Synthesis method of gamma-type manganese dioxide with high specific surface area

Abstract

The invention discloses a synthesis method of gamma-type manganese dioxide with high specific surface area, and belongs to the field of chemical synthesis, the gamma-type manganese dioxide is synthesized through mild liquid phase reaction, has unique microspherical morphology, average pore size of 8.49 nm and specific surface area up to 168.70 m / g, and obviously improves charge storage capacity, catalytic efficiency and ion diffusion rate. The synthesis method disclosed by the invention is simple in process and low in cost, and the obtained material has high specific surface area, a mesoporous structure and excellent surface activity.

Description

Technical Field

[0001] The invention belongs to the field of chemical synthesis and relates to a method for synthesizing gamma-type manganese dioxide with high specific surface area. Background Art

[0002] Traditional manganese dioxide (MnO2) is limited in application in the fields of energy storage and catalysis due to its low specific surface area, uneven pore size distribution, and limited ion transfer rate. Although the existing technology can prepare nano-scale MnO2 through high-temperature hydrothermal method, its process is complicated, energy-intensive, and the product is easy to agglomerate, resulting in a reduction in specific surface area and active sites.

[0003] Manganese dioxide obtained by adding a reducing agent to a potassium permanganate (KMnO4) oxidant solution to undergo an oxidation-reduction reaction is usually called nascent manganese dioxide. In previous studies, the nascent manganese dioxide was aged, evaporated in a high-temperature kettle, and other reactions to obtain various types of MnO2 crystal particles with a particle size mostly in the nanometer range and a uniform texture. This manganese dioxide is different from ordinary manganese dioxide in that it has a microspherical morphology and a larger specific surface area, thereby further improving the ion transmission rate and catalytic efficiency. Summary of the invention

[0004] The object of the present invention is to provide a method for synthesizing γ-type manganese dioxide with a high specific surface area. The γ-type manganese dioxide is synthesized by a mild liquid phase reaction and has a unique microspherical morphology, a mesoporous structure (average pore size 8.49 nm) and a high specific surface area (168.70 m 2 / g), significantly improving the charge storage capacity, catalytic efficiency and ion diffusion rate, breaking through the performance bottleneck of traditional manganese dioxide.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for synthesizing γ-type manganese dioxide with a high specific surface area comprises the following steps:

[0007] Step 1: add sulfuric acid to water to adjust the pH value, and add potassium permanganate solution and manganese chloride tetrahydrate solution while stirring at 10-50°C;

[0008] Step 2: After the reaction is completed, the solution is filtered, washed and dried to obtain γ-type manganese dioxide.

[0009] Preferably, in step 1, the pH value is 1-6.

[0010] Preferably, in step 1, the stirring rate is 50-500 rpm.

[0011] Preferably, in step 1, the concentrations of the potassium permanganate solution and the manganese chloride tetrahydrate solution are 1-8 g / L and 5-10 g / L, respectively.

[0012] Preferably, in step 1, the mass ratio of potassium permanganate to manganese chloride tetrahydrate is 2:1-1:8.

[0013] Preferably, in step 1, potassium permanganate solution and manganese chloride tetrahydrate solution are added with stirring at room temperature, and the reaction is stirred for 3-10 minutes.

[0014] Preferably, in step 2, the drying temperature is 20-50°C.

[0015] Compared with the prior art, the advantages of the present invention are:

[0016] 1. The synthesis method of the present invention has simple process and low cost.

[0017] 2. The γ-type manganese dioxide synthesized by the synthesis method of the present invention has a unique microspherical morphology, a mesoporous structure (average pore size 8.49nm) and a high specific surface area (168.70m 2 / g) BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a SEM image of γ-MnO2 prepared in Example 1 of the present invention.

[0019] Figure 2 It is the XRD diagram of γ-MnO2 prepared in Examples 1 to 4 of the present invention.

[0020] Figure 3 It is the nitrogen desorption-adsorption curve of γ-MnO2 prepared in Example 1 of the present invention.

[0021] Figure 4 It is a SEM image of γ-MnO2 prepared in Example 2 of the present invention.

[0022] Figure 5 It is the nitrogen desorption-adsorption curve of γ-MnO2 prepared in Example 2 of the present invention.

[0023] Figure 6 This is a SEM image of γ-MnO2 prepared in Example 3 of the present invention.

