Application of carbon cloth loaded nonmetal COF material EN-COF electrode in electrochemical synthesis of urea
By using carbon cloth-supported non-metallic COF material EN-COF electrode in electrochemical synthesis of urea, the existing electrocatalysts have been solved, and efficient and stable urea synthesis is achieved.
Patent Information
- Application Number
- CN202510179574.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-19
- Publication Date
- 2025-05-13
- Estimated Expiration
- 2045-02-19
AI Technical Summary
The existing electrocatalysts have problems such as low activity, poor selectivity and short life in the electrochemical synthesis of urea, which affects the efficient synthesis of urea.
The EN-COF electrode with a carbon cloth supported by a non-metallic COF material was synthesized by a solvent-thermal strategy, and the catalyst ink was added dropwise to the carbon cloth through ultrasonic dispersion technology to prepare an EN-COF electrode with high activity and good selectivity.
A Faraday efficiency of 38.69% at -0.5V vs.RHE and a 11-hour continuous electrolytic stable current density of 0.6mAcm-2 were achieved, showing good electrocatalytic activity and stability.
Smart Images
Figure CN119980299A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of electrocatalysis, and specifically relates to an application of a carbon cloth-loaded non-metallic COF material EN-COF electrode in electrochemical synthesis of urea. Background Art
[0002] As an emerging synthesis technology, electrochemical synthesis of urea has shown several significant advantages compared to the traditional Haber-Bosch process. First, electrochemical synthesis of urea can be carried out at lower temperatures and pressures, which not only reduces dependence on energy, but also reduces energy consumption and equipment costs in the production process. Secondly, since the electrochemical process can be carried out at room temperature and pressure, it provides the possibility of using renewable energy sources, such as solar energy or wind energy, which helps to reduce dependence on fossil fuels and thus reduce greenhouse gas emissions. In addition, fewer by-products are produced during the electrochemical synthesis of urea, reducing the complexity and cost of waste treatment. At the same time, the process flow of electrochemical synthesis of urea is more flexible, and the output of urea can be adjusted according to actual needs, which facilitates small-scale or distributed production. Finally, the development of electrochemical synthesis of urea technology can also help promote technological innovation in related fields, such as the research and development of electrocatalyst materials, and open up new paths for the sustainable development of the chemical industry. The production of urea by electrocatalytic CN coupling of nitrogen-containing waste (nitrates, nitriles, nitrogen oxides) with CO2 is a new method for urea synthesis that has attracted widespread attention in recent years. - CO2 is introduced into the liquid and an appropriate overpotential is applied. Urea is synthesized in one step under the action of an electrocatalyst. Compared with traditional industrial methods, this method has the advantages of low energy consumption, simple operation, clean and environmental protection. The key to achieving efficient production of urea is to develop electrocatalysts with high catalytic activity, good selectivity and long life. Covalent organic framework material (COF) is an emerging functional material that has attracted widespread attention in the field of electrosynthesis of urea. Summary of the invention
[0003] The purpose of the present invention is to provide a method for preparing a carbon cloth-supported non-metallic COF material EN-COF electrode with simple raw materials, convenient synthesis, stable performance and good selectivity, and its application in the electrochemical synthesis of urea.
[0004] The technical solution adopted by the present invention is:
[0005] Application of a carbon cloth-loaded non-metallic COF material EN-COF electrode in electrochemical synthesis of urea.
[0006] Further, the above application method is as follows: the carbon cloth-loaded non-metallic COF material EN-COF electrode is used as the working electrode, the counter electrode is a platinum electrode, the reference electrode is an Ag / AgCl electrode, the cathode electrolyte is 35 mL of 0.1M KNO3 solution and 0.1M KHCO3 solution, and the anode electrolyte is 70 mL of 0.1M KHCO3 solution. At a potential of -0.3 to -0.7 V vs. RHE, Ar or CO2 is introduced into the cathode electrolyte, electrolysis is performed for 2 hours, and the cathode electrolyte product is collected.
[0007] Preferably, CO2 is introduced into the cathode electrolyte at a potential of -0.5 V vs. RHE.
