Method for modifying a foamed metal and method for producing 2,5-furandicarboxylic acid

Abstract

The application provides a modified method of foamed metal, comprising the following steps: A) immersing the foamed metal in an acid solution; B) cleaning and drying the foamed metal obtained in step A) to obtain modified foamed metal; the drying temperature is 10-200 DEG C. The application also provides a method for preparing 2,5-furan dicarboxylic acid. In the process of modifying the foamed metal, acid treatment causes the surface of the foamed metal to be etched and chemically oxidized, and the drying process in situ grows corresponding active substances such as metal oxides / hydroxides / hydroxyl oxides; the foamed metal after acid treatment has a larger specific surface area and more exposed active sites, and exhibits high activity and high selectivity in electrocatalytic oxidation. The foamed metal electrode surface reconstruction and modification method provided by the application is simple to operate, mild in conditions, low in cost, low in requirement for equipment, and suitable for large-scale production and industrial application.

Description

Technical Field

[0001] This invention relates to a method for preparing 2,5-furandicarboxylic acid by electrocatalytic oxidation, and more particularly to a method for modifying foam metal and a method for preparing 2,5-furandicarboxylic acid. Background Technology

[0002] The continued use of fossil fuels has exacerbated the energy and environmental crisis, necessitating the development of sustainable clean energy storage and conversion technologies. Among various clean and renewable energy sources, biomass energy has garnered widespread attention in recent years due to its abundant reserves, large-scale application, and sustainability. 5-Hydroxymethylfurfural, as an important biomass platform compound, can be catalytically converted into a series of high-value-added chemicals, serving as important chemical raw materials, pharmaceutical intermediates, and pesticides. Among its oxidation products, 2,5-furandicarboxylic acid, one of the 12 representative bio-based platform molecules released by the U.S. Department of Energy in 2004, is considered an important monomer substitute for the petroleum-derived terephthalic acid and has broad application prospects in polymer industrial production.

[0003] Traditional thermocatalytic methods for preparing 2,5-furandicarboxylic acid require high temperature and high oxygen pressure environments, necessitate noble metal-based catalysts, and are energy-intensive and subject to numerous limitations. In contrast, the electrocatalytic oxidation method, which has attracted considerable attention in recent years, can produce 2,5-furandicarboxylic acid with high selectivity and high yield at ambient temperature and pressure using non-noble metal-based catalysts, representing a green and efficient approach. Studies have reported that transition metal-based catalysts (N-NiMoO4, CuCo2O4, Fe3O4 / Pt / rGO, MoO2-FeP, NiFe-LDH, etc.) exhibit high activity in alkaline solutions for the electrocatalytic oxidation of 5-hydroxymethylfurfural, achieving near-theoretical efficiencies to 2,5-furandicarboxylic acid. However, these catalysts generally suffer from challenging preparation processes and complex procedures.

[0004] Due to their three-dimensional structure and low cost, metal foam is often used as a support for catalysts in the electrocatalytic oxidation of 5-hydroxymethylfurfural (5-HMF) to obtain a high electrochemically active surface area. However, metal foam itself exhibits poor catalytic activity for 5-HMF. A few studies have also attempted to directly modify metal foam through hydrothermal processes, calcination, sulfidation, and phosphating. However, these methods involve complex preparation processes, require the addition of expensive reagents, necessitate high-end equipment, are time-consuming, and do not significantly improve catalytic performance, hindering large-scale practical applications.

[0005] Therefore, how to establish a simple, efficient and economical method to prepare a foam metal electrode with high electrocatalytic oxidation activity for the high-value conversion of 5-hydroxymethylfurfural, and further reduce costs, has become an urgent problem to be solved in this field. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a method for modifying foam metal. The modified foam metal of this application has high catalytic activity and good stability.

[0007] In view of this, this application provides a method for modifying foamed metal, comprising the following steps:

[0008] A) Immerse the foamed metal in an acid solution;

[0009] B) The foam metal obtained in step A) is cleaned and dried to obtain modified foam metal; the drying temperature is 10℃~200℃.

[0010] Preferably, the acid solution is selected from sulfuric acid aqueous solution, hydrochloric acid aqueous solution, nitric acid aqueous solution or phosphoric acid aqueous solution, and the concentration of the acid solution is 0.1 to 6 mol / L.

