A method for the sustained-release preparation of a high-loading single-atom catalyst and its application

Abstract

This invention provides a slow-release preparation method for a high-loading single-atom catalyst. Compared with existing technologies, this invention utilizes the ion exchange and interlayer confinement effects of montmorillonite to pre-confine the metal precursor within the montmorillonite interlayer, isolating it from the carbon and nitrogen precursors. Then, the reactive gas generated during pyrolysis slowly releases the metal precursor from the interlayer in situ, anchoring it onto the outer carbon and nitrogen support. This slow-release synthesis strategy enables targeted synthesis at single-atom sites, offering advantages such as high metal precursor utilization, pure single-atom sites, and high metal loading. Furthermore, the slow-release anchoring of the metal precursor effectively avoids nanoparticle formation, eliminating the need for subsequent acid washing and significantly reducing secondary pollution and high costs. In addition, the slow-release synthesized single-atom catalyst, when used to catalyze the activation of hydrogen peroxide to remove pollutants from water, exhibits advantages such as strong oxidative degradation ability, high pollutant removal efficiency, good catalytic stability, and a wide pH range.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and particularly relates to a slow-release preparation method of a high-loading single-atom catalyst and application thereof. BACKGROUND

[0002] In the past decade, single-atom catalysts (SACs) have been proven to have superior reactivity, selectivity and stability in various industrial catalytic processes compared with nanoscale particles and clusters. In addition, the maximum atomic utilization efficiency of SACs brings new opportunities for high-cost and low-abundance noble metals in practical applications. In SACs, the metal center and its microenvironment jointly determine the catalytic performance, and therefore, controllable anchoring and efficient modulation of the electronic structure of single-atom centers are crucial for synthesizing high-performance SACs. However, the synthesis of high-loading, site-uniform and high-performance single-atom catalysts for practical applications is still a challenge. This is mainly because single-atom metals have high surface free energy and are prone to agglomeration and even react with other functional groups to generate oxides, nitrides and sulfides and other impurities during preparation and use.

[0003] Although various synthesis strategies based on physical and chemical methods have been developed, the current synthesis and modulation methods are mainly a static thinking, that is, the support properties are changed through doping, defects, metal-support interactions and strain, and then the coordination structure and electronic properties of the metal center are modulated. These strategies often involve complex processes (such as acid washing) and special equipment, which not only greatly reduce the utilization efficiency of metal precursors, but also easily cause secondary pollution and high cost. In order to overcome the challenge of fast growth, the large number of generation of high-reactivity anchoring sites and the limited supply of uniform metal precursors are very important for controllable single-atom anchoring to reduce side reactions and nano-aggregation. Therefore, it is urgent to develop a strategy to realize selective anchoring of specific sites and control of metal self-terminated growth, so as to realize excellent heterogeneous catalysis. The slow-release concept and slow-release process have been proven to be an effective method to improve chemical and biochemical reactions in various fields (such as biological and medical delivery, soil remediation and agricultural fertilization), and therefore, by regulating the dynamic interaction between metal precursors and supports through a slow-release strategy, a new idea is expected to be provided for the synthesis of SACs. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to provide a montmorillonite-mediated slow-release preparation method of a high-loading single-atom catalyst with uniform sites and application thereof. The preparation method can balance the supply and demand relationship between metal precursors and anchoring sites, greatly improve the utilization rate of metal precursors, realize the targeted generation of high-quality sites, and realize a single-atom catalyst synthesis process with greater economic and environmental benefits.

[0005] The application provides a slow-release preparation method of a high-loading single-atom catalyst, comprising the following steps:

[0006] S1) ultrasonic blending of montmorillonite and a metal ion precursor to obtain montmorillonite intercalated with metal ions;

[0007] S2) ultrasonic dispersion of the montmorillonite intercalated with metal ions and a carbon-nitrogen precursor to obtain a carbon-coated montmorillonite precursor;

[0008] S3) pyrolysis of the carbon-coated montmorillonite precursor to obtain a high-loading single-atom catalyst.

