Three-dimensional ordered macroporous manganese-based catalyst as well as preparation method and application thereof

Abstract

The invention discloses a three-dimensional ordered macroporous manganese-based catalyst as well as a preparation method and application thereof, and a material with a three-dimensional ordered macroporous structure (3DOM) is prepared by taking polymethyl methacrylate as a template and manganese and other metal composite oxides as a main body. Compared with the traditional catalyst, the pore channels of the three-dimensional ordered macroporous structure are three-dimensionally penetrated and crosslinked, the arrangement is regular and ordered, the pore diameter is uniform, and the specific surface area of the catalyst can be obviously increased. The structure provides a good gas diffusion channel for a gas-solid two-phase catalytic reaction process, mutual contact between the catalyst and gas-phase molecules is greatly improved, the reaction contact time is prolonged, the activity of the catalyst is further improved, and the catalyst shows the capability of cooperatively removing NOx and CO when being used for coupling NH3-SCR / CO catalytic oxidation reaction.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation and environmental catalysis technology, specifically relating to a three-dimensional ordered macroporous manganese-based catalyst, its preparation method, and its application. Background Technology

[0002] Iron and steel sintering and coking enterprises are important industries driving industrialization. During the production process, the sintering flue gas produced contains large amounts of nitrogen oxides (NOx). x NO and carbon monoxide (CO). x It can lead to photochemical pollution, acid rain, near-surface ozone, and PM2.5 deposition. CO can also cause acid rain and the greenhouse effect, and it can bind to hemoglobin in the human body, thus causing great damage to the ecological environment and human health.

[0003] Selective catalytic reduction of CO (CO-SCR) is considered a method for controlling NO. x CO-SCR is an ideal method for CO removal, but sintering flue gas contains a large amount of oxygen. Under oxygen-rich conditions, CO is preferentially oxidized to CO2 by O2 and does not participate in the CO-SCR reaction, which greatly limits the CO-SCR technology.

[0004] Based on the low-temperature efficiency of NH3 selective catalytic reduction (NH3-SCR) and the ease with which CO is oxidized to CO2 under oxygen-rich conditions, releasing heat during the oxidation process and increasing flue gas temperature to promote the reaction, an NH3-SCR coupled CO catalytic oxidation technology was proposed. Currently, to achieve the combined use of CO oxidation and SCR denitrification technologies, CO oxidation catalysts and SCR catalysts are typically developed independently and arranged in series, which increases equipment complexity and modification difficulty. Therefore, if a single catalyst could be used to simultaneously achieve NH3-SCR coupled CO catalytic oxidation, economic losses could be reduced, implementation complexity lowered, and NO reduction achieved. x Synergistic removal of CO, resulting in efficient treatment.

[0005] The core of NH3-SCR coupled CO catalytic oxidation technology lies in the development of highly efficient catalysts. Mn-based catalysts possess diverse chemical valence states (Mn... 2+ Mn 3+ Mn 4+) and excellent oxygen storage / release capacity, active lattice oxygen mobility and abundant surface acidity, it is widely used in low-temperature SCR denitrification and CO catalytic oxidation. However, the pore structure of the traditional catalyst is random and disordered, the pore size difference is obvious, the active sites are not fully utilized and are easy to capture reaction intermediates (such as soot and sulfur oxides), forming carbon deposition or chemisorption poisoning, which makes the low-temperature catalytic activity insufficient, resulting in insufficient reaction and delayed reaction start. The three-dimensional ordered macroporous (3DOM) catalyst has a periodic arrangement of pore channels and a uniform pore size, forming a three-dimensional ordered through structure, which enables the reactant molecules to quickly diffuse and reach the active sites, accelerating the reaction. In addition, the adjustable multi-level pore system can improve the mass transfer efficiency, inhibit excessive reaction and reduce the generation of by-products. The high specific surface area of 3DOM provides sufficient loading space for active sites and has strong thermal stability, which enhances the redox capacity and improves the catalytic activity at low temperature.

[0006] However, the three-dimensional ordered macroporous catalysts currently have the technical defects of complex preparation process, high cost, insufficient mechanical strength, easy collapse or breakage of the pore structure and short service life. The present application reduces the consumption of materials and shortens the process by preparing a PMMA template and vacuum impregnating an ethanol solution as a solvent, and a catalyst with a stable three-dimensional ordered macroporous structure is prepared, solving the existing defects. SUMMARY

[0007] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification of the present application to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0008] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0009] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art and provide a preparation method of a three-dimensional ordered macroporous manganese-based catalyst.

