A monodisperse sub-micron core-shell structure low-temperature rare earth-based denitration catalyst, a preparation method and application thereof

Abstract

The application discloses a kind of monodisperse sub-micron core-shell structure low-temperature rare earth-based denitration catalyst and its preparation method and application, the catalyst is with monodisperse ferroferric oxide wrapping silver as inner core, with cerium dioxide and manganese oxide composite oxide as active component outer layer, vanadium oxide is used as catalyst, polyacrylic acid is used as in-situ generation agent, sodium sulfite is used as light reducing agent, oxalic acid is used as morphology control agent, and is prepared by in-situ reduction-high temperature hydrothermal-impregnation load combined method;With inner core mass as reference, the mass percentage content of active component outer layer is 5-10%, and the mass percentage content of catalyst is 1-5%.The catalyst synthesized by the method has the advantages of large specific surface area, sufficient active site exposure, etc., and can realize the nitrogen oxide ultra-low emission target of low-temperature flue gas working condition in waste incineration industry.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method and application of a monodisperse sub-micron core-shell structure low-temperature rare earth-based denitration catalyst, and belongs to the field of industrial flue gas purification. BACKGROUND

[0002] With the acceleration of urbanization, the output of household garbage is increasing year by year, and the traditional landfill and stacking method gradually cannot meet the environmental protection requirements. Waste incineration has gradually become one of the main methods of modern urban solid waste treatment. Although waste incineration can effectively reduce the volume of garbage and save land resources, this process is also accompanied by certain environmental pollution risks, especially air pollution. During the waste incineration process, atmospheric pollutants represented by nitrogen oxides (NO x ) will be discharged, which can cause acid rain and ozone pollution, seriously affecting human health and ecological safety.

[0003] In order to address this challenge, many countries and regions have developed strict waste incineration emission standards to strive to minimize the pollutant emissions of the waste incineration industry. At present, the main treatment technology for NO x is the selective catalytic reduction method (SCR method), which has achieved relatively good application in the thermal power industry. However, in the face of the working condition that the flue gas temperature in the waste incineration process is usually lower than 300 DEG C, the catalytic efficiency of the SCR catalyst under low-temperature conditions is difficult to achieve the standard emission of waste incineration flue gas pollutants.

[0004] In order to effectively control NO x in the waste incineration industry, it is urgent to develop a denitration catalyst that can work efficiently at a relatively low temperature (lower than 300 DEG C). Therefore, the research and development of a low-temperature denitration catalyst with high activity is one of the important directions of the research on flue gas purification in the waste incineration industry. SUMMARY

[0005] The purpose of the present application is to solve the problem of low catalytic activity of the existing low-temperature denitration catalyst for waste incineration industry flue gas, and a preparation method and application of a monodisperse sub-micron core-shell structure low-temperature rare earth-based denitration catalyst are proposed.

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

[0007] The single-dispersion sub-micron core-shell structure low-temperature rare earth-based denitration catalyst is prepared by in-situ reduction-high temperature hydrothermal-impregnation loading combined method, and has a single-dispersion ferroferric oxide wrapped silver as an inner core, a composite oxide of cerium dioxide and manganese oxide as an outer layer of active component, vanadium oxide as a catalyst promoter, polyacrylic acid as an in-situ generated agent, sodium sulfite as a light reducing agent, and oxalic acid as a morphology control agent; the mass percentage of the outer layer of active component is 1-10% based on the mass of the inner core, the mass percentage of the catalyst promoter is 1-10%, the mass ratio of cerium dioxide to manganese oxide in the active component is 1:(0.1-5), and the mass ratio of ferroferric oxide to silver in the inner core is 1:(0.1-1).

[0008] As a preferred technical solution, in the single-dispersion sub-micron core-shell structure low-temperature rare earth-based denitration catalyst, the mass percentage of the outer layer of active component is 5-10% based on the mass of the inner core, the mass percentage of the catalyst promoter is 1-5%, the mass ratio of cerium dioxide to manganese oxide in the active component is 1:(0.5-2), and the mass ratio of ferroferric oxide to silver in the inner core is 1:(0.1-0.2).

