A method for electrosynthesis of cyclohexanone oxime at ampere-level current density

Abstract

The invention discloses a kind of electrosynthesis method of cyclohexanone oxime under ampere-level current density, belongs to the green electrosynthesis field of high-value chemicals, with water as hydrogen source, NO as nitrogen source, cyclohexanone as carbon source, ruthenium-doped silver supported on hydrophobic carbon paper is working electrode, silver / silver chloride is reference electrode, nickel-iron oxide supported on nickel foam is counter electrode, utilizes three-chamber flow reactor, one-step electrosynthesis cyclohexanone oxime at room temperature.The present invention destroys the continuous site of silver by ruthenium doping, suppresses NO-NO coupling, makes NH2OH generated by nitrogen source and hydrogen source be able to desorb rapidly, thus and carbon source cyclohexanone are condensed, accelerate the electrosynthesis rate of cyclohexanone oxime, and suppress side reaction, thus realize the electrosynthesis of cyclohexanone oxime of high faradaic efficiency under ampere-level current density.

Description

Technical Field

[0001] The present invention relates to the field of green electrosynthesis of high-value chemicals, and in particular to a method for electrosynthesis of cyclohexanone oxime at an ampere-level current density. Background Art

[0002] Cyclohexanone oxime is a key precursor for the production of nylon-6, with an annual global demand of approximately 10 million tons and a global market size of approximately US$25 billion. The industrial production of cyclohexanone oxime typically involves a complex two-step process: first, NH₂OH is produced via the Raschig process, and then NH₂OH reacts with cyclohexanone to form cyclohexanone oxime. This two-step process requires explosive hydrogen, strongly acidic conditions, and precious metal catalysts, raising safety and environmental concerns.

[0003] Nitrogen oxides (NO x ) as nitrogen source, and the construction of C-N bonds by mild electrocatalytic methods has become a sustainable strategy for synthesizing organic nitrogen-containing compounds from inorganic nitrogen sources. Recently, researchers have used NO or nitrite (NO, NO2 - ) as nitrogen source and cyclohexanone as carbon source to achieve aqueous electrosynthesis of cyclohexanone oxime. x The spontaneous condensation of NH2OH intermediates generated by electroreduction is the key step in the formation of cyclohexanone oxime. x Reduction is a multi-electron process involving a variety of nitrogen-containing intermediates such as N2O, N2, NH3, etc., which produces a variety of by-products, resulting in a low Faradaic efficiency of cyclohexanone oxime. Furthermore, the existing cyclohexanone oxime electrosynthesis technology is not suitable for large current densities (≥200mAcm – 2 ) will promote competing reactions, especially H2 evolution and NO-NO coupling to form N-2 products, further reducing the Faradaic efficiency. Therefore, the current density of existing cyclohexanone oxime synthesis technology can only reach tens of milliamperes, which is far lower than the at least 200mAcm required for industrial production. – 2 Therefore, developing effective control strategies is of great significance for achieving high Faradaic efficiency electrosynthesis of cyclohexanone oxime at high current density. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems of the prior art and provide a method for electrosynthesizing cyclohexanone oxime at an ampere-level current density.

[0005] The object of the present invention is to achieve the following technical solution: a method for electrosynthesis of cyclohexanone oxime at an ampere-level current density, the method comprising the following steps:

[0006] Build an electrochemical reactor: A three-chamber flow reactor is constructed, including a gas chamber, a cathode chamber, and an anode chamber, with a cation exchange membrane between the cathode and anode chambers. The cathode chamber contains a catholyte solution, and the anode chamber contains an anolyte solution. A ruthenium-doped working electrode is located between the gas and cathode chambers. A counter electrode of nickel iron oxide is located in the anode chamber. A reference electrode of silver / silver chloride is located in the cathode chamber.

[0007] Electrochemical reaction: Nitrogen oxide is introduced into the gas chamber as a nitrogen source, cyclohexanone is added to the cathode chamber as a carbon source, and a hydrogen source is added to the cathode chamber. While the electrolyte circulates in the cathode and anode chambers, constant current electrolysis is performed with a current density of 0.1 to 1 A cm -2 , and then preparing a reaction solution containing cyclohexanone oxime in the cathode chamber.

