A method of controlling boehmite morphology
Boehmite was prepared by combining hydrothermal reaction with organic base and cationic surfactant modifier, which solved the problems of uncontrollable morphology and high impurities in boehmite, and achieved the effects of controllable morphology, good dispersibility and high purity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANHUI ESTONE MATERIAL TECH CO LTD
- Filing Date
- 2023-12-28
- Publication Date
- 2026-06-19
AI Technical Summary
Existing technologies for preparing boehmite suffer from problems such as uncontrollable morphology, poor dispersibility, and high content of metallic impurities.
Boehmite was prepared by hydrothermal reaction using an aluminum source and a morphology modifier. The pH value and morphology were adjusted by organic base and cationic surfactant. Boehmite with different morphologies was obtained by combining hydrothermal reaction conditions.
It achieves good controllability and dispersibility of boehmite morphology, low content of metal impurities, simple post-processing operation, and high product purity.
Smart Images
Figure CN117886346B_ABST
Abstract
Description
Technical fields:
[0001] This invention relates to the field of boehmite technology, and more specifically to a method for controlling the morphology of boehmite. Background technology:
[0002] Boehmite (γ-AlOOH), also known as diaspore monohydrate, is a hydrated alumina containing one molecule of water of crystallization. It is widely used in lithium batteries, catalyst supports, and inorganic flame retardants. Boehmite used in the lithium battery industry is mostly plate-like in shape, but diverse morphologies of boehmite have become a research hotspot in recent years. Some researchers have prepared rod-shaped, fibrous, flower-like, and spherical boehmite using different methods.
[0003] Patent CN112607759A discloses a method for controlling the morphology of boehmite. Using magnesium chloride and aluminum hydroxide as raw materials, a mixed slurry is prepared in different weight ratios and poured into a reactor for hydrothermal reaction at 160-220℃ for 12-48 hours, yielding needle-like and hexagonal platy boehmite. When the weight ratio of magnesium chloride to aluminum hydroxide is (1-3):1, needle-like boehmite is obtained; when the weight ratio is 1:(20-50), hexagonal platy boehmite is obtained. This method is simple and easy to implement, but the use of magnesium salts as raw materials reduces the purity of the resulting boehmite.
[0004] Patent CN107913665A discloses a method for preparing and applying metal-doped boehmite. The method involves mixing a certain proportion of a doped metal salt solution and an aluminum salt solution as precursors, using sodium citrate as a complexing agent, and water and anhydrous ethanol as a mixed solvent. The mixture is then subjected to a solvothermal reaction in a reactor at 160-220℃ for 12-48 hours to obtain metal-doped boehmite with different morphologies. However, this method uses sodium citrate as a complexing agent, making it difficult to completely remove impurities from the product. The resulting metal-doped boehmite has low crystallinity, limiting its applications.
[0005] Patent CN108569713A discloses a method for preparing platy boehmite using an alkaline process. Aluminum hydroxide is ball-milled with water to form an aluminum hydroxide slurry. Sodium acetate, sodium carbonate, sodium nitrate, and other morphology control agents are added, and then an inorganic alkali is added to adjust the pH to alkalinity. After a hydrothermal reaction, platy boehmite is obtained. This method has a short reaction time, but the use of alkali metal salts and inorganic alkalis makes it difficult to completely remove alkali metal impurities. Summary of the Invention:
[0006] To overcome the shortcomings of existing technologies, this invention provides a method for controlling the morphology of boehmite. This method is simple and easy to implement, and the resulting boehmite has a controllable morphology, good dispersibility, and low metal impurity content.
[0007] The technical problem to be solved by this invention is achieved by the following technical solution:
[0008] The purpose of this invention is to provide a method for controlling the morphology of boehmite, the method comprising the following steps:
[0009] (1) Add aluminum source to deionized water to prepare a slurry;
[0010] (2) Add morphology modifier to slurry and then transfer it to hydrothermal reactor for hydrothermal reaction;
[0011] (3) After cooling, the product is washed with water and dried to obtain boehmite with different morphologies.
[0012] In this invention, the aluminum source is at least one selected from aluminum hydroxide, γ-alumina, and activated alumina. Preferably, the median particle size of the aluminum source is 1-15 μm.
[0013] In a further technical solution, the solid content of the slurry is 10-40%. It is necessary to control the solid content of the slurry. When the solid content is too high, the product agglomerates severely and causes caking; when the solid content is too low, excessive organic alkali needs to be added to adjust the pH value of the slurry, which easily exacerbates product agglomeration.
[0014] In this invention, the morphology modifiers are organic bases and cationic surfactants. Using organic bases and cationic surfactants as morphology modifiers, the organic base controls the morphology of boehmite by adjusting the pH value, while the cationic surfactant adsorbs onto the solid surface during hydrothermal processes to form an electric double layer, improving the dispersibility of the boehmite. The two work together to regulate the morphology and dispersibility of the boehmite.
