CN108654700B

CN108654700B - Tri-peak pore distribution hydrodemetallization catalyst and preparation method thereof

Info

Publication number: CN108654700B
Application number: CN201810518525.2A
Authority: CN
Inventors: 徐景东; 车晓瑞; 王娇红
Original assignee: Sinochem Quanzhou Petrochemical Co Ltd; Sinochem Quanzhou Energy Technology Co Ltd
Current assignee: Sinochem Quanzhou Petrochemical Co Ltd; Sinochem Quanzhou Energy Technology Co Ltd
Priority date: 2018-05-28
Filing date: 2018-05-28
Publication date: 2020-12-04
Anticipated expiration: 2038-05-28
Also published as: CN108654700A

Abstract

The invention discloses a hydrodemetallization catalyst and a preparation method thereof. The catalyst has a trimodal pore distribution structure, the pore volume of the catalyst is 0.5-1.3 mL/g, and the specific surface area of the catalyst is 50-200 m²The volume of pores with the diameter of less than 50 nm accounts for 30-50% of the total pore volume, the volume of pores with the diameter of 50-100 nm accounts for 10-30% of the total pore volume, and the volume of pores with the diameter of more than 100 nm accounts for 30-50% of the total pore volume. Compared with the prior art, the invention adopts a brand-new preparation method of the hydrodemetallization catalyst with trimodal pore distribution to carry out hydrothermal treatment on the alumina carrier with bimodal pore distribution, and transition pores are manufactured between mesopores and macropores, so that the pore loss between the mesopores and the macropores can be compensated. The hydrogenation demetalization catalyst with trimodal pore distribution prepared by the method is more suitable for hydrogenation demetalization and deasphalting of heavy oil such as residual oil.

Description

Tri-peak pore distribution hydrodemetallization catalyst and preparation method thereof

Technical Field

The invention relates to a hydrogenation demetalization catalyst with trimodal pore distribution and a preparation method thereof.

Background

In recent years, with the heavy crude oil resource, the increase of the consumption demand of fuel oil and the stricter of environmental protection regulations, the hydrogenation technology is adopted to convert heavy oil including residual oil into high-quality light fuel oil and chemical products, which is beneficial to improving the processing depth of crude oil, reducing environmental pollution, improving the yield of light oil, improving the product quality and the like.

The residual oil is rich in most of sulfur, nitrogen, polycyclic aromatic hydrocarbon and metal (mainly Fe, Ni, V and the like) in the crude oil. Unlike desulfurization and denitrification, metals such as Fe, Ni, and V are gradually deposited in catalyst channels after being removed by hydrogenation, covering the catalyst active sites, and blocking the catalyst channels to finally and completely deactivate the catalyst, so that hydrogenation removal must be performed first to avoid poisoning downstream hydrodesulfurization, hydrodenitrification, catalytic cracking catalysts, and the like. Metals in heavy oils such as residual oil are mainly present in macromolecular compounds such as colloids and asphaltenes. The compound has complex structure, large molecular size and difficult diffusion, and the metal is often deposited near the orifice to lead the catalyst to be prematurely deactivated, thus reducing the utilization rate of the catalyst. Therefore, in order to maximize the residual oil hydrodemetallization performance, the catalyst is required to have good reaction activity, and also needs to have reasonable pore distribution, so that the mass transfer diffusion, the reaction and the metal deposition of macromolecular reactants can be effectively improved. The solution is to prepare alumina carrier with different pore size distribution, which has both macropore (pore size over 50 nm) and mesopore (pore size under 50 nm), the macropore can provide channel for diffusion of metal-containing asphaltene and other macromolecules, promote impurity-containing macromolecules to quickly diffuse and deposit to the inner pore of the catalyst, improve the utilization rate of the catalyst, and the mesopore can provide as large a specific surface as possible for reaction, promote impurity removal and deposition. Research reports [ J. Ancheyta et al./Catalysis Today 109 (2005) 3-15 ] that bimodal catalysts containing a large number of macropores have a more uniform distribution of metal in the radial direction of the catalyst compared to unimodal catalysts. The deposition distribution of the catalyst metal in the radial direction is more uniform with a multimodal continuous distribution of pores, given the optimum combination of activity and catalyst porosity. Therefore, the trimodal and other multi-modal catalyst carriers with continuously distributed pore channels can ensure that the metal is more uniformly deposited in the pore channels of the catalyst, improve the activity and impurity-containing capacity of the catalyst and contribute to prolonging the running period of the catalyst.

