A dual-morphology boron-containing Zn / Cu metal-organic framework composite material, preparation and application thereof

Abstract

The application discloses a kind of double-morphology boron-containing Zn / Cu metal organic framework composite materials and preparation and application thereof, belong to fine chemical technology field.The double-morphology boron-containing Zn / Cu metal organic framework composite material is prepared by one-pot hydrothermal reaction, and the double-morphology includes three-dimensional nanoflower structure and three-dimensional rod / cylindrical structure.Specifically, by adjusting the Zn / Cu molar ratio in the coordination process with corresponding ligand, when the Zn:Cu molar ratio reaches 1:1, the original single nanoflower structure will evolve into new three-dimensional rod / cylindrical structure, thereby forming two composite morphologies.The double-morphology boron-containing Zn / Cu metal organic framework composite material is used for the electrochemical hydrogenation reduction and electrochemical oxidation of two key reactions of furfural, and both show high activity and high selectivity.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, specifically relating to a dual-morphology boron-containing Zn / Cu metal-organic framework composite material and its preparation and application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Furfural is a multifunctional biomass-derived platform molecule extracted from agricultural waste and is an indispensable raw material in sustainable biorefineries. Through catalytic hydrogenation and other selective conversion pathways, furfural can be efficiently converted into a variety of high-value-added chemical substances. Through hydrogenation reduction, furfural can produce important chemicals including furfuryl alcohol and 2-methylfuran. Among these, furfuryl alcohol is one of the most important hydrogenation products of furfural. It can be used to synthesize furan resins and rubber, as well as pesticides and coatings, and its demand is increasing year by year. Furthermore, the catalytic oxidation of furfural to produce furoic acid is also a very important industrial chemical reaction. Furoic acid can be used as a preservative to prepare glutinous rice resin and is widely used in the preparation of fragrances, flavorings, and pharmaceuticals. Therefore, how to achieve high-value conversion of biomass furfural is of significant research importance.

[0004] The traditional process for producing furfural-based furfuryl alcohol via hydrogenation relies on high-pressure hydrogen, posing safety hazards such as high storage and transportation costs and explosion risks. Furthermore, the demanding reaction conditions result in significant energy consumption. Currently, electrocatalysis-driven biomass-derived small molecule upgrading and conversion is emerging as a green alternative, with its advantages of mild reaction conditions and controllable product selectivity becoming increasingly apparent. In addition, the synthesis of furoic acid is mainly carried out through traditional thermocatalytic processes, such as the Cannizaro reaction under alkaline conditions. However, this reaction also produces an equal amount of furfuryl alcohol, limiting the amount of the desired substance produced and increasing the complexity of separation. In contrast, the electrocatalytic oxidation of furfural is a targeted and environmentally friendly alternative to traditional synthetic methods.

[0005] The inherent structural determinism and chemical tunability of metal-organic frameworks (MOFs) with exposed sites make them ideal model systems for exploring the electrocatalytic pathway of furfural. However, research on the active site mechanism of MOFs in furfural electrocatalysis is relatively limited, and it is relatively difficult to prepare target products with high selectivity and high Faradaic efficiency in the electrochemical conversion of furfural, which hinders the efficient catalytic reaction. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a dual-morphology boron-containing Zn / Cu metal-organic framework composite material, its preparation, and its applications. The boron-containing Zn / Cu metal-organic framework material of the present invention exhibits two differentiated morphologies (three-dimensional nanoflower structure and three-dimensional rod / column structure), each displaying unique structural advantages. First, the three-dimensional nanoflower structure possesses two key structural advantages. On one hand, it constructs numerous mesoporous and macroporous transport channels, accelerating the diffusion rate of reactants and products, thereby effectively alleviating the limitations of mass transfer. On the other hand, the full exposure of numerous boron-containing active sites at the edges of the nanosheets significantly increases the density of catalytic active centers, further enhancing the overall catalytic activity. Second, the three-dimensional column / rod structure exhibits excellent structural stability and ordered crystal plane arrangement. It not only maintains structural integrity in complex electrocatalytic reaction systems, reducing the loss of active components, but also optimizes electron transport paths through its ordered crystal plane structure, reducing charge transfer resistance, thereby ensuring the continuous and efficient conduction of the catalytic reaction. Experimental verification shows that the prepared material exhibits excellent catalytic performance in two key reactions of furfural electrocatalysis (i.e., electrocatalytic hydrogenation reduction and electrocatalytic oxidation). Thanks to the complementary and synergistic effects of its dual structural features, it can not only promote the rapid desorption of products (such as furfuryl alcohol and furoic acid), but also inhibit the formation of byproducts caused by excessive reaction, thereby improving the selectivity of the target product.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a dual-morphology boron-containing Zn / Cu metal-organic framework composite material, wherein the dual-morphology boron-containing Zn / Cu metal-organic framework composite material is Zn / Cu-MBON, where MBON represents metal-borate-organic framework, and the dual morphology is a three-dimensional nanoflower-like layered porous structure and a three-dimensional rod / column structure assembled from nanosheets.

