High-dispersion nanometer cobaltosic oxide and preparation method thereof

Abstract

The invention discloses high-dispersion nanometer cobaltosic oxide and a preparation method thereof.The preparation method comprises the steps that a cobalt salt solution and a precipitator solution are mixed and then stirred at a high speed, and an intermediate system is obtained; stirring the intermediate system at a low speed for continuous reaction, and then collecting insoluble substances; according to the preparation method disclosed by the invention, structure regulators such as a chelating agent, a surfactant and an oxidizing agent do not need to be added, and the high-dispersion nano cobaltosic oxide can be prepared by controlling the stirring speed after the cobalt salt solution and the precipitant solution are mixed; continuous feeding is not needed, low-speed stirring is mainly adopted for precipitation reaction, and energy consumption caused by continuous feeding and high-speed stirring is avoided. Meanwhile, the nano cobaltosic oxide prepared by the method is similar to a sphere, the agglomeration phenomenon is not obvious, and the particle size distribution is relatively concentrated.

Description

Technical Field

[0001] The invention relates to the technical field of cobalt tetroxide preparation, and in particular to highly dispersed nano cobalt tetroxide and a preparation method thereof. Background Art

[0002] Nano-cobalt oxide has a large specific surface area, high catalytic activity, good magnetism, high stability and can be used as a precursor material for lithium batteries. It is widely used in adsorption, catalysis, targeted therapy, pigments and fillers, and energy storage. Factors such as the morphology and particle size of nano-cobalt oxide are crucial to its application. For example, in order to increase the capacity of lithium cobalt oxide positive electrodes, cobalt oxide particles of different gradations need to be filled in proportion during preparation.

[0003] The preparation methods of nano-cobalt tetroxide mainly include sol-gel method, thermal decomposition method, chemical precipitation method, etc. Among them, chemical precipitation method has the highest industrial applicability and is currently the most commonly used method. For example, CN117886370A discloses a method for preparing nano-cobalt tetroxide, which uses cobalt solution, sodium hydroxide solution, ammonia solution and hydrogen peroxide solution as raw materials, and controls the amount of hydrogen peroxide solution added to make the partially synthesized Co(OH) 2 Oxidized to CoOOH, due to Co(OH) 2 Different from the crystal form of CoOOH, the synthesized micron-sized particles are composed of nano-sized Co(OH) 2 The nano-scale CoOOH is agglomerated by intermolecular forces, and then by increasing the solid-liquid ratio of the synthetic slurry, the micron-scale synthetic particles collide with each other and break into nano-scale Co(OH) 2 Mix the particles with CoOOH and then calcine to obtain nano-scale cobalt tetroxide products. This method is easy to control and industrialize, but the prepared cobalt tetroxide has obvious agglomeration and no obvious spherical particles. At the same time, the reaction time is long and the feed must be controlled all the time. The introduction of ammonia and hydrogen peroxide may increase the corrosion of the equipment and cause discomfort to the operators.

[0004] It is necessary to provide a simple, easy and uniform method for preparing nano-cobalt tetroxide. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method for preparing highly dispersed nano-cobalt oxide, comprising: The cobalt salt solution and the precipitant solution are mixed and stirred at high speed to obtain an intermediate system; The intermediate system was stirred at a low speed to continue the reaction, and then the insoluble matter was collected; The insoluble matter is heat-treated to obtain highly dispersed nano-cobalt tetroxide.

[0006] Further, the volume ratio of the cobalt salt solution to the precipitant solution is 1:1-4; The cobalt salt concentration in the cobalt salt solution is 90-150 g / L; The precipitant solution is a soluble bicarbonate solution with a concentration of 80-160 g / L.

[0007] In the present invention, the types of cobalt salt and soluble bicarbonate salt need not be strictly limited. For example, the cobalt salt can be at least one of cobalt sulfate, cobalt chloride, cobalt nitrate, etc.; the soluble bicarbonate salt can be at least one of potassium bicarbonate, sodium bicarbonate, ammonium bicarbonate, etc. The solvents of the cobalt salt solution and the precipitant solution do not need to be strictly limited, and are general solvents, such as at least one of water, ethanol, acetone, etc., preferably water.

[0008] Furthermore, the high-speed stirring is continued for 1-2 hours at a stirring speed of 300-500 rpm.

[0009] Furthermore, the low-speed stirring is continued for 4-12 hours at a temperature of 35-60° C. and a stirring speed of 10-50 rpm.

