A hydrocracking catalyst and its preparation method and application

Abstract

The present invention discloses a hydrocracking catalyst, its preparation method, and its application. The catalyst comprises a support and an active metal selected from Group VIB and Group VIII metals. In the hydrocracking catalyst, the atomic ratio of the tetracoordinated Group VIB metal species to the hexacoordinated Group VIB metal species is 25:1 to 4:1. The hydrocracking catalyst of the present invention has low hydrogen consumption, excellent stability, and can extend the operating cycle of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrocracking, and in particular to a hydrocracking catalyst, a preparation method thereof and an application thereof. Background Art

[0002] With increasingly stringent environmental regulations, the quality requirements for clean oil products are gradually increasing. Hydrocracking technology, as a clean and environmentally friendly technology, can convert low-quality crude oil into high-value-added products, including light naphtha, heavy naphtha, jet fuel, diesel, and specialty oils. While hydrocracking technology is highly adaptable to feedstocks, it can also be prone to degradation of hydrogenation performance and stability due to catalyst desulfurization when processing some low-sulfur, high-nitrogen feedstocks. This has even forced some hydrocracking units to shut down prematurely due to catalyst desulfurization.

[0003] The active metals of hydrocracking catalysts are generally nickel, cobalt, molybdenum, tungsten, etc. These metals generally exist in an oxidized state before sulfidation, but the molybdenum species or tungsten species with high coordination numbers on the catalyst surface are easy to reduce and have poor stability.

[0004] Therefore, developing a highly stable hydrocracking catalyst to improve the catalyst's ability to resist sulfur loss is of great significance for extending the catalyst's service life and the unit's operating cycle.

[0005] CN105080548A discloses a method for improving the selectivity and stability of nickel-based liquid-phase hydrogenation catalysts. This method is applicable to nickel-based liquid-phase hydrogenation catalysts synthesized by coprecipitation. During the active metal loading process, a soluble salt alkaline additive is added to the nickel metal solution to reduce the surface acidity of the catalyst. After adding the alkaline additive, the catalyst prepared by this method has improved selectivity and stability. However, the catalyst prepared by this method is suitable for the hydrogenation of fatty aldehydes and has a limited scope of application.

[0006] CN112047843A discloses a method for improving the stability of a fixed-bed meta-xylenediamine hydrogenation catalyst. This method involves loading a protective agent, barium-modified magnesium oxide, and a hydrogenation catalyst in a fixed-bed reactor in a graded manner. Meta-xylenediamine is hydrogenated in an ammonia atmosphere to synthesize 1,3-cyclohexanedimethylamine. The protective agent is a cobalt catalyst supported on barium-modified magnesium oxide. This method, by loading the protective agent before the hydrogenation catalyst, can extend the service life of the hydrogenation catalyst. This method is also simple to implement and readily industrializable. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention provides a hydrocracking catalyst and its preparation method and application. The hydrocracking catalyst prepared by the method of the present invention can improve the stability of the hydrocracking catalyst and achieve the purpose of extending the operating cycle of the device.

[0008] A first aspect of the present invention provides a hydrocracking catalyst comprising: a carrier and an active metal, wherein the active metal is selected from Group VIB metals and Group VIII metals, and wherein the ratio of the tetracoordinated Group VIB metal species to the hexacoordinated Group VIB metal species in terms of atoms is 25:1 to 4:1, preferably 20:1 to 5:1.

[0009] Furthermore, the hydrocracking catalyst further comprises an additive, wherein the additive is carbon, and the carbon is derived from at least one of carbon-containing substances such as coke and graphite.

[0010] Furthermore, the carrier includes a cracking component, and the cracking component is a molecular sieve and / or amorphous silica-alumina. The molecular sieve is at least one of a Y molecular sieve and a Beta molecular sieve.

[0011] Furthermore, the carrier further comprises aluminum oxide and / or a binder, and the binder is derived from aluminum sol.

