Preparation method of macroporous high-hydrothermal-stability aluminum oxide and pseudo-boehmite

Abstract

The invention provides a preparation method of macroporous high-hydrothermal-stability aluminum oxide and pseudo-boehmite, and the preparation method of the pseudo-boehmite comprises the following steps: step 1, adding an aluminum salt solution and an alkali solution into a rotating liquid membrane reactor at the same time, and nucleating at 20-30 DEG C to obtain nucleating slurry; wherein the rotating speed of the rotating liquid film reactor is 500 to 1200 rpm, and the stator-rotor gap of the rotating liquid film reactor is 0.1 to 0.3 mm; and step 2, transferring the nucleation slurry into a crystallization reaction device, crystallizing at 70-90 DEG C, and then carrying out solid-liquid separation and drying to obtain the pseudo-boehmite. The most probable pore size of the aluminum oxide prepared by the method is 6-12nm, the specific surface area is 150-600m < 2 > / g, and the aluminum oxide can still keep higher specific surface area after being subjected to hydrothermal treatment for 120 hours.

Description

Technical Field

[0001] The present invention belongs to the field of catalyst materials, and particularly relates to a method for preparing macroporous alumina with high hydrothermal stability and pseudoboehmite. This method is suitable for large-scale production. The alumina is mainly used as a catalyst support and a catalyst. Background Art

[0002] Aluminum oxide (Al 2 O 3 ) has good chemical stability, high temperature resistance, wear resistance, high thermal conductivity, high insulation and low dielectric loss, etc., and is widely used in the fields of chemical engineering, electronics and electrical appliances, and aerospace. Preparing a catalyst support that can meet the application requirements faces many problems in the production process, such as the spherical morphology of Al 2 O 3 is difficult to control, the particle size distribution is wide, the hydrothermal stability is insufficient, the mechanical strength is not enough, the production process is complex, time-consuming and costly.

[0003] As a precursor for preparing spherical alumina, the properties of pseudoboehmite will greatly affect the properties of the prepared spherical alumina.

[0004] At present, the domestic methods for synthesizing pseudoboehmite mainly focus on the co-precipitation method.

[0005] US4313923 reported a method for preparing pseudoboehmite by slowly dropping a sodium aluminate solution into an aluminum sulfate solution, which includes a long aging time (20 - 60h).

[0006] The literature "J.Colloid Interface Sci.,2016,469:1 - 7" uses a simple co-precipitation method, including using sodium aluminate and aluminum sulfate as raw materials, and adjusting different pH values to change the morphology and structure of the prepared pseudoboehmite.

[0007] The literature "Chin.J.Catal.,2003,24,505 - 508" uses sodium aluminate and ammonium bicarbonate to prepare high-purity pseudoboehmite by co-precipitation method, and its impurity content reaches the low standard of SB powder.

[0008] CN103172097A reported a method for preparing pseudoboehmite with a large specific surface area by using the nucleation crystallization isolation method, which includes nucleation at 50 - 120°C and crystallization at 80 - 120°C.

[0009] The above patents and literatures all focus on controlling the properties of pseudoboehmite such as morphology and purity, and there is little research on the pore size and crystal plane structure of pseudoboehmite, and the optimization of the pore structure and the improvement of the hydrothermal stability of spherical alumina are insufficient.

[0010] The nucleation and crystallization processes can greatly affect the formation of the crystal structure of pseudo-boehmite. In the prior art, relevant patents and literature on the preparation of pseudo-boehmite using the nucleation crystallization isolation method do not consider the crystal plane field. At the same time, both the nucleation and crystallization processes in CN103172097A are carried out at high temperatures. High temperatures can lead to an increase in the chemical reaction rate, which is not conducive to the formation of a special crystal plane structure.

[0011] The properties of the precursor pseudo-boehmite are crucial for the performance of the alumina support. Developing a precursor pseudo-boehmite with excellent properties is very crucial for improving the hydrothermal stability of the corresponding alumina support. Summary of the Invention

[0012] The main object of the present invention is to provide a method for preparing macroporous alumina with high hydrothermal stability and pseudo-boehmite, so as to overcome the defects such as small specific surface area and poor hydrothermal stability of alumina in the prior art.

