Modified manganese-based denitration catalyst and preparation method thereof

Abstract

The invention relates to the field of catalyst preparation, and discloses a modified manganese-based denitration catalyst and a preparation method thereof. The method comprises the following steps: mixing and grinding manganese salt and optional cerium salt, and roasting the obtained mixture to obtain the manganese-based catalyst, the method comprises the following steps: placing a manganese-based catalyst in a modified gas atmosphere for adsorption, then mixing the manganese-based catalyst with water, carrying out ultrasonic treatment, and then drying a separated solid product; wherein the modified gas contains the following components in percentage by volume: 3-8% of oxygen, 400-600 ppm of nitric oxide and 92-97% of inert gas. The modified manganese-based denitration catalyst has excellent low-temperature denitration performance, denitration catalysis is carried out at the temperature of 150 DEG C, and the NO conversion rate can reach 60% or above.

Description

Technical Field

[0001] The invention relates to the field of catalyst preparation, and in particular to a modified manganese-based denitration catalyst and a preparation method thereof. Background Art

[0002] Industrial production and urban transportation emit a large amount of nitrogen oxides, which easily form smog, photochemical smog, acid rain and other problems, causing great harm to the surrounding environment. 3 Selective catalytic reduction of NO(NH 3 -SCR) has been widely used due to its high denitration efficiency and low operating cost. The chemical composition of its corresponding commercial denitration catalyst is V 2 O 5 -WO 3 / TiO 2 . Business VO x -WO x / TiO 2 Although the catalyst has been widely used in flue gas denitrification of coal-fired power plants, it still has the following problems: narrow operating temperature range (300-400℃), easy alkali / alkaline earth metal poisoning, and active component V 2 O 5 In addition, with the successful implementation of the ultra-low emission policy in the power industry, the steel, glass, cement and other industries have x The emission requirements are getting higher and higher, and the flue gas conditions in these industries are such that commercial V-based catalysts are difficult to apply directly. Therefore, the development of low-temperature denitrification catalysts has become a hot issue in recent years.

[0003] Currently, most research is devoted to developing transition metal oxide catalysts to replace commercial vanadium-based catalysts. Researchers have tried a variety of transition metal oxides for low-temperature denitrification, including manganese oxide, copper oxide, cerium oxide, and titanium oxide. Among them, manganese-based catalysts have become an important candidate catalyst due to their rich valence states, excellent redox properties, and certain sulfur resistance.

[0004] At present, various types of manganese-based catalysts have been invented and studied, and modification methods to improve the performance of manganese-based catalysts have also emerged in an endless stream. Compared with the common doping modification in the prior art, how to use low-cost treatment methods to improve the denitrification performance of manganese-based catalysts at low temperatures and make them widely used in practice has important theoretical value and practical significance. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of high modification cost and poor denitration performance of manganese-based denitration catalysts in the prior art, and to provide a modified manganese-based denitration catalyst and a preparation method thereof. The method pre-adsorbs the manganese-based catalyst by a modified atmosphere, and then uses an ultrasonic-assisted water washing method to remove NO adsorbed on the surface.x The species are removed, and the acidity and redox properties of the manganese-based catalyst are improved, thereby improving the low-temperature denitration performance of the manganese-based catalyst.

[0006] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a modified manganese-based denitration catalyst, the method comprising the following steps: (1) mixing and grinding a manganese salt and an optional cerium salt, and then calcining the resulting mixture to obtain a manganese-based catalyst; (2) placing the manganese-based catalyst in a modified gas atmosphere for adsorption, then mixing the manganese-based catalyst with water and ultrasonicating, and then drying the separated solid product; The modified gas contains 3-8 volume % of oxygen, 400-600 ppm of nitric oxide and 92-97 volume % of inactive gas.

[0007] Preferably, in step (1), the manganese salt is selected from at least one of manganese acetate tetrahydrate, potassium permanganate and manganese nitrate.

[0008] Preferably, the cerium salt is selected from at least one of cerium nitrate hexahydrate, cerium nitrate and cerium acetate hydrate.

[0009] Preferably, in step (1), the molar ratio of the manganese salt to the cerium salt is 1-10:1.

[0010] Preferably, in step (1), the grinding time is 1-30 min.

[0011] Preferably, in step (1), the calcination conditions include: temperature of 300-600°C, time of 1-10h, and heating rate of 1-10°C / min.

