A copper-silver alloy catalyst and preparation and use thereof
By introducing silver into the copper-based catalyst to form a Cu-Ag heterostructure, the problems of easy aggregation and hydrogen evolution side reaction of copper-based catalysts are solved, realizing an efficient and stable acetylene semi-hydrogenation to ethylene process, and improving catalytic activity and selectivity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV
- Filing Date
- 2024-10-28
- Publication Date
- 2026-06-02
Smart Images
Figure CN119465253B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of alloy material preparation technology, specifically to a copper-silver alloy catalyst and its preparation and application. Background Technology
[0002] Ethylene, propylene, butadiene, benzene, toluene, and xylene are important basic raw materials in petrochemical products, collectively known as the "three olefins" or "three benzenes." Among them, ethylene is a crucial commercial raw material for polymer production, accounting for over 75% of fossil products and holding a vital position in the national economy. According to a report by GlobalData, global ethylene demand will increase from 201 million tons per year in 2020 to 299 million tons per year in 2025, representing a growth of 49%. my country is also expected to lead the growth of ethylene production capacity in Asia by 2025.
[0003] Petroleum steam cracking is currently the main process for producing ethylene, but this process consumes large amounts of fossil fuels, harming the environment and hindering sustainable development. Since the 1950s, thermocatalytic ethylene production has gradually attracted attention. This method uses metals such as palladium as catalysts, enabling the production of ethylene at temperatures exceeding 200°C. o The method achieves an acetylene conversion rate of over 90% and an ethylene selectivity of 85%, but the precious metals used are costly, and the reaction is only effective at temperatures above 100°C. o Ideal acetylene conversion rates can only be achieved at temperatures above a certain temperature. Furthermore, both industrial and laboratory processes require the addition of excess hydrogen during the reaction, increasing operational risks and reducing the selectivity of acetylene to ethylene. Therefore, researchers are exploring green, clean, and sustainable electrocatalytic methods to achieve efficient acetylene to ethylene conversion. Numerous reports have demonstrated the feasibility and economic viability of using water as a proton source for hydrogenation reduction of the feedstock at room temperature through electrocatalysis. Moreover, with the continuous development of electrocatalytic reactors, devices such as flow cells have solved the mass transfer problem of acetylene gas feedstock in aqueous solutions. It is also hoped that water-insoluble acetylene gas can be selectively hydrogenated to ethylene using water protons. Based on this, electrocatalytic reduction of acetylene to ethylene has attracted widespread attention.
[0004] Based on the type of metal atoms at the active center, metal-based catalysts used in the electrocatalytic acetylene semi-hydrogenation can be divided into noble metal catalysts and non-noble metal catalysts. Noble metal catalysts, represented by platinum, exhibit good performance in the electrocatalytic reduction of acetylene to ethylene, but their high price limits their industrial application. Recent studies have found that inexpensive and highly conductive copper-based catalysts also demonstrate good performance in the electrocatalytic acetylene semi-hydrogenation. The surface of copper-based catalysts, especially the copper (111) crystal facet, has high ethylene adsorption energy and low ethylene desorption energy. This ensures sufficient adsorption of the reactant acetylene while promptly removing the product ethylene from the catalyst surface, preventing excessive reduction of acetylene to methane, and greatly improving the catalytic activity and selectivity of acetylene reduction to ethylene. However, copper-based catalysts, such as copper nanoparticles, are prone to aggregation during the reaction due to their high surface energy, reducing active sites and decreasing the catalyst's activity and stability at high currents. Furthermore, in the electrocatalytic acetylene semi-hydrogenation process, the "proton-deficient" microenvironment at low current densities is more conducive to the formation of C4 byproducts, reducing the selectivity of ethylene. Meanwhile, in aqueous electrolytes, especially at high reduction current densities, intense competitive hydrogen evolution side reactions occur, reducing the Faraday efficiency of ethylene. Therefore, designing a catalyst with a simple preparation process, high yield, highly active reaction sites, and the ability to suppress carbon-carbon coupling and over-hydrogenation is a current key challenge.
