CN116037139A

CN116037139A - Hydrodemetallization catalyst and preparation method thereof

Info

Publication number: CN116037139A
Application number: CN202111260943.4A
Authority: CN
Inventors: 季洪海; 凌凤香; 王少军; 谷明镝; 张会成
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2021-10-28
Filing date: 2021-10-28
Publication date: 2023-05-02
Anticipated expiration: 2041-10-28
Also published as: CN116037139B

Abstract

The invention discloses a hydrodemetallization catalyst and a preparation method thereof, wherein the catalyst comprises an active metal component and an alumina carrier, the active metal component is Mo, co, ni, V, the alumina carrier is a composite carrier of flaky alumina and granular alumina, the loading on the flaky alumina is mainly Mo, co, ni, V, and the loading on the granular alumina is mainly Mo and Ni. The preparation method comprises the following steps: (1) Impregnating sheet-like pseudo-boehmite with an active component impregnating solution I, and drying the impregnated material to obtain modified pseudo-boehmite; (2) And (3) kneading the modified pseudo-boehmite and pseudo-boehmite P2 to form, drying and roasting, and then impregnating the alumina carrier with the active component impregnating solution II to obtain the hydrodemetallization catalyst. The catalyst has high active metal content in the macroporous part, and the active metal component is well matched with the pore canal of the catalyst, so that the catalyst has good application prospect in hydrogenation demetallization reaction of coal tar.

Description

Hydrodemetallization catalyst and preparation method thereof

Technical Field

The invention belongs to the field of catalyst preparation, and particularly relates to a hydrodemetallization catalyst and a preparation method thereof.

Background

At present, the world economy rapidly develops, the demand for fuel oil products is more and more increased, and the quality requirement for the oil products is more and more strict. The shortage of crude oil resources in the world is urgent, but the storage amount of coal is very abundant, so that the use of coal for producing fuel oil products for vehicles is a way, and the main technologies for producing the fuel oil from the coal comprise direct liquefaction of the coal, indirect liquefaction of the coal and the like. The traditional processing method of coal tar aims at physical separation and extraction of single-component or narrow-fraction products, and most medium-temperature coal tar is used as fuel except for extracting small amount of chemical products such as crude phenol. The traditional processing method has neither economical efficiency nor cleanliness, most coal tar can only be simply used as fuel directly, and serious environmental pollution is caused by high sulfur and nitrogen content and incomplete combustion, so that the market value is extremely low. The coal tar can be processed into high-quality products by adopting hydrotreatment, but the impurity content in the coal tar is high, and the catalyst has higher performance requirements. The coal tar hydrotreatment generally requires the cooperation of a hydrogenation protecting agent, a hydrodemetallization catalyst, a hydrofining catalyst and a hydrocracking catalyst to achieve comprehensive processing effects.

For the hydrodemetallization catalyst of coal tar, the hydrodemetallization catalyst is required to have larger pore volume and larger pore diameter because the coal tar contains more metal impurities such as Na, ca, fe, ni. At present, the types of special coal tar hydrodemetallization catalysts are few, and hydrodemetallization catalysts used in the residuum hydrotreatment process are mainly adopted. Hydrodemetallization catalysts are required to have larger pore volume and larger pore diameter, slow down the deactivation of the catalyst and prolong the operation period of the catalyst.

CN102847541a discloses a coal tar hydrodemetallization catalyst and a preparation method thereof, and the preparation process of the catalyst comprises the following steps: (1) taking or preparing an alumina carrier; (2) Treating the alumina carrier in the step (1) by using an organic acid solution with the pH value lower than 3, then impregnating the alumina carrier subjected to acid treatment by using an aluminum nitrate solution, and drying and roasting to obtain a modified alumina carrier; (3) Loading hydrogenation active components by an impregnation method to obtain the coal tar hydrodemetallization catalyst. The method improves the macroporous content and the pore channel penetrability of the final catalyst by the action of the organic acid and the alumina carrier.

CN108722454a discloses a coal tar hydrodemetallization catalyst and a preparation method thereof, wherein the catalyst comprises an alumina carrier and hydrogenation active components. The pore-enlarging agent and the sintering agent are added during the carrier molding, the freeze drying method is adopted in the drying process, and the alumina carrier has large pore volume, concentrated pore distribution, high mechanical strength and proper surface acidity through the dual actions of the pore-enlarging agent and the sintering agent.

