A graphitized activated carbon supported iron-cobalt bimetallic catalyst for ammonia synthesis

Abstract

The application discloses a graphitized activated carbon supported iron-cobalt bimetallic catalyst for synthesizing ammonia and a preparation method thereof, which comprises the following steps: high-temperature heat treatment of activated carbon in an inert atmosphere, oxidation and hole expansion in air to obtain graphitized activated carbon, introduction of carbon-containing organic matter, impregnation of an iron precursor solution, heat treatment in a CO-containing mixed gas, impregnation of a cobalt precursor solution, drying, reduction, impregnation of a potassium precursor solution, drying, reduction, and ammonia synthesis catalyst with graphitized activated carbon as a carrier, iron and cobalt bimetallic as active components and potassium as an additive is obtained. Compared with the activated carbon supported iron catalyst prepared by the prior art, the catalyst obtained by the application has higher ammonia synthesis activity and better application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ammonia synthesis catalysts, and particularly relates to a graphitized activated carbon supported iron-cobalt bimetallic catalyst for synthesizing ammonia and a preparation method thereof. BACKGROUND

[0002] The annual ammonia production in the world exceeds 150 million tons, about 80% of which is used for producing chemical fertilizers, and the rest is mainly used as raw materials for various nitrogen-containing chemical products, applied in the fields of medicines, explosives and plastics. Recently, it is found that ammonia is an ideal hydrogen storage material and a carbon-free energy, which is an important chemical related to the development of the field of renewable energy in the future. Therefore, the demand for ammonia in human society will increase day by day, and it is necessary to continuously develop new ammonia synthesis processes that can efficiently synthesize ammonia under mild conditions, and the key is the design and development of cheap and high-performance catalysts.

[0003] It is known that the ammonia synthesis reaction is composed of a series of elementary reaction steps such as adsorption, activation, reaction of nitrogen and hydrogen molecules, and desorption of intermediates and products, so the catalyst needs to have enough active sites to improve its ammonia synthesis performance. The specific surface area of the existing molten iron ammonia synthesis catalyst is low, resulting in low adsorption efficiency of ammonia synthesis reaction gas on the surface of the catalyst, so it needs to be kept under high pressure (15-30 MPa) and high temperature (450-510 ℃) harsh reaction conditions to maintain high activity, and the reaction energy consumption is high and the emission is large. The second generation of ruthenium-based ammonia synthesis catalysts can operate under relatively mild conditions (380−440 ℃, 10−11.0 MPa), but the price of ruthenium metal is high, and the cost of the catalyst is high, which is a problem that cannot be avoided in the large-scale industrial application of Ru-based catalysts. Therefore, it is urgent to develop more cost-effective high-performance catalysts, especially catalysts that can efficiently synthesize ammonia under relatively mild conditions.

[0004] In view of the problem, the application uses graphitized activated carbon as a carrier, combines a CO-containing atmosphere treatment step, and introduces cobalt metal, so that the iron metal particles in the obtained graphitized activated carbon supported iron-cobalt bimetallic catalyst are small, and a large amount of superparamagnetic iron oxide exists in the prepared catalyst, so the catalyst has high ammonia synthesis activity. SUMMARY

[0005] In view of the fact that the existing molten iron catalyst cannot meet the ammonia synthesis under mild conditions, the application provides a graphitized activated carbon supported iron-cobalt bimetallic ammonia synthesis catalyst and a preparation method thereof, which has high ammonia synthesis activity and good application prospect.

[0006] To achieve the above object, the application adopts the following technical scheme:

[0007] The application discloses a graphitized activated carbon supported iron-cobalt bimetallic catalyst for synthesizing ammonia, which is composed of graphitized activated carbon as a carrier, iron and cobalt bimetallic as active components and potassium as an additive; wherein the mass ratio of iron to the graphitized activated carbon is 0.05:1-0.3:1, the mass ratio of cobalt to the graphitized activated carbon is 0.01:1-0.09:1, and the mass ratio of potassium to the graphitized activated carbon is 0.02:1-0.2:1.

