A supported perovskite / cordierite catalyst, its preparation method and use

Abstract

The present application belongs to the field of catalytic oxidation and water treatment, and provides a supported perovskite / cordierite catalyst, a preparation method and application thereof. The present application performs pretreatment on a honeycomb-shaped cordierite, dissolves soluble manganese salt, soluble lanthanum salt and a complexing agent to obtain a sol-gel, dips the pretreated honeycomb-shaped cordierite in the sol-gel, and takes out the dipped carrier to perform calcination. The prepared supported perovskite / cordierite catalyst is a solid-phase catalyst, and has simple solid-liquid separation and low catalyst loss. The prepared supported perovskite / cordierite catalyst can make hydrogen peroxide quickly decompose into hydroxyl radicals and persulfate quickly decompose into sulfate radicals in an organic wastewater environment, so as to degrade organic pollutants, and reduce the addition amount of the activator hydrogen peroxide or persulfate. The prepared supported perovskite / cordierite catalyst can degrade various organic wastewaters.

Description

Technical Field

[0001] This invention relates to the fields of catalytic oxidation and water treatment technology, and in particular to a supported perovskite / cordierite catalyst, its preparation method, and its application. Background Technology

[0002] Traditional methods for treating industrial wastewater, such as physical, chemical, or biological methods, are not ideal.

[0003] Advanced oxidation processes (AOPs) utilize the free radicals generated during reactions to oxidize recalcitrant macromolecular toxic organic pollutants in wastewater into less toxic or non-toxic small molecules, or even completely oxidize them into CO2, H2O, and other small molecules, thereby achieving pollutant degradation. Hydrogen peroxide can form hydroxyl radicals (·OH) during oxidation, while persulfate can form sulfate radicals and hydroxyl radicals. All of these free radicals possess strong oxidizing capabilities and their oxidation process is non-selective, capable of undergoing a series of non-selective free radical chain reactions with most electron-rich organic compounds, achieving the goal of degrading organic matter.

[0004] Chinese patent publication number CN113830875A discloses a method based on LaCu 0.5 Mn 0.5 The method of degrading bisphenol A in water using O3 perovskite involves adding LaCu to the water. 0.5 Mn 0.5 O3 perovskite and persulfate achieved a 100% degradation rate of bisphenol A (BPA) in water below 10 ppm within 120 minutes, but only 90% for 15 ppm and 82% for 20 ppm. The catalyst in this patent is only suitable for low-concentration organic matter degradation and can only catalyze the degradation of BPA, and powdered LaCu is used in the reaction process. 0.5 Mn 0.5 O3 perovskite, when used as a catalyst, suffers from solid-liquid separation and catalyst loss, making it difficult to industrialize.

[0005] Chinese patent CN115301243A discloses a supported perovskite catalyst, its preparation method, and its application. First, the active perovskite component PrFe is prepared. x Co 1-xO3 was used, and then the active component was loaded onto pillared montmorillonite using a solid melting method. In the performance verification experiment, 150 mL of 100 mg / L salicylic acid solution and 0.05 g of catalyst were added to a three-necked flask, and the pH was adjusted to 5.0. After stirring at different temperatures for 30 min, 0.21 mL of H2O2 solution was added. When the effect was good, the COD removal rate could reach 74.07%. The reaction conditions in this patent are harsh, requiring the solution pH to be maintained at 5.0, and the amount of hydrogen peroxide added is relatively large, about 470 mg / L. In addition, powder is used as a catalyst in the reaction process, which has the problems of solid-liquid separation and catalyst loss, making it difficult to industrialize. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a supported perovskite / cordierite catalyst, its preparation method, and its application. The catalyst prepared by this invention is easy to recover, and when applied to wastewater treatment, it allows for a wide range of selectable conditions and requires a small amount of activator.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preparing a supported perovskite / cordierite catalyst, comprising the following steps:

[0009] Pre-treated honeycomb cordierite is obtained by pre-treating honeycomb cordierite.

[0010] Soluble manganese salt, soluble lanthanum salt and complexing agent are dissolved, and the resulting mixture is subjected to sol-gelation to obtain a gel;

[0011] The pretreated honeycomb cordierite was impregnated in the gel, and the impregnated support was removed and calcined to obtain the supported perovskite / cordierite catalyst.

