GB1584706A - Hydrotreating catalyst and process utilizing the same - Google Patents

Description

(54) HYDROTREATING CATALYST AND PROCESS UTILIZING THE SAME (71) We, EXXON RESEARCH AND ENGINEERING COMPANY, a Corporation duly organised and existing under the laws of the State of Delaware, United States of America, of Linden, New Jersey, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a catalyst and process for hydrotreating of mineral oils. More particularly, this invention relates to an alumina-containing hydrotreating catalyst having a median pore radius of from 70 to 95 Angstroms and having a specified pore size distribution.

Hydrodesulfurization catalysts having specified pore size distribution have been proposed to overcome disadvantages of conventional prior art catalysts.

Multi-stage processes of hydroprocessing have been proposed in an attempt to overcome some of the disadvantages of the one-stage processes. For example, it has been proposed to use a two-stage process for hydro-processing a heavy hydrocarbon feedstock in which the second stage catalyst has a larger pore diameter than the first stage catalyst.

It has now been found that special advantages can be obtained by utilizing wide pore catalyst having a narrow pore size distribution.

The present invention provides a catalyst comprising an alumina-containing support composited with a hydrogenation component comprising at least one Group VIB metal component and at least one Group VIII metal component, in which the catalyst has a median pore radius in the range of from 70 to 95 Angstroms, a total pore volume between 0.45 and 1.50 mVg; at least 0.40 ml/g pore volume in pores with radii in the range of from 10 Angstroms above and 10 Angstroms below said median pore radius; at least 75 percent of the pore volume in pores with radii in the range of from 10 Angstroms above and 10 Angstroms below said median pore radius; and a total surface area in the range of from 130 to 500 square meters per gram.

Furthermore, in accordance with the invention there is provided a process for hydrotreating a sulfur and asphaltene-containing hydrocarbon oil which comprises contacting said oil under hydrotreating conditions with hydrogen and a catalyst as specified in the preceding paragraph.

Furthermore, in accordance with the invention, there is provided a process for hydrotreating a heavy hydrocarbon feed, which comprises: contacting said feed in a first treating zone with hydrogen and a first hydrotreating catalyst under hydrotreating conditions to produce a first hydrotreated hydrocarbon product, and contacting at least a portion of said first hydrotreated hydrocarbon product in a second treating zone with hydrogen and a second catalyst, said first catalyst having a median pore radius in the range of from 30 to 60 Angstroms and said second catalyst being a catalyst as specified hereinabove and having a median pore radius greater than the median pore radius of said first catalyst.

The pore radius referred to herein is determined using a Mercury Penetration Porosimeter Model 915-2 manufactured by Micromeritics Corporation, Norcross, Georgia. The surface tension of the mercury was taken as 474 dynes per centimeter at 25"C and a contact angle of 140 was used. The calculation of pore volume distribution is similar to that used by ORR, Powder Technology, volume 3, 1969- 70, pages 117-123. By "median pore radius" is intended herein that 50van of the pore volume is above the given radius and 50V of the pore volume is below the given radius. By the expression "10 Angstroms above and 10 Angstroms below the median pore radius" is intended that the radius can be plus or minus 10 Angstroms from the actual median pore radius of the given catalyst.

Brief Description of the Drawings Figure 1 is a graph comparing the temperature required to achieve 0.3 weight percent sulfur in liquid product versus days on oil for the catalyst of the present invention (catalyst F) and conventional catalysts (catalysts A and D).

Figure 2 is a graph comparing the temperature required to achieve 0.3 weight percent sulfur in liquid product versus days on oil for the catalyst of the present invention (catalyst F) and a conventional catalyst (catalyst G).

Figure 3 is a graph comparing the effect of pore size distribution at approximately the same median pore diameter for a catalyst of the present invention (catalyst F) and a conventional catalyst (catalyst E) on temperature required to achieve 0.3 weight percent sulfur in liquid product versus days on oil.

Figure 4 is a graph showing the effect of pore radius and metals level on hydrodesulfurization activity of the catalyst of the present invention (catalysts L, F, J, K) and conventional catalysts (G, H and I).

Figure 5 is a graph showing the effect of median pore radius on vanadium removal selectivity for the catalyst of the present invention (catalysts F, J, L, K) and conventional catalysts (G, H, I, E).

