A supported cheap CuNi bimetallic catalyst and its application in nitrile reduction reaction

Abstract

The application relates to a supported cheap CuNi bimetallic catalyst and a preparation method thereof, which is prepared by uniformly mixing copper chloride and nickel chloride, adding a graphene oxide (GO) solution, neutralizing the mixed solution by using an alkali solution to adjust the pH value of the mixed solution, heating and stirring the mixed solution, dropwise adding a sodium borohydride solution and continuously stirring, cooling and ripening, then removing the upper solution, centrifugally treating and washing the lower precipitate for multiple times, and drying and crushing. The supported cheap bimetallic Cu1Ni1@rGO catalyst has a stable chemical structure, the dispersion of the nanoparticles can be improved by loading the metal on the graphene oxide, the catalyst has high catalytic activity, stability and catalytic efficiency when being used in the hydrogenation reduction reaction of nitrile and the like, and the recyclable use rate of the catalyst in the reaction can be improved.

Description

Technical Field

[0001] This invention relates to the field of catalysts, and more specifically, to the preparation of a supported, inexpensive CuNi bimetallic catalyst and its application in nitrile reduction reactions. Background Technology

[0002] Amines are an important class of organic compounds and crucial raw materials for the fine chemical industry. Utilizing abundant and inexpensive metals as catalysts, the hydrogenation reduction of nitrile with molecular hydrogen is a highly attractive, atom-economical, and sustainable selective route to primary amines. Currently, expensive and difficult-to-obtain precious metals such as palladium (Pd), gold (Au), ruthenium (Ru), rhodium (Rh), iridium (Ir), and platinum (Pt) are mainly used as catalysts for the hydrogenation reduction of nitrile to amines. To reduce costs and the amount of precious metals used, the use of abundant, inexpensive, and readily available metals such as Cu and Ni, supported on reduced graphene oxide (Cu1Ni1@rGO), as catalysts is of great significance for the hydrogenation reduction of nitrile to amines. Therefore, Cu1Ni1@rGO ​​shows broad application prospects in the nitrile hydrogenation reduction catalysis industry. Simultaneously, developing a catalyst with high catalytic activity, stability, and efficiency, while also being recyclable, is a major problem that urgently needs to be solved. Summary of the Invention

[0003] This invention relates to a supported, inexpensive CuNi bimetallic catalyst and its preparation method, specifically a supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalyst. The method involves uniformly mixing copper chloride and nickel chloride, adding a graphene oxide (GO) solution to achieve uniform mixing, neutralizing and adjusting the pH of the mixture with an alkaline solution to obtain a mixed solution, heating and stirring the solution, adding sodium borohydride solution dropwise while continuing stirring, cooling and aging, removing the upper layer, and repeatedly centrifuging and washing the lower precipitate, followed by drying and crushing to obtain the final product. The supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalyst exhibits a stable chemical structure. Supporting the metal on graphene oxide significantly improves the dispersibility of nanoparticles. When used in the hydrogenation reduction reactions of substances such as nitriles, it demonstrates high catalytic activity, stability, and catalytic efficiency, and also improves the recyclability of the catalyst in the reaction.

[0004] This invention relates to a method for preparing a supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalyst, comprising the following steps:

[0005] 1) Take copper chloride and nickel chloride solutions and stir to mix them completely and evenly;

[0006] 2) Add the graphene oxide (GO) solution dropwise and sonicate to ensure that the graphene oxide solution is completely and uniformly mixed with the copper chloride and nickel chloride solutions.

[0007] 3) Neutralize and adjust the pH of the above mixed solution to 7-9 with alkali solution;

[0008] 4) Dissolve sodium borohydride (NaBH4) in water to obtain a sodium borohydride solution for later use;

[0009] 5) Heat the above mixed solution and stir magnetically, then add sodium borohydride solution dropwise while continuing to stir; after the reaction is complete, cool to room temperature and allow to stand for aging.

