A porous cordierite-based ozone catalyst and a preparation method and application thereof

Abstract

The application provides a kind of porous cordierite-based ozone catalyst and its preparation method and application, based on the preparation method of the application, ozone catalyst is prepared, the obtained ozone catalyst can give consideration to good mechanical properties and wastewater treatment effect.The preparation method comprises the following steps:1) applying coating liquid on pretreated porous cordierite, the coating liquid comprises manganese dioxide, silica sol and water;2) the porous cordierite to which the coating liquid is applied in step 1) is dried at 120-200 DEG C, to obtain the ozone catalyst with coating layer formed on the porous cordierite.In step 1), the manganese dioxide is prepared by the following method: KMnO4 aqueous solution and Mn (NO3) 2 aqueous solution are stirred and reacted at 15-35 DEG C, the obtained reaction product is filtered, the filter cake is washed with water, and the filter cake is dried and then heat treated at a temperature of 180-300 DEG C.

Description

Technical Field

[0001] This invention relates to ozone catalysts suitable for the treatment of organic wastewater, specifically to an ozone catalyst, its preparation method, and its application. Background Technology

[0002] Advanced oxidation technologies (AOCs) are highly efficient wastewater treatment technologies that decompose organic matter in water by generating highly oxidizing hydroxyl radicals, which then mineralize it into CO2 and H2O. Ozone catalytic oxidation is one of the most widely used AOC methods in engineering applications. Ozone catalytic oxidation technologies often employ heterogeneous ozone catalysts, primarily supported particulate catalysts, which are packed into a reaction tower in a fixed-bed configuration for a gas-liquid-solid three-phase reaction. However, solid particles are prone to pulverization and breakage during application, presumably due to particle collisions caused by airflow and water flow, resulting in mechanical damage to the catalyst. Furthermore, fluid flow can easily create channeling between particles, reducing catalyst utilization.

[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 specific 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.

[0004] Patent application CN201711065843.X relates to a method for preparing a heterogeneous ozone catalyst, its products, and applications. The preparation method mainly includes hydrothermal growth of nickel oxide nanosheets on the surface of cordierite honeycomb ceramics and growth of zinc oxide nanorods on the surface of cordierite honeycomb ceramics on which nickel oxide nanosheets have been grown.

[0005] Patent application CN201510508937.4 discloses a high-salt ozone resistant catalyst, which is 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 preparation process involves mixing the components in a mixer to prepare a coating solution, immersing the activated alumina particles in the coating solution, and then drying and calcining them to obtain the high-salt ozone resistant catalyst.

[0006] 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

[0007] This invention provides an ozone catalyst based on porous cordierite, its preparation method, and its application. The ozone catalyst prepared by the method of this invention has a simple preparation process, low energy consumption, and the obtained ozone catalyst can achieve both good mechanical properties and wastewater treatment effect, and is particularly suitable for treating organic wastewater generated in the coal chemical industry.

[0008] To achieve its objective, the present invention provides the following technical solution:

[0009] This invention provides a method for preparing an ozone catalyst based on porous cordierite, comprising the following steps:

[0010] 1) Apply a coating liquid to pretreated porous cordierite, the coating liquid comprising manganese dioxide, silica sol and water;

[0011] 2) Dry the porous cordierite with the coating liquid applied in step 1) at 120-200°C to obtain an ozone catalyst with a coating layer formed on the porous cordierite.

[0012] In step 1), the manganese dioxide is prepared by a method including the following steps: stirring and reacting KMnO4 aqueous solution and Mn(NO3)2 aqueous solution at 15-35°C, filtering the resulting reaction product, washing the filter cake with water, drying the filter cake, and then heat-treating it at 180-300°C.

[0013] In some embodiments, the temperature of the heat treatment is 180-220°C;

[0014] And / or, the molar ratio of KMnO4 to Mn(NO3)2 is 1:1.1-3.5, preferably 1:1.5-2.5, and more preferably 1:2.0-2.5;

[0015] And / or, the heat treatment time is 3-6 hours.

[0016] In some embodiments, step 1) includes: pretreating porous cordierite in an alkaline solution, followed by washing and drying;

[0017] Preferably, the pH of the alkaline solution is 10-12; preferably, the alkaline solution is selected from aqueous solutions of sodium hydroxide and / or potassium hydroxide.

[0018] Preferably, the pretreatment is carried out at 60-100℃, and the pretreatment time is preferably 6-10h.

[0019] In some embodiments, in step 1), the weight ratio of water, silica sol, and manganese dioxide in the coating liquid is 100-150:12.5-37.5:100, wherein the weight of the silica sol is based on the amount of silicon dioxide it contains.

[0020] Preferably, the weight ratio of water, silica sol, and manganese dioxide is 100-150:20-30:100, wherein the weight of silica sol is based on the amount of silica it contains.

[0021] In some embodiments, in step 2), the drying is carried out at 120–150°C.

[0022] In some embodiments, in step 1), the porous cordierite is immersed in the coating liquid to allow the coating liquid to adhere to the carrier; preferably, during the immersion process, the porous cordierite is repeatedly immersed multiple times.

