A method for the preparation of an electrocatalyst for the hydrogenation of carbonyl compounds to alcohols and the use thereof

Abstract

The application provides a preparation method of an electrocatalyst for preparing alcohol compounds by hydrogenation of carbonyl compounds, comprising the following steps: (S1) preparing a condensation product by condensation polymerization of o-vanillin and a binary amine as an organic ligand; (S2) preparing a cerium complex by using a cerium salt and the organic ligand, and performing heat treatment in an inert atmosphere to obtain an amorphous cerium oxide-carbon composite material; (S3) dispersing the amorphous cerium oxide-carbon composite material in a weak alkaline solution, adding a copper salt solution dropwise under stirring, washing, drying, and then performing heat treatment under protection of an inert atmosphere, and cooling to obtain the catalyst. The electrocatalyst prepared by the method is used in a reaction for preparing corresponding alcohol compounds by electrocatalytic hydrogenation of carbonyl compounds, and solves the problems of low reaction activity, poor product selectivity and difficult large-scale application of existing hydrogenation electrocatalysts.

Description

Technical Field

[0001] This invention belongs to the field of inorganic composite catalysts, specifically relating to a method for preparing an electrocatalyst for the hydrogenation of carbonyl compounds to alcohols and its applications. Background Technology

[0002] Alcohols are an important class of chemical products with wide applications in pharmaceuticals, energy, and fine chemical synthesis. Selective hydrogenation of carbonyl compounds is a major method for preparing alcohols. Furfural, for example, is an important carbonyl compound and currently the only biomass platform compound produced on a large industrial scale. It can be derived from lignocellulose, with a mature production process and an annual output of up to 300,000 tons. Selective hydrogenation of furfural yields furfuryl alcohol, a high-value product. Furfuryl alcohol can be dehydrated by acid catalysis to produce furan resin, which can be used in composite materials, adhesives, and coatings. However, industrially, furfuryl alcohol is mainly produced through the thermocatalytic hydrogenation of furfural, a process involving high temperature and pressure, and requiring a toxic copper chromite catalyst. Therefore, developing a green and safe alternative catalyst is of great significance. However, the hydrogenation reaction indicated by metal catalysts mainly proceeds through a proton-coupled electron transfer process, making it difficult to obtain a single alcohol product, increasing the cost of subsequent product separation, and thus hindering further application. Furthermore, the reactivity of metal catalysts remains relatively low, resulting in insufficient economic efficiency for the electrocatalytic preparation of alcohols from carbonyl compounds. Therefore, constructing a highly active electrocatalyst for the hydrogenation of carbonyl compounds with single-product selectivity is of great practical significance for this process.

[0003] Several reports on the use of composite metal catalysts for the electrocatalytic hydrogenation of carbonyl compounds have been disclosed in the prior art. Reference 1 (“Electrochemical hydrogenation of biomass-based furfural in aqueous media by Cu catalyst supported on N-doped hierarchically porous carbon”, Appl. Catal., B 2022, 305, 121062) discloses a composite catalyst of nitrogen-doped porous carbon nanosheets supported on cuprous oxide particles, which exhibits a 95% furfuryl alcohol Faradaic efficiency at a potential of -0.25 V (relative to the reversible hydrogen electrode). However, because the catalyst material is a single metallic copper, it lacks additional active sites, resulting in low intrinsic activity for the electrocatalytic hydrogenation of furfural to furfuryl alcohol, with a current density of only about 20 mA / cm² at -0.25 V. 2Reference 2 (“Selective furfural conversion via parallel hydrogenation–oxidation on MOF-derived CuO / RuO2 / Celectrocatalysts via pulsed laser”, Appl. Catal., B 2023, 339, 123164) discloses a metal-organic framework-derived carbon-supported CuO / RuO2 heterointerface catalyst that exhibits high activity for the electrocatalytic hydrogenation of furfural in an alkaline electrolyte, with a reduction current density exceeding 70 mA / cm² at -0.40 V. 2 However, due to the difficulty in providing sufficient adsorbed active hydrogen sites, it is difficult to obtain the single product furfuryl alcohol, which makes subsequent product separation difficult. It can be seen that although the known supported metal composite catalysts in the prior art can achieve high furfuryl alcohol Faradaic efficiencies, the intrinsic activity of the catalyst and the ability to obtain a single product are the limiting factors for the large-scale industrialization and commercialization of such catalysts.

