Novel bimetallic carbon material, low-temperature synthesis method thereof and application of novel bimetallic carbon material in ammonia production through nitrate reduction

Abstract

The invention discloses a novel bimetallic carbon material, a low-temperature synthesis method thereof and application of the novel bimetallic carbon material to ammonia production through nitrate radical reduction, and the method comprises the following steps: adding iminodiacetic acid type chelate resin (such as Mitsubishi chemical CR11 chelate resin) into a copper salt solution and a salt solution of an iron-series element to obtain a metal ion exchange precursor; drying the metal ion exchange precursor at room temperature for a period of time; mixing the dried metal ion exchange precursor according to a certain proportion, putting into a crusher, and crushing into powder; putting the powder into a tablet press for tabletting, putting a sample in an air-water vapor atmosphere after tabletting, and treating at 150-200 DEG C for 1-4 hours to finally prepare the bimetallic carbon material. The prepared bimetallic carbon material has high dispersity and excellent electro-catalytic performance, and the preparation process is simple, green and energy-saving, and has industrial application prospects.

Description

Technical Field

[0001] The invention belongs to the field of material preparation, and in particular relates to a novel bimetallic carbon material and a low-temperature synthesis method thereof and application of the bimetallic carbon material in the production of ammonia by nitrate reduction. Background Art

[0002] Ammonia is an important chemical and energy carrier, but the traditional Haber-Bosch process for producing ammonia is energy-intensive and has an impact on the environment. Therefore, exploring electrochemical ammonia synthesis methods using renewable energy has become a hot topic. - Reduction to ammonia (NO3RR) using NO3 - As a nitrogen source, the reaction process can be carried out at room temperature and pressure. Compared with the high temperature and high pressure conditions of traditional industrial ammonia synthesis, it is a green, environmentally friendly and efficient nitrate treatment method due to its convenient operation, low energy consumption and no secondary pollution. The ammonia produced can be used as a carrier of hydrogen energy. Nitrates are widely distributed in water bodies such as new energy battery waste and aquaculture tail water. They have high solubility in water and the dissociation energy of the N=O bond is relatively low. This provides a feasible new method and technology for green and sustainable ammonia synthesis by electrochemical reduction of nitrates, which has broad potential for development. This technology is carried out under the action of metal carbon-based catalysts at room temperature and pressure. The commonly used active substances in this technology are metals such as Cu, Cu, Co, Ru, Rh and Fe; the commonly used catalyst carriers are SiO2, mesoporous carbon and activated carbon. Most of the metal carbon materials used for electrochemical nitrate reduction to produce ammonia are basically prepared under high temperature conditions above 600 degrees and in a nitrogen atmosphere to improve the load stability and catalytic activity of the metal.

[0003] However, the above method still has certain limitations. For example, high-temperature calcination not only increases energy consumption, but also puts higher requirements on equipment, which does not meet the needs of energy conservation and emission reduction. In addition, high-temperature treatment usually involves multiple steps of calcination, reduction and other operations, and the process flow is relatively long, which increases production costs and difficulty. For example, under high temperature conditions, metal particles are prone to agglomeration, resulting in a decrease in catalytic activity and affecting reaction efficiency.

[0004] Therefore, developing a low-temperature, efficient and simple method for preparing metal-carbon-based catalysts is an important research direction in the current NO3RR field. Summary of the invention

[0005] The object of the present invention is to provide a novel metal-based carbon material for electrochemically reducing nitrate to ammonia and a low-temperature synthesis method thereof in view of the deficiencies of the prior art. The method can achieve the high-efficiency preparation of the bimetallic carbon material, and the prepared modified metal carbon material has the characteristics of high surface area, rich pore size distribution, high dispersion of active metals, diverse surface functional groups, good electrocatalytic performance, etc. The synthesis method can be prepared in one step under low-temperature conditions, with low energy consumption, meeting the requirements of green and energy-saving.

[0006] The object of the present invention is achieved through the following solutions:

[0007] In the first aspect, the present invention provides a low-temperature synthesis method of a novel bimetallic carbon material, using chelating resin (Mitsubishi Chemical CR11) as a carbon source, and copper and iron-based elements (iron, cobalt, nickel) as active substances, and performing treatments under different conditions, and successively proceeding according to the following steps:

[0008] Step (1): At room temperature, add iminodiacetic acid type chelating resin into copper salt solution and iron-based element salt solution respectively, adjust the pH to 3-7, and then stir evenly for ion exchange to obtain copper ion exchange resin and iron-based element ion exchange resin;

[0009] Preferably, the concentrations of the copper salt solution and the iron-based element salt solution are respectively 1-2 mol / L, more preferably 1 mol / L.

