Cordierite-based supported ozone catalyst and preparation method and application thereof

Abstract

The application provides a cordierite-based supported ozone catalyst and a preparation method and application thereof. The prepared supported ozone catalyst can well balance excellent COD removal rate and good mechanical properties when used for treating organic wastewater, especially high-salt organic wastewater in the field of coal chemical industry. The preparation method comprises the following steps: 1) pretreating porous cordierite in an acid solution, then cleaning and drying to obtain a carrier; 2) applying a coating liquid on the carrier, then drying to obtain a precursor; the coating liquid comprises an active component, silica sol and optional starch; the active component comprises MnO2 and optionally CeO2; the coating liquid also preferably comprises glass fiber and polyethylene glycol; 3) calcining the precursor at 100-150 DEG C to obtain a supported ozone catalyst with a coating layer formed on the carrier.

Description

Technical Field

[0001] This invention relates to ozone catalysts suitable for treating organic wastewater, especially high-salt organic wastewater from the coal chemical industry, and specifically to a cordierite-based supported ozone catalyst, its preparation method, and its application. Background Technology

[0002] Biochemical methods are commonly used to remove organic matter from water. Microorganisms decompose organic matter, thus removing it. However, microorganisms struggle to survive in high-salt environments, making COD removal difficult. Advanced oxidation processes (AOPs) are highly efficient wastewater treatment technologies that generate strong hydroxyl radicals to decompose organic matter in water, mineralizing it into CO2 and H2O. Ozone has strong oxidizing properties in water and is therefore frequently used in AOPs. Specific ozone catalysts can be added to improve oxidation efficiency. Industrial coal chemical wastewater often contains high levels of salt, thus requiring high catalyst activity and stability.

[0003] Patent application CN202010067144.4 describes a highly efficient heterogeneous ozone catalyst for treating acidic industrial wastewater and its preparation method. This heterogeneous ozone catalyst consists of a cordierite honeycomb ceramic support and γ-Al₂O₃ and the active component Pd-CeOx supported on the surface of the cordierite honeycomb ceramic support. The preparation method includes: impregnating the cordierite honeycomb ceramic sequentially in γ-Al₂O₃ sol, CeOx sol, and lead nitrate solution, followed by drying and calcination to obtain the heterogeneous ozone catalyst. This catalyst is used for treating high-COD acidic organic wastewater effluent, achieving a COD removal efficiency nearly 15% higher than existing catalysts, with more stable COD levels in the effluent. It is also low-cost to prepare, produces no secondary pollution, and solves the problem of treating high-concentration, high-organic wastewater from industries such as printing and dyeing, pesticides, pharmaceuticals, papermaking, and chemicals.

[0004] Patent application CN 201711065843.X discloses a method for preparing a heterogeneous ozone catalyst, its product, and its applications. The preparation process includes the hydrothermal growth of nickel oxide nanosheets on the surface of cordierite honeycomb ceramic and the growth of zinc oxide nanorods on the cordierite honeycomb ceramic surface on which nickel oxide nanosheets have been grown. Compared with ozone catalysts prepared by conventional impregnation methods, this catalyst uses a two-step hydrothermal method to first generate nickel oxide nanosheets on the surface of the cordierite honeycomb ceramic support, and then hydrothermally grow zinc oxide nanorods on the cordierite honeycomb ceramic surface on which nickel oxide nanosheets have been grown.

[0005] Patent application CN201911181406.3 discloses a method for preparing a modified ozone catalyst suitable for high-salinity wastewater from coal chemical industry. This method overcomes the shortcomings of existing ozone catalysts in removing COD from high-salinity wastewater due to their low efficiency. Furthermore, to adapt to different production processes and application environments, it provides a method for preparing a modified ozone catalyst suitable for high-salinity wastewater from coal chemical industry. This method is based on the preparation of a calcined ozone catalyst and includes the following steps: immersing the calcined ozone catalyst in a non-polar reagent for 12-24 hours, followed by filtration; drying and calcining the filtered ozone catalyst to obtain the modified ozone catalyst. The modified ozone catalyst in this document has a surface "loaded with a non-polar reagent," which, in ozone oxidation experiments, can "specifically" "attract" heterocyclic compounds to the catalyst surface to undergo oxidation reactions with hydroxyl radicals, making it particularly suitable for removing COD from complex and turbid wastewater.