[0009] A preparation method of the above catalyst is as follows:

[0010] (1) In-situ reduction-high temperature hydrothermal method for preparing ferroferric oxide wrapped silver inner core

[0011] The paper is immersed in a polyacrylic acid solution, taken out, dried at low temperature, and then used; then the paper adsorbed with polyacrylic acid is immersed in a silver salt solution, dried at low temperature again, and then placed in a sodium borohydride solution for reaction; after the reaction, the powder obtained after baking for the first time is washed to obtain single-dispersion nanosilver particles;

[0012] The single-dispersion nanosilver particles, iron salt, sodium sulfite, oxalic acid, and deionized water are uniformly mixed, and then placed in a hydrothermal reactor for high-temperature hydrothermal reaction; after the reaction, the mixture is filtered, dried, and baked for the second time to obtain the ferroferric oxide wrapped silver inner core;

[0013] (2) Impregnation loading method for preparing the catalyst

[0014] The cerium salt, manganese salt, vanadium salt, and deionized water are mixed to obtain a composite precursor solution; then the ferroferric oxide wrapped silver inner core prepared in step (1) is placed in the composite precursor solution, dried at low temperature, and then baked at high temperature to obtain the single-dispersion sub-micron core-shell structure low-temperature rare earth-based denitration catalyst.

[0015] In the above preparation method, the concentration of the polyacrylic acid solution in step (1) is 1-10 wt%; the concentration of the silver salt solution is 1-15 wt%; and the concentration of the sodium borohydride solution is 1-10 wt%;

[0016] Preferably, the concentration of the polyacrylic acid solution is 2-6 wt%; the concentration of the silver salt solution is 5-10 wt%; and the concentration of the sodium borohydride solution is 1-5 wt%.

[0017] In the preparation method, the reaction time in step (1) is 30-60 min; the temperature for low-temperature drying is 25-35 DEG C, and the low-temperature drying time is 20-24 h.

[0018] In the preparation method, the drying temperature in step (1) is 50-60 DEG C, the drying time is 2-4 h, the temperature for first-time calcination is 500-600 DEG C, and the first-time calcination time is 2-3 h.

[0019] In the preparation method, the temperature for high-temperature hydrothermal reaction in step (1) is 140-160 DEG C, the high-temperature hydrothermal reaction time is 3-6 h; the drying temperature is 80-100 DEG C, and the drying time is 3-6 h; the temperature for second-time calcination is 400-500 DEG C, and the second-time calcination time is 2-4 h.

[0020] In the preparation method, the cerium salt in step (2) is cerium nitrate hexahydrate or cerium chloride, the manganese salt is manganese nitrate hexahydrate or manganese chloride, and the vanadium salt is ammonium metavanadate; the temperature for low-temperature drying is 30-40 DEG C, the low-temperature drying time is 24-48 h; the temperature for high-temperature calcination is 500-600 DEG C, and the high-temperature calcination time is 2-4 h.

[0021] In the technical scheme, the catalyst is applied to low-temperature denitration in the waste incineration industry.

[0022] In the technical scheme, further, polyacrylic acid and deionized water are mixed to prepare a polyacrylic acid solution, then paper is immersed in the polyacrylic acid solution, taken out, and dried at low temperature for standby; then silver salt and deionized water are mixed to prepare a silver salt solution, and the paper adsorbed with polyacrylic acid is immersed in the silver salt solution, dried at low temperature, and placed in a sodium borohydride solution for reaction, dried after the reaction, and placed in a muffle furnace for high-temperature calcination; then the obtained powder after calcination is placed in a dilute hydrochloric acid solution and a sodium hydroxide solution for acid washing and alkali washing, respectively, and then washed with deionized water to obtain monodisperse nano silver particles; the monodisperse nano silver particles, iron salt, sodium sulfite, oxalic acid, and deionized water are mixed to prepare a mixture, and then the mixture is placed in a hydrothermal reaction kettle for high-temperature hydrothermal reaction, filtered and dried after the reaction, and calcined again to obtain a silver core wrapped with magnetite; the dilute hydrochloric acid solution is a hydrochloric acid solution with a mass fraction of 5-10%, the sodium hydroxide solution is a sodium hydroxide solution with a mass fraction of 10-20%, and the mass ratio of the dilute hydrochloric acid solution / sodium hydroxide solution to the obtained powder after calcination is 1:(30-40).