[0010] Preferably, the iron-based element is one of iron, cobalt or nickel, the copper salt is copper nitrate, and the salt of the iron-based element is nickel nitrate, iron nitrate or cobalt nitrate.

[0011] Preferably, the ion exchange duration is 2-5 h.

[0012] Preferably, the iminodiacetic acid type chelating resin is Mitsubishi DIAION TM CR11.

[0013] In this step, the present invention uses iminodiacetic acid type chelating resin as a carbon source. This chelating resin contains iminodiacetic acid (IDA) functional groups, which contain two carboxylic acid groups (-COOH) and one nitrogen atom (N), and can jointly provide electron pairs to coordinate with specific metal ions to form stable five-membered ring chelates. When heavy metal ions such as copper (Cu 2+ ) and iron (Fe 3+)When approaching IDA, heavy metal ions will be surrounded by IDA and form stable complexes. This chelation is usually more specific and firm than simple ion exchange because it relies on the simultaneous action of multiple ligand sites to fix metal ions. With the regulation of pH, more metal ions can form stable metal five-membered ring chelates with IDA.

[0014] Step (2): Filter out and dry the copper ion exchange resin and iron-based element ion exchange resin.

[0015] The drying temperature is controlled at 30 - 110 °C, and the drying time is 2 - 48 h.

[0016] Step (3): Mix and crush the dried copper ion exchange resin and iron-based element ion exchange resin to obtain a mixed powder. Among them, the molar ratio of copper in the copper ion exchange resin to the iron-based element in the iron-based element ion exchange resin is 1:(0.5 - 4).

[0017] Step (4): Press the mixed powder into tablets, and then perform heat treatment in a water vapor-air atmosphere. After cooling, the double-metal carbon material is obtained.

[0018] The pressure of the tablet press is controlled at 2 - 5 MPa, and the pressing time is 1 - 3 min.

[0019] The air treatment temperature is controlled at 150 - 200 °C, and the treatment duration is 1 h - 4 h.

[0020] The air treatment is carried out in a water vapor atmosphere, and the water vapor concentration (volume fraction) is 1% - 20%.

[0021] In this step, the tar generated during the heat treatment of the tablet-shaped sample in an air atmosphere will show a cross-linking phenomenon, and this cross-linking phenomenon can improve the carbon yield. In addition, the addition of water vapor can increase the content of oxygen-containing functional groups useful for electrocatalysis and improve the electrocatalytic performance. The chelate after ion exchange contains metal ions such as copper, nickel, cobalt, and iron, and these metal ions can promote the carbonization of the chelate. Therefore, the preparation of the metal carbon material can be achieved at a relatively low temperature.

[0022] The key technology for preparing the modified carbon material by this method lies in the control of the loading and mixing process of the modifying substances and the water vapor concentration during the air treatment process. The specific principle is as follows:

[0023] The target ions are uniformly attached to the chelating resin for modification through ion exchange, and then air-water vapor treatment is carried out on it. During the whole process, carbon forms its basic structure and surface acidic functional groups, and at the same time, the carbon yield is increased. Thus, a metal carbon composite material with uniformly distributed metal active sites and high performance is prepared.

[0024] In a second aspect, the present invention provides a novel bimetallic carbon material prepared by the above method.

[0025] In a third aspect, the present invention provides the application of the above novel bimetallic carbon material in the electrochemical reduction of nitrate to ammonia.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] 1. In the preparation process of the modified activated carbon material adopted by the present invention, after the target ions are attached to the carrier through ion exchange, air treatment is carried out to make the modified carbon have a high specific surface area and rich pore sizes (mainly mesopores).

[0028] 2. This modification method is in-situ growth. The prepared carbon material can fully exert the characteristics of the modified substance and the carbon itself, overcome the disadvantages of reduced and missing activity caused by the modified substance occupying the original sites of the activated carbon, and has high ammonia production performance.

[0029] 3. The process flow of this method is simple, environmentally friendly, and has a short production cycle. In particular, it can prepare metal-carbon materials at low temperature, saving energy consumption. In addition, the production raw materials are easy to obtain and the price is low, the production cost is low, the yield is high, and it has industrial application prospects. The finally prepared metal-based carbon catalyst has the characteristics of rich pore sizes and high dispersion degree, and its electrocatalytic performance is excellent. Description of the Drawings

[0030] Figure 1 are the SEM and Mapping diagrams of the composite metal-carbon material.

