Mn3N2-based advanced oxidation catalyst and preparation method thereof

Abstract

The invention discloses an advanced oxidation catalyst based on Mn3N2 and a preparation method, and belongs to the field of advanced oxidation catalysis of heterogeneous catalysts, synthesis of a precursor is completed by means of two steps of low-temperature water bath pre-coordination and hydrothermal synthesis, PVP is added in batches in a low-temperature water bath stage and a hydrothermal stage, and the precursor is prepared through a hydrothermal synthesis method. The effects of protecting the low-dimensional crystal nucleus and preventing the nano-particles from growing are respectively achieved. And calcining to obtain the Mn3N2 nano-particle catalyst with high dispersion and high specific surface area. The Mn3N2 catalyst prepared through the method is high in efficiency and large in catalytic activity specific surface area, the anchoring effect of nitrogen atoms on manganese ions is high, metal ions are not prone to being dissolved out, and meanwhile synthesis of Mn3N2 does not depend on large equipment and is simple and easy to implement.

Description

Technical Field

[0001] The present invention belongs to the field of advanced oxidation catalysis of heterogeneous catalysts, and specifically relates to a method based on Mn 3 N 2 Advanced oxidation catalyst and preparation method thereof. Background Art

[0002] Antibiotics play an important role in human life safety, but antibiotics are absorbed and transformed in organisms, and then excreted in the form of metabolites, and some are still excreted in their original form. Even after treatment, trace residues will still enter the water environment and even the water cycle. Long-term drinking of contaminated water will pose a great threat to human life and health. Therefore, how to more thoroughly remove antibiotics from sewage has become a new challenge. In current research, advanced oxidation processes (AOPs) have attracted much attention due to their high efficiency in degradation rates. This method mainly utilizes the generated reactive oxygen species, such as sulfate radicals (SO4-·), hydroxyl radicals (·OH) and singlet oxygen ( 1 O 2 ) completes the organic matter degradation process.

[0003] Transition metals can effectively activate persulfate to degrade antibiotics, and have the advantages of low cost, low energy consumption, and easy promotion. Compared with manganese oxide, manganese nitride has the advantages of variable valence, flexible electronic structure and electron mobility, and metal ion is not easy to penetrate. However, manganese nitride Mn 3 N 2 Research in advanced oxidation technology is relatively rare. 3 N 2 The commonly used synthesis methods are magnetron sputtering, vapor deposition, and metal nitriding, which rely on large equipment. More importantly, the products obtained by the above methods have a relatively flat surface and a small specific surface area, which is not conducive to providing abundant reaction sites and catalytic sites for catalytic reactions. Therefore, a simple Mn 3 N 2 The preparation method increases the specific surface area of ​​the synthetic material, which is of great significance to improving its application value in advanced catalytic oxidation technology. Summary of the invention

[0004] The purpose of the present invention is to provide a Mn-based 3 N 2 Advanced oxidation catalyst and preparation method to solve the problems of poor efficiency, small catalytic activity specific surface area and metal ion dissolution in the reaction process of manganese-based catalysts in the prior art, and simplify and optimize Mn 3 N 2 Complex synthesis process.

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

[0006] A Mn-based 3 N 2 A method for preparing an advanced oxidation catalyst comprising:

[0007] S1: Mix N-N-dimethylformamide and ethanol to prepare solution A;

[0008] S2: adding manganese chloride and polyvinyl pyrrolidone from which crystal water has been removed by heating to solution A, and stirring until completely dissolved to obtain solution B;

[0009] S3: adding 5,10,15,20-tetracarboxyphenylporphyrin to solution B, stirring until completely dissolved, obtaining solution C, and reacting solution C in a water bath to obtain liquid D;

[0010] S4: adding polyvinyl pyrrolidone to solution D, stirring to dissolve, and then performing a hydrothermal reaction. After the reaction is completed, centrifugation and drying are performed to obtain a powder sample E;

[0011] S5: Powder sample E is heat treated in an inert gas atmosphere to obtain Mn 3 N 2 .

[0012] Preferably, in S1, N-N-dimethylformamide and ethanol are mixed in a volume ratio of 1:3 to 1:1.

[0013] Preferably, in S2, 0.5 g to 1.0 g of manganese chloride and 10 mg to 20 mg of polyvinyl pyrrolidone are dissolved in 40 mL to 70 mL of solvent A and stirred until completely dissolved to obtain solution B.

