Process for the electrocatalytic preparation of formaldehyde oxime under mild conditions

Abstract

The application discloses a method for electrocatalytically preparing formaldehyde oxime under mild conditions and belongs to the technical field of electrocatalytic organic synthesis. The method comprises the following steps: (1) an anode catalyst is used as an anode, a two-dimensional metal-based catalyst supported on a substrate is used as a cathode, and an electrolyte, an ion exchange membrane and an Ag / AgCl reference electrode are assembled into an electrocatalytic reactor; (2) a nitrogen source and a gaseous carbon source are added into the electrolyte in the cathode chamber, and the nitrogen source and the gaseous carbon source are reduced respectively under room temperature, normal pressure and a voltage of-0.1 to-5 V vs. RHE, and then a carbon-nitrogen coupling reaction occurs to generate formaldehyde oxime. Compared with a traditional formaldehyde oxime synthesis method, the electrocatalytic method has mild reaction conditions and a simple process route, and provides a new idea and method for green and inexpensive preparation of formaldehyde oxime.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalytic organic synthesis, and in particular to a method for preparing formaldehyde oxime under mild conditions through electrocatalysis. Background Art

[0002] Formaldehyde oxime, with the molecular formula CH2NOH, is a colorless or slightly yellow liquid at room temperature and normal pressure with a pungent odor. It is easily oxidized or participates in addition reactions, and can be used as a reducing agent or reactive intermediate. Formaldehyde oxime is primarily used in the synthesis of various nitrogen-containing organic compounds, such as hydrazines, pyrazoles, and nitrogen-containing heterocyclic compounds. It has potential value in the design of fungicides, herbicides, and pharmaceutical molecules. It is also commonly used for the quantitative determination of specific metal ions and as a precursor for specialized polymers or functional materials.

[0003] At present, the main method for synthesizing formaldehyde oxime in industry is the formaldehyde ammoxidation method, that is, formaldehyde oxime is prepared by the catalytic reaction of hydroxylamine and formaldehyde under acidic conditions with an acidic catalyst. The formaldehyde oxime ammoxidation method uses hydroxylamine salt as raw material, and the synthesis of hydroxylamine requires a complex production process, and hydroxylamine is prone to explosion under heating conditions, which increases the operating cost of the process. Zhang et al. reported a Mn catalyst that uses nitrate and formaldehyde as raw materials and realizes the preparation of formaldehyde oxime through an electrocatalytic pathway. However, this scheme uses formaldehyde as a carbon source, and the industrial preparation of formaldehyde relies on fossil energy, which increases production costs (Sci. Chi. Chem. 2023, 66, (6): 1758-1762.). Wang et al. reported a molecular nickel catalyst that can realize the electrosynthesis of formaldehyde oxime using carbon dioxide and nitrate as raw materials, but its yield is low, selectivity is poor, and economic benefits are not high (Nat. Sustain. 2021, 4 (8): 725-730.). Therefore, developing an environmentally friendly, low-cost, highly active and highly selective formaldehyde oxime synthesis route is of great significance and will help enrich the synthesis paths of more high-value-added fine chemicals. Summary of the Invention

[0004] To address the above technical issues, the present invention provides a method for the electrocatalytic synthesis of formaldehyde oxime under mild conditions. This method utilizes a metal-based oxide as a cathode catalyst, inorganic carbon and nitrogen sources as raw materials, and employs electrocatalytic technology to directly produce formaldehyde oxime. This reduces dependence on fossil resources and environmental hazards, achieving the green and sustainable production of high-value-added chemicals.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows: The present invention provides a method for preparing formaldehyde oxime by electrocatalysis under mild conditions, characterized in that it comprises the following steps:

[0006] (1) Assembling the electrocatalytic reactor

[0007] The anode catalyst is used as an anode, and the two-dimensional metal-based catalyst supported by the support substrate is used as a cathode, to assemble an electrocatalytic reactor with an electrolyte, an ion exchange membrane and an Ag / AgCl reference electrode.

