Modified manganese-based de-nox catalyst and method for preparing the same

Abstract

This invention relates to the field of catalyst preparation, and discloses a modified manganese-based denitrification catalyst and its preparation method. The method includes the following steps: mixing and grinding a manganese salt and optionally a cerium salt, then calcining the resulting mixture to obtain a manganese-based catalyst; placing the manganese-based catalyst in a modified gas atmosphere for adsorption, then mixing the manganese-based catalyst with water and sonicating, and then drying the separated solid product; wherein the modified gas contains 3-8 vol% oxygen, 400-600 ppm nitric oxide, and 92-97 vol% inactive gases. The modified manganese-based denitrification catalyst of this invention exhibits superior low-temperature denitrification performance, achieving a NO conversion rate of over 60% at 150°C.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation, specifically to a modified manganese-based denitrification catalyst and its preparation method. Background Technology

[0002] Industrial production and urban transportation emit large amounts of nitrogen oxides, easily leading to smog, photochemical smog, acid rain, and other problems, causing significant harm to the surrounding environment. Selective catalytic reduction of NO by NH3 (NH3-SCR) has been widely used due to its high denitrification efficiency and low operating cost. The corresponding commercial denitrification catalyst has a chemical composition of V2O5-WO3 / TiO2. Commercial VO x -WO x While TiO2 catalysts have been widely used in flue gas denitrification in coal-fired power plants, they still suffer from drawbacks such as a narrow operating temperature range (300-400℃), susceptibility to alkali / alkaline earth metal poisoning, and the biotoxicity of the active component V2O5. Furthermore, with the successful implementation of ultra-low emission policies in the power industry, industries such as steel, glass, and cement are increasingly focusing on NOx emission reduction. x With increasingly stringent emission requirements, and flue gas conditions in these industries making the direct application of commercial V-based catalysts difficult, the development of low-temperature denitrification catalysts has become a hot topic in recent years.

[0003] Currently, most research focuses on developing transition metal oxide catalysts to replace commercial vanadium-based catalysts. Researchers have explored the application of various transition metal oxides in low-temperature denitrification, including manganese oxide, copper oxide, cerium oxide, and titanium oxide. Among these, manganese-based catalysts have emerged as an important candidate catalyst due to their abundant valence states, excellent redox performance, and certain sulfur resistance.

[0004] Currently, various manganese-based catalysts have been invented and researched, and numerous modification methods have emerged to improve the performance of manganese-based catalysts. Compared with the doping modification commonly used in existing technologies, how to improve the denitrification performance of manganese-based catalysts at low temperatures using low-cost processing methods, so as to enable their widespread application in practice, has important theoretical value and practical significance. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of high modification cost and poor denitrification performance at low temperatures of existing manganese-based denitrification catalysts. This invention provides a modified manganese-based denitrification catalyst and its preparation method. The method involves pre-adsorption treatment of the manganese-based catalyst with a modified atmosphere, followed by ultrasonic-assisted water washing to remove NO adsorbed on the surface. x Species removal improves the acidity and redox properties of the manganese-based catalyst, thereby enhancing its low-temperature denitrification performance.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a modified manganese-based denitration catalyst, the method comprising the following steps:

[0007] (1) Mix and grind manganese salt and optional cerium salt, and then calcine the resulting mixture to obtain a manganese-based catalyst;

[0008] (2) The manganese-based catalyst is placed in a modified gas atmosphere for adsorption, then the manganese-based catalyst is mixed with water and sonicated, and then the separated solid product is dried.

[0009] The modified gas contains 3-8% by volume oxygen, 400-600 ppm nitric oxide, and 92-97% by volume inactive gas.

[0010] Preferably, in step (1), the manganese salt is selected from at least one of manganese acetate tetrahydrate, potassium permanganate, and manganese nitrate.

[0011] Preferably, the cerium salt is selected from at least one of cerium nitrate hexahydrate, cerium nitrate, and cerium acetate hydrate.