[0012] Preferably, in step (2), the adsorption conditions include: temperature of 30-300°C, time of 0.5-2h, gas flow rate of 100-150mL / min, gas space velocity of 20000-70000mL·g -1 ·h -1 .

[0013] Preferably, in step (2), the weight ratio of the water to the manganese-based catalyst is 100-500:1.

[0014] Preferably, in step (2), the ultrasonic conditions include: power of 100-150W, and time of 2-3h.

[0015] Preferably, in step (2), the drying conditions include: temperature of 30-50° C. and time of 18-30 h.

[0016] The second aspect of the present invention provides a modified manganese-based denitration catalyst prepared by the method described above.

[0017] The preparation method of the modified manganese-based denitration catalyst of the present invention comprises pre-adsorbing the manganese-based catalyst with a modified atmosphere, and then washing the NO adsorbed on the surface with ultrasonic-assisted water. x The species are removed, the surface material of the manganese-based catalyst is reconstructed, the acidity and redox properties of the manganese-based catalyst are improved, and the low-temperature denitration performance of the manganese-based catalyst is improved. The modified manganese-based denitration catalyst of the present invention has excellent low-temperature denitration performance, and the NO conversion rate can reach more than 60% when denitration catalysis is carried out at 150°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 XRD patterns of Mn-100-NW prepared in Example 2 and MnCe-100-NW prepared in Example 5; Figure 2 NO adsorbed on the surfaces 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 spectra of species. DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0020] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0021] The preparation method of the modified manganese-based denitration catalyst of the present invention comprises the following steps: (1) mixing and grinding a manganese salt and an optional cerium salt, and then calcining the resulting mixture to obtain a manganese-based catalyst; (2) placing the manganese-based catalyst in a modified gas atmosphere for adsorption, then mixing the manganese-based catalyst with water and ultrasonicating, and then drying the separated solid product; The modified gas contains 3-8 volume % of oxygen, 400-600 ppm of nitric oxide and 92-97 volume % of inactive gas.

[0022] In the most preferred embodiment, the modified gas contains 5±0.5 volume % oxygen, 500±10 ppm nitrogen monoxide and 95±0.5 volume % inactive gas. In the present invention, when the content of the components in the modified gas is within the above range, the modified manganese-based denitration catalyst has better catalytic activity.

[0023] In the present invention, the inactive gas refers to a gas that does not react with the manganese-based catalyst. In a specific embodiment, the inactive gas can be nitrogen and / or an inert gas (such as argon), preferably nitrogen.

[0024] In the present invention, in step (1), the manganese salt may be at least one of manganese acetate tetrahydrate, potassium permanganate and manganese nitrate, preferably manganese acetate tetrahydrate.

[0025] In the present invention, the cerium salt may be at least one of cerium nitrate hexahydrate, cerium nitrate and cerium acetate hydrate, preferably cerium nitrate hexahydrate.

[0026] In the method of the present 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 the present invention, when the molar ratio of the manganese salt to the cerium salt is within the above range (especially within the preferred range), the prepared MnCe catalyst has better denitration performance.

[0027] In the method of the present invention, in step (1), the grinding time can be 1-30 min, preferably 5-15 min. In the present invention, when the grinding time is within the above range (especially within the preferred range), the prepared manganese-based catalyst has better deoxidation performance.

[0028] In the method of the present invention, in step (1), the calcination conditions may include: temperature of 300-600°C, preferably 400-500°C; time of 1-10h, preferably 1-5h; heating rate of 1-10°C / min, preferably 1-5°C / min. In the method of the present invention, when the calcination conditions are within the above range (especially within the preferred range), the prepared catalyst has a better pore structure.

[0029] In some embodiments, the process of preparing the manganese-based catalyst comprises: grinding the manganese salt for 1-30 min, placing it in a muffle furnace, heating it to 300-600° C. at a heating rate of 1-10° C. / min, and calcining it for 1-10 h to obtain Mn 3 O 4When step (1) is implemented according to this embodiment, Mn with good denitration catalytic performance can be obtained. 3 O 4 catalyst.

