Preparation method of MOF-derived Sm-doped Co3O4 catalyst and application of MOF-derived Sm-doped Co3O4 catalyst in water treatment
The Sm-doped Co3O4 catalyst prepared by MOF derivatization and rare earth Sm doping technology solves the problems of low activity and poor stability of existing cobalt-based catalysts in water treatment, and achieves efficient degradation of recalcitrant organic pollutants. It is suitable for complex water bodies such as tap water, river water and medical wastewater, and has the potential for industrial application.
Patent Information
- Application Number
- CN202610464081.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-09
- Publication Date
- 2026-05-12
AI Technical Summary
Existing spinel-type heterogeneous cobalt-based catalysts suffer from problems such as low activity of catalytic active sites, poor electron transfer efficiency, difficulty in controlling the PMS activation pathway, small specific surface area, and susceptibility to interference from water matrix, which limit their large-scale application in water treatment.
Sm-doped Co3O4 catalysts were prepared by combining MOF derivatization with rare earth Sm doping technology. By forming bridging structural units through atomic-level uniform doping, the electronic configuration and spin state were optimized, thereby achieving the directional generation of sulfate radicals and improving catalytic activity and stability.
The prepared catalyst has a regular morphology and uniformly dispersed active sites, and has the ability to efficiently degrade recalcitrant organic pollutants. It has a wide applicable pH range, excellent cycle stability, and is suitable for complex water bodies such as tap water, river water and medical wastewater. It can also be produced on a large scale, with high degradation efficiency and low cost.
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Figure CN122006729A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a method for preparing rare earth-doped metal oxide catalysts, and more particularly to a MOF-derived Sm-doped catalyst. The preparation method of the catalyst and its application in the degradation of recalcitrant organic pollutants in water bodies by activated persulfate. Background Technology
[0002] As a typical spinel-type heterogeneous cobalt-based catalyst, it possesses advantages such as good environmental compatibility, structural stability, and moderate cost, making it a commonly used catalytic material for activating PMS. However, pure-phase... There are many technical defects: First, the intrinsic activity of the catalytic active sites is low, resulting in poor electron transfer efficiency. Secondly, the PMS activation pathway is difficult to precisely control, the generation of sulfate free radicals has poor selectivity, and it is easy to generate a variety of active species and trigger side reactions. Third, the active sites of the catalyst are prone to aggregation, resulting in a small specific surface area and limited contact area with pollutants, leading to a low overall degradation efficiency. These defects severely limit its large-scale application in actual water treatment projects.
[0003] Doping modification is an optimization Effective technical pathways for improving electronic structure and catalytic performance: Rare earth elements possess unique 4f electron configurations, abundant coordination sites, and strong electronegativity. Incorporating them into the lattice of metal oxides can effectively regulate the electron density, lattice structure, and spin state of the metal sites, thereby significantly enhancing the catalytic activity and stability of the catalyst. The metal-organic framework (MOF) derivatization method, using MOF materials as precursors and preparing metal oxides through high-temperature calcination, effectively preserves the porous structure and morphological characteristics of MOF materials. This method can prepare metal oxide catalysts with regular morphology, uniformly dispersed active sites, abundant pore structure, and large specific surface area, providing reliable technical support for the precise control of catalyst structure.
[0004] Currently, rare earth samarium doping Catalyst research is still in its early stages, and existing technologies have many shortcomings: First, a mature, stable, and scalable MOF-derived Sm doping technology has not yet been developed. The catalyst preparation process is complex, and existing preparation methods involve harsh reaction conditions, making it difficult to achieve mass production. Secondly, regarding Sm doping pairs The mechanism of spin state regulation of Co ions and its influence on PMS activation pathway and directional generation of sulfate radicals lack systematic and in-depth research. Third, the catalyst produced has poor adaptability to actual water bodies, is easily affected by the water matrix, has insufficient cycle stability, and has a high metal leaching rate, which cannot meet the actual needs of industrial water treatment.
[0005] Therefore, it is necessary to develop a MOF-derived Sm-doped material that is simple to process, scalable, exhibits excellent catalytic performance, and demonstrates strong stability. Catalysts are used to solve the above-mentioned technical problems. Summary of the Invention
[0006] To address the shortcomings of existing technologies, the present invention aims to provide a MOF-derived Sm-doped material. The catalyst preparation method is simple, has mild reaction conditions, good reproducibility, and has the potential for large-scale production. The catalyst prepared by this method has a regular morphology and uniformly dispersed active sites. It can precisely control the spin state of Co ions to achieve the directional generation of sulfate radicals. It has a high efficiency in degrading recalcitrant organic pollutants in water, and is applicable to a wide pH range, has excellent cycle stability, and low metal leaching, making it suitable for various actual water treatment scenarios.