[0013] To achieve the above object, the present invention provides a method for preparing pseudo-boehmite, which includes the following steps:

[0014] Step 1, simultaneously adding an aluminum salt solution and an alkali solution into a rotating liquid film reactor, and nucleating at 20 - 30 °C to obtain a nucleation slurry; wherein, the rotation speed of the rotating liquid film reactor is 500 - 1200 rpm, and the stator-rotor gap of the rotating liquid film reactor is 0.1 - 0.3 mm;

[0015] Step 2, transferring the nucleation slurry to a crystallization reaction device, carrying out crystallization at 70 - 90 °C, then performing solid-liquid separation and drying to obtain pseudo-boehmite.

[0016] In the method for preparing pseudo-boehmite according to the present invention, the rotation speed of the rotating liquid film reactor is 500 - 1000 rpm.

[0017] In the method for preparing pseudo-boehmite according to the present invention, the stator-rotor gap of the rotating liquid film reactor is 0.1 - 0.2 mm.

[0018] In the method for preparing pseudo-boehmite according to the present invention, the aluminum salt solution is an aqueous solution of at least one of aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum acetate, and the corresponding hydrates of these substances.

[0019] In the method for preparing pseudo-boehmite according to the present invention, the alkali solution is an aqueous solution of at least one of sodium hydroxide, sodium carbonate, sodium acetate, sodium meta-aluminate, urea, hexamethylenetetramine, and ammonia water.

[0020] The preparation method of pseudo-boehmite according to the present invention, wherein the molar concentration of the aluminum salt solution is 0.01 mol / L - 0.03 mol / L; the molar concentration of the alkali solution is 0.03 mol / L - 0.18 mol / L; the aluminum salt solution is calculated by aluminum, the alkali solution is calculated by hydroxide ions, and the molar ratio of the aluminum salt solution to the alkali solution is 1:3 - 7.

[0021] The preparation method of pseudo-boehmite according to the present invention, wherein in step 1, the aluminum salt solution and the alkali solution are added to the rotating liquid film reactor at the same speed.

[0022] The preparation method of pseudo-boehmite according to the present invention, wherein in step 2, the crystallization time is 1 - 5 hours.

[0023] The preparation method of pseudo-boehmite according to the present invention, wherein in step 2, the drying temperature is 60 - 90 °C and the drying time is 2 - 12 hours.

[0024] In order to achieve the above object, the present invention also provides a preparation method of macroporous high hydrothermal stability alumina, comprising the following steps: subjecting the pseudo-boehmite obtained by the above preparation method to oil-ammonia column forming, drying and calcining to obtain macroporous high hydrothermal stability alumina.

[0025] The beneficial effects of the present invention:

[0026] The present invention discloses a preparation method of macroporous high hydrothermal stability alumina and pseudo-boehmite. By using a rotating liquid film reactor, at a low nucleation temperature, a shear force of 500 - 1200 rpm, and a specific stator-rotor gap, the formation of pseudo-boehmite crystal nuclei with a specific crystal plane orientation is promoted, and then pseudo-boehmite with crystal plane selectivity is prepared through aging. In the process of converting pseudo-boehmite into alumina, there is a corresponding relationship between the crystal planes of pseudo-boehmite and alumina. Subjecting the pseudo-boehmite with crystal plane selectivity to oil-ammonia column forming, drying and calcining to obtain alumina with exposed high hydrothermal stability crystal planes, thereby showing excellent hydrothermal stability. The most probable pore diameter of the alumina prepared by the method of the present invention is 6 - 12 nm, the specific surface area is 150 - 600 m 2 / g, and it can still maintain a high specific surface area after 120 h of hydrothermal treatment. In addition, the method of the present invention does not require the use of expensive equipment, and the chemicals used are aluminum salts and alkalis, which has the advantages of simple operation, low cost, and easy large-scale production. Description of the Drawings

[0027] Figure 1 XRD pattern of the pseudo-boehmite prepared in Example 1.

[0028] Figure 2 XRD pattern of the macroporous high hydrothermal stability alumina prepared in Example 1.