[0008] In one example, the working electrode is AgRu, and the preparation of the working electrode includes the following sub-steps:

[0009] (1) RuCl3 and allylamine hydrochloride are dissolved in water and mixed uniformly, AgNO3 solution is added dropwise to the mixture, formaldehyde is added, and the resulting solution is mixed uniformly; the molar ratio of RuCl3 to AgNO3 is between 1:49 and 1:4;

[0010] (2) transferring the mixed solution obtained in step (1) into an autoclave, reacting at 175-185° C. for 1-2 hours, cooling, washing, and drying at 45-60° C. to obtain an AgRuCl precursor;

[0011] (3) 2-8 mg of AgRuCl precursor was ultrasonically dispersed in 1-4 ml of ethanol / naphthol mixed solution, and then drop-coated on hydrophobic carbon paper and dried to obtain an AgRuCl electrode; the content of each substance in the ethanol / naphthol mixed solution was 990-3960 μl of ethanol and 10-40 μl of naphthol, and the drop-coating area on the hydrophobic carbon paper was controlled to be 1-1.2 cm 2 Inside;

[0012] (4) AgRuCl electrode was used as the working electrode, Ag / AgCl as the reference electrode, and nickel iron oxide supported on nickel foam as the counter electrode. A voltage of -1.8 V was applied in a flow reactor. The electrolyte was a mixture of 0.9-1.35 mol / L NaClO4 and 0.1-0.15 mol / L NaOH. The AgRu electrode was prepared by electrolysis for 10-15 minutes.

[0013] In one example, the flow rate of the nitrogen source into the gas chamber is 35-45 ml min – 1 .

[0014] In one example, the concentration of the nitrogen source is 10% to 100%.

[0015] In one example, nitrogen oxides are replaced by one or a mixture of sodium nitrite, potassium nitrite, sodium nitrate, potassium nitrate, ammonium nitrate or lithium nitrate as a nitrogen source, which is directly added to the cathode chamber, and the gas chamber is eliminated.

[0016] In one example, the cathode electrolyte solution is an aqueous solution of one or more of sodium hydroxide, potassium hydroxide, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, sodium sulfate, potassium sulfate, and sodium perchlorate, and the anode electrolyte solution is an aqueous solution of one or more of sodium hydroxide, potassium hydroxide, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, sodium sulfate, potassium sulfate, and sodium perchlorate.

[0017] In one example, the cathode electrolyte solution is sodium perchlorate and sodium hydroxide, and the anode electrolyte solution is sodium hydroxide; when the electrolyte concentration of the cathode electrolyte solution is 1 to 1.5 mol / L, the concentration of sodium perchlorate in the cathode electrolyte solution is 0.9 to 1.35 mol / L, and the concentration of sodium hydroxide in the cathode electrolyte solution is 0.1 to 0.15 mol / L; the concentration of sodium hydroxide in the anode electrolyte solution is 1 to 1.5 mol / L.

[0018] In one example, the cathode electrolyte solution is 20-25 mL, the anode electrolyte solution is 20-25 mL, and 2-4 mmol of cyclohexanone is added to the cathode chamber.

[0019] In one example, when the cathode electrolyte solution and the anode electrolyte solution are circulated, the flow rate is controlled at 20-25 ml min – 1 .

[0020] In one example, during constant current electrolysis, the potential is in the range of -1.35 to -10 V, the reaction temperature is 25 to 30° C., and the reaction time is 0.5 to 2 h.

[0021] It should be further explained that the technical features corresponding to the above examples can be combined or replaced with each other to form a new technical solution.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention destroys the continuous sites of silver by ruthenium doping, inhibits NO-NO coupling, and enables the rapid desorption of NH2OH generated by nitrogen source and hydrogen source, thereby condensing with carbon source cyclohexanone, accelerating the electrosynthesis rate of cyclohexanone oxime and inhibiting side reactions, thereby achieving high Faradaic efficiency electrosynthesis of cyclohexanone oxime at ampere-level current density. – 2The cyclohexanone oxime synthesized at a current density of 10.7 mmol h -1 cm – 2 production speed.

