Preparation method of carbon-silicon oxide composite carrier, composite carrier prepared by the method, heterogeneous catalytic oxidation catalyst and application

Abstract

The present application relates to a preparation method of carbon-silicon oxide composite carrier and the composite carrier, heterogeneous catalytic oxidation catalyst and application thereof.The preparation method of carbon-silicon oxide composite carrier is to mix a silicon source and a carbon source to form a precursor solution, and then to synthesize the carbon-silicon oxide composite carrier in situ by carbonization.The method is convenient, efficient and suitable for industrial application.The composite carrier obtained has high mechanical strength, large specific surface area, high stability, stable performance, suitable specific gravity and the like.Further, the preparation method can adjust the pore and element distribution by parameter adjustment, thereby improving the treatment effect of the catalyst on complex water quality.

Description

Technical Field

[0001] The present invention relates to the fields of catalytic materials and environmental protection, and in particular to a method for preparing a carbon-silicon oxide composite carrier, the prepared composite carrier, a heterogeneous catalytic oxidation catalyst and applications thereof. Background Art

[0002] Water is the source of life. With the rapid advancement of urbanization and industrialization, water shortages and pollution have become serious challenges worldwide. To alleviate these challenges, advanced oxidation processes (AOPs) are gaining widespread attention worldwide. AOPs utilize catalysts, light, electricity, and other methods to generate reactive oxygen species, leveraging their potent oxidizing properties to degrade organic pollutants in water. They are highly efficient, convenient, and offer minimal secondary pollution.

[0003] Based on the reaction mechanism and catalytic degradation theory of homogeneous catalytic oxidation systems, heterogeneous catalytic oxidation technology has gradually developed to improve material separation and recycling. Heterogeneous catalytic oxidation primarily utilizes the decomposition of oxide precursors such as ozone, hydrogen peroxide, and persulfate on the surface of a solid catalyst to produce reactive oxygen species such as hydroxyl radicals, sulfate radicals, and singlet oxygen, which are used for the deep removal of recalcitrant organic matter in water or air. Compared with homogeneous catalytic oxidation technology, heterogeneous catalytic oxidation offers greater potential for application due to the ease of solid catalyst recovery after the reaction and relatively lower processing costs. Designing efficient and stable catalysts is a key factor in the development of heterogeneous catalytic oxidation. Traditional heterogeneous catalytic oxidation catalysts include carbon-based catalysts and metal-based catalysts. The active groups of carbon-based catalysts are easily oxidized and easily destroyed in complex three-phase systems. Metal-based catalysts, on the other hand, are mostly solid structures, so the internal catalytic sites are affected by mass transfer and thus lack catalytic activity. The development of heterogeneous catalytic oxidation catalysts that balance high catalytic activity, high mass transfer efficiency, and high mechanical strength has been a hot topic in research and development. Summary of the Invention

[0004] Problems to be solved by the invention

[0005] The inventor’s previous research disclosed a granular high-efficiency dual-support catalyst with better stability and catalytic performance (such as patent document 1: CN108479784A), which has both the good surface activity of carbon-based materials and the excellent mechanical properties of alumina materials, which is conducive to the catalytic performance of ozone catalytic oxidation active metals. However, the inventor further discovered that Si-OH has a richer hydroxyl group and may be more conducive to the adsorption of ozone and improve catalytic performance. However, in the preparation process of the granular dual-support catalyst based on carbon-based materials and silicon oxide, it was found that if the previous dual-support preparation method was adopted, the prepared granular dual-support catalyst had the practical problem of being unable to be applied in systems such as fluidized beds due to its excessive specific gravity. Therefore, how to design and develop a composite support that is easy to operate and a method for preparing a heterogeneous catalytic oxidation catalyst based thereon, the catalyst based on the carbon-silicon oxide composite support obtained by this method is suitable for application in industrial systems such as fluidized beds and has both high catalytic activity and mechanical strength.

[0006] To address the aforementioned technical problems, the present invention aims to provide a method for preparing a carbon-silicon oxide composite support. This method is convenient and efficient, allows for easy control of pore size and element distribution, and has strong applicability. Furthermore, the present invention provides a composite support obtained by this preparation method, which exhibits high mechanical strength, a large specific surface area, strong stability and performance, and a suitable specific gravity suitable for industrial applications.

[0007] Another object of the present invention is to provide a heterogeneous catalytic oxidation catalyst and a method for preparing the same. The catalyst exhibits high catalytic activity, high mass transfer efficiency, and low cost, and the preparation method is convenient, efficient, and highly applicable. Furthermore, the present invention provides an application of the heterogeneous catalytic oxidation catalyst in the field of ozone catalytic oxidation.

[0008] Solutions for solving problems

[0009] Through long-term research, the inventors found that the above technical problems can be solved by implementing the following technical solutions:

[0010] [1] A method for preparing a carbon-silicon oxide composite carrier, wherein the carbon-silicon oxide composite carrier is prepared by mixing a silicon source and a carbon source to form a precursor solution, and then carbonizing the precursor solution to synthesize the carbon-silicon oxide composite carrier in situ.

[0011] [2] The preparation method according to [1], wherein the carbon source is selected from a polymer, a polymer precursor or a sugar; the silicon source is selected from an organosilicon source; and further, the carbon source contains heteroatoms.

[0012] [3] The preparation method according to [1] or [2], wherein the carbon source is selected from a polymer precursor, and the silicon source and the polymer precursor are hydrolyzed and polymerized under alkaline conditions to form a precursor solution; further, the polymer precursor includes a polyphenol substance.

[0013] [4] The preparation method according to [1] or [2], wherein the preparation method further comprises spinning and pre-oxidation steps before the carbonization.

[0014] [5] The preparation method according to any one of the technical solutions [1] to [4], wherein the carbonization is carried out by heating the material at a rate of 0.5 to 10°C / min and maintaining the temperature at 500 to 1100°C for 0.5 to 6 hours.

[0015] [6] A carbon-silicon oxide composite carrier prepared by the preparation method described in any one of the technical solutions [1] to [5].

[0016] [7] The carbon-silicon oxide composite carrier according to [6], wherein the carbon-silicon oxide composite carrier is a granular or powdery core-shell type composite carrier, comprising silicon dioxide as a core and a carbon layer on its surface as a shell layer.

[0017] [8] The carbon-silicon oxide composite support according to [6], wherein the carbon-silicon oxide composite support is a fibrous hybrid carbon fiber-silica fiber composite support.

[0018] [9] A heterogeneous catalytic oxidation catalyst, wherein the catalyst comprises a carbon-silicon oxide composite carrier as described in any one of the technical solutions [6] to [8].

