MoWO4 catalyst derived from metal organic framework as well as preparation method and application of MoWO4 catalyst

Abstract

The invention discloses a metal organic framework-derived MoWO4 catalyst as well as a preparation method and application thereof, and belongs to the technical field of environmental catalytic purification, the prepared metal organic framework-derived MoWO4 catalyst is plate-shaped, the specific surface area of the catalyst is greater than 30m < 2 > / g, and the surface of the catalyst contains a higher proportion of hydroxyl functional groups; the catalyst belongs to a bimetallic oxide catalyst, and the catalytic activity of the catalyst is obviously higher than that of a monometal oxide catalyst; the catalyst prepared by the method provided by the invention has high specific surface area and abundant surface hydroxyl groups as active sites, so that the catalytic activity of the catalyst on PMS activation and sulfadiazine degradation is obviously higher than that of a bimetallic oxide catalyst obtained by a conventional solvothermal synthesis method; the catalyst prepared by the method also has the advantages of good electrochemical performance and high stability, and can play a longer effect on degradation of pollutants.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental catalytic purification, and specifically relates to a metal organic framework-derived MoWO4 catalyst and a preparation method and application thereof. Background Art

[0002] Antibiotics are drugs used to treat bacterial infections and can inhibit or kill bacteria. However, due to the long-term improper use of antibiotics by humans and the immature treatment technology, the water and soil environment around the world is currently facing various degrees of antibiotic pollution. Antibiotics can enter the human body through contaminated water and food, breathing, and skin contact. Long-term low-level antibiotic exposure may increase the risk of human disease. In addition, the continuous release of antibiotics in the environment will not only cause pollution, but also lead to the production of antibiotic-resistant bacteria and antibiotic-resistant genes, which will cause more serious environmental hazards than the antibiotics themselves and become a direct threat to the human immune system. Therefore, it is urgent to find an effective method to remove antibiotics from water. Sulfadiazine is a representative of sulfonamide antibacterial drugs with broad-spectrum antibacterial properties. Sulfadiazine inhibits bacterial dihydrofolate synthase and interferes with the synthesis of folic acid, which is necessary for the synthesis of nucleic acids and proteins, thereby inhibiting bacterial growth and reproduction.

[0003] Metal oxides are an important class of industrial catalysts, and their morphology and structure largely determine their catalytic performance. Due to the influence of their own crystal structure, the activity of lattice oxygen of a single metal oxide is inhibited, which makes it impossible to efficiently catalyze the reaction. Bimetallic oxides have unique surface properties, and they themselves have a variety of catalytic active sites, have advantages such as high conductivity, good anti-poisoning, strong thermal stability, and less environmental damage. At the same time, the selectivity of the catalyst can be optimized by adjusting the ratio and distribution of the metal, so it has become a research hotspot for catalyst preparation materials. For example, Chinese patent CN112547041B provides a method for preparing a tin / tantalum bimetallic oxide catalyst, and the tin / tantalum bimetallic oxide catalyst obtained by the method has excellent dihydroxyacetone to lactic acid catalytic performance, can achieve a dihydroxyacetone conversion rate of 100%, and a lactic acid yield of better than 90%. However, there are few studies on the removal of antibiotics using bimetallic oxide catalysts, especially the removal of sulfadiazine using bimetallic oxide catalysts. Summary of the invention

[0004] The present invention provides a metal organic framework derived MoWO4 catalyst and its preparation method and application. The prepared MoWO4 catalyst has a high specific surface area and abundant surface hydroxyl groups as active sites, which can activate PMS (peroxymonosulfate) to generate hydroxyl radicals (·OH) and sulfate radicals (SO4 ·-), effectively improving the catalytic degradation ability of sulfadiazine.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions: A method for preparing a metal organic framework-derived MoWO4 catalyst comprises the following steps: S1: Add molybdenum acetate tetrahydrate (Mo(OAc)4·4H2O) and tungsten acetate tetrahydrate (W(OAc)6·4H2O) into 50 mL of deionized water and stir for 10 min at room temperature to obtain a molybdenum tungsten solution; S2: Dissolve 0.4 mmol 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA) in 20-30 ml 80 mmol / L NaOH solution, and stir for 15 min at room temperature to obtain an alkaline solution of 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA); S3: Add the alkaline solution of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) dropwise into the molybdenum tungsten solution, and stir the reaction at room temperature for 30 minutes; S4: transferring the obtained MoW2-ptcda mixture into a high temperature reactor and heating it at 150°C for 4h; S5: The MoW2-ptcda mixture obtained after heating is cooled to room temperature and centrifuged, and the precipitate is collected, washed with deionized water and dried at 60° C. for 6 hours to obtain the MoW2-ptcda MOF material; S6: Under the protection of nitrogen atmosphere, the MoW2-ptcda MOF material was heated to 400°C at a rate of 5°C / min and maintained at the peak temperature for 1.5 h, and then cooled to room temperature to obtain a metal organic framework-derived MoWO4 catalyst.

