Red mud-based denitration catalyst as well as preparation method and application thereof

Abstract

The invention 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 that 1, Bayer process red mud powder and nitric acid are stirred and mixed, then solid-liquid separation is conducted, obtained solids are washed and dried, and acidified red mud is obtained; (2) stirring and mixing the biochar and nitric acid, then carrying out solid-liquid separation, and washing and drying the obtained solid to obtain acidified biochar; (3) grinding and mixing the acidified red mud and the acidified biochar; and heating the obtained mixture to 400-500 DEG C at a rate of 2-5 DEG C in an inert atmosphere environment, and roasting at 400-500 DEG C for 2-5 hours 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 invention relates to the fields of nitrogen oxide control, solid waste recycling and catalytic technology, and in particular to a red mud-based denitration catalyst and a preparation method and application thereof. Background Art

[0002] Nitrogen oxides are one of the main sources of air pollution, which mainly come from the combustion process, 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 impacts. Common methods include improving combustion efficiency, using catalytic reduction technology (such as SCR catalysts), and developing clean energy technologies.

[0003] NH 3 -SCR is a technology widely used to reduce nitrogen oxide emissions. This technology is mainly used in power plants, industrial boilers and motor vehicle exhaust treatment. Its principle is that ammonia reacts with nitrogen oxides (mainly NO, NO 2 ) reaction, reducing it to nitrogen. The denitrification effect of this technology mainly depends on the performance of the denitrification catalyst. Vanadium-based catalysts (V 2 O 5 -WO 3 / TiO 2 ) is the mainstream denitrification catalyst widely used at present. It can work efficiently in the temperature range of 300-400 ° C, has good sulfur and water resistance, and is widely used in power plants and large industrial boilers. However, vanadium-based catalysts have poor high-temperature stability, are prone to vanadium volatilization, and are easily deactivated at high temperatures, resulting in a decrease in denitrification effect. In addition, V 2 O 5 It is biologically toxic and may have an impact on the environment and health. Therefore, the development of new denitrification catalysts is of great significance.

[0004] Red mud is a solid waste generated during the production of alumina industry. Its main components include iron oxide, aluminum oxide, silicon dioxide and some other metal oxides. Red mud is rich in metal oxide components, as well as has a large specific surface area and good adsorption properties. Red mud usually contains a large amount of iron oxide, which is an effective active component that can participate in the reduction reaction of nitrogen oxides. Iron oxide-based catalysts show good denitrification activity under low and medium temperature conditions. In recent years, some studies have begun to explore its application in the field of environmental governance, including its use in the preparation of denitrification catalysts. The current process of using red mud to prepare denitrification catalysts is as follows: first, the red mud is pretreated with acid (such as nitric acid, hydrochloric acid, etc.) to remove impurities, and then other metals (such as vanadium, tungsten, copper, etc.) are loaded on the surface of the red mud by impregnation, coprecipitation or hydrothermal method to further improve its catalytic performance. However, these methods have complicated preparation processes, and have problems such as high cost and long time consumption. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a red mud-based denitrification catalyst and a preparation method and application thereof. The denitrification catalyst is prepared using red mud and biochar as raw materials. The preparation method is simple and can maintain a high denitrification effect within a wide temperature range.

[0006] The present invention is achieved through the following technical solutions: The present invention provides a method for preparing a red mud-based denitration catalyst, comprising the following steps: (1) mixing the Bayer process red mud powder with nitric acid, and then separating the solid and liquid. The obtained solid is washed and dried to obtain acidified red mud; (2) mixing the biochar with nitric acid, and then separating the solid and the liquid, and washing and drying the obtained solid to obtain the acidified biochar; (3) Grinding and mixing the acidified red mud and the acidified biochar; heating the resulting mixture to 400-500°C at a rate of 2-5°C in an inert atmosphere, and calcining at 400-500°C for 2-5 h to obtain the catalyst. Preferably, in step (1), the stirring speed is 600-800 r / min.

[0007] Preferably, in step (2), the stirring speed is 500-600 r / min.

[0008] Preferably, in step (2), the biochar is at least one of almond shell biochar, coconut shell biochar, apricot shell biochar and walnut shell biochar.

[0009] Preferably, in step (2), the particle size of the acidified biochar is 40-60 mesh.

