Core-shell type hydrogenation catalyst and method for preparing the same

Abstract

This invention discloses a core-shell hydrogenation catalyst and its preparation method. The catalyst comprises a core layer and a shell layer, wherein the core layer is alumina loaded with an active metal component, and the shell layer is alumina loaded with molybdenum carbide. The active metal is at least one of Group VIII metals and at least one of Group VIB metals. The preparation method of the catalyst is as follows: first, boehmite powder is mixed with an organic acid solution and dried before introducing the active metal component. Then, after molding, a spherical core layer material is obtained. Then, under rolling spherical conditions, the obtained spherical core layer material, boehmite powder, molybdenum carbide powder, and an organic alcohol polymer solution are mixed evenly to obtain a catalyst precursor. Finally, the catalyst precursor is dried and calcined to obtain the core-shell hydrogenation catalyst. The hydrogenation catalyst provided by this invention is particularly suitable for the hydrogenation conversion of heavy oil, coal tar, and other oils containing macromolecular aromatics and polycyclic aromatic hydrocarbons.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical catalysis technology, and relates to a catalytic material and its preparation method, particularly to a hydrogenation catalytic material and its preparation method. Background Technology

[0002] As international crude oil becomes increasingly heavier and market demand for distillate fuels and chemical feedstocks continues to grow, the hydroconversion of low-quality heavy oil to produce high-quality products is becoming increasingly attractive. Residue oils and other petroleum products contain large amounts of gums and asphaltenes, while ethylene tar, coal tar, and other petroleum products contain a significant amount of polycyclic aromatic hydrocarbons (PAHs). These components have large molecules and high degrees of unsaturation. During hydroconversion, on the one hand, hydrogenation is difficult due to steric hindrance, and on the other hand, carbon deposits easily form, causing pore blockage of the catalyst and affecting the hydrogenation efficiency of the catalyst.

[0003] CN200910083078.3 discloses a hydrocracking catalyst and its preparation method. The catalyst consists of a main catalyst and a co-catalyst. The main catalyst is an aluminosilicate supported on a transition metal, and the co-catalyst is selected from one or more of nitrogen-containing heterocyclic compounds, aromatic nitrogen-containing compounds, and acyl nitrogen-containing compounds to obtain a mixture. The main catalyst and co-catalyst are mixed to obtain a catalyst suitable for the hydrocracking of heavy distillate oils. This preparation method involves a simple mixing of the co-catalyst and the main catalyst, resulting in weak synergistic effects.

[0004] Core-shell catalysts can produce a progressive catalytic effect on oil molecules, with the molecules further entering the core layer for transformation after treatment in the shell. The preparation process of core-shell catalysts is one of the key factors affecting their catalytic efficiency.

[0005] CN202110228071.7 discloses a core-shell catalyst. The preparation method of this core-shell catalyst utilizes different electronic promoters to regulate the catalytic performance of the iron-based catalyst. It achieves control over the acidity and pore structure of the molecular sieve surface through direct ion exchange and alkaline solution pore-expansion treatment, and is applied in the field of carbon dioxide hydrogenation. The preparation method of this core-shell structure involves physically coating an active metal onto a molecular sieve support. However, the dispersibility of the active metal and its synergistic effect with the molecular sieve support need further improvement.

[0006] CN201710709622.5 discloses a core-shell structured hydrogenation catalyst containing a non-acidic or weakly acidic porous support and at least two metal elements or compounds selected from VIII, VIB, and VIIB supported thereon. The metal elements or compounds are distributed in a core-shell layer on the support surface, achieved through two identical loading processes, resulting in a shell layer covering the core layer. This core-shell distribution method allows for hydrogenation of asphaltenes within the pores of a conventional catalyst. However, due to steric hindrance, the hydrogenation conversion of macromolecules by the active metal within the pores is somewhat limited, and the metal utilization rate is slightly insufficient. Summary of the Invention

[0007] The core objective of this invention is to provide a core-shell hydrogenation catalyst and its preparation method. Microspherical particles form the core layer, which is then wrapped with a shell containing molybdenum carbide active components through a rolling molding process. This achieves a catalyst particle pore structure with a small inner core and a large outer core. The core layer exhibits hydrogenation activity for cyclic and chain-like small molecules, while the shell layer exhibits hydrogenation activity for polycyclic aromatic hydrocarbons rich in π-bond electrons. This enables stepwise hydrogenation of the spherical catalyst particle shell and core layers, and the cascade utilization of the pores. The hydrogenation catalyst provided by this invention is particularly suitable for the hydrogenation conversion of heavy oil, coal tar, and other oils containing large-molecule aromatic hydrocarbons and polycyclic aromatic hydrocarbons.

