Preparation method and application of nitrogen-doped carbon composite material

Abstract

The present invention discloses a preparation method and application of a nitrogen-doped carbon composite material. The preparation method of the material of the present invention is that a nitrogen source and a carbon source sugar compound are dispersed in ethanol and water, and then reacted during drying in an oven, while removing water and ethanol, cooling, cleaning, drying, and calcining and carbonizing under an N2 atmosphere to complete the preparation. The main component of the catalyst of the present invention is porous carbon, and the surface of the nitrogen-doped carbon composite material has a rich pore structure. Nitrogen doping can improve the electrical conductivity and wettability of the composite material to the electrolyte. The raw materials of the present invention are easily available and low in price, the preparation process is simple, the energy consumption is low, and it is suitable for industrial production. The prepared nitrogen-doped carbon composite material has a special structure and distinct morphological characteristics, and exhibits good performance when used as a catalyst for electrocatalytic production of peracetic acid.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic material preparation, and in particular relates to a preparation method and application of a nitrogen-doped carbon composite material. Background Art

[0002] Peracetic acid is an organic peroxide widely used in environmental protection, biopharmaceuticals, and industrial production, such as wastewater treatment and the synthesis of pharmaceutical intermediates. Compared to traditional bleaches and disinfectants, it offers superior environmental performance, with its primary decomposition products being water and carbon dioxide, resulting in minimal environmental impact. It effectively degrades organic pollutants, oxidizes harmful substances in wastewater, and improves water purification.

[0003] Currently, the production of peracetic acid primarily relies on the ethylene oxide process and direct synthesis. However, these methods typically require high temperature and high pressure conditions, are subject to challenges such as intense competition from side reactions, and exhibit low yields. With advancements in science and technology and growing environmental awareness, industrial production processes are increasingly focused on improving environmental technologies, including wastewater treatment and energy utilization.

[0004] Electrocatalytic production of peracetic acid has attracted widespread attention as a more environmentally friendly, safe, low-cost, and on-site production method. Oxygen is reduced to hydrogen peroxide via an electrochemical cathode reduction reaction, and acetic acid is oxidized to peracetic acid in situ. However, key scientific and technological limitations lie in its low activity, slow reaction rate, and poor stability. Therefore, developing highly selective, stable, and low-cost catalysts for electrocatalytic production of peracetic acid presents a significant challenge. Summary of the Invention

[0005] In view of the deficiencies of the above-mentioned prior art, the object of the present invention is to provide a preparation method and application of a nitrogen-doped carbon composite material. The present invention adopts a simple calcination method to synthesize a nitrogen-doped carbon composite material electrocatalyst, which is simple to prepare, has efficient reaction, has high yield and high stability in the electrocatalytic production of peracetic acid, and has good industrial application prospects.

[0006] The technical solution adopted in the present invention is as follows:

[0007] A preparation method and application of a nitrogen-doped carbon composite material, comprising the following steps:

[0008] 1) Dispersing the nitrogen source and carbon source in a mixed solution of ethanol and water, and sonicating until all the solids are dissolved;

[0009] 2) transferring the dispersed liquid from step 1) to a watch glass, placing the watch glass in an oven, and drying it in the oven to remove water and ethanol while reacting;

[0010] 3) After the reaction is completed, the system of step 2) is naturally cooled to room temperature, the solid product is separated, washed to remove the residue, and dried. The dried product is placed in a tubular furnace and calcined and carbonized under a N2 atmosphere to obtain the nitrogen-doped carbon composite material.

[0011] Furthermore, the carbon source in step 1) is at least one of glucose, fructose, sucrose, etc.

[0012] Furthermore, the nitrogen source in step 1) is at least one of hydroxylamine hydrochloride and glucosamine hydrochloride.

[0013] Furthermore, the molar ratio of the nitrogen source to the carbon source in step 1) is 0.3-1:1, preferably 0.5:1.

[0014] Furthermore, the drying temperature in step 1) is 50-120° C.; and the drying time is 12-24 hours, preferably 14 hours.

