A hydrofining catalyst for a boiling bed and a method for preparing the same

Abstract

The present application belongs to the technical field of petroleum chemical catalysts, and particularly relates to a hydrofining catalyst for a ebullated bed and a preparation method thereof.The catalyst comprises a carrier and an active component supported on the carrier, the carrier is spherical porous gamma-Al2O3 modified by fluorinated graphene, an oleophobic interface is formed on the surface of the carrier through C-F bonds, the fluorine content is 0.5-2.0 wt%, and the mass fraction of graphene accounts for 2-6% of the total mass of the carrier; the active component is Ni-Co-W2C heterostructure nanoparticles prepared by phosphotungstic acid confined pyrolysis, wherein the phosphorus element is anchored on the metal-carbide interface in the form of PO4 3‑ , and the molar ratio of Ni to Co is 0.8-2.0:1.The catalyst prepared by the present application has excellent desulfurization and denitrification performance, mechanical strength and long-term stability, and is suitable for ebullated bed reactor operation.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical catalyst technology, specifically relating to a hydrorefining catalyst for fluidized bed and its preparation method. Background Technology

[0002] Hydrorefining is an important process in the petroleum refining industry, mainly used to remove impurities such as sulfur, nitrogen, and oxygen from petroleum fractions, thereby improving oil quality. Ebullated bed hydrorefining technology, as an advanced hydrorefining process, has advantages such as high mass and heat transfer efficiency, mild reaction conditions, and high catalyst utilization, making it particularly suitable for the hydrorefining of heavy feedstocks.

[0003] Traditional fluidized bed hydrogenation catalysts mostly employ Mo-Co or Mo-Ni based catalysts with γ-Al₂O₃ as the support. However, existing catalysts suffer from the following problems under fluidized bed operating conditions: First, traditional supports are prone to surface carbonization and pore blockage under high temperature, high pressure, and sulfur-containing environments, leading to rapid catalyst deactivation; second, the active metal exhibits poor dispersion on the support surface, easily resulting in agglomeration and sintering, affecting the persistence of catalytic activity; third, severe mechanical collisions and wear between catalyst particles in the fluidized bed place higher demands on the catalyst's mechanical strength.

[0004] In recent years, carbide catalysts have attracted widespread attention due to their unique electronic structure and excellent hydrogenation performance. Tungsten carbide (W₂C) possesses platinum-like electronic properties and exhibits excellent activity and selectivity in hydrogenation reactions. However, W₂C is prone to agglomeration and phase transition during preparation, making it difficult to obtain a highly dispersed active phase. Furthermore, the sulfur resistance of single carbides still needs improvement.

[0005] Graphene, as a two-dimensional carbon material, possesses excellent electrical conductivity, mechanical strength, and chemical stability, making it a promising catalyst support. Fluorinated graphene, by introducing CF bonds, can modulate its surface electronic properties and hydrophobicity, providing a new approach to solving the problem of catalyst deactivation in sulfur-containing environments.

[0006] Therefore, developing a novel hydrorefining catalyst suitable for fluidized bed operation, with high activity, high stability, and excellent mechanical strength is of great significance for improving the hydrorefining efficiency of heavy oil products. Summary of the Invention

[0007] The purpose of this invention is to provide a hydrorefining catalyst for fluidized bed and its preparation method. By using fluorinated graphene-modified support and phosphotungstic acid confined pyrolysis technology, a catalyst with a unique heterostructure is prepared. While ensuring high hydrogenation activity, the catalyst's anti-carbon deposition performance and mechanical strength are significantly improved, meeting the stringent requirements of fluidized bed operation.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] The hydrorefining catalyst for fluidized beds described in this invention comprises a support and an active component supported on the support. The support is a spherical porous γ-Al₂O₃ modified with fluorinated graphene. An oleophobic interface is formed on the support surface through CF bonds. The fluorine content is 0.5-2.0 wt%, more preferably 1.0-1.5 wt%, to balance oleophobicity and support mechanical strength. The graphene mass fraction accounts for 2-6% of the total support mass. The active component is a phosphotungstic acid (H₃PW₂O₃) modified with fluorinated graphene. 12 O 40 Ni-Co-W2C heterostructured nanoparticles were prepared by confined pyrolysis, in which phosphorus was mainly present as PO4. 3- The form is anchored at the metal-carbide interface, with a Ni to Co molar ratio of 0.8-2.0:1 and a total loading of 12-25 wt% of active components.

