Method for regenerating desulfurization and denitrification catalyst based on red mud
By combining physical crushing method and water washing method, the desulfurization and denitrification catalyst made of red mud produced by Bayer's alumina production process is regenerated, which solves the problem of low catalyst regeneration efficiency in the prior art, and achieves efficient catalyst regeneration and environmentally friendly use effects.
Patent Information
- Application Number
- CN202510319625.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2025-06-20
AI Technical Summary
There is a lack of effective methods in the prior art to regenerate the desulfurization and denitrification catalyst made of red mud produced by the Bayer method for producing alumina, resulting in low catalyst utilization efficiency and serious environmental pollution.
The catalyst regeneration is carried out by combining physical crushing and water washing. The specific steps include crushing the failed catalyst to less than 100 mesh, then mixing it with water in a certain proportion, stirring and washing it, granulating it after suction filtration and drying, and obtaining a first-stage regenerated catalyst.
Through this method, the regeneration efficiency and service life of the catalyst can be significantly improved, the cost of use and environmental pressure can be reduced, and the desulfurization and denitrification efficiency of the catalyst can be maintained above 90%.
Smart Images
Figure CN120169446A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of catalyst regeneration, and particularly relates to a method for regenerating a desulfurization and denitrification catalyst based on red mud. Background Art
[0002] After the red mud produced by the Bayer process for alumina production is made into a catalyst, it has good desulfurization and denitrification performance. However, the treatment of the catalyst after it fails will bring other troubles to environmental governance. Therefore, the regeneration of the failed catalyst can not only improve the utilization efficiency of the catalyst, reduce the use cost, but also reduce the environmental burden.
[0003] The catalyst made from the red mud produced by the Bayer process for alumina production mainly consists of iron oxide (Fe2O3), aluminum oxide (Al2O3), silicon dioxide (SiO2), calcium oxide (CaO), sodium oxide (Na2O), etc. Its desulfurization and denitrification principle includes that metal oxides such as Fe2O3 catalyze the SCR reaction of NO and NH3 at high temperature, the basic substances such as CaO and Na2O produce a neutralization reaction with SO2, and the adsorption effect, etc. The main reason for the failure of the catalyst made from the red mud produced by the Bayer process for alumina production is that the pores in the catalyst are blocked after a long time of desulfurization and denitrification, and the catalytic and neutralization reaction efficiency decreases and the adsorption efficiency drops.
[0004] Through experiments, conventional catalyst regeneration methods such as high temperature and steam have poor regeneration effects on this catalyst; although physical crushing regeneration is effective, the number of regeneration times is limited; and water washing is difficult to operate due to the viscosity of red mud, and the cost is difficult to control.
[0005] On the one hand, there is no disclosed method for regenerating a desulfurization and denitrification catalyst based on red mud in the prior art. On the other hand, in the prior art, there is less about the desulfurization and denitrification catalyst based on red mud, which is different from the desulfurization and denitrification catalyst regenerated in this application. For example, CN111450841A discloses a reduction method for simultaneously desulfurizing and denitrifying a catalyst prepared by using red mud and its preparation method. The prepared desulfurization and denitrification catalyst is loaded, which is significantly different from the desulfurization and denitrification catalyst regenerated in this application, resulting in that it cannot be effectively regenerated according to the prior art. Summary of the Invention
[0006] To solve the deficiencies of the prior art, the present invention provides a method for regenerating a desulfurization and denitrification catalyst based on red mud. The present invention first proposes a method for regenerating a desulfurization and denitrification catalyst based on red mud, and this method combines the physical crushing method and the water washing method, which not only solves the limitation of the number of physical crushing regenerations, but also reduces the water washing frequency and the water washing cost.