[0029] Figure 3 SEM photograph of the macroporous high hydrothermal stability alumina prepared in Example 1.

[0030] Figure 4 BET characterization diagram of the hydrothermal treatment process of the macroporous high hydrothermal stability alumina prepared in Example 1.

[0031] Figure 5 SEM photograph of the alumina prepared in Comparative Example 1.

[0032] Figure 6 BET characterization diagram of the hydrothermal treatment process of the alumina prepared in Comparative Example 1. Detailed implementation manners

[0033] The technical solutions of the present invention will be described in detail below. The following implementation manners are carried out on the premise of the technical solutions of the present invention, and the detailed implementation processes are given. However, the protection scope of the present invention is not limited to the following implementation manners. For the structures or experimental methods without specific conditions noted in the following implementation manners, they are usually in accordance with conventional conditions.

[0034] The present invention provides a method for preparing a macroporous high hydrothermal stability spherical alumina precursor boehmite, which includes the following steps:

[0035] Step 1: Simultaneously add an aluminum salt solution and an alkali solution into a rotating liquid film reactor, and nucleate at 20 - 30°C to obtain a nucleation slurry; wherein, the rotation speed of the rotating liquid film reactor is 500 - 1200 rpm, and the stator-rotor gap of the rotating liquid film reactor is 0.1 - 0.3 mm;

[0036] Step 2: Transfer the nucleation slurry to a crystallization reaction device, carry out crystallization at 70 - 90°C, then perform solid-liquid separation and drying to obtain boehmite.

[0037] In the preparation of the boehmite of the present invention, the nucleation process and the crystallization process are separated. At room temperature, by controlling the rotation speed and the stator-rotor gap of the rotating liquid film reactor during the nucleation process, boehmite with different crystal plane selective growth is grown, so that the prepared alumina has a relatively high specific surface area, a relatively large pore diameter, and can still maintain a relatively high specific surface area after 120 h of hydrothermal treatment.

[0038] In one implementation manner, the aluminum salt solution is an aqueous solution of at least one of aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum acetate or the corresponding hydrates of these substances. The corresponding hydrates of these substances are aluminum nitrate, aluminum sulfate, aluminum chloride, and aluminum acetate hydrates. The molar concentration of the aluminum salt solution is 0.01 mol / L - 0.03 mol / L.

[0039] In one embodiment, the alkali solution is an aqueous solution of at least one of sodium hydroxide, sodium carbonate, sodium acetate, sodium aluminate, urea, hexamethylenetetramine or ammonia water, and the molar concentration of the alkali solution is 0.06 mol / L - 0.18 mol / L. In another embodiment, based on aluminum in the aluminum salt solution and based on hydroxide ions in the alkali solution, the molar ratio of the aluminum salt solution to the alkali solution is 1:4 - 7, for example, the molar ratio is 1:6.

[0040] The present invention does not particularly limit the structure of the rotating liquid film reactor, and a commonly used rotating liquid film reactor in the art can be used. During the nucleation process of boehmite in the present invention, the rotation speed of the rotating liquid film reactor is 500 - 1200 rpm, preferably 500 - 1000 rpm, such as 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm. The stator-rotor gap of the rotating liquid film reactor is 0.1 - 0.3 mm, preferably 0.1 - 0.2 mm, such as 0.1 mm, 0.2 mm, 0.3 mm. The nucleation process of the present invention is carried out at room temperature. At the same time, by limiting the rotation speed and the stator-rotor gap of the rotating liquid film reactor, boehmite with different crystal plane orientations can be grown, so that the prepared alumina can have a larger pore diameter, a larger specific surface area and stable hydrothermal stability.

[0041] In one embodiment, the speeds of adding the aluminum salt solution and the alkali solution to the rotating liquid film reactor in the present invention are the same.

[0042] Then, transfer the nucleation slurry to a crystallization reaction device, carry out crystallization at 70 - 90 °C, and then perform solid-liquid separation and drying to obtain boehmite.

[0043] The crystallization process of the present invention is carried out at a low temperature, which can prevent the growth rate of crystal planes from being too fast due to high temperature.

[0044] The present invention does not particularly limit the crystallization reaction device, and a commonly used crystallization reaction device in the art can be used.

