A preparation method of a denitration catalyst

Abstract

The present invention relates to a preparation method of a denitration catalyst, belonging to the technical field of flue gas treatment, and comprising the following steps: A1. Prepare MgO / g-C3N4 composite material; A2. Perform amino modification on the MgO / g-C3N4 composite material; A3. Prepare cerium-manganese-lanthanum composite oxide / TiO2 composite material; A4. Perform phosphoric acid modification on the cerium-manganese-lanthanum composite oxide / TiO2 composite material; A5. Disperse the phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in ethanol, then add the amino-modified MgO / g-C3N4 composite material, perform ultrasonic stirring, centrifugation, washing, drying, and calcination to obtain the denitration catalyst. The technical solution of the present invention significantly improves the anti-poisoning ability and low-temperature denitration activity of the denitration catalyst through the synergistic effect of each component.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas treatment, and specifically relates to a preparation method of a denitration catalyst. Background Art

[0002] Nitrogen oxides (NO x ) are the main culprits causing photochemical smog, ozone layer depletion and acid rain formation. They not only harm the environment but also pose great harm to human health. Therefore, the treatment of NO x is an urgent problem to be solved at present. Currently, the method widely used in industry is the selective catalytic reduction (SCR) technology, which has the advantages of high purification efficiency and low economic cost, and is one of the most effective technologies for removing NO x .

[0003] The core of the selective catalytic reduction technology is the catalyst, which can directly affect the overall denitration efficiency and stability. Traditional vanadium-titanium catalysts are difficult to meet the requirements due to reasons such as high operating temperature, narrow operating temperature window, and strong biological toxicity of the active component vanadium that may cause secondary pollution. Manganese-based catalysts have received increasing attention from domestic and foreign researchers due to their good low-temperature denitration activity and are expected to replace vanadium-based catalysts in the field of low-temperature denitration. However, the manganese-based catalysts have poor anti-poisoning ability. Therefore, it is necessary to provide a denitration catalyst with strong anti-poisoning ability, high low-temperature denitration activity and a wider operating temperature window. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a denitration catalyst, which combines a phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material and an amino-modified MgO / g-C3N4 composite material, significantly improves the stability and specific surface area of the denitration catalyst, thereby improving the denitration catalytic activity of the denitration catalyst, and through the synergistic effect of each component, significantly improves the anti-poisoning ability and low-temperature denitration activity of the denitration catalyst.

[0005] The technical problem to be solved by the present invention: Traditional vanadium-titanium catalysts are difficult to meet the requirements due to reasons such as high operating temperature, narrow operating temperature window, and strong biological toxicity of the active component vanadium that may cause secondary pollution. Manganese-based catalysts have good low-temperature denitration activity, but the manganese-based catalysts have poor anti-poisoning ability.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of a denitration catalyst includes the following steps:

[0008] A1. Ultrasonically disperse g-C3N4 nanosheets in ethanol, then add a magnesium source and continue ultrasonic dispersion until uniform to obtain a mixed solution. Put the mixed solution into an agate mortar and grind it into a paste, then dry and calcine it to obtain a MgO / g-C3N4 composite material.

[0009] Further, in step A1, the mass ratio of g-C3N4 nanosheets to the magnesium source is (80 - 100):(5 - 15).

[0010] Further, in step A1, the grinding time is 20 - 50 min.

[0011] Further, in step A1, the calcination temperature is 400 - 500 °C and the calcination time is 2 - 5 h.

[0012] A2. Add the MgO / g-C3N4 composite material to ammonia water and carry out a heating and stirring reaction. After the reaction is completed, carry out centrifugation, washing, and drying to obtain an amino-modified MgO / g-C3N4 composite material.

[0013] In the above preparation process, the g-C3N4 nanosheets have a two-dimensional porous structure and a high specific surface area. Uniformly loading MgO on the g-C3N4 nanosheets helps to provide more basic adsorption sites. The g-C3N4 nanosheets have rich nitrogen-containing functional groups and a large pore volume. At the same time, the loaded MgO and amino groups in the composite material, through the synergistic effect of the basic adsorption sites provided by MgO, the nitrogen-containing functional groups, and the amino groups, can significantly enhance the surface ammonia activation and NO x adsorption capacity. At the same time, it can also adsorb the acidic gas sulfur dioxide in flue gas, avoiding the reaction of sulfur dioxide with acidic active centers and causing the inactivation of acidic active centers, and significantly improving the anti-sulfur poisoning ability of the denitrification catalyst.

