Preparation method of manganese dioxide with large specific surface area by taking chlorous acid as catalyst

Abstract

The invention relates to a method for preparing manganese dioxide with a large specific surface area by taking chlorous acid as a catalyst, which specifically comprises the following steps of: changing the electrode potential of HClO2 / Cl2 and MnO4- / MnO2 couple by adjusting the partial pressure of chlorine, thereby controlling the proceeding direction of reversible reaction # imgabs0 #; and finally, the electrolytic manganese dioxide with low selling price is converted into the chemical manganese dioxide with high price and large specific surface area. Compared with the prior art, the method provided by the invention is green and environment-friendly, basically does not generate any waste pollutants, and basically does not consume any chemical agent (chlorous acid only plays a catalyst role in the reaction process) in the production process.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic materials, and in particular to a method for preparing manganese dioxide with a large specific surface area by using chlorous acid as a catalyst. Background Art

[0002] Indoor air quality has a profound impact on human health. Artificial boards, wallpapers, paints, etc. commonly used in interior decoration are the main sources of indoor air pollutants. Indoor air pollutants mainly include volatile organic compounds, particulate matter, microorganisms, etc. Among them, formaldehyde has become the most important indoor pollutant due to its wide source, high toxicity, and strong carcinogenicity.

[0003] At present, three strategies are usually adopted for indoor formaldehyde pollution: source control, ventilation, and end-of-pipe control. Source control refers to the selection of green and formaldehyde-free decoration materials. Due to the cost of decoration materials, source control is difficult to promote. Ventilation can only transfer formaldehyde from indoors to outdoors, which is a temporary solution but not a fundamental solution. Therefore, end-of-pipe control is an efficient and feasible means of formaldehyde purification.

[0004] Catalytic oxidation directly converts formaldehyde into harmless carbon dioxide and water. It is the most promising formaldehyde terminal treatment method. Its core technology lies in the activity of the catalyst. Precious metal catalysts can catalytically oxidize formaldehyde under relatively mild conditions, but they are difficult to promote due to their high cost. Manganese dioxide has been widely used in catalytic oxidation of formaldehyde due to its high low-temperature catalytic activity and low toxicity and low cost.

[0005] Manganese dioxide can be divided into electrolytic manganese dioxide (EMD) and chemical manganese dioxide (CMD) according to different production methods. Electrolytic manganese dioxide is a cheap and abundant material with high electrochemical capacity, and is mainly used to prepare high-performance zinc-manganese batteries. Chemical manganese dioxide has the advantages of large specific surface area, sufficient surface hydroxyl groups and oxygen vacancies, and good catalytic activity. Therefore, in terms of catalytic oxidation of formaldehyde, chemical manganese dioxide with a large specific surface area is the best choice for catalysts. However, the price of chemical manganese dioxide is very expensive, up to dozens of times that of electrolytic manganese dioxide.

[0006] Therefore, there is an urgent need for a method for directly converting cheap electrolytic manganese dioxide into expensive chemical manganese dioxide. Summary of the invention

[0007] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a method for preparing manganese dioxide with large specific surface area using chlorous acid as a catalyst, specifically, by adjusting the chlorine partial pressure to change the HClO2 / Cl2 and MnO4 - / MnO2 electrode potential, thereby controlling the reversible reaction The direction of progress is to eventually convert the cheap electrolytic manganese dioxide into expensive chemical manganese dioxide with a large specific surface area.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] The object of the present invention is to provide a method for preparing manganese dioxide with a large specific surface area using chlorous acid as a catalyst, the method comprising the following steps:

[0010] S1, preparing chlorous acid solution;

[0011] S2, the chlorous acid solution obtained in step S1 and electrolytic manganese dioxide are fully stirred and reacted in a negative pressure reaction tank, chlorine gas is extracted during the reaction, and solid-liquid separation is performed to obtain a liquid as a mixed solution 1;

[0012] S3, the mixed solution 1 obtained in step S2 and the manganese dioxide seed crystals are fully stirred and reacted in a high-pressure reaction tank, chlorine gas is introduced during the reaction, and the solid-liquid separation is performed to obtain a solid with a large specific surface area manganese dioxide.