[0045] In one embodiment, the crystallization time is 1 - 5 hours, for example 2 hours. After the crystallization is completed, the crystallization product is naturally cooled to room temperature, and then solid-liquid separation is carried out. The present invention does not particularly limit the method of solid-liquid separation, such as filtration, centrifugation, etc. Then wash the filter cake with water until it is neutral, and dry it to obtain boehmite. The present invention does not particularly limit the drying temperature, preferably 70 - 90 °C, and the drying time is 2 - 12 hours.

[0046] The boehmite prepared by the present invention is irregular particles, which form a large number of macropores when stacked, and can be used to prepare macroporous alumina.

[0047] In one embodiment, the present invention provides the above method for preparing alumina from pseudo-boehmite, that is, the macroporous high hydrothermal stability pseudo-boehmite obtained by the above preparation method is formed into columns by oil-ammonia method, dried and calcined to obtain macroporous high hydrothermal stability alumina.

[0048] The present invention does not particularly limit the oil-ammonia column forming method, and it can be carried out in a conventional manner in the art. After forming, it is washed, dried and calcined to obtain macroporous high hydrothermal stability alumina, and its chemical formula is γ-Al 2 O 3 . In one embodiment, the drying temperature is 100-120 °C and the calcination temperature is 450-650 °C.

[0049] The alumina prepared by the method of the present invention has special crystal planes, and is spherical alumina, and exhibits excellent hydrothermal stability, which is beneficial to its use as a catalyst or a catalyst support. Specifically, the most probable pore diameter of the alumina prepared by the method of the present invention is 6-12 nm, the specific surface area is 150-600 m 2 / g, and it can still maintain a high specific surface area after 120 h of hydrothermal treatment.

[0050] The technical solution of the present invention will be further described in detail below through specific examples.

[0051] Raw material sources and specifications

[0052] Aluminum salts: aluminum nitrate, aluminum sulfate, aluminum chloride or aluminum acetate and their corresponding hydrates.

[0053] Alkaline compounds: sodium hydroxide, sodium carbonate, sodium acetate, sodium metaaluminate, urea, hexamethylenetetramine or ammonia water.

[0054] Example 1

[0055] Step 1: Prepare an aluminum salt solution with a molar concentration of 0.01 mol / L using aluminum sulfate octadecahydrate; prepare an alkaline solution with a molar concentration of 0.06 mol / L using sodium metaaluminate according to the molar ratio of aluminum salt / alkali of 1:6;

[0056] Step 2: Start the rotating liquid film reactor, set the stator-rotor gap of the rotating liquid film reactor to 0.2 mm and the rotation speed to 1000 rpm, and pump the aluminum salt solution and the alkaline solution in Step 1 into the reactor at the same rate using peristaltic pumps for rapid nucleation, and collect the nucleation slurry at the slurry outlet;

[0057] Step 3: Add the nucleation slurry to a three-necked flask, age and grow at 70 °C for 2 h, then naturally cool to room temperature, centrifuge the aged product, and wash it with water until neutral. The product is dried at 60 °C for 12 h to obtain the product pseudo-boehmite;

[0058] Step 4: The pseudo-boehmite obtained in Step 3 is formed through an oil-ammonia column, washed, dried, and calcined to obtain the final product, spherical alumina; its chemical formula is γ-Al 2 O 3 , with a particle size of 1.5 mm, a bulk density of 0.65 g / mL, a pore volume of 0.53 mL / g, a most probable pore diameter of 7.6 nm, and a specific surface area of 231.6 m 2 / g. After 120 hours of hydrothermal treatment, it can still maintain a specific surface area of more than 74.8%.

[0059] Figure 1 XRD pattern of the pseudo-boehmite prepared in Example 1, showing no impurity diffraction peaks, indicating extremely high purity. Figure 2 XRD pattern of the macroporous high hydrothermal stability alumina prepared in Example 1, showing typical γ-alumina diffraction peaks. Figure 3 SEM image of the macroporous high hydrothermal stability alumina prepared in Example 1, with an internal structure having certain pores. Figure 4 BET characterization diagram of the hydrothermal treatment process of the macroporous high hydrothermal stability alumina prepared in Example 1, with a relatively low degree of decrease in specific surface area, and still able to maintain a specific surface area of more than 74.8%.