[0010] in:

[0011] The fluorinated graphene-modified support employs a unique surface engineering strategy. Fluorinated graphene, through the introduction of CF bonds, significantly alters the electronic properties and hydrophobicity of the support surface. The fluorine content is controlled within the range of 0.5-2.0 wt%; below 0.5 wt%, the modification effect is not significant, while above 2.0 wt% may affect the mechanical strength of the support. A graphene mass fraction of 2-6% is optimal, ensuring both the conductivity and mechanical strength of the support while avoiding the adverse effects of excessive graphene on the specific surface area. The oleophobic interface design effectively prevents the deep adsorption of heavy oil molecules on the support surface, slowing down the carbon deposition and deactivation process.

[0012] Specifically, the carrier has a hierarchical pore structure, with mesopores having a diameter of 8-15 nm and macropores having a diameter of 50-150 nm, resulting in a mesopore / macropore volume ratio of 0.6-1.2. This hierarchical pore structure facilitates mass transfer and diffusion of reactants and products. Mesopores provide a high specific surface area for dispersing active components, while macropores facilitate the transport of macromolecules. The optimized pore size ratio ensures a balance between mass transfer efficiency and the dispersion of active components.

[0013] Specifically, the Ni-Co-W2C heterostructure nanoparticles are prepared via phosphotungstic acid confined pyrolysis. Phosphorus is represented by PO4. 3- The structure is anchored at the metal-carbide interface, playing a dual role in structure guidance and electronic regulation. The optimal molar ratio of Ni to Co is 0.8-2.0:1. Ni provides excellent hydrogenation activity, while Co enhances sulfur resistance; the synergistic effect of the two significantly improves catalytic performance. The heterostructured nanoparticles have an average particle size of 3-8 nm, with W2C encapsulating the Ni-Co alloy in a core-shell structure. This unique structure ensures high metal dispersion while utilizing the electronic effects of W2C.

[0014] Specifically, the catalyst particles are spherical with an average particle size of 0.5-1.2 mm, a bulk density of 1.0-1.4 g / cm³, and an attrition index ≤1.5 wt% / h. They are specifically designed for the operating characteristics of fluidized bed reactors. The spherical particle shape facilitates fluidization uniformity, the particle size range ensures good fluidization performance, and the bulk density and attrition index meet the requirements for industrial applications.

[0015] Specifically, the method for preparing the catalyst includes:

[0016] (1) Preparation of fluorinated graphene: Graphene oxide and ammonium fluoride are reacted at 250-300℃ for 2-4 hours under argon protection at a mass ratio of 1:2-4. The HF produced by the decomposition of ammonium fluoride is fluorinated in situ on the surface of graphene.

[0017] (2) Carrier preparation: Fluorinated graphene was mixed with γ-Al2O3 precursor, spray dried and calcined at 500℃ for 3h;

[0018] (3) Phosphotungstic acid impregnation: 0.1-0.3 mol / L phosphotungstic acid H3PW 12 O 40 The solution is immersed on the carrier for 6-12 hours;

[0019] (4) Metal precursor loading: A solution of Ni(NO3)2·6H2O and Co(NO3)2·6H2O with a total concentration of 0.8-1.5 mol / L was loaded onto the support by a stepwise impregnation method;

[0020] (5) Confined pyrolysis: The pyrolysis treatment is carried out in a stepwise manner under a hydrogen atmosphere. The temperature is raised to 400℃ and held for 30 min to decompose phosphotungstic acid to form a WO3 coating. The temperature is then raised to 650℃ and held for 2 h to reduce WO3 to W2C and migrate to the Ni-Co phase interface. The heating rate is 3-5℃ / min.

