Electrocatalytic oxygen reduction tandem aldehyde oximation method

Abstract

The invention relates to an electrocatalytic oxygen reduction and aldehyde oximation tandem method, belongs to the technical field of electrocatalysis, and solves at least one of the problems of poor safety, high energy consumption, more byproducts and lower selectivity of an aldehyde oxime preparation method in the prior art. According to the method, a cathode is a carbon catalyst electrode, and a carbon catalyst is at least one of XC-72, acetylene black and graphene oxide; the anode is at least one of iridium tantalum titanium, glassy carbon and platinum; the catholyte comprises a molecular sieve catalyst, aldehyde and an ammonium salt solution, the anolyte is a sulfuric acid solution, and the catholyte and the anolyte are separated through a proton exchange membrane; and carrying out an electrocatalytic reaction, carrying out an electrocatalytic oxygen reduction reaction on the cathode to generate hydrogen peroxide, carrying out a reaction on the hydrogen peroxide and NH4 < + > in the catholyte to generate hydroxylamine, and carrying out a C-N coupling reaction on the hydroxylamine and aldehyde to generate aldoxime. The method is safe, the value of the cathode product is improved, the energy consumption is low, and the selectivity is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalysis, and particularly relates to a method for electrocatalytic oxygen reduction and aldoxime coupling in series. BACKGROUND

[0002] Aldoxime is a fine chemical with wide application, and oxime is crucial in pesticide synthesis, the medical field, metal ion detection, material science and organic synthesis reactions, with a global demand of more than 9 million tons per year. With the promotion of carbon neutralization policy, it is extremely important to develop and utilize renewable energy for chemical synthesis.

[0003] The existing aldoxime production method is benzaldehyde condensation with hydroxylamine, which is the most commonly used and mature industrialized method. Benzaldehyde and hydroxylamine derivatives (such as hydroxylamine hydrochloride) undergo nucleophilic addition-elimination reaction to generate benzaldehyde oxime under alkaline conditions. However, this method needs to use high-purity benzaldehyde, which has safety problems, and the method also has problems of high energy consumption, many by-products and low selectivity. SUMMARY

[0004] In view of the above analysis, the embodiments of the present application aim to provide a method for electrocatalytic oxygen reduction and aldoxime coupling in series, to solve at least one of the problems of poor safety, high energy consumption, many by-products and low selectivity in the existing aldoxime preparation method.

[0005] In one aspect, the embodiments of the present application provide a method for electrocatalytic oxygen reduction and aldoxime coupling in series, which comprises: The cathode is a carbon catalyst electrode, and the carbon catalyst is at least one of XC-72, acetylene black and graphene oxide; the anode is at least one of iridium tantalum titanium, glassy carbon and platinum; The cathode electrolyte comprises a molecular sieve catalyst, an aldehyde, a base and an ammonium salt solution, the anode electrolyte is a sulfuric acid solution, and the cathode electrolyte and the anode electrolyte are separated by a proton exchange membrane; The electrocatalytic reaction is carried out, the cathode undergoes an electrocatalytic oxygen reduction reaction to generate hydrogen peroxide, the hydrogen peroxide reacts with NH 4+ to generate hydroxylamine, and the hydroxylamine reacts with the aldehyde to generate C-N coupling to generate aldoxime.

[0006] Preferably, the preparation method of the carbon catalyst electrode comprises the following steps: Step (1), annealing treatment is performed on a commercially available carbon catalyst at 400-600 DEG C, and the annealed carbon catalyst is washed with deionized water and dried to obtain an oxygen-doped carbon catalyst; Step (2), the oxygen-doped carbon catalyst is dispersed in a solution containing Nafion, alcohol and deionized water to prepare an ink slurry, and the ink slurry is sprayed on a current-carrying body and dried to obtain the carbon catalyst electrode.

[0007] Preferably, in step (1), the temperature of the drying is 50-100 DEG C.

[0008] Preferably, in step (2), the alcohol is isopropanol and / or ethanol.