[0010] Furthermore, the collection is performed by filter pressing and washing to wash the impurity ions to a concentration lower than 20 ppm.

[0011] Furthermore, the heat treatment is carried out at 120-180° C. for 4-6 hours, then the temperature is raised to 300-400° C. for 2-5 hours, and finally the temperature is raised to 620-800° C. for 3-8 hours.

[0012] The present invention also provides a highly dispersed nanometer cobalt oxide, which is obtained by using the above-mentioned preparation method of highly dispersed nanometer cobalt oxide.

[0013] The present invention also provides the application of the above-mentioned highly dispersed nano-cobalt tetroxide in the fields of adsorption, catalysis, targeted therapy, pigments and fillers, and energy storage.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The invention does not need to add structure regulators such as chelating agents, surfactants, oxidants, etc., and can prepare highly dispersed nano cobalt oxide by controlling the stirring speed after mixing the cobalt salt solution and the precipitant solution. It does not need to feed continuously and mainly adopts low-speed stirring to carry out precipitation reaction, thereby avoiding the energy consumption caused by continuous feeding and high-speed stirring. At the same time, the nano cobalt oxide prepared by the invention has a spherical shape, no obvious agglomeration phenomenon, and a relatively concentrated particle size distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 The scanning electron microscope image of the cobalt carbonate prepared in Example 3 at a magnification of 20,000 times is shown; Figure 2 The scanning electron microscope image of the cobalt carbonate prepared in Example 3 at a magnification of 30,000 times is shown; Figure 3 The scanning electron microscope image of the highly dispersed nano-cobalt oxide prepared in Example 3 at a magnification of 20,000 times is shown; Figure 4 The scanning electron microscope image of the highly dispersed nano-cobalt tetroxide prepared in Example 3 at a magnification of 30,000 times is shown; Figure 5 The scanning electron microscope image of the nano-cobalt trioxide prepared in Comparative Example 1 at a magnification of 10,000 times is shown. DETAILED DESCRIPTION

[0017] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0018] The following will be combined with the specific embodiments of the present invention and the drawings of the specification to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example 1 A method for preparing highly dispersed nano-cobalt oxide comprises the following steps: S1, prepare 90g / L cobalt chloride solution with cobalt chloride and water; prepare 100g / L ammonium bicarbonate solution with ammonium bicarbonate and water; S2, adding the cobalt chloride solution and the ammonium bicarbonate solution into the reactor at a volume ratio of 1:1, and then stirring at a stirring speed of 300 rpm at room temperature for 1 hour to obtain an intermediate system; S3, maintaining the temperature of the intermediate system at 35°C and a stirring speed of 10 rpm for 12 hours, collecting the insoluble matter after the reaction, and putting it into a filter press for filter pressing and washing, washing the impurity ion concentration to below 20 ppm, and obtaining a wet material; S4. The wet material is placed in a roller kiln for calcination, kept at 150°C for 5 hours, then heated to 350°C for 3 hours, and finally heated to 750°C for 5 hours, and finally naturally cooled to room temperature to obtain highly dispersed nano-cobalt oxide.

[0020] Example 2 A method for preparing highly dispersed nano-cobalt oxide comprises the following steps: S1, prepare 120g / L cobalt chloride solution with cobalt chloride and water; prepare 130g / L ammonium bicarbonate solution with ammonium bicarbonate and water; S2, adding the cobalt chloride solution and the ammonium bicarbonate solution into the reactor at a volume ratio of 1:2, and then stirring at a stirring speed of 400 rpm at room temperature for 1 hour to obtain an intermediate system; S3, maintaining the temperature of the intermediate system at 45°C and a stirring speed of 30 rpm for 8 hours, collecting the insoluble matter after the reaction, and putting it into a filter press for filter pressing and washing, washing the impurity ion concentration to below 20 ppm, and obtaining a wet material; S4. The wet material is placed in a roller kiln for calcination, kept at 150°C for 5 hours, then heated to 350°C for 3 hours, and finally heated to 750°C for 5 hours, and finally naturally cooled to room temperature to obtain highly dispersed nano-cobalt oxide.

