Preparation method of spherical nano cobaltosic oxide

Abstract

The invention discloses a preparation method of spherical nano cobaltosic oxide, which comprises the following steps: by taking cobalt nitrate, sodium hydroxide and ammonia water as raw materials, preparing micron-sized cobalt hydroxide particles mixed with a large amount of ammonium radicals by adopting a low-pH and high-ammonia synthesis process, and then carrying out oxidation reaction on the cobalt hydroxide particles and compressed air in a high-temperature strong-alkali solution to obtain the spherical nano cobaltosic oxide. The preparation method comprises the following steps: preparing a cobaltosic oxide nano-particle by using a one-step method to obtain micron-sized cobaltosic oxide particles consisting of spherical particles, then washing, drying and crushing the micron-sized cobaltosic oxide particles to obtain a nano spherical cobaltosic oxide product, so that the cobaltosic oxide prepared by the process is nano-sized and is spherical in microstructure, and the process has simple requirements on equipment and is suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation, and in particular relates to a method for preparing spherical nano cobalt tetroxide. Background Art

[0002] As an important nanomaterial, spherical nanocobalt oxide (Co3O4) has shown broad application prospects in lithium-ion batteries, magnetic materials, catalysts, etc. due to its unique physical and chemical properties. With the continuous development of nanotechnology, the preparation technology, properties and application research of spherical nanocobalt oxide have also made significant progress.

[0003] There are many methods for preparing spherical nano-cobalt tetroxide, mainly including physical and chemical methods. Although physical methods such as ball milling and vapor deposition can produce nano-scale cobalt tetroxide, it is difficult to control its morphology and particle size distribution. In contrast, chemical methods such as coprecipitation, sol-gel, and hydrothermal methods have higher controllability and repeatability, and are therefore more widely used in practical applications.

[0004] At present, the industry mainly prepares spherical nano-cobalt tetroxide products through sol-gel method, hydrothermal method, etc., but these preparation methods are generally complicated in process, have high requirements on raw materials and production equipment, and are not conducive to large-scale production. Summary of the invention

[0005] In order to overcome the shortcomings of the existing production process, the purpose of the present invention is to provide a method for preparing spherical nano-cobalt tetroxide with a simple and easy-to-control production process and easy industrial production.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A method for preparing spherical nano-cobalt tetroxide, the specific steps of the method are as follows: a. Liquid preparation Using cobalt nitrate as raw material, a cobalt solution with a cobalt concentration of 100-120 g / L is prepared as solution A; a sodium hydroxide solution with a concentration of 180-220 g / L is prepared as solution B; and a 90-100 g / L ammonia solution is prepared as solution C; b. Synthesis reaction At the beginning of the synthesis reaction, the A, B, and C solutions are added to the reactor in parallel and the synthesis reaction is carried out under stirring. During the reaction, the flow rate of the A and C solutions, the reaction pH value, the reaction temperature, the stirring intensity, and the reaction time are strictly controlled, and the flow rate of the B solution is dynamically adjusted according to the reaction pH value; c. Oxidation After the synthesis reaction is completed, the solid and liquid are separated, and the solid slag sample is put into a reactor filled with solution B to undergo oxidation reaction with compressed air; d. Washing After the oxidation reaction is completed, the prepared material is washed; e. Drying Drying the washed material; f. Broken The dried micron-sized cobalt tetroxide is crushed to obtain a nano-spherical cobalt tetroxide product.

[0007] In the step (b), the reactor is 10 m 3 The reactor is characterized in that the flow rates of solutions A, B and C, the reaction pH value, the reaction temperature, the stirring intensity and the reaction time are strictly controlled during the reaction process, wherein the flow rate of solution A is 800 L / h, the flow rate of solution B is dynamically adjusted according to the synthetic pH value, the flow rate of solution C is 100 L / h, the ammonia content in the reactor during the synthesis process is controlled to be 6-7 g / L, the reaction pH value is 7.0-7.2, the reaction temperature is 70-75° C., the stirring intensity of the reactor is 30-35 Hz, and the reaction time is 4-6 h.

[0008] In the step (c), the oxidation process reactor is 5m 3 Reactor, the solid content of the prepared oxidation slurry is 30~40%, the oxidation conditions are temperature 80~90℃, and the compressed air flow rate is 40~60m 3 / h, stirring intensity is 30~35Hz, and oxidation time is 2~3h.

[0009] In the step (d), the washing equipment is a centrifuge, the filter cloth specification is 6000 mesh filter cloth, the washing liquid is a 10-15 g / L citric acid solution with a temperature of ≥80°C, and the Na content in the cobalt hydroxide after washing is ≤0.02%.

[0010] The drying equipment in step (e) is a flash evaporator, and the drying temperature is 200-300°C.

[0011] In the step (f), the crushing equipment is a jet mill, and the crushing pressure is 0.6-0.8 MPa.

[0012] In the step (f), the spherical nano-cobalt oxide has an index of D50≤0.5 μm and a microscopic morphology of spherical particles.