[0031] Figure 2 is the comparison diagram of the ammonia production performance of the composite metal-carbon material. Detailed Embodiments

[0032] The following further analyzes the present invention in combination with specific embodiments.

[0033] The embodiments of the present invention are implemented on the premise of the technical solutions of the invention, and detailed synthesis steps and specific operation methods are given. However, the protection scope of the present invention is not limited to the following embodiments. The experimental reagents used in the following embodiments can be obtained from conventional biochemical reagent companies without special instructions.

[0034] In the following embodiments, the electrochemical ammonia production experiment includes the following steps:

[0035] On an electrochemical workstation, using a three-electrode system, in an H-type electrolytic cell, the electrocatalytic nitrate reduction reaction performance of the catalyst was tested. The electrolytic cell was divided into a cathode chamber and an anode chamber, separated by a proton exchange membrane Nafion 117 in the middle. In a typical three-electrode system, the counter electrode was a Pt sheet electrode, the reference electrode was an Ag / AgCl (saturated KCl) standard electrode, and the working electrode was a carbon paper coated with the catalyst. The electrolyte was Na2SO4, the source of nitrate was KNO3, the electrolyte volumes in the cathode chamber and the anode chamber were 60 mL respectively. A bimetallic carbon material was added as the catalyst, the reaction time was 1 h. After the electrolytic reaction, the composition of the electrolyte was analyzed by ultraviolet-visible spectrophotometry.

[0036] As described above, the present invention provides a method for synthesizing a bimetallic carbon material, and the synthesis method includes the following steps:

[0037] Step (1): At room temperature, iminodiacetic acid type chelating resin was respectively added to a copper salt solution and a salt solution of an iron group element, and then stirred evenly for ion exchange for 2 - 5 h to obtain a copper ion-exchanged resin and an iron group element ion-exchanged resin; wherein, the pH values of the copper salt solution and the salt solution of the iron group element were both 3 - 7, and the concentrations were both 1 - 2 mol / L;

[0038] Step (2): The copper ion-exchanged resin and the iron group element ion-exchanged resin were filtered out and dried at 30 - 110 °C for 2 - 48 h;

[0039] Step (3): The dried copper ion-exchanged resin and the iron group element ion-exchanged resin were mixed and pulverized to obtain a mixed powder; wherein, the molar ratio of Cu in the copper ion-exchanged resin to the iron group element in the iron group element ion-exchanged resin was 1:(0.5 - 4);

[0040] Step (4): The mixed powder was pressed for 1 - 3 min under a pressure of 2 - 5 MPa, and then placed in a steam-air atmosphere with a concentration of 1% - 20%, and heat-treated at 150 - 200 °C for 1 - 4 h, and the bimetallic carbon material was obtained after cooling.

[0041] The iron group element refers to three elements with similar properties, namely iron, cobalt, and nickel, which are respectively at the head of Group 8, Group 9, and Group 10 (collectively called Group VIII B) in the periodic table, above the six platinum group elements; the outermost layer of the electron shell of the iron group elements all has two electrons, but the number of electrons in the second outermost layer is different, which are 6, 7, and 8 respectively. Coupled with their similar atomic radii, their properties are also very similar. Based on this, in the embodiments of the present invention, a salt solution of iron was used as a reactant for preparation.

[0042] Example 1

[0043] At room temperature, 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) was added to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The concentrations of the Cu(NO3)2 and Fe(NO3)3 solutions were both 1 mol / L, the pH was 7, and they were stirred evenly. After 2 h of ion exchange, the resin was filtered out and placed in a petri dish and dried at 30 °C for 24 h; the dried samples were taken out according to the molar ratio in Table 1 (calculated based on Cu and Fe, the same below), mixed and pulverized on a pulverizer, and further pressed into tablets at 5 MPa for 1 min; finally, the tableted samples were treated at 170 °C in a 1% steam-air mixed atmosphere for 2 h, and the prepared bimetallic carbon material was used for the electrochemical ammonia synthesis experiment. The effects of different molar ratios of Cu(NO3)2 and Fe(NO3)3 on the ammonia synthesis performance of the bimetallic carbon material are shown in Table 1.