[0021] Example 3 A method for preparing highly dispersed nano-cobalt oxide comprises the following steps: S1, prepare 130g / L cobalt chloride solution with cobalt chloride and water; prepare 150g / L ammonium bicarbonate solution with ammonium bicarbonate and water; S2, adding the cobalt chloride solution and the ammonium bicarbonate solution into the reactor at a volume ratio of 1:3, and then stirring at a stirring speed of 450 rpm at room temperature for 1 hour to obtain an intermediate system; S3, maintaining the temperature of the intermediate system at 50°C and a stirring speed of 40 rpm for 6 hours, collecting the insoluble matter after the reaction, and putting it into a filter press for filter pressing and washing, washing the impurity ion concentration to below 20 ppm, and obtaining a wet material; S4. The wet material is placed in a roller kiln for calcination, kept at 150°C for 5 hours, then heated to 350°C for 3 hours, and finally heated to 750°C for 5 hours, and finally naturally cooled to room temperature to obtain highly dispersed nano-cobalt oxide.

[0022] Example 4 A method for preparing highly dispersed nano-cobalt oxide comprises the following steps: S1, prepare 150g / L cobalt chloride solution with cobalt chloride and water; prepare 160g / L ammonium bicarbonate solution with ammonium bicarbonate and water; S2, adding the cobalt chloride solution and the ammonium bicarbonate solution into the reactor at a volume ratio of 1:4, and then stirring at room temperature at a stirring speed of 400 rpm for 1 hour to obtain an intermediate system; S3, maintaining the temperature of the intermediate system at 60°C and a stirring speed of 50 rpm for 4 hours, collecting the insoluble matter after the reaction, and putting it into a filter press for filter pressing and washing, washing the impurity ion concentration to below 20 ppm, and obtaining a wet material; S4. The wet material is placed in a roller kiln for calcination, kept at 150°C for 5 hours, then heated to 350°C for 3 hours, and finally heated to 750°C for 5 hours, and finally naturally cooled to room temperature to obtain highly dispersed nano-cobalt oxide.

[0023] Example 5 A method for preparing highly dispersed nano-cobalt oxide comprises the following steps: S1, prepare 130g / L cobalt sulfate solution with cobalt sulfate and water; prepare 150g / L ammonium bicarbonate solution with ammonium bicarbonate and water; S2, adding the cobalt sulfate solution and the ammonium bicarbonate solution into the reactor at a volume ratio of 1:3, and then stirring at room temperature at a stirring speed of 450 rpm for 1 hour to obtain an intermediate system; S3, maintaining the temperature of the intermediate system at 50°C and a stirring speed of 40 rpm for 6 hours, collecting the insoluble matter after the reaction, and putting it into a filter press for filter pressing and washing, washing the impurity ion concentration to below 20 ppm, and obtaining a wet material; S4. The wet material is placed in a roller kiln for calcination, kept at 150°C for 5 hours, then heated to 350°C for 3 hours, and finally heated to 750°C for 5 hours, and finally naturally cooled to room temperature to obtain highly dispersed nano-cobalt oxide.

[0024] Example 6 A method for preparing highly dispersed nano-cobalt oxide comprises the following steps: S1, prepare 130g / L cobalt chloride solution with cobalt nitrate and water; prepare 150g / L ammonium bicarbonate solution with ammonium bicarbonate and water; S2, adding the cobalt nitrate solution and the ammonium bicarbonate solution into the reactor at a volume ratio of 1:3, and then stirring at room temperature at a stirring speed of 450 rpm for 1 hour to obtain an intermediate system; S3, maintaining the temperature of the intermediate system at 50°C and a stirring speed of 40 rpm for 6 hours, collecting the insoluble matter after the reaction, and putting it into a filter press for filter pressing and washing, washing the impurity ion concentration to below 20 ppm, and obtaining a wet material; S4. The wet material is placed in a roller kiln for calcination, kept at 150°C for 5 hours, then heated to 350°C for 3 hours, and finally heated to 750°C for 5 hours, and finally naturally cooled to room temperature to obtain highly dispersed nano-cobalt oxide.

[0025] Comparative Example 1 A method for preparing nano-cobalt tetroxide comprises the following steps: S1, prepare 130g / L cobalt chloride solution with cobalt chloride and water; prepare 150g / L ammonium bicarbonate solution with ammonium bicarbonate and water; S2, adding the cobalt chloride solution and the ammonium bicarbonate solution into the reactor at a volume ratio of 1:3, and then stirring at a stirring speed of 450 rpm at room temperature for 1 hour to obtain an intermediate system; S3, maintaining the temperature of the intermediate system at 50°C without stirring, reacting for 6 hours, collecting the insoluble matter after the reaction, and putting it into a filter press for filter pressing and washing, washing the impurity ion concentration to below 20ppm, and obtaining a wet material; S4. The wet material is placed in a roller kiln for calcination, kept at 150°C for 5 hours, then heated to 350°C for 3 hours, and finally heated to 750°C for 5 hours, and finally naturally cooled to room temperature to obtain nano-cobalt tetroxide.

