Wide-temperature SCR denitration catalyst, its preparation method for modifying the acidic sites of NO oxidation catalyst and application

Abstract

The present invention relates to a wide-temperature SCR denitration catalyst, a preparation method for modifying the acidic sites of its NO oxidation catalyst, and an application. A wide-temperature SCR denitration catalyst is prepared by doping tungsten elements on the basis of an NO oxidation catalyst using a co-precipitation method. The NO oxidation catalyst is mullite-type SmMn2O5, and the chemical formula of this catalyst is Sm x W y Mn2O5, where x and y are the molar fractions of Sm and W elements respectively, and the values of x and y satisfy the following conditions: x is 0.95 to 0.99, y is 0.01 to 0.05, and x + y = 1. The present invention develops a wide-temperature SCR catalyst based on mullite-type SmMn2O5. Compared with the currently commercial vanadium-titanium-based SCR catalyst, the working temperature window is broadened, and the applicable range of the catalyst is greatly improved. It is a new type of low-cost wide-temperature SCR catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and relates to a preparation method of a denitration catalyst, in particular to a wide-temperature SCR denitration catalyst, a preparation method for modifying the acidic sites of its NO oxidation catalyst, and applications thereof. Background Art

[0002] China's energy structure dominated by coal will not undergo a fundamental change in a long period of time. Nitrogen oxides generated from coal combustion are one of the main air pollutants. In recent years, China has attached great importance to the problem of nitrogen oxide pollution, implemented a series of emission reduction measures, and put forward higher requirements for future nitrogen oxide emission reduction work.

[0003] Selective catalytic reduction (SCR) technology is currently the most mature and widely used denitration technology. However, the operating temperature window of current commercial vanadium-titanium catalysts is 300 - 400 °C. When the temperature is lower than 300 °C, their catalytic efficiency will decrease significantly, and the ideal denitration effect cannot be achieved. In addition, the flue gas temperature of industrial sources in China is significantly lower than the operating temperature window of vanadium-titanium catalysts after dust removal and desulfurization. Moreover, the exhaust gas temperature of motor vehicles and marine diesel engines in the transportation field is also lower than the operating temperature window of vanadium-titanium catalysts during startup, idling, and partial load. Therefore, developing a wide-temperature SCR catalyst suitable for China's national conditions and applying it to the denitration of industrial source flue gas and engine exhaust has important significance for nitrogen oxide emission reduction. Summary of the Invention

[0004] The purpose of the present invention is to provide a wide-temperature SCR denitration catalyst. Based on the NO oxidation catalyst, the SCR denitration performance of this catalyst is improved by doping tungsten. It shows good SCR denitration activity in the temperature range of 150 - 350 °C. Especially at a temperature of 200 - 350 °C, it can successfully catalytically convert 100% of NO, solving the problem that the low-temperature activity of current commercial vanadium-titanium catalysts is low and the denitration efficiency is difficult to meet the requirements in the prior art.

[0005] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0006] A wide-temperature SCR denitration catalyst is prepared by coprecipitation on the basis of a NO oxidation catalyst doped with tungsten elements. The NO oxidation catalyst is mullite-type SmMn2O5.

[0007] The chemical formula of this catalyst is Sm x W y Mn2O5, where x and y are the molar fractions of Sm and W elements respectively, and the values of x and y satisfy the following conditions:

[0008] x is 0.95 - 0.99, y is 0.01 - 0.05, and x + y = 1.

[0009] Based on mullite-type SmMn2O5, the present invention has developed a wide-temperature SCR catalyst. Compared with the currently commercial vanadium-titanium-based SCR catalyst, it broadens the working temperature window, greatly improves the applicable range of the catalyst, and is a new type of low-cost wide-temperature SCR catalyst.

[0010] During the research work, the inventors accidentally found that doping with a small amount of tungsten element increases the specific surface area and pore size of the catalyst, and at the same time can increase the content of tetravalent manganese on the catalyst surface, providing more surface acidic reaction sites. Therefore, appropriate doping with tungsten element improves the SCR activity and N2 selectivity of the mullite catalyst, especially showing good catalytic denitrification performance in the wide temperature range of 150 - 350 °C.

