Preparation method and application of MOFs-based composite catalyst

Abstract

This invention relates to the field of composite catalyst technology, specifically to a method for preparing and applying a MOFs-based composite catalyst, comprising the following steps: dispersing modified MOFs and modified GO in a modified solvent, adding N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine; after the reaction, centrifuging to collect the precipitate, washing the precipitate with sufficient modified solvent and anhydrous ethanol, and finally washing with deionized water until the filtrate is clear to obtain a purified product; dispersing the purified product in methanol and refluxing to obtain the modified MOFs-based composite catalyst. This invention utilizes the bimetallic active sites of modified MOFs, the electronic conductivity of modified GO, and the uniformly dispersed structure formed with the assistance of the modified solvent to achieve a synergistic effect of adsorption-mass transfer-catalysis. The catalyst first rapidly adsorbs organic pollutant molecules through its porous structure, then achieves oxidative degradation of pollutants through efficient photogenerated carrier separation, and finally releases degradation products through unobstructed pores.

Description

Technical Field

[0001] This invention relates to the field of composite catalyst technology, specifically to a method for preparing MOFs-based composite catalysts and their applications. Background Technology

[0002] With the rapid development of industrial production, the discharge of organic wastewater has been increasing year by year. Among them, wastewater containing recalcitrant organic pollutants such as Rhodamine B, methyl orange, and tetracycline poses a serious threat to the ecological environment and human health due to its high toxicity and difficulty in degradation. Photocatalytic degradation technology has become an ideal choice for treating this type of organic wastewater due to its advantages such as being green and environmentally friendly and having no secondary pollution. MOFs-based composite catalysts have attracted much attention in the field of photocatalysis due to their high specific surface area, tunable pore structure, and abundant active sites. Traditional MOF-based catalysts often employ a single metal active site design, resulting in a rapid recombination rate of photogenerated electron-hole pairs, leading to low photocatalytic efficiency and difficulty in achieving rapid degradation of organic pollutants. Some composite catalysts combine MOFs with carbon materials through physical mixing, but the interfacial bonding between the two is weak, resulting in significant interfacial mass transfer resistance and inefficient transfer of photogenerated carriers, further reducing the interfacial efficiency of the catalytic reaction. Therefore, to address the problems mentioned above, this invention proposes a method for preparing MOF-based composite catalysts and their applications. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing MOFs-based composite catalysts and their applications, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a MOFs-based composite catalyst includes the following steps: S1. Disperse the modified MOFs and modified GO in the modified solvent, sonicate to form a uniform suspension, add N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine, stir at room temperature for 24-30 min under nitrogen protection, raise the temperature to 50-60℃, and continue stirring for 20-24 h. S2. After the reaction is complete, the precipitate is collected by centrifugation, washed with sufficient modified solvent and anhydrous ethanol, and finally washed with deionized water until the filtrate is clear to obtain the purified product. S3. The purified product was dispersed in methanol, refluxed, and then vacuum dried to obtain the modified MOFs-based composite catalyst. In step S1, the modified MOFs are prepared through the following steps; S11. Dissolve 2-aminoterephthalic acid in a mixture of modified solvent and methanol, sonicate, then add tetrabutyl titanate and ferric chloride hexahydrate, and stir to form a homogeneous solution. S12. React the homogeneous solution at 142-150℃ for 20-24h, cool naturally to room temperature, collect the precipitate by centrifugation, wash the precipitate with sufficient modified solvent and methanol respectively, and dry under vacuum to obtain doped MOFs. S13. Disperse the doped MOFs in the modified solvent, add pyromellitic methyl chloride and 4-dimethylaminopyridine, stir under nitrogen protection, collect the product by centrifugation, wash the product with sufficient modified solvent, wash with methanol, and vacuum dry to obtain modified MOFs.

[0005] Furthermore, the modified GO in step S1 is obtained through the following steps: S101. Disperse GO in deionized water, add concentrated nitric acid and concentrated sulfuric acid, stir at 0-2℃, add potassium permanganate, continue stirring for 2-3 hours, then raise the temperature to 35-40℃, stir for 1-2 hours, add hydrogen peroxide, centrifuge to collect the precipitate, wash with deionized water until the pH of the filtrate is 6-7, and vacuum dry to obtain carboxylated GO. S102. Disperse carboxylated GO in a modified solvent, add N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, stir at room temperature for 4-6 h under nitrogen protection to obtain activated GO dispersion; S103. Add 3-aminopropyltriethoxysilane to the activated GO dispersion, heat to 50-60℃ under nitrogen protection, and stir continuously for 12-16h. After the reaction is completed, collect the precipitate by centrifugation, wash the precipitate with sufficient DMF, wash with anhydrous ethanol, and vacuum dry to obtain modified GO.

