Wax oil hydrocracking catalysts, their preparation and use

Abstract

This invention discloses a wax oil hydrocracking catalyst, its preparation, and its application. The catalyst mainly comprises the following components by weight: 1-30 parts of mesoporous-microporous SBA-15 / HY composite molecular sieve; 15-40 parts of amorphous silica-alumina; 5-30 parts of mesoporous alumina; 10-30 parts of oxides of metal W or Mo; 1-8 parts of oxides of metal Co or Ni; 1.0-5.0 parts of extrusion aid; and 3-8 parts of binder. The mesoporous-microporous SBA-15 / HY composite molecular sieve is prepared under ultrasonic emulsification. The wax oil hydrocracking catalyst provided by this invention can operate stably for long periods when processing inferior wax oil feedstock.

Description

Technical Field

[0001] This invention relates to a catalyst for the hydrocracking of wax oil, its preparation, and its application. Background Technology

[0002] Hydrocracking technology is a crucial method for the deep processing of heavy oil, boasting numerous advantages such as strong feedstock adaptability, flexible processing schemes, high liquid product yields, and good product quality. In particular, heavy naphtha has a high aromatic content, making it a high-quality feedstock for catalytic reforming to produce aromatics or high-octane gasoline. Hydrocracking tail oil and light naphtha are rich in alkanes, making them excellent feedstocks for steam cracking to ethylene plants. Simultaneously, it can also produce high-quality No. 3 jet fuel and blending components for clean diesel fuel meeting the China VI emission standard. Hydrocracking technology has gradually developed into a key secondary processing technology for modern refining enterprises to directly produce clean oil products and high-quality chemical raw materials from inferior wax oil. It is also the core of refining structure adjustment and transformation and upgrading. The core of hydrocracking technology lies in the development and optimization of high-performance hydrocracking catalysts.

[0003] Hydrocracking catalysts used in industrial applications mainly consist of alumina, molecular sieves, active metals, and silica-alumina oxides. Alumina, molecular sieves, and silica-alumina oxides form the support, whose primary function is to provide suitable acidic sites during the hydrocracking reaction to promote the breaking of chemical bonds in heavy oil molecules, while also providing abundant specific surface area. The active metal primarily provides the hydrogenation function. In existing methods, the acidic components of hydrocracking catalysts are mostly provided by Y-type molecular sieves, combinations of Y and β molecular sieves, or combinations of Y and SAPO-34 molecular sieves. Summary of the Invention

[0004] This invention aims to increase the hydroxyl density on the surface of the hydrocracking catalyst support, improve the metal dispersion in the catalyst, reduce the interaction between the support and the metal in the catalyst, and enhance the synergistic effect between the hydrogenation center and the acid center while improving the metal utilization rate, so as to enable the hydrocracking catalyst to operate stably for a long period of time when processing inferior wax oil feedstock.

[0005] As a first aspect of the present invention, a catalyst for the hydrocracking of wax oil is disclosed, which mainly comprises the following components by weight: 1-30 parts of mesoporous-microporous SBA-15 / HY composite molecular sieve; 15-40 parts of amorphous silica-alumina; 5-30 parts of mesoporous alumina; 10-30 parts of oxides of metal W or Mo; 1-8 parts of oxides of metal Co or Ni; 1.0-5.0 parts of extrusion aid; and 3-8 parts of binder.

[0006] The mesoporous-microporous SBA-15 / HY composite molecular sieve was prepared by ultrasonic emulsification.

[0007] In one or more optional embodiments, the mesoporous SBA-15 / HY composite molecular sieve has a grain size of 150-300 nm and a specific surface area of ​​510-550 m². 2 / g, pore volume is 0.60~0.75ml / g, pore size distribution is 7.5~8.5nm, and total acidity is 0.18~0.28mmol / g.

[0008] In one or more optional embodiments, the specific surface area of ​​the amorphous silicon-aluminum is 200–550 m². 2 / g.

[0009] In one or more optional embodiments, the specific surface area of ​​the mesoporous alumina is 250–450 m². 2 / g.

[0010] In one or more optional embodiments, the extrusion aid is at least one of starch, guar gum, polyethylene glycol, and methyl cellulose.