[0008] The application described in any one of the above items, the preparation method of the carbon cloth supported non-metallic COF material EN-COF electrode comprises the following steps: TDOEB solid and TAPT solid are loaded into a pyrex tube, dissolved in a mixed solvent, frozen and evacuated from the air, and then the tube is flame-sealed; then the tube is placed in an oven for heating reaction, the tube is cooled to room temperature, centrifuged and washed with tetrahydrofuran, and the yellow solid is collected after vacuum drying, and the solid is fully ground to obtain a catalyst powder; the obtained catalyst powder is mixed with a membrane solution, 2-acetylene black, isopropanol, and ultrapure water to prepare ink, ultrasonicated, and the ink is dripped onto the carbon cloth using a pipette to obtain a carbon cloth supported non-metallic COF material EN-COF electrode.
[0009] Furthermore, in the method for preparing the above-mentioned carbon cloth-supported non-metallic COF material EN-COF electrode, the amount of TDOEB used is 0.03 mmol, and the amount of TAPT used is 0.03 mmol.
[0010] Furthermore, in the method for preparing the above-mentioned carbon cloth-supported non-metallic COF material EN-COF electrode, the mixed solvent is: 2 mL of dioxane, 8 mL of mesitylene and 0.8 mL of 6M acetic acid solution.
[0011] Furthermore, in the method for preparing the above-mentioned carbon cloth-loaded non-metallic COF material EN-COF electrode, the freezing is performed under 77K liquid nitrogen.
[0012] Furthermore, in the method for preparing the above-mentioned carbon cloth-loaded non-metallic COF material EN-COF electrode, the heating reaction temperature is 393K and the reaction time is 72h.
[0013] Furthermore, in the preparation method of the above-mentioned carbon cloth-loaded non-metallic COF material EN-COF electrode, the amount of the catalyst powder is 3 mg, the amount of 2-acetylene black is 3 mg, the amount of membrane solution is 30 μL, the amount of isopropanol is 170 μL, and the amount of ultrapure water is 200 μL; the ultrasonic time is 1 h.
[0014] Furthermore, the preparation method of the above-mentioned carbon cloth-loaded non-metallic COF material EN-COF electrode, the pretreatment method of the carbon cloth is: cut the carbon cloth into a rectangle of 1 cm×2 cm, soak it in acetone, anhydrous ethanol, concentrated nitric acid, anhydrous ethanol, and acetone in turn, ultrasonically oscillate for 30 minutes each time, and repeatedly wash it with ultrapure water, and vacuum dry the treated carbon cloth for use.
[0015] The beneficial effects of the present invention are:
[0016] 1. The present invention utilizes a solvent thermal strategy to synthesize catalyst powder and prepare it into ink, uses carbon cloth to support the catalyst, the raw materials are simple and easy to obtain, and the synthesis operation is easy.
[0017] 2. The catalyst synthesized by the present invention is used for electrochemical synthesis of urea, and reaches a maximum Faraday efficiency of 38.69% at -0.5V vs. RHE, showing good electrocatalytic activity and stability. The EN-COF catalyst obtained by the present invention has good application prospects in the field of electrocatalytic urea synthesis.
[0018] 3. The synthesized catalyst of the present invention was continuously electrolyzed at -0.5V vs. RHE for 11h, and the current density was stable at 0.6mAcm -2 , showing good electrocatalytic activity and stability. The EN-COF catalyst obtained in the present invention has good application prospects in the field of electrocatalytic urea synthesis. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 is a SEM image of the EN-COF catalyst prepared in Example 1.
[0020] Figure 2 is the FT-IR spectrum of the EN-COF catalyst prepared in Example 1.
[0021] Figure 3 is the XRD spectrum of the EN-COF catalyst prepared in Example 1.
[0022] Figure 4 This is the N2 adsorption-desorption isotherm diagram of the carbon cloth-loaded EN-COF electrode in Example 1.
[0023] Figure 5 This is a diagram of the experimental setup for electrochemical synthesis of urea using carbon cloth-loaded EN-COF electrodes in Example 2.
[0024] Figure 6 This is a comparison chart of the LSV curves of the carbon cloth-loaded EN-COF electrode in Example 2 in Ar and CO2 gases.
[0025] Figure 7It is the UV-vis absorption spectrum and urea standard curve of the diacetyl monooxime method for testing urea yield and Faraday efficiency in Example 2.
[0026] Figure 8 This is the urea Faraday efficiency diagram of the carbon cloth-loaded EN-COF electrode in Example 2.
