MXPA98010769A - A process to presulfate hydrocarbon conversion catalysts - Google Patents

Abstract

The present invention relates to: The invention provides a process for presulphurizing the porous particles of a sulfurizable catalyst containing at least one metal or metal oxide, comprising (a) impregnating the catalyst with an inorganic polysulfide solution to obtain a catalyst with incorporated sulfur in which at least a portion of the sulfur or sulfur is incorporated in the pores of the catalyst, and (b) heating the catalyst with incorporated sulfur in the presence of a non-oxidizing atmosphere, presulfurized catalysts and their use in processes hydrocarbon conversion

Description

A PROCESS TO PRESULFORE CATALYSTS OF CONVERSION OF HYDROCARBONS Field of Invention This invention relates to a process for presulfurizing or presulfiding hydrocarbon conversion catalysts, to presulfurized catalysts and their use in hydrocarbon conversion processes.

Background of the Invention It is known that it is often convenient to use the step of "presulphurization" or "presulphication" of the metals that are part of the composition of certain catalysts for refining and / or hydroconverting hydrocarbons, either before they are used initially, that is, fresh catalysts, or before they are used again after regeneration. Hydrocarbon conversion catalysts, such as hydrotreating, hydrocracking and tail gas treatment catalysts, are typically REF .: 29131 subjected to a "presulfurization step" of this type.

A hydrotreater catalyst can be defined as any catalyst composition that can be used to catalyze the hydrogenation of hydrocarbon feedstocks, and most particularly to hydrogenate particular components of the feedstock, such as unsaturates and organo-compounds containing sulfur, nitrogen and metals. A hydrocracking catalyst can be defined as any catalyst composition that can be used to crack large and complex petroleum-derived molecules to achieve smaller molecules with the concomitant addition of hydrogen to the molecules. A tail gas catalyst can be defined as any catalyst composition that can be used to catalyze the conversion of hazardous effluent gas streams to less harmful products, and most particularly to convert sulfur oxides to hydrogen sulfide, which can be recovered and converted without difficulty to elemental sulfur. A reduced catalyst can be defined as any catalyst composition containing a metal in the reduced state such as, for example, an olefin hydrogenation catalyst. Such metals are typically reduced with a reducing agent such as, for example, hydrogen or formic acid. The metals on these reduced catalysts can be totally reduced or partially reduced.

The catalyst compositions for hydrogenation catalysts are well known and several are commercially available. Typically, the active phase of the catalyst is based on at least one metal of group VIII, VIB, IVB, IIB or IB of the Periodic Table of the Elements. In general, the hydrogenation catalysts contain at least one element selected from Pt, Pd, Ru, Ir, Rh, Os, Fe, Co, Ni, Cu, Mo, Ti, Hg, Ag or Au usually supported on a support such as alumina, silica, silica-alumina and carbon.

The catcher compositions for hydrotreating and / or hydrocracking or tail gas treatment are well known and several are commercially available. Metal oxide catalysts falling within this definition include cobalt-molybdenum, nickel-tungsten and nickel-molybdenum usually supported on alumina, silica and silica-alumina carriers, including zeolite. Also, other transition metal element catalysts may be employed for these purposes. In general, catalysts containing at least one element selected from V, Cr, Mn, Re, Ni, Cu, Zn, Mo, Rh, Ru, Os, Ir, Pd, Pt, Ag, Au, Cd, Sn , Sb, Bi and Te have been described as suitable for these purposes.

For maximum effectiveness these metal oxide catalysts are converted at least in part to metal sulphides. The metal oxide catalysts can be sulfurized in the reactor by contact at elevated temperatures with hydrogen sulfide or an oil or a sulfur-containing raw material ("in situ").

However, it is advantageous that sulfur metal oxide catalysts are supplied to the user., as an element or in the form of an organo-sulfur compound, incorporated therein. These pre-fused catalysts can be charged to a reactor and brought to reaction conditions in the presence of hydrogen, causing the sulfur or sulfur compound to react with hydrogen and the metal oxides thereby converting them into sulphides, without requiring them. additional process steps. These presulphurized catalysts provide an economic advantage to the plant operator and avoid many of the hazards such as flammability and toxicity encountered by the plant operator when using hydrogen sulfide, liquid sulfides, organic polysulfides and / or mercaptans to sulfurize the catalysts .