[0009] Preferably, in step (2), the oxygen-doped carbon catalyst, Nafion, alcohol and deionized water are used in a ratio of 2-10 mg: 20-50 muL Nafion: 470-970 muL: 200-500 muL.

[0010] Preferably, in the carbon catalyst electrode, the loading of the carbon catalyst is 0.2-0.8 mg / cm 2 .

[0011] Preferably, in step (2), the current-carrying fluid is one of carbon cloth, hydrophilic carbon paper, hydrophobic carbon paper, nickel foam, nickel sheet, nickel mesh, copper foam, copper sheet, copper mesh, titanium sheet, titanium mesh, stainless steel sheet, stainless steel mesh, ITO conductive glass and FTO conductive glass.

[0012] Preferably, in the cathode electrolyte, the molecular sieve catalyst, aldehyde and ammonium salt are used in a ratio of 100-500 mg: 1-100 mmol: 0.5-1 mol.

[0013] Preferably, the sulfuric acid concentration of the anode electrolyte is 0.1-1 M.

[0014] Preferably, the voltage of the electrocatalytic reaction is -0.5-1 V, and the time is 1-5 h.

[0015] Compared with the prior art, the present application can at least achieve one of the following beneficial effects: 1. The present application adopts a cathode oxygen reduction series C-N coupling amine oxime reaction, an electrocatalytic oxygen reduction reaction occurs at the cathode to generate hydrogen peroxide, and the hydrogen peroxide reacts with NH 4+ in the cathode electrolyte to generate hydroxylamine, and the hydroxylamine reacts with the aldehyde to generate aldehyde oxime. This series system produces aldehyde oxime not only safely, but also improves the value of the cathode product and reduces energy consumption.

[0016] 2. The cathode electrode catalyst prepared by the present application is obtained by annealing a commercial carbon catalyst. After oxygen doping by heat treatment, it has excellent ORR performance, further improves the aldehyde conversion rate and product selectivity, and has less by-products.

[0017] 3. For the cathode oxygen reduction process, the catalytic activity is improved by oxygen doping, which helps to reduce oxygen to hydrogen peroxide; at the same time, since the in-situ synthesized hydrogen peroxide is used for C-N coupling amine oximation of aldehyde in series, the problem of not being able to use in-situ generated hydrogen peroxide is further solved, and the economic value and practicability of the cathode product are improved.

[0018] 4. In the three-electrode H cell system, the faradic efficiency of the commercial carbon catalyst modified by oxygen doping for electrocatalytic oxygen reduction to prepare hydrogen peroxide can reach 92%, and the system can be stably operated for 100 h under a current density of 200 mA / cm 2 .

[0019] In the present application, the above technical solutions can be combined with each other to realize more preferred combination schemes. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purpose and other advantages of the present application can be realized and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0021] Figure 1 It is an oximation reaction route schematic diagram of aldehyde C-N coupling amine oximation in series with oxygen reduction.

[0022] Figure 2 It is an X-ray diffraction pattern of the cathode carbon catalyst in Example 1.

[0023] Figure 3 It is a scanning electron microscope (a) and a transmission electron microscope (b) of the cathode carbon catalyst in Example 1.

[0024] Figure 4 It is a nuclear magnetic resonance hydrogen spectrum of the cathode electrolyte product in Example 1 and an oximation reaction route schematic diagram of benzaldehyde oximation in series with oxygen reduction.

[0025] Figure 5 It is an oximation reaction route schematic diagram of aldehyde C-N coupling amine oximation in series with oxygen reduction.

[0026] Figure 6 It is a stable operation test of the system in Example 1. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present application will be specifically described below in conjunction with the drawings, wherein the drawings constitute a part of this application and are used to illustrate the principles of the embodiments of the present application, and are not used to limit the scope of the present application.

