WO2002032570A2

WO2002032570A2 - Hydrodemetallation catalyst and method for making same

Info

Publication number: WO2002032570A2
Application number: PCT/US2001/032432
Authority: WO
Inventors: Opinder Kishan Bhan
Original assignee: Shell Internationale Research Maatschappij B.V.
Priority date: 2000-10-19
Filing date: 2001-10-16
Publication date: 2002-04-25
Also published as: AR030905A1; WO2002032570A3; AU2002215374A1

Abstract

A catalyst for hydrodemetallation of a heavy hydrocarbon stream comprising particles of alumina support having a bimodal pore size distribution and catalytically active amounts of metal from Group VIB distributed uniformly throughout and on the surface of the particles, wherein at least 20 % of the total volume of pores contained in said catalyst is in pores having a pore diameter of at least 1000 Å and wherein at least 50 % of the total volume of pores contained in said catalyst is in pores having a pore diameter of no greater than 350 Å. A method of making such catalyst and a process for removing metals from a heavy hydrocarbon stream using said catalyst.

Description

HYDRODEMETALLATION CATALYST AND METHOD FOR

MAKING SAME

Technical Field

This invention relates to a catalyst for removal of metals from heavy hydrocarbon oils and fractions and a method of making such catalyst.

Background Art

Petroleum feedstocks are characterized by relatively high levels of contaminants, including sulfur, nitrogen, Conradson carbon residue, aromatic compounds and metals such as nickel, vanadium and iron. During catalytic hydroprocessing heterogeneous catalysts are contacted with a feedstock in the presence of hydrogen under conditions of elevated temperature and pressure to reduce the concentration of the contaminants in feedstocks. The hydrotreating process promotes reactions such as hydrodesulfurization (HDS), hydrodenitrogenation (HDN), Conradson carbon removal, hydrodemetallation (HD ) and aromatics saturation, accompanied by a conversion to lower boiling products. As the sulfur and nitrogen components are converted into hydrogen sulfide and ammonia, metals are deposited onto the catalyst as metal sulfides. The most significant problem encountered in hydroprocessing of heavy oils containing high concentrations of metals results from this deposition of metal sulfides on the catalyst. As metal sulfides are deposited on the catalyst, they poison or occlude catalytic metal sites which are predominately located in the catalyst pores, leading to rapid deactivation of the catalyst. To date, a catalyst that is effective at removing metals and which maintains its effectiveness over long periods of use has not been available.

Some researchers have taught catalysts based on a support having a bimodal pore size distribution. For example, Japanese patent application JP 1 1 128744 teaches a catalyst preparation method where molybdenum is impregnated on a γ-alumina support having a bimodal pore structure in such a way that a concentration gradient exists between the molybdenum on the particle surface and internally. Other researchers have taught catalysts that appear to be directed at fulfilling the need for a catalyst that is effective at promoting hydrodemetallation.

For example, U.S. Patent No. 5,002,919 (Yamazaki, et al.) teaches a catalyst comprising a support having a unimodal pore size distribution on which a metal that promotes hydrogenation has been deposited. U.S. Patent No. 5,322,829 (Artes, et al ) also teaches a catalyst comprising a support having a unimodal pore size distribution on which Group IVB and Group VIII metals have been deposited. Disclosure of the Invention

It has been found that a catalyst having a bimodal pore structure prepared by mixing alumina with fines produced by crushing commercial hydroprocessing or hydrocracking catalyst comprising at least 20 wt.% alumina and metal from Group VIB of the Periodic Table and, optionally, a Group VIII metal and/or phosphorus followed by mulling with water and, optionally, an acid, extruding, drying and calcining at the proper temperature is highly effective at removing metals from heavy oil fractions and maintains its effectiveness for much longer periods than catalysts presently available.

