A method for preparing a catalyst for HMF electrocatalytic reduction reaction

Abstract

The present invention relates to the field of inorganic material preparation and discloses a method for preparing a catalyst for the electrocatalytic reduction reaction of HMF. The method comprises oxidizing copper foam with sodium hydroxide and then reducing the copper foam with anhydrous sodium sulfate to obtain a copper foam precursor. Zinc chloride, potassium chloride, and boric acid are used as electrolyte raw materials and electroplated at a certain temperature to obtain a copper-zinc bimetallic catalyst. The method for preparing the catalyst for the electrocatalytic reduction reaction of HMF differs from the currently used copper-based bimetallic catalyst in that a copper-zinc bimetallic catalyst is used for the electrocatalytic reduction reaction of HMF. At the same time, an electroplating method is used to electroplated metallic zinc on copper, resulting in a simple preparation process and good reproducibility. More importantly, the electroplating method can directly grow metallic zinc in situ on the copper substrate. The prepared catalyst has a large specific surface area and can fully contact the reaction solution, thereby increasing the electrochemically active surface area.

Description

Technical Field

[0001] The present invention relates to the field of inorganic material preparation, and in particular to a method for preparing a catalyst for HMF electrocatalytic reduction reaction. Background Art

[0002] In recent years, with the rapid growth of the world's population, chemical petroleum fuel resources (such as coal, crude oil, and natural gas) have been significantly reduced, while global energy demand continues to grow. Fossil fuels have adverse environmental impacts, necessitating the development of new technologies for clean and renewable energy. However, in this context, biomass, with its readily available and renewable properties, offers a promising alternative to chemicals and fuels.

[0003] The furan-based biochemical 5-hydroxymethylfurfural (HMF) is one of the most promising and widely used biomass-derived platforms. HMF can be obtained by dehydrating hexoses (such as fructose and glucose). Due to its diverse chemical functional groups, HMF can be converted into other high-value-added products and more stable derivatives through oxidation and reduction reactions, hydrolysis, esterification, and oxidative cleavage. HMF can be reduced to produce 2,5-dihydroxymethylfuran (DHMF), an important precursor for the production of polyethylene foam and polyester. Another hydrogenation product of HMF is 2,5-dimethylfuran (DMF), which can be used as a new liquid fuel to replace fossil fuels. Compared with bioethanol, DMF has higher energy density, higher octane number, and lower volatility. Its immiscibility with water makes it easier to mix with gasoline, which facilitates its transportation and storage, making DMF a promising liquid fuel option. On the other hand, DMF has a boiling point between ethanol and butanol, offering excellent gasification properties. This helps suppress engine intake air resistance, meeting low-temperature engine starting requirements, and exhibiting good performance in direct-injection and spark-ignition engines. HMF can also be converted into other valuable products. Another reduction product, 5-MFA, has been identified as the primary intermediate in the synthesis of the biofuel DMF from 5-HMF, though its synthesis has only been performed on a laboratory scale. 5-MFA, a member of the furan family, can be considered a primary precursor for biofuel production due to its significant characteristics, such as low oxygen content, high energy density, chemical stability, low volatility, and good solubility in hydrocarbons. It is also widely used as a flavoring agent and food additive.

[0004] Current research on metal Cu catalysts mainly focuses on: (1) synthesizing copper with different exposed crystal face ratios as a catalyst, and (2) combining Cu with other transition metals to prepare bimetallic catalysts to improve the catalytic activity and stability of the catalyst. For example, patent document No. CN114622237A discloses a nickel-copper bimetallic catalyst NiCu NTs. By electrodeposition, nickel foam is used as a working electrode, platinum sheet is used as a counter electrode, and saturated calomel electrode is used as a reference electrode in deionized water containing nickel sulfate, copper sulfate, and boric acid. Electrodeposition is carried out at a current of 60-120 mA for 5-20 minutes to obtain a NiCu alloy precursor. The NiCu NTs bimetallic catalyst is obtained by reacting at a constant potential of 0.5-1.2 V for 5-10 minutes. This catalyst is used in the electrooxidation of 5-hydroxymethylfurfural to produce 2,5-furandicarboxylic acid and has the advantages of stable catalytic performance and abundant catalytic reaction active sites.