[0008] The first aspect of the present invention provides a core-shell hydrogenation catalyst, the catalyst comprising a core layer and a shell layer, wherein the core layer is alumina supported on an active metal component, the shell layer is alumina supported on molybdenum carbide, and the active metal is at least one of a group VIII metal and at least one of a group VIB metal.

[0009] Specifically, in the aforementioned core-shell hydrogenation catalysts, the active metal of Group VIII is one or more of Ni and Co, and the active metal of Group VIB is one or more of Mo and W.

[0010] In the aforementioned core-shell hydrogenation catalyst, specifically, based on the total weight of the core layer and calculated as metal oxides, the content of Group VIII metals is 1.0wt%-8.0wt%, preferably 2.0wt%-4.0wt%; and the content of Group VIB metals is 5.0wt%-20.0wt%, preferably 8.0wt%-15.0wt%.

[0011] In the aforementioned core-shell hydrogenation catalyst, specifically, based on the total weight of the shell layer, the molybdenum carbide content is 2.0wt%-10.0wt%, preferably 4.0wt%-8.0wt%.

[0012] In the aforementioned core-shell hydrogenation catalysts, specifically, the active metal of Group VIB is Mo, and the molar ratio of hexavalent molybdenum to divalent molybdenum is between 0.2 and 10.

[0013] Specifically, among the core-shell hydrogenation catalysts mentioned above, the catalyst attenuation rate is <2.0%.

[0014] Specifically, in the aforementioned core-shell hydrogenation catalyst, the catalyst has a pore volume of 0.40-0.80 mL / g, preferably 0.45-0.75 mL / g, and a specific surface area of ​​150-280 m². 2 / g, preferably 160-260m 2 / g.

[0015] In the aforementioned core-shell hydrogenation catalysts, specifically, the volume ratio of the core layer to the shell layer is 1:3.6 to 1:0.38.

[0016] In the aforementioned core-shell hydrogenation catalyst, specifically, in the core layer, the pore volume of pores with a diameter of 6-15 nm accounts for 60%-80% of the core layer pore volume, and the pore volume of pores with a diameter >100 nm accounts for more than 5% of the core layer pore volume.

[0017] In the aforementioned core-shell hydrogenation catalysts, specifically, the pore volume of pores with a diameter of 6-15 nm accounts for 40%-60% of the total pore volume, and the pore volume of pores with a diameter >100 nm accounts for more than 15% of the total pore volume.

[0018] A second aspect of this invention provides a method for preparing a core-shell hydrogenation catalyst, the method comprising the following steps:

[0019] (1) Mix the pseudoboehmite powder with an organic acid solution, mix well and dry it before introducing the active metal component, and then obtain a spherical core layer material after molding treatment;

[0020] (2) Under the condition of rolling spherical formation, the spherical core material obtained in step (1), pseudo-boehmite powder, molybdenum carbide powder, and organic alcohol polymer solution are mixed evenly to obtain the catalyst precursor;

[0021] (3) The catalyst precursor obtained in step (2) is dried and calcined to obtain a core-shell hydrogenation catalyst.

[0022] In the above-mentioned preparation method of core-shell hydrogenation catalyst, specifically, the boehmite powder in step (1) can be a commercially available product, or it can be prepared according to the methods disclosed in existing literature or patents, such as precipitation, aluminum alkoxide hydrolysis, inorganic salt sol-gel method, hydrothermal method, and vapor deposition method. The boehmite powder in steps (1) and (2) can be the same type of boehmite powder, or different types of boehmite powder can be used.

[0023] In the above-mentioned preparation method of core-shell hydrogenation catalyst, specifically, the concentration of organic acid solution in step (1) is 1.0wt%-10.0wt%, preferably 2.0wt%-6.0wt%, and the organic acid can be selected from at least one of monobasic acid, dibasic acid, and polybasic acid, preferably an organic acid with 3-8 carbon atoms. Specifically, the organic acid can be one or more of citric acid, tartaric acid, acrylic acid, etc.