[0030] In other embodiments, the process of preparing the manganese-based catalyst includes: mixing a manganese salt and a cerium salt in a molar ratio of 1-10:1, grinding for 1-30 minutes, placing in a muffle furnace, heating to 300-600°C at a heating rate of 1-10°C / min, calcining for 1-10 hours to obtain a MnCe catalyst, and then grinding and tableting the catalyst. When step (1) is implemented according to this embodiment, a MnCe catalyst with better denitration catalytic performance can be obtained.

[0031] In the method of the present invention, in step (2), the adsorption conditions may include: temperature of 30-300°C, preferably 30-200°C; time of 0.5-2h, preferably 0.5-1h; gas flow rate of 100-150mL / min, preferably 100-120mL / min; gas space velocity of 20000-70000mL·g -1 ·h -1 , preferably 20000-60000mL·g -1 ·h -1 In the method of the present invention, when the adsorption conditions are within the above range (especially within the preferred range), more NO is adsorbed on the surface of the manganese-based catalyst. x Species.

[0032] In the method described in the present invention, the adsorption modification process of the manganese-based catalyst may also include: using an inactive gas at a flow rate of 50-200 mL / min to purge the manganese-based catalyst for 10-60 minutes at 100-200°C, then placing the manganese-based catalyst in a modified gas atmosphere for adsorption, and after the adsorption is completed, using an inactive gas at a flow rate of 50-200 mL / min to purge the manganese-based catalyst for 10-60 minutes at 100-200°C. In the method described in the present invention, when the adsorption process is implemented according to the above method, more NO is adsorbed on the surface of the manganese-based catalyst. x Species.

[0033] In the method of the present invention, in step (2), the weight ratio of the water to the manganese-based catalyst may be 100-500:1, preferably 200-400:1. In the method of the present invention, when the weight ratio of the water to the manganese-based catalyst is within the above range (especially within the preferred range), the NO on the surface of the manganese-based catalyst is x Species removal is more thorough.

[0034] In the method of the present invention, in step (2), the ultrasonic conditions may include: power of 100-150W, preferably 90-120W; time of 2-3h, preferably 2-2.5h. In the method of the present invention, when the ultrasonic conditions are within the above range (especially within the preferred range), the NO on the surface of the manganese-based catalyst is x Species removal is more thorough.

[0035] In the method of the present invention, in step (2), the drying conditions may include: a temperature of 30-50° C., preferably 30-40° C.; and a drying time of 18-30 h, preferably 20-24 h.

[0036] In some embodiments, the ultrasonic washing process of the manganese-based catalyst further comprises: placing water and the adsorption-modified manganese-based catalyst in a weight ratio of 100-500:1 into a container, placing the container in an ultrasonic tank and ultrasonicating for 2-3 hours at a power of 100-150 W, filtering the mixture in the container and naturally air-drying the separated solid product at 30-50° C. for 18-30 hours. When step (2) is implemented according to this embodiment, a modified manganese-based denitration catalyst with better denitration catalytic performance can be obtained.

[0037] The present invention also provides a modified manganese-based denitration catalyst prepared by the above method. The modified manganese-based denitration catalyst is modified, and the surface material is reconstructed, thereby improving the acidity and redox properties of the manganese-based catalyst, thereby improving the low-temperature denitration performance of the manganese-based catalyst. Specifically, the modified manganese-based denitration catalyst of the present invention has excellent low-temperature denitration performance, and the NO conversion rate can be significantly improved when catalytic denitration is carried out at 150°C.

[0038] The modified manganese-based denitration catalyst and its preparation method of the present invention are further illustrated by examples. The examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0039] The experimental methods in the following examples and comparative examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples and comparative examples, unless otherwise specified, are all commercially available.