[0005] For example, a research paper (“Non-noble bimetallic alloy in the high selective electrochemical synthesis of biofuel 2,5-dimethyl-furan from 5-hydroxymethylfurfural,” Green Chemistry, Vol. 21, No. 5, 2019) reports that a CuNi bimetallic catalyst was used for the electrocatalytic reduction of HMF, achieving a 91.17% selectivity for 2,5-dimethylfuran (DMF). The catalyst was deposited onto copper foam using nickel electrodeposition.

[0006] From the current research status at home and abroad, the method of preparing catalysts by electrodeposition is not only simple in process and low in cost, but also has high stability of catalytic materials and a large specific surface area, thereby improving catalytic activity. In the process of preparing Cu-based bimetallic catalysts, bimetallic catalysts with excellent catalytic performance and conversion can be prepared by selecting suitable metals. For example, the patent document with publication number CN106881143A discloses a CuAu bimetallic catalyst, in which a copper source and a gold source are simultaneously dissolved in water, ammonia is added to obtain a metal complex and other raw materials, and then a carrier is added to adjust the pH value and calcined to obtain a highly dispersed, highly active CuAg bimetallic catalyst. This material utilizes the synergistic effect of the copper and gold bimetallics to further enhance the activity of the catalyst.

[0007] Copper-based bimetallic catalysts can enhance catalytic performance by leveraging the synergistic effects between the two metals. When preparing copper-based bimetallic catalysts, the addition of zinc is beneficial. Both zinc and copper are non-precious metals with abundant reserves, low prices, and high conductivity. Highly conductive catalysts are beneficial for enhancing catalytic activity. Currently, there are few methods for preparing copper-zinc bimetallic catalysts using electrodeposition for the electrocatalytic reduction of HMF. The effect of zinc content in copper-based bimetallic catalysts on the electrocatalytic reduction of HMF has not yet been fully characterized. Therefore, we propose a method for preparing a catalyst for the electrocatalytic reduction of HMF. Summary of the Invention

[0008] (1) Technical problems solved

[0009] In view of the deficiencies of the prior art, the present invention provides a method for preparing a catalyst for HMF electrocatalytic reduction reaction to solve the above problems.

[0010] (2) Technical solution

[0011] To achieve the above-mentioned purpose, the present invention provides the following technical solutions:

[0012] A method for preparing a catalyst for HMF electrocatalytic reduction reaction comprises the following steps:

[0013] Step 1: Dissolve sodium hydroxide in deionized water and stir until completely dissolved to obtain a uniform sodium hydroxide solution. Use copper foam as the working electrode, platinum sheet as the counter electrode, and silver chloride as the reference electrode. Apply 40-60 mA current in the sodium hydroxide solution for oxidation for 25-30 minutes at a reaction condition of 60-80°C to obtain a copper oxide material.

[0014] Step 2: dissolve anhydrous sodium sulfate in deionized water and stir until completely dissolved to obtain a uniform anhydrous sodium sulfate solution. Use copper oxide as the working electrode, platinum sheet as the counter electrode, and silver chloride as the reference electrode. Apply current reduction in the anhydrous sodium sulfate solution to obtain a foam copper precursor.

[0015] Step 3: Dissolve zinc chloride, potassium chloride and boric acid in deionized water to form a reaction solution, and stir until they are completely dissolved to obtain a uniform solution to obtain a reaction solution;

[0016] Step 4: Using the copper foam precursor as the working electrode, the platinum sheet as the counter electrode, and the silver-silver chloride as the reference electrode, apply a current of -10 to -30 mA in the reaction solution for electrodeposition for 5 to 20 minutes. After the reaction, the copper foam is taken out and washed and dried to obtain a copper-zinc bimetallic catalyst material.

[0017] Preferably, the amount of sodium hydroxide added in the first step is 2 to 4 mol / L.

[0018] Preferably, the reaction conditions in the first step are 70° C., 50 mA current, and 20 min oxidation time.

[0019] Preferably, the amount of anhydrous sodium sulfate added in the second step is 0.5 to 2 mol / L.

[0020] Preferably, the applied current in the second step is -40 to -60 mA for 25 to 30 minutes.

[0021] Preferably, in the third step, the concentration of zinc chloride is 40-60 g / L, the concentration of potassium chloride is 180-200 g / L, and the concentration of boric acid is 20-30 g / L.

[0022] Preferably, the stirring time in the third step is 5 minutes and the rotation speed is 500 rpm.

[0023] Preferably, the applied current in the fourth step is -20 mA and the reaction temperature is 25°C.

[0024] Preferably, the foam copper in the first step needs to be cut to an area of 1×1 cm 2 .

