Preparation method of cobalt-based powder material
The solvothermal method for preparing cobalt-based powder materials solves the problems of poor dispersibility and morphology controllability in existing technologies, and realizes the preparation of high-purity, low-energy-consumption cobalt-based powder materials, which are applicable to the field of inorganic pigments.
Patent Information
- Application Number
- CN202411741849.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-01-10
AI Technical Summary
Existing cobalt-based powder materials suffer from problems such as poor dispersibility, poor morphology controllability, limited color, high energy consumption in preparation methods, and complex production processes, which restrict their widespread application.
Cobalt-based powder materials were synthesized by a solvothermal method. Cobalt salt solution, phosphate solution and precipitant solution were mixed in an alcohol-based organic solvent, and the pH value was controlled at 9-11. The solvothermal reaction was carried out at 120-200℃ and 0.3-4 MPa. After centrifugation, washing and drying, blue-purple NH4CoPO4·H2O powder was prepared.
It achieves uniform morphology, narrow particle size distribution, controllable color, and high purity of cobalt-based powder materials, simplifies the preparation process, and reduces energy consumption.
Smart Images
Figure CN119284861A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of inorganic pigment preparation, and in particular to a method for preparing a cobalt-based powder material. Background Art
[0002] Cobalt-based pigments are an important class of inorganic pigments, including cobalt phosphate, cobalt oxide, cobalt ferrite, etc. They usually have bright colors, excellent weather resistance, light resistance, heat resistance, acid and alkali resistance, etc., and are widely used in ceramics, glass, coatings, construction, rubber, art pigments and other fields. However, there are still bottlenecks in the production and application of cobalt-based pigments.
[0003] For example, in the preparation process of high-end cobalt blue pigment, high-temperature solid-phase reaction will cause grain enlargement and agglomeration. In addition, the traditional solid-phase reaction method generally uses cobalt hydroxide, carbonate or oxide as raw materials, mixes according to the corresponding amount of substances, and calcines at high temperature (for example, 700-1000°C) to obtain the product. This method mainly uses mechanical means to mix and refine the raw materials, which can easily lead to uneven microscopic distribution of the raw materials, making it difficult for the diffusion process to proceed smoothly. At the same time, impurities are easily introduced during the mechanical refinement process, and the calcination temperature is high, the calcination time is long, the reaction steps are many, the energy consumption is large, the stoichiometric ratio is difficult to control, and the impurities are easy to form. There are large differences in the composition, structure, and particle size distribution of the products. Therefore, the prepared cobalt-based materials have poor morphological uniformity, the color is difficult to effectively control, and the energy consumption is large. The coprecipitation method generally involves mixing chemical raw materials in a solution state, adding an appropriate precipitant to the solution, and coprecipitating the components that have been evenly mixed in the solution in a stoichiometric ratio, or first reacting and precipitating an intermediate product in the solution, and then calcining and decomposing it to prepare a fine powder. This method can obtain cobalt-based powder at a lower temperature, but the production process is complicated, and the precipitation process is prone to component segregation, affecting the purity of the product.
[0004] In summary, existing cobalt-based powder materials have problems such as poor dispersibility, poor morphology controllability, and single color. The preparation methods have disadvantages such as high energy consumption and complex production processes, which limit the widespread promotion and application of this type of material. Summary of the invention
[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a cobalt-based powder material with a simple preparation method and high purity.
[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:
[0007] A method for preparing a cobalt-based powder material comprises the following steps:
[0008] S1. Adding a cobalt salt solution, a hydrogen phosphate solution, and a precipitant solution to an alcohol organic solvent in sequence under stirring, and adjusting the pH value to 9 to 11 with aqueous ammonia to obtain a mixture;
[0009] S2. The mixture is subjected to a solvent thermal reaction at a temperature of 120 to 200° C. and a pressure of 0.3 to 4 MPa for 4 to 72 hours, and then centrifuged, washed, and dried to obtain a bluish-purple cobalt-based powder material.