[0024] In the above-mentioned preparation method of core-shell hydrogenation catalyst, specifically, the amount of organic acid solution added in step (1) is 1.0wt%-8.0wt% of the dry weight of boehmite powder in step (1), preferably 2.0wt%-6.0wt%.

[0025] In the above-mentioned preparation method of core-shell hydrogenation catalyst, specifically, the mixing mentioned in step (1) can be carried out by any of the following methods: kneading, impregnation, etc. The kneading process can be carried out in a kneader, specifically a horizontal kneader or a plow kneader; the impregnation process can be carried out in an impregnation machine, specifically a rotary drum impregnation machine or a double cone impregnation machine, preferably a rotary drum impregnation machine. The choice of the mixing method can be made according to actual needs.

[0026] In the above-mentioned preparation method of core-shell hydrogenation catalyst, the drying conditions in step (1) are as follows: the drying temperature is 60℃-150℃, preferably 80℃-120℃; the drying time is 1h-20h, preferably 2h-8h.

[0027] In the above-mentioned method for preparing core-shell hydrogenation catalyst, specifically, the active metal component in step (1) includes at least one metal selected from Group VIII and at least one metal selected from Group VIB, wherein the Group VIII metal is preferably nickel and / or cobalt, and the Group VIB metal is preferably molybdenum and / or tungsten, more preferably molybdenum.

[0028] In the above-mentioned preparation method of core-shell hydrogenation catalyst, specifically, the active metal component in step (1) can be introduced by impregnation. Specifically, the process of introducing the active metal can be carried out by equal volume impregnation. The impregnation process can be carried out in a kneader. Specifically, the material is placed in the kneader, and the precursor of the active metal component is added in batches during the kneading process. The kneading process makes the precursor of the active metal component and the powder evenly mixed. It can be left to stand for a period of time to homogenize it.

[0029] In the above-mentioned method for preparing core-shell hydrogenation catalysts, specifically, the precursor of the active metal component in step (1) is one or more of an oxide containing an active metal component and a salt containing an active metal component; more specifically, the precursor of molybdenum can be industrial-grade molybdenum trioxide and / or ammonium heptamolybdate, preferably molybdenum trioxide; the precursor of tungsten can be one or more of ammonium metatungstate, sodium tungstate, and tungstic phosphate; the precursor of nickel can be one or more of nickel nitrate, nickel acetate, basic nickel carbonate, and nickel chloride, preferably basic nickel carbonate; the precursor of cobalt can be one or more of cobalt nitrate, cobalt acetate, basic cobalt carbonate, and cobalt chloride, preferably basic cobalt carbonate.

[0030] In the above-mentioned preparation method of core-shell hydrogenation catalyst, specifically, in step (1), the active metal component, based on oxides and the total weight of the core layer, has the following contents: the content of Group VIII metal is 1.0wt%-8.0wt%, preferably 2.0wt%-4.0wt%; the content of Group VIB metal is 5.0wt%-20.0wt%, preferably 8.0-15.0wt%.

[0031] In the above-mentioned preparation method of core-shell hydrogenation catalyst, specifically, the molding in step (1) refers to forming a spherical shape; furthermore, the particle size of the spherical core material is controlled to be 0.3 mm-1.0 mm, preferably 0.4 mm-0.8 mm.

[0032] In the above-mentioned preparation method of core-shell hydrogenation catalyst, specifically, the molybdenum carbide powder in step (2) is industrial grade molybdenum carbide powder, and the amount added is 2.0wt%-10.0wt% of the shell weight, preferably 4.0wt%-8.0wt%.

[0033] In the above-mentioned preparation method of core-shell hydrogenation catalyst, specifically, the organic alcohol polymer in step (2) can be one or more of polyethylene glycol, polypropylene glycol, and polyvinyl alcohol, preferably one or more of polyethylene glycol and polypropylene glycol. The molecular weight of the organic alcohol polymer is between 6,000 and 20,000, and the amount of organic alcohol polymer added is 3.0 wt% to 15.0 wt% of the dry weight of the boehmite powder in step (2).

[0034] In the above-mentioned preparation method of core-shell hydrogenation catalyst, specifically, the rolling spherical process can be carried out in a ball rolling machine or a shot blasting machine. In a further preferred case, during the rolling process of the spherical core material obtained in step (1), pseudo-boehmite powder and molybdenum carbide powder are sprayed in, and at the same time, an organic alcohol polymer solution is uniformly sprayed in to obtain the catalyst precursor.