[0012] Furthermore, the Group VIB metal is selected from W and / or Mo, and the Group VIII metal is selected from Co and / or Ni.

[0013] Furthermore, based on the weight of the hydrocracking catalyst, the content of the active metal in terms of oxide is 20% to 50%, preferably 25% to 40%; the content of the carrier is 50% to 80%, preferably 60% to 75%, wherein the content of molecular sieve and / or amorphous silica-alumina in the carrier is 5% to 40%, preferably 10% to 35%, and among the active metals, the content of Group VIII metal in terms of oxide is 2% to 20%, preferably 3% to 15%, and the content of Group VIB metal in terms of oxide is 12% to 45%, preferably 15% to 35%.

[0014] Furthermore, the content of the additive is less than 12% based on the weight of the hydrocracking catalyst.

[0015] Furthermore, the content of the binder is 8% or less based on the weight of the hydrocracking catalyst.

[0016] A second aspect of the present invention provides a method for preparing the above-mentioned hydrocracking catalyst, comprising:

[0017] (1) impregnating a support raw material with a solution containing an active metal precursor, followed by drying and calcining to obtain a hydrocracking catalyst intermediate;

[0018] (2) mixing the hydrocracking catalyst intermediate obtained in step (1) with an additive component, and calcining under an inert gas; when the mass loss of the hydrocracking catalyst intermediate is 60% to 100%, preferably 65% ​​to 90%, of the amount of the additive component added, cooling and stopping the calcination to obtain a hydrocracking catalyst powder;

[0019] (3) Mixing the hydrocracking catalyst powder with a binder, forming, drying, and calcining to obtain a hydrocracking catalyst.

[0020] Furthermore, in step (1), the active metal precursor is selected from at least one of its soluble salts. For example, when Mo is selected as the main active metal, the precursor is selected from at least one of ammonium molybdate, ammonium molybdate tetrahydrate, ammonium molybdate hexahydrate, and sodium molybdate, preferably ammonium molybdate hexahydrate. When W is selected as the main active metal, the precursor is selected from at least one of sodium tungstate, ammonium paratungstate, and ammonium metatungstate, preferably ammonium metatungstate. When Ni is selected as the auxiliary active metal, the precursor is selected from at least one of nickel sulfate, nickel nitrate, and nickel nitrate hexahydrate, preferably nickel nitrate hexahydrate. When Co is selected as the auxiliary active metal, the precursor is selected from at least one of cobalt sulfate, cobalt nitrate, and cobalt chloride, preferably cobalt nitrate.

[0021] Furthermore, the impregnation method in step (1) can be at least one of an equal volume impregnation method, an excess volume impregnation method and a steam impregnation method, preferably an equal volume impregnation method.

[0022] Furthermore, in step (1), the drying temperature is 40 to 100° C., preferably 60 to 100° C., and the drying time is 2 to 12 hours, preferably 4 to 10 hours.

[0023] Furthermore, in step (1), the calcination temperature is 200-600° C., preferably 300-500° C., the calcination time is 2-12 h, preferably 4-6 h, and the calcination atmosphere is air or oxygen.

[0024] Furthermore, in step (2), the mass ratio of the hydrocracking catalyst intermediate to the coke is 30:1 to 5:1, preferably 15:1 to 6:1.

[0025] Furthermore, in step (2), the inert gas is at least one of nitrogen, helium, argon and the like, and the calcination temperature is 300-800°C.

[0026] Furthermore, in step (2), the calcination is carried out in two stages. The first stage calcination conditions are as follows: the calcination temperature is increased from room temperature to 300-400°C at a rate of 3-18°C / h, preferably 4-15°C / h, and a first constant temperature is performed, and the first constant temperature time is 2-8 hours; the second stage calcination conditions are as follows: the calcination temperature is further increased at a rate of 2-8°C / h, preferably 3-6°C / h, to 410-800°C, and a second constant temperature is performed, and the second constant temperature time is determined according to the weight loss of the hydrocracking catalyst intermediate.

