CA1221353A - Catalyst for the simultaneous demetallization and desulfurization of heavy hydrocarbon feedstocks - Google Patents

Abstract

ABSTRACT
This invention relates to catalysts having simultaneous desulfurization and demetallization activity in treatment of heavy crudes and residues which approaches unity over a useful life in excess of 80 days; the catalyst comprises a porous alumina support and has a pore volume of about 0.5 to about 1.2 ml/g and an average pore diameter of about 150 to about 300 .ANG., the alumina support is impregnated with a Group VIB
metal, for example molybdenum, in an amount of about 5 to about 30 percent of the catalyst weight expressed as metal oxide and a Group VIII metal in an amount of about 0.1 to 8 percent of the catalyst weight expressed as metal oxide.

Description

This invention relates to catalysts for the simultaneous demetallization and desulfurization of heavy hydrocarbon feed-stock.
The use of catalysts For the demetallization of crude hydrocarbons of petroleum origin has been known for some time.
Demetallization of such cruxes is desirable in order to reduce the content of contaminating metals, for example vanadium, nickel, iron, etc., because they reduce the useful life of contacted catalysts used in refiring operations, such as hydra-cracking, hydrodesulfurization and catalytic cracking. These contaminating metals are deposited on the catalyst as a poison;
they deactivate the catalyst and this leads to a premature removal of the deactivated catalyst from the reactor and its replacement after a shorter period than would otherwise occur.
Various metals have been used as catalysts for the treatment of petroleum hydrocarbons for the elimination of the contaminating metals and sulfur present therein. For example, the elimination of metals can be accomplished by using bauxite as a catalyst (US. Patent Nos. 2~687,983 and 2,769,758), using iron oxide and alumina (US. Patent No. 2,771,401); or using macro porous alumina having a large macro porosity in a boiling bed (US. Patent 3,901,792).
A multi step hydra treatment method has been proposed in order to remove some disadvantages of the single step pro-seeders (US. Patent No. 3,696,027). The multi-step method consists of passing a heavy hydrocarbon at high pressures and temperature and in the presence of hydrogen, through a three-I;

I ~2~3~3 phase reactor of particles of a macro porous catalyst. The catalyst has a high capacity for accepting metals but a low desulfurizing activity. The liquid effluent as treated by the first macro porous catalyst is raised to a high temperature and pressure in the presence of hydrogen in a fixed bed reactor which contains particles of catalyst having a moderate dozily-foreseeing activity. Finally, the effluent from the preceding reactor is raised to a high temperature and pressure, in the presence of hydrogen, in a third fixed bed reactor which con-twins particles of catalyst which are highly active in dozily-furization.
According to the invention, a catalyst is provided for the hydra treatment of heavy crudest In particular the invention is concerned with a catalyst for the simultaneous hydrodemetallization and hydra-desulfurization of heavy crudest The catalyst of the invention is capable of Somali-tonsil demetallizing and desulfurizing heavy cruxes over a long period of time such that no significant decrease in de-metallizing or desulfurizing activity occurs over at least dyes of continuous processing of heavy crudest Furthermore, the ratio of percent of demetallizing to desulfurizing activity approaches unity over a useful life in excess of 80 days.
In accordance with the invention the catalyst come proses at least one metallic component selected from Group VIM
of the Periodic Table and at least one metallic component of Group VIII of the Periodic Table. These metallic components 7.