[0011] Preferably, the chemical formula of the catalyst is Sm 0.99 W 0.01 Mn2O5. This catalyst can efficiently catalyze (100% NO conversion) and the catalytic working range is 200 - 350 °C.

[0012] A method for modifying the acidic sites of a NO oxidation catalyst of the wide-temperature SCR denitration catalyst described in the present invention, the method comprising the following steps:

[0013] S1. At a temperature of 30 - 60 °C, dissolve the surfactant in water to obtain solution A;

[0014] The surfactant is a mixture of PEG-600 and Pluronic F127, and their concentrations are 40 - 60 wt.% and 5 - 20 wt.% respectively;

[0015] S2. Dissolve the precursors manganese nitrate, samarium nitrate and ammonium metatungstate in solution A to obtain solution B;

[0016] S3. Dropwise add the precipitant into solution B and stir to adjust the pH of the solution to 9 - 11, then add the H2O2 solution and continue to stir to obtain precipitate C;

[0017] S4. After filtering the precipitate C by suction, through drying, calcination and grinding, obtain the wide-temperature SCR denitration catalyst.

[0018] Preferably, the precipitant in S3 is 15 - 45 wt.% of tetramethylammonium hydroxide or ammonia water. The alkaline environment provided by the precipitant should be sufficient to precipitate the precursors.

[0019] Preferably, in S3, the mass concentration of the H2O2 solution is 15-45%, the molar ratio of manganese nitrate to H2O2 is controlled to be 1:1-1:1.5, and the stirring time is 2-5 hours. The significance of controlling the molar ratio of manganese nitrate to H2O2 is that under these conditions, the ratio of manganese in different valence states in the product is optimal, resulting in the best catalyst performance. The optimal conditions in S3 are that the solution pH = 10, and the molar ratio of manganese nitrate to hydrogen peroxide is 1:1.3.

[0020] Preferably, in S4, the drying temperature is 60-110°C and the time is 8-14 hours; the calcination is divided into two stages. The temperature of the first stage is 400-600°C, the calcination time is 6-8 hours, the temperature of the second stage is 800-900°C, the calcination time is 6-8 hours, and the heating rate is 6-10°C / min; it is ground into particles of 60-120 mesh.

[0021] Preferably, the grinding in S4 results in catalyst powder particles with a particle size of 60-120 mesh.

[0022] An application of the wide-temperature SCR denitration catalyst described in the present invention in flue gas denitration, characterized in that: the wide temperature is in the range of 150-350°C.

[0023] Preferably, the wide temperature is in the range of 200-350°C. In the temperature range of 200-350°C, the catalytic conversion rate of the catalyst to NO is 100%.

[0024] Compared with the prior art, the present invention improves the SCR activity and N2 selectivity of the NO oxidation catalyst (mullite-type SmMn2O5) by doping a small amount of tungsten element. Especially in the wide temperature range of 150-350°C, it shows good catalytic denitration activity, broadens the application scenario of the SCR catalyst, and makes up for the deficiencies of existing commercial catalysts. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0026] Figure 1 is Sm 0.99 W 0.01 Mn2O5's NO conversion rate in the SCR reaction at different temperatures;

[0027] Figure 2 is Sm 0.99 W 0.01N2O (a) and NO2 (b) production of Mn2O5 in the SCR reaction at different temperatures;

[0028] Figure 3 is Sm 0.98 W 0.02 NO conversion rate of Mn2O5 in the SCR reaction at different temperatures;

[0029] Figure 4 is Sm 0.98 W 0.02 N2O (a) and NO2 (b) production of Mn2O5 in the SCR reaction at different temperatures;

[0030] Figure 5 is Sm 0.95 W 0.05 NO conversion rate of Mn2O5 in the SCR reaction at different temperatures;

[0031] Figure 6 is Sm 0.95 W 0.05 N2O (a) and NO2 (b) production of Mn2O5 in the SCR reaction at different temperatures;

[0032] Figure 7 is the NO conversion rate of SmMn2O5 in the SCR reaction at different temperatures;