[0014] Further, in step A2, the dosage ratio of the MgO / g-C3N4 composite material to ammonia water is (2 - 6) g:(32 - 40) mL.

[0015] Further, in step A2, the temperature of the heating and stirring reaction is 60 - 90 °C and the time is 4 - 10 h.

[0016] A3. Dissolve a cerium source, a manganese source, and a lanthanum source in deionized water, then add citric acid and stir until completely dissolved to obtain a mixed metal salt solution. Add TiO2 to the mixed metal salt solution, disperse it evenly, and keep it at 30 - 50 °C for 2 - 8 h, then dry and calcine it to obtain a cerium-manganese-lanthanum composite oxide / TiO2 composite material.

[0017] Further, in step A3, the mass ratio of the cerium source, the manganese source, the lanthanum source, citric acid, and TiO2 is (5 - 10):(5 - 10):(3 - 8):(2 - 6):(90 - 100).

[0018] Further, in step A3, the TiO2 is anatase TiO2.

[0019] Further, in step A3, the calcination temperature is 500 - 600 °C, and the calcination time is 2 - 7 h.

[0020] A4. Disperse the cerium - manganese - lanthanum composite oxide / TiO2 composite material in a phosphoric acid solution, heat and stir for reaction, then perform centrifugation, washing, and drying to obtain a phosphoric - acid - modified cerium - manganese - lanthanum composite oxide / TiO2 composite material;

[0021] During the above - mentioned preparation process, the cerium - manganese - lanthanum composite oxide is loaded on the TiO2 support. In the cerium - manganese - lanthanum composite oxide, La2O3 is the acidic active center. After the surface of the cerium - manganese - lanthanum composite oxide / TiO2 composite material is modified with phosphoric acid, the number of acidic active sites is further increased, which can promote the adsorption and activation of the reaction molecule NH3 on the surface and inside the pores of the catalyst, thereby improving the denitrification catalytic activity of the catalyst. In the present invention, loading La2O3 on the TiO2 support can prevent TiO2 from transforming from the anatase type to the rutile type under high - temperature conditions, and improve the high - temperature resistance performance of the catalyst. In the cerium - manganese - lanthanum composite oxide, the addition of the active components CeO2 and MnO2 significantly improves the low - temperature denitrification catalytic activity of the catalyst.

[0022] Further, in step A4, the dosage ratio of the cerium - manganese - lanthanum composite oxide / TiO2 composite material to the phosphoric acid solution is (1 - 4) g:(30 - 45) mL.

[0023] Further, in step A4, the concentration of the phosphoric acid solution is 1 - 5 mol / L.

[0024] Further, in step A4, the temperature of the heat - stirring reaction is 50 - 60 °C, and the time is 2 - 5 h.

[0025] A5. Disperse the phosphoric - acid - modified cerium - manganese - lanthanum composite oxide / TiO2 composite material in ethanol, then add the amino - modified MgO / g - C3N4 composite material, ultrasonically stir for 2 - 4 h, perform centrifugation, washing, drying, and calcination to obtain a denitrification catalyst.

[0026] During the above preparation process, the phosphoric acid-modified cerium manganese lanthanum composite oxide / TiO2 composite material and the amino-modified MgO / g-C3N4 composite material are combined through the electrostatic interaction between the negatively charged phosphate groups on the phosphoric acid-modified cerium manganese lanthanum composite oxide / TiO2 composite material and the positively charged amino groups on the amino-modified MgO / g-C3N4 composite material. Combining composite materials with different shapes significantly improves the stability and specific surface area of the denitration catalyst, thereby enhancing the denitration catalytic activity of the denitration catalyst. In the present invention, the acidic active center and the basic active center are respectively loaded on different carriers, which can avoid the reduction of the denitration catalytic activity caused by the mutual neutralization of the acidic and basic active centers.