[0006] Furthermore, the modified solvent in step S1 is prepared through the following steps: S1001. Mix N,N-dimethylformamide and ethylene glycol dimethyl ether and stir magnetically until homogeneous to obtain a basic mixed solvent; S1002. Add KH560 and p-toluenesulfonic acid catalyst to the basic mixed solvent, heat to 45-50℃ under nitrogen atmosphere, and stir at a constant temperature for 3-4 hours to form a modified system. S1003. After the reaction is complete, the modified system is cooled to room temperature, triethanolamine is added to neutralize the p-toluenesulfonic acid catalyst, and the mixture is stirred and filtered through an organic filter membrane to obtain the modified solvent.

[0007] Furthermore, in step S1, the mass ratio of modified MOFs to modified GO is (2-3):1, and the mass ratio of modified MOFs to the total amount of modified GO, modified solvent, N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1:(50-60):(0.6-0.9):(0.05-0.10).

[0008] Furthermore, in step S11, the mass ratio of 2-aminoterephthalic acid: tetrabutyl titanate: ferric chloride hexahydrate is 1:(2.0-3.0):(0.8-1.2), and the mass ratio of the total mass of the modified solvent and methanol mixture to the mass ratio of 2-aminoterephthalic acid is (40-50):1, wherein the mass ratio of the modified solvent to methanol is (3-4):1.

[0009] Furthermore, in step S13, the mass ratio of doped MOFs, pyromellitic trimethylol chloride, and 4-dimethylaminopyridine is 1:(1.5-2.0):(0.1-0.2), and the mass ratio of modified solvent to doped MOFs is (25-35):1.

[0010] Furthermore, in step S101, the mass ratio of GO, concentrated nitric acid, concentrated sulfuric acid, potassium permanganate, and hydrogen peroxide is 1:(15-20):(60-80):(1.0-1.5):(2.0-3.0).

[0011] Furthermore, in step S102, the mass ratio of carboxylated GO, N-hydroxysuccinimide, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1:(0.4-0.6):(0.8-1.2), and the mass ratio of modified solvent to carboxylated GO is (30-40):1. In step S103, the mass ratio of carboxylated GO to 3-aminopropyltriethoxysilane is 1:(0.5-0.8).

[0012] Furthermore, in step S1001, the mass ratio of N,N-dimethylformamide to ethylene glycol dimethyl ether is (7-9):(1-3), in step S1002, the mass ratio of the basic mixed solvent, KH560, and p-toluenesulfonic acid is 1:(0.005-0.012):(0.002-0.005), and the mass ratio of the basic mixed solvent to triethanolamine is 1:(0.001-0.003).

[0013] Furthermore, the application of the MOFs-based composite catalyst prepared according to any one of the preparation methods in the degradation of organic wastewater pollutants.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention eliminates the interfacial mass transfer resistance between modified MOFs and modified GO through covalent bonding. Photogenerated charge carriers can be rapidly transferred at the interface, allowing the catalytic reaction to proceed efficiently at the interface. The bimetallic active sites of modified MOFs, the electronic conductivity of modified GO, and the uniform dispersion structure formed with the help of modified solvents form a synergistic effect of adsorption-mass transfer-catalysis. The catalyst first rapidly adsorbs organic pollutant molecules through the porous structure, then achieves the oxidative degradation of pollutants through efficient photogenerated charge carrier separation, and finally releases degradation products through unobstructed pores. 2. This invention modifies the Ti and Fe bimetallic sites in MOFs to form synergistic photocatalytic centers, which can effectively absorb visible light and generate photogenerated electron-hole pairs. The layered structure of modified GO has excellent electronic conductivity, which can quickly capture the photogenerated electrons generated by MOFs, avoid the rapid recombination of electron-hole pairs, greatly improve the utilization rate of photogenerated carriers, and thus enhance the redox ability of the catalyst, achieving rapid degradation of organic pollutants such as Rhodamine B. Attached Figure Description