The present invention provides for such a catalyst comprising a support comprising alumina having a bimodal pore size distribution, a catalytically active amount of metal from Group VIB of the Periodic Table and, optionally, a metal from Group VI II and/or phosphorus distributed uniformly throughout the catalyst particle as well as on its surface. This catalyst has been found to be particularly effective at removing metals from heavy oil fractions containing high concentrations of nickel and vanadium while exhibiting good stability, i.e.. the ability to exhibit activity equivalent to or close to its initial activity, even when the amount of metals removed (i.e., deposited on the catalyst) is nearly equivalent to the weight of fresh catalyst.

The present invention also provides for a process for manufacturing such catalyst comprising: 1) mixing between 60 % and 90 % alumina powder with the balance fines derived from crushing catalyst comprising alumina, metal from Group

VIB of the Periodic Table and, optionally, metal from Group VIII and/or phosphorous, in sufficient quantity that the resultant mixture contains desired concentrations of active metals; b) mulling the mixture with water or an aqueous solution of acid; and c) drying, extruding and then calcining the product of (b) at moderate calcining temperatures between about 400°C and about 790°C. Finally, the present invention provides for a catalyst made by the process of the present invention and for a process for removing metals from a heavy oil fraction comprising contacting such heavy oil fraction with the catalyst of the present invention in the presence of hydrogen at elevated temperature and pressure. Brief Description of the Drawings

Figure 1. shows the reaction rate constant at two operating temperatures,

370°C and 395°C. versus weight percentage of vanadium deposited, calculated on a fresh catalyst weight basis for removal of vanadium from whole Boscan crude by the catalyst of the present invention in a hydrotreating process as compared to that of a commercial hydrodemetallation catalyst.

Figure 2. shows the reaction rate constant at two operating temperatures,

370°C and 400°C, versus weight percentage of vanadium deposited, calculated on a fresh catalyst weight basis for removal of vanadium from Bachaquero long residuum by the catalyst of the present invention in a hydrotreating process as compared to that of a commercial hydrodemetallation catalyst.

Figure 3. shows the reaction rate constant at two operating temperatures, 370°C and 395°C, versus weight percentage of vanadium deposited, calculated on a fresh catalyst weight basis for removal of vanadium from whole Boscan crude by the catalyst of the present invention in a hydrotreating process as compared to that of catalysts prepared in a similar manner but calcined at higher and lower temperatures.

Figure 4. shows the concentration of molybdenum across the cross section of a conventional catalyst particle.

Figure 5. shows the concentration of molybdenum across the cross section of a catalyst particle of the present invention. Figure 6. is a TEM photograph of the surface of a catalyst particle of the present invention.

Figure 7. is a TEM photograph of the surface of a catalyst particle prepared following the procedure of the present invention but calcined at 815°C. Figure 8. is a TEM photograph of the surface of a commercial catalyst particle calcined at 815°C.

Figure 9. shows the reaction rate constant at 370°C, 385°C and 400°C versus weight percentage of vanadium deposited, calculated on a fresh catalyst weight basis for removal of vanadium from Heavy Arabian long residuum by Catalysts D, E and F. Figure 10. shows the reaction rate constant at two operating temperatures,

370°C and 400°C, versus weight percentage of vanadium deposited, calculated on a fresh catalyst weight basis for removal of vanadium from Bachaquero long residuum by the catalyst of the present invention in a hydrotreating process as compared to that of a commercial hydrodemetallation catalyst and Catalyst F. Detailed Description of the Invention Catalyst

The catalyst of the present invention comprises an alumina support having a bimodal pore size distribution, a uniform distribution across the catalyst cross- section of a catalytically active amount of metal from Group VIB of the Periodic Table Group and optionally, a metal from Group VIII and/or phosphorus. Support

The alumina support should have a bimodal pore size distribution, which is accomplished by mixing alumina powder and fines from crushed hydrotreating or hydrocracking catalyst. This bimodal distribution provides a) a sufficient number of macropores, i.e., pores of at least 1000 A in diameter, to allow large macro-molecular species in the hydrocarbon fraction (such as asphaltenes) that contain the bulk of the metals and organic metal complexes to enter the catalyst interior and to provide sufficient pore volume for effective deposition of metals without blocking the pore mouths; and b) a sufficiently high concentration of micropores, i.e., pores no larger than 350 Λ in diameter, to maintain high surface area, where sulfur-containing molecules are converted to H₂S. At least 50 % of the pores should be micropores, preferably at least 60 % and at least 20 % should be macropores, preferably at least 30 %. Gamma phase alumina is preferred for the support. Pore volume distribution is determined by mercury intrusion at high pressures. The total pore volume of the support should be between 0.6 and 1.2 cc/g. The support surface area should be between about 80 m /g and about 350

2/ m /g.