[0027] Further, in step A5, the mass ratio of the phosphoric acid-modified cerium manganese lanthanum composite oxide / TiO2 composite material to the amino-modified MgO / g-C3N4 composite material is (7-8):(2-3).

[0028] Further, in step A5, the calcination temperature is 500-650 °C, and the calcination time is 1-3 h.

[0029] Further, the preparation method of the g-C3N4 nanosheets includes the following steps:

[0030] Put urea in a crucible, then place it in a muffle furnace for the first calcination, cool to room temperature, and then perform the second calcination to obtain g-C3N4 nanosheets.

[0031] Further, the temperature of the first calcination is 540-570 °C, the calcination time is 4-6 h, and the heating rate is 1-3 °C / min.

[0032] Further, the temperature of the second calcination is 450-500 °C, the calcination time is 2-3 h, and the heating rate is 3-5 °C / min.

[0033] Advantages of the present invention:

[0034] (1) In the technical solution of the present invention, the phosphoric acid-modified cerium manganese lanthanum composite oxide / TiO2 composite material and the amino-modified MgO / g-C3N4 composite material are combined, which significantly improves the stability and specific surface area of the denitration catalyst, thereby enhancing the denitration catalytic activity of the denitration catalyst. In the present invention, the acidic active center and the basic active center are respectively loaded on different carriers, which can avoid the reduction of the denitration catalytic activity caused by the mutual neutralization of the acidic and basic active centers.

[0035] (2) In the technical solution of the present invention, MgO is uniformly loaded on the two-dimensional porous g-C3N4 nanosheets, which helps to provide more basic adsorption sites. Through the synergistic effect of the basic adsorption sites provided by MgO, the nitrogen-containing functional groups and the amino groups, the surface ammonia activation and NOx The adsorption capacity can also adsorb the acidic gas sulfur dioxide in the flue gas, significantly improving the sulfur poisoning resistance of the denitration catalyst.

[0036] (3) In the technical solution of the present invention, La2O3 in the cerium-manganese-lanthanum composite oxide is an acidic active center. After the surface of the cerium-manganese-lanthanum composite oxide / TiO2 composite material is modified with phosphoric acid, the number of acidic active sites is further increased, which can promote the adsorption and activation of the reaction molecule NH3 on the surface and inside the pores of the catalyst, thereby improving the denitration catalytic activity of the catalyst. In the cerium-manganese-lanthanum composite oxide, the addition of the active components CeO2 and MnO2 significantly improves the low-temperature denitration catalytic activity of the catalyst.

[0037] (4) In the technical solution of the present invention, loading La2O3 on the TiO2 support can prevent TiO2 from transforming from the anatase type to the rutile type under high-temperature conditions, improving the high-temperature resistance of the catalyst. Specific embodiments

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0039] Example 1: This example provides a preparation method of g-C3N4 nanosheets, including the following steps:

[0040] Put 300 g of urea in a crucible, then put it into a muffle furnace and conduct the first calcination at 560 °C for 5 h with a heating rate of 2 °C / min. After cooling to room temperature, conduct the second calcination at 470 °C for 3 h with a heating rate of 4 °C / min to obtain g-C3N4 nanosheets.

[0041] Example 2: A preparation method of a denitration catalyst, including the following steps:

[0042] A1. Ultrasonically disperse 80 g of the g-C3N4 nanosheets prepared in Example 1 in 8 L of ethanol, then add 5 g of magnesium nitrate hexahydrate, and continue to ultrasonically disperse evenly to obtain a mixed solution; put the mixed solution into an agate mortar and grind it for 20 min until it becomes paste-like, then dry it, and then calcine it at 400 °C for 2 h to obtain the MgO / g-C3N4 composite material;

[0043] A2. Add 30 g of the MgO / g-C3N4 composite material to 480 mL of ammonia water, heat and stir the reaction at 60 °C for 4 h. After the reaction is completed, centrifuge, wash, and dry to obtain the amino-modified MgO / g-C3N4 composite material;