[0012] Preferably, in step (1), the molar ratio of the manganese salt to the cerium salt is 1-10:1.

[0013] Preferably, in step (1), the grinding time is 1-30 min.

[0014] Preferably, in step (1), the calcination conditions include: a temperature of 300-600℃, a time of 1-10h, and a heating rate of 1-10℃ / min.

[0015] Preferably, in step (2), the adsorption conditions include: a temperature of 30-300℃, a time of 0.5-2h, a gas flow rate of 100-150mL / min, and a gas hourly space velocity of 20000-70000mL·g. -1 ·h -1 .

[0016] Preferably, in step (2), the weight ratio of water to manganese-based catalyst is 100-500:1.

[0017] Preferably, in step (2), the conditions for ultrasound include: power of 100-150W and time of 2-3h.

[0018] Preferably, in step (2), the drying conditions include a temperature of 30-50°C and a time of 18-30 hours.

[0019] A second aspect of the present invention provides a modified manganese-based denitrification catalyst prepared by the method described above.

[0020] The method for preparing the modified manganese-based denitrification catalyst of the present invention involves pre-adsorption treatment of the manganese-based catalyst with a modified atmosphere, followed by ultrasonic-assisted water washing to remove the NO adsorbed on the surface. x Species removal and surface material reconstruction of the manganese-based catalyst improve its acidity and redox properties, thereby enhancing its low-temperature denitrification performance. The modified manganese-based denitrification catalyst of this invention exhibits excellent low-temperature denitrification performance, achieving a NO conversion rate of over 60% at 150°C. Attached Figure Description

[0021] Figure 1 XRD patterns of Mn-100-NW prepared in Example 2 and MnCe-100-NW prepared in Example 5;

[0022] Figure 2 NO adsorbed on the surface of Mn-RT-NW, Mn-100-NW, Mn-200-NW, MnCe-RT-NW, MnCe-100-NW and MnCe-200-NW prepared in Examples 1-6 x UV absorption spectrum of a species. Detailed Implementation

[0023] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] The preparation method of the modified manganese-based denitration catalyst of the present invention includes the following steps:

[0026] (1) Mix and grind manganese salt and optional cerium salt, and then calcine the resulting mixture to obtain a manganese-based catalyst;

[0027] (2) The manganese-based catalyst is placed in a modified gas atmosphere for adsorption, then the manganese-based catalyst is mixed with water and sonicated, and then the separated solid product is dried.

[0028] The modified gas contains 3-8% by volume oxygen, 400-600 ppm nitric oxide, and 92-97% by volume inactive gas.

[0029] In the most preferred embodiment, the modified gas contains 5 ± 0.5 vol% oxygen, 500 ± 10 ppm nitric oxide, and 95 ± 0.5 vol% inactive gas. In this invention, when the component content of the modified gas is within the above range, the modified manganese-based denitrification catalyst exhibits better catalytic activity.

[0030] In this invention, the inactive gas refers to a gas that does not react with the manganese-based catalyst. In specific embodiments, the inactive gas can be nitrogen and / or an inert gas (such as argon), preferably nitrogen.

[0031] In this invention, in step (1), the manganese salt can be at least one of manganese acetate tetrahydrate, potassium permanganate and manganese nitrate, preferably manganese acetate tetrahydrate.

[0032] In this invention, the cerium salt can be at least one of cerium nitrate hexahydrate, cerium nitrate, and cerium acetate hydrate, preferably cerium nitrate hexahydrate.

[0033] In the method described in this invention, in step (1), the molar ratio of the manganese salt to the cerium salt can be 1-10:1, preferably 1-5:1. In this invention, when the molar ratio of the manganese salt to the cerium salt is within the above range (especially the preferred range), the prepared MnCe catalyst has better denitrification performance.

[0034] In the method described in this invention, the grinding time in step (1) can be 1-30 min, preferably 5-15 min. In this invention, when the grinding time is within the above range (especially the preferred range), the prepared manganese-based catalyst has better denitrification performance.

