Active manganese aldehyde and ammonia removing filter screen, its preparation method and application

Abstract

The application relates to the technical field of air purification materials, and particularly discloses an active manganese aldehyde and ammonia removal filter screen, which comprises a honeycomb base body and an active manganese catalyst layer loaded on the surface of the glass fiber paper honeycomb base body; the active manganese catalyst layer is formed by coating catalyst slurry on the surface of the glass fiber paper honeycomb base body through an automatic spraying process and drying; the automatic spraying process parameters are as follows: the moving speed of the honeycomb base body is 50-300 mm / s, the spraying distance is 50-200 mm, the spraying pressure is 0.2-0.6 MPa, and the spraying amount is 2-10 g / s; the catalyst slurry contains ammonium intercalation and pyrolysis-treated layered delta-MnO2 powder; and the application also provides a preparation method of the active manganese aldehyde and ammonia removal filter screen. The active manganese aldehyde and ammonia removal filter screen has the advantages of low cost, firm catalyst loading, good aldehyde and ammonia removal effect, high mechanical strength and suitability for large-scale production, and has a good use prospect.

Description

Technical Field

[0001] This application relates to the field of air purification materials technology, specifically to an activated manganese aldehyde and ammonia removal filter and its preparation method and application. Background Technology

[0002] Ammonia is a typical air pollutant. In indoor environments, it mainly comes from decoration materials, cleaning agents, pet excrement, and human metabolic products. Long-term exposure can harm human health. Therefore, the development of efficient formaldehyde and ammonia removal technologies is of great significance.

[0003] In existing air purification equipment for formaldehyde and ammonia removal, honeycomb filters are widely used due to their advantages such as low air resistance, large specific surface area, and regular structure. The substrates of existing honeycomb filters are mostly metal or paper materials. Metal and ceramic honeycomb filters have high mechanical strength and good heat resistance, but their material costs are high, and the catalyst coating is prone to peeling due to differences in thermal expansion coefficients. While paper honeycomb filters are inexpensive, they have poor water resistance and insufficient mechanical strength, making them unsuitable for wet loading processes. Furthermore, the current method for loading catalysts onto the surface of honeycomb filters is mainly the impregnation method, which involves immersing the honeycomb substrate in a catalyst slurry and then drying it. However, this method has drawbacks such as low catalyst utilization, easy clogging of small-diameter pores, and uneven coating distribution, affecting the overall purification performance of the filter.

[0004] In the field of catalyst materials, manganese dioxide has attracted widespread attention due to its excellent low-temperature catalytic oxidation activity and environmental friendliness. However, the adsorption of ammonia by conventional manganese dioxide is mainly physical, with insufficient exposure of its surface active sites, resulting in very limited catalytic oxidation efficiency.

[0005] Therefore, developing an activated manganese filter screen for removing aldehydes and ammonia that is low in cost, has high mechanical strength, a robust catalyst loading, and high efficiency in removing aldehydes and ammonia is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] In order to overcome the problems of existing activated manganese aldehyde and ammonia removal filters, such as the difficulty in balancing manufacturing cost and mechanical strength, and the poor aldehyde and ammonia removal effect due to low catalyst loading, this application provides an activated manganese aldehyde and ammonia removal filter, its preparation method and application.

[0007] This application provides an activated manganese filter screen for removing formaldehyde and ammonia, employing the following technical solution: An activated manganese filter for removing formaldehyde and ammonia includes a honeycomb substrate and an activated manganese catalyst layer loaded on the surface of the fiberglass paper honeycomb substrate; the loading of the activated manganese catalyst layer is 40-200% of the weight of the fiberglass paper honeycomb substrate. The active manganese catalyst layer is formed by coating the catalyst slurry onto the surface of the fiberglass paper honeycomb substrate using an automatic spraying process and then drying it. The automatic spraying process parameters are: honeycomb substrate moving speed of 50-300 mm / s, spraying distance of 50-200 mm, spraying pressure of 0.2-0.6 MPa, and spraying amount of 2-10 g / s. The catalyst slurry contains layered δ-MnO2 powder obtained by ammonium intercalation and pyrolysis treatment; the layered δ-MnO2 powder is obtained by mixing potassium permanganate with a reducing agent and ammonium salt and then carrying out a hydrothermal reaction at 80-180℃ for 6-24h, followed by washing, drying and grinding; the layered δ-MnO2 powder can efficiently catalyze the oxidation of ammonia at room temperature.