[0008] The two-dimensional metal-based cathode catalyst is any one of titanium oxide, copper oxide, niobium oxide, iron oxide, vanadium oxide and molybdenum oxide.

[0009] (2) Electro-catalytic reaction

[0010] The nitrogen source and the gaseous carbon source are added to the electrolyte in the cathode chamber, and at room temperature, normal pressure and a voltage of -0.1 to -5 V vs. RHE, the nitrogen source and the gaseous carbon source are reduced in the cathode chamber, and then a carbon-nitrogen coupling reaction occurs to generate formaldehyde oxime.

[0011] As shown in Figure 1 , in the electro-catalytic reaction, the carbon source and the nitrogen source in the cathode undergo an electro-catalytic co-reduction reaction to generate formaldehyde oxime, and the anode undergoes an electro-catalytic water oxidation reaction.

[0012] Preferably, the voltage is -0.6 to -1.5 V vs. RHE.

[0013] Preferably, the gaseous carbon source is one of carbon dioxide and carbon monoxide, and the electrolyte should be pre-saturated with the gaseous carbon source before the electro-catalytic reaction; during the electro-catalytic reaction, the flow rate of the carbon source gas is controlled at 1 to 50 mL min -1 .

[0014] Preferably, the nitrogen source is one of nitrogen, nitric oxide, nitrogen dioxide, potassium nitrate, potassium nitrite, sodium nitrate and sodium nitrite.

[0015] When the nitrogen source is a gas, the electrolyte should be pre-saturated with the gaseous nitrogen source before the electro-catalytic reaction; during the electro-catalytic reaction, the flow rate of the gaseous nitrogen source is controlled at 1 to 50 mL min -1 ; when the nitrogen source is potassium nitrate, potassium nitrite, sodium nitrate or sodium nitrite, the concentration of the nitrogen source in the electrolyte in the cathode chamber is 0.005 to 1.0 M.

[0016] Preferably, the electrolyte is an aqueous solution of any one or several of sodium hydroxide, potassium hydroxide, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, sodium sulfate or potassium sulfate; the molar concentration of the electrolyte is 0.01 to 2 M.

[0017] Preferably, the diaphragm is any one of AMI7001, CMI7000, FAA-320, nafion XL or nafion 117.

[0018] Preferably, the anode catalyst is any one of platinum sheet and nickel foam.

[0019] Preferably, the electric energy required for the operation of the electrocatalytic reactor comes from clean and renewable energy sources such as solar energy, wind energy, and hydropower.

[0020] The beneficial effects of the present invention are:

[0021] The present invention provides a method for preparing formaldehyde oxime by electrocatalysis under mild conditions. The method adopts an electrochemical method, uses cheap and readily available carbon dioxide and carbon monoxide as carbon sources, and uses nitrogen, nitric oxide, nitrate and nitrite as nitrogen sources, to synthesize formaldehyde oxime in a one-step process. This method avoids the use of expensive and unstable hydroxylamine as a reaction raw material and the use of acidic solutions, thereby significantly reducing the production cost of formaldehyde oxime and improving the safety of the production process.

[0022] Compared with traditional formaldehyde oxime preparation methods, the electrocatalytic method of the present invention does not require the use of acidic solutions and strong oxidants, has mild reaction conditions, and simple steps, providing new ideas and methods for the green and sustainable preparation of formaldehyde oxime. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the electrocatalytic reaction for preparing formaldehyde oxime according to the present invention;

[0024] Figure 2 The NMR spectra of the reaction solution and the standard drug formaldehyde oxime in Example 1 of the present invention are as follows;

[0025] Figure 3 Graph showing the formaldehyde oxime generation rate and Faraday efficiency in Examples 1-10 of the present invention. DETAILED DESCRIPTION

[0026] The following non-limiting examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0027] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0028] Example 1

[0029] Formaldehyde oxime is prepared by electrocatalysis using potassium nitrate as a nitrogen source and carbon dioxide as a carbon source, comprising the following steps:

