High-stability catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a high-stability catalyst as well as a preparation method and application thereof. The high-stability catalyst comprises an internal catalyst component and a polyimide film coated outside the catalyst. The preparation method comprises the following steps: reacting a heterogeneous catalyst with a dianhydride monomer solution, adding a diamine monomer solution, and carrying out a polymerization reaction to obtain a polyamide acid film packaged heterogeneous catalyst; and adding an organic solvent into the polyamide acid film packaged catalyst, then adding a dehydrating agent, and carrying out imidization reaction under an alkaline condition to obtain the polyimide film packaged heterogeneous catalyst. After the heterogeneous catalyst is packaged by a polyimide film, the leaching of metal ions in heterogeneous Fenton reaction is obviously inhibited, the stability is greatly improved, and the heterogeneous catalyst shows excellent catalytic degradation activity of organic matters.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a highly stable catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] The Fenton oxidation technology plays an important role in the field of water treatment. Its essence is a chain reaction between ferrous ions and hydrogen peroxide to generate hydroxyl radicals. Hydroxyl radicals have strong oxidation ability, and their oxidation potential is second only to fluorine, reaching as high as 2.80 V. In addition, hydroxyl radicals have a very high electronegativity or electrophilicity, with an electron affinity as high as 569.3 kJ, and have strong addition reaction characteristics. Therefore, the Fenton reagent can oxidize most organic substances in water without selectivity, and is particularly suitable for the oxidation treatment of organic wastewater that is difficult to degrade biologically or is difficult to achieve by general chemical oxidation. However, a large amount of iron sludge after the reaction belongs to hazardous solid waste, which leads to secondary pollution and additional disposal costs, greatly limiting the application of Fenton oxidation. Therefore, the heterogeneous Fenton oxidation technology based on heterogeneous Fenton catalysts can avoid the above-mentioned shortcomings in principle, but there are still certain challenges in practical applications.

[0003] On the one hand, the activity of the catalyst is often positively correlated with the leaching amount of metal ions. Existing catalysts have problems such as easy leaching of metal ions, easy decline in activity and stability, and easy secondary pollution in practical applications. Chinese invention patent CN118698549A provides a nickel-cobalt acetate-based hydroxide Fenton catalyst, a preparation method thereof, and an application thereof. The preparation method includes the following steps: under stirring at 80°C - 90°C, mixing a polyvinylpyrrolidone solution and a nickel-cobalt solution, aging for 15 - 20 h, separating, washing, and drying to obtain a nickel-cobalt precursor, and then calcining in an oxygen-containing atmosphere at 200°C - 300°C for 1 - 3 h to obtain a nickel-cobalt acetate-based hydroxide Fenton catalyst. Although the prepared catalyst has more exposed catalytic active sites, it does not solve the stability problem of the catalyst.

[0004] On the other hand, since the heterogeneous reactor is mainly fluidized bed, the density or suspension ability of the catalyst has a significant impact on energy consumption. In recent years, attempts in this regard include optimizing the physical and chemical properties of the catalyst, such as changing the surface structure and pore size of the catalyst; optimizing the reaction conditions, such as adjusting reaction temperature, pressure, and other conditions to improve catalytic performance. Chinese invention patent CN105568343A discloses a method and application for preparing an iron oxide ceramic film-like Fenton catalyst on the surface of a titanium alloy by plasma electrolytic oxidation. The method includes the following steps: First, pretreatment of the titanium alloy surface; Second, placing the polished titanium alloy obtained in the first step in the electrolyte in a stainless steel electrolytic cell, connecting it to the positive electrode of the power supply as the anode; The stainless steel electrolytic cell is connected to the negative electrode of the power supply as the cathode; Third, using a square wave power supply for reaction to obtain an iron oxide ceramic film-like Fenton catalyst. It can be seen that it forms an iron oxide ceramic film on the surface of the catalyst by electrolytic oxidation reaction. However, in actual applications, due to its highly ordered and complex internal structure, poor mechanical stability and chemical stability, and its corresponding high preparation difficulty and cost, it is difficult to be further applied. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the first object of the present invention is to provide a highly stable catalyst.