[0023] In some embodiments, the coating layer comprises 3%-10% by weight, preferably 3%-5%, based on the total weight of the ozone catalyst.

[0024] In some embodiments, in the method for preparing the manganese dioxide, the heat treatment temperature is 180-220°C, and the molar ratio of KMnO4 to Mn(NO3)2 is 1:1.5-2.5, preferably 1:2.0-2.5;

[0025] In step 1), the weight ratio of water, silica sol, and manganese dioxide in the coating liquid is 100-150:20-30:100, wherein the weight of silica sol is based on the amount of silica it contains.

[0026] In step 2), the drying is carried out at 120–150°C;

[0027] The coating layer comprises 3%-5% by weight, based on the total weight of the ozone catalyst.

[0028] In some embodiments, the porous cordierite is honeycomb cordierite;

[0029] And / or, the porous cordierite has a regular and well-formed shape.

[0030] The present invention also provides an ozone catalyst based on porous cordierite prepared by the preparation method described above.

[0031] The present invention also provides an application in which the ozone catalyst obtained by the preparation method described above or the ozone catalyst described above is used in the treatment of organic wastewater, especially organic wastewater generated in the coal chemical industry.

[0032] The technical solution provided by this invention has the following beneficial effects:

[0033] The preparation method provided by this invention involves loading manganese dioxide, an active ingredient, onto porous cordierite using a coating liquid and then drying it in one step using a low-temperature drying method. This method features a simple preparation process, low energy consumption, and the ability to quickly and easily obtain an ozone catalyst. Furthermore, the provided ozone catalyst exhibits good catalytic reaction efficiency, good mechanical properties, and is not easily detached, thus reducing mechanical loss. Attached Figure Description

[0034] Figure 1 The diagram shown is a schematic of the experimental apparatus for catalytic ozonation.

[0035] Figure 2 The image shown is a schematic diagram of an ozone catalyst obtained in one embodiment.

[0036] Figure 3 This is a scanning electron microscope image of commercially available manganese dioxide used in one embodiment.

[0037] Figure 4 This is a scanning electron microscope image of the self-made manganese dioxide used in one embodiment.

[0038] Figure 1 The following are the labels in the attached diagram: 1. Ozone generator, 2. Ozone concentration detector, 3. Reactor, 4. Catalyst. Detailed Implementation

[0039] 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.

[0040] 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.

[0041] 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.

[0042] This invention provides a method for preparing an ozone catalyst based on porous cordierite, which mainly includes the following steps:

[0043] 1) Apply a coating solution to the pretreated porous cordierite, the coating solution comprising manganese dioxide, silica sol and water;

[0044] 2) Dry the porous cordierite with the coating liquid applied in step 1) at 120-200°C to obtain an ozone catalyst with a coating layer formed on the porous cordierite.

[0045] In step 1), manganese dioxide is prepared by a method including the following steps: stirring and reacting KMnO4 aqueous solution and Mn(NO3)2 aqueous solution at 15-35℃ (e.g., room temperature), filtering the resulting reaction product, washing the filter cake with water, drying the filter cake, and then heat-treating it at 180-300℃.

[0046] Using the above-mentioned preparation method of the present invention, an ozone catalyst is prepared by applying a coating liquid containing manganese dioxide and silica sol prepared by a specific process to porous cordierite and then drying it at low temperature in one step. This method has the advantages of short process flow, simple operation, low energy consumption, and the ozone catalyst obtained can well balance mechanical properties (the coating layer is not easy to fall off) and catalytic activity. It can be used to treat organic wastewater, especially high-salt organic wastewater in the coal chemical industry, and has the characteristics of high COD removal efficiency and reusability.

[0047] The inventors have discovered that the manganese dioxide prepared by the preferred process in the preparation method of the present invention has a microscopic morphology of a multi-level structure similar to microalgae. The ozone catalyst prepared by preparing the coating solution of the present invention by combining the manganese dioxide obtained by this method with silica sol and applying it to porous cordierite and drying it at low temperature has significantly improved reaction activity and can significantly improve the COD removal rate of organic wastewater.

[0048] In a preferred embodiment, manganese dioxide is heat-treated at 180-220°C. The inventors have found that using this preferred temperature for heat treatment results in manganese dioxide being combined with cordierite and other materials to prepare an ozone catalyst based on the method of this invention, and the resulting catalyst exhibits significantly improved performance. In some embodiments, the heat treatment time for manganese dioxide preparation is 3-6 hours. In a specific embodiment, the filter cake is washed with water, particularly hot water, to remove unreacted portions during manganese dioxide preparation, for example, with hot water at a temperature of 50-70°C until the filtrate is clear. The filter cake is then dried at 60-80°C, for example, for 10-16 hours. Furthermore, the heat-treated manganese dioxide is ground to obtain manganese dioxide powder, which is used in the subsequent preparation of the coating solution.