[0015] A nitrogen-doped carbon composite material is used in the electrocatalytic production of peracetic acid. The electrocatalytic reaction process is carried out in a gas diffusion flow cell, including an anode chamber and a cathode chamber. The anode chamber and the cathode chamber are separated by a proton exchange membrane. The anode uses a titanium mesh electrode, and the cathode uses a working electrode (the working electrode is prepared by coating the nitrogen-doped carbon composite material on a side of the gas diffusion electrode having micropores). The cathode divides the cathode chamber into two small chambers on the left and right. The small chamber close to the proton exchange membrane is recorded as the cathode liquid chamber, and the other small chamber is the cathode air chamber. The cathode working electrode has a microporous side facing the cathode liquid cavity; the anode and cathode are respectively connected to the positive electrode and negative electrode of a constant current meter via wires; a Na2SO4 solution is used as the anode electrolyte, acetic acid is used as the reaction substrate in the cathode liquid cavity, and an aqueous solution of the reaction substrate is used as the cathode electrolyte; air or oxygen is introduced into the cathode air chamber, the constant current meter is energized to perform an electrocatalytic reaction, and the air or oxygen diffuses to the surface of the cathode gas diffusion electrode to contact the nitrogen-doped carbon composite material catalyst, and a reaction occurs at the cathode under the action of the catalyst to generate peracetic acid.

[0016] The preparation process of the working electrode is as follows: a nitrogen-doped carbon composite electrocatalyst is mixed with a 5% mass concentration of Nafion solution and anhydrous ethanol, the volume ratio of Nafion solution to anhydrous ethanol is 0.1-3:9, preferably 0.5-1:9, the concentration of the electrocatalyst after mixing is 0.1-1 mg / mL, and after ultrasonic dispersion, it is sprayed on the side surface of a commercial gas diffusion electrode (YSL-30T) with micropores, and the coating amount of the electrocatalyst on the side surface of the gas diffusion electrode is 0.05-0.2 mg / cm 2 , dried, prepared into a working electrode, and assembled in a gas diffusion flow cell for electrocatalytic determination.

[0017] Furthermore, the concentration of the Na2SO4 aqueous solution is 0.05-0.2 mol / L, preferably 0.1 mol / L.

[0018] Furthermore, the device for the electrocatalytic reaction also includes an anode liquid storage tank, a cathode liquid storage tank, a circulation pump 1 and a circulation pump 2. When the electrocatalytic reaction is carried out, the circulation pump 1 is started to allow the cathode electrolyte to circulate between the cathode liquid storage tank and the cathode liquid chamber; at the same time, the circulation pump 2 is started to allow the anode electrolyte to circulate between the anode chamber and the anode liquid storage tank.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1) The raw materials are easily available, the cost is low, there is no waste acid or waste liquid, the preparation steps are simple, and the repeatability is good;

[0021] 2) The reaction conditions are relatively mild, and the preparation process has few safety hazards;

[0022] 3) The nitrogen-doped carbon composite material prepared using the above-mentioned technology incorporates nitrogen onto a carbon substrate through simple calcination. This invention modifies the electrochemical state and morphological structure of the carbon through nitrogen doping, enhancing the yield and efficiency of the carbon catalyst for peracetic acid. Furthermore, the catalyst exhibits excellent electrocatalytic stability, demonstrating excellent potential for practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1a This is one of the SEM images of the nitrogen-doped carbon composite material described in Example 5;

[0024] Figure 1b This is the second SEM image of the nitrogen-doped carbon composite material described in Example 5;

[0025] Figure 1c This is the third SEM image of the nitrogen-doped carbon composite material described in Example 5;

[0026] Figure 2 It is a schematic diagram of the explosion structure of the gas diffusion flow cell of this application. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0028] Example 1: A method for preparing a nitrogen-doped carbon composite material, comprising the following steps:

[0029] 1) Dissolve 180 mg of anhydrous glucose and 60 mg of hydroxylamine hydrochloride in 200 ml of a mixture of deionized water and ethanol (volume ratio of ethanol to water: 1:1). Ultrasonicate until uniformly distributed and stir at room temperature for 15 min.

