A pseudo-boehmite and a method for producing the same

Abstract

This application relates to a pseudoboehmite and its preparation method. The method includes: obtaining a pseudoboehmite slurry; adding an auxiliary agent and a dispersant to the pseudoboehmite slurry to carry out a chemical reaction, and controlling the temperature of the chemical reaction to obtain pseudoboehmite; wherein the chemical composition of the auxiliary agent includes NH4. + The dispersant promotes a single-crystal distribution of the grains. This application addresses the problem of large amounts of Na inclusions between the grains of pseudoboehmite prepared by existing carbide methods. + The technical problem of high water consumption due to difficulty in removal.

Description

Technical Field

[0001] This application relates to the field of boehmite preparation technology, and in particular to a boehmite and its preparation method. Background Technology

[0002] Boehmite, also known as pseudo-boehmite, has the chemical formula AlOOH·nH2O. It is a white solid powder with high specific surface area and large pore volume, and can be used as a catalyst support and material for the production of activated alumina.

[0003] Currently, the main method for preparing boehmite in China is the carbonization method. The reaction raw materials for the carbonization method are sodium aluminate solution and CO2 gas. Due to the unique material properties of boehmite, washing removes sodium... + It is extremely difficult and consumes a large amount of water. At the same time, a large amount of washing liquid enters the production system, disrupting the water balance of the production system, increasing evaporation costs, and the resulting washing liquid is directly discharged, causing significant environmental damage. Summary of the Invention

[0004] This application provides a pseudoboehmite and its preparation method to solve the problem of large amounts of Na inclusions between grains in pseudoboehmite prepared by existing carbide methods. + The technical problem of high water consumption due to difficulty in removal.

[0005] In a first aspect, this application provides a method for preparing pseudoboehmite, the method comprising:

[0006] A pseudo-boehmite slurry was obtained;

[0007] Additives and dispersants are added to the pseudoboehmite slurry to carry out a chemical reaction, and the temperature of the chemical reaction is controlled to obtain pseudoboehmite; wherein,

[0008] The chemical composition of the auxiliary agent includes NH4. + The dispersant can promote the single-crystal distribution of crystal grains.

[0009] Optionally, the auxiliary agent includes at least one of the following: (NH4)2CO3, NH4HCO3.

[0010] Optionally, the additive is 4g to 10g relative to the second pseudo-boehmite slurry described in 1L.

[0011] Optionally, the dispersant includes at least one of the following: methanol, ethanol, and ethylene glycol.

[0012] Optionally, the dispersant is 2 mL to 10 mL relative to the second pseudoboehmite slurry described in 1 L.

[0013] Optionally, the temperature of the chemical reaction is 110℃~160℃.

[0014] Optionally, the chemical reaction can be carried out for 2 to 4 hours.

[0015] Optionally, obtaining the pseudo-boehmite slurry includes:

[0016] Sodium aluminate solution and carbon dioxide gas were subjected to a carbonation decomposition reaction, followed by aging, centrifugation washing, and slurry preparation to obtain a pseudoboehmite slurry; wherein...

[0017] The concentration of Al2O3 in the sodium aluminate solution is 15 g / L to 50 g / L.

[0018] Optionally, the aging process parameters include: a temperature of 80℃~95℃ and a time of 2h~3h.

[0019] Secondly, this application provides a pseudoboehmite, which is prepared by the method described in any one of the embodiments of the first aspect.

[0020] The technical solutions provided in this application have the following advantages compared with the prior art:

[0021] The method for preparing the pseudoboehmite provided in this application involves a chemical reaction between a second pseudoboehmite slurry, an additive, and a dispersant. The temperature of this chemical reaction is controlled to ensure increasingly perfect crystallization of the pseudoboehmite grains and a higher degree of crystallinity. Under the action of the dispersant, the pseudoboehmite grains are distributed as single crystals with little or no agglomeration. Na+ is interspersed between the grains. + The number of impurity ions is greatly reduced; and due to the NH4+ in the additives... + The existence of NH4 + It can replace Na + This causes Na between grains + This further reduces the amount of Na, thus solving the problem of large amounts of Na inclusions between grains in pseudoboehmite prepared by existing carbide methods. + The technical problem of high water consumption due to difficulty in removal. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic flowchart illustrating a method for preparing pseudoboehmite provided in an embodiment of this application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0027] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0028] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0029] Firstly, this application provides a method for preparing pseudoboehmite, please refer to [link to relevant documentation]. Figure 1 The method includes:

[0030] S1. Obtain the pseudo-boehmite slurry;

[0031] In some embodiments, obtaining the pseudoboehmite slurry includes: subjecting a sodium aluminate solution and carbon dioxide gas to a carbonation decomposition reaction, followed by aging, centrifugal washing, and slurry preparation to obtain the pseudoboehmite slurry; wherein the concentration of Al2O3 in the sodium aluminate solution is 15 g / L to 50 g / L.

