Highly active anti-coking bifunctional hydrocracking catalyst and its preparation method

Abstract

This invention discloses a highly active anti-coking bifunctional hydrocracking catalyst and its preparation method, relating to the field of petroleum refining hydrocracking catalyst technology. This invention introduces silicon, an anti-coking factor, directly during the boehmite synthesis stage, embedding silicon atoms into the boehmite framework structure. After calcination, an alumina-silica composite support with specific surface chemistry is formed. The silicon element is uniformly distributed within the support framework, forming a stable Si-O-Al bonded structure after calcination. This structure effectively regulates the distribution and strength of acid centers on the support surface, reducing the number of strong acid centers and thus inhibiting the condensation and deposition of coke precursors at strong acid sites during the reaction. Simultaneously, the silicon-containing boehmite, after calcination, forms a support with a specific pore structure, providing a substrate for the uniform loading of subsequent active components and avoiding pore blockage and uneven distribution problems caused by the introduction of additives in post-processing.

Description

Technical Field

[0001] This invention relates to the field of petroleum refining hydrocracking catalyst technology, specifically to a highly active anti-coking bifunctional hydrocracking catalyst and its preparation method. Background Technology

[0002] Hydrocracking is a core process for the lightification of heavy oil, and its catalyst performance directly determines the unit's operating efficiency and product quality. Hydrocracking catalysts typically consist of an active metal component and an acidic support, possessing both hydrogenation and cracking functions. However, under the high-temperature and high-pressure conditions of hydrogen-induced reactions, carbon deposition and coking inevitably occur on the catalyst surface, leading to the covering of active centers and pore blockage, severely affecting the catalyst's lifespan and the long-term stable operation of the unit. Therefore, developing hydrocracking catalysts with both high activity and excellent anti-coking properties has always been a technical challenge and research hotspot in this field.

[0003] To address the coking problem of hydrocracking catalysts, existing technologies mainly employ the following improvement measures:

[0004] One approach is to optimize the catalyst pore structure by increasing the pore size and volume to delay pore blockage.

[0005] Second, it adjusts the compatibility between the active metal components and the acidic support to inhibit excessive pyrolysis reactions;

[0006] Third, anti-coking aids such as alkali metals, alkaline earth metals, or phosphorus are added to the catalyst to reduce the acid strength and acid density on the support surface.

[0007] However, the above methods all have obvious shortcomings: pore structure adjustment often comes at the cost of sacrificing specific surface area, resulting in a reduction in the number of active sites; the matching and regulation of active metals and acidity is difficult to balance high conversion rate and low coking rate; the introduction of anti-coking additives usually adopts the post-impregnation treatment method, the additives are unevenly distributed and easily block the pores, and cannot effectively inhibit the generation and deposition of coke precursors from the source of the carrier.

[0008] Therefore, there is an urgent need to develop a bifunctional catalyst that can enhance the anti-coking ability from the catalyst support itself while maintaining high hydrocracking activity, in order to solve the technical problem of shortened lifespan and limited operating cycle of existing catalysts due to coking. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a highly active, anti-coking bifunctional hydrocracking catalyst and its preparation method. This catalyst directly introduces silicon, an anti-coking factor, during the boehmite synthesis stage, embedding silicon atoms into the boehmite framework. After calcination, an alumina-silica composite support with specific surface chemistry is formed. Silicon is uniformly distributed within the support framework, forming a stable Si-O-Al bonded structure after calcination. This structure effectively regulates the distribution and strength of acid centers on the support surface, reducing the number of strong acid centers and thus inhibiting the condensation and deposition of coke precursors at strong acid sites during the reaction. Simultaneously, the silicon-containing boehmite, after calcination, forms a support with a specific pore structure, providing a substrate for the uniform loading of subsequent active components and avoiding pore blockage and uneven distribution problems caused by the introduction of additives in post-processing. This intrinsic anti-coking design solves the problem of preferential formation of coke precursors at strong acid sites from the material source, significantly delaying the carbon deposition and deactivation process while maintaining high pyrolysis activity of the catalyst.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: On the one hand, a highly active anti-coking bifunctional hydrocracking catalyst, based on 100% of the total weight of the highly active anti-coking bifunctional hydrocracking catalyst, the catalyst includes an active component and a support, wherein the active component includes tungsten oxide and nickel oxide, and the support includes alumina and silicon oxide;

[0011] The tungsten oxide content is 20-30%;

[0012] The content of nickel oxide is 5-10%;

[0013] The alumina content is 50-60%;

[0014] The content of silicon dioxide is 10-20%;

[0015] The catalyst has a specific surface area of ​​150-200 m² / g, a pore volume of 0.3-0.5 mL / g, and a pore size of 6-12 nm.

[0016] Furthermore, the alumina is derived from boehmite, which has a specific surface area of ​​300-400 m² / g, a pore volume of 0.7-1.1 mL / g, and a probable pore size of 10-12 nm.

[0017] The pseudoboehmite contains silicon, an anti-coking factor, at a content of 2.5-3.0%, and the silicon forms at least a portion of the silicon oxide in the catalyst.

[0018] Furthermore, the silica is derived from molecular sieves, which have a specific surface area of ​​600-700 m² / g, a pore volume of 0.1-0.2 mL / g, and a pore size of 2-4 nm.

[0019] Furthermore, the tungsten oxide and nickel oxide are uniformly distributed in the form of nanoparticles on the surface and within the pores of the carrier, and the particle size of the nanoparticles is 5-15 nm.

[0020] Furthermore, the catalyst has a bimodal pore size distribution, with the first peak located at 2-5 nm and the second peak located at 8-12 nm, and the pore volume with a pore size of 8-12 nm accounts for more than 60% of the total pore volume.

[0021] Furthermore, the total acidity of the catalyst is 0.3 mmol / g-0.5 mmol / g, wherein the proportion of weak acid centers in the total acidity is ≥70%, the proportion of medium-strong acid centers in the total acidity is 20%-25%, and the proportion of strong acid centers in the total acidity is ≤5%.

[0022] Furthermore, the mass ratio of the alumina to the silicon oxide is (2.5-6):1.

[0023] Furthermore, the mass ratio of the pseudoboehmite to the molecular sieve is (2-6):1.

[0024] On the other hand, the specific steps of this preparation method are as follows:

[0025] S100, Carrier precursor mixing: Boehmite, molecular sieve, guar gum powder, and hydroxymethyl cellulose are placed in a kneader and stirred for 10 minutes to obtain a solid mixture. An inorganic acid aqueous solution with a pH of 2-4 is prepared and added to the kneader. The mixture is kneaded with the solid mixture until a uniform agglomerate is formed. The amount of deionized water added is adjusted to control the dryness and moisture content of the agglomerate.