[0023] The catalyst activity evaluation experiment condition of the present application: 1 mL of catalyst with 20-40 meshes is poured into a quartz tube with an inner diameter of 6 mm, fixed with quartz wool and iron wire, and placed in a tube furnace, and the actual temperature of the catalytic reaction is adjusted by controlling the heating temperature of the tube furnace. The gas composition: NO (500 ppm), NH3 (500 ppm), O2 (11 vol.%), H2O (5 vol.%), and the rest is N2, the total gas flow is 500 mL / min, the control temperature is 90-300 DEG C, each 30 DEG C stays stable for 30 min, the NO concentration is measured by Laoying 3021 type portable carbon emission monitor, and the denitration efficiency of the catalyst is higher than 90% in the temperature range of 180-300 DEG C.

[0024] Beneficial effects:

[0025] (1) The present application uses polyacrylic acid to pretreat A4 paper, which not only makes the surface of the A4 paper have more carboxyl groups, but also reduces the size of the limited structure formed by the fiber intersection, thereby facilitating the adsorption and fixation of the silver salt solution, and then using sodium borohydride solution to reduce the silver salt solution in situ, thereby preparing monodisperse nano silver particles, then using calcination, acid washing and alkali washing to remove the paper to obtain high-purity monodisperse nano silver particles, and finally using the hydrothermal reaction of the nano silver particles and the iron salt to generate a sub-micron core coated with silver nanoparticles, wherein sodium sulfite is used to reduce the iron salt, and oxalic acid is used as a morphology control agent to make the ferric oxide stably grow and coat the nano silver particles;

[0026] (2) The present application uses cerium oxide, manganese oxide and vanadium oxide as active components and catalysts, which have excellent redox performance, can guarantee excellent low-temperature reduction activity of the catalyst, and the silver and ferric oxide in the core not only have good electron transport performance to promote the improvement of activity, but also can be easily recycled by using the magnetism of the ferric oxide when the catalyst is blown by ash in the actual engineering, thereby guaranteeing that the catalyst is not easy to form secondary pollution.

[0027] Therefore, the prepared catalyst not only has excellent low-temperature flue gas denitration performance, but also has the advantages of environmental friendliness, simple preparation process, low cost, high cost performance and strong application promotion value. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 TEM image of the catalyst prepared in Example 1;

[0029] Figure 2 TEM image of the catalyst prepared in Comparative Example 1;

[0030] Figure 3 NO removal performance diagram of the catalyst prepared in Examples 1-3 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0031] The application will be further described in conjunction with the following examples, which are implemented on the premise of the technical solutions of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following examples.

[0032] Example 1

[0033] (1) Preparation of Fe3O4-coated silver core by in-situ reduction-high temperature hydrothermal method