[0004] Based on this, from the perspective of catalyst structure design and cost, it is of great practical significance to prepare a catalyst that is simple to synthesize, low in cost, and highly active for the electrocatalytic hydrogenation of carbonyl compounds to prepare alcohol products. Summary of the Invention

[0005] To address the shortcomings of existing catalysts for the hydrogenation of carbonyl compounds to alcohols, such as poor catalytic activity and / or selectivity, or complex catalyst preparation processes, this invention provides a method for preparing an electrocatalyst for the hydrogenation of carbonyl compounds to alcohols. Specifically, the catalyst provided by this invention is an amorphous cerium oxide-supported metal cluster composite material, which can be used for the electrocatalytic hydrogenation of carbonyl compounds to alcohols, exhibiting excellent catalytic performance, with superior electrochemical activity and stability. This invention utilizes a simple synthesis method, eliminating the need for complex electrochemical regulation and transformation of morphology. Compared to other methods for preparing metal particle catalysts, it eliminates the need for complex precursor design and control, resulting in a simpler, lower-cost, and more convenient process. This invention provides the following technical solutions to address the aforementioned technical problems.

[0006] A method for preparing an electrocatalyst for the hydrogenation of carbonyl compounds to alcohols includes the following steps:

[0007] (S1) The condensation reaction of o-vanillin and diamine yields the condensation product, which is used as an organic ligand.

[0008] (S2) Cerium salts and organic ligands are used to prepare cerium complexes, which are then heat-treated in an inert atmosphere to obtain amorphous cerium oxide-carbon composite materials.

[0009] (S3) The amorphous cerium oxide-carbon composite material is dispersed in a weakly alkaline solution, and a copper salt solution is added dropwise while stirring. The mixture is washed, dried, and then heat-treated under an inert atmosphere and cooled to obtain the catalyst.

[0010] Further, in step (S1), the molar ratio of o-vanillin to diamine is 1-2:1, preferably 1.5-2:1; even further, the diamine is selected from at least one of 2,2-dimethyl-1,3-propanediamine, 1,3-propanediamine, 1,4-butanediamine, and 1,5-diaminopentane.

[0011] Furthermore, in step (S1), the reaction conditions are 70-90℃ for 6-10 hours, and the reaction medium is an alcohol, such as methanol, ethanol, or isopropanol. After the reaction is completed, the alcohol solvent is evaporated, and the resulting polycondensation product is used for subsequent organic ligands.

[0012] The inventors unexpectedly discovered that using the condensation product of o-vanillin and diamine as an organic ligand can result in a highly dispersed distribution of cerium in the amorphous cerium oxide-carbon composite material obtained after the pyrolysis of the cerium complex, making it easier to form extremely rich oxygen vacancies. This is likely because the organic ligand obtained from the condensation of o-vanillin and diamine possesses a unique metal-O4 chelate coordination cavity, which can form a Ce-O4 coordination structure with cerium ions. Furthermore, the organic ligand decomposes into carbon after pyrolysis; therefore, compared to a single cerium oxide support, this amorphous cerium oxide-carbon composite material exhibits excellent electrical conductivity, making it suitable for electrocatalytic reactions.

[0013] Further, in step (S2), the cerium salt is selected from at least one of cerium nitrate, cerium chloride, and their hydrates; the ratio of cerium salt to condensation product, calculated as Ce, is 1 mmol: 0.3-0.5 g. The preparation conditions for the cerium complex are as follows: the organic ligand is dissolved in an alcohol (at least one of methanol, ethanol, and isopropanol), added dropwise to the alcoholic solution of the cerium salt, stirred at 50-70°C for 6-10 h, cooled, washed, and dried to obtain the cerium complex. Even further, the concentration of the organic ligand alcoholic solution is 2-5 wt%, and the concentration of the cerium salt alcoholic solution is 0.5-1 mmol / mL.

[0014] Further, in step (S2), the inert atmosphere is nitrogen or argon, preferably nitrogen; the heat treatment temperature is 500-700℃, preferably 550-600℃; the heat treatment heating rate is 10-20℃ / min; and the heat treatment time is 0.5-2h, preferably 1-1.5h.

[0015] Further, in step (S3), the weak alkaline solution has a pH of 9-10 and is selected from sodium hydroxide solution, potassium hydroxide solution, and potassium carbonate solution, preferably sodium hydroxide solution; the concentration of the alkaline solution can be 0.1-1.0 mM, preferably 0.4-0.6 mM. The ratio of amorphous cerium oxide-carbon composite material to the weak alkaline solution is 1 g: 100-200 mL.

[0016] Further, in step (S3), the copper salt is selected from at least one of copper nitrate and copper chloride; the concentration of the metallic copper salt is 4-20 mg / mL, preferably 8-12 mg / mL; the mass ratio of the amorphous cerium oxide-carbon composite material to the copper salt is 4-6:1-2, preferably 2-3:1.