[0027] Furthermore, in step (3), the adhesive component is selected from at least one of aluminum sol, sesbania powder, etc., preferably sesbania powder.

[0028] Furthermore, in step (3), mixing and molding can be carried out in a conventional manner in the art, such as molding after sufficient rolling, and the molded shape can be at least one of a clover, a four-leaf clover, a cylinder, and a tooth ball.

[0029] Furthermore, in step (3), the drying temperature is 40 to 120° C., preferably 60 to 100° C.; and the drying time is 2 to 24 hours, preferably 4 to 10 hours.

[0030] Furthermore, in step (3), the calcination temperature is 300-500° C., preferably 350-450° C.; and the calcination time is 3-12 h, preferably 4-10 h.

[0031] The third aspect of the present invention provides the use of the above hydrocracking catalyst in the production of heavy naphtha by diesel hydrocracking.

[0032] Furthermore, the feedstock for producing heavy naphtha by hydrocracking is a low-sulfur, high-nitrogen diesel feedstock having a sulfur content of 200 to 1200 ppm, preferably 400 to 1000 ppm, and a nitrogen content of 300 to 1500 ppm, preferably 400 to 1200 ppm, by mass.

[0033] Furthermore, in the production of heavy naphtha by hydrocracking, the reaction conditions of hydrocracking are generally as follows: reaction pressure of 6.0-18.0 MPa, hydrocracking reaction temperature of 300-460°C, volume space velocity of 0.5-8.0 h -1 Preferably, the reaction pressure is 8.0-15.0 MPa, the hydrocracking reaction temperature is 320-390°C, and the volume space velocity in the hydrocracking section is 1.0-4.0 h -1 .

[0034] Furthermore, the diesel hydrocracking process produces heavy naphtha with a high liquid yield, which can be as high as 95 wt % or more, and a high yield and aromatic potential of the obtained heavy naphtha.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention increases the proportion of high-stability active metals and improves the stability and activity of the catalyst when processing low-sulfur, high-nitrogen feedstocks by adding coke during the preparation of the hydrocracking catalyst and reducing some high-coordination oxidation state metals in an inert gas.

[0037] (2) When the hydrocracking catalyst of the present invention is used for diesel hydrocracking to produce heavy naphtha, the liquid yield is high, reaching over 95%, the yield and aromatic potential of the produced heavy naphtha are high, and the hydrogen consumption of the device is low.

[0038] (3) In the catalyst preparation method of the present invention, a two-stage calcination method is adopted, and the crystal phase transformation process of the catalyst active phase is smooth, and the degree of carbon to oxidized metal can be accurately controlled to achieve the target property requirements. DETAILED DESCRIPTION

[0039] The hydrocracking catalyst provided by the present invention, its preparation method and application will be further described below in conjunction with the examples to compare and demonstrate the effects and advantages of the hydrocracking catalyst prepared by the preparation method of the present invention, but the present invention is not limited thereto.

[0040] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, were purchased from conventional biochemical reagent stores.

[0041] In the present invention, the ratio of the tetracoordinated VIB Group metal species to the hexacoordinated VIB Group metal species is analyzed using an H2-TPR instrument. The reduction peak attributable to the hexacoordinated species in the first low-temperature zone and the reduction peak attributable to the tetracoordinated species in the second high-temperature zone are split and fitted to obtain the ratio of the VIB Group metal species with different coordination numbers. This ratio is calculated as the metal atomic ratio.

[0042] The properties of the feedstock oils used in the following Examples and Comparative Examples are shown in Table 1. In the Examples and Comparative Examples, the refining reactors were all loaded with FF-66 hydrofining catalyst, while the cracking reactors were loaded with the hydrocracking catalyst prepared according to the present invention in the Examples and the hydrocracking catalyst used in the Comparative Examples. The physical properties of each catalyst are shown in Table 2. Both the Examples and Comparative Examples were evaluated for 2500 hours under the conditions shown in Table 3 to examine the stability of the different catalysts. The evaluation results for the Examples are shown in Table 4, and the evaluation results for the Comparative Examples are shown in Table 5.