[0024] At the same time, compared with the prior art of "directly utilizing cyclohexanone and hydroxylamine for a coupling reaction", the present invention does not require the advance preparation of hydroxylamine, and the conditions for the hydroxylamine generation process are mild, and no hazardous gases such as sulfur dioxide and hydrogen are required. It can be generated and used in situ, and the storage of hydroxylamine is also avoided, thereby realizing a one-step room temperature electrosynthesis of cyclohexanone oxime. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The same reference numerals are used in these drawings to represent the same or similar parts. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application.

[0026] Figure 1 Schematic diagram of a three-chamber flow reactor for electrosynthesis of cyclohexanone oxime using NO as a nitrogen source, provided in an exemplary embodiment of the present invention;

[0027] Figure 2 A schematic diagram of a reaction principle provided in an exemplary embodiment of the present invention;

[0028] Figure 3 Schematic diagram of experimental data of the Faradaic efficiency of cyclohexanone oxime at different NO concentrations and different potentials provided in an exemplary embodiment of the present invention;

[0029] Figure 4 The different NO concentrations and NH4 at different potentials provided in an exemplary embodiment of the present invention + Schematic diagram of Faraday efficiency experimental data;

[0030] Figure 5 Schematic diagram of experimental data of the Faradaic efficiency of N-2 (N2O+N2) products at different NO concentrations and different potentials provided in an exemplary embodiment of the present invention;

[0031] Figure 6 A reaction pathway diagram for the electrosynthesis of cyclohexanone oxime at low NO coverage and high NO coverage provided in an exemplary embodiment of the present invention;

[0032] Figure 7 Figure a is a schematic diagram of a scanning electron microscope (SEM) of an AgRu catalyst provided in an exemplary embodiment of the present invention; Figure 7b, c, and d are schematic transmission electron microscope (TEM) images of an AgRu catalyst provided in an exemplary embodiment of the present invention;

[0033] Figure 8 Schematic diagram of X-ray photoelectron spectroscopy (XPS) of an AgRu catalyst provided in an exemplary embodiment of the present invention;

[0034] Figure 9 This is a stability test diagram of the electrosynthesis of cyclohexanone oxime using an AgRu catalyst provided in an exemplary embodiment of the present invention;

[0035] Figure 10 A schematic diagram of experimental data of FE of cyclohexanone oxime synthesized at different current densities and the potential E corresponding to the current density provided for a preferred example of the present invention;

[0036] Figure 11 A schematic diagram of the production rate of cyclohexanone oxime synthesized at different current densities provided as a preferred example of the present invention;

[0037] Figure 12 A schematic diagram of the nuclear magnetic resonance spectrum of cyclohexanone oxime synthesized as a preferred example of the present invention;

[0038] Figure 13 This is a schematic diagram of experimental data of FE of cyclohexanone oxime synthesized at different current densities and the potential E corresponding to the current density provided for the comparative example of the present invention.

[0039] In the figure: 101 - gas chamber, 102 - cathode chamber, 103 - anode chamber, 104 - cation exchange membrane. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is described clearly and completely below with reference to the accompanying drawings. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0041] In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the directions or positional relationships described in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the use of ordinal numbers (for example, "first and second", "first to fourth", etc.) is for the purpose of distinguishing objects and is not limited to this order, and cannot be understood as indicating or implying relative importance.

[0042] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0043] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] In one example, a method for electrosynthesis of cyclohexanone oxime at an ampere-level current density comprises the following steps:

[0045] S1: Build an electrochemical reactor: Figure 1 The three-chamber flow reactor shown includes a gas chamber 101, a cathode chamber 102 and an anode chamber 103 arranged in sequence, and a cation exchange membrane 104 is provided between the cathode chamber and the anode chamber; optionally, the cation exchange membrane is any one of AMI7001, CMI7000, FAA-3-20, nafionXL, Nafion 117, and in this example it is a Nafion117 proton exchange membrane; a ruthenium-doped working electrode is provided between the gas chamber and the cathode chamber, and in this example the working electrode is AgRu supported on hydrophobic carbon paper; the counter electrode is nickel-iron oxide supported on nickel foam, and is provided in the anode chamber; the reference electrode is silver / silver chloride, and is provided in the cathode chamber; the cathode chamber has a cathode electrolyte solution, and the anode chamber has an anode electrolyte solution.

