A method for preparing modified alumina

Abstract

This invention provides a method for preparing modified alumina, comprising: (1) dissolving an aluminum-containing compound in a solvent, then adding a modifier and stirring evenly, and then adding a pore-expanding agent to obtain a mixed reaction solution; wherein the molar ratio of the pore-expanding agent to the aluminum-containing compound is pore-expanding agent:Al2O3 = 1~20:1; (2) transferring the mixed reaction solution into a hydrothermal reactor and placing it in a homogeneous reactor for aging, heating the aged solution to 120~200℃, and crystallizing at a constant temperature for 12~36h; (3) drying the crystallized product, cooling it to room temperature, and then performing segmented heating calcination to obtain modified alumina. The preparation method of this invention can obtain modified alumina with a single pore size distribution that has high water absorption and high thermal stability.

Description

Technical Field

[0001] This invention belongs to the technical field of inorganic materials, and particularly relates to a method for preparing a modified alumina carrier. Background Technology

[0002] Alumina, as an excellent catalyst support material for hydrogenation, has its pore structure significantly impacting the catalyst's activity, selectivity, and lifetime. Alumina supports with large pore size and volume offer unique advantages in refining applications such as catalytic hydrogenation. The large pore size facilitates mass transfer of reactants, improving reaction efficiency, while suitable surface properties provide ample contact space between reactants and catalyst active sites, promoting rapid diffusion of reaction products and increasing reaction rates. Furthermore, it can accumulate carbon residue, extending catalyst lifetime to some extent.

[0003] However, existing methods for preparing alumina supports mainly have the following problems:

[0004] 1) After modification, the existing alumina has uneven distribution of modifiers in the alumina, resulting in uneven pore size after high-temperature calcination, which ultimately affects the activity and selectivity of the catalyst.

[0005] 2) After high-temperature calcination, the specific surface area and pore size and pore volume of alumina decrease, which leads to a reduction in the dispersion and loading of the active phase. As a result, the catalyst activity is limited, thus restricting its widespread application.

[0006] 3) Although high-temperature calcination can improve the stability of alumina, excessively high calcination temperatures (≥1000℃) will lead to a sharp decrease in surface hydroxyl groups, thereby reducing the dispersion and anchoring effect of hydroxyl groups on the active phase. This will cause the active phase to migrate and sinter during long-term operation of the prepared supported catalyst, ultimately affecting the stability of the catalyst. Summary of the Invention

[0007] To overcome the problems existing in the prior art, the present invention provides a method for preparing modified alumina. By mixing the modifier and alumina more uniformly under high temperature and high pressure hydrothermal conditions, a modified alumina with high water absorption and high thermal stability and a single pore size distribution is prepared.

[0008] To achieve the objectives of this invention, the following technical solution is adopted:

[0009] This invention provides a method for preparing modified alumina, comprising the following steps:

[0010] (1) After dissolving the aluminum-containing compound in a solvent, a modifier is added and stirred evenly. Then, a pore-expanding agent is added to obtain a mixed reaction solution.

[0011] Wherein, the molar ratio of the pore-expanding agent to the aluminum-containing compound is pore-expanding agent:Al2O3 = 1 to 20:1;

[0012] (2) The mixed reaction solution is transferred into a hydrothermal reactor and placed in a homogeneous reactor for aging. The aged solution is heated to 120-200°C and crystallized at a constant temperature for 12-36 hours.

[0013] (3) The product obtained by the crystallization treatment is dried, cooled to room temperature and then subjected to segmented heating and calcination to obtain modified alumina.

[0014] The segmented heating and calcination refers to heating from room temperature to 600-700℃ at a heating rate of 0.5-5℃ / min and calcining for 0.5-3h; then, heating to 1100-1150℃ at a heating rate of 2-10℃ / min and calcining for 0.5-3h.

[0015] In a preferred embodiment of the preparation method of the present invention, in step (1), the mass ratio of the modifier to the aluminum-containing compound is SiO2:Al2O3 = 0.01 to 0.12:1, for example, 0.05:1, 0.08:1, 0.10:1, or 0.11:1. In the preparation method of the present invention, the ratio of the modifier to the aluminum-containing compound is usually calculated in the form of the oxide of its main substance.

[0016] In some preferred embodiments, the pore expander and the aluminum-containing compound are mixed in the following molar ratio: Al2O3 = 2 to 10:1, for example, 3:1, 5:1, 8:1.

