Preparation method of denitration catalyst

Abstract

The invention relates to a preparation method of a denitration catalyst, and belongs to the technical field of flue gas treatment.The preparation method comprises the following steps that A1, an MgO / g-C3N4 composite material is prepared; a2, carrying out amino modification on the MgO / g-C3N4 composite material; a3, preparing a cerium-manganese-lanthanum composite oxide / TiO2 composite material; a4, carrying out phosphoric acid modification on the cerium-manganese-lanthanum composite oxide / TiO2 composite material; and A5, dispersing the phosphoric acid modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in ethanol, then adding the amino modified MgO / g-C3N4 composite material, and carrying out ultrasonic stirring, centrifugation, washing, drying and calcination to obtain the denitration catalyst. According to the technical scheme, through the synergistic effect of all the components, the anti-poisoning capacity and low-temperature denitration activity of the denitration catalyst are remarkably improved.

Description

Technical Field

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

[0002] Nitrogen oxides (NO x ) is the main culprit for photochemical smog, ozone layer depletion and acid rain, which not only harms the environment but also has great harm to human health. x The treatment of NO is an urgent problem to be solved. 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. x One of the most effective techniques.

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

[0004] The object of the present invention is to provide a method for preparing 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, thereby significantly improving 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 improving the anti-poisoning ability and low-temperature denitration activity of the denitration catalyst.

[0005] The technical problem to be solved by the present invention is that the conventional vanadium-titanium catalysts are difficult to meet the requirements due to the high operating temperature, narrow use temperature window, strong biological toxicity of the active component vanadium, and the possibility of secondary pollution. Manganese-based catalysts have good low-temperature denitrification activity, but their anti-poisoning ability is poor.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing a denitration catalyst comprises the following steps: 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; Furthermore, in step A1, the mass ratio of g-C3N4 nanosheets and magnesium source is (80-100):(5-15).

[0007] Furthermore, in step A1, the grinding time is 20-50 min.

[0008] Furthermore, in step A1, the calcination temperature is 400-500° C., and the calcination time is 2-5 hours.

[0009] 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; In the above preparation process, g-C3N4 nanosheets are two-dimensional porous structures with high specific surface area. The uniform loading of MgO on g-C3N4 nanosheets helps to provide more alkaline adsorption sites. g-C3N4 nanosheets have abundant nitrogen-containing functional groups and large pore volume. At the same time, the MgO and amino groups loaded on the composite material can significantly enhance the surface ammonia activation and NO through the synergistic effect of the alkaline adsorption sites provided by MgO, nitrogen-containing functional groups and amino groups. x It has good adsorption capacity and can also adsorb acidic gas sulfur dioxide in flue gas to avoid the deactivation of acidic active centers caused by the reaction of sulfur dioxide with the acidic active centers, which significantly improves the anti-sulfur poisoning ability of the denitrification catalyst.

[0010] Furthermore, in step A2, the usage ratio of MgO / g-C3N4 composite material and ammonia water is (2-6) g: (32-40) mL.

[0011] Furthermore, in step A2, the temperature of the heating and stirring reaction is 60-90° C. and the time is 4-10 h.

[0012] 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; Furthermore, in step A3, the mass ratio of the cerium source, manganese source, lanthanum source, citric acid and TiO2 is (5-10): (5-10): (3-8): (2-6): (90-100).

[0013] Furthermore, in step A3, TiO2 is anatase TiO2.

[0014] Furthermore, in step A3, the calcination temperature is 500-600° C., and the calcination time is 2-7 hours.

[0015] 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; In the above preparation process, the cerium manganese lanthanum composite oxide is loaded on the TiO2 carrier, and 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 acidic active sites are further increased, which can promote the adsorption and activation of the reaction molecule NH3 on the catalyst surface and inside the pores, thereby improving the denitration catalytic activity of the catalyst. The present invention loads La2O3 on the TiO2 carrier, which can prevent TiO2 from transforming from anatase type to rutile type under high temperature conditions, and improve the high temperature resistance of the catalyst. In the cerium manganese lanthanum composite oxide, the addition of active components CeO2 and MnO2 significantly improves the low-temperature denitration catalytic activity of the catalyst.