[0013] Furthermore, the large specific surface area manganese dioxide is chemical manganese dioxide, and the specific surface area of ​​the large specific surface area manganese dioxide is greater than or equal to 180m 2 / g.

[0014] Furthermore, in step S2, the solid obtained by solid-liquid separation is the remaining electrolytic manganese dioxide.

[0015] Furthermore, in step S3, the liquid obtained by solid-liquid separation is a mixed solution 2.

[0016] Further, after step S3, the following steps are performed:

[0017] S4, stirring the mixed solution 2 obtained in step S2 and the remaining electrolytic manganese dioxide obtained in step S3 in a negative pressure reaction tank for reaction, extracting chlorine gas during the reaction, and separating the solid and the liquid to obtain the mixed solution 1;

[0018] S5, stirring the mixed solution 1 obtained in step S4 and the manganese dioxide seed crystals in a high-pressure reaction tank for reaction, introducing chlorine gas during the reaction, and separating the solid and the liquid to obtain a solid with a large specific surface area manganese dioxide.

[0019] Furthermore, steps S4 to S5 are repeated to prepare manganese dioxide with a large specific surface area.

[0020] Furthermore, in step S1, the preparation of the chlorous acid solution includes the following process: mixing a sodium chlorite solution and dilute sulfuric acid at a solute molar ratio of 1:0.5 to prepare a chlorous acid solution.

[0021] Furthermore, in step S1, during the preparation of the chlorous acid solution, the operation is performed in a dark environment and the temperature of the chlorous acid solution is controlled at 0-5°C.

[0022] Furthermore, in step S1, the dilute sulfuric acid concentration is selected to be a sulfuric acid aqueous solution with a solute mass fraction of less than 20%.

[0023] Furthermore, in step S2, the partial pressure of chlorine in the negative pressure reaction tank is 0.004-0.006 atm.

[0024] Further preferably, in step S2, the partial pressure of chlorine in the negative pressure reaction tank is controlled at 0.005 atm.

[0025] Furthermore, in step S2, the reaction time is 40 min to 55 min.

[0026] Furthermore, in step S2, the solid-liquid separation method includes one or more of centrifugal separation, plate and frame filtration and vacuum filtration.

[0027] Furthermore, in step S2, the stirring speed is 440 rpm to 660 rpm.

[0028] Further, in step S2, electrolytic manganese dioxide is added to the chlorous acid solution at a concentration of 250 g / L.

[0029] Furthermore, the chemical reaction in the negative pressure reaction tank is MnO2+HClO2=HMnO4+0.5Cl2↑.

[0030] As a preferred technical solution, the reaction liquid in the negative pressure reaction tank is a chlorous acid solution with a concentration of 1.54 mol / L, and the reaction starts when the chlorine partial pressure is 0.005 atm. 502V, reaction ends

[0031] As a preferred technical solution, when the reaction liquid in the negative pressure reaction tank is the mixed solution 2, the reaction starts. End of reaction

[0032] Furthermore, in step S3, the partial pressure of chlorine in the high-pressure reaction tank is 4 to 5 atm.

[0033] Further preferably, in step S3, when the partial pressure of chlorine in the high-pressure reaction tank is controlled at 4.2 atm, the conversion rate of permanganate decomposing into large specific surface area manganese dioxide is 90%.

[0034] Furthermore, in step S3, the reaction time is 90 min to 105 min.

[0035] Furthermore, in step S3, the solid-liquid separation method includes one or more of centrifugal separation, plate and frame filtration and vacuum filtration.

[0036] Furthermore, in step S3, the stirring speed is 130 rpm to 230 rpm.

[0037] Furthermore, in step S3, manganese dioxide seed crystals are added into the mixed solution 1 at a concentration of 0.14 g / L to 0.18 g / L.

[0038] Furthermore, the chemical reaction in the high pressure reaction tank is HMnO4+0.5Cl2↑=MnO2↓+HClO2.