[0012] Preferably, the pretreatment includes: impregnating honeycomb cordierite in an inorganic acid; the inorganic acid includes nitric acid, and the mass concentration of the nitric acid is 5-10%; the impregnation temperature is room temperature, and the time is 2-5 hours.

[0013] Preferably, in the mixed solution, the concentration of soluble manganese salt is 0.2–0.5 mol / L, the concentration of soluble lanthanum salt is 0.24–1.2 mol / L, and the ratio of complexing agent concentration to total metal salt concentration is 1:1–1.2; the metal salt includes soluble manganese salt and soluble lanthanum salt, the soluble manganese salt includes one or more of manganese nitrate, manganese chloride, and manganese acetate tetrahydrate, the soluble lanthanum salt includes lanthanum nitrate and / or lanthanum chloride, and the complexing agent includes citric acid; the pH value of the mixed solution is 4–7.

[0014] Preferably, the mixture further includes soluble chromium salts; the concentration of soluble chromium salts in the mixture is ≤0.5mol / L; the soluble chromium salts include chromium nitrate and / or chromium chloride.

[0015] Preferably, the concentration ratio of the sol-gel is 3 to 3.9, and the sol-gel is carried out under the conditions of water bath and stirring, wherein the temperature of the water bath is 60 to 95°C.

[0016] Preferably, the impregnation temperature is room temperature and the time is 10 to 30 minutes; the impregnation is carried out under stirring conditions.

[0017] Preferably, the calcination includes sequentially performing a first calcination and a second calcination;

[0018] The first calcination temperature is 200-300℃, and the holding time is 1-2 hours;

[0019] The second calcination temperature is 500–800℃, and the holding time is 3–5 hours.

[0020] This invention also provides a supported perovskite / cordierite catalyst obtained by the preparation method described above. The supported perovskite / cordierite catalyst comprises cordierite and an active component supported on the cordierite. The active component comprises perovskite, specifically LaCrO3, LaMnO3, MnCrO3, and La. 1-x MnO3.

[0021] This invention also provides the application of the supported perovskite / cordierite catalyst described in the above technical solution in the degradation of organic wastewater, wherein the organic wastewater is one or more of dye wastewater, chemical wastewater, coking wastewater, landfill leachate, and laboratory wastewater.

[0022] Preferably, it includes the following steps:

[0023] The supported perovskite / cordierite catalyst, activator, and organic wastewater to be treated are mixed to obtain a degradation solution for degradation.

[0024] The ratio of the supported perovskite / cordierite catalyst to the organic wastewater to be treated is 1-5 g: 100 mL;

[0025] The activator includes hydrogen peroxide or persulfate;

[0026] The pH value of the degradation solution is preferably 5 to 8.

[0027] This invention provides a method for preparing a supported perovskite / cordierite catalyst, comprising the following steps: pretreating honeycomb cordierite to obtain pretreated honeycomb cordierite; dissolving a soluble manganese salt, a soluble lanthanum salt, and a complexing agent, and performing sol-gelation on the resulting mixture to obtain a gel; impregnating the pretreated honeycomb cordierite in the gel, removing the impregnated support, and calcining it to obtain the supported perovskite / cordierite catalyst.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) The supported perovskite / cordierite catalyst prepared by the present invention is a solid-phase catalyst with simple solid-liquid separation and low catalyst loss.

[0030] (2) The preparation method of the present invention is simple, the reaction conditions are mild and controllable, the cost is low, the cycle is short, and it is easy to prepare on a large scale.

[0031] (3) The supported perovskite / cordierite catalyst prepared by the present invention can generate hydroxyl radicals in an organic wastewater environment, which can initiate a chain reaction, so that hydrogen peroxide is rapidly decomposed into hydroxyl radicals and persulfate is rapidly decomposed into sulfate radicals, thereby degrading organic pollutants; and reducing the amount of activator hydrogen peroxide and persulfate added.

[0032] (4) The supported perovskite / cordierite catalyst prepared by the present invention can degrade a variety of organic wastewater, including one or more combinations of dye wastewater, chemical wastewater, coking wastewater, landfill leachate or laboratory wastewater. Attached Figure Description

[0033] Figure 1 The X-ray diffraction pattern of cordierite after pretreatment obtained in Example 2;

[0034] Figure 2 Scanning electron microscope images of industrial-grade honeycomb cordierite (a) and cordierite after pretreatment obtained in Example 2 (b);

[0035] Figure 3 The graph shows the degradation of coking wastewater by the supported perovskite / cordierite catalysts prepared in Examples 4-11.

