Preparation method and application of CoMnxFe2-xO4 catalyst

Abstract

The invention discloses a preparation method and application of a CoMnxFe2-xO4 catalyst, and belongs to the technical field of catalyst preparation. Comprising the following steps: S1, dissolving iron nitrate nonahydrate and manganese sulfate in first deionized water to prepare a mixed solution, and adjusting the pH value of the solution with dilute sulfuric acid to obtain a manganese-iron precursor solution; s2, dispersing cobalt dichloride hexahydrate in second deionized water to form a suspension, then adding the mesoporous silica carrier for ultrasonic treatment, stirring and drying in a water bath to obtain a prepared sample, and drying the prepared sample to obtain cobalt dichloride-loaded mesoporous silica; s3, soaking the mesoporous silica loaded with cobalt dichloride into the manganese-iron precursor solution, stirring and soaking at room temperature to obtain a secondary sample, filtering, washing to remove surface ions, and drying; and S4, calcining the dried secondary sample in a tubular furnace to obtain the composite catalyst. The performance of the prepared catalyst is remarkably improved, the activity is basically kept stable, and good stability and anti-poisoning performance are shown.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and specifically relates to a CoMnxFe 2-x Preparation method and application of O4 catalyst. Background Art

[0002] Currently, the ecological environment is subject to various forms of pollution, resulting in a significant deterioration in air and environmental quality, significantly impacting human health and environmental quality. Rapid industrial development has resulted in the generation of large quantities of wastewater, with water pollution accounting for a significant proportion of environmental pollution. Clean water is essential for a healthy life. However, the rapid development of modern society is depleting water resources worldwide, causing irreversible damage to water supply quality. Water pollution is a major environmental issue worldwide.

[0003] Photocatalytic technology offers a new approach to addressing wastewater issues. It is a highly efficient and cost-effective new technology for dye wastewater treatment, with semiconductors often used as specialized photocatalytic materials. When exposed to sunlight, photocatalytic materials absorb specific wavelengths of light and produce redox-active substances, converting pollutants in the wastewater into substances such as H2O and CO2. However, current catalysts suffer from insufficient activity and poor stability in certain complex reaction systems. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a CoMnxFe 2-x The preparation method and application of O4 catalyst, through innovative raw material combination and preparation process, develops a new type of composite catalyst to show excellent catalytic performance in specific reactions and promote technological upgrading in related fields.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a CoMnxFe 2-x A method for preparing an O4 catalyst, comprising the following steps:

[0007] S1, dissolving ferric nitrate nonahydrate and manganese sulfate in first deionized water to prepare a mixed solution, and adjusting the pH value of the solution to 4-5 with dilute sulfuric acid to obtain a manganese-iron precursor solution;

[0008] S2. Dispersing cobalt dichloride hexahydrate in a second deionized water to form a uniform suspension, adding a mesoporous silica support to the suspension, performing ultrasonic treatment, and then stirring and evaporating in a water bath until dry to obtain a preliminary sample, and then drying the preliminary sample in an oven for several hours to obtain mesoporous silica loaded with cobalt dichloride;

[0009] S3, immersing the cobalt dichloride-loaded mesoporous silica in a manganese-iron precursor solution, stirring and impregnating at room temperature to obtain a secondary sample, filtering the secondary sample after the impregnation, washing it with deionized water to remove unadsorbed ions on the surface, and then drying the secondary sample in an oven overnight;

[0010] S4. Place the dried secondary sample in a tube furnace, raise the temperature from room temperature to 450-550° C., and calcine at this temperature to form a composite catalyst.

[0011] Furthermore, in step S2, the ultrasonic treatment time of the mesoporous silica carrier in the suspension is 30-45 minutes; the water bath condition is 55-65°C; the drying temperature of the prepared sample in the oven is 120°C, and the drying time is 4-6 hours.

[0012] Furthermore, in step S3, the stirring and immersion time at room temperature is 12-18 hours; and the secondary sample is dried in an oven at 75-85°C overnight.

[0013] Furthermore, in step S4, the heating rate of the room temperature is 5°C / min, and the calcination temperature after heating is 3-5 hours.

[0014] Furthermore, the molar ratio of the manganese sulfate to the ferric nitrate nonahydrate is 0.2-0.4:1.6-1.8; and the total weight of the manganese sulfate and the ferric nitrate nonahydrate accounts for 5-10% of the first deionized water.

