Nitrogen carrier composition for chemical-looping synthesis of ammonia as well as preparation method and application of nitrogen carrier composition

Abstract

The invention discloses a nitrogen carrier composition for chemical-looping synthesis of ammonia and a preparation method and application thereof, the nitrogen carrier composition comprises the following components by weight: 55-75 wt% of FexMoyMnzN, 20-35 wt% of hydrotalcite-like compound and 3-10 wt% of pseudo-boehmite, in the FexMoyMnzN, x is equal to 0-0.9, z is equal to 0-0.6, and y is less than or equal to 1-(x + z); the preparation method comprises the following steps: adding ferric nitrate, ammonium molybdate and manganous nitrate into a mixed solution of urea and ammonia water, and performing ultrasonic treatment after primary stirring; then adding hydrotalcite and pseudo-boehmite, carrying out secondary stirring and mixing, and carrying out suction filtration to obtain a solid precipitate; drying, naturally cooling to room temperature, grinding into a granular precursor, pyrolyzing in an inert atmosphere, and then naturally cooling to room temperature to obtain a nitrogen carrier composition; the nitrogen carrier composition has the advantages of low nitrogen fixation and nitrogen release reaction temperature and high nitrogen fixation and NH3 synthesis rate.

Description

Technical Field

[0001] The present invention relates to the field of ammonia synthesis, and in particular to a nitrogen-carrying body composition for chemical chain ammonia synthesis, a preparation method and an application thereof. Background Art

[0002] Ammonia is not only an important chemical product and the main raw material of nitrogen fertilizer, but also has been given new meanings such as "energy carrier" and "hydrogen carrier", and its important position in the chemical and energy industries is becoming increasingly prominent. At present, there are two main catalysts for industrial ammonia synthesis: iron-based and improved ruthenium-based. Iron-based catalysts have the advantages of high activity, long life and relatively low cost, but they have the following disadvantages: (1) relatively harsh reaction conditions, reaction temperature 300-550℃, reaction pressure 15.0-32.0MPa; (2) high energy consumption, consuming 1-2% of the world's total energy annually; (3) heavy pollution, CO2 emissions account for more than 2.0% of global CO2 emissions annually; (4) high equipment requirements and large investment. The main features of improved precious metal ruthenium-based catalysts are high activity, high ammonia concentration and wide H2 / N2 range, and they can operate at low temperature (430℃) and low pressure (9.5-10.5MPa). However, ruthenium-based catalysts are expensive and easy to deactivate, which limits their large-scale industrial application. Therefore, designing and developing new non-precious metal-based high-performance catalysts and realizing ammonia synthesis under mild conditions has become one of the most challenging research topics.

[0003] Chemical chaining ammonia synthesis technology, as one of the possible solutions for achieving "green" ammonia synthesis, splits the traditional ammonia synthesis process into two steps: nitridation and ammonia synthesis. Ammonia synthesis is completed by transferring nitrogen and heat between the two reactions using a nitrogen carrier. Compared with the catalytic ammonia synthesis process, the chemical chaining process has the following characteristics: (1) It can be operated under normal pressure conditions and has a simple process flow; (2) It can be used for distributed and small-scale ammonia production, and is easy to synthesize "green ammonia" by electrolyzing water to produce hydrogen in areas with abundant wind power and solar energy; (3) Due to the formation of stable nitrides and oxides, it is easy to start and stop the process and is easy to couple with renewable energy; (4) The reactants, temperature, pressure, etc. of each step, such as nitridation and ammonia synthesis, can be optimized separately. It is considered to be a new ammonia synthesis technology with high efficiency, low energy consumption, and environmental friendliness.

[0004] Chinese patent document CN202011284388.4 discloses a method for simultaneously producing ammonia and synthesis gas using chemical looping technology. The method comprises the following steps: reacting a composite metal oxygen carrier, nitrogen, and a carbon reducing agent to form a nitrogen fixation reaction to produce metal nitrides, metal oxides, and CO; and reacting the metal nitrides and metal oxides with water vapor to produce ammonia and H2, while also producing the composite metal oxygen carrier. This invention synthesizes ammonia under normal pressure and mild conditions, while simultaneously producing CO and H2 in separate steps throughout the cycle. The composite metal oxygen carrier has the molecular formula AxByOz, where A is a main group IA, IIA, or IIIA element, and B is a transition metal element, with x = 1-3, y = 1-5, and z = 2-4. The main group IA, IIA, or IIIA elements are selected from one or more of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, and Al. The transition metal element is selected from one or more of La, V, Ce, Ti, Zn, Cu, Co, Cr, Ce, Ni, Fe, Mn, W, Tc or Yb.