[0036] Figure 4 The graph shows the changes in COD concentration (left) and COD removal rate (right) over time in the degradation lifetime experiment of the supported perovskite / cordierite catalyst prepared in Example 11 on coking wastewater.

[0037] Figure 5 Example 11: Supported perovskite / cordierite catalyst prepared and X-ray diffraction pattern after lifetime experiment;

[0038] Figure 6The image shows the supported perovskite / cordierite catalyst prepared in Example 11 and its scanning electron microscope (SEM) image after a lifetime experiment. Detailed Implementation

[0039] This invention provides a method for preparing a supported perovskite / cordierite catalyst, comprising the following steps:

[0040] Pre-treated honeycomb cordierite is obtained by pre-treating honeycomb cordierite.

[0041] Soluble manganese salt, soluble lanthanum salt and complexing agent are dissolved, and the resulting mixture is subjected to sol-gelation to obtain a gel;

[0042] The pretreated honeycomb cordierite was impregnated in the gel, and the impregnated support was removed and calcined to obtain the supported perovskite / cordierite catalyst.

[0043] Unless otherwise specified, all raw materials used in this invention are preferably commercially available products.

[0044] This invention pre-treats honeycomb cordierite to obtain pre-treated honeycomb cordierite.

[0045] In this invention, the honeycomb cordierite is preferably industrial-grade honeycomb cordierite. The honeycomb cordierite is preferably 2cm × 2cm in size.

[0046] In this invention, the pretreatment preferably includes: impregnating honeycomb cordierite in an inorganic acid. In this invention, the inorganic acid preferably includes nitric acid, and the mass concentration of the nitric acid is preferably 5-10%. In this invention, the impregnation temperature is preferably room temperature, and the impregnation time is preferably 2-5 hours.

[0047] After the pretreatment, the present invention preferably further includes: taking out the honeycomb cordierite and washing and drying it sequentially. In the present invention, the washing reagent is preferably water, and the present invention does not specifically limit the amount of washing reagent or the number of washings, as long as the resulting washing water is neutral. In the present invention, the drying temperature is preferably 90-110℃, and the drying time is preferably 4-8 hours.

[0048] In this invention, the honeycomb cordierite is resistant to high temperature, corrosion, and oxidation, and can be calcined at high temperature under air source conditions; and the honeycomb cordierite is a carrier with a certain size and shape, which is easy to recycle; this invention uses inorganic acid to remove impurities from the surface of the honeycomb cordierite.

[0049] In this invention, a soluble manganese salt, a soluble lanthanum salt, and a complexing agent are dissolved, and the resulting mixture is then subjected to sol-gelation to obtain a gel.

[0050] In this invention, the reagent used for dissolving is preferably water.

[0051] In this invention, the concentration of soluble manganese salt in the mixed solution is preferably 0.2–0.5 mol / L, the concentration of soluble lanthanum salt is preferably 0.2–1.2 mol / L, and the ratio of complexing agent concentration to total metal salt concentration is preferably 1:1–1.2; the metal salt includes soluble manganese salt and soluble lanthanum salt. In this invention, the soluble manganese salt preferably includes one or more of manganese nitrate, manganese chloride, and manganese acetate tetrahydrate. In this invention, the soluble lanthanum salt preferably includes lanthanum nitrate and / or lanthanum chloride. In this invention, the complexing agent preferably includes citric acid.

[0052] In this invention, the pH value of the mixture is preferably 4 to 7. In this invention, the pH value of the mixture is preferably adjusted using an alkaline solution, which preferably includes sodium hydroxide solution and / or ammonia. This invention does not specifically limit the concentration and ratio of the sodium hydroxide solution and ammonia, as long as the pH value of the mixture is maintained at 4 to 7.

[0053] In this invention, the mixture preferably further includes soluble chromium salts; the concentration of the soluble chromium salts in the mixture is preferably ≤0.5 mol / L, more preferably 0.1–0.5 mol / L. In this invention, the soluble chromium salts preferably include chromium nitrate and / or chromium chloride.