[0025] (3) Beneficial effects

[0026] Compared with the prior art, the preparation method of the catalyst for HMF electrocatalytic reduction reaction provided by the present invention has the following beneficial effects:

[0027] 1. A method for preparing a catalyst for the electrocatalytic reduction reaction of HMF, wherein the catalyst is obtained by an electrodeposition method. The preparation process has mild reaction conditions, a simple process, a short production time, and uses inexpensive and readily available raw materials.

[0028] 2. This method for preparing a catalyst for the electrocatalytic reduction of HMF differs from currently used copper-based bimetallic catalysts in that it utilizes a copper-zinc bimetallic catalyst for the HMF electrocatalytic reduction reaction. Furthermore, the method employs an electrodeposition method to deposit metallic zinc onto copper, resulting in a simple preparation process and highly reproducible results. More importantly, the electrodeposition method enables the in-situ growth of metallic zinc directly on the copper substrate, resulting in a catalyst with a large specific surface area, sufficient contact with the reaction solution, and a larger electrochemically active surface area. The introduction of metallic zinc reduces the electrical resistance of the catalyst material and promotes the catalytic reaction. The corresponding HMF reduction product exhibits good conversion and Faradaic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 X-ray diffraction patterns of catalysts obtained at different electrodeposition times according to the present invention;

[0030] Figure 2 This is a scanning electron microscope image of the CuZn electrode material according to an embodiment of the present invention;

[0031] Figure 3 Electrocatalytic reduction performance of CuZn electrode materials with different deposition times under HMF according to the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] See also Figure 1-3 The present invention provides a method for preparing a catalyst for the electrocatalytic reduction reaction of HMF. For details of the technical solution, please refer to the following Examples 1-4.

[0034] Example 1

[0035] The preparation method of the catalyst for the HMF electrocatalytic reduction reaction provided in this embodiment comprises the following steps:

[0036] Dissolve 7.2g of sodium hydroxide in 60mL of deionized water to obtain a uniform reaction solution. Cut the dried copper foam into 1×1cm2 areas to fix the electrodeposition reaction area at 1×1cm2. Use the copper foam as the working electrode, the platinum electrode as the counter electrode, and the silver-silver chloride electrode as the reference electrode in an electrochemical workstation to treat the copper foam. Using the chronopotentiometry, oxidize the copper foam at 70°C and 50mA for 20min to obtain copper oxide.

[0037] The oxidized copper foam was washed with deionized water and dried for later use. 8.52 g of anhydrous sodium sulfate was dissolved in 60 mL of deionized water to obtain a uniform reaction solution. The oxidized copper foam was used as the working electrode, the platinum electrode as the counter electrode, and the silver-silver chloride electrode as the reference electrode. The Cu precursor was obtained by reduction at -50 mA for 30 min at 70°C.

[0038] The reduced copper precursor was washed with deionized water and placed in a vacuum drying oven at 60°C for later use. The prepared catalyst was rinsed with deionized water to remove any residual reaction solution, and then dried in a vacuum drying oven for later use. 2.7g zinc chloride, 9g potassium chloride, and 1.25g boric acid were dissolved in deionized water and magnetically stirred at 500 rpm for 5 minutes to obtain a uniform reaction solution.

[0039] Electrochemical deposition was performed in an electrochemical workstation using a Cu precursor as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride electrode as the reference electrode. The CuZn catalyst was first deposited using chronopotentiometry at -20 mA for 5 minutes at room temperature (25°C). The catalyst was then rinsed with deionized water, clearing any remaining reaction solution, and dried in a 60°C vacuum oven until ready for use. This was labeled CuZn-5.

[0040] Example 2

[0041] The preparation method of the catalyst for the HMF electrocatalytic reduction reaction provided in this embodiment comprises the following steps:

