Method for preparing bimetallic catalyst through oxidation-reduction strategy and application
The preparation of bimetallic catalysts through redox strategies has solved the problems of complex preparation process and harsh conditions in the prior art, and achieved the effect of preparing efficient catalysts under mild conditions, reducing costs and environmental pollution.
Patent Information
- Application Number
- CN202411499858.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-25
- Publication Date
- 2025-02-07
AI Technical Summary
The existing bimetallic catalyst preparation methods usually rely on complex process flow and harsh experimental conditions, making it difficult to prepare uniform bimetallic catalysts, and there are problems of high preparation costs and environmental pollution in industrial applications.
Bimetallic catalysts are prepared by redox strategy, reducing metal ions M1 are anchored using vacancy on the support, and oxidized metal ions M2 are captured through redox reaction to form bimetallic nanoclusters or particles, simplifying the preparation process and reduce the harshness of reaction conditions.
The preparation of efficient bimetallic catalysts under relatively simple and mild conditions is achieved, reducing the preparation cost, avoiding environmental pollution, and achieving thermodynamic ultimate catalytic performance in a lower temperature range.
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of catalytic material preparation, and in particular to a method for preparing a bimetallic catalyst through a redox strategy. Background Art
[0002] Bimetallic compound catalysts have been widely used in many fields due to their unique catalytic properties, especially in catalytic reforming, electrocatalytic synthesis, catalytic conversion of light alkanes, etc. Among them, bimetallic catalysts, especially tin-platinum (Sn-Pt) catalysts, have made significant progress in industrial applications such as catalytic reforming and propane dehydrogenation.
[0003] However, many bimetallic catalytic systems do not exist in the form of homogeneous alloys, but often form core-shell structures or other thermodynamically advantageous heterogeneous structures, which makes it difficult to prepare uniform bimetallic catalysts. Although some researchers have introduced unconventional technical means in the preparation process, such as surface plasmon resonance and pulsed laser ablation, these methods usually rely on complex process flows and harsh experimental conditions, and are difficult to be widely promoted and applied.
[0004] In addition, some researchers have proposed some new universal preparation methods. For example, the surface inorganic metal chemical synthesis method proposed by Professor Ding Kunlun's research group successfully prepared a series of Ir-M (M=Fe, Co, Ni, Cu, Pd, Pt) bimetallic nanoparticle catalysts by sequentially adsorbing different cations and anions. However, the metal salts used in this method require specific chloride salts, and different metal salts also require different organic solvents to assist, which to a certain extent limits the batch synthesis and industrial application of catalysts. Summary of the invention
[0005] The present invention aims to overcome the deficiencies in the prior art and provide a relatively simple and mild method for preparing a bimetallic catalyst. By using the method of the present invention, the vacancies on the carrier are used to anchor the reducing metal ions M1, and the oxidizing metal ions M2 are captured by redox reactions to form bimetallic nanoclusters or particles, thereby simplifying the preparation process and reducing the harshness of the reaction conditions. In order to verify the universality of the redox strategy, the present invention prepared a variety of Sn-M, Cr-M and Fe-M bimetallic catalyst systems. At the same time, two platinum complex precursors [PtCl4] with different charges were selected. 2- and [Pt(NH3)4] 2+, used to prepare Sn-Pt catalysts; through structural characterization, it was found that the two Sn-Pt catalysts have similar structural features; in addition, using carbon monoxide oxidation and propane dehydrogenation reactions as probe reactions, the experimental results showed that the two catalysts exhibited similar effects in terms of catalytic performance; this result further proves the wide applicability and effectiveness of the method of the present invention.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing a bimetallic catalyst by a redox strategy and its application, wherein the catalyst carrier is Al2O3 or SiO2; The carrier vacancies are prepared by treating Al2O3 or SiO2 with alkali solution of appropriate concentration; The reducing metal ion M1 is anchored in the vacancy by strong electrostatic adsorption and vacuum dried to obtain the precursor 1; The precursor 1 is dispersed in an ethanol solution, a metal salt of the metal M2 is dissolved in deionized water or an ethanol solution, added to the solution, and stirred to promote a redox reaction, thereby obtaining a precursor 2; The precursor 2 is centrifuged, washed, and vacuum dried to obtain a bimetallic catalyst.
[0007] Based on the above technical solution, the alkali solution is one or a mixture of KOH, NaOH, LiOH, and CsOH solutions.
[0008] Based on the above technical solution, the concentration of the aforementioned alkali solution is 0.0001-1 mol / mL.
[0009] Based on the above technical solution, the alkali treatment time is 12h-144h.
[0010] Based on the above technical solution, the loading amount of metal M1 is 0.001-1 mol%.