[0011] Preferably, the foam metal is selected from one or more of foamed nickel, foamed copper, foamed cobalt, foamed iron, foamed iron-nickel, foamed molybdenum-nickel, and foamed copper-nickel.

[0012] Preferably, the immersion time in the acid solution is 10 min to 24 h.

[0013] Preferably, the drying method is air drying, oven drying, or vacuum drying.

[0014] Preferably, the drying temperature is 50–100°C.

[0015] Preferably, the drying time is 3 to 100 hours.

[0016] This application also provides a method for preparing 2,5-furandicarboxylic acid, comprising the following steps:

[0017] Using modified foam metal as the working electrode, 5-hydroxymethylfurfural is added to the electrolyte solution, and electrolysis is carried out by constant potential electrolysis to obtain 2,5-furandicarboxylic acid; the modified foam metal is the modified foam metal prepared by the modification method described in the above scheme.

[0018] Preferably, the electrolyte solution is an alkaline solution with a concentration of 0.1 to 1 mol / L.

[0019] Preferably, the voltage of the electrolysis is 0.45 to 0.75 V.

[0020] This application provides a method for modifying foamed metal. First, the foamed metal is immersed in an acid solution, then cleaned and dried to obtain modified foamed metal. In this process, the foamed metal is first etched in the acid solution to increase its surface roughness and form more catalytically active sites on its surface. The subsequent drying causes oxidation of the foamed metal surface, resulting in the in-situ growth of corresponding active species such as metal oxides, metal hydroxides, or metal hydroxyl oxides. This increases the specific surface area and electrochemically active area of ​​the foamed metal. Furthermore, the surface-active substances grown in situ on the foamed metal are tightly bonded to the substrate, exhibiting good conductivity and stability, and maintaining excellent stability even during long-term operation.

[0021] Furthermore, the preparation method provided in this application is simple, the preparation conditions are mild, the equipment requirements are low, and the raw materials are widely available and inexpensive, making it suitable for large-scale production and commercial application. Attached Figure Description

[0022] Figure 1 These are scanning electron microscope images of the modified nickel foam electrode and the blank nickel foam electrode prepared in Example 1 and Comparative Example 1 of the present invention;

[0023] Figure 2 A high-resolution transmission electron microscope image of the modified nickel foam electrode prepared in Example 1 of this invention;

[0024] Figure 3 The current density difference at 0.02V varies with scan rate between the modified nickel foam electrode prepared in Example 1 and Comparative Example 1 of this invention and the blank nickel foam electrode.

[0025] Figure 4 Linear scanning voltammetric curves of the modified nickel foam electrode and the blank nickel foam electrode prepared in Example 1 and Comparative Example 1 of this invention in a 1 mol / L potassium hydroxide solution containing 10 mmol / L 5-hydroxymethylfurfural;

[0026] Figure 5 This is a comparison of the 5-hydroxymethylfurfural conversion rate, 2,5-furandicarboxylic acid yield, and Faraday efficiency of the modified nickel foam electrode prepared in Example 1 and Comparative Example 1 of this invention and the blank nickel foam electrode.

[0027] Figure 6 The relationship between the conversion rate of 5-hydroxymethylfurfural, the yield of 2,5-furandicarboxylic acid, and the Faraday efficiency of the modified nickel foam electrode prepared in Example 1 of the present invention and the number of cycles after 25 cycles is shown.

[0028] Figure 7 These are scanning electron microscope images of the modified copper foam electrode and the blank copper foam electrode prepared in Example 2 and Comparative Example 2 of the present invention.

[0029] Figure 8 This is a comparison of the 5-hydroxymethylfurfural conversion rate, 2,5-furandicarboxylic acid yield, and Faraday efficiency of the modified foamed copper electrode prepared in Example 2 and Comparative Example 2 of this invention and the blank foamed copper electrode.

[0030] Figure 9 These are scanning electron microscope images of the modified nickel-molybdenum foam electrode and the blank nickel-molybdenum foam electrode prepared in Example 3 and Comparative Example 3 of the present invention.

[0031] Figure 10 This is a comparison of the 5-hydroxymethylfurfural conversion rate, 2,5-furandicarboxylic acid yield, and Faraday efficiency of the modified foamed nickel-molybdenum electrode prepared in Example 3 and Comparative Example 3 of the present invention and the blank foamed nickel-molybdenum electrode.