[0007] The technical solution provided by the present invention is as follows:
[0008] A method for regenerating a red mud-based desulfurization and denitrification catalyst includes the following steps:
[0009] 1) Obtain a red mud-based desulfurization and denitrification catalyst whose saturated sulfur capacity value has decreased to 1% after use;
[0010] 2) Crush the catalyst with a crusher to less than 100 mesh;
[0011] 3) Mix the crushed catalyst powder with water in a weight ratio of 1:(2 - 4), and then stir (for example, using a stirrer, the speed is 200 - 400 rpm, preferably 300 rpm; the stirring time is 0.5 - 2 h, preferably 1 h) for the first-stage water washing;
[0012] 4) Filter by suction or pressure filtration until there is no dripping liquid, and separate to obtain filter cakes and filtrate;
[0013] 5) Re-add the filter cakes in step 4) to the filtrate, add water until the ratio of filter cakes to filtrate reaches 1:(2 - 4), and then stir (for example, using a stirrer, the speed is 200 - 400 rpm, preferably 300 rpm; the stirring time is 0.5 - 2 h, preferably 1 h) for the second-stage water washing;
[0014] 6) After water washing, filter by suction until there is no accumulated water on the surface of the filter cakes, then wash with water (the water consumption is generally not less than 100% of the weight of the catalyst powder), and continue to filter by suction until there is no dripping liquid on the surface of the filter cakes;
[0015] 7) Dry and crush the filter cakes into pellets to obtain a first-stage regenerated catalyst.
[0016] Based on the above technical solution, the water washing regeneration can be carried out on the red mud-based desulfurization and denitrification catalyst that has failed after use, especially after the first failure, and the desulfurization and denitrification catalyst that has undergone multiple crushing and regeneration.
[0017] In step 3), the preferred weight ratio is 1:3. In actual operation, it can be adjusted according to the filtrate recovery situation, that is, adjusted to a weight ratio of filter cakes to filtrate of 1:3.
[0018] Specifically, in step 1), the red mud-based desulfurization and denitrification catalyst is the desulfurization and denitrification catalyst that has failed for the first time after use.
[0019] Specifically, in step 1), it is the desulfurization and denitrification catalyst that has been used after at least one crushing and regeneration and finally fails.
[0020] The inventor found that for the desulfurization and denitrification catalyst that has been used after at least one crushing and regeneration and finally becomes ineffective, the technical solution provided by the present invention can carry out water washing regeneration through the above technical solution. Moreover, the sulfur capacity value of the regenerated desulfurization and denitrification catalyst is as high as 1.2 - 1.4%.
[0021] Specifically, the crushing and regeneration includes the following steps:
[0022] a) Use a crusher to crush the ineffective catalyst to less than 100 mesh;
[0023] b) Granulate the obtained catalyst powder;
[0024] c) Shape and dry to obtain the crushed and regenerated catalyst.
[0025] Based on the above technical solution, the ineffective desulfurization and denitrification catalyst can be simply crushed and regenerated first.
[0026] During the above granulation process, appropriate water or binder can be added to increase the viscosity. Examples of the binder include sodium carboxymethylcellulose or polyacrylamide, etc.
[0027] Further: Repeat steps a) to c), and the number of repetitions is 1 - 3 times.
[0028] Based on the above technical solution, through simple crushing and regeneration, it can still be used 1 - 3 times.
[0029] Further, the method for regenerating the desulfurization and denitrification catalyst based on red mud further includes the following steps:
[0030] 8) Use the catalyst obtained in step 7) until it becomes ineffective;
[0031] 9) Use a crusher to crush the ineffective catalyst to less than 100 mesh, and then granulate and shape it;
[0032] 10) Dry it to obtain the second - level regenerated catalyst for the first time.
[0033] The inventor found that for the catalyst regenerated by water washing above, that is, the first - level regenerated catalyst, it can also be simply crushed and regenerated.
[0034] Further, the method for regenerating the desulfurization and denitrification catalyst based on red mud further includes the following steps to be repeated: 11) Use the second - level regenerated catalyst obtained for the first time until it becomes ineffective, then use a crusher to crush the ineffective catalyst to less than 100 mesh, then granulate and shape it, and then dry it to obtain the reusable second - level regenerated catalyst.
[0035] The inventor found that for the catalyst regenerated by water washing above, that is, the first - level regenerated catalyst, it can also be repeatedly crushed and regenerated, thereby increasing the number of regeneration and use times.
[0036] Specifically, the number of repetitions is 1 - 15 times.
[0037] Specifically, the sulfur capacity value of the catalyst obtained by primary regeneration is 1.3 - 1.5%.
[0038] Specifically, the sulfur capacity value of the catalyst obtained by secondary regeneration for the first time is 1.2 - 1.4%.
[0039] Based on the above technical solution, both the catalyst of primary regeneration and the catalyst of secondary regeneration have high sulfur capacity values, so they can be used repeatedly for many times.
[0040] Specifically, after repeating 1 - 15 times, the nitrate capacity value of the catalyst is 0.15 - 0.16%.
[0041] Based on the above technical solution, neither the crushing regeneration nor the water washing regeneration affects the nitrate capacity value.