[0006] The second object of the present invention is to provide a preparation method of the above-mentioned highly stable catalyst. The present invention generates a polyamic acid film on the surface of the catalyst through the polymerization reaction of dianhydride and diamine, and converts the polyamic acid film into a more stable polyimide film through thermal imidization, effectively improving the stability of the heterogeneous Fenton catalyst.

[0007] The third object of the present invention is to provide the application of the above-mentioned highly stable catalyst and the highly stable catalyst prepared by the above-mentioned preparation method in the treatment of polluted water.

[0008] To achieve the above objects, the present invention adopts the following technical solutions:

[0009] On the one hand, the present invention provides a highly stable catalyst, including a Fenton catalyst and a polyimide film coated on the outside of the Fenton catalyst.

[0010] Preferably, the Fenton catalyst is a heterogeneous Fenton catalyst.

[0011] Preferably, the Fenton catalyst is selected from iron-based Fenton catalysts.

[0012] As an example of the present invention, the Fenton catalyst is a heterogeneous iron-based Fenton catalyst.

[0013] More preferably, the iron-based Fenton catalyst is selected from FeOOH, Fe 3 O4 , FeOCl, FeO, Fe 2 O 3 or at least one of elemental Fe, more preferably FeOOH.

[0014] Preferably, and as an example of the present invention, the particle size distribution of the Fenton catalyst is 10 nm - 10 μm.

[0015] Preferably, the polyimide film is obtained by condensation polymerization of a polyamine and a dianhydride.

[0016] Preferably, the dianhydride is selected from at least one of pyromellitic dianhydride (abbreviated as PMDA), 3,3’,4,4’-biphenyltetracarboxylic dianhydride (abbreviated as BPDA), benzophenone tetracarboxylic dianhydride (abbreviated as BTDA), hexafluorodiacid dianhydride (abbreviated as 6FDA), diphenyl ether tetracarboxylic dianhydride (abbreviated as ODPA), and bisphenol A type diether dianhydride (abbreviated as BPADA).

[0017] More preferably, and as an example of the present invention, the dianhydride is hexafluorodiacid dianhydride.

[0018] The chemical formula of pyromellitic dianhydride is as follows:

[0019]

[0020] The chemical formula of 3,3’,4,4’-biphenyltetracarboxylic dianhydride is as follows:

[0021]

[0022] The chemical formula of benzophenone tetracarboxylic dianhydride is as follows:

[0023]

[0024] The chemical formula of hexafluorodiacid dianhydride is as follows:

[0025]

[0026] The chemical formula of diphenyl ether tetracarboxylic dianhydride is as follows:

[0027]

[0028] The chemical formula of bisphenol A type diether dianhydride is as follows:

[0029]

[0030] Preferably, the polyamine is selected from at least one of tetrakis(4-aminophenyl)methane (abbreviated as TAM), 1,3,5-tris(4-aminophenyl)benzene (abbreviated as TAPB), and tris(2-aminoethyl)amine (abbreviated as 3N). More preferably, the polyamine is selected from tetrakis(4-aminophenyl)methane.

[0031] On the other hand, the present invention provides a method for preparing the above-mentioned highly stable catalyst, and the preparation method includes the following steps:

[0032] (1) Mix a dianhydride solution, a polyamine solution and a Fenton catalyst, and add a non-solvent to obtain an intermediate wrapped with a polyamic acid film;

[0033] (2) Subject the intermediate obtained in step (1) to thermal imidization treatment to obtain a highly stable catalyst encapsulated with a polyimide film.

[0034] Preferably, in step (1), the solvent of the dianhydride solution is selected from at least one of dimethylformamide (abbreviation: DMF), dimethyl sulfoxide (abbreviation: DMSO), dichloromethane (abbreviation: DCM), dichloroethane (abbreviation: EDC), chloroform (abbreviation: TCM), ethyl acetate (abbreviation: EAC), ethanol (abbreviation: EtOH), and acetone (abbreviation: ACE), and more preferably dichloromethane.

