Preparation method and application of novel cobalt manganese oxide nanosheet

Abstract

The invention relates to the technical field of functional materials, and particularly discloses a novel cobalt manganese oxide nanosheet preparation method and application thereof.The preparation method comprises the steps that a certain amount of cobalt manganese inorganic solution, carbamide, D-glucose and deionized water are subjected to a hydrothermal reaction, centrifugal washing is carried out multiple times, preliminary drying is carried out under the specific temperature condition, and the cobalt manganese oxide nanosheet is obtained; and calcining under a specific activation temperature condition, mixing with a certain amount of chloroauric acid solution, washing, drying and activating to finally prepare the gold-loaded mesoporous cobalt manganese oxide. Compared with a single cobalt-manganese oxide or a traditional catalyst, the preparation method has the advantages that efficient catalytic conversion of substances can be realized under a milder condition, side reactions are reduced, the selectivity of a target product is improved, and the advantages of metal oxides, mesoporous materials, noble metal loading and the like are fused; the defects of the existing material in the related fields are overcome, and the material has considerable application potential in the fields of energy, environment, chemical industry and the like.

Description

Technical Field

[0001] The invention relates to the technical field of functional materials, and in particular to a preparation method and application of a novel cobalt manganese oxide nanosheet. Background Art

[0002] In the field of functional materials technology, with the continuous development of science and technology, the demand for materials with special properties is growing. Metal oxides occupy an important position in functional materials due to their rich physical and chemical properties. Cobalt manganese oxide, as an important transition metal oxide, has good catalytic activity, redox properties and other advantages. Its unique crystal structure and electronic properties make it widely studied and applied in energy storage, catalytic reaction and other fields.

[0003] Mesoporous materials have the advantages of high specific surface area, regular pore structure and adjustable pore size, and show excellent performance in adsorption, separation, catalysis and other processes. Preparing cobalt manganese oxide into a mesoporous structure can significantly increase its specific surface area, increase the number of active sites, and thus improve its performance. Gold, as a precious metal, has unique chemical stability, good conductivity and excellent catalytic activity. Loading gold on other materials can give full play to the excellent properties of gold and achieve synergistic effects with the help of the characteristics of the carrier.

[0004] In actual application scenarios, such as the field of oil-water separation, traditional separation materials often have problems such as low separation efficiency, easy contamination, and poor stability. In terms of catalytic reactions, the above-mentioned functional materials may exhibit unique catalytic properties in some reactions involving organic synthesis, environmental pollutant degradation, etc. (such as oil-water separation). In view of this, the present invention proposes a novel method for preparing gold-loaded mesoporous cobalt manganese oxide to overcome the shortcomings of existing functional materials. Summary of the invention

[0005] The purpose of the present invention is to realize efficient catalytic conversion of catalytic reactions under milder conditions, reduce the occurrence of side reactions, and improve the selectivity of target products, and to propose a novel preparation method and application of cobalt manganese oxide nanosheets.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A preparation method and application of a novel cobalt manganese oxide nanosheet comprises the following steps:

[0008] S1. Preparation of cobalt-manganese metal organic framework: stirring and dissolving a certain amount of D-glucose in a certain amount of deionized water, adding a certain amount of cobalt nitrate hexahydrate and a certain amount of manganese nitrate hexahydrate into the above solution to form a light pink transparent solution A, and dissolving a certain amount of carbonamide in a certain amount of deionized water to form a colorless solution B;

[0009] During the process of vigorously stirring solution A for 10 to 15 minutes, solution B is slowly added to solution A to obtain a final mixed solution, and the final mixed solution is charged into a hydrothermal synthesis reactor, and a cobalt-manganese precursor material is prepared by a hydrothermal method, which can ensure that the inorganic cobalt-manganese solution and organic substances such as carbon amide are fully mixed and reacted, and a light pink product is obtained after centrifugal separation, and after washing with ethanol for 3 to 4 times, the product is charged into a drying furnace at about 60° C. for drying;

[0010] S2, preparation of cobalt-manganese metal nanosheets, calcining the cobalt-manganese metal organic frame obtained in step S1 in a tubular furnace;

[0011] S3, gold loading treatment, taking the particles obtained in step S2 and mixing them with an inorganic gold solution, stirring them evenly, then ultrasonicating and soaking them, and drying them to obtain a gold loaded material;

[0012] S4, high temperature activation, placing the product in step S3 into a tubular furnace, activating it in an air atmosphere, and obtaining the target product after cooling. Nitrogen is filled into the furnace to isolate the air, so that the gold nanoparticles are evenly dispersed on the surface of the manganese cobalt oxide, and oxidation and excessive ablation are effectively prevented to ensure the activity of the catalyst.