3t3 3 are deposited on a refractory oxide support or base; the catalyst having the following physical properties: average pore diameter varying between 150 and 300, especially 200 to 300 and preferably 240 to 280 Angstrom units and a total porous volume between 0.50 and 1.20, in particular between 0.70 and 1.00, and suitably about 0.9 ml/gram.
The catalyst also has a characteristic signal band strength ratio, as determined by X-ray photoelectron spectra-scope Iamb VIB)/I (refractory metal) and Iamb VOW (refract-tory metal) wherein Me VIM and Me VIII indicate the Group VIM and VIII metallic components respectively and 'refractory metal' indicates the metal of the refractory oxide support.
In particular, the ratio Iamb VIB)/I (refractory metal) is between 5 andl3, and the ratio Iamb VOW (refractory metal) is between 1 and 5.
In a preferred embodiment the catalyst has a pore size distribution such that less than 10% of the pores are larger than 300 A in diameter. Further, preferably at least 60 to 80% of the total pore volume has pores with a diameter of more than lo A.
Furthermore in a particular embodiment in which the metallic components were molybdenum and nickel the catalyst presented no important information when subjected to X-ray diffraction spectroscopy. Infrared or Reman spectroscopy shows an intense signal or peak between 930 and 950 cm 1, which is characteristic of molybdenum species in a Comma or Nemo phase. On the other hand only a poorly defined signal occurs between 950 and 960 cm 1 which indicates that a posy molybdate phase is present in small quantities only. It has been found that the improvement over -the prior art is obtained by using the catalyst to hydra treat heavy cruxes and residues, and it is based fundamentally on its properties whereby there is simultaneously obtained a demetallizing activity and a desulfurizing activity with good stability. This represents a commercial advantage in the refining of heavy hydrocarbons and residues.
The catalyst of the invention has a controlled duster-button of misprize and macro pores. The term "misprize" refers to a portion of the total pore volume which contains pores having a diameter in the range of 100 to 600 Angstrom units, determined by the method of nitrogen absorption described by E. V. Ballot and 0. K. Dolled in "Analytical Chemistry", volume 32, page 532, 1960. The term "macro pores" refers to the portion of the total pore volume which contains pores having a diameter greater than 600 Angstrom units, determined by a Mercury Penetration Pyres-meter 915-2, manufactured by Micromeritics Corporation, Georgia, U.S.A., using a 140 contact angle and a mercury surface tension of 474 dynes per centimeter at 25C. The term "total pore volume" of the catalyst as used in this specification refers to the sum of the mesopore volume and-the MicroPro volume as determined by the above methods.
The term "demetallization" refers to the elimination of 70% of the metals contained in heavy cruxes or residues, as effected by having petroleum hydrocarbons pass across a reaction SLY

zone containing the catalyst of the invention. The term "desulfurization" likewise refers to the elimination by the catalyst of 70% of the sulfur present in the heavy hydrocarbon crude by passage through the reaction zone.
In preparing the catalyst of the invention a refract tory oxide support is used and such support and the resulting catalyst have a total pore volume ranging between 0.5 and 1.2D, suitably 0.70 and 1.00 ml/gram (preferably about .9 ml/g); an average pore diameter varying between 150 and 300, suitably 200 to 300 Angstrom units (preferably 250 A) and a surface area varying from 120 to 400, suitably between 130 and 300 m2/gram (preferably 200 mug the particle size suitably varies in the range of 1/60 to 1/8 inch. Suitable support material is selected from the following refractory oxides: alumina, silica, magnesia, zircon, titanic and mixtures thereof, alone or impregnated with stabilizing materials. Alumina, silica and mixtures thereof represent preferred support materials.
The refractory oxide support having the above characteristics may be impregnated to deposit the catalytic gaily active metals. Various methods of impregnating active metals on a refractory oxide support are known in the art.
In general, they can be classed into successive impregnation methods, dry impregnation methods and co-impregna-lion methods.
In a successive impregnation method the support is first impregnated with one of the active principles and is then passed to a drying and/or calcination phase. The cycle Lowe is repeated or the second and subsequent active principles.
In carrying out a dry impregnation, an exact volume (retention volume of the refractory oxide) of active metal compound solution is added which will then be absorbed by the dry support.
Comprehension is carried out by placing the refract tory oxide or support in contact with a solution containing all the active metals of the catalyst. The impregnated catalyst then proceeds to the drying and/or calcination stages.
The present invention uses two stages of successive impregnation. An extruded refractory oxide, for example having the aforementioned specifications, is put into contact with, for example a solution of ammonium molybdate, ammonium pane-molybdate, molybdenum oxalate or molybdenum pentachloride, or with a soluble salt of the metal of another Group VIM metal. In order to obtain a composition of about 5 to 30%, suitably 5 to 20% by weight of molybdenum or other Group VIM metal on the support, determined as the oxide, the first impregnation stage should last for a time of about 4 hours at ambient temperature and moderate agitation. The pi of the impregnating solution is held constant with the addition of a buffer solution. At the end of the first impregnation period, the Group VIM metal solution is drained off and the moist impregnated catalyst is placed into a furnace with air circulation at 120C and at atmospheric pressure for 24 hours.
The refractory oxide support, for example alumina, impregnated with group VIM metal is then put into contact with