[0032] Figure 11 The X-ray diffraction pattern of the modified copper foam prepared in Example 4 of this invention. Detailed Implementation

[0033] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0034] In view of the need for electrocatalytic activity of foamed metals in the prior art, this application provides a method for modifying foamed metals. This method involves acid treatment and drying of the foamed metal to induce in-situ chemical oxidation growth of corresponding metal oxides / hydroxides / hydroxy oxides on its surface, resulting in a material with high catalytic oxidation activity for 5-hydroxymethylfurfural. Specifically, this invention discloses a method for modifying foamed metals, including the following steps:

[0035] A) Immerse the foamed metal in an acid solution;

[0036] B) The foam metal obtained in step A) is cleaned and dried to obtain modified foam metal; the drying temperature is 10-200℃.

[0037] In the process of modifying foamed metal, this application first immerses the foamed metal in an acid solution. The foamed metal is a type of foamed metal well-known to those skilled in the art; for example, the foamed metal is selected from one or more of foamed nickel, foamed copper, foamed cobalt, foamed iron, foamed iron-nickel, foamed molybdenum-nickel, and foamed copper-nickel. The acid solution can specifically be an aqueous solution of sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid, with a concentration of 0.1–6 mol / L; specifically, the concentration of the acid solution is 1–4 mol / L, and more specifically, the concentration of the acid solution is 1–2 mol / L. The immersion time in the acid solution is 10 min–24 h; specifically, the immersion time is 1–6 h, and more specifically, the immersion time is 1–3 h.

[0038] This application then cleans and dries the obtained foamed metal to obtain modified foamed metal. The drying temperature is 10–200°C. In the above process, the cleaning is well known to those skilled in the art, and the drying time is 3–100 hours, specifically 6–12 hours, and the drying temperature is 50–100°C.

[0039] In this application, immersion in acid solution not only etches the foam metal surface, increases the specific surface area, and increases the number of active sites in the electrochemical reaction process, but also causes chemical oxidation of the foam metal surface during the subsequent drying process, generating one or more of the corresponding catalytically active species, such as metal oxides, hydroxides, or hydroxy oxides. These active species are key active species in the electrocatalytic oxidation of 5-hydroxymethylfurfural. Furthermore, the acid immersion allows the subsequent drying process to proceed at a relatively low drying temperature (10–200°C, preferably 60°C), generating the corresponding active substances and significantly reducing energy consumption.

[0040] This application also provides a method for preparing 2,5-furandicarboxylic acid, comprising the following steps:

[0041] Using modified foam metal as the working electrode, 5-hydroxymethylfurfural is added to the electrolyte solution, and electrolysis is carried out by constant potential electrolysis to obtain 2,5-furandicarboxylic acid; the modified foam metal is the modified foam metal prepared by the modification method described in the above scheme.

[0042] In the above-mentioned preparation of 2,5-furandicarboxylic acid, 5-hydroxymethylfurfural is electrocatalytically oxidized to 2,5-furandicarboxylic acid. An electrocatalyst with good catalytic oxidation performance of 5-hydroxymethylfurfural needs to maintain high electrocatalytic oxidation activity of 5-hydroxymethylfurfural while having poor oxygen evolution reaction activity in order to ensure that it can obtain a high Faradaic efficiency. The modified foam metal prepared in this application can achieve the above-mentioned effect.

[0043] In the preparation of 2,5-furandicarboxylic acid, the electrolyte solution is a 0.1–1 mol / L alkaline solution, more specifically a 0.3–1 mol / L potassium hydroxide solution. The electrolysis voltage is 0.45–0.75 V. In the electrocatalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid, a mercury / mercuric oxide electrode is used as the reference electrode, and a platinum sheet electrode is used as the counter electrode.

[0044] This invention provides a method for preparing surface-modified foamed metal, which involves a one-step acid treatment to induce in-situ chemical oxidation growth of corresponding metal oxides / hydroxides / hydroxyoxides on the foamed metal surface, resulting in an electrode material with high catalytic activity for the oxidation of 5-hydroxymethylfurfural. The method for preparing the modified foamed metal electrode provided by this invention is simple to operate, highly controllable, green, efficient, low-cost, and suitable for large-scale production, making it suitable for commercial promotion and application. It offers a promising solution for preparing foamed metal electrodes with high electrocatalytic activity.