[0030] (1) A 1.0 M aqueous solution of potassium bicarbonate was used as the cathode electrolyte. Potassium nitrate was dissolved in the cathode electrolyte to make the concentration of potassium nitrate 0.1 M. Before the reaction, the electrolyte was heated at 50 mL min. -1 The flow rate of carbon dioxide was continuously passed for 30 minutes to saturate the electrolyte with carbon dioxide. The flow rate of carbon dioxide during the reaction was 20 mL min -1, Nafion 117 as the separator, and 1.0 M potassium bicarbonate aqueous solution as the anolyte;

[0031] (2) A two-dimensional titanium dioxide catalyst was loaded on a carbon cloth as a cathode (the preparation method of the two-dimensional titanium dioxide catalyst is referred to Ref: Adv. Mater. 2018, 30(11): 1705369.), a platinum sheet was used as an anode, and Ag / AgCl (saturated potassium chloride) was used as a reference electrode. At room temperature and pressure, a constant potential reaction was carried out at a voltage of -0.6 V vs. RHE for 2 h. Oxidation occurred at the anode to generate oxygen, and potassium nitrate and carbon dioxide were reduced at the cathode, respectively, and then a carbon-nitrogen coupling reaction occurred to generate formaldehyde oxime.

[0032] The obtained product was subjected to nuclear magnetic analysis, and the results were as follows Figure 2 As shown, the peak positions of the product formaldehyde oxime are 6.5 ppm and 7.0 ppm, respectively, and the retention time of the internal standard disodium maleate is 5.9 ppm.

[0033] The obtained product was quantified by NMR, and the yield and Faradaic efficiency of formaldehyde oxime were calculated, as shown in Figure 3 shown.

[0034] Example 2

[0035] Formaldehyde oxime is prepared by electrocatalysis using nitric oxide as the nitrogen source and carbon dioxide as the carbon source:

[0036] (1) A 1.0 M potassium bicarbonate aqueous solution was used as the cathode electrolyte. Before the reaction, 50 mL min -1 The flow rate of carbon dioxide and nitric oxide was continuously passed for 30 minutes, and the electrolyte was saturated with carbon dioxide and nitric oxide. The flow rates of carbon dioxide and nitric oxide during the reaction were 20 mL min -1 and 10 mL min -1 , Nafion 117 as the separator, and 1.0 M potassium bicarbonate aqueous solution as the anolyte;

[0037] (2) Carbon cloth was used as a supporting substrate to load two-dimensional titanium dioxide as the cathode (the preparation method of two-dimensional titanium dioxide catalyst refers to Ref: Adv. Mater. 2018, 30(11): 1705369.), platinum sheet was used as the anode, and Ag / AgCl (saturated potassium chloride) was used as the reference electrode. At room temperature and pressure, a constant potential reaction was carried out at a voltage of -0.6 V vs. RHE for 2 h. Oxidation occurred at the anode to generate oxygen, and potassium nitrate and carbon dioxide were reduced at the cathode, respectively, and the reduction products underwent carbon-nitrogen coupling reaction to generate formaldehyde oxime.

[0038] The obtained product is subjected to nuclear magnetic resonance analysis, and a hydrogen spectrum peak of formaldehyde oxime can be detected.

[0039] The obtained product was quantified by NMR, and the yield and Faradaic efficiency of formaldehyde oxime were calculated, as shown in Figure 3 shown.