[0006] Patent application CN201510508937.4 discloses a high-salt ozone-resistant catalyst, composed of the following components in parts by weight: 88.7-91.3 parts of activated alumina particles with a particle size of 2-4 mm, 1.4-1.6 parts of copper oxide, 0.8-1.2 parts of titanium dioxide, 4-7 parts of polyethylene glycol, and 1.9-2.1 parts of polyvinyl alcohol. The 88.7-91.3 parts of the activated alumina particles with a particle size of 2-4 mm are then mixed with 1 part of copper oxide... 0.4–1.6 parts of copper oxide, 0.8–1.2 parts of titanium dioxide, 4–7 parts of polyethylene glycol, and 1.9–2.1 parts of polyvinyl alcohol are mixed in a mixer to form a catalyst mother ball, which is then uniformly mixed and covers the surface of the activated alumina particles. The catalyst mother ball is then dried and calcined to obtain the high-salt-resistant ozone catalyst. This literature discloses that the obtained ozone catalyst has improved tolerance to high-salt substances, resulting in excellent performance in the catalytic oxidation treatment of saline wastewater, including COD removal, decolorization, deodorization, degradation of toxic pollutants, and improvement of the wastewater's biodegradability.

[0007] Existing heterogeneous ozone catalyst preparation processes suffer from drawbacks such as complex processes, unsatisfactory catalyst mechanical properties, and insufficient ozone utilization. Particularly when using ozone catalysts to treat organic wastewater from the coal chemical industry, the complex composition of this wastewater, typically containing high levels of salt and organic matter, places higher demands on the mechanical properties and catalytic activity of the ozone catalyst. Developing an ozone catalyst suitable for organic wastewater, particularly from the coal chemical industry, and capable of providing a relatively simple preparation process that balances good mechanical properties with effective wastewater treatment, is one of the critical technical challenges in this field that urgently needs to be overcome. Summary of the Invention

[0008] This invention provides a cordierite-based supported ozone catalyst, its preparation method, and its application. The preparation method of this invention for the supported ozone catalyst is simple, easy, and quick, requiring no high-temperature calcination and enabling the acquisition of a high-salt-tolerant ozone catalyst at relatively low temperatures. Furthermore, the supported ozone catalyst prepared by this invention can effectively balance excellent COD removal rate and good mechanical properties when used for the treatment of organic wastewater, especially high-salt organic wastewater in the coal chemical industry.

[0009] To achieve its objective, the present invention provides the following technical solution:

[0010] This invention provides a method for preparing a cordierite-based supported ozone catalyst, comprising the following steps:

[0011] 1) The porous cordierite was pretreated in an acidic solution, then washed and dried to obtain a carrier;

[0012] 2) Apply a coating solution to the carrier and then dry it to obtain a precursor; the coating solution includes an active component, silica sol and optional starch; the active component includes MnO2 and optionally CeO2; the coating solution also preferably includes glass fiber and polyethylene glycol;

[0013] 3) The precursor is calcined at 100-150°C to obtain a supported ozone catalyst with a coating layer formed on the support.

[0014] In some embodiments, in step 1), the pH of the acidic solution is 2-4;

[0015] Preferably, in step 1), the acidic solution is selected from hydrochloric acid aqueous solution and / or nitric acid aqueous solution;

[0016] Preferably, in step 1), the pretreatment includes soaking the porous cordierite in the acidic solution for 10-12 hours.

[0017] In some embodiments, in step 2), the coating liquid comprises the following components in parts by weight:

[0018] The composition comprises 50-100 parts MnO2, 0-3 parts CeO2, 10-15 parts silica sol, 0-0.3 parts glass fiber, 0-0.15 parts polyethylene glycol, 0-0.5 parts starch, and 100 parts water, wherein the weight of the silica sol is based on the amount of silicon dioxide contained therein; preferably, the weight of MnO2 is 90-100 parts; preferably, the weight of the glass fiber is 0.1-0.3 parts, and the weight of the polyethylene glycol is 0.05-0.15 parts.

[0019] Preferably, the weight ratio of MnO2 to CeO2 is 50-100:1-3, more preferably 100:1-3. 4. The preparation method according to claim 3, characterized in that, in step 2), the carrier is immersed in the coating liquid so that the surface of the carrier is coated with a coating liquid layer.

[0020] In some implementations, step 3) involves calcining at 100-150°C for 4-10 hours.

[0021] In some embodiments, the coating layer comprises 5-20% by weight, preferably 10-20%, based on the weight of the supported ozone catalyst.

[0022] In some embodiments, the weight ratio of MnO2 to CeO2 in the coating liquid is 100:1-3;

[0023] Furthermore, based on the weight of the supported ozone catalyst, the weight percentage of the coating layer is 10-20%.

[0024] In some embodiments, the porous cordierite is honeycomb cordierite.

[0025] In some embodiments, the porous cordierite has a regular shape; preferably, the overall shape of the porous cordierite is cuboid or cube, or approximately cuboid or cube.