[0016] Furthermore, 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.

[0017] Furthermore, in step A4, the concentration of the phosphoric acid solution is 1-5 mol / L.

[0018] Furthermore, in step A4, the temperature of the heating and stirring reaction is 50-60° C. and the time is 2-5 h.

[0019] 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.

[0020] In the above-mentioned 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 together by 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. The composite materials of different shapes are combined together, which significantly improves the stability and specific surface area of ​​the denitration catalyst, thereby improving the denitration catalytic activity of the denitration catalyst. The present invention loads the acidic active center and the alkaline active center on different carriers respectively, which can avoid the reduction of the denitration catalytic activity due to the mutual neutralization of the acidic and alkaline active centers.

[0021] Furthermore, in 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).

[0022] Furthermore, in step A5, the calcination temperature is 500-650° C., and the calcination time is 1-3 h.

[0023] Furthermore, the preparation method of g-C3N4 nanosheets comprises the following steps: The urea was placed in a crucible, and then placed in a muffle furnace for the first calcination, cooled to room temperature, and then calcined for the second time to obtain g-C3N4 nanosheets.

[0024] Furthermore, the first calcination temperature is 540-570°C, the calcination time is 4-6h, and the heating rate is 1-3°C / min.

[0025] Furthermore, the second calcination temperature is 450-500°C, the calcination time is 2-3h, and the heating rate is 3-5°C / min.

[0026] Beneficial effects of the present invention: (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 together, which significantly improves the stability and specific surface area of ​​the denitration catalyst, thereby improving the denitration catalytic activity of the denitration catalyst. The present invention loads the acidic active center and the alkaline active center on different carriers respectively, which can avoid the reduction of the denitration catalytic activity due to the mutual neutralization of the acidic and alkaline active centers.

[0027] (2) In the technical solution of the present invention, MgO is uniformly loaded on the two-dimensional porous structure of g-C3N4 nanosheets, which helps to provide more alkaline adsorption sites. The synergistic effect of the alkaline adsorption sites, nitrogen-containing functional groups and amino groups provided by MgO can significantly enhance the surface ammonia activation and NO x It has strong adsorption capacity and can also adsorb acidic gas sulfur dioxide in flue gas, which significantly improves the anti-sulfur poisoning ability of denitrification catalyst.

[0028] (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 acidic active sites are further increased, which can promote the adsorption and activation of the reaction molecule NH3 on the catalyst surface and inside the pores, thereby improving the denitrification catalytic activity of the catalyst. The addition of active components CeO2 and MnO2 in the cerium manganese lanthanum composite oxide significantly improves the low-temperature denitrification catalytic activity of the catalyst.

[0029] (4) In the technical solution of the present invention, La2O3 is loaded on the TiO2 carrier, which can prevent TiO2 from transforming from anatase type to rutile type under high temperature conditions, thereby improving the high temperature resistance of the catalyst. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Embodiment 1: This embodiment provides a method for preparing g-C3N4 nanosheets, comprising the following steps: 300 g of urea was placed in a crucible and then put into a muffle furnace. The first calcination was carried out at 560°C for 5 h with a heating rate of 2°C / min. After cooling to room temperature, the second calcination was carried out at 470°C for 3 h with a heating rate of 4°C / min to obtain g-C3N4 nanosheets.