[0035] In the method described in this invention, the calcination conditions in step (1) may include: a temperature of 300-600℃, preferably 400-500℃; a time of 1-10h, preferably 1-5h; and a heating rate of 1-10℃ / min, preferably 1-5℃ / min. In the method described in this invention, when the calcination conditions are within the above ranges (especially the preferred ranges), the prepared catalyst has a better pore structure.

[0036] In some embodiments, the process of preparing the manganese-based catalyst includes: grinding a manganese salt for 1-30 min and then placing it in a muffle furnace, heating it to 300-600°C at a heating rate of 1-10°C / min, calcining it for 1-10 h to obtain a Mn3O4 catalyst, and then grinding and pressing the catalyst into tablets. When step (1) is carried out according to this embodiment, a Mn3O4 catalyst with good denitrification catalytic performance can be obtained.

[0037] In other embodiments, the process of preparing the manganese-based catalyst includes: mixing manganese salt and cerium salt in a molar ratio of 1-10:1 and grinding for 1-30 min, then placing the mixture in a muffle furnace and heating it to 300-600°C at a heating rate of 1-10°C / min, calcining for 1-10 h to obtain the MnCe catalyst, and then grinding and pressing the catalyst into tablets. When step (1) is carried out according to this embodiment, a MnCe catalyst with better denitrification catalytic performance can be obtained.

[0038] In the method described in this invention, in step (2), the adsorption conditions may include: a temperature of 30-300℃, preferably 30-200℃; a time of 0.5-2h, preferably 0.5-1h; a gas flow rate of 100-150mL / min, preferably 100-120mL / min; and a gas space velocity of 20000-70000mL·g. -1 ·h -1 The preferred value is 20,000-60,000 mL·g -1 ·h -1 In the method described in this invention, when the adsorption conditions are within the above-mentioned range (especially the preferred range), more NO is adsorbed on the surface of the manganese-based catalyst. x Species.

[0039] In the method described in this invention, the adsorption modification process of the manganese-based catalyst may further include: purging the manganese-based catalyst with an inactive gas at a flow rate of 50-200 mL / min at 100-200 °C for 10-60 min; then placing the manganese-based catalyst under a modifying gas atmosphere for adsorption; and after adsorption, purging the manganese-based catalyst again with an inactive gas at a flow rate of 50-200 mL / min at 100-200 °C for 10-60 min. In the method described in this invention, when the adsorption process is carried out according to the above method, more NO is adsorbed on the surface of the manganese-based catalyst. x Species.

[0040] In the method described in this invention, in step (2), the weight ratio of water to the manganese-based catalyst can be 100-500:1, preferably 200-400:1. In the method described in this invention, when the weight ratio of water to the manganese-based catalyst is within the above range (especially the preferred range), the NO on the surface of the manganese-based catalyst... x The removal of species is more thorough.

[0041] In the method described in this invention, in step (2), the conditions for ultrasound may include: a power of 100-150W, preferably 90-120W; and a time of 2-3 hours, preferably 2-2.5 hours. In the method described in this invention, when the ultrasound conditions are within the above range (especially the preferred range), the NO on the surface of the manganese-based catalyst... x The removal of species is more thorough.

[0042] In the method described in this invention, in step (2), the drying conditions may include: a temperature of 30-50°C, preferably 30-40°C; and a time of 18-30h, preferably 20-24h.

[0043] In some embodiments, the ultrasonic water washing process of the manganese-based catalyst further includes: placing water and the adsorbed modified manganese-based catalyst in a container at a weight ratio of 100-500:1, then placing the container in an ultrasonic bath and ultrasonicating it at a power of 100-150W for 2-3 hours; filtering the mixture in the container and air-drying the separated solid product at 30-50℃ for 18-30 hours. When implementing step (2) according to this embodiment, a modified manganese-based denitrification catalyst with better denitrification catalytic performance can be obtained.