[0045] Experimental results show that the modified nickel foam electrode prepared by the method provided in this invention has a large specific surface area and electrochemically active area, and the nickel hydroxyl oxide grown in situ on the nickel foam electrode exhibits high electrocatalytic activity. Using the modified nickel foam electrode prepared by the method provided in this invention as the working electrode, it was applied to the electrocatalytic oxidation of 5-hydroxymethylfurfural to selectively convert it to 2,5-furandicarboxylic acid. A mercury / mercuric oxide electrode was used as the reference electrode, a platinum sheet electrode as the counter electrode, and a 1 mol / L potassium hydroxide solution containing 10 mmol / L 5-hydroxymethylfurfural was used as the electrolyte. Constant potential electrolysis was performed at 0.45 V, which efficiently oxidized 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid, with a 5-hydroxymethylfurfural conversion rate close to 100%, and a 2,5-furandicarboxylic acid yield and Faraday efficiency of approximately 95%.

[0046] To further understand the present invention, the following detailed description of the modification method of foam metal and the preparation method of 2,5-furandicarboxylic acid provided by the present invention is provided in conjunction with the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0047] All raw materials used in this invention are not particularly restricted in terms of their source or purity, and are all commercially available. This invention preferably uses analytical grade or conventional purity used in the field of electrocatalytic preparation.

[0048] To facilitate differentiation of different modified foam metal electrodes and simplify description, modified foam metal electrodes are represented by M-XY; where M = Ni, Cu, NiMo, etc., representing different foam metal electrodes; X = 1, 3, etc., representing the immersion time in acid solution in hours; Y = Cl, S, etc., representing the acid solution used, such as hydrochloric acid or sulfuric acid.

[0049] Example 1

[0050] A) Preparation method of surface-reconstructed modified nickel foam electrode

[0051] (1) Cut the nickel foam into 1*3cm pieces. 2 Immerse it in a 1 mol / L sulfuric acid or 2 mol / L hydrochloric acid solution and let it stand for 3 hours;

[0052] (2) Take out the nickel foam, wash it with deionized water, and dry it in a 60°C oven for 10 hours to obtain surface-modified nickel foam electrodes (Ni-3Cl and Ni-3S).

[0053] B) Method for preparing 2,5-furandicarboxylic acid by electrocatalytic oxidation of 5-hydroxymethylfurfural.

[0054] (1) Use Ni-3Cl or Ni-3S as the working electrode, mercury / mercury oxide electrode as the reference electrode, platinum sheet electrode as the counter electrode, and 1 mol / L potassium hydroxide solution containing 10 mmol / L 5-hydroxymethylfurfural as the electrolyte.

[0055] (2) Electrolyze at a constant potential of 0.45V for 1 hour.

[0056] Comparative Example 1

[0057] The method for preparing blank foamed nickel (Ni) electrodes involves immersing them in an ethanol solution to clean surface deposits such as dust; the remaining operations are consistent with those in Example 1.

[0058] The modified nickel foam electrodes (Ni-3Cl and Ni-3S) prepared in Example 1 exhibit significantly enhanced electrocatalytic activity after one-step acid treatment, enabling them to efficiently electrocatalyze the oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid.

[0059] The surface morphology of the Ni-3Cl, Ni-3S and Ni electrodes prepared in Example 1 and Comparative Example 1 of this invention was examined.

[0060] like Figure 1 As shown, Figure 1 These are scanning electron microscope images of the Ni-3Cl, Ni-3S, and Ni electrodes prepared in Example 1 and Comparative Example 1 of this invention; Figure 1 It can be seen that, compared with the smooth surface of the Ni electrode, the surfaces of the Ni-3Cl and Ni-3S electrodes are etched to form a structure of stacked nanosheets, resulting in increased surface roughness. Figure 2 This is a high-resolution transmission electron microscope image of Ni-3S prepared in Example 1 of the present invention; from Figure 2 It can be seen that the active species of nickel hydroxyl oxide were grown in situ on the Ni-3S electrode modified by sulfuric acid treatment.

[0061] The electrocatalytic oxidation activity of 5-hydroxymethylfurfural by Ni-3Cl, Ni-3S and Ni electrodes prepared in Example 1 and Comparative Example 1 of this invention was detected.

[0062] like Figure 3 As shown, Figure 3 This is a graph showing the change in current density difference at 0.02V with scan rate for the Ni-3Cl, Ni-3S, and Ni electrodes prepared in Example 1 and Comparative Example 1 of this invention; Figure 3 It can be seen that, compared with the Ni electrode, the electrochemical active area of ​​Ni-3Cl and Ni-3S electrodes is significantly increased, indicating that they have more exposed catalytic active sites during the reaction process.

