WO1992000807A1 - A high activity slurry catalyst process - Google Patents

Abstract

A high viscosity index lubricating oil is produced from heavy oils by using a high activity slurry catalyst process. The catalyst is produced by sulfiding aqueous Group VIB metal compounds to a dosage greater than 8 SCF hydrogen sulfide per pound of Group VIB metal. The Group VIB metal can be promoted with Group VIII metals to enhance its activity. High activity slurry catalysts for hydroprocessing heavy hydrocarbon oils are produced from Group VIB metal compounds by sulfiding an aqueous mixture of the metal compound with from greater than about 8 to about 14 SCF of hydrogen sulfide per pound of Group VIB metal. The hydroprocessing of heavy oils is improved by the use of a high activity slurry catalyst prepared by sulfiding an aqueous Group VIB metal compound with a gas containing hydrogen sulfide to a dosage greater than 8 SCF of hydrogen sulfide per pound of Group VIB metal. After introducing the slurry catalyst into the heavy oil, and subjecting the mixture to elevated temperatures and partial pressures of hydrogen, the mixture is treated in a fixed or ebullated bed of hydrodesulfurization/hydrodemetalation catalyst under hydroprocessing conditions.

Description

A HIGH ACTIVITY SLURRY CATALYST PROCESS

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U. S. Serial No. 548,157 filed July 5, 1990, U.S. Serial No. 586,622 filed September 21, 1990 and U.S. Serial No. 621,501 filed December 3, 1990.

This application is also a continuation-in-part of

U. S. Serial No. 388,790 filed August 2, 1989, which is a continuation-in-part of U. S. Serial No. 527,414 filed

August 29, 1983 (now USP 4,557,821). This application is also a continuation-in-part of U. S. Serial No. 252,839 filed September 30, 1988, which is a continuation-in-part of U. S. Serial No. 941,456 filed December 15, 1986 (now

USP 4,857,496), which is a continuation-in-part of

U. S. Serial No. 767,767 filed August 21, 1985 (abandoned) which is a continuation-in-part of U. S. Serial No. 527,414 filed August 29, 1983 (now USP 4,557,821). This application is also a continuation-in-part of U. S. Serial No. 275,235 filed November 22, 1988, which is a continuation-in-part of U. S. Serial No. 767,822 filed August 21, 1985 (abandoned) which is a continuation-in-part of U. S. Serial No. 527,414 filed August 29, 1983 (now USP 4,557,821). Related

applications include U. S. Serial No. 767,760 filed

August 21, 1985 (now USP 4,824,821) also a continuation-in-part of U. S. Serial No. 527,414 filed August 29, 1983; U. S. Serial No. 767,768 filed August 21, 1985 (now

USP 4,710,486), also a continuation-in-part of U. S. Serial No. 527,414 filed August 29, 1983; and U. S. Serial

No. 767,821 filed August 21, 1985 (now USP 4,762,812), also a continuation-in-part of U..S. Serial No. 527,414 filed

August 29, 1983 BACKGROUND OF THE INVENTION

This invention relates to the catalytic hydroprocessing of heavy hydrocarbon oils including crude oils, heavy crude oils and residual oils as well as refractory heavy

distillates, including FCC decanted oils and lubricating oils. It also relates to the hydroprocessing of shale oils, oils from tar sands, and liquids derived from coals. The invention relates to a catalyst for the hydroprocessing of such hydrocarbonaceous feedstocks, the use of such

catalysts, and the preparation of such catalysts.

In U. S. Serial No. 527,414 filed August 29,1983 (now

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 The catalyst comprised a dispersed form of molybdenum disulfide prepared by reacting aqueous ammonia and

molybdenum oxide to form an aqueous ammonium molybdate which was reacted with hydrogen sulfide to form a precursor slurry. The precursor slurry was mixed with feed oil, hydrogen and hydrogen sulfide and heated under certain conditions. A variety of dosages of hydrogen sulfide expressed as SCF of hydrogen sulfide per pound of molybdenum were taught to be useful in forming the precursor slurry (Column 3). From 2-8 SCF/LB were preferred (Column 4). It was found to be necessary to mix the slurry with oil in the presence of both hydrogen and hydrogen sulfide in order to obtain a catalytically active slurry catalyst

(Columns 11-12). The oil-slurry mixture was then sulfided with hydrogen and hydrogen sulfide at at least two

temperatures (Column 24) under certain conditions. The feed and catalyst, with water added were charged to the

hydroprocessing reactor. Water introduction was deemed beneficial (Columns 26-27) for certain purposes, as was nickel addition to the slurry catalyst (Columns 42-44).

In U. S. Serial No. 941,456 filed December 15, 1986

(USP 4,857,496), a parent application of the present application, is described a sulfiding process in which there are two or three heating steps providing time-temperature sequences to complete the preparation of the final catalyst prior to flowing the feed to the higher temperature

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. U. S. Serial No. 767,760 filed August 21, 1985

(USP 4,824,821) also a continuation-in-part of

U. S. Serial No. 527,414 filed August 29, 1983 describes the promotion of a Group VIB slurry catalyst by the addition of a Group VIII metal such as nickel or cobalt, to the aqueous ammonia compound after sulfiding is underway.

