Method for reforming ethylene glycol to hydrogen coupled with formic acid production by using a nickel, copper, cobalt ternary metal catalyst at an industrial current density

Abstract

A method for reforming ethylene glycol to formic acid coupled hydrogen production by using a nickel, copper and cobalt ternary metal catalyst at an industrial current density. The method uses an H-shaped electrolytic cell, separates the cathode and anode by an anion membrane, uses a platinum mesh electrode as the cathode, and uses a material with NiCuCoO4 loaded on a nickel foam substrate as the anode. By applying a constant voltage electrolysis, hydrogen can be efficiently produced at the cathode, and formic acid can be electrolytically synthesized at the anode. The method can be carried out at room temperature and normal pressure, the conditions are mild, the material cost is low, the synthesis process is easy to operate and suitable for large-area production, and the method shows excellent industrial application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for coupling hydrogen production by oxidation of ethylene glycol at an industrial current density using a nickel, copper, cobalt ternary catalyst. BACKGROUND

[0002] The development of the plastic industry provides sufficient impetus for the high-quality development of China's economy. Polyethylene terephthalate (PET) plastic is one of the most widely used plastics in the world. Its excellent physical, chemical, optical and other properties and excellent processability make it widely used in food, medical, home appliance and other industries. However, the plastic recycling system in China still needs to be improved. According to the statistics of the National Bureau of Statistics, in 2022, the total output of plastic products in China was 69.01 million tons. According to the statistics of the China Resources Recycling Association, in 2022, China produced 63 million tons of waste plastics, of which only 18.9 million tons were recycled, accounting for 30%. Because the degradation rate of PET plastic in nature is extremely low, improper disposal methods have caused serious damage to the natural environment, such as visual pollution, land resource encroachment, air pollution, etc. It is worth noting that under alkaline conditions, PET can be hydrolyzed to generate its monomers, i.e. terephthalic acid and ethylene glycol. At present, the application of terephthalic acid is relatively concentrated, about 90% is used to produce PET. Acidification treatment of PET alkaline hydrolysis liquid can obtain terephthalic acid precipitation, which can be reused as raw material to produce PET, thereby saving industrial costs to a certain extent. Formic acid is a basic organic chemical raw material, which can be directly used for fabric processing, textile printing and dyeing, and industrial solvent. At present, formic acid is mainly synthesized by the reaction of carbon monoxide and sodium hydroxide, i.e. sodium formate is generated by the reaction of carbon monoxide and sodium hydroxide, and then formic acid is obtained by acidification with sulfuric acid. However, this method uses a large amount of chemicals, and the synthesis raw materials are all dangerous chemicals, which puts high requirements on the safety measures during production, thereby indirectly increasing the production cost.

[0003] With the rapid development of renewable power generation technology, electrochemical synthesis is receiving more and more attention. At present, there have been many reports on the synthesis of high-value industrial raw materials (such as formic acid, glycolic acid, 2,5-furan dicarboxylic acid, etc.) by electrochemical oxidation of small organic molecules (such as methanol, ethylene glycol, 5-hydroxymethyl furfural, etc.). Formic acid is one of the main products of the electro-oxidation of ethylene glycol (EG). Therefore, the synthesis of formic acid by electrocatalytic oxidation of EG in the hydrolysis liquid of waste PET plastic is a more green and economical synthesis technology. However, in order to pursue higher catalytic performance and substrate conversion rate, most of the reported catalysts contain noble metals such as Au, Ag and Pd, which greatly increases the production cost and cannot be applied to large-scale application in practice.