[0026] S200, Carrier Forming and Calcination: The uniform agglomerated material obtained in S100 is transferred to an extruder and extruded using a 2.0mm clover-shaped die to obtain a clover-shaped catalyst carrier precursor. The catalyst carrier precursor is left to stand at room temperature for 6 hours, then placed in a drying equipment and dried at 50℃-100℃ for 4 hours. It is then placed in a muffle furnace and heated to 500℃-550℃ at a heating rate of 3℃ / min, and calcined at a constant temperature for 4 hours to obtain the catalyst carrier.

[0027] S300, Impregnation solution preparation: Add soluble tungsten salt and soluble nickel salt to deionized water, stir thoroughly to dissolve, and prepare a stable impregnation solution;

[0028] S400, Impregnation and Calcination Activation: The catalyst support obtained in S200 is mixed with the impregnation solution obtained in S300 and impregnated for 2 hours to obtain the impregnated material. The impregnated material is placed in a drying device and dried at 50℃-100℃ for 4 hours. Then it is placed in a muffle furnace and heated to 300℃-500℃ at a heating rate of 3℃ / min. It is then calcined at a constant temperature for 4 hours to obtain a highly active anti-coking bifunctional hydrocracking catalyst.

[0029] Furthermore, in S100, the inorganic acid is at least one of nitric acid and citric acid, and the total added mass of guar gum powder and hydroxymethyl cellulose is 2%-5% of the total mass of boehmite and molecular sieve.

[0030] In the S300, the soluble tungsten salt is ammonium metatungstate, and the soluble nickel salt is nickel nitrate;

[0031] In the S400, the impregnation is carried out by an equal volume impregnation method, and the volume ratio of the impregnation liquid to the pore volume of the catalyst support is (1.05-1.1):1.

[0032] Compared with existing technologies, this highly active anti-coking bifunctional hydrocracking catalyst and its preparation method have the following advantages:

[0033] I. This invention introduces silicon, an anti-coking factor, directly into the boehmite synthesis stage, embedding silicon atoms into the boehmite framework structure. After calcination, an alumina-silica composite support with specific surface chemistry is formed. The silicon element is uniformly distributed in the support framework, forming a stable Si-O-Al bonded structure after calcination. This structure can effectively regulate the distribution and acid strength of acid centers on the support surface, reducing the number of strong acid centers, thereby inhibiting the condensation and deposition of coke precursors at strong acid sites during the reaction. At the same time, the silicon-containing boehmite forms a support with a specific pore structure after calcination, providing a substrate for the uniform loading of subsequent active components and avoiding the problems of pore blockage and uneven distribution caused by the introduction of additives in post-processing. This intrinsic anti-coking design of the support solves the problem of preferential formation of coke precursors at strong acid sites from the material source, enabling the catalyst to maintain high pyrolysis activity while significantly delaying the carbon deposition and deactivation process.

[0034] Second, the catalyst of this invention exhibits a bimodal pore size distribution. This pore structure is synergistically constructed from silica-containing pseudoboehmite and molecular sieves. The 8-12 nm mesopores serve as the main channels for transporting reactants and products, effectively reducing internal diffusion resistance and the residence time of reactant molecules within the channels, thereby reducing the probability of secondary coking due to excessive cracking. Meanwhile, the 2-5 nm micropores provide sufficient specific surface area and acid centers to ensure the activity of the catalytic cracking reaction. The active components, tungsten oxide and nickel oxide, are uniformly distributed on the surface of the bimodal pores in the form of 5-15 nm nanoparticles. This particle size distribution ensures both the high dispersion of the active components and avoids the risk of sintering deactivation due to excessively small particles, allowing reactant molecules to quickly enter and exit the catalytic reaction zone. This significantly reduces the chance of secondary reactions and deposition of coke precursors within the channels, thus effectively inhibiting coking from the reaction kinetics perspective while maintaining high hydrocracking activity, achieving a balance between anti-coking performance and high catalytic activity.

[0035] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0037] Figure 1 A flowchart of a method for preparing a highly active anti-coking bifunctional hydrocracking catalyst;

[0038] Figure 2 A flowchart illustrating the steps involved in preparing a highly active, anti-coking bifunctional hydrocracking catalyst. Detailed Implementation

[0039] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0040] To address the shortcomings of existing petroleum refining hydrocracking catalysts, such as decreased activity due to coking, pore blockage, and shortened lifespan, as well as the difficulties in achieving both uneven additive distribution and optimal pore structure and specific surface area in existing anti-coking modification methods, this invention provides a highly active anti-coking bifunctional hydrocracking catalyst and its preparation method. The aim is to pre-embed the anti-coking factor silicon element into the framework structure during the pseudo-boehmite synthesis stage to form a uniformly distributed and stable Si-O-Al bonded support. Combined with a bimodal pore structure design and synergistic loading of nanoscale active components, a bifunctional catalyst system with intrinsic anti-coking capability and high hydrocracking activity is constructed.

[0041] This invention is primarily applied to heavy oil hydrocracking processes in petrochemicals and coal tar processing. In these scenarios, the catalyst needs to operate under high temperature, high pressure, and hydrogen-rich conditions for extended periods. Coking is a core bottleneck restricting the long-term stable operation of the unit. Traditional methods, such as introducing anti-coking additives through post-treatment or adjusting the single pore structure, are insufficient to effectively suppress the formation and deposition of coke precursors from both the carrier's intrinsic and reaction kinetic perspectives. This invention addresses the challenge of simultaneously achieving high activity and anti-coking performance by synergistically combining three key elements: constructing an anti-coking carrier from silica-containing boehmite, optimizing mass transfer efficiency through a bimodal pore structure, and ensuring uniform distribution of nano-active components. This systematically solves the problem of the difficulty in achieving both high activity and anti-coking performance from two dimensions: regulating the surface chemical properties of the carrier and optimizing the reaction mass transfer pathway. This provides a complete technical solution for the long-term stable operation of hydrocracking catalysts.

[0042] Performance Testing Methodology Description

[0043] In all embodiments and comparative examples of this invention, the physicochemical structure characterization and hydrocracking performance evaluation of the catalysts were conducted using a unified testing method to ensure the comparability and accuracy of the data. Specifically:

[0044] I. Physical and chemical structural characterization methods

[0045] Specific surface area, pore volume and pore size distribution: The nitrogen adsorption-desorption method was used. The sample was first degassed under vacuum at 300℃ for 4h, and then nitrogen adsorption test was carried out in liquid nitrogen atmosphere at -196℃. The specific surface area was calculated by BET model, and the pore volume, pore size distribution and probabilistic pore size were calculated by BJH model. At the same time, the bimodal pore structure characteristics were confirmed.