[0040] Example 3

[0041] Formaldehyde oxime is prepared by electrocatalysis using nitric oxide as a nitrogen source and carbon monoxide as a carbon source, comprising the following steps:

[0042] (1) A 1.0 M potassium bicarbonate aqueous solution was used as the cathode electrolyte. Before the reaction, 50 mL min -1 The flow rate of carbon monoxide and nitric oxide was continuously passed for 30 minutes, and the electrolyte was saturated with carbon monoxide and nitric oxide. The flow rate of carbon monoxide and nitric oxide during the reaction was 20 mL min -1 and 10 mL min -1 , Nafion 117 as the separator, and 1.0 M potassium bicarbonate aqueous solution as the anolyte;

[0043] (2) Carbon cloth was used as a supporting substrate to load two-dimensional titanium dioxide as the cathode (the preparation method of two-dimensional titanium dioxide catalyst refers to Ref: Adv. Mater. 2018, 30(11): 1705369.), platinum sheet was used as the anode, and Ag / AgCl (saturated potassium chloride) was used as the reference electrode. At room temperature and pressure, a constant potential reaction was carried out at a voltage of -0.6 V vs. RHE for 2 h. Oxidation occurred at the anode to generate oxygen, and potassium nitrate and carbon dioxide were reduced at the cathode, respectively, and the reduction products underwent carbon-nitrogen coupling reaction to generate formaldehyde oxime.

[0044] The obtained product is subjected to nuclear magnetic resonance analysis, and a hydrogen spectrum peak of formaldehyde oxime can be detected.

[0045] The obtained product was quantified by NMR, and the yield and Faradaic efficiency of formaldehyde oxime were calculated, as shown in Figure 3 shown.

[0046] Example 4

[0047] Formaldehyde oxime is prepared by electrocatalysis using nitric oxide as a nitrogen source and carbon dioxide as a carbon source, comprising the following steps:

[0048] (1) A 1.0 M potassium bicarbonate aqueous solution was used as the cathode electrolyte. Before the reaction, 50 mL min -1 The flow rate of carbon dioxide and nitric oxide was continuously passed for 30 minutes, and the electrolyte was saturated with carbon dioxide and nitric oxide. The flow rates of carbon dioxide and nitric oxide during the reaction were 20 mL min -1 and 10 mL min -1 , Nafion 117 as the separator, and 1.0 M potassium bicarbonate aqueous solution as the anolyte;

[0049] (2) A two-dimensional molybdenum oxide catalyst was loaded on a carbon cloth as a cathode (the preparation method of the two-dimensional molybdenum oxide catalyst is referred to Ref: Adv. Mater, 2016, 28(19): 3785-3790.), a platinum sheet was used as an anode, and Ag / AgCl (saturated potassium chloride) was used as a reference electrode. At room temperature and pressure, a constant potential test reaction was carried out at a voltage of -0.6 V vs. RHE for 2 h. Oxidation occurred at the anode to generate oxygen, and potassium nitrate and carbon dioxide were reduced at the cathode, respectively, and the reduction products underwent carbon-nitrogen coupling reaction to generate formaldehyde oxime.

[0050] The obtained product is subjected to nuclear magnetic resonance analysis, and a hydrogen spectrum peak of formaldehyde oxime can be detected.

[0051] The obtained product was quantified by NMR, and the yield and Faradaic efficiency of formaldehyde oxime were calculated, as shown in Figure 3 shown.

[0052] Example 5

[0053] Electrocatalytic preparation of formaldehyde oxime using potassium nitrate as nitrogen source and carbon dioxide as carbon source:

[0054] (1) A 1.0 M aqueous solution of potassium bicarbonate was used as the cathode electrolyte. Potassium nitrate was dissolved in the cathode electrolyte to make the concentration of potassium nitrate 0.1 M. Before the reaction, the electrolyte was heated at 50 mL min. -1 The flow rate of carbon dioxide was continuously passed for 30 minutes to saturate the electrolyte with carbon dioxide. The flow rate of carbon dioxide during the reaction was 20 mL min -1 , AMI7001 as the diaphragm, and 1.0 M potassium hydroxide aqueous solution as the anolyte;

[0055] (2) A two-dimensional vanadium oxide catalyst was loaded on a carbon cloth as a cathode (the preparation method of the two-dimensional vanadium oxide catalyst is referred to Ref: J. Power Sources, 2015, 294: 1-7.), a platinum sheet was used as an anode, and Ag / AgCl (saturated potassium chloride) was used as a reference electrode. At room temperature and pressure, a constant potential test reaction was carried out at a voltage of -0.6 V vs. RHE for 2 h. Oxidation occurred at the anode to generate oxygen, and potassium nitrate and carbon dioxide were reduced at the cathode, respectively, and the reduction products underwent carbon-nitrogen coupling reaction to generate formaldehyde oxime.