Various methods for presulfurizing metal oxide catalysts are known. The hydrotreating catalysts have been presulphized by incorporating sulfur compounds into a porous catalyst before hydrotreating a hydrocarbon feedstock. For example, U.S. Pat. No. 4,530,917 describes a method for presulfurizing a hydrotreating catalyst with organic polysulfides. U.S. Pat. No. 4,177,136 discloses a method for presulfurizing a catalyst by treating the catalyst with elemental sulfur. Hydrogen is then used as a reducing agent to convert the elemental sulfur to hydrogen sulfide in situ. U.S. Pat. No. 4,089,930 describes the pretreatment of a catalyst with elemental sulfur in the presence of hydrogen. U.S. Pat. No. 4,943,547 describes a method for presulfurizing a hydrotreating catalyst by sublimating elemental sulfur in the pores of the catalyst and then heating the mixture of sulfur and catalyst to a temperature above the melting point of the sulfur in the presence of hydrogen. The catalyst is activated with hydrogen. Published PCT Application No. WO 93/02793 discloses a method for presulfurizing a catalyst, wherein elemental sulfur is incorporated into a porous catalyst and at the same time, or subsequently, the catalyst is treated with a liquid olefinic hydrocarbon.

However, these ex situ presulphurized catalysts must be subjected to a separate activation step before coming into contact with the hydrocarbon feed in a hydrocarbon processing reactor.

Description of the invention.

Therefore, an object of the present invention is to prepare an activated, presulphurized or presulphided catalyst, either fresh or regenerated, without the requirement of a separate activation treatment before being brought into contact with the hydrocarbon feed in the reactor.

Therefore, according to the present invention, there is provided a process for presulphurizing the porous particles of a sulfurizable catalyst containing at least one metal or metal oxide, comprising (a) impregnating the catalyst with an inorganic polysulfide solution. to obtain a catalyst with incorporated sulfur in which at least a portion of the sulfur or sulfur is incorporated in the pores of the catalyst; and (b) heating the catalyst with incorporated sulfur in the presence of a non-oxidizing atmosphere.

The present invention additionally provides a presulphurized catalyst which can be obtained by a process according to the invention.

As used in this specification, the term "inorganic polysulfide" refers to polysulfide ions having the general formula S (X) 2_ where x is an integer greater than 2, i.e., x is an integer having a value of at least 3, preferably from 3 to 9, and preferably from 3 to 5, and the term "inorganic", in this context, refers to the nature of the polysulfide portion instead of the counterion, which may be organic. As used herein, the phrase "inorganic polysulfide solution" refers to a solution containing inorganic polysulfides. As used in this specification, catalysts containing the terms "metal (s)", "metal oxide (s)" and "metal sulfide (s)" include catalyst precursors that are subsequently used as effective catalysts. Additionally, the term "metal (s)" includes metal (s) in partially oxidized form. The term "metal oxide (s)" includes metal oxide (s) in partially reduced form. The term "metal sulfide (s)" includes metal sulfide (s) that are partially sulfided, as well as fully sulfided metals. The above terms include in part other components such as carbides, brorides, nitrides, oxyhalides, alkoxides and alcoholates.

In the present invention, a catalyst containing metal oxide or presulfurable metal is impregnated with a solution of inorganic polysulfide presulfiding the catalyst metal oxide or presulfurable metal at a temperature and for a time effective to cause incorporation of the sulphide or sulfur to the pores of the catalyst. The catalyst is heated after impregnation under non-oxidizing conditions for a sufficient time to fix the sulfur or sulfur incorporated on the catalyst.

The catalysts mentioned herein as "sulfurous metal oxide catalyst (s)" can be catalyst precursors which are used as effective catalysts while they are in the sulfided form and not in the oxide form. Since the preparation technique of the present invention can be applied to regenerated catalysts which may have the metal sulphide not completely converted to the oxides, the phrase "sulfurous metal oxide catalyst (s)" also refers to These catalysts have part of their metals in the sulphurated state.