[0007] Another object of the present invention is to provide the above-mentioned MOF-derived Sm-doped material. The application of the catalyst in water treatment specifically involves using the catalyst to activate persulfate and degrade recalcitrant organic pollutants in water. These recalcitrant organic pollutants include, but are not limited to, antibiotics such as sulfamethoxazole, phenolic compounds, and industrial dyes. This application has the advantages of high degradation efficiency and fast reaction speed, and has good prospects for industrial application.
[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A MOF-derived Sm-doped The method for preparing the catalyst includes the following steps: Step 1: Prepare solutions A and B: Solution A is an aqueous solution of 2-methylimidazole; Solution B is a mixed aqueous solution of cobalt salt, samarium salt, and hexadecyltrimethylammonium bromide; Step 2: Slowly add solution B dropwise to solution A, stir the reaction, and collect the precipitate formed; Step 3: The precipitate is washed and dried to obtain the Sm-ZIF-67 precursor; Step 4: Calcine the Sm-ZIF-67 precursor in air, cool it naturally to room temperature, and then grind it to obtain the MOF-derived Sm-doped Co3O4 catalyst.
[0009] Preferably, the ratio of 2-methylimidazole to deionized water in solution A is 9g:80mL; Solution B contains , And 10 mg of cetyltrimethylammonium bromide, in 20 mL of deionized water.
[0010] Preferably, the stirring reaction conditions in step two are stirring at 25°C for 3 hours.
[0011] Preferably, in step two, the precipitate is collected by centrifugation with centrifugation parameters of 8000 rpm and 10 min.
[0012] Preferably, in step three, the washing process involves alternating between ethanol and deionized water, repeated three times. The drying conditions are 60℃ overnight.
[0013] Preferably, in step four, the heating rate of calcination is 2℃ / min, the calcination temperature is 400℃, and the holding time for calcination is 4h.
[0014] Preferred, Sm 3+ Atomically uniform doping is applied to the Co3O4 spinel lattice, replacing part of the octahedral Co. 3+ Sites form Co-O-Sm bridging structural units.
[0015] Preferably, the obtained catalyst contains Co 3+ It is in the intermediate spin state, and the catalyst active sites are uniformly dispersed and have a large specific surface area.
[0016] Preferably, the method can be scaled up to a kilogram-scale preparation, and the morphology, crystal form and catalytic performance of the catalyst after scale-up are consistent with those of the laboratory small-scale sample.
[0017] Application of a MOF-derived Sm-doped Co3O4 catalyst in water treatment, wherein the catalyst is prepared by any of the preparation methods described in claims 1-9 and is used to activate persulfate and degrade recalcitrant organic pollutants in water. The recalcitrant organic pollutants include at least one of antibiotic pollutants, phenolic compounds, and industrial dyes; The antibiotic contaminant is at least one of sulfamethoxazole, sulfaisoxazole, oxytetracycline, tetracycline, ciprofloxacin, and norfloxacin. The phenolic compound is at least one of bisphenol A, phenol, and 4-chlorophenol; The industrial dye is at least one of Rhodamine B, methylene blue, and Congo red. The water treatment is applicable to water bodies with a pH range of 3 to 11. The water body includes at least one of tap water, river water, and medical wastewater.
[0018] The principles and beneficial effects of this invention are as follows: This invention employs MOF derivatization combined with rare-earth Sm doping technology. Using ZIF-67 as a template, rare-earth Sm ions are introduced for in-situ doping, and Sm-doped materials are prepared through a one-step calcination process. catalyst. Atomic-level uniform doping In the spinel lattice, some octahedrons are replaced. The site is fixed without disrupting the original regular square morphology of the catalyst, while inducing local lattice distortion to form a stable... Bridge-connected structural unit.
[0019] Sm doping can be precisely controlled. The spin state will have a high spin Transformation into intermediate spin Optimize the electronic configuration of Co active sites and enhance... The relative content of Co makes the Co center in an electron-deficient state, which greatly enhances the orbital hybridization ability and charge transfer efficiency between the catalyst and PMS, realizes the directional and efficient generation of sulfate radicals, eliminates the occurrence of ineffective side reactions, and improves the selectivity of pollutant degradation.