[0028] The present application provides a method for electrocatalytic oxygen reduction and aldehyde oxime formation in series, as shown in the formula, which comprises: Figure 1 The cathode is a carbon catalyst electrode, and the carbon catalyst is at least one of XC-72, acetylene black and graphene oxide, and is further preferably XC-72; the anode is at least one of iridium tantalum titanium, glassy carbon and platinum; The cathode electrolyte comprises a molecular sieve catalyst, an aldehyde, a base and an ammonium salt solution, the anode electrolyte is a sulfuric acid solution, and the cathode electrolyte and the anode electrolyte are separated by a proton exchange membrane; The electrocatalytic reaction is carried out, and the cathode undergoes an electrocatalytic oxygen reduction reaction to generate hydrogen peroxide, and the hydrogen peroxide reacts with NH 4+ to generate hydroxylamine, and the hydroxylamine reacts with the aldehyde to generate C-N coupling reaction to generate aldehyde oxime.

[0029] Compared with the prior art, the present application connects the oxygen reduction and the amine oximation reaction of aldehyde in series, in-situ electro-synthesizes hydrogen peroxide at the cathode, and connects the amine oximation reaction of aldehyde to synthesize oxime through C-N coupling reaction, to generate oxime products with higher economic value. For the cathode oxygen reduction reaction, a carbon catalyst is used as the cathode, and a commercial anode catalyst is used for system construction. The oxygen reduction and C-N coupling system only needs aldehyde and cathode electrolyte as raw materials, the ammonium salt electrolyte can be used as the electrolyte of the reaction system and the nitrogen source of C-N coupling, and the oxime product obtained by electrocatalytic synthesis has high conversion rate and selectivity, is environmentally friendly, has no by-products, the conversion rate of aldehyde in the reaction can be as high as 99.9%, and the selectivity of the product can be as high as 99.9%, solving the problems of large use of explosive hydroxylamine hazardous chemicals, low conversion rate and low product selectivity in the preparation of aldehyde oxime in the prior art.

[0030] Exemplarily, the preparation method of the carbon catalyst electrode comprises the following steps: Step (1), annealing treatment is performed on the commercially available carbon catalyst XC-72, acetylene black or graphene oxide at 400-600°C (for example, 400°C, 450°C, 500°C, 550°C or 600°C), and the annealed carbon catalyst is washed with deionized water and dried to obtain an oxygen-doped carbon catalyst; if the annealing temperature is too high, the carbon will be oxidized to carbon dioxide, and the oxygen-containing functional groups will be introduced only at the temperature in the present application; the carbon catalyst is further preferably XC-72; Step (2), the oxygen-doped carbon catalyst is dispersed in a solution containing Nafion, alcohol and deionized water to prepare an ink slurry, and the ink slurry is sprayed on a current-carrying body and dried to obtain the carbon catalyst electrode.

[0031] Exemplarily, in step (1), the drying is vacuum drying.

[0032] ​In an example, in step (1), the drying temperature is 50-100℃, such as 50℃, 60℃, 70℃, 80℃, 90℃, 100℃. If the drying temperature is too high, the material will be deformed, and if the drying temperature is too low, the material will not be dried completely.

[0033] In an example, in step (2), the alcohol is isopropyl alcohol and / or ethanol.

[0034] In an example, in step (2), the amount ratio of the oxygen-doped carbon catalyst, Nafion, alcohol and deionized water is 2-10 mg:20-50 μL:470-970 μL alcohol:200-500 μL.

[0035] In an example, in the carbon catalyst electrode, the loading amount of the carbon catalyst is 0.2-0.8 mg / cm 2 , such as 0.2 mg / cm 2 , 0.4 mg / cm 2 , 0.6 mg / cm 2 , 0.8 mg / cm 2 . If the loading amount is too low, the active sites will be too few to affect the catalytic effect, and if the loading amount is too high, the gas diffusion layer will be too thick, and the gas cannot be transported.

[0036] In an example, the drying temperature is 45-55℃.

[0037] In an example, in step (2), the current-carrying fluid is one of carbon cloth, hydrophilic carbon paper, hydrophobic carbon paper, nickel foam, nickel sheet, nickel mesh, copper foam, copper sheet, copper mesh, titanium sheet, titanium mesh, stainless steel sheet, stainless steel mesh, ITO conductive glass and FTO conductive glass.