[0030] 2) Transfer the dispersed liquid to a watch glass, and then place the watch glass in an oven at 100°C to dry it to remove water and ethanol;

[0031] 3) The system of step 2) is naturally cooled to room temperature, cleaned to remove residues, and dried. The dried product is placed in a tube furnace and calcined and carbonized under a N2 atmosphere at a calcination temperature of 300°C. The preparation is completed.

[0032] Example 2: A method for preparing a nitrogen-doped carbon composite material comprises the following steps:

[0033] 1) Dissolve 180 mg of anhydrous glucose and 60 mg of hydroxylamine hydrochloride in 200 ml of a mixture of deionized water and ethanol (volume ratio of ethanol to water: 1:1). Ultrasonicate until uniformly distributed and stir at room temperature for 15 min.

[0034] 2) Transfer the dispersed liquid to a watch glass, and then place the watch glass in an oven at 100°C to dry it to remove water and ethanol;

[0035] 3) The system of step 2) is naturally cooled to room temperature, cleaned to remove residues, and dried. The dried product is placed in a tube furnace and calcined and carbonized under a N2 atmosphere at a calcination temperature of 400°C. The preparation is completed.

[0036] Example 3: A method for preparing a nitrogen-doped carbon composite material, comprising the following steps:

[0037] 1) Dissolve 180 mg of anhydrous glucose and 60 mg of hydroxylamine hydrochloride in 200 ml of a mixture of deionized water and ethanol (volume ratio of ethanol to water: 1:1). Ultrasonicate until uniformly distributed and stir at room temperature for 15 min.

[0038] 2) Transfer the dispersed liquid to a watch glass, and then place the watch glass in an oven at 100°C to dry it to remove water and ethanol;

[0039] 3) The system of step 2) is naturally cooled to room temperature, cleaned to remove residues, and dried. The dried product is placed in a tube furnace and calcined and carbonized under a N2 atmosphere at a calcination temperature of 500°C. The preparation is completed.

[0040] Example 4: A method for preparing a nitrogen-doped carbon composite material, comprising the following steps:

[0041] 1) Dissolve 180 mg of anhydrous glucose and 60 mg of hydroxylamine hydrochloride in 200 ml of a mixture of deionized water and ethanol (volume ratio of ethanol to water: 1:1). Ultrasonicate until uniformly distributed and stir at room temperature for 15 min.

[0042] 2) Transfer the dispersed liquid to a watch glass, and then place the watch glass in an oven at 100°C to dry it to remove water and ethanol;

[0043] 3) The system of step 2) is naturally cooled to room temperature, cleaned to remove residues, and dried. The dried product is placed in a tube furnace and calcined and carbonized under a N2 atmosphere at a calcination temperature of 600°C. The preparation is completed.

[0044] Example 5: A method for preparing a nitrogen-doped carbon composite material, comprising the following steps:

[0045] 1) Dissolve 180 mg of anhydrous glucose and 60 mg of hydroxylamine hydrochloride in 200 ml of a mixture of deionized water and ethanol (volume ratio of ethanol to water: 1:1). Ultrasonicate until uniformly distributed and stir at room temperature for 15 min.

[0046] 2) Transfer the dispersed liquid to a watch glass, and then place the watch glass in an oven at 100°C to dry it to remove water and ethanol;

[0047] 3) The system of step 2) is naturally cooled to room temperature, washed to remove residues, dried, and the dried product is placed in a tube furnace and calcined and carbonized under a N2 atmosphere at a calcination temperature of 700°C. The preparation is completed. Figure 1a 、 Figure 1b and Figure 1c , it can be seen that the material is a porous carbon structure.

[0048] Example 6: A method for preparing a nitrogen-doped carbon composite material, comprising the following steps:

[0049] 1) Dissolve 180 mg of anhydrous glucose and 60 mg of hydroxylamine hydrochloride in 200 ml of a mixture of deionized water and ethanol (volume ratio of ethanol to water: 1:1). Ultrasonicate until uniformly distributed and stir at room temperature for 15 min.

