Preparation method and application of high-spinning monatomic cobalt monolithic catalyst

Abstract

According to the preparation method of the high-spinning monatomic cobalt monolithic catalyst provided by the invention, monatomic sites are constructed on a millimeter-scale porous macroscopic carrier by adopting a green solvent'one-pot method ', so that the advantages of high monatomic reaction activity and high practicability and stability of the macroscopic carrier can be integrated; meanwhile, stable and ordered monatomic sites are formed through induction of a confinement effect generated by a nano pore channel in the carrier, and selective oxidation of non-free radical species dominated by the monatomic sites is enhanced through an adsorption enrichment-confinement catalysis effect to remove water pollutants; the strong carrier-metal interaction is regulated and controlled, so that the monatomic activity and the catalytic stability are improved, and the secondary pollution problem caused by metal dissolution is reduced. The preparation process is simple, convenient, green and economical, the confinement type active metal coordination environment and the non-free radical selective oxidation path are easy to regulate and control, and the application prospect in the aspect of selective oxidation removal of various pollutants under the complex water quality condition is good.

Description

Technical Field

[0001] The present invention relates to the fields of single-atom catalysis, novel environmental materials and deep purification of sewage and wastewater, and in particular to a preparation method and application of a high-spin single-atom cobalt monolithic catalyst. Background Art

[0002] Advanced oxidation technology has the ability to efficiently transform / degrade pollutants and is considered to be an effective method for treating pollutants in water. At present, the advanced oxidation technologies used to reduce pollutants in water mainly include catalytic ozone oxidation, Fenton-like oxidation, persulfate oxidation, photocatalytic oxidation, etc. This type of technology forms various free radicals (such as · OH, SO4 ·- 、O2 ·- etc.) or non-free radicals (such as 1 O2, direct electron transfer and high-valent metal species) to destroy the active functional groups of pollutants. For example, patent document CN 110526381B discloses a method for removing emerging pollutants by generating reactive oxygen species (ROS) from a Co-MOFs-based macroscopic composite material. By adding the prepared Co-MOFs-based macroscopic composite material to an aqueous solution containing peroxide, a large amount of ROS is generated to remove emerging pollutants in the water. However, due to the presence of organic matter (natural organic matter, extracellular secretions, etc.) and inorganic interfering ions (Cl – or HCO3 – / CO3 2– ) etc., · OH, SO4 ·– When removing low-concentration, high-risk pollutants from water, deep purification processes based on free radical oxidation often face challenges such as free radical quenching and low oxidant utilization efficiency. This leads to a series of technical challenges, including incomplete pollutant removal, high water quality safety risks, and high energy and chemical consumption. Essentially, this type of catalyst suffers from poor resistance to substrate interference and poor stability in actual water bodies.

[0003] The profound changes in nanotechnology, especially the development of single-atom catalysis technology, have provided many opportunities to solve the above problems. Single-atom catalysts (SACs) have a clear metal coordination structure, unique electronic structure and maximized atomic utilization, which makes them show great application potential in the selective catalytic removal of pollutants in water: (1) The single-atom site has positive charge characteristics (ACS Catal. 10 (19), 11011-11045), which is conducive to capturing negatively charged pollutants in water; (2) The coordination environment of SAC is highly adjustable (Chin. J. Catal. 43 (4), 928-955), and the stoichiometric reaction efficiency of selective catalysis to produce target active species is high. It is considered to be an ideal choice for mediating non-radical pathways and selective catalytic oxidation (Environ. Sci. Technol. 57 (50), 21416-21427); (3) SAC supports can be flexibly selected and specific catalytic sites and functional interfaces can be constructed. However, the currently developed SACs are mostly in powder form and used, which limits the large-scale application of single-atom catalysts. Constructing single-atom sites on macroscopic supports combines the advantages of high single-atom reactivity with the practicality and stability of macroscopic supports, making it one of the most important technical means to promote the large-scale application of single-atom catalysis technology. More importantly, the "confinement effect" generated by the nanopores within the macroscopic supports can induce the formation of stable and ordered single-atom sites, thereby enhancing the pollution removal efficiency of the SAC non-radical selective oxidation process through "confinement catalysis" (Water Res. 233, 119719). At the same time, leveraging the strong interaction between the support and the metal can enhance the activity and stability of single-atom catalysis, reducing the problem of single-atom metal dissolution and the generation of secondary pollution. Currently, few SAC composite materials have simultaneously taken into account these characteristics and application requirements.