[0042] Specifically: The desulfurization and denitrification catalyst is made from red mud produced in the production of alumina by the Bayer process.
[0043] Based on the above technical solution, the desulfurization and denitrification catalyst is directly obtained from red mud produced in the production of alumina by the Bayer process through physical treatment steps such as granulation, without the need for modification, such as surface modification, or addition of other elements for modification. This makes the entire technical solution have wide applicability.
[0044] The beneficial effects of the present invention are as follows:
[0045] 1) Improve the catalytic efficiency of the regenerated catalyst: The average desulfurization and denitrification efficiency of the regenerated catalyst can remain above 90% of that before regeneration;
[0046] 2) Improve the catalyst regeneration efficiency: By combining physical crushing regeneration and water washing regeneration, within a single catalyst cycle (calculated based on 10 times of crushing regeneration and 1 time of water washing regeneration), the utilization rate (the weight of the material that can be catalytically treated per unit weight of the catalyst) can be increased by more than 6 times;
[0047] 3) Reduce the use cost: Compared with the traditional water washing regeneration of the catalyst, this combined regeneration method can reduce the water consumption by 92.3%, and the loss of filter cloth and power consumption during the filtration process can be reduced by more than 80%;
[0048] 4) Reduce the environmental pressure: The regeneration and reuse of the catalyst can greatly reduce the emission and treatment of saturated catalysts; The cascaded use of the filtrate during the water washing process can reduce the sewage discharge by 33%. Description of the Drawings
[0049] Figure 1It is a flowchart of the method for regenerating the desulfurization and denitrification catalyst based on red mud provided by the present invention. Specific embodiments
[0050] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.
[0051] Unless otherwise specified, the test methods used in the examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, are reagents and materials that can be obtained from commercial channels.
[0052] Source of the desulfurization and denitrification catalyst based on red mud: It is obtained by retrieving the waste red mud from the alumina plant and granulating it.
[0053] Example 1
[0054] Crush and regenerate the conventionally used and failed desulfurization and denitrification catalyst based on red mud, including the following steps:
[0055] a) Crush the failed desulfurization and denitrification catalyst based on red mud to below 100 mesh using a crusher;
[0056] b) Granulate the obtained catalyst powder;
[0057] c) Shape and dry to obtain the crushed and regenerated catalyst;
[0058] d) Repeat steps a) to c) three times, and then continue to use until it fails, and the sulfur capacity value drops to 1%.
[0059] Example 2
[0060] On the basis of Example 1, wash and regenerate the catalyst that has been used until it fails and the sulfur capacity value drops to 1%, including the following steps:
[0061] 1) Obtain the desulfurization and denitrification catalyst based on red mud whose saturated sulfur capacity has dropped to 1% after use;
[0062] 2) Crush the catalyst to below 100 mesh using a crusher;
[0063] 3) Mix the crushed catalyst powder with water in a weight ratio of 1:3, and then stir using a stirrer at a speed of 300 rpm for 1 h for the first-stage water washing;
[0064] 4) Filter by suction or pressure filtration until there is no dripping liquid, and separate to obtain filter cakes and filtrate;
[0065] 5) adding the filter block in step 4) back into the filtrate, adding water until the ratio of the filter block to the filtrate reaches 1:3, and then stirring with a stirrer at a speed of 300 rpm for 1 hour to perform a second stage of water washing;
[0066] 6) After washing with water, filter until there is no water on the surface of the filter block, then rinse with 100% water by weight of the catalyst powder, and continue to filter until there is no droplet on the surface of the filter block;
[0067] 7) The filter block is dried and crushed into granules to obtain a first-stage regenerated catalyst.
[0068] Tested:
[0069] The sulfur capacity of the primary regenerated catalyst was 1.4%.
[0070] Example 3
[0071] Based on Example 2, the catalyst regenerated by water washing is used conventionally until it fails, and then crushed and regenerated, including the following steps:
[0072] 8) Use a crusher to crush the spent catalyst to less than 100 mesh, and then granulate it;
[0073] 9) Drying to obtain the second-stage regenerated catalyst for the first time.
[0074] Tested:
[0075] The sulfur capacity of the catalyst obtained by the second-stage regeneration for the first time was 1.35%.
[0076] The above embodiments can refer to Figure 1 process.