[0004] In the electrochemical organic oxidation system under alkaline conditions, the main factor affecting the performance of the catalyst is the concentration of organic matter and hydroxyl ions (OH - ), so enhancing the adsorption of the two is beneficial to improve the electrocatalytic performance of the catalyst. Cobalt-based spinel oxide (Co3O4) is an electrocatalyst containing multiple reaction sites (Co 3+ (Oh), Co 2+ (Td), Co 2+ (Oh)). Liu et al. took the oxygen evolution reaction (OER) as an example, and synthesized MgCo2O4, CoCr2O4, Co2TiO4 catalysts based on Co3O4 by doping in turn, and screened the above sites in turn, to explore the role of each site. The results showed that *OH is more inclined to occur oxidation reaction to generate *OOH at Co 3+ (Oh) site, and the presence of Co 2+ (Td) further increases the number of *OOH. In addition, the activation energy required for *OH to be oxidized to *O at Co 3+ (Oh) site is the lowest, thus conducive to the occurrence of oxidation reaction (Liu Z, Wang G, Zhu X, et al. Optimal geometrical configuration of cobalt cations in spinel oxides to promote oxygen evolution reaction [J]. Angewandte Chemie, 2020, 132(12): 4766-4772.). In addition, it is reported that in the process of organic electro-oxidation, Co 2+ (Td) is a Lewis acid site responsible for the adsorption of OH - , and Co 3+ (Oh) is a Brønsted acid site responsible for the adsorption and oxidation of organic matter. By modifying the above sites with heteroatoms, the position of the d-conduction band of the catalyst, as well as the electronic orbital distribution, etc. can be changed, thus changing the adsorption capacity of the catalyst for different substances (Ma J, Wang X, Song J, et al. Synergistic Lewis and Brønsted acid sites in cobalt-based spinel oxides for efficient electrocatalytic oxidation of organic compounds [J]. Nature Communications, 2018, 9(1): 1-10.). Acid Sites Promote OH*Formation and Enhance Formate Selectivity: Towards High-efficiency Glycerol Valorization[J]. Angewandte Chemie International Edition, 2024, 63(14): e202319153.; J. Ma, X. Wang, J. Song, Y. Tang, T. Sun, L. Liu, J. Wang, J. Wang, M. Yang, Angew. Chem. Int. Ed. 2024, 63, e202319153.; Lu Y, Dong C L, Huang Y C, et al. Identifying the geometric site dependence of spinel oxides for the electrooxidation of 5-hydroxymethylfurfural[J]. Angewandte Chemie International Edition, 2020, 59(43): 19215-19221.). Due to the controllable electronic structure and rich reaction sites, this kind of catalyst stands out among non-noble metal catalysts.

[0005] Although there are currently reports on the modification of intrinsic Co3O4 catalysts, the performance of the modified catalysts has not been significantly enhanced, and there is still a certain gap from the requirements of actual industrial application. SUMMARY

[0006] The application discloses a method for reforming ethylene glycol into formic acid and coupling hydrogen production under industrial current density by using a nickel-copper-cobalt ternary metal catalyst. The method uses an H-shaped electrolytic cell, separates the anode and cathode by an anion membrane, uses a platinum mesh electrode as the cathode, uses a nickel-copper-cobalt ternary metal material (NiCuCoO4 / NF) loaded on a nickel foam substrate as the anode, and can efficiently produce hydrogen at the cathode and electrolytically synthesize formic acid and glyoxal at the anode by applying a constant voltage. The method can be carried out at room temperature and normal pressure, has mild conditions, low material cost, strong operability in the synthesis process, and is suitable for large-area production, and has excellent industrial application prospect.

[0007] Specifically, the application provides a method for reforming ethylene glycol into formic acid and coupling hydrogen production under industrial current density by using a nickel-copper-cobalt ternary metal catalyst, and the method is as follows:

[0008] The electrolytic cell containing an anion exchange membrane is used, the platinum mesh electrode is used as the cathode, the NiCuCoO4 / NF is used as the anode, the potassium hydroxide (KOH) solution is added in the cathode reaction chamber as the cathode electrolyte, the KOH solution containing EG is added in the anode reaction chamber as the anode electrolyte, the anode electrolyte in the anode reaction chamber is subjected to the coupling electrolysis reaction under the conditions of stirring and room temperature, the only product formic acid is obtained in the anode reaction chamber, and the product hydrogen is obtained in the cathode reaction chamber; wherein the anode is prepared by the following method:

[0009] (1) cleaning the foam nickel substrate;

[0010] (2) preparing a solution containing cobalt nitrate (Co(NO3)2), nickel nitrate (Ni(NO3)2) and copper nitrate (Cu(NO3)2);

[0011] (3) assembling a single-chamber electrolysis cell system containing the foam nickel obtained in the step (1) as a working electrode, the platinum mesh electrode as a counter electrode, the Ag|AgCl electrode as a reference electrode, and the solution obtained in the step (2) as an electrolyte;

[0012] (4) connecting the electrochemical workstation, and applying a constant current to the working electrode for a certain time;

[0013] (5) taking out the material, and sending the material to a muffle furnace for heating and oxidation to obtain the anode.

[0014] Further, the platinum mesh electrode is used as the cathode, and the KOH solution with a concentration of 1M is added in the cathode reaction chamber.