[0015] Furthermore, the molar ratio of the mesoporous silica to the cobalt dichloride hexahydrate is 1:1.8-2.0, and the mesoporous silica and the cobalt dichloride hexahydrate account for 8-12% of the total weight of the second deionized water.

[0016] Furthermore, the CoMnxFe 2-x O4 catalyst is used to degrade tetracycline.

[0017] The beneficial effects of the present invention are:

[0018] 1. In the present invention, the significant synergistic effect between manganese, cobalt and cobalt species is utilized. Since manganese species have multiple variable valence states (Mn 2+ 、Mn 3+ 、Mn 4+ ), can participate in the redox cycle through valence changes during the reaction process and promote electron transfer; in addition, cobalt dichloride hexahydrate itself has good magnetic properties and catalytic activity, and the Co in its spinel structure 2+ 、Co 3+ It can participate in redox reactions, cooperate with manganese species, and enhance the adsorption and activation capabilities of reactant molecules.

[0019] 2. In the present invention, the high specific surface area and rich pore structure of the selected mesoporous silica carrier provide a larger dispersion space for the active components, so that the active components can be highly dispersed and the exposure of the active sites is increased; at the same time, the mesoporous structure of silica is conducive to the rapid diffusion of reactant molecules to the active sites and the rapid departure of product molecules from the catalyst surface, thereby reducing the diffusion resistance of reactants and products in the catalyst pores and improving the efficiency of the catalytic reaction.

[0020] 3. This invention introduces manganese, cobalt, and ferric nitrate into a mesoporous silica support system for the first time, creating a novel multi-component synergistic catalyst system. Furthermore, through an optimized isovolumetric impregnation method and step-by-step calcination process, the loading and distribution of active components on the support surface are precisely controlled, promoting interactions between the active components and forming stable and highly efficient catalytically active centers. Compared with traditional catalyst preparation methods, the preparation process of this invention is more sophisticated and can better control the catalyst's microstructure and performance.

[0021] 4. The catalyst prepared by the present invention has significantly improved catalytic performance. After continuous reaction, the activity of the catalyst remains basically stable, showing good stability and anti-poisoning performance. In addition, the catalyst of the present invention also has high activity, high stability and anti-poisoning performance at low temperature, providing a new solution for the field of catalysis and can be widely used in environmental protection, chemical industry and other industries.

[0022] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the purpose, technical solutions and beneficial effects of the invention clearer, the present invention is described with the following drawings:

[0024] Figure 1 is a SEM image of the catalyst material of the present invention;

[0025] Figure 2 The photocatalytic activity diagram and degradation rate diagram of the catalyst materials prepared with different doping ratios of the present invention for degrading tetracycline are shown. DETAILED DESCRIPTION

[0026] like Figure 1-2 As shown, the present invention provides a CoMnxFe 2-x Preparation method of O4 catalyst.

[0027] In the present invention:

[0028] ① The manganese source is manganese sulfate (MnSO4·H2O) with a purity of not less than 99%. As a source of manganese element, manganese sulfate can more easily participate in chemical reactions in the subsequent preparation process to form catalytically active manganese species;

[0029] ② The carrier uses mesoporous silica (m-SiO2) with a high specific surface area and rich pore structure. Mesoporous silica not only provides a good dispersion carrier for active components, but also promotes the contact between reactants and catalyst active sites and the diffusion of products through its unique pore structure.

[0030] Example 1

[0031] S1, dissolving manganese sulfate and ferric nitrate nonahydrate in a molar ratio of 0.4:1.6 in 30 ml of first deionized water to prepare a mixed solution, adjusting the pH of the solution to 4.5 with dilute sulfuric acid, and stirring uniformly to obtain a manganese-cerium precursor solution;

[0032] S2. Dispersing cobalt dichloride hexahydrate in 30 ml of a second deionized water to form a uniform suspension, slowly adding a mesoporous silica support to the suspension and ultrasonically treating the suspension for 40 minutes (the molar ratio of cobalt dichloride hexahydrate to mesoporous silica is 1:2) to uniformly load the cobalt dichloride hexahydrate on the surface of the mesoporous silica, and then stirring and evaporating the mixture in a 60° C. water bath until dry to obtain a preliminary sample, and then drying the preliminary sample in a 120° C. oven for 5 hours to obtain mesoporous silica loaded with cobalt dichloride;

[0033] S3, immersing the cobalt dichloride-loaded mesoporous silica in a manganese-iron precursor solution and stirring and immersing at room temperature for 15 hours to obtain a secondary sample. After the immersion, the secondary sample is filtered and washed with deionized water five times to remove unadsorbed ions on the surface. The secondary sample is then dried in an oven at 80°C overnight.