[0010] To solve the above technical problems, the present application provides the following technical solutions: comprising,

[0011] Methyl methacrylate is mixed with deionized water and heated and stirred in a water bath, preheated potassium persulfate initiator solution is added thereto and continued to be stirred to obtain a monodisperse polymethyl methacrylate microsphere emulsion;

[0012] The monodisperse polymethyl methacrylate microsphere emulsion is centrifuged to obtain a milky white solid, which is dried to obtain a polymethyl methacrylate template;

[0013] Ce(NO3)3·6H2O, Mn(NO3)2 and citric acid are dissolved in ethanol to obtain a manganese-based precursor solution;

[0014] The poly(methyl methacrylate) template is added to the manganese-based precursor solution, vacuum impregnation is carried out, and then solid-liquid separation is carried out by vacuum filtration to obtain a solid Mn-M@PMMA precursor material, which is dried, calcined, and then cooled to room temperature to obtain the three-dimensionally ordered macroporous manganese-based catalyst.

[0015] As a preferred scheme of the preparation method of the three-dimensionally ordered macroporous manganese-based catalyst, the volume ratio of methyl methacrylate, deionized water and potassium persulfate solution is 1:11-12:(0.3-0.5).

[0016] As a preferred scheme of the preparation method of the three-dimensionally ordered macroporous manganese-based catalyst, the temperature of the water bath heating and stirring is 50-80°C, the stirring speed is 200-400 rpm, and the stirring time is 30-60 min.

[0017] As a preferred scheme of the preparation method of the three-dimensionally ordered macroporous manganese-based catalyst, the centrifugation speed of the monodisperse poly(methyl methacrylate) microsphere emulsion is 1000-4000 rpm, the centrifugation time is 20-60 min, the drying temperature of the milky white solid obtained by centrifugation is 50-100°C, and the drying time is 10-15 h.

[0018] As a preferred scheme of the preparation method of the three-dimensionally ordered macroporous manganese-based catalyst, the sum of the amounts of substance of Ce(NO3)3·6H2O and Mn(NO3)2 is 0.01-0.03 mol, and the amount-of-substance ratio is 3:1-1:3.

[0019] As a preferred scheme of the preparation method of the three-dimensionally ordered macroporous manganese-based catalyst, in the precursor solution, the total metal salt ion concentration of Mn and Ce is 1-2 mol / L, and the molar ratio of citric acid to metal salt ions is 1:1.

[0020] As a preferred scheme of the preparation method of the three-dimensionally ordered macroporous manganese-based catalyst, the vacuum impregnation time is 4-9 h.

[0021] As a preferred scheme of the preparation method of the three-dimensionally ordered macroporous manganese-based catalyst, the drying time of the solid Mn-M@PMMA precursor material is 8-12 h, the temperature is 40-60°C, and the calcination is carried out at a temperature rising rate of 1-5°C from room temperature to 400-600°C and then maintained for 2-5.

[0022] Another object of the present application is to provide a three-dimensional ordered macroporous manganese-based catalyst, the main body of which is composed of manganese oxide and cerium oxide, the mass ratio of Mn / Ce is 3:1-1:3, the three-dimensional macroporous structure channels are cross-linked and arranged in order, and the pore size is uniform.

[0023] Another object of the present application is to provide an application of the three-dimensional ordered macroporous manganese-based catalyst, which is used for NH3-SCR coupled CO catalytic oxidation reaction.

[0024] The present application has the following advantages:

[0025] (1) The present application uses polymethyl methacrylate as a template, and manganese and other metal composite oxides as the main body to prepare a three-dimensional ordered macroporous structure (3DOM) material. Compared with traditional catalysts, the three-dimensional ordered macroporous structure channels are cross-linked in three dimensions and arranged in order, the pore size is uniform, and the specific surface area of the catalyst can be significantly increased. This structure provides a good gas diffusion channel for the gas-solid two-phase catalytic reaction process, greatly improves the mutual contact between the catalyst and the gas molecules, increases the reaction contact time, and further improves the activity of the catalyst.