[0011] In one or more alternative embodiments, the adhesive is made of inorganic acid and / or organic acid; the inorganic acid is at least one selected from hydrochloric acid, nitric acid, phosphoric acid, and sulfuric acid; and the organic acid is at least one selected from formic acid, acetic acid, citric acid, and tartaric acid.

[0012] In one or more preferred embodiments, the oxide content of the metal W or Mo is 18 to 28 parts.

[0013] In one or more preferred embodiments, the content of the oxide of the metal Co or Ni is 3 to 6 parts.

[0014] In one or more preferred embodiments, the content of the extrusion aid is 2 to 4 parts.

[0015] As a second aspect of the present invention, a method for preparing the above-mentioned wax oil hydrocracking catalyst is provided, the method comprising:

[0016] Amorphous silica-alumina, mesoporous alumina, meso-microporous SBA-15 / HY composite molecular sieve, binder and extrusion aid are mixed evenly, extruded into strips (e.g., cylindrical, clover-shaped or four-leaf clover-shaped), dried and calcined to obtain the carrier.

[0017] The impregnation solution is prepared using a compound containing oxides of metal W or Mo and oxides of metal Co or Ni, and a strongly electronegative organic complexing agent.

[0018] The carrier is impregnated with the impregnation solution, dried, and calcined to obtain a wax oil hydrocracking catalyst.

[0019] In one or more optional embodiments, the organic complexing agent is at least one of ethylene glycol, glycerol, and EDTA.

[0020] As a third aspect of the present invention, the application of the above-mentioned wax oil hydrocracking catalyst in the wax oil hydrocracking process is involved.

[0021] This invention employs macroporous amorphous silica-alumina and mesoporous alumina as the main supports, and meso-microporous SBA-15 / HY composite molecular sieve as the acidic component, thus optimizing the pore structure and acid properties of the hydrocracking catalyst. In the hydrocracking process of inferior wax oil, the internal diffusion performance of polycyclic aromatic hydrocarbons in the molecular sieve has a very important influence on the catalyst activity. Compared with conventional amorphous silica-alumina and alumina, macroporous amorphous silica-alumina, mesoporous alumina, and meso-microporous SBA-15 / HY composite molecular sieve have more mesoporous structures, which is beneficial to improving the diffusion rate and ring-opening cracking ability of polycyclic aromatic hydrocarbons and cycloalkanes. Furthermore, the mesoporous-microporous SBA-15 / HY composite molecular sieve used in this invention is prepared under ultrasonic emulsification, which makes the composite molecular sieve fit more uniformly, resulting in smaller crystal size, more uniform and regular particle size, and a more concentrated distribution range of specific surface area, pore volume, and pore size. Therefore, the support and catalyst prepared from this mesoporous-microporous SBA-15 / HY composite molecular sieve can expose more acidic centers, increase the accessibility between reactants and catalysts, and the catalyst has stable performance and higher activity.

[0022] This invention uses a strongly electronegative organic complexing agent during the metal impregnation process, which increases the hydroxyl density on the support surface, improves the metal dispersion, and reduces the interaction between the support and the metal. While improving the metal utilization rate, it also enhances the synergistic effect between the hydrogenation center and the acid center, enabling the hydrocracking catalyst to operate stably for a long period of time when processing inferior wax oil feedstock.

[0023] The wax oil hydrocracking catalyst provided by this invention can effectively inhibit excessive cracking in the hydrocracking reaction of inferior wax oil rich in macromolecules, improve the conversion selectivity of wax oil macromolecule reactants to target products, increase the production of naphtha as reforming feedstock, light naphtha and cracked tail oil as ethylene cracking feedstock, and also produce jet fuel as No. 3 jet fuel, and effectively improve the smoke point and lower the freezing point of jet fuel.