[0038] In an example, in the cathode electrolyte, the amount ratio of the molecular sieve catalyst, aldehyde and ammonium salt is 100-500 mg:1-100 mmol:0.5-1 mol.

[0039] In an example, the molecular sieve catalyst is at least one of TS-1, TS-2, Ti-MWW, Ti-MOR and Ti-Beta.

[0040] In an example, the aldehyde is at least one of benzaldehyde, acetaldehyde and formaldehyde.

[0041] In an example, the ammonium salt is at least one of ammonium bicarbonate, ammonium chloride and ammonium carbonate.

[0042] In an example, the sulfuric acid concentration of the anode electrolyte is 0.1-1M, such as 0.1M, 0.3M, 0.5M, 0.7M, 1M.

[0043] Exemplarily, the electrocatalytic reaction is carried out in a three-electrode system, and the reference electrode is mercury / mercury oxide.

[0044] Exemplarily, during the electrolysis process, oxygen is introduced into the cathode at a flow rate of 20-50 mL / min.

[0045] Exemplarily, the voltage of the electrocatalytic reaction is -0.5-1.3 V, and further preferably -0.3-0.1 V; and the time is 1-5 h.

[0046] Hereinafter, the method for electrocatalytic oxygen reduction and tandem aldehyde oxime formation according to the present application will be further illustrated by specific examples.

[0047] In the following examples, the raw materials used are obtained by commercial channels, and are not specifically stated as analytical pure or premium pure. Among them, the related reagents can be prepared into a certain concentration of aqueous solution for subsequent use.

[0048] The instrument, method and condition of XRD analysis: The test instrument is Shimadzu XRD-600, Cu Kα is used as the emission source (λ=0.15418 nm), and the voltage is 40 kV. The prepared electrode is directly tested to determine its crystal structure and phase composition, and the test range is 2θ of 5-80 degrees, and the scanning speed is 10 degrees / min.

[0049] The instrument, method and condition of SEM and TEM analysis: The test instrument is ZEISS Supra 55 of Germany, which directly tests the surface and side surface morphology characteristics.

[0050] The test instrument is JEM-2100F / Japan Electronic Corporation (JEOL), after the carbon catalyst is scraped off, it is dispersed with anhydrous ethanol by ultrasonic, 2-3 drops are taken by a dropper, and dropped on an ultrathin microgrid. After drying, the microstructure and crystal structure of the carbon catalyst are tested and observed.

[0051] The test electrochemical workstation is Chenhua 660E type.

[0052] Example 1 The example provides a method for electrocatalytic oxygen reduction and tandem aldehyde oxime formation, comprising: Preparation of carbon catalyst electrode: (1): 4 mg of XC-72 carbon material is weighed, and is subjected to annealing treatment at 500°C. The carbon catalyst after annealing treatment is washed with deionized water and dried at 80°C to obtain an oxygen-doped carbon catalyst. (2): The oxygen-doped carbon catalyst was ultrasonically dispersed in a mixed solution containing 30 μL of Nafion, 970 μL of isopropyl alcohol, and 500 μL of deionized water to form an ink suspension; the suspension was sprayed on commercial carbon paper, and the catalyst loading was 0.5 mg / cm 2 , and dried at 50 °C to obtain a cathode carbon catalyst electrode.

[0053] According to the structure of Figure 1 , an oxygen reduction tandem benzaldehyde C-N coupling hydroxylamine system was prepared, in which the above-prepared carbon catalyst electrode was used as the cathode, iridium tantalum titanium was used as the anode, mercury / mercury oxide was used as the reference electrode, the anode electrolyte was 0.5 M H2SO4 solution, the cathode electrolyte was 1 M NH4HCO3 and 5 mM benzaldehyde solution, and 300 mg of commercial TS-1 molecular sieve catalyst was added to the cathode side, wherein the amount ratio of the molecular sieve catalyst, benzaldehyde, and NH4HCO3 was 300 mg:5 mmol:1 mol. The constant potential voltage was-0.3 ~ 0.1 V (RHE), and potentiostatic electrolysis was performed for 5 hours. During the electrolysis process, oxygen was introduced into the cathode at a flow rate of 20 mL / min, and the cathode underwent an electrocatalytic oxygen reduction reaction to generate hydrogen peroxide. The hydrogen peroxide reacted with NH 4+ in the cathode electrolyte to generate hydroxylamine, and the hydroxylamine reacted with benzaldehyde to generate benzaldehyde oxime through C-N coupling.