[0044] A3. Dissolve 7.5 g of cerium nitrate hexahydrate, 7.5 g of manganese nitrate hexahydrate and 4.5 g of lanthanum nitrate hexahydrate in 100 mL of deionized water, then add 3 g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; add 135 g of anatase TiO2 (specific surface area 180 m 2 / g) to the mixed metal salt solution, after dispersing evenly, keep it at 30 °C for 2 h, dry, and calcine at 500 °C for 2 h to obtain a cerium-manganese-lanthanum composite oxide / TiO2 composite material;

[0045] A4. Disperse 100 g of the cerium-manganese-lanthanum composite oxide / TiO2 composite material in 1400 mL of a phosphoric acid solution with a concentration of 1 mol / L, heat and stir at 50 °C for 2 h, then perform centrifugation, washing and drying to obtain a phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material;

[0046] A5. Disperse 84 g of the phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in 500 mL of ethanol, then add 24 g of the amino-modified MgO / g-C3N4 composite material, ultrasonically stir for 2 h, perform centrifugation, washing and drying, and calcine at 500 °C for 1 h to obtain a denitration catalyst.

[0047] Example 3: A method for preparing a denitration catalyst, comprising the following steps:

[0048] A1. Ultrasonically disperse 80 g of the g-C3N4 nanosheets prepared in Example 1 in 9 L of ethanol, then add 7 g of magnesium nitrate hexahydrate, continue to ultrasonically disperse evenly to obtain a mixed solution; put the mixed solution into an agate mortar and grind for 30 min until it becomes pasty, then dry, and then calcine at 400 °C for 3 h to obtain a MgO / g-C3N4 composite material;

[0049] A2. Add 40 g of the MgO / g-C3N4 composite material to 520 mL of ammonia water, heat and stir at 70 °C for 5 h, after the reaction is completed, perform centrifugation, washing and drying to obtain an amino-modified MgO / g-C3N4 composite material;

[0050] A3. Dissolve 10 g of cerium nitrate hexahydrate, 10 g of manganese nitrate hexahydrate and 7 g of lanthanum nitrate hexahydrate in 140 mL of deionized water, then add 4 g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; add 140 g of anatase TiO2 (specific surface area 180 m 2 / g) to the mixed metal salt solution, after dispersing evenly, keep it at 40 °C for 3 h, dry, and calcine at 500 °C for 3 h to obtain a cerium-manganese-lanthanum composite oxide / TiO2 composite material;

[0051] A4. Disperse 120 g of cerium-manganese-lanthanum composite oxide / TiO₂ composite material in 1500 mL of phosphoric acid solution with a concentration of 2 mol / L, heat and stir the reaction at 50 °C for 3 h, then carry out centrifugation, washing, and drying to obtain phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO₂ composite material;

[0052] A5. Disperse 88 g of phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO₂ composite material in 450 mL of ethanol, then add 28 g of amino-modified MgO / g-C₃N₄ composite material, ultrasonically stir for 3 h, carry out centrifugation, washing, and drying, and calcine at 550 °C for 2 h to obtain a denitrification catalyst.

[0053] Example 4: A preparation method of a denitrification catalyst, comprising the following steps:

[0054] A1. Ultrasonically disperse 90 g of g-C₃N₄ nanosheets prepared in Example 1 in 9 L of ethanol, then add 10 g of magnesium nitrate hexahydrate, continue to ultrasonically disperse evenly to obtain a mixed solution; put the mixed solution into an agate mortar and grind it for 40 min until it becomes paste-like, then carry out drying, and then calcine at 400 °C for 4 h to obtain MgO / g-C₃N₄ composite material;

[0055] A2. Add 60 g of MgO / g-C₃N₄ composite material to 560 mL of ammonia water, heat and stir the reaction at 7 °C for 7 h, after the reaction is completed, carry out centrifugation, washing, and drying to obtain amino-modified MgO / g-C₃N₄ composite material;

[0056] A3. Dissolve 11 g of cerium nitrate hexahydrate, 10 g of manganese nitrate hexahydrate, and 9 g of lanthanum nitrate hexahydrate in 150 mL of deionized water, then add 6.5 g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; add 143 g of anatase TiO₂ (specific surface area 180 m 2 / g) to the mixed metal salt solution, disperse evenly, keep it at 40 °C for 6 h, dry, and calcine at 550 °C for 5 h to obtain cerium-manganese-lanthanum composite oxide / TiO₂ composite material;