U. S. Serial No. 767,768 filed August 21, 1985

(USP 4,710,486) also a continuation-in-part of U. S. Serial No. 527,414 filed August 29, 1983 describes the specific regulation of the amount of sulfiding occurring in

intermediate temperature sulfiding steps by stoichiometric replacement of oxygen associated with the Group VIB metal with sulfur up to fifty to ninety-five percent replacement. At least three stages of sulfiding were preferred with additional replacement of oxygen by sulfur in the high temperature step. U. S. Serial No. 767,821 filed August 21, 1985

(USP 4,762,812) also a continuation-in-part of U. S. Serial No. 527,414 filed August 29, 1983 described a process for the recovery of spent molybdenum catalysts.

A parent application of the present application U. S. Serial No. 275,235 filed November 22, 1988 described a Group VIB metal sulfide slurry catalyst for hydroprocessing heavy oils or residual oil which has a pore volume in the

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

hydrogenated in one or two stages by contacting the oil with hydrogen in the presence of added dispersed hydrogenation catalysts suspended in the oil, as well as in the additional presence of porous solid contact particles, in the

two-stage version, the normally liquid product of the first stage is hydrogenated in a catalytic hydrogenation reactor. The dispersed catalyst can be added as an oil/water emulsion prepared by dispersing a water-soluble salt of one or more transition elements in oil. The porous contact particles are preferably inexpensive materials such as alumina, porous silica gel, and naturally occurring or treated clays.

Examples of suitable transition metal compounds include (NH₄)₂ MoO₄, ammonium heptamolybdate and oxides and sulfides of iron, cobalt and nickel. The second reaction zone preferably contains a packed or fixed bed of catalysts, and the entire feed to the second reaction zone preferably passes upwardly through the second zone.

In USP 4,564,439 a heavy oil is converted to transportation fuel in a two-stage, close-coupled process, wherein the first stage is a hydrothermal treatment zone for the

feedstock mixed with dispersed demetalizing contact particles having coke-suppressing activity, and hydrogen; and the second stage closely coupled to the first, is a hydrocatalytic processing reactor.

The specifications of all of the foregoing U. S. Patent applications are incorporated herein by reference as if fully set forth in ipsis verbis.

FIELD OF THE INVENTION Increasingly, petroleum refiners find a need to make use of heavier or poorer quality crude feedstocks in their

processing. As that need increases the need also grows to process the fractions of those poorer feedstocks boiling at elevated temperatures, particularly those temperatures above 1000°F, and containing increasingly high levels of

contaminants, such as undesirable metals, sulfur, and coke-forming precursors. These contaminants significantly interfere with the hydroprocessing of these heavier

fractions by ordinary hydroprocessing means. The most common metal contaminants found in these hydrocarbon

fractions include nickel, vanadium, and iron. The various metals deposit themselves on hydrocracking catalysts, tending to poison or de-activate those catalysts.

Additionally, metals and asphaltenes, and coke-precursors can cause interstitial plugging of catalyst beds, reduce catalyst life, and run length. Moreover, asphaltenes also tend to reduce the susceptibility of hydrocarbons to

desulfurization processes. Such de-activated or plugged catalyst beds are subject to premature replacement. As a practical matter the run length in a fixed bed resid desulfurization process is limited by coke and/or metals loadings of the catalyst. 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 500ºF and below about 1300ºF, and will generally have a kinematic viscosity greater than about 2cS (measured at 100ºC). 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. Generally, lubricating oil base stocks prepared from

hydrocarbon feedstocks boiling above 1000°F require

pretreatment prior to the upgrading zone. One such

pretreatment method is solvent deasphalting, which removes heavy hydrocarbonaceous components which otherwise form precipitates during lube oil processing. The use of these pretreatment methods adds additional processing steps over the process of this invention, and leads to low yields of lubricating oil stocks. Distillates suitable for use as lubricating oil base stocks may be further treated to meet specific quality

specifications. Wax may be removed to lower the pour point, Dewaxing may be carried out by conventional means known in the art such as, for example, by solvent dewaxing or by catalytic dewaxing. Distillates recovered from the

upgrading zone may also be further treated with a catalyst in the presence of hydrogen to remove hydrocarbonaceous components which are subject to oxidation and formation of color bodies during storage.

It would also be advantageous if a slurry catalyst process produced a lubricating oil base stock with high viscosity index from heavy oils.

SUMMARY OF THE INVENTION

The present invention provides a high activity catalyst which is prepared by dispersing a slurry catalyst in a hydrocarbonaceous oil for hydroprocessing. The present process has the advantage over conventional processes of achieving higher conversion of nitrogen, sulfur, metals and bottoms than fixed bed resid desulfurization, thermal or existing slurry processes. The process comprises: sulfiding an aqueous mixture of a Group VIB metal compound with a gas containing hydrogen sulfide to a dosage greater than about 8, preferably from greater than about 8 up to 14 SCF of hydrogen sulfide per pound of Group VIB metal to form a slurry; and mixing the slurry with feed oil and a hydrogen-containing gas at elevated temperature and pressure. Twelve SCF hydrogen sulfide corresponds to about 1 mole of molybdenum per

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

Group VIB metal to form a slurry; adding a Group VIII metal compound to the slurry; and mixing the slurry and Group VIII metal compound with a feed oil and a hydrogen-containing gas at elevated temperature and pressure. The inclusion of

Group VIII metal compounds improves the denitrogenation capability of the slurry catalyst.

A high viscosity index lubricating oil is produced from heavy oils by using our high activity slurry catalyst process. The lubricating oil which is produced is of surprisingly high viscosity index and good viscosity. In our process, the highly active Group VIB metal sulfide catalyst slurry is contacted with feed oil and a hydrogencontaining gas at elevated temperature and pressure; and separating from the product an oil fraction boiling above about 650ºF which is subsequently dewaxed. The process also comprises adding a Group VIII metal compound to the slurry; contacting the slurry catalyst containing the Group VIB and the Group VIII metal with a feed oil and a hydrogen- containing gas at elevated temperature and pressure to effect hydroprocessing of said feed oil; and separating a product lubricating oil base stock boiling above about 650°F, which is preferably subsequently dewaxed.