[0035] Preferably, in step (1), the solvent of the polyamine solution is selected from at least one of dimethylformamide, dimethyl sulfoxide, dichloromethane, dichloroethane, chloroform, ethyl acetate, ethanol, and acetone, and more preferably dimethylformamide.

[0036] Preferably, in step (1), the non-solvent is selected from at least one of petroleum ether, n-hexane, n-heptane, n-pentane, n-octane, and cyclohexane. Further preferably, the non-solvent is selected from at least one of petroleum ether and n-hexane.

[0037] Preferably, in step (1), the concentration of the dianhydride solution is 0.5 - 4.5 mg / mL, more preferably 1.5 - 3.5 mg / mL, and still more preferably 2.5 mg / mL.

[0038] Preferably, in step (1), the concentration of the polyamine solution is 10 - 25 mg / mL, more preferably 15 - 20 mg / mL, and still more preferably 17.5 mg / mL.

[0039] Preferably, in step (1), the mass ratio of the dianhydride solution, the polyamine solution, the catalyst and the non-solvent is 10 - 20:0.1 - 5:0.1 - 5:50 - 100; more preferably 16:1:1:80.

[0040] Preferably, in step (1), the mixing method is to first mix the catalyst with the dianhydride solution, and then add the polyamine solution and mix well.

[0041] Preferably, the catalyst is first stirred and ultrasonically treated with the dianhydride solution at -5°C to 5°C, and then the polyamine solution is added and stirred for 1 - 5 min. Further preferably, the polyamine solution is added and stirred for 3 - 4 min.

[0042] Preferably, in step (1), the polymerization time is 1 - 6 min. More preferably, the polymerization time is 3 - 6 min.

[0043] Preferably, in step (1), after polymerization, a post-treatment step is further included. More preferably, the post-treatment includes washing and drying.

[0044] Preferably, in step (2), the thermal imidization treatment includes the following steps: mixing the intermediate obtained in step (1) with a solvent and a dehydrating agent, and carrying out a reaction.

[0045] More preferably, the solvent is dimethylformamide.

[0046] More preferably, the dehydrating agent is at least one of propionic anhydride, butyric anhydride and acetic anhydride. Most preferably, the dehydrating agent is acetic anhydride.

[0047] More preferably, the reaction is carried out at 10°C - 40°C in an alkaline environment, and the reaction time is 1 - 3 h. Most preferably, the reaction is carried out at room temperature in an alkaline environment, and the reaction time is 2 h.

[0048] More preferably, the alkaline environment is provided by an alkaline substance. Even more preferably, the alkaline substance is selected from at least one of triethylamine, tripropylamine, diethylamine and anhydrous potassium carbonate.

[0049] More preferably, the mass ratio of the catalyst in step (1) to the polyamic acid, dehydrating agent and alkaline substance in step (2) is 1:5 - 70:1 - 10:0.1 - 5. Even more preferably, the mass ratio of the catalyst in step (1) to the polyamic acid, dehydrating agent and alkaline substance in step (2) is 1:20 - 40:3 - 6:1 - 2.

[0050] More preferably, after the reaction, a post-treatment is further included. Even more preferably, the post-treatment includes washing and drying.

[0051] Finally, the present invention provides the application of the above preparation method in improving the stability of the catalyst.

[0052] The present invention utilizes non-solvent induced phase separation to concentrate and rapidly polymerize diamine and dianhydride monomers to encapsulate the catalyst. In this method, the polymer coating can rapidly and effectively wrap the catalyst surface, preventing the leaching of metal ions, thereby improving the stability of the catalyst. Especially polyamic acid and its derivative polyimide, due to their excellent chemical stability and mechanical properties, can be reused multiple times and are ideal encapsulation materials.