[0054] In this invention, the concentration ratio of the sol-gelation is preferably 3 to 3.9. In this invention, the sol-gelation is preferably carried out under conditions of a water bath and stirring, and the temperature of the water bath is preferably 60 to 95°C. This invention does not specifically limit the time of the sol-gelation, as long as a gel is obtained.

[0055] After obtaining the pretreated honeycomb cordierite and the gel, the present invention impregnates the pretreated honeycomb cordierite in the gel, removes the impregnation carrier and calcines it to obtain the supported perovskite / cordierite catalyst.

[0056] In this invention, the immersion temperature is preferably room temperature, i.e., no additional heating or cooling is required; the immersion time is preferably 10 to 30 minutes; and the immersion is preferably carried out under stirring conditions.

[0057] After removing the impregnated carrier and before calcination, the present invention preferably includes drying; the drying temperature is preferably 80-140°C and the drying time is preferably 8-12 hours.

[0058] In this invention, the calcination preferably includes performing a first calcination and a second calcination in sequence.

[0059] In this invention, the temperature of the first calcination is preferably 200-300°C, and the holding time is preferably 1-2 hours; after the first calcination, the temperature is preferably directly raised to the temperature of the second calcination for the second calcination.

[0060] In this invention, during the first calcination stage, the citrate polymer undergoes a vigorous redox reaction with nitrate particles. The nitrate acts as an oxidant, breaking the N / N bond, and carbon-containing groups participate in the reaction, releasing gases such as CO, CO2, NO, NO2, O2, and H2. The large amount of gas generated internally makes the product fluffy. When La(NO3)2, Mn(NO3)2, Cr(NO3)2, and C6H8O7 form a polymer, O2 and NO2 gases are released during heating and decomposition. Therefore, a large amount of gas and heat are released at this temperature. A residence time is set to allow for gas release and a stable, slow rise.

[0061] M(C6H8O7) x +NH4 + +NO3 - →MO x +CO x ↑+NO x ↑ + O2↑ + H2O + Heat

[0062] La(NO3)2→La(NO2)2+O2↑

[0063] 2Mn(NO3)2→2MnO+4NO2↑+O2↑

[0064] 2Cr(NO3)2→2CrO+4NO2↑+O2↑.

[0065] In this invention, the second calcination temperature is preferably 500-800°C, and the holding time is preferably 3-5 hours.

[0066] This invention also provides a supported perovskite / cordierite catalyst obtained by the preparation method described in the above technical solution. In this invention, the supported perovskite / cordierite catalyst comprises cordierite and an active component supported on the cordierite, wherein the active component comprises perovskite, and the perovskite comprises LaCrO3, LaMnO3, MnCrO3, and La. 1-x MnO3. In this invention, the active ingredient preferably further includes a metal oxide; the metal oxide preferably includes CrMn. 1.5 O4, CrO2, MnO2 and Cr5O 12 .

[0067] The present invention also provides the application of the supported perovskite / cordierite catalyst described in the above technical solution in the degradation of organic wastewater.

[0068] In this invention, the organic wastewater is preferably one or more of dye wastewater, chemical wastewater, coking wastewater, landfill leachate, and laboratory wastewater.

[0069] In this invention, when the supported perovskite / cordierite catalyst is applied to degrade organic wastewater, it preferably includes the following steps:

[0070] The supported perovskite / cordierite catalyst, activator, and organic wastewater to be treated are mixed to obtain a degradation solution for degradation.

[0071] In this invention, the preferred ratio of the supported perovskite / cordierite catalyst to the organic wastewater to be treated is 1-5 g: 100 mL.

[0072] In this invention, the activator preferably includes hydrogen peroxide or persulfate.

[0073] In this invention, when the activator is hydrogen peroxide, the concentration of hydrogen peroxide in the degradation solution is preferably 50-150 mg / L.

[0074] In this invention, when the activator is persulfate, the concentration of persulfate in the degradation solution is preferably 200-400 mg / L.

[0075] In this invention, the pH value of the degradation solution is preferably 5 to 8.

[0076] In this invention, the degradation temperature is preferably room temperature, i.e., neither additional cooling nor additional heating is required.

[0077] The following detailed description, in conjunction with embodiments, illustrates the supported perovskite / cordierite catalyst, its preparation method, and its applications provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0078] Example 1

[0079] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in a 5% nitric acid solution for 5 hours, washed with water until the solution was neutral, and dried at 90℃ for 8 hours to obtain pretreated cordierite.

