CN114453015A

CN114453015A - Preparation method of hydrocracking catalyst, hydrocracking catalyst and application

Info

Publication number: CN114453015A
Application number: CN202011134801.9A
Authority: CN
Inventors: 唐兆吉; 王继锋; 樊宏飞
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2020-10-21
Filing date: 2020-10-21
Publication date: 2022-05-10
Anticipated expiration: 2040-10-21
Also published as: CN114453015B

Abstract

The invention discloses a preparation method of a hydrocracking catalyst, the hydrocracking catalyst and application. The preparation method of the hydrocracking catalyst comprises the following steps: (i) preparing a Y/Al-SBA-15 composite molecular sieve; (ii) adding the Y/Al-SBA-15 composite molecular sieve prepared in the step (i), the modified beta molecular sieve and the alumina dry glue powder into an acid solution, and drying and roasting after forming to obtain a hydrocracking catalyst carrier; (iii) and (3) impregnating the hydrocracking catalyst carrier obtained in the step (ii) with a solution containing an active metal component, and then drying and roasting to obtain the hydrocracking catalyst. The hydrocracking catalyst prepared by the method has excellent comprehensive performance, and is used in the coal tar hydrocracking reaction process, and the product quality is excellent.

Description

Preparation method of hydrocracking catalyst, hydrocracking catalyst and application

Technical Field

The invention relates to a preparation method of a hydrocracking catalyst, in particular to a preparation method of a hydrocracking catalyst suitable for converting coal tar distillate into clean gasoline and diesel oil.

Background

Coal tar is an important byproduct in the coal pyrolysis and dry distillation process, is a black or blackish brown viscous liquid with pungent odor, is a complex mixture of high-aromatic hydrocarbon, and can be divided into low-temperature coal tar and high-temperature coal tar according to the coal pyrolysis and dry distillation temperature and the process method. The coal tar raw material has the characteristics of high content of heteroatoms such as sulfur, nitrogen and the like, high ash content, high content of polycyclic aromatic hydrocarbon, high content of colloid and asphaltene and the like.

The hydrogenation of coal tar is carried out under the action of catalyst at high temperature and high pressure to modify the molecular structure and remove S, N, O and other hetero atoms, so as to achieve the effects of cleanness and light weight, and obtain fraction fuels such as gasoline, diesel oil, kerosene and the like. The method can not only improve the utilization rate of non-renewable resources such as coal and reduce the waste of resources, but also provide beneficial supplement for petroleum with short supply. Coal tar contains a large amount of aromatic compounds, the nitrogen content (0.45-1.30%) and the sulfur content (0.29-0.40%) of the coal tar are high, and a large amount of SO can be generated by directly combusting the coal tar_XAnd NO_XAnd does not meet the exhaust emission standard, thereby causing serious environmental pollution.

The main purpose of hydro-upgrading is to further change the molecular structure of each component in the coal tar, and the product performance is fully improved. Compared with distillate oil hydrogenation, the coal tar has four high characteristics: the oxygen content is high; the content of colloid and carbon residue is high; the content of sulfur and nitrogen is high; the aromatic hydrocarbon content is high, and the developed hydrogenation reforming catalyst has the characteristic of meeting the requirement of being suitable for refining coal tar.

CN101885984A discloses a combined process for generating clean fuel oil by coal tar hydrogenation and a catalyst thereof. The active components of the hydro-upgrading catalyst in the patent are metal oxides NiO and MoO of VIII group and VIB group₃、CoO、WO₃The carrier is acid modified kaolin. Because the acid modified kaolin is used as a carrier, the pore volume of the acid modified kaolin is very small, and the acidity of the acid modified kaolin is higher, the colloid and the asphaltene of the coal tar raw material with higher content of the colloid and the asphaltene cannot enter the pore channel of the catalyst, and more carbon deposit is formed on the surface of the catalyst, so that the catalyst is easy to deactivate, and the running period is short.

CN102029157A discloses a catalyst for coal tar pitch hydrocracking lightening reaction, which is prepared by taking an inorganic porous material as a carrier, selecting one of alumina, silica gel containing alumina, MCM-41 or SBA-15, loading one or two of metal elements Fe, Ni, Co and Mo of an active component on the carrier in the form of metal oxide or metal sulfide by a vacuum impregnation method, drying under normal pressure under the protection of nitrogen, and roasting. The catalyst prepared by the method has poor activity, more reaction coking, shorter service life, low yield of cracked light oil and further improved conversion rate of coal tar pitch.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a preparation method of a hydrocracking catalyst suitable for coal tar, the hydrocracking catalyst and application. The hydrocracking catalyst prepared by the method has excellent comprehensive performance, and is used in the coal tar hydrocracking reaction process, and the product quality is excellent.

In a first aspect, the present invention provides a method for preparing a hydrocracking catalyst, comprising:

(i) preparing a Y/Al-SBA-15 composite molecular sieve;

(ii) adding the Y/Al-SBA-15 composite molecular sieve prepared in the step (i), the modified beta molecular sieve and the alumina dry glue powder into an acid solution, and drying and roasting after forming to obtain a hydrocracking catalyst carrier;

(iii) and (3) impregnating the hydrocracking catalyst carrier obtained in the step (ii) with a solution containing an active metal component, and then drying and roasting to obtain the hydrocracking catalyst.

Further, the acid amount of the medium strong acid of the Y/Al-SBA-15 composite molecular sieve is 0.6-1.2 mL/g, preferably 0.7-1.0 mL/g, and the ratio of the B acid to the L acid is less than 1.2.

Further, the ratio of B acid to L acid in the Y/Al-SBA-15 composite molecular sieve is less than 1.0, more preferably less than 0.6, still more preferably more than 0.1, and specifically can be 0.1, 0.2, 0.3, 0.4 or 0.5.

Further, said Y isThe properties of the/Al-SBA-15 composite molecular sieve are as follows: the specific surface area is 550-1000 m²Preferably 680 to 800 m/g²The total pore volume is 0.4 to 1.0mL/g, preferably 0.5 to 0.8 mL/g.

Furthermore, in the Y/Al-SBA-15 composite molecular sieve, the mass content of alumina is 2-85%, preferably 5-82%, and more preferably 7.5-79.5%. In the Y/Al-SBA-15 composite molecular sieve, the content of alumina can be adjusted within a wide range, such as 10.5%, 15.5%, 16.5%, 18.2%, 20.5%, 25.5%, 30.2%, 32.5%, 35.5%, 40.1%, 45.5%, 50.5%, 55.3%, 60.5%, 70.5%, 78.5% and the like.