[0013] The characteristics of the method are as follows: the method adopts a high ammonia (6-7 g / L) and low pH (7.0-7.2) synthesis process to prepare cobalt hydroxide, and the prepared cobalt hydroxide particles are mixed with a large amount of ammonium ions, which are released during the high temperature and high pH oxidation process, so that the cobalt hydroxide is oxidized into micron-sized cobalt oxide particles composed of spherical primary particles, and then washed, dried and crushed to obtain spherical nano cobalt oxide products. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flow chart of the preparation process of the present invention.

[0015] Figure 2 This is a microscopic morphology of the spherical nano-cobalt oxide prepared in Example 1.

[0016] Figure 3 This is a microscopic morphology of the spherical nano-cobalt oxide prepared in Example 2.

[0017] Figure 4 This is a microscopic morphology of the spherical nano-cobalt oxide prepared in Example 3.

[0018] Figure 5 This is a microscopic morphology of micron-sized cobalt tetroxide before crushing in Example 1. DETAILED DESCRIPTION

[0019] The following will be described clearly and completely in conjunction with 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.

[0020] Embodiment 1 Production steps see Figure 1 , which will not be described here. The specific parameters in each step are as follows: With cobalt nitrate as raw material, a cobalt solution with a cobalt concentration of 100 g / L was prepared as solution A; a sodium hydroxide solution with a concentration of 180 g / L was prepared as solution B; and an ammonia solution with a concentration of 90 g / L was prepared as solution C.

[0021] The synthesis reaction was carried out at 10m 3 A, B, and C solutions were added to the reactor in parallel for synthesis. During the synthesis, the flow rate of solution A was strictly controlled to be 800 L / h, the flow rate of solution B was about 600 L / h, and the specific flow rate was dynamically adjusted according to the reaction pH value. The flow rate of solution C was 100 L / h. During the reaction process, the slurry ammonia concentration was about 6 g / L, the reaction pH value was controlled at 7.0-7.2, the reaction temperature was 70°C, the stirring intensity of the reactor was 30 Hz, and the reaction time was 4 h.

[0022] After the synthesis reaction is completed, stop adding liquid and separate the solid and liquid of the synthetic slurry. 3 The mixture is mixed into a 30% solid content slurry in the reactor, and then the oxidation reaction is started under the action of compressed air. The oxidation conditions are a temperature of 80-82°C and a compressed air flow rate of 40m 3 / h, stirring intensity is 30Hz, and oxidation time is 2h.

[0023] After the oxidation reaction is completed, the slurry is washed using a centrifuge and a 6000-mesh filter cloth. The washing liquid is a 10 g / L citric acid solution at ≥80°C. When the Na% in the cobalt hydroxide is ≤0.02%, the washing is completed.

[0024] The washed micron-sized cobalt tetroxide was dried by flash evaporator at 200°C. The morphology of micron-sized cobalt tetroxide is as follows: Figure 5 shown.

[0025] The dried material is crushed on a jet crusher with a crushing pressure of 0.6Mpa.

[0026] The D50 of the prepared spherical nano-cobalt oxide is 0.41µm, and the microscopic morphology is shown in the attached Figure 2 .

[0027] Embodiment 2 The production steps are the same as above and will not be repeated here. The specific parameters in each step are as follows: With cobalt nitrate as raw material, a cobalt solution with a cobalt concentration of 110 g / L was prepared as solution A; a sodium hydroxide solution with a concentration of 200 g / L was prepared as solution B; and an ammonia solution with a concentration of 95 g / L was prepared as solution C.

[0028] The synthesis reaction was carried out at 10m 3 A, B, and C solutions were added to the reactor in parallel for synthesis. During the synthesis, the flow rate of solution A was strictly controlled to be 800 L / h, the flow rate of solution B was about 600 L / h, and the specific flow rate was dynamically adjusted according to the reaction pH value. The flow rate of solution C was 100 L / h. During the reaction process, the slurry ammonia concentration was about 6.4 g / L, the reaction pH value was controlled at 7.0-7.2, the reaction temperature was 72°C, the stirring intensity of the reactor was 32 Hz, and the reaction time was 5 h.

[0029] After the synthesis reaction is completed, stop adding liquid and separate the solid and liquid of the synthetic slurry. 3 The mixture was mixed into a 35% solid content slurry in the reactor, and then the oxidation reaction was started under the action of compressed air. The oxidation conditions were a temperature of 84-86°C and a compressed air flow rate of 50m 3 / h, stirring intensity is 32Hz, and oxidation time is 2.5h.

[0030] After the oxidation reaction is completed, the slurry is washed using a centrifuge and a 6000-mesh filter cloth. The washing liquid is a 12 g / L citric acid solution at ≥80°C. When the Na% in the cobalt hydroxide is ≤0.02%, the washing is completed.

[0031] The washed micron-sized cobalt tetroxide is dried by a flash evaporator at a drying temperature of 250°C.

[0032] The dried material is crushed on a jet crusher with a crushing pressure of 0.7Mpa.

[0033] The D50 of the prepared spherical nano-cobalt oxide is 0.39µm, and the microscopic morphology is shown in the attached Figure 3 .