[0019]

[10] The heterogeneous catalytic oxidation catalyst according to [9], wherein the catalyst further comprises an active site, wherein the active site comprises a transition metal, a heteroatom or a composite structure of the two; further, the transition metal is selected from one or more of manganese, iron, cobalt, nickel, copper, zinc, and cerium, and the heteroatom is selected from one or more of oxygen, sulfur, nitrogen, phosphorus, and boron; further, the transition metal is selected from manganese.

[0020]

[11] A method for preparing a heterogeneous catalytic oxidation catalyst, wherein the preparation method comprises mixing a silicon source and a carbon source to form a precursor solution, adding a transition metal salt solution to the precursor solution or centrifugally drying the precursor solution and then adding it to a transition metal salt solution, and then carbonizing to synthesize a transition metal-doped carbon-silicon oxide composite carrier catalyst in situ, wherein the transition metal is selected from manganese.

[0021]

[12] A heterogeneous catalytic oxidation catalyst prepared according to the preparation method described in

[11] .

[0022]

[13] Application of the heterogeneous catalytic oxidation catalyst as described in any of the technical solutions [9],

[10] or

[12] in ozone catalytic oxidation.

[0023] Effects of the Invention

[0024] The preparation method of the carbon-silicon oxide composite carrier provided by the present invention utilizes a carbon source and a silicon source to in situ synthesize the carbon-silicon oxide composite carrier. The operation is convenient and efficient, and the applicability is strong. The obtained composite carrier has high mechanical strength, large specific surface area, strong stability and stable performance, and a suitable specific gravity suitable for industrial application. In addition, the preparation method of the present invention can adjust the pores and element distribution through parameter adjustment, thereby improving the treatment effect of the catalyst on complex water quality. In some specific embodiments of the present invention, the composite carrier can be granular or powdery, or fibrous. Furthermore, the fibrous composite carrier can more fully expose the catalytic sites, and its hierarchical porous structure is more conducive to efficient reaction and mass transfer. Its light and soft properties allow it to be processed into any desired macroscopic shape, which is beneficial to reactor design.

[0025] The heterogeneous catalytic oxidation catalyst prepared based on the carbon-silicon oxide composite support of the present invention combines the advantages of high catalytic activity, high mass transfer, and low cost, and can be used in the heterogeneous catalytic oxidation treatment of wastewater, exhaust gas, and other wastewater. In some specific embodiments of the present invention, the manganese-doped carbon-silicon oxide composite support catalyst has unexpectedly excellent ozone catalytic oxidation performance, can effectively degrade and remove refractory organic matter in water at room temperature and pressure, with high removal efficiency, and is particularly suitable for the advanced treatment of refractory wastewater.

[0026] It should be noted that the above description does not disclose all embodiments of the present invention and all advantages of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : Micromorphology and element distribution of Mn-CSF prepared in Example 1

[0028] Figure 2 : Micromorphology and element distribution of Mn-CSF-0.2 obtained in Example 1

[0029] Figure 3 : Example 2 Schematic diagram of the preparation process and the micromorphology and element distribution of the prepared MnNx-CSF

[0030] Figure 4 : Microscopic morphology of Mn-CSM obtained in Example 4

[0031] Figure 5 : Mn-CSM micromorphology and element distribution diagram obtained in Example 4

[0032] Figure 6 :Nitrogen adsorption curves of MnNx-CSF and N-CSF

[0033] Figure 7 :Nitrogen adsorption curve of Mn-CSM

[0034] Figure 8 :Comparison of oxalic acid removal effects of Mn-CSF, ozone alone, and traditional Mn-SiO2 catalysts

[0035] Figure 9 :Comparison of oxalic acid removal effects of Mn-CSF and other metal-loaded catalysts

[0036] Figure 10 :Comparison of the degradation effects of Mn-CSM, CSM, Mn-CM, CM and ozone on oxalic acid

[0037] Figure 11 :Comparison of the degradation effects of Mn-CSM, Mn-CSM-800, Mn-CSM-600 and ozone on oxalic acid

[0038] Figure 12 :Comparison of the removal effect of p-hydroxybenzoic acid by MnNx-CSF, ozone alone, and traditional Mn-SiO2 catalysts

[0039] Figure 13 Comparison of the degradation effects of Mn-CSF, ozone alone, and traditional Mn-SiO2 catalyst on secondary biochemical effluent from coal gasification

[0040] Figure 14 Comparison of the degradation effects of Mn-CSF and other metal-loaded catalysts on coal gasification secondary biochemical effluent

[0041] Figure 15 :Research results of cycle tests on treatment of secondary effluent from coal gasification using Mn-CSF and conventional Mn-SiO2 catalysts

[0042] Figure 16 :Results of cyclic test on treatment of oxalic acid by Mn-CSM

[0043] Figure 17 Schematic diagram of the electrostatic potential of MnNx-CSF and ozone and the adsorption energy of the reaction process of MnNx-CSF and ozone DETAILED DESCRIPTION

[0044] The following describes embodiments of the present invention, but the present invention is not limited thereto. The present invention is not limited to the various configurations described below; various modifications may be made within the scope of the invention. Embodiments and examples obtained by appropriately combining the technical means disclosed in different embodiments and examples are also included within the technical scope of the present invention. In addition, all documents listed in this specification are cited as references in this specification.

[0045] Unless defined otherwise, technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0046] In the context of describing this specification (especially in the context of the following claims), the terms "a," "an," and "the" and similar language are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.

[0047] In this specification, a numerical range expressed using "numerical value A to numerical value B" or "numerical value A - numerical value B" means a range including the endpoints numerical values ​​A and B.

[0048] In this specification, the use of "above" or "below" includes the number.

[0049] In this specification, the use of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process. In this specification, "optional" or "optionally" means that the event or situation described below may or may not occur, and the description includes both cases where the event occurs and cases where the event does not occur.

[0050] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "some specific / preferred technical solutions," "other specific / preferred technical solutions," etc., mean that the specific elements (e.g., features, structures, properties, and / or characteristics) described in connection with the embodiment are included in at least one embodiment described herein and may or may not be present in other embodiments. Furthermore, it should be understood that the elements may be combined in various embodiments in any appropriate manner.

[0051] The term "comprises" and any variations thereof in the description and claims of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0052] In this specification, the term "particles" and the term "powder" are distinguished by particle size. Powder is smaller than particle size. Particles with a particle size of ≤100μm are usually called "powders", and particles with a size of >100μm are called "particles".

[0053] In the present invention, the term "silanol" is used to include compounds having one or more Si-OH moieties and those compounds having Si-OAlk (wherein Alk is an alkyl) moieties (such as Si-O-methyl, Si-O-ethyl, etc.), which are readily hydrolyzed to Si-OH moieties in aqueous fluids having a pH suitable for such hydrolysis.