[0015] Further, in the anode electrolyte, the EG concentration is 0.1-0.3M, and the KOH concentration is 1M.

[0016] Further, the concentration of the electrolyte is 20-40mM.

[0017] Further, the constant current is 10-20mA, and the power-on time is 5-15min.

[0018] Further, the material is taken out and cleaned with deionized water.

[0019] Further, the oxidation temperature of the material is 300-400℃, and the heating time is 150-200min.

[0020] Further, the EG is oxidized at a potential of 1.4-1.8V vs.RHE.

[0021] The application provides a high-efficiency ethylene glycol electro-oxidation method for preparing formic acid on a NiCuCoO4 / NF. 3+ and Cu 2+The Bronsted acid sites (Co 3+ (Oh)) and Lewis acid sites (Co 2+ (Td)) is modified and regulated to enhance the adsorption capacity of EG and hydroxyl groups in the electrolyte, thereby greatly improving the oxidation efficiency of the catalyst on EG and meeting the requirements of industrial application in the 21st century. The second invention point is that compared with the simple water electrolysis hydrogen production process, the addition of EG accelerates the electron transfer rate at the anode end, thereby improving the hydrogen production efficiency at the cathode end. The method of the present invention can be carried out at room temperature and normal pressure, with mild conditions, low material cost, strong operability of the synthesis process and suitable for large-scale production, showing excellent industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 XRD pattern of NiCuCoO4 / NF

[0023] Figure 2 (a)Ni (b)Cu (c)Co XPS images of NiCuCoO4 / NF before and after reaction

[0024] Figure 3 SEM image of NiCuCoO4 / NF

[0025] Figure 4 (a) Oxygen evolution performance and (b) EGOR performance of NiCuCoO4 / NF, NiCo2O4 / NF, CuCo2O4 / NF, and Co3O4 / NF in 1 M KOH electrolyte (85% iR compensation)

[0026] Figure 5 NMR spectrum of the electrolyte after oxidation with NiCuCoO4 / NF

[0027] Figure 6 Efficiency and yield of formic acid produced by EGOR with NiCuCoO4 / NF at different potentials

[0028] Figure 7 EGOR stability test of NiCuCoO4 / NF at 1.6V vs.RHE

[0029] Figure 8 Current density of EGOR of NiCuCoO4 / NF, NiCo2O4 / NF, CuCo2O4 / NF, and Co3O4 / NF in (a) KOH and (b) EG at different concentrations at 1.4 V vs. RHE. Example

[0030] The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples within the scope of the present invention.

[0031] Example 1

[0032] (1) NiCuCoO4 / NF

[0033] The nickel foam was treated with acetone for 15 minutes to remove surface oil; further, treated with ethanol for 15 minutes to remove residual acetone on the surface of the material; further, treated with 3M hydrochloric acid for 15 minutes to remove metal oxides on the surface of the material; further, treated with ethanol multiple times until the solution was clear and colorless; further, vacuum dried for 40 minutes; further, a solution containing cobalt nitrate (Co(NO3)2), nickel nitrate (Ni(NO3)2), and copper nitrate (Cu(NO3)2) was prepared, with concentrations of 12 mM, 12 mM, and 6 mM, respectively; further, the nickel foam cut into 1 x 2 cm was used as the working electrode, the platinum mesh electrode was used as the counter electrode, and the Ag|AgCl electrode was used as the reference electrode, and the above prepared solution was used as the electrolyte to assemble a single-chamber electrolytic cell system, and the working electrode area immersed in the electrolyte was 1 x 1 cm; further, after connecting the electrochemical workstation, a constant current of 13 mA was applied to the working electrode, and the power-on time was 600 s, after which the material was taken out and rinsed with deionized water; further, the material was sent to a muffle furnace and oxidized at 400°C in an air atmosphere for 180 min, with a heating rate of 1°C / min, to obtain NiCuCoO4 / NF.

