Micron-sized spherical cobaltosic oxide and preparation method thereof

Abstract

The invention discloses micron-sized spherical cobaltosic oxide and a preparation method thereof.The preparation method comprises the steps that a cobalt salt solution and a precipitator solution are stirred and mixed, then stirring is stopped, a reaction is conducted, and insoluble substances are collected; and carrying out heat treatment on the insoluble substance to obtain the micron-sized spherical cobaltosic oxide. According to the method, continuous feeding control is not needed, structural regulators such as a chelating agent, a surfactant and an oxidizing agent do not need to be added, additional equipment is not needed, stirring is stopped after the cobalt salt solution and the precipitant solution are stirred and mixed, the mild precipitation reaction is carried out, and energy loss caused by continuous feeding and stirring is avoided. The cobaltosic oxide prepared by the method has good dispersity, uniform particle size distribution and a loose and porous structure, and presents a perfect sphere.

Description

Technical Field

[0001] The invention relates to the technical field of spherical cobalt oxide, and in particular to micron-sized spherical cobalt oxide and a preparation method thereof. Background Art

[0002] Cobalt tetroxide is widely used in varistors, chemical sensors, lithium-ion batteries, supercapacitors, photocatalysis, heterogeneous catalysis, adsorption and other fields due to its unique physical and chemical properties. Its preparation methods include uniform precipitation method, solid phase reaction method, mechanical ball milling method, wet precipitation-calcination method, and hydrothermal method. At the same time, cobalt tetroxide with different morphological structures has certain special properties, such as crystal face effect, size effect, quantum effect, etc., which makes researchers turn their focus to the precise control of the morphology and size of cobalt tetroxide. For the control of crystals, its forming process can be divided into nucleation and growth stages, which are controlled by kinetics and thermodynamics. How to control the kinetic and thermodynamic parameters to prepare micron-sized cobalt tetroxide with specific morphology has always been a difficult point.

[0003] There are some methods that have successfully prepared micron-sized spherical cobalt tetroxide. For example, CN106335930A discloses a porous spherical cobalt tetroxide electrode material and its preparation method and application, wherein cobalt salt, urea and solvent are mixed and then atomized and heated to obtain spherical cobalt tetroxide. The spherical cobalt tetroxide prepared by this method has a porous structure, but the particle size is small, only 1-2μm, and the atomization treatment requires additional equipment, which is not suitable for industrial production. CN109422293A discloses a method for preparing a micron-sized spherical cobalt tetroxide material, wherein cobalt salt, polyethylene glycol and alcohol are dissolved in deionized water to form a uniform solution and then subjected to hydrothermal reaction. This method has high sphericity and dispersion, but an additional surfactant, polyethylene glycol, is added, and hydrothermal reaction is not suitable for mass production. CN105399148A discloses a method for preparing large-particle-size, high-density spherical cobalt tetroxide, which comprises a cobalt salt solution and an ammonium carbonate or ammonium bicarbonate solution for precipitation reaction, continuous feeding and separation until the cobalt carbonate grows to a target particle size, and then pyrolysis to obtain large-particle-size, high-density cobalt tetroxide. However, this method requires continuous feeding, solid-liquid separation, and separate kettle operation, and the process is very cumbersome.

[0004] It is necessary to provide a method for preparing micron-sized spherical cobalt oxide without lengthy steps or additional additives. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method for preparing micron-sized spherical cobalt oxide, comprising: The cobalt salt solution and the precipitant solution are stirred and mixed, and then the stirring is stopped to react and collect the insoluble matter; The insoluble matter is heat treated to obtain micron-sized spherical 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 stirring is continued for 1-2 hours at a stirring speed of 300-500 rpm.

[0009] Furthermore, the reaction is continued at 35-60° C. for 5-25 h.

[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 micron-sized spherical cobalt oxide, which is obtained by using the above-mentioned preparation method of micron-sized spherical cobalt oxide.