[0054] (Method for preparing composite carrier)

[0055] The present invention first provides a method for preparing a carbon-silicon oxide composite support. The preparation method includes mixing a silicon source and a carbon source to form a precursor solution, followed by in-situ carbonization to synthesize the carbon-silicon oxide composite support. This method obtains silicon oxide (i.e., silicon dioxide) and a carbon-based material through an in-situ reaction. The prepared composite support combines the robustness of the metal-like oxide silicon dioxide with the high reactivity of the carbon material, has high chemical stability, and can maintain stable performance even in highly oxidizing environments, making it particularly suitable for use in heterogeneous catalytic oxidation reaction systems in the environmental field. Compared to single silica particle catalysts or carbon-based catalysts, the composite support of the present invention has superior mechanical strength and catalytic performance. Compared to other supports such as alumina, the composite support of the present invention has Si-OH bonds, which results in more abundant hydroxyl groups on its surface, which can adsorb more ozone and promote the occurrence of catalytic reactions. Therefore, the composite support of the present invention has superior ozone catalytic oxidation performance. In addition, the in-situ preparation method makes it easier to control the particle size of the composite support, and the obtained composite support has an appropriate specific gravity, making it particularly suitable for process applications such as fluidized beds. In some specific embodiments of the present invention, the preparation method of the present invention can be combined with electrospinning technology to obtain a fibrous mixed carbon fiber-silica fiber composite carrier. The fibrous structure can more fully expose the catalytic sites and is lighter, with a filling density of 2g / 20mL. In some preferred embodiments of the present invention, the filling density of the catalytic material based on the fibrous composite carrier is reduced by more than 80% compared with the traditional carbon-alumina type granular catalyst, but has a higher degradation effect. Therefore, the composite carrier of the present invention has very good cost-effectiveness.

[0056] The silicon source used in the preparation method of the present invention refers to a precursor for obtaining silicon dioxide after the reaction. The carbon source refers to a precursor that can provide a carbon material or produce graphitization. The types of silicon source and carbon source are not particularly limited. In some specific embodiments of the present invention, the silicon source includes one or more inorganic silicon sources such as sodium silicate and potassium silicate and organic silicon sources such as ethyl orthosilicate, methyl orthosilicate, and propyl orthosilicate. The silicon source may also include heteroatoms such as sulfur and nitrogen, such as 3-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, hexamethyldisilazane, or halogens such as silicon tetrachloride and dichlorodimethylsilane. Preferably, the silicon source is selected from an organic silicon source, and more preferably, the silicon source is a silanol compound, such as one or more trialkoxysilanes (such as trimethoxysilane, triethoxysilane, ethyltriethoxysilane, or mixtures thereof) and tetraalkoxysilanes (such as tetramethoxysilane, tetraethoxysilane, or mixtures thereof). In some specific embodiments of the present invention, the carbon source includes one or more of a polymer, a polymer precursor or a carbohydrate, wherein the polymer precursor in the present invention refers to a substance that can self-polymerize to form a polymer. Preferably, the polymer is selected from a high molecular polymer with good spinnability, such as one or more of polyacrylonitrile (PAN), polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyester, polyamide, etc.; the polymer precursor mainly includes polyphenols, and the structure of the polyphenols contains two or more phenolic hydroxyl structures, such as dopamine, dopa, catechol, resorcinol, tannic acid, gallic acid, catechin, anthocyanin, pyrogallol and its salts, hydrates, etc. In addition to polyphenols, polymer precursors also include small molecule organic compounds such as formaldehyde; carbohydrates include one or more of monosaccharides such as glucose and fructose, oligosaccharides such as sucrose, and polysaccharides. In some preferred embodiments of the present invention, the carbon source includes one or more of polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl alcohol, glucose, dopamine, dopamine hydrochloride, dopa, dopa hydrochloride, catechol, resorcinol and formaldehyde. In some specific embodiments of the present invention, in order to improve the charge distribution on the catalyst surface and enhance the adsorption capacity for ozone and organic matter, heteroatoms can be introduced during the preparation of the composite carrier, and the heteroatoms are selected from one or more of oxygen, sulfur, nitrogen, phosphorus and boron. Preferably, the present invention introduces the aforementioned heteroatoms by changing the types of carbon source and silicon source. In some preferred embodiments of the present invention, in order to enhance the anchoring capacity for metal elements, the carbon source contains heteroatoms. Furthermore, the present invention utilizes the polycondensation reaction of nitrogen-containing, sulfur-containing, phosphorus-containing and other polymer precursors to obtain a carbon shell structure doped with different elements, thereby improving the electron cloud distribution of the outer layer of the carbon shell and enhancing the stability of the catalyst in an ozone catalytic environment.

[0057] The silicon source and carbon source of the present invention are mixed to form a precursor solution. The process of forming the precursor solution can be a chemical reaction method or a physical mixing method. In some specific embodiments of the present invention, when the carbon source is selected from a polymer precursor, the silicon source and the polymer precursor are hydrolyzed and polymerized under alkaline conditions to form a precursor solution, and the hydrolysis of the silanol compound under alkaline conditions is further achieved by adding an alkaline catalyst such as ammonia water to the system. In other specific embodiments of the present invention, when the carbon source is selected from a polymer or a sugar, the polymer or sugar can be dissolved in a solvent and stirred until the polymer or sugar is completely dissolved; then the silicon source is added to the solution, and stirred or heated and stirred until completely mixed to obtain a precursor solution. In some specific embodiments of the present invention, the mass ratio of the silicon source to the carbon source is greater than or equal to 1. In order to obtain better comprehensive performance, the silicon source accounts for 52% to 95% of the total mass of the silicon source and the carbon source, and further 53% to 80%.

[0058] Regarding the treatment of the precursor solution, the present invention includes at least two methods, depending on whether an electrospinning process is adopted: 1) directly centrifugally washing and drying the precursor solution to obtain a powdered precursor, such as oven drying, preferably at a drying temperature of 60 to 90°C, and then carbonizing the powdered precursor; 2) using the precursor solution for electrospinning and pre-oxidizing the obtained spinning membrane, and then carbonizing it. Pre-oxidation is to ensure the toughness of the spinning during subsequent use. Tension is applied to the spinning process. In some specific embodiments of the present invention, the electrospinning injection speed is 0.5-2 mL / h, the spinning time is 5-12 h, preferably 6-10 h, and then the complete spinning membrane is peeled off and the spinning membrane is fully hydrolyzed. Furthermore, the hydrolysis conditions are to stand in the air for 12-48 h, and then pre-oxidize in the air atmosphere of a muffle furnace. The pre-oxidation heating / cooling rate is 0.5-5 ° C / min, from room temperature to 260-280 ° C and kept warm for 0.5-2 h.

