MnOOH material as well as preparation method and application thereof

Abstract

The invention discloses a MnOOH material as well as a preparation method and application thereof, and relates to the technical field of inorganic materials. Manganese metal hydrolyzed ammonium acetate is used as a catalyst to synthesize Mn3O4 with high specific surface area, and then the Mn3O4 with high specific surface area and an oxidant are subjected to a hydrothermal reaction to synthesize gamma-type MnOOH. The preparation process provided by the invention can greatly reduce the reaction temperature and time, and is beneficial to large-scale production; and the agglomeration phenomenon of the MnOOH material can be effectively avoided, gamma-type MnOOH with high specific surface area can be obtained, the specific surface area reaches up to 150m < 2 > / g, and the gamma-type MnOOH has good chemical stability and electrochemical performance.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic materials, and in particular to a MnOOH material and a preparation method and application thereof. Background Art

[0002] In the fields of inorganic chemical material synthesis, materials science and nanotechnology, MnOOH is an important inorganic nanomaterial. Due to its unique physical and chemical properties, it is widely used in catalysis, adsorption, sensing and energy storage. MnOOH has a variety of crystal forms, such as α-MnOOH, β-MnOOH, γ-MnOOH, etc. The performance of MnOOH is closely related to its specific surface area, crystal form and chemical stability. MnOOH with different crystal forms has differences in adsorption performance, so it is necessary to select the appropriate crystal form according to application requirements. Therefore, how to synthesize MnOOH with high specific surface area, suitable crystal structure and good chemical stability is a hot spot and difficulty in current research.

[0003] In the existing technology, the synthesis methods of MnOOH mainly include chemical precipitation method, hydrothermal method, sol-gel method and microwave assisted method. The raw materials are mostly: high-sulfur manganese ore, potassium permanganate (KMnO 4 ), although these methods can synthesize MnOOH, they have the following problems:

[0004] (1) The reaction conditions are strict and require high temperature, high pressure or special environment, which not only increases the difficulty of synthesis, but also increases energy consumption, which is not conducive to large-scale production;

[0005] (2) The reaction process is complicated, often requiring multiple steps, and the synthesis steps are cumbersome, which reduces the synthesis efficiency;

[0006] (3) The specific surface area and morphology of the synthesized MnOOH are difficult to control and its chemical stability is poor, which limits its application range;

[0007] (4) Finally, the existing synthesis methods easily lead to the agglomeration of MnOOH materials, which not only reduces its specific surface area but also affects its performance.

[0008] Therefore, there is an urgent need to develop new preparation methods for MnOOH materials to meet the requirements of simplicity, energy saving, and precise control of the specific surface area and crystal form of MnOOH materials.

[0009] In view of this, the present invention is proposed. Summary of the invention

[0010] The object of the present invention is to provide a method for preparing a MnOOH material, aiming to provide a simple, energy-saving preparation method capable of accurately controlling the specific surface area and crystal form of the MnOOH material.

[0011] Another object of the present invention is to provide a MnOOH material, which is a γ-type MnOOH material with a high specific surface area.

[0012] The third object of the present invention is to provide the use of the above-mentioned MnOOH material in the preparation of lithium-ion batteries, supercapacitors and catalysts.

[0013] The present invention is achieved in that:

[0014] In a first aspect, the present invention provides a method for preparing a MnOOH material, comprising:

[0015] Mixing manganese powder and water to prepare slurry and grinding to obtain manganese slurry;

[0016] Mixing manganese slurry and ammonium acetate for reaction and aging to obtain aged slurry;

[0017] The aged slurry is subjected to solid-liquid separation to obtain manganese tetraoxide material;

[0018] The MnOOH material is prepared by mixing manganese tetraoxide material with an oxidant.

[0019] In an optional embodiment, during the preparation of the aged slurry, ammonium acetate is added in an amount of 0.8 g / L-1.2 g / L to adjust the pH value of the system to 6.4-7.6.

[0020] In an optional embodiment, during the reaction of manganese slurry and ammonium acetate, the reaction temperature is controlled to be less than or equal to 70° C., the stirring rate is 200 r / min-300 r / min, and the reaction time is 4 h-6 h.

[0021] In an optional embodiment, when the mass fraction of manganese in the manganese particles in the manganese slurry after the reaction is measured to be between 71% and 72%, the manganese slurry after the reaction is aged for 20 min to 60 min.

[0022] In an optional embodiment, the solid content of the manganese slurry is 55%-65% by adjusting the amount of water used.