[0057] A4. Disperse 130 g of cerium-manganese-lanthanum composite oxide / TiO₂ composite material in 1600 mL of phosphoric acid solution with a concentration of 3 mol / L, heat and stir the reaction at 60 °C for 4 h, then carry out centrifugation, washing, and drying to obtain phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO₂ composite material;

[0058] A5. Disperse 91 g of phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO₂ composite material in 450 mL of ethanol, then add 31 g of amino-modified MgO / g-C₃N₄ composite material, ultrasonically stir for 3 h, carry out centrifugation, washing, and drying, and calcine at 600 °C for 2 h to obtain a denitrification catalyst.

[0059] Example 5: A preparation method of a denitration catalyst, comprising the following steps:

[0060] A1. Ultrasonically disperse 95 g of the g-C3N4 nanosheets prepared in Example 1 in 9 L of ethanol, then add 12 g of magnesium nitrate hexahydrate, and continue to ultrasonically disperse evenly to obtain a mixed solution; put the mixed solution into an agate mortar and grind it for 40 min until it becomes paste-like, then dry it, and then calcine it at 400 °C for 5 h to obtain the MgO / g-C3N4 composite material;

[0061] A2. Add 80 g of the MgO / g-C3N4 composite material to 600 mL of ammonia water, heat and stir the reaction at 90 °C for 5 h, and after the reaction is completed, carry out centrifugation, washing, and drying to obtain the amino-modified MgO / g-C3N4 composite material;

[0062] A3. Dissolve 15 g of cerium nitrate hexahydrate, 7.5 g of manganese nitrate hexahydrate, and 10 g of lanthanum nitrate hexahydrate in 165 mL of deionized water, then add 8 g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; add 150 g of anatase TiO2 (specific surface area 180 m 2 / g) to the mixed metal salt solution, disperse it evenly, keep it at 50 °C for 4 h, dry it, and calcine it at 600 °C for 3 h to obtain the cerium-manganese-lanthanum composite oxide / TiO2 composite material;

[0063] A4. Disperse 160 g of the cerium-manganese-lanthanum composite oxide / TiO2 composite material in 1700 mL of a phosphoric acid solution with a concentration of 5 mol / L, heat and stir the reaction at 60 °C for 3 h, then carry out centrifugation, washing, and drying to obtain the phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material;

[0064] A5. Disperse 96 g of the phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in 500 mL of ethanol, then add 24 g of the amino-modified MgO / g-C3N4 composite material, ultrasonically stir for 3 h, centrifuge, wash, dry, and calcine at 650 °C for 2 h to obtain the denitration catalyst.

[0065] Example 6: A preparation method of a denitration catalyst, comprising the following steps:

[0066] A1. Ultrasonically disperse 100 g of the g-C3N4 nanosheets prepared in Example 1 in 10 L of ethanol, then add 15 g of magnesium nitrate hexahydrate, and continue to ultrasonically disperse evenly to obtain a mixed solution; put the mixed solution into an agate mortar and grind it for 50 min until it becomes paste-like, then dry it, and then calcine it at 500 °C for 5 h to obtain the MgO / g-C3N4 composite material;

[0067] A2. Add 90 g of MgO / g-C3N4 composite material to 600 mL of ammonia water, heat and stir the reaction at 90 °C for 10 h. After the reaction, centrifuge, wash, and dry to obtain an amino-modified MgO / g-C3N4 composite material;

[0068] A3. Dissolve 15 g of cerium nitrate hexahydrate, 15 g of manganese nitrate hexahydrate, and 12 g of lanthanum nitrate hexahydrate in 220 mL of deionized water, then add 9 g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; Add 150 g of anatase TiO2 (specific surface area 180 m 2 / g) to the mixed metal salt solution. After dispersing evenly, keep it at 50 °C for 8 h, dry, and calcine at 600 °C for 5 h to obtain a cerium-manganese-lanthanum composite oxide / TiO2 composite material;

[0069] A4. Disperse 160 g of the cerium-manganese-lanthanum composite oxide / TiO2 composite material in 1800 mL of a phosphoric acid solution with a concentration of 5 mol / L, heat and stir the reaction at 60 °C for 5 h, then centrifuge, wash, and dry to obtain a phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material;

[0070] A5. Disperse 96 g of the phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in 600 mL of ethanol, then add 36 g of the amino-modified MgO / g-C3N4 composite material, ultrasonically stir for 4 h, centrifuge, wash, and dry, and calcine at 650 °C for 3 h to obtain a denitrification catalyst.