[0034] 1g of polyacrylic acid, 20g of deionized water were mixed uniformly to prepare a polyacrylic acid solution, then 70g of paper was immersed in the polyacrylic acid solution and taken out, dried at a low temperature of 30℃ for 24h and reserved; 1g of silver nitrate, 10g of deionized water were mixed uniformly to prepare a silver salt solution, and the paper adsorbed with polyacrylic acid was immersed in the silver salt solution and dried at a low temperature of 30℃ for 24h and reserved; 1g of sodium borohydride was dissolved in 30ml of deionized water to prepare a sodium borohydride solution, and the paper adsorbed with silver salt was placed in the solution for reaction for 30min, after the reaction was completed, the paper was dried at 50℃ for 2h and then placed in a muffle furnace for high-temperature calcination at 500℃ for 2h, then the powder obtained after calcination was sequentially placed in 30g of 5% dilute hydrochloric acid solution and 30g of 10% sodium hydroxide solution for acid washing and alkali washing, and then washed with deionized water to obtain monodisperse silver nanoparticles; 0.5g of monodisperse silver nanoparticles, 26.17g of iron nitrate nonahydrate, 0.25g of sodium sulfite, 1.5g of oxalic acid and 20ml of deionized water were mixed uniformly, and then placed in a hydrothermal reaction kettle for high-temperature hydrothermal reaction at 140℃ for 3h, after the reaction was completed, the product was filtered, dried at 80℃ for 3h and then calcined at 400℃ for 2h to obtain Fe3O4-coated silver core;

[0035] (2) Preparation of catalyst by impregnation loading method

[0036] 0.084g of cerium nitrate hexahydrate, 0.055g of manganese nitrate hexahydrate, 0.013g of ammonium metavanadate and 2.6ml of deionized water were mixed uniformly to prepare a composite precursor solution, then 1g of Fe3O4-coated silver core prepared in step (1) was placed in the composite precursor solution, dried at a low temperature of 30℃ for 24h and then calcined at a high temperature of 500℃ for 2h to obtain monodisperse sub-micron core-shell structure low-temperature rare earth-based denitration catalyst;

[0037] The mass percentage content of the outer layer of active components was 5% based on the mass of the core, the mass percentage content of the catalyst was 1%, and the mass ratio of cerium dioxide and manganese oxide in the active components was 1:0.5, and the mass ratio of Fe3O4 and silver in the core was 1:0.1;

[0038] (3) Catalytic activity test

[0039] Take 20-40 mesh catalyst 1 mL, pour into the inner diameter of 6 mm quartz tube, with quartz wool and iron wire fixed, the quartz tube is placed in the tube furnace, by controlling the heating temperature of the tube furnace to adjust the actual temperature of the catalytic reaction. The gas composition: NO (500 ppm), NH3 (500 ppm), O2 (11 vol.%), the rest is N2, the total flow of the gas is 500 mL / min, the temperature is controlled at 90-300℃, each 30℃ stays stable for 30 min, the NO concentration is measured by Laoying 3021 type portable carbon emission monitor, the catalyst denitration efficiency in the temperature range of 150-300℃ is higher than 90%.

[0040] Example 2

[0041] (1) In-situ reduction-high temperature hydrothermal method for preparing four-iron oxide coated silver core

[0042] Mix 1g polyacrylic acid and 30g deionized water to prepare a polyacrylic acid solution, then immerse 75g paper in the polyacrylic acid solution, take it out, dry it at low temperature of 40℃ for 36h, and reserve it for use; then mix 1g silver nitrate and 15g deionized water to prepare a silver salt solution, immerse the paper adsorbed with polyacrylic acid in the silver salt solution, and dry it at low temperature of 40℃ for 36h for use; dissolve 1g sodium borohydride in 40ml deionized water to prepare a sodium borohydride solution, and place the paper adsorbed with silver salt in it for reaction for 45min, after the reaction, dry it at 55℃ for 3h, place it in a muffle furnace for high temperature calcination at 550℃ for 2.5h, then place the obtained powder in 35g 8% mass fraction hydrochloric acid solution and 35g 15% mass fraction sodium hydroxide solution for acid washing and alkali washing, and then clean it with deionized water to obtain monodisperse silver nanoparticles; mix 0.7g monodisperse silver nanoparticles, 12.26g iron chloride hexahydrate, 0.5g sodium sulfite, 2.8g oxalic acid and 35ml deionized water, then place them in a hydrothermal reactor for high temperature hydrothermal reaction at 150℃ for 4.5h, after the reaction, filter and dry at 90℃ for 5h, and then calcine at 450℃ for 3h to obtain four-iron oxide coated silver core;