[0056] The obtained product is subjected to nuclear magnetic resonance analysis, and a hydrogen spectrum peak of formaldehyde oxime can be detected.

[0057] The obtained product was quantified by NMR, and the yield and Faradaic efficiency of formaldehyde oxime were calculated, as shown in Figure 3 shown.

[0058] Example 6

[0059] Formaldehyde oxime is prepared by electrocatalysis using nitric oxide as the nitrogen source and carbon dioxide as the carbon source:

[0060] (1) A 1.0 M potassium bicarbonate aqueous solution was used as the cathode electrolyte. Before the reaction, 50 mL min -1 The flow rate of carbon dioxide and nitric oxide was continuously passed for 30 minutes, and the electrolyte was saturated with carbon dioxide and nitric oxide. The flow rates of carbon dioxide and nitric oxide during the reaction were 5 mL min -1 and 50 mL min -1 , Nafion 117 as the separator, and 1.0 M potassium bicarbonate aqueous solution as the anolyte;

[0061] (2) A two-dimensional titanium dioxide catalyst was loaded on a carbon cloth as a cathode (the preparation method of the two-dimensional titanium dioxide catalyst is referred to Ref: Adv. Mater. 2018, 30(11): 1705369.), a platinum sheet was used as an anode, and Ag / AgCl (saturated potassium chloride) was used as a reference electrode. At room temperature and pressure, a constant potential reaction was carried out at a voltage of -0.1 V vs. RHE for 2 h. Oxidation occurred at the anode to generate oxygen, and potassium nitrate and carbon dioxide were reduced at the cathode, respectively, and the reduction products underwent carbon-nitrogen coupling reaction to generate formaldehyde oxime.

[0062] The obtained product is subjected to nuclear magnetic resonance analysis, and a hydrogen spectrum peak of formaldehyde oxime can be detected.

[0063] The obtained product was quantified by NMR, and the yield and Faradaic efficiency of formaldehyde oxime were calculated, as shown in Figure 3 shown.

[0064] Example 7

[0065] Formaldehyde oxime is prepared by electrocatalysis using nitric oxide as the nitrogen source and carbon dioxide as the carbon source:

[0066] (1) A 1.0 M potassium bicarbonate aqueous solution was used as the cathode electrolyte. Before the reaction, 50 mL min -1 The flow rate of carbon dioxide and nitric oxide was continuously passed for 30 minutes, and the electrolyte was saturated with carbon dioxide and nitric oxide. The flow rates of carbon dioxide and nitric oxide during the reaction were 5 mL min -1 and 50 mL min -1 , Nafion 117 as the separator, and 1.0 M potassium bicarbonate aqueous solution as the anolyte;

[0067] (2) A two-dimensional titanium dioxide catalyst was loaded on a carbon cloth as a cathode (the preparation method of the two-dimensional titanium dioxide catalyst is referred to Ref: Adv. Mater. 2018, 30(11): 1705369.), a platinum sheet was used as an anode, and Ag / AgCl (saturated potassium chloride) was used as a reference electrode. At room temperature and pressure, a constant potential reaction was carried out at a voltage of -1.5 V vs. RHE for 2 h. Oxidation occurred at the anode to generate oxygen, and potassium nitrate and carbon dioxide were reduced at the cathode, respectively, and the reduction products underwent carbon-nitrogen coupling reaction to generate formaldehyde oxime.

[0068] The obtained product is subjected to nuclear magnetic resonance analysis, and a hydrogen spectrum peak of formaldehyde oxime can be detected.

[0069] The obtained product was quantified by NMR, and the yield and Faradaic efficiency of formaldehyde oxime were calculated, as shown in Figure 3 shown.

