CuO-loaded modified fly ash-based CO oxidation catalyst and preparation method thereof
By modifying fly ash-based CO oxidation catalysts with CuO support, the CO emission problem in the steel industry has been solved, achieving efficient and low-cost CO oxidation, and providing a high-value utilization pathway for fly ash, thus promoting resource recycling and environmental protection.
Patent Information
- Application Number
- CN202511290491.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-10
- Publication Date
- 2025-11-07
AI Technical Summary
Existing technologies are insufficient for efficiently removing CO emissions in the steel industry, commercial precious metal catalysts are expensive, and traditional modification methods pose secondary pollution problems.
A CuO-supported modified fly ash-based CO oxidation catalyst was prepared by using modified fly ash as a support, loading CuO as the active component, and using calcium hydroxide-citric acid combined modification treatment.
It significantly improves CO oxidation efficiency, reduces catalyst costs, reduces secondary pollution during the production process, provides a high-value-added utilization path for fly ash, and achieves resource recycling and environmental protection.
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Figure CN120900719A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of CO oxidation catalysts, in particular to a CuO loaded modified fly ash based CO oxidation catalyst and a preparation method thereof. BACKGROUND
[0002] As an important basic industry of China's national economy, the crude steel output of the national scale above enterprises reached 1.005 billion tons in 2024. As a typical high energy consumption and high emission industry, its production process relies on fossil fuel combustion and leads to a large amount of CO emission. Excessive CO emission not only causes photochemical pollution but also deepens the greenhouse effect, and also endangers people's health. Under the background of the "double carbon" strategy, developing an economic and efficient CO deep removal technology has become a rigid demand for steel enterprises to realize ultra-low emission transformation.
[0003] The current CO catalytic oxidation technology applied to small mobile emission sources is the most promising CO control technology in sintering flue gas CO control. This technology uses the selective adsorption of CO and O2 on the surface active sites of the catalyst and reacts to generate CO2 to achieve the purpose of CO purification. However, in actual application, due to the cost problem of commercial noble metal catalysts, it is difficult to directly introduce them into the treatment of steelmaking flue gas in the steel industry. Therefore, developing new catalyst materials with easy-to-obtain raw materials and low cost has become a key breakthrough for efficient CO control in this field. SUMMARY
[0004] The purpose of the present application is to provide a CuO loaded modified fly ash based CO oxidation catalyst and a preparation method thereof. The catalyst improves the dispersion of the active component Cu on the surface of the modified fly ash carrier by increasing the specific surface area of the modified fly ash carrier, widens the active temperature window, and can achieve high CO catalytic activity at low temperature, significantly improves the CO oxidation efficiency of the catalyst, and has the advantages of easy-to-obtain raw materials and low cost.
[0005] To achieve the above purpose, the present application provides the following scheme:
[0006] One of the technical solutions of the present application is a preparation method of a CuO loaded modified fly ash based CO oxidation catalyst, comprising the following steps:
[0007] Step 1: calcining the fly ash to obtain pretreated fly ash;
[0008] Step 2: mixing the pretreated fly ash with a calcium hydroxide suspension and performing a hydrothermal reaction, then filtering and drying to obtain calcium hydroxide modified fly ash;
[0009] Step 3: mixing the calcium hydroxide modified fly ash with a citric acid solution and reacting, then filtering and drying to obtain a calcium hydroxide-citric acid combined modified fly ash carrier;
[0010] Step 4, the calcium hydroxide-citric acid combined modified fly ash carrier is mixed with copper nitrate solution by impregnation method, stirring to dry, and then drying and calcining in sequence to obtain a CuO loaded modified fly ash based CO oxidation catalyst.
[0011] The second technical solution of the present application is a CuO loaded modified fly ash based CO oxidation catalyst prepared by the above preparation method.
[0012] The third technical solution of the present application is the application of the above CuO loaded modified fly ash based CO oxidation catalyst in CO catalytic oxidation.
[0013] Compared with the prior art, the present application has the following beneficial technical effects:
[0014] ①Significantly reduce the cost of CO oxidation catalyst production: using modified fly ash as a carrier can achieve a relatively ideal CO conversion efficiency under the condition of loading a small amount of CuO, effectively reducing the amount of metal salt reagent used in the catalyst production process.