[0015] Figure 1 A schematic diagram of the preparation process of the modified MOFs-based composite catalyst; Figure 2 A schematic diagram of the process for modifying MOFs; Figure 3 A flowchart illustrating the process of modifying GO; Figure 4 A schematic diagram of the process for modifying solvents; Figure 5 The XRD phase analysis spectrum of the modified MOFs-based composite catalyst in Example 1 is shown below. Figure 6 Here is an electron microscope image of the modified GO in Example 1; Figure 7 Electron micrographs of the modified MOFs in Example 1; Figure 8 This is an electron microscope image of the modified MOFs-based composite catalyst in Example 1. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] Please see Figures 1-8 The present invention provides a technical solution: Example 1: A method for preparing a MOFs-based composite catalyst includes the following steps: S1001: Take 70g of N,N-dimethylformamide and 10g of ethylene glycol dimethyl ether, mix them, and stir magnetically for 10min until uniform to obtain the basic mixed solvent; S1002: Add 0.4g KH560 (γ-glycidyl etheroxypropyltrimethoxysilane) and 0.16g p-toluenesulfonic acid to the basic mixed solvent, heat to 45℃ under nitrogen atmosphere, and stir at a constant temperature for 3h to form a modified system. S1003: Cool the modified system to room temperature, add 0.08g of triethanolamine to neutralize the catalyst, stir for 10min, and filter through an organic filter membrane to obtain the modified solvent.

[0018] S11: Take 1g of 2-aminoterephthalic acid, dissolve it in a mixed solvent of 30g of modified solvent and 10g of methanol, sonicate for 8min, add 2.0g of tetrabutyl titanate and 0.8g of ferric chloride hexahydrate, stir for 25min to form a homogeneous solution. S12: The homogeneous solution was reacted at 142℃ for 20h, naturally cooled to room temperature, the precipitate was collected by centrifugation, the precipitate was washed 3 times with modified solvent and methanol respectively, and dried under vacuum at 55℃ for 4h to obtain doped MOFs. S13: Take 1g of the above-mentioned doped MOFs, disperse them in 25g of modified solvent, add 1.5g of trimesoyl chloride and 0.1g of 4-dimethylaminopyridine, stir at 50℃ for 10h under nitrogen protection, collect the product by centrifugation, wash 3 times with modified solvent and 2 times with methanol, and dry under vacuum at 74℃ for 8h to obtain modified MOFs.

[0019] S101: Take 1g of GO, disperse it in 120g of deionized water, add 15g of concentrated nitric acid and 60g of concentrated sulfuric acid, stir at 0℃ for 30min, add 1.0g of potassium permanganate, continue stirring for 2h, then raise the temperature to 35℃, stir for 1h, add 2.0g of hydrogen peroxide, centrifuge to collect the precipitate, wash with deionized water until the pH of the filtrate is 6, and vacuum dry at 60℃ for 8h to obtain carboxylated GO; S102: Take 1g of the above carboxylated GO, disperse it in 30g of modified solvent, add 0.4g of N-hydroxysuccinimide and 0.8g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, stir at room temperature for 4h under nitrogen protection to obtain activated GO dispersion; S103: Add 0.5g of 3-aminopropyltriethoxysilane to the activated GO dispersion, heat to 50℃ under nitrogen protection, and stir continuously for 12h. After the reaction is completed, collect the precipitate by centrifugation, wash 3 times with DMF and 2 times with anhydrous ethanol, and dry under vacuum at 70℃ for 8h to obtain modified GO.

[0020] S1: Take 2g of modified MOFs and 1g of modified GO and disperse them in 150g of modified solvent. Sonicate for 25min to form a uniform suspension. Add 1.8g of N,N'-dicyclohexylcarbodiimide and 0.15g of 4-dimethylaminopyridine. Stir at room temperature for 24min under nitrogen protection. Heat to 50℃ and continue stirring for 20h. S2: After the reaction is complete, the precipitate is collected by centrifugation, washed 3 times with modified solvent, washed 3 times with anhydrous ethanol, and finally washed with deionized water until the filtrate is clear to obtain the purified product. S3: The purified product was dispersed in methanol, refluxed at 54°C for 1 h, and vacuum dried at 73°C for 10 h to obtain the modified MOFs-based composite catalyst.

[0021] Example 2: A method for preparing a MOFs-based composite catalyst includes the following steps: S1001: Take 75g of N,N-dimethylformamide and 15g of ethylene glycol dimethyl ether, mix them, and stir magnetically for 12min until uniform to obtain the basic mixed solvent; S1002: Add 0.72g KH560 and 0.27g p-toluenesulfonic acid to the basic mixed solvent, heat to 47℃ under nitrogen atmosphere, and stir at a constant temperature for 3.5h to form a modified system; S1003: Cool the modified system to room temperature, add 0.18g of triethanolamine to neutralize the catalyst, stir for 10min, and filter through an organic filter membrane to obtain the modified solvent.