[0013] The present invention also provides the application of the micron-sized spherical cobalt tetroxide in the fields of adsorption, catalysis, targeted therapy, sensing, pigments and fillers, and energy storage.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention does not need to continuously control the feed, does not need to add structural regulators such as chelating agents, surfactants, oxidants, and does not need additional equipment. The cobalt salt solution and the precipitant solution are stirred and mixed and then the stirring is stopped to perform a gentle precipitation reaction, thereby avoiding the energy loss caused by continuous feeding and stirring. The cobalt oxide prepared by the present invention has good dispersibility, uniform particle size distribution, loose and porous structure, and presents a relatively perfect spherical shape. 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 cobalt carbonate prepared in Example 2 of the present invention at a magnification of 10000 times is shown; Figure 2 The scanning electron microscope image of cobalt carbonate prepared in Example 2 of the present invention at a magnification of 30,000 times is shown; Figure 3 The scanning electron microscope image of the micron-sized spherical cobalt oxide prepared in Example 2 at a magnification of 10,000 times is shown; Figure 4 The scanning electron microscope image of the micron-sized spherical cobalt oxide prepared in Example 2 at a magnification of 30,000 times is shown; Figure 5 The scanning electron microscope image of the cobalt carbonate prepared in Comparative Example 1 at a magnification of 30,000 times is shown; Figure 6 The scanning electron microscope image of the micron-sized spherical cobalt oxide 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 micron-sized spherical cobalt oxide comprises the following steps: Step 1: Prepare 90 g / L cobalt sulfate solution with cobalt sulfate and water; prepare 100 g / L ammonium bicarbonate solution with ammonium bicarbonate and water. Step 2, adding the cobalt sulfate solution and the ammonium bicarbonate solution into a reaction kettle at a volume ratio of 1:1, stirring at a stirring speed of 300 rpm for 1 hour to mix evenly; then stopping stirring to obtain a reaction system; Step 3, close the reactor, keep the reaction system at 35°C for 25 hours to react, collect the insoluble matter after the reaction, put it into the filter press for filter pressing and washing, wash the impurity ion concentration to below 20ppm, and obtain wet material; Step 4: Place the wet material in a roller kiln for calcination, keep it at 145° C. for 5 hours, then heat it to 360° C. for 3 hours, and finally heat it to 720° C. for 5 hours, and finally cool it naturally to room temperature to obtain micron-sized spherical cobalt tetroxide.

[0020] Example 2 A method for preparing micron-sized spherical cobalt oxide comprises the following steps: Step 1: Prepare 110 g / L cobalt sulfate solution with cobalt sulfate and water; prepare 120 g / L ammonium bicarbonate solution with ammonium bicarbonate and water. Step 2, adding the cobalt sulfate solution and the ammonium bicarbonate solution into a reaction kettle at a volume ratio of 1:2, stirring at a stirring speed of 400 rpm for 1.5 hours to mix evenly; then stopping stirring to obtain a reaction system; Step 3, close the reactor, keep the reaction system at 45°C for 15 hours to react, collect the insoluble matter after the reaction, put it into the filter press for filter pressing and washing, wash the impurity ion concentration to below 20ppm, and obtain wet material; Step 4: Place the wet material in a roller kiln for calcination, keep it at 145° C. for 5 hours, then heat it to 360° C. for 3 hours, and finally heat it to 720° C. for 5 hours, and finally cool it naturally to room temperature to obtain micron-sized spherical cobalt tetroxide.

[0021] Example 3 A method for preparing micron-sized spherical cobalt oxide comprises the following steps: Step 1: Prepare 130 g / L cobalt sulfate solution with cobalt sulfate and water; prepare 140 g / L ammonium bicarbonate solution with ammonium bicarbonate and water. Step 2, adding the cobalt sulfate solution and the ammonium bicarbonate solution into a reaction kettle at a volume ratio of 1:3, stirring at a stirring speed of 450 rpm for 1.5 hours to mix evenly; then stopping stirring to obtain a reaction system; Step 3, close the reactor, keep the reaction system at a temperature of 50°C for 10 hours to react, collect the insoluble matter after the reaction, put it into a filter press for filter pressing and washing, wash the impurity ion concentration to less than 20ppm, and obtain a wet material; Step 4: Place the wet material in a roller kiln for calcination, keep it at 145° C. for 5 hours, then heat it to 360° C. for 3 hours, and finally heat it to 720° C. for 5 hours, and finally cool it naturally to room temperature to obtain micron-sized spherical cobalt tetroxide.