[0043] In the present invention, unless otherwise specified, percentages refer to mass fractions.

[0044] The bracketed order in this invention is only for the convenience of reading and review and has no particular order.

[0045] Example 1

[0046] The catalyst preparation method of this embodiment is as follows: γ-alumina and Y molecular sieve are used as carrier raw materials, ammonium metatungstate is used as the tungsten source, and nickel nitrate hexahydrate is used as the nickel source. A solution of a certain concentration is prepared and the carrier is impregnated by an equal volume co-impregnation method. After drying at 80°C for 6 hours, it is calcined at 400°C for 4 hours. Based on the weight of the hydrocracking catalyst intermediate, the obtained hydrocracking catalyst intermediate has an alumina content of 45%, a Y molecular sieve content of 25%, a WO3 content of 25% by weight, and a NiO content of 5% by weight, respectively. After mixing a hydrocracking catalyst intermediate with coke in a mass ratio of 12:1, the calcination temperature was first increased to 380°C at a heating rate of 4°C / h under a nitrogen atmosphere and held at that temperature for 3 hours. The calcination temperature was then increased to 600°C at a rate of 5°C / h. When the mass loss of the hydrocracking catalyst intermediate reached 85% by weight of the coke added, the calcination temperature was rapidly reduced and the calcination was stopped to obtain a hydrocracking catalyst powder. A binder of sesbania powder (4% by weight relative to the weight of the hydrocracking catalyst powder) was added to the powder, and the catalyst was extruded to obtain a shaped catalyst. The shaped catalyst was then dried at 80°C for 4 hours and calcined at 300°C for 4 hours to obtain a finished hydrocracking catalyst, HC-1.

[0047] The ratio of tetracoordinated W(Td) species to hexacoordinated W(Oh) species in the HC-1 catalyst was 12:1. The HC-1 catalyst was loaded into a hydrocracking reactor and an evaluation experiment was conducted for 2500 h according to the conditions in Table 3.

[0048] Example 2

[0049] The catalyst preparation method of this embodiment is as follows: γ-alumina and Y molecular sieve are used as carrier raw materials, ammonium metatungstate is used as the tungsten source, and nickel nitrate hexahydrate is used as the nickel source. A solution of a certain concentration is prepared and the carrier is impregnated by an equal volume co-impregnation method. After drying at 80°C for 6 hours, it is calcined at 400°C for 4 hours. Based on the weight of the hydrocracking catalyst intermediate, the obtained hydrocracking catalyst intermediate has an alumina content of 48%, a Y molecular sieve content of 22%, a WO3 content of 24% by weight, and a NiO content of 6% by weight, respectively. After mixing a hydrocracking catalyst intermediate with coke in a mass ratio of 10:1, the calcination temperature was first increased to 360°C at a heating rate of 4°C / h under a nitrogen atmosphere and held at that temperature for 3 hours. The calcination temperature was then increased to 650°C at a rate of 5°C / h. When the mass loss of the hydrocracking catalyst intermediate reached 80% by weight of the coke added, the calcination temperature was rapidly reduced and the calcination was stopped to obtain a hydrocracking catalyst powder. A binder of sesbania powder (4% by weight relative to the weight of the hydrocracking catalyst powder) was added to the powder, and the catalyst was extruded to obtain a shaped catalyst. The shaped catalyst was then dried at 80°C for 4 hours and calcined at 300°C for 4 hours to obtain a finished hydrocracking catalyst, HC-2.

[0050] The ratio of tetracoordinated W(Td) species to hexacoordinated W(Oh) species in the HC-2 catalyst was 10:1. The HC-2 catalyst was loaded into a hydrocracking reactor and an evaluation experiment was conducted for 2500 h according to the conditions in Table 3.