[0063] like Figure 4 As shown, Figure 4 The above are linear sweep voltammetry curves of the Ni-3Cl, Ni-3S, and Ni electrodes prepared in Example 1 and Comparative Example 1 of this invention in a 1 mol / L potassium hydroxide solution containing 10 mmol / L 5-hydroxymethylfurfural; Figure 4 It can be seen that, compared with the Ni electrode, the Ni-3Cl and Ni-3S electrodes have lower onset potentials and higher current densities, indicating that they have higher catalytic activity in the oxidation of 5-hydroxymethylfurfural.

[0064] like Figure 5 As shown, Figure 5 This is a comparative bar chart showing the 5-hydroxymethylfurfural conversion, 2,5-furandicarboxylic acid yield, and Faraday efficiency of Ni-3Cl, Ni-3S, and Ni electrodes prepared in Example 1 and Comparative Example 1 of this invention; Figure 5 It can be seen that, compared with the Ni electrode, the performance of Ni-3Cl and Ni-3S electrodes for the electrocatalytic oxidation of 5-hydroxymethylfurfural is significantly improved, and almost complete conversion of 5-hydroxymethylfurfural can be achieved. Moreover, the yield and Faraday efficiency of 2,5-furandicarboxylic acid can also reach about 95%.

[0065] The cyclic stability of the Ni-3S electrode prepared in Example 1 of this invention for the electrocatalytic oxidation of 5-hydroxymethylfurfural was tested.

[0066] like Figure 6 As shown, Figure 6 This is a graph showing the relationship between the conversion rate of 5-hydroxymethylfurfural, the yield of 2,5-furandicarboxylic acid, and the Faraday efficiency of the Ni-3S electrode prepared in Example 1 of this invention and the number of cycles after 25 cycles. Figure 6 It can be seen that after modification with sulfuric acid, Ni-3S exhibits excellent durability. During 25 cycles, the conversion rate of 5-hydroxymethylfurfural, the yield of 2,5-furandicarboxylic acid, and the Faraday efficiency did not decrease significantly. It can still efficiently oxidize 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid, which demonstrates the excellent stability of the Ni-3S electrode.

[0067] Example 2

[0068] A) Preparation method of surface-reconstructed modified copper foam electrodes (Cu-1Cl and Cu-1S)

[0069] Immerse the copper foam in a 1 mol / L sulfuric acid or 2 mol / L hydrochloric acid solution and let it stand for 1 hour; the rest of the operation is the same as in Example 1.

[0070] B) Method for preparing 2,5-furandicarboxylic acid by electrocatalytic oxidation of 5-hydroxymethylfurfural:

[0071] Electrolysis was performed at a constant potential of 0.55V for 1.5 hours; the remaining operations were consistent with those in Example 1.

[0072] Comparative Example 2

[0073] The method for preparing blank foamed copper electrode (Cu) involves immersing it in an ethanol solution to clean surface deposits such as dust; the remaining operations are consistent with those in Example 2.

[0074] The Cu-1Cl and Cu-1S electrodes prepared in Example 2 showed significantly enhanced electrocatalytic oxidation activity of 5-hydroxymethylfurfural after acid immersion treatment, and were able to efficiently convert 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid.

[0075] The surface morphology of Cu-1Cl, Cu-1S and Cu electrodes prepared in Example 2 and Comparative Example 2 of this invention was detected.

[0076] like Figure 7 As shown, Figure 7 These are scanning electron microscope images of the Cu-1Cl, Cu-1S, and Cu electrodes prepared in Example 2 and Comparative Example 2 of this invention; Figure 7 It can be seen that the Cu electrode has a smooth surface, but after treatment with hydrochloric acid and sulfuric acid, the surfaces of Cu-1Cl and Cu-1S electrodes are etched into mountain-like shapes, and the surface roughness increases.

[0077] The electrocatalytic oxidation performance of 5-hydroxymethylfurfural by Cu-1Cl, Cu-1S and Cu electrodes prepared in Example 2 and Comparative Example 2 of this invention was tested.