[0005] Chinese patent document CN202210348758.9 discloses a supported molybdenum-based nitrogen carrier suitable for chemical chain ammonia synthesis and a preparation method thereof. The preparation method comprises the following steps: mixing hexamethylenetetramine, molybdate, ammonia water, and ZSM-5 molecular sieve, and filtering to obtain a white precipitate; drying the white precipitate and grinding it to obtain a supported precursor; pyrolyzing the supported precursor under protective atmosphere conditions and cooling it to obtain a supported molybdenum-based nitrogen carrier suitable for chemical chain ammonia synthesis.

[0006] Chinese patent document CN201811079936.2 discloses a chemical chaining method for producing ammonia using an iron-based oxygen carrier. This method achieves continuous and stable ammonia production through the redox reaction of the iron-based oxygen carrier. The method consists of three stages: 1) the oxygen carrier hydrolysis stage, in which water vapor is used in a hydrolysis reactor to hydrolyze iron nitride to produce high-purity ammonia and simultaneously generate iron oxide; 2) the oxygen carrier oxidation stage, in which the iron oxide generated after the hydrolysis reaction enters an air reactor and is further oxidized by air into high-valent Fe2O3 and oxygen-deficient nitrogen; and 3) the oxygen carrier reduction stage, in which nitrogen and coke are used to reduce the iron oxide to iron nitride, simultaneously generating CO or CO2 gas. This method uses water vapor, coke, and nitrogen as raw materials to produce high-quality ammonia while also producing CO gas as a byproduct.

[0007] The existing chemical chain ammonia synthesis technology still has defects such as high reaction temperature and low ammonia synthesis efficiency. Summary of the Invention

[0008] In order to address the deficiencies in the prior art, the present invention aims to provide a nitrogen-carrying composition for chemical chain ammonia synthesis, a preparation method, and an application thereof, thereby producing a novel non-precious metal-based high-performance catalyst, which enables ammonia synthesis under mild conditions with high efficiency.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A nitrogen carrier composition for chemical chain synthesis of ammonia, comprising the following components based on the weight of the composition: 55-75wt% of Fe x Mo y Mn z N, 20-35 wt% of hydrotalcite-like substances, and 3-10 wt% of pseudo-boehmite.

[0011] Preferably, the composition comprises the following components based on the weight of the composition: 60-70 wt% of Fe x Mo y Mn z N, 25-30 wt% of hydrotalcite-like substances, and 5-8 wt% of pseudo-boehmite.

[0012] Preferably, the Fe x Mo y Mn z In N, x=0~0.9, z=0~0.6, y≤1-(x+z).

[0013] Preferably, the hydrotalcite-like compound is one or more of magnesium-aluminum hydrotalcite, magnesium-aluminum-cerium hydrotalcite, magnesium-aluminum-zinc hydrotalcite or magnesium-aluminum-calcium-zinc hydrotalcite.

[0014] The present invention also claims a method for preparing the nitrogen-carrying composition, which is characterized by comprising the following steps:

[0015] Ferric nitrate, ammonium molybdate, and manganese nitrate are sequentially added to a mixed solution of urea and ammonia water, stirred once, and then ultrasonically treated; hydrotalcite and pseudo-boehmite are then added, stirred and mixed a second time, and filtered to obtain a solid precipitate; the solid precipitate is dried, then naturally cooled to room temperature, ground into a granular precursor, and the precursor is pyrolyzed in a nitrogen atmosphere. After the pyrolysis is completed, it is naturally cooled to room temperature to obtain a nitrogen-carrying composition.

[0016] Preferably, the concentration of urea in the mixed solution is 20-30 wt%, the concentration of aqueous ammonia is 8-16 vol%, the stirring time is 2-4 h, and the ultrasonic time is 0.5-2 h.

[0017] Preferably, the secondary stirring time is 4 to 6 hours.

[0018] Preferably, the drying condition is 60-80° C. for 18-24 hours, and the particle size of the precursor particles is 80-350 μm.

[0019] Preferably, the pyrolysis temperature is 550-650° C., and the pyrolysis time is 6-10 h.