[0032] In this embodiment, an appropriate Al2O3 concentration in the sodium aluminate solution is used to promote good grain development. If the concentration is too low, it can lead to difficulty in controlling the endpoint, and the resulting slurry concentration is low, resulting in a low product yield. Conversely, if the concentration is too high, the slurry concentration will be too high, easily causing severe agglomeration between grains, affecting grain development, resulting in low crystallinity, and a large amount of Na inclusions between the grains. + Impurities such as these are difficult to remove. Specifically, the concentration of Al2O3 can be 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, etc.

[0033] Furthermore, the aforementioned carbonation decomposition reaction of sodium aluminate solution and carbon dioxide gas specifically includes: passing carbon dioxide gas into the aluminate solution at a temperature of 15–50°C to carry out the carbonation decomposition reaction, with a carbon dioxide gas flow rate of 1.0 m³ / min. 3 / h~5.0m 3The reaction was controlled at a final pH of 9.5–11.5 per hour to obtain a boehmite carbonation slurry. The temperature of the carbonation decomposition reaction was crucial, as it primarily involves the formation of boehmite crystal nuclei. Lower temperatures favor the formation of finer crystal nuclei, but excessively low temperatures result in a viscous sodium aluminate solution containing sodium carbonate, hindering nuclei formation. Higher temperatures promote nuclei growth, but lead to fewer and coarser nuclei, resulting in coarser boehmite grains. Higher temperatures also slowed nuclei formation, reduced the number of nuclei, and resulted in coarser grains. The flow rate of carbon dioxide gas was also controlled. Insufficient CO2 flow resulted in a slow reaction, prolonged reaction time, low yield, and poor economics; excessive CO2 flow caused a rapid reaction, leading to a large number of instantaneous nuclei and excessively rapid grain growth, which negatively impacted product quality. Finally, the final pH of the reaction was controlled to obtain higher purity boehmite, as the pH of the slurry reflected the degree of carbonation in the aluminate solution. At excessively low pH, a large amount of diatomite impurities are easily formed in the product; at excessively high pH, ​​a large amount of gibbsite impurities are easily formed in the product.

[0034] In some embodiments, the aging process parameters include: a temperature of 80°C to 95°C and a time of 2 hours to 3 hours.

[0035] In this embodiment, during the aging reaction, the crystal nuclei further grow into crystals. At low temperatures, crystal growth is slow, requiring a longer time for complete crystal development, resulting in low yield. Higher temperatures lead to faster crystal growth and better crystal development, which is beneficial for solid-liquid separation; however, excessively high temperatures increase operational difficulty and energy consumption. The aging reaction time needs to be comprehensively considered. A short time results in incomplete crystal development and difficult solid-liquid separation, while an excessively long time leads to low production efficiency. Specifically, the aging temperature can be 80℃, 85℃, 90℃, 95℃, etc., and the aging time can be 2h, 2.5h, 3h, etc.

[0036] In addition, the above washing is carried out in a multi-stage countercurrent washing method. The temperature of the washing water is ≥90℃. The washing effect is poor when the washing water temperature is too low. The washing water consumption is large. The washing is carried out until the pH value of the filter cake is ≤8.0 to obtain a pseudo-boehmite wet filter cake.

[0037] The above method involves adding water to the wet filter cake of boehmite and stirring to form a slurry with a solid content of 150–180 g / L. If the slurry concentration is too low, the boehmite will disperse well, but the yield will be low; if the slurry concentration is too high, it will not be conducive to the dispersion of boehmite, and it will easily agglomerate, which will increase the amount of detergent and dispersant to be added.

[0038] S2. Add additives and dispersants to the pseudoboehmite slurry to carry out a chemical reaction, and control the temperature of the chemical reaction to obtain pseudoboehmite; wherein,

[0039] The chemical composition of the auxiliary agent includes NH4. + The dispersant can promote the single-crystal distribution of crystal grains.

[0040] In some embodiments, the additive includes at least one of the following: (NH4)2CO3 and NH4HCO3.

[0041] In some embodiments, the additive is 4g to 10g relative to the second pseudo-boehmite slurry described in 1L.