[0035] In the above preparation method of core-shell hydrogenation catalyst, specifically, the drying temperature in step (3) is 60℃-150℃.

[0036] In the above-mentioned method for preparing the core-shell hydrogenation catalyst, specifically, the calcination in step (3) is carried out in the presence of an inert atmosphere, wherein the inert atmosphere is nitrogen and / or an inert gas, and the inert gas can be one or a mixture of several inert gases such as helium, neon, and argon. The calcination temperature is 400℃-700℃.

[0037] A third aspect of the present invention provides a hydrogenation catalyst obtained by the above preparation method.

[0038] Compared with the prior art, the core-shell hydrogenation catalyst and its preparation method provided by the present invention have the following advantages:

[0039] The core-shell hydrogenation catalyst provided by this invention has the characteristic of strong hydrogenation ability for macromolecules containing π-bond electrons. It can hydrogenate components containing polycyclic aromatic hydrocarbons. As the hydrogenation process proceeds, the number of π-bond electrons decreases, preventing the occurrence of over-hydrogenation reaction and avoiding pore blockage. It is especially suitable for the hydrogenation process of oils such as heavy residue oil and ethylene tar.

[0040] The core-shell hydrogenation catalyst provided by this invention uses organic alcohol polymers to expand the pores during the formation of the shell, giving the shell a large pore size. This reduces the steric hindrance when the shell interacts with macromolecules, making it particularly suitable for hydrogenation of fused ring macromolecules. The core layer has a small pore size, enabling hydrogenation of cyclic and chain-like small molecules. The shell and core layers are utilized stepwise to achieve efficient hydrogenation.

[0041] In the preparation process of the core-shell hydrogenation catalyst provided by this invention, an organic acid solution is used in the pretreatment of the core powder and an organic alcohol polymer is used in the formation of the shell. This can avoid the migration of active metals during high-temperature calcination, thereby maintaining good metal dispersion while increasing the calcination temperature.

[0042] In the preparation process of the core-shell hydrogenation catalyst provided by this invention, an organic acid solution is used in the pretreatment of the core layer powder, and an organic alcohol polymer is used in the formation of the shell layer. During the catalyst calcination process, hydroxyl and carboxyl groups are bridged, thereby improving the mechanical properties of the core-shell catalyst and significantly enhancing its wear resistance. Implementation

[0043] The technical features of the present invention are further described below through embodiments, but are not limited to these embodiments.

[0044] In this paper, the abrasion rate test method is described in ASTM D 4058-1996. This test method is used to test the abrasion performance of catalysts or catalyst supports, wherein the catalyst or catalyst support sample is rotated in a cylindrical drum with a single baffle for a fixed number of revolutions.

[0045] In this paper, pore volume and specific surface area were determined by cryogenic liquid nitrogen physical adsorption, specifically using a Micron ASAP2420 cryogenic nitrogen adsorption instrument. The procedure involved: a small sample was vacuum-treated at 300°C for 3-4 hours, and finally, the product was placed under cryogenic liquid nitrogen conditions (-200°C) for nitrogen adsorption-desorption testing. Surface area was obtained using the BET equation, and pore size distribution was obtained using the BJH model.

[0046] Example 1

[0047] Weigh 500g of industrial pseudoboehmite raw material (70wt% on a dry basis) and place it in a rotary drum impregnation machine. Spray 200mL of 4wt% citric acid aqueous solution during the rotation process. After the impregnation is completed, homogenize for 2h and dry at 110℃ for 6h to obtain the pretreated core layer powder.

[0048] Weigh out 73.29 g of molybdenum oxide (99 wt%), 23.89 g of basic nickel carbonate (54 wt% nickel oxide), and 23.98 g of phosphoric acid, and heat to prepare a 500 mL impregnation solution. Place the pretreated core layer powder into a kneader, and gradually spray in 245 mL of impregnation solution during the kneading process. Mix for 8 minutes and let stand for 2 hours to homogenize. Knead the impregnated powder into balls to obtain core layer particles.

[0049] 300g of industrial boehmite raw material (70wt% dry basis) was weighed into a kneader, and 21g of molybdenum carbide powder was added. The mixture was dry-mixed evenly to obtain shell powder. 10.5g of polyethylene glycol 6000 was weighed and dissolved in 200mL of boiling water to prepare a polyethylene glycol 6000 aqueous solution. 300g of core particles were weighed and placed into a ball rolling mill. During the rolling process, the shell powder was added evenly, and the polyethylene glycol 6000 aqueous solution was sprayed in simultaneously to obtain a catalyst precursor with a main particle size of 0.4mm-0.6mm. The product was dried at 110℃ for 8h and calcined at 550℃ under nitrogen atmosphere for 2h to obtain catalyst A.