[0046] S2: Electrochemical reaction: Nitrogen oxide is introduced into the gas chamber as a nitrogen source, in this case NO; a carbon source, cyclohexanone, is added to the cathode chamber, and a hydrogen source, in this case water, is added to the cathode chamber; then, while the electrolyte circulates between the cathode and anode chambers, constant current electrolysis is performed with a current density of 0.1 to 1 Acm -2 , the potential is -1.35~-10V, the reaction temperature is 25~30℃, and the reaction time is 0.5~2h. At this time, the reaction principle is as follows Figure 2 As shown, in the cathode chamber, hydrogen gas or hydrogen ions produced by water electrolysis react with NO diffused into the gas chamber to generate NH2OH, which then condenses with cyclohexanone to generate cyclohexanone oxime; at the same time, in the anode chamber, water molecules are oxidized to generate oxygen and hydrogen ions to maintain the charge balance in the circuit, thereby preparing a reaction solution containing cyclohexanone oxime in the cathode chamber, and obtaining an anode reaction solution in the anode chamber, thereby utilizing a three-chamber flow reactor to achieve the synthesis of cyclohexanone oxime through a green and mild electrocatalytic method.

[0047] It should be noted that if Figure 2 As shown in Figure 2, in the process of electrosynthesis of cyclohexanone oxime using NO and cyclohexanone, the possible competing reactions include hydrogen evolution reaction, NH2OH overhydrogenation to NH3, and NO-NO coupling to generate N-2 (N2O, N2) products. Therefore, metallic silver with a large hydrogen evolution free energy and weak NH2OH adsorption energy should be selected as the catalyst, that is, Ag is used as the working electrode to electrosynthesize cyclohexanone oxime. At this time, the experimental data of the Faradaic efficiency (FE) of the synthesis of cyclohexanone oxime CYC under different NO concentrations and different potentials (the potential E of the Ag / AgCl reference electrode) are shown as follows: Figure 3 As shown, NH4 + The experimental data of Faraday efficiency are as follows Figure 4 As shown in the figure, the experimental data of the Faraday efficiency of N-2 (N2O+N2) products at different NO concentrations and different potentials are as follows: Figure 5 As shown, when the NO concentration is preferably 70%, the Faradaic efficiency of cyclohexanone oxime is higher, but compared with the NO concentration of 100%, the current density of cyclohexanone oxime synthesized at a NO concentration of 70% is still not large enough. Figure 6 As shown, the study of the experimental mechanism shows that low NO coverage (Low coverage) is conducive to the generation of NH3 and H2; high NO coverage (High coverage) is conducive to the generation of cyclohexanone oxime, but at the same time, NO-NO coupling is prone to occur to generate N-2 by-products (N2O, N2). Based on the understanding of the above mechanism, the present invention uses AgRu as the working electrode to electrosynthesize cyclohexanone oxime, destroys the continuous sites of silver by ruthenium doping, and inhibits NO-NO coupling under high NO coverage. At the same time, Ag has a large hydrogen evolution free energy and can inhibit H2 precipitation, thereby achieving high Faraday efficiency electrosynthesis of cyclohexanone oxime at ampere-level current density. In the method of the present invention, the concentration of NO is 10% to 100%, preferably 100%. Among them, the scanning electron microscope photo of the AgRu catalyst is shown in FIG. Figure 7 As shown in a, the transmission electron microscope photo of AgRu catalyst is as follows Figure 7 As shown in b, c, and d, the X-ray photoelectron spectroscopy images of the AgRu catalyst are as follows Figure 8 As shown, Figure 8 The horizontal axis is the binding energy, and the vertical axis is the intensity. The stability test of the AgRu catalyst electrosynthesis of cyclohexanone oxime is as follows: Figure 9 As shown, cyclohexanone oxime was synthesized using AgRu catalyst as the working electrode, which has strong stability.

[0048] Compared with the prior art of "directly utilizing cyclohexanone and hydroxylamine for direct coupling reaction", the method of the present invention does not require the preparation of hydroxylamine in advance, and the conditions for the hydroxylamine generation process are mild, and no hazardous gases such as sulfur dioxide and hydrogen are required. It can be generated and used in situ, and the storage of hydroxylamine is avoided, and the one-step conversion from NO to cyclohexanone oxime can be achieved. Compared with the existing cyclohexanone oxime electrosynthesis technology, the method of the present invention achieves high Faradaic efficiency cyclohexanone oxime synthesis at a high current density, and at 1Acm –2 The cyclohexanone oxime synthesized at a current density of 10.7 mmol h -1 cm -2 production speed.