[0042] In the embodiments of this application, (NH4)2CO3 and NH4HCO3 are selected as auxiliaries, which can effectively promote the NH4 + It can replace Na + This causes Na between grains + Further reduction without introducing additional impurities. Appropriate additives will reduce Na... + Complete displacement requires sufficient additives, which wastes resources; insufficient additives may result in poor displacement. Specifically, relative to 1L of the second pseudoboehmite slurry, the additives mentioned above can be 4g, 5g, 6g, 7g, 8g, 9g, 10g, etc.

[0043] In some embodiments, the dispersant includes at least one of the following: methanol, ethanol, and ethylene glycol.

[0044] In some embodiments, the dispersant is 2 mL to 10 mL relative to the second pseudoboehmite slurry described in 1 L.

[0045] In the embodiments of this application, methanol, ethanol, and ethylene glycol are selected as dispersants, which can promote the single-crystal distribution of pseudoboehmite grains, with no or minimal agglomeration, and the Na interspersed between the grains. + Impurity ions are greatly reduced. Too much dispersant wastes costs; too little dispersant may not achieve the above-mentioned technical effects. Specifically, relative to 1L of the second pseudoboehmite slurry, the dispersant can be 2mL, 3mL, 4mL, 5mL, 6mL, 7mL, 8mL, 9mL, 10mL, etc.

[0046] In some embodiments, the temperature of the chemical reaction is 110°C to 160°C.

[0047] In some embodiments, the chemical reaction takes 2 to 4 hours.

[0048] In the embodiments of this application, under higher temperature and pressure, the pseudoboehmite crystallizes more completely, promoting the Na... + When impurity ions detach from the crystals and dissolve in the solution, and under the action of the dispersant, the crystal grains are distributed in a single crystal pattern with little or no agglomeration, greatly reducing intercrystalline alkali inclusions. Simultaneously, the NH4 in the detergent is reduced.+ It can displace Na + This causes the Na on the surface of the pseudo-thin crystal and between the grains to... + Further reduction facilitates the washing of boehmite, reducing the amount of washing water. If the temperature is too low, the boehmite crystallization will be incomplete, and Na... + Impurity ions tend to adhere to the crystal surface or become trapped between grains, hindering washing. Excessive temperature causes the boehmite crystals to lose some of their water of crystallization, resulting in the formation of new crystal phases and impurities. Too short a reaction time leads to incomplete boehmite crystallization, making it difficult to disperse as single crystals; too long a reaction time results in low yield and is uneconomical. Specifically, the reaction temperature can be 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, etc., and the reaction time can be 2h, 3h, 4h, etc.

[0049] In addition, after step S2, the process includes solid-liquid separation, washing, drying, pulverizing, and packaging to obtain the pseudo-boehmite product. The washing is performed using a multi-stage countercurrent washing method, with the washing water temperature ≥90℃. If the washing water temperature is too low, the washing effect will be poor, and the water consumption will be high. When the sodium oxide content in the product is ≤0.3%, the lower the washing water temperature, the greater the water consumption.

[0050] Secondly, this application provides a pseudoboehmite, which is prepared by the method described in any one of the embodiments of the first aspect.

[0051] This pseudoboehmite is prepared using the aforementioned method. It exhibits high crystallinity, high purity, good colloidal solubility, large specific surface area, and large pore volume. The specific steps of the preparation method can be found in the above embodiments. Since this pseudoboehmite utilizes some or all of the technical solutions described in the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions in the above embodiments, which will not be elaborated upon here.

[0052] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0053] This application provides a method for preparing pseudoboehmite, the method comprising:

[0054] S11. Obtain the pseudo-boehmite slurry;

[0055] S21. Adding additives and dispersants to the pseudoboehmite slurry to carry out a chemical reaction, and controlling the temperature of the chemical reaction to obtain pseudoboehmite; wherein,

[0056] The chemical composition of the auxiliary agent includes NH4. + The dispersant promotes the formation of single-crystal grains. For specific process steps, please refer to Examples 1-3.

[0057] Example 1

[0058] Prepare a 1L sodium aluminate solution with an Al₂O₃ concentration of 15g / L. Initiate a carbonation decomposition reaction by introducing carbon dioxide gas into the solution at 15℃. The carbon dioxide gas flow rate is 1.0m³. 3 / h, control the reaction endpoint pH=9.5; heat the carbonized slurry to age at 95℃ for 2h, after aging, perform solid-liquid separation, then wash the filter cake with pure water at ≥90℃ until the filter cake pH value ≤8.0; add water to the filter cake and stir to form a slurry with a solid content of 160g / L, then add (NH4)2CO3 to make its concentration 4g / L, add methanol to make its concentration 8mL / L, load the slurry into a high-pressure reactor with a filling volume of 60-80%, then heat to 140℃ and hold for 3h, then cool down to perform solid-liquid separation, wash the filter cake in a multi-stage countercurrent washing manner with a washing water temperature of ≥90℃, after the filter cake is washed and qualified, perform drying, crushing, and packaging processes to obtain the pseudoboehmite product.