[0059] The preparation method of the composite carrier of the present invention also includes a carbonization treatment. The carbonization treatment is mainly a process of graphitizing the carbon source by anaerobic calcination. In some specific embodiments of the present invention, the sample to be carbonized, such as a powdered precursor or a pre-oxidized spinning membrane, is placed in a tubular furnace and calcined at high temperature and anaerobic under the protection of an inert gas such as argon. The carbonization heating rate is preferably 0.5 to 10°C / min, further 2 to 5°C / min. The inventors have found that the calcination temperature has an effect on the ozone oxidation performance of the catalyst. The calcination temperature is preferably 500 to 1100°C, further 600 to 1000°C, and more preferably 1000°C or 600°C. The calcination time is 0.5 to 6h, further 2 to 5h. Afterwards, the temperature can be naturally lowered or the cooling rate can be 0.5 to 10°C / min. After the carbonization treatment, the carbon-silicon oxide composite carrier of the present invention is obtained.

[0060] The preparation method of the composite carrier of the present invention is simple to operate, highly operable, and highly controllable. By adjusting the acidity and alkalinity of the precursor solution, such as controlling the input amount of the alkaline catalyst, the specific surface area and pore size distribution of the catalyst are adjusted. In some specific embodiments of the present invention, the input amount of the alkaline catalyst is preferably 0.0045-0.045 g / mL, and more preferably 0.005-0.05 g / mL; by changing the type of carbon source, the element distribution of the carbon shell or carbon fiber is adjusted, the anchoring of the metal element is enhanced, and the stability of the catalyst in the ozone catalytic environment is improved; in addition, during the electrospinning process, by adjusting the shaft speed, spinning injection rate, positive and negative voltage, the spacing between the receiving end and the needle, etc., the orientation, strength and thickness of the fiber can be improved, which is more conducive to adjusting the specific surface area and pore size structure of the catalyst. At the same time, by adjusting the temperature environment of pre-oxidation and carbonization, the graphitization of the catalyst and the thickness of the fiber can be improved, which is more conducive to the microscopic scale functional design of the catalyst.

[0061] (Compound Carrier)

[0062] According to the preparation method of the composite carrier of the present invention, at least two different forms of carbon-silicon oxide composite carriers can be obtained depending on whether the spinning step is performed: one is a granular or powdered core-shell composite carrier, including silicon dioxide as a core and a carbon skeleton layer on its surface as a shell layer; the other is a fibrous mixed carbon fiber-silicon dioxide fiber composite carrier. In some specific embodiments of the present invention, the microstructure of the composite carrier can be adjusted by adjusting the parameters of the preparation method. In order to obtain better catalytic activity, for the preferred powdered core-shell composite carrier of the present invention, its average particle size is 150 to 300 nm, preferably 200 to 250 nm; its specific surface area is 10 to 500 m 2 / g, preferably 150-450m 2 / g; the total pore volume range is 0.06 to 2 mL / g, more preferably 0.3 to 1.8 mL / g; the average pore size is 2 to 16 nm. For the fibrous hybrid carbon fiber-silica fiber composite carrier, the average fiber diameter is 0.2 to 20 μm, preferably 0.5 to 10 μm. If the average diameter is too small, the mechanical strength is insufficient or it is difficult to spin. If the average diameter is too large, it will affect the specific surface area of ​​the composite carrier, which is not conducive to the improvement of catalytic and mass transfer effects; the specific surface area is about 20 to 300 m 2 / g, more preferably 50 to 200 m 2 / g, the total pore volume range is 0.01-0.35mL / g, more preferably 0.04-0.30mL / g; the average pore diameter is 2.0-7.0nm, more preferably 3.0-6.0nm. The average particle size or average diameter of the present invention is obtained by statistically analyzing the particle size or fiber diameter in the SEM image using imageJ software.

[0063] (Heterogeneous Oxidation Catalyst)

[0064] The present invention also provides a heterogeneous catalytic oxidation catalyst comprising the composite support of the present invention. The catalyst of the present invention has good structural stability and mechanical strength, lower material cost and higher catalytic degradation efficiency.

[0065] The catalytic active sites of the catalyst of the present invention can be transition metals, heteroatoms or a composite structure of the two. Furthermore, the transition metal is selected from one or more of manganese, iron, cobalt, nickel, copper, zinc and cerium, and the heteroatoms are selected from one or more of oxygen, sulfur, nitrogen, phosphorus and boron. In some specific embodiments of the present invention, the catalytic performance of the catalyst, especially the catalytic activity for ozone catalytic oxidation reaction, can be further improved by introducing a transition metal salt solution such as one or more of manganese salts, iron salts, cobalt salts, nickel salts, copper salts, zinc salts, cerium salts or hydrates thereof during the preparation process of the composite carrier. The types of the above-mentioned transition metal salts are not particularly limited, for example, they can be selected from one or more of nitrates, halogen salts, acetates, acetylacetonates, sulfates or hydrates thereof. In other specific embodiments of the present invention, the composite carrier of the present invention can also be doped with heteroatoms, for example, heteroatom doping can be achieved by adopting a carbon source containing heteroatoms. In some preferred embodiments of the present invention, the inventors have found that manganese-doped carbon-silicon oxide composite supports have unexpectedly high ozone catalytic oxidation performance, and the manganese doping amount (manganese content accounts for the total mass of the catalyst) is preferably 1% to 5%, further 1.5% to 4%. Furthermore, in addition to manganese doping, the composite support of the present invention is preferably doped with heteroatoms, and the heteroatom content is preferably 5% to 15% of the total mass of the catalyst, and further preferably 8 to 12%.

[0066] (Preparation method of heterogeneous catalytic oxidation catalyst)

[0067] The present invention also provides a method for preparing a heterogeneous catalytic oxidation catalyst, comprising mixing a silicon source and a carbon source to form a precursor solution, adding a transition metal salt solution to the precursor solution, or centrifugally drying the precursor solution and then adding it to a transition metal salt solution, centrifugally drying, and then carbonizing to synthesize the catalyst in situ. Further preferably, the transition metal salt is a manganese salt, such as one or more of manganese sulfate, manganese sulfate hydrate, manganese acetylacetonate, manganese acetate, and manganese acetate hydrate.

[0068] In some specific embodiments of the present invention, the steps are as follows:

[0069] Step 1: Weigh a certain amount of polymer precursor to prepare a 0.5-100 g / L solution and stir evenly;

[0070] Step 2: Add the silanol compound and ammonia water to the above solution and stir to obtain a precursor solution;

[0071] Step 3: Centrifuge, wash, and dry the precursor solution to obtain a powdered precursor. Weigh the powdered precursor, dissolve it in a manganese salt solution, and then centrifuge, wash, and dry it. Alternatively, directly add the manganese salt solution to the precursor solution, stir, and then centrifuge, wash, and dry it.