[0006] In the above steps, the stirring rate in S1, S2 and S3 is 120-150 r / min.

[0007] The molar ratio of molybdenum acetate tetrahydrate (Mo(OAc)4·4H2O) and tungsten acetate tetrahydrate (W(OAc)6·4H2O) added to deionized water in S1 is 1:2, the molybdenum acetate tetrahydrate (Mo(OAc)4·4H2O) added ranges from 0.2 to 0.3 mmol, and the tungsten acetate tetrahydrate (W(OAc)6·4H2O) added ranges from 0.4 to 0.6 mmol.

[0008] The MoWO4 catalyst derived from the metal organic framework prepared above is arranged in a uniform plate shape, the metal is evenly distributed on the surface of the plate catalyst, and the surface contains a high proportion of hydroxyl functional groups; the length of the plate is 0.3~0.5μm, the thickness is 0.1~0.2μm; the specific surface area of ​​the catalyst is greater than 30m 2 / g.

[0009] The catalyst prepared above can be used for catalytic degradation of sulfadiazine.

[0010] Beneficial effects: The present invention provides a metal organic framework derived MoWO4 catalyst and its preparation method and application, which has the following advantages over the prior art: (1) The metal organic framework-derived MoWO4 catalyst prepared in the present invention is a bimetallic oxide catalyst, and its catalytic activity is significantly higher than that of a single metal oxide catalyst. Due to the influence of its own crystal structure, the activity of the lattice oxygen of a single metal oxide is inhibited, which makes it impossible to efficiently catalyze the reaction. The bimetallic oxide prepared in the present invention has unique surface properties and has multiple catalytic active sites. It has the advantages of high electrical conductivity, good anti-poisoning, strong thermal stability and less environmental harm. At the same time, the selectivity of the catalyst can be optimized by adjusting the proportion and distribution of the metals; (2) The catalyst prepared by the method of the present invention has a high specific surface area and abundant surface hydroxyl groups as active sites, which makes its catalytic activity for PMS activation and sulfadiazine degradation significantly higher than that of the bimetallic oxide catalyst obtained by the conventional solvothermal synthesis method; (3) The catalyst prepared by the method of the present invention has a higher Mo 2+ and W 4+ ratio, which enables it to efficiently activate PMS and catalyze the degradation of sulfadiazine. PMS accepts Mo 2+ and W 4+ The electrons donated generate sulfate radicals (SO4 ·- ), sulfate radical (SO4 ·- ) has strong oxidizing properties, can catalyze the opening of the benzene ring and the removal of the amino group, and promote the degradation of sulfadiazine. In addition, the catalyst prepared by the present invention can also generate a variety of free radicals such as hydroxyl radicals (·OH) and singlet oxygen in the reaction system, further improving the catalytic reaction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the preparation process of the metal organic framework-derived MoWO4 catalyst in an embodiment of the present invention, in which the yellow part of the MoWO4 catalyst obtained in the figure represents the catalyst MoWO4 body, and the orange and blue circles represent molybdenum ions and tungsten ions; Figure 2 Schematic diagram of the catalytic conversion rate of sulfadiazine by MoWO4 catalyst prepared in Examples 1-3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0012] The present invention is described in detail and completely below with reference to the accompanying drawings and specific embodiments: Example 1

[0013] like Figure 1 As shown, a method for preparing a metal organic framework-derived MoWO4 catalyst specifically comprises the following steps: 0.2 mmol of molybdenum acetate tetrahydrate (Mo(OAc)4·4H2O) and 0.4 mmol of tungsten acetate tetrahydrate (W(OAc)6·4H2O) were added to 50 mL of deionized water and stirred at room temperature for 10 min to obtain a molybdenum tungsten solution; Dissolve 0.4 mmol of 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA) in 20 ml of 80 mmol / L NaOH solution, and stir for 15 min at room temperature to obtain an alkaline solution of 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA). The alkaline solution of 3,4,9,10-perylenetetracarboxylic dianhydride was added dropwise into the molybdenum tungstate solution, and the mixture was stirred at room temperature for 30 minutes to obtain a MoW2-ptcda mixed solution; The obtained MoW2-ptcda mixed solution was transferred to a high-temperature reactor lined with polytetrafluoroethylene and heated at 150°C for 4 h; The MoW2-ptcda mixed solution obtained after heating was cooled to room temperature and centrifuged, and the precipitate was collected, washed with deionized water, and dried at 60° C. for 6 hours to obtain the MoW2-ptcda MOF material; Under the protection of nitrogen atmosphere, the MOF material was heated to 400°C at a rate of 5°C / min and maintained at the peak temperature for 1.5h, and then cooled to room temperature to obtain a metal organic framework-derived MoWO4 catalyst. Example 2