[0021] Specifically, the hydrogen flow rate was controlled at 100-300 mL / min during the preparation process, and the catalyst was dried at 120℃ for 8 hours between each step to ensure the reproducibility and stability of the catalyst preparation.

[0022] Specifically, the stepwise impregnation method refers to: first impregnating the carrier in a phosphotungstic acid solution (0.1-0.3 mol / L, 6-12 h), drying it, and then impregnating it in a Ni / Co nitrate mixed solution (total concentration 0.8-1.5 mol / L, impregnated twice, 6 h each time), and drying it at 120°C for 8 h after each impregnation.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. The oleophobic interface formed by the fluorinated graphene-modified support significantly improves the catalyst's resistance to carbon deposition. The introduction of CF bonds alters the electron density distribution on the support surface, reducing the adsorption capacity of heavy oil molecules, effectively delaying the carbon deposition and deactivation process, and improving the catalyst's lifespan.

[0025] 2. The confined pyrolysis technology of phosphotungstic acid enabled the precise construction of Ni-Co-W2C heterostructures. The anchoring effect of phosphate groups ensured high dispersion of the active components, while the confined environment suppressed W2C aggregation and phase transition. The resulting heterostructure possessed unique electronic properties and geometric structure, significantly improving hydrogenation activity and selectivity.

[0026] 3. The hierarchical pore structure optimizes the mass transfer performance of the catalyst. The reasonable ratio of mesopores and macropores ensures both a high specific surface area and effective diffusion of macromolecules, avoiding activity degradation caused by pore blockage, making it particularly suitable for the hydrogenation treatment of heavy feedstocks.

[0027] 4. The synergistic effect of the Ni-Co-W2C ternary system fully leverages the advantages of each component. Ni provides excellent C-C bond hydrogenolysis activity, Co enhances tolerance to sulfur-containing compounds, and W2C acts as an electronic promoter to regulate the electronic properties of the metal. The synergistic effect of the three significantly improves the overall performance of the catalyst.

[0028] 5. The spherical particle design and optimized mechanical properties ensure stable operation of the catalyst in the fluidized bed. The wear index is ≤1.5wt% / h, far superior to traditional catalysts, effectively reducing catalyst replenishment costs and environmental pollution.

[0029] 6. The prepared catalyst has excellent hydrorefining performance: desulfurization rate ≥99.5%, denitrification rate ≥95%, and maintains high activity after continuous operation for more than 2000 hours under fluidized bed conditions, meeting the stringent requirements of industrial applications. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to these embodiments. Those skilled in the art should recognize that the present invention covers all possible alternatives, improvements and equivalents included within the scope of the claims.

[0031] Graphene oxide: sheet thickness 0.8-1.2nm, C / O molar ratio 2.5-3.0, purchased from Shanghai Carbon Source Huigu New Material Technology Co., Ltd.

[0032] Ammonium fluoride: analytical grade, purity ≥98%, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0033] γ-Al2O3 precursor: specific surface area 250-300m² / g, purchased from Shandong Aluminum Co., Ltd.

[0034] Phosphotungstic acid: H3PW 12 O 40 nH2O, purity ≥99%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0035] Nickel nitrate and cobalt nitrate: analytical grade, purchased from Tianjin Kemeo Chemical Reagent Co., Ltd.

[0036] The remaining raw materials are conventional products, all obtained through commercial purchases.

[0037] Example 1:

[0038] A method for preparing a hydrorefining catalyst for a fluidized bed includes the following steps:

[0039] (1) Preparation of fluorinated graphene: 10g of graphene oxide was mixed with 0.48g of ammonium fluoride, and the mixture was heated to 275℃ for 3h under argon protection. After cooling, the mixture was washed with deionized water until neutral and dried to obtain fluorinated graphene with a fluorine content of 1.2wt%.