2~L3~3 an aqueous Group VIII metal solution, for example cobalt nitrate or nickel nitrate solution in order to obtain a concentration of 0.1 to 8%, suitably 1 to 5%, by weight of Group VIII metal, determined as oxide on the catalyst. The time of the second impregnation ranges from 2 to 3 hours. The catalyst is dried for 24 hours at a temperature of 120C, and calcined at 400 to 600C, especially 500C for a period from 1 to 24 hours. A
volume of dry air is circulated at a rate of 40 to 100, suitably 50 milliliters of air per hour per gram of catalyst during calcination.
Any element of Group VIM of the Periodic Table may be used for catalytic demetallization in the present invention.
Molybdenum and tungsten are preferably used in the form of oxides or sulfides in their final reactive form, preferably in quantities ranging from about 6 to about 25% by weight (as oxide with respect to the total weight of the catalyst. As species within Group VIII nickel and cobalt are preferred as sulfides in their ultimate form and preferably in quantities ranging between about 1 and 5% with respect to the total weight of the catalyst, calculated as oxide.
After impregnation and calcination the catalyst is optionally sulfide at a temperature in the range of 200 and 400C, at atmospheric pressure or at elevated pressures using elementary sulfur, sulfur compounds such as mercaptans or mixtures of hydrogen and hydrogen sulfide or mixtures thereof.
In order to determine the effectiveness of the present catalyst according to this invention in demetallizing ;353 and desulfurizing hydrocarbons-of petroleum origin, batches were used which have a high content in such metals as nickel, vanadium and iron. In the case of the present invention batches of Venezuelan heavy cruxes were used which generally contain 300 Pam of the aforementioned metal contaminants and 7 to 12% by weight of Conrad son carbon, and 5 to 10% by weight of asphaltenes; they contain between 3 and 5% by weight of sulfur. These heavy cruxes are subjected to a simultaneous demetallization and desulfurization, using the catalyst of the present invention in the presence of hydrogen at a temperature ranging between 360 and 415C, a pressure ranging between 600 and 3000 psi, a liquid hourly space velocity (LHSV) between 0.1 and 10 volumes per volume-hour and a hydrogen : feed ratio of from 2000 to 6000 standard cubic feet per barrel of feed (SCF/bbl).
The following examples are presented to more fully describe, but not to limit the invention.

Comparative tests were made, using a catalyst of the prior art and a catalyst according to the present invention.
The physical-chemical characteristics of the conventional catalyst (I) and of the novel catalyst of the invention (F) are summed up in Table I.

3~3 g TABLE I
PHYSICAL AND CHEMICAL PROPERTIES OF THE CATALYSTS

Properties CATALYST

. % Moo 14 5 8 1 coo 5.1 % No .98 % Aye REST REST
Surface Area, m gram 285 177 Total pore volume (ml/gram) O. 64 0.84 Average pore diameter ( A) 77 189 Bed resistance (kg/cm ) 10.3 1. 72 Particle size (inch) 1/16" 1/16"
Pore distribution (~) _ 20 - 30 A 2.8 0.0 30 - 60 A 40. 2 OWE
60 - 90 A 51.6 OKAY
90 - 150 A 6. 3 24.39 150 - 300 A 1.6 65.85 300 - 10 A 6.10 > 10 A 3.66 .