[0026] (2) The catalyst preparation method of the present application is simple, the raw materials are easy to obtain, the price is low, the catalytic performance is excellent, the stability and water resistance are good, and it is suitable for industrial application of low-temperature NH3-SCR coupled CO catalytic oxidation. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0028] Figure 1 The SEM images of the catalysts prepared in Example 1 and Comparative Examples 1-3.

[0029] Figure 2 The stability test results of the catalyst prepared in Example 1.

[0030] Figure 3 The water resistance test results of the catalyst prepared in Example 1.

[0031] Figure 4 The NOx conversion rate and CO conversion rate graph of the manganese-based catalyst prepared in Example 1 and Comparative Examples 1-3 for NH3-SCR and CO catalytic oxidation reaction.

[0032] Figure 5The manganese-based catalyst prepared in Example 1 of the present application, Comparative Examples 1-3 was coupled to perform NH3-SCR / CO catalytic oxidation reaction of NO x Conversion rate vs. CO conversion rate graph.

[0033] Figure 6 The manganese-based catalyst prepared in Example 1-5 of the present application was coupled to perform NH3-SCR / CO catalytic oxidation reaction of NO x Conversion rate vs. CO conversion rate graph.

[0034] Figure 7 The manganese-based catalyst prepared in Example 1 of the present application and Comparative Examples 4, 5 was coupled to perform NH3-SCR / CO catalytic oxidation reaction of NO x Conversion rate vs. CO conversion rate graph.

[0035] Figure 8 The catalyst prepared in Example 1 of the present application and Comparative Example 6 was coupled to perform NH3-SCR / CO catalytic oxidation reaction of NO x Conversion rate vs. CO conversion rate graph. DETAILED DESCRIPTION

[0036] In order to make the above objectives, features and advantages of the present application more apparent and comprehensible, the specific embodiments of the present application will be described in detail below with reference to the description and examples.

[0037] In the following description, a lot of specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can be practiced in other different manners from those described herein, and those skilled in the art can make similar generalization without departing from the connotation of the present application, therefore, the present application is not limited by the specific embodiments disclosed below.

[0038] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. The "in one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is the embodiment alone or alternatively mutually exclusive with other embodiments.

[0039] The raw materials used in the present application are all commercially available in the art without special instructions.

[0040] In the present application, the NO x The calculation formulae of the conversion rate and CO conversion rate are as follows:

[0041] The NO x Conversion rate = [NO x ] in - [NO x ] out / [NO x ] in× 100%

[0042] CO x Conversion = [CO] in - [CO] out / [CO] in × 100%

[0043] wherein [NO x ] in is the inlet concentration of nitrogen oxides, ppm; [NO x ] out is the outlet concentration of nitrogen oxides, ppm; [CO] in is the inlet concentration of CO, ppm, [CO] out is the outlet concentration of CO, ppm.

[0044] Example 1

[0045] The present embodiment provides a preparation method of a three-dimensional ordered macroporous manganese-based catalyst, in particular:

[0046] 1) Preparation of polymethyl methacrylate template:

[0047] 55 mL of methyl methacrylate and 650 mL of deionized water were mixed into a three-necked flask, heated to 70°C in a water bath, and the whole process was carried out under stirring at a speed of 350 rpm / min, then a preheated potassium persulfate initiator solution (0.20 g dissolved in 20 ml of deionized water) was added, and the stirring was continued for 40 min to obtain a monodisperse polymethyl methacrylate microsphere emulsion;

[0048] The monodisperse polymethyl methacrylate microsphere emulsion was placed in a centrifuge tube and centrifuged at a speed of 4000 r / min for 20 min, and a milky white solid was obtained by centrifugation, which was dried to obtain a polymethyl methacrylate (PMMA) template;

[0049] 2) Preparation of manganese-based catalyst:

[0050] 10 mmol of 50% mass fraction of Ce(NO3)3·6H2O, 10 mmol of 50% mass fraction of Mn(NO3)2 aqueous solution and 20 mmol (3.842 g) of citric acid were dissolved in 10 mL of ethanol solution, the molar ratio of citric acid to total metal salt ions was 1:1, a manganese-based precursor solution was obtained, the concentration of metal salt ions in the solution was 2 mol / L, the mass ratio of Ce(NO3)3·6H2O and Mn(NO3)2 was 1:1, and the total amount of substance was 0.02 mol;

[0051] 2g PMMA template was added into the manganese-based precursor solution and vacuum impregnated for 6h. After impregnation, solid-liquid separation was carried out by vacuum suction filtration. The collected solid was dried at 60℃ for 12 hours and then placed in a muffle furnace for programmed temperature rising at a rate of 1℃ / min. The temperature was raised to 450℃ under air atmosphere and maintained for 5h. After cooling to room temperature, the three-dimensionally ordered macroporous manganese-based catalyst of the present example was obtained.