[0008] The preparation method of the graphitized activated carbon supported iron-cobalt bimetallic catalyst comprises the following steps:

[0009] 1) after high-temperature heat treatment of the activated carbon in an inert atmosphere and cooling to room temperature, the activated carbon is transferred to an air atmosphere to perform oxidation and hole expansion, thereby obtaining graphitized activated carbon;

[0010] 2) carbon-containing organic matter is introduced into the graphitized activated carbon by using a solution impregnation method;

[0011] 3) the graphitized activated carbon with the introduced carbon-containing organic matter obtained in step 2) is immersed into an iron precursor solution, and then heat treatment is performed in a mixed gas containing CO, thereby obtaining an iron catalyst supported by the graphitized activated carbon;

[0012] 4) the iron catalyst supported by the activated carbon obtained in step 3) is impregnated with a cobalt precursor solution, dried and then reduced, thereby obtaining an iron-cobalt bimetallic catalyst precursor supported by the graphitized activated carbon;

[0013] 5) the iron-cobalt bimetallic catalyst precursor supported by the graphitized activated carbon obtained in step 4) is immersed into a potassium precursor solution, dried and then reduced, thereby obtaining the graphitized activated carbon supported iron-cobalt bimetallic catalyst.

[0014] Further, the inert atmosphere in step 1) is one or more of nitrogen and group 0 gas, and the gas flow rate is 25-1000 mL / min.

[0015] Further, the high-temperature heat treatment in step 1) is performed at a temperature of 1500-2000 DEG C for 1-10 hours.

[0016] Further, the oxidation and hole expansion in step 1) is performed at a temperature of 200-500 DEG C for 3-48 hours.

[0017] Further, the carbon-containing organic matter in step 2) is any one of sucrose, glucose and melamine, and the mass ratio of the carbon-containing organic matter to the graphitized activated carbon is 0.01:1-0.1:1.

[0018] Further, the iron precursor solution in step 3) is a ferric nitrate solution or a ferric chloride solution.

[0019] Further, the CO-containing mixed gas in step 3) is a mixed gas of CO and nitrogen or a Group 0 gas, wherein the volume content of CO is 3-100%.

[0020] Further, the temperature of the heat treatment in step 3) is 200-600 ℃, and the time is 0.5-20 hours.

[0021] Further, the cobalt precursor solution in step 4) is an aqueous solution of cobalt nitrate.

[0022] Further, the potassium precursor solution in step 5) is obtained by dissolving potassium hydroxide or potassium nitrate in one or more of water, methanol, and ethanol.

[0023] Further, the reduction in steps 4) and 5) is carried out by treating at 200-600 ℃ for 0.2-48 hours in a hydrogen-containing gas, wherein the hydrogen-containing gas is a mixed gas of hydrogen and nitrogen or a Group 0 gas, and the volume content of hydrogen is 1-100%.

[0024] The significant advantages of the present application are:

[0025] The present application provides a graphitized activated carbon-supported iron-cobalt bimetallic catalyst for synthesizing ammonia. The catalyst uses graphitized activated carbon as a carrier, introduces an iron precursor, and then performs heat treatment in a CO-containing atmosphere. After that, cobalt metal and potassium as an additive are introduced, thereby obtaining an ammonia synthesis catalyst with small average particle size of iron metal particles and containing a large amount of superparamagnetic iron oxide. Compared with existing graphitized carbon-supported iron catalysts and traditional iron-cobalt bimetallic catalysts prepared by impregnation, the catalyst obtained by the present application has higher ammonia synthesis activity and good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 HADDF-STEM images and particle size distribution diagrams of the 5K-10Fe / C-H catalyst (a) obtained in Comparative Example 1 and the 5K-2Co-10Fe / C catalyst (b) obtained in Example 1.