[0071] Comparative Example 1

[0072] Compared with Example 3, the amino-modified MgO / g-C3N4 composite material was not added in Comparative Example 1, and magnesium nitrate hexahydrate was added during the preparation of the cerium-manganese-lanthanum composite oxide / TiO2 composite material. The specific preparation steps are as follows:

[0073] A1. Dissolve 10 g of cerium nitrate hexahydrate, 10 g of manganese nitrate hexahydrate, 2.9 g of magnesium nitrate hexahydrate, and 7 g of lanthanum nitrate hexahydrate in 140 mL of deionized water, then add 4 g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; Add 140 g of anatase TiO2 (specific surface area 180 m 2 / g) to the mixed metal salt solution. After dispersing evenly, keep it at 40 °C for 3 h, dry, and calcine at 500 °C for 3 h to obtain a cerium-manganese-magnesium-lanthanum composite oxide / TiO2 composite material;

[0074] A2. Disperse 120 g of cerium-manganese-magnesium-lanthanum composite oxide / TiO2 composite material in 1500 mL of phosphoric acid solution with a concentration of 2 mol / L. After heating and stirring the reaction at 50 °C for 3 h, carry out centrifugation, washing, and drying to obtain a phosphoric acid-modified cerium-manganese-magnesium-lanthanum composite oxide / TiO2 composite material, which is the denitration catalyst.

[0075] Comparative Example 2

[0076] Compared with Example 3, lanthanum nitrate hexahydrate was not added during the preparation process of Comparative Example 2, and other steps and raw materials were the same as those in Example 3.

[0077] Comparative Example 3

[0078] Compared with Example 3, cerium nitrate hexahydrate was not added during the preparation process of Comparative Example 3, and other steps and raw materials were the same as those in Example 3.

[0079] Performance Testing

[0080] (1) Denitration catalytic activity test: Simulated flue gas composition: NO: 1000 ppm, NH3: 1000 ppm, O2: 8%, N2 as the balance gas, space velocity of 30000 h -1 , flue gas flow rate of 300 mL / min. Take the same volume of catalyst and put it into a fixed-bed reactor for testing. Test the denitration efficiency of the catalyst at different temperatures, and control the reaction temperature at 100 - 350 °C. The results are shown in Table 1;

[0081] (2) Water and sulfur resistance performance test of denitration catalyst: Simulated flue gas composition: NO: 1000 ppm, NH3: 1000 ppm, O2: 8%, H2O: 20%, SO2: 500 ppm, N2 as the balance gas, space velocity of 30000 h -1 , flue gas flow rate of 300 mL / min. Take the same volume of catalyst and put it into a fixed-bed reactor for testing. Test the denitration efficiency of the catalyst at different temperatures, and control the reaction temperature at 100 - 300 °C. The results are shown in Table 2;

[0082] (3) Stability test of denitration catalyst: Simulated flue gas composition: NO: 1000 ppm, NH3: 1000 ppm, O2: 8%, H2O: 20%, SO2: 500 ppm, N2 as the balance gas, space velocity of 30000 h -1 , flue gas flow rate of 300 mL / min. Take the same volume of catalyst and put it into a fixed-bed reactor for testing. Test the denitration efficiency of the catalyst under 120 h, and control the reaction temperature at 150 °C. The results are shown in Table 3;

[0083] Table 1

[0084]

[0085] Table 2

[0086]

[0087] Table 3

[0088]