[0008] This application uses a fiberglass paper honeycomb matrix as the main body of the filter screen, and coats its surface with an active manganese catalyst layer through an automated spraying process, thereby obtaining a low-cost, robustly loaded catalyst, high mechanical strength, and suitable for large-scale production of a formaldehyde and ammonia removal filter screen. Specifically: First, the raw material cost of the fiberglass paper honeycomb matrix used in this application is low, and it itself has high heat resistance, high thermal insulation, and non-flammability, resulting in excellent safety performance. More importantly, the fiberglass paper has high mechanical strength and good water resistance, and can withstand the mechanical and damp heat shocks during catalyst slurry spraying and use, providing a stable and durable carrier for the catalyst. Second, this application adopts an automated spraying process and controls its parameters within a specific range, which ensures that the catalyst slurry is uniformly covered on the inner and outer surfaces of the honeycomb channels in the form of fine droplets, while avoiding large droplets clogging the channels, ensuring that the catalyst layer coating has a consistent thickness, strong adhesion, and is not easily peeled off after drying. In summary, this application, through the selection of the filter substrate and the setting of the automatic spraying process, can improve the overall performance of the filter, enabling the filter to maintain low wind resistance and high strength while fully utilizing the active sites, thereby achieving efficient and long-lasting formaldehyde and ammonia removal efficiency.

[0009] In some embodiments, the moving speed of the cellular substrate can be 50-100mm / s, 50-150mm / s, 50-200mm / s, 50-300mm / s, 100-150mm / s, 100-200mm / s, 100-300mm / s, 150-200mm / s, 150-300mm / s, or 200-300mm / s.

[0010] In one specific implementation, the moving speed of the cellular substrate can also be 50 mm / s, 100 mm / s, 150 mm / s, 200 mm / s, or 300 mm / s.

[0011] In some implementations, the spraying distance can be 50-100mm or 100-200mm.

[0012] In one specific implementation, the spraying distance can also be 50mm, 100mm or 200mm.

[0013] In some embodiments, the spraying pressure may be 0.2-0.4 MPa or 0.4-0.6 MPa.

[0014] In one specific implementation, the spraying pressure may also be 0.2 MPa, 0.4 MPa, or 0.6 MPa.

[0015] In some implementations, the spraying rate can be 2-5 g / s or 5-10 g / s.

[0016] In one specific implementation, the spraying amount can also be 2 g / s, 5 g / s, or 10 g / s.

[0017] Optionally, the catalyst slurry has a solid content of 5-30 wt% and comprises the following raw materials in parts by weight: 90-110 parts of layered δ-MnO2 powder, 5-25 parts of binder and 0.5-5 parts of dispersant.

[0018] Optionally, the layered δ-MnO2 powder is obtained by mixing potassium permanganate with a reducing agent and ammonium salt, followed by a hydrothermal reaction at 80-180℃ for 6-24 hours, and then washing, drying, and grinding.

[0019] Optionally, during the preparation of the layered δ-MnO2 powder, drying is carried out at 200-300°C under nitrogen or argon protection.