[0032] Embodiment 2: A method for preparing a denitration catalyst comprises the following steps: A1. Ultrasonic dispersion of 80 g of the g-C3N4 nanosheets prepared in Example 1 in 8 L of ethanol, and then adding 5 g of magnesium nitrate hexahydrate, and continuing ultrasonic dispersion to obtain a mixed solution; the mixed solution was put into an agate mortar and ground for 20 min until it became a paste, and then dried, and then calcined at 400° C. for 2 h to obtain a MgO / g-C3N4 composite material; A2, adding 30g of MgO / g-C3N4 composite material to 480mL of ammonia water, heating and stirring at 60°C for 4h, centrifuging, washing and drying after the reaction to obtain an amino-modified MgO / g-C3N4 composite material; 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, 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), after being evenly dispersed, kept at 30°C for 2h, dried, and calcined at 500°C for 2h to obtain a cerium-manganese-lanthanum composite oxide / TiO2 composite material; A4, dispersing 100g of cerium manganese lanthanum composite oxide / TiO2 composite material in 1400mL of 1mol / L phosphoric acid solution, heating and stirring at 50°C for 2h, centrifuging, washing and drying to obtain phosphoric acid-modified cerium manganese lanthanum composite oxide / TiO2 composite material; A5. Disperse 84 g of phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in 500 mL of ethanol, add 24 g of amino-modified MgO / g-C3N4 composite material, stir ultrasonically for 2 h, centrifuge, wash, dry, and calcine at 500 °C for 1 h to obtain a denitration catalyst.

[0033] Embodiment 3: A method for preparing a denitration catalyst comprises the following steps: A1. Ultrasonic dispersion of 80 g of the g-C3N4 nanosheets prepared in Example 1 in 9 L of ethanol, and then adding 7 g of magnesium nitrate hexahydrate, and continuing to ultrasonically disperse uniformly to obtain a mixed solution; the mixed solution was put into an agate mortar and ground for 30 min until it became a paste, and then dried, and then calcined at 400° C. for 3 h to obtain a MgO / g-C3N4 composite material; A2, adding 40g of MgO / g-C3N4 composite material to 520mL of ammonia water, heating and stirring at 70°C for 5h, centrifuging, washing and drying after the reaction to obtain an amino-modified MgO / g-C3N4 composite material; A3. Dissolve 10g of cerium nitrate hexahydrate, 10g of manganese nitrate hexahydrate and 7g of lanthanum nitrate hexahydrate in 140mL of deionized water, add 4g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; add 140g of anatase TiO2 (specific surface area 180m 2 / g), after being evenly dispersed, kept at 40 ° C for 3 h, dried, and calcined at 500 ° C for 3 h to obtain a cerium-manganese-lanthanum composite oxide / TiO2 composite material; A4, dispersing 120g of cerium manganese lanthanum composite oxide / TiO2 composite material in 1500mL of 2mol / L phosphoric acid solution, heating and stirring at 50°C for 3h, centrifuging, washing and drying to obtain phosphoric acid-modified cerium manganese lanthanum composite oxide / TiO2 composite material; A5. Disperse 88 g of phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in 450 mL of ethanol, add 28 g of amino-modified MgO / g-C3N4 composite material, stir ultrasonically for 3 h, centrifuge, wash, dry, and calcine at 550°C for 2 h to obtain a denitration catalyst.

[0034] Embodiment 4: A method for preparing a denitration catalyst comprises the following steps: A1. Ultrasonic dispersion of 90 g of the g-C3N4 nanosheets prepared in Example 1 in 9 L of ethanol, and then adding 10 g of magnesium nitrate hexahydrate, and continuing ultrasonic dispersion to obtain a mixed solution; the mixed solution was put into an agate mortar and ground for 40 min until it became a paste, and then dried, and then calcined at 400 ° C for 4 h to obtain a MgO / g-C3N4 composite material; A2, adding 60g of MgO / g-C3N4 composite material to 560mL of ammonia water, heating and stirring at 7°C for 7h, centrifuging, washing and drying after the reaction to obtain an amino-modified MgO / g-C3N4 composite material; A3. Dissolve 11g of cerium nitrate hexahydrate, 10g of manganese nitrate hexahydrate and 9g of lanthanum nitrate hexahydrate in 150mL of deionized water, add 6.5g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; add 143g of anatase TiO2 (specific surface area 180m 2 / g), after being evenly dispersed, kept at 40°C for 6h, dried, and calcined at 550°C for 5h to obtain a cerium-manganese-lanthanum composite oxide / TiO2 composite material; A4, dispersing 130g of cerium manganese lanthanum composite oxide / TiO2 composite material in 1600mL of 3mol / L phosphoric acid solution, heating and stirring at 60°C for 4h, centrifuging, washing and drying to obtain phosphoric acid-modified cerium manganese lanthanum composite oxide / TiO2 composite material; A5. Disperse 91 g of phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in 450 mL of ethanol, add 31 g of amino-modified MgO / g-C3N4 composite material, stir ultrasonically for 3 h, centrifuge, wash, dry, and calcine at 600°C for 2 h to obtain a denitration catalyst.