[0044] Table 1. Effects of different molar mixing ratios of Cu(NO3)2 and Fe(NO3)3 on ammonia synthesis performance

[0045]

[0046] The catalyst prepared in this example was used together with the monometal modified resin materials Fe / CR11 and Cu / CR11 for electrochemical ammonia synthesis, and the results are as Figure 2 shown. It can be seen from Figure 2 this that the bimetal modification adopted in the present invention has an obvious improvement in catalytic performance.

[0047] Example 2

[0048] At room temperature, 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) was added to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The concentrations of the Cu(NO3)2 and Fe(NO3)3 solutions were both 1 mol / L, the pH was 6, and they were stirred evenly. After ion exchange for the time shown in Table 2, the resin was filtered out and placed in a 50 °C environment and dried for 12 h; the dried copper ion-exchanged resin and iron ion-exchanged resin were taken out according to a molar ratio of 1:2, put into a pulverizer and mixed and pulverized, and further pressed into tablets at 4 MPa for 2 min; finally, the tableted samples were treated at 170 °C in a 5% steam-air mixed atmosphere for 1.5 h, and the prepared bimetallic carbon material was used for the electrochemical ammonia synthesis experiment. The effects of different ion exchange times on the ammonia synthesis performance of the bimetallic carbon material are shown in Table 2.

[0049] Table 2. Effects of different ion exchange times on ammonia synthesis performance

[0050]

[0051] Example 3

[0052] At room temperature, 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) was added to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The concentrations of the solutions of Cu(NO3)2 and Fe(NO3)3 were both 1 mol / L, and the pH values of the solutions are shown in Table 3. Stir at a constant speed. After 4 h of ion exchange, the resin was filtered out and dried at a certain temperature for 2 h. The dried copper ion-exchanged resin and iron ion-exchanged resin were taken out in a molar ratio of 1:3, put into a pulverizer and mixed and pulverized, and further pressed into tablets at 6 MPa for 1 min. Finally, the tableted sample was treated at 180 °C in a 1% steam-air mixed atmosphere for 1.5 h, and the prepared bimetallic carbon material was used for the electrochemical ammonia synthesis experiment. The effects of different air drying temperatures on the ammonia synthesis performance of the bimetallic carbon material are shown in Table 3.

[0053] Table 3. Effects of different pH values on ammonia synthesis performance

[0054]

[0055] Example 4

[0056] At room temperature, 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) was added to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The concentrations of the solutions of Cu(NO3)2 and Fe(NO3)3 were both 1 mol / L and the pH values were both 5, and stirred at a constant speed. After 3 h of ion exchange, the resin was filtered out and dried at the temperature shown in Table 4 for 2 h. The dried copper ion-exchanged resin and iron ion-exchanged resin were taken out in a molar ratio of 1:3, put into a pulverizer and mixed and pulverized, and further pressed into tablets at 3 MPa for 3 min. Finally, the tableted sample was treated at 180 °C in a 1% steam-air mixed atmosphere for 1.5 h, and the prepared bimetallic carbon material was used for the electrochemical ammonia synthesis experiment. The effects of different air drying temperatures on the ammonia synthesis performance of the bimetallic carbon material are shown in Table 4.

[0057] Table 4. Effects of different drying temperatures on ammonia synthesis performance

[0058]

[0059] Example 5

[0060] At room temperature, add 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The concentrations of the Cu(NO3)2 and Fe(NO3)3 solutions are both 1 mol / L, and the pH values are both 4. Stir evenly, filter out the resin after 2 h of ion exchange, and place it in an environment at 30 °C for drying according to the drying time in Table 5; Take out the dried copper ion-exchanged resin and iron ion-exchanged resin in a molar ratio of 1:2, put them into a pulverizer for mixing and pulverizing, and further press into tablets at 2 MPa for 4 min; Finally, treat the tableted sample in a mixed atmosphere of 3% water vapor - air at 160 °C for 2 h, and use the prepared bimetallic carbon material for the electrochemical ammonia synthesis experiment. The effects of different drying times on the ammonia synthesis performance of the bimetallic carbon material are shown in Table 5.

[0061] Table 5. Effects of Drying Time on Ammonia Synthesis Performance

[0062]

[0063] Example 6

[0064] At room temperature, add 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The concentrations of the Cu(NO3)2 and Fe(NO3)3 solutions are both 1 mol / L, and the pH values are both 3. Stir evenly, take out the dried copper ion-exchanged resin and iron ion-exchanged resin in a molar ratio of 1:1, put them into a pulverizer for mixing and pulverizing, and further press into tablets at the strength in Table 6 for 2 min; Finally, treat the tableted sample in a mixed atmosphere of 10% water vapor - air at 150 °C for 4 h, and use the prepared bimetallic carbon material for the electrochemical ammonia synthesis experiment. The effects of different tablet pressing strengths on the ammonia synthesis performance of the bimetallic carbon material are shown in Table 6.