3~ii3 It can be seen from Table I that less than 10% of the pores had a diameter larger than 300 A
The verification of the catalytic activity of -the above catalysts for the demetallization and desulfurization of a Venezuelan Marshall crude which contains 338 Pam vanadium, 2.7% sulfur, 10.7% Conrad son carbon, 8.25% asphaltenes and has a APE gravity of 11.7, is demonstrated in Table II. A sample of this crude was put in contact with the aforementioned catalysts at a temperature of 400C, a pressure of 1500 psi, a liquid hourly space velocity (LHSV) of 1 hour and an Ho:
batch volumetric ratio of 800 Nm3. The results are shown in Table II, wherein % HODS and % HDV are percentage hydra-desulfurization and hydrodemetallization, respectively.
TABLE II
INITIAL CATALYST ACTIVITY

CATALYST HODS %HDV S=%HDS/%HDV

I 45.3 29.1 1.55 F 65.9 55.4 1.19 . .

A series of experiments measuring demetallizing and desulfurizing activity were conducted using different catalysts made according to the invention. The catalysts labeled A, B, C, D, E, F and G are set out in Table III. Prior to the activity test, all catalysts were presulfided in the described form.

~2~3~

In addition, similar tests were conducted for prior art catalyst I having the properties shown in Table I.
The experimental conditions and hydrocarbon feed stock used in these tests were the same as those of Example 1.
The results are graphically indicated in the accompany-in drawings in which:
FIG. 1 regroups the comparative tests of demetallizing constant (TV) and desulfurizing constant (Us) of the catalysts according to the present invention and of the (conventional) I
catalyst as a function of the total pore volume of the catalysts.
FIG. 2 shows a comparison of the effect of the pore size diameter of the catalysts on the demetallizing and desulfurizing constants (TV and Us).
With further reference to Fig. 1, it will be observed that the catalysts E, F and G, which each have a total pore volume of 0.8 to 0.9 ml/gram have significant simultaneous demetallizing and a desulfurizing activity. The catalysts B
and C, which have a pore volume greater than 1.0 ml/gram have a greater demetallizing activity than desulfurizing activity.
Finally, conventional catalyst I has a significant desulfuriz-in activity only.
With further reference to Fig. 2, the data show that in order for a catalyst to have significant simultaneous demetallization and desulfurization activity the average pore diameter for the catalyst should suitably range between 200 and 300 Angstrom units.

I
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_ _ _ _ _ _ __ __ _ _ _ __ _ _ _ _ co I Ox I o ox I I
Ox l I I ED I O I l l l D
(I U') Jo I I I N Irk O or) r I
_ _ _ _ __ __ _ _ _ _ _ _ _ _ ox I o I I Lo o so ox l a a it I Jo I l l l o Lo Lo O O O O . ED ED I
I I Lo_ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ED I D I I ox co o l a ox Lo O I l l l Lo Lo an Clue Lo CO O O O D O ED O
ED O N I
. _ __ _ _ _ _ _ __ _ _ _ _ _ _ _ _ 1- I ox I O N to I I
I if- us I Jo l I ox ox JO ox I o I' o O ox Lo ED
CC r I I I
Lo _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ O I. ED Jo d- ED Cal Lo ED to ED LO-) Lo ED l O I I I l I l 01 Cal I ox a:) Lo o C~J O o I C~J I coy ED C~J
l_ Jo I .
I _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ I ox r- D O o ox r- Lo I O In l O In O l O Lo O
at m o o u- o I a I I _ coy I: _ _ _ _ _ _ _ _ _ _ _ _ _ _ I Lo I Lo I
I an I I co I l I us ED I I I