The lubricating oil fraction is of high viscosity index and good viscosity characteristics for lubricating oil base stock. 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 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 the heavy oil feedstock.

In a two-stage process embodiment of the present invention, the heavy oil is contacted in a first-stage with the active catalyst slurry and hydrogen at a temperature and for a time sufficient to achieve measurable thermal cracking in the product stream. Then the effluent of the first-stage is contacted with a fixed or ebullated bed of

desulfurization-demetalation catalyst and hydrogen gas in a second-stage. The second-stage catalyst bed may be graded by catalyst activity and/or temperature profile to promote uniform metal deposition, and preferably the effluent stream flows upwardly through the second-stage catalyst bed. In ebullating beds, the catalyst is graded by staged reactors. In our process the metals are deposited on the slurry catalyst and this catalyst provides the advantage of demetalation at lower levels of conversion of the 1000°F+ fraction of the heavy oil.

Our process provides the advantage that when the 1000°F+ conversion of the heavy feed oil is less than 70%, the coke yield is less than about 1.0%. Even at conversions as high as 90%, and at low slurry catalyst concentrations

(100-1000 ppm), the coke yield is less than 2.5%.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the denitrogenation activity of various catalysts pretreated at essentially the same ammonia to molybdenum ratio but sulfided to various extents. Figures 2-3 show the denitrogenation rate constant, and API gravity increase as a function of the extent of sulfiding,

respectively. Figure 4 indicates the molybdenum sulfided catalyst precursors which yield active catalysts are aqueous gels. Figure 5 shows the benefit of promoting the active catalysts of this invention with a Group VIII metal.

Figure 6 graphs the amount of coke produced by the present invention and the amount of coke produced by a competitive process, as coke yield (weight percent), versus the amount of the 1000°F+ fraction of residua converted to lighter products, as volume percent.

Figure 7 graphs the percent of vanadium metal removed from residua by the present invention and a competitive process, versus the 1000ºF+ fraction conversion of the residua. DETAILED DESCRIPTION OF THE

PREFERRED EMBODIMENTS OF THE INVENTION

The activity of the Group VIB metal slurry catalyst is a function of the preparation conditions. The preferred Group VIB metal is molybdenum, but tungsten compounds are also catalytically useful. Molybdenum is used herein for purposes of exemplification and does not exclude other Group VIB compounds. The high activity slurry catalyst used in the present invention is described in U.S. Serial

No. 548,157, filed July 5, 1990, the disclosure of which has been incorporated herein by reference. In an improved process for the preparation of molybdenum sulfide slurry catalyst, sulfiding of the aqueous solution formed by pretreatment of molybdenum oxide with aqueous ammonia is carried out with a dosage of at least 8 SCF of hydrogen sulfide per pound of molybdenum. When this dosage of hydrogen sulfide is used, it is not necessary to have hydrogen sulfide present in the recycled gas stream during hydroprocessing. Furthermore, the activation of the

catalyst appears independent of the ratio of ammonia to molybdenum used to form the aqueous mixture.

HIGH ACTIVITY CATALYST

We have found that the activity of the final Group VIB metal catalyst is a special function of the activation conditions used to transform the starting Group VIB compound to the final, active catalyst. In the following we will by way of exemplification and discussion refer to the preferred

Group VIB metal, molybdenum and its compounds as typical of our slurry catalyst. However, the reference to molybdenum is by way of preference and exemplification only, and is not intended to exclude other Group VIB metals and compounds thereof.

As an improvement of other methods of preparing the catalyst of the present invention we have found that activation of the catalyst occurs by sulfiding the aqueous solution formed by pretreatment with aqueous ammonia to at least 8 SCF of hydrogen sulfide per pound of molybdenum. With this degree of sulfiding it is no longer necessary to have hydrogen sulfide present in the recycled gas stream during

hydroprocessing. Furthermore, the activation of the

catalyst is achieved relatively independent of the

ammonia-to-molybdenum ratio used to form the aqueous

mixture. Sulfiding;

Catalyst activity is achieved when the extent of sulfiding is from greater than about 8 up to about 14 SCF of hydrogen sulfide per pound of molybdenum. This sulfiding dosage produces a catalyst precursor characterized by a sulfur-to-molybdenum mole ratio of about 3. The effect of

sulfiding on catalyst activation is demonstrated in the first set of examples. In these examples, two types of catalyst were prepared by first reacting molybdenum oxide with aqueous ammonia at identical conditions and with the same amount of ammonia. The aqueous mixture was then sulfided in the absence of added oil. The catalysts differ in the extent of sulfiding provided. The first type was sulfided to a dosage of 2.7 SCF of hydrogen sulfide per pound of molybdenum (SC-21). The second type of catalyst was sulfided beyond 12 SCF of hydrogen sulfide per pound of molybdenum (SC-25-2). The conditions used to pretreat with ammonia and sulfide these catalysts are summarized below.