[0043] (2) Preparation of catalyst by impregnation loading method

[0044] Weigh 0.051g cerium chloride, 0.050g manganese chloride, 0.039g ammonium metavanadate, and 2.04ml deionized water to prepare a composite precursor solution, then place 1g of the four-iron oxide coated silver core prepared in step (1) in the composite precursor solution, dry it at low temperature of 30℃ for 36h, and then calcine it at high temperature of 500℃ for 3h to obtain a monodisperse sub-micron core-shell structure low-temperature rare earth-based denitration catalyst;

[0045] The mass percentage of the active component outer layer is 7%, the mass percentage of the co-catalyst is 3%, the mass ratio of cerium dioxide and manganese oxide in the active component is 1:1, and the mass ratio of ferroferric oxide and silver in the core is 1:0.15;

[0046] (3) Catalyst activity test

[0047] Take 20-40 mesh catalyst 1 mL, pour into a quartz tube with an inner diameter of 6 mm, fix with quartz wool and iron wire, place the quartz tube in a tube furnace, adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. The gas composition is: NO (500 ppm), NH3 (500 ppm), O2 (11 vol.%), and the rest is N2, the total gas flow is 500 mL / min, the control temperature is 90-300℃, and each 30℃ stays stable for 30 min. The NO concentration is measured by Laoying 3021 portable carbon emission monitor. The denitration efficiency of the catalyst is higher than 90% in the temperature range of 150-300℃.

[0048] Example 3

[0049] (1) Preparation of ferroferric oxide coated silver core by in-situ reduction-high temperature hydrothermal method

[0050] Mix 1 g of polyacrylic acid and 30 g of deionized water to prepare a polyacrylic acid solution, then immerse 80 g of paper in the polyacrylic acid solution, take it out, and dry it at a low temperature of 40℃ for 48 h for standby; then mix 1 g of silver nitrate and 20 g of deionized water to prepare a silver salt solution, and immerse the paper adsorbed with polyacrylic acid in the silver salt solution and dry it at a low temperature of 40℃ for 48 h for standby; dissolve 1 g of sodium borohydride in 50 ml of deionized water to prepare a sodium borohydride solution, and place the paper adsorbed with silver salt in it for reaction for 60 min, then dry it at 60℃ for 4 h, and then place it in a muffle furnace for calcination at a high temperature of 600℃ for 3 h, then place the calcined powder in 40 g of 10% dilute hydrochloric acid solution and 40 g of 20% sodium hydroxide solution for acid washing and alkali washing, respectively, and then clean it with deionized water to obtain monodisperse silver nanoparticles; mix 0.5 g of monodisperse silver nanoparticles, 13.1 g of iron nitrate nonahydrate, 0.5 g of sodium sulfite, 2.5 g of oxalic acid, and 30 ml of deionized water, then place them in a hydrothermal reaction kettle for hydrothermal reaction at a high temperature of 140℃ for 3 h, filter and dry at 80℃ for 3 h, and then calcine at 400℃ for 2 h to obtain a ferroferric oxide coated silver core;

[0051] (2) Preparation of catalyst by impregnation loading method

[0052] 0.085g of cerium nitrate hexahydrate, 0.22g of manganese nitrate hexahydrate, 0.065g of ammonium metavanadate, and 4.25ml of deionized water are mixed to obtain a composite precursor solution, and then 1g of the silver core coated with the ferric oxide prepared in step (1) is placed in the composite precursor solution, dried at 30°C for 24h, and then calcined at 500°C for 2h to obtain a low-temperature rare earth-based denitration catalyst with a monodisperse sub-micron core-shell structure;

[0053] The mass percentage of the outer layer of the active component is 10% based on the mass of the core, the mass percentage of the promoter is 5%, and the mass ratio of cerium dioxide to manganese oxide in the active component is 1:2, and the mass ratio of ferric oxide to silver in the core is 1:0.2;