cC _ N _ _ I O r O _ O _ _ _ O _ ox r I I
O I) I
J I< E E
o E u v I s c s E o I: E _ I, o o I o at: o o I: 0 ~13 o I o I
Jo V) .) o o o o o O Al ., ., a >, C Al C I) ED US In O O O
Z 2 a a N Jo a Jo .
cC >, 3 3 s E E I) Jo o on l l l l , A
.9 >, I on .,_ v) I: o Jo a v, or- O O O O O O
I: I a I a .,. a) ED a Lo o C Of I I) ox o o i- -a I) I: I o ., LO O a Al at o I _ a cc _ _ Jo _ _ _ For this example, catalysts F, G, E which showed simultaneous demetallizing and desulfurizing activity in Example 2, were modified so as to increase the active metal concentrations in order to show that the observed simultaneous effects were not due to low metallic contents. The molybdenum content was increased up to 15% by weight as Moo and the nickel content was increased to about 5% by weight.
Table IV shows that the ratio of demetallization to desulfurization activities did not change with the increase in active metal content of the catalyst.
TABLE IV
INFLUENCE OF THE METALLIC CONTENT
CATALYST Moe Noah S=%HDS/%HDV

F 5.8 .98 1.18 F-l 14.3 4.20 1.20 E 6.0 1.90 1.20 E-1 15.3 5.00 1.18 G 5.9 2.20 1.12 G-1 14.8 4.80 1.10 Catalysts E and F of Examples 1 and 2 were tested in order to study the relation between signal band strength ratio I as obtained by UPS and the demetallizing and desulfurizing activity of the catalysts on whole heavy crudest All catalysts were presulfurized in the manner described previously. The results obtained are shown in Table V.

i TABLE V
RELATION BETWEEN UPS RATIO AND HODS AND HDV
ACTIVITY OF THE CATALYSTS
Catalyst (Mo3d)/I(Al2p) HODS %HDV

E-l 9 70 68 From Table V it can be seen that there is a strong relation between simultaneous demetallization and desulfuriza-lion of heavy cruxes and the I(Mo3d)/I(Al2p) signal band strength ratio of the catalysts. Reduction of this signal band strength ratio is uniformly accompanied by a decrease in the HODS activity of the catalyst.

The catalysts F and E of Examples 1 and 2 and the conventional catalyst I, of the prior art, were tested in order to study their useful life time in demetallizing and desulfurizing a continuous feed of heavy crude. The export-mental conditions were as follows: T = 400C; hydrogen pressure 1500 psi; LHSV = 1 H 1 and H2:feed ratio = 1000 m3(5TP)m3. The results obtained are shown in Table V.

~%;~3~;3 TABLE VI
ACTIVITIES OVER USEFUL LIVES OF CATALYSTS

CATALYST % HODS HDV
Initial Final Initial Final 24 lyres 80 dyes hours 80 days (Conventional) 30 2' _ _ (Invention) 70 65 60 60 The results of the preceding Table clearly show the effectiveness of the catalyst of the present invention for the simultaneous and stable demetallization and desulfurization of heavy crude feeds or their derivatives which have high metal and sulfur contents.

The catalyst F of Example 1 and conventional catalyst I of Example 5 were tested in order to study their useful lives in demetallizing and desulurizing a continuous feed of O'er Negro Residual 350C+. The experimental conditions were as follows: T = 400C, hydrogen pressure = 1800 prig, LHSV = 1 and H2/Feed = 1000 Nm3/m3. The properties of Residual 350~C+
are summarized in Table VII

I -TABLE VII

CHARACTERISTICS OF RESIDUAL
_ 360C+ SYRIA NEGRO

Properties Residual 350C~
Syria Negro APT gravity 5.2 Viscosity Cyst, 140F 3500 Conrad son Carbon, % by Wt. 17.1 Asphaltenes, % by Wt. 12.1 Sulfur, % by Wt. 4.53 Nitrogen, Pam 7700 Vanadium, Pam 535 Table VIII shows the results obtained with catalysts F and I. Catalyst F shows a substantial increase in the HODS
and HDV catalytic activities over catalyst I. It may be seen that the new catalyst remains stable for more than 220 days, while catalyst I fails irreversibly after 70 operating days.
TABLE VIII