[0010] 6) Remove the upper layer solution, centrifuge the lower layer precipitate, remove the upper layer solution after centrifugation, retain the precipitate at the bottom of the centrifuge tube, and wash the precipitate; after multiple centrifugation and washing, remove the impurities in the precipitate to obtain the supported low-cost bimetallic Cu1Ni1@rGO ​​catalyst.

[0011] 7) The catalyst prepared by vacuum drying is crushed into fine black powder particles.

[0012] In step 1), copper chloride and nickel chloride are CuCl2·2H2O and NiCl2·6H2O hydrates, respectively, with a molar ratio of 1:1. The concentrations of the copper chloride and nickel chloride solutions are 0.005-0.02 mol / L and 0.005-0.02 mol / L, respectively. In step 2), the mass ratio of copper chloride, nickel chloride, and graphene oxide (GO) is (5-30):(10-40):(60-400); the concentration of the graphene oxide (GO) solution is 1.0-4.0 mg / mL. In step 3), the alkaline solution is a sodium hydroxide solution with a concentration of 0.2-1.0 mol / L; the pH value is adjusted to 8. In step 4), sodium borohydride is dissolved in deionized water to prepare a concentration of 0.5-1.5 mol / L. In step 5), the mixture is heated from room temperature to 70℃-90℃ at a rate of 1-3℃ / min; sodium borohydride solution is added dropwise and the mixture is magnetically stirred at the above temperature for 2-4 hours, then allowed to stand for 6-18 hours for aging. In step 6), the supernatant is removed, and the lower precipitate is placed in a centrifuge tube and centrifuged for 10-30 minutes at a speed of 10000-16000 rpm. After centrifugation, the supernatant is removed, and the precipitate at the bottom of the centrifuge tube is retained. The precipitate is washed with deionized water at least 3 times, centrifuged for 10-30 minutes to remove the supernatant, and then washed with anhydrous ethanol at least 3 times, centrifuged for 10-30 minutes to remove the supernatant. This process completely removes other impurities from the precipitate, yielding the supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalyst. In step 7), the vacuum drying process includes: placing the obtained catalyst in a vacuum drying oven, and when the vacuum degree of the vacuum drying oven is 0, gradually increasing the temperature from room temperature to 50-80℃, and vacuum drying for 18-30 hours; when the vacuum drying oven cools to room temperature, take out the prepared catalyst, grind it thoroughly into a fine black powder with a quartz grinder, weigh it, and set it aside.

[0013] The present invention also relates to a supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalyst prepared by the method described above.

[0014] As mentioned above, the application of supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalysts in hydrogenation reduction reactions, especially the application of substances such as nitriles in hydrogenation reduction reactions.

[0015] Beneficial effects:

[0016] The supported low-cost bimetallic CuNi catalyst described in this invention is a supported low-cost bimetallic Cu1Ni1@rGO ​​catalyst. The advantages of the supported low-cost bimetallic nanoparticle catalyst are: (1) Compared to single metal nanoparticles, it has greater tunability; the particle size and morphology of the nanoparticles can be controlled by adjusting the relative ratio of the two metals, resulting in a synergistic effect between the two metal atoms; (2) Electrons not only transfer between the two metal atoms but also compete for transfer at the interface between the two atoms and reduced graphene oxide, which is beneficial for controlling the electronic state of active atoms and improving their catalytic activity; (3) The introduction of transition metal ions can induce different exposure surfaces in the nanocatalyst, thereby regulating its catalytic activity; (4) The supported low-cost bimetallic Cu1Ni1@rGO ​​catalyst has a stable chemical structure and good electrical conductivity, showing good application prospects in electrocatalysis and other fields; (5) Copper and nickel are both low-cost transition metals, and these two metal elements are abundant in the Earth's crust, greatly reducing the cost of catalyst preparation; (6) The catalyst is magnetic and can be separated by centrifugation or magnetic force, resulting in high recycling rate. The advantages of graphene oxide (GO) as a supported substrate are as follows: GO has a large surface area and numerous hydroxyl (-OH), carbonyl (-C=O), and carboxyl (-COOH) groups on its surface, making it an excellent dispersion carrier. It provides significant support and anchoring for alloy nanoparticles, helping to control the size and distribution of metal particles formed during synthesis, thus achieving excellent monodispersion. Therefore, loading metals onto graphene oxide can significantly improve the dispersibility of nanoparticles, reduce their aggregation during catalysis, enhance their catalytic activity and efficiency, and also improve the recyclability of the catalyst in the reaction.

