A red mud-based denitration catalyst, a preparation method and application thereof

Abstract

The application provides a red mud-based denitration catalyst and a preparation method and application thereof. The preparation method of the red mud-based denitration catalyst comprises the following steps: (1) stirring and mixing Bayer red mud powder and nitric acid, then performing solid-liquid separation, washing and drying the obtained solid to obtain acidified red mud; (2) stirring and mixing biochar and nitric acid, then performing solid-liquid separation, washing and drying the obtained solid to obtain acidified biochar; (3) grinding and mixing the acidified red mud and the acidified biochar; under an inert atmosphere, the obtained mixture is heated to 400-500 DEG C at a rate of 2-5 DEG C, and is calcined at 400-500 DEG C for 2-5 h to obtain the catalyst. The preparation method of the denitration catalyst is simple, and the denitration catalyst can maintain a high denitration effect in a wide temperature range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nitrogen oxide control, solid waste recycling and catalysis technology, in particular to a red mud-based denitration catalyst and its preparation method and application. BACKGROUND

[0002] Nitrogen oxides are one of the main sources of air pollution, which mainly comes from combustion processes, especially the combustion of fossil fuels, such as vehicle engine emissions, power plant emissions, industrial boilers and other high-temperature combustion equipment. Controlling nitrogen oxide emissions is an important measure to improve air quality and reduce environmental impact. Common methods include improving combustion efficiency, using catalytic reduction technology (such as SCR catalysts), and developing clean energy technology, etc.

[0003] NH3-SCR is a widely used technology to reduce nitrogen oxide emissions, which is mainly applied in the fields of power plant, industrial boiler and motor vehicle exhaust treatment, etc. Its principle is that ammonia reacts with nitrogen oxides (mainly NO, NO2) in a suitable temperature condition and catalyst environment, and is reduced to nitrogen. The denitration effect of this technology mainly depends on the performance of the denitration catalyst. Vanadium-based catalyst (V2O5-WO3 / TiO2) is the mainstream denitration catalyst widely used at present, which can work efficiently at a temperature range of 300-400 °C, has good resistance to sulfur and water, and is widely used in power plants and large industrial boilers. However, vanadium-based catalyst has poor high-temperature stability, is prone to volatilization of vanadium, and is easily deactivated at high temperatures, resulting in a decrease in denitration effect. In addition, V2O5 has biological toxicity, which may have an impact on the environment and health. Therefore, it is of great significance to develop new denitration catalysts.

[0004] Red mud is a solid waste generated in the production process of alumina industry, mainly composed of iron oxide, aluminum oxide, silicon dioxide and some other metal oxides. Due to its rich metal oxide composition, large specific surface area and good adsorption performance, red mud usually contains a large amount of iron oxide, which is an effective active component and can participate in the reduction reaction of nitrogen oxides. Iron oxide-based catalysts show good denitration activity at low and medium temperatures. In recent years, some studies have begun to explore its application in the field of environmental governance, including the preparation of denitration catalysts. At present, the process of preparing denitration catalysts using red mud is as follows: first, use acid (such as nitric acid, hydrochloric acid, etc.) to pretreat red mud to remove impurities, and then load other metals (such as vanadium, tungsten, copper, etc.) on the surface of red mud by impregnation method, coprecipitation method or hydrothermal method to further improve its catalytic performance. However, these methods have complex preparation process, high cost and long time-consuming problems. SUMMARY

[0005] In view of the problems in the prior art, the application provides a red mud-based denitration catalyst as well as a preparation method and application thereof, the red mud-based denitration catalyst is prepared from red mud and biochar as raw materials, the preparation method is simple, and the red mud-based denitration catalyst can maintain high denitration effect in a wide temperature range.

[0006] The application is achieved by the following technical solutions.

[0007] The application provides a preparation method of a red mud-based denitration catalyst, and the preparation method comprises the following steps.

[0008] (1) Bayer red mud powder is stirred and mixed with nitric acid, then solid-liquid separation is performed, the obtained solid is washed and dried to obtain acidified red mud;

[0009] (2) Biochar is stirred and mixed with nitric acid, then solid-liquid separation is performed, the obtained solid is washed and dried to obtain acidified biochar;

[0010] (3) The acidified red mud and the acidified biochar are ground and mixed; the obtained mixture is heated to 400-500 DEG C at a rate of 2-5 DEG C under an inert atmosphere, and is calcined at 400-500 DEG C for 2-5 h to obtain the catalyst.