CATALYTIC ACTIVITIES OVER
USEFUL LIVES OF CATALYSTS
Catalysts % HODS % HDV
-24h 80 day 220 day 24h 80 day 220 day I

(Prior Art) 40 25 15 20 (Invention) 68 65 62 70 70 69 Without doubt, the newly developed catalyst is an attractive alternative to conventional catalysts when used for the hydra treatment of heavy cruxes and residues.

~22~;3 Thus the catalyst of the invention may particularly reemployed for the hydra treatment of a heavy hydrocarbon feed-stock containing high levels of nickel and vanadium contaminants sulfur and asphaltenes comprising contacting the heavy hydra-carbon feed stock with a catalyst of -the invention in a reactor at a temperature varying between 300 and 450C, a pressure varying between 600 and 3000 prig, a linear hourly space velocity varying from 0.05 to 5 (hours) 1, a H2:feed ratio ranging from 300 to 20,000 SCF/bbl and a partial hydrogen pressure of from 500 to 3000 prig.
In particular the hydrocarbon feed stock may contain more than 100 Pam nickel and vanadium contaminants, more than 2% sulfur and more than 8% asphaltenes.
In an especially preferred embodiment I(MeVIB)/I(re-factory metal) is 5 to 8.

Claims (35)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A process for the hydrotreatment of a heavy hydro-carbon feedstock containing high levels of nickel and vanadium contaminants, sulfur and asphaltenes comprising the steps of:
contacting said heavy hydrocarbon feedstock with a catalyst characterized by simultaneous demetallizing and desulfurizing activity wherein the ratio of percent of demetallizing to desulfurizing approaches unity over a useful life in excess of 80 days in a reactor at a temperature varying between 300 and 450°C, a pressure varying between 600 and 3000 psig, a linear hourly space velocity varying from 0.05 to 5 (hours)-1, a H2:feed ratio range from 300 to 20,000 SCF/bbl and a partial hydrogen pressure of from 500 to 3000 psig; said catalyst com-prising an alumina support material impregnated with a first compound consisting essentially of a metallic compound whose metallic component is selected from Group VIB of the Periodic Table, disposed on said alumina support material so as to comprise from 5 to 30% of the catalyst by weight, calculated as an oxide and a second compound consisting essentially of a metallic compound whose metallic component is selected from Group VIII of the Periodic Table, disposed on said support material so as to comprise from 0.1 to 8% of the catalyst by weight, calculated as an oxide; a total pore volume ranging from between 0.50 to 1.20 ml/g; and an average pore diameter of about between 200 to 300 .ANG..

2. A process according to claim 1, wherein said catalyst has signal band strength ratios, as determined by X-ray photo-electron spectroscopy, as follows: I(MeVIB)/I(refractory metal) is between 5 and 13 and I(MeVIII)/I(refractory metal) is between 1 and 5, wherein MeVIB is said Group VIB metallic component, MeVIII is said Group VIII metallic component and 'refractory metal' is aluminium.

3. A process according to claim 1, wherein said catalyst has a pore size distribution such that less than 10% of the pores of the catalyst are larger than 300 .ANG. in diameter.

4. A process according to claim 2, wherein said catalyst has a pore size distribution such that less than 10% of the pores of the catalyst are larger than 300 .ANG. in diameter.