[0040] (2) Preparation of carrier: 3g of fluorinated graphene was mixed with 97g of γ-Al2O3 precursor, and an appropriate amount of deionized water was added to make a slurry. The slurry was spray-dried to make spherical particles, and calcined at 500℃ for 3h to obtain fluorinated graphene modified carrier with an average particle size of 0.8mm.

[0041] (3) Phosphotungstic acid impregnation: Dissolve 3.2g of phosphotungstic acid in 100mL of deionized water to prepare a 0.2mol / L solution, impregnate 50g of the carrier for 8h, and dry at 120℃ for 8h;

[0042] (4) Metal precursor loading: Prepare 100 mL of aqueous solution containing 12.6 g of Ni(NO3)2·6H2O and 10.2 g of Co(NO3)2·6H2O (Ni:Co molar ratio 1.2:1), impregnate the support in two steps, each impregnation for 6 h, and dry at 120 °C for 8 h;

[0043] (5) Confined pyrolysis: The impregnated sample was heated in a tube furnace under a hydrogen atmosphere (flow rate 200 mL / min) according to the program: heated to 400℃ (heating rate 4℃ / min) and held for 30 min, then heated to 650℃ and held for 2 h, and naturally cooled to obtain the catalyst with a total active component loading of 18 wt%.

[0044] Example 2:

[0045] The preparation method of a hydrorefining catalyst for a fluidized bed differs from that in Example 1 only in step (1) for preparing fluorinated graphene: 10g of graphene oxide is mixed with 0.200g of ammonium fluoride, heated to 275℃ for 3h under argon protection, cooled, washed with deionized water until neutral, and dried to obtain fluorinated graphene with a fluorine content of 0.5wt%.

[0046] (2) Preparation of carrier: 2g of fluorinated graphene was mixed with 98g of γ-Al2O3 precursor, and an appropriate amount of deionized water was added to make a slurry. The slurry was spray-dried to make spherical particles, and calcined at 500℃ for 3h to obtain fluorinated graphene modified carrier with an average particle size of 0.8mm.

[0047] (4) Metal precursor loading: Prepare 100 mL of aqueous solution containing 8.44 g of Ni(NO3)2·6H2O and 10.2 g of Co(NO3)2·6H2O (Ni:Co molar ratio 0.8:1), impregnate the carrier in two steps, each impregnation for 6 h, and dry at 120 °C for 8 h.

[0048] Example 3:

[0049] The preparation method of a hydrorefining catalyst for a fluidized bed differs from that in Example 1 only in step (1) for preparing fluorinated graphene: 10g of graphene oxide is mixed with 0.40g of ammonium fluoride, heated to 275℃ for 3h under argon protection, cooled, washed with deionized water until neutral, and dried to obtain fluorinated graphene with a fluorine content of 1.0wt%.

[0050] (2) Preparation of carrier: 6g of fluorinated graphene was mixed with 94g of γ-Al2O3 precursor, and an appropriate amount of deionized water was added to make a slurry. The slurry was spray-dried to make spherical particles, and calcined at 500℃ for 3h to obtain fluorinated graphene modified carrier with an average particle size of 0.8mm.

[0051] (4) Metal precursor loading: Prepare 100 mL of aqueous solution containing 21.0 g of Ni(NO3)2·6H2O and 10.2 g of Co(NO3)2·6H2O (Ni:Co molar ratio 2.0:1), impregnate the support in two steps, each impregnation for 6 h, and dry at 120 °C for 8 h;

[0052] (5) Confined pyrolysis: The impregnated sample was heated in a tube furnace under a hydrogen atmosphere (flow rate 200 mL / min) according to the program: heated to 400℃ (heating rate 4℃ / min) and held for 30 min, then heated to 650℃ and held for 2 h, and then naturally cooled to obtain the catalyst.