[0077] Effect example
[0078] The catalyst obtained by secondary regeneration in Example 3 was repeatedly used until it failed, and then further crushed and regenerated, and the catalyst was tested. After crushing and regenerating for the 15th time, the test results were as follows:
[0079] The sulfur capacity is 1.0%.
[0080] Comparative Example 1
[0081] Referring to Example 3, the difference is that, based on Example 2, the catalyst regenerated by water washing is used conventionally until it fails, and then water washing is used for regeneration. After use, only water washing is repeated for regeneration. According to the test results, after 5 repeated regenerations, the sulfur capacity value dropped to 1.0%. After water washing again, the sulfur capacity value could not be restored to more than 1.2%, indicating complete failure.
[0082] In the above embodiments, the usage method referred to in normal use is as follows: used at a temperature of about 110°C, an inlet sulfur dioxide concentration of 2000 - 5000 mg / cubic meter, and an inlet nitrogen oxide concentration of 200 - 400 mg / cubic meter. The outlet meets the requirements that the sulfur dioxide concentration is lower than 35 mg / cubic meter and the nitrogen oxide concentration is lower than 30 mg / cubic meter.
[0083] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A method for regenerating a desulfurization and denitrification catalyst based on red mud, characterized in that: The following steps are involved: 1) obtaining a red mud-based desulfurization and denitrification catalyst whose saturated sulfur capacity is reduced to 1% after use; 2) crushing the catalyst to less than 100 meshes using a crusher; 3) Mixing the crushed catalyst powder with water in a weight ratio of 1:(2-4), and then stirring to perform the first stage of water washing; 4) Filter by suction or pressure until there is no droplet, and separate the filter cake and the filtrate; 5) adding the filter block in step 4) back into the filtrate, stirring and performing a second stage of water washing; 6) After washing with water, filter until there is no water on the surface of the filter block, then rinse with water and continue to filter until there is no dripping liquid on the surface of the filter block; 7) The filter block is dried and crushed into granules to obtain a first-stage regenerated catalyst.
2. The method for regenerating a desulfurization and denitrification catalyst based on red mud according to claim 1, characterized in that: In step 1), the red mud-based desulfurization and denitrification catalyst is: Desulfurization and denitrification catalysts that fail for the first time after use; Alternatively, the spent desulfurization and denitrification catalyst is obtained by continuing to use the catalyst after being crushed and regenerated at least once.
3. The method for regenerating a desulfurization and denitrification catalyst based on red mud according to claim 2, characterized in that: The crushing regeneration comprises the following steps: a) Use a crusher to crush the spent catalyst to less than 100 mesh; b) granulating the obtained catalyst powder; c) Forming and drying to obtain a broken and regenerated catalyst.
4. The method for regenerating a desulfurization and denitrification catalyst based on red mud according to claim 3, characterized in that: Repeat steps a) to c) 1-3 times.
5. The method for regenerating a desulfurization and denitrification catalyst based on red mud according to claim 1, characterized in that: The following steps are also included: 8) using the catalyst obtained in step 7) until it becomes ineffective; 9) Use a crusher to crush the spent catalyst to less than 100 mesh, and then granulate it; 10) Drying to obtain the second-stage regenerated catalyst for the first time.
6. The method for regenerating a desulfurization and denitrification catalyst based on red mud according to claim 5, characterized in that: The method also includes the following steps which are repeated: 11) using the first obtained secondary regenerated catalyst until it becomes ineffective, and then crushing the ineffective catalyst to less than 100 meshes using a crusher, and then granulating and forming the catalyst, and then drying the catalyst to obtain a reusable secondary regenerated catalyst.
7. The method for regenerating a desulfurization and denitrification catalyst based on red mud according to claim 6, characterized in that: The number of repetitions is 1-15 times.
8. The method for regenerating a desulfurization and denitrification catalyst based on red mud according to claim 7, characterized in that: The sulfur capacity of the first-stage regenerated catalyst obtained is 1.3-1.5%; The sulfur capacity of the first obtained secondary regenerated catalyst is 1.2-1.4%.
9. The method for regenerating a desulfurization and denitrification catalyst based on red mud according to claim 7, characterized in that: After repeating 1-15 times, the nitric acid content of the catalyst is 0.15-0.16%.
10. The method for regenerating a desulfurization and denitrification catalyst based on red mud according to any one of claims 1 to 9, characterized in that: The desulfurization and denitration catalyst is a desulfurization and denitration catalyst made from red mud produced by the Bayer process for producing alumina.