[0051] Example 3

[0052] The catalyst preparation method of this embodiment is as follows: γ-alumina and Y molecular sieve are used as carrier raw materials, ammonium metatungstate is used as the tungsten source, and nickel nitrate hexahydrate is used as the nickel source. A solution of a certain concentration is prepared and the carrier is impregnated by an equal volume co-impregnation method. After drying at 80°C for 6 hours, it is calcined at 400°C for 4 hours. Based on the weight of the hydrocracking catalyst intermediate, the obtained hydrocracking catalyst intermediate has an alumina content of 48%, a Y molecular sieve content of 22%, a WO3 content of 24% by weight, and a NiO content of 6% by weight, respectively. After mixing a hydrocracking catalyst intermediate with coke in a mass ratio of 10:1, the calcination temperature was first increased to 360°C at a heating rate of 3°C / h under a nitrogen atmosphere and held at that temperature for 3 hours. The calcination temperature was then increased to 650°C at a rate of 8°C / h. When the mass loss of the hydrocracking catalyst intermediate reached 80% of the coke added, the calcination temperature was rapidly reduced and the calcination was stopped to obtain a hydrocracking catalyst powder. A binder of sesbania powder (4% by weight relative to the weight of the hydrocracking catalyst powder) was added to the powder, and the catalyst was extruded to obtain a shaped catalyst. The shaped catalyst was then dried at 80°C for 4 hours and calcined at 300°C for 4 hours to obtain the finished hydrocracking catalyst HC-3.

[0053] The ratio of tetracoordinated W(Td) species to hexacoordinated W(Oh) species in the HC-3 catalyst is 4:1. The HC-3 catalyst was loaded into a hydrotreating reactor and an evaluation experiment was conducted for 2500 hours according to the conditions in Table 3.

[0054] Comparative Example 1

[0055] A solution of a certain concentration was prepared using γ-alumina and Y molecular sieve as the carrier raw materials, ammonium metatungstate as the tungsten source, and nickel nitrate hexahydrate as the nickel source. The carrier was impregnated using an equal volume co-impregnation method, dried at 80°C for 6 hours, and then calcined at 400°C for 4 hours. Based on the weight of the hydrocracking catalyst intermediate, the resulting hydrocracking catalyst intermediate had an alumina content of 48%, a Y molecular sieve content of 22%, a WO3 content of 24%, and a NiO content of 6% (based on the weight of the hydrocracking catalyst intermediate). A binder of sesbania powder (4% by weight, relative to the weight of the hydrocracking catalyst intermediate) was added to the powder, and the catalyst was extruded to obtain a shaped catalyst. The shaped catalyst was then dried at 80°C for 4 hours and calcined at 300°C for 4 hours to obtain the finished hydrocracking catalyst, Catalyst-1.

[0056] The ratio of tetracoordinated W(Td) species to hexacoordinated W(Oh) species in the Catalyst-1 catalyst is 1:3. The prepared hydrocracking catalyst was loaded into a hydrocracking reactor and subjected to a 2500 h stability test according to the conditions in Table 3.

[0057] Comparative Example 2

[0058] The catalyst preparation method of this comparative example is as follows: γ-alumina and Y molecular sieve are used as carrier raw materials, ammonium metatungstate is used as tungsten source, and nickel nitrate hexahydrate is used as nickel source. A solution of a certain concentration is prepared, and the carrier is impregnated by an equal volume co-impregnation method. After drying at 70°C for 6 hours, it is calcined at 420°C for 4 hours. Based on the weight of the hydrocracking catalyst intermediate, the hydrocracking catalyst intermediate having an alumina content of 50%, a Y molecular sieve content of 20%, a WO3 content of 24wt%, and a NiO content of 6wt% is obtained, respectively, in terms of WO3 and NiO. After the hydrocracking catalyst intermediate is mixed with coke in a mass ratio of 3:1, the calcination temperature is first increased to 360°C at a heating rate of 4°C / h under a nitrogen environment and calcined at a constant temperature. When the mass loss of the hydrocracking catalyst intermediate is 80wt% of the coke addition amount, the calcination temperature is rapidly reduced and the calcination is stopped to obtain a hydrocracking catalyst powder. 4 wt% (relative to the weight of the hydrocracking catalyst powder) of binder sesbania powder was added to the powder, and a shaped catalyst was obtained by extrusion. The shaped catalyst was dried at 80° C. for 4 h and calcined at 300° C. for 4 h to obtain a finished hydrocracking catalyst Catalyst-2.