[0024] The wax oil hydrocracking catalyst provided by this invention is suitable for the production process of producing high-quality chemical feedstock and jet fuel through hydrocracking of wax oil distillate at 220-570℃. After hydrocracking, the naphtha yield is generally 50-60 wt%, the aromatic potential of heavy naphtha is greater than 45%, and the sulfur and nitrogen contents are both <0.5 μg / g; the jet fuel yield is 10-15 wt%, the smoke point is greater than 25.5 mm, the freezing point is less than -60℃, and the flash point is greater than 50℃; the yield of National VI clean diesel is 8-15%, and the cetane number of diesel is 62.2; the yield of light naphtha + tail oil is 15-20%, and the BMCI value of tail oil can be reduced to below 10. Both light naphtha and tail oil can be used as high-quality ethylene cracking feedstock with low BMCI values. This technology can simultaneously reduce diesel production and increase chemical feedstock production, which is conducive to the transformation of oil refining into chemical industry. Detailed Implementation

[0025] The embodiments of the present invention are described in detail below: The embodiments of the present invention are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The process parameters in the following embodiments that do not specify specific conditions are generally in accordance with conventional conditions.

[0026] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0027] The inventors implemented a related technical solution with reference to patent CN201410711529, and found that the hydrocracking catalyst support prepared by that solution had a low mesoporous pore content, and the metal loading method used was a conventional equal-volume impregnation method, resulting in a high metal content and a low specific surface area of ​​the support material after metal loading. The inventors implemented a related technical solution with reference to patent CN200710064672.9, and found that the impregnation method for metal loading was a conventional equal-volume impregnation method or an oversaturated impregnation method, resulting in a high metal content and a low specific surface area of ​​the support material after metal loading. The inventors implemented a related technical solution with reference to patent CN201811521961.1, and found that this method only involved a mechanical mixing of Y molecular sieve and SAPO-34 molecular sieve, while this technology uses a meso-microporous SBA-15 / HY composite molecular sieve as the acidic component, with a high mesoporous pore content and a large average pore size, making it suitable for the hydrocracking process of inferior wax oil feedstock rich in polycyclic aromatic hydrocarbons. The inventors implemented a related technical solution with reference to patent CN201811522285.X, and found that this method only involves the mechanical mixing of Y molecular sieve and SAPO-34 molecular sieve. Compared with this technology, the mesoporous channel content is low, and it is mainly used to produce more middle distillate oil. The inventors implemented a related technical solution with reference to patent WO2020119754A1, and found that the method for preparing hydrocracking catalysts involves acidity optimization of SAPO-34 molecular sieves, but the synthetic materials only use silane as a regulator, resulting in high costs and hindering the reduction of catalyst costs and widespread industrial application. The inventors implemented a related technical solution with reference to patent CN105709844A, and found that the catalyst prepared by this method has low selectivity for jet fuel. The inventors implemented a related technical solution with reference to patent CN104667969B, and found that the catalyst prepared by this method has relatively low oil selectivity.

[0028] Since none of the above methods met the inventor's expectations, the inventor conducted further research and development and came up with this invention.

[0029] The properties of macroporous amorphous silicon-aluminum and mesoporous alumina used in the embodiments of the present invention are shown in Table 1; the properties of conventional amorphous silicon-aluminum and alumina used in the comparative examples of the present invention are shown in Table 2.

[0030] Table 1 Properties of macroporous amorphous silica-alumina and mesoporous alumina

[0031] project Macroporous amorphous silicon aluminum project Mesoporous alumina Aperture distribution, nm Aperture distribution, nm 2-4 10.0 2-10 3.7 4-10 59.2 10-20 90.5 10-60 30.8 20-50 5.8 Pore ​​volume, mL / g 0.88 Pore ​​volume, mL / g 1.13 <![CDATA[S BET ,m 2 / g]]> 325 <![CDATA[S BET ,m 2 / g]]> 388

[0032] Table 2 Properties of Common Amorphous Silicon-Aluminum and Alumina

[0033] project Conventional amorphous silicon and aluminum project Conventional alumina Aperture distribution, nm Aperture distribution, nm 2-4 34.5 2-10 15.7 4-10 57.9 10-20 46.8 10-60 7.6 20-50 37.5 Pore ​​volume, mL / g 0.66 Pore ​​volume, mL / g 0.67 <![CDATA[S BET ,m 2 / g]]> 268 <![CDATA[S BET ,m 2 / g]]> 256

[0034] The mesoporous-microporous SBA-15 / HY composite molecular sieve used in the embodiments of this invention is prepared by the following method:

[0035] S1 mixes nonionic surfactant P123, inorganic acid and water, stirs at 20-40°C, then adds silicon source and hydrolyzes at 30-60°C under ultrasonic emulsification for 4-16 hours, and obtains solid hydrolysis product and mother liquor after filtration.