[0004] Therefore, providing a monolithic single-atom catalyst with long-lasting catalytic activity and high stability that can be used to remove pollutants in water has become a technical problem that needs to be urgently solved in this field. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method and application of a millimeter-scale high-spin single-atom cobalt monolithic catalyst. The method provided by the present invention has the characteristics of simple synthesis conditions and rapid reaction. After being added to pollutant-containing water together with peroxide, the catalytic system of the present application can persistently produce non-radical active species with high selectivity and high stoichiometric reaction efficiency, effectively remove pollutants in water, and have good resistance to substrate interference in water and long-lasting and stable catalytic activity.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a high-spin single-atom cobalt monolithic catalyst, comprising the following steps:

[0008] (1) dissolving dopamine hydrochloride (PDA) and a metal salt in a buffer solution to obtain a precursor solution;

[0009] (2) adding a carrier to the precursor solution and impregnating the precursor solution at room temperature to obtain an impregnated product;

[0010] (3) washing, drying and calcining the impregnation product to obtain the high-spin single-atom cobalt monolithic catalyst;

[0011] The concentration of dopamine hydrochloride in the precursor solution is 5-20 mM, and the concentration of the metal salt is 10-60 mM; the metal salt is a cobalt salt, or a mixed salt of a cobalt salt and one or more of an iron salt, a manganese salt, a copper salt, a cerium salt or a nickel salt.

[0012] Preferably, when the metal salt is a mixed salt, the mass ratio of the cobalt salt to other metal salts is (1-10):1.

[0013] Preferably, the buffer solution in step (1) is one or more of phosphoric acid, citric acid, carbonic acid, acetic acid, barbituric acid, and Tris; and / or,

[0014] The pH of the buffer solution is 7-9.

[0015] Preferably, the carrier in step (2) is one or more of activated alumina balls, alumina ceramic membranes, zeolite molecular sieves, activated carbon, and nickel foam; and / or, the carrier is preferably a macroscopic carrier with a diameter / thickness of 1-10 mm.

[0016] Preferably, the calcination treatment in step (3) comprises: heating the impregnated product to 500-800°C at a heating rate of 5°C / min and keeping the temperature for 2-3 hours, and then cooling it to room temperature at a cooling rate of 5°C / min to obtain the high-spin single-atom cobalt monolithic catalyst.

[0017] Preferably, the calcination treatment in step (3) is carried out under air, nitrogen or argon conditions.

[0018] The present invention also provides the use of a high-spin single-atom cobalt monolithic catalyst prepared by any of the aforementioned preparation methods in the selective catalytic oxidation of water pollutants.

[0019] Preferably, the use of the high-spin single-atom cobalt monolithic catalyst in the selective catalytic oxidation of water pollutants includes adding the high-spin single-atom cobalt monolithic catalyst and peroxide to the water body to generate non-radical species to efficiently remove water pollutants.

[0020] Wherein, the peroxide is one or more of peroxymonosulfate, peroxydisulfate or ozone.

[0021] Preferably, the concentration ratio of the single-atom catalyst and peroxide to pollutants in the water body is (1000-10000):(25-100):1.

[0022] Preferably, the water pollutants are electron-rich pollutants.

[0023] The present invention provides a method for preparing a high-spin single-atom cobalt monolithic catalyst, comprising: (1) dissolving dopamine hydrochloride and a metal salt in a buffer solution to obtain a precursor solution; (2) adding a carrier to the precursor solution and performing room temperature impregnation to obtain an impregnation product; and (3) washing, drying and calcining the impregnation product to obtain the high-spin single-atom cobalt monolithic catalyst.

[0024] In the prior art, PDA is used to prepare single-atom catalysts mainly by using PDA as a source of C and N (e.g., patents CN116885215A and CN117335094A), utilizing C or N to coordinate with metal ions (e.g., forming Co-C bonds or Co-N bonds), thereby forming single-atom sites. In the present invention, the PDA adhered to the carrier mainly acts as a template. The inventors utilize the PDA self-polymerization process to pre-disperse Co ions in the complex network structure of PDA. During the calcination process, the PDA skeleton collapses through thermal decomposition (occupying space), and induces the Co ions to directly bond with the O atoms in the carrier (i.e., Co-O bonds). Since the Co ions fixed in the early stage are highly dispersed, atomically dispersed Co sites can be formed in the later stage. The Co-O bonds are anchored to the carrier surface in the form of tetrahedral coordination and high-spin states, ultimately forming a high-spin single-atom cobalt monolithic catalyst. This is an effect that the prior art fails to achieve with PDA.