Further, the pore distribution of the Y/Al-SBA-15 composite molecular sieve comprises: the pore volume of the pores with the pore diameter of 4-15 nm accounts for 42-72%, preferably 45-65%, and more preferably 55-65% of the total pore volume.

Further, the mass content of the Y/Al-SBA-15 composite molecular sieve is 5-25%, preferably 8-15%.

Furthermore, in the Y/Al-SBA-15 composite molecular sieve, the mass content of alumina in the Al-SBA-15 molecular sieve is 5-75%. The mass content of alumina in the Al-SBA-15 molecular sieve can be adjusted within a wide range, and can be 8%, 10%, 15%, 18%, 21.0%, 25.0%, 28.0%, 33.5%, 54.5%, 68.5% and the like.

Further, the preparation method of the Y/Al-SBA-15 composite molecular sieve comprises the following steps: amorphous silica-alumina dry gel is used as a raw material, P123 triblock copolymer is used as a template agent to carry out first crystallization to synthesize the Al-SBA-15 molecular sieve, and then ultrastable Y molecular sieve slurry is added to carry out second crystallization to obtain the Y/Al-SBA-15 composite molecular sieve.

Further, the amorphous silica-alumina dry gel has the following properties: the surface area is 400-650 m²Per g, preferably 450 to 600m²The pore volume is 0.52-1.8 ml/g, preferably 0.85-1.5 ml/g, and the pore distribution is as follows: the pore volume with the pore diameter of 4-15 nm accounts for 85% -95% of the total pore volume, and the pore volume with the pore diameter of more than 15nm accounts for less than 5% of the total pore volume.

Further, in the amorphous silica-alumina dry gel, the mass content of alumina is 2-85%. The mass content of the alumina can be adjusted within a wide range, and can be, for example, 5%, 10%, 15%, 16%, 18%, 20%, 25%, 30%, 32%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, 75%, and the like.

Further, the properties of the ultrastable Y molecular sieve are as follows: SiO 2₂/Al₂O₃The molar ratio is 25-150, and the specific surface area is 550-1000 m²(iv)/g, the total pore volume is 0.30-0.60 mL/g.

Furthermore, the ultrastable Y molecular sieve slurry can be prepared by adding water into an ultrastable Y molecular sieve and pulping, and the mass content of the ultrastable Y molecular sieve in the slurry is 20-40%.

Further, the specific preparation method of the Y/Al-SBA-15 composite molecular sieve comprises the following steps:

(1) mixing amorphous silica-alumina dry gel and water to form slurry;

(2) preparing an acidic solution containing a P123 triblock copolymer;

(3) and (2) mixing the slurry prepared in the step (1) with the acidic aqueous solution containing the P123 triblock copolymer prepared in the step (2), performing first crystallization, adding the ultrastable Y molecular sieve slurry, and performing second crystallization to prepare the Y/Al-SBA-15 composite molecular sieve.

According to the method, the amorphous silica-alumina in the step (1) is prepared by a carbonization method, and can be prepared by the following steps:

a. respectively preparing a sodium aluminate solution and a sodium silicate solution;

b. adding part or all of sodium silicate solution into sodium aluminate solution, and introducing CO₂Controlling the reaction temperature of the gas to be 10-40 ℃, preferably 15-35 ℃, and controlling the pH value of the gel to be 8-11; wherein when CO is introduced₂When the gas amount accounts for 40-100 percent of the total input amount, preferably 50-80 percent, adding the rest sodium silicate solution;

c. c, ventilating and stabilizing the mixture for 10-30 minutes under the temperature and pH value control of the step b;

d. c, filtering the solid-liquid mixture obtained in the step c, and washing a filter cake;

e. d, pulping the filter cake obtained in the step d, then carrying out hydro-thermal treatment, filtering and drying to obtain the amorphous silica-alumina dry gel; the hydrothermal treatment conditions are as follows: treating for 2-10 hours at 120-150 ℃ and under the water vapor pressure of 0.5-4.0 MPa.

Further, in the step a, the concentration of the sodium aluminate solution is 15-55 gAl₂O₃L, further 15 to 35gAl₂O₃L, the concentration of the sodium silicate solution is 50-200 gSiO₂A further amount of 50 to 150g SiO₂/L。

Further, in the step b, part or all of the sodium silicate solution is added, namely 5wt% -100 wt% of the total added sodium silicate solution. The CO is₂The concentration of the gas is 30-60 v%. And c, ventilating and stirring in the gelling process in the step b.

Further, the specific process of step b is as follows: (1) adding all sodium silicate into sodium aluminate, and introducing CO₂A gas; (2) adding part of sodium silicate into sodium aluminate, and introducing all CO₂Gas, then adding the remaining sodium silicate solution to the mixture; (3) after adding part of sodium silicate to sodium aluminate, part of CO is introduced₂Gas, then CO is introduced₂The gas was added to the remaining sodium silicate solution.

Further, filtering the slurry obtained in the step d, washing the slurry with deionized water at the temperature of 50-95 ℃ until the slurry is nearly neutral,

and further, mixing the filter cake obtained in the step e according to a solid-liquid volume ratio of 8: 1-12: 1, adding water and pulping.

Further, the drying in the step e can be performed by a conventional method, and can be performed for 6-8 hours at 110-130 ℃.

Further, the mass ratio of the amorphous silica-alumina dry gel to water in the step (1) is 10: 90-30: 70, preferably 15: 85-25: 75.

further, the pH value of the acidic aqueous solution in the step (2) is 1-5, preferably 1.2-2.3, and the mass content of the P123 triblock copolymer in the acidic aqueous solution is 0.5-5.0%, preferably 0.8-2.8%.

Further, the P123 triblock copolymer is added to dilute acid in step (2)(e.g., dilute hydrochloric acid), said dilute acid solution having a concentration of H⁺0.05 to 0.3mol/L, preferably 0.1 to 0.2mol/L, and more preferably 0.13 to 0.18 mol/L; in order to sufficiently dissolve the P123 triblock copolymer, the temperature system is controlled to 10 to 60 ℃, preferably 20 to 40 ℃, and more preferably 25 to 35 ℃.

Further, in the step (3), the slurry prepared in the step (1) is mixed with the acidic aqueous solution containing the P123 triblock copolymer prepared in the step (2), and the amounts of the slurry prepared in the step (1) and the acidic aqueous solution containing the P123 triblock copolymer prepared in the step (2) are such that the mass ratio of the P123 triblock copolymer to the amorphous silica-alumina in the mixed system is 0.5:1 to 5:1, preferably 1:1 to 5:1, and more preferably 1:1 to 3: 1.