[0036] S2. The mother liquor is added to the reaction vessel. Based on the amount of P123, inorganic acid and water added in S1, 20-70% P123, 10-60% inorganic acid and 10-40% water are added and stirred at 20-30°C. Then, silicon source is added and hydrolysis reaction is carried out at 30-60°C under ultrasonic emulsification conditions. After filtration, solid hydrolysis products and mother liquor are obtained.

[0037] S3 is repeated 5 to 20 times with S2. All the solid hydrolysis products obtained are combined. The combined solid hydrolysis products are then subjected to hydrothermal crystallization with a small amount of mother liquor to obtain crystallized products.

[0038] Under normal temperature conditions, the crystallized product was dissolved in hydrochloric acid solution and stirred for 8–16 h. Then, HY molecular sieve was added and stirred for another 4–6 h. After filtration, drying, and calcination, mesoporous-microporous SBA-15 / HY composite molecular sieve was obtained.

[0039] The silicon source involved in the above method can be methyl orthosilicate, ethyl orthosilicate, butyl orthosilicate, silica sol, or water glass; the inorganic acid involved in the above method can be hydrochloric acid, phosphoric acid, nitric acid, or carbonic acid.

[0040] The properties of the mesoporous-microporous SBA-15 / HY composite molecular sieve prepared by the above method are shown in Table 3.

[0041] Table 3 Properties of the mesoporous-microporous SBA-15 / HY composite molecular sieve of the present invention

[0042] project Mesoporous-microporous SBA-15 / HY composite molecular sieve <![CDATA[Specific surface area, m 2 / g]]> 510-550 Pore ​​volume, ml / g 0.60-0.75 Average pore size, nm 7.5-8.5 Grain size, nm 150-300 Brønsted acid, mmol / g 0.06-0.10 L-acid, mmol / g 0.13-0.18 Total acid content, mmol / g 0.18-0.28

[0043] Example 1

[0044] 32g of mesoporous-microporous SBA-15 / HY composite molecular sieve (properties shown in Table 3), 74g of mesoporous alumina (Henghuan Aluminum Industry, properties shown in Table 1), 86g of macroporous amorphous silica-alumina (Henghuan Aluminum Industry, properties shown in Table 1), and 5.0g of guar gum powder (Dongfang Chemical Glass) were mixed evenly. A mixed solution prepared from 4.5g of concentrated nitric acid (96wt%), 4.2g of citric acid, and 105g of water was then added dropwise. After stirring evenly, the mixture was kneaded on a twin-screw extruder and extruded into 1.5mm cylindrical pieces. The extruded pieces were dried at 110℃ for 2 hours and calcined in air at 550℃ for 4 hours to prepare a support. The support was then impregnated with an impregnation solution prepared from 100mL of water, 8g of EDTA, 26g of nickel nitrate, and 37g of ammonium metatungstate for 2 hours, dried at 120℃ for 4 hours, and calcined in air at 500℃ for 4 hours to obtain catalyst A. Its physicochemical properties are shown in Table 4.

[0045] Example 2

[0046] 26g of mesoporous-microporous SBA-15 / HY composite molecular sieve (properties shown in Table 3), 74g of mesoporous alumina (Henghuan Aluminum Industry, properties shown in Table 1), 86g of macroporous amorphous silica-alumina (Henghuan Aluminum Industry, properties shown in Table 1), and 5.0g of guar gum powder (Dongfang Chemical Glass) were mixed thoroughly. A mixed solution prepared by adding 4.5g of concentrated nitric acid (96wt%), 4.2g of citric acid, and 105g of water was then added dropwise. After stirring evenly, the mixture was kneaded on a twin-screw extruder and extruded into 1.5mm cylindrical pieces. The extruded pieces were dried at 110℃ for 2 hours and calcined in air at 550℃ for 4 hours to prepare a support. The support was then impregnated with an impregnation solution prepared by 100mL of water, 5g of glycerol, 26g of nickel nitrate, and 37g of ammonium metatungstate for 2 hours, dried at 120℃ for 4 hours, and calcined in air at 500℃ for 4 hours to obtain catalyst B. Its physicochemical properties are shown in Table 4.