[0026] The present invention also provides a cordierite-based supported ozone catalyst prepared by the preparation method described above.

[0027] The present invention also provides an application of the cordierite-based supported ozone catalyst described above in the treatment of organic wastewater, particularly in the treatment of organic wastewater generated in the coal chemical industry.

[0028] The technical solution provided by this invention has the following beneficial effects:

[0029] The preparation method provided by this invention involves first pretreating the carrier cordierite with an acidic solution, and then applying a coating layer to a coating solution containing active components and silica sol (preferably also containing glass fiber and polyethylene glycol). This allows for the calcination at low temperatures to obtain an ozone catalyst that combines good reactivity and mechanical properties. The coating layer of this catalyst is not easily detached and is easy to reuse. The preparation method of this invention is simple in overall process, easy and quick to operate, easy to implement, and has low energy consumption. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a supported ozone catalyst prepared in one embodiment.

[0031] Figure 2 This is a schematic diagram of a supported ozone catalyst prepared in a comparative embodiment.

[0032] Figure 3 This is a schematic diagram of the experimental apparatus for catalytic ozonation.

[0033] Figure 4 This is a schematic diagram of a honeycomb cordierite carrier.

[0034] Figure 3 The following are the labels in the attached diagram: 1. Ozone generator, 2. Ozone concentration detector, 3. Reactor, 4. Catalyst. Detailed Implementation

[0035] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" may be used herein to include any and all combinations of one or more of the associated listed items.

[0037] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in this technical field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0038] This invention provides a method for preparing a cordierite-based supported ozone catalyst, which mainly includes the following steps:

[0039] 1) The porous cordierite was pretreated in an acidic solution, then washed and dried to obtain a carrier;

[0040] 2) Apply a coating solution to a support and then dry it to obtain a precursor; the coating solution includes an active component, silica sol and optional starch; the active component includes MnO2 and optionally CeO2; the coating solution also preferably includes glass fiber and polyethylene glycol; 3) Calcine the precursor at 100-150°C to obtain a supported ozone catalyst with a coating layer formed on the support.

[0041] Using the preparation method of the present invention, porous cordierite is pretreated in an acidic solution, and then a coating solution containing MnO2 (and optionally CeO2) of specific components is applied and calcined at a relatively low temperature. This method can obtain a supported ozone catalyst based on a low-energy-consumption and simple and quick preparation process. At the same time, when this catalyst is applied to the treatment of organic wastewater, especially high-salt organic wastewater in the coal chemical industry, it can effectively remove COD and has good mechanical properties. The coating layer of the catalyst is not easy to fall off.

[0042] In some preferred embodiments, in step 1), the pretreatment of porous cordierite in an acidic solution is preferably carried out in an acidic solution with a pH of 2-4. Pretreatment under these pH conditions facilitates the uniform and firm coating of the coating solution onto the carrier surface, resulting in a catalyst with excellent performance. In some embodiments, the acidic solution can be, for example, an aqueous solution of hydrochloric acid and / or an aqueous solution of nitric acid. Specifically, during the pretreatment process, the porous cordierite can be immersed in the acidic solution, for example, for 10-12 hours. In some embodiments, after immersion in the acidic solution, the porous cordierite is washed with water, for example, until the washing solution is neutral, and then dried to constant weight. Drying can be carried out at 100-120°C. The pretreatment of cordierite in the acidic solution can be carried out at room temperature without additional heating.

[0043] In some embodiments, in step 1), the porous cordierite is pre-washed with water and dried before being placed in the acidic solution for the pretreatment. The drying in this step can be carried out, for example, in an oven at 100-120°C to remove moisture.

[0044] In some preferred embodiments, in step 2), the coating solution used comprises the following components in parts by weight: 50-100 parts MnO2, 0-3 parts CeO2, 10-15 parts silica sol, 0-0.3 parts glass fiber, 0-0.15 parts polyethylene glycol, 0-0.5 parts starch, and 100 parts water, wherein the weight of the silica sol is based on the silica content therein. Using a coating solution with the preferred formulation helps the coating solution adhere uniformly and firmly to the inner and outer surfaces of the cordierite carrier, which is beneficial for obtaining an ozone catalyst with good mechanical properties and for fully utilizing the reactivity of the obtained ozone catalyst in the treatment of organic wastewater. The inventors have found that if the silica sol in the coating solution is replaced with other types of binders such as alumina sol or water glass, the coating solution becomes difficult to apply to the carrier, and the coating layer on the surface of the final ozone catalyst is prone to peeling off, making it difficult to form a coating layer with good mechanical stability. In a preferred embodiment, the coating solution contains 0.1-0.3 parts by weight of glass fiber and 0.05-0.15 parts by weight of polyethylene glycol. It is preferable to add the above proportions of glass fiber and polyethylene glycol to the coating solution, which helps to improve the uniformity of coating solution application, improve catalyst activity, and enhance mechanical stability.