[0049] In a preferred embodiment, when preparing manganese dioxide, the molar ratio of KMnO4 to Mn(NO3)2 is 1:1.1-3.5, preferably 1:1.5-2.5, and more preferably 1:2.0-2.5. The manganese dioxide prepared using the preferred molar ratio is used to prepare an ozone catalyst by the method of the present invention, and the resulting catalyst has a better COD removal effect.

[0050] In step 1), applying a coating liquid to porous cordierite includes applying the coating liquid to the outer and inner surfaces (e.g., the surfaces of the internal pores) of the porous cordierite.

[0051] In some preferred embodiments, in step 1), the pH of the alkaline solution used in the pretreatment of porous cordierite is 10-12; preferably, the pretreatment is carried out at 60-100°C for 6-10 hours. The inventors have found that pretreatment of the porous cordierite support in an alkaline solution facilitates the formation of a uniform and robust coating layer on the support surface by the subsequent coating solution, and ultimately leads to a high-performance ozone catalyst. In some embodiments, the alkaline solution is selected from aqueous solutions of sodium hydroxide and / or potassium hydroxide.

[0052] In some preferred embodiments, in step 1), the weight ratio of water, silica sol, and manganese dioxide in the coating solution is 100-150:12.5-37.5:100, wherein the weight of the silica sol is based on the amount of silica it contains. Preferably, the weight ratio of water, silica sol, and manganese dioxide is 100-150:20-30:100, wherein the weight of the silica sol is based on the amount of silica it contains. Using a coating solution with the preferred composition ratio facilitates the uniform and relatively firm coating of active manganese dioxide onto the carrier surface, and is beneficial for ultimately obtaining a catalyst with excellent activity. Using a coating solution with the preferred composition ratio makes it easy to obtain the required coating amount and reduces the likelihood of uneven coating and a decrease in the effective pore area.

[0053] In some embodiments, in step 1), the porous cordierite is immersed in the coating solution to allow the coating solution to adhere to the carrier; preferably, the porous cordierite is repeatedly immersed multiple times to ensure that the coating solution covers both the inner and outer surfaces of the carrier. This preferred method of applying the coating solution facilitates uniform contact between the inner and outer surfaces of the porous cordierite and the coating solution, resulting in a uniform coating layer and thus improving the performance of the ozone catalyst.

[0054] In a preferred embodiment, step 2) involves drying the support coated with the coating solution in step 1) at a low temperature of 120–150°C to obtain an ozone catalyst resistant to high salt content (≤50,000 mg / L); drying can be performed, for example, in a muffle furnace. The inventors have found that the ozone catalyst prepared under the preferred low-temperature drying conditions exhibits excellent mechanical properties and good catalytic activity. Specifically, in step 3), the support coated with the coating solution is dried until the catalyst reaches a constant weight and its mass no longer decreases (for example, this can be determined by weighing every 1 hour after 6 hours).

[0055] The ozone catalyst prepared using the method of this invention does not require a relatively high coating loading and can achieve good treatment results in treating organic wastewater, obtaining a high COD removal rate and saving costs. In some embodiments, the weight percentage of the coating layer is 3%-10% based on the total weight of the ozone catalyst, preferably 3%-5%.

[0056] In a preferred embodiment, in the method for preparing manganese dioxide, the heat treatment temperature is 180-220℃, and the molar ratio of KMnO4 to Mn(NO3)2 is 1:1.5-2.5, preferably 1:1.5-2.5; in step 1), the weight ratio of water, silica sol, and manganese dioxide in the coating solution is 100-150:20-30:100, wherein the weight of the silica sol is based on the amount of silicon dioxide it contains; in step 2), drying is carried out at 120-150℃; based on the total weight of the ozone catalyst, the weight percentage of the coating layer is 3%-5%. The ozone catalyst prepared based on the preferred combination of conditions has better overall performance, combining superior catalytic activity and mechanical properties, and achieving better COD removal effect.

[0057] In a preferred embodiment, the porous cordierite is honeycomb cordierite, which has honeycomb-shaped channels that can achieve fixed spatial distribution and transport of liquids and gases, reducing the scouring and collision of fluids on the catalyst. At the same time, the abundant channel structure provides more active sites for the catalytic reaction, which is beneficial for the ozone-catalyzed decomposition of COD.

[0058] In a preferred embodiment, the porous cordierite used in this invention has a regularly shaped form, i.e., it is a carrier with a regular structure, such as a cuboid, cube, or roughly cube or cuboid shape. When an ozone catalyst is made using a carrier with a regular structure, it is beneficial to have a more uniform gas-liquid distribution when used for organic wastewater treatment, thereby improving the catalytic reaction efficiency. Moreover, during use, it can reduce collisions caused by catalyst displacement, thereby further reducing catalyst mechanical loss.

[0059] The present invention also provides an ozone catalyst based on porous cordierite, which can be obtained by the preparation method described above.