[0039] As a preferred technical solution, the partial pressure of chlorine in the high-pressure reaction tank is controlled at 4.2 atm. At the end of the reaction

[0040]

[0041] Furthermore, the chlorine extracted in the chlorine extraction process in step S2 is stored for standby use and is used to be introduced into the chlorine process in step S3.

[0042] Furthermore, the chlorine gas extracted in the chlorine extraction process in step S4 is stored for standby use and is used for feeding into the chlorine process in step S5.

[0043] Furthermore, the storage and standby conditions are as follows: after the chlorine gas is dried, it is pressurized to above 0.75 MPa and stored in a steel cylinder in the form of liquid chlorine.

[0044] As a preferred technical solution, the desiccant used for chlorine drying includes one or more of concentrated sulfuric acid, phosphorus pentoxide, anhydrous calcium chloride, anhydrous calcium sulfate and anhydrous magnesium sulfate.

[0045] Furthermore, in step S2, manganese dioxide seeds of different crystal forms are added into the high-pressure reaction tank to obtain manganese dioxide of corresponding crystal forms with large specific surface area.

[0046] Furthermore, in step S2, the manganese dioxide seed crystals include one or more of α-MnO2, β-MnO2, γ-MnO2, δ-MnO2 and λ-MnO2.

[0047] Furthermore, the method specifically comprises the following steps:

[0048] (1) A 3.08 mol / L sodium chlorite solution and a 1.54 mol / L dilute sulfuric acid solution were mixed in a volume ratio of 1:1 in the dark and the temperature was controlled at 0 to 5° C. to prepare a 1.54 mol / L chlorous acid solution.

[0049] (2) The 1.54 mol / L chlorous acid solution and a certain amount of electrolytic manganese dioxide are transferred to a negative pressure reaction tank and stirred for reaction. During the reaction, the generated chlorine gas in the negative pressure reaction tank is extracted and stored for standby use, and the air pressure is controlled at 0.005 atm (in the negative pressure reaction tank, air is extracted in the initial stage, and chlorine gas is continuously generated. Finally, the total air pressure in the negative pressure reaction tank is the chlorine partial pressure. The two values ​​are consistent. Controlling the total air pressure is controlling the chlorine partial pressure). After the reaction is completed, solid-liquid separation is performed to obtain a mixed solution 1 (liquid) with a pH of 0.52, a permanganate concentration of 0.2 mol / L, and a chlorous acid concentration of 1.34 mol / L and the remaining electrolytic manganese dioxide (solid). The mixed solution 1 is the raw material for the production of large specific surface area manganese dioxide and enters the next process.

[0050] (3) The mixed solution 1 obtained in the above step (2) (the raw material for producing the manganese dioxide with a large specific surface area) and a certain amount of manganese dioxide seed crystals are transferred to a high-pressure reaction tank and stirred for reaction. During the reaction, the stored chlorine gas is pressed into the high-pressure reaction tank and the chlorine partial pressure is controlled at 4.2 atm (the chlorine partial pressure control method is: the partial pressure provided by the original air in the high-pressure reaction tank is a fixed value of 1 atm. If the chlorine partial pressure needs to be controlled at 4.2 atm, the total air pressure is controlled at 5.2 atm). After the reaction is completed, solid-liquid separation is performed to obtain a mixed solution 2 (liquid) with a pH of 0.92, a permanganate concentration of 0.02 mol / L, and a chlorous acid concentration of 1.52 mol / L and a manganese dioxide with a large specific surface area (solid).

[0051] (4) The mixed solution 2 obtained in the above step (3) and the remaining electrolytic manganese dioxide are transferred back to the negative pressure reaction tank for sufficient stirring and reaction. During the reaction, the generated chlorine gas in the negative pressure reaction tank is extracted and stored for standby use, and the gas pressure is controlled at 0.005 atm. After the reaction is completed, solid-liquid separation is performed to obtain a mixed solution 1 (raw material for producing large specific surface area manganese dioxide) with a pH of 0.52, a permanganate concentration of 0.2 mol / L, and a chlorous acid concentration of 1.34 mol / L and the remaining electrolytic manganese dioxide.