[0044] This invention also provides a modified manganese-based denitrification catalyst prepared by the above method. The modified manganese-based denitrification catalyst undergoes modification, resulting in surface material reconstruction, which improves the acidity and redox properties of the manganese-based catalyst, thereby enhancing its low-temperature denitrification performance. Specifically, the modified manganese-based denitrification catalyst of this invention exhibits excellent low-temperature denitrification performance; catalytic denitrification at 150°C significantly improves the NO conversion rate.

[0045] The modified manganese-based denitrification catalyst and its preparation method described in this invention are further illustrated below through examples. These examples are implemented based on the technical solution of this invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of this invention is not limited to the following examples.

[0046] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples and comparative examples are commercially available.

[0047] Example 1

[0048] (1) Grind 25g of manganese acetate tetrahydrate for 10min and put it into a crucible. Then place the crucible in a muffle furnace and heat it to 450℃ at a heating rate of 1℃ / min. Calcine for 2h to obtain Mn3O4 catalyst. Then grind and press the catalyst into tablets.

[0049] (2) Place 0.3g of the Mn3O4 catalyst in a tube furnace, purge the manganese-based catalyst with an inactive gas at a flow rate of 100mL / min at 150°C for 30min, and then introduce a modified gas into the tube furnace, adjusting the temperature to 30°C, the gas flow rate to 100mL / min, and the gas space velocity to 20000mL·g. -1 ·h -1 The manganese-based catalyst is adsorbed in the modified gas atmosphere for 1 hour. After the adsorption is completed, the manganese-based catalyst is purged into the tube furnace with an inactive gas at a flow rate of 100 mL / min for 30 minutes. The modified gas contains 3% by volume oxygen, 400 ppm nitric oxide and 97% by volume nitrogen.

[0050] (3) Take out the modified Mn3O4 catalyst into a 100mL reagent bottle, add 100mL of water, tighten the cap, set the ultrasonic pool power to 100W, place the reagent bottle in the ultrasonic pool and sonicate for 2h. After sonication, filter the mixture in the reagent bottle, and then air dry the filter paper at 30℃ for 24h to obtain the modified manganese-based denitrification catalyst of the present invention, denoted as Mn-RT-NW.

[0051] Example 2

[0052] (1) Grind 25g of manganese acetate tetrahydrate for 10min and put it into a crucible. Then place the crucible in a muffle furnace and heat it to 450℃ at a heating rate of 1℃ / min. Calcine for 2h to obtain Mn3O4 catalyst. Then grind and press the catalyst into tablets.

[0053] (2) Place 0.3g of the Mn3O4 catalyst in a tube furnace, purge the manganese-based catalyst with an inactive gas at a flow rate of 100mL / min at 150°C for 30min, and then introduce a modified gas into the tube furnace, adjusting the temperature to 100°C, the gas flow rate to 100mL / min, and the gas space velocity to 20000mL·g. -1 ·h -1 The manganese-based catalyst is adsorbed in the modified gas atmosphere for 1 hour. After the adsorption is completed, the temperature is adjusted to 30°C. Then, an inactive gas with a flow rate of 100 mL / min is introduced into the tube furnace to purge the manganese-based catalyst for 30 minutes. The modified gas contains 5% by volume oxygen, 500 ppm nitric oxide and 95% by volume nitrogen.

[0054] (3) Take out the modified Mn3O4 catalyst into a 100mL reagent bottle, add 100mL of water, tighten the cap, set the ultrasonic pool power to 100W, place the reagent bottle in the ultrasonic pool and sonicate for 2h. After sonication, filter the mixture in the reagent bottle, and then air dry the filter paper at 30℃ for 24h to obtain the modified manganese-based denitrification catalyst of the present invention, denoted as Mn-100-NW.

[0055] Example 3

[0056] (1) Grind 25g of manganese acetate tetrahydrate for 10min and put it into a crucible. Then place the crucible in a muffle furnace and heat it to 450℃ at a heating rate of 1℃ / min. Calcine for 2h to obtain Mn3O4 catalyst. Then grind and press the catalyst into tablets.