Although the presence of alumina in the support is essential, supports comprising zeolites and other inorganic oxides, such as alumina-silica, alumina- boria, alumina-titania, and alumina-magnesia, may be used so long as the percentage of alumina in the support comprises at least 64 wt. % of the support material.

Catalytic Metal

A critical element of the present invention is the even distribution of a catalytically active amount of a Group VIB metal throughout each catalyst particle. Catalyst prepared by conventional methods, such as by impregnating a support with a solution containing the desired metal followed by drying and calcining, invariably exhibits a gradient in the concentration of metal across the catalyst particle's cross section. A typical concentration gradient for a conventionally prepared catalyst is shown in Figure 4 for molybdenum. This scan, showing "PP as a function of location on the particle diameter ("Point") illustrates the decrease in Mo concentration from the particle surface towards the particle's interior. "PI" is defined as the actual amount of metal loading present on catalyst at time "t" divided by the maximum amount of deposition that is possible in the absence of any diffusion restrictions and infinite time. The PI for this particle is 0.69. In contrast. Figure 5 shows the concentration profile for Mo across the cross section of a catalyst particle of the present invention. Figure 5 illustrates that the concentration of Mo is almost uniform throughout the catalyst particle, having a PI of 0.987. Catalyst of the present invention should have a PI for the Group VIB metal of at least about 0.8, preferably at least about 0.9. Suitable metals from Group VIB are tungsten and molybdenum in an amount such that the Group VIB metal represents between about 0.5 wt.% and about 10 wt. % of the finished catalyst. Between about 2 wt. % and about 6 wt.% of molybdenum is preferred. If present, any of the metals from Group VIII are acceptable, with cobalt and nickel being preferred.

Phosphorus aids hydrogenation. Its presence in the finished catalyst is also optional and largely depends on whether the catalyst that is crushed to make fines contains it. When present, phosphorus increases the hydrogenation activity of the catalyst while reducing the metals-removal activity. If present, the amount of phosphorus should be between about 0.1 wt. % and about 2 wt.% of the finished catalyst.

Catalyst Preparation The catalyst of the present invention may be prepared by crushing commercial hydroprocessing or hydrocracking catalyst comprising alumina- containing supports comprising alumina, zeolites or other inorganic oxides, such as alumina-silica, alumina-boria, alumina-titania, and alumina-magnesia impregnated with a Group VIB metal and, optionally, a Group VIII metal and/or phosphorus to yield catalyst fines having a particle size distribution such that the median particle diameter is between about 2 μm and about 50 μm, preferably between about 5 μm and about 15 μm. If the median particle size of the fines is too large, i.e., above about 100 μm, catalyst strength and activity will be impaired. Suitable metals concentrations in the fines are between about 2 wt. % and about 20 wt. % of Group VIB metal, preferably molybdenum, up to about 10 wt. % Group VIII metal and up to about 4 wt. % phosphorus. Alternatively, fines produced during the manufacture of a commercial catalyst may be collected and milled to produce the recommended median particle size.

The catalyst fines are then mixed with alumina powder in a ratio such that the alumina powder comprises between about 60 wt.% and 90 wt.% of the mixture, preferably between about 70 wt.% and 80 wt.%. The proportion of fines is determined by the concentration of metals in the commercial catalyst used to produce the fines, the metals loading desired in the finished catalyst and the pore size distribution desired in the finished catalyst. The mixture is then mulled with water or, preferably, an aqueous acid solution by techniques well known to those skilled in the art. Any inorganic acid. except phosphoric acid which should be avoided, or organic acid, such as acetic or lactic is suitable, with nitric acid being preferred. The aqueous acid solution should contain no more than about 6 % acid, with acid concentrations between about 0.2 % and about 2 % being preferred.