In a preferred embodiment, prior to impregnation with the inorganic polysulfide solution, the catalyst particles or pellets of metal or metal oxide are hydrated to equilibrium with air in order to reduce the initial exotherm.

In carrying out the process of the present invention, the porous catalyst particles are contacted and reacted with an inorganic polysulfide solution under conditions which cause the sulfur or sulfur compounds to be incorporated into the pores of the catalyst by impregnation. . Catalysts with incorporated inorganic polysulfide or incorporated sulfur compound will be referred to as "catalysts with incorporated sulfur".

The inorganic polysulfide solution is typically prepared by dissolving elemental sulfur in an aqueous solution of ammonium sulfide (or ammonium derivative, ie tetra ethyl ammonium, tetraethyl ammonium, etc.). Preferred polysulfides include inorganic polysulfides of the general formula S (X) 2- in which x is an integer greater than 2, preferably from 3 to 9 and preferably from 3 to 5, such as, for example, S (3 > 2 ~, S (4) 2 ~, S <5) 2 ~, S < 6) 2 ~ and mixtures of the same.

The inorganic polysulfide solution is a red solution in which a dark coloration denotes a long chain polysulfide and a lighter color denotes a shorter chain polysulfide. The inorganic polysulfide solution thus prepared is used to impregnate the catalyst particles using an impregnation method of pore volume or by incipient moisture, such that the pores of the catalyst are filled without exceeding the volume of the catalyst. The amounts of sulfur used in the present process will depend on the amounts of catalytic metal present in the catalyst that needs to be converted to the sulfide. For example, a catalyst containing molybdenum would require two moles of sulfur or mono-sulfur compounds to convert each mol of molybdenum to molybdenum disulfide, making similar determinations for other metals. In regenerated catalysts, the existing sulfur levels can be factored into the calculations for the required amounts of sulfur.

The amount of sulfur typically present in the inorganic polysulfide solution in the present process is in the range of from 5 weight percent to 50 weight percent, based on the total weight of the solution. to be obtained by increasing the concentration of the starting ammonium sulfide solution The inorganic polysulfide solution will generally have a sulfur to sulfide ratio by weight in the range of from 2: 1 to 5: 1, and preferably in the range of 2: 1 to 3: 1 The amount of sulfur in the inorganic polysulfide solution is generally such that the amount of sulfur impregnated on the catalyst particles is typically an amount sufficient to provide the techyometric conversion of the metal components from the oxide form to the sulfide form, and is generally in the order of from 2 weight percent to 15 weight percent, and preferably from 4 p. or weight percent up to 12 weight percent, based on the total weight of the sulfided catalyst.

It has been found that the addition of sulfur presulphuration in descending amounts of up to about 50 percent of the requirement is tequio-metric resulting in catalysts having an adequate hydrodenitrification activity., which is an important property of hydrotreating and first stage hydrocracking catalysts. Thus, the amount of presulphurized sulfur used for incorporation into the catalyst will typically be in the order of from 0.2 to 1.5 times the amount is techiometric, and preferably from 0.4 to 1.2 times the amount is techyometric.

For hydrotreating / hydrocracking catalysts and tail gas treatment, which contain Group VIB and / or Group VIII metals, the amount of presulphurization sulfur employed is typically 1% to 15% by weight of the charged catalyst, and, preferably, the The sulfur amount of presulphurization employed is 4% to 12% by weight of the charged catalyst.

The impregnation step with sulfur will typically be carried out at a temperature in the range from 0 ° C to 30 ° C or more, up to 60 ° C. The lower temperature limit is set by the freezing point of the inorganic polysulfide solution under the specific impregnation conditions, while the upper temperature limit is set mainly by the decomposition of the inorganic polysulfide solution to volatile compounds and elemental sulfur. .