[0046] Acidity and Acid Distribution: The temperature-programmed ammonia desorption method (NH3-TPD) was used. Samples were pretreated at 500℃ in a helium atmosphere for 1 h, then cooled to 100℃ to saturate with adsorbed NH3. After helium purging to remove physically adsorbed NH3, the temperature was increased to 600℃ at a rate of 10℃ / min, and the desorption curves were recorded. The desorption peaks at 100-250℃ corresponded to weak acid centers, 250-400℃ to medium-strong acid centers, and 400-600℃ to strong acid centers. The total acidity and the proportion of each acid center were calculated based on these values.

[0047] Active metal particle size and distribution: Using transmission electron microscopy (TEM), 200 metal particles were randomly selected to statistically analyze their particle size distribution and calculate the average particle size. At the same time, the dispersion of metal particles on the carrier surface and in the pores was confirmed.

[0048] Carbon deposition test: Thermogravimetric-differential scanning calorimetry (TG-DSC) was used. In an air atmosphere, the temperature was increased from room temperature to 800℃ at a rate of 10℃ / min. The mass loss in the range of 300-600℃ was recorded, which is the mass fraction of carbon deposition on the catalyst after the reaction.

[0049] II. Evaluation Methods for Hydrocracking Catalytic Performance

[0050] Evaluation apparatus: Fixed-bed high-pressure hydrocracking experimental apparatus, catalyst loading 10 mL, catalyst crushed to 20-40 mesh, with quartz sand filling the upper and lower ends for support and dispersion of the gas flow.

[0051] Reactant: Vacuum gas oil (VGO), with the following properties: density at 20℃ 0.9218 g / cm³, distillation range 350-520℃, sulfur content 1250 μg / g, nitrogen content 850 μg / g, and carbon residue 0.28 wt%.

[0052] Pretreatment conditions: The catalyst was pre-sulfurized before the reaction. The sulfiding oil was straight-run kerosene containing 2 wt% carbon disulfide. Sulfidation conditions: reaction pressure 15 MPa, temperature 320℃, isothermal sulfidation for 8 h, hydrogen-to-oil volume ratio 800:1, liquid hourly space velocity 1.0 h⁻¹. -1 .

[0053] Reaction conditions: reaction temperature 380℃, reaction pressure 15MPa, hydrogen-to-oil volume ratio 1200:1, liquid hourly space velocity 1.5h⁻¹ -1 .

[0054] Performance index calculation:

[0055] Hydrocracking conversion rate: Conversion rate (wt%) = (Mass of >350℃ fraction in feedstock - Mass of >350℃ fraction in product) / Mass of >350℃ fraction in feedstock × 100%;

[0056] Middle distillate oil yield:

[0057] Middle distillate oil (180-350℃ diesel fraction) yield (wt%) = mass of 180-350℃ fraction in product / total mass of feedstock × 100%;

[0058] Catalyst lifetime:

[0059] The effective life of the catalyst is the cumulative reaction time from the initial conversion rate after 4 hours of stable operation after pre-sulfurization to the point where the conversion rate decreases by 10% from the initial value.

[0060] Carbon deposit amount: After 100 hours of continuous reaction, the catalyst was removed and its carbon deposit mass fraction was tested by TG-DSC.

[0061] Example 1

[0062] This embodiment uses typical component ratios and standard preparation processes to clarify the core composition of the catalyst, the source of the support, the pore structure, the acid distribution, and the active metal distribution parameters, and to verify the basic hydrocracking activity and anti-coking performance of the catalyst, providing a benchmark for all embodiments and comparative examples.

[0063] Catalyst composition and design parameters:

[0064] Based on the total mass of the catalyst (100%), the catalyst composition in this embodiment is: 25% tungsten oxide, 8% nickel oxide, 55% aluminum oxide, and 12% silicon oxide; the mass ratio of aluminum oxide to silicon oxide is 4.58:1.

[0065] Vector source parameters:

[0066] Boehmite: specific surface area on a dry basis of 350 m² / g, pore volume of 0.9 mL / g, pore size of 11 nm, elemental silicon content of 2.8% (dry basis), and the silica formed after calcination accounts for 28.5% of the total silica in the catalyst;

[0067] Molecular sieve: USY type molecular sieve, specific surface area 650m² / g, pore volume 0.15mL / g, pore size 3nm, SiO2 / Al2O3 molar ratio 12, and the silica formed after calcination accounts for 71.5% of the total silica in the catalyst;

[0068] The dry-basis mass ratio of boehmite to molecular sieve is 5.85:1.

[0069] Target physicochemical parameters of the catalyst: specific surface area 170 m² / g, pore volume 0.4 mL / g, pore size 8 nm, bimodal pore size distribution (first peak 2-5 nm, second peak 8-12 nm), pore volume of 8-12 nm accounts for 62% of the total pore volume, total acidity 0.42 mmol / g, weak acid sites account for 72%, medium-strong acid sites account for 23%, strong acid sites account for 5%, average particle size of active metal nanoparticles 10 nm, particle size range 5-15 nm.

[0070] Taking the preparation of 100g of finished catalyst as an example, such as Figure 1 and Figure 2 As shown, the preparation process and specific steps of this highly active anti-coking bifunctional hydrocracking catalyst are as follows:

[0071] S100, Carrier Precursor Mixing: Weigh 57.22g of silica-containing boehmite (dry basis), 9.78g of USY molecular sieve (dry basis), 1.0g of guar gum powder, and 1.0g of hydroxymethyl cellulose. Place them in a kneader and mix at room temperature for 10 minutes to obtain a solid mixture. Prepare a nitric acid aqueous solution with a pH of 3 and slowly add it to the kneader. Continue kneading with the solid mixture, and simultaneously add deionized water to adjust the dryness and moisture content of the material until a uniform and plastic agglomerated material is formed. The total amount of guar gum powder and hydroxymethyl cellulose added is 2.99% of the total dry basis mass of boehmite and molecular sieve.

[0072] S200, Carrier Forming and Calcination: The above-mentioned agglomerated material is transferred to an extruder and extruded using a 2.0mm clover-shaped die to obtain a clover-shaped catalyst carrier precursor; the precursor is aged at room temperature for 6 hours, then placed in a forced-air drying equipment and dried at 80℃ for 4 hours; subsequently, the dried precursor is placed in a muffle furnace and heated to 520℃ at a heating rate of 3℃ / min, calcined at a constant temperature for 4 hours, and then naturally cooled to room temperature to obtain the catalyst carrier with a total dry basis mass of 67g.