[0011] Preferably, in step (1), the stirring speed is 600-800 r / min.

[0012] Preferably, in step (2), the stirring speed is 500-600 r / min.

[0013] Preferably, in step (2), the biochar is at least one of almond shell biochar, coconut shell biochar, apricot shell biochar and walnut shell biochar.

[0014] Preferably, in step (2), the particle size of the acidified biochar is 40-60 meshes.

[0015] Preferably, in step (3), the mass ratio of the acidified red mud to the acidified biochar is (5-7):(3-5).

[0016] Preferably, in step (3), the inert atmosphere is nitrogen, helium or argon.

[0017] Preferably, in step (3), after calcination, the mixture is ground and sieved to 60-80 meshes to obtain the catalyst.

[0018] The application further provides a red mud-based denitration catalyst prepared by the preparation method.

[0019] The application further provides application of the red mud-based denitration catalyst in catalytic denitration.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] The present application adopts the Bayer process red mud and biochar as the main components, and prepares the catalyst through acidification, grinding mixing and calcination. The present application adopts the grinding mixing method to mix the Bayer process red mud and biochar, which can better retain the metal oxides (such as iron oxide) and other components in the red mud compared with the ultrasonic dispersion method, avoids the ultrasonic dispersion from removing the metal oxides in the red mud, and thus provides the catalytic activity of the material. The present application limits the temperature, the temperature rising rate and the time during the calcination of the red mud and biochar mixture, which can promote the crystal phase transformation of the red mud components to form a catalyst with high crystallinity, helps to ensure uniform temperature distribution, avoids the structure unevenness caused by local overheating, and avoids the problems of excessive sintering or insufficient phase transformation of the catalyst caused by excessively high temperature (> 500℃) or excessively low temperature (< 400℃). Compared with the sintered red mud, the Bayer process red mud contains less impurities, has smaller and more uniform particles, can provide a larger specific surface area, is beneficial to the adsorption and reaction of the reactants, has more diverse chemical components, and can provide more active components for the catalyst. The surface of the biochar contains rich functional groups (such as carboxyl, hydroxyl, phenolic hydroxyl, etc.) which can provide active sites for the catalyst and improve the dispersibility of the catalyst. The pore structure of the biochar can complement the particles of the red mud, increase the overall specific surface area of the catalyst, promote the diffusion and adsorption of the reaction gas, and thus increase the contact opportunities between the nitrogen oxides and the active sites of the catalyst. The components such as alumina contained in the red mud have good thermal stability, which can maintain the structural integrity of the catalyst under high temperature conditions, and the addition of biochar can further improve the sintering resistance of the catalyst and prolong its service life. Therefore, the synergistic effect between the acidified red mud and the acidified biochar not only improves the pore structure of the catalyst, but also makes the catalyst have good denitration effect. The NO conversion rate of the catalyst prepared by the present application is more than 90% under the conditions of space velocity 23000 h-1, 250~400℃, and the catalyst has a long service life. The preparation method of the present application is simple, the raw material cost is low, the cumbersome process of loading metal is avoided, and the environmental pollution can be effectively reduced. The resource utilization of the red mud and the biochar is not only beneficial to environmental protection, but also can reduce the production cost of the denitration catalyst. Therefore, the catalyst of the present application has good application prospect in the field of nitrogen oxide control. -1 BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor.

[0023] ​Figure 1 is a SEM image of the catalyst obtained in Example 1 of the present application.

[0024] Figure 2 is a XRD spectrum of the catalyst obtained in Example 1 of the present application. DETAILED DESCRIPTION

[0025] Following, the embodiments of the present application will be described through specific, concrete examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present specification. The present application can also be implemented or applied through other different specific embodiments, and each detail in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present application.

[0026] It should be noted that the process equipment or device not specifically mentioned in the following examples is the conventional equipment or device in the art.

[0027] It should be noted that the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not a limitation on the arrangement order of each method step or a limitation on the scope of the implementation of the present application, and the change or adjustment of the relative relationship, without substantial change of the technical content, is also regarded as the scope of the implementation of the present application.