[0052] (5) The mixed solution 1 (the raw material for producing manganese dioxide with a large specific surface area) is transferred back to the high-pressure reaction tank to prepare manganese dioxide with a large specific surface area, i.e., step (3); the obtained mixed solution 2 is transferred back to the negative pressure reaction tank to prepare mixed solution 1 (the raw material for producing manganese dioxide with a large specific surface area), i.e., step (4). The process {steps (3) and (4) are continuously cycled} to prepare manganese dioxide with a large specific surface area. In this process, chlorous acid is not lost at all and plays a catalytic role in the process of converting electrolytic manganese dioxide into manganese dioxide with a large specific surface area.

[0053] Furthermore, in step (1), the solid-liquid separation method includes one or more of centrifugal separation, plate and frame filtration and vacuum filtration.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] 1) The technical solution provides a method for preparing manganese dioxide with a large specific surface area using chlorous acid as a catalyst, which basically does not generate any waste pollutants, and the production process is green and environmentally friendly.

[0056] 2) The technical solution provides a method for preparing manganese dioxide with a large specific surface area using chlorous acid as a catalyst. After preparing the chlorous acid solution, basically no chemical agent is consumed. The chlorous acid only acts as a catalyst in the reaction process, and what is consumed essentially is electrical energy.

[0057] 3) The technical solution provides a method for preparing manganese dioxide with a large specific surface area using chlorous acid as a catalyst, and the reversible reaction The core reaction of the present invention is to change the HClO2 / Cl2 and MnO4 by adjusting the chlorine partial pressure. - / MnO2 electrode potential, thereby controlling the direction of the reversible reaction, and ultimately converting electrolytic manganese dioxide into chemical manganese dioxide with a large specific surface area. Reduce the chlorine partial pressure to When the reaction proceeds in the forward direction, electrolytic manganese dioxide is converted into permanganate; increasing the chlorine partial pressure to When , the reaction proceeds in the reverse direction, and the newly generated permanganate is converted into manganese dioxide with a large specific surface area. DETAILED DESCRIPTION

[0058] The present invention is described in detail below in conjunction with specific embodiments. Component models, material names, connection structures, control methods, algorithms and other features not clearly described in this technical solution are all considered to be common technical features disclosed in the prior art.

[0059] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0060] The present invention provides a catalyst with a large specific surface area (≥180m 2 / g) manganese dioxide preparation method, which is achieved by the following technical scheme:

[0061] (1) 3.08 mol / L sodium chlorite solution (sodium chlorite aqueous solution) and 1.54 mol / L dilute sulfuric acid were mixed in a volume ratio of 1:1 in the dark, and the temperature was controlled at 0 to 5° C. to prepare a chlorous acid solution with a concentration of 1.54 mol / L.

[0062] (2) The 1.54 mol / L chlorous acid solution and a certain amount of electrolytic manganese dioxide are transferred to a negative pressure reaction tank and stirred for reaction. During the reaction, the generated chlorine gas in the negative pressure reaction tank is extracted and stored for standby use, and the gas pressure is controlled at 0.005 atm. After the reaction is completed, solid-liquid separation is performed to obtain a mixed solution 1 (liquid) with a pH of 0.52, a permanganate concentration of 0.2 mol / L, and a chlorous acid concentration of 1.34 mol / L and the remaining electrolytic manganese dioxide (solid). The mixed solution 1 is the raw material for the production of large specific surface area manganese dioxide and enters the next process.

[0063] (3) The mixed solution 1 obtained in the above step (2) (the raw material for producing the manganese dioxide with a large specific surface area) and a certain amount of manganese dioxide seed crystals are transferred to a high-pressure reaction tank and stirred for reaction. During the reaction, the stored chlorine gas is pressed into the high-pressure reaction tank and the chlorine partial pressure is controlled at 4.2 atm. After the reaction is completed, solid-liquid separation is performed to obtain a mixed solution 2 (liquid) with a pH of 0.92, a permanganate concentration of 0.02 mol / L, and a chlorous acid concentration of 1.52 mol / L and a manganese dioxide with a large specific surface area (solid).