Following mulling, the mixture is formed into catalyst particles of the desired shape and size. Extrusion of the mixture is preferred. The catalyst particles are then dried and calcined by methods known to those skilled in the art. During calcination, the metals originally contained in the catalyst fines migrate to the remaining alumina, dispersing uniformly throughout the entire particle surface. The temperature at which calcination is performed is important, however. If the catalyst particles are calcined at too low a temperature, below about 370°C, the metals will not properly disperse. If, however, the calcination temperature is above about 790°C, alumina changes phase resulting in drastically reduced surface area and very wide pores, thereby dramatically reducing catalyst strength and catalyst activity. Therefore, calcination temperatures between about 540°C and 730°C are preferred, and temperatures between about 650°C and 705°C particularly preferred.

The importance of proper calcination temperature cannot be overemphasized. In commercial practice, calcination is accomplished by transporting the catalyst particles through a kiln wherein the particles are exposed to increasingly higher temperatures as they progress. Normally, this procedure will expose the particles to low temperatures initially (about 425°C) and progressively to temperatures that, at the outlet of the oven, reach up to 900°C. The preferred calcination temperature (650°C to 705°C) referred to above is meant to apply to the temperature to which the catalyst particles are exposed "on average". Particular care must be taken to insure that the catalyst particles, while being exposed to temperatures during calcination within the range described above, spend as little time as practical at temperatures above 790°C. The importance of this practice is illustrated by reference to Figures 6 -8. Figure 6 is a photograph of a section of the surface of a catalyst particle at an enlargement of 47,600 taken by Transmission Electron Microscopy (TEM). This photograph shows a very finely grained surface with no distinguishable crystals of alumina. In contrast. Figure 7 shows a photograph (taken under the same conditions) of catalyst made by the procedure of the present invention that has been calcined at a temperature of 815°C. In this photograph, easily distinguishable crystals of alumina with metal can be discerned, indicating that the alumina in the presence of metals has experienced a phase transformation, thereby producing a mediocre catalyst. For comparison, Figure 8 shows the surface of a conventionally prepared catalyst of the same nominal composition calcined at 815°C. No noticeable phase transformation has occurred.

Process for Removing Metals from Heavy Hydrocarbon Fractions Hydrodemetallation of heavy hydrocarbon fractions may be achieved by contacting such feed with the catalyst of the present invention in the presence of hydrogen at elevated temperature and pressure. The preferred operating conditions are between about 6,996 kPa (1 ,000 psig) and about 20,786 kPa (3,000 psig), between about 315°C and about 455°C, a hydrogen treat gas rate between about 178.1 and 1 ,781 m³ per m³ (1,000 and 10,000 SCF per bairel) of feed and sufficient catalyst to result in a liquid hourly space velocity (LHSV) of between about 0.1 hr^"1 and about 2 hr^"1. It is preferred that the catalyst of the present invention be employed in the lead or first bed of a multi-bed system to permit removal of metals by a catalyst that is particularly well-adapted for such, thereby permitting the use of another catalyst less resistant to rapid deactivation from metals contamination in subsequent beds.

Examples:

Example 1

This example describes the preparation of a catalyst of the present invention and the characteristics of such catalyst. A mixture comprising 70 wt.% alumina powder and 30 wt.% fines from crushed commercial hydroprocessing catalyst was prepared. The mixture was mulled in a 1 % aqueous solution of nitric acid for 35 minutes, extruded into 1.2 mm trilobe cylinders, dried at 100°C (212°F) for 3 hours and calcined at 677°C for 2 hours. Analysis of the resulting catalyst, designated Catalyst A, showed it to have the following metals concentrations uniformly distributed throughout the catalyst and pore size distribution determined by Hg intrusion under pressure: Metals: wt. % Ni: 0.96 wt. % Mo: 5.4 wt. % P: 0.48

