Preparation method and application of Fe2O3 catalyst
By preparing a high-purity, highly crystalline sponge-like Fe2O3 catalyst, the problems of insufficient low-temperature activity and vanadium contamination of existing catalysts were solved, achieving high-efficiency flue gas denitrification at medium and low temperatures, which is suitable for flue gas treatment in cement kilns and glass furnaces.
Patent Information
- Application Number
- CN202511608885.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-05
- Publication Date
- 2026-01-30
AI Technical Summary
Existing commercial catalysts V2O5-WO3(MoO3)/TiO2 have insufficient activity at low temperatures, resulting in poor denitrification effects in industries such as cement kilns and glass furnaces. They also pose risks of high cost and vanadium pollution. Fe-based catalysts are complex to prepare and have insufficient activity at medium and low temperatures.
Two different iron salts were dissolved and the pH was adjusted before a hydrothermal reaction was carried out to form a precursor with a specific structure. The precursor was then calcined at high temperature to prepare a high-purity, highly crystalline sponge-like Fe2O3 catalyst with high activity at medium and low temperatures and a wide temperature range.
It achieves high denitrification efficiency in the temperature range of 210 to 330℃, especially close to 100% in the range of 240 to 330℃. It is suitable for flue gas denitrification in glass furnaces and cement furnaces, and the preparation method is simple and low in cost.
Smart Images
Figure CN121422967A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a catalyst, particularly a method for preparing an Fe2O3 catalyst, and also to the application of the Fe2O3 catalyst. Background Technology
[0002] Selective catalytic reduction technology is widely used for NO removal in flue gas. x Removal, especially of NO in flue gas from coal-fired power plants x The purification and removal of vanadium is a crucial process. Currently, the commercially available catalyst for this process is V2O5-WO3(MoO3) / TiO2. This catalyst is expensive and suffers from low selectivity at high temperatures and the potential for secondary pollution from vanadium. Most importantly, its low-temperature (<300℃) activity is insufficient, making it unsuitable for flue gas denitrification in industries such as cement kilns and glass furnaces. Therefore, developing vanadium-free, environmentally friendly, and highly efficient low-temperature denitrification catalysts is an urgent problem to be solved. In numerous studies, Fe-based catalysts have demonstrated good catalytic performance and selectivity, and are considered promising environmentally friendly denitrification catalysts. However, they still face challenges such as complex preparation methods, insufficient low-temperature activity, and the need for additional additives like Mn and Ti to enhance activity. Summary of the Invention
[0003] Purpose of the invention: The purpose of this invention is to provide a method for preparing Fe2O3 catalyst, so as to prepare a catalyst with high catalytic activity at medium and low temperatures and a wide temperature range of activity. Another purpose of this invention is to provide the application of this catalyst.
[0004] Technical solution: The preparation method of the Fe2O3 catalyst of the present invention includes the following steps:
[0005] (1) Dissolve the first ferric salt and the second ferric salt in water to form a solution, add an organic solvent, add an alkali to adjust the pH to 8-10, and then place it at 150-170℃ for hydrothermal reaction;
[0006] (2) Separation step (1) solid: calcine the solid at 490~510℃ to obtain Fe2O3 catalyst.
[0007] Preferably, the first iron salt and the second iron salt have different anions, and each is independently selected from one or more of ferric chloride, ferric sulfate, and ferric nitrate.
[0008] This invention employs two iron salts. The different anions of the two iron salts lead to gradient differences in the iron ion hydrolysis rate and solution environment, such as ionic strength and complexation. Under high temperature and high pressure and water-organic solvent environment, a precursor with a specific structure and improved crystallinity is formed, laying the foundation for subsequent calcination to obtain high-purity and high-crystallinity Fe2O3. Finally, the precursor is calcined at a specific temperature to obtain a sponge-like Fe2O3 catalyst. The obtained Fe2O3 catalyst exhibits high low-temperature activity and a wide activity temperature window.
[0009] Preferably, the concentrations of the first ferric salt and the second ferric salt in the solution are 0.05 mol / L to 0.10 mol / L and 0.04 mol / L to 0.07 mol / L, respectively.
[0010] Preferably, the organic solvent is at least one of ethanol, methanol, and ethylene glycol.
[0011] Preferably, the volume ratio of the organic solvent to water is 1:6 to 1:4. The organic solvent needs to be matched with the aqueous phase, iron salt concentration, etc. Too high a ratio will lead to a decrease in solution stability, while too low a ratio will not achieve the desired control effect.
[0012] Preferably, the mass ratio of the first iron salt to the second iron salt is 2:1 to 1:2.
[0013] Preferably, the calcination time is 1.5 to 2.5 hours.
[0014] Preferably, the alkali is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water. The alkali acts as a pH adjuster and precipitant, providing OH-. - Make Fe 3+ It produces iron hydroxide precursors.
[0015] Preferably, the hydrothermal reaction lasts for 6 to 10 hours.
[0016] Application of the Fe2O3 catalyst prepared by the aforementioned method in flue gas denitrification.
[0017] Preferably, the activity temperature window of the Fe2O3 catalyst is 210–330 °C.