[0020] The present invention also claims protection for an application of the nitrogen-carrying body composition in ammonia synthesis based on chemical chaining technology: the nitrogen-carrying body undergoes a nitrogen absorption reaction with N2 in a nitrogen absorption reactor, and then fluidizes into a nitrogen release reactor to react with H2 to release NH3, while simultaneously reducing the nitrogen-carrying body to its initial state, completing the regeneration of the nitrogen-carrying body, and then proceeding to the next nitrogen absorption-release process.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides a nitrogen-carrying body composition for synthesizing ammonia based on chemical chaining technology. The composition uses iron, molybdenum and manganese ternary nitrides as active components and can achieve good nitrogen fixation and ammonia release performance, ammonia production rate and ammonia production amount at relatively low temperatures. The hydrotalcite-like and pseudo-boehmite-like have a special pore structure, high pore volume and specific surface area, and can provide a good dispersion effect for the active components, further improving the nitrogen fixation and ammonia release performance of the active components. The interaction between the pseudo-boehmite and hydrotalcite-like also effectively increases the strength of the nitrogen-carrying body composition. In addition, the nitrogen-carrying body of the present invention can react with H2 to produce ammonia under normal pressure and mild conditions, and is particularly suitable for use in areas with abundant wind power and solar energy. It can be distributed and miniaturized to produce hydrogen through water electrolysis to synthesize "green ammonia", and has strong economic and competitive advantages. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0024] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0025] The present invention provides a nitrogen carrier composition for chemical chain synthesis of ammonia, which comprises the following components based on the weight of the composition: 55-75wt% of Fe x Mo y Mn z N, 20-35 wt% of hydrotalcite-like substances, and 3-10 wt% of pseudo-boehmite.

[0026] Specifically, Fe x Mo y Mn zThe content of N can be 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, 66wt%, 67wt%, 68wt%, 69wt%, 70wt%, 71wt%, 72wt%, 73wt%, 74wt%, 75wt%, preferably 60-70wt%;

[0027] Specifically, the content of hydrotalcite-like substances may be 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, 35wt%, preferably 25-30wt%;

[0028] Specifically, the content of pseudo-boehmite can be 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, preferably 5-8wt%;

[0029] Preferably, the Fe x Mo y Mn z In N, x=0~0.9, z=0~0.6, y≤1-(x+z).

[0030] Specifically, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9; z can be 0.1, 0.2, 0.3, 0.4, 0.5, or 0.6;

[0031] Preferably, the hydrotalcite-like compound is one or more of magnesium-aluminum hydrotalcite, magnesium-aluminum-cerium hydrotalcite, magnesium-aluminum-zinc hydrotalcite or magnesium-aluminum-calcium-zinc hydrotalcite.

[0032] The present invention also claims a method for preparing the nitrogen-carrying composition, which is characterized by comprising the following steps:

[0033] Ferric nitrate, ammonium molybdate, and manganese nitrate are sequentially added to a mixed solution of urea and ammonia water, stirred once, and then ultrasonically treated; hydrotalcite and pseudo-boehmite are then added, stirred and mixed a second time, and filtered to obtain a solid precipitate; the solid precipitate is dried, then naturally cooled to room temperature, ground into a granular precursor, and the precursor is pyrolyzed under an inert atmosphere. After the pyrolysis is completed, it is naturally cooled to room temperature to obtain a nitrogen-carrying composition.

[0034] Specifically, the concentration of urea in the mixed solution is 20-30wt%, which can be 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, or 30wt%;

[0035] Specifically, the concentration of ammonia water is 8-16 vol%, and can be 8 vol%, 9 vol%, 10 vol%, 11 vol%, 12 vol%, 13 vol%, 14 vol%, 15 vol%, or 16 vol%.

[0036] Specifically, the stirring time is 2 to 4 hours, which may be 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours; the ultrasonic time is 0.5 to 2 hours, which may be 0.5 hours, 1 hour, 1.5 hours, or 2 hours.

[0037] Specifically, the secondary stirring time is 4 to 6 hours, which can be 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours;

[0038] Specifically, the drying temperature is 60-80°C, which can be 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C; the drying time is 18-24h, which can be 18h, 19h, 20h, 21h, 22h, 23h, 24h.

[0039] Specifically, the particle size of the precursor particles is 80-350μm, which can be 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 270μm, 280μm, 290μm, 300μm, 310μm, 320μm, 330μm, 340μm, 350μm, or 360μm.

[0040] Preferably, the pyrolysis temperature is 550-650°C, which can be 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C, or 650°C; the pyrolysis time is 6-10h, which can be 6h, 7h, 8h, 9h, or 10h.