[0070] Example 8

[0071] Electrocatalytic preparation of formaldehyde oxime using potassium nitrate as nitrogen source and carbon dioxide as carbon source:

[0072] (1) A 1.0 M aqueous solution of potassium bicarbonate was used as the cathode electrolyte. Potassium nitrate was dissolved in the cathode electrolyte to make the concentration of potassium nitrate 0.1 M. Before the reaction, the electrolyte was heated at 50 mL min. -1 The flow rate of carbon dioxide was continuously passed for 30 minutes to saturate the electrolyte with carbon dioxide. The flow rate of carbon dioxide during the reaction was 20 mL min -1 , AMI7001 as the diaphragm, and 1.0 M potassium hydroxide aqueous solution as the anolyte;

[0073] (2) A two-dimensional niobium oxide catalyst was loaded on a carbon cloth as a cathode (the preparation method of the two-dimensional niobium oxide catalyst is referred to Ref: Chem. Mater. 2016, 28(16): 5753-5760.), a platinum sheet was used as an anode, and Ag / AgCl (saturated potassium chloride) was used as a reference electrode. At room temperature and pressure, a constant potential test reaction was carried out at a voltage of -0.6 V vs. RHE for 2 h. Oxidation occurred at the anode to generate oxygen, and potassium nitrate and carbon dioxide were reduced at the cathode, respectively, and the reduction products underwent carbon-nitrogen coupling reaction to generate formaldehyde oxime.

[0074] The obtained product is subjected to nuclear magnetic resonance analysis, and a hydrogen spectrum peak of formaldehyde oxime can be detected.

[0075] The obtained product was quantified by NMR, and the yield and Faradaic efficiency of formaldehyde oxime were calculated, as shown in Figure 3 shown.

[0076] Example 9

[0077] Electrocatalytic preparation of formaldehyde oxime using potassium nitrite as nitrogen source and carbon dioxide as carbon source:

[0078] (1) A 1.0 M aqueous solution of potassium bicarbonate was used as the cathode electrolyte. Potassium nitrate was dissolved in the cathode electrolyte to make the concentration of potassium nitrate 0.1 M. Carbon dioxide was continuously passed through the electrolyte at a flow rate of 50 mL min-1 for 30 minutes before the reaction. The electrolyte was saturated with carbon dioxide. The flow rate of carbon dioxide during the reaction was 20 mL min-1. -1 , AMI7001 as the diaphragm, and 1.0 M potassium hydroxide aqueous solution as the anolyte;

[0079] (2) A two-dimensional niobium oxide catalyst was loaded on a carbon cloth as a cathode (the preparation method of the two-dimensional niobium oxide catalyst is referred to Ref: Chem. Mater. 2016, 28(16): 5753-5760.), a platinum sheet was used as an anode, and Ag / AgCl (saturated potassium chloride) was used as a reference electrode. At room temperature and pressure, a constant potential test reaction was carried out at a voltage of -0.6 V vs. RHE for 2 h. Oxidation occurred at the anode to generate oxygen, and potassium nitrate and carbon dioxide were reduced at the cathode, respectively, and the reduction products underwent carbon-nitrogen coupling reaction to generate formaldehyde oxime.

[0080] The obtained product is subjected to nuclear magnetic resonance analysis, and a hydrogen spectrum peak of formaldehyde oxime can be detected.

[0081] The obtained product was quantified by NMR, and the yield and Faradaic efficiency of formaldehyde oxime were calculated, as shown in Figure 3 shown.