[0017] Further, in step (S3), the stirring time is 10-14h; the inert atmosphere is nitrogen or argon, preferably argon; the heat treatment temperature is 300-600℃, preferably 400-500℃; and the heat treatment time is 0.5-2h, preferably 1-1.5h.

[0018] This invention also provides an electrocatalyst prepared by the above-described method. Further, the electrocatalyst is an amorphous cerium oxide-supported metal cluster composite material, wherein metallic Cu is supported in cluster form on an amorphous cerium oxide-carbon composite support, the atomic ratio of carbon to cerium is 30:1 to 40:1, the cerium oxide is highly amorphous, and the oxygen vacancy concentration is 2 × 10⁻⁶. 17 ~2×10 18 / g, with a Cu loading content of 1.6-2.2wt%.

[0019] The XPS spectrum of the obtained catalyst shows the 2p of Cu. 3 / 2 The orbital binding energy position is located at 932.7 ± 0.2 eV, and the corresponding 1s orbital binding energy position of O is located at 531.1 ± 0.1 eV; preferably, the 2p orbital binding energy of Cu in its XPS spectrum is... 3 / 2 The orbital binding energy is located at 932.7 ± 0.1 eV, and the corresponding 1s orbital binding energy of O is located at 531.1 ± 0.05 eV.

[0020] Due to the electron transfer interaction between the cerium oxide support and the metal, the XPS spectrum of the copper clusters provided in this invention, loaded onto the amorphous cerium oxide support, will shift to a certain extent. Therefore, the position of the characteristic peaks in the XPS spectrum can be used to determine this shift. Specifically, the binding energy of the 2p orbitals of Cu in the XPS shifts by 0.4 eV towards higher binding energies, proving that an electron transfer process from Cu to the amorphous cerium oxide support has occurred in the composite material.

[0021] The present invention also provides the use of the electrocatalyst prepared by the above preparation method in the hydrogenation reaction of carbonyl compounds to prepare alcohols.

[0022] Furthermore, the hydrogenation of the carbonyl compound to prepare alcohols includes the electrocatalytic hydrogenation of furfural to prepare furfuryl alcohol, the electrocatalytic hydrogenation of 5-methylfurfural to prepare 5-methyl-2-furanethanol, the electrocatalytic hydrogenation of 3-furancarbaldehyde to prepare 3-furanethanol, the electrocatalytic hydrogenation of 2-acetylfuran to prepare 1-(2-furanyl)ethanol, the electrocatalytic hydrogenation of benzaldehyde to prepare benzyl alcohol, and the electrocatalytic hydrogenation of cyclohexanone to prepare cyclohexanol.

[0023] This invention provides an amorphous cerium oxide-carbon composite support for supporting metal cluster catalysts and its preparation method for the electrocatalytic hydrogenation of carbonyl compounds to alcohols. The amorphous cerium oxide-carbon composite support is obtained by pyrolysis of a complex of cerium ions and the polycondensation product of o-vanillin and a diamine. The polycondensation ligand possesses a unique metal-O4 chelate coordination cavity, which can form a Ce-O4 coordination structure with cerium ions. This results in a highly dispersed distribution of cerium in the amorphous cerium oxide-carbon composite material after pyrolysis, making it easier to form abundant oxygen vacancies. Benefiting from the oxygen vacancy effect of the amorphous cerium oxide support and the strong metal-support interaction, the metal clusters are strongly bound to the support, and the structure described in this invention remains unchanged under reducing conditions. The method for supporting amorphous cerium oxide provided by this invention is simple and reproducible, with significant reference value and broad application prospects. The amorphous cerium oxide-supported metal cluster composite material provided by this invention exhibits excellent catalytic activity and stability for the electrocatalytic hydrogenation of carbonyl compounds to corresponding alcohols, demonstrating significant industrial advantages.

[0024] The present invention also provides an amorphous cerium oxide-supported metal cluster composite catalyst for the hydrogenation of carbonyl compounds to alcohols. It has high catalytic activity, good substrate versatility, and high Faraday efficiency for the conversion of carbonyl compounds to alcohols, and has obvious advantages for industrialization.

[0025] Compared with other existing technologies, the present invention has the following advantages:

[0026] 1. The present invention provides an amorphous cerium oxide-supported metal cluster composite material prepared based on the interaction between the amorphous support and the metal cluster. Compared with other methods, this method is simple to prepare, low in cost, and significantly improves the effect, making it suitable for practical applications. The catalyst has excellent reactivity and substrate universality in the hydrogenation of carbonyl compounds to prepare corresponding alcohols.