[0009] In one or more embodiments, the molar ratio of Zn to Cu is (0.9~1.1):(0.9~1.1), preferably 1:1. The ratio of Zn to Cu significantly affects the morphology of the material; as the proportion of copper increases, the morphology also changes. Without copper, the boron-zinc-based three-dimensional metal-organic nanosheet material obtained with only zinc exhibits a single nanoflower-like morphology. Adding a small amount of copper also results in a single nanoflower-like morphology. When the zinc-copper molar ratio is equal, the material exhibits a dual-morphology structure, with both three-dimensional nanoflower-like and three-dimensional rod / column-like morphologies coexisting. Even when the copper proportion is greater than that of zinc, the material also exhibits a dual-morphology structure; however, excessive copper addition leads to irregular morphology, such as irregular three-dimensional rod / column structures. Furthermore, the morphology of the material also affects its catalytic performance. According to subsequent experimental results based on this invention, only a Zn to Cu molar ratio of 1:1 yields a dual-morphology structure material with superior catalytic performance.

[0010] Secondly, the present invention provides a method for preparing the above-mentioned dual-morphology boron-containing Zn / Cu metal-organic framework composite material, comprising the following steps:

[0011] Zinc salt, copper salt, organic ligand, boric acid, and solvent are prepared by a one-pot hydrothermal reaction.

[0012] The organic ligand is imidazole.

[0013] In one or more embodiments, the specific preparation method of the one-pot hydrothermal reaction is as follows:

[0014] Step 1: Dissolve the zinc salt and copper salt together in a solvent to obtain solution a; dissolve the organic ligand and boric acid in a solvent to obtain solution b; mix solution a and solution b and stir.

[0015] Step 2: Then, the mixture is subjected to hydrothermal reaction, centrifuged, washed, and dried to obtain the final product.

[0016] In one or more embodiments, in step 1, the mixture is stirred for 20-60 minutes, such as 20, 30, 40, 50, or 60 minutes. Appropriate stirring time ensures that solution a and solution b are thoroughly mixed to obtain a blue solution.

[0017] In one or more embodiments, in step 1, the molar ratio of the total of the two metal salts, boric acid and imidazole is (3~4):(22~25):(5~10), preferably (3.25~3.85):(22.4~22.6):(7.3~7.4), and more preferably (3.7~3.8):(22.4~22.6):(7.3~7.4).

[0018] In one or more embodiments, in step 1, the zinc salt is one or more of zinc sulfate, zinc nitrate, zinc acetate, and zinc chloride. In step 1, the copper salt is one or more of copper sulfate, copper nitrate, copper acetate, and copper chloride.

[0019] In one or more embodiments, in step 1, the concentration of the zinc salt solution is 1.5~2.5 mol / L, specifically 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, or 2.5 mol / L. The concentration of the copper salt solution is also 1.5~2.5 mol / L, specifically 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, or 2.5 mol / L.

[0020] In one or more embodiments, in step 1, the ratio of imidazole to water in solution b is (7~8 mmol):(20~40 mL), preferably (7.3~7.4 mmol):(25~35 mL).

[0021] In one or more embodiments, in step 1, the solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, acetone, formic acid, methanol, ethanol, and water.

[0022] In one or more embodiments, in step 2, the temperature of the hydrothermal reaction is 130~160℃, specifically 130℃, 140℃, 145℃, 150℃, 155℃, or 160℃, preferably 145~155℃, the heating rate is 4~8℃ / min, specifically 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, or 8℃ / min, and the reaction time is 5~10h, specifically 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 9h, or 10h, preferably 6~9h.

[0023] In one or more embodiments, the present invention does not particularly limit the specific conditions for washing, and can be carried out according to methods in the art, washing until the solution is clear. For example, anhydrous ethanol can be used for multiple washes.

[0024] In one or more embodiments, the present invention does not particularly limit the drying conditions, and the drying can be carried out according to methods in the art. For example, vacuum drying can be used, with a drying temperature of 70~90°C and a drying time of 6~24 hours.

[0025] In a preferred embodiment, in step 2, the mixture undergoes a hydrothermal reaction, and after naturally cooling to room temperature, the white precipitate is collected by centrifugation, washed with water, and dried overnight. The resulting blue sample is the dual-morphology boron-containing Zn / Cu metal-organic framework composite material.

[0026] Thirdly, the present invention provides the application of the above-mentioned dual-morphology boron-containing Zn / Cu metal-organic framework composite material in the electrochemical hydrogenation reduction and / or electrochemical oxidation reactions of aldehyde biomass derivatives. The aldehyde biomass derivative is furfural. Preferably, it is used in the electrochemical hydrogenation reduction and / or electrochemical oxidation reactions of furfural.

[0027] Fourthly, this invention provides a method for electrochemical hydrogenation reduction, using the aforementioned dual-morphology boron-containing Zn / Cu metal-organic framework composite material as a catalyst to perform an electrochemical hydrogenation reduction reaction on aldehyde biomass derivatives. The aldehyde biomass derivative is furfural.

