A method for preparing an ultra-stable metal-doped aluminum fluoride catalyst
The ultra-stable metal-doped aluminum fluoride catalyst prepared by ball milling and heat treatment solves the stability problem of photocatalysts under extreme environments, and achieves long-term stability and high efficiency photocatalytic performance under strong acids, alkalis and high temperatures.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUZHOU UNIV
- Filing Date
- 2026-04-10
- Publication Date
- 2026-07-10
AI Technical Summary
Existing photocatalysts have poor stability under strong acid, alkali, high temperature or strong oxidizing atmosphere, which limits their large-scale application.
An ultra-stable metal-doped aluminum fluoride catalyst was prepared by ball milling and heat treatment of aluminum-containing compounds. The aluminum fluoride substrate was prepared by self-dissolution of fluorine material in the ball mill jar, avoiding the use of toxic and corrosive reagents, thus constructing a catalyst that is resistant to acid and alkali corrosion and stable at high temperatures.
The prepared catalyst maintains its powder morphology and crystal structure under extreme conditions, exhibiting excellent acid and alkali resistance and thermal oxidation resistance, and retains its photocatalytic CO2 reduction activity.
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Abstract
Description
Technical Field
[0001] This invention relates to the fields of catalytic material preparation and photocatalysis, specifically to a method for preparing an ultra-stable metal-doped aluminum fluoride catalyst. Background Technology
[0002] Utilizing solar energy to drive photocatalytic CO2 reduction into high-value chemical raw materials is an important approach to solving the global energy crisis and achieving the goal of "carbon neutrality." However, currently widely reported photocatalysts, such as metal-organic frameworks (MOFs), molecular catalysts, metal oxides, and carbon-based composites, exhibit poor stability under complex working conditions (such as strong acids and alkalis, high temperatures, or strong oxidizing atmospheres), severely restricting their practical large-scale application. Although MOF materials possess extremely high porosity, they are extremely unstable in acidic and alkaline environments. For example, Kim et al. (Nanomaterials, 2024, 14, 110) pointed out that Zr-based MOFs are prone to phase transitions and structural collapse under alkaline conditions. Guo et al. (Publication No.: CN109126893A) pointed out that MOF materials, due to their weak coordination bonds, are prone to hydrolysis and framework collapse in the presence of an aqueous phase. The mechanistic study by Ail et al. (J. Environ. Chem. Eng., 2025, 120038) definitively demonstrates that in catalytic systems lacking physical confinement, molecular catalysts are highly susceptible to severe aggregation, leading to a decrease in catalytic activity. Carbon-based catalysts and traditional metal oxides exhibit significant structural degradation under thermal oxidizing atmospheres and strong light irradiation. Huang et al. (ACS. Appl. Nano. Mater., 2024, 7, 7442-7452) pointed out that in thermal oxidizing environments, the in-plane hydrogen bonds and interlayer van der Waals forces of polymeric carbon-based materials are severely oxidized, etched, and destroyed, even resulting in the complete loss of semiconductor properties. Meanwhile, Huang et al. (Publication No.: CN103721738B) clearly pointed out the defects of existing photocatalytic materials such as metal oxides (sulfides) in severe photocorrosion at strong redox interfaces, leading to easy catalyst deactivation. Wang et al. (publication number: CN103272639B) also confirmed that conventional carbon-based semiconductors are prone to structural damage under the strong oxidation of photogenerated carriers. Summary of the Invention
[0003] To address the aforementioned problems, this invention provides a method for preparing an ultra-stable metal-doped aluminum fluoride catalyst. This method involves ball milling and heat treatment of aluminum-containing compounds to transform them into ultra-stable metal-doped aluminum fluoride, aiming to provide a novel ultra-stable material solution for photocatalytic CO2 reduction under strong acid, strong alkali, and high-temperature oxidizing environments.
[0004] To achieve the above objectives, the present invention adopts the following technical solution.
[0005] (1) The aluminum-containing compound is dried and ground to obtain aluminum-containing compound powder;
[0006] (2) The aluminum-containing compound powder obtained in step (1) is mixed with metal salt in ethanol in a certain proportion, and mechanically ball-milled in a ball mill jar made of polytetrafluoroethylene. After drying, a composite precursor containing metal and fluorine is obtained.