[0011] Based on the above technical solution, the vacuum drying temperature of the precursor 1 is 60-180°C, and the drying time is 6-36h.
[0012] Based on the above technical solution, the redox reaction time is controlled within 0.5-36h.
[0013] On the basis of the above technical solution, the centrifugal speed of the precursor 2 is 3000-10000r / min.
[0014] On the basis of the above technical solution, the vacuum drying temperature of the precursor 2 is 60-180°C, and the drying time is 6-36h.
[0015] The present invention provides a method for preparing the bimetallic catalyst, and selects Sn-Pt catalysts prepared from two platinum complex precursors with different charges. Characterization shows that they have similar structures. Using carbon monoxide oxidation and propane dehydrogenation reactions as probe reactions, it is found that the two catalysts have similar catalytic properties.
[0016] Compared with the existing bimetallic catalyst technology, the beneficial effects are reflected in the following aspects: The redox strategy proposed in the present invention loads two metals in steps. The first metal loading adopts strong electrostatic adsorption method with ethanol as solvent to avoid the hydrolysis of metal ion M1, such as Sn 2+ The second metal is captured by a redox strategy, using the redox reaction between M1 and M2 ions to capture the metal ion M2, avoiding the poor solubility of the second metal in ethanol solution and the problem of failure to load due to differences in the charge of metal ions.
[0017] The catalyst preparation method provided by the present invention is carried out at room temperature except for drying, thus avoiding high temperature or harsh conditions such as surface plasma resonance, pulsed laser ablation and the like in the existing bimetallic catalyst preparation method.
[0018] The catalyst preparation method provided by the invention adopts ethanol as solvent, partially dissolves metal salts insoluble in ethanol in water, the solvent is non-toxic, and the pollution to the environment during the preparation process is avoided, and the preparation cost is low.
[0019] The catalyst prepared by the present invention can achieve thermodynamic limit catalytic performance within a relatively low temperature range, and the catalyst preparation method provided by the present invention provides a new idea for the preparation of bimetallic catalysts in industry. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 The X-ray diffraction and nuclear magnetic resonance spectra of the vacancy-containing carrier prepared in Example 1, wherein the control sample is an untreated carrier.
[0021] Figure 2 This is the nuclear magnetic resonance spectrum of the precursor 1 prepared in Example 1, wherein the comparative sample is a carrier containing vacancies.
[0022] Figure 3 This is the X-ray photoelectron spectrum of the bimetallic catalyst prepared in Example 1.
[0023] Figure 4 This is the X-ray photoelectron spectrum of the bimetallic catalyst prepared in Example 2.
[0024] Figure 5 This is the X-ray photoelectron spectrum of the bimetallic catalyst prepared in Example 4.
[0025] Figure 6 The propane dehydrogenation performance of the bimetallic catalysts prepared in Examples 1 and 2. DETAILED DESCRIPTION
[0026] In order to further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose of the invention, the following is a method for preparing a bimetallic catalyst according to a redox strategy proposed by the present invention and its specific implementation, characteristics and effects in combination with preferred embodiments. The preparation method of the bimetallic compound catalyst is as follows: 1. The structure of carrier vacancies. The carrier can be made of Al2O3, SiO 2； In this step, the carrier is treated with alkali solution at a concentration of 0.001-1 mol / mL for a treatment time of 12 h-144 h, and then centrifuged, washed, and dried to obtain a carrier containing different vacancies; Preferably, the amount of alkali solution and the carrier in this step is 0.001 mol of alkali solution per 2 g of carrier, and the treatment time is preferably 72 hours.
[0027] 2. Use strong electrostatic adsorption to anchor the metal ion M1 in the vacancy. The metal ion M1 can be Sn 2+ , Fe 2+ Cr 3+ etc. with reducing metal cations; In this step, the metal ion M1 solution is dispersed into the ethanol solution. Preferably, the amount of the metal ion M1 and the vacancy-containing carrier is in the ratio of 0.0188 mol of the metal ion M1 per 0.5 g of the vacancy-containing carrier. The strong electrostatic adsorption treatment temperature is 80°C.
[0028] 3. Use redox reaction to capture the second metal, which should be an oxidizing metal ion or complex, such as Cu 2+ 、Au 3+ , [PtCl4] 2- 、[Pt(NH3)4] 2+ wait; In this step, the precursor 1 loaded with metal ions M1 is dispersed in an ethanol solution, and an alcohol solution or an aqueous solution of metal ions M2 is added. Preferably, the ratio of metal ions M2 to metal ions M1 is 1:1. Stirring allows the metal ions M1 and metal ions M2 to fully react to capture the metal ions M2. Preferably, the redox reaction time is more than 8 hours.