[0064] (4) The mixed solution 2 obtained in the above step (3) and the remaining electrolytic manganese dioxide are transferred back to the negative pressure reaction tank for sufficient stirring and reaction. During the reaction, the generated chlorine gas in the negative pressure reaction tank is extracted and stored for standby use, and the gas pressure is controlled at 0.005 atm. After the reaction is completed, solid-liquid separation is performed to obtain a mixed solution 1 (raw material for producing large specific surface area manganese dioxide) with a pH of 0.52, a permanganate concentration of 0.2 mol / L, and a chlorous acid concentration of 1.34 mol / L and the remaining electrolytic manganese dioxide.

[0065] (5) The mixed solution 1 (the raw material for producing manganese dioxide with a large specific surface area) is transferred back to the high-pressure reaction tank to prepare manganese dioxide with a large specific surface area, i.e., step (3); the obtained mixed solution 2 is transferred back to the negative pressure reaction tank to prepare mixed solution 1 (the raw material for producing manganese dioxide with a large specific surface area), i.e., step (4). The process {steps (3) and (4) are continuously cycled} to prepare manganese dioxide with a large specific surface area. In this process, chlorous acid is not lost at all and plays a catalytic role in the process of converting electrolytic manganese dioxide into manganese dioxide with a large specific surface area.

[0066] The solid-liquid separation method includes one or more of centrifugal separation, plate and frame filtration and vacuum filtration.

[0067] After the chlorine gas is dried, it is pressurized to above 0.75MPa and stored in a steel cylinder in the form of liquid chlorine.

[0068] The desiccant used for chlorine drying includes one or more of concentrated sulfuric acid, phosphorus pentoxide, anhydrous calcium chloride, anhydrous calcium sulfate and anhydrous magnesium sulfate.

[0069] The partial pressure of chlorine in the negative pressure reaction tank is controlled at 0.005atm.

[0070] The chemical reaction in the negative pressure reaction tank is MnO2+3HClO=HMnO4+1.5Cl2↑+H2O.

[0071] The chemical reaction in the negative pressure reaction tank is MnO2+HClO2=HMnO4+0.5Cl2↑.

[0072] The reaction liquid in the negative pressure reaction tank is a 1.54 mol / L chlorous acid solution. When the chlorine partial pressure is 0.005 atm, the reaction begins. End of reaction

[0073]

[0074] When the reaction liquid in the negative pressure reaction tank is mixed solution 2, the reaction starts End of reaction

[0075] The negative pressure reaction time is controlled between 40 minutes and 55 minutes.

[0076] By adding manganese dioxide seeds of different crystal forms into a high-pressure reaction tank, manganese dioxide with a large specific surface area of ​​the corresponding crystal form can be obtained.

[0077] The manganese dioxide seed crystals include one or more of α-MnO2, β-MnO2, γ-MnO2, δ-MnO2 and λ-MnO2.

[0078] When the partial pressure of chlorine in the high-pressure reaction tank is controlled at 4.2 atm, the conversion rate of permanganate decomposing into large specific surface area manganese dioxide is 90%.

[0079] The chemical reaction in the high-pressure reaction tank is HMnO4+0.5Cl2↑=MnO2↓+HClO2.

[0080] When the reaction starts in the high pressure reactor At the end of the reaction

[0081] The high pressure reaction time is controlled at 90 min to 105 min.

[0082] In the following examples, electrolytic manganese dioxide was purchased from Hunan Simoncheng Technology Co., Ltd. and had a specific surface area of ​​44.7 m 2 / g. α-MnO2 seed crystals were purchased from Dalian Tongmanganese New Material Technology Co., Ltd., and δ-MnO2 seed crystals were purchased from Dalian Tongmanganese New Material Technology Co., Ltd. The concentration of dilute sulfuric acid was 1.54 mol / L.