[0052] Comparative Example 1

[0053] The present comparative example differs from Example 1 in that Ce(NO3)3·6H2O in step 2) was adjusted to Cu(NO3)2·3H2O. The remaining steps were carried out according to Example 1 to obtain the catalyst of the present comparative example.

[0054] Comparative Example 2

[0055] The present comparative example differs from Example 1 in that Ce(NO3)3·6H2O in step 2) was adjusted to Co(NO3)2·6H2O. The remaining steps were carried out according to Example 1 to obtain the catalyst of the present comparative example.

[0056] Comparative Example 3

[0057] The present comparative example differs from Example 1 in that Ce(NO3)3·6H2O in step 2) was adjusted to Fe(NO3)2·6H2O. The remaining steps were carried out according to Example 1 to obtain the catalyst of the present comparative example.

[0058] Figure 1 (a~d) are SEM images of the catalysts prepared in Example 1 and Comparative Examples 1~3, respectively. It can be seen that the catalyst prepared under the conditions of Example 1 has a typical three-dimensionally ordered pore structure.

[0059] Figure 2 The stability test results of the catalyst prepared in Example 1 (the reaction conditions for the test were: 500ppm NO + 500ppm NH3+ 4000ppm CO + 10vol% oxygen + nitrogen (balancing gas), total gas flow rate was 200mL / min, space velocity was 60000mL / h, and reaction temperature was 250℃) are shown in the following table. It can be seen that the conversion of NO was stabilized at about 95% and the conversion of CO was stabilized at about 70% in the 6h continuous reaction. This proves that the catalyst has excellent stability. x

[0060] Figure 3 ​The results of the water resistance test of the catalyst prepared in Example 1 (the reaction conditions tested are: 500 ppm NO + 500 ppm NH3+ 4000 ppm CO + 10 vol% oxygen + nitrogen (balance gas), the total flow rate of the gas is 200 mL / min, the space velocity is 60000 mL / h, the reaction temperature is 250°C, and the water vapor concentration is 5 vol%) show that, in the 4 hours of continuous reaction, when no water vapor is introduced in the first 2 hours, the NO x conversion rate is stable at 95%, and the CO conversion rate is stable at 70%. When about 5 vol% of water vapor is introduced, the NO x conversion rate decreases by 5% and is maintained at about 90%, and the CO conversion rate decreases by 20% and is maintained at about 50%. In addition, after the water vapor is removed, the NO x conversion rate returns to the initial level, indicating that the catalyst prepared in Example 1 has good water resistance.

[0061] Catalyst activity evaluation

[0062] The catalyst prepared above is pressed, crushed and sieved according to the present scheme, and the particle size of the catalyst is controlled to be 40-60 mesh. 0.2 mL of the catalyst is weighed and placed in a quartz tube (inner diameter 8 mm), and quartz wool is filled at both ends of the quartz tube to fix the catalyst and ensure the passage of the reaction gas. The reaction gas is 500 ppm ammonia + 5 vol% oxygen + 500 ppm nitrogen monoxide + 4000 ppm carbon monoxide + nitrogen (balance gas), and the total flow rate of the reaction gas is controlled to be 200 mL / min, corresponding to a space velocity (GHSV) of 60000 mL / h. The reaction process adopts programmed temperature rising, and the reaction temperature range is controlled to be 150-400°C. A flue gas analyzer is used to test the concentrations of the reactants and products. The catalytic activity is evaluated by the NO x conversion rate and the CO conversion rate.

[0063] The product catalyst performance of Example 1 and Comparative Examples 1-3 is tested according to the above catalyst activity evaluation method, and the results are shown in Tables 1-4 and Figures 4-5 .

[0064] Table 1 Comparison results of catalytic activity test of NH3-SCR reaction alone

[0065]

[0066]

[0067] Figure 4 The left is the NOx conversion rate graph of the manganese-based catalyst prepared in Example 1 and Comparative Examples 1-3 in the NH3-SCR catalytic oxidation reaction alone, according to Table 1 and Figure 4 It can be seen from the left that the catalyst prepared by doping different elements has good catalytic activity in the removal of NOx The performance is significantly affected; the catalyst prepared in Example 1 of this invention has a high NO content. x The catalysts prepared under the conditions of Comparative Examples 2 and 3 all achieved high conversion rates and a wide temperature window, and both catalysts could achieve NO conversion within the temperature range of 150–250 °C. x The high degree of transformation.