[0015] In a further technical solution, the organic base is a quaternary ammonium base and / or an organic amine.
[0016] Preferably, the quaternary ammonium base includes, but is not limited to, at least one of choline, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, dodecyltrimethylammonium hydroxide, tetradecyltrimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide, and octadecyltrimethylammonium hydroxide.
[0017] Preferably, the organic amine includes, but is not limited to, at least one of ethylamine, ethylenediamine, aniline, naphthylamine, and N-methylmorpholine.
[0018] In a further technical solution, the cationic surfactant is a quaternary ammonium salt cationic surfactant.
[0019] Preferably, the quaternary ammonium salt cationic surfactant includes, but is not limited to, at least one of dodecyltrimethylammonium bromide (DTAB), hexadecyltrimethylammonium bromide (CTAB), and octadecyltrimethylammonium bromide (OTAB).
[0020] In a further technical solution, the weight ratio of organic base to cationic surfactant in the morphology modifier is (1-50):1.
[0021] In a further technical solution, the amount of the morphology modifier is 1-5% of the mass of the aluminum source. It is necessary to control the amount of the morphology modifier; if the amount is too small, it cannot effectively control the morphology of the boehmite; if the amount is too large, the cleaning time will increase.
[0022] In this invention, the hydrothermal reaction temperature is 160–220°C, and the reaction time is 20–50 h. By adding morphology modifiers and controlling the hydrothermal reaction conditions, boehmite with different morphologies is obtained.
[0023] In this invention, the different morphologies of boehmite include massive boehmite, tabular boehmite, and flaky boehmite.
[0024] The beneficial effects of this invention are:
[0025] (1) The present invention uses aluminum source and morphology modifier to prepare boehmite with different morphologies through hydrothermal reaction, and the morphology and thickness of boehmite can be controlled from block, plate to sheet.
[0026] (2) In the morphology modifier described in this invention, an organic base is used instead of a traditional inorganic base to adjust the pH value of the reaction system and control the morphology of boehmite. However, boehmite is prone to agglomeration under alkaline conditions and has poor dispersibility. Quaternary ammonium salt cationic surfactants are not affected by pH changes. During hydrothermal processes, they adsorb onto the solid surface to form an electric double layer, thereby improving the dispersibility of boehmite. Therefore, this invention adjusts the morphology and dispersibility of boehmite through the combined action of organic base and cationic surfactant.
[0027] (3) The present invention can obtain boehmite products by washing the hydrothermal reaction products with hot water, and the post-processing operation is simple; in addition, the morphology modifier used in the present invention will not introduce metal ions, thereby improving the purity of the boehmite products. Attached image description:
[0028] Figure 1 Here is a SEM image of boehmite obtained in Example 1;
[0029] Figure 2 The XRD pattern of boehmite obtained in Example 1;
[0030] Figure 3Here is a SEM image of boehmite obtained in Example 2;
[0031] Figure 4 Here is a SEM image of boehmite obtained in Example 3;
[0032] Figure 5 Here is a SEM image of boehmite obtained in Example 4;
[0033] Figure 6 Here is a SEM image of boehmite obtained in Example 5;
[0034] Figure 7 Here is a SEM image of boehmite obtained in Example 6;
[0035] Figure 8 SEM image of boehmite obtained in Example 7;
[0036] Figure 9 Here is a SEM image of boehmite obtained in Example 8;
[0037] Figure 10 SEM image of boehmite obtained in Example 9;
[0038] Figure 11 SEM image of boehmite obtained in Comparative Example 1;
[0039] Figure 12 SEM image of boehmite obtained in Comparative Example 2;
[0040] Figure 13 SEM image of boehmite obtained in Comparative Example 3;
[0041] Figure 14 The image shows the SEM image of boehmite obtained in Comparative Example 4. Detailed implementation method:
[0042] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments and illustrations.
[0043] The metal impurity content in the following examples and comparative examples was determined according to US EPA 3050B:1996, using ICP-OES analysis.
[0044] Example 1
[0045] 20g of aluminum hydroxide (median particle size 2μm) was added to 80g of deionized water to form a slurry. Then, 0.2g of morphology modifier (aniline to CTAB mass ratio 40:1) was added, and the mixture was transferred to a hydrothermal reactor and reacted at 200℃ for 48h. After cooling, the product was washed with deionized water and dried to obtain regular plate-shaped boehmite.
[0046] Figure 1 This is a SEM image of boehmite obtained in Example 1. From... Figure 1 As can be seen, Example 1 yielded regular, tabular boehmite. The Na content was determined to be 50 ppm and the Ca content to be 33 ppm.