[0017] In some specific embodiments, the aluminum-containing compound is selected from one or more of alumina, aluminum oxalate, aluminum acetate, aluminum stearate, aluminum propoxide, aluminum laurate, aluminum ammonium carbonate, aluminum sulfate, aluminum ammonium sulfate, aluminum carbonate, aluminum isopropoxide, aluminum nitrate, or aluminum ammonium nitrate; wherein, alumina can be selected from various crystal forms of alumina; preferably selected from aluminum nitrate (generally selected from aluminum nitrate nonahydrate), aluminum carbonate, or aluminum isopropoxide.

[0018] In some specific embodiments, the modifier may be selected from one or more of silica sol, tetraethyl orthosilicate, or silicates; preferably silica sol or tetraethyl orthosilicate.

[0019] In some specific embodiments, the pore-expanding agent may be selected from one or more of cellulose, ammonium carbonate, ammonium bicarbonate, sawdust, activated carbon, or carbon black; preferably activated carbon, carbon black, ammonium carbonate, or ammonium bicarbonate.

[0020] In step (1) of the preparation method of the present invention, the solvent can be water, or a mixed solvent composed of an organic solvent and water; when a mixed solvent is selected, the mass ratio of the organic solvent to water is preferably 0.05 to 0.8:1, for example, 0.1:1, 0.4:1, or 0.7:1. In some specific embodiments, the organic solvent is selected from one or more of polyethylene glycol, isopropanol, propylene glycol, polyethylene oxide, ethanol, cellulose methyl ether, polyvinyl alcohol, or polyacrylamide.

[0021] In step (2) of the preparation method of the present invention, the mixed reaction liquid is transferred into a hydrothermal reactor and placed in a homogeneous reactor for aging. Specifically, the aging process is carried out at a rotation speed of 5 to 20 rpm for 8 to 24 hours.

[0022] In step (2) of the preparation method of the present invention, the aged solution is heated to 120-200°C. When the temperature and pressure exceed a certain level, the solubility of the solvent can be greatly improved, which promotes the migration of the solute in the solution, making the modifier and aluminum-containing compound mix more uniformly, and a uniformly doped alumina carrier can be obtained. In some preferred embodiments, the temperature is increased to 120-200°C at a rate of 0.5-4°C / min, for example, at a rate of 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min, and then increased to 150°C, 170°C, and 180°C.

[0023] In step (3) of the method of the present invention, the product obtained by crystallization treatment is dried at 80-120°C, for example, 100°C or 120°C; and the dried product is cooled to room temperature, and then subjected to segmented heating and calcination; specifically, the temperature is first raised from room temperature to 600-700°C at a heating rate of 0.5-5°C / min, and calcined for 0.5-3 hours; then, the temperature is further raised to 1100-1150°C at a heating rate of 2-10°C / min, and calcined for 0.5-3 hours. In the above segmented high-temperature calcination process, it is beneficial to uniformly distribute the modifier and reduce the probability of surface defects of alumina during the heating and calcination stage.

[0024] After the high-temperature calcination of the present invention, the pore size distribution of the alumina is uniform. The silicon-doped alumina prepared at a calcination temperature of up to 1100°C still contains more hydroxyl groups. At the same time, during the calcination process, the volatilized ammonia and CO2 play a role in expanding the pores, which can increase the pore size and pore volume of the alumina.

[0025] The above technical solution achieves the following technical effects:

[0026] The modified alumina preparation method provided by this invention prepares alumina through silicon doping. It involves crystallization at a specific temperature (120-200℃) followed by segmented calcination to obtain modified alumina, which increases the pore size and pore volume of the modified alumina and results in a uniform pore size distribution. At the same time, after high-temperature calcination, the surface of the alumina is still rich in more hydroxyl groups, which significantly improves the dispersibility, stability, and loading of the supported active phase during application, enhances the diffusion of reactants and products, and increases the activity of the final catalyst. Detailed Implementation

[0027] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0029] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in this technical field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0030] The following examples demonstrate the use of the following methods to test the properties of alumina:

[0031] (1) Most probable pore size and specific surface area: BET test was used;

[0032] (2) Water absorption rate: The conventional gravimetric method was used for testing. A certain amount of alumina carrier was weighed, and its mass and the total mass of the container after loading the carrier were recorded. Deionized water was added drop by drop, and the mixture was stirred continuously with a glass rod to ensure uniform water absorption until the impregnation was complete and the surface of the carrier was wet and sandy. The total mass of the container at this point was weighed, and the water absorption of a certain mass of carrier was calculated. This water absorption was divided by the mass of the carrier to obtain the water absorption rate of the carrier.