[0020] The Sm-doped material prepared by this invention The catalyst exhibits stable physicochemical properties and extremely low metal leaching, effectively preventing homogeneous catalytic side reactions and reducing secondary pollution. With a large specific surface area and ample active sites, under optimized conditions, it can achieve complete degradation of sulfamethoxazole in water within 10 minutes. Its apparent pseudo-first-order rate constant is significantly higher than that of the pure phase catalyst. It boasts a 55-fold improvement. This catalyst has an extremely wide applicable pH range, maintaining high degradation efficiency within a pH range of 3-11. It exhibits strong adaptability to complex real-world water bodies such as tap water, river water, and medical wastewater, and can efficiently degrade a variety of recalcitrant organic pollutants.
[0021] Meanwhile, the preparation process of this invention is simple, the reaction conditions are mild, the raw materials are readily available, and the reproducibility is good. No special equipment is required, and it can realize the production scale from laboratory small-scale to kilogram-scale. Moreover, the performance of the catalyst does not significantly decrease after scale-up. The catalyst has excellent cycle stability and still maintains extremely high degradation efficiency after nine consecutive cycles. After deactivation, it can be regenerated by mild heat treatment, which greatly reduces the cost of use. It has extremely high application value and promotion prospects in the field of industrial water treatment. Attached Figure Description
[0022] Figure 1 For the present invention A schematic diagram of the catalyst preparation process.
[0023] Figure 2 The invention obtained Catalysts and pure phases Morphology and structural characterization diagrams of the catalyst; in, Figure 2 a and b are pure phases, respectively. and TEM image of the catalyst; Figure 2 c and d are pure phases, respectively. and HR-TEM image of the catalyst; Figure 2 e is catalyst picture; Figure 2 f is Sm doping EDS elemental mapping diagram of the catalyst.
[0024] Figure 3 The product obtained by this invention Catalysts and pure phases Electronic structure characterization diagram of the catalyst; in, Figure 3 a is the XRD pattern of the catalyst; Figure 3 b is the Raman spectrum of the catalyst; Figure 3 c is Spectrum; Figure 3 d is Spectrum; Figure 3 e is Spectrum; Figure 3 f is Spectrum.
[0025] Figure 4 The product obtained by this invention Catalysts and pure phases Spin state characterization diagram of the catalyst; in, Figure 4 a is the room temperature magnetization hysteresis curve; Figure 4 b is the fitted graph of the temperature-dependent magnetization curve.
[0026] Figure 5 The following is a characterization diagram of the performance of the catalyst prepared in this invention in activating PMS to degrade pollutants and the active species. in, Figure 5 a is a comparison of the degradation efficiency of sulfamethoxazole in different systems; Figure 5 b is the result of the free radical quenching experiment; Figure 5 c is EPR signal diagram.
[0027] Figure 6 The diagram shows the actual water treatment performance and large-scale preparation verification of the catalyst of this invention. in, Figure 6 a is a graph showing the degradation efficiency of pollutants in water bodies at different pH levels; Figure 6 b is a graph showing the degradation efficiency of pollutants in different actual water bodies; Figure 6 c is the cyclic stability test result of the catalyst; Figure 6 b shows the degradation effect of various recalcitrant pollutants.
[0028] Figure 7 The diagram shows the actual water treatment performance and large-scale preparation verification of the catalyst of this invention. in, Figure 7 a, Figure 7 b is a schematic diagram of kilogram-scale preparation; Figure 7 c is a comparison of the catalytic performance of the enlarged sample and the laboratory small-scale sample; Figure 7 d is the enlarged XRD pattern of the sample; Figure 7 e shows the packed column reactor apparatus diagram and 7f shows the long-term operation effect diagram. Detailed Implementation
[0029] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0030] according to Figure 1 As shown in Example 1, MOF-derived Sm doping Catalyst preparation; Step 1: Prepare solution A: Weigh 9g of 2-methylimidazole, add it to 80mL of deionized water, and stir magnetically until completely dissolved to obtain a clear solution A; Prepare solution B: Weigh... , Add 10 mg of cetyltrimethylammonium bromide to 20 mL of deionized water and stir continuously until completely dissolved to obtain solution B.
[0031] Step 2: Add solution B slowly and uniformly to solution A. After the addition is complete, continue stirring at room temperature for 3 hours to allow the precursor to crystallize fully.
[0032] Step 3: Place the mixed reaction solution in a centrifuge and centrifuge at 8000 rpm for 10 minutes to collect the purple precipitate.