Pore Volume Distribution:

Total Pore Volume, cc/g 0.97 Median Pore Diameter, A 124.8

% Pore Volume in Pores having diameters: less than 70 A 4.4

70-100 A 24.7 100-130 A 22.4

130-150 A 4.7

150-180 A 3.2

180-200 A 1.3

200-240 A 1.6 240-300 A 1.4

300-350 A 0.7

350-450 A 1.0

450-600 A 0.8

600-1000 A 1.4 1000-3000 A 5.1

3000-5000 A 5.3 greater than 5000 A 21.6 Example 2

This example compares the performance of catalyst of the present invention to that of a commercial hydrometallation catalyst when used to treat whole Boscan crude.

The performance of Catalyst A from Example 1 was compared to that of a commercial hydrometallation catalyst comprising an alumina support impregnated with 4 wt. % Mo. Each catalyst was used to treat whole Boscan crude oil containing 5.3 wt.% S, 1 1 1 wppm Ni and 1360 wppm V at 370°C and at 395°C at a liquid hourly space velocity (LHSV) of 0.5 h ^"'. The results of these tests are shown as graphs of the reaction rate constants for conversion of vanadium versus weight percentage of vanadium deposited, calculated on afresh catalyst weight basis, on Figure 1. Vanadium removal proceeds at 1.5 order of reaction. The reaction rate constant is defined as: k_v = LHSV F 1 - 1 1

0.5 V_n v, J where V₀ = the square root of the vanadium concentration leaving the reactor, and

V; = the square root of the vanadium concentration entering the reactor.

Figure 1 shows that Catalyst A exhibits much higher activity for removal of vanadium at the normal hydrotreating temperature of 395°C than the conventional catalyst and equivalent activity at a lower operating temperature of 370°C. Figure 1 also shows that this improvement in performance increases as run length increases, indicating that Catalyst A not only has a higher activity for removal of vanadium but also is more stable. Example 3

This example compares the performance of catalyst of the present invention to that of a commercial hydrometallation catalyst when used to treat Bachaquero long residuum.

The performance of Catalyst A from Example 1 was compared to that of a commercial hydrometallation catalyst comprising an alumina support impregnated with 4 wt. % Mo. Each catalyst was used to treat Bachaquero long residuum (nominal cut point = 343 °C) containing 3.3 wt.% S, 34 wppm Ni and 262 wppm V at 370°C and at 400°C at a liquid hourly space velocity (LHSV) of 0.5 h ^"'. The results of these tests are shown as graphs of the reaction rate constants for conversion of vanadium versus weight percentage of vanadium deposited, calculated on a fresh catalyst weight basis, on Figure 2. These tests illustrate the same phenomena as in Example 2; that is, superior performance at 400°C and equivalent performance at 370°C, and more stable operation.

Example 4

(Comparative)

This example illustrates the importance of calcining the catalyst of the present invention at the proper temperature.

Catalysts B and C were prepared following the same procedure described in Example 1 except that Catalyst B was calcined at 732°C and Catalyst C at

538°C. The performances of Catalysts A, B and C in treating the same Boscan crude and same process conditions as used in Example 2 were determined, and the results are shown in Figure 3. Figure 3 shows that at an operating temperature of 395°C, Catalyst A exhibits a superior capability to catalyze the removal of vanadium to that demonstrated by either Catalyst B or C. i Example 5

(Comparative)

This example describes the preparation of a catalyst impregnated with 2.3 wt.%) Ni and 4 wt.% Mo.