[0022] S11: Take 1g of 2-aminoterephthalic acid, dissolve it in a mixed solvent of 33.75g of modified solvent and 11.25g of methanol, sonicate for 10min, add 2.25g of tetrabutyl titanate and 0.9g of ferric chloride hexahydrate, stir for 27min to form a homogeneous solution. S12: The homogeneous solution was reacted at 145℃ for 22h, naturally cooled to room temperature, the precipitate was collected by centrifugation, the precipitate was washed 3 times with modified solvent and methanol respectively, and dried under vacuum at 57℃ for 5h to obtain doped MOFs. S13: Take 1g of the above-mentioned doped MOFs, disperse them in 28g of modified solvent, add 1.65g of trimesoyl chloride and 0.13g of 4-dimethylaminopyridine, stir at 54℃ for 10.7h under nitrogen protection, collect the product by centrifugation, wash 3 times with modified solvent and 2 times with methanol, and dry under vacuum at 76℃ for 8.8h to obtain modified MOFs.

[0023] S101: Take 1g of GO, disperse it in 130g of deionized water, add 17g of concentrated nitric acid and 68g of concentrated sulfuric acid, stir at 1℃ for 32min, add 1.2g of potassium permanganate, continue stirring for 2.5h, then raise the temperature to 37℃, stir for 1.5h, add 2.4g of hydrogen peroxide, centrifuge to collect the precipitate, wash with deionized water until the pH of the filtrate is 6.5, and vacuum dry at 62℃ for 9h to obtain carboxylated GO; S102: Take 1g of the above carboxylated GO, disperse it in 33g of modified solvent, add 0.48g of N-hydroxysuccinimide and 0.95g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, stir at room temperature for 5h under nitrogen protection to obtain activated GO dispersion; S103: Add 0.6 g of 3-aminopropyltriethoxysilane to the activated GO dispersion, heat to 53 °C under nitrogen protection, and stir continuously for 14 h. After the reaction is complete, collect the precipitate by centrifugation, wash 3 times with DMF and 2 times with anhydrous ethanol, and dry under vacuum at 72 °C for 9 h to obtain modified GO.

[0024] S1: Take 2.2g of modified MOFs and 1g of modified GO and disperse them in 160g of modified solvent. Sonicate for 27min to form a uniform suspension. Add 2.04g of N,N'-dicyclohexylcarbodiimide and 0.18g of 4-dimethylaminopyridine. Stir at room temperature for 27min under nitrogen protection. Heat to 53℃ and continue stirring for 22h. S2: After the reaction is complete, the precipitate is collected by centrifugation, washed 3 times with modified solvent, washed 2 times with anhydrous ethanol, and finally washed with deionized water until the filtrate is clear to obtain the purified product. S3: The purified product was dispersed in methanol, refluxed at 56°C for 1.5 h, and vacuum dried at 75°C for 11 h to obtain the modified MOFs-based composite catalyst.

[0025] Example 3: A method for preparing a MOFs-based composite catalyst includes the following steps: S1001: Take 80g of N,N-dimethylformamide and 20g of ethylene glycol dimethyl ether, mix them, and stir magnetically for 13min until homogeneous to obtain the basic mixed solvent; S1002: Add 0.9g KH560 and 0.35g p-toluenesulfonic acid to the basic mixed solvent, heat to 48℃ under nitrogen atmosphere, and stir at a constant temperature for 3.6h to form a modified system; S1003: Cool the modified system to room temperature, add 0.25g of triethanolamine to neutralize the catalyst, stir for 10min, and filter through an organic filter membrane to obtain the modified solvent.

[0026] S11: Take 1g of 2-aminoterephthalic acid, dissolve it in a mixed solvent of 36g of modified solvent and 12g of methanol, sonicate for 11min, add 2.7g of tetrabutyl titanate and 1.1g of ferric chloride hexahydrate, stir for 28min to form a homogeneous solution. S12: The homogeneous solution was reacted at 148℃ for 23h, naturally cooled to room temperature, the precipitate was collected by centrifugation, the precipitate was washed 4 times with modified solvent and methanol respectively, and vacuum dried at 58℃ for 5.5h to obtain doped MOFs. S13: Take 1g of the above-mentioned doped MOFs, disperse them in 32g of modified solvent, add 1.85g of trimesoyl chloride and 0.18g of 4-dimethylaminopyridine, stir at 58℃ for 11.6h under nitrogen protection, collect the product by centrifugation, wash 4 times with modified solvent and 3 times with methanol, and dry under vacuum at 78℃ for 9.5h to obtain modified MOFs.