[0005] Currently, researchers are exploring various methods, such as doping and composite modification, to modify copper catalysts, thereby suppressing competitive hydrogen evolution reactions and over-hydrogenation reactions, and ultimately improving the catalytic activity and selectivity of copper-based catalysts in the electrocatalytic half-hydrogenation of acetylene. For example, Chinese patent document CN115976548A describes a method for preparing a supported metal phthalocyanine compound electrode. First, under ultrasonic conditions, the metal phthalocyanine compound solution and the support solution are dispersed separately in DMF. Then, the metal phthalocyanine compound solution and the support solution are mixed and stirred, treated with plasma, and after treatment, filtered, washed, and dried. The resulting catalyst and Nafion solution are poured into an organic solvent and ultrasonically treated to obtain a slurry. The cut electrode material is washed, and the slurry is evenly coated onto the electrode material. The solution is then irradiated with an infrared lamp until completely dry to obtain the supported metal phthalocyanine compound electrode. This method can achieve high selectivity and high stability in the half-hydrogenation of acetylene under mild conditions, but the preparation process is relatively complex. Therefore, a simpler and more effective method is needed to improve the intrinsic properties and electrocatalytic activity of the catalyst. Summary of the Invention
[0006] In view of the problems in the prior art, the present invention aims to provide a catalyst that improves the intrinsic performance and electrocatalytic activity of the catalyst in a simple and effective way, thereby achieving high selectivity and high stability in the electrocatalytic acetylene semi-hydrogenation to ethylene.
[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution.
[0008] A copper-silver alloy catalyst was prepared via a simple sodium borohydride reduction method. By introducing metallic silver into the copper matrix, abundant Cu-Ag heterointerfaces were formed within the catalyst. These heterointerfaces provide numerous reactive sites, and the heterometallic composite alters the electronic structure of the catalyst surface. This changes the binding energy of key reaction intermediates such as *C₂H₃ in the electrocatalytic reduction of acetylene to ethylene, thereby improving the catalytic performance of the electrocatalytic acetylene semi-hydrogenation to ethylene. More specifically, the technical solution provided by this invention is as follows.
[0009] This invention first provides a method for preparing a copper-silver alloy catalyst, which can obtain a copper-silver alloy catalyst with high electrocatalytic activity for the production of ethylene from acetylene through a simple sodium borohydride reduction method.
[0010] A method for preparing a copper-silver alloy catalyst includes the following steps:
[0011] (1) Add copper nitrate and silver nitrate to deionized water to prepare an aqueous solution containing copper nitrate and silver nitrate and stir continuously;
[0012] (2) Prepare a sodium borohydride solution as a reducing agent;
[0013] (3) The sodium borohydride solution from step 2) is added dropwise to the aqueous solution containing copper nitrate and silver nitrate from step 1) to carry out a reduction reaction, and the reduction product precipitates out of the solution;
[0014] (4) The reduction product obtained in step (3) was washed with deionized water and anhydrous ethanol, filtered, dried in a vacuum oven at 60 °C for 12 h, taken out and ground to obtain a copper-silver alloy catalyst. The obtained catalyst was a gray-green powder.
[0015] More specifically, in step (1), the molar concentration of copper nitrate in the aqueous solution is 0.039–0.124 mol / L, and the molar concentration of silver nitrate in the aqueous solution is 0.031–0.116 mol / L, with a molar ratio of copper nitrate to silver nitrate of 4:1–1:3. The copper-silver alloy catalyst prepared under these conditions, when applied to the electrocatalytic production of ethylene from acetylene, can further improve the catalytic activity and selectivity of the main product ethylene while maintaining good performance in suppressing hydrogen evolution. If the proportion of silver in the prepared copper-silver alloy catalyst is too low, its effect on the electronic structure of the catalyst surface is not significant, and it cannot improve the catalytic activity and selectivity; if the proportion of silver is too high, it may exacerbate the competitive hydrogen evolution reaction.
[0016] The stirring described in step (1) is preferably performed at a stirring speed of 600–1000 rpm.
[0017] The concentration of the sodium borohydride solution in step (2) is 1–5 mol / L. Excess sodium borohydride ensures that the metal ions are fully reduced to zero-valent metal elements and precipitated.