[0028] The method specifically includes: employing a three-electrode system, the working electrode comprising a substrate and a boron-containing Zn / Cu metal-organic framework composite material with the above-mentioned dual morphology; the reference electrode being a mercury / mercury oxide (Hg / HgO) reference electrode; and the counter electrode being a platinum sheet electrode, which is then subjected to electrochemical hydrogen reduction.

[0029] In one or more embodiments, the electrolyte is a KOH solution with a concentration of 0.85~1.2 M, preferably 1 M. In one or more embodiments, the voltage for the electrocatalytic reduction of furfural is -0.45~-0.65V vs. RHE, preferably -0.55~-0.6V vs. RHE, and most preferably -0.6V vs. RHE. The total charge of the reaction is 110~120C, preferably 115C.

[0030] Fifthly, the present invention provides a method for an electrochemical oxidation reaction, using the aforementioned dual-morphology boron-containing Zn / Cu metal-organic framework composite material as a catalyst to perform an electrochemical oxidation reaction on aldehyde biomass derivatives. The aldehyde biomass derivative is furfural.

[0031] The method specifically includes: the working electrode comprising a substrate and a boron-containing Zn / Cu metal-organic framework composite material with the above-mentioned dual morphology; the reference electrode is a mercury / mercury oxide (Hg / HgO) reference electrode; and the counter electrode is a platinum sheet electrode, which can be subjected to electrochemical oxidation.

[0032] In one or more embodiments, the electrolyte is a KOH solution with a concentration of 0.85~1.2 M, preferably 1 M.

[0033] In one or more embodiments, the voltage for the electrocatalytic oxidation of furfural is 1.2~1.45V vs. RHE, preferably 1.3~1.35V vs. RHE, and most preferably 1.35V vs. RHE. The total charge of the reaction is 110~120C, preferably 115C.

[0034] One or more of the above technical solutions have the following advantages or beneficial effects:

[0035] 1. This invention provides a dual-morphology boron-containing Zn / Cu metal-organic framework composite material, namely Zn / Cu-MBON, which is manufactured via a simple hydrothermal method. Specifically, copper and zinc salts are used as co-metallic precursors. By adjusting the Zn / Cu molar ratio during coordination with the corresponding ligands, a significant morphological evolution was observed in the sample with increasing Cu content. When the Zn:Cu molar ratio reaches 1:1, the original single nanoflower structure evolves into a new three-dimensional rod / column structure, thus forming two composite morphologies. Subsequently, this material was used in two key reactions of furfural: electrochemical hydrogenation reduction and electrochemical oxidation. Notably, Zn / Cu-MBON exhibits a unique dual-structure characteristic: a 3D nanoflower-like layered porous structure assembled from nanosheets and a three-dimensional rod / column structure. This structural uniqueness helps to maximize the exposure of edge active sites and improve mass transfer efficiency.

[0036] 2. The present invention provides a dual-morphology boron-containing Zn / Cu metal-organic framework composite material, which, compared to single-metal Zn-MOF (MBON-2) catalysts, not only retains its three-dimensional self-assembled nanoflower structure (ensuring high exposure of active sites), but also derives a three-dimensional rod / column secondary structure. These two structures synergistically optimize catalytic performance, accelerating the adsorption and activation of substrate molecules at catalytic active sites.

[0037] 3. This invention innovatively constructs a boron-containing Zn / Cu metal-organic framework composite material (Zn / Cu-MBON), achieving the controllable synthesis of a dual-morphology material through a co-coordination strategy of zinc / copper metal salts and ligands. The synergistic effect of the high-density boron active sites and Zn / Cu bimetallic centers in the material endows it with excellent bifunctional catalytic properties: exhibiting high activity and high selectivity in both the electrocatalytic hydrogenation and electrocatalytic oxidation of furfural. Its high intrinsic activity induced by its electron-rich characteristics further ensures the superior catalytic performance.

[0038] 4. The dual-morphology boron-containing Zn / Cu metal-organic framework material of this invention was used for the electrochemical hydrogenation reduction reaction of furfural. Constant voltage electrolysis test was carried out at -0.6V vs. RHE voltage. By controlling the amount of charge, when the total charge of the reaction reached 115C, the selectivity of furfuryl alcohol could reach 98.5% and the conversion rate of furfural could reach 97.9%.

[0039] 5. The dual-morphology boron-containing Zn / Cu metal-organic framework material of this invention was used for the electrochemical oxidation reaction of furfural. Constant voltage electrolysis test was carried out at 1.35V vs. RHE voltage. By controlling the amount of charge, when the total charge of the reaction reached 115C, the selectivity of furoic acid could reach 99.2% and the conversion rate of furfural could reach 98.4%. Attached Figure Description

[0040] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0041] Figure 1 The diffraction patterns (PXRD) of the dual-morphology boron-containing Zn / Cu metal-organic framework composite material Zn1Cu1-MBON prepared in Example 1 of this invention are compared with those of MBON-2, Zn4Cu1-MBON, Zn2Cu1-MBON and Zn1Cu2-MBON prepared in the comparative examples.