Further, the conditions of the first crystallization in the step (3) are: the crystallization temperature is 80-120 ℃, and preferably 90-110 ℃; the crystallization time is 10-35 h, preferably 16-24 h; the pH value in the crystallization process is controlled to be 2.0-5.0, preferably 3.2-4.8.

Further, the conditions of the second crystallization in the step (3) are: the crystallization temperature is 80-130 ℃, and preferably 90-120 ℃; the crystallization time is 4-20 h, preferably 10-15 h; the pH value is controlled to be 2.0-5.0, preferably 4.2-5.0 in the crystallization process.

Further, after the crystallization step of step (3), the Y/Al-SBA-15 composite molecular sieve may be separated from the obtained mixture by any conventionally known means, such as filtration, washing, drying, etc. The filtration can adopt suction filtration. The washing can be performed by using deionized water as a washing solution. The drying can be carried out at 80-150 ℃, preferably 90-130 ℃, and the drying time is 2-12 hours, preferably 3-6 hours. The drying may be carried out at atmospheric pressure.

Further, the composite molecular sieve prepared by the above method may be calcined to remove the template agent and water and the like if necessary. The roasting can be carried out according to any mode conventionally known in the field, the roasting temperature is controlled to be 450-600 ℃, preferably 480-580 ℃, further preferably 500-560 ℃, and the roasting time is 2-10 hours, preferably 3-6 hours. In addition, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or oxygen.

Further, in step (ii), the modified beta molecular sieve preferably has the following properties: SiO 2₂/Al₂O₃The molar ratio is 35-155, and the specific surface area is 510-850 m²The pore volume is 0.30-0.60 mL/g.

Further, in step (ii), the properties of the alumina are as follows: the pore volume is 0.80 mL/g-1.2 mL/g, the specific surface area is 140m²/g～360m²(ii)/g, the average pore diameter is 10 to 14 nm.

Further, the hydrocracking catalyst carrier obtained in the step (ii) takes the weight of the hydrocracking catalyst carrier as a reference, and the weight content of the Y/Al-SBA-15 composite molecular sieve is 5% -25%; the weight content of the modified beta molecular sieve is 5-15%, and the weight content of the alumina is 60-90%.

Further, in step (ii), the acidic solution is at least one of acetic acid or nitric acid. The mass concentration of the acid solution is 2.3-4.5 wt%; the acid solution contains guar gum, and the mass content of the guar gum in the acid solution is 0.2-1 wt%.

Further, in step (ii), the drying conditions are as follows: the drying temperature is 80-150 ℃, preferably 90-120 ℃, and the drying time is 0.5-20.0 h, preferably 3.0-6.0 h; the calcination conditions were as follows: the roasting temperature is 450-650 ℃, preferably 500-650 ℃, and the roasting time is 0.5-20.0 h, preferably 3.0-6.0 h. The drying and calcination may be carried out in an oxygen-containing atmosphere, the oxygen concentration is not particularly limited, such as an air atmosphere, etc., and may also be carried out in an inert atmosphere, such as a nitrogen atmosphere, etc.

Further, the hydrocracking catalyst carrier may be shaped as required, such as a dentate sphere, cloverleaf, clover, or cylindrical bar.

Further, the active metal component in step (iii) comprises a group VIB metal, preferably molybdenum and/or tungsten, and a group VIII metal, preferably cobalt and/or nickel.

Furthermore, the content of the VIB group metal calculated by oxide is 10wt% -18 wt%, and the content of the VIII group metal calculated by oxide is 4wt% -8 wt% based on the weight of the hydrocracking catalyst.

Furthermore, the coal tar hydrocracking catalyst may further contain a certain auxiliary agent, such as P, B, Ti, Zr, etc., wherein the content of the auxiliary agent is less than 10% of the weight of the coal tar hydrocracking catalyst, and may be 0.1% to 8.0% by weight of the coal tar hydrocracking catalyst.

Further, in step (iii), the impregnation may be carried out by a method conventional in the art, such as an equal-volume impregnation, a supersaturated impregnation, a stepwise impregnation, a co-impregnation, etc., preferably an equal-volume co-impregnation.

Further, in the step (iii), the drying temperature is 80-150 ℃, preferably 90-120 ℃, and the drying time is 0.5-20.0 h, preferably 3.0-6.0 h; the roasting temperature is 400-650 ℃, preferably 400-550 ℃, and the roasting time is 0.5-20.0 h, preferably 2.0-6.0 h.

In a second aspect, the present invention provides a hydrocracking catalyst prepared by the process of the first aspect.

The hydrocracking catalyst had the following properties: the specific surface area is 200-500 m²Preferably 220 to 350 m/g²The pore volume is 0.30 to 0.65mL/g, preferably 0.35 to 0.60 mL/g.

In a third aspect, the invention provides the use of a hydrocracking catalyst prepared by the above process.

Further, the application is that the hydrocracking catalyst is applied to a coal tar hydrocracking process and is used in a hydrocracking method for converting coal tar into clean gasoline and diesel.

Further, the reaction conditions of the hydrocracking catalyst applied to hydrocracking of the coal tar distillate are as follows: the reaction temperature is 340-430 ℃, the preferable temperature is 355-400 ℃, the hydrogen partial pressure is 5-20 MPa, the preferable pressure is 8-15 MPa, the volume ratio of hydrogen to oil is 500-2000: 1, the preferable pressure is 850-1800: 1, and the liquid hourly space velocity is 0.1-E1.5h^-1Preferably 0.2 to 0.8h^-1。

Further, the properties of the coal tar are as follows: the density (20 ℃) was 1000kg/m³~1200 kg/m³The nitrogen content is 0.8-1.5 wt%, the sulfur content is 0.2-0.8 wt%, and the aromatic component and colloid content are high.

Compared with the prior art, the preparation method of hydrocracking catalysis has the following advantages:

the invention selects the ordered mesoporous-microporous Y/Al-SBA-15 composite molecular sieve and the modified beta molecular sieve which have high stability, adjustable acid amount and reasonable pore distribution as the acidic components, can flexibly adjust the acidity of the catalyst, improve the activity and selectivity of the catalyst, have proper cracking and isomerization effects on alkane and arene in reactants, maintain high diesel yield, greatly improve the cetane number of the diesel, greatly improve the condensation point, and reduce the density and the sulfur content of the diesel.