[0010] Preferably, in step (3), the mass ratio of acidified red mud to acidified biochar is (5-7):(3-5).

[0011] Preferably, in step (3), the inert atmosphere is nitrogen, helium or argon.

[0012] Preferably, in step (3), after calcination, the catalyst is ground and sieved to 60-80 mesh to obtain the catalyst.

[0013] The present invention also provides a red mud-based denitration catalyst obtained by the preparation method as described above.

[0014] The present invention also provides application of the red mud-based denitration catalyst in catalytic denitration.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses Bayer red mud and biochar as main components, and prepares the catalyst by acidification, grinding, mixing and roasting. The present invention uses grinding and mixing to mix Bayer red mud and biochar. Compared with the ultrasonic dispersion method, it can better retain the metal oxides (such as iron oxide) and other components in the red mud, avoid ultrasonic dispersion to remove the metal oxides of the red mud, thereby providing the catalytic activity of the material. The present invention limits the temperature, heating rate and time when the red mud and biochar mixture is roasted. Under the temperature, heating rate and time of the present invention, the crystal phase transformation of the red mud component can be promoted to form a higher crystallinity of the catalyst, which helps to ensure uniform temperature distribution, avoid structural unevenness caused by local overheating, and avoid excessive sintering or insufficient phase change of the catalyst due to excessively high (>500°C) or too low (<400°C) temperature. Compared with sintered red mud, Bayer red mud contains fewer impurities, smaller and more evenly distributed particles, can provide a larger specific surface area, is conducive to the adsorption and reaction of reactants, has more diverse chemical components, and can provide more active components for the catalyst. The surface of biochar contains abundant functional groups (such as carboxyl, hydroxyl, phenolic hydroxyl, etc.), which can provide active sites for the catalyst and improve the dispersion of the catalyst. The pore structure of biochar can complement the particles of 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 opportunity between nitrogen oxides and the active sites of the catalyst. The components such as alumina contained in red mud have good thermal stability and can maintain the structural integrity of the catalyst under high temperature conditions. The addition of biochar may further improve the catalyst's anti-sintering ability and extend its service life. Therefore, the synergistic effect between acidified red mud and acidified biochar not only improves the pore structure of the catalyst, giving it a good denitrification effect, but also improves the denitrification effect at an air velocity of 23000 h -1, within the range of 250-400°C, the NO conversion rate exceeds 90%. The preparation method of the present invention is simple, the raw material cost is low, the cumbersome process of loading metals is avoided, and environmental pollution can be effectively reduced. The resource utilization of red mud and biochar is not only beneficial to environmental protection, but also can reduce the production cost of denitration catalysts. Therefore, the catalyst of the present invention has good application prospects in the field of nitrogen oxide control. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a SEM image of the catalyst obtained in Example 1 of the present invention.

[0018] Figure 2 It is the XRD spectrum of the catalyst obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0020] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0021] It should be noted that the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are 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 intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0022] The method for preparing the red mud-based denitration catalyst of the present invention comprises the following steps: (1) mixing the Bayer process red mud powder with nitric acid, and then separating the solid and liquid. The obtained solid is washed and dried to obtain acidified red mud; (2) mixing the biochar with nitric acid, and then separating the solid and the liquid. The obtained solid is washed, dried, and then ground and sieved to 40-60 mesh to obtain acidified biochar. (3) Grinding and mixing the acidified red mud and the acidified biochar; heating the resulting mixture to 400-500°C at a rate of 2-5°C in an inert atmosphere, calcining the mixture at 400-500°C for 2-5 h, and grinding and sieving the mixture to 60-80 mesh after calcination to obtain the catalyst. In the above method of the present invention, in step (1), the stirring speed is 600-800 r / min, and in step (2), the stirring speed is 500-600 r / min.

[0023] The biochar described in the present invention is at least one of almond shell biochar, coconut shell biochar, apricot shell biochar and walnut shell biochar.

[0024] The mass ratio of the acidified red mud to the acidified biochar in the present invention is (5-7): (3-5). The inert atmosphere is nitrogen, helium or argon.

[0025] Example 1, preparation of red mud biochar denitrification catalyst.