Description of the Preferred Embodiments In one embodiment of the invention, a sulfur and asphaltene-containing heavy hydrocarbon feedstock is contacted in a hydrotreating zone with hydrogen and the catalyst of the present invention under hydrodesulfurization conditions to produce a hydrocarbon product having a reduced content of sulfur. The catalyst of the invention is particularly suited for use when it is desired to desulfurize the asphaltene fraction of the feed to a level greater than 400% desulfurization, preferably to a level greater than 50% desulfurization, more preferably to a level greater than 700 desulfurization of the asphaltene fraction.

By "hydrotreating process" is intended herein the contacting of the hydrocarbon feed with a catalyst in the presence of hydrogen and under selected conditions to remove heteroatoms, such as sulfur, nitrogen, oxygen and metallic contaminants such as nickel, vanadium and iron, from the feedstock and/or to saturate aromatic hydrocarbons and/or olefinic hydrocarbons in the feedstock and/or to hydrocrack the feedstock. The process of the invention is particularly well suited for hydrodesulfurization and hydrodemetallization of asphaltenecontaining heavy sulfur-bearing mineral oils which usually also contain a high content of metallic contaminants.

Heavy Hydrocarbon Feedstocks The heavy hydrocarbon feedstocks utilized in the present invention comprise hydrocarbons boiling above 650"F. (at atmospheric pressure) which contain substantial quantities of material boiling above 1000"F. The process is particularly suited for treating sulfur- and asphaltene-containing hydrocarbon oils containing greater than 100 wppm nickel and vanadium contaminants. Suitable feeds include heavy crude mineral oils, residual petroleum oil fractions such as fractions produced by atmospheric and vacuum distillation of crude oil. Such residual oils usually contain large amounts of sulfur and metallic contaminants such as nickel and vanadium. Total metal content of such oils may range up to 2000 weight parts per million or more and the sulfur content may range to 8 weight percent or more.

The Conradson carbon residue of these heavy hydrocarbon feeds will generally range from 5 to 50 weight percent (as to Conradson carbon, see ASTM Test Dl 890- 65). The preferred process feedstock is a petroleum residuum obtained from distillation or other treating or separation process. From 30 to 100 percent of the petroleum residuum feed boils above 900"F. (at atmospheric pressure). Other suitable feedstocks include heavy hydrocarbons recovered from tar sands, synthetic crude oils recovered from oil shales, heavy oils produced from the liquefaction of coal, etc. The hydrocarbon feeds will generally contain at least 10 percent of materials boiling above 1000"F. (at atmospheric pressure).

Operating Conditions in the Hydrotreating Zone The operating conditions in the hydrotreating zone are summarized in the following table: Preferred Conditions Broad Range Range Temperature, F 600-900 650-800 Pressure, psig 600-3500 800-3200 Liquid Hourly Space Velocity 0.05-5.0 0.10-2.5 V/V/Hr.

Hydrogen Rate, SCF/bbl 300-20,000 600-12,000 Hydrogen Partial Pressure, 500-3000 800-2500 psig A more preferred pressure range is from 1200 to 2500 psig.

The Hydrotreating Catalyst The hydrotreating catalyst of the present invention utilized in the hydrotreating zone comprises a hydrogenation component and an aluminacontaining support.

The median pore radius of the hydrodesulfurization catalyst of the present invention will be from 70 to 95 Angstroms. The hydrotreating catalyst of the present invention has the following physical characteristics shown in Table I.

TABLE I Characterization of Catalyst Pore Size Distribution Broad Range Preferred More Preferred Minimum Maximum Minimum Maximum Minimum Maximum Surface Area, m2/g 130 500 132 200 135 175 Pore Volume, ml/g 0.45 1.50 0.48 1.00 0.50 0.60 Median Pore Radius, (Rm) A 70 95 75 90 78 86 Pore Volume Distribution PV above 100 Radius, ml/g 0 0.050 0 0.040 0 0.035 PV between Rm#10 , ml/g 0.40 1.00 0.41 0.80 0.42 0.60 % PV between Rm#10 ,% 75 99 80 98 81 96 PV below 60 Radius, ml/g 0 0.050 0 0.040 0 0.035 The hydrotreating catalyst of the present invention comprises a hydrogenation component comprising a Group VIB metal component and a Group VIII metal component composited with a refractory support. A preferred hydrotreating catalyst comprises a hydrogenation component comprising at least one elemental metal, metal oxide, or metal sulfide of a Group VIB metal and at least one elemental metal, metal oxide or metal sulfide of a Group VIII metal wherein the Group VIB metal, calculated as the oxide thereof, based on the total catalyst, is present in an amount of at least 8 weight percent, preferably from 8 to 25 weight percent, more preferably from 14 to 20 weight percent, and wherein the Group VIII metal component, calculated as the metal oxide, based on the total catalyst, is present in an amount of at least 2.5 weight percent, preferably from 2.5 to 15 weight percent, more preferably from 3.5 to 6.5 weight percent. The preferred Group VIB metal component is selected from the group consisting of molybdenum oxide, molybdenum sulfide, tungsten oxide and tungsten sulfide and mixtures thereof and a preferred Group VIII metal component is selected from the group consisting of nickel oxide, nickel sulfide; cobalt oxide, cobalt sulfide, and mixtures thereof. The oxide catalysts are preferably sulfided prior to use in a conventional way.