CATALYST PREPARATION:

Catalyst, SC: -21 -25-2

Pretreatment

NH,/Mo, 1b/1b. 0.23 0.23 Sulfiding:

H₂S/Mo,SCF/1b. 2.7 14.0 Temperature, °F 150 150 Pressure, psig. 30 400 Sulfiding Gas:

Composition, %

H₂S 8-10 8-10 Hydrogen 88-90 88-90 Tables IA-IB compare the results of two runs performed on the same feedstock and at identical conditions with both the undersulfided catalyst SC-21 and the catalyst, SC-25-2.

Catalyst activation is evident from the hydrogen

consumption, denitrogenation, desulfurization, demetalation and 975ºF+ conversion results. Hydrogen consumption was increased from 584 to 1417 SCF per barrel, desulfurization from 38 to 89 weight percent, denitrogenation from 21 to 84 weight percent, demetalation from 66 to 99 weight percent and 975°F+ conversion from 77 to 92 volume percent.

TABLE IA

OPERATING CONDITIONS

Feedstock < - - - - - Hvy . Arabian - - - - - - - - - - - > Catalyst SC-21 SC-25-2

Cat. to oil ratio 0.0213 0.0193

Molybdenum,wt./wt.

LHSV 0.59 0.56

Temperatures, F.

Pretreater : 682 . 682.

Reactor: 808 . 811.

Pressures:

Rx. Inlet, psig: 2842 . 2748.

H₂ partial pressures, psi 1958 . 1498.

H₂S partial pressure, psi 150 . 365.

Recycle gas:

Gas rate, SCF/Bbl. 6650 5419.

TABLE IB

CONVERSIONS Feedstock ← - - - - - - - Hvy . Arabian - - - - - - -→

Conversions:

Hydrogen Consumption, SCFB: 584. 1417.

Conversion:

Vacuum Resid, % as 53.7 71.4

975°F+ vol %

Total 76.6 92.1

Desulfurization, wt. % 38. 89.

Denitrogenation, wt. % 21. 84.

Demetalation, wt. % 66. 99.

Nickel Removal, wt. % 61. 99.

Vanadium Removal, wt. % 67. 99. Catalysts sulfided at higher sulfiding dosages than about 12-14 SCF of hydrogen sulfide per pound of molybdenum yield neither higher nor lower catalyst activities when tested in batch operations. Figure 1 shows the denitrogenation activities various catalysts pretreated at essentially the same ammonia to molybdenum ratio but presulfided with various dosages of hydrogen sulfide. These pretreated and sulfided catalysts were screened in a batch reactor with no added hydrogen sulfide and with a feed that contained little sulfur. No further sulfiding was provided to the catalyst aside from that performed in the presulfiding step in the absence of oil. The results shown in Figure 1 illustrate the criticality of sulfiding this catalyst to greater than 8 SCF H₂S per pound of molybdenum. Ammonia Pretreatment: The catalysts were pretreated over a wide range of ammonia to molybdenum ratios, from materials prepared without ammonia (0 ammonia to molybdenum ratio) to catalysts

pretreated to 0.35 pound of ammonia per pound of molybdenum. The results indicate that catalyst activity is independent of the ammonia to molybdenum ratio used to form the slurry catalyst. Although a slight optimum when the ammonia to molybdenum ratio was about 0.16 was observed, catalysts were produced even when aqueous slurries of molybdenum oxide were appropriately sulfided without ammonia pretreatment.

However, pretreatment with ammonia is preferred because better control of the particle size is achieved when the molybdenum oxide is dissolved in aqueous ammonia. Hydrogen Sulfide Requirements During Hydroprocessing: In prior work it was required to include the recycling of a hydrogen-hydrogen sulfide stream separated from the

hydroprocessing zone wherein the hydrogen sulfide partial pressure was at least 20 psi and the circulation of hydrogen sulfide was greater than 5 SCF per pound of molybdenum.

However, in the present invention, by increasing the

sulfiding dosage, in the absence of oil, to values of from about greater than 8 to about 14 SCF of hydrogen sulfide per pound of molybdenum, not only are active slurry catalysts produced, but the need of having hydrogen sulfide present in the recycled gas stream is eliminated. Table II shows and compares various runs performed with both undersulfided catalyst and the catalysts of this invention. As can be observed, stable and high activity catalysts have been obtained over a wide range of hydrogen sulfide partial pressures and circulation rates at the reactor inlet.

Active catalysts, have been obtained at hydrogen sulfide partial pressures from 271 psi to 3.5 and circulation rates from 78 to as low as 5 SCF of hydrogen sulfide per pound of molybdenum. Effect of Hydrogen Partial Pressure During Sulfiding: In the examples given above all the catalysts were sulfided with hydrogen sulfide contained in a hydrogen gas. I have now demonstrated that active molybdenum sulfide catalysts can be produced when the sulfiding step is performed in the absence of hydrogen. To study this effect a series of catalysts were prepared at various sulfiding dosages with a gas containing no hydrogen. The catalysts were prepared using conventional sulfiding techniques described in the background section, except that the sulfiding gas stream contained no hydrogen. The sulfiding gas consisted of 20% by mole of hydrogen sulfide and 80% nitrogen. The resulting catalysts were tested in a batch microactivity unit for their denitrogenation, hydrogenation, and desulfurization activities. The catalysts were tested at typical catalyst conditions with the gas charge consisting of pure hydrogen.

The results from this study were compared to those obtained with catalysts sulfided under hydrogen partial pressure. Figures 2-3 show the denitrogenation rate constant, and API gravity increase as a function of the extent of sulfiding. Also contained in these figures are similar results obtained with catalysts sulfided with a hydrogen sulfide and hydrogen gas mixture having the same hydrogen sulfide composition as that used in this study. From the denitrogenation results, it is evident that active catalysts were obtained regardless of the hydrogen partial pressure.