[0033] Step 4: Wash the precipitate alternately with ethanol and deionized water, repeating the washing process 3 times to completely remove unreacted reagents. Place the washed precipitate in a 60℃ oven and dry it overnight to obtain the Sm-ZIF-67 precursor.
[0034] Step 5: Transfer the Sm-ZIF-67 precursor to a muffle furnace and heat it to 400°C at a rate of 2°C / min under air atmosphere. Calcine at this temperature for 4 hours, and after naturally cooling to room temperature, grind it into a fine powder to obtain the MOF-derived Sm doped precursor. Catalyst, denoted as .
[0035] Comparative Example 1: Pure Phase Catalyst preparation; The preparation steps are exactly the same as in Example 1, except that solution B is removed. Pure ZIF-67 precursor was obtained, and then subjected to the same calcination process to obtain pure phase. Catalyst, denoted as .
[0036] Structural characterization and performance testing; Morphology and structure characterization were performed using transmission electron microscopy, high-resolution transmission electron microscopy, aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectroscopy.
[0037] according to Figure 2 The test results shown are as follows: With pure phase All samples maintained a regular square morphology with a side length of approximately 230 nm, indicating that rare-earth Sm doping did not disrupt the catalyst's framework structure. HR-TEM images showed clear... (311) Crystal plane lattice fringes: After Sm doping, the lattice spacing increased from 0.244 nm to 0.249 nm, showing a significant lattice expansion phenomenon. This phenomenon originates from the large radius... Replace small radius This leads to localized lattice distortion. AC-HAADF-STEM images show that Sm elements are uniformly dispersed in the catalyst at the atomic level, without agglomeration or the formation of impurity phases; EDS elemental mapping results indicate that Co, Sm, and O elements are uniformly distributed in the catalyst. Figure 3The test results shown are as follows: XRD pattern shows that the catalyst has a pure spinel structure with no impurity peaks. After Sm doping, the diffraction peaks corresponding to the (311) crystal plane shift slightly to a lower angle, further confirming the lattice expansion phenomenon; Raman spectroscopy shows that the octahedral sites The characteristic peaks of the bond show a significant red shift, proving that Mainly occupying the octahedron The site changed The local coordination environment.
[0038] Electronic structure and spin state characterization: Synchrotron radiation X-ray absorption spectroscopy, magnetic characterization and other methods were used to test the electronic structure and spin state of the catalyst.
[0039] according to Figure 3 The test results shown are as follows: A positive shift in the absorption edge of the spectrum confirms an increase in the average oxidation state of Co; FT-EXAFS spectroscopy shows that... , The contraction of bond lengths indicates a reorganization of the local coordination environment of the Co active site. Test results confirmed that a stable catalyst was formed inside. Bridge-connected structural unit. According to... Figure 4 The magnetic characterization results shown indicate that the pure phase C It is a high-spin state, after Sm doping, The transition to an intermediate spin state effectively optimizes the electronic structure of the catalytic active site.
[0040] Catalytic performance testing was conducted using sulfamethoxazole as the target pollutant to test the degradation performance of PMS activated by the catalyst. Specific experimental conditions were: pollutant concentration 10 mg / L, catalyst dosage 0.1 g / L, PMS dosage 0.1 g / L, and reaction carried out at room temperature.
[0041] according to Figure 5 The test results show that using the catalyst alone or PMS alone has almost no degradation effect on SMX; pure phase After 10 minutes of reaction, the degradation rate of SMX was less than 5%; while After 10 minutes of reaction, the degradation rate of SMX reached 100%, and the degradation rate was significantly improved.
[0042] The results of free radical quenching experiments and EPR characterization show that In the system, sulfate free radicals ( SMX is the dominant active species, and its generation is highly selective; species such as hydroxyl radicals, singlet oxygen, and superoxide radicals contribute very little to the degradation of SMX, thus achieving efficient and targeted degradation of pollutants.
[0043] Actual water body adaptability and stability tests, based on Figure 6 The test results shown are valid over a wide pH range of 3-11. The system can rapidly degrade SMX without being affected by significant pH fluctuations. In actual water bodies such as tap water, river water, and medical wastewater, the degradation rate of SMX remains above 99% after 10 minutes of reaction, indicating that the catalyst has extremely strong anti-interference ability. Cyclic stability tests show that the catalyst maintains extremely high degradation efficiency after nine consecutive cycles, with no significant attenuation of catalytic performance; the deactivated catalyst can completely recover its catalytic activity after mild heat treatment. Furthermore, Catalysts can efficiently remove a variety of recalcitrant organic pollutants, including antibiotics, phenolic compounds, and industrial dyes.