[0027] 2. The raw materials used in this invention are inexpensive and the rare earth metal cerium is abundant. At the same time, the catalyst preparation method is simple, the impregnation adsorption reaction and the tubular furnace pyrolysis process are easy to operate, highly operable, have a large output, strong versatility, and low industrial production cost, which can be carried out on a large scale.

[0028] 3. The present invention uses the condensation product of o-vanillin and diamine as an organic ligand. This organic ligand has a unique metal-O4 chelate coordination cavity, which can form a Ce-O4 coordination structure with cerium ions. This results in a highly dispersed distribution of cerium in the amorphous cerium oxide-carbon composite material obtained after the pyrolysis of the cerium complex, making it easier to form extremely rich oxygen vacancies.

[0029] 4. The amorphous cerium oxide support used in this invention can interact with the metal clusters supported thereon through electron transfer, which greatly increases the reduction current density of the carbonyl compound electrocatalytic hydrogenation to alcohol by the resulting composite catalyst. Attached Figure Description

[0030] Figure 1 The X-ray powder diffraction patterns of the highly efficient and stable amorphous cerium oxide-supported copper cluster composite material prepared in Example 1 of the present invention and Comparative Example 1 are shown.

[0031] Figure 2 (a) is a transmission electron microscope image of the highly efficient and stable amorphous cerium oxide-supported copper cluster composite material prepared in Example 1 of the present invention. Figure 2 (b) is a transmission electron microscope image of Comparative Example 1.

[0032] Figure 3 The energy spectrum of each element is shown for the highly efficient and stable amorphous cerium oxide-supported copper cluster composite material prepared in Example 1 of this invention.

[0033] Figure 4 The electron paramagnetic resonance spectra of the highly efficient and stable amorphous cerium oxide-supported copper cluster composite material prepared in Example 1 of the present invention and Comparative Example 1 are shown.

[0034] Figure 5 The efficient and stable amorphous cerium oxide-supported copper cluster composite material prepared in Example 1 of this invention and the XPS energy dispersive spectroscopy of Comparative Example 1 are shown below. Figure 5 (a) is the 2p orbital pattern of Cu. Figure 5 (b) is the 1s orbital spectrum of O.

[0035] Figure 6 The X-ray absorption structure spectra of the highly efficient and stable amorphous cerium oxide-supported copper cluster composite material prepared in Example 1 of this invention and Comparative Example 1 are shown. Figure 6 (a) is the X-ray absorption near-edge structure spectrum of Cu. Figure 6 (b) is the extended X-ray absorption fine structure spectrum of Cu.

[0036] Figure 7 The figures show the high-efficiency and stable amorphous cerium oxide-supported copper cluster composite material prepared in Example 1 of this invention and the experimental performance curves of furfural electrocatalytic hydrogenation in Comparative Example 1, wherein... Figure 7(a) Polarization curves in 1M potassium hydroxide electrolyte and 1M potassium hydroxide and 0.05M furfural mixed electrolyte. Figure 7 (b) represents the Faraday efficiency and selectivity of the product furfuryl alcohol.

[0037] Figure 8 This is a substrate universality experiment for the amorphous cerium oxide-supported copper cluster composite material prepared in Example 1 of the present invention. Detailed Implementation

[0038] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0039] Unless otherwise specified, the methods described in the following embodiments are conventional methods.

[0040] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0041] Example 1

[0042] (S1) Dissolve 4.053 g of o-vanillin (0.0266 mol) in 100 mL of ethanol, stir until homogeneous, and sonicate for 1 hour. Then dissolve 1.474 g of 2,2-dimethyl-1,3-propanediamine (0.014 mol) in 30 mL of ethanol and add it dropwise to the o-vanillin ethanol solution while stirring. Reflux and stir at 90 °C for 6 hours. Remove the ethanol solvent under vacuum and dry under vacuum at 60 °C for 6 hours to obtain the organic ligand. The ligand has the molecular formula C. 21 H 26 O4N2 has a molecular weight of 370.4 g / mol.

[0043] (S2) Dissolve 2.054 g of the above organic ligand in 100 mL of ethanol and sonicate for half an hour. Then, dissolve 2.605 g of cerium nitrate hexahydrate (6 mmol) in 10 mL of ethanol and add it dropwise to the ethanol solution of the organic ligand while stirring. Reflux and stir at 60 °C for 6 hours, cool to room temperature, centrifuge, and wash three times with 50 mL of ethanol each time. Dry under vacuum at 60 °C for 6 hours to obtain the cerium complex. Place the cerium complex in a tube furnace under nitrogen protection and heat to 600 °C at a heating rate of 10 °C / min. Pyrolyze for 1 hour, cool to room temperature, and remove the sample. The obtained material is an amorphous cerium oxide-carbon composite support. In the synthesis of this product, the optimal pyrolysis temperature is the key to obtaining amorphous cerium oxide.