) An aqueous solution comprising 12.5 g of Ni(N0₃)2-6H₂0, 4.85 g of NH )₂Mθ₂θ₇, 2.48 g M0O₃ in deionized water was prepared and used to impregnate a support comprising wide pore alumina. The impregnated support was then dried for several hours at 125°C and calcined at 482°C for 2 hours. The resulting catalyst, designated Catalyst D, contained 2.3 wt.% Ni and 4.0 wt. % i Mo and had a pore volume distribution as follows:

Total Pore Volume, cc/g 0.8382

Median Pore Diameter, A 162.0 % Pore Volume in Pores having diameters: less than 70 A 2.1

70-100 A 2.8

100-130 A 12.7

130-150 A 19.5 150-170 A 20.4

170-210 A 25.2

210-350 A 1 1.5

350-650 A 2.9

650-3000 A 2.3 greater than 3000 A 0.5

Example 6

(Comparative) This example describes the preparation of a catalyst impregnated with 4 wt.% Mo.

An aqueous solution comprising 4.70 g of (NH₄)₂Mo₂O , 2.40 g M0O₃ in deionized water was prepared and used to impregnate a support comprising wide pore alumina. The impregnated support was then dried and calcined as in Example 5. The resulting catalyst, designated Catalyst E, contained 4.0 wt. % Mo and had a pore volume distribution as follows:

Total Pore Volume, cc/g 0.8568

Median Pore Diameter, A 193.5

% Pore Volume in Pores having diameters: less than 70 A 1.1

70-100 A 1.0

100-130 A 3.6

130-150 A 6.8

150-170 A 14.6

170-210 A 36.01

210-350 A 25.7

350-650 A 5.4

650-3000 A 4.2 greater than 3000 A 1.5

Example 7

(Comparative) This example describes the preparation of a catalyst prepared by comulling ammonium dimolybdate with alumina containing 4 wt.%> Mo.

An aqueous solution comprising 225.5 g of

in 196.91 g deionized water and 35.52 g H₂O was prepared. A solution containing 180.0 g of glacial acetic acid and 95.0 g of deionized water was prepared. 3,992.55 g of γ-alumina were added to a muller. With the muller running, the Mo solution was added and mulled for 3 minutes. Then the acid solution and 3,952.1 g of deionized water was added and mulled for 55 minutes. A portion of the mulled material was extruded into 1/20 inch trilobe extrudates, dried for several hours at 125DC and calcined at 732DC for 2 hours. The resulting catalyst, designated Catalyst F, contained 4.0 wt. % Mo and had a pore volume distribution as follows:

Total Pore Volume, cc/g 0.874

Median Pore Diameter, A 140.0 % Pore Volume in Pores having diameters: less than 70 A 1.5

70-100 A 5.3

100-130 A 30.5 130-150 A 21.7

150-170 A 10.8

170-210 A 10.4

210-350 A 1 1.2

350-650 A 4.5 650-3000 A 2.6 greater than 3000 A 1.5

Example 8 (Comparative) This example compares the performance of Catalysts D, E and F from

Examples 5, 6 and 7 in treating Fleavy Arabian Long Residuum.

Each catalyst was used to treat Heavy Arabian Long Residuum (nominal cut point = 343°C) containing 4.42 wt.% S, 31 wppm Ni and 106 wppm V at 370°C, 385°C and 400°C at a liquid hourly space velocity (LHSV) of 0.5 h ^"'. Temperature was held at 370°C for 600 hours, followed by 600 hours at 385°C and 400 hours at 400°C. The results of these tests are shown as graphs of the reaction rate constants for conversion of vanadium versus weight percentage of vanadium deposited, calculated on a fresh catalyst weight basis, on Figure 9. The data on Figure 9 show that: 1) the addition of Ni to the Mo in the impregnated catalyst (i.e..

Catalyst D) provided inferior vanadium removal activity compared to Catalyst E (i.e., without Ni). This was particularly true at the high operating temperature of 400°C, at which Catalyst D deactivated more quickly than Catalyst E; and 2) Catalyst E provided superior vanadium removal activity at all temperatures relative to Catalyst F, showing that simple co- mulling of Mo with alumina produces a less effective catalyst than the catalyst of the present invention. Example 9

(Comparative) This example compares the performance of Catalysts A, F and a commercial HDM catalyst containing 4 wt.% Mo in treating Bachaquero long residuum. Each catalyst was used to treat Bachaquero long residuum as in Example

3 at 370°C and 400°C at a liquid hourly space velocity (LHSV) of 0.5 h ^"'. Temperature was held at 370°C for 600 hours, followed by 1400 hours at 400°C. The results of these tests are shown as graphs of the reaction rate constants for conversion of vanadium versus weight percentage of vanadium deposited, calculated on a fresh catalyst weight basis, on Figure 10. The data on Figure 10 show that Catalyst A is far more effective at removing vanadium than either Catalyst F or the Commercial HDM catalyst.