[0018] In step (3), to ensure the reduction reaction proceeds fully, the solution is continuously stirred throughout the process of adding sodium borohydride solution dropwise at a speed of 600–1000 rpm. This higher stirring speed ensures that the copper and silver ions in the solution react fully with the sodium borohydride, allowing copper and silver to precipitate out relatively uniformly and gradually. Furthermore, after the sodium borohydride solution is completely added, the stirring is maintained at this speed for approximately 10 minutes, ensuring the reaction proceeds fully through continuous high-speed stirring.
[0019] The preparation principle of the copper-silver alloy catalyst provided by this invention using the sodium borohydride reduction method is as follows: Copper nitrate and silver nitrate are dissolved in an aqueous solution. Under vigorous stirring, sodium borohydride solution is slowly added dropwise to the aqueous solution containing copper nitrate and silver nitrate. As the sodium borohydride solution is added, copper and silver ions in the solution react with it to gradually generate metallic elements, which then precipitate out. The vigorous stirring and the slow dropping rate of sodium borohydride ensure that silver and copper ions in the solution gradually and uniformly precipitate out as metallic elements in a certain proportion. Finally, the product obtained after the reduction reaction is washed with deionized water and anhydrous ethanol, thoroughly dried under vacuum, and ground to obtain the copper-silver alloy catalyst.
[0020] The present invention also provides a copper-silver alloy catalyst prepared by the above method, wherein the microstructure of the copper-silver alloy catalyst is a coral-like structure composed of several copper nanoparticles and silver nanoparticles, wherein the copper nanoparticles and silver nanoparticles are uniformly distributed. The copper-silver alloy catalyst is composed of two phases, Cu and Ag, and the molar ratio of copper to silver is 4.12:1–1:2.95.
[0021] Furthermore, the microstructure of the copper-silver alloy catalyst is a coral-like structure composed of several nanoparticles; wherein the copper nanoparticles and silver nanoparticles are uniformly dispersed, and the molar ratio of copper to silver in the composition of the copper-silver alloy catalyst is 0.51:1.
[0022] The present invention also provides the application of the above-mentioned copper-silver alloy catalyst in the electrocatalytic production of ethylene from acetylene, as detailed below.
[0023] The copper-silver alloy catalyst of the present invention is attached to carbon paper as a working electrode, with a loading of 0.8-1.8 mg / cm³. -2An electrocatalytic reaction of acetylene to ethylene was carried out in a fluid electrolytic cell using a 1 mol / L potassium hydroxide solution as the electrolyte and an electrolyte flow rate of 10 mL / min. Hg / HgO was used as the reference electrode and nickel foam was used as the counter electrode.
[0024] This invention prepares the copper-silver alloy catalyst by a simple sodium borohydride reduction method. Introducing metallic silver into a copper-based catalyst and combining it with copper forms a copper-silver alloy catalyst. This combination modulates the electronic structure of the catalytic material and the binding energy of reaction intermediates in the electrocatalytic acetylene to ethylene reaction. Simultaneously, it forms abundant Cu-Ag heterointerfaces, thereby providing a large number of active sites and improving the catalytic activity and selectivity of the electrocatalytic acetylene to ethylene reaction.
[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0026] (1) A copper-silver alloy catalyst was prepared by a simple sodium borohydride reduction method. The preparation method is simple, efficient, and reproducible, and is suitable for industrial production.
[0027] (2) The present invention prepares a copper-silver alloy catalyst by a simple sodium borohydride reduction method, wherein copper and silver nanoparticles are uniformly composited together, which has good conductivity and electrocatalytic potential. For example, the catalyst has a large current density and a low overpotential in the test potential range, showing excellent electrocatalytic potential.
[0028] (3) This invention prepares a copper-silver alloy catalyst through a simple sodium borohydride reduction method, which successfully introduces metallic silver into the copper-based catalyst, forming a rich Cu-Ag heterostructure interface. This provides a large number of active sites, altering the catalyst's electronic structure, such as electron cloud density, and the binding energy of reaction intermediates like *C2H3 in the electrocatalytic reduction of acetylene to ethylene, thereby improving the catalytic performance of the electrocatalytic acetylene semi-hydrogenation to ethylene. For example, at a current density of 100 mA cm⁻¹ -2 At that time, compared to the nano-copper catalyst, its ethylene Faradaic efficiency increased from 66.4% to 91.8%; at a current density of 500 mA cm⁻¹ -2 At that time, compared with the nano-copper catalyst, its ethylene Faraday efficiency increased from 92.2% to 97.1%.