[0028] The preparation method of the red mud-based denitration catalyst described in the present application comprises the following steps:

[0029] (1) stirring and mixing the Bayer process red mud powder with nitric acid, then solid-liquid separation, washing and drying the obtained solid to obtain acidified red mud;

[0030] (2) stirring and mixing the biochar with nitric acid, then solid-liquid separation, washing and drying the obtained solid, and then grinding and sieving to 40-60 meshes to obtain acidified biochar;

[0031] (3) grinding and mixing the acidified red mud and the acidified biochar; under an inert atmosphere, the obtained mixture is heated at a rate of 2-5 ℃ to 400-500 ℃, and calcined at 400-500 ℃ for 2-5 h, and then ground and sieved to 60-80 meshes to obtain the catalyst.

[0032] In the above method of the present application, in step (1), the stirring speed is 600-800 r / min, and in step (2), the stirring speed is 500-600 r / min.

[0033] The biochar is at least one of almond shell biochar, coconut shell biochar, apricot shell biochar and walnut shell biochar.

[0034] The mass ratio of the acidified red mud and the acidified biochar is (5-7):(3-5). The inert atmosphere is nitrogen, helium or argon.

[0035] Example 1, preparation of a red mud biochar denitration catalyst.

[0036] First step, pretreatment of the Bayer process red mud using nitric acid: mix the Bayer process red mud powder and 1 mol / L nitric acid at a solid-liquid ratio of 1:8, stir at room temperature at a speed of 625 r / min for 5 min, then stir in a water bath at 80 ℃ for 60 min, keep the stirring speed at 625 r / min, then perform suction filtration, wash the red mud with deionized water until the pH of the filtrate reaches 7.0, and finally dry the washed red mud in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0037] Second step, pretreatment of almond shell biochar using nitric acid: mix the almond shell biochar and 0.5 mol / L nitric acid at a solid-liquid ratio of 1:5, stir at room temperature at a speed of 500 r / min for 3 h, then perform suction filtration, wash the biochar with deionized water until the pH of the filtrate reaches 7.0, and finally dry the washed biochar in an oven (90 ℃) for 24 h, then grind and sieve to 40-60 mesh to obtain acidified almond shell biochar, marked as ABC.

[0038] Third step, mix the ARM obtained in the first step and the ABC obtained in the second step at a mass ratio of 5:5, grind and mix uniformly, place the mixture in a tube furnace and calcine at 450 ℃ under a nitrogen atmosphere for 2 h, the temperature rising rate is 2 ℃ / min, after calcination, grind and sieve to 60-80 mesh to obtain a red mud biochar denitration catalyst, marked as R5B5-450(2).

[0039] Example 2, preparation of a red mud biochar denitration catalyst.

[0040] First step, pretreatment of the Bayer process red mud using nitric acid: mix the Bayer process red mud powder and 1 mol / L nitric acid at a solid-liquid ratio of 1:8, stir at room temperature at a speed of 625 r / min for 5 min, then stir in a water bath at 80 ℃ for 60 min, keep the stirring speed at 625 r / min, then perform suction filtration, wash the red mud with deionized water until the pH of the filtrate reaches 7.0, and finally dry the washed red mud in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0041] Second step, using nitric acid to pretreat almond shell biochar, mixing almond shell biochar and 0.5 mol / L nitric acid according to the solid-liquid ratio of 1:5, stirring at room temperature at a speed of 500 r / min for 3 h, then performing suction filtration, washing the biochar with deionized water until the pH of the filtrate reaches 7.0, finally drying the washed biochar in an oven (90 ℃) for 24 h, then grinding and sieving to 40-60 mesh to obtain acidified almond shell biochar, marked as ABC.

[0042] Third step, grinding and uniformly mixing the ARM obtained in the first step and the ABC obtained in the second step according to a mass ratio of 7:3, placing the mixture in a tube furnace and calcining under a nitrogen atmosphere at 450 ℃ for 2 h at a heating rate of 2 ℃ / min, grinding and sieving to 60-80 mesh after calcination, obtaining a red mud biochar denitrification catalyst, marked as R7B3-450(2).

[0043] Example 3, preparation of a red mud biochar denitrification catalyst.