[0047] Figure 2 The image shows the XRD pattern of boehmite obtained in Example 1. Figure 2 It can be seen that Example 1 yielded a pure phase γ-AlOOH, without any impurities.
[0048] Example 2
[0049] 30g of aluminum hydroxide (median particle size 10μm) was added to 70g of deionized water to form a slurry. Then, 0.6g of morphology modifier (ethylenediamine to CTAB mass ratio 20:1) was added, and the mixture was transferred to a hydrothermal reactor and reacted at 170℃ for 20h. After cooling, the product was washed with deionized water and dried to obtain massive boehmite.
[0050] Figure 3 This is a SEM image of boehmite obtained in Example 2. From... Figure 3 As can be seen, Example 2 yielded massive boehmite. The Na content was determined to be 35 ppm.
[0051] Example 3
[0052] 20g of aluminum hydroxide (median particle size 1μm) was added to 80g of deionized water to form a slurry. Then, 0.5g of morphology modifier (N-methylmorpholine to CTAB mass ratio of 35:1) was added, and the mixture was transferred to a hydrothermal reactor and reacted at 180℃ for 30h. After cooling, the product was washed with deionized water and dried to obtain platy boehmite.
[0053] Figure 4 This is a SEM image of boehmite obtained in Example 3. From... Figure 4 As can be seen, Example 3 yielded platy boehmite. The Na content was determined to be 36 ppm and the Zn content to be 1 ppm.
[0054] Example 4
[0055] 20g of aluminum hydroxide (median particle size 5μm) and 2g of γ-Al₂O₃ (median particle size 15μm) were added to 80g of deionized water to form a slurry. Then, 0.8g of morphology modifier (choline to CTAB mass ratio of 5:1) was added, and the mixture was transferred to a hydrothermal reactor and reacted at 190℃ for 40h. After cooling, the product was washed with deionized water and dried to obtain massive boehmite.
[0056] Figure 5This is a SEM image of boehmite obtained in Example 4. From... Figure 5 As can be seen, Example 4 yielded massive boehmite. The Na content was determined to be 14 ppm and the K content to be 2 ppm.
[0057] Example 5
[0058] 35g of γ-Al₂O₃ (median particle size 8μm) was added to 75g of deionized water to form a slurry. Then, 0.8g of morphology modifier (ethylamine to CTAB mass ratio 15:1) was added, and the mixture was transferred to a hydrothermal reactor and reacted at 185℃ for 35h. After cooling, the product was washed with deionized water and dried to obtain platy boehmite.
[0059] Figure 6 This is a SEM image of boehmite obtained in Example 5. From... Figure 6 As can be seen, Example 5 yielded platy boehmite. The Na content was determined to be 124 ppm.
[0060] Example 6
[0061] 10g of aluminum hydroxide (median particle size 15μm) was added to 90g of deionized water to form a slurry. Then, 0.1g of morphology modifier (tetramethylammonium hydroxide to DTAB mass ratio of 50:1) was added, and the mixture was transferred to a hydrothermal reactor and reacted at 160℃ for 50h. After cooling, the product was washed with deionized water and dried to obtain plate-shaped boehmite.
[0062] Figure 7 This is a SEM image of boehmite obtained in Example 6. From... Figure 7 It can be seen that Example 6 yielded plate-like boehmite. The Na content was determined to be 101 ppm.
[0063] Example 7
[0064] 30g of aluminum hydroxide (median particle size 3μm) was added to 70g of deionized water to form a slurry. Then, 1.5g of morphology modifier (dodecyltrimethylammonium hydroxide to OTAB in a mass ratio of 1:1) was added, and the mixture was transferred to a hydrothermal reactor and reacted at 220℃ for 20h. After cooling, the product was washed with deionized water and dried to obtain long, sheet-like boehmite.
[0065] Figure 8 This is a SEM image of boehmite obtained in Example 7. From... Figure 8 As can be seen, Example 7 yielded long, platy boehmite. The Na content was determined to be 83 ppm.
[0066] Example 8
[0067] 30g of activated alumina (median particle size 5μm) was mixed with 70g of deionized water to form a slurry. Then, 0.3g of morphology modifier (octadecyltrimethylammonium hydroxide to OTAB mass ratio of 30:1) was added, and the mixture was transferred to a hydrothermal reactor and reacted at 185℃ for 30h. After cooling, the product was washed with deionized water and dried to obtain massive boehmite.
[0068] Figure 9 This is a SEM image of the boehmite obtained in Example 8. From... Figure 9 As can be seen, Example 8 yielded massive boehmite. The Na content was determined to be 118 ppm.