[0029] (4) A copper-silver alloy catalyst prepared in this invention, even at 600 mA cm⁻¹ -2 Even at high current densities, its Faraday efficiency for converting acetylene to ethylene still reaches 89.2%, demonstrating its potential for industrial application.
[0030] (5) This invention uses clean and renewable electrical energy as its energy source, and can achieve efficient conversion of acetylene to ethylene without heating or pressurizing. Furthermore, the reaction system uses water as a hydrogen source, and there is no need to add dangerous hydrogen gas, which is in line with the concept of green, environmentally friendly and sustainable development. Attached Figure Description
[0031] Figure 1 The image shows the SEM image of the copper-silver alloy catalyst prepared in Example 1.
[0032] Figure 2 This is a TEM image of the copper-silver alloy catalyst prepared in Example 1.
[0033] Figure 3 The XRD patterns are of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2.
[0034] Figure 4 The electrochemical polarization curves of the catalysts prepared in Example 1, Comparative Examples 1 and 2 in a three-electrode reaction cell and a 1 M potassium hydroxide electrolyte are shown.
[0035] Figure 5 The figure shows the ethylene Faraday efficiency of the catalysts prepared in Example 1, Comparative Examples 1 and 2 in a three-electrode reaction cell and a 1 M potassium hydroxide electrolyte.
[0036] Figure 6 The figure shows the 1,3-butadiene Faraday efficiency of the catalysts prepared in Example 1, Comparative Examples 1 and 2 in a three-electrode reaction cell and a 1 M potassium hydroxide electrolyte.
[0037] Figure 7 The figure shows the hydrogen Faraday efficiency of the catalysts prepared in Example 1, Comparative Examples 1 and 2 in a three-electrode reaction cell and a 1 M potassium hydroxide electrolyte. Detailed Implementation
[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Example 1
[0039] Preparation steps of a copper-silver alloy catalyst:
[0040] Step 1: Weigh 0.1000 g of copper nitrate and 0.1406 g of silver nitrate on an electronic balance, i.e., the molar ratio of copper nitrate to silver nitrate is 1:2. Dissolve them completely in 8 ml of deionized water under magnetic stirring at 600-1000 rpm.
[0041] Step 2: Weigh 0.3783 g of sodium borohydride using an electronic balance and dissolve it in 2 ml of deionized water, resulting in a concentration of 5 mol / L.
[0042] Step 3: Slowly add the prepared sodium borohydride solution dropwise to the aqueous solution containing silver nitrate and copper nitrate. While adding the solution, continuously stir the reaction solution magnetically at 800 rpm. After the sodium borohydride solution is completely added, continue stirring at this speed for about 10 minutes until the reduction reaction is complete. The continuous high-speed stirring ensures that the reduction reaction proceeds fully and that copper and silver are uniformly precipitated, finally yielding a composite precipitate with uniformly distributed copper and silver nanoparticles.
[0043] Step 4: Wash the precipitate from Step 3 with deionized water and anhydrous ethanol, filter it, dry it in a vacuum oven at 60 °C for 12 h, take it out and grind it to obtain a copper-silver alloy catalyst. The catalyst powder is gray-green. Example 2
[0044] Preparation steps of a copper-silver alloy catalyst:
[0045] Step 1: Weigh 0.2400 g of copper nitrate and 0.04218 g of silver nitrate on an electronic balance, i.e., the molar ratio of copper nitrate to silver nitrate is 4:1. Dissolve them completely in 8 ml of deionized water under magnetic stirring.
[0046] Step 2: Weigh 0.3000 g of sodium borohydride on an electronic balance and dissolve it in 2 ml of deionized water.
[0047] Step 3: Slowly add the prepared sodium borohydride solution dropwise to the aqueous solution containing silver nitrate and copper nitrate. While adding the solution, continuously stir the reaction solution magnetically at 900 rpm. After the sodium borohydride solution has been added, continue stirring at this speed until the reduction reaction is completely finished, and the precipitate is obtained.