[0044] (S3) Take 50 mg of amorphous cerium oxide-carbon composite support in a beaker, add 8 mL of 0.6 mM sodium hydroxide solution, sonicate for 30 minutes, then add 2.5 mL of 10 mg / mL copper nitrate solution dropwise while stirring, stir for 12 hours, centrifuge, wash once with ethanol, and dry under vacuum at 50 °C for 1 hour. Place the obtained solid in an argon-protected tube furnace, heat to 500 °C at a heating rate of 10 °C / min, calcine for 1 hour, cool to room temperature, and remove the sample. The obtained material is an amorphous cerium oxide-supported copper cluster composite material.

[0045] Comparative Example 1

[0046] The preparation method was basically the same as in Example 1, except that the pyrolysis temperature of the cerium complex in step S2 was changed from 600℃ to 900℃. The resulting cerium oxide support was highly crystallized, and the cerium oxide lattice fringes could be clearly seen in the transmission electron microscope images. The oxygen vacancy concentration was also extremely low, at 1 ± 0.5 × 10⁻⁶. 15 / g. The obtained crystalline cerium oxide-supported copper composite material was tested in 1M potassium hydroxide electrolyte, and the partial current density of furfuryl alcohol at a potential of -0.5V was 22±2 mA / cm. 2 The furfuryl alcohol Faraday efficiency was 86±1%, and the furfuryl alcohol selectivity was 85.3%. This clearly demonstrates that the degree of crystallinity of the cerium oxide support plays a crucial role in the activity of the supported copper clusters.

[0047] Figure 1 The X-ray powder diffraction curves of the composite materials prepared in Example 1 and Comparative Example 1 are shown. The product of Example 1 has no obvious diffraction peaks, indicating that cerium oxide is in an amorphous state and copper has not undergone obvious agglomeration. The X-ray diffraction curve of the product of Comparative Example 1 corresponds to the standard diffraction card of cerium dioxide, indicating that the cerium oxide support is highly crystallized.

[0048] Figure 2 These are transmission electron microscope images of the composite materials prepared in Example 1 and Comparative Example 1. Figure 2 (a) is a transmission electron microscope image of the highly efficient and stable amorphous cerium oxide-supported copper cluster composite material prepared in Example 1. It can be seen that the cerium oxide exhibits a highly amorphous morphology, with no obvious lattice stripes and no obvious copper aggregation. Figure 2 (b) is a transmission electron microscope image of the highly crystallized cerium oxide-supported copper cluster composite material prepared in Comparative Example 1. The lattice fringes of cerium oxide can be seen, and there is no obvious copper aggregation.

[0049] Figure 3The energy dispersive spectroscopy (EDS) spectra of the composite material prepared in Example 1 show that cerium, oxygen, copper, carbon, and nitrogen are uniformly distributed on the composite catalyst prepared in Example 1. Furthermore, the absence of obvious copper aggregation demonstrates the uniform loading of copper on the amorphous cerium oxide-carbon composite support. The mass loading of Cu is 1.84%.

[0050] Figure 4 The image shows the electron paramagnetic resonance (EPR) spectrum of the composite material prepared in Example 1. It can be seen that the catalyst prepared in Example 1, due to the high amorphization of the cerium oxide support, has abundant oxygen vacancies on the support, with an oxygen vacancy concentration of approximately 1 × 10⁻⁶. 18 / g. In Comparative Example 1, the cerium oxide support was highly crystallized with an extremely low oxygen vacancy concentration of approximately 1 × 10⁻⁶ g. 15 / g.

[0051] Figure 5 The XPS spectrum of the composite material prepared in Example 1 is shown below. Figure 5 (a) is the 2p orbital pattern of Cu. Figure 5 (b) is the 1s orbital spectrum of O. It can be seen that the Cu valence state of the composite material obtained in Example 1 is 0 / +1. Compared with the comparative example, the characteristic peak of Cu shifts to a higher energy direction by 0.4 eV, demonstrating a significant electron transfer effect of Cu to the amorphous cerium oxide support. Meanwhile... Figure 5 (b) It shows that the oxygen vacancy concentration in the amorphous cerium oxide-supported copper cluster composite material prepared in Example 1 is significantly higher than that in the highly crystalline cerium oxide-supported copper cluster composite material prepared in Comparative Example 1.