[0042] Figure 2 The image shows a scanning electron microscope (SEM) image of the dual-morphology boron-containing Zn / Cu metal-organic framework composite material Zn1Cu1-MBON prepared in Example 1 of this invention; where a is a three-dimensional rod / column morphology and b is a three-dimensional nanoflower morphology.

[0043] Figure 3 This is a scanning electron microscope (SEM) image of MBON-2, a nanoflower-like boron-containing three-dimensional metal-organic framework material prepared in Comparative Example 1 of this invention.

[0044] Figure 4 The image shows a scanning electron microscope (SEM) image of the nanoflower-like boron-containing three-dimensional metal-organic framework material Zn4Cu1-MBON-2 prepared in Comparative Example 2 of this invention.

[0045] Figure 5 This is a scanning electron microscope (SEM) image of the nanoflower-like boron-containing three-dimensional metal-organic framework material Zn2Cu1-MBON-2 prepared in Comparative Example 3 of this invention.

[0046] Figure 6 This is a scanning electron microscope (SEM) image of the material Zn1Cu2-MBON-2 prepared in Comparative Example 4 of this invention.

[0047] Figure 7 The graph shows the reaction performance of the catalytic material prepared in Example 1 of this invention for the catalytic reduction and conversion of furfural under different reaction voltages.

[0048] Figure 8This is a reaction cycle stability diagram of the dual-morphology boron-containing Zn / Cu metal-organic framework material prepared in Example 1 of the present invention during electrocatalytic furfural reduction;

[0049] Figure 9 The graph shows the reaction performance of the catalytic material prepared in Example 1 of this invention at different reaction voltages for the electro-oxidation conversion of furfural.

[0050] Figure 10 This is a reaction cycle stability diagram of the dual-morphology boron-containing Zn / Cu metal-organic framework material prepared in Example 1 of the present invention during the electrocatalytic oxidation of furfural. Detailed Implementation

[0051] Explanation of terms involved:

[0052] MBON: The metallic component in MBON is zinc, which is the single nanoflower-shaped boron-zinc-based three-dimensional metal-organic nanosheet material prepared in Comparative Example 1.

[0053] Zn1Cu1-MBON: The molar ratio of Zn to Cu is 1:1, which is the dual-morphology boron-containing Zn / Cu metal-organic framework material prepared in Example 1.

[0054] Zn2Cu1-MBON: The molar ratio of Zn to Cu is 2:1, which is the single nanoflower-like boron-containing Zn / Cu metal-organic framework material prepared in Comparative Example 3.

[0055] Zn4Cu1-MBON: The molar ratio of Zn to Cu is 4:1, which is the single nanoflower-like boron-containing Zn / Cu metal-organic framework material prepared in Comparative Example 2.

[0056] Zn1Cu2-MBON: The molar ratio of Zn to Cu is 1:2, which is the boron-containing Zn / Cu metal-organic framework material prepared in Comparative Example 4.

[0057] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0058] Example 1:

[0059] A method for preparing a boron-containing Zn / Cu metal-organic framework material, comprising the following steps:

[0060] Step 1: Take 1.87 mmol zinc nitrate hexahydrate as zinc salt and 1.87 mmol copper nitrate pentahydrate as copper salt and add them together to 30 mL of deionized water to obtain solution a;

[0061] Then, 22.5 mmol of boric acid and 7.36 mmol of imidazole were added together to 30 mL of deionized water to obtain solution b;

[0062] Step 2: Mix and stir solutions a and b for 30 min, transfer to a polytetrafluoroethylene reactor, heat to 150 °C, and react for 6 h. After the reaction is complete, wait for the temperature to drop to room temperature, centrifuge the precipitate, wash it three times with anhydrous ethanol, and dry it at 80 °C for 10 h to obtain a blue powder, which is the boron-containing Zn / Cu metal-organic framework material.

[0063] Figure 1 The XRD patterns of the boron-containing Zn / Cu metal-organic framework material prepared in Example 1, MBON-2 prepared in Comparative Example 1, Zn4Cu1-MBON prepared in Comparative Example 2, Zn2Cu1-MBON prepared in Comparative Example 3, and Zn1Cu2-MBON prepared in Comparative Example 4 are shown in comparison. The comparison confirms that all characteristic peaks of the sample in the catalytic material MBON-2 are retained, and a new characteristic peak appears at approximately 16° in Example 1, which may be related to the newly emerging three-dimensional rod / column secondary structure. Furthermore, it was found that the characteristic peaks in Zn2Cu1-MBON and Zn4Cu1-MBON did not change compared to MBON-2. However, with further increases in copper salt, new characteristic peaks appeared in the XRD diffraction patterns of Zn1Cu1-MBON prepared in Example 1 and Zn1Cu2-MBON prepared in Comparative Example 4.

[0064] Figure 2 The SEM images of the dual-morphology boron-containing Zn / Cu metal-organic framework catalyst show that the Zn1Cu1-MBON crystal structure exhibits two structures. Compared with the single-metal Zn-MOF (MBON-2) catalyst, it not only retains its three-dimensional self-assembled nanoflower structure (ensuring high exposure of active sites), but also constructs a three-dimensional rod / column secondary structure. The two structures work together to optimize catalytic performance and accelerate the adsorption and activation of substrate molecules at the catalytic active sites.