[0060] Example 2

[0061] Step 1: Prepare an aluminum salt solution with a molar concentration of 0.02 mol / L using aluminum sulfate octadecahydrate; prepare an alkali solution with a molar concentration of 0.12 mol / L using sodium aluminate according to the ratio of aluminum salt / alkali molar ratio of 1:6;

[0062] Step 2: Start the rotating liquid film reactor, set the stator-rotor gap of the rotating liquid film reactor to 0.2 mm and the rotation speed to 500 rpm, and pump the aluminum salt solution and the alkali solution in Step 1 into the reactor at the same rate using peristaltic pumps for rapid nucleation, and collect the nucleated slurry at the slurry outlet;

[0063] Step 3: Add the nucleated slurry to a three-necked flask, age and grow at 70 °C for 2 h, then naturally cool to room temperature, centrifuge the aged product, and wash it with water until neutral. Place the product in an oven at 60 °C and dry it for 12 h to obtain the product pseudo-boehmite;

[0064] Step 4: The pseudo-boehmite obtained in Step 3 is formed through an oil-ammonia column, washed, dried, and calcined to obtain the final product, spherical alumina; its chemical formula is γ-Al 2 O 3 , with a particle size of 1.4 mm, a bulk density of 0.66 g / mL, a pore volume of 0.50 mL / g, a most probable pore diameter of 7.4 nm, and a specific surface area of 230.8 m 2 / g, the specific surface area can remain 71.3% after 120 hours of hydrothermal treatment.

[0065] Example 3

[0066] Step 1: Prepare an aluminum salt solution with a molar concentration of 0.1 mol / L using aluminum sulfate octadecahydrate; prepare an alkali solution with a molar concentration of 0.3 mol / L using sodium aluminate according to the molar ratio of aluminum salt / alkali of 1:3.

[0067] Step 2: Start the rotating liquid film reactor, set the stator-rotor gap of the rotating liquid film reactor to 0.2 mm and the rotation speed to 1100 rpm, and pump the aluminum salt solution and the alkali solution in Step 1 into the reactor at the same rate using peristaltic pumps for rapid nucleation, and collect the nucleated slurry at the slurry outlet.

[0068] Step 3: Add the nucleated slurry to a three-necked flask, age and grow at 70 °C for 2 h, then naturally cool to room temperature, centrifuge the aged product, and wash it with water until neutral. Place the product in an oven at 60 °C and dry it for 12 h to obtain the product pseudo-boehmite.

[0069] Step 4: Shape the pseudo-boehmite obtained in Step 3 through an oil-ammonia column, wash, dry, and calcine it to obtain the final product spherical alumina; its chemical formula is γ-Al 2 O 3 , with a particle size of 1.5 mm, a bulk density of 0.64 g / mL, a pore volume of 0.56 mL / g, a most probable pore diameter of 8.2 nm, and a specific surface area of 233.2 m 2 / g, the specific surface area can remain 72.5% after 120 hours of hydrothermal treatment.

[0070] Example 4

[0071] Step 1: Prepare an aluminum salt solution with a molar concentration of 0.01 mol / L using aluminum sulfate octadecahydrate; prepare an alkali solution with a molar concentration of 0.03 mol / L using sodium aluminate according to the molar ratio of aluminum salt / alkali of 1:3.

[0072] Step 2: Start the rotating liquid film reactor, set the stator-rotor gap of the rotating liquid film reactor to 0.1 mm and the rotation speed to 1000 rpm, and pump the aluminum salt solution and the alkali solution in Step 1 into the reactor at the same rate using peristaltic pumps for rapid nucleation, and collect the nucleated slurry at the slurry outlet.

[0073] Step 3: Add the nucleated slurry to a three-necked flask, age and grow at 70 °C for 2 h, then naturally cool to room temperature, centrifuge the aged product, and wash it with water until neutral. Place the product in an oven at 60 °C and dry it for 12 h to obtain the product pseudo-boehmite.