[0059] Comparative Example 1

[0060] Referring to Example 1, the difference from Example 1 is that the filter cake that has been washed and qualified after aging is mixed with water to form a slurry. (NH4)2CO3 and methanol are not added to the slurry. The slurry is directly loaded into the high-pressure reactor and then heated.

[0061] The product indicators of pseudo-boehmite and the amount of washing water used per ton of product were analyzed, and the results are shown in Table 1.

[0062] Table 1. Comparison of Samples from Example 1 and Comparative Example 1 with Industry Standard Product Indicators.

[0063]

[0064] Table 1 shows the washing water consumption per ton of product: the sum of washing water consumption after aging and washing water consumption after hydrothermal reaction in an autoclave. As can be seen from Table 1, compared with the industry standard product and the product of Comparative Example 1, the pseudoboehmite prepared in Example 1 of this application has a higher pore volume and specific surface area, resulting in a significant reduction in washing water consumption per ton of product. The data in Table 1 indicate that when it is necessary to reduce the sodium oxide content of the product to the same or similar value, the pseudoboehmite preparation method provided in this application is more water-efficient and energy-saving.

[0065] Example 2

[0066] Prepare a 1L sodium aluminate solution with an Al₂O₃ concentration of 50g / L. Initiate a carbonation decomposition reaction by introducing carbon dioxide gas into the solution at a temperature of 40℃. The carbon dioxide gas flow rate is 4.5m³ / L. 3 / h, control the final pH of the reaction to be 10.5; heat the carbonized slurry to age at 90℃ for 2h, and then perform solid-liquid separation. Wash the filter cake with pure water at ≥90℃ until the pH value of the filter cake is ≤8.0; add water to the filter cake and stir to form a slurry with a solid content of 150g / L, then add NH4HCO3 to make the concentration 8g / L, and add ethanol to make the concentration 5mL / L. Load the slurry into a high-pressure reactor with a filling volume of 60-80%, then heat to 160℃ and hold for 2h, then cool down to perform solid-liquid separation. Wash the filter cake in a multi-stage countercurrent washing manner with a washing water temperature of ≥90℃. After the filter cake is washed and qualified, it is dried, crushed, and packaged to obtain the pseudoboehmite product.

[0067] Comparative Example 2

[0068] Referring to Example 2, the difference is that after the filter cake is washed and qualified after aging, water is added and stirred to form a slurry. NH4HCO3 and ethanol are not added to the slurry. The slurry is directly loaded into the high-pressure reactor and then heated.

[0069] The product indicators of pseudo-boehmite and the amount of washing water used per ton of product were analyzed, and the results are shown in Table 2.

[0070] Table 2 Comparison of Example 2 and Comparative Example 2 with Industry Standard Product Indicators

[0071]

[0072] Table 2 shows the washing water consumption per ton of product: the sum of washing water consumption after aging and washing water consumption after hydrothermal reaction in an autoclave. As can be seen from Table 2, compared with the industry standard product and the product of Comparative Example 2, the pseudoboehmite prepared in Example 2 of this application has a higher pore volume and specific surface area, resulting in a significant reduction in washing water consumption per ton of product. The data in Table 2 indicate that when it is necessary to reduce the sodium oxide content of the product to the same or similar value, the pseudoboehmite preparation method provided in this application is more water-efficient and energy-saving.

[0073] Example 3

[0074] A 1L sodium aluminate solution with an Al₂O₃ concentration of 30g / L was prepared. Carbon dioxide gas was then introduced into the solution at 30℃ to initiate a carbonation decomposition reaction. The flow rate of the carbon dioxide gas was 2.8m³. 3 / h, control the final pH of the reaction to be 11.5; heat the carbonized slurry to age at 80℃ for 3h, and after aging, perform solid-liquid separation. Wash the filter cake with distilled water at ≥90℃ until the pH value of the filter cake is ≤8.0; add water to the filter cake and stir to form a slurry with a solid content of 180g / L, then add NH4HCO3 to make the concentration 10g / L, and add ethanol to make the concentration 10mL / L. Load the slurry into a high-pressure reactor with a filling volume of 60-80%, then heat to 110℃ and hold for 4h, then cool down to perform solid-liquid separation. Wash the filter cake in a multi-stage countercurrent washing manner with a washing water temperature of ≥90℃. After the filter cake is washed and qualified, it is dried, crushed, and packaged to obtain the pseudoboehmite product.