After impregnation of the catalyst particles with the inorganic polysulfide solution, the incorporated sulfur catalyst is subjected to a heat treatment in the presence of a fluent non-oxidizing gas, such as, for example, nitrogen, carbon dioxide, argon, helium and mixtures thereof, at a temperature sufficient to extract most of the water of residual pore volume and fix the sulfur on the catalyst. The heat treatment of the incorporated sulfur catalyst is preferably carried out using a ramp temperature method in which the incorporated sulfur catalyst is first heated to a temperature in the range of from 50 ° C to 150 ° C, preferably 120 ° C. ° C, to get most of the water out of pore volume. The catalyst is then ramped to a final retention temperature in the range of from 120 ° C to 400 ° C, and preferably from 230 ° C to 350 ° C, to fix the sulfur incorporated on the catalyst.

After this heat treatment, the catalyst is cooled to room temperature and rehydrated with a non-oxidizing gas saturated with water. The resulting catalyst is stable to handling in air.

The presulphurized or presulphurized catalyst of the present invention is then charged, for example, to a hydrotreating and / or hydrocracking reactor or tail gas reactor, the reactor is heated to operating conditions (eg hydrotreating and / or hydrocracking or tail gas treatment), and the catalyst is then immediately contacted with a hydrocarbon feedstock, without the need for extensive activation of the catalyst with hydrogen prior to contacting the catalyst with the hydrocarbon feedstock. Although limitation is not desired by any particular theory, it is believed that the extended period of hydrogen activation generally required for ex situ presulphurized catalysts is not necessary for the presulphurized catalysts according to the present invention because, in the present process, most of the sulfur has already reacted with the metal or metal oxides to form metal sulphides, or, alternatively, the sulfur is fixed to the pores of the catalyst to such an extent that it does not leave the pores of the catalyst before be converted to sulfur.

The process of the present invention is further applicable to the sulfurization of spent catalysts that have been oxy-regenerated. After a conventional oxy-regeneration process, an oxy-regenerated catalyst can be presulphurized as would a fresh catalyst in the above-stated manner.

The present process is particularly suitable for application to hydrotreating and / or hydrocracking catalysts or tail gas treatment. These catalysts typically comprise Group VIB and / or Group VIII metals supported on porous supports such as alumina, silica, silica-alumina and zeolites. The materials are well defined in the art and can be prepared by techniques described therein, such as U.S. Pat. Do not. 4. 530,911 and U.S. Pat. No. 4,520,128. Preferred hydrotreating and / or hydrocracking catalysts or tail gas treatment will contain a Group VIB metal selected from molybdenum, tungsten and mixtures thereof and a Group VIII metal selected from nickel, cobalt and mixtures thereof, supported on alumina. Versatile hydrotreating and / or hydrocracking catalysts that show good activity under various reactor conditions are nickel-molybdenum and cobalt-molybdenum catalysts supported on alumina. Sometimes phosphorus is added as a promoter. A versatile tail gas treatment catalyst that shows good activity under various reactor conditions is a cobal to-molybdenum catalyst supported on alumina.

The ex situ presulphurization method of this invention allows hydrotreating, hydrocracking and / or tail gas treatment reactors to be ripped out more quickly, providing an immediate contact with the hydrocarbon feedstock in the reactor and eliminating the activation step extensive with hydrogen which is necessary for conventional ex situ fused catalysts.

Thus, the present invention further provides a process for converting a hydrocarbon feedstock (ie, a hydrocarbon conversion process), which comprises contacting the feedstock with hydrogen at an elevated temperature in the presence of a pre-sulfurized catalyst according to the invention. to the invention.

The hydrotreating conditions comprise temperatures in the range from 100 ° C to 425 ° C and pressures above 40 atmospheres (4.05 MPa). The total pressure will typically be in the order of 400 to 2500 psig (2.76 to 17.23) MPa). The partial pressure of hydrogen will typically be in the order of from 200 to 2200 psig (1.38 to 15.17 MPa). The hydrogen feed rate will typically be in the order of 200 to 10,000 standard cubic feet per barrel ("SCF / BBL"). The raw material rate will typically have a liquid hourly space velocity ("LHSV") in the range of 0.1 to 15.