[0015] ②Reduce secondary pollution in the catalyst production process: the combined activation of citric acid and calcium hydroxide not only effectively regulates the pore structure of fly ash to increase the specific surface area, but also avoids the secondary pollution caused by the discharge of acid or alkali in traditional acid-base modification, realizing a green and low-emission carrier preparation process and providing an environmentally friendly path for catalyst development.
[0016] ③Provide a new way for high value-added products of fly ash: modified fly ash as a catalyst carrier not only can solve the pressure of fly ash storage, but also can be converted into high value-added products, realizing resource recycling, reducing consumption and improving the environment, and having significant economic and environmental benefits. BRIEF DESCRIPTION OF DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0018] Figure 1 A comparison chart of the catalytic performance data of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 of the present application. DETAILED DESCRIPTION
[0019] The various exemplary embodiments of the present application will now be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.
[0020] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, for a range of values of, for example, the upper limit and the lower limit of the range are also specifically disclosed. Each intermediate value of the range is also specifically disclosed. Each smaller range which falls within the disclosed range is also specifically disclosed. The upper and lower limits of these smaller ranges can independently be included or excluded in the range.
[0021] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application.
[0022] Many modifications and variations of the present application described herein will be apparent to those of ordinary skill in the art from the foregoing description. Other embodiments of the application will be apparent to those of ordinary skill in the art from the foregoing description. The description herein is by way of example only and is not intended to limit the application.
[0023] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having" or the like are open-ended terms that are intended to mean including, but not limited to.
[0024] As used herein, the term "room temperature" means 20-30°C, unless otherwise specified.
[0025] Fly ash is a solid waste discharged on a large scale by coal-fired power plants, which not only occupies land resources, but also causes complex pollution of the atmosphere, soil and groundwater due to particle diffusion and heavy metal leaching, with a serious potential environmental risk. How to realize the high-value utilization and safe disposal of fly ash has become a bottleneck restricting the green development of the energy industry. Against this background, the development of CO oxidation catalysts using modified fly ash as a carrier not only can significantly reduce the production cost of the catalyst, but also can absorb large-scale fly ash, realizing the reduction and resource utilization of solid waste. The breakthrough of this technology will provide strong support for the construction of a circular economy system and the development of air pollution control in the steel industry, and promote the green and low-carbon transformation of the industry.
[0026] Fly ash is mainly composed of glass phase, and has poor activity. Therefore, in order to improve the utilization rate, metal or metal oxide is often loaded on the fly ash during modification to improve its waste gas treatment ability. CuO has Cu + / Cu 2+CuO and transition metal co-doping can significantly reduce the CO oxidation reaction temperature due to the reduction cycle, wide source, low price, synergistic effect with other metal oxides and excellent CO adsorption capacity. Therefore, by selecting modified fly ash as the catalyst carrier and CuO as the active component, the development of CuO-loaded modified fly ash-based catalyst is expected to become an industrialized CO oxidation catalyst, which can add a new path for the realization of energy saving and carbon reduction target of steel industry and the construction of industrial internal circulation economy.
[0027] The first aspect of the present application provides a preparation method of CuO-loaded modified fly ash-based CO oxidation catalyst, comprising the following steps:
[0028] Step 1: calcining the fly ash to obtain pretreated fly ash;
[0029] Step 2: mixing the pretreated fly ash with a calcium hydroxide suspension and then performing a hydrothermal reaction, followed by filtration and drying to obtain calcium hydroxide-modified fly ash;
[0030] Step 3: mixing the calcium hydroxide-modified fly ash with a citric acid solution and then performing a reaction, followed by filtration and drying to obtain a calcium hydroxide-citric acid combined modified fly ash carrier;
[0031] Step 4: mixing the calcium hydroxide-citric acid combined modified fly ash carrier with a copper nitrate solution by impregnation method, stirring until dry, and then sequentially drying and calcining to obtain a CuO-loaded modified fly ash-based CO oxidation catalyst.