[0013] Preferably, the molar ratio of cobalt to manganese in the cobalt-manganese precursor material in step S1 is 2:1.

[0014] Preferably, the temperature of the hydrothermal method in step S1 is 160-180° C., and the hydrothermal time is 10-14 h.

[0015] Preferably, the calcination temperature during the preparation of the cobalt manganese oxide in step S2 is 400-500°C, the calcination time is 2-3h, and the temperature is slowly increased (1°C / min) to a specific temperature (400-500°C), which can remove organic matter in the metal organic framework and introduce a mesoporous structure into the material.

[0016] Preferably, the gold content loaded in step S3 accounts for 1-1.5% of the total mass of the gold-loaded material.

[0017] Preferably, in step S4, the temperature of the tube furnace is 180-200° C., and the activation time is 0.5-4 hours. The temperature of the tube furnace needs to be preheated to the target value before placing the material into the furnace.

[0018] The invention discloses an application of a novel cobalt manganese oxide nanosheet. The nanosheet prepared according to the preparation method can be used as a separation material for water gas pollutants.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention loads gold on mesoporous cobalt manganese oxide. On the one hand, the catalytic performance of gold can be used to improve the activity of the overall material. On the other hand, the high specific surface area and special structure of the mesoporous cobalt manganese oxide can be used to achieve high dispersion of gold, reduce the amount of gold used, and reduce costs.

[0021] 2. The mesoporous gold-loaded cobalt manganese oxide nanosheets of the present invention have the advantages of rich pore structure and large specific surface area, strong toluene adsorption catalytic ability, and resistance to water poisoning, and the preparation method is low in energy consumption and simple in operation, suitable for wide application, especially suitable as a catalyst for gas purification technology under high humidity, achieving the effect of waste treatment and resource utilization;

[0022] 3. Compared with single cobalt manganese oxide or traditional catalysts, the present invention can achieve efficient catalytic conversion of substances under milder conditions, reduce the occurrence of side reactions, and improve the selectivity of target products. It integrates the advantages of metal oxides, mesoporous materials and precious metal loadings, solves the shortcomings of existing materials in related applications, and has considerable application potential in water and gas pollution control in multiple fields such as energy, environment, and chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 SEM and TEM images of cobalt manganese oxide and gold-supported mesoporous cobalt manganese oxide prepared in the embodiments of the present invention;

[0024] Figure 2 This is the XRD pattern of the gold-supported mesoporous cobalt manganese oxide prepared in the embodiment of the present invention;

[0025] Figure 3 Graph showing the performance of the embodiments of the present invention and the comparative example. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0027] Example 1

[0028] Reference Figure 1-3 , a novel method for preparing cobalt manganese oxide nanosheets, as follows:

[0029] Step S1, preparation of cobalt-manganese metal-organic framework, stirring and dissolving 2.97 g of D-glucose in 50 mL of quantitative deionized water, adding 2 mmol of cobalt nitrate hexahydrate and 1 mmol of manganese nitrate hexahydrate to the above solution to form a light pink transparent solution A, dissolving 6.00 g of carbonamide in quantitative deionized water to form a colorless solution B;

[0030] Furthermore, during the process of vigorously stirring solution A for 10 to 15 minutes, solution B is slowly added to solution A to obtain a final mixed solution, and the final mixed solution is charged into a hydrothermal synthesis reactor to prepare a cobalt manganese precursor material by a hydrothermal method. The temperature of the hydrothermal method is 160 to 180°C, and the hydrothermal time is 10 to 14 hours, which can ensure that the inorganic cobalt manganese solution and organic substances such as carbonamide are fully mixed and reacted. A light pink product is obtained after centrifugal separation. After washing with ethanol 3 to 4 times, the product is charged into a drying furnace at about 60°C for drying.