[0010] As a further improvement to the above technical solution:
[0011] In step S1, the molar ratio of cobalt ions in the cobalt salt solution to phosphate ions in the phosphate solution is 1:1-5.
[0012] In step S1, the cobalt salt is a cobalt oxalate solution, the hydrogen phosphate solution is a disodium hydrogen phosphate solution, and the precipitant solution is a sodium carbonate solution.
[0013] The concentration of the cobalt oxalate solution is 0.8-1.2 mol / L, the concentration of the disodium hydrogen phosphate solution is 0.8-1.0 mol / L, and the concentration of the sodium carbonate solution is 0.8-1.2 mol / L. The cobalt salt solution, hydrogen phosphate solution, and precipitant solution of the present invention are all low-concentration solutions. If a high-concentration solution is used, many impurities will appear in the product.
[0014] In step S1, the alcohol organic solvent is a mixed solvent of isopropanol and ethanol.
[0015] The volume ratio of the isopropanol to the ethanol is 5:1.
[0016] In step S1, the stirring speed is 100-300 rpm.
[0017] In step S2, the temperature of the solvent thermal reaction is 150-200° C. and the time is 15-28 hours.
[0018] In step S2, the cleaning is performed by ultrasonic washing with isopropanol for multiple times.
[0019] In step S2, the chemical formula of the cobalt-based powder material is NH4CoPO4·H2O.
[0020] Compared with the prior art, the advantages of the present invention are:
[0021] A method for preparing a cobalt-based powder material of the present invention comprises mixing a cobalt salt solution, a hydrogen phosphate solution and a precipitant solution with an alcohol organic solvent in sequence, and then synthesizing a blue-purple cobalt-based powder material by a solvothermal method. The preparation method is based on a dissolution-recrystallization mechanism. First, a solid solute is dissolved in a hydrothermal medium and enters the solution in the form of ions and molecular clusters. Under high temperature and high pressure conditions, strong convection is generated in the upper and lower parts of the solution, and these ions, molecules or ion clusters are transported to a growth zone (i.e., a low temperature zone) where seed crystals are placed to form a supersaturated solution, followed by crystallization. The preparation method of the present invention is simple, and the prepared product has the advantages of highly controllable color, uniform morphology, narrow particle size distribution, high purity, etc., and can be used for inorganic pigments. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a digital photograph of the cobalt-based powder material prepared in Example 1.
[0023] Figure 2 This is the XRD pattern of the cobalt-based powder material prepared in Example 1.
[0024] Figure 3 This is a SEM image of the cobalt-based powder material prepared in Example 1.
[0025] Figure 4 This is a digital photograph of the cobalt-based powder material prepared in Comparative Example 1.
[0026] Figure 5 This is a digital photograph of the cobalt-based powder material prepared in Comparative Example 2.
[0027] Figure 6 It is a process flow chart of an embodiment. DETAILED DESCRIPTION
[0028] The present invention will be described in further detail below. Unless otherwise specified, the instruments or materials used in the present invention are commercially available.
[0029] Example 1
[0030] like Figure 6 As shown, the method for preparing the cobalt-based powder material of this embodiment comprises the following steps:
[0031] S1, 25mL isopropanol and 5mL ethanol are mixed, and magnetic stirring is carried out for 5min. Continuing under the effect of magnetic stirring, 8mL of cobalt acetate solution with a molar concentration of 0.8mol / L, 3.5mL of disodium hydrogen phosphate with a molar concentration of 1mol / L, and 1mL of sodium carbonate solution with a molar concentration of 1mol / L are added successively, and stirring is continued for 25min after completion of the addition, and then ammonia is added dropwise to adjust the pH to 9.4, and the stirring speed of the process is 240rpm. In the present invention, ammonia is not only used as a pH adjusting agent, but also as a source of ammonium ions in the final product NH4CoPO4·H2O, and participates in the reaction.