In the prior art, the preparation and application of the hydrogenation demetallization catalyst with bimodal pore distribution for hydrogenation of heavy oil such as residue oil are reported more, and the reports of the three-peak hydrogenation demetallization catalyst and other multimodal hydrogenation demetallization catalysts and the preparation methods thereof are few. In the existing hydrodemetallization catalyst with bimodal pore distribution, the bimodal generally comprises mesopores and macropores, the diameter of the mesopores is 2-50 nm, and the diameter of the macropores is more than 100 nm. The bimodal pore distribution catalyst lacks transitional pores between macropores and mesopores, such as pores of 50-100 nm. Some compounds with large molecular size in the residual oil can be diffused by utilizing the macropores, but cannot be well diffused into the mesopores to react and deposit metals, so that the metals are not uniformly distributed in the pore channels of the catalyst. Therefore, the development of trimodal and other multimodal pore distribution catalysts can improve the performance of heavy oil hydroprocessing, especially hydrodemetallization and deasphalting.

US5266300 discloses a heavy oil hydrogenation catalyst with trimodal pore distribution, its preparation and use. The preparation method of the carrier comprises the steps of mixing, forming, drying and roasting pseudo-boehmite containing bimodal pore distribution and alumina thereof. The carrier has trimodal pore distribution, and trimodal pores are respectively distributed at the pore diameter of 3-100 nm, the pore diameter of 100-1000 nm and the pore diameter of 1000-10000 nm. The trimodal pore catalyst has higher hydrodeasphaltene and demetallization activity than commercial catalysts. However, the diameter of two kinds of pores of the trimodal pore catalyst is more than 100 nm, transition pores still lack between mesopores and macropores, and the continuity of pore canal distribution of the mesopores and the macropores cannot be realized.

US7790130 discloses a method for preparing alumina with trimodal pore distribution. The method comprises mixing hydrated alumina with carbonate, shaping and roasting. The prepared alumina carrier has trimodal pore distribution, mainly including small pores less than 15 nm, mesopores of 15-50 nm and large pores more than 50 nm. The alumina with trimodal pore distribution prepared by the method has low pore volume and a large amount of alkali metal sodium, and is not suitable for serving as a heavy oil hydrotreating catalyst.

Disclosure of Invention

The invention aims to provide a novel hydrogenation demetalization catalyst with trimodal pore distribution and a novel method for preparing the hydrogenation demetalization catalyst with trimodal pore distribution, aiming at the defects of the existing hydrogenation demetalization catalyst with bimodal and trimodal pore distribution in residual oil hydrogenation demetalization and demetalization. Compared with the preparation method of the catalyst with bimodal and trimodal pore distribution in the prior patent, the invention adopts a brand-new preparation method of the hydrodemetallization catalyst with trimodal pore distribution to carry out hydrothermal treatment on the alumina carrier with bimodal pore distribution, so as to manufacture transition pores between mesopores and macropores and make up for the pore deletion between the mesopores and the macropores. The hydrogenation demetalization catalyst with trimodal pore distribution prepared by the method is more suitable for hydrogenation demetalization and deasphalting of heavy oil such as residual oil.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a hydrodemetallization catalyst. The catalyst contains an alumina carrier with trimodal pore distribution and an active metal component loaded on the carrier. The catalyst has a typical trimodal pore distribution structure, the pore volume is 0.5-1.3 mL/g, and the specific surface area is 50-200 m determined by mercury intrusion method²The volume of pores with the diameter of less than 50 nm accounts for 30-50% of the total pore volume, the volume of pores with the diameter of 50-100 nm accounts for 10-30% of the total pore volume, and the volume of pores with the diameter of more than 100 nm accounts for 30-50% of the total pore volume. The active metal components contained in the catalyst are at least one metal component of VIB group and at least one metal component of VIII group, the content of the metal component oxides of the VIB group is 0.1-15 wt% and the content of the metal component oxides of the VIII group is 0.1-5 wt% calculated by oxides and based on the catalyst. The catalyst also contains an auxiliary phosphorus, the content of the oxide of the auxiliary phosphorus is 0-5 wt% calculated by oxide and based on the catalyst.