[0065] Example 2:

[0066] Unlike Example 1, this example replaces water in step one with N,N-dimethylformamide. The specific preparation method is as follows:

[0067] A method for preparing a boron-containing Zn / Cu metal-organic framework material, comprising the following steps:

[0068] Step 1: Take 1.87 mmol zinc nitrate hexahydrate as the zinc salt and 1.87 mmol copper nitrate pentahydrate as the copper salt and add them together to 30 mL of N,N-dimethylformamide to obtain solution a;

[0069] Then, 22.5 mmol of boric acid and 7.36 mmol of imidazole were added together to 30 mL of N,N-dimethylformamide to obtain solution b;

[0070] Step 2: Mix and stir solutions a and b for 30 min, transfer to a polytetrafluoroethylene reactor, heat to 150 °C, and react for 6 h. After the reaction is complete, wait for the temperature to drop to room temperature, centrifuge the precipitate, wash it three times with anhydrous ethanol, and dry it at 80 °C for 10 h to obtain a blue powder, which is the boron-containing Zn / Cu metal-organic framework material.

[0071] Example 3:

[0072] Unlike Example 1, this example replaces the reaction time of 6 hours in step two with 9 hours. The specific preparation method is as follows:

[0073] A method for preparing a boron-containing Zn / Cu metal-organic framework material, comprising the following steps:

[0074] Step 1: Take 1.87 mmol zinc nitrate hexahydrate as the zinc salt and 1.87 mmol copper nitrate pentahydrate as the copper salt and add them together to 30 mL of deionized water to obtain solution a;

[0075] Then, 22.5 mmol of boric acid and 7.36 mmol of imidazole were added together to 30 mL of deionized water to obtain solution b;

[0076] Step 2: Mix and stir solutions a and b for 30 min, transfer to a polytetrafluoroethylene reactor, heat to 150 °C, and react for 9 h. After the reaction is complete, wait for the temperature to drop to room temperature, centrifuge the precipitate, wash it three times with anhydrous ethanol, and dry it at 80 °C for 10 h to obtain a blue powder, which is the boron-containing Zn / Cu metal-organic framework material.

[0077] Example 4:

[0078] Unlike Example 1, this example replaces the reaction temperature of 150°C in step two with 140°C. The specific preparation method is as follows:

[0079] A method for preparing a boron-containing Zn / Cu metal-organic framework material, comprising the following steps:

[0080] Step 1: Take 1.87 mmol zinc nitrate hexahydrate as the zinc salt and 1.87 mmol copper nitrate pentahydrate as the copper salt and add them together to 30 mL of water to obtain solution a;

[0081] Then, 22.5 mmol of boric acid and 7.36 mmol of imidazole were added together to 30 mL of water to obtain solution b;

[0082] Step 2: Mix and stir solutions a and b for 30 min, transfer to a polytetrafluoroethylene reactor, heat to 140 °C, and react for 6 h. After the reaction is complete, wait for the temperature to drop to room temperature, centrifuge the precipitate, wash it three times with anhydrous ethanol, and dry it at 80 °C for 10 h to obtain a blue powder, which is the boron-containing Zn / Cu metal-organic framework material.

[0083] Example 5:

[0084] Unlike Example 1, this example replaces zinc nitrate hexahydrate in step one with zinc sulfate hexahydrate. The specific preparation method is as follows:

[0085] A method for preparing a boron-containing Zn / Cu metal-organic framework material, comprising the following steps:

[0086] Step 1: Take 1.87 mmol zinc sulfate hexahydrate as zinc salt and 1.87 mmol copper nitrate pentahydrate as copper salt and add them together to 30 mL of deionized water to obtain solution a;

[0087] Then, 22.5 mmol of boric acid and 7.36 mmol of imidazole were added together to 30 mL of deionized water to obtain solution b;

[0088] Step 2: Mix and stir solutions a and b for 30 min, transfer to a polytetrafluoroethylene reactor, heat to 150 °C, and react for 6 h. After the reaction is complete, wait for the temperature to drop to room temperature, centrifuge the precipitate, wash it three times with anhydrous ethanol, and dry it at 80 °C for 10 h to obtain a blue powder, which is the boron-containing Zn / Cu metal-organic framework material.

[0089] Example 6:

[0090] Unlike Example 1, this example replaces copper nitrate pentahydrate in step one with copper sulfate pentahydrate. The specific preparation method is as follows:

[0091] The preparation method of a boron-containing Zn / Cu metal-organic framework material has the following steps:

[0092] Step 1: Take 1.87 mmol zinc nitrate hexahydrate as the zinc salt and 1.87 mmol copper sulfate pentahydrate as the copper salt and add them together to 30 mL of deionized water to obtain solution a;

[0093] Then, 22.5 mmol of boric acid and 7.36 mmol of imidazole were added together to 30 mL of deionized water to obtain solution b;

[0094] Step 2: Mix and stir solutions a and b for 30 min, transfer to a polytetrafluoroethylene reactor, heat to 150 °C, and react for 6 h. After the reaction is complete, wait for the temperature to drop to room temperature, centrifuge the precipitate, wash it three times with anhydrous ethanol, and dry it at 80 °C for 10 h to obtain a blue powder, which is the boron-containing Zn / Cu metal-organic framework material.