[0025] Beneficial effects: 1. The catalyst in the present invention is prepared by a green solvent "one-pot method", with simple conditions and rapid reaction. 2. The catalyst in the present invention is in a high-spin state and is a millimeter-scale monolithic structure, has higher reaction activity, and is easy to recycle; 3. The constructed confined single-atom cobalt site can form a non-free radical-dominated catalytic oxidation process with peroxides (such as permonosulfate, PMS), which can achieve selective oxidation of various water pollutants under complex water quality conditions. Taking norfloxacin as an example, experiments show that the PCA / PMS system in the present invention can maintain a norfloxacin removal rate of more than 98% within 6 reaction cycles; in addition, PCA / PMS shows good resistance to substrate interference in biochemical effluent and long-lasting and stable catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1The UV-visible spectra of Al2O3 support, PCA precursor, and PCA before and after reaction;

[0027] Figure 2 This is a spherical aberration electron microscopy image of the high-spin single-atom cobalt monolithic catalyst PCA (the circles in the image indicate the distribution positions of the single-atom sites);

[0028] Figure 3 Schematic diagram of the degradation curve of phenol in water by PCA / PMS system;

[0029] Figure 4 Schematic diagram of the degradation curve of different pollutants in water by PCA / PMS system;

[0030] Figure 5 Schematic diagram of norfloxacin degradation curve in biochemical effluent using repeated PCA / PMS system; DETAILED DESCRIPTION

[0031] The present invention provides a method for preparing a high-spin single-atom cobalt monolithic catalyst, comprising the following steps:

[0032] (1) dissolving dopamine hydrochloride and a metal salt in a buffer solution to obtain a precursor solution;

[0033] (2) adding a carrier to the precursor solution and impregnating the precursor solution at room temperature to obtain an impregnated product;

[0034] (3) The impregnation product is washed, dried and calcined to obtain the high-spin single-atom cobalt integral catalyst.

[0035] In the present invention, unless otherwise specified, the substances used are commercially available products well known to those skilled in the art or can be prepared by themselves according to known methods.

[0036] The high-spin state refers to the state in which the number of unpaired electrons with the same spin direction is the largest in the electronic configuration of the same transition element ions with the same oxidation state in a certain crystal field. The Co element in the catalyst of the present invention is tetrahedral coordinated (see Figure 1 ) and presents a high-spin state; relative to the low-spin state, the high-spin state is a high-energy unstable state, which means that the Co site in the high-spin state of the present invention has a higher reactivity.

[0037] In the present invention, the concentration of dopamine hydrochloride in the precursor solution is preferably 5-20 mM, and the concentration of the metal salt is preferably 10-60 mM; the dopamine undergoes self-polymerization under alkaline conditions, during which dopamine reacts with metal ions (such as Co 2+) undergoes chelation, so that the metal ions are evenly dispersed in the network structure of polydopamine and can be fixed on the carrier surface through -NH2 or -OH. The network structure formed by polydopamine produces a confinement effect on the metal ions and plays an important role in the formation of high-spin state single-atom cobalt sites in the later stage. The present invention has no special limitation on the order of adding the dopamine hydrochloride and the metal salt.

[0038] In the present invention, the metal salt is preferably a cobalt salt, or a mixed salt of a cobalt salt and one or more of an iron salt, a manganese salt, a copper salt, a cerium salt or a nickel salt; when the metal salt is a mixed salt, the mass ratio of the cobalt salt to the other metal salts is preferably (1-10): 1. Cobalt is a key active element in the active metal salt, which activates peroxides to produce non-free radicals and then treats pollutants in wastewater; when other metal salts are compounded, other metal salts (such as cerium salts, nickel salts) mainly play a role in regulating the coordination environment (such as coordination number, coordination bond, electronic structure, etc.) of cobalt. The present invention is not particularly limited to the acid radical ion of the metal salt, as long as the metal salt is soluble, such as nitrate.

[0039] In the present invention, the buffer solution in step (1) is preferably one or more of phosphoric acid, citric acid, carbonic acid, acetic acid, barbituric acid, and Tris; and / or the pH of the buffer solution is preferably 7-9. The use of a buffer solution can ensure that the pH value of the impregnation solution fluctuates within a certain range, which is crucial for maintaining the stability of the impregnation process and the consistency of product quality.