The research shows that the pore channel structure of the coal tar hydrodemetallization catalyst can be improved and the macropore content can be improved by the existing means. However, the prior art only pays attention to how to increase the macroporous content of the catalyst, and the matching research of active metal components in the catalyst and pore channels of a carrier is relatively less.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the hydrodemetallization catalyst and the preparation method thereof, and the hydrodemetallization catalyst prepared by the method has high active metal content in the macroporous part, well matches active metal components with catalyst pore channels, and has good application prospect in the hydrodemetallization reaction of coal tar.

The hydrodemetallization catalyst comprises an active metal component and an alumina carrier, wherein the active metal component is Mo, co, ni, V, the alumina carrier is a composite carrier of flaky alumina and granular alumina, the flaky alumina is mainly loaded with Mo, co, ni, V, and the granular alumina is mainly loaded with Mo and Ni; the Mo content of the flaky alumina is 0.3-3 wt% higher than that of the granular alumina carrier in terms of oxide.

In the hydrodemetallization catalyst, the grain size of flaky alumina is 100-500 nm, and the grain size of granular alumina is 20-100 nm; the mass ratio of the flaky alumina is 55-85 wt%, and the mass ratio of the granular alumina is 15-45 wt%. Based on the weight of the hydrodemetallization catalyst, the alumina carrier is 80% -90%, the Mo content is 5.5% -14.5% by weight based on the metal oxide, the V content is 0.5% -2.0% by weight based on the metal oxide, and the Co and Ni content is 1.5% -5.5% by weight based on the metal oxide.

In the hydrodemetallization catalyst, 10-30nm pores account for 55% -85% of the total pore volume, and 10-30nm pores, preferably 60% -80%.

The specific surface area of the hydrodemetallization catalyst is 150-230m ² Per g, pore volume is 0.8-1.4mL/g.

The preparation method of the hydrodemetallization catalyst comprises the following steps:

(1) Impregnating sheet-like pseudo-boehmite P1 with an active component impregnating solution I, and drying the impregnated material to obtain modified pseudo-boehmite GP1;

(2) Kneading the modified pseudo-boehmite GP1 and pseudo-boehmite P2 to form, drying and roasting, then impregnating the alumina carrier with an active component impregnating solution II, and drying and roasting the impregnated material to obtain the hydrodemetallization catalyst.

In the method, the active component impregnating solution I in the step (1) is a solution containing Mo, co and V, wherein the concentration of the Mo in the active component impregnating solution I is 0.1-3.5g/100mL in terms of oxide, the concentration of the Co is 0.1-1.5g/100mL in terms of oxide, and the concentration of the V is 0.2-2g/100mL in terms of oxide. The usage amount of the active component impregnating solution I is the saturated water absorption amount of pseudo-boehmite P1. The drying temperature is 80-140 ℃ and the drying time is 4-8 hours.

In the method of the invention, the sheet pseudo-boehmite P1 in the step (1) has the following properties: 1.0<F ₁ ≤1.5，1.5<F ₂ ≤1.8，F ₁ =D（120）/ D（031），F ₂ =d (120)/D (020); the D (120) represents the crystal grain size of a crystal face corresponding to a (120) peak in an XRD spectrum of pseudo-boehmite crystal grain; d (031) represents the grain size of a crystal face corresponding to the (031) peak in the pseudo-boehmite crystal grain XRD spectrum; d (020) represents the peak (020) in XRD spectrum of pseudo-boehmite crystal grainThe grain size of the corresponding crystal face; the 120 peaks refer to characteristic peaks with 2 theta of 25.5-29.9 degrees in an XRD spectrum; the 031 peak is a characteristic peak with the 2 theta of 36.3-40.5 degrees in an XRD spectrum; the 020 peak is a characteristic peak with 2 theta of 12.0-16.2 degrees in an XRD spectrum, D=Kλ/(Bcosθ), K is Scherrer constant, λ is diffraction wavelength of a target material, B is half-peak width of the diffraction peak, and θ is diffraction angle.

In the method of the invention, the preparation method of the sheet pseudo-boehmite P1 in the step (1) comprises the following steps: mixing gamma-phase alumina powder with propylene oxide water solution, performing hydrothermal treatment, washing and drying the treated material to obtain the product.