[0053] The present invention proposes a method for improving the stability of a heterogeneous Fenton catalyst based on the principles of solvent extraction and equal-volume impregnation. Equal-volume impregnation is used to maximize the local monomer concentration and prevent the uniform nucleation of solvent mixture droplets in the solution. The solvent extraction is used to initiate the concentration of dianhydride and diamine, forming a reaction system with a high concentration. Then, based on the principle of equal-volume impregnation, the concentrated reaction system is uniformly coated on the surface of the heterogeneous Fenton catalyst.

[0054] Beneficial effects:

[0055] (1) The present invention provides a method for surface-modifying a catalyst. By carrying out the polymerization reaction of dianhydride and diamine on the catalyst surface, a polyamic acid film is formed and transformed into a more stable polyimide film through thermal imidization. The heterogeneous Fenton catalyst encapsulated with the polyimide film shows a significant inhibition of metal ion leaching in the heterogeneous Fenton reaction, has strong hydrophobicity, greatly improved stability, and exhibits excellent catalytic degradation activity for organic substances.

[0056] (2) The method for surface-modifying the catalyst provided by the present invention is simple and easy to implement, requires a lower temperature, has a volume reduction by half during the imidization process, is highly economical, is convenient for experimental repetition, industrial scale-up, and popularization and application, and has great technical value and application potential. Description of the drawings

[0057] Figure 1 SEM images of the heterogeneous catalysts encapsulated with the polyimide film obtained in Example 2 and Comparative Example 1, where (a) is the SEM image of the heterogeneous catalyst encapsulated with the polyimide film obtained in Example 2, and (b) is the SEM image of the heterogeneous catalyst encapsulated with the polyimide film obtained in Comparative Example 1;

[0058] Figure 2 Flow chart for improving the stability of the heterogeneous Fenton catalyst of the present invention;

[0059] Figure 3 Flow chart for the polycondensation and imidization of TAM and 6FDA. Detailed implementation manners

[0060] The technical solutions in the embodiments of the present invention are clearly and completely described below. The following content is only used to illustrate the technical solutions of the present invention, rather than to limit the protection scope of the present invention. Any simple modification or equivalent replacement made by those of ordinary skill in the art to the technical solutions of the present invention shall not depart from the essence and scope of the technical solutions of the present invention.

[0061] The technical solutions and technical effects of the present application are further explained and illustrated below through specific implementation manners.

[0062] Example 1

[0063] (1) Place the catalyst FeOOH in a stainless-steel ball-milling jar, add deionized water, and wet-mill it at 400 rpm for 40 min. After drying, obtain the heterogeneous catalyst FeOOH. Take a portion of the catalyst powder to measure the saturated water absorption. Place the FeOOH in a beaker, and weigh its mass before water absorption as m 2 , slowly dropwise add DMF while stirring to ensure uniform impregnation of the carrier. After water absorption, measure the mass of the carrier as m 1 . Calculate the pore volume according to the following formula: V = (m 1 - m 2 ) / ρ DMF . Obtain the amount of DMF absorbed by FeOOH.

[0064] (2) According to the mass parts, react 1 part of the heterogeneous catalyst FeOOH obtained in step (1) with 16 parts of a 6FDA-DCM solution with a concentration of 2.5 mg / mL at -5 °C, stir at 300 rpm for 1 min, sonicate for 1 min, then add 1 part of a TAM-DMF solution with a concentration of 17.5 mg / mL and continue stirring for 3 min. Then quickly add 80 parts of petroleum ether and stir for 3 min. Rinse and filter by suction. Subsequently, perform vacuum drying on the washed product at a temperature of 60 °C for 5 h to obtain the heterogeneous catalyst FeOOH encapsulated by a polyamic acid film;

[0065] (3) Add 40 parts of N,N-dimethylformamide to the product obtained in step (2), stir, then add 6 parts of an acetic anhydride solution with a purity of 99% +, and finally add 2 parts of a triethylamine solution with a purity of 99.5%. Stir at room temperature for 2 h, and the stirring speed is 300 rpm. Then rinse and filter with DMF and DCM respectively, and perform vacuum drying at 60 °C for 5 h to obtain the heterogeneous catalyst FeOOH encapsulated by a polyimide film.