[0073] S300, Impregnation solution preparation: Weigh 30.49g of ammonium metatungstate (WO3 mass fraction ≥82%) and 32.00g of nickel nitrate hexahydrate (NiO mass fraction ≥25%), add them to 25mL of deionized water, stir thoroughly until completely dissolved, and adjust the volume to 28.14mL to prepare a stable and homogeneous impregnation solution; the volume ratio of the impregnation solution to the total pore volume of the catalyst support is 1.05:1.

[0074] S400, Impregnation and Calcination Activation: The catalyst support prepared above is mixed with the impregnation solution and impregnated in equal volume for 2 hours at room temperature and pressure, turning it over every 30 minutes to ensure uniform impregnation, and the impregnated material is obtained; the impregnated material is placed in a forced-air drying equipment and dried at 80℃ for 4 hours; then it is placed in a muffle furnace and heated to 450℃ at a heating rate of 3℃ / min, and calcined at a constant temperature for 4 hours, and then naturally cooled to room temperature to obtain a highly active anti-coking bifunctional hydrocracking catalyst.

[0075] Performance testing

[0076] Physicochemical structural characterization results: The catalyst has a measured specific surface area of ​​172 m² / g, a pore volume of 0.41 mL / g, and a pore size of 8.2 nm; it exhibits a bimodal pore size distribution, with the first peak at 3.2 nm and the second peak at 9.1 nm, and the pore volume of 8-12 nm pores accounts for 63% of the total pore volume; the total acid content is 0.42 mmol / g, with weak acid centers accounting for 73%, medium-strong acid centers accounting for 22%, and strong acid centers accounting for 5%; the average particle size of the active metal nanoparticles is 9.8 nm, with a particle size range of 5-14 nm, and they are uniformly distributed on the surface of the support and within the pores, without agglomeration.

[0077] Hydrocracking performance evaluation results: initial hydrocracking conversion rate was 78.5 wt%, and middle distillate oil yield was 45.2 wt%; after 100 h of reaction, the conversion rate remained at 76.1 wt%, and the catalyst carbon deposition was 3.2 wt%; when the reaction continued until the conversion rate decreased by 10%, the cumulative lifespan was 1280 h.

[0078] The catalyst prepared in this embodiment achieves precise control of acid centers by introducing silica-containing pseudoboehmite in situ. The target bimodal pore structure is constructed through the synergistic effect of pseudoboehmite and molecular sieve. The active metal is uniformly dispersed at the nanoscale, ultimately achieving a balance between hydrocracking activity and anti-coking performance.

[0079] Example 2

[0080] This embodiment is a parameter lower limit verification scheme. It uses the lower limit range parameters of the ratio of active component and support, with 20% tungsten oxide and 5% nickel oxide as the lower limit content of active component. It verifies the hydrocracking activity and anti-coking performance of the catalyst under low active component loading and low silicon content, and proves the feasibility and stability of the technical solution of the present invention within the parameter lower limit range.

[0081] Catalyst composition and design parameters:

[0082] Based on the total mass of the catalyst (100%), the catalyst composition in this embodiment is as follows: tungsten oxide 20%, nickel oxide 5%, aluminum oxide 60%, and silicon oxide 15%; the mass ratio of aluminum oxide to silicon oxide is 4:1, the dry basis mass ratio of boehmite to molecular sieve is 5:1, and the elemental silicon content of boehmite is 2.5% (dry basis).

[0083] Target physicochemical parameters of the catalyst: specific surface area 165 m² / g, pore volume 0.38 mL / g, pore size 9 nm, bimodal pore size distribution, pore volume of 8-12 nm accounting for more than 60% of the total pore volume, total acidity 0.35 mmol / g, weak acid center proportion ≥70%, and active metal nanoparticle size range of 5-15 nm.

[0084] The preparation method, taking the preparation of 100g of finished catalyst as an example, includes the following specific steps:

[0085] Carrier precursor mixing: Weigh 62.5g of silica-containing pseudoboehmite (dry basis), 12.5g of USY molecular sieve (dry basis), 1.2g of guar gum powder, and 0.8g of hydroxymethyl cellulose. Place them in a kneader and mix for 10 minutes to obtain a solid mixture. Prepare a nitric acid-citric acid mixed aqueous solution with a pH of 4 (nitric acid to citric acid mass ratio 1:1). Slowly add the solution to the kneader and knead. Add deionized water to adjust the mixture to a uniform agglomerate.

[0086] Carrier forming and calcination: The lumpy material was extruded into a 2.0 mm clover mold, left to stand at room temperature for 6 hours, dried at 100℃ for 4 hours, heated to 500℃ in a muffle furnace at 3℃ / min, and calcined at a constant temperature for 4 hours to obtain 75 g catalyst carrier.

[0087] Preparation of impregnation solution: Weigh 24.39 g of ammonium metatungstate and 20.00 g of nickel nitrate hexahydrate, dissolve them in deionized water, and make up to 29.93 mL. The volume ratio of impregnation solution to total pore volume of carrier is 1.05:1.

[0088] Impregnation and calcination activation: The carrier is mixed with the impregnation solution and impregnated for 2 hours, dried at 100℃ for 4 hours, heated to 400℃ in a muffle furnace at 3℃ / min, and calcined at a constant temperature for 4 hours to obtain the finished catalyst.

[0089] Performance testing

[0090] Physicochemical structural characterization results: The catalyst has a measured specific surface area of ​​168 m² / g, a pore volume of 0.39 mL / g, and a pore size of 8.8 nm; it exhibits a bimodal pore size distribution, with pores of 8-12 nm accounting for 61% of the total pore volume; the total acid content is 0.36 mmol / g, with weak acid centers accounting for 74%, medium-strong acid centers accounting for 23%, and strong acid centers accounting for 3%; the average particle size of the active metal nanoparticles is 10.2 nm, with a particle size range of 6-14 nm, and they are uniformly dispersed.

[0091] Hydrocracking performance evaluation results: initial hydrocracking conversion rate was 72.3 wt%, and middle distillate oil yield was 43.8 wt%; after 100 h of reaction, the conversion rate remained at 70.5 wt%, and the catalyst carbon deposition was 2.8 wt%; when the reaction continued until the conversion rate decreased by 10%, the cumulative lifespan was 1150 h.