The gamma-phase alumina powder can be a commercial product or can be prepared according to the prior art, and is generally prepared by taking a pseudo-boehmite precursor which is sold in the market or prepared by the prior art as a raw material and roasting the pseudo-boehmite precursor to obtain the gamma-phase alumina powder; the roasting temperature is 400-600 ℃, and the roasting time is 4-8 hours.

The mass percentage concentration of the propylene oxide aqueous solution is 2.5-12%, preferably 4-8%, and the mass ratio of the dosage of the propylene oxide aqueous solution to the gamma-phase alumina powder is 3:1-10:1, preferably 4:1-8:1. preferably, polyethylene glycol 2000-20000 is added into the propylene oxide aqueous solution at the same time, and the mass ratio of the addition amount of the polyethylene glycol 2000-20000 to the gamma-phase alumina powder is 0.01:1-0.05:1.

the hydrothermal treatment is carried out in a closed container, the sealed container is preferably an autoclave, the treatment temperature is 110-180 ℃, preferably 120-160 ℃, the treatment time is 4-8 hours, and the pressure in the sealed container is autogenous pressure during the hydrothermal treatment.

The drying temperature is 100-160 ℃, and the drying time is 6-10 hours.

In the method of the present invention, the pseudo-boehmite P2 in the step (2) may be granular pseudo-boehmite prepared according to the existing method, and the pseudo-boehmite may be pseudo-boehmite prepared by any method, such as acid precipitation method, alkali precipitation method, aluminum alkoxide hydrolysis method, etc., preferably pseudo-boehmite with a pore diameter of more than 10 nm.

In the method of the invention, the mass ratio of the modified pseudo-boehmite GP1 to the pseudo-boehmite P2 in the step (2) is 11:9-17:3.

in the method of the invention, the kneading molding in the step (2) is carried out by adopting a conventional method in the field, and in the molding process, one or more conventional molding aids such as a peptizing agent, an extrusion aid and the like can be added according to requirements. The peptizing agent is one or more of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, oxalic acid and the like, the mass percentage concentration of the peptizing agent is 0.5% -2%, and the dosage of the peptizing agent is determined according to the molding effect; the extrusion aid is sesbania powder, and the addition amount of the extrusion aid is 1-3% of the weight of the final alumina carrier.

In the method of the invention, the active component impregnating solution II in the step (2) is a solution containing Mo and Ni. The Mo concentration is 4.5-12.5g/100mL in terms of oxide, and the Ni concentration is 0.5-3.5g/100mL in terms of oxide.

In the method, the drying temperature of the alumina carrier in the step (2) is 100-160 ℃ and the drying time is 6-10 hours; the calcination temperature of the alumina carrier is 450-750 ℃, preferably 500-600 ℃ and the calcination time is 4-6 hours. The drying temperature of the catalyst is 100-140 ℃ and the drying time is 6-10 hours; the catalyst is calcined at a temperature of 400-600deg.C, preferably 450-500deg.C, for a period of 4-6 hours.

The hydrodemetallization catalyst of the invention is applied to the coal tar hydrotreatment process, and the general reaction conditions are as follows: the reaction temperature is 360-420 ℃, the pressure is 11-15MPa, and the liquid hourly space velocity is 0.2-0.6 hour ^-1 The volume ratio of hydrogen to oil is 1000-2000.

Compared with the prior art, the invention has the following advantages:

(1) The hydrodemetallization catalyst takes two pseudo-boehmite as raw materials, and is synthesized in situ to obtain the catalyst with the matching of active metal and pore canal, namely the cooperative matching of the pore canal size, the metal content and the metal type; the flaky pseudo-boehmite P1 is prepared from pseudo-boehmite with a secondary particle structure as a flaky stacking body, and is used as a raw material, different metals are respectively immersed in the raw material in advance, the flaky particles are stacked in a crossing manner in the forming process, a large number of mesoporous and macroporous pore channels are formed, the flaky particles have a certain thickness, and the carrier can bear larger pressure without collapsing during extrusion molding and roasting, so that the formed pore channels are not damaged, and the pore channel content of macropores is maintained.

(2) The invention firstly impregnates pseudo-boehmite with a secondary particle structure of flaky stacking body by using active components with a certain concentration, so that the active metal content at the flaky alumina carrier position, namely the formed macropores, in the final catalyst is relatively high, and the impregnated active components contain a proper amount of vanadium, so that the interaction among the components can be effectively promoted, and the hydrodemetallization activity at the macropores of the catalyst is greatly improved. In addition, the removed metal impurities are deposited at the large holes, and the prepared catalyst has higher activity stability due to the higher metal capacity of the large holes.