[0034] S4. The dried secondary sample is placed in a tubular furnace, and the temperature is raised from room temperature to 500°C at a heating rate of 5°C / min in an air atmosphere, and calcined at this temperature for 4 hours. After the calcination treatment, the manganese-iron material interacts with the mesoporous silica support loaded with cobalt dichloride to form a composite catalyst with a specific structure and catalytic activity.

[0035] Example 2

[0036] S1, dissolving manganese sulfate and ferric nitrate nonahydrate in a molar ratio of 0.3:1.7 in 30 ml of first deionized water to prepare a mixed solution, adjusting the pH of the solution to 4.5 with dilute sulfuric acid, and stirring uniformly to obtain a manganese-cerium precursor solution;

[0037] S2. Dispersing cobalt dichloride hexahydrate in 30 ml of a second deionized water to form a uniform suspension, slowly adding a mesoporous silica support to the suspension and ultrasonically treating the suspension for 40 minutes (the molar ratio of cobalt dichloride hexahydrate to mesoporous silica is 1:1.8) to uniformly load the cobalt dichloride hexahydrate on the surface of the mesoporous silica, and then stirring and evaporating the mixture in a 60° C. water bath until dry to obtain a preliminary sample, and then drying the preliminary sample in a 120° C. oven for 5 hours to obtain mesoporous silica loaded with cobalt dichloride;

[0038] S3, immersing the cobalt dichloride-loaded mesoporous silica in a manganese-iron precursor solution and stirring and immersing at room temperature for 15 hours to obtain a secondary sample. After the immersion, the secondary sample is filtered and washed with deionized water five times to remove unadsorbed ions on the surface. The secondary sample is then dried in an oven at 80°C overnight.

[0039] S4. The dried secondary sample is placed in a tubular furnace, and the temperature is raised from room temperature to 500°C at a heating rate of 5°C / min in an air atmosphere, and calcined at this temperature for 4 hours. After the calcination treatment, the manganese-iron material interacts with the mesoporous silica support loaded with cobalt dichloride to form a composite catalyst with a specific structure and catalytic activity.

[0040] The difference between Example 2 and Example 1 is that the molar ratios of manganese sulfate to ferric nitrate nonahydrate, and cobalt dichloride hexahydrate to mesoporous silica are different, but they are within the scope of protection of the present invention.

[0041] Example 3

[0042] S1, dissolving manganese sulfate and ferric nitrate nonahydrate in a molar ratio of 0.2:1.8 in 30 ml of first deionized water to prepare a mixed solution, adjusting the pH of the solution to 4.5 with dilute sulfuric acid, and stirring uniformly to obtain a manganese-cerium precursor solution;

[0043] S2. Dispersing cobalt dichloride hexahydrate in 30 ml of a second deionized water to form a uniform suspension, slowly adding a mesoporous silica support to the suspension and ultrasonically treating the suspension for 40 minutes (the molar ratio of cobalt dichloride hexahydrate to mesoporous silica is 1:2) to uniformly load the cobalt dichloride hexahydrate on the surface of the mesoporous silica, and then stirring and evaporating the mixture in a 60° C. water bath until dry to obtain a preliminary sample, and then drying the preliminary sample in a 120° C. oven for 5 hours to obtain mesoporous silica loaded with cobalt dichloride;

[0044] S3, immersing the cobalt dichloride-loaded mesoporous silica in a manganese-iron precursor solution and stirring and immersing at room temperature for 15 hours to obtain a secondary sample. After the immersion, the secondary sample is filtered and washed with deionized water five times to remove unadsorbed ions on the surface. The secondary sample is then dried in an oven at 80°C overnight.

[0045] S4. The dried secondary sample is placed in a tubular furnace, and the temperature is raised from room temperature to 500°C at a heating rate of 5°C / min in an air atmosphere, and calcined at this temperature for 4 hours. After the calcination treatment, the manganese-iron material interacts with the mesoporous silica support loaded with cobalt dichloride to form a composite catalyst with a specific structure and catalytic activity.

[0046] The difference between Example 3 and Example 1 is that the molar ratios of manganese sulfate to ferric nitrate nonahydrate, and cobalt dichloride hexahydrate to mesoporous silica are different, but they are within the scope of protection of the present invention.