[0050] 2) Transfer the dispersed liquid to a watch glass, and then place the watch glass in an oven at 100°C to dry it to remove water and ethanol;

[0051] 3) The system of step 2) is naturally cooled to room temperature, cleaned to remove residues, and dried. The dried product is placed in a tube furnace and calcined and carbonized under a N2 atmosphere at a calcination temperature of 800°C. The preparation is completed.

[0052] Example 7: A method for preparing a nitrogen-doped carbon composite material, comprising the following steps:

[0053] 1) Dissolve 180 mg of anhydrous glucose and 60 mg of hydroxylamine hydrochloride in 200 ml of a mixture of deionized water and ethanol (volume ratio of ethanol to water: 1:1). Ultrasonicate until uniformly distributed and stir at room temperature for 15 min.

[0054] 2) Transfer the dispersed liquid to a watch glass, and then place the watch glass in an oven at 100°C to dry it to remove water and ethanol;

[0055] 3) After the reaction is completed, the system of step 2) is naturally cooled to room temperature, cleaned to remove residues, and dried. The dried product is placed in a tube furnace and calcined and carbonized under a N2 atmosphere at a calcination temperature of 900°C. The preparation is completed.

[0056] Based on the conditions listed above, Examples 1-7 mainly explored the effect of calcination temperature on the overall performance of the catalyst. The specific electrocatalytic peracetic acid production performance test is described in the application examples.

[0057] Example 8: A method for preparing a nitrogen-doped carbon composite material, comprising the following steps:

[0058] 1) Dissolve 180 mg of anhydrous glucose and 60 mg of hydroxylamine hydrochloride in 200 ml of a mixture of deionized water and ethanol (volume ratio of ethanol to water: 1:1). Ultrasonicate until uniformly distributed and stir at room temperature for 15 min.

[0059] 2) The dispersed liquid is transferred to a crucible, placed in a tube furnace, and calcined and carbonized under a N2 atmosphere at a calcination temperature of 700°C. The preparation is then completed.

[0060] According to the conditions listed above, Example 8 mainly explores the effect of pyrolysis conditions on the overall performance of the catalyst. The specific electrocatalytic peracetic acid production performance test is described in the application examples.

[0061] Comparative Example 1: A method for preparing a nitrogen-doped carbon composite material comprises the following steps:

[0062] 1) Dissolve 180 mg of resorcinol and 60 mg of hydroxylamine hydrochloride in 200 ml of a mixture of deionized water and ethanol (volume ratio of ethanol to water: 1:1). Ultrasonicate until uniformly distributed and stir at room temperature for 15 min.

[0063] 2) Transfer the dispersed liquid to a watch glass, and then place the watch glass in an oven at 100°C to dry it to remove water and ethanol;

[0064] 3) After the reaction is completed, the system of step 2) is naturally cooled to room temperature, cleaned to remove residues, and dried. The dried product is placed in a tube furnace and calcined and carbonized under a N2 atmosphere at a calcination temperature of 700°C. The preparation is completed.

[0065] According to the conditions listed above, Comparative Example 1 mainly explores the effects of different carbon sources on the overall performance of the catalyst, and the specific electrocatalytic peracetic acid production performance test is described in the application example.

[0066] Comparative Example 2: A method for preparing a nitrogen-doped carbon composite material comprises the following steps:

[0067] 1) Dissolve 180 mg of anhydrous glucose and 60 mg of urea in 200 ml of a mixture of deionized water and ethanol (volume ratio of ethanol to water: 1:1). Ultrasonicate until uniformly distributed and stir at room temperature for 15 min.

[0068] 2) Transfer the dispersed liquid to a watch glass, and then place the watch glass in an oven at 100°C to dry it to remove water and ethanol;

[0069] 3) After the reaction is completed, the system of step 2) is naturally cooled to room temperature, cleaned to remove residues, dried, and the dried product is placed in a tube furnace for calcination and carbonization. The calcination temperature is 700°C

[0070] According to the conditions listed above, Comparative Example 2 mainly explores the effects of different nitrogen sources on the overall performance of the catalyst. The specific electrocatalytic peracetic acid production performance test is described in the application example.