[0040] Example 1 (1) Grind 25 g of manganese acetate tetrahydrate for 10 min and put it into a crucible. Then place the crucible in a muffle furnace and heat it to 450 °C at a heating rate of 1 °C / min. Calcinate for 2 h to obtain Mn 3 O 4 Catalyst, then grinding and tableting the catalyst; (2) 0.3 g of the Mn3 O 4 The catalyst was placed in a tubular furnace, and an inactive gas with a flow rate of 100 mL / min was introduced into the manganese-based catalyst for 30 min at 150 ° C. Then, a modified gas was introduced into the tubular furnace, and the temperature was adjusted to 30 ° C, the gas flow rate was 100 mL / min, and the gas space velocity was 20000 mL·g -1 ·h -1 , the manganese-based catalyst is adsorbed for 1 hour in the modified gas atmosphere, and after the adsorption is completed, an inactive gas with a flow rate of 100 mL / min is introduced into the tubular furnace to purge the manganese-based catalyst for 30 minutes, wherein the modified gas contains 3% by volume of oxygen, 400 ppm of nitric oxide and 97% by volume of nitrogen; (3) Taking out the modified Mn 3 O 4 The catalyst is placed in a reagent bottle with a capacity of 100 mL, and 100 mL of water is added. The bottle cap is tightened, and the power of the ultrasonic pool is set to 100 W. The reagent bottle is placed in the ultrasonic pool for ultrasonication for 2 hours. After the ultrasonication is completed, the mixture in the reagent bottle is filtered, and the filter paper is naturally air-dried at 30° C. for 24 hours to obtain the modified manganese-based denitrification catalyst of the present invention, which is recorded as Mn-RT-NW.

[0041] Example 2 (1) Grind 25 g of manganese acetate tetrahydrate for 10 min and put it into a crucible. Then place the crucible in a muffle furnace and heat it to 450 °C at a heating rate of 1 °C / min. Calcinate for 2 h to obtain Mn 3 O 4 Catalyst, then grinding and tableting the catalyst; (2) 0.3 g of the Mn 3 O 4 The catalyst was placed in a tubular furnace, and an inactive gas with a flow rate of 100 mL / min was introduced into the manganese-based catalyst for 30 min at 150 ° C. Then, a modified gas was introduced into the tubular furnace, and the temperature was adjusted to 100 ° C., the gas flow rate was 100 mL / min, and the gas space velocity was 20000 mL·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 tubular furnace to purge the manganese-based catalyst for 30 minutes, wherein the modified gas contains 5% by volume of oxygen, 500 ppm of nitric oxide and 95% by volume of nitrogen; (3) Taking out the modified Mn 3 O 4The catalyst is placed in a reagent bottle with a capacity of 100 mL, and 100 mL of water is added. The bottle cap is tightened, and the power of the ultrasonic pool is set to 100 W. The reagent bottle is placed in the ultrasonic pool for ultrasonication for 2 hours. After the ultrasonication is completed, the mixture in the reagent bottle is filtered, and the filter paper is naturally air-dried at 30° C. for 24 hours to obtain the modified manganese-based denitration catalyst of the present invention, which is recorded as Mn-100-NW.

[0042] Example 3 (1) Grind 25 g of manganese acetate tetrahydrate for 10 min and put it into a crucible. Then place the crucible in a muffle furnace and heat it to 450 °C at a heating rate of 1 °C / min. Calcinate for 2 h to obtain Mn 3 O 4 Catalyst, then grinding and tableting the catalyst; (2) 0.3 g of the Mn 3 O 4 The catalyst was placed in a tubular furnace, and an inactive gas with a flow rate of 100 mL / min was introduced into the manganese-based catalyst for 30 min at 150 ° C. Then, a modified gas was introduced into the tubular furnace, and the temperature was adjusted to 200 ° C, the gas flow rate was 150 mL / min, and the gas space velocity was 30000 mL·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 tubular furnace to purge the manganese-based catalyst for 30 minutes, wherein the modified gas contains 8% by volume of oxygen, 600 ppm of nitric oxide and 92% by volume of nitrogen; (3) Taking out the modified Mn 3 O 4 The catalyst is placed in a reagent bottle with a capacity of 100 mL, and 100 mL of water is added. The bottle cap is tightened, and the power of the ultrasonic pool is set to 100 W. The reagent bottle is placed in the ultrasonic pool for ultrasonication for 2 hours. After the ultrasonication is completed, the mixture in the reagent bottle is filtered, and the filter paper is naturally air-dried at 30° C. for 30 hours to obtain the modified manganese-based denitration catalyst of the present invention, which is recorded as Mn-200-NW.

