Preparation method and application of manganese dioxide rich in high-activity lattice oxygen

Abstract

The invention provides a preparation method and application of manganese dioxide rich in high-activity lattice oxygen, and relates to the technical field of environmental catalysis, the preparation method of manganese dioxide comprises preparation of a delta-MnO2 material and preparation of an alpha-MnO2 material rich in high-activity lattice oxygen, and the application comprises catalytic removal of gaseous pollutants under the condition of room-temperature moisture. The concentration of potassium permanganate is 0.05-0.5 mol / L, alcohol is dropwise added into the prepared potassium permanganate solution, the molar ratio of potassium permanganate to alcohol is 0.2-2, the delta-MnO2 material can be converted into alpha-MnO2 rich in high-activity lattice oxygen after being treated in the Mn < 2 + > aqueous solution at 60 DEG C, and the delta-MnO2 material can be converted into high-activity lattice oxygen after being treated in the Mn < 2 + > aqueous solution at 60 DEG C; by means of the process, delta-MnO2 can be converted into alpha-MnO2 rich in high-activity lattice oxygen, preparation of the catalyst is completed at normal pressure and low temperature, high-energy-consumption process treatment such as high-temperature roasting and reducing atmosphere treatment is not needed, and the method is suitable for large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental catalysis, and more specifically, particularly relates to a preparation method and application of manganese dioxide rich in highly active lattice oxygen. Background Art

[0002] With the rapid development of industrialization, people's quality of life has been greatly improved. However, the release of harmful gaseous and liquid pollutants caused by industrial production has also caused considerable damage to human health and ecology. Therefore, there is an urgent need to develop effective and sustainable technologies to solve these environmental problems. Among the many developed technologies, nanocatalysis technology is considered to be one of the most promising strategies to solve global environmental pollution.

[0003] One of the key issues in the development of nanocatalytic technology is the development of highly active nanofunctional materials. At present, nanocatalytic materials used for environmental purification include metals, metal oxides and carbon-based materials. Considering several important factors in the practical application of nanomaterials, such as abundance, cost, toxicity, environmental compatibility and environmental purification activity, MnO2 stands out among many materials due to its acid resistance, low toxicity, low cost and high environmental compatibility, and is widely used in the field of environmental purification.

[0004] In nature, MnO2 is mainly divided into six crystal types: α-MnO2, β-MnO2, γ-MnO2, ε-MnO2, δ-MnO2 and λ-MnO2. In the study of catalytic removal of various types of pollutants, oxygen defect sites in MnO2 are widely considered to be the active sites of catalytic reactions (Journal of Hazardous Materials, 409 (2021) 125020; Environmental Science: Nano, 2023, 10, 1428). To this end, researchers have prepared MnO2 materials rich in oxygen defects through various means such as morphology and structure regulation, element doping, crystal surface engineering, and interface construction. However, recent studies have shown that the highly active lattice oxygen in MnO2 can directly produce singlet oxygen to degrade organic pollutants in water (Applied Catalysis B: Environmental, 307 (2022) 121168); in addition, the increase in the activity of lattice oxygen in MnO2 can greatly improve the material's ability to remove gaseous pollutants such as CO (Frontiers of Environmental Science & Engineering, 2024, 18(5): 62). Therefore, developing a process for preparing MnO2 rich in highly active lattice oxygen and synthesizing MnO2 materials rich in highly active lattice oxygen is of great significance for improving the catalytic performance of MnO2 materials and expanding their applications in the field of environmental purification. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing manganese dioxide rich in highly active lattice oxygen and its application to solve the above problems.

[0006] A method for preparing manganese dioxide rich in highly active lattice oxygen comprises the following steps: S1: prepare a potassium permanganate aqueous solution, wherein the concentration of potassium permanganate is 0.05-0.5 mol / L, add alcohols dropwise to the prepared potassium permanganate solution, wherein the molar ratio of potassium permanganate to alcohols is 0.2-2, place the mixed solution in a 60°C water bath with magnetic stirring for 3 hours, wash and filter the precipitate, and dry it in an oven at a temperature range of 50°C-105°C to obtain δ-MnO2 material; S2: prepare different concentrations of Mn 2+ The salt water solution is then added to the δ-MnO2 material prepared in step 1, and the mixed solution is placed in a water bath in the temperature range of 40-90°C with magnetic stirring for 3 hours. The precipitate is washed with water and filtered, and then dried in an oven in the temperature range of 50°C-105°C to obtain an α-MnO2 material rich in highly active lattice oxygen.

[0007] Preferably, the alcohol in S1 is methanol or ethanol.

[0008] Preferably, the Mn in S2 2+ The concentration of the saline solution can be controlled.

[0009] Another technical problem to be solved by the present invention is to provide an application of manganese dioxide rich in highly active lattice oxygen, including the following contents: 1. Catalytic removal of gaseous pollutants, such as CO, under room temperature and humid conditions. This catalytic reaction is carried out at normal pressure and low temperature; 2. Used to remove organic pollutants in water, such as sulfamethoxazole. The removal reaction is also carried out at normal pressure and low temperature.