[0032] S2. The mixture was transferred to a 100 mL stainless steel autoclave, placed in a forced air oven at 150°C for reaction for 4 hours. After the reaction was completed, the autoclave was taken out to allow it to cool naturally, the solid product was collected by centrifugation, and ultrasonically washed three times with isopropanol to remove by-products. The product was vacuum dried at 80°C and sealed for storage.
[0033] In the present invention, the stainless steel high-pressure reactor provides pressure conditions for the reaction of the solution and promotes the generation of the reaction. During the entire reaction process, the pressure in the reactor changes continuously between 0.3 and 4 MPa. When the reaction starts, the mixture is simply sealed in the reactor. If there is no pressure condition during the entire reaction process, no solid product can be obtained, only a solution.
[0034] Figure 1 This is a digital photo of the cobalt-based powder material prepared in this example. It can be seen that the powder prepared in this example is bluish purple in color and has a fine texture.
[0035] Figure 2 The XRD diagram of the cobalt-based powder material prepared in this embodiment shows that the main component of the powder material prepared in this embodiment is NH4CoPO4·H2O, the crystallinity is high, there is no obvious impurity component, and the purity is high.
[0036] Figure 3 This is a SEM image of the cobalt-based powder material prepared in this embodiment. It can be seen that the powder material prepared in this embodiment is a flower-like structure with uniform morphology.
[0037] Example 2
[0038] The method for preparing the cobalt-based powder material of this embodiment comprises the following steps:
[0039] S1. Mix 20 mL of isopropanol and 4 mL of ethanol and stir magnetically for 15 min. Under magnetic stirring, add 15 mL of 1.2 mol / L cobalt acetate solution, 12 mL of 0.8 mol / L disodium hydrogen phosphate, and 1 mL of 1 mol / L sodium carbonate solution in sequence. After the addition is complete, continue stirring for 25 min, then add 28% ammonia water dropwise to adjust the pH to 9.6. The stirring rate of the process is 240 rpm.
[0040] S2. Transfer the mixture to a 100 mL stainless steel high-pressure reactor (pressure between 0.3 and 4 MPa), place it in a forced air oven at 120°C for reaction for 20 hours. After the reaction is completed, take out the reactor and let it cool down naturally. Collect the solid product by centrifugation and ultrasonically wash it three times with isopropanol to remove by-products. Dry the product in a vacuum oven at 80°C and seal it for storage.
[0041] The powder prepared in this embodiment is blue-purple in color, has a fine texture, and has the same chemical composition and structure as those in Example 1.
[0042] Example 3
[0043] The method for preparing the cobalt-based powder material of this embodiment comprises the following steps:
[0044] S1. Mix 30 mL of isopropanol and 6 mL of ethanol and stir magnetically for 6 min. Under magnetic stirring, add 14 mL of cobalt acetate solution with a molar concentration of 1.2 mol / L, 12.5 mL of disodium hydrogen phosphate with a molar concentration of 0.8 mol / L, and 1 mL of 1 mol / L sodium carbonate solution in sequence. After the addition is completed, continue stirring for 22 min, then add ammonia water dropwise to adjust the pH to 10.4. The stirring rate of this process is 200 rpm.
[0045] S2. Transfer the mixture to a 100 mL stainless steel high-pressure reactor (pressure between 0.3 and 4 MPa), place it in a forced air oven at 160°C for reaction for 7 hours. After the reaction is completed, take out the reactor and let it cool down naturally. Collect the solid product by centrifugation and ultrasonically wash it three times with isopropanol to remove by-products. Dry the product in a vacuum oven at 80°C and store it in a sealed container.
[0046] The powder prepared in this embodiment is blue-purple in color, has a fine texture, and has the same chemical composition and structure as those in Example 1.
[0047] Example 4
[0048] The method for preparing the cobalt-based powder material of this embodiment comprises the following steps:
[0049] S1. Mix 22 mL of isopropanol and 4.4 mL of ethanol and stir magnetically for 8 min. Under magnetic stirring, add 15 mL of 1.0 mol / L cobalt acetate solution, 6.8 mL of 1.0 mol / L disodium hydrogen phosphate, and 1 mL of 1 mol / L sodium carbonate solution in sequence. After the addition is complete, continue stirring for 20 min, then add ammonia water dropwise to adjust the pH to 9.8. The stirring rate of this process is 200 rpm.