[0082] Example 10

[0083] Formaldehyde oxime is prepared by electrocatalysis using nitric oxide as the nitrogen source and carbon dioxide as the carbon source:

[0084] (1) A 1.0 M potassium bicarbonate aqueous solution was used as the cathode electrolyte. Before the reaction, 50 mL min -1 The flow rate of carbon dioxide and nitric oxide was continuously passed for 30 minutes, and the electrolyte was saturated with carbon dioxide and nitric oxide. The flow rates of carbon dioxide and nitric oxide during the reaction were 50 mL min -1 and 5 mL min -1 , Nafion 117 as the separator, and 1.0 M potassium bicarbonate aqueous solution as the anolyte;

[0085] (2) A two-dimensional titanium dioxide catalyst was loaded on a carbon cloth as a cathode (the preparation method of the two-dimensional titanium dioxide catalyst is referred to Ref: Adv. Mater. 2018, 30(11): 1705369.), a platinum sheet was used as an anode, and Ag / AgCl (saturated potassium chloride) was used as a reference electrode. At room temperature and pressure, a constant potential reaction was carried out at a voltage of -0.6 V vs. RHE for 2 h. Oxidation occurred at the anode to generate oxygen, and potassium nitrate and carbon dioxide were reduced at the cathode, respectively, and the reduction products underwent carbon-nitrogen coupling reaction to generate formaldehyde oxime.

[0086] The obtained product is subjected to nuclear magnetic resonance analysis, and a hydrogen spectrum peak of formaldehyde oxime can be detected.

[0087] The obtained product was quantified by NMR, and the yield and Faradaic efficiency of formaldehyde oxime were calculated, as shown in Figure 3 shown.

[0088] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the scope defined in the claims. Other variations or modifications may be made based on the above description. Obvious variations or modifications derived therefrom shall remain within the scope of protection of the present invention.

Claims

1. A method for preparing formaldehyde oxime by electrocatalysis under mild conditions, characterized in that: The following steps are involved: (1) Assembling the electrocatalytic reactor The anode catalyst is used as the anode, the supporting substrate loaded with a two-dimensional metal-based catalyst is used as the cathode, and an electrocatalytic reactor is assembled with an electrolyte, an ion exchange membrane and an Ag / AgCl reference electrode; The two-dimensional metal-based cathode catalyst is any one of titanium oxide, copper oxide, niobium oxide, iron oxide, vanadium oxide, and molybdenum oxide; The electrolyte is an aqueous solution of any one or more of sodium hydroxide, potassium hydroxide, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, sodium sulfate, and potassium sulfate; (2) Electrocatalytic reaction A nitrogen source and a gaseous carbon source are added to the cathode electrolyte. At room temperature, atmospheric pressure, and a voltage of -0.1 to -5 V vs. RHE, the nitrogen source and the gaseous carbon source are reduced, respectively, and then a carbon-nitrogen coupling reaction occurs to generate formaldehyde oxime.

2. The method for preparing formaldehyde oxime using an electrocatalyst according to claim 1, wherein: The gaseous carbon source is one of carbon dioxide and carbon monoxide. The electrolyte should be pre-saturated with the gaseous carbon source before the electrocatalytic reaction. During the electrocatalytic reaction, the gas flow rate is controlled at 1-50 mL min -1 .

3. The method for preparing formaldehyde oxime using an electrocatalyst according to claim 1, wherein: The nitrogen source is any one of nitrogen, nitric oxide, nitrogen dioxide, potassium nitrate, potassium nitrite, sodium nitrate and sodium nitrite.

4. The method for preparing formaldehyde oxime using an electrocatalyst according to claim 3, wherein: When the nitrogen source is nitrogen, nitric oxide, or nitrogen dioxide, the electrolyte should be pre-saturated with the gaseous nitrogen source before the electrocatalytic reaction. During the electrocatalytic reaction, the gas flow rate is controlled at 1-50 mL min -1 ; When the nitrogen source is potassium nitrate, potassium nitrite, sodium nitrate or sodium nitrite, the concentration of the nitrogen source in the cathode compartment electrolyte is 0.005-1.0M.

5. The method for preparing formaldehyde oxime using an electrocatalyst according to claim 1, wherein: The molar concentration of the electrolyte is 0.01~2 M.

6. The method for preparing formaldehyde oxime by electrocatalysis according to claim 1, wherein: The anode catalyst is any one of a platinum sheet and nickel foam.

Images