The invention also provides a preparation method of the trimodal pore distribution hydrodemetallization catalyst, which comprises the steps of preparing the bimodal alumina carrier, preparing the trimodal alumina carrier by carrying out hydrothermal treatment on the bimodal alumina carrier, and loading a hydrogenation active metal component on the trimodal alumina carrier.

(1) The preparation of the bimodal alumina carrier comprises the following steps: the alumina precursor containing pseudo-boehmite is mixed and kneaded with extrusion aid and peptizing agent, formed and roasted. The alumina precursor can be one or a mixture of more of gibbsite, pseudo-boehmite, boehmite and amorphous aluminum hydroxide, and can be a commercial product or a product prepared by any method in the prior art. Preferably pseudoboehmite. The extrusion aid can be one or more of sesbania powder, methyl cellulose, starch and polyvinyl alcohol, and the addition amount of the extrusion aid is 1-5 wt% of alumina (the amount of the alumina is converted from an alumina precursor). The peptizing agent can be an aqueous solution of inorganic acid or organic acid, and the concentration of the acid solution is 0.05-5 wt%; the inorganic acid aqueous solution is hydrochloric acid, sulfuric acid solution or nitric acid solution; the organic acid aqueous solution is formic acid solution, acetic acid solution or citric acid solution. The forming method can adopt tabletting, rolling ball or extruding strip and the like. The shape of the carrier can be made into a sheet shape, a spherical shape, a cylindrical shape, a clover shape or a clover shape according to different requirements. The roasting temperature is 500-1000 ℃, and the roasting time is 1-8 h. The prepared alumina carrier has a bimodal pore distribution structure. The pore volume of the bimodal alumina carrier is 0.6-1.4 mL/g and the specific surface area is 50-300 m measured by mercury intrusion method²The volume of pores with the diameter of less than 50 nm accounts for 50-70% of the total pore volume, the volume of pores with the diameter of 50-100 nm accounts for 0-5% of the total pore volume, and the volume of pores with the diameter of more than 100 nm accounts for 30-50% of the total pore volume.

(2) The bimodal alumina carrier is subjected to hydrothermal treatment to prepare a trimodal alumina carrier: and carrying out hydrothermal treatment on the prepared bimodal pore distribution alumina carrier under a closed condition, drying and roasting to obtain the trimodal alumina carrier. The hydrothermal treatment is to separate the bimodal alumina carrier and water and put the bimodal alumina carrier and the water into a closed container such as a reaction kettle and the like, heat the bimodal alumina carrier and the water to a certain temperature under a closed condition, and then carry out hydrothermal treatment for a period of time at the hydrothermal temperature. The temperature of the hydrothermal treatment is 150-300 ℃, and the time is 1-24 h. The amount of water used in the hydrothermal treatment is 5-200% of the mass of the bimodal alumina carrier. Drying temperatureThe temperature is 80-200 ℃, and the drying time is 1-24 h. The roasting temperature is 400-800 ℃, and the roasting time is 1-8 h. The prepared alumina carrier has a trimodal pore distribution structure, and the pore volume of the trimodal alumina carrier is 0.6-1.4 mL/g and the specific surface area is 50-200 m measured by mercury intrusion method²The volume of pores with the diameter of less than 50 nm accounts for 30-50% of the total pore volume, the volume of pores with the diameter of 50-100 nm accounts for 10-30% of the total pore volume, and the volume of pores with the diameter of more than 100 nm accounts for 30-50% of the total pore volume.

(3) The three-peak alumina carrier is loaded with active metal components: the supporting method is an impregnation method, and comprises preparing a solution of a compound containing an active metal component and impregnating the carrier with the solution, followed by drying, calcination or no calcination to obtain the catalyst. The hydrogenation active metal component contained in the catalyst is selected from at least one metal component of VIB group and at least one metal component of VIII group, and calculated by oxide and based on the catalyst, the content of the oxide of the metal component of VIB group is 0.1-15 wt%, and the content of the oxide of the metal component of VIII group is 0.1-5 wt%. The catalyst also contains an auxiliary phosphorus, the content of the oxide of the auxiliary phosphorus is 0-5 wt% calculated by oxide and based on the catalyst. The dipping temperature is 10-60 ℃, and the dipping time is 1-24 h. The drying temperature is 80-200 ℃, and the drying time is 1-24 h. The roasting temperature is 300-600 ℃, and the roasting time is 1-10 h.