[0034] Comparative Example 1

[0035] (2) NiCo2O4 / NF

[0036] The nickel foam was treated with acetone for 15 minutes to remove surface oil; further, treated with ethanol for 15 minutes to remove residual acetone on the surface of the material; further, treated with 3M hydrochloric acid for 15 minutes to remove metal oxides on the surface of the material; further, treated with ethanol multiple times until the solution was clear and colorless; further, vacuum dried for 40 minutes; further, a solution containing cobalt nitrate (Co(NO3)2) and nickel nitrate (Ni(NO3)2) was prepared, with concentrations of 15 mM and 15 mM, respectively; further, the nickel foam cut into 1 x 2 cm was used as the working electrode, the platinum mesh electrode was used as the counter electrode, and the Ag|AgCl electrode was used as the reference electrode, and the above prepared solution was used as the electrolyte to assemble a single-chamber electrolytic cell system, and the working electrode area immersed in the electrolyte was 1 x 1 cm; further, after connecting the electrochemical workstation, a constant current of 13 mA was applied to the working electrode, and the power-on time was 600 s, after which the material was taken out and rinsed with deionized water; further, the material was sent to a muffle furnace and oxidized at 400°C in an air atmosphere for 180 min, with a heating rate of 1°C / min, to obtain NiCo2O4 / NF.

[0037] Comparative Example 2

[0038] (3)CuCo2O4 / NF

[0039] The nickel foam was ultrasonically treated with acetone for 15 minutes to remove the surface oil; further, the nickel foam was ultrasonically treated with ethanol for 15 minutes to remove the residual acetone on the surface of the material; further, the nickel foam was ultrasonically treated with 3M hydrochloric acid for 15 minutes to remove the metal oxide on the surface of the material; further, the nickel foam was ultrasonically treated with ethanol for multiple times until the solution was clear and colorless; further, the nickel foam was vacuum dried for 40 minutes; further, a solution containing cobalt nitrate (Co(NO3)2) and copper nitrate (Cu(NO3)2) was prepared, with the concentrations of the two being 20mM and 10mM respectively; further, the nickel foam was cut into 1×2cm sizes. Nickel was used as the working electrode, a platinum mesh electrode was used as the counter electrode, and an Ag|AgCl electrode was used as the reference electrode. The prepared solution was used as the electrolyte, and a single-chamber electrolytic cell system was assembled, and the area of ​​the working electrode immersed in the electrolyte was ensured to be 1×1 cm. Furthermore, after connecting to an electrochemical workstation, a constant current of 13 mA was applied to the working electrode for 600 s, after which the material was removed and rinsed with deionized water. Furthermore, the material was sent to a muffle furnace and oxidized at 400°C in an air atmosphere for 180 min, with a heating rate of 1°C / min, to obtain CuCo2O4 / NF.

[0040] Comparative Example 3

[0041] (4)Co3O4 / NF

[0042] The nickel foam was ultrasonically treated with acetone for 15 minutes to remove the oil on the surface; further, the nickel foam was ultrasonically treated with ethanol for 15 minutes to remove the residual acetone on the surface of the material; further, the metal oxide on the surface of the material was ultrasonically treated with 3M hydrochloric acid for 15 minutes; further, the nickel foam was ultrasonically treated with ethanol for multiple times until the solution was clear and colorless; further, the solution was vacuum dried for 40 minutes; further, a solution containing cobalt nitrate (Co(NO3)2) was prepared with a concentration of 30mM; further, the nickel foam cut into 1×2cm size was used as the working electrode, and the platinum mesh was used as the electrode. The electrode was used as the counter electrode, the Ag|AgCl electrode was used as the reference electrode, and the prepared solution was used as the electrolyte. A single-chamber electrolytic cell system was assembled, and the area of ​​the working electrode immersed in the electrolyte was ensured to be 1×1 cm. Furthermore, after connecting to the electrochemical workstation, a constant current of 13 mA was applied to the working electrode for 600 s. After that, the material was taken out and rinsed with deionized water. Furthermore, the material was sent to a muffle furnace and oxidized at 400°C for 180 min in an air atmosphere with a heating rate of 1°C / min to obtain Co3O4 / NF.

[0043] Experiments and data

[0044] 1. Catalyst performance test

[0045] A three-electrode H-type electrolytic cell was built, and the anion exchange membrane was used to separate the two chambers. NiCuCoO4 / NF was used as the working electrode, platinum mesh electrode as the counter electrode, and Hg|HgO electrode as the reference electrode. The electrolyte used for testing was 1M KOH, and the instrument used was Chenhua 660E electrochemical workstation. The specific test conditions were as follows:

[0046] Test method: LSV-Linear Sweep Voltammetry;

[0047] Scan rate: 0.005V / s

[0048] Steady voltage time: 2s

[0049] Sensitivity: 1.e -001 A / V

[0050] Each of the two chambers was filled with 10mL 1M KOH, and during testing, the catalyst was immersed in the liquid surface part with a size of 0.5x1cm to minimize the impact of the resistance of each part on the actual performance of the catalyst during testing. After testing the water electrolysis oxygen evolution performance, 0.3M ethylene glycol was added to the anode end, and then the same method was used for testing to obtain the performance of the catalyst ethylene glycol oxidation (EGOR).