The Y/Al-SBA-15 composite molecular sieve of the invention still shows the regularity of mesoporous structure even under the condition of very high aluminum content, and the regularity can be characterized by the pore distribution of the molecular sieve (especially the pore volume ratio of pores with the diameter of less than 4 nm). As a corroboration, according to the Y/Al-SBA-15 composite molecular sieve disclosed by the invention, even if the mass percentage of alumina in the chemical composition of the molecular sieve is widely changed from 2% to 85%, the pore volume of pores with the pore diameters of 4-15 is still 42% -72%, the integrity and regularity of a mesoporous structure are kept, which are not possessed by Y/Al-SBA-15 composite molecular sieves manufactured by the prior art, and therefore, the pore structure of a catalyst can migrate towards the mesoporous direction after the Y/Al-SBA-15 micro-mesoporous composite molecular sieve is added, and macromolecular reaction in coal tar distillate is facilitated.

According to the invention, through the synergistic effect of the two molecular sieves, the acid amount of the catalyst is well distributed, the dispersion degree of the active component is improved while the acid amount of the medium-strong acid is increased, more active sites suitable for reaction are increased, the hydrogenation function and the cracking function of the catalyst are well matched, the pore volume is improved, and the conversion capability of the catalyst on coal tar macromolecule hydrocarbon compounds is improved.

Drawings

FIG. 1 is an XRD pattern of Al-SBA-15 molecular sieve obtained in comparative example 5 of the present invention.

Detailed Description

In the present invention, the Al-SBA-15 molecular sieve means that aluminum atoms are introduced into the SBA-15 molecular sieve, the existence state of the aluminum atoms in the SBA-15 molecular sieve is not particularly limited, and a part of the aluminum atoms are generally distributed on the framework of the SBA-15 molecular sieve.

In the invention, the determination of the L acid or the B acid adopts an infrared spectroscopy, an instrument adopts an American Nicot Fourier infrared spectrometer-6700, and the determination method comprises the following steps: weighing 20mg of sample with granularity less than 200 meshes, pressing into sheet with diameter of 20mm, placing on sample rack of absorption cell, placing 200mg of sample in cup of instrument, connecting absorption cell and adsorption tube, vacuumizing until vacuum degree reaches 4 × 10^-2And Pa, heating to 500 ℃, keeping for 1 hour to remove adsorbates on the surface of the sample, cooling to room temperature, adsorbing pyridine to saturation, continuously heating to 160 ℃, balancing for 1 hour, and desorbing the physically adsorbed pyridine to obtain the acid quantities of infrared total acid, B acid and L acid, wherein the acid quantity unit of the B acid and the L acid is mmol/L.

In the invention, NH is adopted as the medium strong acid₃TPD method. The adopted instrument is an Auto-Chem II 2920 chemical adsorption instrument of Mike instruments. Ammonia gas is used as an adsorption and desorption medium, helium gas is used as carrier gas, and the acid quantities of different desorption temperature areas are obtained by adopting temperature programming desorption and chromatographic analysis, wherein the ammonia gas desorption temperature corresponding to the acid quantity of the medium-strong acid is 250-400 ℃, and the acid quantity unit is as follows: mL/g is the amount of ammonia adsorbed per gram of molecular sieve.

In the invention, the specific surface area, the pore volume and the pore distribution are measured by adopting an ASAP2405 physical adsorption instrument, and the measuring method comprises the following steps: after the sample is processed, liquid N₂Used as adsorbate, the adsorption temperature is-196 ℃, and analysis and test are carried out. Wherein the specific surface area is calculated by a BET method, and the pore volume and the pore distribution are calculated by a BJH method.

In the present invention, XRD was measured using an X-ray diffractometer model D/max2500 manufactured by Japan science, under the following test conditions: the voltage is 40KV, the current is 80mA, a CuK alpha target is selected, and the incident wavelength is 0.15405 nm. In order to better illustrate the present patent, the present invention is further illustrated below by reference to examples and comparative examples. However, the scope of the present invention is not limited to these examples, and% are mass percentages in the following examples and comparative examples unless otherwise specified.

Example 1

Preparation of coal tar hydrocracking catalyst carrier

(1) Preparation of amorphous silica-alumina dry gel powder A1 and slurry: sodium aluminate solution concentration 18gAl₂O₃Per L, sodium silicate solution concentration 100gSiO₂Putting 0.75L of sodium aluminate solution into a gelling tank, adding 0.35L of sodium silicate solution, controlling the reaction temperature to be 20 ℃, and introducing 40 v% CO₂Gas, introduction of CO₂When the gas accounts for 50 percent of the total input amount, 0.15L of sodium silicate solution is added while introducing gas, the pH value of the formed gel is controlled to be 9.5, then the ventilation is stabilized for 20 minutes, the slurry is filtered and washed to be neutral by deionized water at 65 ℃, a filter cake is added with water according to the solid-liquid volume ratio of 10: 1 for pulping, the treatment is carried out for 2 hours at the temperature of 130 ℃ and the water vapor pressure of 3.5MPa, and after the drying is carried out for 6 hours at the temperature of 120 ℃, the amorphous silica-alumina product A1 is obtained by crushing and sieving. The properties of the amorphous silica-alumina dry gel powder A1 are shown in Table 1. Mixing the prepared amorphous silica-alumina A1 with deionized water, and pulping to form slurry; wherein the mass ratio of the amorphous silica-alumina dry gel to water is 18: 82;

(2) preparing an acidic aqueous solution containing a P123 triblock copolymer; adding the P123 triblock copolymer into dilute hydrochloric acid, wherein the concentration of a dilute hydrochloric acid solution is 0.13mol/L, the pH value of an acidic aqueous solution containing the P123 triblock copolymer is 1.2, the temperature of the acidic aqueous solution containing the P123 triblock copolymer is 25 ℃, and the mass content of the P123 triblock copolymer in the acidic aqueous solution containing the P123 triblock copolymer is 1.6 wt%;

(3) mixing the slurry prepared in the step (1) with the acidic aqueous solution containing the P123 triblock copolymer prepared in the step (2); the mass ratio of the P123 triblock copolymer to the amorphous silica-alumina in the mixed system is 1.2:1, the crystallization temperature is 90 ℃, and the crystallization time is 20 hours; controlling the pH value to be 3.3 in the crystallization process;

(4) slurry containing 12g of USY molecular sieve (wherein the USY molecular sieve has the following properties of 785m of specific surface area²Per g, pore volume 0.53 mL. g^-1，SiO₂/Al₂O₃The USY molecular sieve slurry is prepared by pulping the USY molecular sieve and water at a molar ratio of 45) and pumping into the mixed system prepared in the step (3) by using a vacuum pump, drying for 3h at 100 ℃ after the crystallization time is 10h at a pH value of 4.6 and a temperature of 90 ℃, and roasting for 3h at 550 ℃ to obtain a finished product YAS-1.