[0026] Test Case The microscopic morphologies of the wet material (i.e., cobalt carbonate) obtained in the preparation process of Example 3 and the prepared highly dispersed nano-cobalt oxide were observed using a scanning electron microscope. The results are as follows: Figure 1 and Figure 2 as well as Figure 3 and Figure 4 As shown. Figure 1 and Figure 2 It can be seen that the agglomeration phenomenon of the obtained cobalt carbonate is not obvious, it has good dispersibility, and the particle size is concentrated in the range of 80-300nm. Figure 3 and Figure 4 It can be seen that the decomposition during the calcination process makes the cobalt oxide particles present a polyhedral spherical shape, and the overall particle size is relatively concentrated, ranging from 60 to 300 nm, and there are also a small amount of larger particles of about 500 nm, with good dispersion and no obvious agglomeration. The microscopic morphology of other embodiments was also observed, and similar to Example 3, all retained a spherical nanoparticle structure.

[0027] Figure 5 The microscopic morphology of the nano-cobalt oxide prepared in Comparative Example 1 is shown. It can be seen that its particle size is irregular compared with that in Example 3, with enhanced agglomeration and larger particle size. This shows that maintaining low-speed stirring after mixing is a key factor in preparing highly dispersed and uniform nano-cobalt oxide.

[0028] In summary, the present invention does not need to add chelating agents, surfactants, oxidants and other structural regulators. By controlling the stirring speed after the cobalt salt solution and the precipitant solution are mixed, highly dispersed nano cobalt tetroxide can be prepared. There is no need for continuous feeding and low-speed stirring is mainly used for precipitation reaction, which avoids the energy consumption caused by continuous feeding and high-speed stirring. At the same time, the nano cobalt tetroxide prepared by the present invention has a spherical shape, no obvious agglomeration phenomenon, and a relatively concentrated particle size distribution. On the whole, the present invention can synthesize nano-level cobalt tetroxide by directly mixing two solutions and maintaining low-speed stirring. There are few reaction steps, which is conducive to improving product stability; only low-speed stirring needs to be maintained during the reaction, and the reaction adopts one-step addition, and continuous feeding is not required, which greatly saves electricity costs and manpower maintenance costs; there are few reaction steps, no additional operations during the process, and the impact of external factors on product quality is reduced, and the efficiency of product quality management is improved.

[0029] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing highly dispersed nano-cobalt tetroxide, characterized in that: include, The cobalt salt solution and the precipitant solution are mixed and stirred at high speed to obtain an intermediate system; The intermediate system was stirred at a low speed to continue the reaction, and then the insoluble matter was collected; The insoluble matter is heat-treated to obtain highly dispersed nano-cobalt tetroxide.

2. The method for preparing highly dispersed nano-cobalt tetroxide according to claim 1, characterized in that: The volume ratio of the cobalt salt solution to the precipitant solution is 1:1-4; The cobalt salt concentration in the cobalt salt solution is 90-150 g / L; The precipitant solution is a soluble bicarbonate solution with a concentration of 80-160 g / L.

3. The method for preparing highly dispersed nano-cobalt tetroxide according to claim 1, characterized in that: The high-speed stirring is continued for 1-2 hours at a stirring speed of 300-500 rpm.

4. The method for preparing highly dispersed nano-cobalt tetroxide according to claim 1, characterized in that: The low-speed stirring is continued for 4-12 hours at a temperature of 35-60° C. and a stirring speed of 10-50 rpm.

5. The method for preparing highly dispersed nano-cobalt tetroxide according to claim 1, characterized in that: The collection is performed by filter pressing and washing to wash the impurity ions to a concentration lower than 20 ppm.

6. The method for preparing highly dispersed nano-cobalt tetroxide according to claim 1, characterized in that: The heat treatment is carried out at 120-180° C. for 4-6 hours, then the temperature is raised to 300-400° C. for 2-5 hours, and finally the temperature is raised to 620-800° C. for 3-8 hours.

7. A highly dispersed nano-cobalt tetroxide, characterized in that: The highly dispersed nano-cobalt tetroxide is obtained by the preparation method of any one of claims 1 to 6.

8. An application of the highly dispersed nano-cobalt tetroxide as claimed in claim 7 in the fields of adsorption, catalysis, targeted therapy, pigments and fillers, and energy storage.

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