[0041] The present invention also claims protection for an application of the nitrogen-carrying body composition in ammonia synthesis based on chemical chaining technology: the nitrogen-carrying body undergoes a nitrogen absorption reaction with N2 in a nitrogen absorption reactor, and then fluidizes into a nitrogen release reactor to react with H2 to release NH3, while simultaneously reducing the nitrogen-carrying body to its initial state, completing the regeneration of the nitrogen-carrying body, and then proceeding to the next nitrogen absorption-release process.

[0042] The present invention will be further described below with reference to specific examples.

[0043] Example 1

[0044] A method for preparing a nitrogen-carrying composition for chemically chaining ammonia synthesis comprises the following steps:

[0045] In a mixed solution of 1500g urea with a concentration of 25wt% and ammonia with a concentration of 12vol%, 129.9g Fe(NO3)3·9H2O (purity 98.5%), 37.8g (NH4)6Mo7O 24 ·4H2O (purity 98.5%) and 135.8g Mn(NO3)2·4H2O (purity 97.5%), stirred for 3h, and then ultrasonicated for 1h; then 40g magnesium aluminum hydrotalcite (dry basis 70wt%) and 7.3g pseudo-boehmite (dry basis 68wt%) were added in sequence, stirred for 5h, and filtered to obtain a solid precipitate; the solid precipitate was dried at 60°C for 20h and then naturally cooled to room temperature, and then ground into a granular precursor with a particle size of 80 to 350μm; the precursor was pyrolyzed at 580°C in a nitrogen atmosphere for 8h, and then naturally cooled to room temperature to obtain the nitrogen-carrying body composition, wherein x=0.3, y=0.2, and z=0.5.

[0046] Example 2

[0047] A method for preparing a nitrogen-carrying composition for chemically chaining ammonia synthesis comprises the following steps:

[0048] In a mixed solution of 1500g urea with a concentration of 25wt% and ammonia with a concentration of 12vol%, 126.0g Fe(NO3)3·9H2O (purity 98.5%), 36.7g (NH4)6Mo7O 24·4H2O (purity 98.5%) and 131.7g Mn(NO3)2·4H2O (purity 97.5%), stirred for 3h, and then ultrasonicated for 1h; then 42.9g magnesium aluminum cerium ternary hydrotalcite (dry basis 70wt%) and 7.3g pseudo-boehmite (dry basis 68wt%) were added in sequence, stirred for 6h, and filtered to obtain a solid precipitate; the solid precipitate was dried at 70℃ for 20h and then naturally cooled to room temperature, and then ground into a granular precursor with a particle size of 80-350μm; the precursor was pyrolyzed at 600℃ in a nitrogen atmosphere for 8h, and then naturally cooled to room temperature to obtain the nitrogen-carrying body composition, wherein x=0.3, y=0.2, and z=0.5.

[0049] Example 3

[0050] A method for preparing a nitrogen-carrying composition for chemically chaining ammonia synthesis comprises the following steps:

[0051] In a mixed solution of 1500g urea with a concentration of 25wt% and ammonia with a concentration of 12vol%, 219.0g Fe(NO3)3·9H2O (purity 98.5%), 38.3g (NH4)6Mo7O 24 ·4H2O (purity 98.5%) and 82.5g Mn(NO3)2·4H2O (purity 97.5%), stirred for 3h, and then ultrasonicated for 1h; then 35.7g magnesium aluminum zinc ternary hydrotalcite (dry basis 70wt%) and 10.3g pseudo-boehmite (dry basis 68wt%) were added in sequence, stirred for 6h, and filtered to obtain a solid precipitate; the solid precipitate was dried at 70°C for 24h and then naturally cooled to room temperature, and then ground into a granular precursor with a particle size of 80 to 350μm; the precursor was pyrolyzed at 620°C in a nitrogen atmosphere for 6h, and then naturally cooled to room temperature to obtain the nitrogen-carrying body composition, wherein x=0.5, y=0.2, and z=0.3.

[0052] Example 4

[0053] A method for preparing a nitrogen-carrying composition for chemically chaining ammonia synthesis comprises the following steps:

[0054] In a mixed solution of 1500g urea with a concentration of 25wt% and ammonia with a concentration of 12vol%, 314.6g Fe(NO3)3·9H2O (purity 98.5%), 39.3g (NH4)6Mo7O 24·4H2O (purity 98.5%) and 28.2g Mn(NO3)2·4H2O (purity 97.5%), stirred for 3h, and then ultrasonicated for 1.5h; then 35.7g magnesium aluminum calcium zinc quaternary hydrotalcite (dry basis 70wt%) and 10.3g pseudo-boehmite (dry basis 68wt%) were added in sequence, stirred for 5h, and filtered to obtain a solid precipitate; the solid precipitate was dried at 75°C for 20h and then naturally cooled to room temperature, and then ground into a granular precursor with a particle size of 80-350μm; the precursor was pyrolyzed at 650°C in a nitrogen atmosphere for 8h, and then naturally cooled to room temperature to obtain the nitrogen-carrying body composition, wherein x=0.7, y=0.2, and z=0.1.