5. A process according to claim 1 or 3, wherein said total pore volume ranges from about 0.7 to 1.0 ml/g.

6. A process according to claim 2 or 4, wherein said total pore volume ranges from about 0.7 to 1.0 ml/g.

7. A particulate catalyst characterized by simultaneous demetallization and desulfurization activity in a feedstock con-taining nickel and vanadium, sulfur and asphaltenes wherein the ratio of percent of demetallization to desulfurization approaches unity over a useful life in excess of 80 days, said catalyst having the following physical and chemical properties: a total pore volume ranging from about 0.5 to 1.2 ml/g, and an average pore diameter of about 150 to 300 .ANG., said catalyst comprising a support material impregnated with a metallic component of Group VIB of the Periodic Table in an amount of about 5 to 30% of the catalyst by weight, calculated as an oxide of said Group VIB
metallic component, and an metallic component from Group VIII
of the Periodic Table in an amount of about 0.1 to 8% of the catalyst by weight, calculated as an oxide of said Group VIII
metallic component.

8. The catalyst of claim 7, wherein said support material comprises an extruded refractory oxide support.

9. The catalyst of claim 8, wherein said refractory oxide is alumina.

10. The catalyst of claim 7, 8 or 9, wherein said total pore volume ranges from about 0.7 to 1.0 ml/g.

11. The catalyst of claim 7, 8 or 9, having a pore size distribution such that less than 10% of the pores of the catalyst are larger than 300 .ANG. in diameter.

12. The catalyst of claim 7, 8 or 9, having signal band strength ratios, as determined by X-ray photoelectron spectro-scopy, as follows: I(MeVIB)/I(refractory metal) is between 5 and 13 and I(MeVIII)/I(refractory metal) is between 1 and 5, wherein MeVIB is said Group VIB metallic component, MeVIII is said Group VIII metallic component and 'refractory metal' is aluminium.

13. The catalyst of claim 7, 8 or 9, having a pore size distribution such that less than 10% of the pores of the catalyst are larger than 300 .ANG. in diameter; and signal band strength ratios, as determined by X-ray photoelectron spectroscopy, as follows: I(MeVIB)/I(refractory metal) is between 5 and 13 and I(MeVIII)/I(refractory metal) is between 1 and 5, wherein MeVIB is said Group VIB metallic component, MeVIII is said Group VIII metallic component and 'refractory metal' is aluminium.

14. The catalyst of claim 7, 8 or 9, wherein said total pore volume ranges from about 0.7 to 1.0 ml/g, said catalyst having signal band strength ratios, as determined by X-ray photoelectron spectroscopy, as follows: I(MeVIB)/I(refractory metal) is between 5 and 13 and I(MeVIII)/I(refractory metal) is between 1 and 5, wherein MeVIB is said Group VIB metallic component, MeVIII is said Group VIII metallic component and 'refractory metal' is aluminium, and having a pore size dis-tribution such that less than 10% of the pores of the catalyst are larger than 300 .ANG. in diameter.

15. The catalyst of claim 7, 8 or 9, wherein said metallic component of Group VIB comprises a metal selected from the group consisting of molybdenum, tungsten and mixtures thereof.

16. The catalyst of claim 7, 8 or 9, wherein said metallic component of Group VIII comprises a metal selected from the group consisting of cobalt, iron, nickel and mixtures thereof.

17. The catalyst of claim 7, 8 or 9, wherein the metallic component of Group VIB comprises from about 6 to 25% by weight of the catalyst, calculated as oxide.

18. The catalyst of claim 7, 8 or 9, wherein the metallic component of Group VIII comprises about 1 to 5% by weight of the catalyst, calculated as oxide.

19. The catalyst of claim 7, 8 or 9, having a total sur-face area of 120 to 400 m2/g.

20. The catalyst of claim 7, 8 or 9, wherein said average pore diameter is about 200 to 300 .ANG..

21. The catalyst of claim 7, 8 or 9, having a total sur-face area of 120 to 400m2/g, said average pore diameter being about 200 to 300 .ANG..