TABLE II Preferred Catalyst Composition Broad Range Range Nickel or cobalt as oxide, wt /" 2.5-15 3.5-6.5 Tungsten or molybdenum as 8-25 14--20 oxide, wt, E Alumina Balance Balance The catalyst may be prepared in a conventional manner, for example, by impregnating an alumina-containing support having the desired physical characteristics with salts of the desired hydrogenation metals. Methods for preparing the alumina supports are well known in the art. The alumina support may further contain a minor amount of other inorganic oxides, such as silica.

Another embodiment of the invention is a two-stage hydrotreating process in which a heavy hydrocarbonaceous feedstock is first treated with hydrogen in the presence of a first hydrotreating catalyst having relatively small pores and wherein at least a portion of the hydrotreated hydrocarbon product is further treated with hydrogen in a second hydrotreating zone in the presence of a second hydrotreating catalyst, said second hydrotreating catalyst being the narrow pore size distribution catalyst of the present invention.

The heavy hydrocarbonaceous feedstocks for use in the two-stage hydrotreating process are the same feeds as already described.

Operating Conditions in the thirst Hydrotreating Zone The operating conditions for the first hydrotreating zone are summarized in the following table: Preferred Conditions Broad Range Range Temperature, F 600-900 650-800 Pressure, psig 600-3500 800-3200 Liquid Hourly Space Velocity 0.05-5.0 0.10--2.5 V/V/Hr Hydrogen Rate SCF/bbl 3020,000 600--12,000 Hydrogen Partial Pressure, 5003000 8002500 psig The preferred total pressure range is from 1200 to 2500 psig.

When the process is conducted under hydrodesulfurization conditions, with a sulfur-containing heavy hydrocarbon oil, the feed is treated in the first hydrodesulfurization zone for a time sufficient to effect preferably between 35 and 90 weight percent desulfurization, more preferably not more than 88 percent desulfurization of the feed. Subsequently, the partially desulfurized hydrocarbon product is treated in the second hydrodesulfurization zone to effect a total desulfurization between 50 and 99.9 weight percent based on the feed to the first hydrodesulfurization zone.

First Hydrotreating Catalyst The hydrotreating catalyst utilized in the first hydrotreating zone may comprise any conventional hydrotreating catalyst, preferably one having a smaller median pore size radius than the catalyst utilized in the second hydrotreating zone.

Preferably the first hydrotreating zone catalyst has more than 75V of its pore volume in pores having radii in the range of from 10 Angstroms greater and less than the median pore radius of the catalyst. More preferably, the first hydrotreating zone catalyst has less than 0.05 ml/g pore volume in pores with radii greater than 100 Angstroms. Generally, these catalysts comprise a hydrogenation component comprising at least one Group VIB metal component and at least one Group VIII metal component composited with a refractory support. The Groups VIB and VIII referred to herein are groups of the Periodic Table of Elements. The Periodic Table referred to herein is in accordance with the Handbook of Chemistrv and Physics published by the Chemical Rubber Publishing Company, Cleveland, Ohio, 45th Edition, 1964. A preferred catalyst for use in the first hydrotreating zone of the present invention has a median pore radius ranging from 30 to 60 Angstroms.