[0080] Example 2

[0081] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in an 8% nitric acid solution for 3 hours, washed with water until the solution was neutral, and dried at 100℃ for 6 hours to obtain pretreated cordierite.

[0082] The pretreated cordierite prepared in this embodiment was subjected to X-ray diffraction (XRD) testing, and the results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the main component is Mg2Al4Si5O 18 .

[0083] The industrial-grade honeycomb cordierite and the pretreated cordierite prepared in this embodiment were analyzed by scanning electron microscopy. The results are as follows: Figure 2 As shown, Figure 2 Scanning electron microscope (SEM) images of industrial-grade honeycomb cordierite (a) and pretreated cordierite obtained in Example 2 (b). Figure 2 It can be seen that after pretreatment, the surface of cordierite will be fragmented into upright "columnar blocks", which will increase the specific surface area.

[0084] Example 3

[0085] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in a 10% nitric acid solution for 2 hours, washed with water until the solution was neutral, and dried at 110℃ for 4 hours to obtain pretreated cordierite.

[0086] The specific surface area of ​​the pretreated cordierite prepared in Examples 1-3 was tested, and the results are shown in Table 1.

[0087] Table 1. Specific surface area of ​​pretreated cordierite obtained in Examples 1-3

[0088] Iolite 0.58 Example 1 2.44 Example 2 4.80 Example 3 3.25

[0089] As shown in Table 1, the acid modification method in Example 2 reduced the specific surface area of ​​cordierite from 0.58 m² to 0.58 m². 2 / g increased to 4.80m 2 / g, which is beneficial for the subsequent binding and loading of active components.

[0090] Example 4

[0091] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in an 8% nitric acid solution for 3 hours, washed with water until the solution was neutral, and dried at 100℃ for 6 hours to obtain pretreated cordierite.

[0092] Manganese nitrate, lanthanum nitrate, and citric acid were fully dissolved in water, and the pH of the solution was adjusted to 6 using ammonia. The solution was then mixed to obtain a mixed solution (where the concentration of manganese nitrate was 0.2 mol / L, the concentration of lanthanum nitrate was 0.2 mol / L, and the concentration of citric acid was 0.4 mol / L). The solution was placed in a water bath at 60°C and stirred continuously until a viscous gel was formed at a concentration ratio of 3.3. Pretreated cordierite was then placed in the solution and stirred for 30 min. The solid was then removed and dried at 80°C for 12 h. After drying, the solid was placed in a muffle furnace and calcined at 200°C for 1 h, and then further heated to 800°C for 3 h to obtain the supported perovskite / cordierite catalyst.

[0093] Example 5

[0094] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in an 8% nitric acid solution for 3 hours, washed with water until the solution was neutral, and dried at 100℃ for 6 hours to obtain pretreated cordierite.

[0095] Manganese nitrate, lanthanum nitrate, and citric acid were fully dissolved in water, and the pH of the solution was adjusted to 6 using ammonia. The mixture was stirred to obtain a mixed solution (where the concentration of manganese nitrate was 0.2 mol / L, the concentration of lanthanum nitrate was 0.2 mol / L, and the concentration of citric acid was 0.48 mol / L). The solution was placed in a water bath at 60°C and stirred continuously. The solution was concentrated at a concentration ratio of 3.3 until a viscous gel was formed. Pretreated cordierite was placed in the gel and stirred for 30 min. The solid was removed and dried at 80°C for 12 h. The dried solid was then calcined in a muffle furnace at 200°C for 1 h, and then further heated to 800°C for 3 h to obtain the supported perovskite / cordierite catalyst.

[0096] Example 6

[0097] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in an 8% nitric acid solution for 3 hours, washed with water until the solution was neutral, and dried at 100℃ for 6 hours to obtain pretreated cordierite.

[0098] Manganese nitrate, lanthanum nitrate, and citric acid were fully dissolved in water, and the pH of the solution was adjusted to 6 using ammonia. The mixture was stirred to obtain a mixed solution (where the concentration of manganese nitrate was 0.2 mol / L, the concentration of lanthanum nitrate was 0.24 mol / L, and the concentration of citric acid was 0.528 mol / L). The solution was placed in a water bath at 60°C and stirred continuously. The solution was concentrated at a concentration ratio of 3.3 until a viscous gel was formed. Pretreated cordierite was placed in the gel and stirred for 30 min. The solid was removed and dried at 80°C for 12 h. The dried solid was then calcined in a muffle furnace at 200°C for 1 h, and then further heated to 800°C for 3 h to obtain the supported perovskite / cordierite catalyst.