[0033] Figure 8 is the N2O (a) and NO2 (b) production of SmMn2O5 in the SCR reaction at different temperatures;

[0034] Figure 9 is Sm of the comparative example 0.99 W 0.01 NO conversion rate of Mn2O5 in the SCR reaction at different temperatures;

[0035] Figure 10 is Sm of the comparative example 0.99 W 0.01 N2O (a) and NO2 (b) production of Mn2O5 in the SCR reaction at different temperatures;

[0036] Figure 11 is Sm prepared in Example 1 0.99 W 0.01 Microscopic morphology of Mn2O5;

[0037] Figure 12 is Sm prepared in Example 2 0.98 W 0.02 Microscopic morphology of Mn2O5;

[0038] Figure 13is the Sm prepared in Example 3 0.95 W 0.05 The microscopic morphology of Mn2O5;

[0039] Figure 14 is the microscopic morphology of SmMn2O5 prepared in Comparative Example 1;

[0040] Figure 15 is the Sm prepared in Comparative Example 2 0.99 W 0.01 The microscopic morphology of Mn2O5;

[0041] Figure 16 is the specific surface area of the catalysts prepared in Examples 1 - 3. Detailed implementation manners

[0042] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations for the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0043] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to this application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or their combinations.

[0044] The present invention will be further described in conjunction with specific examples below. The following examples are only for explaining the present invention and do not constitute a limitation to the present invention. The test samples and test processes used in the following examples include the following content (if the specific experimental conditions are not specified in the examples, they are usually in accordance with conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following examples can be obtained from commercial channels without special instructions).

[0045] The core of the present invention is to provide a wide - temperature SCR denitration catalyst, which is doped with tungsten elements on the basis of a NO oxidation catalyst (mullite - type SmMn2O5) and is prepared by the co - precipitation method. The NO oxidation catalyst is mullite - type SmMn2O5, and the chemical formula of this catalyst is Sm x W y Mn2O5, where x and y are the molar fractions of Sm and W elements respectively, and the values of x and y satisfy the following conditions: x is 0.95 - 0.99, y is 0.01 - 0.05, and x + y = 1.

[0046] Another core of the present invention is to provide a preparation method for modifying the acidic sites of the NO oxidation catalyst of the wide-temperature SCR denitration catalyst, and the method includes the following steps:

[0047] S1. At a temperature of 30-60°C, dissolve the surfactant in water to obtain solution A;

[0048] The surfactant is a mixture of PEG-600 and Pluronic F127, and their concentrations are 40-60 wt.% and 5-20 wt.% respectively;

[0049] S2. Dissolve the precursors manganese nitrate, samarium nitrate and ammonium metatungstate in solution A to obtain solution B;

[0050] S3. Dropwise add the precipitant to solution B and stir to adjust the pH of the solution to 9-11, and then add the H2O2 solution and continue to stir to obtain precipitate C;

[0051] S4. After filtering the precipitate C by suction, through drying, calcination and grinding, obtain the wide-temperature SCR denitration catalyst.

[0052] In the wide-temperature SCR denitration catalyst of the present invention, the molar ratio of the sum of samarium and tungsten to manganese is 1:2. In order not to damage the structure of mullite itself, the molar ratio of the precursor samarium nitrate to ammonium metatungstate is 19:1-99:1, and the molar ratio of samarium to tungsten is greater than 19:1.

[0053] In the following examples,

[0054] PEG-600 is polyethylene glycol with an average molecular weight of 600;

[0055] Pluronic F127 is a polyoxyethylene polyoxypropylene ether block copolymer with the trade name Pluronic.