[0009] Preferably, the montmorillonite is selected from hydrogen-based montmorillonite and / or sodium-based montmorillonite;

[0010] The metal ion in the metal ion precursor is a transition metal ion and / or a noble metal ion;

[0011] The transition metal ion is selected from one or more of chromium ion, manganese ion, iron ion, cobalt ion, nickel ion and copper ion;

[0012] The noble metal ion is selected from one or more of silver ion, gold ion and platinum ion;

[0013] The carbon-nitrogen precursor is selected from one or more of dicyandiamide, melamine and urea.

[0014] Preferably, the mass ratio of the montmorillonite to the metal ion precursor is 0.5:(0.05-1);

[0015] The mass ratio of the montmorillonite to the carbon-nitrogen precursor is 0.5:(0.5-3).

[0016] Preferably, the ultrasonic blending time in the step S1) is 5-60 min;

[0017] The ultrasonic blending time in the step S2) is 5-60 min;

[0018] The pyrolysis temperature in the step S2) is 450-650 DEG C; the pyrolysis heating rate is 2-20 DEG C / min; and the pyrolysis time is 0.5-3 h.

[0019] The application further provides a high-loading single-atom catalyst prepared by the slow-release preparation method, wherein the high-loading single-atom catalyst has a sheet core-shell structure in which a carbon-nitrogen layer coats a montmorillonite sheet; and the carbon-nitrogen layer is loaded with metal atoms.

[0020] The application further provides application of the high-loading single-atom catalyst prepared by the slow-release preparation method in water treatment.

[0021] The application also provides a water treatment method, in which the high-loading monatomic catalyst is used to catalytically activate hydrogen peroxide to remove pollutants in water.

[0022] Preferably, the ratio of the high-loading monatomic catalyst to hydrogen peroxide is 0.01 g:(0.1-1.8) mmol.

[0023] Preferably, the pollutants are phenolic pollutants, and the phenolic pollutants are selected from phenol and / or bisphenol A.

[0024] Preferably, the pH value of the water is 3-11.

[0025] The application provides a slow-release preparation method of a high-loading monatomic catalyst, which comprises the following steps: S1) blending montmorillonite with a metal ion precursor and performing ultrasonic treatment to obtain montmorillonite intercalated with the metal ion; S2) blending the montmorillonite intercalated with the metal ion with a carbon-nitrogen precursor and performing ultrasonic dispersion to obtain a carbon-coated montmorillonite precursor; and S3) pyrolyzing the carbon-coated montmorillonite precursor to obtain the high-loading monatomic catalyst. Compared with the prior art, the application utilizes the ion exchange and interlayer restriction of montmorillonite to pre-limit the metal precursor in the interlayer of the montmorillonite, so that the metal precursor is separated from the carbon-nitrogen precursor, and then the reactive gas generated in the pyrolysis process is used to slowly release the metal precursor in the interlayer in situ, so that the metal precursor is anchored on the outer carbon-nitrogen carrier. The slow-release synthesis strategy can realize the targeted synthesis of monatomic sites, has the advantages of high utilization rate of the metal precursor, pure monatomic sites and high metal loading, and effectively avoids the formation of nanoparticles by slow-release anchoring of the metal precursor, so that subsequent acid washing and the like are not needed, and secondary pollution and high cost are greatly reduced. In addition, the slow-release synthesized monatomic catalyst is used to catalytically activate hydrogen peroxide to remove pollutants in water, and has the advantages of strong oxidative degradation capacity, high pollutant removal efficiency, good catalytic stability and wide pH application range. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The slow-release preparation flowchart of the high-loading monatomic catalyst provided by the application is shown in the figure;

[0027] Figure 2 The scanning electron microscope (SEM) image (A) and the Raman spectrum image (B) of the high-loading Cu monatomic catalyst with uniform sites obtained in Example 1 of the application are shown in the figure;

[0028] Figure 3 The high-resolution transmission electron microscope (HRTEM) image and the corresponding elemental analysis image of the high-loading Cu monatomic catalyst with uniform sites obtained in Example 1 of the application are shown in the figure;