[0022] Example 4 A method for preparing micron-sized spherical cobalt oxide comprises the following steps: Step 1: Prepare 150 g / L cobalt sulfate solution with cobalt sulfate and water; prepare 160 g / L ammonium bicarbonate solution with ammonium bicarbonate and water. Step 2, adding the cobalt sulfate solution and the ammonium bicarbonate solution into a reaction kettle at a volume ratio of 1:4, stirring at a stirring speed of 500 rpm for 2 hours to mix evenly; then stopping stirring to obtain a reaction system; Step 3, the reaction kettle is closed, and the reaction system is kept at a temperature of 60° C. for 5 hours to react. After the reaction is completed, the insoluble matter is collected and pumped into a filter press for filter pressing and washing, and the concentration of impurity ions is washed to below 20 ppm to obtain a wet material; Step 4: Place the wet material in a roller kiln for calcination, keep it at 145° C. for 5 hours, then heat it to 360° C. for 3 hours, and finally heat it to 720° C. for 5 hours, and finally cool it naturally to room temperature to obtain micron-sized spherical cobalt tetroxide.

[0023] Example 5 A method for preparing micron-sized spherical cobalt oxide comprises the following steps: Step 1: Prepare 110 g / L cobalt chloride solution with cobalt chloride and water; prepare 120 g / L ammonium bicarbonate solution with sodium bicarbonate and water. Step 2, adding the cobalt chloride solution and the ammonium bicarbonate solution into a reaction kettle at a volume ratio of 1:2, stirring at a stirring speed of 400 rpm for 1 hour to mix evenly; then stopping stirring to obtain a reaction system; Step 3, close the reactor, keep the reaction system at 45°C for 15 hours to react, collect the insoluble matter after the reaction, put it into the filter press for filter pressing and washing, wash the impurity ion concentration to below 20ppm, and obtain wet material; Step 4: Place the wet material in a roller kiln for calcination, keep it at 145° C. for 5 hours, then heat it to 360° C. for 3 hours, and finally heat it to 720° C. for 5 hours, and finally cool it naturally to room temperature to obtain micron-sized spherical cobalt tetroxide.

[0024] Example 6 A method for preparing micron-sized spherical cobalt oxide comprises the following steps: Step 1: Prepare 110 g / L cobalt nitrate solution with cobalt nitrate and water; prepare 120 g / L potassium bicarbonate solution with potassium bicarbonate and water. Step 2, adding the cobalt sulfate solution and the ammonium bicarbonate solution into a reaction kettle at a volume ratio of 1:2, stirring at a stirring speed of 400 rpm for 1.5 hours to mix evenly; then stopping stirring to obtain a reaction system; Step 3, close the reactor, keep the reaction system at 45°C for 15 hours to react, collect the insoluble matter after the reaction, put it into the filter press for filter pressing and washing, wash the impurity ion concentration to below 20ppm, and obtain wet material; Step 4: Place the wet material in a roller kiln for calcination, keep it at 145° C. for 5 hours, then heat it to 360° C. for 3 hours, and finally heat it to 720° C. for 5 hours, and finally cool it naturally to room temperature to obtain micron-sized spherical cobalt tetroxide.

[0025] Example 7 A method for preparing micron-sized spherical cobalt oxide comprises the following steps: Step 1: Prepare a 110 g / L cobalt sulfate solution with cobalt sulfate and 50 wt% ethanol aqueous solution; prepare a 120 g / L ammonium bicarbonate solution with potassium bicarbonate and 50 wt% ethanol aqueous solution. Step 2, adding the cobalt sulfate solution and the ammonium bicarbonate solution into a reaction kettle at a volume ratio of 1:2, stirring at a stirring speed of 400 rpm for 1.5 hours to mix evenly; then stopping stirring to obtain a reaction system; Step 3, close the reactor, keep the reaction system at 45°C for 15 hours to react, collect the insoluble matter after the reaction, put it into the filter press for filter pressing and washing, wash the impurity ion concentration to below 20ppm, and obtain wet material; Step 4: Place the wet material in a roller kiln for calcination, keep it at 145° C. for 5 hours, then heat it to 360° C. for 3 hours, and finally heat it to 720° C. for 5 hours, and finally cool it naturally to room temperature to obtain micron-sized spherical cobalt tetroxide.