[0026] In the first step, the Bayer process red mud was pretreated with nitric acid: the Bayer process red mud powder and 1 mol / L nitric acid were mixed in a solid-liquid ratio of 1:8, stirred at 625 r / min for 5 min at room temperature, then stirred in an 80 ℃ water bath for 60 min, with the speed maintained at 625 r / min, and then filtered. The red mud was rinsed with deionized water until the pH of the filtrate reached 7.0, and finally the rinsed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0027] In the second step, the almond shell biochar was pretreated with nitric acid: the almond shell biochar and 0.5 mol / L nitric acid were mixed at a solid-liquid ratio of 1:5, stirred at 500 r / min at room temperature for 3 h, then filtered, and the biochar was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed biochar was dried in an oven (90 °C) for 24 h, and then ground and sieved to 40-60 mesh to obtain acidified almond shell biochar, marked as ABC.

[0028] In the third step, the ARM obtained in the first step and the ABC obtained in the second step were ground and mixed in a mass ratio of 5:5. The mixture was placed in a tubular furnace and calcined at 450 °C for 2 h in a nitrogen atmosphere with a heating rate of 2 °C / min. After calcination, the mixture was ground and sieved to 60-80 mesh to obtain a red mud biochar denitrification catalyst, which was labeled R5B5-450(2).

[0029] Example 2, preparation of red mud biochar denitrification catalyst.

[0030] In the first step, nitric acid was used to pretreat the Bayer process red mud. The Bayer process red mud powder and 1 mol / L nitric acid were mixed in a solid-liquid ratio of 1:8, stirred at 625 r / min for 5 min at room temperature, then stirred in an 80 ℃ water bath for 60 min, and the speed was maintained at 625 r / min. Then, it was filtered and the red mud was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, which was marked as ARM.

[0031] In the second step, the almond shell biochar was pretreated with nitric acid. The almond shell biochar and 0.5 mol / L nitric acid were mixed in a solid-liquid ratio of 1:5, stirred at 500 r / min at room temperature for 3 h, and then filtered. The biochar was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed biochar was dried in an oven (90 °C) for 24 h, and then ground and sieved to 40-60 mesh to obtain acidified almond shell biochar, marked as ABC.

[0032] In the third step, the ARM obtained in the first step and the ABC obtained in the second step were ground and mixed in a mass ratio of 7:3. The mixture was placed in a tubular furnace and calcined at 450 °C for 2 h in a nitrogen atmosphere with a heating rate of 2 °C / min. After calcination, the mixture was ground and sieved to 60-80 mesh to obtain a red mud biochar denitrification catalyst, which was labeled R7B3-450(2).

[0033] Example 3, preparation of red mud biochar denitrification catalyst.

[0034] In the first step, nitric acid was used to pretreat the Bayer process red mud. The Bayer process red mud powder and 1 mol / L nitric acid were mixed in a solid-liquid ratio of 1:8, stirred at 625 r / min for 5 min at room temperature, then stirred in an 80 ℃ water bath for 60 min, and the speed was maintained at 625 r / min. Then, it was filtered and the red mud was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, which was marked as ARM.

[0035] In the second step, the almond shell biochar was pretreated with nitric acid. The almond shell biochar and 0.5 mol / L nitric acid were mixed in a solid-liquid ratio of 1:5, stirred at 500 r / min at room temperature for 3 h, and then filtered. The biochar was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed biochar was dried in an oven (90 °C) for 24 h, and then ground and sieved to 40-60 mesh to obtain acidified almond shell biochar, marked as ABC.

[0036] In the third step, the ARM obtained in the first step and the ABC obtained in the second step were ground and mixed in a mass ratio of 5:5, and the mixture was placed in a tubular furnace and calcined at 400 °C for 2 h in a nitrogen atmosphere with a heating rate of 2 °C / min. After the calcination, the mixture was ground and sieved to 60-80 mesh to obtain a red mud biochar denitrification catalyst, which was labeled R5B5-400(2).

[0037] Example 4, preparation of red mud biochar denitrification catalyst.

[0038] In the first step, nitric acid was used to pretreat the Bayer process red mud. The Bayer process red mud powder and 1 mol / L nitric acid were mixed in a solid-liquid ratio of 1:8, stirred at 625 r / min for 5 min at room temperature, then stirred in an 80 ℃ water bath for 60 min, and the speed was maintained at 625 r / min. Then, it was filtered and the red mud was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, which was marked as ARM.