[0029] The present invention is further described in detail below in conjunction with embodiments. Example Example 1
[0030] 1. Put 10g Al2O3 into a 250ml conical flask, add 0.004mol NaOH solution, add 200ml deionized water, stir at room temperature for 72h, centrifuge and wash until neutral, put into an 80°C oven for drying to obtain a carrier containing vacancies. Its X-ray diffraction and nuclear magnetic resonance spectra are as follows: Figure 1 shown.
[0031] 2. Take 0.5g of the carrier containing vacancies, add 2ml of anhydrous ethanol, add 0.0188mol of SnCl2 ethanol solution, stir evenly, and put it into a vacuum drying oven at 100°C to dry (strong electrostatic adsorption) to obtain precursor 1. The NMR spectrum is as follows: Figure 2 shown.
[0032] 3. Precursor 1 was dispersed in 15 ml of ethanol solution, 0.0188 mol of Na2PtCl4 ethanol solution was added, stirred for 12 h, and dried in a vacuum oven at 100°C to obtain a bimetallic catalyst Sn-Pt-Cl / Al2O3. Its X-ray photoelectron spectrum is shown in Figure 3 shown. Example 2
[0033] 1. Put 10g Al2O3 into a 250ml conical flask, add 0.004mol NaOH solution, add 200ml deionized water, stir at room temperature for 72h, centrifuge and wash until neutral, put it in an oven at 80°C for drying to obtain a carrier containing vacancies.
[0034] 2. Take 0.5 g of the carrier containing vacancies, add 2 ml of anhydrous ethanol, add 0.0188 mol of SnCl2 ethanol solution, stir evenly, and put it into a vacuum drying oven at 100°C to dry (strong electrostatic adsorption effect) to obtain precursor 1.
[0035] 3. Precursor 1 was dispersed in 15 ml of ethanol solution, 0.0188 mol of [Pt(NH3)4](NO3)2 aqueous solution was added, stirred for 24 h, and dried in a vacuum oven at 100°C to obtain the bimetallic catalyst Sn-Pt-NH3 / Al2O3. Its X-ray photoelectron spectrum is shown in Figure 4 shown. Example 3
[0036] 1. Put 10g SiO2 into a 250ml conical flask, add 0.001mol NaOH solution, add 200ml deionized water, stir at room temperature for 144h, centrifuge and wash until neutral, put it in a 100°C oven for drying to obtain a carrier containing vacancies.
[0037] 2. Take 1g of the carrier containing vacancies, add 2ml of anhydrous ethanol, add 0.0188mol of SnCl2 ethanol solution, stir evenly, and put it into a vacuum drying oven at 80°C to dry (strong electrostatic adsorption effect) to obtain precursor 1.
[0038] 3. Disperse the precursor 1 into 15 ml of ethanol solution, add 0.0188 mol of PdCl2 ethanol solution, stir for 12 h, and dry in a vacuum drying oven at 80 ° C to obtain the bimetallic compound catalyst Sn-Pd / SiO2. Example 4
[0039] 1. Put 10g Al2O3 into a 250ml conical flask, add 0.002mol KOH solution, add 200ml deionized water, stir at room temperature for 48h, centrifuge and wash until neutral, put it in an oven at 80°C for drying to obtain a carrier containing vacancies.
[0040] 2. Take 1g of the carrier containing vacancies, add 2ml of anhydrous ethanol, add 0.0188mol of CrCl3 ethanol solution, stir evenly, and put it into a vacuum drying oven at 80°C to dry (strong electrostatic adsorption effect) to obtain precursor 1.
[0041] 3. Precursor 1 was dispersed in 15 ml of ethanol solution, 0.0376 mol of Fe(NO3)3 ethanol solution was added, stirred for 12 h, and dried in a vacuum oven at 80°C to obtain a bimetallic compound catalyst Cr-Fe / Al2O3. Its X-ray photoelectron spectrum is as follows: Figure 5 shown. Example 5
[0042] 1. Put 10g Al2O3 into a 250ml conical flask, add 0.004molCsOH solution, add 200ml deionized water, stir at room temperature for 24h, centrifuge and wash until neutral, put it in an 80°C oven for drying to obtain a carrier containing vacancies.
[0043] 2. Take 0.5 g of the carrier containing vacancies, add 2 ml of anhydrous ethanol, add 0.0188 mol of FeCl2 ethanol solution, stir evenly, and put it into a vacuum drying oven at 100°C to dry (strong electrostatic adsorption effect) to obtain precursor 1.
[0044] 3. Disperse the precursor 1 into 15 ml of ethanol solution, add 0.0376 mol of AuCl3 ethanol solution, stir for 12 h, and dry in a vacuum drying oven at 80 ° C to obtain the bimetallic catalyst Fe-Ag / Al2O3. Example 6
[0045] 1. Put 10g SiO2 into a 250ml conical flask, add 0.008mol NaOH solution, add 200ml deionized water, stir at room temperature for 12h, centrifuge and wash until neutral, put it in a 100°C oven for drying to obtain a carrier containing vacancies.
