low slurry catalyst concentrations
(100-1000 ppm) the coke yield can be maintained at less than l about 2.5 percent.
The process conditions for the second-stage or fixed bed 19 reactor are typical of heavy oil desulfurization conditions 20 except that the preferred flow regime is preferably 21 cocurrent up-flow to minimize the build-up of solids in the 22 bed. The second-stage reactor may be either a fixed, 23 ebullated or a moving bed reactor. The catalyst used in the 24 second stage reactor is a hydrodesulfurization-demetalation 25 catalyst such as those containing a Group VI and/or a 26 Group VIII metal deposited on a refractory metal oxide. 27 Examples of such catalysts are described in U.S. 28 Patents 4,456,701 and 4,466,574 incorporated herein by 29 reference. The process conditions for typical one- and 30 two-stage operations are listed in Table VII. 31 32 33 34
SLURRY HYDROPROCESSING STAGE
Reactor: Thermal Coil Bubble Up-Flow or Ebullated Bed
Flow Regime: Bubble to Dispersed Conditions (typical) Catalyst to Oil
Metal wt, percent: < about 0.01 to about 10 > Temperature: 750 - 1000°F 750 - 875°F Pressure Total: < 500 to 4500 psig >
H2 Pressure: < 200 to 4500 psi. > Recycle Gas Rate: 500 - 2500 SCFB 1500 - 15000 SCFB LHSV, Vol/Hr/Vol: 0.10 - 6.0 1/Hr Coil Volume 0.005 - 0.045 Cu.Ft/Bbl./Day:
FIXED BED HYDROPROCESSING STAGE
Flow Regime: Preferably Up-flow Conditions (typical) Temperature: 625 - 810 β F
Total Pressure: 1500 - 4500 psig
H2 Pressure: 1000 - 4500 psi.
Recycle Gas Rate: 1500 - 15000 SCFB
LHSV,Vol/Hr/Vol: 0.10 - 2.0 1/Hr
Active vs. Inactive Slurry Catalysts:
Quantities of coke greater than 2.5 weight percent based on fresh feed are often formed during thermal treatment of heavy oils. This coke can be held up in fixed bed reactors causing an undesirable increase in the pressure drop across the reactor, loss of catalytic activity and eventually leading to reactor shut down. It is therefore desirable to minimize the formation of coke in the fixed bed catalytic
1 hydroprocessing reactor as well as in any thermal 2 pretreatment which takes place prior to that stage. 3 4 The use of the active catalyst slurry of the present process 5 in the thermal pretreatment stage results in a significant 6 reduction in coke formation compared to pretreatment using 7 other relatively inactive slurry catalysts, such as ammonium 8 heptamolybdate. This is illustrated in the comparative 9 examples of Table VIII. In Table VIII TCHC signifies a run 10 made by the thermal catalytic hydroconversion (TCHC) process using a slurry catalyst which is the relatively inactive 11 2 ammonium heptamolybdate. In Table VIII, the process run 13 labeled ACTIVE corresponds to the use of the active catalyst _.. slurry of the present invention. In the thermal catalytic ις hydroconversion process (TCHC Table VIII) the relatively lβ inactive slurry catalyst was an aqueous ammonium _._- heptamolybdate mixed with a succinimide surfactant. The reactor used for the active process was a stirred autoclave
18 having a length to diameter ratio of 2.6. The (TCHC) 19 thermal catalytic hydroconversion studies were performed in 20 an unstirred reactor having a length to diameter ratio of 21 20. The Maya feedstocks used in both studies were virtually 22 identical with the possible exception of a small difference 23 in the 1000°F+ content. When Maya vacuum residuum is 24 processed using the thermal catalytic hydroconversion 25 process (TCHC) (e.g., USP 4,564,439; USP 4,761,220; 26 USP 4,389,301), in a one-stage process which uses the 27 comparatively inactive slurry catalyst, a coke yield of 4.5% 28 is observed at 85% conversion of 1000 β F+. When the active 29 catalyst slurry of the present process is substituted for 30 this relatively inactive catalyst, a coke yield of only 1.6% 31 is observed at 88% conversion of 1000°F+ fraction. 32 33 34
This reduction in coke yield is observed over a wide range of concentrations of slurry catalysts and thermal severities as illustrated in Figure 6. In Figure 6 coke yields for the process of the present invention and the TCHC process are compared over a wide range of thermal severities as indicated by 1000 β F+ conversion. The coke yield for the active slurry catalyst of the present processes is much less than that for the relatively inactive TCHC processing.
Comparison of Products Produced via Slurry Hydroprocessing Using Active or Inactive (TCHC) Slurry Catalysts
Hydrogen Consumption scf/bbl 1949 1500 Chemical Conversions From Oil
1000+ vol % 88 85
Nitrogen wt. % 54 25
Sulfur wt. % 80 70
Nickel wt. % 96 89
Vanadium wt. % 99 97
Coke Yield t. % 1.6 4.5
1 Among other advantages, Table VIII shows the capability of 2 the process of the present invention to remove metals from 3 heavy oils more efficaciously than the other process. The 4 advantage in this superior metals removal is improved 5 operations of the catalytic hydroprocessing second-stage due 06 to increased catalyst life. Also the demetalation is 07 realized at lower thermal severity and consequently lower 08 destabilization of the feed prior to catalytic go hydroprocessing.
.. Figure 7 illustrates clearly the difference between the
12 present process and the thermal catalytic hydroconversion
13 process. Figure 7 illustrates that the active catalyst
, . process of the present invention provides demetalation at ις lower levels of conversion than the inactive slurry catalyst _. β process. Lower conversion leads to lower destabilization of 17 the feed prior to catalytic hydroprocessing. The less
18 severe the thermal treatment of the feed the more stable are 19 the products obtained.