[0083] Example 1

[0084] This embodiment provides a method for preparing manganese dioxide with a large specific surface area using chlorous acid as a catalyst. The specific parameters of this embodiment are set as follows:

[0085] (1) 3.08 mol / L sodium chlorite solution (sodium chlorite aqueous solution) and 1.54 mol / L dilute sulfuric acid were mixed in a volume ratio of 1:1 in the dark, and the temperature was controlled at 0 to 5° C. to prepare a chlorous acid solution with a concentration of 1.54 mol / L.

[0086] (2) 500L of the above-mentioned 1.54mol / L chlorous acid solution and a certain amount (125kg) of electrolytic manganese dioxide are transferred to a negative pressure reaction tank and stirred for reaction for 40min. During the reaction, the generated chlorine gas in the negative pressure reaction tank is extracted and stored for standby use, and the air pressure is controlled at 0.005atm. The extracted chlorine gas is dried with anhydrous calcium chloride and pressurized to 0.75MPa, and then stored in a steel cylinder in the form of liquid chlorine for standby use. After the reaction is completed, centrifugation is performed to obtain a mixed solution 1 with a pH of 0.52, a permanganate concentration of 0.2mol / L, and a chlorous acid concentration of 1.34mol / L and the remaining electrolytic manganese dioxide. The mixed solution 1 is the raw material for the production of large specific surface area manganese dioxide and enters the next process.

[0087] (3) 375 L of the mixed solution 1 obtained in the above step (2) (raw material for producing manganese dioxide with large specific surface area) and a certain amount (60 g) of λ-MnO2 seed crystals were transferred to a high-pressure reaction tank and stirred for reaction for 90 min. During the reaction, the stored chlorine gas was pressed into the high-pressure reaction tank and the chlorine partial pressure was controlled at 4.2 atm. After the reaction was completed, centrifugation was performed to obtain a mixed solution 2 with a pH of 0.92, a permanganate concentration of 0.02 mol / L, a chlorous acid concentration of 1.52 mol / L and manganese dioxide with large specific surface area.

[0088] (4) The mixed solution 2 obtained in the above step (3) and the remaining electrolytic manganese dioxide obtained in the step (2) are transferred back to the negative pressure reaction tank and stirred for reaction for 40 minutes. During the reaction, the generated chlorine gas in the reaction tank is extracted and stored for standby use, and the air pressure is controlled at 0.005 atm. The extracted chlorine gas is dried with anhydrous calcium chloride and pressurized to 0.75 MPa, and then stored in a steel cylinder in the form of liquid chlorine for standby use. After the reaction is completed, centrifugation is performed to obtain a mixed solution 1 (raw material for the production of large specific surface area manganese dioxide) with a pH of 0.52, a permanganate concentration of 0.2 mol / L, and a chlorous acid concentration of 1.34 mol / L and the remaining electrolytic manganese dioxide.

[0089] (5) The mixed solution 1 (the raw material for producing manganese dioxide with a large specific surface area) in the above step (4) is transferred back to the high-pressure reaction tank to prepare manganese dioxide with a large specific surface area, i.e., step (3); the obtained mixed solution 2 is transferred to the negative pressure reaction tank to prepare mixed solution 1 (the raw material for producing manganese dioxide with a large specific surface area), i.e., step (4). The process is repeated {steps (3) and (4) are continuously cycled} to prepare manganese dioxide with a large specific surface area until the remaining electrolytic manganese dioxide is less than 9 kg.

[0090] Finally, we get: λ-MnO2 crystal form, specific surface area = 222.3m 2 / g of chemical manganese dioxide, impurity Na 0.58 The Mn2O4 content is 12.32g / kg.