[0092] This embodiment successfully prepared a catalyst with both qualified hydrocracking activity and excellent anti-coking performance within the limited lower limit of parameters. It has a high proportion of weak acid centers and a low carbon deposition rate. Even under low active component loading conditions, it can still maintain long-term stable operation, proving the applicability of the technical solution of this invention. There is no significant performance drop at the lower limit parameters, which has good tolerance for industrial application.

[0093] Example 3

[0094] This embodiment is a parameter upper limit verification scheme. It adopts the upper limit range parameters of the ratio of active component and support, with 30% tungsten oxide and 10% nickel oxide as the upper limit content of active component. It verifies the hydrocracking activity, metal dispersion and anti-coking performance of the catalyst under high active component loading and high silicon content, and proves the feasibility and stability of the technical solution of the present invention within the parameter upper limit range.

[0095] Catalyst composition and design parameters:

[0096] Based on the total mass of the catalyst (100%), the catalyst composition in this embodiment is: 30% tungsten oxide, 10% nickel oxide, 50% aluminum oxide, and 10% silicon oxide; the mass ratio of aluminum oxide to silicon oxide is 5:1, the dry-basis mass ratio of boehmite to molecular sieve is 2:1, and the elemental silicon content of boehmite is 3.0% (dry basis).

[0097] Target physicochemical parameters of the catalyst: specific surface area 180 m² / g, pore volume 0.45 mL / g, pore size 7 nm, bimodal pore size distribution, pore volume of 8-12 nm accounting for more than 60% of the total pore volume, total acidity 0.48 mmol / g, weak acid center proportion ≥70%, active metal nanoparticle size range 5-15 nm, and no agglomeration.

[0098] The preparation method, taking the preparation of 100g of finished catalyst as an example, includes the following specific steps:

[0099] Carrier precursor mixing: Weigh 40.0g of silica-containing pseudoboehmite (dry basis), 20.0g of USY molecular sieve (dry basis), 1.5g of guar gum powder, and 1.5g of hydroxymethyl cellulose. Place them in a kneader and mix for 10 minutes to obtain a solid mixture. Prepare a nitric acid aqueous solution with a pH of 2 and slowly add it to the kneader for mixing. Add deionized water to adjust the mixture to a uniform agglomerate.

[0100] Carrier forming and calcination: The lumpy material was extruded into a 2.0 mm clover mold, left to stand at room temperature for 6 h, dried at 50 °C for 4 h, and then calcined in a muffle furnace at a constant temperature of 3 °C / min to 550 °C for 4 h to obtain 60 g of catalyst carrier.

[0101] Preparation of impregnation solution: Weigh 36.59 g of ammonium metatungstate and 40.00 g of nickel nitrate hexahydrate, dissolve them in deionized water, and make up to 29.70 mL. The volume ratio of impregnation solution to total pore volume of carrier is 1.1:1.

[0102] Impregnation and calcination activation: The carrier is mixed with the impregnation solution and impregnated for 2 hours, dried at 50°C for 4 hours, heated to 500°C in a muffle furnace at 3°C / min, and calcined at a constant temperature for 4 hours to obtain the finished catalyst.

[0103] Performance testing

[0104] Physicochemical structural characterization results: The catalyst has a measured specific surface area of ​​178 m² / g, a pore volume of 0.44 mL / g, and a pore size of 7.2 nm; it exhibits a bimodal pore size distribution, with pores of 8-12 nm accounting for 60% of the total pore volume; the total acid content is 0.47 mmol / g, with weak acid centers accounting for 71%, medium-strong acid centers accounting for 24%, and strong acid centers accounting for 5%; the average particle size of the active metal nanoparticles is 11.5 nm, with a particle size range of 7-15 nm, and no obvious agglomeration phenomenon.

[0105] Hydrocracking performance evaluation results: initial hydrocracking conversion rate was 83.6 wt%, and middle distillate oil yield was 44.5 wt%; after 100 h of reaction, the conversion rate remained at 80.2 wt%, and the catalyst carbon deposition was 3.6 wt%; the cumulative lifespan was 1220 h when the conversion rate decreased by 10% during continuous reaction.

[0106] This embodiment successfully prepared a highly active hydrocracking catalyst within the limited upper limit of parameters. The high loading of active metal still maintained nanoscale uniform dispersion without agglomeration or pore blockage. At the same time, the regulation of the framework silicon effectively suppressed coking caused by strong acid centers. It maintained excellent anti-coking performance and long-term stability even at high conversion rates, proving that the technical solution of this invention can take into account both high activity and anti-coking ability, and still has excellent comprehensive performance under the upper limit of parameters.

[0107] Example 4

[0108] This embodiment is a preferred implementation of the present invention. It optimizes the bimodal pore structure, acid distribution, active metal particle size and dispersibility. By precisely controlling the carrier ratio and preparation process, it achieves the optimal balance between hydrocracking activity and anti-coking performance, thus verifying the comprehensive performance advantages of the preferred technical solution of the present invention.

[0109] Catalyst composition and design parameters:

[0110] Based on the total mass of the catalyst (100%), the catalyst composition in this embodiment is as follows: tungsten oxide 28%, nickel oxide 9%, aluminum oxide 53%, and silicon oxide 10%; the mass ratio of aluminum oxide to silicon oxide is 5.3:1, the dry mass ratio of boehmite to molecular sieve is 3.5:1, and the elemental silicon content of boehmite is 2.9%.

[0111] Target physicochemical parameters of the catalyst: specific surface area 175 m² / g, pore volume 0.42 mL / g, pore size 9 nm; bimodal pore size distribution, first peak 2-5 nm, second peak 8-12 nm, pore volume of 8-12 nm ≥65% of total pore volume; total acidity 0.40 mmol / g, weak acid centers ≥75%, strong acid centers ≤4%; active metal nanoparticles with a particle size range of 8-12 nm, average particle size 10 nm, uniformly distributed on the surface of the support and within the pores.

[0112] The preparation method, taking the preparation of 100g of finished catalyst as an example, includes the following specific steps:

[0113] Carrier precursor mixing: Weigh 48.22g of silica-containing pseudoboehmite (dry basis), 13.78g of USY molecular sieve (dry basis), 1.2g of guar gum powder, and 1.0g of hydroxymethyl cellulose. Place them in a kneader and mix for 10 minutes to obtain a solid mixture. Prepare a nitric acid aqueous solution with a pH of 2.5 and slowly add it to the kneader for mixing. Add deionized water to adjust the mixture to a uniform agglomerate.

[0114] Carrier forming and calcination: The lumpy material was extruded into a 2.0 mm clover mold, left to stand at room temperature for 6 h, dried at 90 °C for 4 h, and then calcined in a muffle furnace at a rate of 3 °C / min to 530 °C for 4 h to obtain 62 g of catalyst carrier.