[0014] Preferably, in S3, 12 mg to 24 mg of 5,10,15,20-tetracarboxyphenylporphyrin is dissolved in solution B and stirred until completely dissolved to obtain solution C.

[0015] Preferably, in S3, the liquid D is obtained by reacting in a water bath at 50° C. to 80° C. for 20 to 30 minutes.

[0016] Preferably, in S4, 10 mg to 20 mg of polyvinyl pyrrolidone is added to solution D and stirred to dissolve, followed by hydrothermal reaction at 80° C. for 18 to 24 hours, and powder sample E is obtained by centrifugal drying and collection.

[0017] Preferably, 10 mg to 20 mg of polyvinyl pyrrolidone is added to the solution D and stirred to dissolve, and then the solution is transferred to a polytetrafluoroethylene liner and sealed in a stainless steel hydrothermal autoclave and locked to perform a hydrothermal reaction at 80° C. to 100° C. for 18 to 24 hours.

[0018] Preferably, in S5, the powder sample E is placed in a porcelain boat and heat treated in a tube furnace under an inert gas atmosphere for 2 to 3 hours to obtain Mn 3 N 2 .

[0019] Preferably, in S5, the heat treatment is performed in an argon or nitrogen atmosphere at a temperature of 500°C to 650°C.

[0020] The present application also discloses a method based on Mn 3 N 2 The advanced oxidation catalyst is prepared by any one of the preparation methods described above.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The Mn provided by the present invention 3 N 2 The preparation method is that the synthesis of the precursor is completed in two steps by means of low-temperature water bath pre-coordination and hydrothermal synthesis. In the low-temperature water bath stage and the hydrothermal stage, PVP is added in batches to protect the low-dimensional crystal nucleus and prevent the growth of nanoparticles. Through calcination, Mn with high dispersion and high specific surface area is obtained. 3 N 2 Nanoparticle catalyst. The Mn prepared by this method 3 N 2 The catalyst has high efficiency, large catalytic activity specific surface area, strong anchoring effect of nitrogen atoms on manganese ions, and metal ions are not easy to dissolve. 3 N 2 The synthesis does not rely on large equipment and is simple and easy; it avoids the dependence on large equipment in conventional magnetron sputtering, vapor deposition, etc., and the synthesis method is simpler and safer, and the synthesized Mn 3 N 2 The specific surface area is larger, which can provide more catalytic active sites.

[0023] The Mn synthesized by the present invention 3 N 2 It has high efficiency in electron mobility and is highly efficient in catalyzing the decomposition of PMS to produce active oxygen. Nitrogen atoms can anchor manganese ions, effectively inhibiting the dissolution of manganese ions, improving the reusability of the catalyst, and avoiding secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 Mn 3 N 2 Scanning electron microscope photos of

[0026] Figure 2 Mn 3 N 2 Degradation curve of catalytic degradation of methylene blue. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0030] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0031] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0032] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0034] The technical solution provided by the present invention is: a method based on Mn 3 N 2 A method for preparing an advanced oxidation catalyst comprising:

[0035] S1: N-N-dimethylformamide (DMF) and ethanol are mixed to prepare solution A;

[0036] S2: adding manganese chloride and polyvinylpyrrolidone (PVP) from which crystal water is removed by heating to solution A, and stirring until completely dissolved to obtain solution B;

[0037] S3: Add 5,10,15,20-tetracarboxyphenylporphyrin (TCPP) to solution B and continue magnetic stirring until the drug is completely dissolved to obtain solution C. Transfer solution C to a distillation flask and react in a 60°C water bath to obtain liquid D.

[0038] S4: Add polyvinyl pyrrolidone (PVP) to solution D, stir and dissolve, transfer to a polytetrafluoroethylene liner, seal and lock in a stainless steel hydrothermal autoclave at 80°C for hydrothermal reaction, and collect by centrifugation and drying to obtain powder sample E;

[0039] S5: The collected powder sample E is then placed in a porcelain boat and heat treated in a tube furnace under an inert gas atmosphere to obtain Mn 3 N 2 .

[0040] In some embodiments, in S1, DMF and ethanol are mixed in a volume ratio of 1:3 to 1:1.

[0041] In some embodiments, in S2, 0.5 g to 1.0 g of manganese chloride and 10 mg to 20 mg of polyvinyl pyrrolidone are dissolved in 40 mL to 70 mL of solvent A and stirred until completely dissolved to prepare solution B.