[0027] Figure 2 Mossbauer spectra of the 5K-10Fe / C-H catalyst (a) obtained in Comparative Example 1 and the 5K-2Co-10Fe / C catalyst (b) obtained in Example 1. DETAILED DESCRIPTION

[0028] A graphitized activated carbon-supported iron-cobalt bimetallic catalyst, the preparation of which comprises the following steps:

[0029] 1) After heat treatment of activated carbon at a high temperature of 1500-2000 ℃ in an inert atmosphere for 1-10 hours and cooling to room temperature, the activated carbon is transferred to an air atmosphere, and is oxidized and expanded at a temperature of 200-500 ℃ for 3-48 hours to obtain graphitized activated carbon.

[0030] 2) impregnating the graphitized activated carbon with a solution of carbon-containing organic matter, thereby introducing carbon-containing organic matter into the graphitized activated carbon;

[0031] 3) impregnating the graphitized activated carbon with the introduced carbon-containing organic matter obtained in step 2) in a solution of ferric nitrate or ferric chloride, and then heat treating at 200-600 ℃ for 0.5-20 hours in a CO-containing mixed gas to obtain a graphitized activated carbon-supported iron catalyst;

[0032] 4) impregnating the graphitized activated carbon-supported iron catalyst obtained in step 3) with a solution of cobalt nitrate, and then reducing at 200-600 ℃ for 0.2-48 hours in a hydrogen-containing gas after drying to obtain a graphitized activated carbon-supported iron-cobalt bimetallic catalyst precursor;

[0033] 5) impregnating the graphitized activated carbon-supported iron-cobalt bimetallic catalyst precursor obtained in step 4) in a solution of potassium precursor, and then reducing at 200-600 ℃ for 0.2-48 hours in a hydrogen-containing gas after drying to obtain a graphitized activated carbon-supported iron-cobalt bimetallic catalyst.

[0034] In step 1), the inert atmosphere is one or more of nitrogen, 0-group gas, and the gas flow rate is 25-1000 mL / min.

[0035] In step 2), the carbon-containing organic matter is any one of sucrose, glucose, or melamine, and the mass ratio of the carbon-containing organic matter to the graphitized activated carbon used is 0.01:1-0.1:1.

[0036] In step 3), the CO-containing mixed gas is a mixed gas of CO and nitrogen or 0-group gas, wherein the volume content of CO is 3-100%.

[0037] In step 5), the solution of potassium precursor is obtained by dissolving potassium hydroxide or potassium nitrate in one or more of water, methanol, or ethanol.

[0038] In steps 4) and 5), the hydrogen-containing gas is a mixed gas of hydrogen and nitrogen or 0-group gas, wherein the volume content of hydrogen is 1%-100%.

[0039] In the obtained catalyst, the mass ratio of iron to graphitized activated carbon is 0.05:1-0.3:1, the mass ratio of cobalt to graphitized activated carbon is 0.01:1-0.09:1, and the mass ratio of potassium to graphitized activated carbon is 0.02:1-0.2:1.

[0040] In order to make the content of the present application more convenient to understand, the technical solutions of the present application will be further described below in combination with specific embodiments, but the present application is not limited thereto.

[0041] Example 1

[0042] 1) The activated carbon was heat-treated in nitrogen (1000 mL / min) at 1800 °C for 2 hours, then cooled to room temperature, and then oxidized in air at 400 °C for 24 hours to obtain graphitized activated carbon;

[0043] 2) The obtained graphitized activated carbon was immersed in a melamine-containing aqueous solution, wherein the mass ratio of melamine to graphitized activated carbon used was 0.05:1;

[0044] 3) The sample treated in step 2) was immersed in an appropriate amount of aqueous ferric nitrate solution, dried, and then heat-treated in pure CO at 500 °C for 2 hours to obtain a graphitized activated carbon-supported iron catalyst;

[0045] 4) The prepared graphitized activated carbon-supported iron catalyst was immersed in an appropriate amount of aqueous cobalt nitrate solution, dried, and then reduced in pure hydrogen at 450 °C for 6 hours to obtain a graphitized activated carbon-supported iron-cobalt bimetallic catalyst precursor;

[0046] 5) The cooled precursor of step 5) was immersed in an aqueous potassium hydroxide solution, dried, and then reduced in pure hydrogen at 450 °C for 6 hours to obtain a 5K-2Co-10Fe / C catalyst sample, wherein the mass ratio of iron metal to graphitized activated carbon was 0.1:1, the mass ratio of cobalt metal to graphitized activated carbon was 0.02:1, and the mass ratio of potassium to graphitized activated carbon was 0.05:1.