[0035] Embodiment 5: A method for preparing a denitration catalyst comprises the following steps: A1. Ultrasonic dispersion of 95 g of the g-C3N4 nanosheets prepared in Example 1 in 9 L of ethanol, and then adding 12 g of magnesium nitrate hexahydrate, and continuing ultrasonic dispersion to obtain a mixed solution; the mixed solution was put into an agate mortar and ground for 40 min until it became a paste, and then dried, and then calcined at 400 ° C for 5 h to obtain a MgO / g-C3N4 composite material; A2, adding 80g of MgO / g-C3N4 composite material to 600mL of ammonia water, heating and stirring at 90°C for 5h, centrifuging, washing and drying after the reaction to obtain an amino-modified MgO / g-C3N4 composite material; A3. Dissolve 15g of cerium nitrate hexahydrate, 7.5g of manganese nitrate hexahydrate and 10g of lanthanum nitrate hexahydrate in 165mL of deionized water, add 8g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; add 150g of anatase TiO2 (specific surface area 180m 2 / g), after being evenly dispersed, it was kept at 50 ° C for 4 hours, dried, and calcined at 600 ° C for 3 hours to obtain a cerium-manganese-lanthanum composite oxide / TiO2 composite material; A4, dispersing 160g of cerium manganese lanthanum composite oxide / TiO2 composite material in 1700mL of 5mol / L phosphoric acid solution, heating and stirring at 60°C for 3h, centrifuging, washing and drying to obtain phosphoric acid-modified cerium manganese lanthanum composite oxide / TiO2 composite material; A5. Disperse 96 g of phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in 500 mL of ethanol, add 24 g of amino-modified MgO / g-C3N4 composite material, stir ultrasonically for 3 h, centrifuge, wash, dry, and calcine at 650°C for 2 h to obtain a denitration catalyst.

[0036] Embodiment 6: A method for preparing a denitration catalyst comprises the following steps: A1. Ultrasonic dispersion of 100 g of the g-C3N4 nanosheets prepared in Example 1 in 10 L of ethanol, and then adding 15 g of magnesium nitrate hexahydrate, and continuing ultrasonic dispersion to obtain a mixed solution; the mixed solution was put into an agate mortar and ground for 50 min until it became a paste, and then dried, and then calcined at 500° C. for 5 h to obtain a MgO / g-C3N4 composite material; A2, adding 90g of MgO / g-C3N4 composite material to 600mL of ammonia water, heating and stirring at 90°C for 10h, centrifuging, washing and drying after the reaction to obtain an amino-modified MgO / g-C3N4 composite material; A3. Dissolve 15g of cerium nitrate hexahydrate, 15g of manganese nitrate hexahydrate and 12g of lanthanum nitrate hexahydrate in 220mL of deionized water, add 9g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; add 150g of anatase TiO2 (specific surface area 180m 2 / g), after being evenly dispersed, it was kept at 50°C for 8 hours, dried, and calcined at 600°C for 5 hours to obtain a cerium-manganese-lanthanum composite oxide / TiO2 composite material; A4, dispersing 160g of cerium manganese lanthanum composite oxide / TiO2 composite material in 1800mL of 5mol / L phosphoric acid solution, heating and stirring at 60°C for 5h, centrifuging, washing and drying to obtain phosphoric acid-modified cerium manganese lanthanum composite oxide / TiO2 composite material; A5. Disperse 96 g of phosphoric acid-modified cerium-manganese-lanthanum composite oxide / TiO2 composite material in 600 mL of ethanol, add 36 g of amino-modified MgO / g-C3N4 composite material, stir ultrasonically for 4 h, centrifuge, wash, dry, and calcine at 650°C for 3 h to obtain a denitration catalyst.