[0029] Figure 4(A) and the Cu K-edge Fourier transform graph and fitting results (B) of the X-ray absorption fine structure spectrum of the high-angle dark-field annular scanning transmission electron microscopy image of the high-loading Cu monatomic catalyst with uniform sites obtained in Example 1 of the present application;

[0030] Figure 5 Comparison diagram of metal precursor utilization rate of the high-loading Cu monatomic catalyst with uniform sites prepared by the slow-release synthesis method of the present application and the Cu monatomic catalyst prepared by the conventional pyrolysis method;

[0031] Figure 6 Comparison diagram of activity of the Cu monatomic catalysts prepared by the slow-release synthesis method of the present application and the conventional pyrolysis method in treating phenol wastewater;

[0032] Figure 7 Comparison diagram of heavy metal dissolution in the process of treating phenol wastewater by the Cu monatomic catalysts prepared by the slow-release synthesis method of the present application and the conventional pyrolysis method;

[0033] Figure 8 Comparison diagram of degradation capacity of the high-loading Cu monatomic catalyst with uniform sites in treating phenol wastewater under different hydrogen peroxide dosages according to the present application;

[0034] Figure 9 Diagram of the treatment capacity of the high-loading Cu monatomic catalyst with uniform sites according to the present application for phenol wastewater with different pH values. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0036] The present application provides a slow-release preparation method of a high-loading monatomic catalyst, comprising the following steps: S1) blending and ultrasonicating montmorillonite and a metal ion precursor to obtain montmorillonite intercalated with metal ions; S2) blending and ultrasonicating the montmorillonite intercalated with metal ions with a carbon-nitrogen precursor to obtain carbon-coated montmorillonite precursor; and S3) pyrolyzing the carbon-coated montmorillonite precursor to obtain a high-loading monatomic catalyst.

[0037] Reference is made to Figure 1 , Figure 1 The slow-release preparation flowchart of the high-loading monatomic catalyst according to the present application is shown in the figure.

[0038] The application utilizes the ion exchange and interlayer restriction of montmorillonite, limits the metal precursor in the interlayer of montmorillonite in advance, and separates it from the carbon-nitrogen precursor; then slowly releases the metal precursor in the interlayer in situ by using the reactive gas generated in the pyrolysis process, and anchors it on the outer carbon-nitrogen carrier.

[0039] In the application, the sources of all raw materials are not specially limited and can be commercially available.

[0040] The montmorillonite and the metal ion precursor are blended and ultrasonically treated to obtain the montmorillonite intercalated with metal ions; the montmorillonite is preferably hydrogen-based montmorillonite and / or sodium-based montmorillonite; the metal ion precursor is a salt corresponding to the metal ion known to those skilled in the art, and is not specially limited, and in the application, it is preferably an inorganic salt corresponding to the metal ion, more preferably one or more of a nitrate salt, a sulfate salt and a chloride salt corresponding to the metal ion; the metal ion in the metal ion precursor is a transition metal ion and / or a noble metal ion; the transition metal ion is preferably one or more of a chromium ion, a manganese ion, an iron ion, a cobalt ion, a nickel ion and a copper ion; the noble metal ion is preferably one or more of a silver ion, a gold ion and a platinum ion; the mass ratio of the montmorillonite to the metal ion precursor is preferably 0.5:(0.05-1), more preferably 0.5:(0.1-1), further preferably 0.5:(0.1-0.5), and most preferably 0.5:(0.1-0.3); in the examples provided in the application, the mass ratio of the montmorillonite to the metal ion precursor is specifically 0.5:0.144 or 0.5:0.24; the power of the ultrasonic treatment is preferably 200-600 W, more preferably 300-500 W, and further preferably 400 W; and the time of the ultrasonic treatment is preferably 5-60 min, more preferably 10-40 min.