[0065] Table 6. Effects of Different Tablet Pressing Strengths on Ammonia Synthesis Performance

[0066]

[0067] Example 7

[0068] At room temperature, add 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The concentrations of the Cu(NO3)2 and Fe(NO3)3 solutions are both 1 mol / L, the pH is 7, and stir evenly. After 0.5 h of ion exchange, filter out the resin and dry it in an 80 °C environment for 4 h; take out the dried copper ion-exchanged resin and iron ion-exchanged resin in a molar ratio of 1:4, put them into a pulverizer and mix and pulverize, and further press tablets according to the tableting time in Table 7 at a strength of 3.5 Mpa; finally, treat the tableted sample in a 5% steam-air mixed atmosphere at 160 °C for 3 h to prepare different bimetallic carbon materials. The effects of different tableting times on the ammonia production performance of the bimetallic carbon materials are shown in Table 7.

[0069] Table 7. Effects of different tableting times on ammonia production performance

[0070]

[0071] Example 8

[0072] At room temperature, add 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The concentrations of the Cu(NO3)2 and Fe(NO3)3 solutions are both 1 mol / L, the pH is 6, and stir evenly. After 1 h of ion exchange, filter out the resin and dry it in an 110 °C environment for 2 h; take out the dried copper ion-exchanged resin and iron ion-exchanged resin in a molar ratio of 1:0.5, put them into a pulverizer and mix and pulverize, and further press tablets at 3 MPa for 3 min; finally, treat the tableted sample in the steam-air mixed atmosphere in Table 8 at 190 °C for 1 h to prepare different bimetallic carbon materials. The effects of different steam concentrations on the ammonia production performance of the bimetallic carbon materials are shown in Table 8.

[0073] Table 8. Effects of different steam concentrations on ammonia production performance

[0074]

[0075] Example 9

[0076] At room temperature, add 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The solution concentrations of Cu(NO3)2 and Fe(NO3)3 are both 1 mol / L, the pH values are both 5, and stir evenly. After 2 h of ion exchange, filter out the resin and place it in an environment at 30 °C for drying for 48 h; Take out the dried copper ion-exchanged resin and iron ion-exchanged resin in a molar ratio of 1:2, put them into a crusher for mixing and crushing, and further press into tablets at 4 MPa for 3 min; Finally, place the pressed sample in a 1% steam-air mixed atmosphere and treat it at the temperature in Table 9 for 2 h to prepare different bimetallic carbon materials. The effects of different treatment temperatures on the ammonia production performance of the bimetallic carbon materials are shown in Table 9.

[0077] Table 9. Effects of Different Treatment Temperatures on Ammonia Production Performance

[0078]

[0079]

[0080] Example 10

[0081] At room temperature, add 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The solution concentrations of Cu(NO3)2 and Fe(NO3)3 are both 1 mol / L, the pH values are both 7, and stir evenly. After 3 h of ion exchange, filter out the resin and place it in an environment at 110 °C for drying for 2 h; Take out the dried copper ion-exchanged resin and iron ion-exchanged resin in a molar ratio of 1:0.5, put them into a crusher for mixing and crushing, and further press into tablets at 3 MPa for 3 min; Finally, place the pressed sample in a 10% steam-air mixed atmosphere and treat it at 170 °C for the time in Table 10 to prepare different bimetallic carbon materials. The effects of different treatment times on the ammonia production performance of the bimetallic carbon materials are shown in Table 10.

[0082] Table 10. Effects of Different Treatment Times on Ammonia Production Performance

[0083]

[0084] Example 11

[0085] At room temperature, 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) was added to the solutions of Cu(NO3)2 and Fe(NO3)3 respectively. The solution concentrations of Cu(NO3)2 and Fe(NO3)3 were both 1 mol / L, and the pH was 7. Stirring was carried out at a constant speed. After 2 h of ion exchange, the resin was filtered out and dried in an environment of 30 °C for 48 h; the dried copper ion-exchanged resin and iron-based element ion-exchanged resin were taken out in a molar ratio of 1:2, put into a pulverizer and mixed and pulverized, and further tableted at 3.5 MPa for 3 min; finally, the tableted sample was heat-treated at 170 °C for 2 h in a 5% steam-air mixed atmosphere.