[0050] Example 2

[0051] Other conditions were the same as in Example 1, except that polyethylene glycol 6000 was replaced with polypropylene glycol 6000, 21g of molybdenum carbide powder was replaced with 10.5g of molybdenum carbide powder, and the calcination at 550°C in a nitrogen atmosphere was replaced with calcination at 700°C in a nitrogen atmosphere, thus obtaining catalyst B.

[0052] Example 3

[0053] Weigh 400g of industrial pseudoboehmite raw material (70wt% on a dry basis) and place it in a rotary drum impregnation machine. Spray 80mL of 8wt% citric acid aqueous solution during the rotation process. After the impregnation is completed, homogenize for 2h and dry at 100℃ for 8h to obtain the pretreated core layer powder.

[0054] Weigh out 83.41 g of molybdenum oxide (99% purity), 38.23 g of basic nickel carbonate (54 wt% nickel oxide), and 30.70 g of phosphoric acid, and heat to prepare a 500 mL impregnation solution. Place the pretreated core layer powder into a kneader, and gradually spray in 196 mL of impregnation solution during the kneading process. Mix for 8 minutes and let it stand for 2 hours to homogenize. Knead the impregnated powder into balls to obtain core layer particles.

[0055] 150g of industrial boehmite raw material (70wt% dry basis) was weighed into a kneader, and 4.2g of molybdenum carbide powder was added. The mixture was dry-mixed evenly to obtain shell powder. 5.25g of polyethylene glycol 10000 was weighed and dissolved in 200mL of boiling water to prepare a polyethylene glycol 10000 aqueous solution. 300g of core particles were weighed and placed into a ball rolling mill. During the rolling process, the shell powder was added evenly, and the polyethylene glycol 10000 aqueous solution was sprayed in simultaneously to obtain a catalyst precursor with a main particle size of 0.6mm-0.8mm. The product was dried at 110℃ for 8h and calcined at 500℃ under a helium atmosphere for 2h to obtain catalyst C.

[0056] Example 4

[0057] Other conditions were the same as in Example 3, except that 80 mL of 8 wt% citric acid aqueous solution was replaced with 210 mL of 5 wt% tartaric acid aqueous solution, and 4.2 g of molybdenum carbide powder was replaced with 8.4 g of molybdenum carbide powder, to obtain catalyst D.

[0058] Comparative Example 1

[0059] Weigh 500g of industrial pseudoboehmite raw material (70wt% on a dry basis) and place it in a rotary drum impregnation machine. Spray 200mL of 4wt% citric acid aqueous solution during the rotation process. After the impregnation is completed, homogenize for 2h and dry at 110℃ for 6h to obtain the pretreated core layer powder.

[0060] Weigh out 73.29 g of molybdenum oxide (99 wt%), 23.89 g of basic nickel carbonate (54 wt% nickel oxide), and 23.98 g of phosphoric acid, and heat to prepare a 500 mL impregnation solution. Place the pretreated core layer powder into a kneader, and gradually spray in 245 mL of impregnation solution during the kneading process. Mix for 8 minutes and let stand for 2 hours to homogenize. Knead the impregnated powder into balls to obtain core layer particles.

[0061] 300g of industrial boehmite raw material (70wt% dry basis) was weighed into a kneader, and 21g of molybdenum oxide powder was added. The mixture was dry-mixed evenly to obtain shell powder. 10.5g of polyethylene glycol 6000 was weighed and dissolved in 200mL of boiling water to prepare a polyethylene glycol 6000 aqueous solution. 300g of core particles were weighed and placed into a ball rolling mill. During the rolling process, the shell powder was added evenly, and the polyethylene glycol 6000 aqueous solution was sprayed in simultaneously to obtain a catalyst precursor with a main particle size of 0.4mm-0.6mm. The product was dried at 110℃ for 8h and calcined at 550℃ under nitrogen atmosphere for 2h to obtain catalyst E.

[0062] Comparative Example 2

[0063] Weigh 400g of industrial pseudoboehmite raw material (70wt% on a dry basis) and place it in a rotary drum impregnation machine. Spray 80mL of 8wt% citric acid aqueous solution during the rotation process. After the impregnation is completed, homogenize for 2h and dry at 100℃ for 8h to obtain the pretreated core layer powder.