[0068] Table 2 Comparison of catalytic activity tests for CO oxidation alone

[0069] CO conversion 150℃ 175℃ 200℃ 225℃ 250℃ 275℃ 300℃ 350℃ 400℃ Example 1 28.75 50.95 61.60 75.10 85.45 90.55 93.55 96.40 98.05 Comparative Example 1 24.70 43.00 54.40 58.00 64.00 73.00 80.50 88.00 94.00 Comparative Example 2 10.00 15.55 28.75 39.25 45.70 51.85 60.70 73.00 81.25 Comparative Example 3 14.35 10.00 18.40 29.50 44.65 55.00 62.50 74.50 83.80

[0070] Figure 4 (Right) is a graph showing the CO conversion rate of the manganese-based catalysts prepared in Example 1 and Comparative Examples 1-3 of the present invention, when used alone for the catalytic oxidation of CO, according to Table 2 and... Figure 4 (Right) It can be seen that the preparation of catalysts by doping with different elements has a different effect on the individual removal of NO. x The performance was affected. The catalysts prepared under the conditions of Comparative Example 2 and Comparative Example 3 showed poor CO catalytic oxidation performance, while the catalyst prepared under the conditions of Example 1 showed the best CO catalytic oxidation performance, achieving a CO conversion rate of over 85% in the temperature range of 250–400 °C.

[0071] Table 3. Comparison of NH3-SCR catalytic activity test results for coupled NH3-SCR / CO catalytic oxidation reaction.

[0072]

[0073]

[0074] Table 4. Comparison of CO catalytic activity in the coupled NH3-SCR / CO catalytic oxidation reaction.

[0075] CO conversion 150℃ 175℃ 200℃ 225℃ 250℃ 275℃ 300℃ 350℃ 400℃ Example 1 25.00 40.6 49.00 57.55 69.25 80.05 85.30 95.05 99.25 Comparative Example 1 37.00 46.00 55.00 65.50 75.25 83.35 91.90 98.05 98.80 Comparative Example 2 1.00 1.00 10.00 17.50 26.95 44.05 58.75 86.50 91.60 Comparative Example 3 0.10 4.00 7.15 15.25 26.05 35.65 53.50 70.60 79.90

[0076] Figure 5 As Example 1 of this invention, manganese-based catalysts prepared in Comparative Examples 1-3 are used in the coupled NH3-SCR / CO catalytic oxidation reaction to produce NO. x Conversion rate vs. CO conversion rate graph, based on Tables 3 and 4. Figure 5 It can be seen that doping with different elements affects the NH3-SCR coupled CO catalytic oxidation performance of the catalyst. After introducing CO, compared with the SCR reaction alone, all samples showed improved NO oxidation performance at low temperatures. xThe conversion rates are all reduced. The catalyst prepared under the preparation condition of Example 1 exhibits the strongest NOx removal performance under the NH3-SCR coupled CO catalytic oxidation atmosphere, and achieves more than 80% of NOx conversion rate at 150-300°C. After the introduction of NO and NH3, the CO conversion rates of the catalysts prepared under various preparation conditions all decrease in the whole temperature range. The catalysts prepared under the preparation conditions of Comparative Example 2 and Comparative Example 3 exhibit poor low-temperature CO catalytic oxidation performance, and cannot achieve 60% of CO conversion rate below 300°C. The catalysts prepared under the preparation conditions of Example 1 and Comparative Example 1 exhibit relatively strong CO catalytic oxidation performance, and achieve more than 80% of CO conversion rate after 275°C. However, the catalyst prepared under the preparation condition of Comparative Example exhibits poor low-temperature NOx removal performance. In comprehensive comparison, the catalyst prepared under the preparation condition of Example 1 exhibits the strongest ability of synergistically removing NO x and CO, simultaneously achieves more than 70% of CO conversion rate and NOx conversion rate in the temperature range of 250-300°C, and is more suitable for practical application scenarios at low and medium temperatures.