[0048] Step 4: Wash the precipitate from Step 3 with deionized water and anhydrous ethanol, filter it, dry it in a vacuum oven at 60 °C for 12 h, take it out and grind it to obtain a gray-green powdery copper-silver alloy catalyst. Example 3
[0049] Preparation steps of a copper-silver alloy catalyst:
[0050] Step 1: Weigh 0.1500 g of copper nitrate and 0.1055 g of silver nitrate on an electronic balance, i.e., the molar ratio of copper nitrate to silver nitrate is 1:1. Dissolve them completely in 8 ml of deionized water under magnetic stirring.
[0051] Step 2: Weigh 0.3000 g of sodium borohydride on an electronic balance and dissolve it in 2 ml of deionized water.
[0052] Step 3: Slowly add the prepared sodium borohydride solution dropwise to the aqueous solution containing silver nitrate and copper nitrate, while simultaneously carrying out the reduction reaction under magnetic stirring at 600 rpm to obtain the precipitate.
[0053] Step 4: Wash the precipitate from Step 3 with deionized water and anhydrous ethanol, filter it, dry it in a vacuum oven at 60 °C for 12 h, take it out and grind it to obtain the copper-silver alloy catalyst. Example 4
[0054] Preparation steps of a copper-silver alloy catalyst:
[0055] Step 1: Weigh 0.0750 g of copper nitrate and 0.1582 g of silver nitrate on an electronic balance, i.e., the molar ratio of copper nitrate to silver nitrate is 1:3. Dissolve them completely in 8 ml of deionized water under magnetic stirring.
[0056] Step 2: Weigh 0.0756 g of sodium borohydride using an electronic balance and dissolve it in 2 ml of deionized water.
[0057] Step 3: Slowly add the prepared sodium borohydride solution dropwise to the aqueous solution containing silver nitrate and copper nitrate, while simultaneously carrying out the reduction reaction under magnetic stirring at 1000 rpm to obtain the precipitate.
[0058] Step 4: Wash the precipitate from Step 3 with deionized water and anhydrous ethanol, filter it, dry it in a vacuum oven at 60 °C for 12 h, take it out and grind it to obtain a gray-green powdery copper-silver alloy catalyst.
[0059] The copper-silver alloy catalysts prepared in each embodiment were subjected to microscopic morphology and compositional analysis. SEM and TEM analysis revealed that the copper-silver alloy catalysts prepared in each embodiment exhibited a coral-like structure composed of several copper and silver nanoparticles, with the copper and silver nanoparticles uniformly distributed. Figure 1 and Figure 2 The SEM and TEM images of the copper-silver alloy catalyst prepared in Example 1 are shown below. Figure 1 As can be seen from Example 1, the copper-silver alloy catalyst prepared in Example 1 is composed of nanoparticles with a relatively regular microstructure; further from... Figure 2 It can be seen that the prepared copper-silver alloy catalyst has a coral-like structure composed of several nanoparticles.
[0060] XRD analysis confirmed that the copper-silver alloy catalysts prepared in each embodiment consisted of Cu and Ag, with Cu primarily exposed as the Cu (111) crystal plane and Ag primarily exposed as the Ag (111) crystal plane. For example, Figure 3 The XRD pattern of the copper-silver alloy catalyst prepared in Example 1 is recorded. The figure shows that the main components of the copper-silver alloy catalyst prepared in Example 1 are Ag and Cu. Further testing revealed that the molar ratio of copper to silver in the copper-silver alloy catalysts prepared in each example generally met the range of 4:1–1:3, the ratio of copper to silver added as raw materials during the preparation of the catalyst. The test results in each example were basically consistent with the ratio of the raw materials added. For example, the copper-silver molar ratio in the copper-silver alloy catalyst prepared in Example 1 was 0.51:1; in Example 2, it was 4.12:1; in Example 3, it was 1.04:1; and in Example 4, it was 1:2.95. This also confirms that the reduction reaction during the preparation process was very complete.
[0061] The copper-silver alloy catalysts prepared in each embodiment were applied to the electrocatalytic acetylene semi-hydrogenation to ethylene, and all showed excellent Faraday efficiency and high ethylene-specific selectivity. The following application example 1 shows the specific application of the copper-silver alloy catalyst prepared in Example 1.