[0032] In some embodiments of the present application, the calcium hydroxide suspension is prepared by dissolving calcium hydroxide in water; the solvent of the citric acid solution is water; and the solvent of the copper nitrate solution is water.
[0033] In preferred embodiments of the present application, in step 1, the calcination treatment is specifically as follows: heating at a heating rate of 5-10℃ / min to 800-850℃ and maintaining for 2-3h.
[0034] In preferred embodiments of the present application, after the calcination treatment in step 1, a step of cooling to room temperature at a cooling rate of 5-10℃ / min is further included.
[0035] In a preferred embodiment of the present application, in step 1, the temperature of the calcination treatment can be 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, etc., and the calcination time can be, for example, 2h, 2.5h, 3h. The heating rate of the calcination treatment is controlled at 5-10℃ / min, for example, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min; the cooling rate of the calcination treatment is controlled at 5-10℃ / min, for example, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min.
[0036] In a preferred embodiment of the present application, in step 2, the mass fraction of the calcium hydroxide suspension is 10%-18%; the solid-liquid ratio of the pretreated fly ash to the calcium hydroxide suspension is (0.058-0.169)g:1ml; the temperature of the hydrothermal reaction is 180-190℃, for example, 180℃, 185℃, 190℃, etc.; the time of the hydrothermal reaction is 8-10h, for example, 8h, 9h, 10h, etc.
[0037] In step 2, before mixing the calcium hydroxide modified fly ash with the citric acid solution and performing the reaction, a step of stirring for 30-40min is further included. Specifically, the stirring time can be 30min, 35min, 40min, etc.
[0038] In a preferred embodiment of the present application, in step 3, the concentration of the citric acid solution is 1-2mol / L; the solid-liquid ratio of the calcium hydroxide modified fly ash to the citric acid solution is 1g:(10-30)ml; the temperature of the reaction is room temperature, and the time of the reaction is 3-4h; stirring is further performed during the reaction, and the stirring time is 3-4h, which can be, for example, 3h, 3.5h, 4h, etc.
[0039] In steps 2 and 3, the drying temperature is 60-70℃, for example, 60℃, 65℃, 70℃, etc.; and the drying time is 12-14h, for example, 12h, 13h, 14h, etc.
[0040] In a preferred embodiment of the present application, in step 4, the concentration of the copper nitrate solution is 0.1-1mol / L; and the solid-liquid ratio of the calcium hydroxide-citric acid combined modified fly ash carrier to the copper nitrate solution is (0.045-1.511)g:1ml.
[0041] In some embodiments of the present application, the loading amount of CuO in the catalyst can be regulated by adjusting the solid-liquid ratio of the calcium hydroxide-citric acid combined modified fly ash carrier to the copper nitrate solution.
[0042] In the preferred embodiment of the present application, in step 4, the temperature for impregnation is 60-70℃, for example, it can be 60℃, 65℃, 70℃, etc.; the temperature for drying is 60-70℃, for example, it can be 60℃, 65℃, 70℃, etc.; the time for drying is 12-14h, for example, it can be 12h, 13h, 14h, etc.; the calcination specifically refers to: heating at a heating rate of 5-10℃ / min to 400-450℃ and keeping for 4-5h; after the calcination is completed, it further includes the step of cooling to room temperature at a cooling rate of 5-10℃ / min under air atmosphere.
[0043] In some embodiments of the present application, in step 4, the temperature for calcination can be, for example, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, etc., and the calcination time can be, for example, 4h, 4.5h, 5h. The heating rate for calcination is controlled at 5-10℃ / min, for example, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min; the cooling rate after calcination is controlled at 5-10℃ / min, for example, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min.
[0044] The second aspect of the present application provides a CuO-loaded modified fly ash-based CO oxidation catalyst prepared according to the preparation method described above.
[0045] The present application uses calcium hydroxide-citric acid combined modification to prepare the catalyst, which has no strong acid / alkali waste liquid discharge, is relatively friendly to the environment, and the prepared catalyst is suitable for industrial application of CO emission control technology in the steel industry, has significant economic value and environmental benefits as a high-value fly ash product.
[0046] The third aspect of the present application provides the application of the above-mentioned CuO-loaded modified fly ash-based CO oxidation catalyst in CO catalytic oxidation.