[0051] 2. Ethylene glycol oxidation product test

[0052] A three-electrode H-type electrolytic cell was built, and the anion exchange membrane was used to separate the two chambers. NiCuCoO4 / NF was used as the working electrode, platinum mesh electrode as the counter electrode, and Hg|HgO electrode as the reference electrode. The electrolyte used for testing was 1M KOH, and the instrument used was Chenhua 660E electrochemical workstation. The specific test conditions were as follows:

[0053] Test method: i-t-Amperometric i-t Curve;

[0054] Running time: 2h

[0055] Steady voltage time: 2s

[0056] Sensitivity: 1.e -001 A / V

[0057] Each of the two chambers was filled with 10mL 1M KOH, and in addition, 0.186g of ethylene glycol was added to the anode end to make the concentration 0.3M. During testing, the catalyst was immersed in the liquid surface part with a size of 0.5x1cm.

[0058] Take 80 μL of the above-mentioned reaction electrolyte, add 20 μL of 2M sulfuric acid solution and 900 μL of deionized water for neutralization and dilution. Use Shimazu LC-40D high performance liquid chromatograph as an analyzer, with a standard automatic sampler, a variable wavelength scanning ultraviolet detector. The detection chromatographic conditions for organic acids are as follows:

[0059] Chromatographic column: Angilent Hi-Plex H, 8 μm, 7.7 x 300 mm;

[0060] Mobile phase: 5 mM sulfuric acid;

[0061] Flow rate: 0.6 ml / min

[0062] Column temperature: 50°C

[0063] Injection volume: 10 μL

[0064] Detection wavelength: 210 nm.

[0065] 3. Ethylene glycol oxidation stability test

[0066] A three-electrode H-type electrolysis cell was built, and the anion exchange membrane was used to separate the two chambers. NiCuCoO4 / NF was used as the working electrode, platinum mesh electrode as the counter electrode, and Hg|HgO electrode as the reference electrode. The electrolyte used for testing was 1M KOH, and the instrument used was Chenhua 660E electrochemical workstation. The specific test conditions are as follows:

[0067] Test method: i-t-Amperometric i-t Curve;

[0068] Test potential: 1.6V vs. RHE

[0069] Stabilization time: 2s

[0070] Sensitivity: 1.e -001 A / V

[0071] Each of the two chambers was filled with 60 mL of 1M KOH, and in addition, 0.3M ethylene glycol was added to the anode end. The anode electrolyte was replaced every 24h.

[0072] Take 80 μL of the replaced electrolyte, add 20 μL of 2M sulfuric acid solution and 900 μL of deionized water for neutralization and dilution. Use

[0073] Shimazu LC-40D high performance liquid chromatograph as an analyzer, with a standard automatic sampler, a variable wavelength scanning ultraviolet detector. The detection chromatographic conditions for organic acids are as follows:

[0074] Chromatographic column: Angilent Hi-Plex H, 8 μm, 7.7 x 300 mm;

[0075] Mobile phase: 5mM sulfuric acid;

[0076] Flow rate: 0.6ml / min

[0077] Column temperature: 50°C

[0078] Injection volume: 10μL

[0079] Detection wavelength: 210nm.

[0080] 4. Site action proof test

[0081] Three-electrode H-type electrolysis cell was built, and the anion exchange membrane was used to separate the two chambers. NiCuCoO4 / NF, NiCo2O4 / NF, CuCo2O4 / NF, and Co3O4 / NF were used as working electrodes, platinum mesh electrode as counter electrode, Hg|HgO electrode as reference electrode. The instrument used was Chenhua 660E electrochemical workstation, and the specific test conditions were as follows:

[0082] Test method: i-t-Amperometric i-t Curve;

[0083] Run time: 10h

[0084] Steady voltage time: 2s

[0085] Sensitivity: 1.e-001A / V

[0086] To verify Ni 3+ As a Brønsted acid site, each chamber was filled with 10mL 1M KOH, so that the concentration of EG at the anode end was 0.01M, 0.03M, 0.05M, 0.1M, 0.3M in turn. Further, to verify Cu 2+ As a Lewis acid site, the concentration of KOH in the two chambers was 0.1M, 0.25M, 0.5M, 1M, 2M in turn.