[0062] Application Example 1
[0063] Application of the copper-silver alloy catalyst prepared in Example 1 as a cathode material for the electrocatalytic semi-hydrogenation of acetylene to ethylene.
[0064] Step 1: Weigh 10 mg of the catalyst prepared in Example 1 using an analytical balance, and simultaneously take 100 μL of isopropanol and 20 μL of 0.5 wt.% Nafion solution. Mix the three together and place them in a sample vial for sonication for 2 h.
[0065] Step 2: Cut out 2 × 2 cm pieces 2 Take a piece of carbon paper, and attach PTFE tape around the edges, leaving a 1 × 1 cm margin. 2 For space-drop coating of the catalyst, 100 μL of the catalyst solution prepared in step one is added dropwise to a 1 × 1 cm⁻¹ column. 2 On the carbon paper in the region, the catalyst loading was 1 mg cm⁻¹ -2 It is dried at room temperature or under infrared light and used as a working electrode.
[0066] Step 3: Using Hg / HgO as the reference electrode and nickel foam as the counter electrode, together with the working electrode, a three-electrode system is placed in a fluid electrolysis cell. 1 M potassium hydroxide is used as the electrolyte solution, and tests are conducted at different current densities. The yields of the product ethylene and the byproduct 1,3-butadiene are analyzed by gas chromatography.
[0067] Application Example 2
[0068] The copper-silver alloy catalyst prepared in Example 1 is used as a cathode material for the electrocatalytic semi-hydrogenation of acetylene to ethylene. The catalyst loading in this application example is 0.8 mg cm⁻¹. -2 Everything else is exactly the same as in Application Example 1.
[0069] Application Example 3
[0070] The copper-silver alloy catalyst prepared in Example 1 is used as a cathode material for the electrocatalytic semi-hydrogenation of acetylene to ethylene. The catalyst loading in this application example is 1.8 mg cm⁻¹. -2 Everything else is exactly the same as in Application Example 1.
[0071] In addition to the application of the copper-silver alloy catalyst in Example 1, the inventors also used copper-silver alloy catalysts prepared in other examples as cathode materials for the electrocatalytic acetylene semi-hydrogenation to ethylene production, under the same application conditions as in Examples 1-3, with a preferred loading of 0.8-1.8 mg / cm³. -2 When the loading is too low, there are few catalytic active sites, and the hydrogen evolution side reaction is more serious; when the loading is too high, there is more acetylene adsorbed on the catalyst surface and insufficient active hydrogen, which will lead to an increase in C4 byproducts.
[0072] The application effects of the catalysts prepared in each example were tested under the conditions of the above application examples, showing that in the range of 0.8-1.8 mg / cm², the results were satisfactory. -2 At the given catalyst loading, the catalysts in each embodiment exhibited comparable catalytic performance and Faradaic efficiency, demonstrating excellent catalytic performance and ethylene Faradaic efficiency. Taking the data from Application Example 1 as an example, ... Figure 4 The current density of the copper-silver alloy catalyst prepared in Example 1 at different potentials can be seen. This catalyst exhibits a large current density within the tested potential range, demonstrating its good conductivity and catalytic potential. Figure 5 It can be seen that the ethylene Faradaic efficiency of the catalyst in Example 1 at different current densities is [value missing]. Specifically, at a current density of 500 mA cm⁻¹, [value missing]. -2 At that time, its ethylene Faraday efficiency reached its highest level, approximately 97.1%; from Figure 6It can be seen that the catalyst has a 1,3-butadiene Faradaic efficiency at different current densities, with the lowest 1,3-butadiene Faradaic efficiency being approximately 1.02%. Compared with Comparative Example 1, the formation of the byproduct 1,3-butadiene was significantly suppressed in Example 1, improving the selectivity of the product ethylene. Figure 7 It can be seen that this catalyst operates within the range of 100-500 mA cm⁻¹. -2 Within the specified range, the Faraday efficiency of hydrogen is below 0.52%, and the current density is 600 mA cm⁻¹. -2 At that time, its hydrogen Faraday efficiency was only 9.69%, demonstrating good performance in suppressing hydrogen evolution.
[0073] Comparative Example 1
[0074] A method for preparing a copper-based catalyst:
[0075] Step 1: Weigh 0.300 g of copper nitrate on an electronic balance and dissolve it completely in 8 ml of deionized water under magnetic stirring.