[0020] In the catalyst slurry of this application, the layered δ-MnO2 powder is obtained by ammonium intercalation and pyrolysis of potassium permanganate. This treatment can transform the originally inert Mn... 4+ Partially reduced to highly active Mn 3+ It also opens up closed interlayer domains into open active edges, increasing Mn 4+ Mn 3+ And surface-active sites such as oxygen vacancies; in the subsequent use for formaldehyde and ammonia removal, ammonia molecules can react with Mn 3+ By forming coordination bonds, the removal of formaldehyde and ammonia is transformed from physical adsorption to chemical adsorption that is conducive to catalysis. At room temperature, ammonia can be efficiently catalyzed and oxidized, converting it into harmless nitrogen and water, effectively avoiding secondary pollution caused by the re-release of ammonia.

[0021] In some embodiments, the temperature of the hydrothermal reaction can be 80-140°C or 140-180°C.

[0022] In one specific implementation, the temperature of the hydrothermal reaction can also be 80°C, 140°C, or 180°C.

[0023] In some implementations, the temperature of the hydrothermal reaction can be 6-12h or 12-24h.

[0024] In one specific implementation, the temperature of the hydrothermal reaction can also be 6h, 12h, or 24h.

[0025] Optionally, the reducing agent is manganese sulfate, manganese chloride, manganese nitrate, manganese carbonate, or manganese acetate; the ammonium salt is ammonium sulfate, ammonium chloride, ammonium nitrate, tetramethylammonium hydroxide, or tetramethylammonium.

[0026] Optionally, the automatic spraying and drying of the catalyst slurry is repeated 1-3 times; the drying temperature for each time is 80-150℃ and the time is 10-60 minutes.

[0027] Optionally, the binder is selected from one or more of aqueous silica sol, aqueous acrylic emulsion, and aluminum sol; the dispersant is selected from one or more of citric acid, tartaric acid, and polyacrylic acid.

[0028] Secondly, this application provides a method for preparing an activated manganese aldehyde and ammonia removal filter, comprising the following steps: First, a catalyst slurry is prepared. Then, an automatic spraying device is used to spray the catalyst slurry onto the surface of a glass fiber paper honeycomb substrate. After drying, an activated manganese aldehyde and ammonia removal filter is obtained. The automatic spraying equipment includes a conveying device, a spraying device, a drying device, and a control system; the spraying device includes a nozzle and a slurry conveying system.

[0029] Thirdly, this application provides an application of an activated manganese formaldehyde and ammonia removal filter in an air purification device.

[0030] In summary, this application has the following beneficial effects: 1. The formaldehyde and ammonia removal filter of this application uses fiberglass paper honeycomb as the matrix. Compared with metal honeycomb, it has the advantages of low raw material cost, high mechanical strength, good heat resistance and insulation, and good water resistance. It can withstand the airflow impact during spraying, drying and subsequent use.

[0031] 2. The automated spraying process employed in this application can uniformly coat the catalyst slurry onto the surface of the honeycomb substrate, effectively avoiding the drawbacks of traditional impregnation methods such as excessive material usage, uneven coating, and easy pore clogging. This results in a strong, durable catalyst coating that significantly extends the filter's lifespan. Furthermore, the aforementioned spraying process boasts a high degree of automation, enabling continuous and large-scale production, and yields products of stable quality, making it suitable for industrial application.

[0032] 3. In the process of removing aldehydes and ammonia, the layered δ-MnO2 powder in the activated manganese catalyst layer of this application allows ammonia molecules to react with Mn. 3+ By forming coordination bonds, the removal of formaldehyde and ammonia is transformed from physical adsorption to chemical adsorption that is conducive to catalysis. At room temperature, ammonia can be efficiently catalyzed and oxidized, converting it into harmless nitrogen and water, effectively avoiding secondary pollution caused by the re-release of ammonia. Detailed Implementation