[0047] Example 2

[0048] 1) The activated carbon was heat-treated in argon (1000 mL / min) at 1900 °C for 8 hours, then cooled to room temperature, and then oxidized in air at 500 °C for 8 hours to obtain graphitized activated carbon;

[0049] 2) The obtained graphitized activated carbon was immersed in a sucrose solution, wherein the mass ratio of sucrose to graphitized activated carbon used was 0.1:1;

[0050] 3) The sample treated in step 2) was immersed in an appropriate amount of aqueous ferric nitrate solution, dried, and then heat-treated in a 75% CO + 25% Ar mixed gas at 450 °C for 6 hours to obtain a graphitized activated carbon-supported iron catalyst;

[0051] 4) The prepared graphitized activated carbon-supported iron catalyst was immersed in an appropriate amount of aqueous cobalt nitrate solution, dried, and then reduced in a 75% H2 + 25% N2 mixed gas at 400 °C for 18 hours to obtain a graphitized activated carbon-supported iron-cobalt bimetallic catalyst precursor;

[0052] 5) The precursor after step 5) is impregnated with potassium hydroxide aqueous solution, dried and then reduced in pure hydrogen at 550 ℃ for 4 hours to obtain a 3K-8Co-20Fe / C catalyst sample, in which the mass ratio of iron metal to graphitized active carbon is 0.2:1, the mass ratio of cobalt metal to graphitized active carbon is 0.08:1, and the mass ratio of potassium to graphitized active carbon is 0.03:1.

[0053] Example 3:

[0054] 1) The active carbon is heat-treated in a 10%He+90%N2 mixed gas (1000 mL / min) at 1600 ℃ for 5 hours, then cooled to room temperature, and then oxidized and expanded in 100 mL / min of air at 300 ℃ for 40 hours to obtain graphitized active carbon;

[0055] 2) The obtained graphitized active carbon is impregnated with a glucose solution, in which the mass ratio of glucose to graphitized active carbon used is 0.08:1;

[0056] 3) The sample after step 2) is impregnated with an appropriate amount of ferric nitrate aqueous solution, dried and then heat-treated in a 80%CO+20%N2 mixed gas at 250 ℃ for 16 hours to obtain a graphitized active carbon supported iron catalyst;

[0057] 4) The prepared graphitized active carbon supported iron catalyst is impregnated with an appropriate amount of cobalt nitrate aqueous solution, dried and then reduced in a 90%H2+10%Ar mixed gas at 300 ℃ for 40 hours to obtain a graphitized active carbon supported iron-cobalt bimetallic catalyst precursor;

[0058] 5) The precursor after step 5) is impregnated with potassium hydroxide aqueous solution, dried and then reduced in pure hydrogen at 350 ℃ for 12 hours to obtain a 15K-3Co-15Fe / C catalyst sample, in which the mass ratio of iron metal to graphitized active carbon is 0.15:1, the mass ratio of cobalt metal to graphitized active carbon is 0.03:1, and the mass ratio of potassium to graphitized active carbon is 0.15:1.

[0059] Comparative Example 1:

[0060] 1) The active carbon is heat-treated in nitrogen (1000 mL / min) at 1800 ℃ for 2 hours, then cooled to room temperature, and then oxidized and expanded in 100 mL / min of air at 400 ℃ for 24 hours to obtain graphitized active carbon;

[0061] 2) The obtained graphitized active carbon is impregnated with a melamine solution, in which the mass ratio of melamine to graphitized active carbon used is 0.05:1;

[0062] 3) The sample after step 2) was impregnated with an appropriate amount of aqueous ferric nitrate solution, dried and then reduced in pure H2 at 500 ℃ for 6 hours to obtain a graphitized activated carbon supported iron catalyst;

[0063] 4) The graphitized activated carbon supported iron catalyst obtained in step 3) was impregnated with an aqueous potassium hydroxide solution, dried and then reduced in pure hydrogen at 450 ℃ for 6 hours to obtain a 5K-10Fe / C-H catalyst sample, in which the mass ratio of iron metal to graphitized activated carbon was 0.1:1 and the mass ratio of potassium to graphitized activated carbon was 0.05:1.