A particularly preferred catalyst comprises the oxide or sulfide of a Group VIB metal and the oxide or sulfide of a Group VIII metal deposited upon a support material comprising a silica-stabilized alumina containing 1 to 6 weight percent silica, the catalyst having a surface area of at least 150 square meters per gram and more than 80 percent of its pore volume in pores having radii of from 25 to 45 Angstroms. The active metallic components in the particularly preferred catalysts are a Group VIB oxide or sulfide, specifically a molybdenum or tungsten oxide or sulfide selected from the group consisting of molybdenum oxide, molybdenum sulfide, tungsten oxide, tungsten sulfide and mixtures thereof and a Group Vlll oxide or sulfide, specifically a nickel or cobalt oxide or sulfide selected from the group consisting of nickel oxide, cobalt oxide, nickel sulfide, cobalt sulfide and mixtures thereof. The preferred active metal components are nickel oxide with molybdenum oxide and cobalt oxide with molybdenum oxide. The oxide catalysts are preferably sulfided prior to use. The preferred catalysts and methods for preparing these catalysts are disclosed in U.S. Patent 3,770,618 and U.S. Patent 3,509,044.

The operating conditions in the second hydrotreating zone fall substantially in the same ranges as the conditions listed for the first hydrotreating zone.

At least a portion of the hydrotreated hydrocarbon product resulting from the first hydrotreating zone is subsequently treated in the second hydrotreating zone. If desired, hydrogen sulfide produced in the first hydrotreating zone may be separated from the hydrotreated product before passing the product to the second hydrotreating zone. However, it is not necessary to remove the H2S from the hydrotreated product of the first reaction zone before subjecting the product to the second hydrotreating zone.

The hydrogen-containing treating gas is recycled to the hydrotreating zones, usually after removal of hydrogen sulfide.

The Second Hydrotreating Catalyst The catalyst utilized in the second hydrotreating zone has a median pore radius greater than the median pore radius of the first hydrotreating zone catalyst.

The catalyst used in the second hydrotreating zone is a catalyst in accordance with the catalyst of the present invention. The second hydrotreating zone catalyst has the physical characteristics given in Table I and has the composition already described of the catalyst of the present invention including the composition given in Table II.

The following examples are presented to illustrate the present invention. All the catalysts utilized in the experiments described in Examples I to 3 were sulfided in a conventional manner before being tested. The tests were conducted at 2000 psig hydrogen pressure and a gas rate of 3000 SCF per barrel. The respective comparative runs were made at the same space velocity.

EXAMPLE I Comparative runs were conducted utilizing a conventional prior art catalyst and a catalyst in accordance with the present invention. The characteristics of the catalysts designated herein Catalysts S and T are tabulated in Table III. Catalyst S is a conventional catalyst. Catalyst T is a catalyst in accordance with the present invention.

A Safaniya atmospheric residuum (Heavy Arabian) containing 3.6 weight percent sulfur was passed in upward flow through a fixed bed of extrudates of catalyst S comprising approximately 4 weight percent CoO and 12 weight percent MoO3 and having the characteristics shown in Table III. The characteristics of this atmospheric residuum are given in Table IV. A run was carried out such that after sulfiding the catalyst, the residuum feedstock was added to the reactor, feed rate, pressure and gas rate set, and the temperature adjusted each day to maintain approximately 1.0 weight percent product sulfur.

Note that of the 3.61 weight percent sulfur in the feed, approximately 1.47 weight percent was in the asphaltene (pentane-insoluble fraction). Hence, a 1.0 weight percent product sulfur will represent 32.0 percent desulfurization of the asphaltene fraction, assuming that all of the non-asphaltene sulfur was preferentially removed before removal of the sulfur from the asphaltenes.

TABLE III Catalyst Inspections Catalyst No. S T Chemical Composition: % CoO 4.0 4.5 % MoO3 12.0 16.0 % SiO2 1.0 % Al203 Balance Balance Physical Properties: BET Surface Area, m2/g 270 137 Total Pore Volume, ml/g 0.47 0.525 Pore Size Distribution: Median Pore Radius, A 35 84 Pore Volume Distribution: P.V. above 100 A Radius ml/g 0.02 0.025 P.V. between Rm#10 , mVg 0.435 0.435 % P.V. between R~+l0A 92.6 82.9 P.V. below 60 A Radius, ml/g 0.44 0.015 TABLE IV Feedstock Inspections Safaniya Atmospheric Residuum Feedstock No. 1 Gravity, API @60 F. 13.9 Sulfur, Wt.% 3.61 Carbon Wt.% 84.92 Hydrogen, wt.% 11.14 Nitrogen, Wt.% 0.269 Oxygen, Wt.% conradson Carbon, Wt.% 12.0 Aniline Pt., F RI @ 67 C. Bromine No., g/100 g 5.9 1160 ASTM Distillation @ Imm IBP, F. 445 5% @ F. 584 10% @ F. 642 20% @ F. 743 30% @ F. 829 40% @ F. 901 50% @ F. 995 60% @ F.