[0056] Example 1 Sm 0.99 W 0.01 Preparation of Mn2O5

[0057] Limit the preparation method of the above wide-temperature SCR denitration catalyst, and the specific steps of the method are as follows:

[0058] 1) Stir PEG-600 and Pluronic F127 at 60°C to dissolve them in deionized water, with concentrations of 45 wt.% and 18 wt.% respectively, to obtain solution A;

[0059] 2) Dissolve manganese nitrate, samarium nitrate and ammonium metatungstate in solution A, where the molar ratio of samarium nitrate to ammonium metatungstate is 99:1, and the molar ratio of the sum of samarium nitrate and ammonium metatungstate to manganese nitrate is 1:2, to obtain solution B;

[0060] 3) Slowly add a 25 wt.% tetramethylammonium hydroxide solution drop by drop into solution B and stir continuously until the pH of the solution is 10. Then add a 30 vol.% H₂O₂ solution and continue stirring for 2 hours, where the molar ratio of manganese nitrate to hydrogen peroxide is 1:1.3, to obtain precipitate C;

[0061] 4) After suction filtration, place precipitate C in an oven at 80 °C and dry for 12 hours to obtain a dry solid;

[0062] 5) Place the solid in a muffle furnace, calcine at 500 °C for 8 hours, and then calcine at 800 °C for 8 hours. After that, grind the catalyst into a powder with a particle size of 100 mesh, where the heating rate is 8 °C / min for both, to obtain the SCR denitration catalyst Sm 0.99 W 0.01 Mn₂O₅.

[0063] Example 2 Sm 0.98 W 0.02 Preparation of Mn₂O₅

[0064] Limit the preparation method of the above wide-temperature SCR denitration catalyst. The specific steps of this method are as follows:

[0065] 1) Stir PEG-600 and Pluronic F127 at 60 °C until they are dissolved in deionized water, with concentrations of 45 wt.% and 18 wt.% respectively, to obtain solution A;

[0066] 2) Dissolve manganese nitrate, samarium nitrate, and ammonium metatungstate in solution A, where the molar ratio of samarium nitrate to ammonium metatungstate is 49:1, and the sum of samarium nitrate and ammonium metatungstate and manganese nitrate is 1:2, to obtain solution B;

[0067] 3) Slowly add a 25 vol.% tetramethylammonium hydroxide solution drop by drop into solution B and stir continuously until the pH of the solution is 10. Then add a 30 vol.% H₂O₂ solution and continue stirring for 2 hours, where the molar ratio of manganese nitrate to hydrogen peroxide is 1:1.3, to obtain precipitate C;

[0068] 4) After suction filtration, place precipitate C in an oven at 80 °C and dry for 12 hours to obtain a dry solid;

[0069] 5) Place the solid in a muffle furnace, calcine at 500 °C for 8 hours, and then calcine at 800 °C for 8 hours. After that, grind the catalyst into a powder with a particle size of 100 mesh, where the heating rate is 8 °C / min for both, to obtain the SCR denitration catalyst Sm 0.98 W 0.02 Mn₂O₅.

[0070] Example 3 Sm0.95 W 0.05 Preparation of Mn2O5

[0071] The preparation method of the above-mentioned wide-temperature SCR denitration catalyst is limited, and the specific steps of this method are as follows:

[0072] 1) Stir PEG-600 and Pluronic F127 at 60 °C to dissolve them in deionized water, with concentrations of 45 wt.% and 18 wt.% respectively, to obtain solution A;

[0073] 2) Dissolve manganese nitrate, samarium nitrate and ammonium metatungstate in solution A, where the molar ratio of samarium nitrate to ammonium metatungstate is 19:1, and the sum of samarium nitrate and ammonium metatungstate and manganese nitrate is 1:2 in molar ratio, to obtain solution B;

[0074] 3) Dropwise add 25 wt.% tetramethylammonium hydroxide solution to solution B and stir continuously until the solution pH = 10.4, then add 30 vol.% H2O2 solution and continue stirring for 2 hours, where the molar ratio of manganese nitrate to hydrogen peroxide is 1:1, to obtain precipitate C;

[0075] 4) After suction filtration, put precipitate C into an oven at 80 °C and dry for 12 hours to obtain a dry solid;

[0076] 5) Put the solid into a muffle furnace, calcine at 500 °C for 8 hours, and then calcine at 800 °C for 8 hours, and then grind the catalyst into powder with a particle size of 100 mesh, where the heating rate is 8 °C / min, to obtain the SCR denitration catalyst Sm 0.95 W 0.05 Mn2O5.