[0045] In the above-mentioned coating liquid formulation system, the weight part of MnO2 is 50-100 parts, preferably 90-100 parts. Using the preferred weight part of MnO2 is beneficial to further improve the mechanical properties of the catalyst and to obtain a catalyst with excellent performance.

[0046] In some preferred embodiments, the active components in the coating solution include both MnO2 and CeO2, with a weight ratio of 50-100:1 to 3, preferably 100:1 to 100:3; using the active components in the preferred ratio can improve the catalytic activity of the ozone catalyst.

[0047] In the preparation method of the present invention, preferably, step 2) of applying the coating liquid to the support includes applying the coating liquid to each of the exposed surfaces of the support, such as the outer and inner surfaces of the support. For example, for cordierite with internal channels, the coating liquid is applied to the surfaces of these internal channels accordingly. By applying the coating liquid, a coating layer is formed on the support of the finally obtained ozone catalyst. Preferably, the coating liquid layer is adhered to the surface of the support by immersing the support in the coating liquid, for example, by repeatedly immersing the support in the coating liquid to ensure that the coating liquid is fully and uniformly adhered to each of the exposed surfaces of the support. In step 2), drying after applying the coating liquid to the support can be carried out at 60-80°C until the coating liquid solidifies on the surface.

[0048] In the preparation method of this invention, in step 3), the precursor obtained in the aforementioned steps only needs to undergo one low-temperature calcination step. A high-performance supported ozone catalyst can be obtained by low-temperature calcination at 100-150°C. The calcination time can be, for example, 4-10 hours. The inventors have found that, based on the preparation process of this invention, if a higher calcination temperature is used, it will adversely affect the catalytic activity and mechanical stability of the ozone catalyst, resulting in a decrease in COD removal rate.

[0049] In the preparation method of this invention, based on the weight of the supported ozone catalyst, the preferred weight percentage of the coating layer is 5-20%. Based on this coating layer loading, the obtained ozone catalyst not only exhibits high catalytic activity and achieves a good COD removal rate, but also maintains low mechanical loss during use. More preferably, the weight percentage of the coating layer is 10-20%, and the ozone catalyst using this preferred coating layer ratio exhibits even better catalytic activity.

[0050] In some preferred embodiments of the preparation method of the present invention, the porous cordierite is preferably honeycomb cordierite, which has honeycomb-shaped internal channels. Using the preferred cordierite can serve as a fixed-bed catalyst, reducing collisions caused by displacement between catalysts, thereby further reducing catalyst mechanical loss; simultaneously, the abundant internal channels of porous cordierite, especially honeycomb cordierite, facilitate increasing the ozone contact area, improving ozone utilization, and promoting enhanced catalytic activity. Preferably, cordierite has a regular shape, serving as a cordierite carrier with a regular structure. For example, its overall shape is rectangular or cubic, or roughly rectangular or cubic. The resulting catalyst is a regularly shaped ozone catalyst, which allows multiple supported ozone catalysts to be stacked and / or helps maintain their fixed positions, reducing collisions and disturbances, and minimizing catalyst mechanical wear. Furthermore, the regularly shaped ozone catalyst obtained based on the regularly shaped cordierite carrier also allows for more uniform gas-liquid distribution, avoiding or reducing ozone gas channeling, thus improving ozone utilization, catalyst efficiency, and COD removal rate.

[0051] In some preferred embodiments, the active components in the coating solution of step 2) include both MnO2 and CeO2, and the weight ratio of the two is preferably 100:1 to 3; step 3) is calcined at 100-150°C, and the weight percentage of the coating layer is 10-20% based on the weight of the supported ozone catalyst; the ozone catalyst prepared by this preferred scheme has better catalytic activity and can also take into account excellent mechanical properties, and the coating layer is not easy to fall off, which is beneficial to reducing the mechanical loss rate of the catalyst.

[0052] The present invention also provides a cordierite-based supported ozone catalyst prepared by the preparation method described above. This catalyst is simple to prepare and has the characteristics of good mechanical properties, high catalytic efficiency, and reusability.