[0014] like Figure 1 As shown, a method for preparing a metal organic framework-derived MoWO4 catalyst specifically comprises the following steps: 0.3 mmol of molybdenum acetate tetrahydrate (Mo(OAc)4·4H2O) and 0.6 mmol of tungsten acetate tetrahydrate (W(OAc)6·4H2O) were added to 50 mL of deionized water and stirred at room temperature for 10 min to obtain a molybdenum tungsten solution; Dissolve 0.4 mmol of 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA) in 30 ml of 80 mmol / L NaOH solution, and stir for 15 min at room temperature to obtain an alkaline solution of 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA). Add the alkaline solution of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) dropwise into the molybdenum tungsten solution and stir the reaction at room temperature for 30 minutes. The obtained MoW2-ptcda mixture was transferred to a high-temperature reactor lined with polytetrafluoroethylene and heated at 150 °C for 4 h; The MoW2-ptcda mixture obtained after heating was cooled to room temperature and centrifuged, and the precipitate was collected, washed with deionized water, and dried at 60° C. for 6 hours to obtain the MoW2-ptcda MOF material; Under the protection of nitrogen atmosphere, the MOF material was heated to 400°C at a rate of 5°C / min and maintained at the peak temperature for 1.5h, and then cooled to room temperature to obtain a metal organic framework-derived MoWO4 catalyst. Example 3

[0015] like Figure 1 As shown, a method for preparing a metal organic framework-derived MoWO4 catalyst specifically comprises the following steps: 0.26mmol of molybdenum acetate tetrahydrate (Mo(OAc)4·4H2O) and 0.52mmol of tungsten acetate tetrahydrate (W(OAc)6·4H2O) were added to 50mL of deionized water and stirred at room temperature for 10min to obtain a molybdenum tungsten solution; Dissolve 0.4 mmol of 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA) in 25 ml of 80 mmol / L NaOH solution, and stir for 15 min at room temperature to obtain an alkaline solution of 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA). Add the alkaline solution of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) dropwise into the molybdenum tungsten solution and stir the reaction at room temperature for 30 minutes; The obtained MoW2-ptcda mixture was transferred to a high-temperature reactor lined with polytetrafluoroethylene and heated at 150 °C for 4 h; The MoW2-ptcda mixture obtained after heating was cooled to room temperature and centrifuged, and the precipitate was collected, washed with deionized water, and dried at 60° C. for 6 hours to obtain the MoW2-ptcda MOF material; Under the protection of nitrogen atmosphere, the MOF material was heated to 400°C at a rate of 5°C / min and maintained at the peak temperature for 1.5h, and then cooled to room temperature to obtain a metal organic framework-derived MoWO4 catalyst.

[0016] Comparative Example 1 According to the ratio of 1:2, 0.25mmol Co(NO3)2·6H2O and Fe(NO3)3·9H2O were weighed and dissolved in 50ml deionized water, and 5~10M NaOH solution was added to adjust the pH to 11~13, and then ultrasonic and stirred to mix evenly to obtain a reddish brown mixed solution. Then the mixed solution was transferred to a high-temperature reactor lined with polytetrafluoroethylene, and reacted at a reaction temperature of 160°C for 12h under vacuum conditions. The material was collected and placed in an oven at 100°C for thorough drying to prepare the required CoFe2O4 catalyst.

[0017] The MoWO4 catalyst prepared in Examples 1 to 3, the CoFe2O4 catalyst prepared in Comparative Example 1, and potassium persulfate complex salt PMS were placed in 250 ml conical flasks (the catalyst dosage was 0.2 g / L, and the PMS dosage was 0.4 mmol / L), and 100 ml of a properly prepared 50 mg / L sulfadiazine solution was added in sequence. Each conical flask was placed in a constant temperature incubator, and the reaction was carried out at 130°C and 120 rpm for 1 hour. The residual concentration of sulfadiazine in the solution after the reaction was determined by the liquid chromatography internal standard method, and the catalytic conversion rate of the prepared catalyst to sulfadiazine was calculated based on the difference between the initial concentration and the residual concentration. The specific catalytic conversion rate of sulfadiazine is shown in Table 1. In Tables 1 and Figure 2 , Example 1 is represented by E1, Example 2 is represented by E2, Example 3 is represented by E3, and Comparative Example 1 is represented by F1.