[0042] In some embodiments, in S3, 12 mg to 24 mg of 5,10,15,20-tetracarboxyphenylporphyrin is dissolved in solution B and stirred until completely dissolved to obtain solution C, which is reacted in a water bath at 60° C. for 20 to 30 minutes to obtain liquid D.

[0043] In some embodiments, in S4, 10 mg to 20 mg of polyvinyl pyrrolidone (PVP) is added to solution D, stirred and dissolved, and then transferred to a polytetrafluoroethylene liner, sealed and locked in a stainless steel hydrothermal autoclave, and subjected to hydrothermal reaction at 80° C. for 18 to 24 hours, and then centrifuged and dried to obtain a powder sample E;

[0044] In some embodiments, in S5, heat treatment is performed in an argon or nitrogen atmosphere at a temperature of 500° C. to 650° C. for 2 to 3 hours.

[0045] In some embodiments, a Mn-based 3 N 2 A method for preparing an advanced oxidation catalyst comprising:

[0046] Step 1: N-N-dimethylformamide (DMF) and ethanol are mixed in a volume ratio of 1:3 to 1:1 to prepare solution A;

[0047] Step 2: Add 0.5 g to 1.0 g of manganese chloride from which crystal water is removed by heating and 10 mg to 20 mg of polyvinyl pyrrolidone (PVP) to 40 mL to 70 mL of solution A, and stir until completely dissolved to prepare solution B;

[0048] Step 3: Add 12 mg to 24 mg of 5,10,15,20-tetracarboxyphenylporphyrin (TCPP) to solution B and continue magnetic stirring until the drug is completely dissolved to obtain solution C. Transfer solution C to a distillation flask and react in a 60°C water bath for 20 to 30 minutes to obtain liquid D.

[0049] Step 4: Add 10 mg to 20 mg of polyvinyl pyrrolidone (PVP) to solution D, stir to dissolve, transfer to a polytetrafluoroethylene liner, seal and lock in a stainless steel hydrothermal autoclave to perform a hydrothermal reaction at 80° C. for 18 to 24 hours, and collect by centrifugation and drying to obtain a powder sample E;

[0050] Step 5: Then, the collected powder sample E is placed in a porcelain boat and heat treated in a tube furnace under an argon or nitrogen atmosphere at a temperature of 500°C to 650°C for 2 to 3 hours to obtain Mn3 N 2 .

[0051] Embodiment 1:

[0052] Step 1: N-N-dimethylformamide (DMF) and ethanol are mixed in a volume ratio of 1:3 to prepare solution A;

[0053] Step 2: Add 0.5 g of manganese chloride from which crystal water is removed by heating and 10 mg of polyvinyl pyrrolidone (PVP) to 40 mL of solution A and stir until completely dissolved to prepare solution B;

[0054] Step 3: Add 12 mg of 5,10,15,20-tetracarboxyphenylporphyrin (TCPP) to solution B and continue magnetic stirring until the drug is completely dissolved to obtain solution C. Transfer solution C to a distillation flask and react in a 60°C water bath for 30 minutes to obtain liquid D.

[0055] Step 4: Add 10 mg of polyvinyl pyrrolidone (PVP) to solution D, stir and dissolve, transfer to a polytetrafluoroethylene liner, seal and lock in a stainless steel hydrothermal autoclave, perform hydrothermal reaction at 80°C for 18 hours, and collect by centrifugation and drying to obtain powder sample E;

[0056] Step 5: The collected powder sample E is then placed in a porcelain boat and heat treated in a tube furnace under an argon or nitrogen atmosphere at 600°C for 2 h to obtain Mn 3 N 2 .

[0057] Embodiment 2:

[0058] Step 1: N-N-dimethylformamide (DMF) and ethanol are mixed in a volume ratio of 1:2 to prepare solution A;

[0059] Step 2: Add 1.0 g of manganese chloride from which crystal water is removed by heating and 20 mg of polyvinyl pyrrolidone (PVP) to 70 mL of solution A and stir until completely dissolved to prepare solution B;

[0060] Step 3: Add 24 mg of 5,10,15,20-tetracarboxyphenylporphyrin (TCPP) to solution B and continue magnetic stirring until the drug is completely dissolved to obtain solution C. Transfer solution C to a distillation flask and react in a 60°C water bath for 20 minutes to obtain liquid D.