[0023] In an optional embodiment, the particle size D50 of the particles in the manganese slurry after grinding is controlled to be 0.8 μm-2.0 μm.

[0024] In an optional embodiment, the aged slurry is subjected to solid-liquid separation by filter pressing, and the water content of the solid material after filter pressing is controlled to be 2%-5%.

[0025] In an optional embodiment, the oxidant is hydrogen peroxide, and the molar ratio of the manganese tetraoxide material to the hydrogen peroxide is controlled to be 2:(2-5);

[0026] And / or, the reaction temperature of the manganese manganese oxide material and the oxidant is controlled to be 180° C.-220° C., and the reaction time is controlled to be 2 h-4 h.

[0027] In a second aspect, the present invention provides a MnOOH material prepared by any one of the preparation methods in the aforementioned embodiments;

[0028] Preferably, the MnOOH material is γ-type;

[0029] Preferably, the specific surface area of ​​the MnOOH material is 150 m 2 / g-180m 2 / g.

[0030] In a third aspect, the present invention provides use of the MnOOH material of the aforementioned embodiment in the preparation of a lithium-ion battery, a supercapacitor or a catalyst.

[0031] The present invention has the following beneficial effects: the present invention uses metal manganese to hydrolyze ammonium acetate as a catalyst to synthesize Mn with high specific surface area. 3 O 4 , and then use the high specific surface area Mn 3 O 4 The oxidant is added to carry out hydrothermal reaction to synthesize γ-type MnOOH. The preparation process provided by the present invention can greatly reduce the reaction temperature and time, which is conducive to large-scale production; it can also effectively avoid the agglomeration of MnOOH materials, and can obtain γ-type MnOOH with a high specific surface area, and its specific surface area is as high as 150m 2 / g has good chemical stability and electrochemical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 This is the XRD pattern of the MnOOH material prepared in Example 1;

[0034] Figure 2 This is the XRD pattern of the MnOOH material prepared in Comparative Example 1. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0036] The present invention provides a method for preparing a MnOOH material, and the steps are as follows:

[0037] S1. Preparation of manganese slurry

[0038] Manganese powder and water are mixed to form a slurry with a certain solid content, and then ground to obtain manganese slurry. Grinding reduces the particle size of particles in the manganese slurry, which is conducive to the subsequent acquisition of manganese tetraoxide materials with a larger specific surface area.

[0039] Specifically, manganese powder is a commercially available material, such as that purchased from Sinosteel Tianyuan, and most of the manganese powder is converted into manganese hydroxide after mixing with water. The grinding method is not limited, such as using a ball mill to grind, so that the particle size D50 of the particles in the slurry after grinding meets the requirements.

[0040] In some embodiments, the amount of water is adjusted to make the solid content of the manganese slurry 55%-65%, such as 55%, 58%, 60%, 63%, 65%, etc. By adjusting the ball milling parameters, the particle size D50 of the particles in the manganese slurry after grinding is controlled to be 0.8μm-2.0μm, such as 0.8μm, 1.0μm, 1.2μm, 1.5μm, 1.8μm, 2.0μm, etc.

[0041] S2, reaction with ammonium acetate

[0042] The ground manganese slurry is poured into a reactor, and ammonium acetate is added to the reactor to cause an exothermic reaction. After the reaction is completed, it is aged to obtain an aged slurry. The role of ammonium acetate in the reaction process is equivalent to a catalyst. 3 COO - It is a weak acid ion that can buffer the pH value of the solution, making the reaction milder and avoiding too fast or too slow reaction. It can also produce carbon dioxide, making the specific surface area larger and the product purer.

[0043] In order to increase the specific surface area of ​​manganese tetraoxide, the inventor optimized the dosage of ammonium acetate: ammonium acetate can be added in an amount of 0.8g / L-1.2g / L, and the pH value of the system can be adjusted to 6.4-7.6 at this dosage to promote the reaction. If the catalyst concentration is too low, the reaction rate is too slow, the reaction time is prolonged, and the product specific surface area is high, but if the concentration is too low, the reaction will be incomplete, the product will be impure, the yield will be low, the economy will be poor, and the synthesized MnOOH will have low crystallinity; if the catalyst concentration is too high: the reaction rate is too fast, the product particles are large, the specific surface area is reduced, and the crystallinity is poor.

[0044] Specifically, the amount of ammonium acetate added can be 0.8 g / L, 0.9 g / L, 1.0 g / L, 1.1 g / L, 1.2 g / L, etc.; by adjusting the amount of ammonium acetate added, the pH value of the system can be 6.4, 6.5, 6.8, 7.0, 7.2, 7.4, 7.6, etc.