[0059] The ratio of tetracoordinated W(Td) species to hexacoordinated W(Oh) species in the Catalyst-2 catalyst was 32:1. The Catalyst-2 catalyst was loaded into a hydrotreating reactor and evaluated for 2500 h under the conditions shown in Table 3.

[0060] Comparative Example 3

[0061] The catalyst preparation method of this comparative example is as follows: γ-alumina and Y molecular sieve are used as carrier raw materials, ammonium metatungstate is used as tungsten source, and nickel nitrate hexahydrate is used as nickel source. A solution of a certain concentration is prepared, and the carrier is impregnated by an equal volume co-impregnation method. After drying at 80°C for 6 hours, it is calcined at 400°C for 4 hours. Based on the weight of the hydrocracking catalyst intermediate, the hydrocracking catalyst intermediate having an alumina content of 48%, a Y molecular sieve content of 22%, a WO3 content of 24wt%, and a NiO content of 6wt% is obtained, respectively, in terms of WO3 and NiO. After the hydrocracking catalyst intermediate is mixed with coke in a mass ratio of 10:1, it is directly calcined at a constant temperature at 360°C under a nitrogen environment. When the mass loss of the hydrocracking catalyst intermediate is 80wt% of the coke addition amount, the calcination temperature is rapidly reduced and the calcination is stopped to obtain a hydrocracking catalyst powder. 4 wt% (relative to the weight of the hydrocracking catalyst powder) of binder sesbania powder was added to the powder, and a shaped catalyst was obtained by extrusion. The shaped catalyst was dried at 80° C. for 4 h and calcined at 300° C. for 4 h to obtain a finished hydrocracking catalyst HC-4.

[0062] The ratio of tetracoordinated W(Td) species to hexacoordinated W(Oh) species in the HC-4 catalyst was 2:1. The HC-4 catalyst was loaded into a hydrocracking reactor and an evaluation experiment was conducted for 2500 h according to the conditions in Table 3.

[0063] Table 1 Properties of crude oil

[0064] Raw oil name Diesel feedstock <![CDATA[Density (20 °C) / g·cm -3 > 0.86 Distillation range / ℃ 215～366 S, ppm 350 N, ppm 460

[0065] Table 2 Industrial catalysts

[0066] Industrial agents FF-66 Physical and chemical properties - Pore ​​diameter / nm 2~10nm <![CDATA[Pore volume / mL·g -1 > ≥0.25 <![CDATA[Specific surface area / m 2 ·g -1 > ≥180 shape Gear Ball <![CDATA[Loading heap ratio, g / cm 3 > 0.75

[0067] Table 3 Evaluation conditions

[0068] Reaction pressure, MPa 10.0 <![CDATA[Volume space velocity of refining agent, h -1 > 2.0 <![CDATA[Volume space velocity of cracking agent, h -1 > 1.5 Nitrogen content of refined oil, ppm 10 Hydrocracking conversion rate, % 65 Hydrogen-to-oil ratio at the inlet of hydrotreating reactor / hydrocracking reactor 800:1 / 1200:1 Running time, h 2500

[0069] Table 4 Example test results

[0070]

[0071]

[0072] Table 5 Comparative Example Test Results

[0073] project Comparative Example 1 Comparative Example 2 Comparative Example 3 Total liquid yield, wt% 92.8 92.9 94.5 Heavy naphtha yield, wt% 47.6 47.8 48.2 Heavy naphtha aromatic potential, wt% 47.9 48.2 49.0 Diesel sulfur content, ppm 15.0 12.3 10.0 Hydrogen consumption, wt% 2.16 2.14 2.10 Cracking catalyst deactivation rate, ℃ / d 0.052 0.055 0.043

[0074] It can be seen from the experimental results of the comparative examples and the embodiments that, under the condition of controlling the same conversion rate, the use of the hydrocracking catalyst of the present invention not only has high liquid yield, high heavy naphtha yield, high aromatic potential, low hydrogen consumption, but also has a slow catalyst deactivation rate.