[0064] Comparative Example 2:

[0065] 1) Activated carbon was heat treated in nitrogen (1000 mL / min) at 1800 ℃ for 2 hours, then cooled to room temperature, and then oxidized in 100 mL / min of air at 400 ℃ for 24 hours to obtain graphitized activated carbon;

[0066] 2) The obtained graphitized activated carbon was impregnated with a melamine solution, in which the mass ratio of melamine to graphitized activated carbon was 0.05:1;

[0067] 3) The sample after step 2) was impregnated with an appropriate amount of aqueous ferric nitrate solution, dried and then heat treated in pure CO at 500 ℃ for 2 hours to obtain a graphitized activated carbon supported iron catalyst;

[0068] 4) The graphitized activated carbon supported iron catalyst obtained in step 3) was impregnated with an aqueous potassium hydroxide solution, dried and then reduced in pure hydrogen at 450 ℃ for 6 hours to obtain a 5K-10Fe / C catalyst sample, in which the mass ratio of iron metal to graphitized activated carbon was 0.1:1 and the mass ratio of potassium to graphitized activated carbon was 0.05:1.

[0069] Comparative Example 3:

[0070] 1) Activated carbon was heat treated in nitrogen (1000 mL / min) at 1800 ℃ for 2 hours, then cooled to room temperature, and then oxidized in 100 mL / min of air at 400 ℃ for 24 hours to obtain graphitized activated carbon;

[0071] 2) The obtained graphitized activated carbon was impregnated with an appropriate amount of aqueous ferric nitrate solution, followed by impregnation with an appropriate amount of aqueous cobalt nitrate solution, and then dried and reduced in pure hydrogen at 450 ℃ for 6 hours to obtain a graphitized activated carbon supported iron-cobalt bimetallic catalyst precursor;

[0072] 3) The precursor after cooling in step 2) is impregnated with potassium hydroxide aqueous solution, dried and reduced in pure hydrogen at 450 ℃ for 6 hours to obtain a 5K-2Co-10Fe / C-H catalyst sample, in which the mass ratio of iron metal to graphitized active carbon is 0.1:1, the mass ratio of cobalt metal to graphitized active carbon is 0.02:1, and the mass ratio of potassium to graphitized active carbon is 0.05:1.

[0073] Comparative Example 4:

[0074] 1) The active carbon is impregnated with a melamine solution, in which the mass ratio of melamine to active carbon used is 0.05:1;

[0075] 2) The sample after treatment in step 1) is impregnated with an appropriate amount of iron nitrate aqueous solution, dried and heat-treated in pure CO at 500 ℃ for 2 hours to obtain an active carbon supported iron catalyst;

[0076] 3) The prepared active carbon supported iron catalyst is impregnated with an appropriate amount of cobalt nitrate aqueous solution, dried and reduced in pure hydrogen at 450 ℃ for 6 hours to obtain an active carbon supported iron-cobalt bimetallic catalyst precursor;

[0077] 4) The precursor after cooling in step 3) is impregnated with potassium hydroxide aqueous solution, dried and reduced in pure hydrogen at 450 ℃ for 6 hours to obtain a 5K-2Co-10Fe / AC catalyst sample, in which the mass ratio of iron metal to active carbon is 0.1:1, the mass ratio of cobalt metal to active carbon is 0.02:1, and the mass ratio of potassium to active carbon is 0.05:1.