[0034] Embodiment 3 The production steps are the same as above and will not be repeated here. The specific parameters in each step are as follows: With cobalt nitrate as raw material, a cobalt solution with a cobalt concentration of 120 g / L is prepared as solution A; a sodium hydroxide solution with a concentration of 220 g / L is prepared as solution B; and an ammonia solution with a concentration of 100 g / L is prepared as solution C.

[0035] The synthesis reaction was carried out at 10m 3 A, B, and C solutions were added to the reactor in parallel for synthesis. During the synthesis, the flow rate of solution A was strictly controlled to be 800 L / h, the flow rate of solution B was about 590 L / h, and the specific flow rate was dynamically adjusted according to the reaction pH value. The flow rate of solution C was about 100 L / h. During the reaction process, the slurry ammonia concentration was about 6.7 g / L, the reaction pH value was controlled at 7.0-7.2, the reaction temperature was 75°C, the stirring intensity of the reactor was 35 Hz, and the reaction time was 6 h.

[0036] After the synthesis reaction is completed, stop adding liquid and separate the solid and liquid of the synthetic slurry. 3 The mixture is mixed into a slurry with a solid content of 40% in the reactor, and then the oxidation reaction is started under the action of compressed air. The oxidation conditions are a temperature of 88-90°C and a compressed air flow rate of 60m 3 / h, stirring intensity is 35Hz, and oxidation time is 3h.

[0037] After the oxidation reaction is completed, the slurry is washed using a centrifuge and a 6000-mesh filter cloth. The washing liquid is a 15 g / L citric acid solution at ≥80°C. When the Na% in the cobalt hydroxide is ≤0.02%, the washing is completed.

[0038] The washed micron-sized cobalt tetroxide is dried by a flash evaporator at a drying temperature of 300°C.

[0039] The dried material is crushed on a jet crusher with a crushing pressure of 0.8Mpa.

[0040] The D50 of the prepared spherical nano-cobalt oxide is 0.18µm, and the microscopic morphology is shown in the attached Figure 4 .

Claims

1. A method for preparing spherical nano-cobalt tetroxide, characterized in that: The specific steps are as follows: a. Liquid preparation Using cobalt nitrate as raw material, a cobalt solution with a cobalt concentration of 100-120 g / L is prepared as solution A; a sodium hydroxide solution with a concentration of 180-220 g / L is prepared as solution B; and a 90-100 g / L ammonia solution is prepared as solution C; b. Synthesis reaction At the beginning of the synthesis reaction, the A, B, and C solutions are added to the reactor in parallel, and the synthesis reaction is carried out under stirring; During the reaction, the flow rates of solution A and C, reaction pH value, reaction temperature, stirring intensity and reaction time are strictly controlled, and the flow rate of solution B is dynamically adjusted according to the reaction pH value; c. Oxidation After the synthesis reaction is completed, the solid and liquid are separated, and the solid slag sample is put into a reactor filled with solution B to undergo oxidation reaction with compressed air; d. Washing After the oxidation reaction is completed, the prepared material is washed; e. Drying Drying the washed material; f. Broken The dried micron-sized cobalt tetroxide is crushed to obtain a nano-spherical cobalt tetroxide product.

2. The method for preparing spherical nano-cobalt oxide according to claim 1, characterized in that: In the step (b), the reactor is 10 m 3 The reactor is characterized in that the flow rates of solutions A, B and C, the reaction pH value, the reaction temperature, the stirring intensity and the reaction time are strictly controlled during the reaction process, wherein the flow rate of solution A is 800 L / h, the flow rate of solution B is dynamically adjusted according to the synthetic pH value, the flow rate of solution C is 100 L / h, the ammonia content in the reactor during the synthesis process is controlled to be 6-7 g / L, the reaction pH value is 7.0-7.2, the reaction temperature is 70-75° C., the stirring intensity of the reactor is 30-35 Hz, and the reaction time is 4-6 h.

3. The method for preparing spherical nano-cobalt oxide according to claim 1, characterized in that: In the step (c), the oxidation process reactor is 5m 3 The solid content of the prepared oxidation slurry is 30-40%, the oxidation conditions are 80-90℃, and the compressed air flow rate is 40-60m 3 / h, stirring intensity is 30~35Hz, and oxidation time is 2~3h.

4. The method for preparing spherical nano-cobalt tetroxide according to claim 1, characterized in that: In the step (d), the washing equipment is a centrifuge, the filter cloth specification is 6000 mesh filter cloth, the washing liquid is a 10-15 g / L citric acid solution with a temperature of ≥80°C, and the Na content in the cobalt hydroxide after washing is ≤0.02%.

5. The method for preparing spherical nano-cobalt tetroxide according to claim 1, characterized in that: The drying equipment in step (e) is a flash evaporator, and the drying temperature is 200-300°C.

6. The method for preparing spherical nano-cobalt tetroxide according to claim 1, characterized in that: In the step (f), the crushing equipment is a jet mill, and the crushing pressure is 0.6-0.8 MPa.

7. The method for preparing spherical nano-cobalt tetroxide according to claim 1, characterized in that: In the step (f), the spherical nano-cobalt oxide has an index of D50≤0.5 μm and a microscopic morphology of spherical particles.

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