[0045] In some embodiments, during the reaction of manganese slurry and ammonium acetate, the reaction temperature is controlled to be less than or equal to 70°C. Since the reaction is an exothermic reaction, the maximum temperature is controlled to be ≤70°C during the reaction to prevent excessive temperature from affecting the morphology of manganese tetraoxide. Specifically, the reaction temperature can be 70°C, 60°C, 50°C, 40°C, etc. The reaction time is controlled to be 4h-6h so that the reaction is fully carried out, specifically 4.0h, 4.5h, 5.0h, 5.5h, 6.0h, etc.

[0046] In some embodiments, during the reaction of manganese slurry and ammonium acetate, the stirring rate is 200r / min-300r / min, such as 200r / min, 230r / min, 250r / min, 280r / min, 300r / min, etc. The reaction rate is preferably within the above range. If the stirring speed is too high, high shear force will cause product particles to break, and the specific surface area may be higher, but high shear force will also make the reaction rate too fast, resulting in local supersaturation and generating uneven products, and too high stirring speed may cause crystal breakage and reduce crystallinity; if the stirring speed is too low, precipitation or agglomeration will occur, the surface area is low, and the reaction rate is slow, the product particles may be larger, and the production efficiency will also decrease.

[0047] In some embodiments, when the mass fraction of manganese in the manganese particles in the manganese slurry after the reaction is measured to be between 71% and 72%, that is, approximately equal to the manganese content in manganese tetraoxide, the manganese slurry after the reaction is aged for 20 minutes to 60 minutes. Specifically, the aging process can be carried out in an aging tank, and the aging time can be controlled to be 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc.

[0048] S3, solid-liquid separation

[0049] The aged slurry is subjected to solid-liquid separation, and water and ammonium acetate are removed to obtain the manganese tetraoxide material. The specific surface area of ​​the manganese tetraoxide prepared in the embodiment of the present invention is 30-35 m 2 / g.

[0050] In some embodiments, the aged slurry may be separated into solid and liquid by filter pressing, but the present invention is not limited thereto. The water content of the solid material after filter pressing may be controlled to be 2%-5% to meet the requirement of water content of the product.

[0051] S4. Oxidation reaction

[0052] The obtained manganese tetraoxide material with high specific surface area is mixed with an oxidant for reaction to obtain a MnOOH material with high specific surface area.

[0053] In some embodiments, the oxidant is hydrogen peroxide, and the molar ratio of manganese tetraoxide material to hydrogen peroxide is controlled to be 2:(2-5), such as 2:2, 2:3, 2:4, 2:5, etc. The reaction formula is as follows:

[0054] 2Mn 3 O 4 +3H 2 O 2 →6MnOOH+O 2 ;

[0055] In some embodiments, the reaction temperature of the manganese tetraoxide material and the oxidant is controlled to be 180° C.-220° C., and the reaction time is 2 h-4 h, so that the manganese tetraoxide is fully converted into MnOOH. Specifically, the reaction temperature can be 180° C., 190° C., 200° C., 210° C., 220° C., etc., and the reaction time can be 2 h, 3 h, 4 h, etc.

[0056] It should be noted that the present invention simplifies the synthesis steps, reduces the reaction temperature and time, and can also accurately control the specific surface area and crystal form of the MnOOH material, thereby improving the synthesis efficiency and facilitating large-scale production.

[0057] The embodiment of the present invention provides a MnOOH material, which is prepared by the preparation method provided by the embodiment of the present invention. The MnOOH material is γ-type and has a specific surface area of ​​150 m 2 / g-180m 2 / g.

[0058] It should be noted that the γ-type MnOOH prepared in the embodiment of the present invention has a high specific surface area and excellent adsorption performance, and can be widely used in catalysis, adsorption, sensing and energy storage and other fields. Compared with the MnOOH material prepared in the prior art, the γ-type MnOOH of the present invention has a higher specific surface area, better chemical stability and electrochemical performance, and therefore has greater application potential in the fields of lithium-ion batteries, supercapacitors and catalysts.