Drawings

FIG. 1 is an XRD spectrum of large-grain pseudo-boehmite P1-1 prepared in example 1.

FIG. 2 is an SEM image of large-grain pseudo-boehmite P1-1 prepared in example 1.

FIG. 3 is a cross-sectional SEM image of the catalyst prepared in example 5 and a selected area for component analysis.

Detailed Description

The technical scheme and effect of the present invention will be further described with reference to the following examples, but is not limited thereto. Wherein, in the invention, wt% represents mass fraction.

BET method: application N ₂ Physical adsorption-desorption characterization examples and comparative examples the pore structure of the carriers were as follows: using ASAP-2420 type N ₂ The physical adsorption-desorption instrument characterizes the structure of the sample hole. And (3) taking a small amount of sample, vacuum-treating for 3-4 hours at 300 ℃, and finally placing the product under the condition of low temperature (-200 ℃) of liquid nitrogen for nitrogen adsorption-desorption test. Wherein the specific surface area is obtained according to BET equation, and the distribution ratio of pore volume and pore diameter below 30nm is obtained according to BJH model.

The microstructure of the alumina carrier is characterized by applying a scanning electron microscope, and the specific operation is as follows: the JSM-7500F scanning electron microscope is adopted to characterize the microstructure of the carrier, the accelerating voltage is 5KV, the accelerating current is 20 mu A, and the working distance is 8mm.

X-ray diffraction (XRD) analysis was performed on a D/max-2500 type full-automatic rotary target X-ray diffractometer manufactured by Japanese Kabushiki Kaisha. The Cu target, the K alpha radiation source, the graphite monochromator and the tube voltage of 40kV and the tube current of 80mA are adopted.

And (3) analyzing the metal content, and measuring the metal content in the reaction raw materials and the generated oil by adopting an IRIS Advantage full-spectrum direct-reading plasma atomic emission spectrometer of Thermo Scientific company according to an ASTM D4951-2006 standard method.

Demetallization% = (metal content of feed oil-metal content of product)/metal content of feed oil x 100%.

Relative demetallization rate: the demetallization rate of a certain catalyst was measured and defined as 100% relative demetallization rate, and the impurity removal rate of other catalyst/defined as catalyst impurity removal rate x 100% relative impurity removal rate.

Preparation of sheet pseudo-boehmite:

example 1

500 g of pseudo-boehmite (self-made by an aluminum sulfate-sodium metaaluminate method, and the dry basis weight content of which is 76%) is weighed and baked at 500 ℃ for 6 hours to prepare gamma-phase alumina powder.

Weighing 100 g of gamma-phase alumina, adding 630 g of propylene oxide solution with the mass concentration of 5.4%, magnetically stirring for 30 minutes, transferring the mixed material into an autoclave, sealing, heating at 130 ℃ for 6 hours, cooling, filtering, washing, drying at 110 ℃ for 6 hours to obtain sheet-like pseudo-boehmite P1-1, wherein the properties of the pseudo-boehmite are shown in Table 1, the XRD spectrum of the pseudo-boehmite is shown in figure 1, and the scanning electron microscope is shown in figure 2.

Example 2

As in example 1, except that the firing temperature of pseudo-boehmite was 480 ℃. The propylene oxide solution was used in an amount of 730 g and the mass concentration of the solution was 4.3%. The heat treatment temperature is 140 ℃ and the treatment time is 5 hours, and the sheet pseudo-boehmite P1-2 is prepared, and the properties of the pseudo-boehmite are shown in Table 1.

Example 3

The same as in example 1 except that the amount of propylene oxide solution was 540 g, the mass concentration of the solution was 6.6%. The heat treatment temperature is 120 ℃ and the treatment time is 7.5 hours, and the pseudo-boehmite P1-3 is prepared, and the properties of the pseudo-boehmite are shown in Table 1.

Example 4

The same as in example 1 except that the amount of propylene oxide solution was 430 g, the mass concentration of the solution was 7.4%, and an appropriate amount of polyethylene glycol-10000 was added to the mixture, and the addition amount of polyethylene glycol-10000 was 1.5 g. The heat treatment temperature is 155 ℃ and the treatment time is 4 hours, and the sheet pseudo-boehmite P1-4 is prepared, and the properties of the pseudo-boehmite are shown in Table 1.