[0072] Step 4: Carbonize the powder product from step 3.

[0073] In some other specific embodiments of the present invention, the steps are specifically included:

[0074] Step 1: Select a certain amount of polymer and dissolve it in the solvent, stirring at room temperature until it is completely dissolved;

[0075] Step 2: Add the silicon source to the solution, heat and stir until the silicon source is completely mixed; further, the heating temperature is 80-110°C;

[0076] Step 3: Add manganese salt to the solution and stir to dissolve;

[0077] Step 4: After the solution has cooled to room temperature, transfer the precursor into a syringe.

[0078] Step 5: Electrospinning, after which the complete spinning membrane is peeled off; further spinning is performed at a push injection rate of 0.5 to 2 mL / h;

[0079] Step 6: After the spinning membrane is fully hydrolyzed, it is pre-oxidized in an air atmosphere of a muffle furnace and taken out after cooling to room temperature;

[0080] Step 7: Carbonize the pre-oxidized spinning membrane.

[0081] The preparation method of the heterogeneous catalytic oxidation catalyst of the present invention has the characteristics of strong operability and wide application range, and can be extended to other solid-phase catalyst material preparation fields, such as heterogeneous Fenton, persulfate catalysis and other fields.

[0082] (Application of heterogeneous catalytic oxidation catalysts)

[0083] The catalyst of the present invention is suitable for use in heterogeneous catalytic oxidation reaction systems and can be used in heterogeneous catalytic oxidation treatments such as water and gas. The catalyst of the present invention is particularly suitable for use in the field of ozone catalytic oxidation to achieve deep treatment of water or gas containing refractory organic matter. Further, water includes domestic or industrial organic wastewater or drinking water. Furthermore, organic wastewater includes wastewater from coal chemical industry, petrochemical industry, pharmaceutical industry, printing and dyeing, papermaking and other processes. Refractory organic wastewater generally refers to such wastewater with low biodegradability, and the BOD5 / COD value is generally below 0.3 or even lower, making it difficult to biodegrade. In some specific embodiments of the present invention, the catalyst of the present invention can achieve deep treatment of refractory organic wastewater such as coal gasification wastewater, and the degradation pathway is mainly the hydroxyl radical pathway. In addition, the catalyst of the present invention can also maintain a stable degradation effect under repeated tests, and has good mechanical properties and a long service life.

[0084] Example

[0085] The present invention will be further described below through specific embodiments:

[0086] (Characterization Instruments and Methods)

[0087] Scanning electron microscopy (SEM, Gemini SEM 500) and energy dispersive spectroscopy (EDS) were used to characterize the micromorphology, appearance, and elemental distribution of the catalysts prepared in the examples. ImageJ software was used to calculate the diameter of the catalyst wires, and the diameter of the 50-100 segments was statistically calculated. Sample preparation conditions: The prepared catalyst was gently crushed to spread it out, and a 0.5 cm 2 For catalysts with large areas, thinner ones are better.

[0088] The specific surface area and pore size distribution analyzer (QuadraSorb SI) was used to characterize the specific surface area, pore size and other parameters of the catalyst. Sample preparation conditions: The prepared catalyst was crushed to make it loose, and a small portion was cut and then cut into chips.

[0089] Example 1:

[0090] The preparation method of the manganese-doped carbon-silicon oxide composite support catalyst based on silicon alkoxide, formaldehyde and resorcinol is as follows:

[0091] Step 1: Prepare solution A: Dissolve 1 g of cetyltrimethylammonium bromide (CTAB) in 69 mL of methanol and stir at room temperature for 15 minutes until completely dissolved.

[0092] Step 2: Prepare Solution B: Stir 0.35g of resorcinol, 1.16mL of aqueous ammonia, and 63.2mL of deionized water until the mixture is clear. To adjust the catalyst surface area and pore size distribution, add different ratios of aqueous ammonia: 0.232mL, 0.464mL, 1.16mL, and 2.332mL, respectively.

[0093] Step 3: After mixing solution A and solution B, add 117.9 μL of tetraethyl orthosilicate (TEOS) and 0.49 mL of formaldehyde, heat at 40°C for 15 minutes, and then stir at 70°C for 75 minutes.

[0094] Step 4: After washing by centrifugation three times, the precursor powder was obtained and dried in an oven at 80°C.

[0095] Step 5: The dried powder was dissolved in a solution containing 20 wt% MnSO4·H2O, stirred for 2 hours, washed three times by centrifugation and dried.

[0096] Step 6: The resulting powder was placed in a tubular furnace under argon protection, heated to 800°C at a rate of 5°C / min, held for 2 hours, and then cooled naturally to obtain the prepared manganese-doped carbon-silicon oxide composite supported catalyst. The resulting catalysts were labeled Mn-CSF-0.2, Mn-CSF-0.4, Mn-CSF, and Mn-CSF-2 (with ammonia dosages of 0.232 mL, 0.464 mL, 1.16 mL, and 2.332 mL, respectively).

[0097] The obtained catalyst micromorphology and element distribution are shown in Figure 1 (Mn-CSF) and Figure 2 (Mn-CSF-0.2).

[0098] from Figure 1 The prepared catalysts are small spheres of approximately 250 nm in diameter, with some nanometer-sized metal oxide particles visible on their surfaces. TEM observations show that the prepared nanospheres are regular spheres with SiO2 inside and a carbon layer covering the outside.

[0099] Example 2:

[0100] The preparation method of the manganese-doped carbon-silicon oxide composite support catalyst based on silicon alkoxide and dopamine hydrochloride is as follows:

[0101] Step 1: Prepare solution A: Stir 24 mL of methanol, 80 mL of deionized water, and 1 mL of ammonia for 30 minutes until clear, then add 1 mL of tetraethyl orthosilicate (TEOS).

[0102] Step 2: Prepare Solution B: Prepare 8 mL of 50 g / L dopamine hydrochloride solution.

[0103] Step 3: After mixing solution A and solution B, add gradient concentrations of manganese acetate (0 mg, 20 mg, 40 mg, 60 mg) and stir for 36 hours.

[0104] Step 4: After centrifugation and washing three times, a gray-green powder was obtained and dried at 80°C.

[0105] Step 5: The obtained powder was placed in a tube furnace with argon protective gas, heated to 900°C at a rate of 5°C / min, kept at this temperature for 2 hours, and then cooled naturally to obtain the prepared manganese-doped carbon-silicon oxide composite support catalyst. The obtained catalysts were labeled as N-CSF, MnNx-CSF, MnNx-CSF-2, and MnNx-CSF-3 (the dosage of manganese acetate was 0 mg, 20 mg, 40 mg, and 60 mg, respectively).