10g of YAS-1 mesoporous-microporous composite molecular sieve and 10g of modified beta molecular Sieve (SiO)₂/Al₂O₃The molar ratio is 65, the specific surface area is 630m²0.48mL/g in pore volume), 80g of alumina (0.98 mL/g in pore volume and 335m in specific surface area²Per g, average pore diameter of 12 nm), adding into a rolling machine for rolling, adding an aqueous solution containing guar gum (0.4 wt%) and nitric acid (2.2 wt%) after 20 minutes of rolling, rolling into paste, extruding into strips, drying the extruded strips at 120 ℃ for 3 hours, and roasting at 550 ℃ for 3 hours to obtain the carrier Z1.

(II) catalyst preparation

The carrier Z1 was impregnated with W, Ni-containing impregnation solution in equal volume, dried at 120 ℃ for 3h, calcined at 420 ℃ for 2h to obtain the final catalyst C-1, the properties of which are shown in Table 2.

Example 2

Preparation of hydrocracking catalyst carrier

(1) Preparation of amorphous silica-alumina dry gel powder A2 and slurry: sodium aluminate solution concentration 20gAl₂O₃Per L, sodium silicate solution concentration 35gSiO₂L, putting 0.3L of sodium aluminate solution into a gelling tank, then adding 0.5L of sodium silicate solution, controlling the reaction temperature to be 22 ℃, and introducing 35 v% CO₂Gas, introduction of CO₂When gas accounts for 50% of total input amount, adding 0.2L sodium silicate solution while introducing gas, controlling pH value of gelatinized gel to 9.8, then ventilating and stabilizing for 20 min, filtering slurry, washing with 75 deg.C deionized water to neutral, adding water into filter cake according to solid-liquid volume ratio of 8:1Pulping, treating at 120 deg.C under 3.0MPa water vapor pressure for 2 hr, drying at 120 deg.C for 8 hr, pulverizing, and sieving to obtain amorphous silica-alumina product A2, wherein the properties of amorphous silica-alumina dry gel powder A2 are shown in Table 1. Mixing the prepared amorphous silica-alumina A2 with deionized water, and pulping to form slurry; wherein the mass ratio of the amorphous silica-alumina dry gel to water is 23: 77;

(2) preparing an acidic aqueous solution containing a P123 triblock copolymer; adding the P123 triblock copolymer into dilute hydrochloric acid, wherein the concentration of a dilute hydrochloric acid solution is 0.16mol/L, the pH value of an acidic aqueous solution containing the P123 triblock copolymer is 1.4, the temperature of the acidic aqueous solution containing the P123 triblock copolymer is 28 ℃, and the mass content of the P123 triblock copolymer in the acidic aqueous solution containing the P123 triblock copolymer is 2.3 wt%;

(3) mixing the slurry prepared in the step (1) with the acidic aqueous solution containing the P123 triblock copolymer prepared in the step (2); the mass ratio of the P123 triblock copolymer to the amorphous silica-alumina in the mixed system is 1.2:1, the crystallization temperature is 93 ℃, and the crystallization time is 18 hours; controlling the pH value to be 3.4 in the crystallization process;

(4) slurry containing 56.98g of USY molecular sieve (wherein the USY molecular sieve has the following properties: specific surface area 823 m²Per g, pore volume 0.52 mL. g^-1，SiO₂/Al₂O₃The USY molecular sieve slurry is prepared by pulping the USY molecular sieve and water at a molar ratio of 48) and pumping into the mixed system prepared in the step (3) by using a vacuum pump, drying at 100 ℃ for 4h and roasting at 550 ℃ for 3h after the crystallization time is 11h at the pH value of 4.8 and the temperature of 95 ℃, so as to obtain a finished product YAS-2.

12g of YAS-2 mesoporous-microporous composite molecular sieve and 8g of modified beta molecular Sieve (SiO)₂/Al₂O₃The molar ratio is 68, the specific surface area is 655m²(g, pore volume 0.52 mL/g) 80g of alumina (same as in example 1) was added to a roll mill and rolled for 23 minutes, then an aqueous solution containing guar gum (0.4 wt%) and nitric acid (2.3 wt%) was added thereto and rolled into a paste, and then a bar was extruded, and the extruded bar was dried at 120 ℃ for 3 hours and calcined at 550 ℃ for 3 hours to obtain a support Z2.

(II) preparation of catalyst

The carrier Z2 was impregnated with equal volume of W, Ni-containing impregnation solution, dried at 120 ℃ for 3h, calcined at 430 ℃ for 2h to obtain the final catalyst C-2, the properties of which are shown in Table 2.

Example 3

Preparation of hydrocracking catalyst carrier

(1) Preparation of amorphous silica-alumina dry gel powder A3 and slurry: sodium aluminate solution concentration 21gAl₂O₃Per L, sodium silicate working solution concentration 65gSiO₂L, putting 0.83L of sodium aluminate solution into a gel forming tank, then adding 0.5L of sodium silicate solution, controlling the reaction temperature to be 32 ℃, and introducing 52 v% CO₂Stopping gas when the pH value reaches 9.8, then ventilating and stabilizing for 20 minutes, washing to be neutral, adding water into a filter cake according to the solid-liquid volume ratio of 9: 1 for pulping, treating for 3 hours at 130 ℃ under the water vapor pressure of 3.9MPa, drying for 8 hours at 130 ℃, crushing and sieving to obtain an amorphous silica-alumina product A3. The properties of the amorphous silica-alumina dry gel powder A3 are shown in Table 1. Mixing the prepared amorphous silica-alumina A3 with deionized water, and pulping to form slurry; wherein the mass ratio of the amorphous silica-alumina dry gel to water is 19: 81;

(2) preparing an acidic aqueous solution containing a P123 triblock copolymer; adding the P123 triblock copolymer into diluted hydrochloric acid, wherein the concentration of a diluted hydrochloric acid solution is 0.15mol/L, the pH value of an acidic aqueous solution containing the P123 triblock copolymer is 1.9, the temperature of the acidic aqueous solution containing the P123 triblock copolymer is 33 ℃, and the mass content of the P123 triblock copolymer in the acidic aqueous solution containing the P123 triblock copolymer is 1.9 wt%;

(3) mixing the slurry prepared in the step (1) with the acidic aqueous solution containing the P123 triblock copolymer prepared in the step (2); the mass ratio of the P123 triblock copolymer to the amorphous silica-alumina in the mixed system is 1.3:1, the crystallization temperature is 95 ℃, and the crystallization time is 12 hours; the pH value is controlled to be 3.6 in the crystallization process,

(4) slurry containing 50.9g of USY molecular sieve (wherein the USY molecular sieve has the following properties of specific surface area of 795m²Per g, pore volume 0.54 mL. g^-1，SiO₂/Al₂O₃The USY molecular sieve slurry is prepared by pulping the USY molecular sieve and water at a molar ratio of 43) and pumping into the mixed system prepared in the step (3) by using a vacuum pump, drying at 100 ℃ for 4h and roasting at 550 ℃ for 3h after the crystallization time is 10h at the pH value of 4.9 and the temperature of 95 ℃, so as to obtain a finished product YAS-3.