[0017] The supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalyst obtained in this invention exhibits excellent conversion and selectivity in the hydrogenation reduction catalysis of nitriles. In particular, after multiple cycles, its conversion rate remains at 95% and its selectivity remains at 100%, indicating that the catalyst has good catalytic activity and stability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 Transmission electron microscopy (TEM) image of Cu1Ni1@rGO;

[0020] Figure 2Here is a high-resolution transmission electron microscope image of Cu1Ni1@rGO;

[0021] Figure 3 X-ray powder diffraction patterns of Cu1Ni1@rGO, Cu@rGO, and Ni@rGO;

[0022] Figure 4 The catalytic conversion and selectivity of Cu1Ni1@rGO@rGO;

[0023] Figure 5 (a) TEM image of Cu1Ni1@rGO ​​after 10 cycles, with insets showing its particle size distribution; (b) HRTEM image, (c) EDS image and (d) XRD pattern before and after 10 cycles;

[0024] Figure 6 This is a structural diagram of graphene oxide and its supported metal. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and technical features described in this application can be combined with each other. It should also be pointed out that, unless otherwise indicated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms "comprising" or "including" and similar words used in this invention refer to elements or objects preceding the word that encompass the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0026] Example 1: Preparation of a supported, low-cost bimetallic Cu1Ni1@rGO ​​catalyst

[0027] (1) Preparation method of supported low-cost bimetallic Cu1Ni1@rGO ​​catalyst:

[0028] 1. Add 10 mL of 0.01 mol / L copper chloride (CuCl2·2H2O) and nickel chloride (NiCl2·6H2O) solution to a round-bottom flask, and stir magnetically to mix the copper chloride and nickel chloride completely and evenly. The solution is transparent dark green.

[0029] 2. Add 40 mL of 2.0 mg / mL graphene oxide (GO) solution dropwise into the round-bottom flask mentioned above, while simultaneously sonicating. The dropping rate is 60-80 drops per minute. After the addition is complete, continue sonicating for 2 hours to ensure that the graphene oxide solution is completely and uniformly mixed with the copper chloride and nickel chloride solutions.

[0030] 3. Neutralize and adjust the pH of the mixed solution in the flask to 8 with 0.5 mol / L sodium hydroxide solution. At this point, the solution turns dark green.

[0031] 4. Accurately weigh 1.5132g of sodium borohydride (NaBH4) and dissolve it in 50mL of deionized water to prepare a sodium borohydride solution with a molar concentration of 0.8mol / L. Let it stand for later use.

[0032] 5. Place the round-bottom flask in an oil bath and heat with magnetic stirring, gradually increasing the temperature from room temperature to 80°C at a rate of 2°C / min. Using a syringe, add 2 mL of freshly prepared 0.8 mol / L sodium borohydride solution dropwise into the round-bottom flask over 30 min. The solution will gradually change from dark green to black. Stir magnetically for 3 h at an oil bath temperature of 80°C. After the reaction is complete, allow it to cool naturally to room temperature and let it stand overnight for 12 h for aging.

[0033] 6. Remove the upper layer of solution from the round-bottom flask, place the lower precipitate in a centrifuge tube and centrifuge for 20 min at a speed of 14000 rpm. After centrifugation, remove the upper layer of solution from the centrifuge tube, retain the precipitate at the bottom of the centrifuge tube, wash the precipitate with deionized water at least 3 times, centrifuge for 20 min to remove the upper layer of solution, wash with anhydrous ethanol at least 3 times, centrifuge for 20 min to remove the upper layer of solution, and completely remove other impurities from the precipitate to obtain the supported bimetallic Cu1Ni1@rGO ​​catalyst.