[0054] The electrochemical performance of the system was tested at room temperature 25 °C, and then the product was detected by nuclear magnetic resonance.

[0055] Figure 2 The X-ray diffraction pattern of the cathode carbon catalyst is shown, and the characteristic peaks correspond to the standard characteristic peaks of the (002) and (100) crystal planes of carbon.

[0056] Figure 3 The scanning electron microscope and transmission electron microscope images of the cathode carbon catalyst are shown, and the catalyst morphology is irregular spherical.

[0057] Figure 4 The nuclear magnetic resonance hydrogen spectrum of the product of the cathode electrolyte and the schematic diagram of the oxygen reduction tandem benzaldehyde oximation reaction route are shown. It can be seen that after the tandem electrosynthesis, benzaldehyde is completely converted into benzaldehyde oxime target product.

[0058] Figure 5 The schematic diagram of the oxygen reduction tandem aldehyde C-N coupling hydroxylamine reaction route is shown. First, hydrogen peroxide is generated by oxygen reduction, and then Ti-OOH is formed from hydrogen peroxide under the catalysis of molecular sieve, which promotes the generation of *OOH and NH 4+ to generate hydroxylamine intermediate (NH2OH*), and finally NH2OH* reacts with benzaldehyde to generate benzaldehyde oxime through C-N coupling.

[0059] Figure 6 Example 1 was tested at 200 mA / cm 2 a current density of 200 mA / cm 2 and can be stably operated for 100 h at a current density of 200 mA / cm

[0060] Example 2 The example provides a method for electrocatalytic oxygen reduction coupled with aldehyde oximation, comprising: Preparation of a carbon catalyst electrode: (1): 4 mg of acetylene black was weighed and annealed at 500°C. The annealed carbon catalyst was washed with deionized water and dried at 80°C to obtain an oxygen-doped carbon catalyst; (2): The oxygen-doped carbon catalyst was ultrasonically dispersed in a mixture of 30 microliters of Nafion, 970 microliters of isopropanol, and 500 μL of deionized water to form an ink suspension. The suspension was sprayed onto commercial carbon paper with a catalyst loading of 0.5 mg / cm 2 and dried at 50°C to obtain a cathode carbon catalyst electrode.

[0061] An oxygen reduction coupled with formaldehyde C-N coupling amine oximation system was prepared, in which the above-prepared carbon catalyst electrode was used as the cathode, iridium tantalum titanium was used as the anode, mercury / mercury oxide was used as the reference electrode, the anode electrolyte was 0.5 M H2SO4, and the cathode electrolyte was 1 M NH4HCO3 and 5 mM formaldehyde solution. At the same time, 300 mg of commercial TS-1 molecular sieve catalyst was added to the cathode side, wherein the amount ratio of the molecular sieve catalyst, formaldehyde, and NH4HCO3 was 300 mg:5 mmol:1 mol. The constant potential voltage was-0.3 ~ 0.1 V (RHE), and constant potential electrolysis was performed for 5 hours. During the electrolysis process, oxygen was introduced into the cathode at a flow rate of 20 mL / min, and the cathode underwent an electrocatalytic oxygen reduction reaction to generate hydrogen peroxide. The hydrogen peroxide reacted with NH 4+ in the cathode electrolyte to generate hydroxylamine, and the hydroxylamine reacted with formaldehyde to generate formaldehyde oxime.