[0059] It should be noted that in the field of nanotechnology, the synthesis method of the present invention avoids the common agglomeration phenomenon in the prior art, and the prepared MnOOH material has better dispersibility, which not only improves its specific surface area, but also enhances its performance. In addition, since the synthesis method of the present invention is carried out under mild conditions, the energy consumption is low, it is more environmentally friendly, and is conducive to sustainable development. This is of great significance for promoting the development of the field of nanotechnology and meeting the market demand for nanomaterials that are efficient, environmentally friendly, and can be mass-produced. In general, the technical application prospects of the present invention are broad, the market demand is large, and it is expected to play an important role in the fields of materials science, inorganic chemical material synthesis, and nanotechnology.

[0060] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0061] Example 1

[0062] This embodiment provides a method for preparing a MnOOH material, and the steps are as follows:

[0063] (1) Mix metal manganese powder with a particle size D50 of 6-15 μm and water to prepare a manganese slurry with a solid content of 60% (mass fraction, the same below), and grind the manganese slurry on a ball mill to a particle size D50 of about 1.2-3 μm.

[0064] (2) The ground manganese slurry is introduced into the reactor, and ammonium acetate is added to the reactor at 1.0 g / L to adjust the pH value of the solution to about 7.0. The reaction process itself is an exothermic reaction. The maximum temperature during the reaction is controlled to be ≤70°C (the reaction temperature is in the range of 40°C-60°C), the stirring speed is controlled to be between 250 r / min, the reaction time is 5 hours, and when the manganese content in the manganese slurry is measured to be between 71% and 72%, the manganese slurry is introduced into an aging tank and aged for 30 minutes.

[0065] (3) The manganese slurry after aging in the aging tank is filtered in a filter press, and the water content of the filtration is controlled at 2%-5% to obtain manganese tetraoxide material.

[0066] (4) The obtained manganese tetraoxide material with high specific surface area is mixed with 30% by mass of hydrogen peroxide, the molar ratio of the manganese tetraoxide material to the hydrogen peroxide is 2:3, and the mixture is reacted at 200° C. for 3 hours to obtain a γ-type MnOOH material with high specific surface area.

[0067] After testing, the specific surface area of ​​the manganese tetraoxide material obtained in step (3) is 35.11 m 2 / g, the specific surface area of ​​the MnOOH material obtained in step (4) is 160.67 m 2 / g, the crystallinity of the material is: 98%.

[0068] The XRD pattern of the MnOOH material prepared in this example is shown in Figure 1 As shown, it can be seen that the corresponding PDF card of this material is: 18-0805. It can be seen that the MnOOH material is γ-type and has a large specific surface area because ammonium acetate dissociates into NH 4 + and CH 3 COO - , CH 3 COO - It is a weak acid ion and can form a relatively stable complex with metallic manganese to avoid excessive reaction. In addition, the acetate ion produces gas when it decomposes, which is beneficial to increase the pH value of the product.

[0069] Example 2

[0070] The only difference from Example 1 is that ammonium acetate is added at 0.8 g / L in step (2).

[0071] After testing, the specific surface area of ​​the manganese tetraoxide material obtained in step (3) is 38.45 m 2 / g, the specific surface area of ​​the MnOOH material obtained in step (4) is 180.35m 2 / g, the crystallinity of the material is: 93%.

[0072] Example 3

[0073] The only difference from Example 1 is that ammonium acetate is added in step (2) at 1.2 g / L.

[0074] After testing, the specific surface area of ​​the manganese tetraoxide material obtained in step (3) is 33.16 m 2 / g, the specific surface area of ​​the MnOOH material obtained in step (4) is 150.23 m 2 / g, the crystallinity of the material is: 92%.

[0075] Example 4

[0076] The only difference from Example 1 is that ammonium acetate is added at 0.5 g / L in step (2).

[0077] After testing, the specific surface area of ​​the manganese tetraoxide material obtained in step (3) is 42.97 m 2 / g, the specific surface area of ​​the MnOOH material obtained in step (4) is 182.13 m 2 / g, the crystallinity of the material is: 71%.

[0078] Example 5

[0079] The only difference from Example 1 is that in step (2), ammonium acetate is added at 1.5 g / L.

[0080] After testing, the specific surface area of ​​the manganese tetraoxide material obtained in step (3) is 29.59 m 2 / g, the specific surface area of ​​the MnOOH material obtained in step (4) is 98.46m 2 / g, the crystallinity of the material is: 64%.

[0081] Example 6

[0082] The only difference from Example 1 is that the stirring rate in step (2) is 200 r / min.

[0083] After testing, the specific surface area of ​​the manganese tetraoxide material obtained in step (3) is 32.15 m 2 / g, the specific surface area of ​​the MnOOH material obtained in step (4) is 145.67m 2 / g, the crystallinity of the material is: 83%.