[0049] In one example, the flow rate of nitrogen oxides into the gas chamber is 35-45 ml min – 1 .

[0050] In one example, nitrogen oxides are replaced by one or a mixture of sodium nitrite, potassium nitrite, sodium nitrate, potassium nitrate, ammonium nitrate or lithium nitrate. In this case, the nitrogen source is directly added to the cathode chamber for electrochemical reaction, the gas chamber of the reactor is correspondingly eliminated, and other structures remain unchanged.

[0051] In one example, the cathode electrolyte solution is an aqueous solution of one or more of sodium hydroxide, potassium hydroxide, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, sodium sulfate, potassium sulfate, and sodium perchlorate, and the anode electrolyte solution is an aqueous solution of one or more of sodium hydroxide, potassium hydroxide, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, sodium sulfate, potassium sulfate, and sodium perchlorate. In this example, the cathode electrolyte solution is sodium perchlorate and sodium hydroxide, and the anode electrolyte solution is sodium hydroxide. Preferably, when the electrolyte concentration of the cathode electrolyte solution is 1 mol / L, the concentration of sodium perchlorate in the cathode electrolyte solution is 0.9 mol / L, the concentration of sodium hydroxide in the cathode electrolyte solution is 0.1 mol / L; and the concentration of sodium hydroxide in the anode electrolyte solution is 1 mol / L. Preferably, the cathode electrolyte solution is 25 mL, the anode electrolyte solution is 25 mL, and the amount of cyclohexanone added to the cathode chamber is 4 mmol.

[0052] In one example, the cathode electrolyte solution and the anode electrolyte solution were circulated using a peristaltic pump with a flow rate controlled at 20-25 ml min – 1 .

[0053] In one example, before constructing the electrochemical reactor, the preparation of the working electrode AgRu includes the following sub-steps:

[0054] (1) RuCl3 and allylamine hydrochloride were dissolved in water and mixed uniformly under constant stirring. AgNO3 solution was added dropwise to the mixture, and then formaldehyde was added. The resulting solution was mixed for 10 minutes, wherein the molar ratio of RuCl3 to AgNO3 was 1:9;

[0055] (2) The mixed solution obtained in step (1) was transferred to an autoclave, reacted at 180° C. for 1 hour, cooled, washed with deionized water and ethanol, and dried at 45° C. to obtain an AgRuCl precursor;

[0056] (3) 2 mg of AgRuCl precursor was ultrasonically dispersed in 1 ml of ethanol / naphthol mixed solution, and then drop-coated on hydrophobic carbon paper and dried to obtain an AgRuCl electrode; wherein, the content of each substance in the ethanol / naphthol mixed solution was 990 μl of ethanol and 10 μl of naphthol, and the drop-coating area on the hydrophobic carbon paper was controlled to be 1 cm 2 Inside;

[0057] (4) The AgRuCl electrode was used as the working electrode, Ag / AgCl as the reference electrode, and nickel iron oxide supported on nickel foam as the counter electrode. A voltage of –1.8 V was applied in a flow reactor. The electrolyte was a mixture of 0.9 mol / L NaClO4 and 0.1 mol / L NaOH. The electrolysis was carried out for about 10 minutes to prepare the AgRu working electrode.

[0058] Based on the above examples, a preferred example of the present invention was obtained and carried out at room temperature (room temperature, 25° C.):

[0059] (1) First, a three-chamber flow reactor was used, with AgRu supported on hydrophobic carbon paper as the working electrode, silver / silver chloride as the reference electrode, and nickel iron oxide supported on nickel foam as the counter electrode. The cathode electrolyte solution in the cathode chamber was 25 mL of 0.1 M NaOH + 0.9 M NaClO4 (pH 12.5) solution, and the anolyte solution in the anode chamber was 25 mL of 1 M NaOH (pH 13.6). Then, 4 mmol (392.6 mg) of cyclohexanone was added to the cathode chamber, and NO was introduced into the gas chamber. Then, electrolysis was performed with a constant current of 1 A cm -2 , the reaction coulomb volume is set to 200C, a cathode reaction solution containing cyclohexanone oxime is obtained in the cathode chamber, and an anode reaction solution is obtained in the anode chamber, such as Figure 10 As shown, at a current density of 1 A cm –2 Under the condition of NO concentration of 100%, the Faradaic efficiency of cyclohexanone oxime is as high as 86%. Figure 10The Faradaic efficiency of cyclohexanone oxime CYC synthesized at different current densities and the potential E compared to the Ag / AgCl reference electrode are shown in this step. In the figure, the horizontal axis j represents the current density, and the vertical axis FE% on the left represents the Faradaic efficiency of cyclohexanone oxime (corresponding to Figure 10 The right vertical axis E represents the potential corresponding to the current density (corresponding to Figure 10 ).