[0027] S101: Take 1g of GO, disperse it in 140g of deionized water, add 18g of concentrated nitric acid and 75g of concentrated sulfuric acid, stir at 1℃ for 34min, add 1.4g of potassium permanganate, continue stirring for 2.8h, then raise the temperature to 39℃, stir for 1.8h, add 2.8g of hydrogen peroxide, centrifuge to collect the precipitate, wash with deionized water until the pH of the filtrate is 6.8, and vacuum dry at 64℃ for 9.5h to obtain carboxylated GO; S102: Take 1g of the above carboxylated GO, disperse it in 38g of modified solvent, add 0.55g of N-hydroxysuccinimide and 1.1g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, stir at room temperature for 5.5h under nitrogen protection to obtain activated GO dispersion; S103: Add 0.75g of 3-aminopropyltriethoxysilane to the activated GO dispersion, heat to 58℃ under nitrogen protection, and stir continuously for 15h. After the reaction is completed, collect the precipitate by centrifugation, wash 3 times with DMF and 2 times with anhydrous ethanol, and dry under vacuum at 74℃ for 9.5h to obtain modified GO.

[0028] S1: Take 2.8g of modified MOFs and 1g of modified GO and disperse them in 209g of modified solvent. Sonicate for 29min to form a uniform suspension. Add 2.4g of N,N'-dicyclohexylcarbodiimide and 0.28g of 4-dimethylaminopyridine. Stir at room temperature for 29min under nitrogen protection. Raise the temperature to 58℃ and continue stirring for 23h. S2: After the reaction is complete, the precipitate is collected by centrifugation, washed 4 times with modified solvent, washed 3 times with anhydrous ethanol, and finally washed with deionized water until the filtrate is clear to obtain the purified product. S3: The purified product was dispersed in methanol, refluxed at 59°C for 1.8 h, and vacuum dried at 78°C for 11.5 h to obtain the modified MOFs-based composite catalyst.

[0029] Example 4: A method for preparing a MOFs-based composite catalyst includes the following steps: S1001: Take 90g of N,N-dimethylformamide and 30g of ethylene glycol dimethyl ether, mix them, and stir magnetically for 15min until homogeneous to obtain the basic mixed solvent; S1002: Add 1.44g KH560 and 0.6g p-toluenesulfonic acid to the basic mixed solvent, heat to 50℃ under nitrogen atmosphere, and stir at a constant temperature for 4h to form a modified system; S1003: Cool the modified system to room temperature, add 0.36g of triethanolamine to neutralize the catalyst, stir for 10min, and filter through an organic filter membrane to obtain the modified solvent.

[0030] S11: Take 1g of 2-aminoterephthalic acid, dissolve it in a mixed solvent of 37.5g of modified solvent and 12.5g of methanol, sonicate for 12min, add 3g of tetrabutyl titanate and 1.2g of ferric chloride hexahydrate, stir for 30min to form a homogeneous solution; S12: The homogeneous solution was reacted at 150℃ for 24h, naturally cooled to room temperature, the precipitate was collected by centrifugation, the precipitate was washed 4 times with modified solvent and methanol respectively, and dried under vacuum at 60℃ for 6h to obtain doped MOFs. S13: Take 1g of the above-mentioned doped MOFs, disperse them in 35g of modified solvent, add 2g of trimesoyl chloride and 0.2g of 4-dimethylaminopyridine, stir at 60℃ for 12h under nitrogen protection, collect the product by centrifugation, wash 4 times with modified solvent and 3 times with methanol, and dry under vacuum at 80℃ for 8h to obtain modified MOFs.

[0031] S101: Take 1g of GO, disperse it in 150g of deionized water, add 20g of concentrated nitric acid and 80g of concentrated sulfuric acid, stir at 2℃ for 35min, add 1.5g of potassium permanganate, continue stirring for 3h, then raise the temperature to 40℃, stir for 2h, add 3g of hydrogen peroxide, centrifuge to collect the precipitate, wash with deionized water until the pH of the filtrate is 7, and vacuum dry at 65℃ for 10h to obtain carboxylated GO; S102: Take 1g of the above carboxylated GO, disperse it in 40g of modified solvent, add 0.6g of N-hydroxysuccinimide and 1.2g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, stir at room temperature for 6h under nitrogen protection to obtain activated GO dispersion; S103: Add 0.8 g of 3-aminopropyltriethoxysilane to the activated GO dispersion, heat to 60 °C under nitrogen protection, and stir continuously for 16 h. After the reaction is complete, collect the precipitate by centrifugation, wash 4 times with DMF, wash 3 times with anhydrous ethanol, and dry under vacuum at 75 °C for 10 h to obtain modified GO.