[0064] Weigh out 83.41 g of molybdenum oxide (99 wt%), 38.23 g of basic nickel carbonate (54 wt% nickel oxide), and 30.70 g of phosphoric acid, and heat to prepare a 500 mL impregnation solution. Place the pretreated core layer powder into a kneader, and gradually spray in 196 mL of impregnation solution during the kneading process. Mix for 8 minutes and let stand for 2 hours to homogenize. Knead the impregnated powder into balls to obtain core layer particles.

[0065] 150g of industrial pseudoboehmite raw material (70wt% dry basis) was weighed into a kneader, and 4.2g of molybdenum carbide powder was added. The mixture was dry-mixed evenly to obtain shell powder. 300g of core particles were weighed into a ball rolling mill, and the shell powder was added evenly during the rolling process. At the same time, 200mL of water was sprayed in to obtain a catalyst precursor with a main particle size of 0.6mm-0.8mm. The product was dried at 110℃ for 8h and calcined at 500℃ in a helium atmosphere for 2h to obtain catalyst F.

[0066] Table 1. Physicochemical properties of catalysts

[0067]

[0068] As can be seen from Table 1, the hydrogenation catalyst prepared in this study has many large-diameter pores in its shell, good overall metal dispersion, and good wear resistance, making it particularly suitable as a hydrogenation catalyst for heavy oil or residue fluidized bed.

[0069] The catalysts prepared in Examples 1-4 and Comparative Examples 1-2 were evaluated in performance on a continuously stirred autoclave (CSTR) with a catalyst loading of 100 mL. The properties of the feedstock and the evaluation conditions are shown in Table 2. The activity of the catalyst prepared in Comparative Example 1 was set as 100. The evaluation results of the other catalysts compared with the catalyst in Comparative Example 1 are shown in Table 3.

[0070] Table 2. Properties and Evaluation Conditions of Crude Oil

[0071]

[0072] Table 3 Evaluation Results

[0073]

[0074] As can be seen from Table 3, the hydrogenation catalyst prepared in this study significantly improves the removal of metals and impurities and increases the conversion rate compared with the catalyst prepared in the comparative example, indicating that it is particularly suitable for heavy oil hydrogenation reaction.

Claims

1. A core-shell hydrogenation catalyst, comprising a core layer and a shell layer, wherein the core layer is alumina supported with an active metal component, and the shell layer is alumina supported with molybdenum carbide; the active metal is at least one of Group VIII metals and at least one of Group VIB metals; based on the total weight of the shell layer, the molybdenum carbide content is 2.0 wt%-10.0 wt%; in the catalyst, the pore volume of pores with a diameter of 6-15 nm accounts for 40%-60% of the total pore volume, and the pore volume of pores with a diameter >100 nm accounts for more than 15% of the pore volume of the core layer; the Group VIII metal is Ni and / or Co, and the Group VIB metal is Mo, or Mo and W; based on the total weight of the core layer and calculated as metal oxides, the content of the Group VIII metal is 1.0 wt%-8.0 wt%, and the content of the Group VIB metal is 5.0 wt%-20.0 wt%; the molar ratio of hexavalent molybdenum to divalent molybdenum in the Group VIB metal is 0.2-10.

2. The core-shell hydrogenation catalyst according to claim 1, characterized in that: Based on the total weight of the shell, the molybdenum carbide content is 4.0wt%-8.0wt%.

3. The core-shell hydrogenation catalyst according to claim 1, characterized in that: Based on the total weight of the core layer, the content of Group VIII metals, calculated as metal oxides, is 2.0 wt%–4.0 wt%; the content of Group VIB metals is 8.0 wt%–15.0 wt%.

4. The core-shell hydrogenation catalyst according to claim 1, characterized in that: The catalyst has a pore volume of 0.40-0.80 mL / g and a specific surface area of ​​150-280 m². 2 / g.

5. The core-shell hydrogenation catalyst according to claim 1, characterized in that: The catalyst has a pore volume of 0.45-0.75 mL / g and a specific surface area of ​​160-260 m². 2 / g.

6. The core-shell hydrogenation catalyst according to claim 1, characterized in that: The volume ratio of the core layer to the shell layer of the catalyst is 1:3.6-1:0.

38.