Comparative example 1

As in example 1, except that the mixed material was not transferred into an autoclave for sealing treatment, but subjected to normal pressure reflux treatment in a condensing reflux apparatus, the gamma-phase alumina was analyzed to be not rehydrated to pseudo-boehmite.

Comparative example 2

Comparative boehmite P5, the properties of which are shown in Table 1, were obtained as in example 1 except that propylene oxide was replaced with the same amount of ethylene oxide.

Comparative example 3:

comparative boehmite P6, the properties of which are shown in Table 1, were obtained by replacing propylene oxide with the same amount of distilled water as in example 1.

Preparation of hydrodemetallization catalyst:

example 5

Weighing 100 g of flaky pseudo-boehmite P1-1 prepared in the example, impregnating the pseudo-boehmite P1-1 with an active component impregnating solution I with the concentration of molybdenum oxide of 2.0g/100mL and the concentration of cobalt oxide of 0.52g/100mL and the concentration of vanadium pentoxide of 1.0g/100mL in a saturated impregnation method, and drying the impregnated pseudo-boehmite at 120 ℃ for 6 hours to obtain the modified pseudo-boehmite GP1-1.

20 g of pseudo-boehmite P2 (produced by Winzhou refined alumina Co., ltd., dry basis weight content is 5%, and several apertures are 12.5 nm) is weighed, 42 g of modified pseudo-boehmite GP1-1 mass and 0.2 g of sesbania powder are evenly mixed, a proper amount of acetic acid aqueous solution with mass concentration of 1% is added for kneading, extrusion molding is carried out, the molded product is dried at 140 ℃ for 6 hours, and the dried product is baked in air at 550 ℃ for 5 hours, thus obtaining the alumina carrier.

30 g of the alumina carrier is weighed, the alumina carrier is impregnated with Mo-Ni-P active component impregnating solution II with the concentration of molybdenum oxide of 6.5g/100mL and the concentration of nickel oxide of 1.6g/100mL in a saturated impregnation mode, the impregnated material is dried at 120 ℃ for 6 hours, and the dried material is roasted in air at 500 ℃ for 5 hours to prepare the hydrodemetallization catalyst Cat-1, and the catalyst properties are shown in Table 2. The metal component content at the flaky particles and the granular particles in the catalyst is measured by using a scanning electron microscope and an energy spectrometer, and the measurement results are shown in Table 3. The measurement selection area is shown in fig. 3.

Example 6

As in example 5, except that the pseudo-boehmite used in the modification treatment was pseudo-boehmite prepared in example 2, the concentration of molybdenum oxide in the active component impregnating solution I was 2.5g/100mL, the concentration of cobalt oxide was 0.63g/100mL, and the concentration of vanadium pentoxide was 0.7g/100mL; the mass of the modified pseudo-boehmite GP1-2 is 57 g when the carrier is molded; the concentration of molybdenum oxide in the active component impregnating solution II is 6.0g/100mL, the concentration of nickel oxide is 1.5g/100mL, and the hydrodemetallization catalyst Cat-2 is prepared, and the catalyst properties are shown in Table 2.

Example 7

As in example 5, except that the pseudo-boehmite used in the modification treatment was pseudo-boehmite prepared in example 4, the concentration of molybdenum oxide in the active component impregnating solution I was 3.0g/100mL, the concentration of cobalt oxide was 0.75g/100mL, and the concentration of vanadium pentoxide was 0.5g/100mL; the mass of the modified pseudo-boehmite GP1-4 is 90 g when the carrier is molded; the concentration of molybdenum oxide in the active component impregnating solution II is 5.6g/100mL, the concentration of nickel oxide is 1.4g/100mL, and the hydrodemetallization catalyst Cat-3 is prepared, and the catalyst properties are shown in Table 2.

Example 8

As in example 5, except that the pseudo-boehmite used in the modification treatment was pseudo-boehmite prepared in example 3, the concentration of molybdenum oxide in the active component impregnating solution I was 1.5g/100mL, the concentration of cobalt oxide was 0.35g/100mL, and the concentration of vanadium pentoxide was 1.5g/100mL; the mass of the modified pseudo-boehmite GP1-3 is 30 g when the carrier is molded; the concentration of molybdenum oxide in the active component impregnating solution II is 7.0g/100mL, the concentration of nickel oxide is 1.8g/100mL, and the hydrodemetallization catalyst Cat-4 is prepared, and the catalyst properties are shown in Table 2.