[0031] Step S2, preparation of cobalt-manganese metal nanosheets, taking the cobalt-manganese metal organic framework obtained in step S1 and calcining it in a tube furnace, the calcination temperature is 400-500°C, the calcination time is 2-3h, and the temperature is slowly increased (1°C / min) to a specific temperature (400-500°C), which can remove the organic matter in the metal organic framework and introduce the mesoporous structure into the material. The SEM and TEM images of the product are as follows Figure 1 As shown in (a) and (b).

[0032] Step S3, gold loading treatment, taking the particles obtained in step S2 and mixing them with an inorganic gold solution, stirring them evenly, then ultrasonicating and soaking them, and drying them to obtain a gold loaded material, wherein the loaded gold content accounts for 1 to 1.5% of the total mass of the gold loaded material.

[0033] Step S4, high temperature activation, placing the product in step S3 into a tube furnace, the temperature of the tube furnace is 180-200°C, the activation time is 0.5-4h, the temperature of the tube furnace needs to be preheated to the target value before placing the material into the furnace, and activation is carried out in an air atmosphere, and the target product is obtained after cooling, and nitrogen is filled into the air to isolate the air, so that the gold nanoparticles are evenly dispersed on the surface of the manganese cobalt oxide, and oxidation and excessive ablation are effectively prevented to ensure the activity of the catalyst. The product SEM and TEM are as follows Figure 1 (c) and (d), the XRD patterns are shown in Figure 2 shown.

[0034] Comparative Example 1

[0035] The preparation method of the novel cobalt manganese oxide nanosheets in this comparative example is as follows:

[0036] Step S1, preparation of cobalt-manganese metal-organic framework, stirring and dissolving 2.97 g of D-glucose in 50 mL of quantitative deionized water, adding 2 mmol of cobalt nitrate hexahydrate and 1 mmol of manganese nitrate hexahydrate to the above solution to form a light pink transparent solution A, dissolving 6.00 g of carbonamide in quantitative deionized water to form a colorless solution B;

[0037] Furthermore, during the process of vigorously stirring solution A for 10 to 15 minutes, solution B is slowly added to solution A to obtain a final mixed solution, and the final mixed solution is charged into a hydrothermal synthesis reactor to prepare a cobalt manganese precursor material by a hydrothermal method. The temperature of the hydrothermal method is 160 to 180°C, and the hydrothermal time is 10 to 14 hours, which can ensure that the inorganic cobalt manganese solution and organic substances such as carbonamide are fully mixed and reacted. A light pink product is obtained after centrifugal separation. After washing with ethanol 3 to 4 times, the product is charged into a drying furnace at about 60°C for drying.

[0038] Step S2, preparation of cobalt-manganese metal nanosheets, taking the cobalt-manganese metal organic framework obtained in step S1 and calcining it in a tubular furnace, the calcination temperature is 400-500°C, the calcination time is 2-3h, and the temperature is slowly increased (1°C / min) to a specific temperature (400-500°C), which can remove the organic matter in the metal organic framework and introduce the mesoporous structure into the material.

[0039] The difference between this comparative example 1 and embodiment 1 is that there are no steps S3 and S4.

[0040] Comparative Example 2

[0041] The preparation method of the novel cobalt manganese oxide nanosheets in this comparative example is as follows:

[0042] Step S1, preparation of cobalt-manganese metal-organic framework, stirring and dissolving 2.97 g of D-glucose in 50 mL of quantitative deionized water, adding 2 mmol of cobalt nitrate hexahydrate to the above solution to form a light pink transparent solution A, dissolving 6.00 g of carbonamide in quantitative deionized water to form a colorless solution B;

[0043] Furthermore, during the process of vigorously stirring solution A for 10 to 15 minutes, solution B is slowly added to solution A to obtain a final mixed solution, and the final mixed solution is charged into a hydrothermal synthesis reactor to prepare a cobalt manganese precursor material by a hydrothermal method. The temperature of the hydrothermal method is 160 to 180°C, and the hydrothermal time is 10 to 14 hours, which can ensure that the inorganic cobalt manganese solution and organic substances such as carbonamide are fully mixed and reacted. A light pink product is obtained after centrifugal separation. After washing with ethanol 3 to 4 times, the product is charged into a drying furnace at about 60°C for drying.