[0076] Step 2: Weigh 0.3783 g of sodium borohydride using an electronic balance and dissolve it in 2 ml of deionized water.
[0077] Step 3: Slowly add the prepared sodium borohydride solution dropwise to the aqueous solution containing copper nitrate, and carry out the reduction reaction fully under magnetic stirring at 800 rpm to obtain the precipitate.
[0078] Step 4: The precipitate from Step 3 was washed with deionized water and anhydrous ethanol, filtered, and dried in a vacuum oven at 60 °C for 12 h. It was then removed, ground, and the copper-based catalyst was obtained. XRD analysis showed that... Figure 3 As shown in the figure, the copper-based catalyst prepared in Comparative Example 1 is composed of elemental Cu.
[0079] The copper-based catalyst prepared in Comparative Example 1 was applied to the electrocatalytic acetylene semi-hydrogenation to ethylene. This copper-based catalyst served as the cathode material for the electrocatalytic acetylene semi-hydrogenation to ethylene process. Except for the different cathode material, the method steps and parameters were consistent with those in Application Example 1. Tests showed that... Figure 4 Compared to the copper-silver alloy catalyst of Example 1, the copper-based catalyst of Comparative Example 1 exhibited lower current densities in the test range, and significantly lower conductivity and catalytic potential. Figure 5 The test results showed that, using the copper-based catalyst of Comparative Example 1 as the cathode material, the highest Faradaic efficiency obtained by electrocatalytic acetylene semi-hydrogenation to ethylene was approximately 92.2%, significantly lower than that of Example 1; Figure 6 As shown, carbon-carbon coupling is more intense at low current densities, resulting in a greater amount of 1,3-butadiene byproducts. At 100 mA cm⁻¹, this effect is particularly pronounced.-2 The Faradaic efficiency for the electrocatalytic semi-hydrogenation of acetylene to 1,3-butadiene was approximately 34.5%; from Figure 7 It can be seen that this catalyst operates within the range of 100-500 mA cm⁻¹. -2 Within the specified range, the Faraday efficiency of hydrogen is consistently below 3.41%, indicating good performance in suppressing hydrogen evolution, but the current density is 600 mA / cm². -2 At that time, its hydrogen Faraday efficiency was 16.5%, which was significantly higher than that of the example.
[0080] Comparative Example 2
[0081] A method for preparing a silver-based catalyst:
[0082] Step 1: Weigh 0.2109 g of silver nitrate on an electronic balance and dissolve it completely in 8 ml of deionized water under magnetic stirring.
[0083] Step 2: Weigh 0.3783 g of sodium borohydride using an electronic balance and dissolve it in 2 ml of deionized water.
[0084] Step 3: Slowly add the prepared sodium borohydride solution dropwise to the aqueous solution containing silver nitrate, and carry out the reduction reaction fully under magnetic stirring at 800 rpm to obtain the precipitate.
[0085] Step 4: The precipitate from Step 3 was washed with deionized water and anhydrous ethanol, filtered, and dried in a vacuum oven at 60 °C for 12 h. It was then removed, ground, and the silver-based catalyst was obtained. XRD analysis showed that... Figure 3 As shown in the figure, the silver-based catalyst prepared in Comparative Example 2 is composed of elemental Ag.
[0086] The silver-based catalyst prepared in Comparative Example 2 was applied to the electrocatalytic acetylene semi-hydrogenation to ethylene. This copper-based catalyst was used as the cathode material in the electrocatalytic acetylene semi-hydrogenation to ethylene process. Except for the different cathode material, the other method steps and parameters were consistent with those in Application Example 1. Tests showed that... Figure 4 Compared to the copper-silver alloy catalyst in Example 1, the silver-based catalyst in Comparative Example 2 exhibited lower current densities in the testing range, and significantly lower conductivity and catalytic potential. Figure 5 The test results showed that, using the silver-based catalyst of Comparative Example 2 as the cathode material, the highest Faradaic efficiency obtained by electrocatalytic acetylene semi-hydrogenation to ethylene was approximately 65.9%, which was significantly lower than that of Example 1; at 100-500 mA cm⁻¹ -2 Within the current density range, its hydrogen evolution side reaction is very strong, at 500 mA cm⁻¹. -2 The hydrogen Faraday efficiency is 92.8% at 600 mA cm⁻¹. -2The hydrogen evolution side reaction is more intense, and the hydrogen Faraday efficiency is further increased (e.g., Figure 7 ).