[0026] Comparative Example 1 A method for preparing micron-sized spherical cobalt oxide comprises the following steps: Step 1: Prepare 110 g / L cobalt chloride solution with cobalt sulfate and pure water; prepare 120 g / L ammonium bicarbonate solution with ammonium bicarbonate and pure water. Step 2, adding the cobalt sulfate solution and the ammonium bicarbonate solution into the reaction kettle at a volume ratio of 1:2, stirring at a stirring speed of 200 rpm for 1.5 hours to mix evenly; then stopping the stirring to obtain an intermediate precipitation system; Step 3, transfer the reaction system to a reactor, stir at a temperature of 45°C for 15 hours to react, collect the insoluble matter after the reaction, and put it into a filter press for filter pressing and washing, and wash the impurity ion concentration to below 20ppm to obtain a wet material; Step 4: Place the wet material in a roller kiln for calcination, keep it at 145° C. for 5 hours, then heat it to 360° C. for 3 hours, and finally heat it to 720° C. for 5 hours, and finally cool it naturally to room temperature to obtain micron-sized spherical cobalt tetroxide.

[0027] Test Case The microscopic morphologies of the wet material (i.e., cobalt carbonate) obtained in the preparation process of Example 2 and the prepared micron-sized spherical 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 obtained cobalt carbonate has a uniform size distribution, presents a relatively perfect spherical structure and does not have agglomeration; Figure 3 and Figure 4 It can be seen that the decomposition of cobalt carbonate during the calcination process makes the product cobalt oxide particles present a spherical structure with a loose and porous surface, retaining very good dispersibility, without agglomeration, and the calcination does not destroy the relatively perfect spherical structure. The average particle size of cobalt oxide is about 5μm. The microscopic morphology of micron-sized spherical cobalt oxide prepared in other examples was also observed, and similar to Example 2, all have a relatively perfect spherical structure.

[0028] The microscopic morphologies of the cobalt carbonate obtained in the preparation process of Comparative Example 1 and the micron-sized spherical cobalt oxide prepared are as follows: Figure 5 and Figure 6 As shown. It can be seen that the morphology of cobalt carbonate is uneven and there is obvious agglomeration. The cobalt oxide obtained by calcination and pyrolysis also retains these morphological characteristics, and the average particle size is only 1-2μm. Compared with Example 2, Comparative Example 1 uses a lower speed for mixing when the cobalt sulfate solution and the ammonium bicarbonate solution are mixed. This shows that keeping a high speed mixing and standing for the same time for growth is conducive to obtaining cobalt carbonate with regular morphology, reduced agglomeration, perfect spherical structure and larger particle size, thereby preparing more regular, better dispersed and larger particle size micron-sized spherical cobalt oxide.

[0029] In summary, the present invention does not require continuous control of feed, does not require the addition of structural regulators such as chelating agents, surfactants, oxidants, and does not require additional equipment. The cobalt salt solution and the precipitant solution are stirred and mixed and then the stirring is stopped to perform a gentle precipitation reaction, thereby avoiding the energy loss caused by continuous feeding and stirring. The cobalt oxide prepared by the present invention has good dispersibility, uniform particle size distribution, and a loose and porous structure, and presents a relatively perfect spherical shape. Based on the perfect spherical structure, the micron-sized spherical cobalt oxide prepared by the present invention has good application prospects in the fields of adsorption, catalysis, targeted therapy, sensing, pigments and fillers, and energy storage.

[0030] 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 micron-sized spherical cobalt oxide, characterized in that: include, The cobalt salt solution and the precipitant solution are stirred and mixed, and then the stirring is stopped to react and collect the insoluble matter; The insoluble matter is heat treated to obtain micron-sized spherical cobalt tetroxide.

2. The method for preparing micron-sized spherical cobalt oxide 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 micron-sized spherical cobalt oxide according to claim 1, characterized in that: The stirring is continued for 1-2 h at a stirring speed of 300-500 rpm.

4. The method for preparing micron-sized spherical cobalt oxide according to claim 1, characterized in that: The reaction was continued at 35-60°C for 5-25 h.

5. The method for preparing micron-sized spherical cobalt oxide 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 micron-sized spherical cobalt oxide 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 micron-sized spherical cobalt oxide, characterized in that: The micron-sized spherical cobalt oxide is obtained by the preparation method of any one of claims 1 to 6.

8. An application of the micron-sized spherical cobalt oxide as claimed in claim 7 in the fields of adsorption, catalysis, targeted therapy, sensing, pigments and fillers, and energy storage.

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