[0041] The montmorillonite intercalated with metal ions is blended with a carbon-nitrogen precursor, and ultrasonically dispersed to obtain a carbon-coated montmorillonite precursor; the carbon-nitrogen precursor is a carbon-nitrogen precursor known to those skilled in the art, and is not specially limited, and in the application, it preferably includes but is not limited to one or more of dicyandiamide, melamine and urea; the mass ratio of the montmorillonite to the carbon-nitrogen precursor is preferably 0.5:(0.5-3), more preferably 0.5:(0.5-2), further preferably 0.5:(0.5-1.5), and most preferably 0.5:(0.5-1); the power of the ultrasonic dispersion is preferably 200-600 W, more preferably 300-500 W, and further preferably 400 W; and the time of the ultrasonic dispersion is preferably 5-60 min, more preferably 10-40 min.

[0042] pyrolyzing the carbon-coated montmorillonite precursor to obtain the high-loading single-atom catalyst; the pyrolysis temperature is preferably 450-650 DEG C, more preferably 500-600 DEG C, and even more preferably 550 DEG C; the pyrolysis temperature increase rate is preferably 2-20 DEG C / min, more preferably 5-20 DEG C / min, and even more preferably 8-15 DEG C / min, and most preferably 10-13 DEG C / min; and the pyrolysis time is preferably 0.5-3 h, more preferably 0.5-2.5 h, and even more preferably 1-2 h, and most preferably 1-1.5 h.

[0043] The present application utilizes a slow-release strategy to balance the supply-demand relationship between metal ion precursors and anchoring sites in the synthesis of single-atom catalysts, to prepare high-loading metal single-atom catalysts with uniform sites, which are used to catalytically activate hydrogen peroxide (H2O2) to remove pollutants in water, and have the advantages of strong oxidative degradation ability, high pollutant removal efficiency, good catalytic stability, and wide pH application range. The slow-release synthesis strategy provided by the present application has the advantages of simple preparation method, target synthesis of single-atom sites, high utilization rate of metal precursors, pure single-atom sites, and high metal loading. Moreover, the metal precursors are anchored by slow release, effectively avoiding the formation of nanoparticles, and subsequent acid washing is not required, greatly reducing secondary pollution and high cost, and providing a new idea for the synthesis and regulation of high-performance single-atom catalysts.

[0044] The present application also provides a high-loading single-atom catalyst prepared by the above slow-release preparation method, wherein the high-loading single-atom catalyst has a core-shell structure of a montmorillonite sheet coated with a carbon nitride layer; and the carbon nitride layer is loaded with metal atoms.

[0045] The montmorillonite and the metal atoms are the same as described above, and will not be repeated here.

[0046] The present application also provides a use of the high-loading single-atom catalyst prepared by the above slow-release preparation method in water treatment.

[0047] The present application also provides a method for water treatment, wherein the high-loading single-atom catalyst prepared by the above slow-release preparation method is used to catalytically activate hydrogen peroxide to remove pollutants in water.

[0048] Preferably, the ratio of the high-loading single-atom catalyst to hydrogen peroxide is 0.01 g:(0.1-1.8) mmol, more preferably 0.01 g:(0.1-1.5) mmol, and even more preferably 0.01 g:(0.1-1.0) mmol. In the embodiments provided by the present application, the ratio of the high-loading single-atom catalyst to hydrogen peroxide is specifically 0.01 g:0.1148 mmol or 0.01 g:0.1176-0.94 mmol.

[0049] The pollutants are preferably phenolic pollutants; the phenolic pollutants are preferably phenol and / or bisphenol A.

[0050] The pH value of the water is preferably 3-11; in the embodiments provided by the present application, the pH value of the water is specifically 3, 3.23, 5, 7, 9 or 11.

[0051] In order to further illustrate the present application, the present application provides a slow-release preparation method and application of a high-loading single-atom catalyst in the following embodiments.

[0052] The reagents used in the following embodiments are commercially available.