[0033] This application provides an activated manganese aldehyde and ammonia removal filter, including a honeycomb matrix and an activated manganese catalyst layer loaded on the surface of the glass fiber paper honeycomb matrix; The preparation method of the above-mentioned activated manganese formaldehyde and ammonia removal filter includes the following steps: (1) Preparation of catalyst slurry: Weigh the layered δ-MnO2 powder, binder and dispersant according to the ratio, mix them evenly, then add water to adjust the solid content to 5-30%, stir and disperse for 30-40 min to obtain catalyst slurry; (2) Automatic spraying load: The fiberglass paper honeycomb substrate is placed on the conveyor belt of the automatic spraying production line and transported to the spraying station for spraying. The nozzle is a two-fluid air-water mixing nozzle. The moving speed of the honeycomb substrate is set to 50-300mm / s, the spraying distance is 50-200mm, the spraying pressure is 0.2-0.6MPa, and the spraying amount is 2-10g / s. After the spraying is completed, the honeycomb substrate enters the hot air drying oven and is dried at 80-150℃ for 10-60min. The above "automatic spraying + drying" operation is repeated 1-3 times to obtain the activated manganese formaldehyde and ammonia removal filter.

[0034] In this application, the fiberglass paper honeycomb matrix is ​​of model HexWeb HRH-327, purchased from Hexcel; the raw materials, reagents, solvents, etc. used in this application are all commercially available.

[0035] The following describes this application in further detail with reference to preparation examples, embodiments, and performance testing.

[0036] Preparation Examples 1-5

[0037] Preparation Examples 1-5 each provide a layered δ-MnO2 powder.

[0038] The difference in the above preparation examples lies in the temperature and time of the hydrothermal reaction, as shown in Table 1 below.

[0039] The preparation method of the layered δ-MnO2 powder provided in Examples 1-5 includes the following steps: 4.74 g of potassium permanganate (KMnO4, 0.03 mol) is weighed and dissolved in 100 mL of deionized water; 2.52 g of manganese sulfate monohydrate (MnSO4·H2O, 0.015 mol) is weighed and dissolved in 50 mL of deionized water; under vigorous stirring, the manganese sulfate solution is slowly added dropwise to the potassium permanganate solution, and stirring is continued for 30 min after the addition is complete; then 0.5 g of ammonium sulfate is added to the above mixture, and the mixture is transferred to a hydrothermal reactor lined with polytetrafluoroethylene for hydrothermal reaction; after the reaction is completed, the mixture is naturally cooled to room temperature, and the product is washed three times alternately with deionized water and anhydrous ethanol, and finally dried at 230 °C under nitrogen protection for 12 h, and ground to obtain brown layered δ-MnO2 powder.

[0040] Table 1. Hydrothermal reaction temperature and time in the preparation methods of layered δ-MnO2 powder provided in Examples 1-5

[0041] Comparative Preparation Example 1

[0042] Comparative preparation example 1 provides a MnO2 powder.

[0043] The difference between the above comparative preparation example and preparation example 2 is that the hydrothermal reaction temperature is 230℃ and the reaction time is 6h.

[0044] Comparative Preparation Example 2

[0045] Comparative preparation example 2 provides a MnO2 powder.

[0046] The difference between the above comparative preparation example and preparation example 2 is that the hydrothermal reaction temperature is 230℃ and the reaction time is 12h.

[0047] Comparative preparation example 3

[0048] Comparative preparation example 3 provides a MnO2 powder.

[0049] The difference between the above comparative preparation example and preparation example 3 is that the hydrothermal reaction temperature is 50°C and the reaction time is 30h.

[0050] Examples 1-5

[0051] Examples 1-5 each provide an activated manganese filter for removing formaldehyde and ammonia.

[0052] The difference between the above embodiments is that the layered δ-MnO2 powder used in the catalyst slurry of Examples 1-5 was derived from Preparation Examples 1-5, respectively.