[0106] The schematic diagram of the catalyst preparation process and the obtained catalyst micromorphology and element distribution are shown in Figure 3 (MnNx-CSF).

[0107] Example 3:

[0108] Compared with Example 1, the fifth step is omitted, that is, no manganese salt is added, and other conditions remain unchanged. The prepared carbon-silicon oxide composite support is marked as CSF.

[0109] Example 4:

[0110] The difference compared with Example 1 is that the transition metal salt added in step 5 is different. Other conditions remain unchanged, and the 20wt% manganese sulfate is replaced with ferric chloride or a mixture of ferric chloride and manganese sulfate with the same mass fraction, wherein the molar ratios of ferric chloride added are 100%, 75%, 50%, and 25%, respectively, to prepare iron-doped or iron-manganese-doped carbon-silicon oxide composite supported catalysts, which are labeled as Fe-CSF, Mn1Fe3-CSF, Mn1Fe1-CSF, and Mn3Fe1-CSF, respectively.

[0111] Example 5:

[0112] Step 1: Weigh 2 g of polyacrylonitrile (PAN) as a substrate, dissolve it in N,N-dimethylformamide (DMF), and stir at room temperature for 12 h until the polymer is completely dissolved.

[0113] Step 2: Add 2.5 mL (2.35 g) of tetraethoxysilane to the solution and heat with stirring at 100°C for 0.5 h.

[0114] Step 3: Add acetylacetonate manganese salt to the solution and stir to dissolve to obtain a precursor solution.

[0115] Step 4: After the solution has cooled to room temperature, transfer the precursor solution into a syringe.

[0116] Step 5: Electrospinning was performed at a positive and negative voltage of 15 kV, a distance of 12 cm between the needle and the roller / plate receiver, and a bolus injection rate of 1.5 ml / h for 10 hours. The intact spun membrane was then peeled off.

[0117] Step 6: Pre-oxidation: After the spun membrane is fully hydrolyzed, pre-oxidation is carried out in an air atmosphere in a muffle furnace at a heating rate of 0.5°C / min from room temperature to 280°C and kept at this temperature for 2 hours.

[0118] Step 7: Carbonization. The pre-oxidized spun membrane was carbonized in an argon atmosphere in a tubular furnace. The temperature was increased from room temperature to 1000°C at a rate of 3°C / min and held for 2 hours, yielding a fibrous manganese-doped hybrid carbon fiber-silica fiber composite catalyst support, labeled Mn-CSM.

[0119] The obtained catalyst microstructure and element distribution are shown in Figure 4 and Figure 5 (Mn-CSM). The fiber surface of Mn-CSM has some irregular protrusions and spherical metal oxides. The diameter of the catalyst was statistically analyzed using imageJ software, and the diameter of the 50-100 segment was statistically calculated, with an average diameter of 600nm. The pore structure of the catalyst obtained by the BET method was characterized and analyzed: the specific surface area of ​​Mn-CSM reached 225.2m 2 / g, and the average pore diameter is 3.40nm.

[0120] Example 6:

[0121] The difference compared with Example 5 is that there is no step 3, and the solution in step 2 is directly used as the precursor solution. Other conditions remain unchanged to prepare a manganese-free hybrid carbon fiber-inert oxide fiber composite material, which is marked as CSM.

[0122] Example 7:

[0123] The difference compared with Example 5 is that the carbonization temperature in step 7 is changed from 1000° C. to 800° C., while other conditions remain unchanged, to obtain a manganese-doped hybrid carbon fiber-inert oxide fiber composite material, which is labeled as Mn-CSM-800.

[0124] Example 8:

[0125] The difference compared with Example 5 is that the carbonization temperature in step 7 is changed from 1000° C. to 600° C., while other conditions remain unchanged, to obtain a manganese-doped hybrid carbon fiber-inert oxide fiber composite material, which is labeled as Mn-CSM-600.

[0126] Comparative Example 1:

[0127] Compared with Example 1, the difference is that no resorcinol is added in step 2 and no formaldehyde is added in step 3. Other conditions remain unchanged, and a manganese-doped single-carrier catalyst is prepared, which is marked as Mn-SiO2.

[0128] Comparative Example 2:

[0129] The difference compared with Example 5 is that the second step is omitted, and other conditions remain unchanged, thereby obtaining a manganese-doped composite material without silicon alkoxide, which is marked as Mn-CM.

[0130] Comparative Example 3:

[0131] The difference compared with Example 5 is that the second and third steps are omitted, and other conditions remain unchanged, thereby obtaining a composite material consisting only of carbon fibers, which is marked as CM.

[0132] Comparative Example 4:

[0133] Compared with Example 1, the difference is that CTAB is not added in the first step, TEOS is not added in the third step, and other conditions remain unchanged to prepare a pure carbon-based catalyst.

[0134] Comparative Example 5

[0135] Compared with Comparative Example 1, the difference is that no resorcinol is added in step 2, no formaldehyde is added in step 3, and no manganese salt is added in step 5. Other conditions remain unchanged, and a silica catalyst is prepared, which is marked as SiO2.

[0136] Performance Testing

[0137] Chemical oxygen demand (COD): The water quality multi-parameter measuring instrument (Lianhua 5B-3BV8) was used for detection. The measurement method was potassium dichromate rapid digestion spectrophotometry.

[0138] Oxalic acid: Determined using a high-performance liquid chromatograph (Agilent 1200) with a Waters Atlantis T3 column. The mobile phase consisted of 20.0 mM sodium dihydrogen phosphate solution, adjusted to pH 2.5 with phosphoric acid, at a flow rate of 1.0 mL / min. The column oven temperature was 30°C, and the DAD detector was used at a wavelength of 210 nm.

[0139] Para-hydroxybenzoic acid: Analyze using an Agilent 1200 high-performance liquid chromatograph (HPLC) with a C18 reverse-phase column. Mobile phase A is pure methanol, and mobile phase B is a 1‰ phosphoric acid aqueous solution at a flow rate of 1.0 mL / min. The column oven temperature is 30°C, and the DAD detector is used at a wavelength of 280 nm.

[0140] TOC determination: A TOC meter (Shimadzu TOC-L) was used to determine the TOC concentration in the solution after high-temperature combustion and oxidation at 680°C.