[0071] Application Example 1: Performance test steps of a nitrogen-doped carbon composite material for producing peracetic acid by oxygen reduction:

[0072] 1) Place 1 mg of the electrocatalyst in a 10 ml centrifuge tube, add 500 μL of 5% Nafion solution and 4500 μL of alcohol, mix, and ultrasonicate for 25 minutes to ensure uniform dispersion.

[0073] 2) Take the suspension after ultrasonic treatment and spray it evenly on a 3×3 cm 2 A gas diffusion electrode (commercial gas diffusion electrode YSL-30T) with micropores on one side was dried, prepared as a working electrode, and assembled in a gas diffusion flow cell for yield measurement.

[0074] The gas diffusion flow cell includes an anode chamber and a cathode chamber, which are separated by a proton exchange membrane. The anode uses a titanium mesh, and the cathode uses the working electrode. The cathode divides the cathode chamber into two small chambers on the left and right. The small chamber close to the proton exchange membrane is recorded as the cathode liquid chamber, and the other small chamber is the cathode air chamber. The anode and cathode are respectively connected to a constant current meter through wires.

[0075] The exploded structure diagram of the gas diffusion flow cell in this application is as follows Figure 2As shown, the cathode and anode chambers are separated by a proton exchange membrane, including an end plate 1, a stainless steel conductive plate 2, a cathode gas collector 3, a cathode gas diffusion electrode 4, a cathode flow cell 5, a proton exchange membrane 6, an anode electrode 7, an anode flow cell 8 and an end plate 1 arranged from left to right. Fluororubber gaskets can be clamped between two adjacent module plates for sealing. All these modules can be assembled and fixed with bolts to form a stacked structure as a whole.

[0076] Among them, a hollow hole is set in the center of the anode electrode 7, an air inlet and an air outlet are respectively set at both ends of the cathode gas collector 3, and a liquid inlet and an outlet are respectively provided at both ends of the cathode flow pool 5 and the anode flow pool 8, which are connected to the cathode and anode liquid storage tanks through hoses to form a loop; a proton exchange membrane 6 is provided between the cathode flow pool 5 and the anode flow pool 8, and its area is larger than the area of ​​the hollow area in the center of the cathode and anode flow pools.

[0077] comparison Figure 2 , the right side of the gas diffusion electrode 4 is coated with a catalyst.

[0078] 3) Commercial 3×3cm 2 The titanium mesh was used as the anode electrode, the anolyte was 500 mL of a 0.1 mol / L Na2SO4 aqueous solution, the catholyte was 500 mL of a 5 mol / L CH3COOH aqueous solution, and the air flow rate into the cathode gas collector 3 was 10 mL / min. The cathode and anode electrodes were connected to the negative and positive poles of a constant current meter, respectively. The electrocatalytic reaction was carried out at 90 mA for 1 hour, and then the concentration of peracetic acid produced in the catholyte was detected.

[0079] According to the experimental method of Example 1, the electrocatalysts prepared in Examples 1-8 and Comparative Examples 1-2 were tested respectively. The experimental results are shown in Table 1.

[0080] Table 1 Concentrations of different electrocatalysts tested

[0081] Catalyst Grouping Cathode peracetic acid concentration (ppm) Example 1 203 Example 2 267 Example 3 296 Example 4 368 Example 5 415 Example 6 395 Example 7 325 Example 8 203 Comparative Example 1 10 Comparative Example 2 180 Control 1: Carbon black 150 Control 2: Carbon nanotubes 136 Control 3: Pt carbon catalyst 98

[0082] In addition, referring to Table 1, commercial carbon black, carbon nanotubes or Pt carbon catalyst (Pt loading 5%) are also used as control catalysts. The nitrogen-doped carbon composite material is far superior to the commercial carbon-based catalyst in the electrocatalytic production of peracetic acid.