[0074] Step 4: The pseudo-boehmite obtained in Step 3 is formed through an oil-ammonia column, washed, dried, and calcined to obtain the final product, spherical alumina; its chemical formula is γ-Al 2 O 3 , with a particle size of 1.5 mm, a bulk density of 0.71 g / mL, a pore volume of 0.48 mL / g, a most probable pore diameter of 7.8 nm, and a specific surface area of 222.5 m 2 / g. After 120 hours of hydrothermal treatment, the specific surface area can be maintained at 71.9%.

[0075] Example 5

[0076] Step 1: Prepare an aluminum salt solution with a molar concentration of 0.01 mol / L using aluminum sulfate octadecahydrate; prepare an alkali solution with a molar concentration of 0.06 mol / L using sodium aluminate according to the ratio of aluminum salt / alkali molar ratio of 1:6;

[0077] Step 2: Start the rotating liquid film reactor, set the stator-rotor gap of the rotating liquid film reactor to 0.2 mm and the rotation speed to 500 rpm, and pump the aluminum salt solution and the alkali solution in Step 1 into the reactor at the same rate using peristaltic pumps for rapid nucleation, and collect the nucleated slurry at the slurry outlet;

[0078] Step 3: Add the nucleated slurry to a three-necked flask, age and grow at 90 °C for 2 h, then naturally cool to room temperature, centrifuge the aged product, and wash it with water until neutral. Place the product in an oven at 60 °C and dry for 12 h to obtain the product pseudo-boehmite;

[0079] Step 4: The pseudo-boehmite obtained in Step 3 is formed through an oil-ammonia column, washed, dried, and calcined to obtain the final product, spherical alumina; its chemical formula is γ-Al 2 O 3 , with a particle size of 1.5 mm, a bulk density of 0.63 g / mL, a pore volume of 0.54 mL / g, a most probable pore diameter of 7.5 nm, and a specific surface area of 230.9 m 2 / g. After 120 hours of hydrothermal treatment, the specific surface area can be maintained at 70.6%.

[0080] Comparative Example 1

[0081] It is not prepared using pseudo-boehmite with crystal plane selectivity as the precursor. The specific method is to use the SB powder purchased from Sasol as the precursor, form it through an oil-ammonia column, wash, dry, and calcine to obtain spherical alumina.

[0082] Figure 5 Figure 37 shows the SEM photograph of the alumina prepared in Comparative Example 1, and its internal surface is rougher. Figure 6It is the BET characterization diagram of the hydrothermal treatment process of the alumina prepared in Comparative Example 1. The degree of decrease in specific surface area is high, and only 64.8% of the specific surface area can be maintained.

[0083] Comparative Example 2

[0084] Step 1: Prepare an aluminum salt solution with a molar concentration of 0.02 mol / L using aluminum sulfate octadecahydrate; prepare an alkali solution with a molar concentration of 0.12 mol / L using sodium aluminate according to the molar ratio of aluminum salt / alkali of 1:6.

[0085] Step 2: Start the rotating liquid film reactor, set the stator-rotor gap of the rotating liquid film reactor to 0.5 mm and the rotation speed to 700 rpm. Pump the aluminum salt solution and the alkali solution in Step 1 into the reactor at the same rate using peristaltic pumps for rapid nucleation, and collect the nucleated slurry at the slurry outlet.

[0086] Step 3: Add the nucleated slurry to a three-necked flask, age and grow at 70 °C for 2 h, then naturally cool to room temperature. Centrifuge the aged product and wash it with water until neutral. Place the product in an oven at 60 °C for drying for 12 h to obtain the product pseudo-boehmite.

[0087] Step 4: Shape the pseudo-boehmite obtained in Step 3 through an oil-ammonia column, wash, dry, and calcine it to obtain the final product spherical alumina; its chemical formula is γ-Al 2 O 3 , with a particle size of 1.5 mm, a bulk density of 0.67 g / mL, a pore volume of 0.48 mL / g, a most probable pore diameter of 6.6 nm, and a specific surface area of 212.8 m 2 / g. After 120 hours of hydrothermal treatment, the specific surface area is maintained at 65.5%.