[0057] (2) Place 0.3g of the Mn3O4 catalyst in a tube furnace, purge the manganese-based catalyst with an inactive gas at a flow rate of 100mL / min at 150°C for 30min, and then introduce a modified gas into the tube furnace, adjusting the temperature to 200°C, the gas flow rate to 150mL / min, and the gas space velocity to 30000mL·g. -1 ·h -1 The manganese-based catalyst is adsorbed in the modified gas atmosphere for 1 hour. After the adsorption is completed, the temperature is adjusted to 30°C. Then, an inactive gas with a flow rate of 100 mL / min is introduced into the tube furnace to purge the manganese-based catalyst for 30 minutes. The modified gas contains 8% by volume oxygen, 600 ppm nitric oxide and 92% by volume nitrogen.

[0058] (3) Take out the modified Mn3O4 catalyst into a 100mL reagent bottle, add 100mL of water, tighten the cap, set the ultrasonic pool power to 100W, place the reagent bottle in the ultrasonic pool and sonicate for 2h. After sonication, filter the mixture in the reagent bottle, and then air dry the filter paper at 30℃ for 30h to obtain the modified manganese-based denitrification catalyst of the present invention, denoted as Mn-200-NW.

[0059] Example 4

[0060] (1) Grind 15g of manganese acetate tetrahydrate and 27g of cerium nitrate hexahydrate for 10min and put them into a crucible. Then place the crucible in a muffle furnace and heat it to 450℃ at a heating rate of 1℃ / min. Calcine it for 2h to obtain MnCe catalyst. Then grind and press the catalyst into tablets. The molar ratio of manganese acetate tetrahydrate to cerium nitrate hexahydrate is 1:1.

[0061] (2) Place 0.3g of the MnCe catalyst in a tube furnace, purge the manganese-based catalyst for 30min at 150°C with an inactive gas at a flow rate of 100mL / min, and then introduce a modified gas into the tube furnace, adjusting the temperature to 30°C, the gas flow rate to 100mL / min, and the gas space velocity to 20000mL·g. -1 ·h -1 The manganese-based catalyst is adsorbed in the modified gas atmosphere for 1 hour. After the adsorption is completed, the temperature is adjusted to 30°C, and then an inactive gas with a flow rate of 100 mL / min is introduced into the tube furnace to purge the manganese-based catalyst for 30 minutes. The modified gas contains 3% by volume oxygen, 400 ppm nitric oxide and 97% by volume nitrogen.

[0062] (3) Take out the modified MnCe catalyst into a 100mL reagent bottle, add 100mL of water, tighten the cap, set the ultrasonic pool power to 100W, place the reagent bottle in the ultrasonic pool and sonicate for 2h. After sonication, filter the mixture in the reagent bottle, and then air dry the filter paper at 30℃ for 18h to obtain the modified manganese-based denitrification catalyst of the present invention, denoted as MnCe-RT-NW.

[0063] Example 5

[0064] (1) Grind 20g of manganese acetate tetrahydrate and 35g of cerium nitrate hexahydrate for 10min and put them into a crucible. Then place the crucible in a muffle furnace and heat it to 450℃ at a heating rate of 3℃ / min. Calcine it for 2h to obtain MnCe catalyst. Then grind and press the catalyst into tablets. The molar ratio of manganese acetate tetrahydrate to cerium nitrate hexahydrate is 1:1.

[0065] (2) Place 0.3g of the MnCe catalyst in a tube furnace, purge the manganese-based catalyst with an inactive gas at a flow rate of 100mL / min at 150°C for 30min, and then introduce a modified gas into the tube furnace, adjusting the temperature to 100°C, the gas flow rate to 100mL / min, and the gas space velocity to 20000mL·g. -1 ·h -1 The manganese-based catalyst is adsorbed in the modified gas atmosphere for 1 hour. After the adsorption is completed, the temperature is adjusted to 30°C. Then, an inactive gas with a flow rate of 100 mL / min is introduced into the tube furnace to purge the manganese-based catalyst for 30 minutes. The modified gas contains 5% by volume oxygen, 500 ppm nitric oxide and 95% by volume nitrogen.