[0083] In actual industrial applications, long-term stability is also a key indicator of electrocatalyst performance. The electrocatalyst prepared in Example 5 was tested using the same experimental method as in Example 1. After each one-hour electrocatalytic run, the catholyte was replaced and the next batch of electrocatalytic experiments was performed. Following this experimental procedure, after the 100th cycle, the peracetic acid concentration in the catholyte remained around 400 ppm, and it dropped to 200 ppm after approximately 105 cycles.

Claims

1. Application of a nitrogen-doped carbon composite material in electrocatalytic production of peracetic acid, characterized in that Acetic acid is used as the reaction substrate in the cathode liquid chamber of the electrocatalysis; The nitrogen-doped carbon composite material is prepared by the following method: 1) Dispersing a nitrogen source and a carbon source in a mixed solution of ethanol and water, and sonicating until all solids are dissolved, wherein the carbon source is glucose and the nitrogen source is hydroxylamine hydrochloride; 2) Transfer the dispersed liquid from step 1) to a watch glass, which is then placed in an oven for drying. During the drying process, the reaction proceeds while removing water and ethanol. 3) After the reaction is completed, the system of step 2) is naturally cooled to room temperature, cleaned to remove residues, and dried. The dried product is placed in a tubular furnace and calcined and carbonized under a N2 atmosphere to obtain the nitrogen-doped carbon composite material.

2. The use according to claim 1, characterized in that In step 1), the molar ratio of the nitrogen source to the carbon source is 0.3-1:

1.

3. The use according to claim 2, characterized in that In step 1), the molar ratio of the nitrogen source to the carbon source is 0.5-1:

1.

4. The use according to claim 1, characterized in that The drying temperature in step 2) is 50-120°C and the drying time is 12-24 hours.

5. The use according to claim 4, characterized in that The drying temperature in step 2) is 90-100° C. and the drying time is 14 h.

6. The use according to claim 1, characterized in that The nitrogen-doped carbon composite material is coated on one side of a gas diffusion electrode having micropores to prepare a working electrode; the electrocatalytic reaction process is carried out in a gas diffusion flow cell, which includes an anode chamber and a cathode chamber, wherein the anode chamber and the cathode chamber are separated by a proton exchange membrane, the anode is a titanium mesh electrode, the cathode is the working electrode, and the cathode divides the cathode chamber into two small chambers on the left and right, the small chamber close to the proton exchange membrane is recorded as the cathode liquid chamber, and the other small chamber is the cathode air chamber, and the side of the cathode working electrode having micropores is arranged facing the cathode liquid chamber; the anode and cathode are respectively connected to a constant current meter via wires; The anode electrolyte adopts a Na2SO4 aqueous solution, the cathode liquid cavity adopts acetic acid as a reaction substrate, and the aqueous solution of the reaction substrate is adopted as the cathode electrolyte. Air or oxygen is introduced into the cathode air chamber, and a constant current meter is energized to perform an electrocatalytic reaction. The air or oxygen diffuses to the surface of the cathode gas diffusion electrode and contacts the nitrogen-doped carbon composite material catalyst. Under the action of the catalyst, a reaction occurs at the cathode to generate peracetic acid.

7. The use according to claim 6, characterized in that The concentration of Na2SO4 aqueous solution is 0.05-0.2 mol / L; the coating amount of catalyst on the side of the gas diffusion electrode is 0.05-0.2 mg / cm 2 .

8. The use according to claim 7, characterized in that The concentration of Na2SO4 aqueous solution is 0.1 mol / L.

9. The use according to claim 6, characterized in that The device for the electrocatalytic reaction also includes an anode liquid storage tank, a cathode liquid storage tank, a circulation pump 1 and a circulation pump 2. When the electrocatalytic reaction is carried out, the circulation pump 1 is started to allow the cathode electrolyte to circulate between the cathode liquid storage tank and the cathode liquid cavity; at the same time, the circulation pump 2 is started to allow the anode electrolyte to circulate between the anode chamber and the anode liquid storage tank.

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