Comparative example 4

A comparative hydrodemetallization catalyst Cat-5 was prepared as in example 5 except that the flaky pseudo-boehmite P1-1 was changed to pseudo-boehmite P5 prepared in the same amount as in comparative example 2, and the catalyst properties are shown in Table 2.

Comparative example 5

A comparative hydrodemetallization catalyst Cat-6 was prepared as in example 5 except that the pseudo-boehmite P1-1 was replaced with the pseudo-boehmite P6 prepared in the same amount in comparative example 3, and the catalyst properties are shown in Table 2.

Comparative example 6

As in example 5, except that the pseudo-boehmite in sheet form was not subjected to modification treatment, the same amounts of molybdenum oxide, cobalt oxide and vanadium pentoxide were added at the time of support molding, to prepare a comparative hydrodemetallization catalyst Cat-7, the catalyst properties of which are shown in Table 2.

TABLE 1 pseudo-boehmite properties

TABLE 2 hydrodemetallization catalyst Properties

As can be seen from the data in Table 2, the hydrodemetallization catalyst prepared by the method has higher specific surface area and pore volume and high pore channel content of 10-30 nm.

The active metal content of the catalyst Cat-1 prepared in example 5 and the active metal content of the catalyst Cat-7 prepared in comparative example 6 at different morphologies are measured by using a scanning electron microscope and an energy spectrometer, 5 areas at the two morphologies of the different catalysts are randomly selected for measurement, the average value is taken, and the measurement structure is shown in Table 3.

TABLE 3 hydrodemetallization catalyst select area composition

As can be seen from the data in Table 3, in the hydrodemetallization catalyst prepared by the method, the active metal content of the macropores formed by the flaky alumina is higher, and the active metal component content is better matched with the pore channels of the catalyst.

Catalytic performance evaluation:

the hydrodemetallization catalysts (Cat-1-Cat-7) prepared in the above examples and comparative examples were subjected to catalytic performance evaluation as follows:

the catalytic performance of hydrodemetallization catalyst Cat-1-Cat-7 is evaluated on a 200mL small-sized evaluation device by taking certain coal tar as a raw material, wherein the properties of raw oil are shown in Table 4, and the reaction conditions are as follows: the reaction temperature is 365 ℃, the pressure is 12.5MPa, and the liquid hourly space velocity is 0.5 hour ^-1 The hydrogen oil volume ratio is 1200, the contents of various impurities in the generated oil are measured after the reaction for 500 hours and 2000 hours, the impurity removal rate is calculated, and the evaluation results are shown in table 5.

TABLE 4 Properties of raw oil

Table 5 comparative catalyst hydrogenation performance

As can be seen from the data in Table 5, the catalyst of the present invention has higher hydrodemetallization activity and activity stability than the comparative catalyst.

Claims

1. A hydrodemetallization catalyst characterized by: the composite alumina comprises an active metal component and an alumina carrier, wherein the active metal component is Mo, co, ni, V, the alumina carrier is a composite carrier of flaky alumina and granular alumina, the flaky alumina is mainly loaded with Mo, co, ni, V, and the granular alumina is mainly loaded with Mo and Ni; the Mo content of the flaky alumina is 0.3-3 wt% higher than that of the granular alumina carrier in terms of oxide.

2. The hydrodemetallization catalyst of claim 1, characterized in that: the grain size of the flaky alumina is 100-500 nm, and the grain size of the granular alumina is 20-100 nm.

3. The hydrodemetallization catalyst of claim 1, characterized in that: the mass ratio of the flaky alumina is 55-85 wt%, and the mass ratio of the granular alumina is 15-45 wt%.

4. The hydrodemetallization catalyst of claim 1, characterized in that: based on the weight of the catalyst, the alumina carrier is 80% -90%, the Mo content is 5.5% -14.5% by weight based on the metal oxide, the V content is 0.5% -2.0% by weight based on the metal oxide, and the Co and Ni content is 1.5% -5.5% by weight based on the metal oxide.