[0007] (3) The composite precursor obtained in step (2) is heat-treated in an inert atmosphere to obtain a metal-doped aluminum fluoride catalyst.
[0008] Furthermore, the aluminum-containing compound mentioned in step (1) includes one or more of aluminum oxide, aluminum hydroxide, or aluminum hydroxyoxide.
[0009] Furthermore, the drying method described in step (1) includes one or more of the following: room temperature drying, heating drying, and freeze drying. The drying temperature range is -40 to 80 ℃.
[0010] Furthermore, the grinding method described in step (1) is one or more of manual grinding and mechanical grinding, and the ground material is passed through a 60-200 mesh sieve.
[0011] Furthermore, the metal salt mentioned in step (2) includes one or more of iron, cobalt, nickel, copper, and zinc salts.
[0012] Furthermore, the mass ratio of the aluminum compound powder to the metal salt in step (2) is 4:0.5.
[0013] Furthermore, the amount of ethanol mentioned in step (2) is 50-200 mL.
[0014] Furthermore, the ball milling speed in step (2) is 300-600 rpm min. -1 The ball milling time is 8-24 hours.
[0015] Furthermore, the drying method described in step (2) is one or more of room temperature drying and heating drying, with a drying temperature of 20-80 ℃.
[0016] Furthermore, the inert atmosphere mentioned in step (3) is one or more of nitrogen and argon, and the gas flow rate is 10-50 mL / min. -1 .
[0017] Furthermore, in step (3), the heat treatment temperature is 400-600 ℃, and the heating rate is 2-10 ℃ min. -1 The heat preservation time is 2-6 hours.
[0018] Furthermore, an ultrastable metal-doped aluminum fluoride catalyst was prepared using the above preparation method.
[0019] Furthermore, the aforementioned ultrastable metal-doped aluminum fluoride catalyst was applied to photocatalytic carbon dioxide reduction.
[0020] The beneficial effects of this invention are as follows:
[0021] (1) The ultra-stable metal-doped aluminum fluoride catalyst constructed by the in-situ fluorination strategy of the present invention has extreme resistance to acid and alkali corrosion. Unlike traditional MOFs or metal oxides, which are prone to hydrolysis or photocorrosion in the liquid phase, the catalyst prepared by the present invention still maintains its original powder form and crystal structure after being immersed and etched in extremely strong acid and strong alkali solutions for a long time. No dissolution or deactivation of active metals occurs, demonstrating super strong acid and alkali resistance.
[0022] (2) It breaks through the bottleneck of traditional carbon-based polymers being prone to thermal oxidation and etching under oxygen-rich and high-temperature atmospheres. The catalyst of the present invention not only does not collapse under high-temperature inert atmosphere, but also maintains a highly stable structure after repeated calcination at high temperature. It also maintains excellent activity in photocatalytic CO2 reduction reaction and has excellent resistance to thermal oxidation and high-temperature stability.
[0023] (3) Innovation in fluorination process. It avoids the dependence of traditional fluorination reactions on toxic and corrosive reagents and uses the strategy of preparing aluminum fluoride substrate by self-dissolution of fluorine materials in ball mill jars, providing a new path for the green synthesis of heterogeneous catalysts. Attached Figure Description
[0024] Figure 1 This is a scanning electron microscope image of the cobalt-doped aluminum fluoride catalyst prepared in Example 1.
[0025] Figure 2 The image shows the XRD patterns of the cobalt-doped aluminum fluoride catalysts prepared in Comparative Examples 5-8 after pH etching treatment.
[0026] Figure 3 The XRD patterns of the cobalt-doped aluminum fluoride catalysts prepared in Comparative Examples 9-12 after muffle furnace air heat treatment are shown. Detailed Implementation
[0027] An ultra-stable metal-doped aluminum fluoride is prepared by the following steps:
[0028] (1) The aluminum-containing compound is dried and ground to obtain aluminum-containing compound powder;
[0029] (2) The aluminum-containing compound powder obtained in step (1) is mixed with metal salt in ethanol in a certain proportion, and mechanically ball-milled in a ball mill jar made of polytetrafluoroethylene. After drying, a composite precursor containing metal and fluorine is obtained.