[0099] Example 7

[0100] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in an 8% nitric acid solution for 3 hours, washed with water until the solution was neutral, and dried at 100℃ for 6 hours to obtain pretreated cordierite.

[0101] Manganese nitrate, chromium nitrate, lanthanum nitrate, and citric acid were fully dissolved in water. The pH of the solution was adjusted to 7 using ammonia. The mixture was stirred to obtain a mixed solution (where the concentration of manganese nitrate was 0.2 mol / L, the concentration of chromium nitrate was 0.2 mol / L, the concentration of lanthanum nitrate was 0.48 mol / L, and the concentration of citric acid was 1.05 mol / L). The solution was placed in a water bath at 60°C and stirred continuously. The solution was concentrated at a concentration ratio of 3.9 until a viscous gel was formed. Pretreated cordierite was placed in the gel and stirred for 30 min. The solid was removed and dried at 80°C for 12 h. The dried solid was then calcined in a muffle furnace at 200°C for 1 h, and then calcined at 800°C for 3 h to obtain the supported perovskite / cordierite catalyst.

[0102] Example 8

[0103] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in an 8% nitric acid solution for 3 hours, washed with water until the solution was neutral, and dried at 100℃ for 6 hours to obtain pretreated cordierite.

[0104] Manganese nitrate, chromium nitrate, lanthanum nitrate, and citric acid were fully dissolved in water. The pH of the solution was adjusted to 6 using ammonia. The mixture was stirred to obtain a mixed solution (where the concentration of manganese nitrate was 0.2 mol / L, the concentration of chromium nitrate was 0.2 mol / L, the concentration of lanthanum nitrate was 0.48 mol / L, and the concentration of citric acid was 1.05 mol / L). The solution was placed in an 80°C water bath and stirred continuously. The solution was concentrated at a concentration ratio of 3.75 until a viscous gel was formed. Pretreated cordierite was added to the gel and stirred for 30 min. The solid was removed and dried at 80°C for 12 h. After drying, the solid was calcined in a muffle furnace at 200°C for 1 h, and then calcined at 600°C for 3 h to obtain the supported perovskite / cordierite catalyst.

[0105] Example 9

[0106] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in an 8% nitric acid solution for 3 hours, washed with water until the solution was neutral, and dried at 100℃ for 6 hours to obtain pretreated cordierite.

[0107] Manganese nitrate, chromium nitrate, lanthanum nitrate, and citric acid were fully dissolved in water. The pH of the solution was adjusted to 6 using ammonia. The mixture was stirred to obtain a mixed solution (where the concentration of manganese nitrate was 0.5 mol / L, the concentration of chromium nitrate was 0.5 mol / L, the concentration of lanthanum nitrate was 1.2 mol / L, and the concentration of citric acid was 2.64 mol / L). The solution was placed in an 80°C water bath and stirred continuously. The solution was concentrated at a concentration ratio of 3 until a viscous gel was formed. Pretreated cordierite was added to the gel and stirred for 30 min. The solid was removed and dried at 140°C for 8 h. After drying, the solid was placed in a muffle furnace and calcined at 200°C for 2 h. The temperature was then increased to 500°C and calcined for 5 h to obtain the supported perovskite / cordierite catalyst.

[0108] Example 10

[0109] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in an 8% nitric acid solution for 3 hours, washed with water until the solution was neutral, and dried at 100℃ for 6 hours to obtain pretreated cordierite.

[0110] Manganese nitrate, chromium nitrate, lanthanum nitrate, and citric acid were fully dissolved in water. The pH of the solution was adjusted to 6 using ammonia. The mixture was stirred to obtain a mixed solution (where the concentrations of manganese nitrate, chromium nitrate, lanthanum nitrate, and citric acid were 0.3 mol / L, 0.72 mol / L, and 1.58 mol / L). The solution was placed in a water bath at 70°C and stirred continuously. The solution was concentrated at a concentration ratio of 3.5 until a viscous gel was formed. Pretreated cordierite was then added to the gel and stirred for 30 min. The solid was removed and dried at 110°C for 8 h. After drying, the solid was calcined in a muffle furnace at 300°C for 1 h, and then further calcined at 600°C for 3 h to obtain the supported perovskite / cordierite catalyst.