[0095] Comparative Example 1

[0096] A method for preparing a single, flower-like, boron-zinc-based, three-dimensional metal-organic nanosheet material, comprising the following steps:

[0097] Step 1: Add 3.74 mmol of zinc nitrate hexahydrate and 22.5 mmol of boric acid to 15 mL of deionized water to obtain solution a; add 7.36 mmol of imidazole as an organic ligand to 15 mL of deionized water to obtain solution b;

[0098] Step 1: Mix solution a and solution b, stir for 30 min, transfer to a polytetrafluoroethylene reactor, heat to 150 ℃, and react for 6 h. After the reaction is completed, wait for the temperature to drop to room temperature, centrifuge the precipitate, wash it 3 times with anhydrous ethanol, and dry it at 80 ℃ for 12 h to obtain a white powder, which is the three-dimensional nanoflower-like Zn-based MBON-2 precursor.

[0099] Comparative Example 2:

[0100] By controlling the ratio of zinc salt to copper salt, a single nanoflower-like boron-containing Zn / Cu metal-organic framework material with a Zn:Cu ratio of 4:1 was synthesized. The preparation steps are as follows:

[0101] Step 1: Take 3.002 mmol zinc nitrate hexahydrate as zinc salt and 0.7505 mmol copper nitrate pentahydrate as copper salt and add them together to 30 mL of water to obtain solution a;

[0102] Then, 22.5 mmol of boric acid and 7.36 mmol of imidazole were added together to 30 mL of water to obtain solution b;

[0103] Step two: Mix solutions a and b and stir for 30 minutes, then transfer to a polytetrafluoroethylene (PTFE) reactor. Heat to 150°C and react for 6 hours. After the reaction, allow the temperature to drop to room temperature, centrifuge the precipitate, wash three times with anhydrous ethanol, and dry at 80°C for 10 hours to obtain a blue powder, which is the boron-containing Zn4Cu1-MBON metal-organic framework material. Figure 4 As shown, the sample exhibits a three-dimensional nanoflower morphology.

[0104] Comparative Example 3: By controlling the ratio of zinc salt to copper salt, a single nanoflower-like boron-containing Zn / Cu metal-organic framework material with a Zn:Cu ratio of 2:1 was synthesized. The preparation method is as follows:

[0105] Step 1: Take 2.509 mmol of zinc nitrate hexahydrate as the zinc salt and 1.250 mmol of copper nitrate pentahydrate as the copper salt and add them together to 30 mL of water to obtain solution a;

[0106] Then, 22.5 mmol of boric acid and 7.36 mmol of imidazole were added together to 30 mL of water to obtain solution b;

[0107] Step two: Mix solutions a and b and stir for 30 minutes, then transfer to a polytetrafluoroethylene (PTFE) reactor. Heat to 150°C and react for 6 hours. After the reaction, wait for the temperature to drop to room temperature, centrifuge the precipitate, wash it three times with anhydrous ethanol, and dry it at 80°C for 10 hours to obtain a blue powder, which is the boron-containing Zn₂Cu₁-MBON metal-organic framework material. Figure 5 As shown, the sample exhibits a three-dimensional nanoflower morphology.

[0108] Comparative Example 4: By controlling the ratio of zinc salt to copper salt, a boron-containing Zn / Cu metal-organic framework material with a Zn:Cu ratio of 1:2 was synthesized. The preparation method is as follows:

[0109] Step 1: Take 1.250 mmol zinc nitrate hexahydrate as zinc salt and 2.509 mmol copper nitrate pentahydrate as copper salt and add them together to 30 mL of water to obtain solution a;

[0110] Then, 22.5 mmol of boric acid and 7.36 mmol of imidazole were added together to 30 mL of water to obtain solution b;

[0111] Step 2: Mix and stir solutions a and b for 30 min, transfer to a polytetrafluoroethylene reactor, heat to 150 °C, and react for 6 h. After the reaction is complete, wait for the temperature to drop to room temperature, centrifuge the precipitate, wash it three times with anhydrous ethanol, and dry it at 80 °C for 10 h to obtain a blue powder, which is the boron-containing Zn1Cu2-MBON metal-organic framework material.

[0112] Figure 6 The SEM image of Zn1Cu2-MBON prepared in Comparative Example 4 shows that it also exhibits a dual-morphology structure. The nanoflower structure remains, but it has been transformed into a fragmented, plate-like morphology. Furthermore, the excessive addition of copper salt disrupts the original three-dimensional rod-like structure, resulting in an irregular rod-like structure.