[0060] This invention also provides the ozone catalyst obtained by the preparation method described above, or the ozone catalyst described above, for use in the treatment of organic wastewater, particularly for the treatment of organic wastewater generated in the coal chemical industry, specifically, for example, high-salt organic wastewater (e.g., salt content ≤ 60000 mg / L) in the coal chemical industry. The inventors have found that the ozone catalyst provided by this invention is very suitable for the treatment of high-salt organic wastewater in the coal chemical industry, not only achieving a high COD removal rate but also exhibiting good mechanical properties, which helps reduce mechanical loss.

[0061] The present invention will be illustrated below with reference to embodiments:

[0062] The organic wastewater involved in the following examples or comparative examples is high-salt organic wastewater from coal chemical industry, and its various indicators are as follows:

[0063]

[0064] Performance evaluation of catalysts for treating organic wastewater:

[0065] The catalysts obtained in each embodiment or comparative example are used in... Figure 1 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) were placed in glass reactor 3, and 250mL of organic wastewater sample was added. After adsorption for 1 hour, ozone was introduced into the reactor through a pipeline from the ozone outlet of the ozone generator (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.

[0066] 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%.

[0067] Example 1

[0068] In this embodiment, the manganese dioxide used is prepared by the following steps:

[0069] Prepare a 12.6 mmol / L KMnO4 aqueous solution and a 19.0 mmol / L Mn(NO3)2 aqueous solution. Take 100 ml of the above KMnO4 aqueous solution and place it in a beaker. Add 100 ml of the above Mn(NO3)2 aqueous solution at room temperature and stirring at 1000 r / min, and continue stirring for 4 h. After the reaction is complete, immediately filter out the unreacted part by vacuum filtration. Wash repeatedly with hot water. Stop filtration after the filtrate is clear. Place the filter cake in an oven and dry at 80 °C for 10 h. Place the dried sample in a muffle furnace and heat treat at 200 °C for 4 h. Take it out and grind it thoroughly in a mortar to obtain black manganese dioxide powder. Seal and store for later use.

[0070] Pretreatment of porous cordierite: Commercially available honeycomb cordierite was cut into regular structures with length × width × height = 40mm × 40mm × 80mm, and soaked in a sodium hydroxide aqueous solution with pH 12 for 6 hours in a water bath at 80℃ for pretreatment. Then it was washed and dried to serve as a carrier.

[0071] The preparation of ozone catalysts includes the following steps:

[0072] 1) Prepare a coating solution by mixing 100g of the above MnO2 black powder, 100mL of silica sol (containing 25g of silica), and 100g of water. Place the coating solution in a ball mill jar and ball mill at 3500r / min for 30min.

[0073] 2) Immerse the pretreated cordierite support in the above coating solution, repeating the immersion operation multiple times until the surface of the support is uniformly coated with a layer of coating solution; blow the coated catalyst precursor clean and dry it in an oven at 120℃ for 6 hours; obtain catalyst A according to the above steps, wherein the weight percentage of the coating layer is 5%. This catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 65%. There was no coating layer peeling during the application, and the catalyst can be reused multiple times.

[0074] Comparative Example 1

[0075] In this embodiment, the manganese dioxide used is prepared by the following steps:

[0076] Prepare a 12.6 mmol / L KMnO4 aqueous solution and a 19.0 mmol / L Mn(NO3)2 aqueous solution. Take 100 mL of the above KMnO4 aqueous solution and place it in a beaker. Add 100 mL of the above Mn(NO3)2 aqueous solution at room temperature and stirring at 1000 r / min, and continue stirring for 4 h. After the reaction is complete, immediately filter out the unreacted part by vacuum filtration. Wash repeatedly with hot water. Stop filtration after the filtrate is clear. Place the filter cake in an oven and dry at 80 °C for 10 h. Place the dried sample in a muffle furnace and heat treat at 400 °C for 4 h. Take it out and grind it thoroughly in a mortar to obtain black manganese dioxide powder. Seal and store for later use.

[0077] Pretreatment of porous cordierite: Commercially available honeycomb cordierite was cut into regular structures with length × width × height = 40mm × 40mm × 80mm, and pretreated by soaking it in a sodium hydroxide aqueous solution with pH 12 at 80℃ for 6 hours. Then it was washed and dried to serve as a carrier.

[0078] The preparation of ozone catalysts includes the following steps:

[0079] 1) Prepare a coating solution by mixing 100g of the above MnO2 black powder, 100mL of silica sol (containing 25g of silica), and 100g of water. Place the coating solution in a ball mill jar and ball mill at 3500r / min for 30min.

[0080] 2) The pretreated cordierite support was immersed in the above coating solution, and the immersion operation was repeated several times until the surface of the support was uniformly coated with a layer of coating solution; the coated catalyst precursor was blown clean and placed in an oven to dry at 120℃ for 6 hours; catalyst B was obtained according to the above steps, wherein the weight percentage of the coating layer was 5%. The catalyst was used to treat high-salt organic wastewater from a coal chemical industry, and the COD removal rate was 47%.

[0081] The main difference between this comparative example and Example 1 is that the manganese dioxide was heat-treated at 400°C during preparation, resulting in a decrease in the activity of the ozone catalyst and a significant reduction in COD removal efficiency.