[0054] (3) Catalytic activity test

[0055] 1ml of the catalyst with a mesh size of 20-40 is poured into a quartz tube with an inner diameter of 6mm, fixed with quartz wool and iron wire, and placed in a tube furnace, and the actual temperature of the catalytic reaction is adjusted by controlling the heating temperature of the tube furnace. The gas components are: NO (500ppm), NH3 (500ppm), O2 (11vol.%), and the rest is N2, with a total gas flow of 500ml / min. The control temperature is 90-300°C, and each temperature stays stable for 30min. The NO concentration is measured by Laoying 3021 portable carbon emission monitor. The denitration efficiency of the catalyst is higher than 90% in the temperature range of 150-300°C.

[0056] Comparative Example 1

[0057] (1) In-situ reduction-high temperature hydrothermal method for preparing ferric oxide coated silver core

[0058] Except that no A4 paper is added in the process of preparing the ferric oxide coated silver core, the other conditions are the same as in Example 1.

[0059] (2) Catalytic activity test

[0060] 1ml of the catalyst with a mesh size of 20-40 is poured into a quartz tube with an inner diameter of 6mm, fixed with quartz wool and iron wire, and placed in a tube furnace, and the actual temperature of the catalytic reaction is adjusted by controlling the heating temperature of the tube furnace. The gas components are: NO (500ppm), NH3 (500ppm), O2 (11vol.%), and the rest is N2, with a total gas flow of 500ml / min. The control temperature is 90-300°C, and each temperature stays stable for 30min. The NO concentration is measured by Laoying 3021 portable carbon emission monitor. The denitration efficiency of the catalyst is higher than 90% in the temperature range of 150-300°C.

[0061] (3) Comparison effect

[0062] Compared to Example 1, A4 paper was not added in catalyst preparation step (1), and the silver salt was not adsorbed and fixed in the paper fibers. During sodium borohydride reduction, it agglomerated, resulting in the formation of monodisperse submicron particles when the ferric oxide was hydrothermally coated onto the silver particles. Therefore, the catalyst prepared in this case was agglomerated granular. Figure 2 Therefore, the active sites of the prepared catalyst are greatly reduced, resulting in a decrease in the catalyst's low-temperature catalytic activity.

[0063] Comparative Example 2

[0064] (1) Preparation of silver core coated with iron oxide by in-situ reduction-high temperature hydrothermal method

[0065] Except that oxalic acid was not added during the preparation of the silver core coated with iron oxide, the other conditions were the same as in Example 2; (2) Catalytic activity test

[0066] Take 1 mL of 20-40 mesh catalyst and pour it into a quartz tube with an inner diameter of 6 mm. Fix it with quartz wool and wire mesh. Place the quartz tube in a tube furnace and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. Inlet gas components: NO (500 ppm), NH3 (500 ppm), O2 (11 vol.%), and the remainder is N2. The total gas flow rate is 500 mL / min. The temperature is controlled between 90 and 300℃, and the temperature is maintained at 30℃ for 30 min. The NO concentration is measured using a Laoying 3021 portable carbon emission monitor. The denitrification efficiency at 150℃ is 39.8%.

[0067] (3) Comparison effect

[0068] Compared with Example 1, oxalic acid, a morphology control agent, was not added in catalyst preparation step (1). Therefore, the monodisperse silver nanoparticles and iron salts could not completely form a core-shell structure with iron oxide encapsulating silver as the core during the hydrothermal reaction. Under the condition of uneven morphology distribution, the loaded active components were uneven, which led to a decrease in the low-temperature catalytic activity of the catalyst.

Claims

1. A monodisperse submicron core-shell structured low-temperature rare-earth-based denitration catalyst, characterized in that: The catalyst has monodisperse ferroferric oxide wrapped silver as the inner core, a composite oxide of cerium dioxide and manganese oxide as the outer layer of active component, vanadium oxide as the cocatalyst, polyacrylic acid as the in-situ generated agent, sodium sulfite as the light reducing agent, and oxalic acid as the morphology control agent, and is prepared by an in-situ reduction-high temperature hydrothermal-impregnation loading combined method; the mass percentage content of the outer layer of active component is 1-10% based on the mass of the inner core, the mass percentage content of the cocatalyst is 1-10%, the mass ratio of cerium dioxide to manganese oxide in the active component is 1:(0.1-5), and the mass ratio of ferroferric oxide to silver in the inner core is 1:(0.1-1).