[0115] Preparation of impregnation solution: Weigh 34.15 g of ammonium metatungstate and 36.00 g of nickel nitrate hexahydrate, dissolve them in deionized water, and make up to 27.34 mL. The volume ratio of impregnation solution to total pore volume of carrier is 1.08:1.

[0116] Impregnation and calcination activation: The carrier is mixed with the impregnation solution and impregnated for 2 hours, dried at 90°C for 4 hours, heated to 420°C in a muffle furnace at 3°C / min, and calcined at a constant temperature for 4 hours to obtain the finished catalyst.

[0117] Performance testing

[0118] Physicochemical structural characterization results: The catalyst has a measured specific surface area of ​​176 m² / g, a pore volume of 0.42 mL / g, and a pore size of 8.9 nm; it exhibits an excellent bimodal pore size distribution, with the first peak at 3.5 nm and the second peak at 9.5 nm, and the pore volume of 8-12 nm accounts for 68% of the total pore volume; the total acid content is 0.40 mmol / g, with weak acid centers accounting for 78%, medium-strong acid centers accounting for 19%, and strong acid centers accounting for 3%; the average particle size of the active metal nanoparticles is 9.5 nm, with a particle size range of 8-12 nm, and they are highly uniformly dispersed on the surface of the support and within the pores.

[0119] Hydrocracking performance evaluation results: initial hydrocracking conversion rate was 81.2 wt%, and middle distillate oil yield was 46.8 wt%; after 100 h of reaction, the conversion rate remained at 79.5 wt%, and the catalyst carbon deposition was 2.5 wt%; when the reaction continued until the conversion rate decreased by 10%, the cumulative lifespan was 1560 h.

[0120] This embodiment effectively reduces internal diffusion resistance and the probability of secondary coking through a high proportion of mesoporous channels. The high proportion of weak acid centers inhibits the formation of coke precursors from the source. The narrow distribution of nano-active metals achieves a balance between high activity and high stability. Ultimately, the catalyst maintains a high hydrocracking conversion rate while achieving the highest middle distillate oil yield, the lowest carbon deposition, and the longest service life.

[0121] Comparative Example 1

[0122] This comparative example is a blank control scheme. The core difference is that the in-situ introduction of silicon in the synthesis stage of the pseudoboehmite of this invention was not adopted. Instead, conventional silicon-free pseudoboehmite was used, and silicon was introduced by impregnation after silica sol. The total content of other catalyst components and the preparation process parameters are completely consistent with those of Example 1. This is used to verify the core technical advantages of in-situ introduction of silicon in the support framework in regulating acid distribution and improving anti-coking performance.

[0123] Catalyst composition and differences:

[0124] Based on 100% of the total mass of the catalyst, the total composition of the catalyst in this comparative example is: 25% tungsten oxide, 8% nickel oxide, 55% aluminum oxide, and 12% silicon oxide, which is completely consistent with Example 1;

[0125] The core differences are:

[0126] The pseudoboehmite is a conventional silicon-free pseudoboehmite with a dry basis specific surface area of ​​350 m² / g, a pore volume of 0.9 mL / g, a possible pore size of 11 nm, and an elemental silicon content of <0.1%.

[0127] The silica was entirely derived from USY molecular sieves and post-impregnated silica sol. The mass of silica introduced by the silica sol was the same as that introduced in situ by boehmite in Example 1, which was 3.42 g.

[0128] The preparation method, taking the preparation of 100g of finished catalyst as an example, includes the following specific steps:

[0129] Carrier precursor mixing: Weigh 57.22g of silica-free pseudoboehmite, 9.78g of USY molecular sieve, 1.0g of guar gum powder, and 1.0g of hydroxymethyl cellulose on a dry basis, place them in a kneader and stir for 10 minutes. Prepare a nitric acid aqueous solution with a pH of 3 and knead until a uniform agglomerate is formed, consistent with Example 1.

[0130] Carrier molding and calcination: The extrusion molding, standing, drying and calcination process is completely consistent with that in Example 1, and a silicon-free initial carrier is obtained with a total dry weight of 67g.

[0131] Silicon element impregnation: Prepare a silica sol aqueous solution, and use the equal volume impregnation method to impregnate the initial carrier for 2 hours, dry at 80℃ for 4 hours, and calcine at 520℃ for 4 hours to make the total silicon oxide content in the carrier reach 12%, thus obtaining a silicon-containing carrier.

[0132] Activated metal impregnation and calcination: The impregnation solution preparation, impregnation process, drying and calcination activation parameters were completely consistent with those in Example 1, and a comparative catalyst was obtained.

[0133] Performance testing

[0134] Physicochemical structural characterization results: The catalyst has a measured specific surface area of ​​155 m² / g, a pore volume of 0.35 mL / g, and a pore size of 7.5 nm; there is no obvious bimodal pore size distribution, and the pore volume of 8-12 nm accounts for 48% of the total pore volume; the total acid content is 0.45 mmol / g, with weak acid centers accounting for 58%, medium-strong acid centers accounting for 30%, and strong acid centers accounting for 12%; the average particle size of the active metal nanoparticles is 14.5 nm, and local aggregation occurs.

[0135] Hydrocracking performance evaluation results: The initial hydrocracking conversion rate was 71.6 wt%, and the middle distillate oil yield was 40.2 wt%; after 100 h of reaction, the conversion rate dropped to 64.3 wt%, and the catalyst carbon deposition was 8.7 wt%; when the reaction continued until the conversion rate decreased by 10%, the cumulative lifespan was only 420 h.

[0136] This comparative example introduced silicon via a post-impregnation method, which failed to achieve uniform embedding of silicon atoms within the alumina framework, thus hindering the formation of a stable Si-O-Al bond structure and the effective control of acid center distribution on the support. The proportion of strong acid centers significantly increased, failing to suppress coke precursor formation at its source. Furthermore, the post-impregnation process caused partial pore blockage, disrupting the bimodal pore structure, reducing specific surface area and pore volume, and decreasing the dispersion of active metals. Ultimately, the catalyst's hydrocracking activity, anti-coking performance, and service life were all significantly lower than in Example 1, verifying the decisive role of this characteristic in the catalyst's anti-coking performance and long-term stability.

[0137] Comparative Example 2

[0138] This comparative example is a structural control scheme. The core difference is that the bimodal pore structure constructed by the synergistic combination of boehmite and molecular sieve of this invention was not used. No molecular sieve was added to the support. Only a single-pore structure support was prepared using silica-containing boehmite. The total content of other catalyst components and the preparation process parameters are completely consistent with those of Example 1. This is used to verify the synergistic effect of the bimodal pore structure on hydrocracking activity and anti-coking performance.