[0082] Example 2

[0083] In this embodiment, the manganese dioxide used is prepared by the following steps:

[0084] Prepare a 12.6 mmol / L KMnO4 aqueous solution and a 19.0 mmol / L Mn(NO3)2 aqueous solution;

[0085] Take 100 mL of the above KMnO4 solution and place it in a beaker. Add 100 mL of the above Mn(NO3)2 aqueous solution at room temperature and stirring at 1000 r / min, and continue stirring for 4 h.

[0086] Immediately after the reaction is complete, use vacuum filtration to remove the unreacted portion, wash repeatedly with hot water, and stop filtration after the filtrate is clear. Place the filter cake in an oven and dry at 80°C for 10 hours.

[0087] The dried sample was placed in a muffle furnace and heat-treated at 300°C for 4 hours. It was then removed and thoroughly ground in a mortar to obtain black manganese dioxide powder, which was then sealed and stored for later use.

[0088] Pretreatment of porous cordierite:

[0089] Commercially available honeycomb cordierite was cut into regular structures with a length × width × height of 40mm × 40mm × 80mm. It was then pretreated by soaking it in a sodium hydroxide aqueous solution with a pH of 12 and water bath at 80℃ for 6 hours. After that, it was washed and dried to serve as a carrier.

[0090] The preparation of ozone catalysts includes the following steps:

[0091] 1) Prepare a coating solution by mixing 100g of the above MnO2 black powder, 100mL of silica sol (containing 25g of silica), and 100g of water. Place the coating solution in a ball mill jar and ball mill at 3500r / min for 30min.

[0092] 2) The pretreated cordierite support was immersed in the above coating solution, and the immersion operation was repeated several times until the surface of the support was uniformly coated with a layer of coating solution; the coated catalyst precursor was blown clean and placed in an oven to dry at 120℃ for 6 hours; catalyst C was obtained according to the above steps, 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 50%; no coating layer peeling occurred during the application, and the catalyst could be reused multiple times.

[0093] The main difference between this comparative example and Example 1 is that the manganese dioxide was heat-treated at 300°C during preparation. As a result, the activity of the ozone catalyst decreased, and the COD removal effect was inferior to that of Example 1.

[0094] Example 3

[0095] In this embodiment, the manganese dioxide used is prepared by the following steps:

[0096] Prepare a 12.6 mmol / L KMnO4 aqueous solution and a 19.0 mmol / L Mn(NO3)2 aqueous solution;

[0097] Take 100 ml of the above KMnO4 aqueous solution and place it in a beaker. Add 100 ml of the above Mn(NO3)2 aqueous solution at room temperature and stirring at 1000 r / min, and continue stirring for 4 h.

[0098] Immediately after the reaction is complete, use vacuum filtration to remove the unreacted portion, wash repeatedly with hot water, and stop filtration after the filtrate is clear. Place the filter cake in an oven and dry at 80°C for 16 hours.

[0099] The dried sample was heat-treated in a muffle furnace at 200°C for 4 hours, then removed and thoroughly ground in a mortar to obtain black manganese dioxide powder (see scanning electron microscope image). Figure 4 Seal and store for later use.

[0100] Pretreatment of porous cordierite:

[0101] Commercially available honeycomb cordierite was cut into regular structures with a length × width × height of 40mm × 40mm × 80mm. It was then pretreated by soaking it in a sodium hydroxide aqueous solution with a pH of 12 and water bath at 80℃ for 6 hours. After that, it was washed and dried to serve as a carrier.

[0102] The preparation of ozone catalysts includes the following steps:

[0103] 1) Prepare a coating solution by mixing 100g of the above MnO2 black powder, 50mL of silica sol (silica content is 12.5g) and 100g of water. Place the coating solution in a ball mill jar and ball mill at 3500r / min for 30min.

[0104] 2) Immerse the pretreated cordierite support in the above coating solution, repeating the immersion operation multiple times until the surface of the support is uniformly coated with a layer of coating solution; blow the coated catalyst precursor clean and dry it in an oven at 120℃ for 6 hours; obtain catalyst D according to the above steps, wherein the weight percentage of the coating layer is 3%. This catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 48%. There was no coating layer peeling during the application, and the catalyst can be reused multiple times.

[0105] Example 4

[0106] In this embodiment, the manganese dioxide used is prepared by the following steps:

[0107] Prepare a 12.6 mmol / L KMnO4 aqueous solution and a 19.0 mmol / L Mn(NO3)2 aqueous solution;

[0108] Take 100 ml of the above KMnO4 solution and place it in a beaker. Add 100 ml of the above Mn(NO3)2 aqueous solution at room temperature and stirring at 1000 r / min, and continue stirring for 4 h.

[0109] Immediately after the reaction is complete, use vacuum filtration to remove the unreacted portion, wash repeatedly with hot water, and stop filtration after the filtrate is clear. Place the filter cake in an oven and dry at 80°C for 16 hours.

[0110] The dried sample was placed in a muffle furnace and heat-treated at 200°C for 4 hours. It was then removed and thoroughly ground in a mortar to obtain black manganese dioxide powder, which was then sealed and stored for later use.