? ι Active Slurry Catalysts In Resid Hydroprocessing:
«_ Catalyst life in fixed bed or ebullating bed resid
_. hydroprocessing units is limited by metals or coke deposited
25 on the catalyst. The deposited metals and coke plug the catalyst pores and decrease the catalyst activity for 26 hydrogenation, desulfurization and carbon residue removal. 27 Thus, the life of these catalysts can be increased by 28 removing a portion of the metals and coke precursors. The 29 demetalation and coke precursor removal can be achieved with 30 an active slurry catalyst in which some of the metals are 31 deposited on said slurry catalyst prior to contacting the 32 heavy feed with the fixed bed or ebullating bed catalyst. 33 Alternatively the demetalation can be achieved by the slurry 34
01 catalyst within the fixed bed or ebullating bed 02 hydroprocessing unit. 03 04 EXAMPLE II 05 06 The following example illustrates the advantage of 07 pretreating a high metals content heavy feed with an active 08 slurry catalyst prior to feeding the residuum to a fixed bed 09 hydroprocessing unit. The feedstock was an Arabian Heavy 10 atmospheric resid having the inspections listed in 11 Table IX. Table X lists the operating conditions and results when processing this feed containing an active 12 slurry catalyst in a slurry reactor and in a two-stage 13
_.. system consisting of a slurry reactor followed by an upflow
15 fixed bed reactor. For comparison purposes, the results 16 obtained for processing the feed in a fixed bed reactor
17 without the slurry catalyst are also included.
The slurry catalyst was prepared by sulfiding an aqueous
19 ammonium molybdate solution containing 12 weight percent 20 molybdenum and an ammonia to molybdenum weight ratio. The 21 solution was sulfided at 150 β F and 400 psig with a 22 hydrogen-hydrogen sulfide gas mixture equal to 13.5 standard 23 cubic feet of hydrogen sulfide per pound of molybdenum. 24 Nickel sulfate solution was added to the resulting slurry to 25 give a 0.1 nickel to molybdenum weight ratio. The slurry 26 catalyst was dispersed into the feed oil at a 200 ppm level 27 based upon the weight of molybdenum. 28 29
For both tests, the fixed bed reactors were charged with a 30 graded catalyst system: 16.7 volume percent of Catalyst A 31 containing 1.5% cobalt, 6% molybdenum, and 0.8% phosphorous 32 on alumina; 16.7 volume percent of Catalyst B containing 33 1% cobalt, 3% molybdenum, and 0.4% phosphorous on alumina; 34
Q - and 66.6% volume percent of Catalyst C containing 3% nickel,
02 8% molybdenum and 1.8% phosphorous on alumina. The flow 03 direction was upflow with Catalyst A placed at the bottom of 04 the reactor. Catalyst B was placed above Catalyst A, and 05 Catalyst C was placed above Catalyst B. Prior to use, the 06 catalysts were sulfided. The slurry reactor was a one-liter 07 autoclave equipped with a turbine to insure good mixing 08 between the liquid, gas, and catalyst. Flow of the gas, 09 oil, and catalyst was upward.
-- As can be seen in this example, the performance of the fixed
12 bed unit is improved when coupled with a slurry reactor.
13 The cracking conversion and the carbon residue conversion . . are markedly increased, thus resulting in more valuable
15 products. Since a significant amount of nickel and vanadium lβ were deposited on the active catalyst in the slurry reactor,
17 the life of the fixed bed catalyst would be increased lβ because of reduced amounts of metals being deposited.
19 20 One efficient method to increase the yield of distillate is
-x. to feed the heavy uncracked product from a hydroprocessing
22 step to a delayed coker or fluid coker. in these processes,
23 the heavy feed is cracked to light gases, distillates, and
24 coke. Because the distillate products generally are more 25 valuable than coke, it is desirable to minimize the amount
26 of coke, 27 28 If the 1000 β F+ products from the above examples were sent to a delayed coker, the coke yield can be reduced by 29 pretreating the feed using the active slurry catalyst prior 30
31 to hydroprocessing in a fixed bed unit. Fixed bed
32 hydroprocessing without the slurry catalyst pretreatment
33 resulted in a 1000°F+ product of 41.4 volume percent. With 3 - the active slurry catalyst, a yield of only 21.5 volume
percent was obtained. These products contained 15.2% and 20.2% Conradson Carbon, respectively. Thus, the delayed coke yields from these 1000°F+ products would be 10.1 weight percent and 6.9 weight percent, respectively, calculated on a basis of fresh feed to the hydroprocessing unit. The reduction in coke yield due to the pretreatment with the active slurry catalyst is thus 31%.
Material boiling above 1000F
Micro Carbon Residue
01 2 Fixed
03 04 Run Conditions
Slurry Catalyst Concentration, ppm(l None 05 Slurry Reactor LHSV Vol/Hr/H
06 Slurry Reactor Temperature ° Fixed Bed LHSV Vol/Hr/Vo
07 Fixed Bed Temperature °
08 Total Pressure psi
Recycle Gas SCF/
- 0 H„ Consumption SCF/ 850
11 1000°F Cracking Conversion Vol 24.8
12 Liquid Yields Vol 1 133 C ς -350°F 1.8 14 350-500°F 2.1
15 650-1000°F 53.7
16 1000°F+ 41.4
Total 102.7 17 18 Conversions
19 Sulfur 86.9
20 Carbon Residue 59.5
21 Vanadium 90.5
Calculated Delayed Coke
23 YYiieelldd oonn FFrreesshh FFeeeed VtX 6.9 10.1
(1) As Molybdenum