[0033] Example 1

[0034] (1) Weigh 200g of deionized water and 36.2g of isopropanol and mix them together, stirring for 10-120 minutes;

[0035] Add 375.13g of aluminum nitrate nonahydrate to the above mixed solvent, continue stirring for 10-120min to dissolve, then add 8.84g of tetraethyl orthosilicate and stir for 10-120min, then add 400g of ammonium bicarbonate to obtain a mixed reaction solution;

[0036] (2) Transfer the above mixed reaction solution into a 500ml hydrothermal reactor, place it in a homogeneous reactor, set the rotation speed of the homogeneous reactor to 20rpm, age for 24h, and then raise the temperature of the aged solution to 120℃ at a rate of 1℃ / min, and crystallize at a constant temperature for 24h.

[0037] (3) The crystallized product was dried at 120℃ and cooled to room temperature before being calcined in the following segmented manner: first, the temperature was raised to 700℃ at a rate of 2.5℃ / min and then calcined for 2h; then, the temperature was raised to 1100℃ at a rate of 3℃ / min and calcined for 2h to obtain modified alumina, which was denoted as sample A1.

[0038] Example 2

[0039] (1) Add 204.24g of aluminum isopropoxide to 300g of deionized water and stir for 10-120min to dissolve; then add 21.22g of tetraethyl orthosilicate and stir for 10-120min, and then add 200g of ammonium carbonate to obtain a mixed reaction solution.

[0040] (2) Transfer the above mixed reaction solution into a 500ml hydrothermal reactor and place it in a homogeneous reactor. Set the rotation speed of the homogeneous reactor to 20rpm and age for 24h. Then raise the temperature of the aged solution to 150℃ at a rate of 1℃ / min and crystallize it at a constant temperature for 24h.

[0041] (3) After the crystallization product is dried at 120℃, it is cooled to room temperature and then subjected to the following segmented heating and calcination: first, the temperature is raised to 700℃ at a heating rate of 2.5℃ / min and then calcined for 2h; then, the temperature is raised to 1100℃ at a rate of 3℃ / min and calcined for 2h to obtain modified alumina, which is denoted as sample A2.

[0042] Example 3

[0043] (1) Weigh 250g of deionized water and 100g of ethanol, mix them, and stir for 10-120 minutes;

[0044] Add 133.34g of aluminum chloride to the above mixed solvent, continue stirring for 10-120min to dissolve, then add 8.84g of tetraethyl orthosilicate and stir for 10-120min, then add 400g of ammonium bicarbonate to obtain a mixed reaction solution;

[0045] (2) Transfer the above mixed reaction solution into a 500ml hydrothermal reactor and place it in a homogeneous reactor. Set the rotation speed of the homogeneous reactor to 20rpm and age for 24h. Then raise the temperature of the aged solution to 170℃ at a rate of 1℃ / min and crystallize it at a constant temperature for 24h.

[0046] (3) After the crystallization product is dried at 120℃, it is cooled to room temperature and then subjected to the following segmented heating and calcination: first, the temperature is raised to 700℃ at a heating rate of 2.5℃ / min and then calcined for 2h; then, the temperature is raised to 1100℃ at a rate of 3℃ / min and calcined for 2h to obtain modified alumina, which is denoted as sample A3.

[0047] Example 4

[0048] (1) Weigh 150g of deionized water and 50g of ethanol, mix them, and stir for 10-120 minutes;

[0049] Add 375.13g of aluminum nitrate nonahydrate to the above mixed solvent, continue stirring for 10-120min to dissolve, then add 1.77g of tetraethyl orthosilicate and stir for 10-120min, then add 400g of ammonium bicarbonate to obtain a mixed reaction solution;

[0050] (2) Transfer the above mixed reaction solution into a 500ml hydrothermal reactor and place it in a homogeneous reactor. Set the rotation speed of the homogeneous reactor to 15rpm and age for 12h. Then raise the temperature of the aged solution to 200℃ at a rate of 1℃ / min and crystallize it at a constant temperature for 30h.

[0051] (3) After the crystallization product is dried at 100℃, it is cooled to room temperature and then subjected to the following segmented heating and calcination: first, the temperature is raised to 700℃ at a heating rate of 2.5℃ / min and then calcined for 2h; then, the temperature is raised to 1100℃ at a rate of 3℃ / min and calcined for 2h to obtain modified alumina, which is denoted as sample A4.