[0139] Catalyst composition and differences:

[0140] Based on 100% of the total mass of the catalyst, the total composition of the catalyst in this comparative example is: 25% tungsten oxide, 8% nickel oxide, 55% aluminum oxide, and 12% silicon oxide, which is completely consistent with Example 1;

[0141] The core differences are:

[0142] No USY molecular sieve was added to the carrier; all carriers were prepared from silica-containing boehmite, and the parameters of the boehmite were exactly the same as in Example 1, with an elemental silicon content of 2.8%.

[0143] The carrier has a single-peak pore structure, with no 2-5nm microporous characteristic peaks, and only mesoporous characteristic peaks.

[0144] The preparation method, taking the preparation of 100g of finished catalyst as an example, includes the following specific steps:

[0145] Carrier precursor mixing: Weigh 67.0g of siliceous pseudoboehmite, 1.0g of guar gum powder and 1.0g of hydroxymethyl cellulose by dry basis, place them in a kneader and stir for 10min. Prepare a nitric acid aqueous solution with a pH of 3 and knead until a uniform agglomerate is formed. The remaining process is the same as in Example 1.

[0146] Carrier forming and calcination: The extrusion forming, standing, drying and calcination process is completely consistent with that in Example 1, and a single-peak pore structure catalyst carrier is obtained with a total dry weight of 67g.

[0147] Activated metal impregnation and calcination: The impregnation solution preparation, impregnation process, drying and calcination activation parameters were completely consistent with those in Example 1, and a comparative catalyst was obtained.

[0148] Performance testing

[0149] Physicochemical structural characterization results: The catalyst has a measured specific surface area of ​​120 m² / g, a pore volume of 0.42 mL / g, and a pore size of 10.5 nm; it exhibits a unimodal pore size distribution with no characteristic peaks of 2-5 nm micropores, and pores of 8-12 nm account for 72% of the total pore volume; the total acid content is 0.20 mmol / g, with weak acid centers accounting for 75%, medium-strong acid centers accounting for 22%, and strong acid centers accounting for 3%; the average particle size of the active metal nanoparticles is 12.0 nm, and they are uniformly dispersed.

[0150] Hydrocracking performance evaluation results: initial hydrocracking conversion rate was 52.3 wt%, and middle distillate oil yield was 38.5 wt%; after 100 h of reaction, the conversion rate dropped to 48.6 wt%, and the catalyst carbon deposition was 4.1 wt%; when the reaction continued until the conversion rate decreased by 10%, the cumulative lifespan was 680 h.

[0151] This comparative example only possesses large-sized mesoporous channels, lacking the 2-5nm microporous structure provided by molecular sieves. This results in a significant decrease in the catalyst's specific surface area and a markedly insufficient number of acid centers, leading to a precipitous drop in hydrocracking activity and an inability to achieve efficient cracking and conversion of heavy oil. Although the large mesoporous structure delays pore blockage to some extent, insufficient activity leads to an equivalent increase in reaction space velocity and a prolonged residence time of reactants within the channels, which in turn increases the probability of secondary coking. Ultimately, the overall catalyst performance is far lower than that of Example 1, fully demonstrating the synergistic effect of the bimodal pore structure of this invention: micropores provide sufficient specific surface area and acid centers to ensure cracking activity; mesopores provide efficient diffusion channels, reducing internal diffusion resistance and the probability of coking. This verifies the role of the bimodal pore structure in achieving both high activity and anti-coking performance of the catalyst.

[0152] Comparative Example 3

[0153] This comparative example is an active metal control scheme. The core difference is that the calcination process after impregnation of the active metal is adjusted so that the particle size of tungsten oxide and nickel oxide nanoparticles exceeds the 5-15 nm range specified in this invention. The rest of the catalyst composition and preparation process parameters are completely consistent with Example 1. This is used to verify the key influence of nanoscale uniformly distributed active metal on catalytic activity and anti-coking performance.

[0154] Catalyst composition and differences:

[0155] The total content of catalyst components, the source and parameters of the support, and the support preparation process are all completely consistent with those in Example 1;

[0156] The key difference is that the calcination temperature after impregnation with active metal is increased to 650°C, which causes the metal particles to grow through high-temperature sintering, resulting in a particle size that exceeds the limits defined in this invention.

[0157] The preparation method is based on the preparation of 100g of finished catalyst. The preparation of the support, the preparation of the impregnation solution, and the impregnation process are completely consistent with those in Example 1. Only the calcination and activation steps are adjusted: the material after impregnation and drying is placed in a muffle furnace and heated to 650°C at a heating rate of 3°C / min. It is then calcined at a constant temperature for 4 hours and naturally cooled to room temperature to obtain the comparative catalyst.

[0158] Performance testing

[0159] Physicochemical structural characterization results: The catalyst has a measured specific surface area of ​​160 m² / g, a pore volume of 0.38 mL / g, and a pore size of 8.0 nm; it exhibits a bimodal pore size distribution, with pores of 8-12 nm accounting for 60% of the total pore volume; the total acid content is 0.41 mmol / g, with weak acid centers accounting for 72%, medium-strong acid centers accounting for 23%, and strong acid centers accounting for 5%; the average particle size of the active metal nanoparticles is 26.5 nm, with a particle size range of 20-35 nm, and severe agglomeration occurs, with a large number of pore inlets blocked by metal particles.

[0160] Hydrocracking performance evaluation results: The initial hydrocracking conversion rate was 65.8 wt%, and the middle distillate oil yield was 39.6 wt%; after 100 h of reaction, the conversion rate dropped to 57.2 wt%, and the catalyst carbon deposition was 9.5 wt%; when the reaction continued until the conversion rate decreased by 10%, the cumulative lifespan was only 350 h.

[0161] The active metal particle size in this comparative example exceeds the range defined in this invention, resulting in severe agglomeration of metal particles and a significant reduction in the number of exposed active sites. This leads to a significant decrease in the catalyst's hydrogenation activity. The imbalance between hydrogenation and cracking functions prevents the timely saturation of olefins and other coke precursors generated by cracking, resulting in intensified secondary condensation reactions, a substantial increase in carbon deposition, and rapid catalyst deactivation. Ultimately, the catalyst's hydrocracking activity, anti-coking performance, and service life are all far lower than in Example 1. This fully demonstrates the key role of controlling the active metal particle size within the 5-15 nm nanometer range and achieving uniform dispersion in this invention, verifying the impact of this feature on the catalyst's dual-function matching, high activity, and anti-coking performance.