Although in both cases active catalysts were produced, activation of the slurry catalyst occurred at a lower sulfiding dosage, i.e. at 8-10 SCF hydrogen sulfide per pound of molybdenum, when the catalysts were produced under no hydrogen partial pressure. This value was slightly lower than that sulfiding dosage required to activate the catalyst when it is activated under hydrogen partial pressure, i.e. at 12-14 SCF of hydrogen sulfide per pound of

molybdenum. Higher API gravities and amounts of hydrogen used to upgrade the liquid product were obtained with catalysts sulfided under hydrogen partial pressure.

>

Effect of Sulfiding On Continuous Operations:

We have demonstrated that activation of the slurry catalyst occurs by sulfiding aqueous solutions or mixtures of ammonia molybdate and molybdenum oxides. Activity increases as the extent of sulfiding is increased. Maximum activity is obtained when the extent of sulfiding is about 12 SCF of hydrogen sulfide per pound of molybdenum. Catalyst

precursors sulfided at higher sulfiding dosages than about 14 SCF of hydrogen sulfide per pound of molybdenum produce neither higher nor lower activities when tested in batch operations. Because the difference between batch and continuous operations is important, the effect of sulfiding dosage on the activity of the system was studied in

continuous operation on heavy oil feeds. Similar to the results in batch operations, maximum catalyst activation occurred when the catalyst was sulfided to a value of about 12 SCF of hydrogen sulfide per pound of molybdenum. But unlike the results obtained in batch reactor studies, the activity of the catalyst system in continuous operations was found to decrease as the catalyst precursor was sulfided above about 14 SCF of hydrogen sulfide per pound of

molybdenum dosage. For catalyst pretreated at an ammonia to molybdenum weight ratio of 0.23, incipient gel formation occurs at a sulfiding dosage of about 12-14 SCF of hydrogen sulfide per pound of molybdenum. The effect of increasing the sulfiding dosage beyond this dose is to thicken the catalyst precursor aqueous gel. No further sulfur uptake is believed to be achieved by increasing the sulfiding process beyond this 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 caused by the larger particles produced at higher sulfiding dosages. Consequently, catalyst activity loss at higher sulfiding dosages is believed to be due both to the decrease in reactive volume caused by catalyst build-up and by the lower surface area of the larger catalyst particles.

Composition of Matter: Although the active catalyst precursor is characterized by a sulfur to molybdenum mole ratio of about 3, the final catalyst is believed to be an active form of molybdenum disulfide. Decomposition of the catalyst precursor to the final catalyst occurs at conditions typical of the heavy oil feed preheaters conventionally used, and requires no further sulfiding for activation. Furthermore, equilibrium

calculations indicate that at the reactor conditions

employed in slurry operations, molybdenum disulfide is the favored species. The molybdenum sulfided catalyst precursors which yield active catalysts are aqueous gels (Figure 4) which appear as an elastic coherent mass consisting of an aqueous medium in 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. Optimum catalyst activity occurs when the catalyst precursor is sulfided to the point of incipient gel formation.

Extending the sulfiding above this point produces thick gels which are difficult to disperse into the oil. Thick gels 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.

TABLE III

Feedstock < - - - - pec Heavy Cycle Oil - - - - >

Catalyst

Ammonia Pretreatment < - - - - - 0 . 221b NH₃/lb . Mo - - - - >

Sulfiding Dosage < - - - - 13 . 5 SCF H₂S/lb . Mo- - - - >

Reactor

Hydrogen, psi < - - ps - - - - - - - - - - - 1950 - - - - - - - - - - > H₂S, i < - - - - - - - - - - - - - -0 - - - - - - - - - - - - - > Temperature < - - - - - - - - - - - - - 725º F - - - - - - - - - - >

Catalyst-to-Oil

Molybdenum, < - - - - - - - - - - - - -1 .2 - - - - - - - - - - - > wt. % fresh feed

Nickel as wt. % Mo 0 2.3 0 9.1 0 Cobalt as wt. % Mo 0 0 2.1 0 8.8

Desulfurization, wt. % 65.6 76.2 75.0 84.5 83.6 Denitrogenation, wt. % 71.2 77.6 72.2 80.8 75.4 H₂ 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.

HYDROPROCESSING:

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 775ºF 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+ products 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. DEWAXING:

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 feedstock. 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.

EXAMPLE I

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.

TABLE IV

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.

H₂ 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

C₁ plus C₂ 3, 05

C₃ plus C₄ 4.92 (9 2)

C5- 650°F Distillates 66.07 (81 0) 650°F+ 22.86 (27 0) 1000°F+ 0.00 (0 0) Coke 0.67

Total 100.00 (117.2)

Conversions:

Desulfurization, wt. % 98

Denitrification, wt. % 97

Demetalation, wt. % 100

Conversion of 1000°F+, % 100

Carbon Residue Conversion, % 100 TABLE V

HIGH ACTIVITY OPERATIONS FEED AND PRODUCT QUALITIES

Feed < - - - - - - - - PRODUCT- - - - - - - - >

Hondo 650°F+ C5-650ºF 650° F+

Gravity, API 8.1 42.3 33.4

Sulfur, wt. % 5.67 0.08 0.03

Nitrogen, ppm 9600 150 424

Hydrocarbon type. vol. % wt. %

Aromatics : - - - - 19. 3 24 .2

Saturates: - - - - 80.7 75.0

Paraffins: - - - - 48 .1 31.7

Naphthenes: - - - - 32 .6 43.3

Sulfur compounds : - - - - - - - - 0.8

Total - - - - 100.00 100.00

Distillation, °F D-1160 TBP D-2887

IBP 667 83 614

10 % 767 250 652

30 % 914 364 687

50% 1032 445 719

70 % 521 758

90 % 604 828

EP % 666 938

TABLE VI

HIGH ACTIVITY OPERATIONS LUBE OIL PROCESSING OF THE 650°F+ PRODUCT

Solvent Dewaxing:

Yields, wt. %

Oil 75.2

Wax 24.8

Dewaxed Oil:

Pour Point, ºF

Viscosity, cS:

@ 40ºC(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.