[0044] First step, using nitric acid to pretreat Bayer process red mud, mixing Bayer process red mud powder and 1 mol / L nitric acid according to a solid-liquid ratio of 1:8, stirring at room temperature at a speed of 625 r / min for 5 min, then stirring in a 80 ℃ water bath for 60 min at a speed of 625 r / min, then performing suction filtration, washing the red mud with deionized water until the pH of the filtrate reaches 7.0, finally drying the washed red mud in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0045] Second step, using nitric acid to pretreat almond shell biochar, mixing almond shell biochar and 0.5 mol / L nitric acid according to the solid-liquid ratio of 1:5, stirring at room temperature at a speed of 500 r / min for 3 h, then performing suction filtration, washing the biochar with deionized water until the pH of the filtrate reaches 7.0, finally drying the washed biochar in an oven (90 ℃) for 24 h, then grinding and sieving to 40-60 mesh to obtain acidified almond shell biochar, marked as ABC.

[0046] Third step, grinding and uniformly mixing the ARM obtained in the first step and the ABC obtained in the second step according to a mass ratio of 5:5, placing the mixture in a tube furnace and calcining under a nitrogen atmosphere at 400 ℃ for 2 h at a heating rate of 2 ℃ / min, grinding and sieving to 60-80 mesh after calcination, obtaining a red mud biochar denitrification catalyst, marked as R5B5-400(2).

[0047] Example 4, preparation of a red mud biochar denitrification catalyst.

[0048] First step, the Bayer red mud was pretreated by nitric acid, the Bayer red mud powder and 1 mol / L nitric acid were mixed according to the solid-liquid ratio of 1:8, stirred at room temperature at a speed of 625 r / min for 5 min, then stirred in a water bath at 80 ℃ for 60 min, the speed was kept at 625 r / min, then suction filtration was carried out, the red mud was washed with deionized water until the pH of the filtrate reached 7.0, finally the washed red mud was dried in an oven (90 ℃) for 24 h, and acidified red mud was obtained, marked as ARM.

[0049] Second step, almond shell biochar was pretreated by nitric acid, almond shell biochar and 0.5 mol / L nitric acid were mixed according to the solid-liquid ratio of 1:5, stirred at room temperature at a speed of 500 r / min for 3 h, then suction filtration was carried out, the biochar was washed with deionized water until the pH of the filtrate reached 7.0, finally the washed biochar was dried in an oven (90 ℃) for 24 h, then ground and sieved to 40-60 mesh, and acidified almond shell biochar was obtained, marked as ABC.

[0050] Third step, the ARM obtained in the first step and the ABC obtained in the second step were mixed uniformly according to the mass ratio of 5:5, and the mixture was placed in a tube furnace and calcined at 500 ℃ under nitrogen atmosphere for 2 h, the heating rate was 2 ℃ / min, after calcination, the mixture was ground and sieved to 60-80 mesh, and a red mud biochar denitration catalyst was obtained, marked as R5B5-500(2).

[0051] Example 5, preparation of a red mud biochar denitration catalyst.

[0052] First step, the Bayer red mud was pretreated by nitric acid, the Bayer red mud powder and 1 mol / L nitric acid were mixed according to the solid-liquid ratio of 1:8, stirred at room temperature at a speed of 625 r / min for 5 min, then stirred in a water bath at 80 ℃ for 60 min, the speed was kept at 625 r / min, then suction filtration was carried out, the red mud was washed with deionized water until the pH of the filtrate reached 7.0, finally the washed red mud was dried in an oven (90 ℃) for 24 h, and acidified red mud was obtained, marked as ARM.

[0053] Second step, almond shell biochar was pretreated by nitric acid, almond shell biochar and 0.5 mol / L nitric acid were mixed according to the solid-liquid ratio of 1:5, stirred at room temperature at a speed of 500 r / min for 3 h, then suction filtration was carried out, the biochar was washed with deionized water until the pH of the filtrate reached 7.0, finally the washed biochar was dried in an oven (90 ℃) for 24 h, then ground and sieved to 40-60 mesh, and acidified almond shell biochar was obtained, marked as ABC.

[0054] Third step, the ARM obtained in the first step and the ABC obtained in the second step were mixed uniformly according to a mass ratio of 5:5, and the mixture was placed in a tube furnace and calcined at 450 ℃ under a nitrogen atmosphere for 2 h at a heating rate of 5 ℃ / min. After calcination, the mixture was ground and sieved to 60-80 meshes, to obtain a red mud biochar denitration catalyst, marked as R5B5-450(5).