[0141] The ozone catalytic reaction is operated in a sequencing batch or semi-sequential batch mode. For granular or powdered catalysts, a predetermined amount of catalyst is added to the wastewater in a column reactor. Simultaneously, an ozone generator (Longevity EXT120) uses pure oxygen as a source. The generated ozone is then introduced into the reaction solution through an aeration head and an ozone concentration detector (Tonglin 3S-J5000) to initiate the catalytic reaction. Periodic sampling and filtration are performed to measure the organic matter content in the wastewater. For fibrous catalysts, the catalyst is packed into a packed column reactor. Wastewater in a beaker is pumped into the bottom of the packed column reactor by a peristaltic pump. Simultaneously, an ozone generator (Longevity EXT120) uses pure oxygen as a source. The generated ozone is then introduced into the reactor through an ozone concentration detector (Tonglin 3S-J5000). The ozone is mixed with the influent and enters the reactor body, where it comes into contact with the catalyst, forming a three-phase reaction system. The gas and water phases separate at the top of the reactor due to density differences. The exhaust gas enters the ozone destructor, and the effluent is recycled back to the beaker.

[0142] Performance evaluation of the catalyst using oxalic acid simulated wastewater: For granular or powdered catalysts, the concentration of oxalic acid simulated wastewater is 100 mg / L, the pH is not adjusted, and the initial pH is about 3.3. The target wastewater volume for a single treatment is 250 mL, the ozone concentration is 10 mg / L, the gas flow rate is 0.2 L / min, and the reaction time is 60 min. For fibrous catalysts, the concentration of oxalic acid simulated wastewater is 100 mg / L, the pH is not adjusted, and the initial pH is about 3.3. The target wastewater volume for a single treatment is 250 mL, the ozone concentration is 10 mg / L, and the gas flow rate is 0.5 L / min. Ozone is aerated in the oxalic acid solution, and then the solution dissolved with ozone is passed into the reactor, and the effluent returns to the solution, and the cycle is continued for 60 min.

[0143] Catalyst performance was evaluated using simulated p-hydroxybenzoic acid wastewater: The p-hydroxybenzoic acid concentration was 20 mg / L, with no pH adjustment and an initial pH of approximately 4.3. The target wastewater volume for a single treatment was 250 mL, the ozone concentration was 10 mg / L, the gas flow rate was 0.5 L / min, and the reaction time was 30 minutes.

[0144] The calculation formula of removal rate or removal efficiency is: removal rate or removal efficiency = [(C-C0) / C0]*100%, where C is the concentration of the test substance and C0 is the original concentration of the test substance.

[0145] (Specific surface area)

[0146] The specific surface area and pore structure parameters of the products of the examples and comparative examples are measured, and the results are shown in Table 1 and Figure 6 and Figure 7 :

[0147] Table 1:

[0148]

[0149] (Degradation effect of oxalic acid)

[0150] The catalysts of Example 1, Example 3 and Comparative Example 1, Comparative Example 4 and Comparative Example 5 were added to the reactor at a content of 0.2 g / L, and ozone catalytic oxidation experiments were carried out on oxalic acid simulated wastewater. The results are shown in Figure 8 .from Figure 8 It can be seen that Mn-CSF has the best ozone catalytic activity. Within 60 minutes, 87.5% of oxalic acid was degraded by Mn-CSF ozone catalytic oxidation, but oxalic acid could hardly be oxidized and degraded by ozone and simple carbon-based catalysts or silica particle catalysts. At the same time, almost no oxalic acid was adsorbed within 60 minutes, which indicates that the reactive oxygen species (ROS) generated during ozone catalytic oxidation can degrade oxalic acid rather than being removed by adsorption. 24.2% of oxalic acid was degraded by CSF, indicating that the effect of CSF on the ozone catalytic system is improved compared to simple carbon-based catalysts or silica particle catalysts. The first-order kinetic constant of Mn-CSF for oxalic acid is -0.0394±0.0010min -1 , than Mn-SiO2(-0.0145±0.0014min -1 ) and CSF (-0.0044±0.0002min -1 ) were 172% and 795% higher respectively. The ratio of alkaline catalyst ammonia water affects the specific surface area and pore size distribution of the catalyst, and further affects the catalyst's removal effect on organic matter. The catalytic effect of Mn-CSF-0.2 is relatively lower than that of Mn-CSF-0.4 and Mn-CSF-2. The catalytic reaction also follows the first-order kinetic reaction constant. The kinetic constants of different catalysts are as follows: Mn-CSF (-0.0394 ± 0.0010min -1 )>Mn-CSF-2(-0.0373±0.0031min -1 )>Mn-CSF-0.4(-0.0360±0.1384min -1 )>Mn-CSF-0.2(-0.0228±0.0005min -1 ).

[0151] The catalysts of Example 1, Example 3, Comparative Example 1, Comparative Example 5, and other metal-loaded catalysts prepared in Example 4 were added to the reactor at a content of 0.2 g / L, and ozone catalytic oxidation experiments were carried out on oxalic acid simulated wastewater. The results are shown in Figure 9 .from Figure 9It can be seen that Mn-CSF has the best ozone catalytic activity. The present invention unexpectedly found that the oxalic acid removal effect of the catalyst doped with manganese alone within 60 minutes is about 1.5 times greater than that of the iron-doped catalyst or the manganese-iron doped catalyst.

[0152] 2g of Mn-CSM and CSM obtained in Examples 5 and 6 and 2g of Mn-CM and CM obtained in Comparative Examples 2 and 3 were respectively filled into the packed column reactor. The removal effect of 100mg / L oxalic acid in 1 hour by comparing Examples 5 and 6 with Comparative Examples 2 and 3 and ozone is shown in FIG. Figure 10 2g of Mn-CSM, Mn-CSM-800 and Mn-CSM-600 obtained in Examples 5, 7 and 8 were respectively filled into the packed column reactor. Comparison of the removal effects of Examples 5, 7, 8 and ozone on 100mg / L oxalic acid within 1 hour is shown in the following table. Figure 11 .Depend on Figure 10 It can be seen that the Mn-CSM obtained in Example 5 can remove 92% of oxalic acid within 60 minutes, while the Mn-CM obtained in Comparative Example 2 can only remove 83% of oxalic acid within 1 hour, indicating that the introduction of Si increases the ozone catalytic oxidation removal effect of the manganese-based catalyst. This may be because Si-OH has more abundant hydroxyl groups that can adsorb more ozone and promote the occurrence of catalytic reactions. Similar results also appeared in CSM and CM. CSM was able to remove 78% of oxalic acid within 60 minutes, which was 5 percentage points higher than the removal efficiency of CM (73%) within 1 hour. The ozone catalytic oxidation effects of the four are all better than the simple ozone oxidation effect. In addition, Figure 11 It can be seen that different carbonization temperatures will also affect the oxalic acid degradation effect to a certain extent.

[0153] (Degradation effect of parahydroxybenzoic acid)

[0154] The catalysts of Example 2 and Comparative Example 1 were added to the reactor at a concentration of 0.2 g / L and manganese chloride (8 mg / L ≈ the content of Mn in the catalyst). Ozone catalytic oxidation experiments were carried out on simulated p-hydroxybenzoic acid wastewater. The results are shown in Figure 12 .Depend on Figure 12 It can be seen that MnN x -CSF has the best catalytic activity, and the TOC removal rate can reach 85% within 30 minutes. Ozone has a certain oxidation effect on parahydroxybenzoic acid, but only 22% of TOC can be removed within 30 minutes.