70% @0F.

80% @ F 90% @"F.

95% @"F.

FBP, 0F. 1050 Rec., % 58 TABLE IV(COFJ) Feedstock Inspections Safaniya Atmospheric Residuum Res., % 42 V, wppm 88 Ni, wppm 20 Fe, wppm 4 Asphalt, C5 Insoluble, Wt.% 21.6 Sulfur in asphaltene fraction, Wt.% 6.80 A similar experiment was conducted with catalyst T which is a catalyst in accordance with the present invention.

Results of these experiments are shown in Table V, where catalyst activity is represented as the temperature required above base conditions to achieve the desired desulfurization level. Since catalyst S required a substantially lower temperature than catalyst T, it can be seen that catalyst S was more active.

Furthermore, catalyst S deactivated at a substantially lower rate than catalyst T.

TABLE V Catalyst S T Temperature, 0F. above base atday 1 19 19 at day 5 19 32 atdayl0 19 35 at day 20 19 38 at day 30 19 41 EXAMPLE 2 A similar pair of experiments was carried out with catalyst S and catalyst T at a lower feed rate and the temperature was adjusted each day to maintain approximately 0.3 weight percent product sulfur.

If it is assumed that all of the non-asphaltenic sulfur is preferentially removed before conversion of the sulfur in the asphaltenes, this would represent a 79.6% desulfurization of the asphaltene fraction. The results of these experiments are summarized in Table VI.

TABLE VI Catalyst S T Temperature, OF. above base at day 5 45.0 34.2 atday 10 50.4 37.8 at day 20 57.6 49.0 at day 30 63.0 56.0 at day 40 72.0 63.0 It is surprising that catalyst T was now more active than catalyst S, as represented by the lower temperature required above base conditions to achieve the desired desulfurization level at corresponding times.

EXAMPLE 3 A light Arabian 1050"F+ vacuum residuum containing about 4 weight percent sulfur was used in evaluating and comparing catalyst S and catalyst T. The feed was passed in downward flow through a fixed bed of extrudate. The characteristics of this vacuum residuum are given in Table VII.

TABLE VII Feedstock Inspections Light Arabian 10500F plus Vacuum Residuum Feedstock No. 2 Gravity, OKAPI 6.7 Sulfur, Wt.% 4.03 TABLE VII

Feedstock Inspections Light Arabian 10500F plus Vacuum Residuum Carbon, Wt.% 85.37 Hydrogen, Wt.% 9.91 Pour Point, "F 118.00 Conradson Carbon, Wt.% 24.86 Iron, wppm 6.6 Nickel, wppm 26.6 Vanadium, wppm 100.7 Asphaltenes (pentane-insoluble), Wt.% 25.4 Sulfur in asphaltene fraction, Wt.% 5.62 The runs were carried out in a similar way as in the previous examples except that the temperature was adjusted each day to maintain approximately 0.85 weight percent product sulfur. Of the 4.03 weight percent sulfur in the feed, approximately 1.43 weight percent was in the asphaltene (pentane-insoluble) fraction. Therefore, a 0.85 weight percent product sulfur represents 40.6 percent desulfurization of the asphaltene fraction, if it is assumed that all of the non-asphaltene sulfur is removed before sulfur removal begins in the asphaltene fraction.

The results of these experiments are summarized in Table VIII.

TABLE VIII Catalyst S T Temperature, OF. above base at day 5 29 21 atdayl0 35 32 atday25 40 40 atday50 52 43 atday75 79 46 During the first twenty-five days on oil, both catalysts S and T exhibited about the same activity. However, after about 50 days, catalyst T was substantially more active than catalyst S and this trend was increased even further after 75 days on oil.

EXAMPLE 4 A series of comparative runs were conducted utilizing catalysts containing molybdenum and cobalt or nickel composited with an alumina support having varying physical characteristics. The characteristics of the catalysts, designated herein catalysts A, B, C, D, E, F, G, H, I, J, K, L are tabulated in Table IX.

Catalysts designated F, J, K and L are suitable second hydrotreating stage catalysts for the two-stage process of the present invention.