[0037] Comparative Example 1 Compared with Example 3, in Comparative Example 1, no amino-modified MgO / g-C3N4 composite material was added, 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: A1. Dissolve 10g of cerium nitrate hexahydrate, 10g of manganese nitrate hexahydrate, 2.9g of magnesium nitrate hexahydrate and 7g of lanthanum nitrate hexahydrate in 140mL of deionized water, then add 4g of citric acid and stir until completely dissolved to obtain a mixed metal salt solution; add 140g of anatase TiO2 (specific surface area 180m 2 / g), after being evenly dispersed, kept at 40 ° C for 3 h, dried, and calcined at 500 ° C for 3 h to obtain a cerium manganese magnesium lanthanum composite oxide / TiO2 composite material; A2. Disperse 120 g of cerium manganese magnesium lanthanum composite oxide / TiO2 composite material in 1500 mL of 2 mol / L phosphoric acid solution, heat and stir at 50°C for 3 h, then centrifuge, wash and dry to obtain a phosphoric acid-modified cerium manganese magnesium lanthanum composite oxide / TiO2 composite material, i.e., a denitrification catalyst.

[0038] Comparative Example 2 Compared with Example 3, no lanthanum nitrate hexahydrate was added during the preparation process of Comparative Example 2, and other steps and raw materials were the same as those of Example 3.

[0039] Comparative Example 3 Compared with Example 3, no cerium nitrate hexahydrate was added during the preparation process of Comparative Example 3, and other steps and raw materials were the same as those of Example 3.

[0040] Performance Testing (1) Denitrification catalytic activity test: simulated flue gas composition: NO: 1000ppm, NH3: 1000ppm, O2: 8%, N2 as balance gas, air velocity of 30000h -1 , the flue gas flow rate is 300mL / min, the same volume of catalyst is put into the fixed bed reactor for testing, the catalyst denitrification efficiency at different temperatures is tested, and the reaction temperature is controlled at 100 ~ 350℃. The results are shown in Table 1; (2) Test of water and sulfur resistance of denitrification catalyst: Simulated flue gas composition: NO: 1000ppm, NH3: 1000ppm, O2: 8%, H2O: 20%, SO2: 500ppm, N2 as balance gas, air velocity of 30000h -1 , the flue gas flow rate is 300mL / min, the same volume of catalyst is put into the fixed bed reactor for testing, the catalyst denitrification efficiency at different temperatures is tested, and the reaction temperature is controlled at 100 ~ 300℃. The results are shown in Table 2; (3) Denitrification catalyst stability test: simulated flue gas composition: NO: 1000ppm, NH3: 1000ppm, O2: 8%, H2O: 20%, SO2: 500ppm, N2 as the balance gas, air velocity of 30000h -1 , the flue gas flow rate is 300mL / min, the same volume of catalyst is put into the fixed bed reactor for testing, the catalyst denitrification efficiency is tested for 120h, the reaction temperature is controlled at 150℃, and the results are shown in Table 3; Table 1

[0041] Table 2

[0042] Table 3

[0043] It can be seen from the data of Tables 1, 2 and 3 that the denitration catalyst prepared by the present invention has excellent denitration catalytic activity, water-sulfur resistance and stability. It can be seen from the data of Comparative Example 3 and Comparative Example 1 that due to the absence of amino-modified MgO / g-C3N4 composite material, and the magnesium oxide is loaded on the carrier TiO2, the alkaline active center and the pickling active center are loaded on the same carrier, resulting in a significant decrease in denitration catalytic activity, water-sulfur resistance and stability. It can be seen from the data of Comparative Example 3 and Comparative Examples 2 and 3 that the denitration catalytic activity, water-sulfur resistance and stability are decreased without the addition of lanthanum nitrate hexahydrate or cerium nitrate hexahydrate.

[0044] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0045] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall 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 the 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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