[0050] S2. Transfer the mixture to a 100 mL stainless steel high-pressure reactor (pressure between 0.3 and 4 MPa), place it in a forced air oven at 160°C for reaction for 12 hours. After the reaction is completed, take out the reactor and let it cool down naturally. Collect the solid product by centrifugation and ultrasonically wash it three times with isopropanol to remove by-products. Dry the product in a vacuum oven at 80°C and seal it for storage.
[0051] The powder prepared in this embodiment is blue-purple in color, has a fine texture, and has the same chemical composition and structure as those in Example 1.
[0052] Comparative Example 1
[0053] The preparation method of the cobalt-based powder in this comparative example is substantially the same as that in Example 1, except that in step S1, ammonia water is added dropwise to adjust the pH to 8, and other reaction conditions are the same.
[0054] The resulting product is uneven in color, as shown in the optical photograph. Figure 4 shown.
[0055] Comparative Example 2
[0056] The preparation method of the cobalt-based powder in this comparative example is substantially the same as that in Example 4, except that in step S1, ammonia water is added dropwise to adjust the pH to 8.5, and other reaction conditions are the same.
[0057] The resulting product is uneven in color, as shown in the optical photograph. Figure 5 shown.
[0058] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.
Claims
1. A method for preparing a cobalt-based powder material, characterized in that: The following steps are involved: S1. Adding a cobalt salt solution, a hydrogen phosphate solution, and a precipitant solution to an alcohol organic solvent in sequence under stirring, and adjusting the pH value to 9 to 11 with aqueous ammonia to obtain a mixture; S2. The mixture is subjected to a solvent thermal reaction at a temperature of 120 to 200° C. and a pressure of 0.3 to 4 MPa for 4 to 72 hours, and then centrifuged, washed, and dried to obtain a bluish-purple cobalt-based powder material.
2. The method for preparing a cobalt-based powder material according to claim 1, characterized in that: In step S1, the molar ratio of cobalt ions in the cobalt salt solution to phosphate ions in the phosphate solution is 1:1-5.
3. The method for preparing a cobalt-based powder material according to claim 2, characterized in that: In step S1, the cobalt salt is a cobalt oxalate solution, the hydrogen phosphate solution is a disodium hydrogen phosphate solution, and the precipitant solution is a sodium carbonate solution.
4. The method for preparing a cobalt-based powder material according to claim 3, characterized in that: The concentration of the cobalt oxalate solution is 0.8-1.2 mol / L, the concentration of the disodium hydrogen phosphate solution is 0.8-1.0 mol / L, and the concentration of the sodium carbonate solution is 0.8-1.2 mol / L.
5. The method for preparing a cobalt-based powder material according to claim 1, characterized in that: In step S1, the alcohol organic solvent is a mixed solvent of isopropanol and ethanol.
6. The method for preparing a cobalt-based powder material according to claim 5, characterized in that: The volume ratio of the isopropanol to the ethanol is 5:
1.
7. The method for preparing a cobalt-based powder material according to any one of claims 1 to 6, characterized in that: In step S1, the stirring speed is 100-300 rpm.
8. The method for preparing a cobalt-based powder material according to any one of claims 1 to 6, characterized in that: In step S2, the temperature of the solvent thermal reaction is 150-200° C. and the time is 15-28 hours.
9. The method for preparing a cobalt-based powder material according to any one of claims 1 to 6, characterized in that: In step S2, the cleaning is performed by ultrasonic washing with isopropanol for multiple times.
10. The method for preparing a cobalt-based powder material according to any one of claims 1 to 6, characterized in that: In step S2, the chemical formula of the cobalt-based powder material is NH4CoPO4·H2O.