[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The catalyst has high low-temperature activity, with a denitrification efficiency of over 80% in the temperature range of 210-330℃ and close to 100% in the temperature range of 240-330℃; 2. The Fe2O3 catalyst was successfully synthesized using a simple method, which is convenient and low-cost; 3. The catalyst is suitable for flue gas denitrification in glass furnaces and cement furnaces, and can overcome the shortcomings of existing commercial catalysts, such as the limitation of the activity temperature window. Attached Figure Description
[0019] Figure 1 Characterization diagrams of the Fe2O3 catalysts prepared in the embodiments of the present invention: (a) Denitrification efficiency of different catalysts; (b) XRD pattern of Fe2O3-A catalyst;
[0020] Figure 2 This is an electron microscope image of sample Fe2O3-A from an embodiment of the present invention. Detailed Implementation
[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings.
[0022] Example 1: The preparation steps of the Fe2O3 catalyst are as follows:
[0023] (1) Add 1.5 g FeCl3·6H2O and 1.5 g Fe2(SO4)3·xH2O to 50 mL of deionized water and stir magnetically for 10 min; then add 11 mL of ethanol directly to the solution and continue stirring for 10 min; then add 10 mL of 1.5 mol / L NaOH solution dropwise to the above solution under stirring and stir for 15 min to obtain the reaction precursor solution;
[0024] (2) Transfer the reaction precursor liquid to a 100 mL hydrothermal reactor and place the reactor in an oven at 160 °C for 8 h, then allow it to cool naturally to room temperature; centrifuge the product and wash it three times with deionized water; then dry it in an oven at 70 °C for 12 h to obtain the precursor.
[0025] (3) The dried precursor was placed in a muffle furnace and calcined at 500 °C for 2 h to obtain the final sample, which was labeled as Fe2O3-A.
[0026] Using the same method and steps as described above, but changing the amounts of FeCl3·6H2O and Fe2(SO4)3·xH2O, 2.0 g of FeCl3·6H2O and 1.0 g of Fe2(SO4)3·xH2O were added respectively to prepare Fe2O3-B; 1.0 g of FeCl3·6H2O and 2.0 g of Fe2(SO4)3·xH2O were added to prepare Fe2O3-C catalyst.
[0027] The catalysts Fe2O3-A, Fe2O3-B, and Fe2O3-C prepared by the above method were tested for catalytic activity. The test conditions were as follows: simulated flue gas composition of NO 600 ppm, NH3 600 ppm, O2 3%, N2 balance gas, total flow rate of 1500 mL / min, temperature range of 120–420℃, and denitrification efficiency was measured every 30℃.
[0028] Figure 1 This shows the denitrification efficiency and XRD patterns of different catalysts. From Figure 1 (a) As can be seen, the denitrification efficiency of all three catalysts gradually increases with increasing temperature. However, once the temperature reaches 240 °C, the difference in their denitrification efficiencies becomes negligible. Overall, Fe2O3-A exhibits the best denitrification performance, especially at temperatures below 240 °C, where its denitrification efficiency is the highest among the three catalysts. Furthermore, Fe2O3-A achieves a denitrification efficiency exceeding 80% in the temperature range of 210–330 °C, and nearly 100% in the 240–330 °C range, demonstrating highly efficient denitrification capabilities.
[0029] Figure 1 (b) is the XRD pattern of Fe2O3-A. As can be seen from the figure, the diffraction peaks of Fe2O3-A all belong to Fe2O3, which is a typical Fe2O3 phase composition. Figure 2 Figure 1 shows the electron microscopy characterization of Fe2O3-A, which consists of aggregated sponge-like ellipsoidal particles. Figure 2(a) shows the activity test results of Fe2O3-A, Fe2O3-B, and Fe2O3-C, indicating that the catalyst synthesized by this method has superior catalytic activity.
[0030] Comparative Example 1: The operation steps of this comparative example are the same as those of Example 1 (1) to (3), except that in step (3), the calcination temperature is 300℃. The precursor cannot be completely decomposed into Fe2O3, and the denitrification efficiency of the final sample is reduced.
Claims
1. A method for preparing a Fe203 catalyst, characterized by, The method comprises the following steps: (1) dissolving a first iron salt and a second iron salt in water to form a solution, adding an organic solvent, adjusting the pH to 8-10 by adding a base, and then carrying out a hydrothermal reaction at 150-170℃; (2) separating the solid in step (1), and calcining the solid at 490-510℃ to obtain a Fe2O3 catalyst.
2. The method of claim 1, wherein the Fe2O3 catalyst is prepared by the steps of: The first iron salt and the second iron salt are different in anion and are each independently selected from one or more of ferric chloride, ferric sulfate and ferric nitrate.
3. The method for preparing the Fe2O3 catalyst according to claim 1, characterized in that, The concentrations of the first iron salt and the second iron salt in the solution are 0.05-0.10 mol / L and 0.04-0.07 mol / L, respectively.
4. The method of claim 1, wherein the Fe2O3 catalyst is prepared by the steps of: The calcination time is 1.5-2.5 hours.
5. The method for preparing the Fe2O3 catalyst according to claim 1, characterized in that, The organic solvent is at least one of ethanol, methanol and ethylene glycol.
6. The method of producing Fe2C>3 catalyst according to any one of claims 1 to 5, characterized by, The volume ratio of the organic solvent to water is 1:6-1:
4.
7. The method for preparing the Fe2O3 catalyst according to claim 1, characterized in that, The base is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate and ammonia water.
8. The method for preparing the Fe2O3 catalyst according to claim 1, characterized in that, The duration of the hydrothermal reaction is 6-10 hours.
9. Use of the Fe2O3 catalyst prepared by the method of any one of claims 1-8 in flue gas denitration.
10. Use according to claim 9, characterized in that, The activity temperature window of the Fe2O3 catalyst is 210-330℃.