[0061] Step 4: Add 20 mg of polyvinyl pyrrolidone (PVP) to solution D, stir and dissolve, transfer to a polytetrafluoroethylene liner, seal and lock in a stainless steel hydrothermal autoclave, perform hydrothermal reaction at 80°C for 20 hours, and collect by centrifugation and drying to obtain powder sample E;

[0062] Step 5: The collected powder sample E is then placed in a porcelain boat and heat treated in a tube furnace under an argon or nitrogen atmosphere at 650°C for 2 h to obtain Mn 3 N 2 .

[0063] Embodiment 3:

[0064] Step 1: N-N-dimethylformamide (DMF) and ethanol are mixed in a volume ratio of 1:2 to prepare solution A;

[0065] Step 2: Add 0.8 g of manganese chloride from which crystal water is removed by heating and 16 mg of polyvinyl pyrrolidone (PVP) to 60 mL of solution A and stir until completely dissolved to prepare solution B;

[0066] Step 3: Add 20 mg of 5,10,15,20-tetracarboxyphenylporphyrin (TCPP) to solution B and continue magnetic stirring until the drug is completely dissolved to obtain solution C. Transfer solution C to a distillation flask and react in a 70°C water bath for 25 minutes to obtain liquid D.

[0067] Step 4: Add 16 mg of polyvinyl pyrrolidone (PVP) to solution D, stir and dissolve, transfer to a polytetrafluoroethylene liner, seal and lock in a stainless steel hydrothermal autoclave, perform hydrothermal reaction at 85°C for 18 hours, and collect by centrifugation and drying to obtain powder sample E;

[0068] Step 5: The collected powder sample E was then placed in a porcelain boat and heat treated in a tube furnace under an argon or nitrogen atmosphere at 600°C for 2.5 h to obtain Mn 3 N 2 .

[0069] Embodiment 4:

[0070] Step 1: N-N-dimethylformamide (DMF) and ethanol are mixed in a volume ratio of 1:1.5 to prepare solution A;

[0071] Step 2: Add 0.6 g of manganese chloride from which crystal water is removed by heating and 12 mg of polyvinyl pyrrolidone (PVP) to 45 mL of solution A and stir until completely dissolved to prepare solution B;

[0072] Step 3: Add 15 mg of 5,10,15,20-tetracarboxyphenylporphyrin (TCPP) to solution B and continue magnetic stirring until the drug is completely dissolved to obtain solution C. Transfer solution C to a distillation flask and react in a water bath at 65°C for 30 minutes to obtain liquid D.

[0073] Step 4: Add 14 mg of polyvinyl pyrrolidone (PVP) to solution D, stir and dissolve, transfer to a polytetrafluoroethylene liner, seal and lock in a stainless steel hydrothermal autoclave, perform hydrothermal reaction at 90°C for 22 hours, and collect by centrifugation and drying to obtain powder sample E;

[0074] Step 5: Then, the collected powder sample E was placed in a porcelain boat and heat treated in a tube furnace under an argon or nitrogen atmosphere at a temperature of 500°C for 3 hours to obtain Mn 3 N 2 .

[0075] Embodiment 5:

[0076] Step 1: N-N-dimethylformamide (DMF) and ethanol are mixed in a volume ratio of 1:1 to prepare solution A;

[0077] Step 2: Add 0.9 g of manganese chloride from which crystal water is removed by heating and 18 mg of polyvinyl pyrrolidone (PVP) to 65 mL of solution A and stir until completely dissolved to prepare solution B;

[0078] Step 3: Add 20 mg of 5,10,15,20-tetracarboxyphenylporphyrin (TCPP) to solution B and continue magnetic stirring until the drug is completely dissolved to obtain solution C. Transfer solution C to a distillation flask and react in a water bath at 80°C for 20 minutes to obtain liquid D.

[0079] Step 4: Add 20 mg of polyvinyl pyrrolidone (PVP) to solution D, stir and dissolve, transfer to a polytetrafluoroethylene liner, seal and lock in a stainless steel hydrothermal autoclave, perform hydrothermal reaction at 100°C for 20 hours, and collect by centrifugation and drying to obtain powder sample E;

[0080] Step 5: The collected powder sample E was then placed in a porcelain boat and heat treated in a tube furnace under an argon or nitrogen atmosphere at 580°C for 3 h to obtain Mn 3 N 2 .

[0081] Figure 1 Mn has a high specific surface area 3 N 2 Scanning photo of the prepared Mn 3 N 2 It is composed of nanoparticles with large specific surface area and rich pore structure, which further increases the Mn 3 N 2 The action site of catalyst and persulfate.