[0055] Comparative Example 1

[0056] Bayer process red mud powder and 1 mol / L nitric acid were mixed according to a solid-liquid ratio of 1:8, stirred at room temperature at a speed of 625 r / min for 5 min, then stirred in a water bath at 80 ℃ for 60 min at a speed of 625 r / min, then suction filtered, and the red mud was washed with deionized water until the pH of the filtrate reached 7.0. Finally, the washed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0057] Comparative Example 2

[0058] First step, the Bayer process red mud was pretreated using nitric acid: the Bayer process red mud powder and 1 mol / L nitric acid were mixed according to a solid-liquid ratio of 1:8, stirred at room temperature at a speed of 625 r / min for 5 min, then stirred in a water bath at 80 ℃ for 60 min at a speed of 625 r / min, then suction filtered, and the red mud was washed with deionized water until the pH of the filtrate reached 7.0. Finally, the washed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0059] Second step, the ARM was placed in a tube furnace and calcined at 450 ℃ under a nitrogen atmosphere for 2 h at a heating rate of 2 ℃ / min. After calcination, the mixture was ground and sieved to 60-80 meshes to obtain a red mud denitration catalyst, marked as ARM-450(2).

[0060] Comparative Example 3

[0061] First step, the Bayer process red mud was pretreated using nitric acid: the Bayer process red mud powder and 1 mol / L nitric acid were mixed according to a solid-liquid ratio of 1:8, stirred at room temperature at a speed of 625 r / min for 5 min, then stirred in a water bath at 80 ℃ for 60 min at a speed of 625 r / min, then suction filtered, and the red mud was washed with deionized water until the pH of the filtrate reached 7.0. Finally, the washed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0062] Second step, using nitric acid to pretreat almond shell biochar: almond shell biochar and 0.5 mol / L nitric acid are mixed according to a solid-liquid ratio of 1:5, stirring at a speed of 500 r / min at room temperature for 3 h, then suction filtration, washing the biochar with deionized water until the filtrate pH reaches 7.0, finally drying the washed biochar in an oven (90 DEG C) for 24 h, then grinding to 40-60 mesh, obtaining acidified almond shell biochar, marked as ABC.

[0063] Third step, grinding and mixing the ARM obtained in the first step and the ABC obtained in the second step uniformly according to a mass ratio of 5:5, placing the mixture in a tube furnace and calcining under a nitrogen atmosphere at 300 DEG C for 2 h, the temperature rising rate is 2 DEG C / min, after calcination, grinding to 60-80 mesh, obtaining a red mud denitration catalyst, marked as R5B5-300(2).

[0064] Comparative example 4

[0065] First step, using nitric acid to pretreat the Bayer process red mud: mixing the Bayer process red mud powder and 1 mol / L nitric acid according to a solid-liquid ratio of 1:8, stirring at a speed of 625 r / min at room temperature for 5 min, then stirring in a 80 DEG C water bath for 60 min, the stirring speed is kept at 625 r / min, then suction filtration, washing the red mud with deionized water until the filtrate pH reaches 7.0, finally drying the washed red mud in an oven (90 DEG C) for 24 h, obtaining acidified red mud, marked as ARM.

[0066] Second step, using nitric acid to pretreat almond shell biochar: almond shell biochar and 0.5 mol / L nitric acid are mixed according to a solid-liquid ratio of 1:5, stirring at a speed of 500 r / min at room temperature for 3 h, then suction filtration, washing the biochar with deionized water until the filtrate pH reaches 7.0, finally drying the washed biochar in an oven (90 DEG C) for 24 h, then grinding to 40-60 mesh, obtaining acidified almond shell biochar, marked as ABC.

[0067] Third step, grinding and mixing the ARM obtained in the first step and the ABC obtained in the second step uniformly according to a mass ratio of 5:5, placing the mixture in a tube furnace and calcining under a nitrogen atmosphere at 450 DEG C for 2 h, the temperature rising rate is 8 DEG C / min, after calcination, grinding to 60-80 mesh, obtaining a red mud denitration catalyst, marked as R5B5-450(8).

[0068] The SEM image of the denitration catalyst R5B5-450(2) obtained in example 1 of the present application is shown in Figure 1 the Figure 1It can be seen that the surface of R5B5-450(2) is distributed with a large number of hole structures, and a large number of small-particle metal oxide particles are attached to the hole surface.