The hydrocracking conditions comprise temperatures in the range from 200 ° C to 500 ° C and pressures above 40 atmospheres (4.05 MPa). The total pressure will typically be in the order of 400 to 3000 psig (2.76 to 20.68) MPa). The partial pressure of hydrogen will typically be in the order of 300 to 2600 psig (2.07 to 17.93 MPa). The hydrogen feed rate will typically be in the order of 1000 to 10,000 standard cubic feet per barrel ("SCF / BBL"). The raw material rate will typically have a liquid hourly space velocity ("LHSV") in the range of from 0.1 to . First-stage hydrocracking reactors, which perform considerable hydrotreating of the raw material, can operate at temperatures higher than hydrotreatment reactors and at lower temperatures than second-stage hydrocracking reactors.

The hydrocarbon feedstocks to be hydrotreated or hydrocracked in the present process can vary within a wide boiling range. They include lighter fractions, such as kerosene fractions, as well as heavier fractions, such as gas oils, coker gas oils, vacuum gas oils, waste oils, short and long residues, catalytically cracked cycle oils, thermal cracked gas oils or catalytically, and crude synthesis, which are optionally originated from bituminous sands, shale oils, processes to improve the degree of waste or biomass. Combinations of various hydrocarbon oils can also be used.

The tail gas treatment reactors typically operate at temperatures in the range of 200 ° C to 400 ° C and at atmospheric pressure (101.3 kPa). Approximately 0.5-5% by volume of the tail gas fed to the reactor will comprise hydrogen. The standard gaseous hourly space velocities of the tail gas through the reactor are in the order of from 500 to 10,000 hr-1. There are several ways in which the present catalysts can be initiated in a tail gas treatment reactor. A tail gas or Claus unit feed can be used to initiate the present catalysts. Supplemental hydrogen can be provided, as required, by a gas burner operating at a sub-techyrometric ratio in order to produce hydrogen.

The invention will be described by the following examples which are provided for illustrative purposes.

Preparation of a Polysulfide Solution Inorganic An inorganic polysulfide solution for use in the following examples was prepared by adding 42 grams of elemental sulfur to a vigorously stirred solution of ammonium sulfide (150 milliliters, 22% by weight). The elemental sulfur immediately began to dissolve and the resulting solution became reddish-orange. The mixture was stirred until all the sulfur dissolved. The effective sulfur content of the solution was 30% by weight, and the weight ratio of sulfur to sulfur in the solution was 3.0.

Example 1.

A commercial hydrotreating catalyst having the properties indicated below was used to prepare the presulphurized catalysts.

Table A: Catalyst properties Nickel 3.0% by weight Molybdenum 13.0% by weight Phosphorus 3.5% by weight Alumina range support Surface Area, m / g 162 Vol. Water Pore, cc / g 0.47 Trilobal size 1/16 inch 2.94 cm) A 50 gram sample of the above catalyst was hydrated to equilibrium with air. The hydrated catalyst was then impregnated with 28.0 milliliters of the above inorganic polysulfide solution. This solution was added dropwise to a stirred bed of catalyst pellets contained in a 3N three-milliliter round bottom flask purged with nitrogen (0.5 liters / minute), using a syringe pump apparatus. The pedestal on which the round bottom flask was attached was vibrated using an FMC vibration table, with vibration amplitude established so as to create a drum bed of catalyst pellets. The resulting black pellets were then heated from room temperature to 121 ° C (250 ° F) for one hour. The catalyst was then ramped up to the final retention temperature of 260 ° C (500 ° F) and maintained for one hour. The final sulfur level was 9.3% by weight of the total catalyst. The sulfur content of the catalyst was analyzed using a carbon-sulfur analyzer SC-432 from LECO Corporation. The properties of the catalyst are indicated in Table 1 below.

Comparative Example A The commercial hydrotreating catalyst described in Example 1 above was subjected to the following sulphidation in situ process.