[0052] Figure 6 The X-ray absorption structure spectra of the composite materials prepared in Example 1 and Comparative Example 1 are shown below. Figure 6 (a) is the X-ray absorption near-edge structure spectrum of Cu. Figure 6 (b) is the extended X-ray absorption fine structure spectrum of Cu. It can be seen that the valence state of the composite material obtained in Example 1 is between 0 and +1. Compared with Comparative Example 1, the valence state of Cu in Example 1 is more biased towards +1, demonstrating a significant electron transfer effect of Cu to the amorphous cerium oxide support. Combined with XRD and XPS, it can be inferred that the loading form of Cu is neither metal particles nor single metal atoms, but rather copper clusters.

[0053] In summary, it can be confirmed that the amorphous cerium oxide-supported copper cluster composite material was successfully prepared in Example 1, and that there is an electron transfer interaction between the Cu clusters and the amorphous cerium oxide support.

[0054] Figure 7 The experimental performance curves for the electrocatalytic hydrogenation of furfural to furfuryl alcohol prepared in Example 1 and Comparative Example 1 are shown below. Figure 7(a) shows the polarization curves in 1M potassium hydroxide electrolyte and 1M potassium hydroxide and 0.05M furfural mixed electrolyte. Figure 7 (b) shows the product Faraday efficiency and selectivity of the composite material of Example 1 as a catalyst for the electrocatalytic hydrogenation of furfural.

[0055] The specific experimental steps are as follows: The amorphous cerium oxide-supported copper cluster composite material (loading of 1 mg / cm³) prepared in Example 1 is used... 2 The sample was loaded onto pre-cut carbon cloth and tested in a flow electrolytic cell in 1M potassium hydroxide electrolyte. The product composition was measured by gas chromatography-mass spectrometry, and the Faraday efficiency and selectivity were calculated. The Faraday efficiency and selectivity of Comparative Example 1 were tested under the same operating conditions.

[0056] In the experiment of preparing furfuryl alcohol by electrocatalytic hydrogenation of furfural using the catalyst prepared in Example 1 above, the partial current density of furfuryl alcohol reached 102 mA / cm² at a potential of -0.5 volts. 2 According to the Faraday efficiency formula: FE = 2nF / Q, where n represents the amount of furfuryl alcohol, F represents the Faraday constant (96485 C / mol), and Q represents the total charge passing through, the calculated Faraday efficiency of furfuryl alcohol is 95%, and the selectivity is 98.2%. In Comparative Example 1, the partial current density of furfuryl alcohol at -0.5 V is 32 mA / cm². 2 The furfuryl alcohol Faraday efficiency was 83%, and the furfuryl alcohol selectivity was 96.3%. This indicates that the efficient and stable amorphous cerium oxide-supported copper cluster composite material prepared in this invention has excellent furfural electrocatalytic hydrogenation activity, and the interaction between the amorphous cerium oxide support and the copper clusters improves the catalyst performance.

[0057] Figure 8 This study investigated the substrate universality of the amorphous cerium oxide-supported copper cluster composite material prepared in Example 1. The specific experimental procedure involved replacing furfural with carbonyl compounds of equal concentration, specifically including 5-methylfurfural, 3-furanaldehyde, 2-acetylfuran, benzaldehyde, and cyclohexanone. The Faraday efficiency and selectivity of the corresponding alcohols in the products were analyzed. Figure 8 It can be seen that the amorphous cerium oxide-supported copper cluster composite catalyst prepared in Example 1 has excellent substrate versatility.

[0058] Example 2

[0059] Prepared using the same method as in Example 1, except that the concentration of the sodium hydroxide solution used in Example 1 was changed from 0.6 mM to 0.2 mM. As a result, the mass loading of copper on the amorphous cerium oxide support decreased to 0.5%. The resulting composite catalyst was then tested in 1 M potassium hydroxide electrolyte, and the partial current density of furfuryl alcohol was 82 mA / cm² at a potential of -0.5 V.2 The furfuryl alcohol Faraday efficiency was 94%, and the furfuryl alcohol selectivity was 98.5%.

[0060] Example 3

[0061] Prepared using the same method as in Example 1, except that the concentration of the sodium hydroxide solution used in Example 1 was changed from 0.6 mM to 1 mM. As a result, the copper supported on the amorphous cerium oxide support exhibited slight agglomeration, with a mass loading of 2.3%. Slight diffraction peaks of metallic copper appeared in the X-ray diffraction pattern. The obtained composite catalyst was tested in a 1 M potassium hydroxide electrolyte, and the partial current density of furfuryl alcohol at a potential of -0.5 V was 88 mA / cm². 2 The furfuryl alcohol Faraday efficiency was 95%, and the furfuryl alcohol selectivity was 97.8%.