[0032] S1: Take 3g of modified MOFs and 1g of modified GO and disperse them in 240g of modified solvent. Sonicate for 30min to form a uniform suspension. Add 3.6g of N,N'-dicyclohexylcarbodiimide and 0.4g of 4-dimethylaminopyridine. Stir at room temperature for 30min under nitrogen protection. Heat to 60℃ and continue stirring for 24h. S2: After the reaction is complete, the precipitate is collected by centrifugation, washed 4 times with modified solvent, washed 3 times with anhydrous ethanol, and finally washed with deionized water until the filtrate is clear to obtain the purified product. S3: The purified product was dispersed in methanol, refluxed at 60°C for 2 h, and vacuum dried at 80°C for 12 h to obtain the modified MOFs-based composite catalyst.

[0033] Comparative Example 1 Comparative Example 1 differs from Example 1 in that the modified MOFs are replaced with NH2-MIL-125(Ti), and the remaining steps are exactly the same as in Example 1.

[0034] Comparative Example 2 Comparative Example 2 differs from Example 1 in that the modified GO is replaced with graphene oxide, while the remaining steps are exactly the same as in Example 1.

[0035] Comparative Example 3 Comparative Example 3 differs from Example 1 in that the modified solvent is replaced with an N,N-dimethylformamide solution, and the remaining steps are exactly the same as in Example 1.

[0036] Seven different composite catalysts were prepared using Examples 1-4 and Comparative Examples 1-3. 50 mL of 50 mg / L Rhodamine B simulated wastewater was placed in a 100 mL stoppered conical flask. The pH of the wastewater was adjusted to 7 with HCl / NaOH. 20 mg of the composite catalyst to be tested was added. The flask was placed in a thermostatic magnetic stirrer (300 r / min, 25 °C) under dark conditions and stirred. 5 mL samples were taken at 0, 10, 20, 30, 40, 50, and 60 min, filtered through a 0.22 μm filter membrane, and the absorbance was measured at the maximum absorption wavelength of Rhodamine B (554 nm) using a UV-Vis spectrophotometer. After adsorption equilibrium was reached, the conical flask was placed in a photochemical reactor (300W xenon lamp, filtering out λ<420nm ultraviolet light, simulating visible light, with the light source 15cm above the liquid surface). The stirring (300r / min) and the light source were turned on to start the photocatalytic degradation reaction. During the reaction, 5mL samples were taken at 0, 10, 20, 30, 40, 50, and 60min, filtered through a 0.22μm filter membrane, and the absorbance at the corresponding wavelength was measured. The mass concentration of pollutants at each time point was calculated according to the Lambert-Beer law. The specific test results are shown in Tables 1 and 2 below. Table 1 Table 2 As can be seen from the data in Tables 1 and 2, the composite catalysts prepared in Examples 1-4 all exhibited highly efficient degradation effects. With the progress of the photocatalytic reaction, the absorbance and pollutant concentration of Rhodamine B showed a rapid decreasing trend. After 60 min of reaction, the pollutant concentration in Example 1 was only 1.54 mg / L. Examples 2 and 3 showed better degradation performance, with pollutant concentrations as low as 0.91 mg / L and 0.72 mg / L, respectively, after 60 min. The pollutant concentration in Example 4 was 1.30 mg / L. The catalysts in Examples 1-4 could achieve rapid degradation of Rhodamine B within the first 30 min of reaction, and the pollutant concentration dropped to below 12 mg / L after 30 min. In contrast, the pollutant concentration in Comparative Examples 1-3 was still above 28 mg / L after 30 min. This indicates that the composite catalyst prepared in this invention can effectively accelerate the photocatalytic reaction rate, improve the degradation efficiency of organic pollutants, and is more suitable for the rapid treatment of organic wastewater. Comparing the test data of the examples and the comparative examples, the concentration of Rhodamine B in the catalysts of Comparative Examples 1-3 decreased significantly slower within the same reaction time. After 60 min of reaction, the pollutant concentrations of Comparative Examples 1, 2, and 3 were still as high as 19.48 mg / L, 18.02 mg / L, and 23.45 mg / L, respectively, which were much higher than those of the examples. This indicates that the present invention can significantly improve the photocatalytic degradation ability of the composite catalyst by specifically modifying MOFs and GO and using a modified composite solvent preparation process. In contrast, replacing unmodified MOFs, GO, or a single solvent will reduce the catalytic performance of the catalyst.