Claims

1. A hydrocracking catalyst comprising a support and an active metal, wherein the active metal is selected from a Group VIB metal and a Group VIII metal, wherein the ratio of the tetracoordinate Group VIB metal species to the hexacoordinate Group VIB metal species in the hydrocracking catalyst is 25:1 to 4:1 on an atomic basis; The content of Group VIB metal in the form of oxide is 12% to 45% based on the weight of the hydrocracking catalyst; The hydrocracking catalyst further comprises an additive, wherein the additive is carbon, and the carbon is derived from at least one of coke and graphite; The hydrocracking catalyst is prepared by the following method, which comprises: (1) impregnating a support raw material with a solution containing an active metal precursor, followed by drying and calcining to obtain a hydrocracking catalyst intermediate; (2) mixing the hydrocracking catalyst intermediate obtained in step (1) with the additive component, and calcining under inert gas. When the mass loss of the hydrocracking catalyst intermediate is 60% to 100% of the amount of the additive added, cooling and stopping the calcination to obtain a hydrocracking catalyst powder; (3) The hydrocracking catalyst powder is mixed with a binder, molded, dried, and calcined to obtain a hydrocracking catalyst.

2. The hydrocracking catalyst according to claim 1, characterized in that In the hydrocracking catalyst, the ratio of the tetracoordinated VIB Group metal species to the hexacoordinated VIB Group metal species is 20:1 to 5:1 in terms of atoms.

3. The hydrocracking catalyst according to claim 1, characterized in that The carrier includes a cracking component, which is a molecular sieve and / or amorphous silica-alumina.

4. The hydrocracking catalyst according to claim 1, characterized in that The support also includes alumina.

5. The hydrocracking catalyst according to claim 1, characterized in that The support further comprises a binder, which is derived from an aluminum sol.

6. The hydrocracking catalyst according to claim 1, characterized in that The Group VIB metal is selected from W and / or Mo, and the Group VIII metal is selected from Co and / or Ni.

7. The hydrocracking catalyst according to any one of claims 1 to 6, characterized in that: Based on the weight of the hydrocracking catalyst, the content of the active metal in terms of oxide is 20% to 50%; the content of the carrier is 50% to 80%, wherein the content of the molecular sieve and / or amorphous silica-alumina in the carrier is 5% to 40%, and the content of the Group VIII metal in the active metal in terms of oxide is 2% to 20%.

8. The hydrocracking catalyst according to claim 7, characterized in that Based on the weight of the hydrocracking catalyst, the content of the active metal in terms of oxide is 25% to 40%; the content of the carrier is 60% to 75%, wherein the content of the molecular sieve and / or amorphous silica-alumina in the carrier is 10% to 35%, and among the active metals, the content of the Group VIII metal in terms of oxide is 3% to 15%, and the content of the Group VIB metal in terms of oxide is 15% to 35%.

9. The method for preparing the hydrocracking catalyst according to any one of claims 1 to 8, comprising: (1) impregnating a support raw material with a solution containing an active metal precursor, followed by drying and calcining to obtain a hydrocracking catalyst intermediate; (2) mixing the hydrocracking catalyst intermediate obtained in step (1) with the additive component, and calcining under inert gas. When the mass loss of the hydrocracking catalyst intermediate is 60% to 100% of the amount of the additive added, cooling and stopping the calcination to obtain a hydrocracking catalyst powder; (3) The hydrocracking catalyst powder is mixed with a binder, molded, dried, and calcined to obtain a hydrocracking catalyst.