[0052] Example 5

[0053] (1) Weigh 200g of deionized water and 15g of ethanol, mix them, and stir for 10-120 minutes;

[0054] Add 150g of aluminum nitrate nonahydrate to the above mixed solvent, continue stirring for 10-120min to dissolve, then add 3.524g of tetraethyl orthosilicate and stir for 10-120min, then add 320g of ammonium bicarbonate to obtain a mixed reaction solution;

[0055] (2) Transfer the above mixed reaction solution into a 500ml hydrothermal reactor and place it in a homogeneous reactor. Set the rotation speed of the homogeneous reactor to 10rpm and age for 20h. Then raise the temperature of the aged solution to 150℃ at a rate of 1℃ / min and crystallize it at a constant temperature for 24h.

[0056] (3) After the crystallization product is dried at 100℃, it is cooled to room temperature and then subjected to the following segmented heating and calcination: first, the temperature is raised to 700℃ at a heating rate of 2.5℃ / min and then calcined for 2h; then, the temperature is raised to 1100℃ at a rate of 3℃ / min and calcined for 2h to obtain modified alumina, which is denoted as sample A5.

[0057] Example 6

[0058] (1) Weigh 250g of deionized water and 50g of ethanol, mix them, and stir for 10-120 minutes;

[0059] Add 375.13g of aluminum nitrate nonahydrate to the above mixed solvent, continue stirring for 10-120min to dissolve, then add 8.84g of tetraethyl orthosilicate and stir for 10-120min, then add 320g of ammonium bicarbonate to obtain a mixed reaction solution;

[0060] (2) Transfer the above mixed reaction solution into a 500ml hydrothermal reactor and place it in a homogeneous reactor. Set the rotation speed of the homogeneous reactor to 15rpm and age for 16h. Then, raise the temperature of the aged solution to 150℃ at a rate of 1℃ / min and crystallize it at a constant temperature for 20h.

[0061] (3) After the crystallization product is dried at 90℃, it is cooled to room temperature and then subjected to the following segmented heating and calcination: first, the temperature is raised to 700℃ at a heating rate of 2.5℃ / min and then calcined for 2h; then, the temperature is raised to 1100℃ at a rate of 3℃ / min and calcined for 2h to obtain modified alumina, which is denoted as sample A6.

[0062] Comparative Example 1

[0063] (1) Weigh 200g of deionized water and 20g of isopropanol, mix them, and stir for 10-120 minutes;

[0064] Add 375.13g of aluminum nitrate nonahydrate to the above mixed solvent, continue stirring for 10-120 minutes to dissolve, and then add 400g of ammonium bicarbonate to obtain a mixed reaction solution;

[0065] (2) Transfer the above mixed reaction solution into a 500ml hydrothermal reactor, place it in a homogeneous reactor, set the rotation speed of the homogeneous reactor to 20rpm, age for 24h, and then raise the temperature of the aged solution to 140℃ at a rate of 1℃ / min, and crystallize at a constant temperature for 24h.

[0066] (3) The crystallized product was dried at 120°C and cooled to room temperature before being calcined in the following segmented manner: first, the temperature was raised to 700°C at a rate of 2.5°C / min and then calcined for 2 hours; then, the temperature was raised to 1100°C at a rate of 3°C / min and calcined for 2 hours to obtain modified alumina, which was denoted as sample C1.

[0067] Comparative Example 2

[0068] (1) Weigh 250g of deionized water and 50g of ethanol, mix them, and stir for 10-120 minutes;

[0069] Add 375.13g of aluminum nitrate nonahydrate to the above mixed solvent, continue stirring for 10-120min to dissolve, then add 8.84g of tetraethyl orthosilicate and stir for 10-120min, then add 320g of ammonium bicarbonate to obtain a mixed reaction solution;

[0070] (2) Transfer the above mixed reaction solution into a 500ml hydrothermal reactor and place it in a homogeneous reactor. Set the rotation speed of the homogeneous reactor to 15rpm and age for 16h. Then raise the temperature of the aged solution to 110℃ at a rate of 1℃ / min and crystallize it at a constant temperature for 20h.

[0071] (3) After the crystallization product is dried at 90℃, it is cooled to room temperature and then subjected to the following segmented heating and calcination: first, the temperature is raised to 700℃ at a heating rate of 2.5℃ / min and then calcined for 2h; then, the temperature is raised to 1100℃ at a rate of 3℃ / min and calcined for 2h to obtain modified alumina, which is denoted as sample C2.