[0077] Preparation of Comparative Example 1 SmMn2O5

[0078] To verify the effect difference between this wide-temperature SCR denitration catalyst and undoped mullite-type SmMn2O5, in this test example, a NO oxidation catalyst mullite-type SmMn2O5 was prepared under the same conditions as in the previous test (same as Example 1), and the specific method is as follows:

[0079] 1) Stir PEG-600 and Pluronic F127 at 60 °C to dissolve them in deionized water, with concentrations of 45 wt.% and 18 wt.% respectively, to obtain solution A;

[0080] 2) Dissolve manganese nitrate and samarium nitrate in solution A, where the molar ratio of samarium nitrate to manganese nitrate is 1:2, to obtain solution B;

[0081] 3) Add 45 wt.% tetramethylammonium hydroxide solution dropwise to solution B with continuous stirring until the pH of the solution reaches 10, then add 30 vol.% H2O2 solution and continue stirring for 2 hours, where the molar ratio of manganese nitrate to hydrogen peroxide is 1:1.3, to obtain precipitate C;

[0082] 4) After suction filtration, place precipitate C in an oven at 80 °C and dry for 12 hours to obtain a dry solid;

[0083] 5) Place the solid in a muffle furnace, calcine at 500 °C for 8 hours, and then calcine at 800 °C for 8 hours. After that, grind the catalyst into a powder with a particle size of 100 mesh, where the heating rate is 8 °C / min, to obtain manganese-based mullite SmMn2O5.

[0084] Comparative Example 2 Sm 0.99 W 0.01 Preparation of Mn2O5

[0085] It is the same as the preparation method of the wide-temperature SCR denitration catalyst described in Example 1, with the difference only in step 3):

[0086] Add 25 wt.% tetramethylammonium hydroxide solution dropwise to solution B with continuous stirring until the pH of the solution reaches 9, then add 30 vol.% H2O2 solution and continue stirring for 2 hours, where the molar ratio of manganese nitrate to hydrogen peroxide is 1:1, to obtain precipitate C.

[0087] This comparative example uses different pH and molar ratios of manganese nitrate to hydrogen peroxide from Example 1.

[0088] Verification of catalyst activity in application examples

[0089] To evaluate the catalyst performance, 0.1 g of the catalyst particles prepared in Examples 1-3 and Comparative Examples 1-2 were respectively placed in an SCR catalyst activity evaluation platform, and the activity evaluation was carried out in a fixed-bed quartz tube reactor with an inner diameter of 5 mm.

[0090] NO / N2, NH3 / N2, N2, and O2 were mixed after being controlled by mass flow meters to obtain simulated flue gas with a composition of 350 ppm NO, 350 ppm NH3, and 5% O2, with N2 as the balance gas, a gas flow rate of 200 ml / min, and reaction temperatures of 100, 125, 150, 175, 200, 225, 250, 300, 350, 400 °C. The experimental results are as Figures 1 to 10 shown.

[0091] According to Figure 1 and Figure 2 , SCR denitration catalysis Sm 0.99 W 0.01The efficient catalytic working range (100% NO conversion) of the Mn2O5 sample is 200 - 350 °C.

[0092] According to Figure 3 and Figure 4 , for the SCR denitration catalyst Sm 0.98 W 0.02 The efficient catalytic working range (100% NO conversion) of the Mn2O5 sample is 225 - 350 °C.

[0093] According to Figure 5 and Figure 6 , for the SCR denitration catalyst Sm 0.95 W 0.05 The efficient catalytic working range (100% NO conversion) of the Mn2O5 sample is 250 - 350 °C.

[0094] According to Figure 7 and Figure 8 , for the mullite - type SmMn2O5 sample, the NO conversion rate is above 80% between 125 - 300 °C. Especially in the low - temperature range of 100 - 200 °C, the NO conversion rate is much higher than that of the sample doped with tungsten. However, in the high - temperature range of 300 - 400 °C, the NO conversion rate decreases rapidly. Due to its strong oxidizing property, a large amount of by - products N2O and NO2 are generated, so it is not a good SCR denitration catalyst.