[0027] Fig. 9 This is a test diagram of the catalytic stability of the carbon cloth-loaded EN-COF electrode in Example 2. DETAILED DESCRIPTION
[0028] Example 1 Preparation of carbon cloth loaded non-metallic COF material EN-COF electrode
[0029] (I) The preparation method is as follows:
[0030] 1) Pretreatment of carbon cloth: Cut the carbon cloth into a rectangle of 1 cm × 2 cm, soak it in acetone, anhydrous ethanol, concentrated nitric acid, anhydrous ethanol, and acetone in turn, ultrasonically vibrate it for 30 min each time, and wash it repeatedly with ultrapure water. Vacuum dry the treated carbon cloth for later use.
[0031] 2) Preparation of non-metallic COF materials: 0.03 mmol of each powdered TDOEB and TAPT were ground together and transferred to a pyrex tube, and then 2 mL of dioxane, 8 mL of mesitylene, and 0.8 mL of 6M acetic acid solution were added as a catalyst. After freezing at 77K (liquid nitrogen) and evacuating the air, the tube was flame-sealed. Then, the reaction was heated at 393K in an oven for 3 days, the tube was cooled to room temperature, centrifuged and washed several times with tetrahydrofuran (THF), and the yellow solid was collected after vacuum drying. The solid was fully ground to obtain the catalyst powder EN-COF.
[0032] 3) Preparation of carbon cloth-supported catalyst electrode: 3 mg of catalyst powder, 3 mg of 2-acetylene black, 30 μL of DuPont membrane solution, 170 μL of isopropanol, and 200 μL of ultrapure water were mixed to prepare catalyst ink, and the ink was dispersed evenly by ultrasonication for 60 min. The ink was dripped onto the pretreated carbon cloth using a pipette, with the amount of dripping being 10-12 drops, and weighed after drying. The catalyst loading was calculated based on the mass of the carbon cloth before and after the dripping.
[0033] (II) Test results
[0034] Figure 1 is a SEM image of EN-COF of the EN-COF catalyst powder prepared in Example 1. Figure 1 It can be seen that the material has a three-dimensional network structure composed of various micropores. Figure 2 is the FT-IR spectrum of the EN-COF catalyst powder prepared in Example 1. Figure 2It can be seen that the NH stretching of primary amine (3450cm -1 ) and N-CH3 stretching of TDOEB (1438 cm -1 ) have disappeared, proving that TAPT and TDOEB reacted completely and the reaction proceeded according to the experimental design. Figure 3 This is the XRD spectrum of the EN-COF catalyst powder prepared in Example 1. Compared with the spectra of raw materials TAPT and TDOEB, in the newly synthesized EN-COF catalyst powder, the raw material peak completely disappears, and a COF-specific peak appears at a small angle of 3.5°, proving the formation of the new substance EN-COF. Figure 4 The N2 adsorption-desorption isotherm of the carbon cloth-supported EN-COF electrode in Example 1 shows that the material has obvious gas absorption phenomenon, indicating that the material has obvious microporous structure. Figure 1 The SEM structures correspond to each other.
[0035] Example 2 Application of carbon cloth-supported EN-COF electrode in electrocatalytic synthesis of urea
[0036] Test method: The prepared carbon cloth loaded EN-COF electrode was used as the working electrode.
[0037] Experimental setup Figure 5 As shown, the experimental electrolyzer is an H-type electrolytic cell of Tianjin Aida, the proton exchange membrane is a Nafion117 membrane, the carbon cloth-loaded EN-COF electrode prepared in Example 1 is placed on the cathode electrode clip as the working electrode, the reference electrode uses an Ag / AgCl electrode, the counter electrode uses a platinum sheet electrode, the cathode electrolyte is 35mL 0.1M KNO3 solution and 35mL0.1MKHCO3 solution, and the anolyte is 70mL 0.1M KHCO3 solution. The experimental potential is set to -0.3~-0.7Vvs.RHE, Ar or CO2 is introduced into the cathode electrolyte, the electrolysis time is 2h, and the diacetyl monooxime method is used to detect the urea concentration in the cathode electrolyte.