[0072] Comparative Example 3

[0073] (1) Weigh 200g of deionized water and 30g of isopropanol, mix them, and stir for 10-120 minutes;

[0074] Add 375.13g of aluminum nitrate nonahydrate to the above mixed solvent, continue stirring for 10-120min to dissolve, then add 8.84g of tetraethyl orthosilicate and stir for 10-120min, then add 35.5g of ammonium bicarbonate to obtain a mixed reaction solution;

[0075] (2) Transfer the above mixed reaction solution into a 500ml hydrothermal reactor and place it in a homogeneous reactor. Set the rotation speed of the homogeneous reactor to 15rpm and age for 12h. Then raise the temperature of the aged solution to 200℃ at a rate of 1℃ / min and crystallize it at a constant temperature for 30h.

[0076] (3) After the crystallization product is dried at 100℃, it is cooled to room temperature and then subjected to the following segmented heating and calcination: first, the temperature is raised to 700℃ at a heating rate of 2.5℃ / min and then calcined for 2h; then, the temperature is raised to 1100℃ at a rate of 3℃ / min and calcined for 2h to obtain modified alumina, which is denoted as sample C3.

[0077] Comparative Example 4

[0078] Alumina was prepared using the method described in the literature "Supported Iron Fischer Tropsch Catalyst: Superior Activity and Stability Using a Thermally Stable Silica-Doped Alumina Support".

[0079] (1) Add water to aluminum isopropoxide at a molar ratio of 5:1 and mix briefly; then add a small amount of additional water (molar ratio of 1:2) to tetraethyl orthosilicate, enough to bring the silica content in the final carrier material to 5 wt%.

[0080] (2) The resulting mixture was stirred in a Bosch mixer for 30 minutes and then heat-treated in air at 700°C for 2 hours at a heating rate of about 2.5°C / min to form γ-alumina; then, the product was cooled to room temperature, heated to 1100°C over 5 hours and held at 1100°C for 2 hours to obtain modified alumina, denoted as sample C4.

[0081] The modified alumina obtained above was subjected to performance testing, and the results are shown in Table 1 below:

[0082] Table 1

[0083] A1 115 17 4.1 A2 130 19 4.4 A3 125 19 4.8 A4 102 17 3.9 A5 134 19 4.5 A6 118 17 4.4 C1 35 10 0.8 C2 98 15 1.7 C3 60 17 2.1 C4 140 12 / 70 1.2

[0084] The above-obtained samples were used to prepare supported catalysts according to the following method: a certain amount of ferric ammonium citrate was weighed and dissolved in a certain amount of deionized water (the amount of water was calculated based on the water absorption rate of the support used), and stirred until fully dissolved to obtain a precursor solution; then, samples A1-A6 and C1-C4 of the same mass were weighed and placed in crucibles, and the precursor solution was transferred dropwise with a dropper for impregnation, and the mixture was stirred continuously with a glass rod to ensure uniform impregnation.

[0085] After impregnation, the samples were aged at room temperature for 12 hours. The resulting samples were then dried in a 120°C drying oven for 12 hours, followed by calcination in a muffle furnace. The calcination conditions were: heating to 500°C at 5°C / min in air atmosphere, holding for 2 hours, and then naturally cooling to room temperature. The following supported catalysts with theoretical iron phase loadings (referred to as A10-A60 and C10-C40 respectively) were obtained sequentially: 43.27%, 45.01%, 47.17%, 42.05%, 45.57%, 46.12%, 12.96%, 26.19%, 28.09%, and 18.05%.

[0086] The supported catalyst obtained above was used for Fischer-Tropsch synthesis in a fixed-bed microreactor under the following conditions: First, the prepared supported catalyst was reduced at 400℃ under a 100% H2 atmosphere for 10 h; then, the temperature was lowered to 340℃, and a mixture of H2 and CO was introduced for carbonization for 1.5 h; finally, the reaction was carried out at a reaction temperature of 300℃ and a space velocity of 30000 ml / g. cat Under conditions of 1.5 MPa / h and a reaction ratio of H2 to CO of 1.5, after 240 hours of operation, the CO conversion rate of samples A10-A60 remained almost unchanged throughout the entire test, while the CO conversion rate of the control samples C10-C40 decreased by at least 15% (the difference between the initial conversion rate and the conversion rate after 240 hours of operation). Evaluation data are shown in Table 2 below.