[0040] In the present invention, the carrier in step (2) is preferably one or more of activated alumina balls, alumina ceramic membranes, zeolite molecular sieves, activated carbon, and nickel foam; the carrier is preferably a macroscopic carrier with a diameter / thickness of 1-10 mm; more preferably, the diameter / thickness of the macroscopic carrier is 1-2 mm. The present invention utilizes the "confinement effect" generated by the nanopores within the carrier to induce the formation of stable and ordered single-atom cobalt sites, achieving adsorption and enrichment of low-concentration negatively charged pollutants, and enhancing the SAC-dominated non-radical selective oxidation purification efficiency through confined catalysis. In the existing technology, single-atom catalysts used to remove pollutants from water bodies are mostly in powder form (with a small particle diameter). When used for water purification, they are very prone to problems such as agglomeration and high ion release. They also face technical difficulties such as high recycling costs, large mass transfer resistance, and sludge production. The present invention constructs atomic-level active sites on a macroscopic carrier (diameter / thickness is generally 1-10mm, optional according to actual needs) to make a millimeter-scale monolithic catalyst. It is not only easy to achieve large-scale preparation, but can also be flexibly applied to reactors or structures such as packed towers, filter columns, and fixed beds, and is expected to achieve large-scale application of single-atom catalysts.

[0041] In the present invention, the calcination treatment in step (3) preferably includes: heating the impregnated product to 500-800°C at a heating rate of 5°C / min and holding the temperature for 2-3 hours, and then cooling it to room temperature at a cooling rate of 5°C / min to obtain the high-spin single-atom cobalt monolithic catalyst. The calcination treatment destroys the skeleton of polydopamine, but the Co ions chelated therewith directly form stable chemical bonds with the oxygen element in the carrier, and the tetrahedral coordinated +2-valent Co is in a high-spin state, which makes the catalyst extremely reactive and stable.

[0042] The catalyst of the present invention adopts a "one-pot method" to prepare the precursor, which does not involve tedious and energy-consuming steps such as ultrasonic dispersion, long-term stirring, and centrifugal separation, thereby saving energy; the prepared catalyst precursor can be washed with clean water and filtered out, without the need for organic solvents such as methanol, ethanol, and acetone, thereby being economical, environmentally friendly, simple and easy to use.

[0043] In the present invention, the calcination treatment in step (3) is preferably carried out under air, nitrogen or argon. The present invention is not particularly strict on the calcination atmosphere, and either an oxidizing (air) atmosphere or an inert atmosphere may be used.

[0044] In the prior art, PDA is used to prepare single-atom catalysts mainly by using PDA as a source of C and N (e.g., patents CN116885215A and CN117335094A), utilizing C or N to coordinate with metal ions (e.g., forming Co-C bonds or Co-N bonds), thereby forming single-atom sites. In the present invention, the PDA adhered to the carrier mainly acts as a template. The inventors utilize the PDA self-polymerization process to pre-disperse Co ions in the complex network structure of PDA. During the calcination process, the PDA skeleton collapses through thermal decomposition (occupying space), and induces the Co ions to directly bond with the O atoms in the carrier (i.e., Co-O bonds). Since the Co ions fixed in the early stage are highly dispersed, atomically dispersed Co sites can be formed in the later stage. The Co-O bonds are anchored to the carrier surface in the form of tetrahedral coordination and high-spin states, ultimately forming a high-spin single-atom cobalt monolithic catalyst. This is an effect that cannot be achieved using PDA in the prior art.

[0045] The present invention also provides the use of a high-spin single-atom cobalt monolithic catalyst prepared by any of the aforementioned preparation methods in the selective catalytic oxidation of water pollutants.

[0046] In the present invention, the application of the high-spin single-atom cobalt monolithic catalyst in the selective catalytic oxidation of water pollutants includes adding the high-spin single-atom cobalt monolithic catalyst and peroxide to the water body; the present invention adds the single-atom catalyst and peroxide to the polluted water body, uses the catalyst to catalyze the peroxide to produce active species mainly composed of non-free radicals, and efficiently degrades and removes pollutants in the water body.

[0047] In the present invention, the peroxide is preferably one or more of peroxymonosulfate, peroxydisulfate or ozone.