[0066] Example 2

[0067] (1) Place the catalyst FeOOH in a polytetrafluoroethylene ball-milling jar, add deionized water, and ball-mill it at 400 rpm for 2 h. After drying, obtain the heterogeneous catalyst FeOOH. Take a portion of the catalyst powder to measure the saturated water absorption. Place the FeOOH in a beaker, and weigh its mass before water absorption as m 2 , slowly dropwise add DMF while stirring to ensure uniform impregnation of the carrier. After water absorption, measure the mass of the carrier as m 1 . Calculate the pore volume according to the following formula: V = (m 1 - m 2 ) / ρ DMF . Obtain the amount of DMF absorbed by FeOOH.;

[0068] (2) According to the parts by mass, react 1 part of the heterogeneous catalyst FeOOH obtained in step (1) with 16 parts of a 6FDA-DCM solution with a concentration of 2.5 mg / mL at 5 °C, stir at 300 rpm for 3 min, sonicate for 3 min, then add 1 part of a TAM-DMF solution with a concentration of 17.5 mg / mL and continue stirring for 4 min, and then quickly add 80 parts of petroleum ether and stir for 6 min, rinse and filter by suction, and then vacuum-dry the washed product at a temperature of 60 °C for 12 h to obtain the heterogeneous catalyst FeOOH encapsulated by a polyamic acid film;

[0069] (3) Add 20 parts of an N,N-dimethylformamide solution with a purity of 99.8% to the product obtained in step (2), stir, then add 3 parts of an acetic anhydride solution with a purity of 99% +, and finally add 1 part of a triethylamine solution with a purity of 99.5%, stir at room temperature for 2 h, and the stirring speed is 550 rpm. Then rinse and filter with DMF and DCM respectively, and carry out vacuum drying at 60 °C for 12 h to obtain the heterogeneous catalyst FeOOH encapsulated by a polyimide film.

[0070] Example 3

[0071] Compared with Example 1, in step (1), the catalyst FeOOH was replaced with an equal weight of the catalyst FeOCl, and the other conditions and steps were the same as those in Example 1.

[0072] Example 4

[0073] Compared with Example 1, in step (1), the catalyst FeOOH was replaced with an equal weight of the catalyst Fe 3 O 4 , and the other conditions and steps were the same as those in Example 1.

[0074] Example 5

[0075] Compared with Example 1, in step (1), the catalyst FeOOH was replaced with an equal weight of the catalyst Fe 2 O 3 , and the other conditions and steps were the same as those in Example 1.

[0076] Example 6

[0077] Compared with Example 1, in step (2), the weight part of petroleum ether was changed to 100 parts, and the other conditions and steps were the same as those in Example 1.

[0078] Example 7

[0079] Compared with Example 1, the difference lies in that in step (2), 6FDA-DCM is replaced with a BPDA-EDC solution of equal weight and equal concentration, and the TAM-DMF solution is replaced with a TAPB-DMF solution of equal weight and equal concentration, and the remaining conditions and steps are the same as those in Example 1.

[0080] Example 8

[0081] Compared with Example 1, the difference lies in that in step (2), 6FDA-DCM is replaced with a BTDA-TCM solution of equal weight and equal concentration, and the TAM-DMF solution is replaced with a 3N-DMF solution of equal weight and equal concentration, and the remaining conditions and steps are the same as those in Example 1.

[0082] Example 9

[0083] Compared with Example 1, the difference lies in that in step (2), 6FDA-DCM is replaced with an ODPA-EAC solution of equal weight and equal concentration, and the remaining conditions and steps are the same as those in Example 1.

[0084] Example 10

[0085] Compared with Example 1, the difference lies in that in step (2), 6FDA-DCM is replaced with a BPADA-EtOH solution of equal weight and equal concentration, and the remaining conditions and steps are the same as those in Example 1.

[0086] Example 11

[0087] Compared with Example 1, the difference lies in that in step (2), TAM-DMF is replaced with a TAPB-DMF solution of equal weight and equal concentration, and the remaining conditions and steps are the same as those in Example 1.