[0088] Comparative Example 3

[0089] Step 1: Prepare an aluminum salt solution with a molar concentration of 0.02 mol / L using aluminum sulfate octadecahydrate; prepare an alkali solution with a molar concentration of 0.12 mol / L using sodium aluminate according to the molar ratio of aluminum salt / alkali of 1:6.

[0090] Step 2: Start the rotating liquid film reactor, set the stator-rotor gap of the rotating liquid film reactor to 0.2 mm and the rotation speed to 2000 rpm. Pump the aluminum salt solution and the alkali solution in Step 1 into the reactor at the same rate using peristaltic pumps for rapid nucleation, and collect the nucleated slurry at the slurry outlet.

[0091] Step 3: Add the nucleated slurry to a three-necked flask, age and grow at 70 °C for 2 h, then naturally cool to room temperature. Centrifuge the aged product and wash it with water until neutral. Place the product in an oven at 60 °C for drying for 12 h to obtain the product pseudo-boehmite.

[0092] Step 4: The pseudo-boehmite obtained in Step 3 is formed through an oil-ammonia column, washed, dried, and calcined to obtain the final product, spherical alumina; its chemical formula is γ-Al 2 O 3 , with a particle size of 1.5 mm, a bulk density of 0.70 g / mL, a pore volume of 0.46 mL / g, a most probable pore diameter of 6.3 nm, and a specific surface area of 205.3 m 2 / g. After 120 hours of hydrothermal treatment, the specific surface area remains 65.3%.

[0093] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention. However, these corresponding changes and deformations should all fall within the protection scope of the claims of the present invention.

Claims

1. A preparation method of pseudo-boehmite, characterized in that, it comprises the following steps: Step 1, simultaneously add an aluminum salt solution and an alkali solution into a rotating liquid film reactor, and nucleate at 20 - 30 °C to obtain a nucleated slurry; wherein, the rotation speed of the rotating liquid film reactor is 500 - 1200 rpm, and the stator-rotor gap of the rotating liquid film reactor is 0.1 - 0.3 mm; Step 2, transfer the nucleated slurry to a crystallization reaction device, carry out crystallization at 70 - 90 °C, then carry out solid-liquid separation and drying to obtain pseudo-boehmite.

2. The preparation method of pseudo-boehmite according to claim 1, characterized in that, the rotation speed of the rotating liquid film reactor is 500 - 1000 rpm.

3. The preparation method of pseudo-boehmite according to claim 1, characterized in that, the stator-rotor gap of the rotating liquid film reactor is 0.1 - 0.2 mm.

4. The preparation method of pseudo-boehmite according to claim 1, characterized in that, the aluminum salt solution is an aqueous solution of at least one of aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum acetate and the corresponding hydrates of these substances.

5. The preparation method of pseudo-boehmite according to claim 1, characterized in that, the alkali solution is an aqueous solution of at least one of sodium hydroxide, sodium carbonate, sodium acetate, sodium metaaluminate, urea, hexamethylenetetramine and ammonia water.

6. The preparation method of pseudo-boehmite according to claim 1, characterized in that, the molar concentration of the aluminum salt solution is 0.01 mol / L - 0.03 mol / L; the molar concentration of the alkali solution is 0.03 mol / L - 0.18 mol / L; the aluminum salt solution is calculated based on aluminum, the alkali solution is calculated based on hydroxide ions, and the molar ratio of the aluminum salt solution to the alkali solution is 1:3 - 7.

7. The preparation method of pseudo-boehmite according to claim 1, characterized in that, in Step 1, the aluminum salt solution and the alkali solution are added to the rotating liquid film reactor at the same speed.

8. The preparation method of pseudo-boehmite according to claim 1, characterized in that, in Step 2, the crystallization time is 1 - 5 hours.

9. The preparation method of pseudo-boehmite according to claim 1, characterized in that, in Step 2, the drying temperature is 60 - 90 °C, and the drying time is 2 - 12 hours.

10. A preparation method of macroporous high hydrothermal stability alumina, characterized in that, it comprises the following steps: subject the pseudo-boehmite obtained by the preparation method according to any one of claims 1 - 9 to oil-ammonia column forming, drying and calcination to obtain macroporous high hydrothermal stability alumina.

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