[0066] (3) Take out the modified MnCe catalyst into a 100mL reagent bottle, add 100mL of water, tighten the cap, set the ultrasonic pool power to 100W, place the reagent bottle in the ultrasonic pool and sonicate for 2h. After sonication, filter the mixture in the reagent bottle, and then air dry the filter paper at 30℃ for 24h to obtain the modified manganese-based denitrification catalyst of the present invention, denoted as MnCe-100-NW.

[0067] Example 6

[0068] (1) Grind 30g of manganese acetate tetrahydrate and 53g of cerium nitrate hexahydrate for 10min and put them into a crucible. Then place the crucible in a muffle furnace and heat it to 450℃ at a heating rate of 10℃ / min. Calcine it for 2h to obtain MnCe catalyst. Then grind and press the catalyst into tablets. The molar ratio of manganese acetate tetrahydrate to cerium nitrate hexahydrate is 1:1.

[0069] (2) Place 0.3g of the MnCe catalyst in a tube furnace, purge the manganese-based catalyst with an inactive gas at a flow rate of 100mL / min at 150°C for 30min, and then introduce a modified gas into the tube furnace, adjusting the temperature to 200°C, the gas flow rate to 150mL / min, and the gas space velocity to 30000mL·g. -1 ·h -1 The manganese-based catalyst is adsorbed in the modified gas atmosphere for 1 hour. After the adsorption is completed, the temperature is adjusted to 30°C. Then, an inactive gas with a flow rate of 100 mL / min is introduced into the tube furnace to purge the manganese-based catalyst for 30 minutes. The modified gas contains 8% by volume oxygen, 600 ppm nitric oxide and 92% by volume nitrogen.

[0070] (3) Take out the modified MnCe catalyst into a 100mL reagent bottle, add 100mL of water, tighten the cap, set the ultrasonic pool power to 150W, place the reagent bottle in the ultrasonic pool and sonicate for 3h. After sonication, filter the mixture in the reagent bottle, and then air dry the filter paper at 30℃ for 30h to obtain the modified manganese-based denitrification catalyst of the present invention, denoted as MnCe-200-NW.

[0071] Comparative Example 1

[0072] This comparative example is carried out according to the method described in Example 2, except that in step (2), nitrogen is used instead of the modified gas.

[0073] Comparative Example 2

[0074] This comparative example is carried out according to the method described in Example 2, except that in step (2), the modified gas contains 15% by volume oxygen, 900 ppm nitric oxide and 85% by volume nitrogen.

[0075] Comparative Example 3

[0076] This comparative example was carried out according to the method described in Example 2, except that in step (2), the manganese-based catalyst was placed in a modified gas atmosphere for adsorption and was not subjected to ultrasonic water washing.

[0077] Test Example 1

[0078] In this test example, XRD characterization was used to characterize the modified manganese-based denitrification catalysts Mn-100-NW and MnCe-100-NW prepared in Examples 2 and 5, as described in this invention. The results are as follows: Figure 1 As shown.

[0079] Depend on Figure 1 It can be seen that the main component of the modified manganese-based denitrification catalyst Mn-100-NW is Mn3O4, and the XRD results of the modified manganese-based denitrification catalyst MnCe-100-NW are similar to those of CeO2, indicating that MnO x It mainly exists in a dispersed state on the CeO2 surface.

[0080] Test Example 2

[0081] This test example uses a UV spectrophotometer to test the types of nitrogen oxides desorbed from the surface of the modified manganese-based denitrification catalysts prepared in Examples 1-6 and introduced into the water. The test includes the following steps: preheating the UV spectrophotometer, taking 1 mL of the filtrate separated in step (3) of Examples 1-6 respectively, and measuring the NO content in the filtrate after preheating. x Absorbance.