[0053] The supported ozone catalyst prepared by the method of this invention can be applied to the treatment of organic wastewater, especially to high-salt organic wastewater (e.g., TDS ≤ 60000 mg·L⁻¹) in the coal chemical industry. -1 The ozone catalyst exhibits excellent catalytic oxidation activity, effectively removing COD. Furthermore, it demonstrates good mechanical stability during application, with a low risk of coating peeling, thus reducing mechanical loss. Based on this, the present invention also provides an application where the cordierite-based supported ozone catalyst described above is used for the treatment of organic wastewater, particularly for the treatment of high-salt organic wastewater generated in the coal chemical industry. The supported ozone catalyst provided by the present invention can solve the problems of low COD removal rate and poor catalyst mechanical performance in high-salt organic wastewater from the coal chemical industry. In some embodiments, the ozone catalyst of the present invention is used for the treatment of high-salt organic wastewater from the coal chemical industry, achieving a COD removal rate of over 70%, with superior mechanical performance, thus reducing mechanical loss.

[0054] The present invention will be illustrated below with reference to embodiments:

[0055] Unless otherwise specified, all raw materials used in the following examples and comparative examples were commercially available. Some of the raw material information is as follows: manganese dioxide (99.99%), cerium dioxide (99.99%), polyethylene glycol PEG200, silica sol SS-28, and glass fiber (800 mesh).

[0056] The organic wastewater involved in the following examples or comparative examples is high-salt organic wastewater from coal chemical industry. The various water quality parameters are shown in Table 1 below:

[0057] Table 1 Experimental water quality parameters

[0058]

[0059]

[0060] In the following examples, the weight percentage of the coating layer in the obtained catalyst is calculated as follows: the weight of the carrier before coating with the coating liquid is recorded as m1, and the weight after coating with the coating liquid and drying is recorded as m2. The weight ratio of the coating layer is (m2-m1) / m2*100%.

[0061] Example 1

[0062] Prepare an ozone catalyst according to the following steps:

[0063] 1) Take commercially available honeycomb cordierite (size 50mm long * 50mm high * 30mm wide, see [reference]). Figure 4 The substrate was washed with deionized water, then dried in an oven at 120°C for 4 hours. It was then pretreated by soaking in a 40wt% nitric acid aqueous solution (pH 2) at room temperature for 10 hours. After washing with water until the washing solution was neutral, it was dried at 120°C for 8 hours to obtain the carrier.

[0064] 2) Prepare a coating solution by mixing 100g MnO2, 1g CeO2, 12.5g silica sol (calculated as silica), 0.2g glass fiber, 0.1g polyethylene glycol, 0.5g starch, and 100g water; repeatedly immerse the cordierite carrier pretreated in step 1) in the coating solution until the surface of the carrier is uniformly coated with a layer of coating solution, then blow it clean and place it in an oven to dry at 80℃ for 4h to obtain the precursor;

[0065] 3) The precursor was calcined in a muffle furnace at 115°C for 6 hours to obtain catalyst A with a coating layer (see physical image). Figure 1 The catalyst, with a coating layer comprising 10% by weight, was used to treat high-salt organic wastewater from a coal chemical plant. The COD removal rate was 68%. During application, the coating layer of the catalyst did not peel off and could be reused.

[0066] Example 2

[0067] Prepare an ozone catalyst according to the following steps:

[0068] 1) Commercially available honeycomb cordierite (same specifications as in Example 1) was washed with deionized water, then placed in an oven and dried at 120°C for 4 hours. It was then pretreated by soaking in a 40wt% nitric acid aqueous solution (pH 2) at room temperature for 10 hours. It was then washed with water until the washing solution was neutral, and then dried at 120°C for 8 hours to obtain the carrier.

[0069] 2) Prepare a coating solution by mixing 100g MnO2, 1g CeO2, 12.5g silica sol (calculated as silica), 0.2g glass fiber, 0.1g polyethylene glycol, 0.5g starch, and 100g water; repeatedly immerse the cordierite carrier pretreated in step 1) in the coating solution until the surface of the carrier is uniformly coated with a layer of coating solution; then blow it clean and place it in an oven to dry at 80℃ for 4h to obtain the precursor;

[0070] 3) The precursor was placed in a muffle furnace and calcined at 150°C for 6 hours to obtain catalyst B with a coating layer, wherein the weight percentage of the coating layer was 10%; the catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 70%. During the application, the coating layer of the catalyst did not peel off and could be reused.

[0071] Comparative Example 1 (High-Temperature Calcination)

[0072] Prepare an ozone catalyst according to the following steps:

[0073] 1) Commercially available honeycomb cordierite (same specifications as in Example 1) was washed with deionized water, then placed in an oven and dried at 120°C for 4 hours. It was then pretreated by soaking in a 40wt% nitric acid aqueous solution (pH 2) at room temperature for 12 hours. It was then washed with water until the washing solution was neutral, and then dried at 120°C for 8 hours to obtain the carrier.