[0018] Table 1 Catalytic conversion rates of sulfadiazine by the catalysts prepared in Examples 1 to 3 and Comparative Example 1

[0019] From Table 1 and Figure 2It can be seen that the metal organic framework derived MoWO4 catalyst examples prepared by the method of the present invention can achieve efficient catalytic conversion of sulfadiazine in a relatively short time, and the catalytic conversion rate is above 90% under the reaction conditions of a temperature of 130°C and a reaction time of 1h. However, the catalytic conversion rate of sulfadiazine under the same conditions of the CoFe2O4 catalyst prepared by the conventional solvent thermal synthesis method in comparative example 1 is less than 70%, indicating that the metal organic framework derived MoWO4 catalyst provided by the present invention has excellent catalytic conversion performance of sulfadiazine. In the embodiment of the present invention, the ratio of molybdenum acetate to tungsten acetate is maintained at 1:2 when preparing the catalyst. The prepared catalyst has higher stability during the catalytic process and contains abundant surface hydroxyl groups as active sites, so that a better catalytic effect can be achieved.

[0020] The above are only preferred embodiments of the present invention, which will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those skilled in the art, without departing from the concept of the present invention, several modifications and improvements made are all protected by the present invention.

Claims

1. A metal organic framework derived MoWO4 catalyst, characterized in that: The metal organic framework derived MoWO4 catalyst is arranged in a uniform plate shape, the metal is evenly distributed on the plate surface, and the surface contains hydroxyl functional groups.

2. The metal organic framework derived MoWO4 catalyst according to claim 1, characterized in that The specific surface area of ​​the catalyst is greater than 30 m 2 / g.

3. A method for preparing a metal organic framework derived MoWO4 catalyst, characterized in that: The following steps are involved: S1: adding molybdenum acetate tetrahydrate and tungsten acetate tetrahydrate into deionized water at room temperature, and mixing them evenly to obtain a molybdenum tungsten solution; S2: dissolving 3,4,9,10-perylenetetracarboxylic acid dianhydride in an alkaline solution at room temperature, and mixing them uniformly to obtain an alkaline solution of 3,4,9,10-perylenetetracarboxylic acid dianhydride; S3: adding the alkaline solution of 3,4,9,10-perylenetetracarboxylic dianhydride dropwise into the molybdenum tungstate solution, stirring and reacting at room temperature to obtain a MoW2-ptcda mixed solution; S4: heating the obtained MoW2-ptcda mixed solution, cooling it to room temperature after heating, collecting the precipitate by centrifugation, washing and drying it to obtain the MoW2-ptcda MOF material; S5: The MoW2-ptcda MOF material is heated under the protection of an inert gas atmosphere and then cooled to room temperature to obtain a metal organic framework-derived MoWO4 catalyst.

4. The method for preparing the metal organic framework derived MoWO4 catalyst according to claim 1, characterized in that: The molar ratio of the molybdenum acetate tetrahydrate to the tungsten acetate tetrahydrate is 1:

2.

5. The method for preparing the metal organic framework derived MoWO4 catalyst according to claim 3 or 4, characterized in that: The amount of the molybdenum acetate tetrahydrate added is in the range of 0.2-0.3 mmol, the amount of the tungsten acetate tetrahydrate added is in the range of 0.4-0.6 mmol; and the amount of 3,4,9,10-perylenetetracarboxylic dianhydride used is 0.4 mmol.

6. The method for preparing the metal organic framework derived MoWO4 catalyst according to claim 3, characterized in that: The stirring rate in S1, S2 and S3 is 120-150 r / min.

7. The method for preparing the metal organic framework derived MoWO4 catalyst according to claim 3, characterized in that: The heating temperature in S4 is 150°C and the heating time is 4h.

8. The method for preparing the metal organic framework derived MoWO4 catalyst according to claim 3, characterized in that: In S5, the MoW2-ptcda MOF material was heated to 400°C at a rate of 5°C / min and maintained at the peak temperature for 1.5 h.

9. The MoWO4 catalyst derived from the metal organic framework according to any one of claims 1 to 2 is used to remove antibiotic pollutants.

10. The use of the metal organic framework derived MoWO4 catalyst according to claim 9, characterized in that: The catalyst is used for removing sulfadiazine. The catalyst and PMS are added into a solution containing sulfadiazine to catalyze the degradation of sulfadiazine.

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