[0030] (3) The composite precursor obtained in step (2) is heat-treated in an inert atmosphere to obtain a metal-doped aluminum fluoride catalyst.
[0031] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.
[0032] Example 1
[0033] (1) Place Al(OH)3 in a vacuum freeze dryer and dry for 24 h. After drying, take it out and grind it, and then sieve the powder through a 100-mesh sieve.
[0034] (2) Take 4.0 g of powder, 0.5 g of CoCl2·6H2O, and 50 mL of ethanol from step (1), stir well, and transfer to a ball mill jar. Mill at 450 rpm. -1 The ball mill was operated at a high speed for 8 hours, and then placed in a drying oven at 60 ℃ for drying.
[0035] (3) Place the powder from step (2) in a quartz boat and heat it in a nitrogen atmosphere (20 mL min). -1 ), 500 °C temperature (heating rate 5 °C min) -1 Heat treatment for 3.0 h. Cool to room temperature to obtain cobalt-doped aluminum fluoride catalyst.
[0036] Comparative Example 1
[0037] (1) Place Al(OH)3 in a vacuum freeze dryer and dry for 24 h. After drying, take it out and grind it into powder, and sieve it with a 100 mesh.
[0038] (2) Take 4.0 g of powder, 0.5 g of FeCl2·4H2O and 50 mL of ethanol from step (1), stir well and transfer to a ball mill jar, and mill at 450 rpm min. -1 The ball mill was operated at a high speed for 8 hours, and then placed in a drying oven at 60 ℃ for drying.
[0039] (3) Place the powder from step (2) in a quartz boat and heat it in a nitrogen atmosphere (20 mL min). -1 ), 500 °C temperature (heating rate 5 °C min) -1 Heat treatment for 3.0 h. Cool to room temperature to obtain iron-doped aluminum fluoride catalyst.
[0040] Comparative Example 2
[0041] (1) Place Al(OH)3 in a vacuum freeze dryer and dry for 24 h. After drying, take it out and grind it, and then sieve the powder through a 100-mesh sieve.
[0042] (2) Take 4.0 g of powder, 0.5 g of NiCl2·6H2O and 50 mL of ethanol from step (1), stir evenly and transfer to a ball mill jar, and mill at 450 rpm min. -1 The ball mill was operated at a high speed for 8 hours, and then placed in a drying oven at 60 ℃ for drying.
[0043] (3) Place the powder from step (2) in a quartz boat and heat it in a nitrogen atmosphere (20 mL min). -1 ), 500 °C temperature (heating rate 5 °C min) -1 Heat treatment for 3.0 h. Cool to room temperature to obtain nickel-doped aluminum fluoride catalyst.
[0044] Comparative Example 3
[0045] (1) Place Al(OH)3 in a vacuum freeze dryer and dry for 24 h. After drying, take it out and grind it, and then sieve the powder through a 100-mesh sieve.
[0046] (2) Take 4.0 g of powder, 0.5 g of CuCl2, and 50 mL of ethanol from step (1), stir well, and transfer to a ball mill jar. Mill at 450 rpm. -1 The ball mill was operated at a high speed for 8 hours, and then placed in a drying oven at 60 ℃ for drying.
[0047] (3) Place the powder from step (2) in a quartz boat and heat it in a nitrogen atmosphere (20 mL min). -1 ), 500 °C temperature (heating rate 5 °C min) -1 Heat treatment for 3.0 h. Cool to room temperature to obtain copper-doped aluminum fluoride catalyst.
[0048] Comparative Example 4
[0049] (1) Place Al(OH)3 in a vacuum freeze dryer and dry for 24 h. After drying, take it out and grind it, and then sieve the powder through a 100-mesh sieve.