[0047] In order to demonstrate the superiority of the present invention, comparative examples 1-2 are provided here.

[0048] Comparative Example 1

[0049] S1, dissolving manganese sulfate and ferric nitrate nonahydrate at a molar ratio of 0.5:1.5 in 30 ml of first deionized water to prepare a mixed solution, adjusting the pH of the solution to 4.5 with dilute sulfuric acid, and stirring uniformly to obtain a manganese-cerium precursor solution;

[0050] S2. Dispersing cobalt dichloride hexahydrate in 30 ml of a second deionized water to form a uniform suspension, slowly adding a mesoporous silica support to the suspension and ultrasonically treating the suspension for 40 minutes (the molar ratio of cobalt dichloride hexahydrate to mesoporous silica is 1:2) to uniformly load the cobalt dichloride hexahydrate on the surface of the mesoporous silica, and then stirring and evaporating the mixture in a 60° C. water bath until dry to obtain a preliminary sample, and then drying the preliminary sample in a 120° C. oven for 5 hours to obtain mesoporous silica loaded with cobalt dichloride;

[0051] S3, immersing the cobalt dichloride-loaded mesoporous silica in a manganese-iron precursor solution and stirring and immersing at room temperature for 15 hours to obtain a secondary sample. After the immersion, the secondary sample is filtered and washed with deionized water five times to remove unadsorbed ions on the surface. The secondary sample is then dried in an oven at 80°C overnight.

[0052] S4. The dried secondary sample was placed in a tube furnace and heated from room temperature to 500°C at a heating rate of 5°C / min in an air atmosphere. The sample was then calcined at this temperature for 4 hours. After calcination, the manganese-iron compound interacted with the mesoporous silica support loaded with cobalt dichloride to form a composite catalyst with a specific structure and catalytic activity.

[0053] The difference between Comparative Example 1 and Example 1 is that the molar ratio of the raw materials is changed, wherein the molar ratio of manganese sulfate to ferric nitrate nonahydrate is 0.5:1.5, and the molar ratio of cobalt dichloride hexahydrate to mesoporous silica is 1.5:2.

[0054] Comparative Example 2

[0055] S1, dissolving manganese sulfate and ferric nitrate nonahydrate in a molar ratio of 0.1:1.9 in 30 ml of first deionized water to prepare a mixed solution, adjusting the pH of the solution to 4.5 with dilute sulfuric acid, and stirring uniformly to obtain a manganese-cerium precursor solution;

[0056] S2. Dispersing cobalt dichloride hexahydrate in 30 ml of a second deionized water to form a uniform suspension, slowly adding a mesoporous silica support to the suspension and ultrasonically treating the suspension for 40 minutes (the molar ratio of cobalt dichloride hexahydrate to mesoporous silica is 1:2) to uniformly load the cobalt dichloride hexahydrate on the surface of the mesoporous silica, and then stirring and evaporating the mixture in a 60° C. water bath until dry to obtain a preliminary sample, and then drying the preliminary sample in a 120° C. oven for 5 hours to obtain mesoporous silica loaded with cobalt dichloride;

[0057] S3, immersing the cobalt dichloride-loaded mesoporous silica in a manganese-iron precursor solution and stirring and immersing at room temperature for 15 hours to obtain a secondary sample. After the immersion, the secondary sample is filtered and washed with deionized water five times to remove unadsorbed ions on the surface. The secondary sample is then dried in an oven at 80°C overnight.

[0058] S4. The dried secondary sample was placed in a tube furnace and heated from room temperature to 500°C at a heating rate of 5°C / min in an air atmosphere. The sample was then calcined at this temperature for 4 hours. After calcination, the manganese-iron compound interacted with the mesoporous silica support loaded with cobalt dichloride to form a composite catalyst with a specific structure and catalytic activity.

[0059] The difference between Comparative Example 1 and Example 1 is that the molar ratio of the raw materials is changed, wherein the molar ratio of manganese sulfate to ferric nitrate nonahydrate is 0.1:1.9, and the molar ratio of cobalt dichloride hexahydrate to mesoporous silica is 1:2.

[0060] Figure 1 This is an SEM image of the catalyst of Example 1 of the present invention. It can be seen that the particles of the catalyst powder are small and relatively uniform in size. After manganese doping, the contact between the magnetic particles is hindered, resulting in a weakened agglomeration phenomenon between the particles.