A sample of the catalyst was crushed and sieved to 15-45 mesh, loaded to a test unit that had a set pressure of sulfurization gas (5% H2S / 95% H2) of 1 atmosphere and a flow rate of 45 liters / hour. The temperature was then ramped from room temperature to 204 ° C to 0.5 ° C per minute and maintained at that temperature for two hours. The temperature was then increased to 371 ° C at a rate of 0.5 ° C per minute and maintained at that temperature for one hour and then cooled to room temperature. Then, the unit was changed to a flow of pure hydrogen and the established target rates and pressures, and then the hydrocarbon feed was introduced. The final sulfur level was 8.8% by weight of the total catalyst. The sulfur content of the catalyst was analyzed using a carbon-sulfur analyzer SC-432 from LECO Corporation. The properties of the catalyst are indicated in Table 1 below.

Catalyst Test The sulfurized catalyst in Example 1 above was used to hydrotreat a catalytically cracked heavy gas oil (CCHGO) in a slow continuous flow reactor. A sample of the catalyst was crushed and sieved to 16-45 mesh, diluted with silicon carbide and charged to a slow and continuous flow reactor tube. The reactor tube was pressurized to 1100 psig (7.6 MPa) with hydrogen at a flow rate of 45 liters per hour. The reactor was then heated to 93 ° C and a CCHGO feed was passed over the catalyst at a liquid hourly space velocity (LHSV) of 1.5. The temperature was ramped at a rate of 0.5 ° C per hour up to 332 ° C and then maintained for a period of sixty hours. Samples were then taken and analyzed to determine the activities of hydrogenation, hydrodesulfurization and hydrodesnitri fi cation. The rate constants are reported in relation to Comparative Example A.

Comparative Example A was tested in a manner similar to Example 1 above, except that, since the catalyst was sulfided by an in situ sulphidation method, the catalyst was not discharged from the reactor after sulfation.

The results are presented in Table 1 below.

As can be seen in Table 1, a presulphuring method according to the invention using an inorganic polysulfide solution is an effective means for incorporating sulfur into a hydrotreating catalyst (Example 1).

Table 1 NM = Not Measured 1 Reported as% of sulfur remaining in relation to the sulfur loaded on the catalyst 2 Relative to the sulfurized catalyst with H2S / H2 Example 2 A hydrocracking catalyst based on Ni-W / Zeolite and Ultrastable Z-763, available from Zeolyst International Inc., was presulphurized according to the procedure set forth below.

A 100 gram sample of the above catalyst was hydrated to equilibrium with air. The hydrated catalyst was then impregnated with 23.4 milliliters of the above inorganic polysulfide solution diluted to the water pore volume of 38.6 milliliters. This solution was added dropwise to a stirred bed of catalyst pellets contained in a 3N three-milliliter round bottom flask purged with nitrogen (0.5 liter / minute), using a syringe pump apparatus. The pedestal on which the round bottom flask was attached was vibrated using an FMC vibration table, with an established vibration amplitude so as to create a bed of catalyst pellet drums. The resulting black pellets were then heated from room temperature to 150 ° C for one hour. The catalyst was then ramped up to the final retention temperature of 343 ° C and maintained for one hour. After cooling to room temperature, the air-sensitive catalyst was rehydrated with a stream of nitrogen saturated with water, so that the catalyst could be handled safely in air for loading into the reactor. The final sulfur level was 7.48% by weight of the total catalyst. The sulfur content of the catalyst was analyzed using a carbon-sulfur analyzer SC-432 from LECO Corporation. The properties of the catalyst are indicated in Table 2 below.

Comparative Example B.

The commercial hydrocracking catalyst described in Example 2 above was subjected to the following in situ sulfurization process.

A sample of the catalyst was charged to a test unit that had a set pressure of sulfurization gas (5% H2S / H2) of 350 psig (2.4 MPa) and an established flow rate to give a gas hourly space velocity (GHSV) of 1500 (for example, for 40 milliliters of catalyst, the flow rate is 60 liters / hour). The temperature was then ramped from room temperature to 150 ° C in half an hour and then from 150 ° C to 370 ° C for a period of six hours. The temperature was then maintained at 370 ° C for two hours and then lowered to 150 ° C. Next, the unit was changed to a flow of pure hydrogen and the established target rates and pressures, and then a hydrocarbon feed was introduced. The final sulfur level was 5.45% by weight of the total catalyst. The sulfur content of the catalyst was analyzed using a carbon-sulfur analyzer SC-432 from LECO Corporation. The properties of the catalyst are indicated in Table 2 below.