[0087] Experimental results

[0088] 1. Successful preparation of NiCuCoO4 / NF

[0089] Figure 1 The X-ray diffraction peaks of NiCuCoO4 / NF catalyst were shown, and it could be found that the characteristic peaks were poor, indicating that the crystallinity of the material was low. Compared with crystalline materials, low crystallinity materials have higher disorder degree, which can provide more active sites for the reaction, thereby improving the reaction activity of the catalyst. Figure 2 The X-ray photoelectron spectrum of the catalyst showed that the metal elements in the material after oxidation mainly existed in the form of high oxidation state (Ni3+ , Cu 2+ ,Co 3+ ). In the electrocatalytic oxidation process, OH - In addition to concentration, high-valent metal elements also have a significant promoting effect on the oxidation process, that is, high-valent metal elements in the catalyst are more likely to deprive the reactants of electrons in the electrolyte, causing them to lose electrons and oxidize. Figure 3 It can be seen that NiCuCoO4 exhibits an obvious nanosheet structure. This two-dimensional nanostructure is conducive to the rapid conduction of electrons at the catalyst interface, thereby improving the efficiency of the reaction.

[0090] 2. Electrocatalytic performance of NiCuCoO4 / NF

[0091] Figure 4 The OER and EGOR performance of NiCuCoO4 / NF were demonstrated. In 1M KOH electrolyte, NiCuCoO4 / NF started to undergo OER at a potential of 1.5V vs. RHE and required a potential of 1.6V vs. RHE to reach 100mA·cm -2 The current density of NiCo2O4 / NF is 2.5 times that of NiCo2O4 / NF, CuCo2O4 / NF and Co3O4 / NF respectively. This shows that the strategy of the present invention can successfully modify Co3O4. In actual industrial electrocatalytic oxidation reforming applications, the current density generally needs to reach 300mA·cm -2 For NiCuCoO4 / NF, the potential required to achieve this current density is only 1.39Vvs.RHE, which has a great advantage among non-precious metal catalysts.

[0092] 3. Analysis of Ethylene Glycol Electrooxidation Products and Stability Test of NiCuCoO4 / NF

[0093] Firstly, the EGOR products of NiCuCoO4 / NF were analyzed. Figure 5 Is NiCuCoO4 / NF in the electrolyte after EGOR 1 In the H NMR spectrum, in addition to the solvent D2O, the internal standard DMSO and the reactant EG, only formic acid was detected, indicating that formic acid is the only product of the EGOR reaction, which also facilitates the subsequent separation and purification of formic acid. This experiment tested the electrocatalytic oxidation of ethylene glycol at 1.4-1.8V vs. RHE.Figure 6 As shown, ethylene glycol maintained a relatively high Faraday efficiency of ethylene glycol oxidation in the potential range of 1.4-1.7 V vs. RHE, and the efficiency reached the highest at 1.6 V vs. RHE, which was 95.48%. In addition, the yield of formic acid showed an upward trend during the process of potential rising, but changed little after 1.6 V vs. RHE. This is because at a higher potential, a competitive OER reaction occurs, which reduces the efficiency of the EGOR reaction. Further, according to this result, the present experiment selected the potential of 1.6 V vs. RHE to explore the EGOR stability of the catalyst. Figure 7 The results of the stability test of NiCuCoO4 / NF are shown, and it can be seen from the figure that the catalyst exhibits stable EGOR performance in 168 hours, and the current density can be better maintained in the required range of industrial current density. In addition, the stable high Faraday efficiency (> 90%) further confirms the feasibility of the catalyst in large-scale application.