[0111] Example 11

[0112] Industrial-grade honeycomb cordierite (2cm×2cm in size) was soaked in an 8% nitric acid solution for 3 hours, washed with water until the solution was neutral, and dried at 100℃ for 6 hours to obtain pretreated cordierite.

[0113] Manganese nitrate, chromium nitrate, lanthanum nitrate, and citric acid were fully dissolved in water. The pH of the solution was adjusted to 6 using ammonia. The mixture was stirred to obtain a mixed solution (where the concentrations of manganese nitrate, chromium nitrate, lanthanum nitrate, and citric acid were 0.3 mol / L, 0.72 mol / L, and 1.58 mol / L). The solution was placed in a water bath at 70°C and stirred continuously. The solution was concentrated at a concentration ratio of 3.5 until a viscous gel was formed. Pretreated cordierite was then added to the gel and stirred for 30 min. The solid was removed and dried at 110°C for 8 h. After drying, the solid was calcined in a muffle furnace at 200°C for 2 h, and then further calcined at 650°C for 3 h to obtain the supported perovskite / cordierite catalyst.

[0114] Performance testing

[0115] Test 1: Wastewater Degradation Performance

[0116] The supported perovskite / cordierite catalysts prepared in Examples 4-11 were used for coking wastewater treatment. Specifically:

[0117] Weigh 2g of the supported perovskite / cordierite catalyst prepared in Examples 4-11 into 100mL of coking wastewater (adjusted to pH 6 using sodium hydroxide or sulfuric acid), and simultaneously add 100mg / L hydrogen peroxide to initiate the degradation reaction. Samples are taken every 1 hour to test the concentration of organic matter in the water samples. The results are shown in Table 2. Figure 3 As shown. Figure 3 The figures show the degradation of coking wastewater by the supported perovskite / cordierite catalysts prepared in Examples 4-11.

[0118] Table 2 Degradation of Coking Wastewater

[0119]

[0120] From Table 2 and Figure 3 It can be seen that: when the supported perovskite / cordierite catalyst prepared in Example 11 was added to 100 mg / L hydrogen peroxide and subjected to a degradation reaction of coking water sample for 1 h, the COD value decreased from 658 mg / L to 34.2 mg / L, and the COD removal rate reached 94.8%.

[0121] Test 2: Degradation performance of the supported perovskite / cordierite catalyst prepared in Example 11 on wastewater from various industries.

[0122] The supported perovskite / cordierite catalyst prepared in Example 11 was used for wastewater treatment in various industries, such as coking wastewater, landfill leachate wastewater, dyeing and printing wastewater, and coal chemical wastewater. Specifically:

[0123] 2 g of the supported perovskite / cordierite catalyst prepared in Example 11 was weighed into 100 mL of wastewater (the pH of the wastewater was adjusted to 6 using sodium hydroxide or sulfuric acid). At the same time, 100 mg / L hydrogen peroxide or 300 mg / L persulfate was added every 1 hour to distinguish the degradation reaction. COD was tested every 1 hour until the COD was degraded to below 100 mg / L. The results are shown in Table 3.

[0124] Table 3 Wastewater Degradation Table by Industry

[0125]

[0126]

[0127] Test 3: Lifetime experiment of the supported perovskite / cordierite catalyst in Example 11 on coking wastewater

[0128] The supported perovskite / cordierite catalyst prepared in Example 11 was used in a coking wastewater lifetime experiment. Specifically:

[0129] The supported perovskite / cordierite catalyst prepared in Example 11 was packed into a fixed-bed reactor and subjected to a space velocity of 1 h⁻¹. -1 The reaction was carried out, with 100 mg / L hydrogen peroxide added during the process. COD was tested every 12 hours, and the results were as follows. Figure 4 As shown, Figure 4 This is a graph showing the changes in COD concentration (left) and COD removal rate (right) over time in an experiment on the degradation lifetime of coking wastewater using the supported perovskite / cordierite catalyst prepared in Example 11. Figure 4 It can be seen that after 360 hours of continuous operation, the COD value of the reactor outlet water sample is still below 100 mg / L.