[0078] Comparative Example 5:

[0079] 1) The active carbon is heat-treated in nitrogen (1000 mL / min) at 1800 ℃ for 2 hours, then cooled to room temperature, and then oxidized and hole-enlarged in 100 mL / min of air at 400 ℃ for 24 hours to obtain graphitized active carbon;

[0080] 2) The obtained graphitized active carbon is impregnated with a melamine solution, in which the mass ratio of melamine to graphitized active carbon used is 0.05:1;

[0081] 3) The sample after treatment in step 2) is impregnated with an appropriate amount of iron nitrate aqueous solution, dried and heat-treated in pure CO at 500 ℃ for 2 hours to obtain a graphitized active carbon supported iron catalyst;

[0082] 4) The prepared graphitized activated carbon supported iron catalyst was impregnated with an appropriate amount of aqueous cobalt nitrate solution, dried, and then reduced in pure hydrogen at 450 °C for 6 hours to obtain a 2Co-10Fe / C catalyst sample, in which the mass ratio of iron metal to graphitized activated carbon was 0.1:1 and the mass ratio of cobalt metal to graphitized activated carbon was 0.02:1.

[0083] Figure 1 HADDF-STEM images and particle size distribution diagrams of the 5K-10Fe / C-H catalyst (a) obtained in Comparative Example 1 and the 5K-2Co-10Fe / C catalyst (b) obtained in Example 1. As can be seen from the images, compared with Comparative Example 1, the size of the iron metal particles in the catalyst prepared by heat treating the graphitized activated carbon supported iron catalyst with CO and introducing Co in Example 1 is significantly reduced, and the average particle size is reduced from 27.8 nm of the 5K-10Fe / C-H catalyst to 8.1 nm, which is close to the particle size (26.9 and 9.2 nm) measured by O2 chemisorption in Table 1. At the same time, the O2 chemisorption results of the catalysts show that when the iron addition amount is the same, the iron particle size of the catalyst treated with CO is lower, indicating that the difference in catalyst treatment conditions is an important factor affecting the iron particle size.

[0084] Figure 2 Mossbauer spectra of the 5K-10Fe / C-H catalyst (a) obtained in Comparative Example 1 and the 5K-2Co-10Fe / C catalyst (b) obtained in Example 1. As can be seen from the images, in the 5K-10Fe / C-H catalyst, only α-Fe (93.3%) and a small amount of γ-Fe (6.7%) phases exist. In the 5K-2Co-10Fe / C catalyst, α-Fe (32.8%) and a large amount of superparamagnetic iron oxide (Fe 3+ )(25.7%) are detected at the same time; in addition, the Mossbauer spectrum characterization shows that there is a significant magnetic relaxation phenomenon in the catalyst, which indicates that there are multiple Fe active sites with different interactions with the Co component in the 5K-2Co-10Fe / C catalyst. Smaller iron particle size and a larger variety of active sites can play a role in the activation, reaction and ammonia desorption steps of nitrogen and hydrogen, respectively, thus improving the ammonia synthesis activity of the catalyst.

[0085] The ammonia synthesis catalysts obtained in the examples and comparative examples were evaluated for catalytic activity in a high-pressure activity test device. During the test, 0.3 g of the catalyst was mixed with quartz sand and packed in the isothermal zone of the reactor. The reaction gas was a nitrogen and hydrogen mixture obtained by high-temperature catalytic cracking of ammonia, and the hydrogen to nitrogen ratio was 3:1; the reaction conditions were: pressure 1 MPa, reaction temperature 400 °C, reaction space velocity 3.6x10 4 cm3 g -1 h -1 The results of the catalytic activity determination are shown in Table 1.

[0086] Table 1

[0087]

[0088] As shown in Table 1, the ammonia synthesis rate of the catalyst prepared without Co or K and without introducing carbon-containing organic matter or without graphitization is low, and under the same conditions, the ammonia synthesis rate of the iron-cobalt bimetallic catalyst supported on the graphitized activated carbon obtained in the examples is obviously higher than that of the catalyst obtained in the comparative examples, which proves that the catalyst has good ammonia synthesis catalytic activity and good application prospect.