[0069] The XRD spectrum of the denitration catalyst R5B5-450(2) obtained in Example 1 of the present application is shown in Figure 1. Figure 2 It can be seen that R5B5-450(2) has a strong hematite crystal phase and small crystal grains.

[0070] The denitration effect tests were performed on the catalysts obtained in Examples 1-5 and Comparative Examples 1-4 and the original red mud. The test conditions were as follows: 500 ppm NO, 500 ppm NH3, 5%vol O2, N2 as the balance gas, gas flow rate 50 mL / min, gas hourly space velocity (GHSV) 23000 h-1, and the test temperature range was 200-400 ℃. The test results are shown in Table 1. -1

[0071] Table 1: Denitration of the catalysts obtained in the examples

[0072]

[0073] As can be seen from the above table, the denitration effect of the denitration catalyst prepared in the examples of the present application is obviously better than that of the acidified red mud ARM series and the original red mud of the comparative examples. Among them, the catalyst R5B5-450(2) of Example 1, the catalyst R5B5-400(2) of Example 3 and the catalyst R7B3-450(2) of Example 2 have a NO conversion rate of more than 90% in the range of 250-400 ℃. This shows that compared with the original red mud and the acidified red mud ARM series, the denitration catalyst prepared by mixing red mud and biochar has higher denitration activity. The calcination temperature and the heating rate also have a great influence on the denitration performance of the catalyst. The catalytic activity of the catalyst R5B5-450(2) of Example 1 is better than that of the catalyst R5B5-400(2) of Example 3, the catalyst R5B5-500(2) of Example 4 and the catalyst R5B5-300(2) of Comparative Example 3, which shows that too low calcination temperature (300 ℃) will lead to the failure of the catalyst to form the required active phase, and a higher temperature (500 ℃) can cause the catalyst to sinter, reduce the specific surface area and active sites, and reduce its catalytic activity. 450 ℃ can generally promote the catalyst to form the required active phase without excessive sintering, thereby maintaining good catalytic activity. The catalytic activity of the catalyst R5B5-450(2) of Example 1 is better than that of the catalyst R5B5-450(8) of Comparative Example 4, which shows that a slower heating rate (2 ℃ / min) is helpful for uniform heating and structural stability of the catalyst, avoiding local overheating and uneven phase transformation, and a too fast heating rate (more than 5 ℃ / min) can lead to insufficient or uneven phase transformation, affecting the activity of the catalyst.

[0074] ​The above merely describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a red mud-based denitration catalyst, characterized in that, The method comprises the following steps: (1) stirring and mixing the Bayer process red mud powder with nitric acid, then separating the solid and liquid, washing and drying the obtained solid to obtain acidified red mud; (2) stirring and mixing the biochar with nitric acid, then separating the solid and liquid, washing and drying the obtained solid to obtain acidified biochar; (3) grinding and mixing the acidified red mud and the acidified biochar; In an inert atmosphere, the obtained mixture is heated to 400-500 ℃ at a rate of 2-5 ℃, and calcined at 400-500 ℃ for 2-5 h to obtain the catalyst.

2. The method for preparing the red mud-based denitrification catalyst according to claim 1, characterized in that, In step (1), the stirring speed is 600-800 r / min.

3. The method of claim 1, wherein the red mud-based denitration catalyst is prepared by the steps of: In step (2), the stirring speed is 500-600 r / min. ​ 4. The method for preparing the red mud-based denitrification catalyst according to claim 1, characterized in that, In step (2), the biochar is at least one of almond shell biochar, coconut shell biochar, apricot shell biochar and walnut shell biochar.

5. The method for preparing the red mud-based denitrification catalyst according to claim 1, characterized in that, In step (2), the particle size of the acidified biochar is 40-60 mesh.

6. The method for preparing the red mud-based denitrification catalyst according to claim 1, characterized in that, In step (3), the mass ratio of the acidified red mud to the acidified biochar is (5-7):(3-5).

7. The method for preparing the red mud-based denitrification catalyst according to claim 1, characterized in that, In step (3), the inert atmosphere is nitrogen, helium or argon.

8. The method for preparing the red mud-based denitrification catalyst according to claim 1, characterized in that, In step (3), after calcination, the mixture is ground and sieved to 60-80 mesh to obtain the catalyst.

9. A red mud-based denitration catalyst prepared by the method of any one of claims 1-8.

10. The use of the red mud-based denitration catalyst of claim 9 in catalytic denitration.

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