14g of YAS-3 mesoporous-microporous composite molecular sieve and 6g of modified beta molecular Sieve (SiO)₂/Al₂O₃The molar ratio is 68, and the specific surface area is 658m²(same as example 1) 80g of alumina (pore volume: 0.49 mL/g) was added to a roll mill to conduct rolling, after 23 minutes of rolling, an aqueous solution containing guar gum (0.4 wt%) and nitric acid (2.3 wt%) was added to the mixture to conduct rolling into a paste, and then the paste was extruded, and the extruded bar was dried at 120 ℃ for 3 hours and calcined at 550 ℃ for 3 hours to obtain a support Z3.

(II) catalyst preparation

The carrier Z3 was impregnated with equal volume of impregnating solution containing W, Ni, dried at 120 ℃ for 3h, calcined at 430 ℃ for 2h to obtain the final catalyst C-3, and the properties of the catalyst are shown in Table 2.

Example 4

Preparation of hydrocracking catalyst carrier

(1) Preparation of amorphous silica-alumina dry gel powder A4 and slurry: sodium aluminate solution concentration 25gAl₂O₃Per L, sodium silicate solution concentration 55gSiO₂L, putting 0.5L of sodium aluminate solution into a gel forming tank, then adding 0.15L of sodium silicate solution, controlling the reaction temperature to be 35 ℃, and introducing 60v% CO₂Stopping gas when the pH value reaches 9.5, then ventilating and stabilizing for 20 minutes, washing to be neutral, adding water into a filter cake according to the solid-liquid volume ratio of 8:1 for pulping, treating for 2.5 hours at the temperature of 130 ℃ under the water vapor pressure of 3.2MPa, drying for 8 hours at the temperature of 130 ℃, crushing and sieving to obtain an amorphous silica-alumina product A4. The properties of the amorphous silica-alumina dry gel powder A4 are shown in Table 1. Mixing the prepared amorphous silica-alumina A4 with deionized water, and pulping to form slurry; wherein the mass ratio of the amorphous silica-alumina dry gel to water is 24: 76;

(2) preparing an acidic aqueous solution containing a P123 triblock copolymer; adding the P123 triblock copolymer into dilute hydrochloric acid, wherein the concentration of a dilute hydrochloric acid solution is 0.17mol/L, the pH value of an acidic aqueous solution containing the P123 triblock copolymer is 1.9, the temperature of the acidic aqueous solution containing the P123 triblock copolymer is 33 ℃, and the mass content of the P123 triblock copolymer in the acidic aqueous solution containing the P123 triblock copolymer is 1.5 wt%;

(3) mixing the slurry prepared in the step (1) with the acidic aqueous solution containing the P123 triblock copolymer prepared in the step (2); the mass ratio of the P123 triblock copolymer to the amorphous silica-alumina in the mixed system is 1.8:1, the crystallization temperature is 96 ℃, and the crystallization time is 12 hours; controlling the pH value to be 3.6 in the crystallization process;

(4) slurry containing 79.25g of USY molecular sieve (wherein the USY molecular sieve has the following properties that the specific surface area is 798m²Per g, pore volume 0.51 mL. g^-1，SiO₂/Al₂O₃The USY molecular sieve slurry is prepared by pulping USY molecular sieve and water, and the USY molecular sieve slurry is prepared by beating the USY molecular sieve and water), pumping the USY molecular sieve slurry and the water into the mixed system prepared in the step (3) by using a vacuum pump, drying the USY molecular sieve slurry for 4 hours at the temperature of between 110 ℃ after the crystallization time is 12 hours at the pH value of 5.0, and roasting the USY molecular sieve slurry for 4 hours at the temperature of between 540 ℃ to obtain a finished product YAS-4.

16g of YAS-4 mesoporous-microporous composite molecular sieve and 4g of modified beta molecular Sieve (SiO)₂/Al₂O₃The molar ratio is 66, the specific surface area is 630m²(same as example 1) 80g of alumina (pore volume: 0.51 mL/g) was added to a roll mill to conduct rolling for 25 minutes, an aqueous solution containing guar gum (0.43 wt%) and nitric acid (2.3 wt%) was added to the mixture to conduct rolling into a paste, and then the paste was extruded to obtain a strand, and the extruded strand was dried at 120 ℃ for 4 hours and calcined at 550 ℃ for 3 hours to obtain a support Z4.

(II) catalyst preparation

The carrier Z4 is impregnated with W, Ni-containing impregnation liquid in the same volume, dried at 120 ℃ for 3h, and calcined at 440 ℃ for 3h to obtain the final catalyst which is marked as C-4, and the properties of the catalyst are shown in Table 1.

Comparative example 1

Preparation of hydrocracking catalyst carrier

Respectively weighing template agent triblock copolymer P123 and silicon source tetraethoxysilane, wherein the mass of the template agent P123 is 5.5g, and the mass of tetraethoxysilane is 10.2 g; adding a template agent and a silicon source into an HCl solution with the pH value of 2.8, and fully stirring for 30 hours at the temperature of 28 ℃; standing and crystallizing the stirred mixture for 20h at 120 ℃, washing with deionized water, and drying to obtain SBA-15. Pulping the obtained SBA-15 molecular sieve with a solid-to-liquid ratio of 1:10, adding the obtained SBA-15 molecular sieve into hydrochloric acid solution containing 23g of aluminum isopropoxide, heating to 100 ℃, stirring for 20 hours, and cooling to room temperature to obtain a mixed system F.

Pumping 12g of USY molecular sieve slurry (same as example 1) into a mixed system of the mixed solution F by a vacuum pump, drying at 110 ℃ for 4h after crystallization time of 12h at the pH value of 3.7 and the temperature of 100 ℃, and roasting at 540 ℃ for 4h to obtain a finished product YAS-5.