[0053] Example 1: A high-loading Cu single-atom catalyst with uniform sites was prepared by a slow-release synthesis method

[0054] (1) 0.144 g of copper nitrate trihydrate was dissolved in 1 ml of deionized water, and then 0.5 g of sodium-based montmorillonite was mixed with the copper nitrate solution, and 400 W ultrasonic dispersion was performed for 20 min to perform ion exchange, thereby obtaining Cu ion intercalated montmorillonite;

[0055] (2) The Cu ion intercalated montmorillonite obtained in step (1) was mixed with 0.5 g of melamine, and then 0.5 ml of deionized water was added, and 400 W ultrasonic dispersion was performed for 15 min to obtain a precursor material of carbon-coated montmorillonite;

[0056] (3) The precursor material obtained in step (2) was treated by pyrolysis for 1 h (heating rate 13℃ / min, pyrolysis temperature 550℃), thereby obtaining a high-loading Cu single-atom catalyst with uniform sites.

[0057] Referring to Figure 2 , Figure 3 , Figure 4 and Figure 5 . Figure 2 FIG. 1 is a scanning electron microscope image (A) and Raman spectrum images (B) of the high-loading Cu single-atom catalyst with uniform sites obtained in Example 1 of the present application under different excitation wavelengths; it can be seen from Figure 2 that the synthesized high-loading single-atom catalyst with uniform sites has a sheet structure. Figure 3 FIG. 2 is a high-resolution transmission electron microscope image and corresponding elemental analysis image of the high-loading Cu single-atom catalyst with uniform sites obtained in Example 1 of the present application; it can be seen from Figure 3 that the synthesized single-atom catalyst has a sheet core-shell structure of carbon-coated montmorillonite, and the active metal is distributed on the outer layer of the carbon carrier. Figure 4 FIG. 3 is a high-angle dark-field annular scanning transmission electron microscope image (A) and Cu K-edge Fourier transform spectrum and fitting results (B) of the X-ray absorption fine structure spectrum of the high-loading Cu single-atom catalyst with uniform sites obtained in Example 1 of the present application; it can be seen fromFigure 4 It can be seen that the active metal is monatomic dispersion, and the loading density is high. Figure 5 Comparison chart of metal precursor utilization rate of the site-uniform high-loading Cu monatomic catalyst prepared by the slow-release synthesis method of the present application and the Cu monatomic catalyst prepared by the conventional pyrolysis method; Figure 5 It can be seen that the slow-release synthesis method greatly improves the utilization rate of the metal precursor.

[0058] Example 2 Site-uniform high-loading Fe monatomic catalyst prepared by the slow-release synthesis method

[0059] (1) 0.24 g of iron nitrate nonahydrate was dissolved in 1 ml of deionized water, and then 0.5 g of sodium-based montmorillonite was blended with the iron nitrate solution, and 400 W ultrasonic dispersion was performed for 20 min to perform sufficient ion exchange, to obtain Fe ion intercalated montmorillonite;

[0060] (2) The Fe ion intercalated montmorillonite obtained in step (1) was blended with 0.5 g of dicyandiamide, and then 0.5 ml of deionized water was added, and 400 W ultrasonic dispersion was performed for 15 min to obtain a precursor material of carbon-coated montmorillonite;

[0061] (3) The precursor material obtained in step (2) was treated by pyrolysis for 1.5 h (heating rate 10 ℃ / min, pyrolysis temperature 550 ℃) to obtain a site-uniform high-loading Fe monatomic catalyst.

[0062] Comparative Example 1 Cu monatomic catalyst prepared by the conventional pyrolysis method

[0063] (1) 0.287 g of copper nitrate trihydrate was dissolved in 1.5 ml of deionized water, and then blended with 1.0 g of melamine, and ultrasonic dispersion was performed for 35 min (ultrasonic power 400 W) to obtain a precursor material;

[0064] (2) The precursor material obtained in step (1) was treated by pyrolysis for 1 h (heating rate 13 ℃ / min, pyrolysis temperature 550 ℃) to obtain a Cu monatomic catalyst prepared by the conventional pyrolysis method.