[0111] Pretreatment of porous cordierite:

[0112] Commercially available honeycomb cordierite was cut into regular structures with a length × width × height of 40mm × 40mm × 80mm. It was then pretreated by soaking it in a sodium hydroxide aqueous solution with a pH of 12 and water bath at 80℃ for 6 hours. After that, it was washed and dried to serve as a carrier.

[0113] The preparation of ozone catalysts includes the following steps:

[0114] 1) Prepare a coating solution by mixing 100g of the above MnO2 black powder, 150mL of silica sol (silica content is 37.5g) and 100g of water. Place the coating solution in a ball mill jar and ball mill at 3500r / min for 30min.

[0115] 2) Immerse the pretreated cordierite support in the above coating solution, repeating the immersion operation multiple times until the surface of the support is uniformly coated with a layer of coating solution; blow the coated catalyst precursor clean and dry it in an oven at 120℃ for 6 hours; obtain catalyst E according to the above steps, wherein the weight percentage of the coating layer is 10%. This catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 58%. There was no coating layer peeling during the application, and the catalyst can be reused multiple times.

[0116] Example 5

[0117] In this embodiment, the manganese dioxide used is prepared by the following steps:

[0118] Prepare a 12.6 mmol / L KMnO4 aqueous solution and a 19.0 mmol / L Mn(NO3)2 aqueous solution;

[0119] Take 100 ml of the above KMnO4 aqueous solution and place it in a beaker. Add 150 ml of the above Mn(NO3)2 solution at room temperature and stirring at 1000 r / min, and continue stirring for 4 h.

[0120] Immediately after the reaction is complete, use vacuum filtration to remove the unreacted portion, wash repeatedly with hot water, and stop filtration after the filtrate is clear. Place the filter cake in an oven and dry at 80°C for 10 hours.

[0121] The dried sample was placed in a muffle furnace and heat-treated at 200°C for 4 hours. It was then removed and thoroughly ground in a mortar to obtain black manganese dioxide powder, which was then sealed and stored for later use.

[0122] Pretreatment of porous cordierite:

[0123] Commercially available honeycomb cordierite was cut into regular structures with a length × width × height of 40mm × 40mm × 80mm. It was then pretreated by soaking it in a sodium hydroxide aqueous solution with a pH of 12 and water bath at 80℃ for 6 hours. After that, it was washed and dried to serve as a carrier.

[0124] The preparation of ozone catalysts includes the following steps:

[0125] 1) Prepare a coating solution by mixing 100g of the above MnO2 black powder, 100mL of silica sol (containing 25g of silica), and 100g of water. Place the coating solution in a ball mill jar and ball mill at 3500r / min for 30min.

[0126] 2) The pretreated cordierite support was immersed in the above coating solution, and the immersion operation was repeated several times until the surface of the support was uniformly coated with a layer of coating solution; the coated catalyst precursor was blown clean and placed in an oven to dry at 120℃ for 6 hours; catalyst F was obtained according to the above steps, 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 67%. There was no coating layer peeling during the application, and the catalyst could be reused multiple times.

[0127] Example 6

[0128] In this embodiment, the manganese dioxide used is prepared by the following steps:

[0129] Prepare a 12.6 mmol / L KMnO4 aqueous solution and a 19.0 mmol / L Mn(NO3)2 aqueous solution;

[0130] Take 100 ml of the above KMnO4 aqueous solution and place it in a beaker. Add 200 ml of the above Mn(NO3)2 aqueous solution at room temperature and stirring at 1000 r / min, and continue stirring for 4 h.

[0131] Immediately after the reaction is complete, use vacuum filtration to remove the unreacted portion, wash repeatedly with hot water, and stop filtration after the filtrate is clear. Place the filter cake in an oven and dry at 80°C for 10 hours.

[0132] The dried sample was placed in a muffle furnace and heat-treated at 200°C for 4 hours. It was then removed and thoroughly ground in a mortar to obtain black manganese dioxide powder, which was then sealed and stored for later use.

[0133] Pretreatment of porous cordierite:

[0134] Commercially available honeycomb cordierite was cut into regular structures with a length × width × height of 40mm × 40mm × 80mm. It was then pretreated by soaking it in a sodium hydroxide aqueous solution with a pH of 12 and water bath at 80℃ for 6 hours. After that, it was washed and dried to serve as a carrier.

[0135] The preparation of ozone catalysts includes the following steps:

[0136] 1) Prepare a coating solution by mixing 100g of the above MnO2 black powder, 100mL of silica sol (containing 25g of silica), and 100g of water. Place the coating solution in a ball mill jar and ball mill at 3500r / min for 30min.

[0137] 2) Immerse the pretreated cordierite support in the above coating solution, repeating the immersion operation multiple times until the surface of the support is uniformly coated with a layer of coating solution; blow the coated catalyst precursor clean and dry it in an oven at 120℃ for 6 hours; obtain catalyst G according to the above steps, wherein the weight percentage of the coating layer is 5%. This catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 62%. There was no coating layer peeling during the application, and the catalyst can be reused multiple times.