[0095] According to Figure 9 and Figure 10 , for the SCR denitration catalyst Sm 0.99 W 0.01 The efficient catalytic working range (100% NO conversion) of the Mn2O5 sample is 300 - 350 °C.

[0096] The electron micrographs of the SCR denitration catalysts prepared in Examples 1 - 3 and Comparative Examples 1 - 2 are shown in Figures 11 - 15 , and the specific surface areas are shown in Figure 16 , from Figures 11 - 16 the microscopic morphologies and specific surface areas of each SCR denitration catalyst, it can be seen that for this series of catalysts, as the tungsten content increases, the particle size of the catalyst samples gradually increases, the particle size is no longer uniform, the specific surface area decreases, and the specific surface area of the Sm 0.99 W 0.01 Mn2O5 sample and the Sm 0.98 W 0.02 Mn2O5 sample is better than that of the SmMn2O5 sample.

[0097] According to the above test results, it can be known that after the NO oxidation catalyst (mullite - type SmMn2O5) is doped and modified with tungsten element, the SCR denitration activity is improved and the efficient working temperature window is broadened. Among them, in Example 1, 1% of tungsten is doped to replace samarium, and Sm0.99 W 0.01 SmMn₂O₅ catalyst sample; in Example 2, 2% of tungsten was doped instead of samarium to prepare Sm 0.98 W 0.02 SmMn₂O₅ catalyst sample; in Example 3, 5% of tungsten was doped instead of samarium to prepare Sm 0.95 W 0.05 SmMn₂O₅ catalyst sample; in Comparative Example 1, a mullite-type SmMn₂O₅ catalyst sample was prepared using the parameters of Example 1, and in Comparative Example 2, Sm 0.99 W 0.01 SmMn₂O₅ catalyst sample was prepared.

[0098] The differences between Example 1 and Comparative Examples 1-2: In Example 1, Sm 0.99 W 0.01 SmMn₂O₅ was doped with 1% of tungsten instead of samarium. In Comparative Example 1, SmMn₂O₅ does not contain tungsten, and in Comparative Example 2, it is also Sm 0.99 W 0.01 SmMn₂O₅, but the process parameters are different from those of Comparative Example 1 (pH value during precipitation, molar ratio of manganese nitrate to hydrogen peroxide).

[0099] In Examples 1-3 and Comparative Example 1, catalysts with different doping contents of tungsten were investigated (tungsten replaced 0% to 5% of the samarium content). According to the comparative analysis of each example, the higher the doping amount of tungsten, the narrower the high-efficiency working window of the catalyst. Therefore, the doping amount of tungsten is an important factor affecting the activity of the catalyst.

[0100] According to the comparison of the activities of the catalysts prepared in Example 1 and Comparative Example 2, different preparation parameters were used during the preparation process: acidity and alkalinity, molar ratio of manganese nitrate to hydrogen peroxide. Within the preferred range, the higher the pH and the molar ratio of manganese nitrate to hydrogen peroxide, the stronger the activity of the catalyst within the test range. Acidity and alkalinity and the molar ratio of manganese nitrate to hydrogen peroxide are important influencing factors during the catalyst preparation process.

[0101] The preparation method for modifying the acidic sites of the NO oxidation catalyst of the wide-temperature SCR denitration catalyst according to the present invention. The optimal doping conditions are as follows: Stir the surfactants PEG-600 and Pluronic F127 at 60 °C to dissolve them in deionized water, with concentrations of 45 wt.% and 18 wt.% respectively; dissolve manganese nitrate and samarium nitrate in the solution containing surfactants, where the molar ratio of samarium nitrate to ammonium metatungstate is 99:1, and the molar ratio of samarium nitrate and ammonium metatungstate to manganese nitrate is 1:2; gradually add 25 wt.% tetramethylammonium hydroxide solution to adjust the solution pH to 10, then add 30 vol.% H2O2 solution and stir for 2 hours, where the molar ratio of manganese nitrate to hydrogen peroxide is 1:1.3, to obtain a precipitate; after suction filtration, place the precipitate in an oven at 80 °C and dry for 12 hours to obtain a dry solid; place the solid in a muffle furnace, calcine at 500 °C for 8 hours, and then calcine at 800 °C for 8 hours, and then grind the catalyst into a powder with a particle size of 100 mesh, where the heating rate is 8 °C / min, to obtain the wide-temperature SCR denitration catalyst Sm 0.99 W 0.01 Mn2O5.