[0024] Figure 7 It is the nitrogen desorption-adsorption curve of γ-MnO2 prepared in Example 3 of the present invention.

[0025] Figure 8 It is a SEM image of γ-MnO2 prepared in Example 4 of the present invention.

[0026] Fig. 9 It is the nitrogen desorption-adsorption curve of γ-MnO2 prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail in combination with the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The technical solutions of the present invention are described in detail below in combination with the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0028] Example 1

[0029] (1) 1 mL of 4 g / L potassium permanganate solution and 1 mL of 8 g / L manganese chloride tetrahydrate solution were mixed in 5 mL of a solution at pH 5.41, and magnetically stirred at 100 rpm for 3 min.

[0030] (2) The suspension obtained in step (1) is filtered, and the obtained solid powder is washed several times with deionized water and dried in an oven at 25° C. to obtain γ-MnO2.

[0031] The morphology of γ-MnO2 prepared in this example is as follows Figure 1 As shown, XRD Figure 2 As shown, the nitrogen desorption-adsorption curve is as follows Figure 3 shown.

[0032] Example 2

[0033] (1) 1.25 mL of 4 g / L potassium permanganate solution and 2 mL of 10 g / L manganese chloride tetrahydrate solution were mixed in 5 mL of a solution at pH 5, and magnetically stirred at 200 rpm for 5 min.

[0034] (2) The suspension obtained in step (1) is filtered, and the obtained solid powder is washed several times with deionized water and dried in an oven at 35° C. to obtain γ-MnO2.

[0035] The morphology of γ-MnO2 prepared in this example is as follows Figure 4 As shown, XRD Figure 2 As shown, the nitrogen desorption-adsorption curve is as follows Figure 5 shown.

[0036] Example 3

[0037] (1) 1.25 mL of 4 g / L potassium permanganate solution and 1 mL of 5 g / L manganese chloride tetrahydrate solution were mixed in 5 mL of a solution at pH 4, and magnetically stirred at 300 rpm for 7 min.

[0038] (2) The suspension obtained in step (1) is filtered, and the obtained solid powder is washed several times with deionized water and dried in an oven at 45° C. to obtain γ-MnO2.

[0039] The morphology of γ-MnO2 prepared in this example is as follows Figure 6 As shown, XRD Figure 2 As shown, the nitrogen desorption-adsorption curve is as follows Figure 7 shown.

[0040] Example 4

[0041] (1) 2 mL of 4 g / L potassium permanganate solution and 0.5 mL of 8 g / L manganese chloride tetrahydrate solution were mixed in 5 mL of a solution at pH = 1, and magnetically stirred at 500 rpm for 10 min.

[0042] (2) The suspension obtained in step (1) is filtered, and the obtained solid powder is washed several times with deionized water and dried in an oven at 50° C. to obtain γ-MnO2.

[0043] The morphology of γ-MnO2 prepared in this example is as follows Figure 8 As shown, XRD Figure 2 As shown, the nitrogen desorption-adsorption curve is as follows Fig. 9 shown.

Claims

1. A method for synthesizing γ-type manganese dioxide with a high specific surface area, characterized in that: The following steps are involved: Step 1: add sulfuric acid to water to adjust the pH value, and add potassium permanganate solution and manganese chloride tetrahydrate solution while stirring at 10-50°C; Step 2: After the reaction is completed, the solution is filtered, washed and dried to obtain γ-type manganese dioxide.

2. The method according to claim 1, characterized in that In step 1, the pH value is 1-6.

3. The method according to claim 1, characterized in that In step 1, the stirring rate is 50-500 rpm.

4. The method according to claim 1, characterized in that In step 1, the concentrations of the potassium permanganate solution and the manganese chloride tetrahydrate solution are 1-8 g / L and 5-10 g / L, respectively.

5. The method according to claim 1, characterized in that In step 1, the mass ratio of potassium permanganate and manganese chloride tetrahydrate is 2:1-1:

8.

6. The method according to claim 1, characterized in that In step 1, potassium permanganate solution and manganese chloride tetrahydrate solution are added under stirring at room temperature, and the mixture is stirred for reaction for 3-10 minutes.

7. The method according to claim 1, characterized in that In step 2, the drying temperature is 20-50°C.

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