[0062] Example 4

[0063] Prepared using the same method as in Example 1, except that the concentration of the copper nitrate solution added in Example 1 was changed from 10 mg / mL to 20 mg / mL. As a result, the copper supported on the amorphous cerium oxide support exhibited slight agglomeration, with a mass loading of 2.6%. Slight diffraction peaks of metallic copper appeared in the X-ray diffraction spectrum. The obtained composite catalyst was tested in 1M potassium hydroxide electrolyte, and the partial current density of furfuryl alcohol at a potential of -0.5 V was 85 mA / cm². 2 The furfuryl alcohol Faraday efficiency was 94%, and the furfuryl alcohol selectivity was 97.6%.

[0064] Example 5

[0065] The cerium oxide support was prepared using the same method as in Example 1, except that the pyrolysis temperature of the cerium complex in step S2 was changed from 600°C to 500°C. As a result, the cerium oxide support remained amorphous, but the oxygen vacancy concentration became 1.2 × 10⁻⁶. 18 / g, the obtained composite catalyst was tested in 1M potassium hydroxide electrolyte, and the partial current density of furfuryl alcohol was 84 mA / cm at a potential of -0.5 volts. 2 The furfuryl alcohol Faraday efficiency was 94%, and the furfuryl alcohol selectivity was 97.6%.

[0066] Example 6

[0067] The cerium oxide support was prepared using the same method as in Example 1, except that the pyrolysis temperature of the cerium complex in step S2 was changed from 600°C to 550°C. The cerium oxide support remained amorphous, but the oxygen vacancy concentration became 1.3 × 10⁻⁶. 18 / g, the obtained composite catalyst was tested in 1M potassium hydroxide electrolyte, and the partial current density of furfuryl alcohol was 60mA / cm at a potential of -0.5V. 2The furfuryl alcohol Faraday efficiency was 91%, and the furfuryl alcohol selectivity was 98.1%.

[0068] Example 7

[0069] The cerium complex was prepared using the same method as in Example 1, except that the pyrolysis temperature of the cerium complex in step S2 was changed from 600°C to 700°C. As a result, a slight diffraction peak of cerium oxide appeared in the X-ray diffraction pattern, and the oxygen vacancy concentration became 9 × 10⁻⁶. 17 / g, the obtained composite catalyst was tested in 1M potassium hydroxide electrolyte, and the partial current density of furfuryl alcohol was 72mA / cm at a potential of -0.5V. 2 The furfuryl alcohol Faraday efficiency was 90%, and the furfuryl alcohol selectivity was 96.7%.

[0070] Comparative Example 2

[0071] The preparation method was basically the same as in Example 1, except that the pyrolysis temperature of the cerium complex in step S2 was changed from 600℃ to 800℃. The resulting cerium oxide support was highly crystallized, and the cerium oxide lattice fringes could be clearly seen in the transmission electron microscope images. The oxygen vacancy concentration was also very low, at 1×10⁻⁶. 16 / g. The obtained crystalline cerium oxide-supported copper composite material was tested in 1M potassium hydroxide electrolyte, and the partial current density of furfuryl alcohol was 29 mA / cm² at a potential of -0.5V. 2 The furfuryl alcohol Faraday efficiency was 87%, and the furfuryl alcohol selectivity was 88.6%. This clearly demonstrates that the degree of crystallinity of the cerium oxide support plays a crucial role in the activity of the supported copper clusters.

[0072] Comparative Example 3

[0073] The preparation method was basically the same as in Example 1, except that step S1 was omitted and in step S2, the organic ligand was replaced with o-vanillin. The obtained crystalline cerium oxide-supported copper composite material was tested in 1M potassium hydroxide electrolyte; the partial current density of furfuryl alcohol at a potential of -0.5V was 48 mA / cm². 2 The furfuryl alcohol Faraday efficiency was 88%, and the furfuryl alcohol selectivity was 92.4%.

[0074] Comparative Example 4

[0075] The preparation method was basically the same as in Example 1, except that step S1 was omitted and the organic ligand in step S2 was replaced with guaiacol. The obtained crystalline cerium oxide-supported copper composite material was tested in 1M potassium hydroxide electrolyte; the partial current density of furfuryl alcohol at a potential of -0.5V was 51 mA / cm². 2 The furfuryl alcohol Faraday efficiency was 85%, and the furfuryl alcohol selectivity was 78.0%.