[0055] Example 5

[0056] A method for preparing a nitrogen-carrying composition for chemically chaining ammonia synthesis comprises the following steps:

[0057] In a mixed solution of 1500g urea with a concentration of 25wt% and ammonia with a concentration of 12vol%, 314.6g Fe(NO3)3·9H2O (purity 98.5%), 39.3g (NH4)6Mo7O 24 ·4H2O (purity 98.5%) and 28.2g Mn(NO3)2·4H2O (purity 97.5%), stirred for 3h, and then ultrasonicated for 2h; then 15.4g magnesium aluminum hydrotalcite, 23.1g magnesium aluminum cerium ternary hydrotalcite (dry basis 70wt%) and 12.3g pseudo-boehmite (dry basis 68wt%) were added in sequence, stirred for 6h, and filtered to obtain a solid precipitate; the solid precipitate was dried at 75°C for 24h and then naturally cooled to room temperature, and then ground into a granular precursor with a particle size of 80-350μm; the precursor was pyrolyzed at 600°C in a nitrogen atmosphere for 10h, and then naturally cooled to room temperature to obtain the nitrogen-carrying body composition, wherein x=0.7, y=0.2, and z=0.1.

[0058] Example 6

[0059] A method for preparing a nitrogen-carrying composition for chemically chaining ammonia synthesis comprises the following steps:

[0060] In a mixed solution of 1500g urea with a concentration of 25wt% and ammonia with a concentration of 12vol%, 32.3g Fe(NO3)3·9H2O (purity 98.5%), 85.0g (NH4)6Mo7O 24·4H2O (purity 98.5%) and 61.0g Mn(NO3)2·4H2O (purity 97.5%), stirred for 4h, and then ultrasonicated for 1.5h; then 38.6g magnesium aluminum calcium zinc quaternary hydrotalcite (dry basis 70wt%) and 7.3g pseudo-boehmite (dry basis 68wt%) were added in sequence, stirred for 6h, and filtered to obtain a solid precipitate; the solid precipitate was dried at 80°C for 24h and then naturally cooled to room temperature, and then ground into a granular precursor with a particle size of 80-350μm; the precursor was pyrolyzed at 600°C in a nitrogen atmosphere for 8h, and then naturally cooled to room temperature to obtain the nitrogen-carrying body composition, wherein x=0.1, y=0.6, and z=0.3.

[0061] Example 7

[0062] A method for preparing a nitrogen-carrying composition for chemically chaining ammonia synthesis comprises the following steps:

[0063] In a mixed solution of 1500g urea with a concentration of 25wt% and ammonia with a concentration of 12vol%, 96.9g Fe(NO3)3·9H2O (purity 98.5%), 21.2g (NH4)6Mo7O 24 ·4H2O (purity 98.5%) and 212.6g Mn(NO3)2·4H2O (purity 97.5%), stirred for 4h, and then ultrasonicated for 2.0h; then 14.3g magnesium aluminum cerium hydrotalcite, 21.4g magnesium aluminum calcium zinc quaternary hydrotalcite (dry basis 70wt%) and 7.3g pseudo-boehmite (dry basis 68wt%) were added in sequence, stirred for 6h, and filtered to obtain a solid precipitate; the solid precipitate was dried at 75°C for 22h and then naturally cooled to room temperature, and then ground into a granular precursor with a particle size of 80-350μm; the precursor was pyrolyzed at 620°C in a nitrogen atmosphere for 8h, and then naturally cooled to room temperature to obtain the nitrogen-carrying body composition, wherein x=0.2, y=0.1, and z=0.7.