7. A method for preparing the core-shell hydrogenation catalyst according to any one of claims 1-6, the method comprising the following steps: (1) Mix the pseudoboehmite powder with an organic acid solution, mix well and dry it before introducing the active metal component, and then obtain a spherical core layer material after molding treatment; (2) Under the condition of rolling spherical formation, the spherical core material obtained in step (1), pseudo-boehmite powder, molybdenum carbide powder, and organic alcohol polymer solution are mixed evenly to obtain the catalyst precursor; (3) The catalyst precursor obtained in step (2) is dried and calcined to obtain a core-shell hydrogenation catalyst.

8. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The concentration of the organic acid solution in step (1) is 1.0wt%-10.0wt%, and the organic acid is selected from at least one of monobasic acid and polybasic acid.

9. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The concentration of the organic acid solution in step (1) is 2.0wt%-6.0wt%.

10. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The organic acid in step (1) is an organic acid with 3-8 carbon atoms.

11. The method for preparing the core-shell hydrogenation catalyst according to claim 8, characterized in that: The organic acid in step (1) is one or more of citric acid, tartaric acid and acrylic acid.

12. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The amount of organic acid solution added in step (1) is 1.0wt%-8.0wt% of the dry weight of the boehmite powder in step (1).

13. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The amount of organic acid solution added in step (1) is 2.0wt%-6.0wt% of the dry weight of the boehmite powder in step (1).

14. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The drying conditions in step (1) are as follows: the drying temperature is 60℃-150℃ and the drying time is 1h-20h.

15. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The drying conditions in step (1) are as follows: the drying temperature is 80℃-120℃ and the drying time is 2h-8h.

16. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The precursor of the active metal component in step (1) is one or more of the following: an oxide containing an active metal component, a salt containing an active metal component, or a mixture of two or more of them.

17. The method for preparing the core-shell hydrogenation catalyst according to claim 13, characterized in that: The precursors of molybdenum are industrial-grade molybdenum trioxide and / or ammonium heptamolybdate; the precursors of tungsten are one or more of ammonium metatungstate, sodium tungstate, and tungstic phosphate; the precursors of nickel are one or more of nickel nitrate, nickel acetate, basic nickel carbonate, and nickel chloride; and the precursors of cobalt are one or more of cobalt nitrate, cobalt acetate, basic cobalt carbonate, and cobalt chloride.

18. The method for preparing the core-shell hydrogenation catalyst according to claim 17, characterized in that: The precursor for molybdenum is industrial-grade molybdenum trioxide; the precursor for nickel is basic nickel carbonate; and the precursor for cobalt is basic cobalt carbonate.

19. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The molding in step (1) refers to forming a spherical shape; the particle size of the spherical core material is controlled to be 0.3mm-1.0mm.

20. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The molding in step (1) refers to forming a spherical shape; the particle size of the spherical core material is controlled to be 0.4 mm-0.8 mm.

21. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The molybdenum carbide powder in step (2) is industrial grade molybdenum carbide powder, and the amount added is 2.0wt%-10.0wt% of the shell weight.

22. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The molybdenum carbide powder in step (2) is industrial grade molybdenum carbide powder, and the amount added is 4.0wt%-8.0wt% of the shell weight.

23. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The organic alcohol polymer in step (2) is one or more of polyethylene glycol, polypropylene glycol, and polyvinyl alcohol. The molecular weight of the organic alcohol polymer is 6,000-20,000. The amount of organic alcohol polymer added is 3.0wt%-15.0wt% of the dry weight of the boehmite powder in step (2).

24. The method for preparing the core-shell hydrogenation catalyst according to claim 23, characterized in that: The organic alcohol polymer in step (2) is polyethylene glycol and / or polypropylene glycol.

25. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The rolling and balling process is carried out in a ball rolling machine or a shot blasting machine.

26. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: During the rolling process of the spherical core material obtained in step (1), pseudo-boehmite powder and molybdenum carbide powder are sprayed in, and organic alcohol polymer solution is sprayed in uniformly at the same time to obtain catalyst precursor.

27. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The drying temperature in step (3) is 60℃-150℃.

28. The method for preparing the core-shell hydrogenation catalyst according to claim 7, characterized in that: The calcination in step (3) is carried out in the presence of an inert atmosphere, which is nitrogen and / or an inert gas, wherein the inert gas is one or more of helium, neon and argon; the calcination temperature is 400℃-700℃.

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