[0087] Table 2

[0088] A10 87.9 12.5 29.8 A20 90.5 11.9 31.3 A30 91.2 11.2 32.7 A40 87.1 13.2 29.1 A50 89.8 12.3 30.1 A60 90.9 11.6 31.8 C10 62.1 22.9 21.2 C20 78.1 18.7 24.9 C30 78.9 16.4 25.7 C40 72.6 21.4 23.9

[0089] As can be seen from the data in Table 1 above, the modified alumina prepared by the method provided in this invention can achieve a specific surface area of ​​134 m². 2 / g, the modified alumina has a single pore size of up to 19nm and a water absorption rate as high as 4.8g / g; at the same time, from the pore size distribution data of Comparative Example 4, due to the non-uniformity of the modifier distribution, the resulting alumina has a dual pore size distribution (12nm and 70nm), of which the larger most probable pore size (70nm) is a particle packing pore, and the larger pore size results in a higher specific surface area.

[0090] As can be seen from the evaluation results (Table 2), the modified alumina prepared by the method of the present invention significantly improves the stability and loading of the supported active phase, enhances the diffusion of reactants and products, thereby increasing the activity of the final catalyst in the reaction process, improving the conversion rate of raw materials, reducing the selectivity of methane, and improving the operational stability of the catalyst.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for preparing modified alumina, characterized in that, Includes the following steps: (1) After dissolving the aluminum-containing compound in a solvent, a modifier is added and stirred evenly. Then, a pore-expanding agent is added to obtain a mixed reaction solution. Wherein, the molar ratio of the pore-expanding agent to the aluminum-containing compound is pore-expanding agent: Al2O3 = 5~20:1; (2) The mixed reaction solution is transferred into a hydrothermal reactor and placed in a homogeneous reactor for aging. The aged solution is heated to 120~200℃ and crystallized at a constant temperature for 12~36 h. (3) The product obtained by the crystallization treatment is dried, cooled to room temperature and then subjected to segmented heating and calcination to obtain modified alumina; The segmented heating and calcination refers to heating from room temperature to 600-700℃ at a heating rate of 0.5-5℃ / min and calcining for 0.5-3 h; then, heating to 1100-1150℃ at a heating rate of 2-10℃ / min and calcining for 0.5-3 h. The modifier is selected from one or more of silica sol, tetraethyl orthosilicate, or silicates.

2. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of the modifier to the aluminum-containing compound is SiO2:Al2O3 = 0.01~0.12:

1.

3. The preparation method according to claim 2, characterized in that, The pore-expanding agent and the aluminum-containing compound are mixed in the following molar ratio: Al2O3 = 5~10:

1.

4. The preparation method according to claim 3, characterized in that, The aluminum-containing compound is selected from one or more of aluminum isopropoxide, aluminum sulfate, and aluminum nitrate.

5. The preparation method according to claim 4, characterized in that, The aluminum-containing compound is selected from aluminum nitrate and aluminum isopropoxide.

6. The preparation method according to claim 4, characterized in that, The modifier is selected from silica sol and tetraethyl orthosilicate; the pore-expanding agent is selected from one or more of cellulose, ammonium carbonate, ammonium bicarbonate, sawdust, activated carbon, or carbon black.

7. The preparation method according to claim 6, characterized in that, The pore-expanding agent is selected from activated carbon, carbon black, ammonium carbonate, and ammonium bicarbonate.

8. The preparation method according to claim 6, characterized in that, The solvent is water or a mixture of an organic solvent and water.

9. The preparation method according to claim 8, characterized in that, In the mixed solvent, the mass ratio of the organic solvent to water is 0.05~0.8:

1.

10. The preparation method according to claim 8, characterized in that, The organic solvent is selected from one or more of polyethylene glycol, isopropanol, propylene glycol, polyethylene oxide, ethanol, cellulose methyl ether, polyvinyl alcohol, or polyacrylamide.

11. The preparation method according to any one of claims 1 to 10, characterized in that, In step (2), the homogeneous reactor is aged for 8 to 24 hours at a rotation speed of 5 to 20 rpm.

12. The preparation method according to claim 11, characterized in that, The aged solution is heated to 120~200℃.

13. The preparation method according to claim 12, characterized in that, The temperature is increased at a rate of 0.5~4℃ / min.

14. The preparation method according to any one of claims 1 to 10, 12, and 13, characterized in that, In step (3), the drying process is carried out at 80~120℃.