TABLE IX Catalyst Inspections Catalyst No. A B C D E F G H I J K L Chemical Composition: % CoO (NiO) 2.9 2.9 2.9 3.0(NiO) 4.5 4.5 4.0 4.0(NiO) 4.0 4.0 4.5 3.5(NiO) % MoO3 20.7 20.7 20.7 18.0 16.0 16.0 12.0 12.0 12.0 12.0 16.0 16.1 % SiO2 - - - - - - 1.0 - - - - % Al2O3 Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal.

Physical Properties: BET Surface Area, m2/g 177 153 188 151 161 137 270 197 161 159 154 144 Total Pore Volume, ml/g 0.49 0.565 0.50 0.46 0.65 0.525 0.47 0.525 0.53 0.58 0.52 0.536 Pore Size Distribution: Median Pore Radius, 80 90 69 55 88 84 35 60 69 79 73 84 35 60 69 79 73 84 Pore Volume Distribution: P.V. above 100 Radius, ml/g 0.04 0.155 0.030 0.020 0.20 0.025 0.02 0.020 0.020 0.030 0.023 0.025 P.V. between Rm#10 , ml/g 0.275 0.220 0.315 0.305 0.20 0.435 0.435 0.455 0.485 0.500 0.445 0.454 % P.V. between Rm#10 56.1 39.0 63.0 66.3 30.8 82.9 92.6 86.7 81.5 86.2 85.6 84.7 P.V. below 60 Radius, ml/g 0.095 0.060 0.125 0.325 0.11 0.015 0.44 0.25 0.025 0.02 0.03 0.022 Before testing, all of the catalysts were presulfided in a conventional way. The feed was prepared as follows to simulate a second stage feedstock: Initially a Safaniya atmospheric residuum (Heavy Arabian) containing 3.6 weight /" sulfur was treated over catalyst G, which is a suitable first stage catalyst. The characteristics of this atmospheric residuum are given in Table IV. The resulting product from this operation was collected and used as a feed for the subsequent two-stage experiments. The feedstock used to generate the data recorded in Figures 1, 2, 3, 4 and 5 is given in Table X. All the results were obtained on feedstock number 3. The runs were carried out such that, after sulfiding, the residuum feedstock was added to the reactor, feed rate, pressure and gas rates set, and the temperature adjusted each day so as to maintain approximately a 0.3 weight percent sulfur product.

TABLE X Feedstock Inspections Safaniya Hydrotreated A.R.

Feedstock No. 3.

Gravity, API @ 60 F. 19.3 Sulfur Wt.% 0.98 Carbon, Wt.% 86.80 Hydrogen, Wt.% 12.05 Nitrogen, Wt.% 0.1735 Oxygen, Wt.% Conradson Carbon, Wt.% 7.0 1160 ASTM Distillation @ 1 mm IBP, F. 525 5% @ F. 571 10% @ F. 636 20% @ F. 724 30 /" @ F. 829 40% @ F. 877 50% @ F 943 60% @ F. 1036 70% @ F.

80% @ F.

90% @ F.

95% @ F FBP, F. 1050 Rec., % 63 Res., % 37 V, wppm 53.4 Ni, wppm 17.6 Fe, wppm 0.0 Asphalt, C5 Insoluble Wt.% 11.3 The results of these tests are summarized in Figures 1, 2, 3, 4 and 5.

Figure 1 shows comparative results utilizing catalyst F (which is a second stagy catalyst of the present invention) with catalysts A and D which are conventional catalysts. Figure 2 shows the comparative results between catalyst G, which is a suitable first stage catalyst, with catalyst F, which is a second stage catalyst of the present invention.

It should be noted that catalyst A has a median pore radius which falls within the range of the second stage catalyst of the present invention; however, catalyst A does not have the same narrowness index as that required for the second stage catalyst of the present invention. The term "narrowness index" is used herein to designate the pore volume contained in the region which includes the median pore radius and has the limits 10 Angstroms above and 10 Angstroms below the median value. Moreover, catalyst A has more of its pore volume in pores less than 60 Angstroms radius than is desired. Catalyst D is a smaller pore catalyst which has been heretofore typically used as first stage hydrocracking pretreatment catalyst.

Figure 3 shows a comparison, at approximately the same pore diameter, of the effect of pore size distribution (narrowness index). Catalyst E was prepared on an alumina having an identical chemical composition as catalyst F, the only difference being in pore size distribution. Metals were added to the aluminas in identical fashions. The superior performance of the narrow pore distribution catalyst, F, should be noted.