Catalyst Test The sulfurized catalysts in Example 2 and in Comparative Example B above were used to hydrocrack a catalytically cracked and hydrotreated light gas oil in a slow continuous flow reactor. A sample of the catalyst was crushed and sieved to 16-45 mesh, diluted with silicon carbide and charged to a slow, continuous flow reactor tube. The reactor tube was pressurized to 1500 psig (10, 34 MPa) with hydrogen. The reactor was then heated to 150 ° C and a catalytically cracked and hydrotreated light gas oil feed was passed over the catalyst at a liquid hourly space velocity (LHSV) of 6.0. The ratio of hydrogen to feed in the reactor tube was 6500 standard cubic feet per barrel (SCF / BBL). The temperature was ramped up at a rate of 22 ° C per day for four days and at a rate of 6 ° C per day for five days up to a temperature of 260 ° C. The temperature was then adjusted to obtain an objective conversion of 12% by weight of 190 + ° C in the feed. The results are presented in Table 2 below.

Table 2 NJ NM = Not Measured 1 Normalized Sulfur = Sulfur Analyzed / (100 - (% by weight C +% by weight H)) x 100 2 Reported as% of sulfur remaining relative to the sulfur loaded on the catalyst 3 Temperature required for the conversion of objective hydrocracking. The target conversion is 12% by weight of 190 + ° C (375 + ° F) in the feed.

As can be seen in Table 2, the sulfur retention of a presulphurized catalyst according to the invention, in which an inorganic polysulfide solution (Example 2) is used, is 96%, indicating that essentially all of the sulfur remains on the catalyst after the heating step. In addition, the hydrocracking activity of the catalyst in Example 2 is equivalent to that of a presulphurized hydrocracking catalyst using a conventional in situ presulfurization method (Comparative Example B).

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (10)

Claims

1. A process for presulphurizing the porous particles of a sulfurizable catalyst containing at least one metal or metal oxide, characterized in that it comprises (a) impregnating the catalyst with an inorganic polysulphide solution to obtain a catalyst with incorporated sulfur in which less a portion of the sulfur or sulfur is incorporated in the pores of the catalyst; and (b) heating the catalyst with incorporated sulfur in the presence of a non-oxidizing atmosphere.

2. A process according to claim 1, characterized in that the inorganic polysulfide solution comprises polysulfide ions of general formula S (xj2 ~ where x is an integer having a value of at least 3.

3. A process according to claim 1 or claim 2, characterized in that the inorganic polysulfide solution is prepared by dissolving elemental sulfur in an aqueous solution of ammonium sulphide or ammonium derivative.

4. A process according to any one of claims 1 to 3, characterized in that the inorganic polysulfide solution contains an amount of sulfur in the range of from 5 weight percent to 50 weight percent, based on the total weight of the solution .

5. A process according to any one of the preceding claims, characterized in that, before step a), the catalyst containing at least one metal or metal oxide is hydrated to equilibrium with air

6. A process according to any one of the preceding claims, characterized in that the impregnation in step a) is carried out at a temperature in the range from 0 ° C to 60 ° C.

7. A process according to any one of the preceding claims, characterized in that the heating in step b) is carried out at a temperature in the range of from 50 ° C to 400 ° C.

8. A process according to any one of the preceding claims, characterized in that the heating in step b) is carried out in the presence of a non-oxidizing gas selected from the group consisting of nitrogen, carbon dioxide, argon, helium and mixtures thereof.

9. A presulphurized catalyst, characterized in that it can be obtained by a process as claimed in any one of the preceding claims.

10. A process for converting a hydrocarbon feedstock, characterized in that it comprises contacting the feedstock with nitrogen at elevated temperature in the presence of a presulphurized catalyst according to claim 9.