[0061] Verification of the degradation rates of the catalysts obtained in Examples 1-3 and Comparative Examples 1-2:

[0062] Weigh 100 mg of each catalyst and add it to 100 mL of a 40 mg / L tetracycline solution. Ultrasonicate for 2 minutes to disperse the mixture evenly. Then stir in the dark for 30 minutes to allow the pollutants to reach adsorption equilibrium with the catalyst.

[0063] The solution was then exposed to light, with the liquid surface placed approximately 15 cm from the xenon lamp and mechanically stirred. 5 mL of the solution was sampled every 20 minutes for a total of 100 minutes. The centrifuge was set at 3000 rpm for 10 minutes, and the sample was filtered through a membrane filter, and the absorbance was measured. The degradation rate of tetracycline was calculated as follows:

[0064]

[0065] Where:

[0066] R: degradation rate;

[0067] C0: concentration of the initial solution;

[0068] C t : concentration of the solution after t min.

[0069] Depend on Figure 2 It can be seen that the degradation rates of tetracycline by the catalysts vary across the Examples, Comparative Examples, and conditions. In Examples 1-3, when the manganese sulfate concentrations were 0.2%, 0.3%, and 0.4%, respectively, the degradation rates were 70.2%, 60%, and 80.3%, respectively, demonstrating excellent degradation performance. However, in Comparative Examples 1-2, varying the ratios significantly decreased the degradation rates. Therefore, this comparison demonstrates that only when the appropriate amount of doping is present can the photocatalytic performance of the catalyst be enhanced.

[0070] The composite catalyst prepared by the present invention can significantly improve the photocatalytic performance, not only can promote the capture of light, but also can promote the separation of photogenerated electrons and holes, fully expose the photocatalytic sites and have high activity.

[0071] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A CoMnxFe 2-x The preparation method of O4 catalyst is characterized by: The preparation method comprises the following steps: S1, dissolving ferric nitrate nonahydrate and manganese sulfate in first deionized water to prepare a mixed solution, and adjusting the pH value of the solution to 4-5 with dilute sulfuric acid to obtain a manganese-iron precursor solution; S2. Dispersing cobalt dichloride hexahydrate in a second deionized water to form a uniform suspension, adding a mesoporous silica support to the suspension, performing ultrasonic treatment, and then stirring and evaporating in a water bath until dry to obtain a preliminary sample, and then drying the preliminary sample in an oven for several hours to obtain mesoporous silica loaded with cobalt dichloride; S3, immersing the cobalt dichloride-loaded mesoporous silica in a manganese-iron precursor solution, stirring and impregnating at room temperature to obtain a secondary sample, filtering the secondary sample after the impregnation, washing it with deionized water to remove unadsorbed ions on the surface, and then drying the secondary sample in an oven overnight; S4. Place the dried secondary sample in a tube furnace, raise the temperature from room temperature to 450-550° C., and calcine at this temperature to form a composite catalyst.

2. A CoMnxFe according to claim 1 2-x The preparation method of O4 catalyst is characterized by: In step S2, the ultrasonic treatment time of the mesoporous silica carrier in the suspension is 30-45 minutes; the water bath condition is 55-65° C.; the drying temperature of the prepared sample in the oven is 120° C., and the drying time is 4-6 hours.

3. A CoMnxFe according to claim 1-2 2-x The preparation method of O4 catalyst is characterized by: In step S3, the stirring and immersion time at room temperature is 12-18 hours; and the secondary sample is dried in an oven at 75-85° C. overnight.

4. A CoMnxFe according to claim 3 2-x The preparation method of O4 catalyst is characterized by: In step S4, the heating rate of the room temperature is 5°C / min, and the calcination temperature after heating is 3-5 hours.

5. A CoMnxFe according to claim 4 2-x The preparation method of O4 catalyst is characterized by: The molar ratio of the manganese sulfate to the ferric nitrate nonahydrate is 0.2-0.4:1.6-1.8; the total weight of the manganese sulfate and the ferric nitrate nonahydrate accounts for 5-10% of the first deionized water.

6. A CoMnxFe according to claim 1 2-x The preparation method of O4 catalyst is characterized by: The molar ratio of the mesoporous silica to the cobalt dichloride hexahydrate is 1:1.8-2.0, and the mesoporous silica and the cobalt dichloride hexahydrate account for 8-12% of the total weight of the second deionized water.

7. CoMnxFe according to any one of claims 1 to 6 2-x O4 catalyst is used to degrade tetracycline.

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