[0094] 4. Explanation of site effect in NiCuCoO4 / NF

[0095] To further explain the effect of each site in the catalyst, the present application tests the current density change of NiCuCoO4 / NF, CuCo2O4 / NF, and Co3O4 / NF at 1.4 V vs. RHE in electrolyte with different concentrations of KOH and different concentrations of EG, and respectively takes OH - concentration and EG concentration as the abscissa, and the current density as the ordinate, and linearly fits the whole change process, so as to more intuitively judge. First of all, the active substance responsible for the adsorption of OH - in the catalyst is explored, and the present application tests the change of the oxidation current of 0.3 M EG of the above four catalysts in electrolyte with different concentrations of KOH, as shown in Figure 8 (a) figure, NiCuCoO4 / NF is most sensitive to the change of OH - concentration in the electrolyte, and its slope reaches 201.8, followed by CuCo2O4 / NF (153.06), NiCo2O4 / NF (78.85), and Co3O4 / NF (37.95). That is, when the catalyst contains Cu element, the adsorption capacity of OH - is obviously enhanced, which shows that the Cu site is responsible for the adsorption of OH-. When the research object is the EG concentration in the electrolyte, NiCuCoO4 / NF still shows the strongest sensitivity to it, and its slope reaches 725.76, followed by NiCo2O4 / NF (540.36), CuCo2O4 / NF (307.20), and

[0096] Co3O4 / NF (113.93), that is, when the catalyst contains Ni element, the adsorption capacity of the catalyst to EG is obviously enhanced, which indicates that the Ni site is responsible for the adsorption of EG.

[0097] To further illustrate the specific changes of these sites during the reaction process, the present application compares the relative proportions of Ni 3+ , Cu 2+ , and Co 3+ in the catalyst before and after the reaction. Figure 2 It is found through comparison that after the catalyst is subjected to EGOR, the proportion of Ni 3+ (49.0% to 81.5%) and Cu 2+ (56.4% to 77.0%) is increased, while the content of Co 3+ (59.9% to 28.6%) is decreased. It is indicated that during the EGOR process, the electrons of the Ni site and the Cu site are transferred to the Co site, thereby exposing more Ni 3+ and Cu 2 + Therefore, specifically, during the EGOR reaction process, the Ni 3+ site is responsible for the adsorption of EG, and the Cu 2+ site is responsible for the adsorption of OH-, that is, the modified intrinsic Co3O4 catalyst has the adsorption capacity of organic matter and OH - simultaneously enhanced, thereby making it have the potential for industrial scale application.

[0098] Although the content of the present application has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present application.

Claims

1. A method for producing hydrogen by reforming ethylene glycol to formic acid using a nickel, copper, and cobalt ternary metal catalyst at an industrial-grade current density, characterized in that: The method is as follows: An electrolytic cell containing an anion exchange membrane is used, with a platinum electrode as the cathode and a material loaded with NiCuCoO4 on a nickel foam substrate as the anode. A potassium hydroxide solution is added to the cathode reaction chamber as the cathode electrolyte, and a potassium hydroxide solution containing ethylene glycol is added to the anode reaction chamber as the anode electrolyte. The anode electrolyte in the anode reaction chamber undergoes a coupled electrolysis reaction under stirring and room temperature conditions, wherein the anode reaction chamber produces formic acid as a product and the cathode reaction chamber produces hydrogen as a product. The anode is prepared by the following method: (1) Cleaning the nickel foam substrate; (2) Prepare a solution containing cobalt nitrate (Co(NO3)2), nickel nitrate (Ni(NO3)2), and copper nitrate (Cu(NO3)2); (3) assembling a single-chamber electrolytic cell system containing the nickel foam obtained in step (1) as a working electrode, a platinum mesh electrode as a counter electrode, an Ag|AgCl electrode as a reference electrode, and the solution obtained in step (2) as an electrolyte; (4) After connecting to the electrochemical workstation, apply a constant current to the working electrode for a certain period of time; (5) Taking out the material, sending the material to a muffle furnace for heating and oxidation to obtain the anode.

2. The method according to claim 1, wherein A platinum mesh electrode was used as the cathode, and a 1 M potassium hydroxide solution was added to the cathode reaction chamber.

3. The method according to claim 1, wherein In the anolyte, the concentration of ethylene glycol is 0.1-0.3 M, and the concentration of potassium hydroxide is 1 M.

4. The method according to claim 1, wherein The total metal ion concentration in the solution containing cobalt nitrate, nickel nitrate and copper nitrate required for preparing the anode catalytic electrode described in claim 1 is 20-40 mM.

5. The method according to claim 1, wherein The magnitude of the constant current is 10 to 20 mA.

6. The method according to claim 1, wherein The constant current power-on time for electrodeposition to prepare the anode electrode is 5 to 15 minutes.

7. The method according to claim 1, wherein The oxidation temperature of the material is 300-400° C., and the heating time is 150-200 minutes.

8. The method according to claim 1, wherein Ethylene glycol was oxidized at a potential of 1.4-1.8 V vs. RHE.

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