The invention has the beneficial effects that: the invention provides a hydrogenation demetalization catalyst with trimodal pore distribution and a preparation method thereof. Transition holes are manufactured between mesopores and macropores of the alumina carrier with bimodal pore distribution by adopting hydrothermal treatment, so that the continuity of the pore distribution of the hydrodemetallization catalyst is realized, and the activity of the hydrodemetallization catalyst is improved.

The invention can control the hydrothermal condition, such as the adding amount and the adding mode of water, and adjust the aperture and the proportion of the transition holes. The transition hole can make up for the hole deletion between the macropore and the mesopore, and realizes the continuous distribution of the holes with different pore diameters. The method is simple and easy to operate.

The hydrodemetallization catalyst provided by the invention has trimodal pore distribution, and can be used as catalysts for hydrodemetallization, hydrodeasphaltene removal and the like of heavy oil such as residue oil and the like.

The catalyst provided by the invention can be used alone or in combination with other catalysts. The catalyst provided by the invention is used in combination with other hydrogenation catalysts to carry out hydrotreating on heavy oil, particularly poor-quality residual oil, and provides qualified raw oil for subsequent processes (such as catalytic cracking).

Drawings

FIG. 1 is a mercury intrusion pore size distribution plot of a bimodal pore distribution support A1;

FIG. 2 is a mercury intrusion pore size distribution plot of trimodal pore distribution support B2.

Detailed Description

The present invention is further illustrated by the following examples, but the scope of the present invention is not limited to the following examples.

Examples 1-3 illustrate the alumina supports with trimodal pore size distribution and methods for their preparation provided by the present invention.

Example 1

144 g of commercially available pseudoboehmite P1 and 71 g of commercially available pseudoboehmite P2 were weighed, 4.5 g of sesbania powder was added, and mixed uniformly. Adding 250 g dilute nitric acid solution (containing 3.0 g nitric acid), kneading into plastic body, and extruding into clover-type strip with diameter of 1.3 mm on a strip extruder. And drying the wet strip at 120 ℃ for 4 h, and keeping the temperature of the wet strip in a roasting furnace at 900 ℃ for 2 h to obtain the alumina carrier A1.

80 g of alumina carrier A1 was weighed and placed in a hydrothermal kettle. 8 g of deionized water were weighed into a glass cup. Putting the glass cup into a hydrothermal kettle. And (3) sealing the hydrothermal kettle, putting the kettle into an oven, heating to 220 ℃, and carrying out constant-temperature hydrothermal treatment for 6 hours. And drying the sample subjected to the hydrothermal treatment at 120 ℃ for 4 h, and keeping the temperature in a roasting furnace at 500 ℃ for 2 h to obtain the alumina carrier B1 subjected to the hydrothermal treatment. The pore volume and pore size distribution are shown in Table 1.

Example 2

80 g of alumina carrier A1 was weighed and placed in a hydrothermal kettle. 20 g of deionized water were weighed into a glass cup. Putting the glass cup into a hydrothermal kettle. And (3) sealing the hydrothermal kettle, putting the kettle into an oven, heating to 220 ℃, and carrying out constant-temperature hydrothermal treatment for 6 hours. And drying the sample subjected to the hydrothermal treatment at 120 ℃ for 4 h, and keeping the temperature in a roasting furnace at 500 ℃ for 2 h to obtain the alumina carrier B2 subjected to the hydrothermal treatment. The pore volume and pore size distribution are shown in Table 1.

Example 3

80 g of alumina carrier A1 was weighed and placed in a hydrothermal kettle. 40 g of deionized water were weighed into a glass cup. Putting the glass cup into a hydrothermal kettle. And (3) sealing the hydrothermal kettle, putting the kettle into an oven, heating to 220 ℃, and carrying out constant-temperature hydrothermal treatment for 6 hours. And drying the sample subjected to the hydrothermal treatment at 120 ℃ for 4 h, and keeping the temperature in a roasting furnace at 500 ℃ for 2 h to obtain the alumina carrier B3 subjected to the hydrothermal treatment. The pore volume and pore size distribution are shown in Table 1.

Comparative example 1

The alumina carrier a1 prepared in example 1 was not subjected to hydrothermal treatment. The pore volume and pore size distribution are shown in Table 1.