[0082] At wavelengths of 220nm and 275nm, according to The formula is used to calculate NO3 in the solution. - The absorbance; at a wavelength of 540 nm, the NO2 in the solution was measured. - The absorbance is measured, and the concentration of the solution is determined according to the Lambert-Beer law.

[0083] Depend on Figure 2 It can be seen that the modified gas is adsorbed on the surface of the manganese-based catalyst and reacts to generate NO3. - and NO2 - Species such as [unspecified species], after ultrasonic water washing, remove NO3. - and NO2 - Wash it off.

[0084] Test Example 3

[0085] This test example illustrates the denitrification catalytic performance of the modified manganese-based denitrification catalyst prepared in the comparative examples. The test was conducted in a fixed-bed continuous flow quartz reactor. The catalyst particle size was 20-40 mesh, and the dosage was 100 mg. The reaction gas composition was: 500 ppm NO, 500 ppm NH3, 5% O2, with N2 as the equilibrium gas. The gas hourly space velocity (GHSV) was 60,000 mL·g⁻¹. -1 ·h -1 Before the reaction, the catalyst needs to be purged with high-purity N2 at 150°C for 0.5 h. The catalytic reaction is carried out at 150°C, and activity data are collected after the reaction reaches equilibrium. The NO conversion rate is calculated using the following formula:

[0086]

[0087]

[0088] As can be seen from the results in Table 1, compared with Comparative Examples 1 to 3, the modified manganese-based denitrification catalysts prepared in Examples 1-6 have better low-temperature denitrification catalytic performance. When using the modified manganese-based denitrification catalysts prepared in Examples 1-6 for catalytic denitrification at 150°C, the NO conversion rate can reach more than 60%. In particular, in Examples 4-6, when using MnCe-RT-NW, MnCe-100-NW and MnCe-200-NW for denitrification catalysis at 150°C, the NO conversion rate can reach more than 87%.

[0089] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a modified manganese-based denitration catalyst, characterized in that, The method includes the following steps: (1) Mix and grind manganese salt and optional cerium salt, and then calcine the resulting mixture to obtain a manganese-based catalyst; (2) The manganese-based catalyst is placed in a modified gas atmosphere for adsorption, then the manganese-based catalyst is mixed with water and sonicated, and then the separated solid product is dried. The modified gas contains 3-8% by volume oxygen, 400-600 ppm nitric oxide, and 92-97% by volume inactive gas.

2. The method according to claim 1, characterized in that, In step (1), the manganese salt is selected from at least one of manganese acetate tetrahydrate, potassium permanganate, and manganese nitrate; and / or The cerium salt is selected from cerium nitrate and / or cerium acetate hydrate.

3. The method according to claim 1 or 2, characterized in that, In step (1), the molar ratio of the manganese salt to the cerium salt is 1-10:

1.

4. The method according to claim 1, characterized in that, In step (1), the grinding time is 1-10 min.

5. The method according to claim 1, characterized in that, In step (1), the calcination conditions include: a temperature of 300-600℃, a time of 1-10h, and a heating rate of 1-10℃ / min.

6. The method according to claim 1, characterized in that, In step (2), the adsorption conditions include: a temperature of 30-300℃, a time of 0.5-2h, a gas flow rate of 100-150mL / min, and a gas hourly space velocity of 20000-70000mL·g. -1 ·h -1 .

7. The method according to claim 1, characterized in that, In step (2), the weight ratio of water to manganese-based catalyst is 100-500:

1.

8. The method according to claim 1, characterized in that, In step (2), the conditions for ultrasound include: power of 100-150W and time of 2-3h.

9. The method according to claim 1, characterized in that, In step (2), the drying conditions include a temperature of 30-50°C and a time of 18-30 hours.

10. The modified manganese-based denitrification catalyst prepared by the method according to any one of claims 1-9.

Images