[0074] 2) Prepare a coating solution by mixing 100g MnO2, 1g CeO2, 12.5g silica sol (calculated as silica), 0.2g glass fiber, 0.1g polyethylene glycol, 0.5g starch, and 100g water; repeatedly immerse the cordierite carrier pretreated in step 1) in the coating solution until the surface of the carrier is uniformly coated with a layer of coating solution, then blow it clean and place it in an oven to dry at 80℃ for 4h to obtain the precursor;

[0075] 3) The precursor was placed in a muffle furnace and calcined at 400℃ for 6 hours to obtain catalyst C with a coating layer, wherein the weight percentage of the coating layer was 10%; the catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 45%. During the application, the coating layer of the catalyst showed obvious peeling and could not be reused.

[0076] As can be seen from this comparative example, the main difference compared to Example 1 is that increasing the calcination temperature to 400°C significantly reduces the performance of the ozone catalyst and its COD removal capacity.

[0077] Example 3

[0078] Prepare an ozone catalyst according to the following steps:

[0079] 1) Commercially available honeycomb cordierite (same specifications as in Example 1) was washed with deionized water, then placed in an oven and dried at 120°C for 4 hours. It was then pretreated by soaking in a 40wt% nitric acid aqueous solution (pH 2) at room temperature for 10 hours. It was then washed with water until the washing solution was neutral, and then dried at 120°C for 8 hours to obtain the carrier.

[0080] 2) Prepare a coating solution by mixing 50g MnO2, 1g CeO2, 12.5g silica sol (calculated as silica), 0.2g glass fiber, 0.1g polyethylene glycol, 0.5g starch, and 100g water; repeatedly immerse the cordierite carrier pretreated in step 1) in the coating solution until the surface of the carrier is uniformly coated with a layer of coating solution, then blow it clean and place it in an oven to dry at 80℃ for 4h to obtain the precursor;

[0081] 3) The precursor was placed in a muffle furnace and calcined at 115°C for 6 hours to obtain catalyst D with a coating layer, wherein the weight percentage of the coating layer was 5%; the catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 55%. During the application, the coating layer of the catalyst did not peel off and could be reused.

[0082] As can be seen from Example 3, the ozone catalyst prepared by the preparation method of the present invention can still achieve a good COD removal rate even when the proportion of the coating layer is reduced to a low level of 5%.

[0083] Example 4

[0084] Prepare an ozone catalyst according to the following steps:

[0085] 1) Commercially available honeycomb cordierite (same specifications as in Example 1) was washed with deionized water, then placed in an oven and dried at 120°C for 4 hours. It was then pretreated by soaking in a 40wt% nitric acid aqueous solution at room temperature for 12 hours (pH 2). It was then washed with water until the washing solution was neutral, and then dried at 120°C for 10 hours to obtain the carrier.

[0086] 2) Prepare a coating solution by mixing 100g MnO2, 1g CeO2, 12.5g silica sol (calculated as silica), 0.2g glass fiber, 0.1g polyethylene glycol, 0.5g starch, and 100g water; repeatedly immerse the cordierite carrier pretreated in step 1) in the coating solution until the surface of the carrier is uniformly coated with a layer of coating solution, blow it clean, and dry it in an oven at 80℃ for 4h to obtain the precursor;

[0087] 3) The precursor was placed in a muffle furnace and calcined at 115°C for 6 hours to obtain catalyst E with a coating layer, wherein the weight percentage of the coating layer was 15%; the catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 72%. During the application, the coating layer of the catalyst did not peel off and could be reused.

[0088] Example 5

[0089] Prepare an ozone catalyst according to the following steps:

[0090] 1) Commercially available honeycomb cordierite (same specifications as in Example 1) was washed with deionized water, then placed in an oven and dried at 120°C for 4 hours. It was then pretreated by soaking in a 40wt% nitric acid aqueous solution at room temperature for 12 hours. It was then washed with water until the washing solution was neutral, and then dried at 110°C for 12 hours to obtain the carrier.

[0091] 2) Prepare a coating solution by mixing 100g MnO2, 1g CeO2, 12.5g silica sol (calculated as silica), 0.2g glass fiber, 0.1g polyethylene glycol, 0.5g starch, and 100g water; repeatedly immerse the cordierite carrier pretreated in step 1) in the coating solution until the surface of the carrier is uniformly coated with a layer of coating solution, blow it clean, and dry it in an oven at 80℃ for 4h to obtain the precursor;

[0092] 3) The precursor was placed in a muffle furnace and calcined at 115°C for 6 hours to obtain catalyst F with a coating layer, wherein the weight percentage of the coating layer was 20%; the catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 74%. During the application, the coating layer of the catalyst did not peel off and could be reused.