[0102] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and reference can be made to the description in the method part for related parts.

[0103] The above has introduced the wide-temperature SCR denitration catalyst provided by the present invention in detail. Specific examples are used herein to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A wide-temperature SCR denitration catalyst, characterized in that: The catalyst is prepared by doping tungsten element on the basis of a NO oxidation catalyst using the co-precipitation method. The NO oxidation catalyst is mullite-type SmMn2O5. The chemical formula of this catalyst is Sm x W y Mn2O 5， where x and y are the mole fractions of Sm and W elements respectively, and the values of x and y satisfy the following conditions: x is 0.95 - 0.99, y is 0.01 - 0.05, and x + y = 1; The wide-temperature SCR denitration catalyst is prepared by the following method: S1. At a temperature of 30 - 60 °C, dissolve the surfactant in water to obtain solution A; The surfactant is a mixture of PEG-600 and Pluronic F127, and their concentrations are 40 - 60 wt.% and 5 - 20 wt.% respectively; S2. Dissolve the precursors manganese nitrate, samarium nitrate and ammonium metatungstate in solution A to obtain solution B; S3. Dropwise add the precipitant to solution B and stir to adjust the pH value of the solution to 10, then add the H2O2 solution and continue stirring to obtain precipitate C; S4. After filtering the precipitate C by suction, dry, calcine and grind it to obtain the wide-temperature SCR denitration catalyst.

2. The wide-temperature SCR denitration catalyst according to claim 1, characterized in that: The chemical formula of this catalyst is Sm 0.99 W 0.01 Mn2O5.

3. A preparation method of the wide-temperature SCR denitration catalyst according to claim 1, characterized in that The method includes the following steps: S1. At a temperature of 30 - 60 °C, dissolve the surfactant in water to obtain solution A; The surfactant is a mixture of PEG-600 and Pluronic F127, and their concentrations are 40 - 60 wt.% and 5 - 20 wt.% respectively; S2. Dissolve the precursors manganese nitrate, samarium nitrate and ammonium metatungstate in solution A to obtain solution B; S3. Dropwise add the precipitant to solution B and stir to adjust the pH value of the solution to 10, then add the H2O2 solution and continue stirring to obtain precipitate C; S4. After filtering the precipitate C by suction, dry, calcine and grind it to obtain the wide-temperature SCR denitration catalyst.

4. The preparation method according to claim 3, characterized in that: The precipitant in S3 is 15 - 45 wt.% of tetramethylammonium hydroxide or ammonia water.

5. The preparation method according to claim 3, characterized in that: In S3, the mass concentration of the H2O2 solution is 15 - 45%, control the molar ratio of manganese nitrate to H2O2 to be 1:1 - 1:1.5, and the stirring time is 2 - 5 hours.

6. The preparation method according to claim 3, characterized in that: In S3, the molar ratio of manganese nitrate to H2O2 is 1:1.

3.

7. The preparation method according to claim 3, characterized in that: In S4, the drying temperature is 60 - 110 °C, and the time is 8 - 14 hours; the calcination is divided into two stages. The first-stage temperature is 400 - 600 °C, and the calcination time is 6 - 8 hours. The second-stage temperature is 800 - 900 °C, and the calcination time is 6 - 8 hours. The heating rate is 6 - 10 °C / minute; grind it into particles of 60 - 120 mesh.

8. The preparation method according to claim 3, characterized in that: The grinding in S4 makes the particle size of the obtained catalyst powder be 60 - 120 mesh.

9. An application of the wide-temperature SCR denitration catalyst according to claim 1 in flue gas denitration, characterized in that: The wide temperature is in the range of 150 - 350 °C.

Images