[0060] (2) Stop the introduction of NO, add maleic acid as a quantitative internal standard to the system, take 0.5 mL of the reaction solution and add 100 μL of deuterated water for qualitative and quantitative analysis using nuclear magnetic resonance.

[0061] The Faradaic efficiency FE of cyclohexanone oxime in the embodiment is calculated according to the following formula:

[0062] Cyclohexanone oxime Faraday efficiency = number of electrons transferred × number of moles of product generated × Faraday constant / charge × 100%;

[0063] Furthermore, the production rate of cyclohexanone oxime synthesized under different current densities is as follows: Figure 11 As shown, the method of the present invention can be used at an ampere current density (0.1-1Acm -2 ) to achieve high Faradaic efficiency electrosynthesis of cyclohexanone oxime, preferably with a current density of 1 Acm -2 .in addition, Figure 12 The nuclear magnetic resonance spectrum of cyclohexanone oxime synthesized in this preferred exemplary embodiment is shown. The peak shifted at 5.97 ppm is the peak of maleic acid, the internal standard added for quantification. The peak positions corresponding to the hydrogen atoms of cyclohexanone and cyclohexanone oxime are marked with boxes and dots of the same color. For example, the peaks corresponding to green, yellow, and red are cyclohexanone peaks, while the peaks corresponding to blue, purple, and red are cyclohexanone peaks. The overlapping red peaks are due to the fact that under the experimental conditions, the two hydrogen atoms of cyclohexanone and cyclohexanone oxime have overlapping peak positions in the nuclear magnetic resonance spectrum. Therefore, the Faradaic efficiency of cyclohexanone oxime is calculated by integrating the peaks corresponding to the blue and purple peaks.

[0064] To further demonstrate the high Faradaic efficiency of the electrosynthesis of cyclohexanone oxime by the method of the present invention, a comparative example of the preferred example is given. In this comparative example, only the working electrode is replaced with Ag synthesized by the same method, and the other conditions remain the same as the preferred example. The experimental data of FE of cyclohexanone oxime synthesized at different current densities and the potential E corresponding to the current density are as follows: Figure 13As shown, it can be seen that the Faradaic efficiency of oxime compounds (Oxime) is low. During the electrosynthesis process, relatively less charge is used to generate the target product cyclohexanone oxime, and the Faradaic efficiency of NO-NO coupling to generate N-2 products (N2, N2O) is significantly improved. This further proves that the present invention destroys the continuous sites of silver by ruthenium doping, thereby inhibiting NO-NO coupling, thereby achieving high Faradaic efficiency electrosynthesis of cyclohexanone oxime at ampere-level current density, and is expected to realize industrial mass production of cyclohexanone oxime, which has broad application prospects.