[0046] 2. Take 1g of the carrier containing vacancies, add 2ml of anhydrous ethanol, add 0.0376mol of SnCl2 ethanol solution, stir evenly, and put it into a vacuum drying oven at 80°C to dry (strong electrostatic adsorption effect) to obtain precursor 1.
[0047] 3. Disperse the precursor 1 into 15 ml of ethanol solution, add 0.0376 mol CuCl2 ethanol solution, stir for 12 h, and dry in a vacuum drying oven at 60 ° C to obtain the bimetallic catalyst Sn-Cu / Al2O3. Example 7
[0048] 1. Put 10g Al2O3 into a 250ml conical flask, add 0.01mol NaOH solution, add 200ml deionized water, stir at room temperature for 8h, centrifuge and wash until neutral, put it in an 80°C oven for drying to obtain a carrier containing vacancies.
[0049] 2. Take 0.5 g of the carrier containing vacancies, add 2 ml of anhydrous ethanol, add 0.0376 mol of CrCl3 ethanol solution, stir evenly, and put it into a vacuum drying oven at 80°C to dry (strong electrostatic adsorption effect) to obtain precursor 1.
[0050] 3. Disperse the precursor 1 into 15 ml of ethanol solution, add 0.0376 mol of Na2PtCl4 ethanol solution, stir for 12 h, and dry in a vacuum drying oven at 80 ° C to obtain the bimetallic catalyst Cr-Pt-Cl / Al2O3. Example 8
[0051] 1. Put 10g SiO2 into a 250ml conical flask, add 0.003mol NaOH solution, add 200ml deionized water, stir at room temperature for 144h, centrifuge and wash until neutral, put it in an 80°C oven for drying to obtain a carrier containing vacancies.
[0052] 2. Take 1g of the carrier containing vacancies, add 2ml of anhydrous ethanol, add 0.0188mol of CrCl3 ethanol solution, stir evenly, and put it into a vacuum drying oven at 80°C to dry (strong electrostatic adsorption effect) to obtain precursor 1.
[0053] 3. Disperse the precursor 1 into 15 ml of ethanol solution, add 0.0188 mol (CH3CO2)3Mn ethanol solution, stir for 12 h, and dry in a vacuum drying oven at 80 ° C to obtain the bimetallic catalyst Cr-Mn / SiO2.
[0054] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. The contents not described in detail in this specification belong to the prior art known to professionals in the field. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.
Claims
1. A method for preparing a bimetallic catalyst by a redox strategy and its application, characterized in that: The method utilizes vacancies on a carrier to anchor a reducing metal ion M1, and captures an oxidizing metal ion M2 through a redox reaction, thereby obtaining a bimetallic catalyst.
2. The method for synthesizing a bimetallic catalyst according to claim 1, characterized in that: The vacancy-containing carrier is obtained by treating Al2O3 or SiO2 with alkali, and the alkali is a single solution of KOH, NaOH, LiOH, CsOH solution or a mixed solution thereof.
3. The method for synthesizing a bimetallic catalyst according to claim 1, characterized in that: The vacancy-containing carrier comprises cation vacancies.
4. The method for synthesizing a bimetallic catalyst according to claim 1, characterized in that: The M1 is a reducing metal cation, the metal cation is Sn 2+ Cr 3+ , Fe 2+ One of them.
5. The method for synthesizing a bimetallic catalyst according to claim 1, characterized in that: The M2 is an oxidizing metal ion or complex ion, and the metal ion or complex ion is Mn 3+ , Fe 3+ 、AuCl3 - , [PtCl4] 2- 、[Pt(NH3)4] 2+ One of them.
6. The method for synthesizing a bimetallic catalyst according to claim 1, characterized in that: A redox reaction occurs between the metal ion M1 and the metal ion M2 to generate a bimetallic catalyst, wherein the metal ion M1 is oxidized to a higher valence state and the metal ion M2 is reduced to a lower valence state.
7. The method for synthesizing a bimetallic catalyst according to claim 1, characterized in that: The metal ion M2 is a positively charged ion or a negatively charged ion.
8. The method for synthesizing a bimetallic catalyst according to claim 1, characterized in that: In the preparation process, ethanol is used as a dispersant for anchoring M1 and capturing M2. In the process of capturing M2, redox reaction is used to avoid the solubility problem of M2 in ethanol, that is, M2 is a salt insoluble in ethanol.
9. The bimetallic catalyst probe reaction according to any one of claims 1 to 8 is evaluated as carbon monoxide oxidation and propane dehydrogenation reaction.