[0034] 7. Place the catalyst in a vacuum drying oven. When the vacuum level in the oven reaches 0, gradually increase the temperature from room temperature to 60°C and vacuum dry for 24 hours. After the vacuum drying oven cools to room temperature, remove the prepared catalyst, grind it thoroughly into a fine black powder using a quartz grinder, weigh it, and set it aside.

[0035] (2) Characterization of supported low-cost bimetallic Cu1Ni1@rGO ​​catalyst

[0036] 1. Transmission Electron Microscopy (TEM) Characterization: The Cu1Ni1@rGO ​​catalyst was characterized using transmission electron microscopy (TEM), such as... Figure 1 As shown, the catalyst is uniformly dispersed and of uniform size, with no obvious agglomeration. Its particle size is approximately 4.8 nm. Figure 1 As shown.

[0037] 2. High-resolution transmission electron microscopy (HRTEM) characterization: The Cu1Ni1@rGO ​​catalyst was characterized using high-resolution transmission electron microscopy (HRTEM), such as... Figure 2 As shown, its lattice spacing is 0.206 nm.

[0038] 3. X-ray powder diffraction (XRD) characterization: Cu1Ni1@rGO, Cu@rGO, and Ni@rGO were characterized by X-ray powder diffraction (XRD), such as... Figure 3As shown, the characteristic peak of Cu1Ni1@rGO ​​is located between Cu@rGO and Ni@rGO, indicating that the reduced graphene oxide is loaded with Cu and Ni.

[0039] Example 2: Cu1Ni1@rGO-catalyzed hydrogenation reduction reaction of benzonitrile and its derivatives

[0040] (1) Optimization of conditions for Cu1Ni1@rGO ​​catalytic hydrogenation reduction of benzonitrile

[0041] The steps for applying Cu1Ni1@rGO ​​to the hydrogenation reduction reaction of nitrile and its derivatives are as follows: 5 mg of the prepared Cu1Ni1@rGO ​​catalyst and 0.1 mmol of benzonitrile were added to a 100 mL reaction tube. A mixed solution of 4 mL CH3OH and 6 mL deionized water was then added as a solvent. The tube was sonicated for 10 min to ensure uniform dispersion of Cu1Ni1@rGO ​​and benzonitrile in the solvent. H2 at 50 bar was continuously introduced, and the mixture was magnetically stirred at 25 °C for 1 h at a stirring speed of 1200 rpm. After the reaction, the reaction product was extracted using ethyl acetate as the extractant. Qualitative and quantitative analyses were performed using gas chromatography-mass spectrometry (GC-MS). The conversion rate and selectivity of the Cu1Ni1@rGO ​​catalyst in the hydrogenation reduction of benzonitrile to benzylamine were both greater than 99%.

[0042] The experimental factors such as catalyst type, catalyst dosage, solvent type, and hydrogen source type were screened and optimized. The optimal conditions were: 5 mg Cu1Ni1@rGO ​​as catalyst, 4 mL CH3OH and 6 mL deionized water mixed solution, continuous H2 at 50 bar, reaction at 25 °C for 1 h. The conversion rate and selectivity of the catalytic hydrogenation reduction reaction of benzonitrile were both greater than 99%. The experimental results are shown in Table 1.

[0043]

[0044] Table 1 Optimization of conditions for Cu1Ni1@rGO ​​catalytic hydrogenation reduction of benzonitrile

[0045]

[0046] Reaction conditions: benzonitrile (0.1 mmol), catalyst (5 mg), solvent (10 mL), 50 bar H2, reaction at room temperature for 1 h.

[0047] a Catalyst dosage: 2mg b Catalyst dosage: 4mg c Dosage of NH3·BH3: 0.3 mmol d NaBH4 dosage: 0.3 mmol fDosage of HCOONH4: 0.3 mmol.

[0048] (2) Substrate expansion for Cu1Ni1@rGO-catalyzed hydrogenation reduction of benzonitrile

[0049] Under optimal conditions (5 mg Cu1Ni1@rGO ​​as catalyst, 4 mL CH3OH and 6 mL deionized water mixed solution, continuous bubbling of H2 at 50 bar, reaction at 25 °C for 1 h), we investigated the substrate expansion of the hydrogenation reduction reaction of benzonitrile derivatives, and the experimental results are shown in Table 2.