[0093] Comparative Example 2

[0094] Prepare an ozone catalyst according to the following steps:

[0095] 1) Commercially available spherical cordierite (solid cordierite without internal pores) was washed with deionized water, then dried in an oven at 120°C for 4 hours. It was then pretreated by soaking in a 40wt% nitric acid aqueous solution at room temperature for 10 hours. After washing with water until the washing solution was neutral, it was dried at 110°C for 12 hours to obtain the carrier.

[0096] 2) Prepare a coating solution by mixing 100g MnO2, 1g CeO2, 12.5g silica sol (calculated as silica), 0.2g glass fiber, 0.1g polyethylene glycol, 0.5g starch, and 100g water; immerse the pretreated spherical carrier from step 1) in the coating solution until the surface of the carrier is uniformly coated with a layer of coating solution, blow it clean, and dry it in an oven at 80℃ for 4h to obtain the precursor;

[0097] 3) The precursor was placed in a muffle furnace and calcined at 115°C for 6 hours to obtain catalyst G with a coating layer, wherein the weight percentage of the coating layer was 10%. The catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 60%. During the application, the coating layer of the catalyst was obviously peeled off after being washed and collided by the fluid, and it could not be reused.

[0098] The main difference between this comparative example and Example 1 is that the honeycomb cordierite was replaced with solid spherical cordierite. As a result, under the same conditions, the performance of the ozone catalyst was significantly reduced, the COD removal rate decreased, and the mechanical properties of the catalyst deteriorated significantly.

[0099] Example 6 (without CeO2)

[0100] Prepare an ozone catalyst according to the following steps:

[0101] 1) Commercially available honeycomb cordierite (same specifications as in Example 1) was washed with deionized water, then placed in an oven and dried at 120°C for 4 hours. It was then pretreated by soaking in a 40wt% nitric acid aqueous solution (pH 2) at room temperature for 12 hours. It was then washed with water until the washing solution was neutral, and then dried at 120°C for 10 hours to obtain the carrier.

[0102] 2) Prepare a coating solution by mixing 100g MnO2, 12.5g silica sol (calculated as silica), 0.2g glass fiber, 0.1g polyethylene glycol, 0.5g starch, and 100g water; repeatedly immerse the cordierite carrier pretreated in step 1) in the coating solution until the surface of the carrier is uniformly coated with a layer of coating solution, blow it clean, and dry it in an oven at 80℃ for 4h to obtain the precursor;

[0103] 3) The precursor was placed in a muffle furnace and calcined at 115°C for 6 hours to obtain catalyst H, in which the coating layer accounted for 10% by weight. The catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 65%. During the application, the coating layer of the catalyst did not peel off and could be reused.

[0104] Example 7

[0105] Prepare an ozone catalyst according to the following steps:

[0106] 1) Commercially available honeycomb cordierite (same specifications as in Example 1) was washed with deionized water, then placed in an oven and dried at 120°C for 4 hours. It was then pretreated by soaking in a 40wt% nitric acid aqueous solution (pH 2) at room temperature for 10 hours. It was then washed with water until the washing solution was neutral, and then dried at 120°C for 10 hours to obtain the carrier.

[0107] 2) Prepare a coating solution by mixing 100g MnO2, 3g CeO2, 12.5g silica sol (calculated as silica), 0.2g glass fiber, 0.1g polyethylene glycol, 0.5g starch, and 100g water; repeatedly immerse the cordierite carrier pretreated in step 1) in the coating solution until the surface of the carrier is uniformly coated with a layer of coating solution, then blow it clean and place it in an oven to dry at 80℃ for 4h to obtain the precursor;

[0108] 3) The precursor was placed in a muffle furnace and calcined at 115°C for 6 hours to obtain catalyst I with a coating layer, wherein the weight percentage of the coating layer was 10%; the catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 70%. During the application, the coating layer of the catalyst did not peel off and could be reused.

[0109] As can be seen from the comparison between Example 6 and Examples 1 and 7, adding MnO2 and CeO2 as active components in the coating solution in a ratio of 100:1 to 100:3 helps to further improve the catalytic activity of the ozone catalyst and enhance the COD removal capacity.

[0110] Example 8 (without glass fiber and polyethylene glycol)

[0111] The process was carried out in accordance with Example 1, except that glass fiber and polyethylene glycol were not added to the coating solution.

[0112] The catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 66%.

[0113] Compared to Example 1 and other examples, this embodiment does not contain glass fiber and polyethylene glycol in the coating solution. The coating layer on the catalyst surface is not as uniform and smooth as in other examples. The uniformity and smoothness are significantly reduced compared to other examples, and therefore the risk of coating layer peeling is increased compared to other examples.