[0053] The preparation method of the activated manganese formaldehyde and ammonia removal filter provided in Examples 1-5 includes the following steps: (1) Preparation of catalyst slurry: Weigh 100g of layered δ-MnO2 powder, 25g of binder and 2g of dispersant according to the ratio, mix them evenly, then add water to adjust the solid content to 30%, stir and disperse for 30min to obtain catalyst slurry; (2) Automatic spraying load: The fiberglass paper honeycomb substrate is placed on the conveyor belt of the automatic spraying production line and transported to the spraying station for spraying. The nozzle is a two-fluid air-water mixing nozzle. The moving speed of the honeycomb substrate is set to 150 mm / s, the spraying distance is 200 mm, the spraying pressure is 0.4 MPa, and the spraying amount is 5 g / s. After the spraying is completed, the honeycomb substrate enters the hot air drying oven and is dried at 120℃ for 20 min. The above "automatic spraying + drying" operation is repeated twice to obtain an active manganese formaldehyde and ammonia removal filter with a catalyst weight gain ratio of 100% (i.e., the weight ratio of fiberglass paper honeycomb substrate to active manganese catalyst layer is 1:1).

[0054] Examples 6-15

[0055] Examples 6-15 provide an activated manganese filter for removing formaldehyde and ammonia.

[0056] The difference in the above embodiments is that the parameters of the automatic spraying process (i.e., the loading amount of the active manganese catalyst layer) are shown in Table 2 below.

[0057] Table 2. Parameters of the automatic spraying process in Examples 2 and 6-15

[0058] Comparative Examples 1-3

[0059] Comparative Examples 1-3 each provide an activated manganese filter for removing formaldehyde and ammonia.

[0060] The difference between the above comparative examples and Example 2 is that the layered δ-MnO2 powder used in the catalyst slurries of comparative examples 1-3 were respectively derived from comparative preparation examples 1-3. Comparative Example 4

[0061] Comparative Example 4 provides an activated manganese filter for removing formaldehyde and ammonia.

[0062] The difference between the above comparative example and Example 2 is that the layered δ-MnO2 powder obtained by ammonium intercalation and pyrolysis is replaced with MnO2 powder; The conventional method for preparing δ-MnO2 powder is as follows: Weigh 4.74 g of potassium permanganate (KMnO4, 0.03 mol) and dissolve it in 100 mL of deionized water; weigh 2.52 g of manganese sulfate monohydrate (MnSO4·H2O, 0.015 mol) and dissolve it in 50 mL of deionized water; under vigorous stirring, slowly add the manganese sulfate solution dropwise to the potassium permanganate solution, and continue stirring for 30 min after the addition is complete; then transfer the above mixture into a hydrothermal reactor lined with polytetrafluoroethylene and hydrothermally react at 140 °C for 12 h; after the reaction is completed, allow it to cool naturally to room temperature, wash the product three times alternately with deionized water and anhydrous ethanol, and finally dry it at 230 °C under nitrogen protection for 12 h, and grind it to obtain brown MnO2 powder. Comparative Example 5

[0063] Comparative Example 5 provides an activated manganese filter for removing formaldehyde and ammonia.

[0064] The difference between the above comparative example and Example 2 is that in the automatic spraying process of Comparative Example 5, the moving speed of the honeycomb substrate is 30 mm / s, the spraying distance is 100 mm, the spraying pressure is 0.4 MPa, and the spraying amount is 5 g / s; in the obtained activated manganese aldehyde and ammonia removal filter, the loading of the activated manganese catalyst layer is 250% of the weight of the glass fiber paper honeycomb substrate. Comparative Example 6

[0065] Comparative Example 6 provides an activated manganese filter for removing formaldehyde and ammonia.

[0066] The difference between the above comparative example and Example 2 is that in the automatic spraying process of Comparative Example 6, the moving speed of the honeycomb substrate is 150 mm / s, the spraying distance is 100 mm, the spraying pressure is 0.4 MPa, and the spraying amount is 30 g / s. In the obtained activated manganese aldehyde and ammonia removal filter, the loading of the activated manganese catalyst layer is 300% of the weight of the glass fiber paper honeycomb substrate. Comparative Example 7

[0067] Comparative Example 7 provides an activated manganese filter for removing formaldehyde and ammonia.