[0087] It should be noted that the specific implementation methods described above provide a detailed explanation of the technical solution and application results of the present invention. Readers should understand that the above embodiments are only the most preferred embodiments and are not intended to limit the present invention. Modifications or equivalent substitutions made by those skilled in the art within the core theoretical scope of the present invention should all fall within the protection scope of the present invention.
Claims
1. A copper-silver alloy catalyst, characterized in that, The copper-silver alloy catalyst is composed of two phases, Cu and Ag. The main exposed crystal plane of Cu is Cu(111) crystal plane, and the main exposed crystal plane of Ag is Ag(111) crystal plane. The molar ratio of copper to silver is 4.12:1–1:2.
95. The microstructure of the copper-silver alloy catalyst is a coral-like structure composed of several copper nanoparticles and silver nanoparticles, wherein the copper nanoparticles and silver nanoparticles are uniformly distributed.
2. The copper-silver alloy catalyst according to claim 1, characterized in that: The molar ratio of copper to silver in the composition of the copper-silver alloy catalyst is 0.51:
1.
3. A method for preparing a copper-silver alloy catalyst according to any one of claims 1-2, characterized in that, Including the following steps: 1) Add copper nitrate and silver nitrate to deionized water to prepare an aqueous solution containing copper nitrate and silver nitrate and stir continuously; 2) Prepare a sodium borohydride solution as a reducing agent; 3) The sodium borohydride solution from step 2) is added dropwise to the aqueous solution containing copper nitrate and silver nitrate from step 1) to carry out a reduction reaction, and the reduction product precipitates out of the solution; the sodium borohydride solution is added dropwise under stirring at a speed of 600-1000 rpm. 4) The product obtained in step 3) is washed with deionized water and anhydrous ethanol, filtered, dried in a vacuum oven, taken out and ground to obtain a copper-silver alloy catalyst.
4. The method for preparing a copper-silver alloy catalyst according to claim 3, characterized in that: In step 1), the molar concentration of copper nitrate in the aqueous solution is 0.039–0.124 mol / L, the molar concentration of silver nitrate in the aqueous solution is 0.031–0.116 mol / L, and the molar ratio of copper nitrate to silver nitrate added is 4:1–1:
3.
5. The method for preparing a copper-silver alloy catalyst according to claim 3, characterized in that: The concentration of the sodium borohydride solution mentioned in step 2) is 1–5 mol / L.
6. The application of the copper-silver alloy catalyst according to any one of claims 1-2, characterized in that, The copper-silver alloy catalyst is used in the electrocatalytic reduction of acetylene to prepare ethylene, serving as the cathode material for the electrocatalytic acetylene reduction reaction.
7. The application of the copper-silver alloy catalyst according to claim 6, characterized in that: The copper-silver alloy catalyst was attached to carbon paper as the working electrode, potassium hydroxide solution was used as the electrolyte, Hg / HgO was used as the reference electrode, and nickel foam was used as the counter electrode to form a three-electrode system for the electrocatalytic reduction of acetylene to produce ethylene in a fluid electrolytic cell.
8. The application of the copper-silver alloy catalyst according to claim 7, characterized in that, The steps for applying the copper-silver alloy catalyst to the electrocatalytic reduction of acetylene to prepare ethylene are as follows: Step 1: Take the copper-silver alloy catalyst and mix it evenly with isopropanol and Nafion solution to form a catalyst solution; Step two: Measure the catalyst solution and add it dropwise onto the carbon paper to achieve a catalyst loading of 0.8-1.8 mg / cm³. -2 The working electrode is obtained after drying; Step 3: Using Hg / HgO as the reference electrode and nickel foam as the counter electrode, together with the working electrode, a three-electrode system is placed in a fluid electrolysis cell. 1 M potassium hydroxide is used as the electrolyte solution to carry out the electrocatalytic reduction reaction of acetylene to prepare ethylene.