[0053] Example 4:

[0054] The preparation method of a hydrorefining catalyst for a fluidized bed differs from that in Example 1 only in step (1) for preparing fluorinated graphene: 10g of graphene oxide is mixed with 1.5g of ammonium fluoride, heated to 275℃ for 3h under argon protection, cooled, washed with deionized water until neutral, and dried to obtain fluorinated graphene with a fluorine content of 1.5wt%.

[0055] Preparation of the carrier: 3g of fluorinated graphene was mixed with 97g of γ-Al2O3 precursor, and an appropriate amount of deionized water was added to make a slurry. The slurry was spray-dried to form spherical particles, and calcined at 500℃ for 3h to obtain a fluorinated graphene modified carrier with an average particle size of 0.5mm.

[0056] (3) Phosphotungstic acid impregnation: Dissolve 1.6g of phosphotungstic acid in 100mL of deionized water to prepare a 0.1mol / L solution, impregnate 50g of the carrier for 12h, and dry at 120℃ for 8h.

[0057] Example 5:

[0058] The preparation method of a hydrorefining catalyst for a fluidized bed differs from that in Example 1 only in step (1) for preparing fluorinated graphene: 10g of graphene oxide is mixed with 1.5g of ammonium fluoride, heated to 275℃ for 3h under argon protection, cooled, washed with deionized water until neutral, and dried to obtain fluorinated graphene with a fluorine content of 1.5wt%.

[0059] Preparation of the carrier: 3g of fluorinated graphene was mixed with 97g of γ-Al2O3 precursor, and an appropriate amount of deionized water was added to make a slurry. The slurry was spray-dried to form spherical particles, and calcined at 500℃ for 3h to obtain a fluorinated graphene modified carrier with an average particle size of 1.2mm.

[0060] (3) Phosphotungstic acid impregnation: Dissolve 4.8g of phosphotungstic acid in 100mL of deionized water to prepare a 0.3mol / L solution, impregnate 50g of the carrier for 6h, and dry at 120℃ for 8h;

[0061] (5) Confined pyrolysis: The impregnated sample was heated in a tube furnace under a hydrogen atmosphere (flow rate 200 mL / min) according to the program: heated to 400℃ (heating rate 4℃ / min) and held for 30 min, then heated to 650℃ and held for 2 h, and then naturally cooled to obtain the catalyst.

[0062] Comparative Example 1

[0063] A method for preparing a hydrorefining catalyst for a fluidized bed includes the following steps:

[0064] (1) Preparation of the carrier: 100g of γ-Al2O3 precursor was added to an appropriate amount of deionized water to make a slurry, which was then spray-dried to form spherical particles. The fluorinated graphene modified carrier was calcined at 500℃ for 3h with an average particle size of 0.8mm.

[0065] (2) Phosphotungstic acid impregnation: Dissolve 3.2g of phosphotungstic acid in 100mL of deionized water to prepare a 0.2mol / L solution, impregnate 50g of the carrier for 8h, and dry at 120℃ for 8h;

[0066] (3) Metal precursor loading: Prepare 100 mL of aqueous solution containing 12.6 g of Ni(NO3)2·6H2O and 10.2 g of Co(NO3)2·6H2O (Ni:Co molar ratio 1.2:1), impregnate the support in two steps, each impregnation for 6 h, and dry at 120 °C for 8 h;

[0067] (4) Confined pyrolysis: The impregnated sample was placed in a tube furnace under a hydrogen atmosphere (flow rate 200 mL / min) and heated according to the program: heated to 400℃ (heating rate 4℃ / min) and held for 30 min, then heated to 650℃ and held for 2 h, and naturally cooled to obtain the catalyst with a total active component loading of 18 wt%.