[0075] Comparative Example 3

[0076] Referring to Example 3, the difference from Example 3 is that the washed and qualified filter cake after aging is mixed with water to form a slurry. NH4HCO3 and ethanol are not added to the slurry. The slurry is directly loaded into the high-pressure reactor and then heated.

[0077] The product indicators of pseudo-boehmite and the amount of washing water used per ton of product were analyzed, and the results are shown in Table 3.

[0078] Table 3. Comparison of product indicators of Example 3 and Comparative Example 3 with industry standard product indicators.

[0079]

[0080] The water consumption per ton of product in Table 3 is the sum of the water consumption for washing after aging and the water consumption for washing after hydrothermal reaction in an autoclave.

[0081] As shown in Table 3, compared with the industry standard product and the product of Comparative Example 3, the pseudoboehmite prepared in Example 3 of this application has a higher pore volume and specific surface area, and the washing water consumption per ton of product is significantly reduced. The data in Table 3 indicate that when it is necessary to reduce the sodium oxide content of the product to the same or similar value, the pseudoboehmite preparation method provided in this application is more water-saving and energy-efficient.

[0082] The embodiments of this application provide one or more technical solutions, which have at least the following technical effects or advantages:

[0083] (1) This pseudoboehmite preparation technology uses carbonization method, which is simple to prepare, has low equipment requirements, low cost, and is suitable for industrial production. The prepared pseudoboehmite has the characteristics of good crystal form, high purity, high crystallinity, large pore volume, large specific surface area, and good colloidal solubility, and can be widely used in the field of catalysis.

[0084] (2) Using sodium aluminate solution as raw material, pseudoboehmite products are prepared by carbonation decomposition. By controlling the solution concentration, temperature, carbon dioxide flow rate, and final pH value, pseudoboehmite carbonization liquid is prepared. The aged product inevitably contains trihydrate impurities, which affect the purity and crystallinity of the product. In this preparation process, the aged product is washed and then hydrated into a slurry. After adding washing aids and dispersants, the temperature is raised. Under high temperature and high pressure, the trihydrate phase will be transformed into the pseudoboehmite phase, which improves the purity and crystallinity of the product.

[0085] (3) Under high temperature and high pressure conditions, the pseudoboehmite crystallizes more and more perfectly, with the grains dispersed into single crystals, and Na intercalated between the crystals. + Impurities dissolve in the solution, and the low viscosity of the solution under high temperature and pressure is beneficial for crystal dispersion and the removal of NH4 from the washing aid. + Displace Na + This helps reduce the amount of washing water used for boehmite. In addition, at high temperatures, part of the dispersant is converted into gas and dispersed in the channels of the boehmite grains, which greatly increases the pore volume of the product and improves the pore structure.

[0086] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing pseudoboehmite, characterized in that, The method includes: A pseudo-boehmite slurry was obtained; Additives and dispersants are added to the pseudoboehmite slurry to carry out a chemical reaction, and the temperature of the chemical reaction is controlled to obtain pseudoboehmite; wherein, The chemical composition of the auxiliary agent includes NH4. + The dispersant can promote the single-crystal distribution of crystal grains; The dispersant includes at least one of the following: methanol, ethanol, ethylene glycol. The amount of the additive added is 4g to 10g relative to 1L of the pseudoboehmite slurry, and the amount of the dispersant added is 2mL to 10mL. The temperature of the chemical reaction is 110℃~160℃, and the reaction time is 2h~4h; The obtained pseudo-boehmite slurry includes: Sodium aluminate solution and carbon dioxide gas were subjected to a carbonation decomposition reaction, followed by aging, centrifugation washing, and slurry preparation to obtain a pseudoboehmite slurry; wherein... The concentration of Al2O3 in the sodium aluminate solution is 15 g / L to 50 g / L, and the aging process parameters include: temperature of 80℃ to 95℃ and time of 2h to 3h.

2. The method according to claim 1, characterized in that, The auxiliary agent includes at least one of the following: (NH4)2CO3 and NH4HCO3.

3. A pseudoboehmite, characterized in that, The pseudoboehmite is prepared by the method described in any one of claims 1 to 2.

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