10. The preparation method according to claim 9, characterized in that In step (2), the hydrocracking catalyst intermediate obtained in step (1) is mixed with the additive component and calcined under an inert gas. When the mass loss of the hydrocracking catalyst intermediate is 65-90% of the amount of the additive added, the temperature is lowered and the calcination is stopped to obtain a hydrocracking catalyst powder.

11. The preparation method according to claim 9, characterized in that In step (1), the drying temperature is 40-100° C., the drying time is 2-12 h, and / or the roasting temperature is 200-600° C., the roasting time is 2-12 h, and the roasting atmosphere is air or oxygen.

12. The preparation method according to claim 11, characterized in that In step (1), the drying temperature is 60-100° C., the drying time is 4-10 hours, and / or the roasting temperature is 300-500° C., and the roasting time is 4-6 hours.

13. The preparation method according to claim 9, characterized in that In step (2), the mass ratio of the hydrocracking catalyst intermediate to the coke is 30:1 to 5:

1.

14. The preparation method according to claim 13, characterized in that In step (2), the mass ratio of the hydrocracking catalyst intermediate to the coke is 15:1 to 6:

1.

15. The preparation method according to claim 9, characterized in that In step (2), the inert gas is at least one of nitrogen, helium, and argon, and the calcination temperature is 300-800°C.

16. The preparation method according to claim 9, characterized in that In step (2), the roasting is carried out in two stages. The roasting conditions of the first stage are: the roasting temperature is increased from room temperature to 300-400°C at a rate of 3-18°C / h, and a first constant temperature is performed, and the first constant temperature time is 2-8h; the roasting conditions of the second stage are: the roasting temperature is further increased to 410-800°C at a rate of 2-8°C / h, and a second constant temperature is performed, and the second constant temperature time is determined according to the weight loss of the hydrocracking catalyst intermediate.

17. The preparation method according to claim 16, characterized in that In step (2), in the first stage of roasting conditions, the roasting temperature is increased from room temperature to 300~400°C at a rate of 4~15°C / h, and the first constant temperature is performed; in the second stage of roasting conditions, the roasting temperature is further increased to 410~800°C at a rate of 3~6°C / h, and the second constant temperature is performed.

18. The preparation method according to claim 9, characterized in that In step (3), the drying temperature is 40-120° C., the drying time is 2-24 h, and / or the roasting temperature is 300-500° C., and the roasting time is 3-12 h.

19. The preparation method according to claim 18, characterized in that In step (3), the drying temperature is 60-100° C., the drying time is 4-10 h, and / or the roasting temperature is 350-450° C., the roasting time is 4-10 h.

20. Use of the hydrocracking catalyst according to any one of claims 1 to 8 in producing heavy naphtha by diesel hydrocracking.

21. The use according to claim 20, characterized in that The raw material for producing heavy naphtha by hydrocracking is a low-sulfur, high-nitrogen raw material, wherein the low-sulfur, high-nitrogen raw material has a sulfur content of 200-1200 ppm and a nitrogen content of 300-1500 ppm by mass.

22. The use according to claim 21, characterized in that The raw material for producing heavy naphtha by hydrocracking is a low-sulfur, high-nitrogen raw material, wherein the low-sulfur, high-nitrogen raw material has a sulfur content of 200-1200 ppm and a nitrogen content of 300-1500 ppm by mass.

23. The use according to claim 20, characterized in that The reaction conditions of hydrocracking are as follows: reaction pressure of 6.0-18.0 MPa, hydrocracking reaction temperature of 300-460°C, volume space velocity of 0.5-8.0 h -1 .

24. The use according to claim 23, characterized in that The reaction conditions of hydrocracking are: reaction pressure of 8.0-15.0 MPa, hydrocracking reaction temperature of 320-390°C, volume space velocity of hydrocracking section of 1.0-4.0 h -1 .

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