[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. δ-MnO2 material can be transformed into α-MnO2 rich in highly active lattice oxygen by treating it in Mn2+ aqueous solution at 60 degrees. This process should also be able to transform δ-MnO2 into α-MnO2 rich in highly active lattice oxygen. The cost of raw materials is low, the catalyst preparation method is simple, the preparation of the catalyst is completed at normal pressure and low temperature, and does not require high-energy consumption processes such as high-temperature calcination and reducing atmosphere treatment, which is suitable for large-scale production.

[0011] 2. Through δ-MnO2 and Mn 2+The α-MnO2 prepared by heat treatment of brine solution is rich in highly active lattice oxygen. This material shows good catalytic removal performance for gaseous pollutants in the atmosphere and organic pollutants in aqueous solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is the XRD pattern of the sample obtained in the present invention; Figure 2 3 are SEM images of samples prepared in the comparative example and embodiment 3 of the present invention; Figure 3 1 is the XPS graph of the samples prepared in the comparative example and embodiment 3 of the present invention; Figure 4 3 are H2-TPR curves of the samples prepared in the comparative example and Example 3 of the present invention; Figure 5 2 is the O2-TPD curve of the samples prepared in the comparative example and Example 3 of the present invention; Figure 6 These are the experimental results of the degradation of sulfamethoxazole (SMX) by activating peroxymonosulfate (PMS) with samples prepared in the comparative example and Example 3 of the present invention.

[0013] Figure 7 These are the results of the catalytic O3 decomposition performance of the samples prepared in the comparative example and Example 3 of the present invention. DETAILED DESCRIPTION

[0014] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0015] See also Figure 1-Figure 7 The present invention provides a method for preparing manganese dioxide rich in highly active lattice oxygen, comprising the following steps: S1: prepare a potassium permanganate aqueous solution, wherein the concentration of potassium permanganate is 0.05-0.5 mol / L, add alcohols dropwise to the prepared potassium permanganate solution, wherein the molar ratio of potassium permanganate to alcohols is 0.2-2, place the mixed solution in a 60°C water bath with magnetic stirring for 3 hours, wash and filter the precipitate, and dry it in an oven at a temperature range of 50°C-105°C to obtain δ-MnO2 material; S2: prepare different concentrations of Mn 2+ The salt water solution is then added to the δ-MnO2 material prepared in step 1, and the mixed solution is placed in a water bath in the temperature range of 40-90°C with magnetic stirring for 3 hours. The precipitate is washed with water and filtered, and then dried in an oven in the temperature range of 50°C-105°C to obtain an α-MnO2 material rich in highly active lattice oxygen.

[0016] The alcohol in S1 is methanol or ethanol, and the Mn in S2 is2+ The concentration of the saline solution can be controlled.

[0017] Embodiment 1: (1) Dissolve 3 g of KMnO4 in 50 mL of deionized water by magnetic stirring. Then, slowly add 1 mL of anhydrous ethanol solution to the solution while maintaining magnetic stirring.

[0018] (2) The mixed solution was transferred to a 60°C water bath and reacted for 3 hours while maintaining magnetic stirring throughout the reaction process.

[0019] (3) Wash the precipitate three times with deionized water.

[0020] (4) The washed precipitate was dried in an oven at 105°C to obtain a δ-MnO2 catalyst.

[0021] (5) 2.6 g of MnCl2 was dissolved in 100 mL of deionized water, and then 3 g of δ-MnO2 was added to the above solution and reacted in a 60 °C water bath for 3 h. The reaction solution was kept magnetically stirred during the entire reaction process.

[0022] (6) Wash the precipitate three times with deionized water.

[0023] (7) The washed precipitate was dried in an oven at 105°C to obtain a finished catalyst. The XRD characteristic peaks of this sample at 12.7°, 18.0°, 28.7°, 37.6°, 42.0°, 49.9°, 56.2°, 60.2° and 65.5° corresponded to the standard card PDF#72-1982, belonging to cryptomelane-type MnO2, and marked as α-MnO2-1.

[0024] Embodiment 2: (1) Dissolve 3 g of KMnO4 in 50 mL of deionized water by magnetic stirring, and then slowly add 1 mL of anhydrous ethanol solution to the above solution while maintaining magnetic stirring.

[0025] (2) The mixed solution was transferred to a 60°C water bath and reacted for 3 hours while maintaining magnetic stirring throughout the reaction process.

[0026] (3) Wash the precipitate three times with deionized water.

[0027] (4) The washed precipitate was dried in an oven at 105°C to obtain a δ-MnO2 catalyst.

[0028] (5) 3.47 g of MnCl2 was dissolved in 100 mL of deionized water, and then 3 g of δ-MnO2 was added to the above solution and reacted in a 60 °C water bath for 3 h. The reaction solution was kept magnetically stirred during the entire reaction process.

[0029] (6) Wash the precipitate three times with deionized water.