TWO-STAGE PROCESS:

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 700ºF, 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. Slurry Hydroprocessing:

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.

Process Conditions:

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 temperatures for heavy oil feedstocks are normally above about 700°F, preferably above 750°F.

The concentration of the active slurry catalyst in the heavy oil is normally from about 100 to 10,000 ppm expressed as weight of metal (molybdenum) to weight of heavy oil

feedstock. Demetalation of the heavy oil to the extent of greater than 30% metals removal can be obtained even with less than 50% conversion of the 1000°F+ fraction when the catalyst concentration is in this range, and surprisingly, even when the catalyst concentration is less than about

500 ppm, or even 200 ppm. If the 1000°F+ conversion of the heavy oil is less than 70% the coke yield can be maintained at less than about 1%, and surprisingly, even at conversions as high as 90% and at low slurry catalyst concentrations

(100-1000 ppm) the coke yield can be maintained at less than about 2.5 percent.

The process conditions for the second-stage or fixed bed reactor are typical of heavy oil desulfurization conditions except that the preferred flow regime is preferably

cocurrent up-flow to minimize the build-up of solids in the bed. The second-stage reactor may be either a fixed, ebullated or a moving bed reactor. The catalyst used in the second stage reactor is a hydrodesulfurization-demetalation catalyst such as those containing a Group VI and/or a

Group VIII metal deposited on a refractory metal oxide.

Examples of such catalysts are described in U.S.

Patents 4,456,701 and 4,466,574 incorporated herein by reference. The process conditions for typical one- and two-stage operations are listed in Table VII. TABLE VII

SLURRY HYDROPROCESSING STAGE

Reactor: Thermal Coil Bubble Up-Flow or Ebullated Bed

Flow Regime : Bubble to Di spersed - - - - - - - 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 .

le Gas Rate: 500 - 2500 SCFB 1500 - -1 -50 -0 - - - - > Recyc 0 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 - 810ºF

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 hydroprocessing reactor as well as in any thermal

pretreatment which takes place prior to that stage.

The use of the active catalyst slurry of the present process in the thermal pretreatment stage results in a significant reduction in coke formation compared to pretreatment using other relatively inactive slurry catalysts, such as ammonium heptamolybdate. This is illustrated in the comparative examples of Table VIII. In Table VIII TCHC signifies a run made by the thermal catalytic hydroconversion (TCHC) process using a slurry catalyst which is the relatively inactive ammonium heptamolybdate. In Table VIII, the process run labeled ACTIVE corresponds to the use of the active catalyst slurry of the present invention. In the thermal catalytic hydroconversion process (TCHC Table VIII) the relatively inactive slurry catalyst was an aqueous ammonium

heptamolybdate mixed with a succinimide surfactant. The reactor used for the active process was a stirred autoclave having a length to diameter ratio of 2.6. The (TCHC) thermal catalytic hydroconversion studies were performed in an unstirred reactor having a length to diameter ratio of 20. The Maya feedstocks used in both studies were virtually identical with the possible exception of a small difference in the 1000°F+ content. When Maya vacuum residuum is processed using the thermal catalytic hydroconversion process (TCHC) (e.g., USP 4,564,439; USP 4,761,220;

USP 4,389,301), in a one-stage process which uses the comparatively inactive slurry catalyst, a coke yield of 4.5% is observed at 85% conversion of 1000ºF+. When the active catalyst slurry of the present process is substituted for this relatively inactive catalyst, a coke yield of only 1.6% is observed at 88% conversion of 1000°F+ fraction. 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 1000ºF+ conversion. The coke yield for the active slurry catalyst of the present processes is much less than that for the relatively inactive TCHC processing.

TABLE VIII

Comparison of Products Produced via Slurry Hydroprocessing Using Active or Inactive (TCHC) Slurry Catalysts

Run Identification ACTIVE TCHC

Feed Properties

Feed Stock Maya 900°F+ Maya 975ºF+

Carbon wt. % 83.73 83.89

Hydrogen wt. % 9.83 9.85

Nitrogen ppm 7000 6900

Sulfur wt. % 4.99 5.15

Nickel ppm 118 112

Vanadium ppm 590 600

Run Conditions

Temperature °F 836 835

Pressure psig 2402 2400

Gas Recycle scf/bbl 7052 6500

LHSV vol/hr/vol 0.10 0.39

Slurry Catalyst

Catalyst Cone.