[0076] The comparison of Examples 1, 3, and 4 shows that the condensation polymer obtained by reacting o-vanillin and diamine in this invention can significantly improve catalyst performance.

Claims

1. A method for producing an electrocatalyst for the hydrogenation of a carbonyl compound to an alcohol compound, characterized by, The method comprises the following steps: (S1) condensation of o-vanillin and diamine to obtain a condensation product as an organic ligand; (S2) preparation of cerium complex from cerium salt and the organic ligand, and heat treatment in an inert atmosphere to obtain amorphous cerium oxide-carbon composite material; (S3) dispersion of the amorphous cerium oxide-carbon composite material in a weak alkaline solution, dropwise addition of a copper salt solution under stirring, washing, drying, and then heat treatment under protection of an inert atmosphere to obtain the electrocatalyst; The electrocatalyst is an amorphous cerium oxide supported metal cluster composite material, wherein metal Cu is supported in the form of clusters on an amorphous cerium oxide-carbon composite carrier, the atomic ratio of carbon to cerium is 30:1-40:1, the cerium oxide is in a highly amorphous state, the oxygen vacancy concentration is 2x10 17 ~2x10 18 / g, and the content of the metal Cu loading is 1.6-2.2 wt%.

2. The production method according to claim 1, characterized by, In step (S1), the molar ratio of o-vanillin to diamine is 1-2:

1.

3. The preparation method according to claim 2, characterized in that, The molar ratio of o-vanillin to diamine is 1.5-2:

1.

4. The method of claim 1, wherein, The diamine is at least one selected from 2,2-dimethyl-1,3-propanediamine, 1,3-propanediamine, 1,4-butanediamine, and 1,5-diaminopentane.

5. The preparation method according to claim 1, characterized in that, In step (S1), the reaction conditions are 70-90℃ for 6-10h, and the reaction medium is alcohol.

6. The method of claim 1, wherein, In step (S2), the cerium salt is at least one selected from cerium nitrate, cerium chloride, and their hydrates; and the ratio of cerium salt (calculated as Ce) to condensation product is 1mmol:0.3-0.5g.

7. The production method according to claim 6, characterized by, The preparation conditions of the cerium complex are dissolving the organic ligand in alcohol, dropwise addition to the alcohol solution of the cerium salt, stirring at 50-70℃ for 6-10h, cooling, washing, and drying to obtain the cerium complex.

8. The preparation method according to claim 6, characterized in that, The concentration of the alcohol solution of the organic ligand is 2-5wt%, and the concentration of the alcohol solution of the cerium salt is 0.5-1mmol / mL.

9. The method of claim 1, wherein, In step (S2), the inert atmosphere is nitrogen or argon; the heat treatment temperature is 500-700℃; the heat treatment temperature rising rate is 10-20℃ / min; and the heat treatment time is 0.5-2h.

10. The method of claim 1, wherein, In step (S3), the weak alkaline solution has a pH of 9-10 and is selected from sodium hydroxide solution, potassium hydroxide solution, and potassium carbonate solution; the concentration of the weak alkaline solution is 0.1-1.0mM; and the ratio of the amorphous cerium oxide-carbon composite material to the weak alkaline solution is 1g:100-200mL.

11. The method of claim 10, wherein, The concentration of the weak alkaline solution is 0.4-0.6mM.

12. The method of claim 1, wherein, In step (S3), the copper salt is at least one selected from copper nitrate and copper chloride; the concentration of the copper salt is 4-20mg / mL; the mass ratio of the amorphous cerium oxide-carbon composite material to the copper salt is 4-6:1-2; the stirring time is 10-14h; the inert atmosphere is nitrogen or argon; the heat treatment temperature is 300-600℃; and the heat treatment time is 0.5-2h.

13. The method of claim 12, wherein, In step (S3), the concentration of the copper salt is 8-12mg / mL; the mass ratio of the amorphous cerium oxide-carbon composite material to the copper salt is 2-3:1; the heat treatment temperature is 400-500℃; and the heat treatment time is 1-1.5h.

14. Use of the electrocatalyst prepared by the method of any one of claims 1-13 in a reaction of hydrogenation of a carbonyl compound to prepare an alcohol.

15. Use according to claim 14, wherein the hydrogenation of a carbonyl compound to an alcohol is the electrocatalytic hydrogenation of furfural to furfuryl alcohol, 5-methylfurfural to 5-methyl-2-furanmethanol, 3-furan carboxaldehyde to 3-furanmethanol, 2-acetylfuran to 1-(2-furyl)ethanol, benzaldehyde to benzyl alcohol or cyclohexanone to cyclohexanol.

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