[0050] Table 2. Expanded Substrates for Cu1Ni1@rGO ​​Catalytic Nitrile Reduction Reactions

[0051]

[0052] Reaction conditions: nitrile (0.1 mmol), Cu1Ni1 / rGO (5 mg), CH3OH (4 mL) + H2O (6 mL), 50 bar H2, reaction at 25 °C for 1 h.

[0053] Therefore, the supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalyst has a wide range of applications in hydrogenation reduction reactions. It exhibits good conversion and selectivity for nitrile substances and is not limited to phenyl nitrile substances. It also shows good catalytic effects for heterocyclic nitrile substances such as thiophene and furan, as well as alkyl nitrile compounds.

[0054] (3) Recyclability of Cu1Ni1@rGO ​​catalyzed benzonitrile hydrogenation reduction reaction

[0055] The catalytic performance of Cu1Ni1@rGO ​​in the hydrogenation reduction of benzonitrile was investigated. After 10 cycles, the catalyst maintained a conversion rate of 95% and a selectivity of 100%. Figure 4 As shown, this indicates that the catalyst has good catalytic activity, stability, and recyclability.

[0056] (4) Catalyst recovery

[0057] The recovered catalyst Cu1Ni1@rGO ​​was characterized using TEM, HRTEM, EDX, and XRD. TEM characterization revealed the following (e.g.) Figure 5 a) After 10 cycles, the Cu1Ni1 nanoparticles showed a slight increase in size, approximately 5.9 nm, but remained uniformly distributed on the rGO surface without significant agglomeration, which helps Cu1Ni1@rGO ​​maintain high catalytic activity. HRTEM characterization confirmed this (e.g., Figure 5(b) After 10 cycles of use, the lattice spacing of Cu1Ni1 nanoparticles in the catalyst Cu1Ni1@rGO ​​remained unchanged at 0.206 nm. This is confirmed by EDX characterization (e.g., Figure 5 c) The nanocatalyst Cu1Ni1@rGO ​​is composed of two elements, Cu and Ni, with an atomic ratio of Cu to Ni of approximately 1.09 / 1 in the nanoparticles. Comparison of XRD characterization analyses before and after recycling shows (e.g.) Figure 5 d) The crystallinity of the CuNi nanoparticles remained unchanged before and after use. After centrifuging the reaction mixture to remove the solid catalyst Cu1Ni1@rGO, ICP-OES analysis of the reaction solution showed no significant Cu or Ni leaching (<1 ppm), indicating that the catalytic activity of the catalyst originates from the Cu1Ni1 nanoparticles, rather than from leached Cu or Ni. Therefore, the catalyst Cu1Ni1@rGO ​​exhibits heterogeneous catalytic characteristics.

[0058] To further confirm that the reduction of benzonitrile catalyzed by the Cu1Ni1@rGO ​​nanocatalyst is a heterogeneous catalytic process, the reaction was centrifuged and filtered after 10 min to remove the solid Cu1Ni1@rGO ​​nanocatalyst. Under the same experimental conditions, the filtrate was allowed to react for another 60 min. Real-time monitoring by GC-MS showed that no further conversion of benzonitrile was observed, further demonstrating that the Cu1Ni1@rGO ​​nanocatalyst possesses good stability and heterogeneous catalytic characteristics. Metallic Cu and Ni did not leach from the catalyst, confirming that the benzonitrile reduction reaction catalyzed by this catalyst is a truly heterogeneous catalytic process.