[0030] (7) The washed precipitate was dried in an oven at 105°C to obtain a finished catalyst. The XRD characteristic peaks of this sample at 12.7°, 18.0°, 28.7°, 37.6°, 42.0°, 49.9°, 56.2°, 60.2°, 65.5° and 68.9° corresponded to the standard card PDF#72-1982, belonging to cryptomelane-type MnO2, and marked as α-MnO2-2.

[0031] Embodiment 3: (1) Dissolve 3 g of KMnO4 in 50 mL of deionized water by magnetic stirring, and then slowly add 1 mL of anhydrous ethanol solution to the above solution while maintaining magnetic stirring.

[0032] (2) The mixed solution was transferred to a 60°C water bath and reacted for 3 hours while maintaining magnetic stirring throughout the reaction process.

[0033] (3) Wash the precipitate three times with deionized water.

[0034] (4) The washed precipitate was dried in an oven at 105°C to obtain a δ-MnO2 catalyst.

[0035] (5) 4.34 g of MnCl2 was dissolved in 100 mL of deionized water, and then 3 g of δ-MnO2 was added to the above solution and reacted in a 60 °C water bath for 3 h. The reaction solution was kept magnetically stirred during the entire reaction process.

[0036] (6) Wash the precipitate three times with deionized water.

[0037] (7) The washed precipitate was dried in an oven at 105°C to obtain a finished catalyst. The XRD characteristic peaks of this sample at 12.7°, 18.0°, 28.7°, 37.6°, 42.0°, 49.9°, 56.2°, 60.2°, 65.5° and 68.9° corresponded to the standard card PDF#72-1982, belonging to cryptomelane-type MnO2, and marked as α-MnO2-3.

[0038] Comparative Example: (1) Dissolve 3 g of KMnO4 in 50 mL of deionized water by magnetic stirring, and then slowly add 1 mL of anhydrous ethanol solution to the above solution while maintaining magnetic stirring.

[0039] (2) The mixed solution was transferred to a 60°C water bath and reacted for 3 hours while maintaining magnetic stirring throughout the reaction process.

[0040] (3) Wash the precipitate three times with deionized water.

[0041] (4) The washed precipitate was dried in an oven at 105°C to obtain a finished catalyst. The XRD characteristic peaks of this sample at 12.5°, 25.2°, 37.1° and 65.8° corresponded to the standard card PDF#80-1098, belonging to the birnessite type MnO2, and marked as δ-MnO2.

[0042] Catalyst activity test: Catalyst O3 decomposition performance test conditions: The catalyst catalyzed O3 decomposition performance was tested using a fixed bed reactor evaluation device. 50 mg of 40-60 mesh catalyst was used for the test. The inlet O3 concentration was 100 ppm and the air velocity was 1200 L·g -1 h -1 , the test temperature is 25℃, and the relative humidity RH=50%.

[0043] The test conditions for catalyst activation of PMS and degradation of SMX were as follows: the concentrations of δ-MnO2 and α-MnO2-3 were both 0.25 g / L, the initial concentration of PMS was 10 mM, the initial concentration of SMX was 10 μM, and pH = 7.0.

[0044] The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

Claims

1. A method for preparing manganese dioxide rich in highly active lattice oxygen, characterized in that: The following steps are involved: S1: prepare a potassium permanganate aqueous solution, wherein the potassium permanganate concentration is 0.05-0.5 mol / L, add alcohols dropwise to the prepared potassium permanganate solution, wherein the molar ratio of potassium permanganate to alcohols is 0.2-2, place the mixed solution in a 60°C water bath with magnetic stirring for 3 hours, wash and filter the precipitate, and dry it in an oven at a temperature range of 50°C-105°C to obtain a δ-MnO2 material; S2: Configure different concentrations of Mn 2+ The salt water solution is then added to the δ-MnO2 material prepared in step 1, and the mixed solution is placed in a water bath in the temperature range of 40-90°C with magnetic stirring for 3 hours. The precipitate is washed with water and filtered, and then dried in an oven in the temperature range of 50°C-105°C to obtain an α-MnO2 material rich in highly active lattice oxygen.

2. A method for preparing manganese dioxide rich in highly active lattice oxygen as claimed in claim 1, characterized in that: The alcohol in S1 is methanol or ethanol.

3. A method for preparing manganese dioxide rich in highly active lattice oxygen as claimed in claim 1, characterized in that: S2 Mn 2+ The concentration of the saline solution can be controlled.

4. A manganese dioxide rich in highly active lattice oxygen prepared by the method according to any one of claims 1 to 3.

5. Use of the manganese dioxide rich in highly active lattice oxygen as claimed in claim 4 in catalytic removal of gaseous pollutants under room temperature and humid conditions.

6. Use of the manganese dioxide rich in highly active lattice oxygen as claimed in claim 4 in removing organic pollutants in water.

7. The use according to claim 5, characterized in that: The gaseous pollutant is CO.

8. The use according to claim 6, characterized in that: The organic pollutant in the water is sulfamethoxazole.

9. The use according to claim 5, characterized in that: The catalytic reaction for removing gaseous pollutants is carried out at normal pressure and relatively low temperature.

10. The use according to claim 6, characterized in that: The reaction for removing organic pollutants from water is carried out at normal pressure and relatively low temperature.

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