It will be apparent to one of ordinary skill in the art that many changes and modifications may be made to the invention without departing from its spirit or scope as set forth herein.

Claims

1. A catalyst for hydrodemetallation of a heavy hydrocarbon stream comprising particles of alumina support having a bimodal pore size distribution and between about 0.5 wt. % and about 10 wt. % of a metal selected from tungsten and molybdenum distributed uniformly tliroughout and on the surface of the particles in such a way that the PI is at least 0.8, wherein at least 20 % of the total volume of pores contained in said catalyst is in pores having a pore diameter of at least 1000 A and wherein at least 50 % of the total volume of pores contained in said catalyst is in pores having a pore diameter of no greater than 350 A.

2. The catalyst of Claim 1 wherein the metal is molybdenum.

3. The catalyst of Claim 1 wherein the metal is Mo and the amount of Mo in the catalyst is between about 2 wt. % and about 10 wt.%.

4. The catalyst of Claim 1 wherein the particles of catalyst are extrudates having a diameter between about 0.7 mm and about 10 mm.

5. The catalyst of Claim 1 further comprising a catalytically active amount of metal selected from Group VIII of the Periodic Table.

6. The catalyst of Claim 1 further comprising a catalytically active amount of a metal selected from Group VIII of the Periodic Table and phosphorus.

7. A method of making a hydrodemetallation catalyst comprising: a) mixing an amount of γ-alumina powder with a lesser amount of fines derived from crushing catalyst comprising alumina and a metal selected from molybdenum and tungsten; b) mulling the mixture with an aqueous solution of inorganic acid; and c) drying, extruding and then calcining the product of (b) at a calcining temperature between about 400°C and about 787°C.

8. The method of Claim 7 wherein the calcining temperature is between about 620°C and about 732°C.

9. The method of Claim 7 wherein said amount of fines is between about 10 wt. % and about 40 wt. % of the catalyst.

10. The method of Claim 7 wherein said amount of fines is between about 20 wt. % and about 30 wt. % of the catalyst.

11. The method of Claim 7 wherein the metal is molybdenum.

12. The method of Claim 7 wherein amount of metal in the catalyst is between about 0.5 wt.% and about 10 wt.%.

13. The method of Claim 7 wherein the fines derived from crushing catalyst further comprise a metal from Group VIII and, optionally, phosphorus.

14. The method of Claim 7 wherein the amount of fines is such that at least 20 % of the total volume of pores contained in said catalyst is in pores having a pore diameter of at least 1000 A and the amount of alumina powder is such that at least 50 % of the total volume of pores contained in said catalyst is in pores having a pore diameter no greater than 350 A.

15. The method of Claim 7 wherein the aqueous solution of inorganic acid comprises between about a 0.2 wt. % and 3 wt.% acid.

16. The method of Claim 7 wherein the aqueous solution of inorganic acid comprises between about a 0.2 wt. % and 2 wt.% nitric acid.

17. The method of Claim 7 wherein said extruding produces particles having a diameter between about 0.7 mm and about 10 mm.

18. A process for removing metals from a heavy hydrocarbon fraction comprising contacting the fraction with the catalyst of Claim 1 at elevated temperature and elevated pressure in the presence of hydrogen.

19. The process of Claim 18 wherein said contacting is done in a plurality of fixed catalyst beds and the catalyst of Claim 1 is installed in the first of said beds.

20. A catalyst for removing metals from a heavy hydrocarbon fraction made by the method of Claim 7.