[0089] The above description is only the preferred embodiments of the present application, and any equivalent changes and modifications made within the scope of the patent application of the present application shall be included in the scope of the present application.

Claims

1. A preparation method of a graphitized activated carbon supported iron-cobalt bimetallic catalyst for synthesizing ammonia, the catalyst being composed of graphitized activated carbon as a carrier, iron and cobalt bimetallic as active components, and potassium as an additive, characterized in that: The method comprises the following steps: ​ 1) heat-treating activated carbon at high temperature in an inert atmosphere, cooling to room temperature, and then transferring to an air atmosphere to perform oxidation and pore expansion, to obtain graphitized activated carbon; 2) introducing carbon-containing organic matter into the graphitized activated carbon by a solution impregnation method; 3) immersing the graphitized activated carbon with introduced carbon-containing organic matter obtained in step 2) into an iron precursor solution, and then performing heat treatment in a CO-containing mixed gas, to obtain a graphitized activated carbon loaded iron catalyst; 4) impregnating the graphitized activated carbon loaded iron catalyst obtained in step 3) with a cobalt precursor solution, drying, and then reducing, to obtain a graphitized activated carbon loaded iron-cobalt bimetallic catalyst precursor; 5) immersing the graphitized activated carbon loaded iron-cobalt bimetallic catalyst precursor obtained in step 4) into a potassium precursor solution, drying, and then reducing, to obtain the graphitized activated carbon loaded iron-cobalt bimetallic catalyst; wherein the mass ratio of iron to graphitized activated carbon is 0.05:1-0.3:1, the mass ratio of cobalt to graphitized activated carbon is 0.01:1-0.09:1, and the mass ratio of potassium to graphitized activated carbon is 0.02:1-0.2:1; The carbon-containing organic matter in step 2) is any one of sucrose, glucose, and melamine.

2. The preparation method of a graphitized activated carbon supported iron-cobalt bimetallic catalyst for synthesizing ammonia according to claim 1, characterized in that: In step 1), the inert atmosphere is one or more of nitrogen and a Group 0 gas; the high-temperature heat treatment is performed at a temperature of 1500-2000 ℃ for 1-10 hours; and the oxidation and pore expansion is performed at a temperature of 200-500 ℃ for 3-48 hours.

3. The preparation method of a graphitized activated carbon supported iron-cobalt bimetallic catalyst for synthesizing ammonia according to claim 1, characterized in that: The carbon-containing organic matter in step 2) is used in an amount with a mass ratio to graphitized activated carbon of 0.01:1-0.1:

1.

4. The preparation method of a graphitized activated carbon supported iron-cobalt bimetallic catalyst for synthesizing ammonia according to claim 1, characterized in that: The iron precursor solution in step 3) is a ferric nitrate solution or a ferric chloride solution; the CO-containing mixed gas is a mixed gas of CO and nitrogen or a Group 0 gas, wherein the volume content of CO is 3-100%; and the heat treatment is performed at a temperature of 200-600 ℃ for 0.5-20 hours.

5. The preparation method of a graphitized activated carbon supported iron-cobalt bimetallic catalyst for synthesizing ammonia according to claim 1, characterized in that: The cobalt precursor solution in step 4) is an aqueous cobalt nitrate solution.

6. The preparation method of a graphitized activated carbon supported iron-cobalt bimetallic catalyst for synthesizing ammonia according to claim 1, characterized in that: The potassium precursor solution in step 5) is obtained by dissolving potassium hydroxide or potassium nitrate in one or more of water, methanol, and ethanol.

7. The preparation method of a graphitized activated carbon supported iron-cobalt bimetallic catalyst for synthesizing ammonia according to claim 1, characterized in that: The reduction in steps 4) and 5) is performed in a hydrogen-containing gas at a temperature of 200-600 ℃ for 0.2-48 hours, and the hydrogen-containing gas is a mixed gas of hydrogen and nitrogen or a Group 0 gas, wherein the volume content of hydrogen is 1%-100%.

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