Figure 4 shows the effect of median pore radius and metals level on hydrodesulfurization activity. These data show that an optimum median pore radius for hydrodesulfurization occurs at about 60 Angstrom radius. To improve hydrodesulfurization activity, additional metals were added to bring the total CoMoO4 content from 16 weight percent to approximately 20 weight percent. This had the effect of increasing hydrodesulfurization activity to a value greater than found at the optimum median pore radius value.

Figure 5 shows the vanadium removal selectivity of catalysts having median pore radii ranging between 70 and 95 Angstroms. For median pore radii of less than 70 Angstroms it can be seen that the percent vanadium removal at 70% sulfur removal is approximately constant and not influenced by the median pore radius; however, between 70 and 95 Angstroms, there is a significant improvement in metals removal selectivity. The 70 to 95 Angstroms median pore radii gives a good compromise between desulfurization and demetallization activity. The effect of pore radius on percent vanadium removal was unexpected. lt would be anticipated that a much smoother relationship would occur. It should be noted that median pore radius seems to be more important than narrowness of pore size distribution for hydrodemetallization activity. The narrowness index appears to influence desulfurization, as can be seen in Figures 1 and 3, to a much greater extent.

The results of the above-indicated experiments show that the second stage catalyst of the present invention was selected with a very narrow pore size distribution so as to give superior desulfurization performance and a narrow region of median pore radius so as to give enhanced demetallization performance. These two effects were balanced so as to achieve optimum performance for a given hydrodesulfurization and hydrodemetallization process.

Claims (24)

WHAT WE CLAIM IS:

1. A catalyst comprising an alumina-containing support composited with a hydrogenation component comprising at least one Group VIB metal component and at least one Group VIII metal component, in which the catalyst has a median pore radius in the range of from 70 to 95 Angstroms, a total pore volume between 0.45 and 1.50 ml/g; at least 0.40 ml/g pore volume in pores with radii in the range of from 10 Angstroms above and 10 Angstroms below said median pore radius; at least 75 percent of the pore volume in pores with radii in the range of from 10 Angstroms above and 10 Angstroms below said median pore radius; and a total surface area in the range of from 130 to 500 square meters per gram.

2. The catalyst of claim I wherein said catalyst has the following physical characteristics: Surface Area, m2/g 130 to 500 Pore Volume, ml/g 0.45 to 1.50 Median Pore Radius (rum) A 70 to 95 Pore Volume Distribution PV above 100 A radius, ml/g 0 to 0.05 PV between Rm#10 , ml/g 0.40 to 1.00 O/, PV between R,+10 /" 75 to 99 PV below 60 A radius, ml/g 0 to 0.05

3. The catalyst of claim 1 or claim 2 wherein said catalyst has the following physical characteristics: Surface Area, m2/g 132 to 200 Pore Volume, mVg 0.48 to 1.00 Median Pore Radius (Rm), A 75 to 90 Pore Volume Distribution PV above 100 A radius, ml/g 0 to 0.04 PV between Rm#10 , ml/g 0.41 to 0.80 % PV between Rm#10 ,% 80 to 98 PV below 60 radius, ml/g 0 to 0.04

4. The catalyst of any one of claims 1 to 3 wherein said catalyst has the following physical characteristics: Surface Area, m2/g 135 to 175 Pore Volume, mVg 0.50 to 0.60 Median Pore Radius (run), A 78 to 86 Pore Volume Distribution PV above 100 A radius, mVg 0 to 0.035 PV between R,+10 A, ml/g 0.42 to 0.60 %PVbetweenRrn::l:l0A;% PV 81to96 PV below 60 A radius, mUg 0 to 0.035

5. The catalyst of any one of claims I to 4 wherein said hydrogenation component comprises at least one elemental metal, metal oxide or metal sulfide of a Group VIB element and at least one elemental metal, metal oxide or metal sulfide of a Group VIII metal.

6. The catalyst of any one of claims 1 to 5 wherein said Group VIB metal (calculated as the oxide thereof) comprises at least 8 weight percent of the total catalyst and wherein said Group VIII metal (calculated as the oxide thereof) comprises at least 2.5 weight percent of the total catalyst.