[0077] Example 2

[0078] The difference between this example and Example 1 is that the molar ratio of Ce(NO3)3·6H2O to Mn(NO3)2 in the preparation of the manganese-based catalyst in step 2) is adjusted to 1:2, and the sum of the amounts of substance is kept at 0.02 mol. The remaining step processes all refer to Example 1, that is, the three-dimensionally ordered macroporous manganese-based catalyst of this example is obtained.

[0079] Example 3

[0080] The difference between this example and Example 1 is that the molar ratio of Ce(NO3)3·6H2O to Mn(NO3)2 in the preparation of the manganese-based catalyst in step 2) is adjusted to 1:3, and the sum of the amounts of substance is kept at 0.02 mol. The remaining step processes all refer to Example 1, that is, the three-dimensionally ordered macroporous manganese-based catalyst of this example is obtained.

[0081] Example 4

[0082] The difference between this example and Example 1 is that the molar ratio of Ce(NO3)3·6H2O to Mn(NO3)2 in the preparation of the manganese-based catalyst in step 2) is adjusted to 2:1, and the sum of the amounts of substance is kept at 0.02 mol. The remaining step processes all refer to Example 1, that is, the three-dimensionally ordered macroporous manganese-based catalyst of this example is obtained.

[0083] Example 5

[0084] The difference between the present example and Example 1 is that the molar ratio of Ce(NO3)3.6H2O and Mn(NO3)2 in the preparation of the manganese-based catalyst in step 2) is adjusted to 3:1, and the sum of the molar amounts is kept at 0.02 mol, and the remaining steps are all referred to Example 1, i.e. the three-dimensionally ordered macroporous manganese-based catalyst of the present example is obtained.

[0085] The product catalysts of Examples 2-5 are tested for performance by referring to the catalyst activity evaluation method described above, and compared with Example 1, and the results are shown in Tables 5-6 and Figure 6

[0086] Table 5 Comparison results of NH3-SCR catalytic activity test for NH3-SCR / CO catalytic oxidation reaction coupling

[0087] NOx conversion 150℃ 175℃ 200℃ 225℃ 250℃ 275℃ 300℃ 350℃ 400℃ Example 1 83.20 88.00 90.40 94.00 95.20 92.80 83.20 49.60 28.00 Example 2 56.20 65.08 66.28 67.48 64.60 71.56 54.76 31.96 6.76 Example 3 29.20 57.64 69.04 79.84 80.80 69.28 58.36 24.40 13.6 Example 4 70.00 72.46 72.64 72.64 68.44 52.96 28.60 18.40 4.00 Example 5 40.72 59.20 70.84 70.84 64.84 55.84 34.96 15.76 6.76

[0088] Table 6 Comparison results of CO catalytic activity test for NH3-SCR / CO catalytic oxidation reaction coupling

[0089] CO conversion 150℃ 175℃ 200℃ 225℃ 250℃ 275℃ 300℃ 350℃ 400℃ Example 1 25.00 40.6 49.00 57.55 69.25 80.05 85.30 95.05 99.25 Example 2 16.75 31.75 40.00 49.75 56.05 62.05 70.9 86.20 95.95 Example 3 0 2.36 48.06 63.09 74.35 87.4 91.45 98.35 99.10 Example 4 10.00 18.55 37.15 47.50 67.15 91.00 95.50 99.10 99.70 Example 5 13.75 28.00 40.00 57.1 71.05 85.15 91.00 96.40 99.10

[0090] Figure 6 The NO conversion rate and CO conversion rate diagrams of the manganese-based catalysts prepared in Examples 1-5 for NH3-SCR / CO catalytic oxidation reaction coupling are shown in Figures 1-5, respectively. x Figure 6 It can be seen from Tables 5, 6 and x x x

[0091] Comparative Example 4

[0092] The difference between the present example and Example 1 is that the molar ratio of Ce(NO3)3.6H2O and Mn(NO3)2 in the preparation of the manganese-based catalyst in step 2) is adjusted to 3:1, and the sum of the molar amounts is kept at 0.02 mol, and the remaining steps are all referred to Example 1, i.e. the three-dimensionally ordered macroporous manganese-based catalyst of the present example is obtained.​​​​​

[0093] Comparative Example 5

[0094] The difference between this comparative example and Example 1 is that the calcination temperature in step 2) is adjusted to 500°C, and the rest of the process steps are referred to Example 1 to obtain the catalyst of this comparative example.