[0064] Example 8

[0065] A method for preparing a nitrogen-carrying composition for chemically chaining ammonia synthesis comprises the following steps:

[0066] In a mixed solution of 1500g urea with a concentration of 25wt% and ammonia with a concentration of 12vol%, 76.3g Fe(NO3)3·9H2O (purity 98.5%), 16.7g (NH4)6Mo7O 24·4H2O (purity 98.5%) and 167.6g Mn(NO3)2·4H2O (purity 97.5%), stirred for 4h, and then ultrasonicated for 2.0h; then 15.4g magnesium aluminum hydrotalcite, 23.1g magnesium aluminum calcium zinc quaternary hydrotalcite (dry basis 70wt%) and 7.3g pseudo-boehmite (dry basis 68wt%) were added in sequence, stirred for 6h, and filtered to obtain a solid precipitate; the solid precipitate was dried at 75°C for 24h and then naturally cooled to room temperature, and then ground into a granular precursor with a particle size of 80-350μm; the precursor was pyrolyzed at 650°C in a nitrogen atmosphere for 8h, and then naturally cooled to room temperature to obtain the nitrogen-carrying body composition, wherein x=0.2, y=0.1, and z=0.7.

[0067] The nitrogen-carrying compositions prepared in Examples 1 to 8 were subjected to ammonia synthesis performance evaluation test. The test was conducted in a quartz tube fixed-bed reactor with a catalyst mixture loading of 10.0 g. The nitrogen fixation and NH3 release reaction temperatures were both set at 350°C. The nitrogen fixation reaction used 100% nitrogen at a flow rate of 800 mL / min and a reaction time of 45 min. The NH3 release used 50% H2+50% N2 at a flow rate of 800 mL / min and a reaction time of 45 min. The reaction pressure was atmospheric pressure. The amount of NH3 released was analyzed using a Las IR tunable diode laser absorption spectroscopy (TDLAS) gas analysis system. The ammonia synthesis performance of the composition was evaluated by the reaction NH3 production rate in μmol / (g·h). Specific data are shown in Table 1.

[0068] Table 1 Ammonia synthesis performance of nitrogen-carrying composition

[0069] Example <![CDATA[NH3 production rate, μmol / (g·h)]]> Example 1 19652 Example 2 20347 Example 3 28900 Example 4 26756 Example 5 39655 Example 6 30148 Example 7 41055 Example 8 37540

[0070] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A nitrogen-carrying composition for chemical chain synthesis of ammonia, characterized in that: Based on the weight of the composition, the following components are included: 55-75wt% Fe x Mo y Mn z N, 20-35 wt% of hydrotalcite-like substances, and 3-10 wt% of pseudo-boehmite.

2. The nitrogen-carrying composition according to claim 1, characterized in that Based on the weight of the composition, the following components are included: 60-70 wt% of Fe x Mo y Mn z N, 25-30 wt% of hydrotalcite-like substances, and 5-8 wt% of pseudo-boehmite.

3. The nitrogen-carrying composition according to claim 1, characterized in that The Fe x Mo y Mn z In N, x=0~0.9, z=0~0.6, y≤1-(x+z).

4. The nitrogen-carrying composition according to claim 1, characterized in that The hydrotalcite-like substance is one or more of magnesium-aluminum hydrotalcite, magnesium-aluminum-cerium hydrotalcite, magnesium-aluminum-zinc hydrotalcite or magnesium-aluminum-calcium-zinc hydrotalcite.

5. A method for preparing the nitrogen-carrying composition according to any one of claims 1 to 4, characterized in that: The steps include: Ferric nitrate, ammonium molybdate, and manganese nitrate are sequentially added to a mixed solution of urea and ammonia water, stirred once, and then ultrasonically treated; hydrotalcite and pseudo-boehmite are then added, stirred and mixed a second time, and filtered to obtain a solid precipitate; the solid precipitate is dried, then naturally cooled to room temperature, ground into a granular precursor, and the precursor is pyrolyzed in a nitrogen atmosphere. After the pyrolysis is completed, it is naturally cooled to room temperature to obtain a nitrogen-carrying composition.

6. The preparation method according to claim 5, characterized in that The concentration of urea in the mixed solution is 20-30 wt%, the concentration of ammonia water is 8-16 vol%, the stirring time is 2-4 hours, and the ultrasonic time is 0.5-2 hours.

7. The preparation method according to claim 5, characterized in that The secondary stirring time is 4 to 6 hours.

8. The preparation method according to claim 5, characterized in that The drying conditions are drying at 60-80° C. for 18-24 hours, and the particle size of the precursor particles is 80-350 μm.

9. The preparation method according to claim 5, characterized in that The pyrolysis temperature is 550-650°C, and the pyrolysis time is 6-10 hours.

10. Use of the nitrogen-carrying composition according to any one of claims 1 to 4 in ammonia synthesis based on chemical looping technology.