[0065] Example 3 Application of site-uniform high-loading Cu monatomic catalyst in activating hydrogen peroxide to remove pollutants in water

[0066] The site-uniform high-loading Cu monatomic catalyst obtained in Example 1 was added to a solution with 20 mg / L phenol as the removal object (pH value 7), and the addition amount was 0.5 g / L, and ultrasonic dispersion was performed. Stirring was performed at 700 rpm for 20 min to establish the adsorption-desorption equilibrium of the pollutants. Subsequently, hydrogen peroxide was added to the solution, and the addition amount was 5.74 mM. The stirring speed was maintained at 700 rpm. The phenol removal rate was more than 99% within 40 min.

[0067] Referring to Figure 6 and Figure 7 . Figure 6 Figure for comparing the activity of Cu single-atom catalysts prepared by the slow-release synthesis method of the present application and the conventional pyrolysis method in treating phenol wastewater; from Figure 6 It can be seen from Figure 7 Figure for comparing the heavy metal leaching during the process of Cu single-atom catalysts prepared by the slow-release synthesis method of the present application and the conventional pyrolysis method in treating phenol wastewater; from Figure 7 It can be seen from

[0068] Example 4 Application of the site-uniform high-loading Cu single-atom catalyst in treating phenol wastewater under different hydrogen peroxide dosages

[0069] The site-uniform high-loading Cu single-atom catalyst obtained in Example 1 was added to a solution with 20 mg / L of phenol as the removal object (pH value was 7), and the dosage was 0.5 g / L, and ultrasonic dispersion was performed. Stirring was performed at 700 rpm for 20 min to establish the adsorption-desorption equilibrium of pollutants. Then different amounts of hydrogen peroxide (0.2-1.6 g / L) were added to the solution. The stirring speed was maintained at 700 rpm.

[0070] Referring to Figure 8 , Figure 8 Figure for comparing the degradation capacity of the site-uniform high-loading Cu single-atom catalyst in treating phenol wastewater under different hydrogen peroxide dosages; from Figure 8 It can be seen from

[0071] Example 5 Application of the site-uniform high-loading Cu single-atom catalyst in activating hydrogen peroxide to remove pollutants in water under different pH values

[0072] The site-uniform high-loading Cu single-atom catalyst obtained in Example 1 was respectively added into a solution with 20 mg / L phenol as a removal object, the pH values of the solution were 3, 3.23, 5, 7, 9 and 11 respectively (0.5M NaOH and 0.5M H2SO4 solution were used to adjust the pH value of the solution), the catalyst dosage was 0.5 g / L, and ultrasonic dispersion was carried out. Stirring was carried out at 700 rpm for 20 min to establish the adsorption-desorption equilibrium of the pollutants. Then, hydrogen peroxide was added into the solution, and the dosage was 5.74 mM. The stirring speed was maintained at 700 rpm.

[0073] Referring to Figure 9 , Figure 9 Figure 1 is a diagram of the treatment capacity of the site-uniform high-loading Cu single-atom catalyst of the present application on phenol wastewater with different pH values; from Figure 9 It can be seen from Figure 1 that the site-uniform high-loading Cu single-atom catalyst of the present application has a wide pH range; when the pH value is 3, the phenol removal rate within 1 h can reach 84%; when the pH value is 3.23, the phenol removal rate within 1 h can reach 99.5%; when the pH values are 5, 7 and 9, the phenol removal rate within 1 h can reach 100%; and when the pH value is 11, the phenol removal rate within 1 h can reach 95.5%.

[0074] In summary, the slow-release synthesis method of the montmorillonite-mediated site-uniform high-loading single-atom catalyst provided by the present application has the following advantages:

[0075] 1. The present application utilizes the ion exchange and interlayer restriction of montmorillonite to pre-limit the metal precursor in the interlayer of montmorillonite, so as to separate the metal precursor from the carbon-nitrogen precursor, and then utilizes the reactive gas generated in the pyrolysis process to slowly release the metal precursor in situ and anchor the metal precursor on the outer carbon-nitrogen carrier; the supply-demand relationship between the metal precursor and the anchor site can be effectively balanced;