[0037] Figure 5The XRD phase analysis spectrum of the modified MOFs-based composite catalyst in Example 1 shows a series of sharp and high-intensity characteristic diffraction peaks at 7°, which are characteristic of the crystal structure of the modified MOFs material, indicating that it has good crystallinity and an ordered pore structure. A weak broadened diffraction peak appears near 10°, corresponding to the characteristic peak of the interlayer stacking of modified GO, indicating that the interlayer interaction force of modified GO is weakened and the crystallinity is reduced. The spectrum retains all the main characteristic peaks of the modified MOFs, and the peak positions and shapes are basically consistent, while also including the modified... The faint characteristic peaks of GO directly prove that the two materials were successfully composited, and the crystal structure of the modified MOFs was well maintained during the composite process. The intensity of the characteristic peaks of the modified MOFs of the composite catalyst decreased slightly, but the peak shape was still clear, indicating that the introduction of modified GO did not destroy the crystal framework of the modified MOFs, but only affected its long-range order to a certain extent. The characteristic peaks of modified GO were almost masked after composite because the modified GO was highly dispersed in the modified MOFs matrix in the form of ultrathin sheets, and its interlayer stacking was further destroyed, resulting in a weakening of the diffraction signal.

[0038] Figure 6 The image shows an electron microscope image of the modified GO in Example 1. The modified GO exhibits a layered structure with well-developed and flexible sheets, without obvious agglomeration or clumping. This indicates that after carboxylation, silanization modification, and solvent dispersion treatment, the interlayer forces of the modified GO are effectively weakened, and its dispersibility is significantly improved. This is the structural basis for its ability to achieve uniform composite with modified MOFs. The edges of the modified GO sheets exhibit irregular curling and wrinkling, and there are a small number of mesoporous structures on the sheets. This structural feature increases the specific surface area of ​​the modified GO, providing more active sites for subsequent covalent bonding with modified MOFs. On the other hand, it also provides unobstructed channels for pollutant adsorption and mass transfer during the photocatalytic process, matching the synergistic design of adsorption-mass transfer-catalysis.

[0039] Figure 7 The image shows an electron microscope (EM) image of the modified MOFs in Example 1. The modified MOFs exhibit a uniform nanorod-like morphology with particle sizes ranging from tens to hundreds of nanometers. The overall morphology is regular, without obvious deformities or agglomerates. This indicates that the modification process did not destroy the intrinsic crystal structure of the modified MOFs, but instead helped to form uniformly sized nanocrystals, providing a good structural basis for subsequent composite with modified GO. The sample as a whole shows a dense but relatively uniform particle packing, without large-area hard agglomeration or melting sintering. This shows that the modification process effectively controlled the nucleation and growth of the modified MOFs, ensuring their dispersion and facilitating the formation of a continuous electron transport network in the composite catalyst.

[0040] Figure 8The image shows an electron microscope (EMS) image of the modified MOFs-based composite catalyst in Example 1. The two-dimensional lamellar wrinkled structure of modified GO and the nanorod / nanoparticle morphology of modified MOFs clearly coexist. The modified MOF particles are not simply physically mixed, but rather uniformly attached to and grown on the surface and edges of the modified GO sheets, forming a typical composite structure of sheet-loaded particles. The modified MOF particles are uniformly distributed on the modified GO sheets, without large-area aggregation or detachment, indicating a strong interfacial interaction (such as covalent bonds, hydrogen bonds, or electrostatic interactions). This tight bond is a solid... The modified GO sheets maintain good flexibility and layered structure, without significant breakage or stacking during the composite process, ensuring efficient electron transport and suppressing photogenerated carrier recombination. The modified MOF particles also retain their intrinsic nano-morphology, indicating that the composite process conditions are mild and effectively protect the structural integrity of both materials. The wrinkles between the sheets and the accumulation between the particles form a rich hierarchical porous structure, which not only increases the overall specific surface area but also provides ample space for the adsorption, mass transfer, and catalytic reactions of the reactants, aligning with the design concept of synergistic adsorption-mass transfer-catalysis.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a MOFs-based composite catalyst, characterized in that, Includes the following steps: S1. Disperse the modified MOFs and modified GO in the modified solvent, sonicate to form a uniform suspension, add N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine, stir at room temperature for 24-30 min under nitrogen protection, raise the temperature to 50-60℃, and continue stirring for 20-24 h. S2. After the reaction is complete, the precipitate is collected by centrifugation, washed with sufficient modified solvent and anhydrous ethanol, and finally washed with deionized water until the filtrate is clear to obtain the purified product. S3. The purified product was dispersed in methanol, refluxed, and then vacuum dried to obtain the modified MOFs-based composite catalyst. In step S1, the modified MOFs are prepared through the following steps; S11. Dissolve 2-aminoterephthalic acid in a mixture of modified solvent and methanol, sonicate, then add tetrabutyl titanate and ferric chloride hexahydrate, and stir to form a homogeneous solution. S12. React the homogeneous solution at 142-150℃ for 20-24h, cool naturally to room temperature, collect the precipitate by centrifugation, wash the precipitate with sufficient modified solvent and methanol respectively, and dry under vacuum to obtain doped MOFs. S13. Disperse the doped MOFs in the modified solvent, add pyromellitic methyl chloride and 4-dimethylaminopyridine, stir under nitrogen protection, collect the product by centrifugation, wash the product with sufficient modified solvent, wash with methanol, and vacuum dry to obtain modified MOFs.