2. The monodisperse sub-micron core-shell structure low-temperature rare earth-based de-NOx catalyst according to claim 1, characterized in that: The mass percentage content of the outer layer of active component is 5-10% based on the mass of the inner core, the mass percentage content of the cocatalyst is 1-5%, the mass ratio of cerium dioxide to manganese oxide in the active component is 1:(0.5-2), and the mass ratio of ferroferric oxide to silver in the inner core is 1:(0.1-0.2).

3. A method for preparing the monodisperse sub-micron core-shell structure low-temperature rare earth-based denitration catalyst according to claim 1, characterized in that: The catalyst is prepared by the following method: (1) Preparation of ferroferric oxide wrapped silver inner core by in-situ reduction-high temperature hydrothermal method The paper is immersed in a polyacrylic acid solution, taken out, dried at low temperature, and then used; the paper adsorbed with polyacrylic acid is immersed in a silver salt solution, dried at low temperature again, and then placed in a sodium borohydride solution for reaction; after the reaction, the powder obtained after baking for the first time is washed to obtain monodisperse nano silver particles; The monodisperse nano silver particles, iron salt, sodium sulfite, oxalic acid, and deionized water are uniformly mixed, and then placed in a hydrothermal reaction kettle for high temperature hydrothermal reaction; after the reaction, the mixture is filtered, dried, and baked for the second time to obtain the ferroferric oxide wrapped silver inner core; (2) Preparation of the catalyst by impregnation loading method The cerium salt, manganese salt, vanadium salt, and deionized water are uniformly mixed to prepare a composite precursor solution; the ferroferric oxide wrapped silver inner core prepared in step (1) is placed in the composite precursor solution, dried at low temperature, and then baked at high temperature to obtain the monodisperse submicron core-shell structure low-temperature rare earth-based denitration catalyst.

4. The method of claim 3, wherein: In step (1), the concentration of the polyacrylic acid solution is 1-10 wt%; the concentration of the silver salt solution is 1-15 wt%; and the concentration of the sodium borohydride solution is 1-10 wt%.

5. The method of claim 4, wherein In step (1), the concentration of the polyacrylic acid solution is 2-6 wt%; the concentration of the silver salt solution is 5-10 wt%; and the concentration of the sodium borohydride solution is 1-5 wt%.

6. The method of claim 3, wherein: In step (1), the reaction time is 30-60 min; the low-temperature drying temperature is 25-35℃, and the low-temperature drying time is 20-24 h.

7. The method of claim 3, wherein: In step (1), the drying temperature is 50-60℃, the drying time is 2-4 h, the first baking temperature is 500-600℃, and the first baking time is 2-3 h.

8. The method of claim 3, wherein: In step (1), the high-temperature hydrothermal reaction temperature is 140-160℃, the high-temperature hydrothermal reaction time is 3-6 h; the drying temperature is 80-100℃, the drying time is 3-6 h; the second baking temperature is 400-500℃, and the second baking time is 2-4 h.

9. The method of claim 3, wherein: The cerium salt in step (2) is cerium nitrate hexahydrate or cerium chloride, the manganese salt is manganese nitrate hexahydrate or manganese chloride, and the vanadium salt is ammonium metavanadate; the temperature of low-temperature drying is 30-40 DEG C, the time of low-temperature drying is 24-48 h; the temperature of high-temperature calcination is 500-600 DEG C, and the time of high-temperature calcination is 2-4 h.

10. The use of the monodisperse sub-micron core-shell structure low-temperature rare earth-based denitration catalyst of claim 1 in the low-temperature denitration of waste incineration industry.

Images