[0091] Example 2

[0092] This embodiment provides a method for preparing manganese dioxide with a large specific surface area using chlorous acid as a catalyst. The specific parameters of this embodiment are set as follows:

[0093] (1) 3.08 mol / L sodium chlorite solution (sodium chlorite aqueous solution) and 1.54 mol / L dilute sulfuric acid were mixed in a volume ratio of 1:1 in the dark, and the temperature was controlled at 0 to 5° C. to prepare a chlorous acid solution with a concentration of 1.54 mol / L.

[0094] (2) 1000L of the above-mentioned 1.54mol / L chlorous acid solution and a certain amount (250kg) of electrolytic manganese dioxide are transferred to a negative pressure reaction tank and stirred for reaction for 55min. During the reaction, the generated chlorine gas in the reaction tank is extracted and stored for standby use, and the air pressure is controlled at 0.005atm. The extracted chlorine gas is dried with concentrated sulfuric acid and pressurized to 0.75MPa, and then stored in a steel cylinder in the form of liquid chlorine for standby use. After the reaction is completed, plate and frame filter pressing is performed to obtain a mixed solution 1 with a pH of 0.52, a permanganate concentration of 0.2mol / L, and a chlorous acid concentration of 1.34mol / L and the remaining electrolytic manganese dioxide. The mixed solution 1 is the raw material for the production of large specific surface area manganese dioxide and enters the next process.

[0095] (3) 894 L of the mixed solution 1 obtained in the above step (2) (the raw material for producing the manganese dioxide with a large specific surface area) and a certain amount (143 g) of β-MnO2 seed crystals were transferred to a high-pressure reaction tank and stirred for reaction for 105 min. During the reaction, the stored chlorine gas was pressed into the high-pressure reaction tank and the chlorine partial pressure was controlled at 4.2 atm. After the reaction was completed, plate and frame filter pressing was performed to obtain a mixed solution 2 with a pH of 0.92, a permanganate concentration of 0.02 mol / L, a chlorous acid concentration of 1.52 mol / L and a manganese dioxide with a large specific surface area.

[0096] (4) The mixed solution 2 obtained in the above step (3) and the remaining electrolytic manganese dioxide obtained in step (2) are transferred back to the negative pressure reaction tank and stirred for reaction for 55 minutes. During the reaction, the generated chlorine gas in the reaction tank is extracted and stored for standby use, and the air pressure is controlled at 0.005atm. The extracted chlorine gas is dried with concentrated sulfuric acid and pressurized to 0.75MPa, and then stored in a steel cylinder in the form of liquid chlorine for standby use. After the reaction is completed, plate and frame filter pressing is performed to obtain a mixed solution 1 (production raw material for large specific surface area manganese dioxide) with a pH of 0.52, a permanganate concentration of 0.2mol / L, and a chlorous acid concentration of 1.34mol / L and the remaining electrolytic manganese dioxide.

[0097] (5) The mixed solution 1 (the raw material for producing manganese dioxide with a large specific surface area) in the above step (4) is transferred back to the high-pressure reaction tank to prepare manganese dioxide with a large specific surface area, i.e., step (3); the obtained mixed solution 2 is transferred to the negative pressure reaction tank to prepare mixed solution 1 (the raw material for producing manganese dioxide with a large specific surface area), i.e., step (4). The process is repeated {steps (3) and (4) are continuously cycled} to prepare manganese dioxide with a large specific surface area until the remaining electrolytic manganese dioxide is less than 18 kg.

[0098] Finally, we get: β-MnO2 crystal form, specific surface area = 251.4m 2 / g of chemical manganese dioxide, impurity Na 0.58 The Mn2O4 content is 23.17g / kg.

[0099] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing manganese dioxide with a large specific surface area using chlorous acid as a catalyst, characterized in that: The method comprises the following steps: S1, preparing chlorous acid solution; S2, stirring the chlorous acid solution obtained in step S1 and electrolytic manganese dioxide in a negative pressure reaction tank for reaction, extracting chlorine gas during the reaction, and separating the solid and the liquid to obtain a mixed solution 1; S3, stirring the mixed solution 1 obtained in step S2 and the manganese dioxide seed crystals in a high-pressure reaction tank for reaction, introducing chlorine gas during the reaction, and performing solid-liquid separation to obtain a solid with a large specific surface area manganese dioxide; The large specific surface area manganese dioxide is chemical manganese dioxide, and the specific surface area of ​​the large specific surface area manganese dioxide is greater than or equal to 180m 2 / g.