[0088] Example 12

[0089] Compared with Example 1, the difference lies in that in step (2), TAM-DMF is replaced with a 3N-DMF solution of equal weight and equal concentration, and the remaining conditions and steps are the same as those in Example 1.

[0090] Example 13

[0091] Compared with Example 1, the difference lies in that in step (2), petroleum ether is replaced with n-hexane in equal parts by weight, and the remaining conditions and steps are the same as those in Example 1.

[0092] Example 14

[0093] Compared with Example 1, the difference lies in that in step (3), triethylamine is replaced with tripropylamine in equal parts by weight, and the remaining conditions and steps are the same as those in Example 1.

[0094] Example 15

[0095] Compared with Example 1, the difference lies in that in step (3), triethylamine is replaced with an equal weight portion of diethylamine, and the remaining conditions and steps are the same as those in Example 1.

[0096] Example 16

[0097] Compared with Example 1, the difference lies in that in step (3), triethylamine is replaced with an equal weight portion of anhydrous potassium carbonate, and the remaining conditions and steps are the same as those in Example 1.

[0098] Example 17

[0099] Compared with Example 1, the difference lies in that in step (3), the weight portion of the N,N-dimethylformamide solution is replaced with 20 parts, and the weight portion of the acetic anhydride solution is replaced with 3 parts, and the remaining conditions and steps are the same as those in Example 1.

[0100] Comparative Example 1

[0101] Compared with Example 1, the difference lies in that in step (2), the reaction temperature is changed to react at 10°C, and the remaining conditions and steps are the same as those in Example 1.

[0102] Comparative Example 2

[0103] Compared with Example 1, the difference lies in that in step (2), the reaction temperature is changed to react at 20°C, and the remaining conditions and steps are the same as those in Example 1.

[0104] Comparative Example 3

[0105] Compared with Example 1, the difference lies in that in step (2), the amount of the heterogeneous catalyst FeOOH is 5 parts, the amount of the 6FDA-DCM solution is 20 parts, the amount of the TAM-DMF solution is 5 parts, and the amount of petroleum ether is 100 parts, and the remaining conditions and steps are the same as those in Example 1.

[0106] Test Example

[0107] (1) To test the effect of the polymerization temperature on the polymerization time, at -5°C, 5°C, 10°C and 20°C, 5 mL of a 2.5 mg / mL 6FDA-DCM solution and 305 μL of a 17.5 mg / mL TAM-DMF solution were mixed at a controlled temperature in a 20 mL transparent sample bottle, and fixed in a low-temperature constant temperature bath with a foam board. Samples were taken every 1 min, and the polymerization situation was observed and recorded. The results are shown in Table 1.

[0108] Table 1 Verification of the effect of different polymerization temperatures on the polymerization time

[0109]

[0110] Note: o: clarification; +: initially turbid; ++: slightly turbid; +++: turbid.

[0111] As can be seen from Table 1, the polymerization reaction effect is optimal at a constant temperature of 10°C. During the polymerization reaction: Comparative Example 2 > Example 2 > Comparative Example 1 > Example 1, indicating that a polymerization temperature of 10°C and a polymerization time of 1 min are the most preferred conditions for the polymerization of diamine and dianhydride monomers, and the more preferred polymerization time is 30 s.

[0112] (2) Figure 1 SEM images of the heterogeneous catalyst encapsulated with the polyimide film obtained in Example 2 and Comparative Example 1 Figure 1 Among them, (a) is the SEM image of the heterogeneous catalyst encapsulated with the polyimide film obtained in Example 2. Figure 1 Among them, (b) is the SEM image of the heterogeneous catalyst encapsulated with the polyimide film obtained in Comparative Example 1. The results show that ball milling can make the FeOOH powder more uniform, making it easier for PI to coat on FeOOH to form FeOOH@PI.