[0068] Comparative Example 2

[0069] A method for preparing a hydrorefining catalyst for a fluidized bed includes the following steps:

[0070] (1) Preparation of fluorinated graphene: 10g of graphene oxide and 30g of ammonium fluoride were mixed and reacted at 275℃ for 3h under argon protection. After cooling, the mixture was washed with deionized water until neutral and dried to obtain fluorinated graphene with a fluorine content of 1.2wt%.

[0071] (2) Preparation of carrier: 3g of fluorinated graphene was mixed with 97g of γ-Al2O3 precursor, and an appropriate amount of deionized water was added to make a slurry. The slurry was spray-dried to make spherical particles, and calcined at 500℃ for 3h to obtain fluorinated graphene modified carrier with an average particle size of 0.8mm.

[0072] (3) Metal precursor loading: Prepare 100 mL of aqueous solution containing 12.6 g of Ni(NO3)2·6H2O and 10.2 g of Co(NO3)2·6H2O (Ni:Co molar ratio 1.2:1), impregnate the support in two steps, each impregnation for 6 h, and dry at 120 °C for 8 h;

[0073] (4) Confined pyrolysis: The impregnated sample was placed in a tube furnace under a hydrogen atmosphere (flow rate 200 mL / min) and heated according to the program: heated to 400℃ (heating rate 4℃ / min) and held for 30 min, then heated to 650℃ and held for 2 h, and naturally cooled to obtain the catalyst with a total active component loading of 18 wt%.

[0074] Comparative Example 3

[0075] The preparation method of a hydrorefining catalyst for fluidized bed differs from that in Example 1 only in step (4) metal precursor loading: prepare 100 mL of aqueous solution containing 12.6 g of Ni(NO3)2·6H2O, impregnate the support in two steps, impregnate for 6 h each step, and dry at 120 °C for 8 h.

[0076] Comparative Example 4

[0077] The preparation method of a hydrorefining catalyst for fluidized bed differs from that in Example 1 only in step (5) confined pyrolysis: the impregnated sample is heated in a tube furnace under a hydrogen atmosphere (flow rate 200 mL / min) according to a program: the temperature is raised to 650℃ (heating rate 4℃ / min) and held for 2 hours, and then naturally cooled to obtain the catalyst with a total loading of 18 wt% of active components.

[0078] Comparative Example 5

[0079] The preparation method of a hydrogenation refining catalyst for fluidized bed differs from that in Example 1 only in step (2) preparation of the support: 3g of fluorinated graphene is mixed with 97g of γ-Al2O3 precursor, and an appropriate amount of deionized water is added to make a slurry. The slurry is then spray-dried to form spherical particles, and calcined at 500℃ for 3h to obtain a fluorinated graphene modified support with an average particle size of 0.8mm.

[0080] The γ-Al2O3 precursor uses a single mesoporous structure.

[0081] Performance tests were performed on the catalysts prepared in the examples and comparative examples:

[0082] (1) Hydrogenation refining activity test: A fixed-bed reactor was used, with a reaction temperature of 360℃, a pressure of 4.0MPa, a hydrogen-to-oil ratio of 600:1, and a weight hourly space velocity of 1.5h. -1 The raw material was coking diesel containing 1.2 wt% sulfur, and the desulfurization rate and denitrification rate were measured.

[0083] (2) Mechanical strength test: The wear index is determined in accordance with the SH / T0701 standard.

[0084] (3) Specific surface area and pore structure: The specific surface area and pore size distribution of BET were determined at 77K using the N2 adsorption-desorption method.

[0085] (4) Anti-carbon deposition performance: The amount of carbon on the catalyst surface was measured after 200 h of reaction.

[0086] (5) Stability test: The desulfurization rate was monitored after 2000 hours of continuous reaction.

[0087] The test results are shown in Table 1:

[0088]

[0089] Table 1 Catalyst performance test results

[0090] According to the data in Table 1, the catalysts prepared in Examples 1-5 all had a desulfurization rate of ≥99%, a denitrification rate of ≥95%, a wear index of ≤1.5wt% / h, significantly reduced carbon deposits, and excellent long-term stability. All performance indicators met the design requirements, indicating that the technical solution of the present invention is effective.