2. The method for preparing manganese dioxide with large specific surface area using chlorous acid as a catalyst according to claim 1, characterized in that: In step S1, the preparation of the chlorous acid solution includes the following process: mixing a sodium chlorite solution and dilute sulfuric acid at a solute molar ratio of 1:0.5 to prepare a chlorous acid solution; In step S1, during the preparation of the chlorous acid solution, the process is performed in a dark environment and the temperature of the chlorous acid solution is controlled at 0-5°C. In step S1, the concentration of dilute sulfuric acid is selected to be a sulfuric acid aqueous solution with a solute mass fraction of less than 20%.

3. The method for preparing manganese dioxide with large specific surface area using chlorous acid as a catalyst according to claim 1, characterized in that: In step S2, the partial pressure of chlorine in the negative pressure reaction tank is 0.004-0.006 atm; In step S2, the reaction time is 40 min to 55 min; In step S2, the solid-liquid separation method includes one or more of centrifugal separation, plate and frame filtration, and vacuum filtration; In step S2, the stirring speed is 440 rpm to 660 rpm; In step S2, electrolytic manganese dioxide is added to the chlorous acid solution at a concentration of 250 g / L.

4. The method for preparing manganese dioxide with large specific surface area using chlorous acid as a catalyst according to claim 1, characterized in that: In step S3, the partial pressure of chlorine in the high-pressure reaction tank is 4 to 5 atm; In step S3, the reaction time is 90 min to 105 min.

5. The method for preparing manganese dioxide with large specific surface area using chlorous acid as a catalyst according to claim 1, characterized in that: In step S3, the solid-liquid separation method includes one or more of centrifugal separation, plate and frame filtration and vacuum filtration; In step S3, the stirring speed is 130 rpm to 230 rpm; In step S3, manganese dioxide seed crystals are added into the mixed solution 1 at a concentration of 0.14 g / L to 0.18 g / L.

6. The method for preparing manganese dioxide with large specific surface area using chlorous acid as a catalyst according to claim 1, characterized in that: In step S2, the solid obtained by solid-liquid separation is the remaining electrolytic manganese dioxide; In step S3, the liquid obtained by solid-liquid separation is mixed solution 2; After step S3, perform the following steps: S4, stirring the mixed solution 2 obtained in step S3 and the remaining electrolytic manganese dioxide obtained in step S2 in a negative pressure reaction tank for reaction, extracting chlorine gas during the reaction, and separating the solid and the liquid to obtain the mixed solution 1; S5, stirring the mixed solution 1 obtained in step S4 and the manganese dioxide seed crystals in a high-pressure reaction tank for reaction, introducing chlorine gas during the reaction, and separating the solid and the liquid to obtain a solid with a large specific surface area manganese dioxide.

7. The method for preparing manganese dioxide with large specific surface area using chlorous acid as a catalyst according to claim 6, characterized in that: Repeat steps S4 to S5 to prepare manganese dioxide with a large specific surface area.

8. The method for preparing manganese dioxide with large specific surface area using hypochlorous acid as a catalyst according to claim 6, characterized in that: The chlorine gas extracted in the chlorine extraction process in step S4 is stored for standby use and is used to be introduced into the chlorine process in step S5.

9. The method for preparing manganese dioxide with large specific surface area using chlorous acid as a catalyst according to claim 1, characterized in that: The chlorine gas extracted from the chlorine extraction process in step S2 is stored for standby use and is used to be introduced into the chlorine process in step S3.

10. The method for preparing manganese dioxide with large specific surface area using chlorous acid as a catalyst according to claim 1, characterized in that: In step S2, the manganese dioxide seed crystals include one or more of α-MnO2, β-MnO2, γ-MnO2, δ-MnO2 and λ-MnO2.

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