[0068] The difference between the above comparative example and Example 2 is that the same catalyst slurry and fiberglass paper honeycomb matrix as in Example 2 are used, but the conventional impregnation method is used for loading: the fiberglass paper honeycomb matrix is ​​completely immersed in the catalyst slurry, taken out and the excess slurry in the pores is blown out, and then dried.

[0069] Performance testing

[0070] (1) Ammonia removal efficiency: The activated manganese aldehyde and ammonia removal filters obtained in Examples 1-15 and Comparative Examples 1-7 were placed in a self-made ammonia purification test device. The purification device was placed in a 3m³ experimental chamber, and the test conditions were set as follows: initial ammonia concentration 2mg / m³. 3The relative humidity was 50% and the temperature was 25℃. The ammonia concentration in the chamber after 60 minutes of continuous operation was determined by Nessler's reagent spectrophotometry (HJ 533-2009), and the ammonia removal efficiency was calculated.

[0071] (2) Coating adhesion test: Draw a 1 mm × 1 mm grid on the surface of the activated manganese catalyst layer of the filter screen, ensuring that the cut penetrates the coating; tightly adhere the grid with 3M 600# tape and quickly pull it up vertically; rate according to ASTM D3359 and record the area of ​​coating peeling off. Note: 5B: 0% peeling; 4B: <5%; 3B: 5%~15%; 2B: 15%~35%; 1B: 35%~65%; 0B: >65%.

[0072] (3) Formaldehyde removal performance test: Cut the filter into appropriate sizes and place it in an airflow of 50m³ / h. 3 Place the purifier in a 3m purifier with a capacity of / h. 3 In a sealed experimental chamber, when the formaldehyde concentration inside the chamber reaches 1 mg / m³... 3 When the air purifier is turned on, test the formaldehyde concentration in the chamber after 30 minutes and calculate the formaldehyde removal rate according to the formula. Formaldehyde removal rate % = (formaldehyde concentration in the chamber at 1-30 min / initial formaldehyde concentration in the chamber) × 100%.

[0073] (4) Appearance: Observe whether the active manganese catalyst layer on the surface of the filter screen is uniform and whether there are problems such as clogging or accumulation.

[0074] Table 3 Performance test results of activated manganese formaldehyde and ammonia removal filters in Examples 1-15 and Comparative Examples 1-7

[0075] The test results of Examples 1-5 and Comparative Examples 1-4 show that in the preparation process of MnO2 powder in Comparative Examples 1-2, the pyrolysis temperature was too high and the temperature was too long, resulting in MnO2 powder that was either α-MnO2 or a mixture of α-MnO2 and δ-MnO2, which led to a significant decrease in catalyst activity. In the preparation process of MnO2 powder in Comparative Example 3, the pyrolysis temperature was too low, resulting in poor crystallization of MnO2 and insufficient catalyst efficiency. In Comparative Example 4, the conventional MnO2 powder without ammonium intercalation relied solely on physical adsorption for its aldehyde and ammonia removal effects. In contrast, Examples 1-5 used the layered δ-MnO2 powder containing ammonium intercalation and obtained through pyrolysis treatment as a catalyst, which achieved high-efficiency ammonia removal through chemical adsorption and room-temperature catalysis.