[0089] It can be seen from the data in Table 1, 2 and 3 that the denitration catalyst prepared by the present invention has excellent denitration catalytic activity, water and sulfur resistance performance and stability. By comparing the data of Example 3 and Comparative Example 1, it can be seen that due to the absence of the amino-modified MgO / g-C3N4 composite material, and the magnesium oxide is loaded on the carrier TiO2, the basic active center and the pickling active center are loaded on the same carrier, resulting in a significant decrease in denitration catalytic activity, water and sulfur resistance performance and stability. By comparing the data of Example 3 and Comparative Examples 2 and 3, it can be seen that the absence of lanthanum nitrate hexahydrate or cerium nitrate hexahydrate leads to a decrease in denitration catalytic activity, water and sulfur resistance performance and stability.

[0090] In the description of the specification, the description referring to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0091] The above content is only an example and illustration of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a denitration catalyst, characterized in that: The following steps are involved: A1, ultrasonically dispersing g-C3N4 nanosheets in ethanol, adding a magnesium source, and continuing to ultrasonically disperse uniformly to obtain a mixed solution; grinding the mixed solution in an agate mortar to a paste, and then drying and calcining to obtain a MgO / g-C3N4 composite material; A2, adding the MgO / g-C3N4 composite material into ammonia water for heating and stirring reaction, and after the reaction is completed, centrifuging, washing and drying to obtain an amino-modified MgO / g-C3N4 composite material; A3, dissolving a cerium source, a manganese source and a lanthanum source in deionized water, adding citric acid and stirring until completely dissolved to obtain a mixed metal salt solution; adding TiO2 to the mixed metal salt solution, dispersing it evenly, maintaining it at 30-50° C. for 2-8 hours, drying and calcining to obtain a cerium manganese lanthanum composite oxide / TiO2 composite material; A4, dispersing the cerium manganese lanthanum composite oxide / TiO2 composite material in a phosphoric acid solution, heating and stirring the solution for reaction, and then centrifuging, washing, and drying the solution to obtain a phosphoric acid-modified cerium manganese lanthanum composite oxide / TiO2 composite material; A5. Disperse the phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in ethanol, add the amino-modified MgO / g-C3N4 composite material, ultrasonically stir for 2-4 hours, centrifuge, wash, dry and calcine to obtain a denitrification catalyst.

2. The method for preparing a denitration catalyst according to claim 1, characterized in that: In the step A1, the mass ratio of g-C3N4 nanosheets to magnesium source is (80-100): (5-15).

3. The method for preparing a denitration catalyst according to claim 1, characterized in that: In the step A1, the grinding time is 20-50 minutes; the calcination temperature is 400-500° C., and the calcination time is 2-5 hours.

4. The method for preparing a denitration catalyst according to claim 1, characterized in that: In the step A2, the usage ratio of the MgO / g-C3N4 composite material and ammonia water is (2-6) g: (32-40) mL.

5. The method for preparing a denitration catalyst according to claim 1, characterized in that: In the step A2, the temperature of the heating and stirring reaction is 60-90° C. and the time is 4-10 hours.

6. The method for preparing a denitration catalyst according to claim 1, characterized in that: In step A3, the mass ratio of the cerium source, the manganese source, the lanthanum source, the citric acid and TiO2 is (5-10): (5-10): (3-8): (2-6): (90-100).

7. The method for preparing a denitration catalyst according to claim 1, characterized in that: In the step A3, the calcination temperature is 500-600° C. and the calcination time is 2-7 hours.

8. The method for preparing a denitration catalyst according to claim 1, characterized in that: In step A4, the usage ratio of the cerium manganese lanthanum composite oxide / TiO2 composite material and the phosphoric acid solution is (1-4) g: (30-45) mL; and the concentration of the phosphoric acid solution is 1-5 mol / L.

9. The method for preparing a denitration catalyst according to claim 1, characterized in that: In step A4, the temperature of the heating and stirring reaction is 50-60° C. and the time is 2-5 hours.

10. The method for preparing a denitration catalyst according to claim 1, characterized in that: In the step A5, the mass ratio of the phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material and the amino-modified MgO / g-C3N4 composite material is (7-8):(2-3); the calcination temperature is 500-650°C, and the calcination time is 1-3h.

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