as ppm Mo ppm 1000 1000

Nickel Cone. ppm 100 0

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 wt. % 1.6 4.5 Among other advantages, Table VIII shows the capability of the process of the present invention to remove metals from heavy oils more efficaciously than the other process. The advantage in this superior metals removal is improved operations of the catalytic hydroprocessing second-stage due to increased catalyst life. Also the demetalation is realized at lower thermal severity and consequently lower destabilization of the feed prior to catalytic

hydroprocessing. Figure 7 illustrates clearly the difference between the present process and the thermal catalytic hydroconversion process. Figure 7 illustrates that the active catalyst process of the present invention provides demetalation at lower levels of conversion than the inactive slurry catalyst process. Lower conversion leads to lower destabilization of the feed prior to catalytic hydroprocessing. The less severe the thermal treatment of the feed the more stable are the products obtained. Active Slurry Catalysts In Resid Hydroprocessing: Catalyst life in fixed bed or ebullating bed resid

hydroprocessing units is limited by metals or coke deposited on the catalyst. The deposited metals and coke plug the catalyst pores and decrease the catalyst activity for hydrogenation, desulfurization and carbon residue removal. Thus, the life of these catalysts can be increased by removing a portion of the metals and coke precursors. The demetalation and coke precursor removal can be achieved with an active slurry catalyst in which some of the metals are deposited on said slurry catalyst prior to contacting the heavy feed with the fixed bed or ebullating bed catalyst. Alternatively the demetalation can be achieved by the slurry catalyst within the fixed bed or ebullating bed

hydroprocessing unit.

EXAMPLE II

The following example illustrates the advantage of

pretreating a high metals content heavy feed with an active slurry catalyst prior to feeding the residuum to a fixed bed hydroprocessing unit. The feedstock was an Arabian Heavy atmospheric resid having the inspections listed in

Table IX. Table X lists the operating conditions and results when processing this feed containing an active slurry catalyst in a slurry reactor and in a two-stage system consisting of a slurry reactor followed by an upflow fixed bed reactor. For comparison purposes, the results obtained for processing the feed in a fixed bed reactor without the slurry catalyst are also included.

The slurry catalyst was prepared by sulfiding an aqueous ammonium molybdate solution containing 12 weight percent molybdenum and an ammonia to molybdenum weight ratio. The solution was sulfided at 150ºF and 400 psig with a

hydrogen-hydrogen sulfide gas mixture equal to 13.5 standard cubic feet of hydrogen sulfide per pound of molybdenum.

Nickel sulfate solution was added to the resulting slurry to give a 0.1 nickel to molybdenum weight ratio. The slurry catalyst was dispersed into the feed oil at a 200 ppm level based upon the weight of molybdenum.

For both tests, the fixed bed reactors were charged with a graded catalyst system: 16.7 volume percent of Catalyst A containing 1.5% cobalt, 6% molybdenum, and 0.8% phosphorous on alumina; 16.7 volume percent of Catalyst B containing 1% cobalt, 3% molybdenum, and 0.4% phosphorous on alumina; and 66.6% volume percent of Catalyst C containing 3% nickel,

8% molybdenum and 1.8% phosphorous on alumina. The flow direction was upflow with Catalyst A placed at the bottom of the reactor. Catalyst B was placed above Catalyst A, and Catalyst C was placed above Catalyst B. Prior to use, the catalysts were sulfided. The slurry reactor was a one-liter autoclave equipped with a turbine to insure good mixing between the liquid, gas, and catalyst. Flow of the gas, oil, and catalyst was upward. As can be seen in this example, the performance of the fixed bed unit is improved when coupled with a slurry reactor.

The cracking conversion and the carbon residue conversion are markedly increased, thus resulting in more valuable products. Since a significant amount of nickel and vanadium were deposited on the active catalyst in the slurry reactor, the life of the fixed bed catalyst would be increased because of reduced amounts of metals being deposited.

One efficient method to increase the yield of distillate is to feed the heavy uncracked product from a hydroprocessing step to a delayed coker or fluid coker. in these processes, the heavy feed is cracked to light gases, distillates, and coke. Because the distillate products generally are more valuable than coke, it is desirable to minimize the amount of coke,

If the 1000ºF+ products from the above examples were sent to a delayed coker, the coke yield can be reduced by

pretreating the feed using the active slurry catalyst prior to hydroprocessing in a fixed bed unit. Fixed bed

hydroprocessing without the slurry catalyst pretreatment resulted in a 1000°F+ product of 41.4 volume percent. With 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%.

TABLE IX

Arab Heavy

Feed Atmos. Resid

Nitrogen ppm 2824 Sulfur wt.% 4.5

Material boiling above 1000F vol% 55

API Gravity APIº 11.3

Micro Carbon Residue wt.% 14.4

Carbon wt.% 84.38 Hydrogen wt.% 10.82

Nickel ppm 27

Vanadium ppm 100

Iron ppm 3

TABLE X

Slurry Plus Fixed

Slurry Fixed Bed Bed

Run Conditions

Slurry Catalyst Concentration, ppm(1) 200 200 None Slurry Reactor LHSV Vol/Hr/Hr 0.53 0.53

Slurry Reactor Temperature °F 822 822

Fixed Bed LHSV Vol/Hr/Vol 0.37 0.34 Fixed Bed Temperature °F 723 718

Total Pressure psial 1720 1690 1901

Recycle Gas SCF/B 5360 4570 5000 H₂ Consumption SCF/B 400 1189 850 1000°F Cracking Conversion Vol% 50.0 60.9 24.8

Liquid Yields Vol%

C₅-350°F 4.4 9.8 1.8

350-500°F 4.6 7.6 2.1

500-650°F 10.7 16.2 3.7 650-1000°F 52.9 48.9 53.7

1000°F+ 27.5 21.5 41.4

Total 100.1 104.0 102.7

Conversions

Nitrogen 3.0 57.6 54.2 Sulfur 29.8 87.2 86.9

Carbon Residue 28.0 68.8 59.5

Nickel 14.7 98.2 75.9 Vanadium 44.4 99.5 90.5

Calculated Delayed Coke

Yield on Fresh Feed Wt% 6.9 10.1

(1) As Molybdenum

Claims

WHAT IS CLAIMED IS:

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

hydrogen-containing gas at elevated temperature and pressure.