22. A method for making a catalyst having hydrodemetalliza-tion and hydrodesulfurization activity in a feedstock containing nickel and vanadium, sulfur and asphaltenes which comprises the steps of:
providing an alumina support having a total pore volume of about 0.7 to about 1 milliliters/gram; an average pore diameter of about 150 to about 300 Angstrom units, a surface area of about 130 to about 300 m2/gram; and a particle size of about 1/60 to about 1/8 inch;
impregnating the alumina support with a first metallic compound having a first metallic component selected from Group VIB of the Periodic Table so as to obtain a catalyst composition containing 5 to 30% by weight of said first metallic component, calculated as an oxide;
drying the impregnated alumina support;
impregnating the dried alumina support with a second metallic compound having a second metallic component selected from Group VIII of the Periodic Table so as to obtain a catalyst composition containing 0.1 to 8% by weight of said second metallic component, calculated as an oxide;
drying the thus impregnated support; and calcining the dried impregnated alumina support at a temperature of about 400 to 600°C whereby a catalyst is obtained which is characterized by simultaneous demetallization and desulfurization approaching unity over a useful life in excess of 80 days.

23. The method of claim 22, wherein said alumina support is an extruded support.

24. The method of claim 22, wherein the first metallic component is selected from the group consisting of molybdenum, tungsten and mixtures thereof.

25. The method of claim 22 or 24, wherein the second metallic component is selected from the group consisting of nickel, iron, cobalt and mixture thereof.

26. The method of claim 22, further comprising a step of sulfurizing the calcined support.

27. The method of claim 26, wherein said calcined support is sulfurized at a temperature of between 200 and 400°C, using a sulfur material selected from the group consisting of elemental sulfur, mercaptans, hydrogen sulfide and mixtures thereof, whereby a sulfided catalyst is obtained.

28. The method of claim 22, wherein the catalyst has a total pore volume ranging from about 0.5 to 1.2 ml/g and an average pore diameter of about 150 to 300 .ANG..

29. The method of claim 28, wherein the catalyst has a pore size distribution such that less than 10% of the pores of the catalyst are larger than 300 .ANG..

30. The method of claim 28 or 29, wherein said catalyst has signal band strength ratios, as determined by X-ray photo-electron spectroscopy, as follows: I(MeVIB)/I(refractory metal) is between 5 and 13 and I(MeVIII)/I(refractory metal) is between 1 and 5, wherein MeVIB is said Group VIB metallic component, MeVIII is said Group VIII metallic component and 'refractory metal' is aluminium.

31. A process according to claim 1, wherein the average pore diameter is about 240 to 280 .ANG..

32. A process according to claim 2 or 4, wherein I(MeVIB)/
I(refractory metal) is 5 to 8.

33. The catalyst of claim 7, 8 or 9 having signal band strength ratios, as determined by X-ray photoelectron spectro-scopy, as follows: I(MeVIB)/I(refractory metal) is 5 to 8 and I(MeVIII)/I(refractory metal) is 1 to 5, wherein MeVIB is said Group VIB metallic component, MeVIII is said Group VIII metallic component and 'refractory metal' is aluminium.

34. The catalyst of claim 7, 8 or 9 having a pore size distribution such that less than 10% of the pores of the catalyst are larger than 300 .ANG. in diameter; and signal band strength ratios, as determined by X-ray photoelectron spectro-scopy, as follows: I(MeVIB)/I(refractory metal) is 5 to 8 and I(MeVIII)/I(refractory metal)is 1 to 5, wherein MeVIB is said Group VIB metallic component, MeVIII is said Group VIII metallic component and 'refractory metal' is aluminium.

35. The catalyst of claim 7, 8 or 9, wherein said total pore volume ranges from about 0.7 to 1.0 ml/g, said catalyst having signal band strength ratios, as determined by X-ray photoelectron spectroscopy, as follows: I(MeVIB)/I(refractory metal) is 5 to 8 and I(MeVIII)/I(refractory metal) is 1 to 5, wherein MeVIB is said Group VIB metallic component, MeVIII is said Group VIII metallic component and 'refractory metal' is aluminium, and having a pore size distribution such that less than 10% of the pores of the catalyst are larger than 300 .ANG. in diameter.