[0062] Example 3 The example provides a method for electrocatalytic oxygen reduction coupled with aldehyde oximation, comprising: Preparation of a carbon catalyst electrode: (1): 4 mg of graphene oxide was weighed and annealed at 500°C. The annealed carbon catalyst was washed with deionized water and dried at 80°C to obtain an oxygen-doped carbon catalyst; (2): The oxygen-doped carbon catalyst was ultrasonically dispersed in a mixture solution of 30 μL Nafion, 970 μL isopropanol and 500 μL deionized water to form an ink suspension; the suspension was sprayed on a commercial carbon paper, and the catalyst loading was 0.5 mg / cm 2 The cathode carbon catalyst electrode was obtained by drying at 50 °C.

[0063] An oxygen reduction tandem acetaldehyde C-N coupling hydroxamidation system was prepared, in which the carbon catalyst electrode prepared above was used as the cathode, iridium tantalum titanium was used as the anode, mercury / mercury oxide was used as the reference electrode, and 0.5 M H2SO4 was used as the anode electrolyte; 1 M NH4HCO3 and 5 mM acetaldehyde solution were used as the cathode electrolyte, and 300 mg of commercial TS-1 molecular sieve catalyst was added to the cathode side, wherein the amount ratio of the molecular sieve catalyst, acetaldehyde and NH4HCO3 was 300 mg:5 mmol:1 mol. The constant potential voltage was-0.3 ~ 0.1 V (RHE), and constant potential electrolysis was carried out for 5 hours. During the electrolysis process, oxygen was introduced into the cathode at a flow rate of 20 mL / min, and the cathode generated an electrocatalytic oxygen reduction reaction to generate hydrogen peroxide. The hydrogen peroxide reacted with NH4HCO3 in the cathode electrolyte to generate hydroxylamine, and the hydroxylamine reacted with acetaldehyde to generate acetaldehyde oxime. 4+ The reaction generated hydroxylamine, and the hydroxylamine reacted with acetaldehyde to generate acetaldehyde oxime.

[0064] Comparative Example 1 This comparative example provides a method of electrocatalytic oxygen reduction tandem aldehyde oximation similar to that of Example 1, except that in the preparation method of the carbon catalyst electrode, the XC-72 carbon material was not annealed, and the commercially available XC-72 carbon material was directly dispersed in a mixed solution containing 30 μL Nafion, 970 μL isopropanol and 500 μL deionized water to form an ink suspension by ultrasonic; the suspension was sprayed on a commercial carbon paper, and the catalyst loading was 0.5 mg / cm 2 The cathode carbon catalyst electrode was obtained by drying at 50 °C.

[0065] Comparative Example 2 This comparative example provides a method of electrocatalytic oxygen reduction tandem aldehyde oximation similar to that of Example 1, except that in the preparation method of the carbon catalyst electrode, the annealing temperature was 300 °C.

[0066] Comparative Example 3 This comparative example provides a method of electrocatalytic oxygen reduction tandem aldehyde oximation similar to that of Example 1, except that in the preparation method of the carbon catalyst electrode, the annealing temperature was 700 °C.

[0067] Comparative Example 4 The benzaldehyde oxime is prepared by the method of the prior art, i.e. benzaldehyde and hydroxylamine condensation method, in which benzaldehyde and hydroxylamine hydrochloride are subjected to nucleophilic addition-elimination reaction under alkaline conditions to generate benzaldehyde oxime.

[0068] Although the benzaldehyde and hydroxylamine condensation method is the mainstream method for industrial synthesis of benzaldehyde oxime, it still has the following obvious deficiencies. First, the reaction has extremely high requirements for the purity of raw materials (purity ≥ 98%), and the cost of pretreatment of raw materials is increased; in the condensation process, the use of hydroxylamine has safety hazards and storage difficulties; after the reaction, the pressure of wastewater treatment is large, and the environmental protection cost is high; the production efficiency is low, the steps are relatively complicated, and the production cycle is long; the cost of raw materials is high, and the economic benefit is limited.