[0076] The test results of Examples 2, 6-15, and Comparative Examples 5-7 show that, under the automatic spraying process parameters of Examples 2 and 6-15, the activated manganese formaldehyde and ammonia removal filter obtained has good coating uniformity and adhesion, and excellent formaldehyde and ammonia removal performance. However, the activated manganese formaldehyde and ammonia removal filter obtained under the automatic spraying process parameters of Comparative Examples 5-6 has problems such as slurry accumulation, excessive coating thickness, and pore blockage on the surface, which leads to a decrease in the formaldehyde and ammonia removal performance of the activated manganese formaldehyde and ammonia removal filter. The activated manganese formaldehyde and ammonia removal filter prepared by the traditional impregnation process in Comparative Example 7 has an extremely uneven surface coating, many pores are completely blocked, there are obvious flow marks on the surface, and the adhesion of the coating is very poor. Therefore, this application controls the automatic spraying process parameters within the following ranges: the honeycomb substrate moving speed is 50-300 mm / s, the spraying distance is 50-200 mm, the spraying pressure is 0.2-0.6 MPa, and the spraying amount is 2-10 g / s. This enables the production of activated manganese formaldehyde and ammonia removal filters with uniform surface coating, no clogging or accumulation, and excellent mechanical strength and formaldehyde and ammonia removal effects.

[0077] In summary, the activated manganese formaldehyde and ammonia removal filter provided in this application, by selecting a glass fiber paper honeycomb matrix, using δ-MnO2 treated with "ammonium intercalation + pyrolysis" as a catalyst, and employing an automatic spraying process, successfully solves the technical problems existing in the prior art, such as high cost, easy catalyst detachment, uneven loading, easy pore blockage, and low formaldehyde and ammonia removal efficiency, and has great industrial application value.

[0078] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. The application of an activated manganese formaldehyde and ammonia removal filter in the removal of ammonia and formaldehyde, characterized in that, It includes a fiberglass paper honeycomb matrix and an active manganese catalyst layer supported on the surface of the fiberglass paper honeycomb matrix; the loading of the active manganese catalyst layer is 40-200% of the weight of the fiberglass paper honeycomb matrix. The active manganese catalyst layer is formed by coating the catalyst slurry onto the surface of the fiberglass paper honeycomb substrate using an automatic spraying process and then drying it. The automatic spraying process parameters are: honeycomb substrate moving speed of 50-300 mm / s, spraying distance of 50-200 mm, spraying pressure of 0.2-0.6 MPa, and spraying amount of 2-10 g / s. The catalyst slurry contains layered δ-MnO2 powder obtained through ammonium intercalation and pyrolysis treatment; the layered δ-MnO2 powder is obtained by mixing potassium permanganate with a reducing agent and ammonium salt, followed by a hydrothermal reaction at 80-180℃ for 6-24h, and then washing, drying, and grinding; the layered δ-MnO2 powder can catalytically oxidize ammonia gas at room temperature. The reducing agent is manganese sulfate, manganese chloride, manganese nitrate, manganese carbonate, or manganese acetate; the ammonium salt is ammonium sulfate, ammonium chloride, or ammonium nitrate.

2. The application according to claim 1, characterized in that, The catalyst slurry has a solid content of 5-30 wt% and includes the following raw materials in parts by weight: 90-110 parts of layered δ-MnO2 powder, 5-25 parts of binder, and 0.5-5 parts of dispersant.

3. The application according to claim 1, characterized in that, During the preparation of the layered δ-MnO2 powder, drying is carried out at 200-300℃ under nitrogen or argon protection.

4. The application according to claim 1, characterized in that, The automatic spraying and drying of the catalyst slurry is repeated 1-3 times; the drying temperature for each time is 80-150℃ and the time is 10-60min.

5. The application according to claim 2, characterized in that, The binder is selected from one or more of aqueous silica sol, aqueous acrylic emulsion, and aluminum sol; the dispersant is selected from one or more of citric acid, tartaric acid, and polyacrylic acid.

6. The application as described in any one of claims 1-5, characterized in that, Includes the following steps: First, a catalyst slurry is prepared. Then, an automatic spraying device is used to spray the catalyst slurry onto the surface of a glass fiber paper honeycomb substrate. After drying, an activated manganese aldehyde and ammonia removal filter is obtained. The automatic spraying equipment includes a conveying device, a spraying device, a drying device, and a control system; the spraying device includes a nozzle and a slurry conveying system.

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