[0113] Performance Test

[0114] 1. Fenton reaction degradation of organic pollutants experiment:

[0115] Take a certain amount of the wastewater sample to be treated, conduct necessary pretreatment to remove suspended solids and impurities; weigh a certain amount of the catalyst and add it to the wastewater sample with the pH adjusted (2.8 - 3.5). Under continuous stirring conditions, use a pipette or dropper to add hydrogen peroxide drop by drop to the wastewater containing the catalyst. After the reaction is completed, use a spectrophotometer or other appropriate method to measure the concentration of organic pollutants in the wastewater to evaluate the degradation efficiency. The results are shown in Table 2:

[0116] Table 2 Fenton reaction degradation of organic pollutants experiment

[0117]

[0118] It can be seen that at 120 min, the heterogeneous catalyst FeOOH encapsulated with the polyimide film prepared in Example 1 has a higher percentage of organic pollutant degradation compared to the unencapsulated iron-based Fenton catalyst.

[0119] Furthermore, the pollutant degradation effects of the heterogeneous Fenton catalysts provided in each example and comparative example were tested at 120 min. The results are shown in Table 3:

[0120] Table 3

[0121]

[0122]

[0123] 2. Stability test:

[0124] The removal rate was obtained through cyclic experiments to verify the stability of the encapsulated catalyst. The results showed that the encapsulated catalyst prepared in Example 1 had good stability. After 10 cycles of experiments, the removal rate remained at 93.1 - 95.0%. See Table 4 for details. Among them, the blank control refers to the result of adding hydrogen peroxide for degradation without adding the catalyst.

[0125] Table 4 Stability test of the encapsulated catalyst

[0126]

[0127]

[0128] It can be seen that the heterogeneous catalyst FeOOH encapsulated by the polyimide film provided by the present invention has good cyclic stability.

[0129] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than limiting the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art shall not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A high stability catalyst, characterized in that: The invention comprises a Fenton catalyst and a polyimide membrane coated on the outside of the Fenton catalyst.

2. The high stability catalyst according to claim 1, characterized in that The Fenton catalyst is an iron-based Fenton catalyst; the polyimide membrane is obtained by condensation polymerization of polyamine and dianhydride.

3. The high stability catalyst according to claim 2, characterized in that The dianhydride is selected from at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, hexafluoro dianhydride, diphenyl ether tetracarboxylic dianhydride and bisphenol A diether dianhydride; The polyamine is at least one selected from tetrakis(4-aminophenyl)methane, 1,3,5-tris(4-aminophenyl)benzene, and tris(2-aminoethyl)amine.

4. The high stability catalyst according to claim 2, characterized in that The iron-based Fenton catalyst is selected from at least one of FeOOH, Fe3O4, FeOCl, FeO, Fe2O3 or elemental Fe.

5. The method for preparing a high stability catalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) mixing a dianhydride solution, a polyamine solution and a Fenton catalyst, and adding a non-solvent to obtain an intermediate wrapped with a polyamic acid film; (2) The intermediate obtained in step (1) is subjected to thermal imidization treatment to obtain a high-stability catalyst encapsulated in a polyimide film.

6. The preparation method according to claim 5, characterized in that: In step (1), the non-solvent is selected from at least one of petroleum ether and n-hexane.

7. The preparation method according to claim 5, characterized in that: In step (1), the mass ratio of the dianhydride solution, the polyamine solution, the catalyst and the non-solvent is 10-20:0.1-5:0.1-5:50-100.

8. The preparation method according to claim 5, characterized in that: In step (1), the catalyst is firstly stirred with the dianhydride solution at -10°C to 10°C, and then the polyamine solution is added and stirred for 0.5-10 minutes after ultrasonic treatment.

9. The preparation method according to claim 5, characterized in that: In step (2), the thermal imidization treatment comprises the following steps: mixing the intermediate obtained in step (1) with a solvent and a dehydrating agent to react.

10. Use of the high stability catalyst according to any one of claims 1 to 4 or the high stability catalyst prepared by the preparation method according to any one of claims 5 to 9 in the treatment of polluted water.

Images