[0082] Mn 3 N 2The catalytic performance of PMS in the degradation of methylene blue was evaluated. Figure 2 Shown in Mn 3 N 2 Under the action of Mn, 99.9% of methylene blue can be degraded within 20 minutes, indicating that Mn 3 N 2 Has excellent catalytic performance.

[0083] In summary, the present invention discloses a method based on Mn 3 N 2 Advanced oxidation catalyst and preparation method thereof. The precursor is synthesized in two steps by means of low-temperature water bath pre-coordination and hydrothermal synthesis. In the low-temperature water bath stage and the hydrothermal stage, PVP is added in batches to protect the low-dimensional crystal nucleus and prevent the growth of nanoparticles. By calcination, Mn with high dispersion and high specific surface area is obtained. 3 N 2 Nanoparticle catalyst. The Mn prepared by this method 3 N 2 The catalyst has high efficiency, large catalytic activity specific surface area, strong anchoring effect of nitrogen atoms on manganese ions, and metal ions are not easy to dissolve. 3 N 2 The synthesis does not rely on large equipment and is simple and easy.

[0084] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an advanced oxidation catalyst based on Mn3N2, characterized in that: include: S1: Mix N-N-dimethylformamide and ethanol to prepare solution A; S2: adding manganese chloride and polyvinyl pyrrolidone from which crystal water has been removed by heating to solution A, and stirring until completely dissolved to obtain solution B; S3: adding 5,10,15,20-tetracarboxyphenylporphyrin to solution B, stirring until completely dissolved, obtaining solution C, and reacting solution C in a water bath to obtain liquid D; S4: adding polyvinyl pyrrolidone to solution D, stirring to dissolve, and then performing a hydrothermal reaction. After the reaction is completed, centrifugation and drying are performed to obtain a powder sample E; S5: Heat treat the powder sample E under an inert gas atmosphere to obtain Mn3N2.

2. The method for preparing a Mn3N2-based advanced oxidation catalyst according to claim 1, characterized in that: In the S1, N-N-dimethylformamide and ethanol are mixed in a volume ratio of 1:3 to 1:

1.

3. The method for preparing a Mn3N2-based advanced oxidation catalyst according to claim 1, characterized in that: In the S2, 0.5 g to 1.0 g of manganese chloride and 10 mg to 20 mg of polyvinyl pyrrolidone are dissolved in 40 mL to 70 mL of solvent A and stirred until completely dissolved, to prepare solution B.

4. The method for preparing a Mn3N2-based advanced oxidation catalyst according to claim 1, characterized in that: In the above S3, 12 mg to 24 mg of 5,10,15,20-tetracarboxyphenylporphyrin is dissolved in solution B and stirred until completely dissolved to obtain solution C.

5. The method for preparing a Mn3N2-based advanced oxidation catalyst according to claim 1, characterized in that: In the above S3, liquid D is obtained by reacting in a water bath at 50°C to 80°C for 20 to 30 minutes.

6. The method for preparing a Mn3N2-based advanced oxidation catalyst according to claim 1, characterized in that: In the above S4, 10 mg to 20 mg of polyvinyl pyrrolidone is added to the solution D and stirred to dissolve, followed by a hydrothermal reaction at 80° C. for 18 to 24 hours, and then the powder sample E is collected by centrifugation and drying.

7. The method for preparing a Mn3N2-based advanced oxidation catalyst according to claim 6, characterized in that: After adding 10 mg to 20 mg of polyvinyl pyrrolidone to the solution D and stirring to dissolve, the solution is transferred to a polytetrafluoroethylene liner and sealed in a stainless steel hydrothermal autoclave and locked to perform a hydrothermal reaction at 80° C. to 100° C. for 18 to 24 hours.

8. The method for preparing a Mn3N2-based advanced oxidation catalyst according to claim 1, characterized in that: In the S5, the powder sample E is placed in a porcelain boat and placed in a tube furnace for heat treatment for 2 to 3 hours under an inert gas atmosphere to obtain Mn3N2.

9. The method for preparing a Mn3N2-based advanced oxidation catalyst according to claim 1, characterized in that: In the above S5, heat treatment is performed in an argon or nitrogen atmosphere at a temperature of 500°C to 650°C.

10. An advanced oxidation catalyst based on Mn3N2, characterized in that The method is prepared by any one of claims 1 to 9.

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