[0050] (2) Take 4.0 g of powder, 0.5 g of ZnCl2, and 50 mL of ethanol from step (1), stir well, and transfer to a ball mill jar. Mill at 450 rpm. -1 The ball mill was operated at a high speed for 8 hours, and then placed in a drying oven at 60 ℃ for drying.
[0051] (3) Place the powder from step (2) in a quartz boat and heat it in a nitrogen atmosphere (20 mL min). -1 ), 500 °C temperature (heating rate 5 °C min) -1Heat treatment for 3.0 h. Cool to room temperature to obtain zinc-doped aluminum fluoride catalyst.
[0052] Comparative Example 5
[0053] The sample obtained in Example 1 was placed in 50 mL of pH=1 aqueous solution and stirred continuously for 36 h. The sample was then washed with water and ethanol and dried.
[0054] Comparative Example 6
[0055] The sample obtained in Example 1 was placed in 50 mL of pH=2 aqueous solution and stirred continuously for 36 h. The sample was then washed with water and ethanol and dried.
[0056] Comparative Example 7
[0057] The sample obtained in Example 1 was placed in 50 mL of pH=13 aqueous solution and stirred continuously for 36 h. The sample was then washed with water and ethanol and dried.
[0058] Comparative Example 8
[0059] The sample obtained in Example 1 was placed in 50 mL of pH=14 aqueous solution and stirred continuously for 36 h. The sample was then washed with water and ethanol and dried.
[0060] Comparative Example 9
[0061] The sample obtained in Example 1 was heat-treated in an air atmosphere at 200 °C for 3 h.
[0062] Comparative Example 10
[0063] The sample obtained in Example 1 was heat-treated in an air atmosphere at 300 °C for 3 h.
[0064] Comparative Example 11
[0065] The sample obtained in Example 1 was heat-treated in an air atmosphere at 400 °C for 3 h.
[0066] Comparative Example 12
[0067] The sample obtained in Example 1 was heat-treated in an air atmosphere at 500 °C for 3 h.
[0068] Data Analysis:
[0069] Figure 1 This is a scanning electron microscope (SEM) image of the cobalt-doped aluminum fluoride catalyst described in Example 1. As can be seen from the image, the sample calcined at 500 °C exhibits typical α-AlF3 crystal growth characteristics, displaying a relatively regular hexahedral structure. The sample particles show good dispersion and no obvious agglomeration. The particle size distribution is uniform, with well-developed crystal faces and smooth surfaces.
[0070] To investigate the effects of different metal doping on the photocatalytic CO2 reduction performance of aluminum fluoride supports, the photocatalytic CO2 reduction performance of the samples from Example 1 and Comparative Examples 1-4 was tested, and the results are shown in Table 1. The test results show that among the tested metals (Fe, Co, Ni, Cu, Zn), the Co-doped aluminum fluoride catalyst (Example 1) exhibits the best photocatalytic CO2 reduction performance (yield as high as 15.54 mmol h⁻¹ g⁻¹).
[0071] Table 1. Photocatalytic performance of aluminum fluoride catalysts with different metal doping
[0072] sample <![CDATA[CO production (mmol h −1 g −1 ).]]> Example 1 15.54 Comparative Example 1 2.41 Comparative Example 2 1.52 Comparative Example 3 1.33 Comparative Example 4 1.77
[0073] Figure 2 The XRD patterns of Example 1 and Comparative Examples 5-8 (i.e., Example 1 subjected to acid and alkali etching in solutions with pH = 1, 2, 13, and 14) are shown in Table 2. Their chemical stability was comprehensively evaluated through photocatalytic performance testing. The results are shown in Table 2. After treatment with strong acid and strong alkali, the photocatalytic performance of the samples remained at a high level. The gas yield after acid etching remained >90%, and the gas yield after alkali treatment remained >80%. Furthermore, the XRD patterns showed that the XRD patterns of the acid- and alkali-etched samples were highly consistent with the original sample (Example 1) and perfectly corresponded to the α-AlF3 standard card (PDF#80-1007). This indicates that the cobalt-doped aluminum fluoride catalyst has high acid and alkali corrosion resistance.