[0039] In the second step, the almond shell biochar was pretreated with nitric acid. The almond shell biochar and 0.5 mol / L nitric acid were mixed in a solid-liquid ratio of 1:5, stirred at 500 r / min at room temperature for 3 h, and then filtered. The biochar was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed biochar was dried in an oven (90 °C) for 24 h, and then ground and sieved to 40-60 mesh to obtain acidified almond shell biochar, marked as ABC.

[0040] In the third step, the ARM obtained in the first step and the ABC obtained in the second step were ground and mixed in a mass ratio of 5:5, and the mixture was placed in a tubular furnace and calcined at 500 °C for 2 h in a nitrogen atmosphere with a heating rate of 2 °C / min. After the calcination, the mixture was ground and sieved to 60-80 mesh to obtain a red mud biochar denitrification catalyst, which was labeled R5B5-500(2).

[0041] Example 5, preparation of red mud biochar denitrification catalyst.

[0042] In the first step, nitric acid was used to pretreat the Bayer process red mud. The Bayer process red mud powder and 1 mol / L nitric acid were mixed in a solid-liquid ratio of 1:8, stirred at 625 r / min for 5 min at room temperature, then stirred in an 80 ℃ water bath for 60 min, and the speed was maintained at 625 r / min. Then, it was filtered and the red mud was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, which was marked as ARM.

[0043] In the second step, the almond shell biochar was pretreated with nitric acid. The almond shell biochar and 0.5 mol / L nitric acid were mixed in a solid-liquid ratio of 1:5, stirred at 500 r / min at room temperature for 3 h, and then filtered. The biochar was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed biochar was dried in an oven (90 °C) for 24 h, and then ground and sieved to 40-60 mesh to obtain acidified almond shell biochar, marked as ABC.

[0044] In the third step, the ARM obtained in the first step and the ABC obtained in the second step were ground and mixed in a mass ratio of 5:5. The mixture was placed in a tubular furnace and calcined at 450 °C for 2 h in a nitrogen atmosphere with a heating rate of 5 °C / min. After calcination, the mixture was ground and sieved to 60-80 mesh to obtain a red mud biochar denitrification catalyst, which was labeled R5B5-450(5).

[0045] Comparative Example 1 Bayer red mud powder and 1 mol / L nitric acid were mixed in a solid-liquid ratio of 1:8, stirred at 625 r / min for 5 min at room temperature, then stirred in an 80 ℃ water bath for 60 min with the speed maintained at 625 r / min, then filtered, and the red mud was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0046] Comparative Example 2 In the first step, the Bayer process red mud was pretreated with nitric acid: the Bayer process red mud powder and 1 mol / L nitric acid were mixed in a solid-liquid ratio of 1:8, stirred at 625 r / min for 5 min at room temperature, then stirred in an 80 ℃ water bath for 60 min, with the speed maintained at 625 r / min, and then filtered. The red mud was rinsed with deionized water until the pH of the filtrate reached 7.0, and finally the rinsed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0047] In the second step, ARM was placed in a tubular furnace and calcined at 450 °C for 2 h in a nitrogen atmosphere with a heating rate of 2 °C / min. After calcination, it was ground and sieved to 60-80 mesh to obtain a red mud denitrification catalyst, which was labeled ARM-450(2).

[0048] Comparative Example 3 In the first step, the Bayer process red mud was pretreated with nitric acid: the Bayer process red mud powder and 1 mol / L nitric acid were mixed in a solid-liquid ratio of 1:8, stirred at 625 r / min for 5 min at room temperature, then stirred in an 80 ℃ water bath for 60 min, with the speed maintained at 625 r / min, and then filtered. The red mud was rinsed with deionized water until the pH of the filtrate reached 7.0, and finally the rinsed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0049] In the second step, the almond shell biochar was pretreated with nitric acid: the almond shell biochar and 0.5 mol / L nitric acid were mixed at a solid-liquid ratio of 1:5, stirred at 500 r / min at room temperature for 3 h, then filtered, and the biochar was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed biochar was dried in an oven (90 °C) for 24 h, and then ground and sieved to 40-60 mesh to obtain acidified almond shell biochar, marked as ABC.