[0047] Example 3

[0048] 38g of mesoporous-microporous SBA-15 / HY composite molecular sieve (properties shown in Table 3), 74g of mesoporous alumina (Henghuan Aluminum Industry, properties shown in Table 1), 86g of macroporous amorphous silica-alumina (Henghuan Aluminum Industry, properties shown in Table 1), and 5.0g of guar gum powder (Dongfang Chemical Glass) were mixed thoroughly. A mixed solution prepared by adding 4.5g of concentrated nitric acid (96wt%), 4.2g of citric acid, and 105g of water was then added dropwise. After stirring evenly, the mixture was kneaded on a twin-screw extruder and extruded into 1.5mm cylindrical pieces. The extruded pieces were dried at 110℃ for 2 hours and calcined in air at 550℃ for 4 hours to prepare a support. The support was then impregnated for 2 hours with an impregnation solution prepared by 100mL of water, 5g of glycerol, 26g of nickel nitrate, and 37g of ammonium metatungstate. The impregnation was followed by drying at 120℃ for 4 hours and calcining in air at 500℃ for 4 hours to obtain catalyst C. Its physicochemical properties are shown in Table 4.

[0049] Example 4

[0050] 32g of mesoporous-microporous SBA-15 / HY composite molecular sieve (properties shown in Table 3), 74g of mesoporous alumina (Henghuan Aluminum Industry, properties shown in Table 1), 86g of macroporous amorphous silica-alumina (Henghuan Aluminum Industry, properties shown in Table 1), and 5.0g of guar gum powder (Dongfang Chemical Glass) were mixed thoroughly. A mixed solution prepared by adding 4.5g of concentrated nitric acid (96wt%), 4.2g of citric acid, and 105g of water was then added dropwise. After stirring evenly, the mixture was kneaded on a twin-screw extruder and extruded into 1.5mm cylindrical pieces. The extruded pieces were dried at 110℃ for 2 hours and calcined in air at 550℃ for 4 hours to prepare a support. The support was then impregnated with an impregnation solution prepared by dissolving 26g of nickel nitrate and 37g of ammonium metatungstate in 100mL of water for 2 hours, dried at 120℃ for 4 hours, and calcined in air at 500℃ for 4 hours to obtain catalyst D. Its physicochemical properties are shown in Table 4.

[0051] Comparative Example 1

[0052] 25g of conventional Y molecular sieve, 75g of conventional alumina (properties shown in Table 2), 90g of conventional amorphous silica-alumina (properties shown in Table 2), and 5.0g of guar gum powder (Dongfang Chemical Glass) were added dropwise to a mixed solution of 4.5g concentrated nitric acid (96wt%), 4.2g citric acid, and 105g water. After stirring evenly, the mixture was kneaded on a twin-screw extruder and extruded into 1.5mm cylindrical pieces. The extruded pieces were dried at 110℃ for 2 hours and calcined in air at 550℃ for 4 hours to prepare a support. The support was then impregnated with an impregnation solution prepared by dissolving 26g of nickel nitrate and 37g of ammonium metatungstate in 100mL of water for 2 hours, dried at 120℃ for 4 hours, and calcined in air at 500℃ for 4 hours to obtain catalyst E. Its physicochemical properties are shown in Table 4.

[0053] Comparative Example 2

[0054] 32g of conventional Y molecular sieve, 72g of conventional alumina (properties shown in Table 2), 85g of conventional amorphous silica-alumina (properties shown in Table 2), and 5.0g of guar gum powder (Dongfang Chemical Glass) were mixed thoroughly. Then, a mixed solution of 4.5g concentrated nitric acid (96wt%), 4.2g citric acid, and 105g water was added dropwise and stirred until homogeneous. The mixture was then kneaded on a twin-screw extruder and extruded into 1.5mm cylindrical pieces. The extruded pieces were dried at 110℃ for 2 hours and calcined in air at 550℃ for 4 hours to prepare a support. The support was then impregnated for 2 hours with an impregnation solution prepared by dissolving 26g nickel nitrate and 37g ammonium metatungstate in 100mL of water, dried at 120℃ for 4 hours, and calcined in air at 500℃ for 4 hours to obtain catalyst F. Its physicochemical properties are shown in Table 4.