[0047] The present application uses calcium hydroxide-citric acid combined modification to prepare the catalyst, which has no strong acid / alkali waste liquid discharge, is relatively friendly to the environment, and the prepared catalyst is suitable for industrial application of CO emission control technology in the steel industry, has significant economic value and environmental benefits as a high-value fly ash product.
[0048] The technical solutions described in the present application are conventional solutions in the art if not specifically stated, and the reagents or raw materials used are purchased from commercial channels or are already disclosed if not specifically stated.
[0049] The technical solutions provided by the present application will be described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.
[0050] Example 1
[0051] A preparation method of a CuO loaded modified fly ash based CO oxidation catalyst, the steps are as follows:
[0052] Step 1, 10g of fly ash was heated from room temperature to 800℃ at a heating rate of 10℃ / min in a tube furnace under air atmosphere and kept for 2h, then cooled to room temperature at a rate of 10℃ / min to obtain the pretreated fly ash;
[0053] Step 2, 2.09g of calcium hydroxide was dissolved in 17.73g of water to obtain a calcium hydroxide suspension, 10g of the pretreated fly ash was mixed with the calcium hydroxide suspension by a magnetic stirrer for 30min to obtain a mixed solution. The mixed solution was placed in a reaction kettle with a polytetrafluoroethylene liner and hydrothermally reacted at 180℃ for 8h, then filtered by a vacuum pump, and finally dried in a 60℃ oven for 12h to obtain the calcium hydroxide modified fly ash;
[0054] Step 3, 5g of the calcium hydroxide modified fly ash was mixed with 50ml of 1mol / L citric acid solution by a magnetic stirrer at room temperature and reacted for 3h, then the mixed solution after reaction was filtered by a vacuum pump, and finally dried at 60℃ for 12h to obtain the calcium hydroxide-citric acid combined modified fly ash carrier;
[0055] Step 4, 25g of the calcium hydroxide-citric acid combined modified fly ash carrier prepared by repeating steps 1-3 was mixed with 33ml of 0.5mol / L copper nitrate solution, and then stirred at 60℃ until dry. After drying in a 60℃ oven for 12h, it was calcined at 400℃ in a tube furnace for 4h to obtain the CuO loaded modified fly ash based CO oxidation catalyst, which was marked as 5Cu / CFA.
[0056] Example 2
[0057] The difference from Example 1 is only that in step 4, the amount of the calcium hydroxide-citric acid combined modified fly ash carrier added is 10g, and the amount of 0.5mol / L copper nitrate solution used is 28ml; the rest of the steps and parameters are the same as those of Example 1; the CuO loaded modified fly ash based CO oxidation catalyst prepared is marked as 10Cu / CFA.
[0058] Example 3
[0059] The difference from Example 1 is only that in step 4, the amount of the calcium hydroxide-citric acid combined modified fly ash carrier added is 20g, and the amount of 0.5mol / L copper nitrate solution used is 88ml; the rest of the steps and parameters are the same as those of Example 1; the CuO loaded modified fly ash based CO oxidation catalyst prepared is marked as 15Cu / CFA.
[0060] Comparative Example 1
[0061] The difference between Example 2 and the present example is that step 2 and step 3 are omitted, and the pretreated fly ash is directly mixed with copper nitrate solution; the rest of the steps and parameters are the same as Example 2; the prepared oxidation catalyst is recorded as 10Cu / RCFA.
[0062] Comparative Example 2
[0063] The difference between Example 2 and the present example is that step 2 is omitted; the rest of the steps and parameters are the same as Example 2; the prepared oxidation catalyst is recorded as 10Cu / ACFA.
[0064] Comparative Example 3
[0065] The difference between Example 2 and the present example is that step 3 is omitted; the rest of the steps and parameters are the same as Example 2; the prepared oxidation catalyst is recorded as 10Cu / CCFA.
[0066] Activity detection of the catalyst:
[0067] The catalysts prepared in Examples 1-3 and Comparative Examples 1-3 were respectively placed into a fixed bed reactor for catalytic activity test.