A process according to Claim 1 wherein said hydrogen sulfide dosage is about 8-14 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.

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.

9. A process according to Claim 1 wherein said Group VIB metal compound aqueous mixture is obtained by treating molybdenum oxide with aqueous ammonia.

10. A process according to Claim 1 wherein said elevated temperature is at least about 350° F.

11. A process according to Claim 1 wherein prior to mixing with feed oil, said slurry is in the incipient gel stage.

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.

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.

14. A process for preparing a dispersed Group VIB metal

sulfide catalyst for hydrocarbon oil hydroprocessing comprises: (a) sulfiding ah aqueous mixture of a Group VIB metal compound, with a gas containing hydrogen sulfide, to a dosage of about 8-14 SCF of hydrogen sulfide per pound of Group VIB metal, to form a slurry;

(b) adding a Group VIII metal compound to said slurry; and

(c) mixing said slurry and Group VIII metal compound with a feed oil and a hydrogen-containing gas at elevated temperature and pressure.

15. A process according to Claim 14 wherein said slurry is at the incipient gel formation stage.

16. A process according to Claim 14 wherein said Group VIII metal compound is added to said slurry at a slurry pH less than about 8.

17. A process according to Claim 14 wherein said Group VIII metal to Group VIB metal weight ratio is about 1:2 to about 1:100.

18. A process according to Claim 14 wherein said Group VIB metal is molybdenum.

19. A process according to Claim 14, 15, 16, 17 or 18

wherein said Group VIII metal is nickel.

20. A process according to Claim 14 wherein said Group VIII metal compound is a sulfate, nitrate or carbonate.

21. A process according to Claim 14, 15, 16, 17 or 18

wherein said Group VIII metal is cobalt.

22. A process of hydroprocessing a heavy hydrocarbonaceous feedstock comprises contacting said feedstock with the catalyst of Claim 1 in the presence of hydrogen at elevated temperature and pressure.

23. 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) contacting the product of step (a) with a heavy oil feedstock and a hydrogen-containing 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;

(c) separating from the product of step (b) a fraction boiling above about 650°F; and

(d) dewaxing said fraction to produce said lubricating oil.

24. A process according to Claim 23 wherein said heavy oil feedstock is contacted with the product of step (a) at a temperature of about 775°F, or greater, and at a hydrogen partial pressure of about 700-4500 psi.

25. The product in the lubricating oil range boiling range produced according to Claim 23 is hydrotreated prior to catalytic dewaxing.

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 hydrogen-containing 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.

27. A process according to Claim 26 wherein the product of step (a) is in the incipient gel formation stage.

28. A process for the hydroprocessing of heavy

hydrocarbonaceous oil containing metal contaminants comprises introducing said oil, an active catalyst slurry and a hydrogen-containing gas at elevated temperature and pressure into a fixed or ebullating bed of hydrodesulfurization-hydrodemetalation catalyst at temperatures greater than about 700°F: wherein said active catalyst slurry is prepared by sulfiding an aqueous mixture of a Group VIB metal compound with a gas containing hydrogen sulfide to a dosage greater than 8 SCF of hydrogen sulfide per pound of Group VIB metal.

29. A process for the hydroprocessing of heavy

hydrocarbonaceous oil containing metal contaminants comprises introducing said oil, an active catalyst slurry, porous contact particles, and a

hydrogen-containing gas at elevated temperatures and pressures into in a fixed or ebullating bed of

hydrodesulfurization-hydrodemetalation catalyst at temperatures greater than about 700°F: wherein said active catalyst slurry is prepared by sulfiding an aqueous mixture of a Group VIB metal compound with a gas containing hydrogen sulfide to a dosage greater than 8 SCF of hydrogen sulfide per pound of Group VIB metal.

30. A process for the hydroprocessing of heavy

hydrocarbonaceous oil containing metal contaminants comprises: (a) contacting said oil in a first stage with an active catalyst slurry and hydrogen at a temperature and for a time sufficient to achieve measurable thermal cracking in the product stream; and

(b) in a second stage, contacting said product stream with hydrogen in a fixed or ebullating bed of hydrodesulfurization-hydrodemetalation catalyst at temperatures greater than about 700°F: wherein said active catalyst slurry is prepared by 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.

31. A process according to Claim 28, 29 or 30 wherein the oil flow is upward through said fixed bed.

32. A process according to Claim 28, 29 or 30 wherein the 1000ºF+ fraction conversion of said heavy oil is less than 50%, the percent demetalation of nickel or

vanadium is greater than 30%, and the slurry catalyst concentration is about 100-10,000 ppm in said heavy oil.

33. A process according to Claim 28, 29 or 30 wherein the 1000ºF+ fraction conversion of said heavy oil is greater than 50% and the coke yield is less than about 2.5% at a slurry catalyst concentration of about

100-10,000 ppm in said heavy oil.

34. A process according to Claim 31 or 32 wherein the slurry catalyst concentration is less than about 500 ppm.

35. A process according to Claim 31 or 32 wherein the slurry catalyst concentration is less than about

200 ppm.

36. A process according to Claim 28, 29 or 30 wherein to said slurry is added a Group VIII metal compound.