[0043] Example 4 (1) Grinding 15 g of manganese acetate tetrahydrate and 27 g of cerium nitrate hexahydrate for 10 min and placing them in a crucible, then placing the crucible in a muffle furnace, heating the temperature to 450° C. at a heating rate of 1° C. / min, and calcining for 2 h to obtain a MnCe catalyst, and then grinding the catalyst into tablets, wherein the molar ratio of the manganese acetate tetrahydrate to the cerium nitrate hexahydrate is 1:1; (2) 0.3 g of the MnCe catalyst was placed in a tubular furnace, and an inactive gas with a flow rate of 100 mL / min was introduced into the manganese-based catalyst for 30 min at 150 ° C. Then, a modified gas was introduced into the tubular furnace, and the temperature was adjusted to 30 ° C., the gas flow rate was 100 mL / min, and the gas space velocity was 20000 mL·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 tubular furnace to purge the manganese-based catalyst for 30 minutes, wherein the modified gas contains 3% by volume of oxygen, 400 ppm of nitric oxide and 97% by volume of nitrogen; (3) Take out the modified MnCe catalyst and place it in a reagent bottle with a capacity of 100 mL. Then add 100 mL of water, tighten the bottle cap, set the ultrasonic pool power to 100 W, place the reagent bottle in the ultrasonic pool for ultrasonication for 2 h, filter the mixture in the reagent bottle after the ultrasonication, and then naturally air-dry the filter paper at 30 ° C for 18 h to obtain the modified manganese-based denitrification catalyst of the present invention, which is recorded as MnCe-RT-NW.

[0044] Example 5 (1) Grinding 20 g of tetrahydrate manganese acetate and 35 g of hexahydrate cerium nitrate for 10 min and placing them in a crucible, then placing the crucible in a muffle furnace, heating the temperature to 450° C. at a heating rate of 3° C. / min, and calcining for 2 h to obtain a MnCe catalyst, and then grinding and pressing the catalyst into tablets, wherein the molar ratio of the tetrahydrate manganese acetate to the hexahydrate cerium nitrate is 1:1; (2) 0.3 g of the MnCe catalyst was placed in a tubular furnace, and an inactive gas with a flow rate of 100 mL / min was introduced into the manganese-based catalyst for 30 min at 150 ° C. Then, a modified gas was introduced into the tubular furnace, and the temperature was adjusted to 100 ° C., the gas flow rate was 100 mL / min, and the gas space velocity was 20000 mL·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 tubular furnace to purge the manganese-based catalyst for 30 minutes, wherein the modified gas contains 5% by volume of oxygen, 500 ppm of nitric oxide and 95% by volume of nitrogen; (3) Take out the modified MnCe catalyst and place it in a reagent bottle with a capacity of 100 mL. Then add 100 mL of water, tighten the bottle cap, set the ultrasonic pool power to 100 W, place the reagent bottle in the ultrasonic pool for 2 h, filter the mixture in the reagent bottle after the ultrasonic treatment, and then naturally air-dry the filter paper at 30 ° C for 24 h to obtain the modified manganese-based denitrification catalyst of the present invention, which is recorded as MnCe-100-NW.

[0045] Example 6 (1) grinding 30 g of manganese acetate tetrahydrate and 53 g of cerium nitrate hexahydrate for 10 min and then placing them in a crucible, then placing the crucible in a muffle furnace, heating the temperature to 450° C. at a heating rate of 10° C. / min, and calcining for 2 h to obtain a MnCe catalyst, then grinding the catalyst and pressing it into tablets, wherein the molar ratio of the manganese acetate tetrahydrate to the cerium nitrate hexahydrate is 1:1; (2) 0.3 g of the MnCe catalyst was placed in a tubular furnace, and an inactive gas with a flow rate of 100 mL / min was introduced into the manganese-based catalyst for 30 min at 150 ° C. Then, a modified gas was introduced into the tubular furnace, and the temperature was adjusted to 200 ° C., the gas flow rate was 150 mL / min, and the gas space velocity was 30000 mL·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 tubular furnace to purge the manganese-based catalyst for 30 minutes, wherein the modified gas contains 8% by volume of oxygen, 600 ppm of nitric oxide and 92% by volume of nitrogen; (3) Take out the modified MnCe catalyst and place it in a reagent bottle with a capacity of 100 mL. Then add 100 mL of water, tighten the bottle cap, set the ultrasonic pool power to 150 W, place the reagent bottle in the ultrasonic pool for ultrasonication for 3 h, filter the mixture in the reagent bottle after the ultrasonication, and then naturally air-dry the filter paper at 30 ° C for 30 h to obtain the modified manganese-based denitrification catalyst of the present invention, which is recorded as MnCe-200-NW.