7. The catalyst of any one of claims 1 to 6 wherein said Group VIB metal (calculated as the oxide thereof) comprises at least 14 weight percent of the total catalyst and wherein said Group VIII metal (calculated as the oxide thereof) comprises at least 3.5 weight percent of the total catalyst.

8. The catalyst of any one of claims 1 to 7 wherein said Group VIB metal component is selected from molybdenum oxide, molybdenum sulfide, tungsten oxide, tungsten sulfide and mixtures thereof and wherein said Group VIII metal component is selected from nickel oxide, cobalt oxide, nickel sulfide, cobalt sulfide and mixtures thereof.

9. The catalyst of any otle of claims 1 to 8 comprising a minor amount of an inorganic oxide other than alumina.

10. The catalyst of any one of claims 1 to 9 comprising a minor amount of silica.

11. A catalyst according to any one of claims 1 to 10 substantially as hereinbefore described.

12. A process for hydrotreating a sulfur and asphaltene-containing hydrocarbon oil which comprises contacting said oil under hydrotreating conditions with hydrogen and a catalyst according to any one of claims 1 to 11.

13. The process of claim 12 wherein said hydrotreating conditions include a temperature of from 600 to 9000F., a pressure of from 600 to 3500 psig, a liquid hourly space velocity of from 0.05 to 5 volumes of hydrocarbon oil per hour per volume of catalyst, a hydrogen rate of from 300 to 20,000 standard cubic feet per barrel, and a hydrogen partial pressure of from 500 to 3000 psig.

14. The process of claim 13 wherein said pressure is in the range of from 1200 to 2500 psig.

15. The process of any one of claims 12 to 14 wherein said hydrotreating process is a hydrodesulfurization process and wherein the asphaltene fraction of said hydrocarbon oil is desulfurized to a level greater than 40 weight percent.

16. The process of any one of claims 12 to 15 wherein said hydrocarbon oil contains more than 100 wppm nickel and vanadium contaminants.

17. The process of any one of claims 12 to 16 wherein said hydrotreating process is a two-stage process comprising: (a) contacting a heavy hydrocarbon feed in a first treating zone with hydrogen and a first hydrotreating catalyst under hydrotreating conditions to produce a first hydrotreated hydrocarbon product, and (b) contacting at least a portion of said first hydrotreated hydrocarbon product in a second treating zone with hydrogen and a second hydrotredting catalyst, said first catalyst having a median pore radius in the range of from 30 to 60 Angstroms and said second catalyst being in accordance with any one of claims 1 to 11 and having a median pore radius greater than the median pore radius of said first catalyst.

18. The process of claim 17 wherein said first catalyst has more than 75 percent of its pore volume in pores having radii ranging between said median pore radius of the first catalyst and 10 Angstroms above and 10 Angstroms below the median pore radius of the first catalyst and wherein said first catalyst has less than 0.05 mUg per volume in pores with radii greater than 100 Angstroms.

19. The process of claim 17 or claim 18 wherein said first catalyst comprises the oxide or sulfide of a Group VIB metal and the oxide or sulfide of a Group VIII metal deposited on a support material comprising a silica-stabilized alumina containing from 1 to 6 weight percent silica, said first catalyst having a surface area of at least 150 square meters per gram and more than 80 percent of its pore volume being in pores having radii of from 25 to 45 Angstroms.

20. The process of any one of claims 17 to 19 wherein said hydrotreating process is a hydrodesulfurization process, said heavy hydrocarbon feed being a sulfur-containing feed and wherein said feed in the first hydrodesulfurization zone is desulfurized to a level of from 35 to 90 percent relative to the feed sulfur.

21. The process of claim 20 wherein the desulfurization level in said first hydrodesulfurization zone is limited to not more than 88 weight percent desulfurization based on the feed sulfur.

22. The process of any one of claims 17 to 21 wherein the hydrotreating conditions in each of said treating zones include a temperature of from 600 to 900"F, a pressure of from 600 to 3500 psig, a liquid hourly space velocity of from 0.05 to 5 volumes of hydrocarbon feed per hour per volume of catalyst, a hydrogen rate of from 300 to 20,000 standard cubic feet per barrel, and a hydrogen partial pressure of from 500 to 3000 psig.

23. The hydrotreating process according to any one of claims 12 to 22 substantially as hereinbefore described.

24. A hydrotreated product obtained by hydrotreating a sulfur and asphaltenecontaining hydrocarbon oil by a process according to any one of claims 12 to 23.