[0038] The LSV curves of carbon cloth supported EN-COF electrode in Ar and CO2 atmospheres are shown in Figure 2. Figure 6 As shown in the figure, the current density in the Ar atmosphere is higher than that in the CO2 atmosphere, that is, a strong hydrogen evolution side reaction occurs in the Ar atmosphere, while the hydrogen evolution reaction in the CO2 atmosphere is weakened, which is beneficial to CO2 and NO3 - Reduction reaction and further CN coupling to synthesize urea.
[0039] The standard curve and Faraday efficiency of urea test are as follows Figure 7 , Figure 8 As shown: The five standard curve concentration ranges of the experimental setting are 0, 0.5, 1.0, 1.5, and 2.0 μg mL -1, the R of the standard curve was experimentally measured 2 It reaches 0.99906, with high credibility, and can be used as an external standard curve. Figure 8 As a result, the carbon cloth supported EN-COF electrode achieved a maximum Faradaic efficiency of 38.69% at -0.5 V vs. RHE.
[0040] Catalytic stability test Fig. 9 As shown: At the highest Faraday efficiency potential, the chronoamperometry method was used for continuous electrolysis for 11 h, and the current density was stabilized at 0.6 mA cm -1 , proving that the prepared catalyst electrode has high catalytic stability.
[0041] In summary, the carbon cloth-loaded non-metallic COF material EN-COF electrode of the present invention has a high Faraday efficiency and good electrocatalytic stability. Therefore, this carbon cloth-loaded EN-COF electrode has a relatively ideal development prospect in the field of electrocatalytic urea synthesis.
Claims
1. Application of a carbon cloth-loaded non-metallic COF material EN-COF electrode in the electrochemical synthesis of urea.
2. The use according to claim 1, characterized in that: The method is as follows: the carbon cloth-loaded non-metallic COF material EN-COF electrode is used as the working electrode, the counter electrode is a platinum electrode, the reference electrode is an Ag / AgCl electrode, the cathode electrolyte is 35 mL each of 0.1M KNO3 solution and 0.1M KHCO3 solution, and the anode electrolyte is 70 mL of 0.1M KHCO3 solution. At a potential of -0.3 to -0.7 V vs. RHE, Ar or CO2 is introduced into the cathode electrolyte, electrolyzed for 2 hours, and the cathode electrolyte product is collected.
3. The use according to claim 2, characterized in that: CO2 was bubbled into the catholyte at a potential of -0.5 V vs. RHE.
4. The use according to claim 1, 2 or 3, characterized in that: The preparation method of the carbon cloth-supported non-metallic COF material EN-COF electrode comprises the following steps: loading TDOEB solid and TAPT solid into a pyrex tube, dissolving them in a mixed solvent, freezing and exhausting the air, and then flame-sealing the tube; then placing the tube in an oven for heating reaction, cooling the tube to room temperature, centrifuging and washing with tetrahydrofuran, vacuum drying and collecting yellow solids, and fully grinding the solids to obtain catalyst powder; mixing the obtained catalyst powder with a membrane solution, 2-acetylene black, isopropanol, and ultrapure water to prepare ink, ultrasonicating, and using a pipette to drop the ink onto the carbon cloth to obtain the carbon cloth-supported non-metallic COF material EN-COF electrode.
5. The use according to claim 4, characterized in that: The amount of TDOEB used is 0.03 mmol, and the amount of TAPT used is 0.03 mmol.
6. The use according to claim 4, characterized in that: The mixed solvent is: 2 mL of dioxane, 8 mL of mesitylene and 0.8 mL of 6M acetic acid solution.
7. The use according to claim 4, characterized in that: The freezing is performed under 77K liquid nitrogen.
8. The use according to claim 4, characterized in that: The heating reaction temperature is 393K and the reaction time is 72h.
9. The use according to claim 4, characterized in that: The amount of the catalyst powder used was 3 mg, the amount of 2-acetylene black used was 3 mg, the amount of the membrane solution used was 30 μL, the amount of isopropanol used was 170 μL, and the amount of ultrapure water used was 200 μL; the ultrasonic time was 1 hour.
10. The use according to claim 4, characterized in that: The carbon cloth pretreatment method is as follows: the carbon cloth is cut into a rectangle of 1 cm×2 cm, and is soaked in acetone, anhydrous ethanol, concentrated nitric acid, anhydrous ethanol, and acetone in sequence, each time undergoing ultrasonic oscillation for 30 minutes, and is repeatedly washed with ultrapure water, and the treated carbon cloth is vacuum dried for later use.