5. The hydrodemetallization catalyst of claim 1, characterized in that: the 10-30nm pores account for 55% -85%, preferably 60% -80% of the total pore volume.

6. The hydrodemetallization catalyst of claim 1, characterized in that: the specific surface area of the catalyst is 150-230m ² Per g, pore volume is 0.8-1.4mL/g.

7. A method for preparing the hydrodemetallization catalyst according to any one of claims 1 to 6, which is characterized by comprising the following contents: (1) Impregnating sheet-like pseudo-boehmite P1 with an active component impregnating solution I, and drying the impregnated material to obtain modified pseudo-boehmite GP1; (2) Kneading the modified pseudo-boehmite GP1 and pseudo-boehmite P2 to form, drying and roasting, then impregnating the alumina carrier with an active component impregnating solution II, and drying and roasting the impregnated material to obtain the hydrodemetallization catalyst.

8. The method according to claim 7, wherein: the active component impregnating solution I in the step (1) is a solution containing Mo, co and V, wherein the concentration of Mo in the active component impregnating solution I is 0.1-3.5g/100mL calculated by oxide, the concentration of Co is 0.1-1.5g/100mL calculated by oxide, and the concentration of V is 0.2-2g/100mL calculated by oxide.

9. The method according to claim 7, wherein: the sheet pseudo-boehmite P1 described in the step (1) has the following properties: 1.0<F ₁ ≤1.5，1.5<F ₂ ≤1.8，F ₁ =D（120）/ D（031），F ₂ =d (120)/D (020); the D (120) represents the crystal grain size of a crystal face corresponding to a (120) peak in an XRD spectrum of pseudo-boehmite crystal grain; d (031) represents the grain size of a crystal face corresponding to the (031) peak in the pseudo-boehmite crystal grain XRD spectrum; d (020) represents a crystal grain size of a crystal face corresponding to a (020) peak in the pseudo-boehmite crystal grain XRD spectrum; the 120 peaks refer to characteristic peaks with 2 theta of 25.5-29.9 degrees in an XRD spectrum; the 031 peak is a characteristic peak with the 2 theta of 36.3-40.5 degrees in an XRD spectrum; the 020 peak is a characteristic peak with 2 theta of 12.0-16.2 degrees in an XRD spectrum, D=Kλ/(Bcosθ), K is Scherrer constant, λ is diffraction wavelength of a target material, B is half-peak width of the diffraction peak, and θ is diffraction angle.

10. The method according to claim 7, wherein: the preparation method of the sheet pseudo-boehmite P1 in the step (1) comprises the following steps: mixing gamma-phase alumina powder with propylene oxide water solution, performing hydrothermal treatment, washing and drying the treated material to obtain the product.

11. The method according to claim 10, wherein: the mass percentage concentration of the propylene oxide aqueous solution is 2.5% -12%, and the mass ratio of the dosage of the propylene oxide aqueous solution to the gamma-phase alumina powder is 3:1-10:1.

12. the method according to claim 10, wherein: the hydrothermal treatment is carried out in a closed container, the sealed container is preferably an autoclave, the treatment temperature is 110-180 ℃, the treatment time is 4-8 hours, and the pressure in the sealed container is autogenous pressure during the hydrothermal treatment.

13. The method according to claim 7, wherein: the pseudo-boehmite P2 in the step (2) is granular pseudo-boehmite prepared according to the prior method.

14. The method according to claim 7, wherein: the mass ratio of the modified pseudo-boehmite GP1 to the pseudo-boehmite P2 in the step (2) is 11:9-17:3.

15. the method according to claim 7, wherein: the active component impregnating solution II in the step (2) is a solution containing Mo and Ni, wherein the concentration of Mo is 4.5-12.5g/100mL in terms of oxide, and the concentration of Ni is 0.5-3.5g/100mL in terms of oxide.

16. The method according to claim 7, wherein: the drying temperature of the alumina carrier in the step (2) is 100-160 ℃ and the drying time is 6-10 hours; the roasting temperature of the alumina carrier is 450-750 ℃ and the roasting time is 4-6 hours; the drying temperature of the catalyst is 100-140 ℃ and the drying time is 6-10 hours; the roasting temperature of the catalyst is 400-600 ℃, and the roasting time is 4-6 hours.

17. Use of the hydrodemetallization catalyst of any one of claims 1-6 in a hydrodemetallization reaction of coal tar.