[0055] Table 4 shows the physicochemical properties of catalysts A to F prepared in Examples 1 to 4 and Comparative Examples 1 to 2.

[0056] Table 4. Physicochemical properties of catalysts

[0057]

[0058] As can be seen from Table 4, the pore size (2-60 nm) of catalysts A, B, C, and D prepared in Examples 1-4 of this invention has significantly higher properties such as volume, specific surface area, pore volume, and strength than those of catalysts E and F prepared in Comparative Examples 1 and 2. The total acid content is also slightly higher, but the amount of active metal components is comparable.

[0059] Example 5

[0060] This example presents the evaluation results of catalyst treatment of inferior wax oil.

[0061] Catalysts A to F prepared in Examples 1-4 and Comparative Examples 1-2 were crushed into particles with a length of 2-3 mm and compared and evaluated using straight-run diesel oil as feedstock in a 200 mL fixed-bed hydrotreating unit. 100 mL of catalyst was loaded into the unit. Sulfidation was performed using kerosene containing 2% carbon disulfide. The reaction conditions after sulfidation were: reaction temperature 320-400 °C, hydrogen partial pressure 14-18 MPa, cracked hydrogen-to-oil volume ratio 800-1500:1, and liquid hourly space velocity 1.0-3.0 h⁻¹. -1 .

[0062] The main properties of the feedstock oil used in this embodiment are shown in Table 5, and the catalyst performance evaluation results are shown in Table 6.

[0063] Table 5 Main Properties of Wax Oil Raw Materials

[0064]

[0065] Table 6 Comparison and Evaluation of Catalyst Performance

[0066]

[0067] Note: Reaction pressure 15.0 MPa, cracking reaction temperature 372℃, hydrogen-to-oil volume ratio 1500:1, volume hourly space velocity 1.5 h⁻¹ -1 As can be seen from Table 6, under the same evaluation process conditions, compared with catalysts E and F prepared in Comparative Examples 1 and 2, catalysts A to D prepared in Examples 1 to 4 of this invention have higher liquid yield, higher total yield of chemical feedstock, and lower BMCI value of tail oil when processing inferior wax oil; and higher aromatic potential of heavy naphtha. That is, the catalysts provided by the invention have excellent hydrocracking performance and good selectivity of chemical feedstock to target products, which can help the refining industry transform and upgrade to the chemical industry.

[0068] Although specific embodiments of the invention have been described in detail, those skilled in the art will understand that various modifications and substitutions can be made to those details based on all the teachings disclosed, and all such changes are within the scope of protection of this invention. The full scope of this invention is given by the appended claims and any equivalents thereof.

Claims

1. A catalyst for the hydrocracking of wax oil, characterized in that, The wax oil hydrocracking catalyst mainly comprises the following components by weight: 1-30 parts of mesoporous-microporous SBA-15 / HY composite molecular sieve; 15-40 parts of macroporous amorphous silica-alumina; 5-30 parts of mesoporous alumina; 10-30 parts of oxides of metal W or Mo; 1-8 parts of oxides of metal Co or Ni; 1.0-5.0 parts of extrusion aid; 3-8 parts of binder; The mesoporous-microporous SBA-15 / HY composite molecular sieve was prepared by ultrasonic emulsification, and the steps are as follows: S1 mixes nonionic surfactant P123, inorganic acid and water, stirs at 20-40°C, then adds silicon source and hydrolyzes at 30-60°C under ultrasonic emulsification for 4-16 hours, and obtains solid hydrolysis product and mother liquor after filtration. S2. The mother liquor is added to the reaction vessel. Based on the amount of P123, inorganic acid and water added in S1, 20-70% P123, 10-60% inorganic acid and 10-40% water are added and stirred at 20-30°C. Then, silicon source is added and hydrolysis reaction is carried out at 30-60°C under ultrasonic emulsification conditions. After filtration, solid hydrolysis products and mother liquor are obtained. S3 is repeated 5 to 20 times with S2. All the solid hydrolysis products obtained are combined. The combined solid hydrolysis products are then subjected to hydrothermal crystallization with a small amount of mother liquor to obtain crystallized products. Under normal temperature conditions, the crystallized product was dissolved in hydrochloric acid solution and stirred for 8–16 h. Then, HY molecular sieve was added and stirred for another 4–6 h. After filtration, drying, and calcination, mesoporous-microporous SBA-15 / HY composite molecular sieve was obtained.