[0048] In the present invention, the concentration ratio of the single-atom catalyst and peroxide to the pollutants in the water is preferably (1000-10000): (25-100): 1. In the present invention, the concentration ratio of the single-atom catalyst refers to the mass concentration ratio of the catalyst as a whole, including the carrier, and is not the concentration ratio of the active components in the catalyst.

[0049] In the present invention, the water pollutants are preferably electron-rich pollutants.

[0050] In the present invention, the water pollutants are more preferably norfloxacin, ciprofloxacin, sulfadiazine, 2,4-dichlorophenol, and phenol.

[0051] The single-atom catalyst in the present invention can catalyze peroxides to produce active species mainly composed of non-free radicals, which are not easily affected by natural organic matter in water bodies and have good resistance to substrate interference in biochemical effluents; and directly oxidize and degrade pollutants by interacting with the surface groups of pollutants or transferring electrons through a medium, especially having a certain specificity for electron-rich pollutants.

[0052] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] Example 1

[0054] A method for preparing a high-spin single-atom cobalt monolithic catalyst comprises the following steps:

[0055] (1) Weigh 0.1138 g of dopamine hydrochloride and 0.5239 g of cobalt nitrate hexahydrate and dissolve them in 60 mL of Tris-HCl (pH = 8.8) buffer solution to obtain a precursor solution;

[0056] (2) adding 40 g of activated alumina (1-2 mm in diameter) to the precursor solution and impregnating the mixture at room temperature for 24 h to obtain an impregnated product;

[0057] (3) The impregnated product was washed with deionized water five times, and then dried in an oven at 105°C for 12 h. In an air atmosphere, the impregnated product was heated to 500°C at a heating rate of 5°C / min and kept warm for 3 h. The calcined product was then cooled to room temperature at a cooling rate of 5°C / min to obtain the high-spin single-atom cobalt monolithic catalyst, which was designated as PDA-Co@Al2O3 (hereinafter referred to as PCA).

[0058] After polydopamine and Co ions were anchored on the surface of the Al2O3 support, the target monolithic catalyst (PCA) was obtained by aerobic calcination. Figure 1 As shown, Co in PCA 2+ It is tetrahedral coordinated. Its UV-visible spectrum has no obvious change before and after the reaction, indicating its good stability. Figure 2 The spherical aberration electron microscopy pictures show that the active metal Co is dispersed on the Al2O3 support in the form of single atomic sites ( Figure 2 Small and medium circles indicate the distribution of single-atom sites. Figure 1 and Figure 2 The results show that the present invention provides a method for quickly synthesizing high-spin single-atom cobalt monolithic catalysts at room temperature and pressure.

[0059] Example 2

[0060] The high-spin single-atom cobalt monolithic catalyst prepared by the preparation method described in Example 1 was used in the selective oxidation treatment of phenol wastewater. A 5 mg / L aqueous phenol solution (pH = 6.38) was prepared. 80 mL of the phenol solution was placed in a clean reaction flask. Various materials (10 g / L) and peroxymonosulfate (PMS) (0.1 g / L) were added. The reaction was stirred (200 rpm) at room temperature (25 ± 1°C) for 60 minutes. 1 mL of water samples were collected at regular intervals for analysis.

[0061] The obtained data is plotted into a curve graph, such as Figure 3 As shown in Figure 2, the PCA / PMS system can oxidize and remove more than 86% of phenol within 60 minutes. Figure 3 It can be seen that the adsorption or oxidation process of phenol by PCA and PMS during the entire reaction cycle is not the main reason for its removal. The removal of phenol is mainly achieved by the activation of PMS by PCA to produce active species.

[0062] Example 3

[0063] This example investigates the effectiveness of PCA-activated PMS in removing various pollutants from water. A 5 mg / L aqueous solution of target pollutants (norfloxacin, ciprofloxacin, sulfadiazine, metronidazole, 2,4-dichlorophenol, and phenol) was prepared without pH adjustment. 80 mL of each target pollutant solution was placed in a clean reaction flask. PCA (10 g / L, prepared as in Example 1) and PMS (0.1 g / L) were added. The mixture was stirred at 200 rpm and allowed to react for 60 minutes at room temperature (25 ± 1°C). 1 mL of water was sampled at regular intervals for analysis.