[0162] To visually compare the physicochemical structures and overall hydrocracking performance of the catalysts in different embodiments and comparative examples of this invention, the test data of all embodiments and comparative examples are summarized in the following comprehensive catalyst performance comparison table:

[0163]

[0164] Based on the comprehensive comparison table of catalyst performance and the detailed test results of each example and comparative example, the catalyst prepared by this invention exhibits a stable bimodal pore structure, a high proportion of weak acid centers, and nanoscale uniformly dispersed active metals in Examples 1 to 4. This corresponds to a high initial conversion rate of 72.3%-83.6%, a low carbon deposition of 2.5%-3.6% over 100 hours, and a long service life of over 1150 hours. In contrast, the three comparative examples show that: failure to introduce silicon in situ leads to a sharp increase in the proportion of strong acid centers and destruction of the pore structure, causing the catalyst to rapidly coke and deactivate; the absence of a bimodal pore structure results in a precipitous drop in cracking activity due to insufficient specific surface area and acid centers; and the active metal particle size exceeding the specified range causes metal agglomeration and a reduction in active sites, leading to an imbalance between hydrogenation and cracking functions and significantly reducing catalyst performance and lifespan.

[0165] In summary, this invention achieves a high degree of unity between hydrocracking activity and anti-coking performance from three dimensions: the in-situ introduction of silicon element by pseudoboehmite, the synergistic construction of bimodal pore structure by pseudoboehmite and molecular sieve, and the control of active metal into 5-15 nm nanoparticles and uniform dispersion. This is achieved through the core design of introducing silicon element in situ by pseudoboehmite, constructing a bimodal pore structure mass transfer and active center function. It solves the problems of easy coking, short lifespan and difficulty in balancing activity and anti-coking performance of catalysts in the prior art. The prepared catalyst has excellent comprehensive performance.

[0166] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A highly active, anti-coking bifunctional hydrocracking catalyst, characterized in that, Based on 100% of the total weight of the highly active anti-coking bifunctional hydrocracking catalyst, the catalyst includes an active component and a support, wherein the active component includes tungsten oxide and nickel oxide, and the support includes alumina and silicon oxide; The tungsten oxide content is 20-30%; The nickel oxide content is 5-10%; The alumina content is 50-60%; The content of silicon dioxide is 10-20%; The catalyst has a specific surface area of ​​150-200 m² / g, a pore volume of 0.3-0.5 mL / g, and a pore size of 6-12 nm. The alumina is derived from boehmite, which has a specific surface area of ​​300-400 m² / g, a pore volume of 0.7-1.1 mL / g, and a pore size of 10-12 nm. The pseudoboehmite contains silicon, an anti-coking factor, at a content of 2.5-3.0%, and the silicon forms part of the silicon oxide in the catalyst; The catalyst has a bimodal pore size distribution, with the first peak located at 2-5 nm and the second peak located at 8-12 nm, and the pore volume with a pore size of 8-12 nm accounts for more than 60% of the total pore volume. The tungsten oxide and nickel oxide are uniformly distributed in the form of nanoparticles on the surface and within the pores of the carrier, and the particle size of the nanoparticles is 5-15 nm.

2. The highly active anti-coking bifunctional hydrocracking catalyst according to claim 1, characterized in that, The silica is also derived from molecular sieves, which have a specific surface area of ​​600-700 m² / g, a pore volume of 0.1-0.2 mL / g, and a pore size of 2-4 nm.

3. The highly active anti-coking bifunctional hydrocracking catalyst according to claim 1, characterized in that, The total acidity of the catalyst is 0.3 mmol / g-0.5 mmol / g, wherein the proportion of weak acid centers in the total acidity is ≥70%, the proportion of medium-strong acid centers in the total acidity is 20%-25%, and the proportion of strong acid centers in the total acidity is ≤5%.

4. The highly active anti-coking bifunctional hydrocracking catalyst according to claim 1, characterized in that, The mass ratio of alumina to silicon oxide is (2.5-6):

1.

5. The highly active anti-coking bifunctional hydrocracking catalyst according to claim 1, characterized in that, The mass ratio of the pseudoboehmite to the molecular sieve is (2-6):

1.

6. A method for preparing a highly active, anti-coking bifunctional hydrocracking catalyst, applicable to the highly active, anti-coking bifunctional hydrocracking catalyst according to any one of claims 1-5, characterized in that, The specific steps of this preparation method are as follows: S100, Carrier precursor mixing: Boehmite, molecular sieve, guar gum powder, and hydroxymethyl cellulose are placed in a kneader and stirred for 10 minutes to obtain a solid mixture. An inorganic acid aqueous solution with a pH of 2-4 is prepared and added to the kneader. The mixture is kneaded with the solid mixture until a uniform agglomerate is formed. The amount of deionized water added is adjusted to control the dryness and moisture content of the agglomerate. S200, Carrier Forming and Calcination: The uniform agglomerated material obtained in S100 is transferred to an extruder and extruded using a 2.0mm clover-shaped die to obtain a clover-shaped catalyst carrier precursor. The catalyst carrier precursor is left to stand at room temperature for 6 hours, then placed in a drying equipment and dried at 50℃-100℃ for 4 hours. It is then placed in a muffle furnace and heated to 500℃-550℃ at a heating rate of 3℃ / min, and calcined at a constant temperature for 4 hours to obtain the catalyst carrier. S300, Impregnation solution preparation: Add soluble tungsten salt and soluble nickel salt to deionized water, stir thoroughly to dissolve, and prepare a stable impregnation solution; S400, Impregnation and Calcination Activation: The catalyst support obtained in S200 is mixed with the impregnation solution obtained in S300 and impregnated for 2 hours to obtain the impregnated material. The impregnated material is placed in a drying device and dried at 50℃-100℃ for 4 hours. Then it is placed in a muffle furnace and heated to 300℃-500℃ at a heating rate of 3℃ / min. It is then calcined at a constant temperature for 4 hours to obtain a highly active anti-coking bifunctional hydrocracking catalyst.

7. The method for preparing a highly active anti-coking bifunctional hydrocracking catalyst according to claim 6, characterized in that, In the S100, the inorganic acid is at least one of nitric acid and citric acid, and the total added mass of guar gum powder and hydroxymethyl cellulose is 2%-5% of the total mass of boehmite and molecular sieve. In the S300, the soluble tungsten salt is ammonium metatungstate, and the soluble nickel salt is nickel nitrate; In the S400, the impregnation is carried out by an equal volume impregnation method, and the volume ratio of the impregnation liquid to the pore volume of the catalyst support is (1.05-1.1):1.

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