[0086] The SEM and Mapping diagrams of the prepared bimetallic carbon material are as Figure 1 shown.

[0087] Comparative Example 1

[0088] The resin was replaced with PK resin, and the preparation was carried out according to the conditions of Example 11, and the electrochemical ammonia production experiment was carried out. The results are shown in Table 11.

[0089] Table 11. Influence of resin type on ammonia production performance

[0090]

[0091]

[0092] Example 12

[0093] At room temperature, 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) was added to the solutions of Cu(NO3)2 and Co(NO3)2 respectively. The solution concentrations of Cu(NO3)2 and Co(NO3)2 were both 1 mol / L, and the pH was 7. Stirring was carried out at a constant speed. After 2 h of ion exchange, the resin was filtered out and dried in an environment of 30 °C for 48 h; the dried copper ion-exchanged resin and iron-based element ion-exchanged resin were taken out in a molar ratio of 1:2, put into a pulverizer and mixed and pulverized, and further tableted at 3.5 MPa for 3 min; finally, the tableted sample was heat-treated at 170 °C for 2 h in a 5% steam-air mixed atmosphere to obtain a bimetallic carbon material.

[0094] Example 13

[0095] At room temperature, 10 g of chelating resin (Mitsubishi Chemical CR11, iminodiacetic acid type chelating resin) is added to the solutions of Cu(NO3)2 and Ni(NO3)2 respectively. The solution concentrations of Cu(NO3)2 and Ni(NO3)2 are both 1 mol / L, the pH values are both 7, and they are stirred evenly. After 3 h of ion exchange, the resin is filtered out and dried in an environment of 110 °C for 2 h; the dried copper ion-exchanged resin and iron ion-exchanged resin are taken out in a molar ratio of 1:0.5, put into a crusher and mixed and crushed, and further pressed into tablets at 3 MPa for 3 min; finally, the pressed sample is heat-treated at 170 °C for 4 h in a 10% steam-air mixed atmosphere to prepare a bimetallic carbon material.

[0096] The above embodiments are not limitations on the present invention. The present invention is not limited to the above embodiments. As long as it meets the requirements of the present invention, it belongs to the protection scope of the present invention.

Claims

1. A method for synthesizing a bimetallic carbon material, characterized in that, The synthesis method comprises the following steps: Step (1): At room temperature, add iminodiacetic acid type chelating resin into a copper salt solution and a salt solution of an iron-based element respectively, and then stir evenly for ion exchange to obtain a copper ion-exchanged resin and an iron-based element ion-exchanged resin; Step (2): Filter out and dry the copper ion-exchanged resin and the iron-based element ion-exchanged resin; Step (3): Mix and pulverize the dried copper ion-exchanged resin and the iron-based element ion-exchanged resin to obtain a mixed powder; wherein, the molar ratio of copper in the copper ion-exchanged resin to the iron-based element in the iron-based element ion-exchanged resin is 1: (0.5 - 4); Step (4): Press the mixed powder into tablets, and then place it in a steam-air atmosphere for heat treatment at 150 - 200 °C, and obtain the bimetallic carbon material after cooling.

2. The synthesis method according to claim 1, characterized in that, In step (1), the pH values of the copper salt solution and the salt solution of the iron-based element are both 3 - 7, and the concentrations are both 1 - 2 mol / L.

3. The synthesis method according to claim 2, characterized in that, In step (1), the iron-based element is selected from one of iron, cobalt, and nickel.

4. The synthesis method according to claim 1, characterized in that, In step (1), the ion exchange duration is 2 - 5 h.

5. The synthesis method according to claim 1, characterized in that, In step (2), the drying temperature is 30 - 110 °C, and the drying time is 2 - 48 h.

6. The synthesis method according to claim 1, characterized in that, In step (4), the pressure used for pressing the tablets is 2 - 5 MPa; the pressing time is 1 - 3 min.

7. The synthesis method according to claim 1, characterized in that, In step (4), the volume percentage concentration of water vapor is 1% - 20%.

8. The synthesis method according to claim 1, characterized in that, The heat treatment duration is 1 - 4 h.

9. A bimetallic carbon material, characterized in that, Prepared by using the synthesis method according to any one of claims 1 - 8.

10. Application of the bimetallic carbon material according to claim 9 in the electrochemical reduction of nitrate to ammonia.

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