[0068] The catalyst activity determination conditions were: reaction temperature was 30-300℃, reaction pressure was normal pressure, 5000ppm CO, 20% O2, N2 was the balance gas, gas flow was 200ml / min, and the catalyst dosage was 0.3g. The CO catalytic activity test results of the catalysts are shown in Table 1. Figure 1
[0069] The CO catalytic activity of the catalyst was evaluated by CO conversion rate: X CO = (CO in -CO out ) / CO in *100%.
[0070] Wherein CO in and CO out represent the CO concentrations at the inlet and outlet of the fixed bed reactor, respectively. The specific catalytic activity test results are shown in Table 1. Figure 1 It can be found that the CO conversion rates of all catalyst samples increase with the increase of temperature, and all reach more than 90% CO catalytic efficiency at 240℃. At the same time, it is found that with the increase of CuO loading, the CO conversion efficiency shows a trend of first increasing and then decreasing, and when the CuO loading reaches 10wt.% (Example 2), the CO conversion rate reaches the best state, and the CO conversion rate of 10Cu / CFA can reach 94.3% at 210℃.
[0071] The above described embodiments are only to illustrate the preferred modes of the present application, and are not intended to limit the scope of the present application. Any modification and improvement made by those skilled in the art to the technical solutions of the present application without departing from the design spirit of the present application shall fall within the protection scope of the present application as defined by the claims.
Claims
1. A method for preparing a CuO supported modified fly ash based CO oxidation catalyst, characterized in that, The method comprises the following steps: Step 1, calcining fly ash to obtain pretreated fly ash; Step 2, mixing the pretreated fly ash with a calcium hydroxide suspension and then performing a hydrothermal reaction, and then performing filtration and drying to obtain calcium hydroxide modified fly ash; Step 3, mixing the calcium hydroxide modified fly ash with a citric acid solution and then performing a reaction, and then performing filtration and drying to obtain calcium hydroxide-citric acid combined modified fly ash carrier; Step 4, mixing the calcium hydroxide-citric acid combined modified fly ash carrier with a copper nitrate solution by impregnation, stirring until dry, and then sequentially performing drying and calcination to obtain a CuO loaded modified fly ash based CO oxidation catalyst.
2. The production method according to claim 1, characterized by, In step 1, the calcination treatment is specifically performed by heating at a heating rate of 5-10℃ / min to 800-850℃ and maintaining for 2-3h.
3. The preparation method according to claim 1, characterized in that, In step 1, after the calcination treatment is completed, a step of cooling at a cooling rate of 5-10℃ / min to room temperature is further included.
4. The method of claim 1, wherein, In step 2, the mass fraction of the calcium hydroxide suspension is 10%-18%, the solid-liquid ratio of the pretreated fly ash to the calcium hydroxide suspension is (0.058-0.169)g:1ml, the temperature of the hydrothermal reaction is 180-190℃, and the time of the hydrothermal reaction is 8-10h.
5. The preparation method according to claim 1, characterized in that, In step 3, the concentration of the citric acid solution is 1-2mol / L, the solid-liquid ratio of the calcium hydroxide modified fly ash to the citric acid solution is 1g:(10-30)ml, the temperature of the reaction is room temperature, and the time of the reaction is 3-4h.
6. The method of claim 1, wherein, In step 4, the concentration of the copper nitrate solution is 0.1-1mol / L, and the solid-liquid ratio of the calcium hydroxide-citric acid combined modified fly ash carrier to the copper nitrate solution is (0.045-1.511)g:1ml.
7. The preparation method according to claim 1, characterized in that, In step 4, the temperature of the impregnation is 60-70℃, the temperature of the drying is 60-70℃, the time of the drying is 12-14h, the calcination is specifically performed by heating at a heating rate of 5-10℃ / min to 400-450℃ and maintaining for 4-5h, and after the calcination is completed, a step of cooling at a cooling rate of 5-10℃ / min to room temperature under an air atmosphere is further included.
8. A CuO loaded modified fly ash based CO oxidation catalyst prepared by the preparation method according to any one of claims 1-7.
9. Application of the CuO loaded modified fly ash based CO oxidation catalyst according to claim 8 in catalytic oxidation of CO.