[0064] The obtained data is plotted into a curve graph, such as Figure 4 As shown, the PCA / PMS system exhibited selective degradation of different pollutants within a 60-minute reaction time. Analysis revealed that the PCA / PMS system efficiently removed electron-rich pollutants (e.g., sulfadiazine, norfloxacin, ciprofloxacin, 2,4-dichlorophenol, and phenol) (removal rates of 86%-100%), while exhibited extremely weak removal of electron-poor pollutants (e.g., metronidazole) (removal rate of only 9% after a 60-minute reaction). This example indirectly reflects that the PCA / PMS system produces reactive species primarily composed of non-free radicals.

[0065] Example 4

[0066] This example investigates the reusability of a high-spin single-atom cobalt monolithic catalyst, PCA, to activate PMS for the removal of norfloxacin from water. Using secondary biochemical effluent from a sewage treatment plant as background water, a simulated water sample containing 500 μg / L of norfloxacin was prepared, with a natural pH of 8.30. The experimental steps were as follows: 5.2 g of PCA was weighed and placed in a 10 mL packed column. 80 mL of the simulated water sample was measured and placed in an Erlenmeyer flask. This was pumped into the packed column using a peristaltic pump (at a flow rate of 5 mL / min). The effluent from the packed column was returned to the original Erlenmeyer flask for recirculation. PMS was then added to the simulated water sample to initiate the first round of reaction, and 1 mL of water samples were taken at regular intervals for analysis. After a 60-minute reaction, the liquid in the pipe and packed column was drained, replaced with a new simulated water sample, and the second round of reaction was initiated. The same method was used for subsequent rounds 3-6 of reactions.

[0067] The obtained data is plotted into a curve graph, such as Figure 5 As shown in Figure 2, the PCA / PMS system can maintain a norfloxacin removal rate of more than 98% in 6 reaction cycles; Figure 5 It can be seen that PCA / PMS has good ability to resist substrate interference in biochemical effluent and long-lasting and stable catalytic activity.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a high-spin single-atom cobalt monolithic catalyst, comprising the following steps: (1) dissolving dopamine hydrochloride and a metal salt in a buffer solution to obtain a precursor solution; (2) adding a carrier to the precursor solution for impregnation at room temperature to obtain an impregnation product; (3) The impregnation product is washed, dried and calcined to obtain the high-spin single-atom cobalt monolithic catalyst; The concentration of dopamine hydrochloride in the precursor solution is 5-20 mM, and the concentration of the metal salt is 10-60 mM; the metal salt is a cobalt salt, or a mixed salt of a cobalt salt and one or more of an iron salt, a manganese salt, a copper salt, a cerium salt or a nickel salt.

2. The preparation method according to claim 1, characterized in that: When the metal salt is a mixed salt, the mass ratio of the cobalt salt to other metal salts is (1-10):

1.

3. The preparation method according to claim 1, characterized in that: The buffer solution in step (1) is one or more of phosphoric acid, citric acid, carbonic acid, acetic acid, barbituric acid, and Tris; and the pH of the buffer solution is 7-9.

4. The preparation method according to claim 1, characterized in that: In step (2), the carrier is one or more of activated alumina balls, alumina ceramic membranes, zeolite molecular sieves, activated carbon, and nickel foam; and / or, The carrier is a macroscopic carrier with a diameter / thickness of 1-10 mm.

5. The preparation method according to claim 1, characterized in that: The calcination treatment in step (3) comprises: heating the impregnated product to 500-800°C at a heating rate of 5°C / min and keeping the temperature for 2-3h, and then cooling it to room temperature at a cooling rate of 5°C / min to obtain the high-spin single-atom cobalt monolithic catalyst.

6. The preparation method according to claim 5, characterized in that: The calcination treatment in the step (3) is carried out under air, nitrogen or argon conditions.

7. Use of the high-spin single-atom cobalt monolithic catalyst prepared by the preparation method according to any one of claims 1 to 6 in the selective catalytic oxidation of water pollutants.

8. The use according to claim 7, characterized in that: The application of the high-spin single-atom cobalt monolithic catalyst in the selective catalytic oxidation of water pollutants comprises adding the high-spin single-atom cobalt monolithic catalyst and peroxide to the water to generate non-radical species to efficiently remove water pollutants; Wherein, the peroxide is one or more of peroxymonosulfate, peroxydisulfate or ozone.

9. The use according to claim 8, characterized in that: The concentration ratio of the single atom catalyst and peroxide to the pollutants in the water body is (1000-10000): (25-100):

1.

10. The use according to claim 7, characterized in that: The water pollutants are electron-rich pollutants.

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