[0091] Comparative Example 1, without fluorinated graphene modification, exhibited poor resistance to carbon deposition, and a significant decrease in activity and stability. Comparative Example 2, employing a traditional Mo-Co system, showed insufficient activity and selectivity. Comparative Example 3 lacked the synergistic effect of Co, resulting in decreased sulfur resistance. Comparative Example 4, without stepwise pyrolysis, resulted in incomplete formation of heterostructures. Comparative Example 5, with its single-pore structure, affected mass transfer efficiency. These comparative results validate the necessity and synergistic effect of the various technical features of this invention.

[0092] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A hydrofining catalyst for use in a boiling bed, characterized in that, The catalyst comprises a carrier and an active component supported on the carrier, wherein: The carrier is a fluorinated graphene modified spherical porous γ-Al2O3, the surface of the carrier forms an oleophobic interface through C-F bonds, the fluorine content is 0.5-2.0wt%, and the mass fraction of graphene accounts for 2-6% of the total mass of the carrier; The active component is Ni-Co-W2C heterostructure nanoparticles prepared by phosphotungstic acid confined pyrolysis, in which the phosphorus element is anchored to the metal-carbide interface in the form of PO4 3- with a molar ratio of Ni to Co of 0.8-2.0: 1 and a total loading of the active component of 12-25 wt%; The carrier has a hierarchical pore structure, the mesopore size is 8-15nm, the macropore size is 50-150nm, and the volume ratio of mesopores to macropores is 0.6-1.2:1; the average particle size of the Ni-Co-W2C heterostructure nanoparticles is 3-8nm, and W2C is coated on the Ni-Co alloy in a core-shell structure; The preparation steps are as follows: (1) Fluorinated graphene preparation: graphene oxide is reacted with ammonium fluoride at 250-300℃ for 2-4h to obtain fluorinated graphene; (2) Carrier preparation: fluorinated graphene is mixed with γ-Al2O3 precursor, and after spray drying and molding, it is calcined at 500℃ for 3h; (3) Phosphotungstic acid impregnation: Phosphotungstic acid H3PW 12 O 40 solution is impregnated onto the support; (4) Metal precursor loading: Ni(NO3)2·6H2O and Co(NO3)2·6H2O solutions are impregnated onto the carrier; (5) Confined pyrolysis: stepwise heating pyrolysis treatment under hydrogen atmosphere to obtain the catalyst; The stepwise heating program of confined pyrolysis in step (5) is as follows: heating to 400℃ and keeping for 30min to make phosphotungstic acid decompose to form a WO3 coating, continuing to heat to 650℃ and keeping for 2h to make WO3 reduce to W2C and migrate to the Ni-Co phase interface, and the heating rate is controlled at 3-5℃ / min.

2. A hydrofining catalyst for use in a boiling bed according to claim 1, characterized in that, The catalyst particles are spherical with an average particle size of 0.5-1.2mm, a bulk density of 1.0-1.4g / cm3, and an abrasion index ≤1.5wt% / h, and are suitable for operation of a boiling bed reactor.

3. The hydrofinishing catalyst for a boiling bed according to claim 1, characterized by, The mass ratio of graphene oxide to ammonium fluoride in step (1) is 1:2-4, and the reaction is carried out under argon protection.

4. The hydrofinishing catalyst for a boiling bed according to claim 1, characterized by, In step (3), the concentration of phosphotungstic acid impregnation solution is 0.1-0.3mol / L, and the impregnation time is 6-12h; in step (4), the total concentration of metal precursors is 0.8-1.5mol / L, and a stepwise impregnation method is used.

5. The hydrofinishing catalyst for use in a boiling bed according to claim 1, characterized in that, The hydrogen flow rate during preparation is 100-300mL / min, and each step is treated by drying at 120℃ for 8h.

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