[0078] like Figure 8 As shown, Figure 8 The bar chart shows the comparison of 5-hydroxymethylfurfural conversion, 2,5-furandicarboxylic acid yield, and Faraday efficiency of Cu-1Cl, Cu-1S, and Cu electrodes prepared in Example 2 and Comparative Example 2 of this invention. Figure 8It can be seen that, compared with Cu electrode, Cu-1Cl and Cu-1S electrodes significantly improve the performance of electrocatalytic oxidation of 5-hydroxymethylfurfural, with a conversion rate of 5-hydroxymethylfurfural close to 100%, a yield of 2,5-furandicarboxylic acid above 85%, and a Faraday efficiency of over 80%.

[0079] Example 3

[0080] A) Preparation method of surface-reconstructed modified nickel-molybdenum foam electrodes (NiMo-3Cl and NiMo-3S)

[0081] Immerse the foamed nickel-molybdenum in a 1 mol / L sulfuric acid or 2 mol / L hydrochloric acid solution and let it stand for 3 hours; the rest of the operation is the same as in Example 1.

[0082] B) The method for preparing 2,5-furandicarboxylic acid by electrocatalytic oxidation of 5-hydroxymethylfurfural was carried out at a constant potential of 0.55V for 1 hour; the remaining operations were consistent with those in Example 1.

[0083] Comparative Example 3

[0084] The preparation method of blank foamed nickel-molybdenum electrode (NiMo) involves immersing it in an ethanol solution to clean surface deposits such as dust; the rest is consistent with Example 3.

[0085] The NiMo-3Cl and NiMo-3S electrodes prepared in Example 3 showed significantly improved electrocatalytic oxidation activity of 5-hydroxymethylfurfural through one-step acid etching.

[0086] The surface morphology of the NiMo-3Cl, NiMo-3S and NiMo electrodes prepared in Example 3 and Comparative Example 3 of this invention was examined.

[0087] like Figure 9 As shown, Figure 9 These are scanning electron microscope images of the NiMo-3Cl, NiMo-3S, and NiMo electrodes prepared in Example 3 and Comparative Example 3 of this invention; Figure 9 It can be seen that the surface of NiMo electrode is relatively smooth and flat, while after treatment with hydrochloric acid and sulfuric acid, the surfaces of NiMo-3Cl and NiMo-3S are etched, and a uniform array structure of nanosheets is grown in situ, which increases the surface roughness.

[0088] The electrocatalytic oxidation performance of 5-hydroxymethylfurfural by NiMo-3Cl, NiMo-3S and NiMo electrodes prepared in Example 3 and Comparative Example 3 of this invention was tested.

[0089] like Figure 10 As shown, Figure 10This is a comparative bar chart showing the 5-hydroxymethylfurfural conversion, 2,5-furandicarboxylic acid yield, and Faraday efficiency of the NiMo-3Cl, NiMo-3S, and NiMo electrodes prepared in Example 3 and Comparative Example 3 of this invention; Figure 10 It can be seen that, compared with the NiMo electrode, the acid-modified NiMo-3Cl and NiMo-3S electrodes exhibit higher electrocatalytic activity for the oxidation of 5-hydroxymethylfurfural, with a conversion rate of 5-hydroxymethylfurfural close to 100%, and the yield and Faraday efficiency of 2,5-furandicarboxylic acid both reaching over 90%.

[0090] Example 4

[0091] The preparation method is the same as in Example 1, except that the raw material is copper foam, and Cu-3Cl and Cu-3S are prepared from it.

[0092] like Figure 11 As shown, Figure 11 The X-ray diffraction patterns of Cu-3Cl and Cu-3S prepared in Example 4 of this invention are shown below. Figure 11 It can be seen that copper oxide active species were grown in situ on Cu-3S and Cu-3Cl electrodes modified by sulfuric acid or hydrochloric acid treatment.

[0093] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0094] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for modifying foamed metal, characterized in that, Includes the following steps: (1) Cut the nickel foam into 1*3cm2 pieces, immerse them in a 1mol / L sulfuric acid solution, and let them stand for 3 hours; (2) Take out the nickel foam, wash it with deionized water, and dry it in a 60°C oven for 10 hours to obtain a surface-modified nickel foam electrode.

2. A method for preparing 2,5-furandicarboxylic acid, comprising the following steps: Using modified foam metal as the working electrode, 5-hydroxymethylfurfural is added to the electrolyte solution, and electrolysis is carried out by constant potential electrolysis to obtain 2,5-furandicarboxylic acid; the modified foam metal is the modified foam metal prepared by the modification method described in claim 1.

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