[0113] Application Example 1:

[0114] The materials prepared in the examples and comparative examples were used to prepare furfuryl alcohol by the electrocatalytic hydrogenation of furfural, including the following steps:

[0115] Step 1: First, take 0.005 g of the catalyst material prepared in the examples and comparative examples and add it to a mixed solution of 600 μL ethanol, 300 μL and 50 μL perfluorosulfonic acid resin (Nafion, 5wt.%). Then, sonicate for 30 min to obtain a uniformly dispersed solution. Then, take 200 μL of the dispersion and transfer it to a spray gun. Spray it evenly on a 2 cm × 1 cm hydrophobic carbon cloth and dry it to obtain the catalyst material.

[0116] Step two: Furfural electrocatalytic hydrogenation was carried out at room temperature in a standard three-electrode H-type electrolytic cell. The H-type electrolytic cell was separated by a Nafion 117 membrane. The prepared catalyst electrode served as the working electrode, a platinum sheet as the counter electrode, and a mercury / mercury oxide (Hg / HgO) electrode as the reference electrode. The electrolyte was a 1 M KOH solution. Furfural was electrolytically hydrogenated using a Chenhua electrochemical workstation (CHI760e) with a constant potential setting. The reaction voltage was -0.4 to -0.65 V vs. RHE, and the total charge was 115 C.

[0117] After the reaction was complete, the reaction solution was removed, and the conversion rate of the reactants and the selectivity of the products were evaluated using liquid chromatography (Hitachi, Primaide). The performance results for the hydrogenation of furfural to furfuryl alcohol are as follows: Figure 7 As shown in the figure, the hydrogenation results show that the novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic nanosheet catalyst of this invention exhibits a furfuryl alcohol selectivity of over 88% at all potentials, and a furfuryl alcohol selectivity of 98.5% at the optimal potential. The furfural conversion rate can reach 97.9%, indicating that the catalyst has excellent furfural conversion capability.

[0118] This dual-morphology boron-containing Zn1Cu1-MBON metal-organic framework material also exhibits excellent cycling stability. Figure 8 This indicates that the material still maintains good furfural hydrogenation activity after 7 cycles.

[0119] Experimental Results and Performance Analysis

[0120] The dual-morphology boron-containing Zn / Cu-MBON metal-organic framework material prepared in the examples and the material prepared in the comparative examples were used for the electrocatalytic hydrogenation of furfural at -0.6V vs. RHE. The reactivity of different catalytic materials was investigated, as shown in Table 1.

[0121] Table 1. Comparison of furfural electrocatalytic hydrogenation performance between the materials prepared in the examples and the comparative examples.

[0122]

[0123] As can be seen from the comparison of the electrocatalytic furfural reduction results in the table above, the dual-morphology boron-containing Zn / Cu-MBON metal-organic framework material prepared in this invention exhibits strong reactivity, far exceeding the catalyst reactivity of the comparative single-morphology boron-containing Zn / Cu metal-organic framework material. The dual-morphology boron-containing Zn / Cu-MBON metal-organic framework material prepared in this invention not only retains its three-dimensional self-assembled nanoflower structure (ensuring high exposure of active sites), but also constructs a three-dimensional rod / column secondary structure. These two structures synergistically optimize catalytic performance, accelerating the adsorption and activation of substrate molecules at the catalytic active sites. Simultaneously, the synergistic effect of the high-density boron active sites and the Zn / Cu bimetallic centers endows it with excellent bifunctional catalytic properties, exhibiting high activity and high selectivity in both the electrocatalytic hydrogenation and electrocatalytic oxidation of furfural.

[0124] Application Example 2

[0125] The materials prepared in the examples and comparative examples were used for the electrocatalytic oxidation of furfural, including the following steps:

[0126] Step 1: First, take 0.005 g of the catalyst material prepared in the examples and comparative examples and add it to a mixed solution of 600 μL ethanol, 300 μL and 50 μL perfluorosulfonic acid resin (Nafion, 5wt.%). Then, sonicate for 30 min to obtain a uniformly dispersed solution. Then, take 200 μL of the dispersion and transfer it to a spray gun. Spray it evenly on a 2 cm × 1 cm hydrophobic carbon cloth and dry it to obtain the catalyst material.

[0127] Step two: The electrocatalytic oxidation of furfural was carried out at room temperature in a standard three-electrode H-type electrolytic cell. The H-type electrolytic cell was separated by a Nafion 117 membrane. The prepared catalyst electrode served as the working electrode, the platinum sheet as the counter electrode, and the mercury / mercury oxide (Hg / HgO) electrode as the reference electrode. The electrolyte was a 1 M KOH solution. The electrocatalytic oxidation of furfural was performed using a Chenhua electrochemical workstation (CHI760e) with a constant potential setting. The reaction voltage was 1.2 to 1.45 V vs. RHE, and the total charge was 115 C.

[0128] After the reaction was complete, the reaction solution was removed, and the conversion rate of the reactants and the selectivity of the products were evaluated using liquid chromatography (Hitachi, Primaide). The performance results for the oxidation of furfural to furoic acid are as follows: Figure 9 As shown in the figure, the electrocatalytic oxidation results show that the dual-morphology boron-containing Zn / Cu-MBON metal-organic framework catalyst of this invention achieves a furoate Faraday efficiency and selectivity of over 95% at the optimal potential. Furthermore, the furfural conversion rate and Faraday efficiency exhibit a volcano-like trend with increasing voltage, indicating that the potential has a significant impact on the furfural conversion ability of this catalyst.