[0059] The above example, using the catalytic reduction of benzonitrile as an example, demonstrates the application of the nanocatalyst Cu1Ni1@rGO ​​in hydrogenation reduction reactions. In fact, as can be seen from substrate expansion, the supported bimetallic Cu1Ni1@rGO ​​catalyst has a wide range of applications in hydrogenation reduction reactions, exhibiting good conversion rates and selectivity, and is not limited to substances with a specific structure. The supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalyst has a stable chemical structure; graphene oxide (GO) can serve as an excellent dispersion support, providing significant support and anchoring for the alloy nanoparticles, helping to control the size and distribution of the metal particles formed during synthesis, thus achieving excellent monodispersion (e.g., Figure 6 As shown, loading metals onto graphene oxide can significantly improve the dispersibility of nanoparticles. When used in the hydrogenation reduction reaction of substances such as nitriles, it exhibits high catalytic activity, stability, and catalytic efficiency, and can also improve the recyclability of the catalyst in the reaction.

[0060] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. The application of a supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalyst in the catalytic hydrogenation reduction of nitrile to amine, characterized in that, The preparation method of the catalyst includes the following steps: 1) Take copper chloride solution and nickel chloride solution, stir to mix them evenly, wherein the molar ratio of copper chloride to nickel chloride is 1:1; 2) Add the graphene oxide (GO) solution dropwise and sonicate to ensure that the graphene oxide solution is uniformly mixed with the above solution; 3) Neutralize and adjust the pH of the mixed solution to 7-9 with alkali solution; 4) Dissolve sodium borohydride (NaBH4) in water to obtain a sodium borohydride solution for later use; 5) Heat and stir the mixed solution, and add the sodium borohydride solution dropwise while continuing to stir; after the reaction is complete, cool to room temperature and let it stand to mature. 6) Remove the upper layer of solution, centrifuge the lower layer of precipitate, and after centrifugation, remove the upper layer of solution from the centrifuge tube, retain the precipitate at the bottom of the centrifuge tube, and wash the precipitate. After multiple centrifugation and washing processes, impurities in the precipitate are removed. 7) The catalyst prepared by vacuum drying is crushed into fine black powder particles to obtain the supported, inexpensive bimetallic Cu1Ni1@rGO ​​catalyst; In step 2), the mass ratio of copper chloride to graphene oxide (GO) is (5-30):(60-400); the concentration of the graphene oxide (GO) solution is 1.0-4.0 mg / mL; in step 5), the mixed solution is heated from room temperature to 70℃-90℃ at a heating rate of 1-3℃ / min.

2. The application as described in claim 1, characterized in that, In step 1), copper chloride and nickel chloride are CuCl2·2H2O and NiCl2·6H2O hydrates, respectively, and the concentrations of the copper chloride solution and nickel chloride solution are 0.005-0.02 mol / L and 0.005-0.02 mol / L, respectively.

3. The application as described in claim 1, characterized in that, In step 3), the alkaline solution is a sodium hydroxide solution with a concentration of 0.2-1.0 mol / L; the pH value is adjusted to 8; in step 4), sodium borohydride is dissolved in deionized water to prepare a molar concentration of 0.5-1.5 mol / L.

4. The application as described in claim 1, characterized in that, In step 5), the amount of sodium borohydride solution used is 1-4 mL; the sodium borohydride solution is added dropwise and magnetically stirred at the heating temperature for 2-4 h, and then allowed to stand for 6-18 h for maturation.

5. The application as described in claim 1, characterized in that, In step 6), remove the supernatant solution, place the lower precipitate in a centrifuge tube and centrifuge for 10-30 minutes at a speed of 10,000-16,000 rpm. After centrifugation, remove the supernatant solution from the centrifuge tube, retain the precipitate at the bottom of the centrifuge tube, wash the precipitate with deionized water at least 3 times, centrifuge for 10-30 minutes to remove the supernatant solution, then wash with anhydrous ethanol at least 3 times, centrifuge for 10-30 minutes to remove the supernatant solution, and completely remove other impurities from the precipitate.

6. The application as described in claim 1, characterized in that, In step 7), the vacuum drying process includes: placing the obtained catalyst in a vacuum drying oven, and when the vacuum degree of the vacuum drying oven is 0, gradually increasing the temperature from room temperature to 50-80℃ and vacuum drying for 18-30 hours; when the vacuum drying oven cools to room temperature, take out the prepared catalyst, grind it thoroughly into a fine black powder with a quartz grinder, weigh it, and set it aside.

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