[0044] according to Figure 7 The scale-up experimental results shown indicate that by scaling up the reaction system to 50 L, 1.014 kg of the product can be prepared in batches. The morphology, crystal form, and catalytic performance of the scaled-up sample of the catalyst were basically consistent with those of the laboratory-scale sample. A 5L flow-through column reactor was constructed to... With the catalyst fixed on a melamine sponge, under continuous operation at 0.36 L / h, this reactor can maintain an organic pollutant removal rate of over 99% and a TOC removal rate of around 70% for 168 hours when treating medical wastewater. It has the ability to operate stably for a long time and is suitable for industrial water treatment applications.
[0045] It should be noted that, in order to simplify the description of the present invention and thus help to understand one or more embodiments of the invention, multiple features may sometimes be grouped into one embodiment, drawing or description thereof in the foregoing description of the embodiments of the present invention.
[0046] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.
Claims
1. A method for preparing a MOF-derived Sm-doped Co3O4 catalyst, characterized in that: Includes the following steps: Step 1: Prepare solutions A and B: Solution A is an aqueous solution of 2-methylimidazole; Solution B is a mixed aqueous solution of cobalt salt, samarium salt, and hexadecyltrimethylammonium bromide; Step 2: Slowly add solution B dropwise to solution A, stir the reaction, and collect the precipitate formed; Step 3: The precipitate is washed and dried to obtain the Sm-ZIF-67 precursor; Step 4: Calcine the Sm-ZIF-67 precursor in air, cool it naturally to room temperature, and then grind it to obtain the MOF-derived Sm-doped Co3O4 catalyst.
2. The method for preparing a MOF-derived Sm-doped Co3O4 catalyst according to claim 1, characterized in that: The ratio of 2-methylimidazole to deionized water in solution A is 9 g: 80 mL; Solution B contains , And 10 mg of cetyltrimethylammonium bromide, in 20 mL of deionized water.
3. The method for preparing a MOF-derived Sm-doped Co3O4 catalyst according to claim 1, characterized in that: The reaction conditions in step two are stirring at 25°C for 3 hours.
4. The method for preparing a MOF-derived Sm-doped Co3O4 catalyst according to claim 1, characterized in that: In step two, the precipitate is collected by centrifugation with centrifugation parameters of 8000 rpm and 10 min.
5. The method for preparing a MOF-derived Sm-doped Co3O4 catalyst according to claim 1, characterized in that: In step three, the washing process involves alternating between ethanol and deionized water, repeated three times. The drying conditions are 60℃ overnight.
6. The method for preparing a MOF-derived Sm-doped Co3O4 catalyst according to claim 1, characterized in that: In step four, the heating rate for calcination is 2℃ / min, the calcination temperature is 400℃, and the holding time for calcination is 4h.
7. The method for preparing a MOF-derived Sm-doped Co3O4 catalyst according to claim 1, characterized in that: Sm 3+ Atomically uniform doping is applied to the Co3O4 spinel lattice, replacing part of the octahedral Co. 3+ Sites form Co-O-Sm bridging structural units.
8. The method for preparing a MOF-derived Sm-doped Co3O4 catalyst according to claim 1, characterized in that: Co in the obtained catalyst 3+ It is in the intermediate spin state, and the catalyst active sites are uniformly dispersed and have a large specific surface area.
9. The method for preparing a MOF-derived Sm-doped Co3O4 catalyst according to claim 1, characterized in that: The method can be scaled up to the kilogram scale for preparation, and the morphology, crystal form and catalytic performance of the catalyst after scale-up are consistent with those of the laboratory small-scale sample.
10. The application of a MOF-derived Sm-doped Co3O4 catalyst in water treatment, based on a method for preparing a MOF-derived Sm-doped Co3O4 catalyst according to any one of claims 1-9, characterized in that: The catalyst is prepared by any one of the preparation methods described in claims 1-9 and is used to activate persulfate and degrade recalcitrant organic pollutants in water. The recalcitrant organic pollutants include at least one of antibiotic pollutants, phenolic compounds, and industrial dyes; The antibiotic contaminant is at least one of sulfamethoxazole, oxytetracycline, tetracycline, ciprofloxacin, and norfloxacin; The phenolic compound is at least one of bisphenol A, phenol, and 4-chlorophenol; The industrial dye is at least one of Rhodamine B, methylene blue, and Congo red. The water treatment is applicable to water bodies with a pH range of 3 to 11. The water body includes at least one of tap water, river water, and medical wastewater.