[0042] Dissolve 7.2g of sodium hydroxide in 60mL of deionized water to obtain a uniform reaction solution. Cut the dried copper foam into 1×1cm² sections to maintain a fixed electrodeposition reaction area of 1×1cm². The copper foam was treated in an electrochemical workstation using the copper foam as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride electrode as the reference electrode. Using chronopotentiometry, the copper foam was oxidized at 70°C and 50mA for 20min to produce copper oxide. The oxidized copper foam was rinsed with deionized water and dried for later use. Dissolve 8.52g of anhydrous sodium sulfate in 60mL of deionized water to obtain a uniform reaction solution. Using the oxidized copper foam as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride electrode as the reference electrode, the copper precursor was reduced at 70°C and -50mA for 30min to obtain the copper precursor. The reduced copper precursor was rinsed with deionized water and placed in a vacuum drying oven at 60°C for later use. The prepared catalyst was rinsed with deionized water, the remaining reaction liquid was removed, and the catalyst was dried in a vacuum oven for later use. 2.7g of zinc chloride, 9g of potassium chloride, and 1.25g of boric acid were dissolved in deionized water and magnetically stirred at 500 rpm for 5 minutes to obtain a homogeneous reaction solution. Electrochemical deposition was performed in an electrochemical workstation using the Cu precursor as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride electrode as the reference electrode. Chronopotentiometry was used for electrodeposition at -20mA for 10 minutes at room temperature (25°C) to obtain the CuZn catalyst. The prepared catalyst was rinsed with deionized water, the remaining reaction liquid was removed, and the catalyst was dried in a vacuum oven at 60°C for later use. This was labeled CuZn-10.

[0043] Example 3

[0044] The preparation method of the catalyst for the HMF electrocatalytic reduction reaction provided in this embodiment comprises the following steps:

[0045] Dissolve 7.2g of sodium hydroxide in 60mL of deionized water to obtain a uniform reaction solution. Cut the dried copper foam into 1×1cm² sections to maintain a fixed electrodeposition reaction area of 1×1cm². The copper foam was treated in an electrochemical workstation using the copper foam as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride electrode as the reference electrode. Using chronopotentiometry, the copper foam was oxidized at 70°C and 50mA for 20min to produce copper oxide. The oxidized copper foam was rinsed with deionized water and dried for later use. Dissolve 8.52g of anhydrous sodium sulfate in 60mL of deionized water to obtain a uniform reaction solution. Using the oxidized copper foam as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride electrode as the reference electrode, the copper precursor was reduced at 70°C and -50mA for 30min to obtain the copper precursor. The reduced copper precursor was rinsed with deionized water and placed in a vacuum drying oven at 60°C for later use. The prepared catalyst was rinsed with deionized water, the remaining reaction solution was removed, and the catalyst was dried in a vacuum oven for later use. 2.7g of zinc chloride, 9g of potassium chloride, and 1.25g of boric acid were dissolved in deionized water and magnetically stirred at 500 rpm for 5 minutes to obtain a homogeneous reaction solution. Electrochemical deposition was performed in an electrochemical workstation using the Cu precursor as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride electrode as the reference electrode. Chronopotentiometry was used for electrodeposition at -20mA for 15 minutes at room temperature (25°C) to obtain the CuZn catalyst. The prepared catalyst was rinsed with deionized water, the remaining reaction solution was removed, and the catalyst was dried in a vacuum oven at 60°C for later use. This was labeled CuZn-15.

[0046] Example 4

[0047] The preparation method of the catalyst for the HMF electrocatalytic reduction reaction provided in this embodiment comprises the following steps:

[0048] Dissolve 7.2g of sodium hydroxide in 60mL of deionized water to obtain a uniform reaction solution. Cut the dried copper foam into 1×1cm² sections to maintain a fixed electrodeposition reaction area of 1×1cm². The copper foam was treated in an electrochemical workstation using the copper foam as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride electrode as the reference electrode. Using chronopotentiometry, the copper foam was oxidized at 70°C and 50mA for 20min to produce copper oxide. The oxidized copper foam was rinsed with deionized water and dried for later use. Dissolve 8.52g of anhydrous sodium sulfate in 60mL of deionized water to obtain a uniform reaction solution. Using the oxidized copper foam as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride electrode as the reference electrode, the copper precursor was reduced at 70°C and -50mA for 30min to obtain the copper precursor. The reduced copper precursor was rinsed with deionized water and placed in a vacuum drying oven at 60°C for later use. The prepared catalyst was rinsed with deionized water, the remaining reaction solution was removed, and the catalyst was dried in a vacuum oven until ready for use. 2.7g of zinc chloride, 9g of potassium chloride, and 1.25g of boric acid were dissolved in deionized water and magnetically stirred at 500 rpm for 5 minutes to obtain a homogeneous reaction solution. Electrochemical deposition was performed in an electrochemical workstation using the Cu precursor as the working electrode, a platinum electrode as the counter electrode, and a silver-silver chloride electrode as the reference electrode. The CuZn catalyst was first deposited using chronopotentiometry at -20mA for 20 minutes at room temperature (25°C). The prepared catalyst was rinsed with deionized water, the remaining reaction solution was removed, and the catalyst was dried in a vacuum oven at 60°C until ready for use. This was labeled CuZn-20.