[0069] Example 9
[0070] 20g of aluminum hydroxide (median particle size 8μm) was added to 80g of deionized water to form a slurry. Then, 1.0g of morphology modifier (trimethylethylammonium hydroxide to DTAB mass ratio of 25:1) was added, and the mixture was transferred to a hydrothermal reactor and reacted at 170℃ for 40h. After cooling, the product was washed with deionized water and dried to obtain massive boehmite.
[0071] Figure 10 This is a SEM image of boehmite obtained in Example 9. From... Figure 10 As can be seen, Example 9 yielded massive boehmite. The Na content was determined to be 65 ppm.
[0072] Comparative Example 1
[0073] The only difference between Comparative Example 1 and Example 1 is that no morphology modifier was added, resulting in irregularly shaped plate-like boehmite.
[0074] Figure 11 The image shows a SEM image of boehmite obtained in Comparative Example 1. From... Figure 11 As can be seen, Comparative Example 1 yielded irregularly shaped plate-like boehmite. The sodium content was measured to be 231 ppm, and the Ca content was 121 ppm. This indicates that the addition of the morphology control agent can alter the morphology of the boehmite, and significantly improve its dispersion.
[0075] Comparative Example 2
[0076] The only difference between Comparative Example 2 and Example 1 is that aniline and CTAB are not added. Instead, sodium hydroxide is added to adjust the pH of the reaction system so that the pH of the reaction system is the same as that of Example 1, resulting in irregular plate-shaped boehmite.
[0077] Figure 12 The image shows a SEM image of boehmite obtained in Comparative Example 2. From... Figure 12As can be seen, Comparative Example 2 yielded irregularly shaped plate-like boehmite. The sodium content was determined to be 854 ppm. This indicates that the addition of the morphology modifier significantly reduces the content of metallic impurities in the boehmite, improving its purity; furthermore, replacing the inorganic alkali with the morphology modifier also improves the dispersion of the boehmite.
[0078] Comparative Example 3
[0079] The only difference between Comparative Example 3 and Example 5 is that no morphology modifier was added, resulting in irregular blocky boehmite.
[0080] Figure 13 The image shows a SEM image of boehmite obtained in Comparative Example 3. From... Figure 13 As can be seen, Comparative Example 3 yielded irregularly shaped massive boehmite. The Na content was measured to be 552 ppm. This indicates that the addition of the morphology modifier can change the morphology of the boehmite from massive to flaky, and effectively reduce the alkali metal Na content.
[0081] Comparative Example 4
[0082] The only difference between Comparative Example 4 and Example 1 is that only aniline was added to adjust the pH of the reaction system so that the pH of the reaction system was the same as that of Example 1, without adding CTAB, and the resulting product was plate-shaped boehmite.
[0083] Figure 14 The image shows a SEM image of boehmite obtained in Comparative Example 4. From... Figure 14 As can be seen, Comparative Example 4 yielded plate-like boehmite. The sodium content was measured to be 61 ppm and the Ca content to be 52 ppm. This indicates that the combined use of aniline and CTAB can effectively reduce the metal content of boehmite while improving its dispersion.
[0084] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A method for controlling the morphology of boehmite, characterized in that, The method includes the following steps: (1) Add aluminum source to deionized water to prepare a slurry; (2) Add morphology modifier to the slurry and then transfer it to a hydrothermal reactor for hydrothermal reaction; (3) After cooling, the product is washed with water and dried to obtain boehmite with different morphologies; The morphology modifier is an organic base and a cationic surfactant; The aluminum source is at least one of aluminum hydroxide, γ-alumina, and activated alumina; The organic base is a quaternary ammonium base and / or an organic amine; The quaternary ammonium base is selected from at least one of choline, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, dodecyltrimethylammonium hydroxide, tetradecyltrimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide, and octadecyltrimethylammonium hydroxide; The organic amine is selected from at least one of ethylamine, ethylenediamine, aniline, naphthylamine, and N-methylmorpholine; The cationic surfactant is a quaternary ammonium salt cationic surfactant; The quaternary ammonium salt cationic surfactant is selected from at least one of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and octadecyltrimethylammonium bromide.
2. The method according to claim 1, characterized in that: The median particle size of the aluminum source is 1-15 μm.
3. The method according to claim 1, characterized in that: The solid content of the slurry is 10-40%.
4. The method according to claim 1, characterized in that: The weight ratio of organic base to cationic surfactant in the morphology modifier is (1~50):
1.
5. The method according to claim 1, characterized in that: The amount of the morphology modifier is 1-5% of the mass of the aluminum source.
6. The method according to claim 1, characterized in that: The hydrothermal reaction is carried out at a temperature of 160-220℃ for 20-50 hours.
7. The method according to claim 1, characterized in that: The different morphologies of boehmite include massive boehmite, tabular boehmite, and platy boehmite.