TABLE 1

The results in table 1 and figures 1-2 show that the alumina support prepared by the process of the present invention has a pronounced trimodal pore distribution structure compared to comparative example 1. After hydrothermal treatment, the proportion and the aperture of transition holes between mesopores and macropores are obviously increased, and the continuity of the hole distribution is realized.

Examples 4-6 illustrate catalysts provided by the present invention and methods for their preparation

Example 4

80 g of the support B1 was added to 100 mL of a mixture containing 12.7 g/L NiO and 62.2 g/L MoO₃，8.9 g/L P₂O₅Soaking the catalyst in the Ni-Mo-P solution for 2 hours, drying the catalyst for 2 hours at the temperature of 120 ℃, roasting the catalyst for 0.5 hour at the temperature of 400 ℃, and roasting the catalyst for 2 hours at the temperature of 500 ℃ to obtain the catalyst C1. The nickel oxide and molybdenum oxide contents of catalyst C1 are listed in table 2.

Example 5

80 g of the support B2 was added to 95 mL of a mixture containing 13.4 g/L NiO and 65.5 g/L MoO₃，9.3 g/L P₂O₅Soaking the catalyst in the Ni-Mo-P solution for 2 hours, drying the catalyst for 2 hours at the temperature of 120 ℃, roasting the catalyst for 0.5 hour at the temperature of 400 ℃, and roasting the catalyst for 2 hours at the temperature of 500 ℃ to obtain the catalyst C2.The nickel oxide and molybdenum oxide contents of catalyst C2 are listed in table 2.

Example 6

80 g of the support B3 was added to 97 mL of a mixture containing 13.1 g/L NiO and 64.1 g/L MoO₃，9.2 g/L P₂O₅Soaking the catalyst in the Ni-Mo-P solution for 2 hours, drying the catalyst for 2 hours at the temperature of 120 ℃, roasting the catalyst for 0.5 hour at the temperature of 400 ℃, and roasting the catalyst for 2 hours at the temperature of 500 ℃ to obtain the catalyst C3. The nickel oxide and molybdenum oxide contents of catalyst C3 are listed in table 2.

Comparative example 2

80 g of the carrier A1 was added to 100 mL of a mixture containing 12.7 g/L NiO and 62.2 g/L MoO₃，8.9 g/L P₂O₅Soaking the catalyst in the Ni-Mo-P solution for 2 h, drying at 120 ℃ for 2 h, roasting at 400 ℃ for 0.5 h, and roasting at 500 ℃ for 2 h to obtain the catalyst D1. The nickel oxide and molybdenum oxide contents of catalyst D1 are listed in table 2.

TABLE 2

Example 7 provides a specific embodiment of the resid hydrotreating process of this invention and illustrates the resid hydrodemetallization performance of the catalyst.

Example 7

The catalyst was evaluated on a 100-ml small fixed-bed reactor using a residual oil having a nickel content of 15 ppm, a vanadium content of 50 ppm, a sulfur content of 4.23 wt%, a carbon residue of 10.1 wt%, and a nitrogen content of 2607 ppm as a raw material, and the results are shown in Table 3.

The catalyst loading volume was 100 mL. The process conditions used to evaluate each catalyst were the same. The reaction conditions are as follows: the reaction temperature is 380 ℃, the hydrogen partial pressure is 15 MPa, and the liquid hourly space velocity is 1.0 h^-1The hydrogen/oil volume ratio was 760, and a sample was taken after 200 hours of reaction. And measuring the contents of nickel and vanadium in the oil before and after the hydrotreating by using an inductively coupled plasma emission spectrometer (ICP-AES) (the specific method is shown in RIPP 124-90). The mass fraction of asphaltenes in the oil before and after hydrotreating was analyzed by a petroleum asphalt component determination method (for a specific method, see NB/SH/T0509-2010). The metal and asphaltene removal rates were calculated according to the following formula:

the evaluation results are shown in Table 3.

Comparative example 3

The deasphalted fraction and demetallization rate of catalyst D1 were evaluated by the method of example 7. The results are shown in Table 3.

TABLE 3

The results shown in Table 3 are those after the evaluation reaction was carried out for 200 hours. The comparison shows that the hydrodemetallization activity and the hydrodeasphaltene activity of the hydrodemetallization catalyst provided by the invention are higher than those of a reference catalyst.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.