[0095] The product catalysts of Comparative Examples 4 and 5 are tested for performance by referring to the catalyst activity evaluation method described above, and compared with Example 1, and the results are shown in Tables 7-8 and Figure 7 .

[0096] Table 7 Comparative results of NH3-SCR catalytic activity test for NH3-SCR / CO catalytic oxidation reaction coupling

[0097] NO x conversion rate 150℃ 175℃ 200℃ 225℃ 250℃ 275℃ 300℃ 350℃ 400℃ Example 1 83.20 88.00 90.40 94.00 95.20 92.80 83.20 49.60 28.00 Comparative Example 4 73.96 80.8 86.44 92.56 92.56 87.76 63.76 35.20 20.80 Comparative Example 5 58.00 64.00 79.48 82.00 82.00 82.00 79.60 61.60 43.00

[0098] Table 8 Comparative results of CO catalytic activity test for NH3-SCR / CO catalytic oxidation reaction coupling

[0099]

[0100]

[0101] Figure 7 The NOx conversion rate and CO conversion rate diagrams of the manganese-based catalysts prepared in Example 1 and Comparative Examples 4 and 5 for NH3-SCR / CO catalytic oxidation reaction coupling are shown in Figures 1-3, respectively, according to Tables 7, 8 and x . Figure 7 It can be seen from Tables 7, 8 and

[0102] Comparative Example 6

[0103] The difference between this comparative example and Example 1 is that the template preparation method in step 1) is adjusted, specifically:

[0104] 30 mL of styrene (C8H8) is measured and added to a separatory funnel, and 30 mL of the prepared NaOH solution is used to wash the styrene 4 times to remove the polymerization inhibitor in the styrene, at which time the styrene appears light yellow, and then deionized water is used to wash until the solution is neutral;

[0105] The washed styrene solution was mixed with 500 mL of deionized water and added to a three-necked flask, heated to 70°C in a water bath, and the whole process was carried out under stirring at a speed of 260 rpm / min, then a preheated 70°C potassium persulfate initiator solution (0.20 g dissolved in 20 mL of deionized water) was added, and stirring was continued for 12 h to obtain a monodisperse PS microsphere solution;

[0106] The water bath was turned off, and the cooled PS microsphere emulsion was placed on a Buchner funnel for suction filtration to remove impurities generated during polymerization. An appropriate amount of the filtered emulsion was added to a culture dish, which was then placed in a forced air drying oven at 40°C for drying and solidification, and finally an ordered packed PS hard template was formed.

[0107] The remaining steps were performed according to Example 1 to obtain the catalyst of the present comparative example.

[0108] The catalyst performance of the product of Comparative Example 6 was tested according to the catalyst activity evaluation method described above, and compared with Example 1, and the results are shown in Tables 9-10 and Figure 8

[0109] Table 9. Comparative results of NH3-SCR catalytic activity test for NH3-SCR / CO catalytic oxidation reaction coupling

[0110] NO x conversion rate 150℃ 175℃ 200℃ 225℃ 250℃ 275℃ 300℃ 350℃ 400℃ Example 1 83.20 88.00 90.40 94.00 95.20 92.80 83.20 49.60 28.00 Comparative Example 6 15.01 23.21 25.75 31.02 31.00 28.60 27.52 21.00 17.63

[0111] Table 10. Comparative results of CO catalytic activity test for NH3-SCR / CO catalytic oxidation reaction coupling

[0112] CO conversion 150℃ 175℃ 200℃ 225℃ 250℃ 275℃ 300℃ 350℃ 400℃ Example 1 25.00 40.60 49.00 57.55 69.25 80.05 85.30 95.05 99.25 Comparative Example 6 22.05 28.63 31.21 32.05 38.92 42.21 53.32 82.21 92.15

[0113] Figure 8 The NOx conversion rate and CO conversion rate diagram for the manganese-based catalyst prepared in Example 1 and Comparative Example 6 for NH3-SCR / CO catalytic oxidation reaction coupling is shown in Figure 1, and the results are shown in Tables 9, 10 and x Figure 8 It can be seen that after replacing the PMMA template with a PS template, the catalyst prepared under the conditions of Comparative Example 6 showed poor denitration performance in the entire temperature range under the NH3-SCR coupling CO catalytic oxidation atmosphere, with a maximum NOx conversion rate of only 30% at 150-300°C, and the CO conversion rate also decreased significantly compared to the catalyst prepared under the conditions of Example 1. In summary, the catalyst prepared under the conditions of Example 1 has the strongest catalytic ability to synergistically remove NOx and CO.