15g of YAS-5 molecular sieve and 5g of modified beta molecular Sieve (SiO)₂/Al₂O₃The molar ratio is 62, the specific surface area is 580m²(same as example 1) 80g of alumina (pore volume: 0.48 mL/g) was added to a roll mill to conduct rolling for 25 minutes, an aqueous solution containing guar gum (0.43 wt%) and nitric acid (2.3 wt%) was added to the mixture to conduct rolling into a paste, and then the paste was extruded to obtain a strand, and the extruded strand was dried at 120 ℃ for 4 hours and calcined at 550 ℃ for 3 hours to obtain a support Z5.

(II) catalyst preparation

The carrier Z5 was impregnated with equal volume of W, Ni-containing impregnation solution, dried at 120 ℃ for 3h, calcined at 440 ℃ for 3h to obtain the final catalyst C-5, the properties of which are shown in Table 2.

Comparative example 2

Preparation of hydrocracking catalyst carrier

Adding 5g of P123 into 2mol/L125mL hydrochloric acid solution, and stirring at 40 ℃ until the P123 is completely dissolved; adding 8.5g of tetraethoxysilane into hydrochloric acid solution containing P123, stirring for 4 hours, adding aluminum nitrate to enable the molar ratio of silicon to aluminum to be 40, continuing to stir for 20 hours, adding the solution into a 250mL reaction kettle, stirring for 48 hours at 100 ℃, cooling to room temperature, adjusting the pH value to 7.5 by using 4mol of ammonia water solution, continuously stirring, heating to 100 ℃, stirring for 72 hours, and cooling to 40 ℃ to obtain mixed solution A for later use.

Pumping slurry containing 12g of USY molecular sieve (same as example 1) into a mixed system of the mixed solution A by a vacuum pump, drying at 110 ℃ for 4h after crystallization time of 12h at the pH value of 3.5 and the temperature of 100 ℃, and roasting at 540 ℃ for 4h to obtain a finished product YAS-6.

12g of YAS-6 molecular sieve and 8g of modified beta molecular Sieve (SiO)₂/Al₂O₃The molar ratio is 60, the specific surface area is 530m²(per g, pore volume 0.48 mL/g) 80g of alumina (same as example 1) was added to a roll mill to conduct rolling for 25 minutes, an aqueous solution containing guar gum (0.43 wt%) and nitric acid (2.3 wt%) was added thereto, the mixture was rolled into a paste, and then strands were extruded, and the extruded strands were dried at 120 ℃ for 4 hours and calcined at 550 ℃ for 3 hours to obtain a support Z6.

(II) catalyst preparation

The carrier Z6 was impregnated with an equal volume of W, Ni-containing impregnation solution, dried at 120 ℃ for 3h, calcined at 440 ℃ for 3h to obtain the final catalyst C-6, the properties of which are shown in Table 2.

Examples 5 to 9

Catalyst activity evaluation experiments were carried out using the catalysts C-1 to C-4 prepared in examples 1 to 4, respectively, specifically:

the properties of the feed oil used in the one-stage series process, carried out on a 200mL small scale hydrogenation unit, are shown in Table 3. Refining section operating conditions: the reaction temperature is 385 ℃, the hydrogen partial pressure is 14.5MPa, and the liquid hourly space velocity is 0.3h^-1Hydrogen-oil volume ratio 1500: 1, controlling the nitrogen content of refined oil to be 5-10 mu g/g; the cracking section operating conditions were as follows: the reaction temperature is 383 ℃, the hydrogen partial pressure is 14.5MPa, and the volume ratio of hydrogen to oil is 1200: 1, liquid hourly space velocity of 0.3h^-1. The results of the catalyst activity tests are shown in Table 4.

Comparative examples 3 to 4

The catalysts C-5 and C-6 prepared in comparative examples 1 to 2 were used for evaluation of catalyst activity, and the specific method was the same as in examples 5 to 9.

Comparative example 5

This comparative example illustrates that the composite molecular sieve prepared in example 1 is a Y/Al-SBA-15 composite molecular sieve, and compared to example 1, the Al-SBA-15 molecular sieve was synthesized directly without adding a USY molecular sieve slurry, as follows:

(1) preparation of amorphous silica-alumina dry gel powder A1 and slurry: sodium aluminate solution concentration 18gAl₂O₃Per L, sodium silicate solution concentration 100gSiO₂L, putting 0.75L of sodium aluminate solution into a gelling tank, then adding 0.35L of sodium silicate solution, controlling the reaction temperature to be 20 ℃, and introducing 40 v% CO₂Gas, introduction of CO₂When the gas accounts for 50 percent of the total input amount, 0.15L of sodium silicate solution is added while introducing gas, the pH value of the formed gel is controlled to be 9.5, then the ventilation is stabilized for 20 minutes, the slurry is filtered and washed to be neutral by deionized water at 65 ℃, a filter cake is added with water according to the solid-liquid volume ratio of 10: 1 for pulping, the treatment is carried out for 2 hours at the temperature of 130 ℃ and the water vapor pressure of 3.5MPa, and after the drying is carried out for 6 hours at the temperature of 120 ℃, the amorphous silica-alumina product A1 is obtained by crushing and sieving. The properties of the amorphous silica-alumina dry gel powder A1 are shown in Table 1. Mixing the prepared amorphous silica-alumina A1 with deionized water, and pulping to form slurry; wherein the mass ratio of the amorphous silica-alumina dry gel to water is 18: 82;

(3) mixing the slurry prepared in the step (1) with the acidic aqueous solution containing the P123 triblock copolymer prepared in the step (2); the Al-SBA-15 molecular sieve is prepared after crystallization, filtration, drying and roasting, and the serial number is A-S-1. The mass ratio of the P123 triblock copolymer to the amorphous silica-alumina in the mixed system is 1.2:1, the crystallization temperature is 90 ℃, and the crystallization time is 20 hours; controlling the pH value to be 3.3 in the crystallization process; and drying at 100 ℃ for 3h, and roasting at 550 ℃ for 3h to obtain the finished product Al-SBA-15 molecular sieve. The XRD pattern of the A-S-1 molecular sieve obtained in comparative example 5 is shown in FIG. 1, which shows the characteristic peak of Al-SBA-15 molecular sieve.

The Y/Al-SBA-15 composite molecular sieves prepared in the examples 1-4 of the invention all have XRD patterns similar to those of the comparative example 5, which shows that the Y/Al-SBA-15 composite molecular sieves are all the composite molecular sieves prepared in the examples 1-4.