[0065] The above specific implementation methods are detailed descriptions of the present invention. It cannot be considered that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions and substitutions without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for electrosynthesis of cyclohexanone oxime at an ampere-level current density, characterized in that: The following steps are involved: Build an electrochemical reactor: A three-chamber flow reactor is constructed, including a gas chamber, a cathode chamber, and an anode chamber, with a cation exchange membrane between the cathode and anode chambers. The cathode chamber contains a catholyte solution, and the anode chamber contains an anolyte solution. A ruthenium-doped working electrode is located between the gas and cathode chambers. A counter electrode of nickel iron oxide is located in the anode chamber. A reference electrode of silver / silver chloride is located in the cathode chamber. Electrochemical reaction: Nitrogen oxide is introduced into the gas chamber as a nitrogen source, cyclohexanone is added to the cathode chamber as a carbon source, and a hydrogen source is added to the cathode chamber. While the electrolyte circulates in the cathode and anode chambers, constant current electrolysis is performed with a current density of 0.1 to 1 Acm -2 , and then preparing a reaction solution containing cyclohexanone oxime in the cathode chamber; The working electrode is AgRu, and the preparation of the working electrode includes the following sub-steps: (1) RuCl3 and allylamine hydrochloride are dissolved in water and mixed uniformly, AgNO3 solution is added dropwise to the mixture, formaldehyde is added, and the resulting solution is mixed uniformly; the molar ratio of RuCl3 to AgNO3 is between 1:49 and 1:4; (2) transferring the mixed solution obtained in step (1) into an autoclave, reacting at 175-185° C. for 1-2 hours, cooling, washing, and drying at 45-60° C. to obtain an AgRuCl precursor; (3) 2-8 mg of AgRuCl precursor was ultrasonically dispersed in 1-4 ml of ethanol / naphthol mixed solution, and then drop-coated on hydrophobic carbon paper and dried to obtain an AgRuCl electrode; the content of each substance in the ethanol / naphthol mixed solution was 990-3960 μl of ethanol and 10-40 μl of naphthol, and the drop-coating area on the hydrophobic carbon paper was controlled to be 1-1.2 cm 2 Inside; (4) AgRuCl electrode was used as the working electrode, Ag / AgCl as the reference electrode, and nickel iron oxide supported on nickel foam as the counter electrode. A voltage of -1.8 V was applied in a flow reactor. The electrolyte was a mixture of 0.9-1.35 mol / L NaClO4 and 0.1-0.15 mol / L NaOH. The AgRu electrode was prepared by electrolysis for 10-15 minutes.

2. The method for electrosynthesis of cyclohexanone oxime at an ampere-level current density according to claim 1, wherein: The flow rate of nitrogen oxides into the gas chamber is 35-45 ml min –1 .

3. The method for electrosynthesis of cyclohexanone oxime at an ampere-level current density according to claim 1, wherein: The concentration of nitrogen oxides introduced into the gas chamber is 10% to 100%.

4. The method for electrosynthesis of cyclohexanone oxime at an ampere-level current density according to claim 1, wherein: The nitrogen oxides are replaced by one or a mixture of sodium nitrite, potassium nitrite, sodium nitrate, potassium nitrate, ammonium nitrate or lithium nitrate, which are directly added into the cathode chamber, and the gas chamber is eliminated.

5. The method for electrosynthesis of cyclohexanone oxime at an ampere-level current density according to claim 1, wherein: The cathode electrolyte solution is an aqueous solution of one or more of sodium hydroxide, potassium hydroxide, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, sodium sulfate, potassium sulfate, and sodium perchlorate; the anode electrolyte solution is an aqueous solution of one or more of sodium hydroxide, potassium hydroxide, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, sodium sulfate, potassium sulfate, and sodium perchlorate.

6. The method for electrosynthesis of cyclohexanone oxime at an ampere-level current density according to claim 1 or 5, characterized in that: The cathode electrolyte solution is sodium perchlorate and sodium hydroxide, and the anode electrolyte solution is sodium hydroxide; when the electrolyte concentration of the cathode electrolyte solution is 1-1.5 mol / L, the concentration of sodium perchlorate in the cathode electrolyte solution is 0.9-1.35 mol / L, and the concentration of sodium hydroxide in the cathode electrolyte solution is 0.1-0.15 mol / L; the concentration of sodium hydroxide in the anode electrolyte solution is 1-1.5 mol / L.

7. The method for electrosynthesis of cyclohexanone oxime at an ampere-level current density according to claim 1, wherein: The cathode electrolyte solution is 20-25 mL, the anode electrolyte solution is 20-25 mL; and 2-4 mmol of cyclohexanone is added to the cathode chamber.

8. The method for electrosynthesis of cyclohexanone oxime at an ampere-level current density according to claim 1, wherein: When the cathode electrolyte solution and the anode electrolyte solution are circulated, the flow rate is controlled at 20-25 ml min –1 .

9. The method for electrosynthesis of cyclohexanone oxime at an ampere-level current density according to claim 1, wherein: During constant current electrolysis, the potential is in the range of -1.35 to -10 V, the reaction temperature is 25 to 30°C, and the reaction time is 0.5 to 2 h.

Images