[0138] Comparing Examples 1, 5, and 6, it can be seen that when preparing manganese dioxide, Examples 1 and 5 use a molar ratio of 1:1.5-2.5 to add KMnO4 and Mn(NO3)2, and the resulting catalyst has better activity and better COD removal effect.

[0139] Example 7

[0140] In this embodiment, the manganese dioxide used is prepared by the following steps:

[0141] Prepare a 12.6 mmol / L KMnO4 aqueous solution and a 19.0 mmol / L Mn(NO3)2 aqueous solution;

[0142] Take 100 ml of the above KMnO4 aqueous solution and place it in a beaker. Add 100 ml of the above Mn(NO3)2 solution at room temperature and stirring at 1000 r / min, and continue stirring for 4 h.

[0143] Immediately after the reaction is complete, use vacuum filtration to remove the unreacted portion, wash repeatedly with hot water, and stop filtration after the filtrate is clear. Place the filter cake in an oven and dry at 80°C for 10 hours.

[0144] The dried sample was placed in a muffle furnace and heat-treated at 200°C for 4 hours. It was then removed and thoroughly ground in a mortar to obtain black manganese dioxide powder, which was then sealed and stored for later use.

[0145] Pretreatment of porous cordierite:

[0146] Commercially available honeycomb cordierite was cut into regular structures with a length × width × height of 40mm × 40mm × 80mm. It was then pretreated by soaking it in a sodium hydroxide aqueous solution with a pH of 12 and water bath at 80℃ for 6 hours. After that, it was washed and dried to serve as a carrier.

[0147] The preparation of ozone catalysts includes the following steps:

[0148] 1) Prepare a coating solution by mixing 100g of the above MnO2 black powder, 100mL of silica sol (containing 25g of silica), and 100g of water. Place the coating solution in a ball mill jar and ball mill at 3500r / min for 30min.

[0149] 2) The pretreated cordierite support was immersed in the above coating solution, and the immersion operation was repeated several times until the surface of the support was uniformly coated with a layer of coating solution; the coated catalyst precursor was blown clean and dried in an oven at 200℃ for 6 hours; catalyst I was obtained according to the above steps, 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, slight peeling of the coating layer occurred.

[0150] Compared with Example 1, the main difference in this embodiment is that the coating layer is dried at 200°C after coating. As a result, the COD removal effect of the catalyst decreases during application, and the coating layer shows slight peeling.

[0151] Comparative Example 2

[0152] Commercially available honeycomb cordierite was cut into regular structures with a length × width × height of 40mm × 40mm × 80mm as a carrier. It was pretreated by soaking it in a sodium hydroxide aqueous solution with a pH of 12 and then in a water bath at 80℃ for 6 hours. Then it was cleaned and dried.

[0153] 100g of MnO2 (commercially available, its scanning electron microscope image is shown below) was used. Figure 3 A coating solution was prepared by mixing 50 mL of silica sol (containing 12.5 g of silica) and 100 g of water. The coating solution was then ball-milled at 3500 rpm for 30 min. The pretreated support was immersed in the coating solution repeatedly until a uniform coating layer was formed on the support surface. Excess coating solution was then removed by purging. The support was dried in an oven at 120°C for 6 h to obtain the catalyst. The coating layer comprised 3% of the catalyst by weight. This catalyst was used to treat high-salt organic wastewater from a coal chemical plant, achieving a COD removal rate of 43%.

[0154] Comparative Example 3

[0155] In this embodiment, the manganese dioxide used is prepared by the following steps:

[0156] Prepare a 12.6 mmol / L KMnO4 aqueous solution and a 19.0 mmol / L Mn(NO3)2 aqueous solution;

[0157] Take 100 ml of the above KMnO4 aqueous solution and place it in a beaker. Add 100 ml of the above Mn(NO3)2 solution at room temperature and stirring at 1000 r / min, and continue stirring for 4 h.

[0158] Immediately after the reaction is complete, use vacuum filtration to remove the unreacted portion, wash repeatedly with hot water, and stop filtration after the filtrate is clear. Place the filter cake in an oven and dry at 80°C for 10 hours.

[0159] The dried sample was placed in a muffle furnace and heat-treated at 200°C for 4 hours. It was then removed and thoroughly ground in a mortar to obtain black manganese dioxide powder, which was then sealed and stored for later use.

[0160] Pretreatment of porous cordierite:

[0161] Commercially available honeycomb cordierite was cut into regular structures with a length × width × height of 40mm × 40mm × 80mm. It was then pretreated by soaking it in a sodium hydroxide aqueous solution with a pH of 12 and water bath at 80℃ for 6 hours. After that, it was washed and dried to serve as a carrier.

[0162] The preparation of ozone catalysts includes the following steps:

[0163] 1) Prepare a coating solution by mixing 100g of the above MnO2 black powder, 100mL of aluminum sol (alumina content is 25g) and 100g of water. Place the coating solution in a ball mill jar and ball mill at 3500r / min for 30min.