[0129] This dual-morphology boron-containing Zn1Cu1-MBON metal-organic framework material also exhibits excellent cycling stability. Figure 10 This indicates that the material still maintains good furfural electro-oxidation activity after 7 cycles.

[0130] Table 2. Comparison of furfural electrochemical oxidation performance of materials prepared in the Examples and Comparative Examples

[0131]

[0132] The formula for calculating the Faraday efficiency (FEx) of the target product x is: Where n x Let N be the amount of substance (mol) of the target product x, N be the number of electrons transferred when the target product x is generated (N is 2 when the product is furfuryl alcohol or furoic acid), and F be the Faraday constant (96485 C mol). -1 Q is the amount of charge (C) that generates x transfer.

[0133] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-morphology boron-containing Zn / Cu metal-organic framework composite material, characterized in that, The dual-morphology boron-containing Zn / Cu metal-organic framework composite material is Zn / Cu-MBON, where MBON represents metal-borate-organic framework. The dual morphology consists of a three-dimensional nanoflower-like layered porous structure assembled from nanosheets and a three-dimensional rod / column structure. The preparation method of the dual-morphology boron-containing Zn / Cu metal-organic framework composite material includes the following steps: Zinc salt, copper salt, organic ligand, boric acid, and solvent are prepared by a one-pot hydrothermal reaction. The organic ligand is imidazole; The molar ratio of Zn to Cu is (0.9~1.1):(0.9~1.1); The total amount of zinc salt and copper salt, and the molar ratio of boric acid and imidazole are (3~4):(22~25):(5~10); The hydrothermal reaction temperature is 130~160℃, the heating rate is 4~8℃ / min, and the reaction time is 5~10h.

2. The dual-morphology boron-containing Zn / Cu metal-organic framework composite material according to claim 1, characterized in that, The molar ratio of Zn to Cu is 1:

1.

3. A method for preparing the dual-morphology boron-containing Zn / Cu metal-organic framework composite material according to claim 1 or 2, characterized in that, Includes the following steps: Zinc salt, copper salt, organic ligand, boric acid, and solvent are prepared by a one-pot hydrothermal reaction. The organic ligand is imidazole; The molar ratio of Zn to Cu is (0.9~1.1):(0.9~1.1); The total amount of zinc salt and copper salt, and the molar ratio of boric acid and imidazole are (3~4):(22~25):(5~10).

4. The preparation method according to claim 3, characterized in that, The specific preparation method of the one-pot hydrothermal reaction is as follows: Step 1: Dissolve the zinc salt and copper salt together in a solvent to obtain solution a; dissolve the organic ligand and boric acid in a solvent to obtain solution b; mix solution a and solution b and stir. Step 2: Then, the mixture is subjected to hydrothermal reaction, centrifuged, washed, and dried to obtain the final product.

5. The preparation method according to claim 4, characterized in that, In step 1, stir the mixture for 20-60 minutes after mixing; In step 1, the zinc salt is one or more of zinc sulfate, zinc nitrate, zinc acetate, and zinc chloride; In step 1, the copper salt is one or more of copper sulfate, copper nitrate, copper acetate, and copper chloride.

6. The preparation method according to claim 4, characterized in that, In step 1, the concentration of the zinc salt solution is 1.5~2.5 mol / L; the concentration of the copper salt solution is 1.5~2.5 mol / L. In step 1, the solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, acetone, formic acid, methanol, ethanol, and water.

7. The preparation method according to claim 3 or 4, characterized in that, The hydrothermal reaction temperature is 130~160℃, the heating rate is 4~8℃ / min, and the reaction time is 5~10h.

8. The application of a bimorphic boron-containing Zn / Cu metal-organic framework composite material according to claim 1 or 2, or a bimorphic boron-containing Zn / Cu metal-organic framework composite material obtained by the preparation method according to any one of claims 3 to 7, in the electrochemical hydrogenation reduction and / or electrochemical oxidation reaction of aldehyde biomass derivatives.

9. A method for an electrochemical hydrogenation reduction reaction, characterized in that, Using the dual-morphology boron-containing Zn / Cu metal-organic framework composite material according to claim 1 or 2, or the dual-morphology boron-containing Zn / Cu metal-organic framework composite material obtained by the preparation method according to any one of claims 3 to 7, as a catalyst, an electrochemical hydrogenation reduction reaction of aldehyde biomass derivatives is carried out.

10. A method for an electrochemical oxidation reaction, characterized in that, Using the dual-morphology boron-containing Zn / Cu metal-organic framework composite material according to claim 1 or 2, or the dual-morphology boron-containing Zn / Cu metal-organic framework composite material obtained by the preparation method according to any one of claims 3 to 7, as a catalyst, an electrochemical oxidation reaction of aldehyde biomass derivatives is carried out.

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