[0074] Table 2. Photocatalytic performance of samples after acid and alkali corrosion treatment
[0075] sample <![CDATA[CO production (mmol h −1 g −1 ) <!-- 4 -->]]> Example 1 15.54 Comparative Example 5 14.11 Comparative Example 6 14.24 Comparative Example 7 13.73 Comparative Example 8 12.72
[0076] Figure 3 The XRD patterns of Example 1 and Comparative Examples 9-12 (i.e., Example 1 heat-treated at 200, 300, 400, and 500 °C in air) are shown in Table 3. Photocatalytic performance tests were conducted to comprehensively evaluate their thermal stability. The results are shown in Table 3. The photocatalytic test results quantify the impact of the oxidizing environment on the catalytic performance. After heat treatment, the CO yield of the samples remained stable at a high level of over 87%. Simultaneously, the XRD patterns show that all treated samples maintained the complete α-AlF3 crystal phase (PDF#80-1007). The above analysis indicates that this aluminum fluoride catalyst exhibits excellent oxidation resistance and thermal stability.
[0077] Table 3. Photocatalytic performance of samples after heat treatment in air atmosphere
[0078] sample <![CDATA[CO production (mmol h −1 g −1 )]]> Example 1 15.54 Comparative Example 9 14.22 Comparative Example 10 13.85 Comparative Example 11 13.64 Comparative Example 12 14.55
[0079] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.
Claims
1. A method for preparing an ultrastable metal-doped aluminum fluoride catalyst, characterized in that, The preparation method includes the following steps: (1) The aluminum-containing compound is dried and ground to obtain aluminum-containing compound powder; (2) The aluminum-containing compound powder obtained in step (1) is mixed with metal salt in ethanol in proportion, and mechanically ball-milled in a ball mill jar made of polytetrafluoroethylene. After drying, a composite precursor containing metal and fluorine is obtained. (3) The composite precursor obtained in step (2) is heat-treated in an inert atmosphere to obtain a metal-doped aluminum fluoride catalyst.
2. The method for preparing an ultrastable metal-doped aluminum fluoride catalyst according to claim 1, characterized in that: The aluminum-containing compound in step (1) includes one or more of aluminum oxide, aluminum hydroxide, or aluminum hydroxyoxide, and the drying method includes one or more of room temperature drying, heating drying, and freeze drying; the drying temperature range is -40 to 80 ℃.
3. The method for preparing an ultra-stable metal-doped aluminum fluoride catalyst according to claim 1, characterized in that: The grinding method in step (1) is one or more of manual grinding and mechanical grinding, and the ground material is passed through a 60-200 mesh sieve.
4. The method for preparing an ultrastable metal-doped aluminum fluoride catalyst according to claim 1, characterized in that: In step (2), the metal salt includes one or more of iron, cobalt, nickel, copper, and zinc salts; the mass ratio of the aluminum compound powder to the metal salt is 4:0.5, and the amount of ethanol added is 50-200 mL.
5. The method for preparing an ultrastable metal-doped aluminum fluoride catalyst according to claim 1, characterized in that: In step (2), the ball milling speed is 300-600 rpm. -1 The ball milling time is 8-24 hours.
6. The method for preparing an ultrastable metal-doped aluminum fluoride catalyst according to claim 1, characterized in that: The drying method after ball milling in step (2) is one or more of room temperature drying and heated drying, with a drying temperature of 20-80 ℃.
7. The method for preparing an ultrastable metal-doped aluminum fluoride catalyst according to claim 1, characterized in that: The inert atmosphere used in the heat treatment in step (3) is one or more of nitrogen and argon, and the gas flow rate is 10-50 mL / min. -1 .
8. The method for preparing an ultrastable metal-doped aluminum fluoride catalyst according to claim 1, characterized in that: In step (3), the heat treatment temperature is 400-600 ℃, and the heating rate is 2-10 ℃ min. -1 The heat preservation time is 2-6 hours.
9. A super-stable metal-doped aluminum fluoride catalyst, characterized in that, It is prepared using the method described in any one of claims 1 to 8.
10. The application of the ultra-stable metal-doped aluminum fluoride catalyst as described in claim 9 in photocatalytic carbon dioxide reduction.