[0076] 2. The slow-release synthesis method of the present application reduces the thermal diffusion loss of the metal ion precursor, greatly improves the utilization rate of the metal precursor, and is particularly important for the industrial application of high-cost and low-abundance noble metals;

[0077] 3. The slow-release synthesis strategy of the present application can realize self-terminated growth of metal atoms, effectively avoid the formation of clusters and nanoparticles, and directly realize high single-atom metal loading, which is conducive to obtaining high catalytic performance in the industrial application process;

[0078] 4. The present application can effectively regulate the dynamic interaction between the metal ion and the anchor carrier by controlling the slow release of the metal precursor, realize effective regulation of the coordination structure and electronic properties of the single-atom center, and optimize the performance of the single-atom catalyst;

[0079] 5、The slow-release synthesis method of the application effectively avoids the formation of nanoparticles by slow-release anchoring of metal precursors, without subsequent acid washing and the like, greatly reducing secondary pollution and high cost;

[0080] 6、The slow-release synthesis method of the application makes the anchoring of metal atoms more accurate and efficient, and can realize targeted synthesis of single-atom sites;

[0081] 7、The slow-release synthesized single-atom catalyst of the application is used for catalytic activation of hydrogen peroxide (H2O2) to remove pollutants in water, and has the advantages of strong oxidative degradation capacity, high pollutant removal efficiency, good catalytic stability and wide pH application range, while metal dissolution is greatly reduced, and there is no secondary pollution;

[0082] 8、The slow-release synthesized high-loading single-atom catalyst of the application has simple preparation technology, strong operability, remarkable effect and obvious economy, and has broad industrial application prospects in the fields of catalysis and environmental pollution purification.

Claims

1. A method for the slow release preparation of high loading single atom catalysts, characterized by, The method comprises the following steps: S1) blending and ultrasonicating montmorillonite with metal ion precursors to obtain montmorillonite intercalated with metal ions; S2) blending the montmorillonite intercalated with metal ions with carbon-nitrogen precursors, and ultrasonicating and dispersing to obtain carbon-coated montmorillonite precursors; S3) pyrolyzing the carbon-coated montmorillonite precursors to obtain high-loading single-atom catalysts; The montmorillonite is selected from hydrogen-based montmorillonite and / or sodium-based montmorillonite; The metal ions in the metal ion precursors are one or more of iron ions or copper ions; The carbon-nitrogen precursors are selected from one or more of dicyanamide, melamine and urea; The mass ratio of the montmorillonite to the metal ion precursors is 0.5:(0.05-1); The mass ratio of the montmorillonite to the carbon-nitrogen precursors is 0.5:(0.5-3); The high-loading single-atom catalysts have a layered core-shell structure of carbon-nitrogen layer-coated montmorillonite, and metal atoms are loaded on the carbon-nitrogen layer.

2. The sustained release manufacturing process according to claim 1, wherein, The blending and ultrasonicating in step S1) is performed for 5-60 min; The ultrasonicating and dispersing in step S2) is performed for 5-60 min; The pyrolyzing in step S3) is performed at a temperature of 450-650 DEG C, a heating rate of 2-20 DEG C / min and a time of 0.5-3 h.

3. The high loading single atom catalyst prepared by the slow release preparation method of claim 1 or 2, characterized in that, The high-loading single-atom catalysts have a layered core-shell structure of carbon-nitrogen layer-coated montmorillonite, and metal atoms are loaded on the carbon-nitrogen layer.

4. Use of the high-loading single-atom catalyst prepared by the slow-release preparation method of claim 1 or 2 in water treatment.

5. A method of water treatment, characterized by, The high-loading single-atom catalyst prepared by the slow-release preparation method of claim 1 or 2 removes pollutants in water by catalyzing and activating hydrogen peroxide.

6. The method of claim 5, wherein, The ratio of the high-loading single-atom catalyst to hydrogen peroxide is 0.01 g:(0.1-1.8) mmol.

7. The method of claim 5, wherein, The pollutants are phenolic pollutants selected from phenol and / or bisphenol A.

8. The method of claim 5, wherein, The pH value of the water is 3-11.

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