[0155] (Degradation effect on coal gasification wastewater)

[0156] The target wastewater was a secondary biochemical effluent from coal gasification with a COD concentration of about 105 mg / L (the effluent from a sedimentation tank after biochemical treatment at a wastewater treatment plant of a coal-to-gas enterprise and coagulation and sedimentation). The catalysts of Example 1, Example 3, and Comparative Examples 1, 4, and 5 were added to the reactor at a concentration of 0.2 g / L, and ozone catalytic oxidation experiments were carried out on the secondary biochemical effluent from coal gasification. The results are shown in Figure 13 . The Mn-CSF ozone catalytic reaction degraded about 54.3% of COD within 60 minutes, and the COD was about 48 mg / L after 60 minutes, meeting the Class A standard for Chinese urban sewage treatment plants. Similarly, ozone, SiO2 ozone catalysis and CSF ozone catalysis can also degrade part of the COD, with degradation rates of 22%, 33% and 39% respectively. The catalysts prepared under different alkaline catalyst conditions also have good deep treatment effects on the secondary biochemical effluent of coal gasification. The effect of Mn-CSF-0.4 catalytic ozone oxidation also meets the Class A standard, removing 53% of COD (final COD 49 mg / L), while Mn-CSF-2 removed about 48% of COD.

[0157] The catalysts of Example 1, Example 3, Comparative Example 1, Comparative Example 5, and other metal-loaded catalysts prepared in Example 4 were added to the reactor at a content of 0.2 g / L, and ozone catalytic oxidation experiments were carried out on the secondary biochemical effluent of coal gasification. The results are shown in Figure 14 .from Figure 14 It can be seen that Mn-CSF also has the best ozone catalytic activity for the secondary biochemical effluent of coal gasification.

[0158] (Reusability evaluation)

[0159] The catalysts obtained in Example 1 and Comparative Example 1 were used to degrade the secondary biochemical effluent from coal gasification for 5 cycles. Figure 15 ,The results show that Mn-CSF is less affected by the impact of the complex system after repeated use, while the mechanical strength of Mn-SiO2 is affected in this system.

[0160] The packed column reactor was filled with 10.0 g of the Mn-CSM obtained in Example 5 to degrade oxalic acid for 6 cycles. The results are shown in the figure. Figure 16 , within 6 cycles, the removal rate of oxalic acid by Mn-CSM remained around 90%, which indicates that Mn-CSM can still maintain high catalytic activity and mechanical strength during a certain period of cyclic operation.

[0161] (Mechanism Analysis)

[0162] The pathways for the generation of reactive oxygen species during ozone catalytic oxidation by MnNx-CSF were calculated by DFT. Figure 17The electrostatic potential of the MnN4 system and O3 shows that the electrostatic potential of the central atom Mn is the highest, which is 205.83 kcal / mol, while the electrostatic potential of the side oxygen atoms of ozone is the lowest, which is -0.003 kcal / mol. This means that the side oxygen atoms of the ozone molecule are more easily adsorbed onto the Mn atom, forming a Mn-O3 connection through side adsorption.

[0163] The adsorption energy of MnNx-CSF combined with ozone was calculated, and the results showed that the adsorption energy was -2.74eV, indicating that the combination of the catalyst and ozone is an exothermic process and that the two can be well combined. The electron distribution shows that MnNx-CSF contains both α and β electrons. When it is combined with the ozone molecule, the electrons between Mn and ozone are transferred, and the two oxygen atoms on Mn-O3 are negatively charged, which is consistent with the inventor's speculation. The bond length on Mn-O3 is calculated, where the Mn-O bond length is The OO(1) bond length is Longer than the bond length of ozone molecules The OO(2) bond length is This indicates that a certain connection is formed between Mn and O, which affects the bond length of the ozone molecule. At the same time, the increase in electrons on O3 affects the bond angle of ozone OOO, reducing it to 109.4°, slightly smaller than O3's 116.8°.

[0164] Industrial Applicability

[0165] The technical solution disclosed in the present invention can be applied in industry.

Claims

1. A method for preparing a heterogeneous catalytic oxidation catalyst, characterized in that: The preparation method comprises mixing a silicon source and a carbon source to form a precursor solution, adding a transition metal salt solution to the precursor solution or centrifugally drying the precursor solution and then adding it to a transition metal salt solution, and then carbonizing the precursor solution to synthesize a transition metal-doped carbon-silicon oxide composite carrier catalyst in situ; wherein: the transition metal is manganese; the silicon source is an organic silicon source; the carbon source comprises one or more of a polymer, a polymer precursor or a sugar; and the polymer precursor comprises one or more of a polyphenolic substance and formaldehyde.

2. The preparation method according to claim 1, characterized in that The carbon source includes one or more of polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl alcohol, glucose, dopamine, dopamine hydrochloride, dopa, dopa hydrochloride, catechol, resorcinol and formaldehyde.

3. The preparation method according to claim 1 or 2, characterized in that The carbon source contains heteroatoms.

4. The preparation method according to claim 1 or 2, characterized in that The silicon source is a silanol compound.

5. The preparation method according to claim 4, characterized in that The silicon source is one or more of trialkoxysilane and tetraalkoxysilane.

6. The preparation method according to claim 5, characterized in that The trialkoxysilane is trimethoxysilane, triethoxysilane, ethyltriethoxysilane or a mixture thereof, and the tetraalkoxysilane is tetramethoxysilane, tetraethoxysilane or a mixture thereof.

7. The preparation method according to claim 1, characterized in that The carbon source is selected from a polymer precursor, and the silicon source and the polymer precursor are hydrolyzed and polymerized under alkaline conditions to form a precursor solution.

8. The preparation method according to claim 7, characterized in that The polymer precursor includes polyphenols.

9. The preparation method according to claim 1 or 2, characterized in that: The preparation method further comprises spinning and pre-oxidation steps before the carbonization.

10. The preparation method according to claim 9, characterized in that The carbonization temperature is increased at a rate of 0.5-10° C. / min and maintained at 500-1100° C. for 0.5-6 h.

11. The preparation method according to claim 1 or 2, characterized in that: The transition metal salt is one or more of manganese sulfate, manganese sulfate hydrate, manganese acetylacetonate, manganese acetate and manganese acetate hydrate.

12. The heterogeneous catalytic oxidation catalyst prepared by the preparation method according to any one of claims 1 to 11.

13. Use of the heterogeneous catalytic oxidation catalyst according to claim 12 in ozone catalytic oxidation.

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