[0114] ​​In summary, the three-dimensional ordered macroporous (3DOM) material is prepared by using polymethyl methacrylate as a template and manganese and other metal composite oxides as a main body. Compared with a traditional catalyst, the three-dimensional ordered macroporous channel is three-dimensionally connected and cross-linked, arranged in an ordered manner, and has a uniform pore size, which can significantly increase the specific surface area of the catalyst. The structure provides a good gas diffusion channel for a gas-solid two-phase catalytic reaction process, greatly improves the mutual contact of the catalyst and the gas phase molecules, increases the reaction contact time, and further improves the activity of the catalyst. The catalyst is used for coupling NH3-SCR / CO catalytic oxidation reaction, and shows the ability of synergistically removing NO x and CO.

[0115] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A process for the preparation of a three-dimensionally ordered macroporous manganese-based catalyst, characterized in that: The application relates to a preparation method of a three-dimensional ordered macroporous manganese-based catalyst. Methyl methacrylate is mixed with deionized water in a water bath, preheated potassium persulfate initiator solution is added into the mixture, and stirring is continued to obtain a monodisperse polymethyl methacrylate microsphere emulsion; The monodisperse polymethyl methacrylate microsphere emulsion is centrifuged to obtain a cream solid, and the cream solid is dried to obtain a polymethyl methacrylate template; Ce(NO3)3.6H2O, Mn(NO3)2 and citric acid are dissolved in ethanol to obtain a manganese-based precursor solution; The polymethyl methacrylate template is added into the manganese-based precursor solution, vacuum impregnation is carried out, and then solid-liquid separation is carried out through vacuum filtration to obtain a solid Mn-M@PMMA precursor material; after drying and calcination, the temperature is lowered to room temperature to obtain the three-dimensional ordered macroporous manganese-based catalyst.

2. The method of making a three-dimensionally ordered macroporous manganese-based catalyst according to claim 1, wherein: The volume ratio of the methyl methacrylate, the deionized water and the potassium persulfate solution is 1:11-12:(0.3-0.5).

3. The method of making a three-dimensionally ordered macroporous manganese-based catalyst of claim 2, wherein: The water bath heating and stirring temperature is 50-80 DEG C, the stirring speed is 200-400 rpm, and the stirring time is 30-60 min.

4. The method of making a three-dimensionally ordered macroporous manganese-based catalyst of claim 3, wherein: The centrifugation speed of the monodisperse polymethyl methacrylate microsphere emulsion is 1000-4000 rpm, the centrifugation time is 20-60 min, the drying temperature of the cream solid obtained through centrifugation is 50-100 DEG C, and the drying time is 10-15 h.

5. The method of making a three-dimensionally ordered macroporous manganese-based catalyst of claim 1, wherein: The sum of the molar amounts of the Ce(NO3)3.6H2O and the Mn(NO3)2 is 0.01-0.03 mol, and the molar ratio is 3:1-1:

3.

6. The method of making a three-dimensionally ordered macroporous manganese-based catalyst according to claim 5, wherein: In the precursor solution, the total metal salt ion concentration of Mn and Ce is 1-2 mol / L, and the molar ratio of citric acid to metal salt ions is 1:

1.

7. The method of making a three-dimensionally ordered macroporous manganese-based catalyst of claim 5, wherein: The vacuum impregnation time is 4-9 h.

8. The method of making a three-dimensionally ordered macroporous manganese-based catalyst of claim 5, wherein: The drying time of the solid Mn-M@PMMA precursor material is 8-12 h, the temperature is 40-60 DEG C, and the calcination is carried out by increasing the temperature from room temperature to 400-600 DEG C at a temperature increasing speed of 1-5 DEG C per hour and then keeping the temperature for 2-5 h.

9. The three-dimensionally ordered macroporous manganese-based catalyst prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The catalyst is mainly composed of manganese oxide and cerium oxide, the molar ratio of Mn / Ce is 3:1-1:3, the macroporous structure channel is three-dimensionally penetrated, cross-linked, regularly arranged and ordered, and the pore size is uniform.

10. Use of a catalyst as claimed in claim 9, characterised in that: The catalyst is used for NH3-SCR coupling CO catalytic oxidation reaction.

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