[0069] The deficiencies of the benzaldehyde and hydroxylamine condensation method mainly lie in the purity of raw materials, safety, environmental protection cost, production efficiency and the like. In order to make up for these defects, we have developed a method of in-situ generation of hydroxylamine by electro-synthesis of hydrogen peroxide, and then in-situ aldehyde oximation reaction, which can shorten the reaction time and realize green, efficient, economic and safe aldehyde oximation preparation.

[0070] The aldehyde conversion rate and product selectivity data of examples 1-3 and comparative examples 1-4 are listed in table 1.

[0071] Table 1

[0072] As can be seen from table 1, the method of aldehyde oximation by electro-catalytic oxygen reduction in series adopted by the present application has high aldehyde conversion rate and product selectivity. Specifically, example 1 uses XC-72 as a carbon catalyst, which has the highest aldehyde conversion rate and product selectivity. Compared with the conventional method of comparative example 4, example 1 not only has high aldehyde conversion rate and product selectivity, but also has high safety, low energy consumption and few by-products due to the electrolytic method; examples 2 and 3 have slightly lower aldehyde conversion rate and product selectivity compared with comparative example 4, but still have the advantages of high safety, low energy consumption and few by-products.

[0073] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements easily thought of by those skilled in the art within the technical range disclosed by the present application should be covered within the protection scope of the present application.

Claims

1. A method for electrocatalytic oxygen reduction tandem aldoxime conversion, characterized in that, The method includes: The cathode is a carbon catalyst electrode, wherein the carbon catalyst is at least one of XC-72, acetylene black, and graphene oxide; the anode is at least one of iridium-tantalum-titanium, glassy carbon, and platinum. The cathode electrolyte includes a molecular sieve catalyst, an aldehyde and an ammonium salt solution, and the anolyte is a sulfuric acid solution. The cathode electrolyte and the anolyte are separated by a proton exchange membrane. An electrocatalytic reaction occurs at the cathode, where an electrocatalytic oxygen reduction reaction produces hydrogen peroxide. The hydrogen peroxide then reacts with NH4+ in the cathode electrolyte. 4+ The reaction produces hydroxylamine, which then undergoes a CN coupling reaction with an aldehyde to form an aldoxime.

2. The method according to claim 1, characterized in that, The preparation method of the carbon catalyst electrode includes the following steps: Step (1): Anneal the commercially available carbon catalyst at 400~600℃, rinse the annealed carbon catalyst with deionized water and dry it to obtain an oxygen-doped carbon catalyst. Step (2): Disperse the oxygen-doped carbon catalyst in a solution containing Nafion, alcohol and deionized water to prepare an ink slurry. Spray the ink slurry onto the carrier fluid and dry it to obtain the carbon catalyst electrode.

3. The method according to claim 2, characterized in that, In step (1), the drying temperature is 50~100℃.

4. The method according to claim 2, characterized in that, In step (2), the alcohol is isopropanol and / or ethanol.

5. The method according to claim 2, characterized in that, In step (2), the ratio of oxygen-doped carbon catalyst, Nafion, alcohol and deionized water is 2~10mg: 20~50μL: 470~970μL: 200~500μL.

6. The method according to claim 1 or 2, characterized in that, In the carbon catalyst electrode, the loading of carbon catalyst is 0.2~0.8 mg / cm³. 2 .

7. The method according to claim 2, characterized in that, In step (2), the carrier fluid is one of carbon cloth, hydrophilic carbon paper, hydrophobic carbon paper, nickel foam, nickel sheet, nickel mesh, copper foam, copper sheet, copper mesh, titanium sheet, titanium mesh, stainless steel sheet, stainless steel mesh, ITO conductive glass and FTO conductive glass.

8. The method according to claim 1, characterized in that, In the cathode electrolyte, the ratio of the molecular sieve catalyst, aldehyde, and ammonium salt is 100~500 mg: 1~100 mmol: 0.5~1 mol.

9. The method according to claim 1, characterized in that, The sulfuric acid concentration of the anolyte is 0.1~1M.

10. The method according to claim 1, characterized in that, The voltage for the electrocatalytic reaction is -0.5 to 1 V, and the time is 1 to 5 hours.

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