2. The method for preparing a MOFs-based composite catalyst according to claim 1, characterized in that, The modified GO in step S1 is obtained through the following steps: S101. Disperse GO in deionized water, add concentrated nitric acid and concentrated sulfuric acid, stir at 0-2℃, add potassium permanganate, continue stirring for 2-3 hours, then raise the temperature to 35-40℃, stir for 1-2 hours, add hydrogen peroxide, centrifuge to collect the precipitate, wash with deionized water until the pH of the filtrate is 6-7, and vacuum dry to obtain carboxylated GO. S102. Disperse carboxylated GO in a modified solvent, add N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, stir at room temperature for 4-6 h under nitrogen protection to obtain activated GO dispersion; S103. Add 3-aminopropyltriethoxysilane to the activated GO dispersion, heat to 50-60℃ under nitrogen protection, and stir continuously for 12-16h. After the reaction is completed, collect the precipitate by centrifugation, wash the precipitate with sufficient DMF, wash with anhydrous ethanol, and vacuum dry to obtain modified GO.

3. The method for preparing a MOFs-based composite catalyst according to claim 1, characterized in that, The modified solvent in step S1 is obtained through the following steps: S1001. Mix N,N-dimethylformamide and ethylene glycol dimethyl ether and stir magnetically until homogeneous to obtain a basic mixed solvent; S1002. Add KH560 and p-toluenesulfonic acid catalyst to the basic mixed solvent, heat to 45-50℃ under nitrogen atmosphere, and stir at a constant temperature for 3-4 hours to form a modified system. S1003. After the reaction is complete, the modified system is cooled to room temperature, triethanolamine is added to neutralize the p-toluenesulfonic acid catalyst, and the mixture is stirred and filtered through an organic filter membrane to obtain the modified solvent.

4. The method for preparing a MOFs-based composite catalyst according to claim 1, characterized in that, In step S1, the mass ratio of modified MOFs to modified GO is (2-3):1, and the mass ratio of modified MOFs to the total amount of modified GO, modified solvent, N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1:(50-60):(0.6-0.9):(0.05-0.10).

5. The method for preparing a MOFs-based composite catalyst according to claim 1, characterized in that, In step S11, the mass ratio of 2-aminoterephthalic acid: tetrabutyl titanate: ferric chloride hexahydrate is 1:(2.0-3.0):(0.8-1.2), and the mass ratio of the total mass of the modified solvent and methanol mixture to the mass ratio of 2-aminoterephthalic acid is (40-50):1, wherein the mass ratio of the modified solvent to methanol is (3-4):

1.

6. The method for preparing a MOFs-based composite catalyst according to claim 1, characterized in that, In step S13, the mass ratio of doped MOFs, trimesoyl chloride, and 4-dimethylaminopyridine is 1:(1.5-2.0):(0.1-0.2), and the mass ratio of modified solvent to doped MOFs is (25-35):

1.

7. The method for preparing a MOFs-based composite catalyst according to claim 2, characterized in that, In step S101, the mass ratio of GO, concentrated nitric acid, concentrated sulfuric acid, potassium permanganate, and hydrogen peroxide is 1:(15-20):(60-80):(1.0-1.5):(2.0-3.0).

8. The method for preparing a MOFs-based composite catalyst according to claim 2, characterized in that, In step S102, the mass ratio of carboxylated GO, N-hydroxysuccinimide, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1:(0.4-0.6):(0.8-1.2), and the mass ratio of modified solvent to carboxylated GO is (30-40):

1. In step S103, the mass ratio of carboxylated GO to 3-aminopropyltriethoxysilane is 1:(0.5-0.8).

9. The method for preparing a MOFs-based composite catalyst according to claim 3, characterized in that, In step S1001, the mass ratio of N,N-dimethylformamide to ethylene glycol dimethyl ether is (7-9):(1-3). In step S1002, the mass ratio of the basic mixed solvent, KH560, and p-toluenesulfonic acid is 1:(0.005-0.012):(0.002-0.005). The mass ratio of the basic mixed solvent to triethanolamine is 1:(0.001-0.003).

10. The application of the MOFs-based composite catalyst prepared by any one of claims 1-9 in the degradation of organic wastewater pollutants.

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