[0044] Step S2, preparation of cobalt-manganese metal nanosheets, taking the cobalt-manganese metal organic framework obtained in step S1 and calcining it in a tubular furnace, the calcination temperature is 400-500°C, the calcination time is 2-3h, and the temperature is slowly increased (1°C / min) to a specific temperature (400-500°C), which can remove the organic matter in the metal organic framework and introduce the mesoporous structure into the material.

[0045] Step S3, gold loading treatment, taking the particles obtained in step S2 and mixing them with an inorganic gold solution, stirring them evenly, then ultrasonicating and soaking them, and drying them to obtain a gold loaded material, wherein the loaded gold content accounts for 1 to 1.5% of the total mass of the gold loaded material.

[0046] Step S4, high-temperature activation, placing the product in step S3 into a tubular furnace, the temperature of the tubular furnace is 180-200° C., the activation time is 0.5-4 hours, the temperature of the tubular furnace must be preheated to the target value before placing the material into the furnace, and activation is performed in an air atmosphere. After cooling, the target product is obtained, and nitrogen is filled into the air to isolate the air, so that the gold nanoparticles are evenly dispersed on the surface of the manganese cobalt oxide, and oxidation and excessive ablation are effectively prevented to ensure the activity of the catalyst.

[0047] The difference between Comparative Example 2 and Example 1 is that manganese nitrate hexahydrate is not added.

[0048] like Figure 3 The results show that the catalyst product of Example 1 can catalytically degrade toluene gas by 100% at 148°C, and compared with Comparative Examples 1 and 2, the complete preparation steps and fillers of the example enable the prepared nanosheets to have the ability to achieve efficient catalytic conversion of catalytic reactions under milder conditions.

[0049] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a novel cobalt manganese oxide nanosheet, characterized in that: The following steps are involved: S1. Preparation of cobalt-manganese metal organic framework: stirring and dissolving a certain amount of D-glucose in a certain amount of deionized water, adding a certain amount of cobalt nitrate hexahydrate and a certain amount of manganese nitrate hexahydrate into the above solution to form a light pink transparent solution A, and dissolving a certain amount of carbonamide in a certain amount of deionized water to form a colorless solution B; During the process of vigorously stirring solution A for 10 to 15 minutes, solution B is slowly added to solution A to obtain a final mixed solution, the final mixed solution is charged into a hydrothermal synthesis reactor, and a cobalt-manganese precursor material is prepared by a hydrothermal method, and a light pink product is obtained after centrifugal separation, and after washing with ethanol for 3 to 4 times, the product is charged into a drying furnace at about 60° C. and dried; S2, preparation of cobalt-manganese metal nanosheets, calcining the cobalt-manganese metal organic frame obtained in step S1 in a tubular furnace; S3, gold loading treatment, taking the particles obtained in step S2 and mixing them with an inorganic gold solution, stirring them evenly, then ultrasonicating and soaking them, and drying them to obtain a gold loaded material; S4, high temperature activation, placing the product in step S3 into a tube furnace, activating it in a nitrogen atmosphere, and obtaining the target product after cooling.

2. The method for preparing the novel cobalt manganese oxide nanosheet according to claim 1, characterized in that: The molar ratio of cobalt to manganese in the cobalt-manganese precursor material in step S1 is 2:

1.

3. The method for preparing the novel cobalt manganese oxide nanosheet according to claim 1, characterized in that: The temperature of the hydrothermal method in step S1 is 160-180° C., and the hydrothermal time is 10-14 hours.

4. The method for preparing the novel cobalt manganese oxide nanosheet according to claim 1, characterized in that: The calcination temperature during the preparation of the cobalt manganese oxide in step S2 is 400-500° C., and the calcination time is 2-3 hours.

5. The method for preparing the novel cobalt manganese oxide nanosheet according to claim 1, characterized in that: The gold content loaded in step S3 accounts for 1-1.5% of the total mass of the gold-loaded material.

6. The method for preparing the novel cobalt manganese oxide nanosheet according to claim 1, characterized in that: In step S4, the temperature of the tubular furnace is 180-200° C., and the activation time is 0.5-4 hours. The temperature of the tubular furnace needs to be preheated to the target value before placing the material into the furnace.

7. Application of a novel cobalt manganese oxide nanosheet, characterized in that: The nanosheets prepared by the preparation method according to any one of claims 1 to 6 are used as separation materials for water vapor pollutants.

Images