[0130] X-ray diffraction (XRD) tests were performed on the supported perovskite / cordierite before and after this test, and the results are as follows: Figure 5 As shown, Figure 5 X-ray diffraction pattern of the supported perovskite / cordierite catalyst prepared in Example 11 and after lifetime experiment. From... Figure 5 It can be seen that the diffraction peaks of the cordierite support are quite sharp, and the support itself has the composition of Mg2Al4Si5O. 18 The active components generated by the catalyst loading are mainly: LaCrO3, LaMnO3, MnCrO3, and CrMn. 1.5 O4, La 1-x MnO3, CrO2, MnO2, Cr5O 12 The main active components did not change significantly before and after the reaction. The peak intensity of the corresponding peak before the reaction was slightly higher than that after the reaction, indicating that the active components were slightly reduced.

[0131] Electron microscopy analysis was performed on the supported perovskite / cordierite before and after this test, and the results are as follows: Figure 6 As shown, Figure 6 The images show scanning electron microscope (SEM) images of the supported perovskite / cordierite catalyst prepared in Example 11 and its lifetime after an experiment. Images a, b, and c are SEM images of the supported perovskite / cordierite catalyst prepared in Example 11 at different scanning magnifications, and image d is the SEM image of the supported perovskite / cordierite catalyst prepared in Example 11 after a lifetime experiment. Figure 6 As can be seen from d, after 360 hours of reaction, the amount of active particulate matter decreased.

[0132] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a supported perovskite / cordierite catalyst for degrading COD in organic wastewater, characterized in that, The steps are as follows: The honeycomb cordierite is pretreated by immersing it in an inorganic acid, wherein the inorganic acid is nitric acid and the mass concentration of the nitric acid is 5-10%; the immersion temperature is room temperature and the immersion time is 2-5 hours, thereby obtaining pretreated honeycomb cordierite. A soluble manganese salt, a soluble lanthanum salt, and a complexing agent are dissolved, and the resulting mixture is subjected to sol-gelation to obtain a gel. The concentration of the soluble manganese salt in the mixture is 0.2~0.5 mol / L, and the concentration of the soluble lanthanum salt is 0.24~1.2 mol / L. The mixture also includes a soluble chromium salt; the concentration of the soluble chromium salt in the mixture is ≤0.5 mol / L. The pretreated honeycomb cordierite was impregnated in the gel at room temperature for 10-30 minutes. The impregnation was carried out under stirring. The impregnated support was then removed and calcined to obtain the supported perovskite / cordierite catalyst. The concentration ratio of the sol-gelation is 3 to 3.9, and the sol-gelation is carried out under the conditions of water bath and stirring, wherein the temperature of the water bath is 60 to 95°C. The calcination includes sequentially performing a first calcination and a second calcination; The first calcination temperature is 200~300℃, and the holding time is 1~2h; The second calcination temperature is 500~800℃, and the holding time is 3~5h.

2. The preparation method according to claim 1, characterized in that, The ratio of the concentration of the complexing agent to the total concentration of the metal salt in the mixture is 1:1 to 1.2; the soluble manganese salt is one or more of manganese nitrate, manganese chloride, and manganese acetate tetrahydrate; the soluble lanthanum salt is lanthanum nitrate and / or lanthanum chloride; the complexing agent is citric acid; and the pH value of the mixture is 4 to 7.

3. The preparation method according to claim 1 or 2, characterized in that, The soluble chromium salt is chromium nitrate and / or chromium chloride.

4. The supported perovskite / cordierite catalyst obtained by the preparation method according to any one of claims 1 to 3, characterized in that, The supported perovskite / cordierite catalyst includes cordierite and an active component supported on the cordierite, the active component including perovskite.

5. The application of the supported perovskite / cordierite catalyst according to claim 4 in the degradation of organic wastewater, characterized in that, The organic wastewater is one or more of the following: dye wastewater, chemical wastewater, coking wastewater, landfill leachate, and laboratory wastewater.

6. The application according to claim 5, characterized in that, Includes the following steps: The supported perovskite / cordierite catalyst, activator, and organic wastewater to be treated are mixed to obtain a degradation solution for degradation. The ratio of the supported perovskite / cordierite catalyst to the organic wastewater to be treated is 1~5g:100mL; The activator includes hydrogen peroxide or persulfate; The pH value of the degradation solution is 5-8.

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