2. The wax oil hydrocracking catalyst as described in claim 1, characterized in that, The mesoporous-microporous SBA-15 / HY composite molecular sieve has a grain size of 150-300 nm and a specific surface area of ​​510-550 m². 2 / g, pore volume is 0.60~0.75mL / g, pore size distribution is 7.5~8.5nm, and total acidity is 0.18~0.28mmol / g.

3. The wax oil hydrocracking catalyst as described in claim 1, characterized in that, The specific surface area of ​​the macroporous amorphous silicon-aluminum is 200~550m². 2 / g.

4. The wax oil hydrocracking catalyst as described in claim 1, characterized in that, The specific surface area of ​​the mesoporous alumina is 250~450 m². 2 / g.

5. The wax oil hydrocracking catalyst as described in claim 1, characterized in that, The extrusion aid is at least one of starch, guar gum powder, polyethylene glycol, and methylcellulose.

6. The wax oil hydrocracking catalyst as described in claim 1, characterized in that, The adhesive is made of inorganic acid and / or organic acid, wherein the inorganic acid is at least one selected from hydrochloric acid, nitric acid, phosphoric acid and sulfuric acid, and the organic acid is at least one selected from formic acid, acetic acid, citric acid and tartaric acid.

7. The wax oil hydrocracking catalyst as described in claim 1, characterized in that, The oxide content of the metal W or Mo is 18 to 28 parts.

8. The wax oil hydrocracking catalyst as described in claim 1, characterized in that, The content of the oxide of the metal Co or Ni is 3 to 6 parts.

9. The wax oil hydrocracking catalyst as described in claim 1, characterized in that, The content of the extrusion aid is 2 to 4 parts.

10. A method for preparing the wax oil hydrocracking catalyst according to any one of claims 1 to 9, characterized in that, The method includes: The carrier is prepared by uniformly mixing macroporous amorphous silica-alumina, mesoporous alumina, meso-microporous SBA-15 / HY composite molecular sieve, binder and extrusion aid, extruding into strips, drying and calcining. An impregnation solution is prepared using a compound containing oxides of metals W or Mo and oxides of metals Co or Ni, and an organic complexing agent; the organic complexing agent is at least one of ethylene glycol, glycerol, and ethylenediaminetetraacetic acid. The carrier is impregnated with the impregnation solution, dried, and calcined to obtain a wax oil hydrocracking catalyst. The mesoporous-microporous SBA-15 / HY composite molecular sieve was prepared by ultrasonic emulsification, and the steps are as follows: S1 mixes nonionic surfactant P123, inorganic acid and water, stirs at 20-40°C, then adds silicon source and hydrolyzes at 30-60°C under ultrasonic emulsification for 4-16 hours, and obtains solid hydrolysis product and mother liquor after filtration. S2. The mother liquor is added to the reaction vessel. Based on the amount of P123, inorganic acid and water added in S1, 20-70% P123, 10-60% inorganic acid and 10-40% water are added and stirred at 20-30°C. Then, silicon source is added and hydrolysis reaction is carried out at 30-60°C under ultrasonic emulsification conditions. After filtration, solid hydrolysis products and mother liquor are obtained. S3 is repeated 5 to 20 times with S2. All the solid hydrolysis products obtained are combined. The combined solid hydrolysis products are then subjected to hydrothermal crystallization with a small amount of mother liquor to obtain crystallized products. Under normal temperature conditions, the crystallized product was dissolved in hydrochloric acid solution and stirred for 8–16 h. Then, HY molecular sieve was added and stirred for another 4–6 h. After filtration, drying, and calcination, mesoporous-microporous SBA-15 / HY composite molecular sieve was obtained.

11. The application of the wax oil hydrocracking catalyst according to any one of claims 1 to 9 in the wax oil hydrocracking process.

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