[0084] Example 7

[0085] The only difference from Example 1 is that the stirring rate in step (2) is 300 r / min.

[0086] After testing, the specific surface area of ​​the manganese tetraoxide material obtained in step (3) is 39.82 m 2 / g, the specific surface area of ​​the MnOOH material obtained in step (4) is 167.56 m 2 / g, the crystallinity of the material is: 86%.

[0087] Example 8

[0088] The only difference from Example 1 is that the stirring rate in step (2) is 100 r / min.

[0089] After testing, the specific surface area of ​​the manganese tetraoxide material obtained in step (3) is 26.57 m 2 / g, the specific surface area of ​​the MnOOH material obtained in step (4) is 90.79m2 / g, the crystallinity of the material is: 62%.

[0090] Example 9

[0091] The only difference from Example 1 is that the stirring rate in step (2) is 400 r / min.

[0092] After testing, the specific surface area of ​​the manganese tetraoxide material obtained in step (3) is 40.37 m 2 / g, the specific surface area of ​​the MnOOH material obtained in step (4) is 175.22 m 2 / g, the crystallinity of the material is: 72%.

[0093] Comparative Example 1

[0094] The only difference from Example 1 is that ammonium acetate is replaced by an equal amount of ammonium sulfate.

[0095] After testing, the specific surface area of ​​the manganese tetraoxide material obtained in step (3) is 0.53 m 2 / g, the specific surface area of ​​the MnOOH material obtained in step (4) is 19.36 m 2 / g, the crystallinity of the material is: 94%.

[0096] The XRD pattern of the MnOOH material prepared in this comparative example is as follows Figure 2 As shown, the corresponding PDF card of this material is: 24-0713. It can be seen that the MnOOH material is α-type and has a small specific surface area. This is because when ammonium sulfate is used as a catalyst, NH 4 + and SO 4 2- , SO 4 2- It is a strong acid radical ion. Strong acidic and oxidizing environments can significantly accelerate the hydrolysis reaction of metallic manganese. Therefore, the obtained manganese tetraoxide has a small specific surface area. Moreover, the MnOOH material synthesized by using the manganese tetraoxide in the same hydrothermal reaction has an α-type crystal form and a small specific surface area.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a MnOOH material, characterized in that: include: Mixing manganese powder and water to prepare slurry and grinding to obtain manganese slurry; Mixing manganese slurry and ammonium acetate for reaction and aging to obtain aged slurry; The aged slurry is subjected to solid-liquid separation to obtain manganese tetraoxide material; The manganese manganese tetroxide material is mixed with an oxidant to prepare a MnOOH material.

2. The preparation method according to claim 1, characterized in that: During the preparation of the aged slurry, ammonium acetate is added in an amount of 0.8 g / L-1.2 g / L to adjust the pH value of the system to 6.4-7.

6.

3. The preparation method according to claim 2, characterized in that: During the reaction of the manganese slurry and ammonium acetate, the reaction temperature is controlled to be less than or equal to 70° C., the stirring rate is 200 r / min-300 r / min, and the reaction time is 4 h-6 h.

4. The preparation method according to claim 3, characterized in that: When the mass fraction of manganese in the manganese particles in the manganese slurry after the reaction is measured to be between 71% and 72%, the manganese slurry after the reaction is aged for 20 minutes to 60 minutes.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The solid content of the manganese slurry is adjusted to be 55%-65% by adjusting the amount of water.

6. The preparation method according to claim 5, characterized in that: The particle size D50 of the particles in the manganese slurry after grinding is controlled to be 0.8 μm-2.0 μm.

7. The preparation method according to claim 1, characterized in that: The aged slurry is subjected to solid-liquid separation by means of filter pressing, and the water content of the solid material after filter pressing is controlled to be 2%-5%.

8. The preparation method according to claim 1, characterized in that: The oxidant is hydrogen peroxide, and the molar ratio of the manganese tetraoxide material to the hydrogen peroxide is controlled to be 2:(2-5); And / or, the reaction temperature of the manganese manganese tetroxide material and the oxidant is controlled to be 180° C.-220° C., and the reaction time is controlled to be 2 h-4 h.

9. A MnOOH material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8; Preferably, the MnOOH material is γ-type; Preferably, the specific surface area of ​​the MnOOH material is 150 m 2 / g-180m 2 / g.

10. Use of the MnOOH material according to claim 9 in the preparation of lithium-ion batteries, supercapacitors or catalysts.

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