Claims

1. A three-peak pore distribution hydrodemetallization catalyst is characterized in that: the catalyst has a trimodal pore distribution structure, the pore volume of the catalyst is 0.5-1.3 mL/g, and the specific surface area of the catalyst is 50-200 m²The volume of pores with the diameter of less than 50 nm accounts for 30-50% of the total pore volume, the volume of pores with the diameter of 50-100 nm accounts for 10-30% of the total pore volume, and the volume of pores with the diameter of more than 100 nm accounts for 30-50% of the total pore volume;

the catalyst contains an alumina carrier with trimodal pore distribution and active metal components loaded on the carrier, wherein the active metal components contained in the catalyst are at least one metal component of VIB group and at least one metal component of VIII group, calculated by oxides and based on the catalyst, the content of the metal component oxides of the VIB group is 0.1-15 wt%, and the content of the metal component oxides of the VIII group is 0.1-5 wt%;

the catalyst also contains an auxiliary phosphorus, the content of the oxide of the auxiliary phosphorus is 0-5 wt% calculated by oxide and based on the catalyst.

2. A process for preparing a trimodal pore distribution hydrodemetallization catalyst as claimed in claim 1, characterized in that: the method comprises the following steps:

(1) preparation of bimodal alumina support: mixing and kneading an alumina precursor containing pseudo-boehmite, an extrusion aid and a peptizing agent, molding, drying and roasting;

(2) preparing a trimodal alumina carrier by hydrothermal treatment of a bimodal alumina carrier: carrying out hydrothermal treatment on the prepared bimodal alumina carrier under a closed condition, drying and roasting to obtain a trimodal alumina carrier; the hydrothermal treatment is to separate the bimodal alumina carrier and water and put the bimodal alumina carrier and the water into a closed container of a reaction kettle, heat the bimodal alumina carrier and the water to a certain temperature under a closed condition, and then carry out hydrothermal treatment for a period of time at the temperature;

(3) loading an active metal component on a trimodal alumina carrier: the supporting method is an impregnation method, and comprises preparing a solution of a compound containing an active metal component and impregnating the carrier with the solution, followed by drying, calcination or no calcination to obtain the catalyst.

3. The method of claim 2, wherein: the extrusion aid in the step (1) is one or more of sesbania powder, methyl cellulose, starch and polyvinyl alcohol, and the addition amount of the extrusion aid is 1-5 wt% of alumina; the peptizing agent is inorganic acid aqueous solution or organic acid aqueous solution, and the concentration of the acid solution is 0.05-5 wt%.

4. The method of claim 2, wherein: the molding in the step (1) adopts tabletting, rolling balls or extruding strips; the shape of the carrier is spherical, cylindrical, clover-shaped or clover-shaped; the roasting temperature is 500-1000 ℃, and the roasting time is 1-8 h.

5. The method of claim 2, wherein: the alumina carrier in the step (1) has a bimodal pore distribution structure, and the pore volume of the bimodal alumina carrier is 0.6-1.4 mL/g and the specific surface area is 50-300 m measured by a mercury intrusion method²The volume of pores with the diameter of less than 50 nm accounts for 50-70% of the total pore volume, the volume of pores with the diameter of 50-100 nm accounts for 0-5% of the total pore volume, and the volume of pores with the diameter of more than 100 nm accounts for 30-50% of the total pore volume.

6. The method of claim 2, wherein: the temperature of the hydrothermal treatment in the step (2) is 150-300 ℃, and the time is 1-24 h; the amount of water used in the hydrothermal treatment is 5-200% of the mass of the bimodal alumina carrier; the drying temperature is 80-200 ℃, and the drying time is 1-24 h; the roasting temperature is 400-800 ℃, and the roasting time is 1-8 h.

7. The method of claim 2, wherein: the alumina carrier prepared in the step (2) has a trimodal pore distribution structure, and the pore volume of the trimodal alumina carrier is 0.6-1.4 mL/g and the specific surface area is 50-200 m determined by a mercury intrusion method²The volume of pores with the diameter of less than 50 nm accounts for 30-50% of the total pore volume, the volume of pores with the diameter of 50-100 nm accounts for 10-30% of the total pore volume, and the volume of pores with the diameter of more than 100 nm accounts for 30-50% of the total pore volume.

8. The method of claim 2, wherein: the dipping temperature in the step (3) is 10-60 ℃, and the dipping time is 1-24 h; the drying temperature is 80-200 ℃, and the drying time is 1-24 h; the roasting temperature is 300-600 ℃, and the roasting time is 1-10 h.