TABLE 1 Properties of Y/Al-SBA-15 composite molecular sieves obtained in examples and comparative examples

Item	YAS-1	YAS-2	YAS-3	YAS-4	YAS-5	YAS-6
							Alumina content, wt%	24.9	28.95	38.71	63.52	20.89	15.24
The content of alumina in the Al-SBA-15 molecular sieve is wt%	21.26	25.53	34.91	60.24	17.25	11.6
							Specific surface area, m²/g	772	758	780	765	718	716
Pore volume, mL/g	0.59	0.61	0.57	0.65	0.45	0.46
							Relative degree of crystallinity after firing at 900%	98	98	97	98	88	86
Acid amount of medium strong acid, mL/g	0.72	0.75	0.83	0.86	0.62	0.66
							B/L	0.227	0.246	0.233	0.252	1.21	1.26
Hole distribution,%
							4～15nm	55.26	56.38	62.15	61.18	35.56	32.42
＞15nm	4.86	3.28	4.35	4.15	15.37	11.03

TABLE 2 composition and physico-chemical Properties of the catalysts

Item	C-1	C-2	C-3	C-4	C-5	C-6
							Specific surface area, m²/g	324	325	321	335	178	165
Pore volume, mL/g	0.43	0.44	0.42	0.43	0.32	0.29
							WO₃，wt%	23.1	23.6	22.9	23.3	22.8	23.2
NiO，wt%	5.94	5.92	5.91	5.96	5.87	5.83
							Moderate acid content of strong acid,%	42.32	41.08	43.05	45.07	30.08	28.95

TABLE 3 Properties of the feed oils

Analysis item	Coal tar
		Density (20 ℃), kg/m³	1120
Nitrogen,. mu.g/g	12600
		Distillation range/. degree.C
IBP/10%/30%/50%	170/230/305/340
		70%/90%/95%/EBP	370/415/435/466
Saturation fraction	0.6
		Aromatic component	67
Glue	32.2
		Asphaltenes	0.2
Water content%	1.86
		Residual carbon content%	0 .83
Flash point (closed mouth), deg.C	98
		Ni	0.025
V	0
		Fe	1.488
Na	0

TABLE 4 catalyst evaluation results

Item	C-1	C-2	C-3	C-4	C-5	C-6
							Heavy naphtha
Yield, wt.%	13.2	12.8	12.3	10.8	16.3	17.5
							Aromatic hydrocarbon, wt%	61.2	61.8	62.3	60.9	54.3	49.8
Diesel oil
							Yield, wt.%	82.3	85.5	85.8	84.6	78.5	73.2
Aromatic hydrocarbons, wt.%	10.2	8.8	8.2	9.3	25.6	35.3
							Cetane number	60	63	65	67	45	43
Freezing point, deg.C	-28	-29	-27	-28	-11	-12

The evaluation results in table 4 show that the coal tar hydrocracking catalyst of the present invention has good selectivity and good product properties on the basis of high activity.

TABLE 5 Properties of amorphous silica-alumina

Amorphous silica-alumina numbering	A1	A2	A3	A4
					Specific surface area, m²/g	489	518	509	515
Pore volume, mL/g	1.30	1.26	1.28	1.30
					Hole distribution,%
4～15nm	91	87	86	87
					＞15nm	2.8	3.7	4.6	4.5

Claims

1. A preparation method of a hydrocracking catalyst is characterized by comprising the following steps: the method comprises the following steps:

(i) preparing a Y/Al-SBA-15 composite molecular sieve;

2. The method of claim 1, wherein: the acid content of the medium strong acid of the Y/Al-SBA-15 composite molecular sieve is 0.6-1.2 mL/g, preferably 0.7-1.0 mL/g, and the ratio of the B acid to the L acid is less than 1.2.

3. The method of claim 1, wherein: in the Y/Al-SBA-15 composite molecular sieve, the mass content of alumina is 2-85%, preferably 5-82%.

4. The method of claim 1, wherein: the mass content of the Y/Al-SBA-15 composite molecular sieve is 5-25%, and preferably 8-15%.

5. The method of claim 1, wherein: in the Y/Al-SBA-15 composite molecular sieve, the mass content of alumina in the Al-SBA-15 molecular sieve is 5-75%.

6. The method of claim 1, wherein: the preparation method of the Y/Al-SBA-15 composite molecular sieve comprises the following steps:

(1) mixing amorphous silica-alumina dry gel and water to form slurry;

(2) preparing an acidic solution containing a P123 triblock copolymer;

7. The method of claim 6, wherein: the first crystallization conditions in the step (3) are as follows: the crystallization temperature is 80-120 ℃, the crystallization time is 10-35 h, and the pH value in the crystallization process is controlled to be 2.0-5.0; the conditions of the second crystallization are as follows: the crystallization temperature is 80-130 ℃, the crystallization time is 4-20 h, and the pH value in the crystallization process is controlled to be 2.0-5.0.

8. The method of claim 1, wherein: in step (ii), the preferred properties of the modified beta molecular sieve are as follows: SiO 2₂/Al₂O₃The molar ratio is 35-155, and the specific surface area is 510-850 m²The pore volume is 0.30-0.60 mL/g.

9. The method of claim 1, wherein: in step (ii), the properties of the alumina are as follows: the pore volume is 0.80-1.2 mL/g, the specific surface area is 140-360 m²(iv) g, the average pore diameter is 10 to 14 nm.

10. The method of claim 1, wherein: the hydrocracking catalyst carrier obtained in the step (ii) takes the weight of the hydrocracking catalyst carrier as a reference, and the weight content of the Y/Al-SBA-15 composite molecular sieve is 5% -25%; the weight content of the modified beta molecular sieve is 5-15%, and the weight content of the alumina is 60-90%.

11. The method of claim 1, wherein: in step (iii), the active metal component comprises a group VIB metal, preferably molybdenum and/or tungsten, and a group VIII metal, preferably cobalt and/or nickel; based on the weight of the hydrocracking catalyst, the content of VIB group metal calculated by oxide is 10-18 wt%, and the content of VIII group metal calculated by oxide is 4-8 wt%.

12. A hydrocracking catalyst prepared by the process as claimed in any one of claims 1 to 11.

13. The catalyst of claim 12, wherein: the hydrocracking catalyst had the following properties: the specific surface area is 200-500 m²Preferably 220 to 350 m/g²The pore volume is 0.30 to 0.65mL/g, preferably 0.35 to 0.60 mL/g.

14. An application of a hydrocracking catalyst in a coal tar hydrocracking process is characterized in that: the catalyst is a hydrocracking catalyst prepared according to the process of any one of claims 1 to 11 or a hydrocracking catalyst according to claim 12 or 13.

15. Use according to claim 14, characterized in that: the properties of the coal tar are as follows: the density is 1000 to 1200 kg/m³The nitrogen content is 0.8wt% -1.5 wt%, and the sulfur content is 0.2wt% -0.8 wt%.