[0046] Comparative Example 1 This comparative example is implemented according to the method described in Example 2, except that in step (2), nitrogen is used instead of the modifying gas.

[0047] Comparative Example 2 This comparative example was carried out according to the method described in Example 2, except that in step (2), the modified gas contained 15 volume % oxygen, 900 ppm nitric oxide and 85 volume % nitrogen.

[0048] Comparative Example 3 This comparative example was carried out in accordance with the method described in Example 2, except that in step (2), the manganese-based catalyst was placed in a modified gas atmosphere for adsorption without ultrasonic water washing.

[0049] Test Example 1 In this test example, XRD was used to characterize the modified manganese-based denitration catalysts Mn-100-NW and MnCe-100-NW prepared in Example 2 and Example 5. The results are as follows: Figure 1 shown.

[0050] Depend on Figure 1 It can be seen that the main component of the modified manganese-based denitration catalyst Mn-100-NW is Mn 3 O 4 The XRD results of the modified manganese-based denitrification catalyst MnCe-100-NW are similar to those of CeO 2 Similar, indicating that MnO x Mainly exists in the form of dispersion in CeO 2 surface.

[0051] Test Example 2 In this test example, an ultraviolet spectrophotometer is used to test the types of nitrogen oxide substances desorbed into water from the surface of the modified manganese-based denitrification catalyst prepared in Examples 1-6. The test includes the following steps: preheating the ultraviolet spectrophotometer, taking 1 mL of the filtrate separated in step (3) of Examples 1-6, and measuring the NO in the filtrate after preheating. x The absorbance.

[0052] At wavelengths of 220nm and 275nm, according to The NO in the solution can be calculated by the formula 3 - The absorbance of NO in the solution was measured at a wavelength of 540 nm. 2 - The absorbance of the substance is measured and the concentration of the substance solution is determined based on the Lambert-Beer law.

[0053] 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 NO 3 - and NO 2 - After ultrasonic washing, NO 3 - and NO 2 - Wash off.

[0054] Test Example 3 This test example is used to illustrate the denitration catalytic performance of the modified manganese-based denitration catalyst prepared in the embodiment and the comparative example. The test was carried out 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 NH 3 , 5%O 2 , N 2 As the balance gas, the gas space velocity in the reaction is 60000mL·g -1 ·h -1 Before the reaction, the catalyst needs to be treated with high-purity N 2 Purge at 150°C for 0.5h. The catalytic reaction was carried out at 150°C, and the activity data was collected after the reaction reached equilibrium. The NO conversion rate was calculated by the following formula:

[0055]

[0056] It can be seen from the results in Table 1 that compared with Comparative Examples 1 to 3, the modified manganese-based denitration catalysts prepared in Examples 1-6 have better low-temperature denitration catalysis. When the modified manganese-based denitration catalysts prepared in Examples 1-6 are used for catalytic denitration at 150°C, the NO conversion rate can reach more than 60%; especially in Examples 4-6, when MnCe-RT-NW, MnCe-100-NW and MnCe-200-NW are used for denitration catalysis at 150°C, the NO conversion rate can reach more than 87%.

[0057] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a modified manganese-based denitration catalyst, characterized in that: The method comprises the following steps: (1) mixing and grinding a manganese salt and an optional cerium salt, and then calcining the resulting mixture to obtain a manganese-based catalyst; (2) placing the manganese-based catalyst in a modified gas atmosphere for adsorption, then mixing the manganese-based catalyst with water and ultrasonicating, and then drying the separated solid product; The modified gas contains 3-8 volume % of oxygen, 400-600 ppm of nitric oxide and 92-97 volume % of 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 at least one of cerium nitrate hexahydrate, cerium nitrate and 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: temperature of 300-600°C, time of 1-10h, and heating rate of 1-10°C / min.

6. The method according to claim 1, characterized in that In step (2), the adsorption conditions include: temperature of 30-300°C, time of 0.5-2h, gas flow rate of 100-150mL / min, gas 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 the water to the manganese-based catalyst is 100-500:

1.

8. The method according to claim 1, characterized in that In step (2), the ultrasonic conditions 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: temperature of 30-50°C and time of 18-30h.

10. A modified manganese-based denitration catalyst prepared by the method according to claims 1-9.

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