[0049] Figure 1 : XRD patterns of CuZn catalysts at different deposition times, in the figure: CuZn-5 is the sample of Example 1, CuZn-10 is the sample of Example 2, CuZn-15 is the sample of Example 3, and CuZn-20 is the sample of Example 4. It can be found from the XRD patterns of samples with a deposition time of 10 min and above that the diffraction peak intensity of ZnO gradually increases, and has good crystallinity.

[0050] Figure 2 In the figure: a is the sample of Example 1, b is the sample of Example 2, c is the sample of Example 3, and d is the sample of Example 4.

[0051] Figure 3 In the figure: CuZn-5 is the sample of Example 1, CuZn-10 is the sample of Example 2, CuZn-15 is the sample of Example 3, and CuZn-20 is the sample of Example 4.

[0052] The method for preparing a catalyst for the electrocatalytic reduction of HMF provided in the above-mentioned embodiment of the present invention differs from the currently used copper-based bimetallic catalyst in that a copper-zinc bimetallic catalyst is used for the electrocatalytic reduction of HMF. Furthermore, an electrodeposition method is employed to deposit metallic zinc on copper, resulting in a simple preparation process and highly reproducible results. More importantly, the electrodeposition method enables the in-situ growth of metallic zinc directly on the copper substrate. The prepared catalyst has a large specific surface area, allowing for sufficient contact with the reaction solution, thereby increasing the electrochemically active surface area.

[0053] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a catalyst for HMF electrocatalytic reduction reaction, characterized in that: The following steps are involved: Step 1: Dissolve sodium hydroxide in deionized water and stir until completely dissolved to obtain a uniform sodium hydroxide solution. Use copper foam as the working electrode, platinum sheet as the counter electrode, and silver chloride as the reference electrode. Apply 40-60 mA current in the sodium hydroxide solution for oxidation for 25-30 minutes at a reaction condition of 60-80°C to obtain a copper oxide material. Step 2: dissolve anhydrous sodium sulfate in deionized water and stir until completely dissolved to obtain a uniform anhydrous sodium sulfate solution. Use copper oxide as the working electrode, platinum sheet as the counter electrode, and silver chloride as the reference electrode. Apply current reduction in the anhydrous sodium sulfate solution to obtain a foam copper precursor. Step 3: Dissolve zinc chloride, potassium chloride and boric acid in deionized water to form a reaction solution, and stir until they are completely dissolved to obtain a uniform solution to obtain a reaction solution; Step 4: Using the copper foam precursor as the working electrode, the platinum sheet as the counter electrode, and the silver-silver chloride as the reference electrode, apply a current of -10 to -30 mA in the reaction solution for electrodeposition for 5 to 20 minutes. After the reaction, the copper foam is taken out and washed and dried to obtain a copper-zinc bimetallic catalyst material.

2. The method for preparing a catalyst for HMF electrocatalytic reduction reaction according to claim 1, wherein: The amount of sodium hydroxide added in the first step is 2-4 mol / L.

3. The method for preparing a catalyst for HMF electrocatalytic reduction reaction according to claim 1, wherein: The reaction conditions in the first step are 70° C., 50 mA current, and 20 min oxidation time.

4. The method for preparing a catalyst for HMF electrocatalytic reduction reaction according to claim 1, wherein: The amount of anhydrous sodium sulfate added in the second step is 0.5-2 mol / L.

5. The method for preparing a catalyst for HMF electrocatalytic reduction reaction according to claim 1, wherein: In the second step, the applied current is -40 to -60 mA for 25 to 30 minutes.

6. The method for preparing a catalyst for HMF electrocatalytic reduction reaction according to claim 1, wherein: In the third step, the concentration of zinc chloride is 40-60 g / L, the concentration of potassium chloride is 180-200 g / L, and the concentration of boric acid is 20-30 g / L.

7. The method for preparing a catalyst for HMF electrocatalytic reduction reaction according to claim 1, characterized in that: The stirring time in the third step is 5 min and the rotation speed is 500 rpm.

8. The method for preparing a catalyst for HMF electrocatalytic reduction reaction according to claim 1, wherein: The applied current in the fourth step was -20 mA, and the reaction temperature was 25°C.

9. The method for preparing a catalyst for HMF electrocatalytic reduction reaction according to claim 1, wherein: The copper foam in the first step needs to be cut into 1×1cm 2 .

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