[0114] Comparative Example 3: (Using water glass instead of silica sol)

[0115] This comparative example is based on Example 1, except that the silica sol in the coating solution is replaced with an equal weight of water glass.

[0116] After low-temperature calcination, when the calcined catalyst was removed, severe peeling was found on the surface; the coating would peel off with a light touch (see actual catalyst image). Figure 2 Since it could not be evaluated in the reaction system, no further performance tests were conducted.

[0117] In the above embodiments and comparative examples, the performance evaluation of the catalyst in treating organic wastewater was carried out according to the following procedures:

[0118] The obtained catalyst in Figure 3 Organic wastewater was treated using the catalytic ozonation experimental apparatus shown. Ozone generator 1 was turned on and preheated for 30 minutes. Two catalyst pieces 4 (approximately 95g each; for comparative example 2, the same mass of spherical catalyst) were placed in glass reactor 3, and 250mL of organic wastewater sample was added. After 1 hour of adsorption, ozone was introduced into the reactor through a pipeline from the ozone generator's ozone outlet (gas flow rate 0.2L / min, inlet ozone concentration 40mg / L). The ozone gas generated by the ozone generator flowed through a pipeline equipped with a flow meter into the reactor, where it formed fine bubbles at the bottom of the reactor via a porous gas distribution plate. These bubbles contacted the catalyst and organic wastewater, resulting in a gas-liquid-solid three-phase reaction. The reaction time was 2 hours. The chemical oxygen demand (COD) in the water was measured using a Hach analyzer. Finally, the COD removal rate of the organic wastewater after catalyst treatment was determined.

[0119] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom remain within the scope of protection of this invention.

Claims

1. Use of a cordierite-based supported ozonation catalyst, characterized in that, The ozone oxidation catalyst is applied in treatment of organic wastewater generated in the field of coal chemical industry, and a preparation method of the ozone oxidation catalyst comprises the following steps: 1) a porous cordierite is pretreated in an acidic solution, and then cleaned and dried to obtain a carrier; 2) a coating liquid is applied on the carrier, and then dried to obtain a precursor; the coating liquid comprises the following components in parts by weight: 50-100 parts of MnO2, 0-3 parts of CeO2, 10-15 parts of silica sol, 0-0.3 parts of glass fiber, 0-0.15 parts of polyethylene glycol, 0-0.5 parts of starch and 100 parts of water, wherein the weight of the silica sol is calculated based on the silicon dioxide contained therein; 3) the precursor is calcined at 100-150 DEG C to obtain a supported ozone oxidation catalyst with a coating layer formed on the carrier.

2. Use according to claim 1, characterized in that, In step 1), the pH of the acidic solution is 2-4.

3. Use according to claim 2, characterized in that, In step 1), the acidic solution is selected from an aqueous hydrochloric acid solution and / or an aqueous nitric acid solution.

4. Use according to claim 2, characterized in that, In step 1), the pretreatment comprises soaking the porous cordierite in the acidic solution for 10-12 h.

5. The use according to claim 1, characterized in that, In step (2), the parts by weight of the MnO2 is 90-100 parts; the parts by weight of the glass fiber is 0.1-0.3 parts, and the parts by weight of the polyethylene glycol is 0.05-0.15 parts.

6. Use according to claim 5, characterized in that, The weight ratio of the MnO2 to the CeO2 satisfies 50-100:1-3.

7. Use according to claim 6, characterized in that, The weight ratio of the MnO2 to the CeO2 satisfies 100:1-3.

8. Use according to claim 5, characterized in that, In step 2), the carrier is immersed in the coating liquid so that the surface of the carrier is attached with a coating liquid layer.

9. Use according to any one of claims 1 to 8, characterized in that, In step 3), the calcination is performed at 100-150 DEG C for 4-10 h.

10. Use according to any one of claims 1 to 8, characterized in that, Based on the weight of the supported ozone catalyst, the weight percentage of the coating layer is 5-20%.

11. Use according to claim 10, characterized in that, Based on the weight of the supported ozone catalyst, the weight percentage of the coating layer is 10-20%.

12. Use according to any one of claims 1 to 8, characterized in that, In the coating liquid, the weight ratio of the MnO2 to the CeO2 satisfies 100:1-3; and, based on the weight of the supported ozone oxidation catalyst, the weight percentage of the coating layer is 10-20%.

13. Use according to any one of claims 1 to 8, characterized in that, The porous cordierite is a honeycomb-shaped cordierite.

14. Use according to claim 13, characterized in that, The porous cordierite has a regular shape.

15. Use according to claim 14, characterized in that, The overall shape of the porous cordierite is a cuboid or a square, or is approximately a cuboid or a square.

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