[0164] 2) The pretreated cordierite support was immersed in the above coating solution, and the immersion operation was repeated several times until the surface of the support was uniformly coated with a layer of coating solution; the coated catalyst precursor was blown clean and placed in an oven to dry at 120℃ for 6 hours; catalyst III was obtained according to the above steps, wherein the weight percentage of the coating layer was 5%. This catalyst was used to treat high-salt organic wastewater from a coal chemical plant, and the COD removal rate was 35%. During the application, the coating layer on the surface of the support showed obvious peeling and could not be reused.

[0165] Compared with Example 1, the main difference in this comparative example is that the silica sol was replaced with aluminum sol. The results showed that the mechanical properties and catalytic activity of the catalyst were significantly worse, and the COD removal rate was significantly reduced.

[0166] Comparative Example 4

[0167] This comparative example was conducted in accordance with Example 1, except that the porous cordierite pretreatment was performed only in water, not in an alkaline solution. The results showed that, under the same experimental conditions, the final catalyst exhibited a significantly lower weight percentage of coating, with the coating loading decreasing from 5% in Example 1 to 3%.

[0168] 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 here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. Use of a porous cordierite-based catalyst for ozone, characterized in that, The ozone catalyst is applied in the treatment of organic wastewater generated in the field of coal chemical industry, and a preparation method of the ozone catalyst comprises the following steps: 1) applying a coating liquid on the pretreated porous cordierite, the coating liquid comprising manganese dioxide, silica sol and water, and the weight ratio of water, silica sol and manganese dioxide is 100-150:12.5-37.5:100, wherein the weight of silica sol is calculated based on the silicon dioxide contained therein; 2) drying the porous cordierite to which the coating liquid is applied in step 1) at 120-200 ℃ to obtain the ozone catalyst with a coating layer formed on the porous cordierite; In step 1), the manganese dioxide is prepared by the following method: stirring and reacting KMnO4 aqueous solution and Mn(NO3)2 aqueous solution at 15-35 ℃, filtering the obtained reaction product, washing the filter cake with water, and drying the filter cake and then performing heat treatment at a temperature of 180-300 ℃.

2. Use according to claim 1, characterized in that, The temperature of the heat treatment is 180-220 ℃; And / or, the feeding molar ratio of KMnO4 to Mn(NO3)2 is 1:1.1-3.5; And / or, the time of the heat treatment is 3-6 h.

3. Use according to claim 2, characterized in that, The feeding molar ratio of KMnO4 to Mn(NO3)2 is 1:1.5-2.

5.

4. Use according to claim 2, characterized in that, The feeding molar ratio of KMnO4 to Mn(NO3)2 is 1:2.0-2.

5.

5. The use according to claim 1, characterized in that, In step 1), the pretreatment comprises: pretreating the porous cordierite in an alkaline solution, and then washing and drying.

6. Use according to claim 5, characterized in that, The pH of the alkaline solution is 10-12.

7. Use according to claim 5, characterized in that, The alkaline solution is selected from aqueous solution of sodium hydroxide and / or potassium hydroxide.

8. Use according to claim 5, characterized in that, The pretreatment is performed at 60-100 ℃.

9. Use according to claim 8, characterized in that, The pretreatment time is 6-10 h.

10. The application according to claim 5, characterized in that, In step (1), the weight ratio of water, silica sol and manganese dioxide is 100-150:20-30:100, wherein the weight of silica sol is calculated based on the silicon dioxide contained therein.

11. Use according to any one of claims 1 to 10, characterized in that, In step 2), the drying is performed at 120-150 ℃.

12. The use according to any one of claims 1 to 10, characterized in that, In step 1), the porous cordierite is soaked in the coating liquid to make the coating liquid adhere.

13. Use according to claim 12, characterized in that, During the soaking, the porous cordierite is repeatedly soaked for multiple times.

14. The use according to any one of claims 1 to 10, characterized in that, The weight percentage of the coating layer is 3%-10% based on the total weight of the ozone catalyst.

15. The use according to claim 14, characterized in that, The weight percentage of the coating layer is 3%-5% based on the total weight of the ozone catalyst.

16. The use according to any one of claims 1 to 10, characterized in that, In the method for preparing the manganese dioxide, the temperature of the heat treatment is 180-220 ℃, and the feeding molar ratio of KMnO4 to Mn(NO3)2 is 1:1.5-2.5; In step 1), the weight ratio of water, silica sol and manganese dioxide in the coating liquid is 100-150:20-30:100, wherein the weight of silica sol is calculated based on the silicon dioxide contained therein; In step 2), the drying is performed at 120-150 ℃; The weight percentage of the coating layer is 3%-5% based on the total weight of the ozone catalyst.

17. Use according to claim 16, characterized in that, In the method for preparing the manganese dioxide, the molar ratio of the KMnO4 to the Mn(NO3)2 is 1:2.0-2.

5.

18. The use according to any one of claims 1 to 10, characterized in that, The porous cordierite is a honeycomb-shaped cordierite. And / or, the porous cordierite has a regular shaped appearance.

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