[0050] In the third step, the ARM obtained in the first step and the ABC obtained in the second step were ground and mixed in a mass ratio of 5:5, and the mixture was placed in a tubular furnace and calcined at 300 °C for 2 h in a nitrogen atmosphere with a heating rate of 2 °C / min. After the calcination, the mixture was ground and sieved to 60-80 mesh to obtain a red mud denitrification catalyst, which was marked as R5B5-300(2).

[0051] Comparative Example 4 In the first step, the Bayer process red mud was pretreated with nitric acid: the Bayer process red mud powder and 1 mol / L nitric acid were mixed in a solid-liquid ratio of 1:8, stirred at 625 r / min for 5 min at room temperature, then stirred in an 80 ℃ water bath for 60 min, with the speed maintained at 625 r / min, and then filtered. The red mud was rinsed with deionized water until the pH of the filtrate reached 7.0, and finally the rinsed red mud was dried in an oven (90 ℃) for 24 h to obtain acidified red mud, marked as ARM.

[0052] In the second step, the almond shell biochar was pretreated with nitric acid: the almond shell biochar and 0.5 mol / L nitric acid were mixed at a solid-liquid ratio of 1:5, stirred at 500 r / min at room temperature for 3 h, then filtered, and the biochar was rinsed with deionized water until the pH of the filtrate reached 7.0. Finally, the rinsed biochar was dried in an oven (90 °C) for 24 h, and then ground and sieved to 40-60 mesh to obtain acidified almond shell biochar, marked as ABC.

[0053] In the third step, the ARM obtained in the first step and the ABC obtained in the second step were ground and mixed in a mass ratio of 5:5. The mixture was placed in a tubular furnace and calcined at 450 °C for 2 h in a nitrogen atmosphere with a heating rate of 8 °C / min. After calcination, the mixture was ground and sieved to 60-80 mesh to obtain a red mud denitrification catalyst, which was labeled R5B5-450(8).

[0054] The SEM image of the denitration catalyst R5B5-450 (2) obtained in Example 1 of the present invention is as follows: Figure 1 As shown, from Figure 1 It can be seen that there are a large number of pore structures distributed on the surface of R5B5-450(2), and a large number of small-sized metal oxide particles are attached to the surface of the pores.

[0055] The XRD spectrum of the denitration catalyst R5B5-450 (2) obtained in Example 1 of the present invention is as follows: Figure 2 It can be seen that R5B5-450(2) has a stronger hematite crystal phase and smaller grains.

[0056] The catalysts obtained in Examples 1-5 and Comparative Examples 1-4 and the original red mud were tested for denitrification effects under the following test conditions: 500 ppm NO, 500 ppm NH 3 , 5%vol O 2 , N 2 The gas flow rate was 50 mL / min and the space velocity (GHSV) was 23000 h -1 , the test temperature range is 200-400 ℃. The test results are shown in Table 1.

[0057] Table 1 Denitration of catalysts obtained in various examples

[0058] As can be seen from the above table, the denitration effect of the denitration catalyst prepared in the embodiment of the present invention is significantly better than that of the acidified red mud ARM series and the original red mud in the comparative example. 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 ° C. 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 a 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, indicating that when the calcination temperature is too low (300°C), the catalyst will fail to form the required active phase, and a higher temperature (500°C) may cause the catalyst to sinter, reduce the specific surface area and active sites, and reduce its catalytic activity. 450°C can usually 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, indicating that a slower heating rate (2°C / min) helps to uniformly heat the catalyst and stabilize the structure, avoid local overheating and uneven phase change, and a too fast heating rate (greater than 5°C / min) may cause insufficient or uneven phase change, affecting the activity of the catalyst.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a red mud-based denitrification catalyst, It is characterized in that The following steps are involved: (1) mixing the Bayer process red mud powder with nitric acid, and then separating the solid and liquid. The obtained solid is washed and dried to obtain acidified red mud. (2) mixing the biochar with nitric acid, and then separating the solid and the liquid, and washing and drying the obtained solid to obtain the 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° C. at a rate of 2-5° C., and calcined at 400-500° C. for 2-5 h to obtain the catalyst.

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

3. The method for preparing the red mud-based denitration catalyst according to claim 1, It is characterized in that In step (2), the stirring speed is 500-600 r / min.

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

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

8. The method for preparing the red mud-based denitration catalyst according to claim 1, It is 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 obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the red mud-based denitrification catalyst according to claim 9 in catalytic denitrification.

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