Ammonia cracking catalyst for in-situ dissolution of perovskite oxide and preparation method thereof

Abstract

The invention belongs to the technical field of catalysts, and discloses an ammonia cracking catalyst for perovskite oxide in-situ dissolution and a preparation method. The ammonia cracking catalyst comprises a non-noble metal active component, a perovskite oxide carrier and an alkaline earth metal auxiliary agent, and the non-noble metal active component is distributed on the surface of the perovskite oxide carrier in the form of nanoparticles. The non-noble metal active component is a non-noble metal elementary substance and / or a non-noble metal alloy dissolved in situ from the perovskite oxide, the perovskite oxide carrier is the perovskite oxide after the non-noble metal active component is dissolved in situ, and the alkaline earth metal auxiliary agent is loaded on the perovskite oxide carrier. The ammonia cracking catalyst disclosed by the invention has excellent catalytic activity and stability, can be comparable with the performance of a traditional noble metal ruthenium-based catalyst, and is beneficial to reducing the cost in the field of medium-temperature ammonia decomposition.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and particularly relates to an ammonia cracking catalyst for in-situ dissolution of perovskite oxide and a preparation method thereof. Background Art

[0002] In the context of hydrogen energy development, using ammonia as a hydrogen carrier is one of the ways to solve the current problems of hydrogen storage and transportation. On the application side, ammonia cracking to produce hydrogen is an extremely important link in the field of ammonia energy. Among them, the development of low-cost, highly active, and highly stable ammonia cracking catalysts is one of the current research focuses. Although ruthenium-based catalysts have good catalytic activity below 450°C, the reserves of precious metal ruthenium are limited, and there will be cost issues in industrial applications. Therefore, the development of medium-low temperature and highly efficient non-precious metal catalysts is a top priority.

[0003] At present, most ammonia cracking catalysts are supported catalysts, which are mainly composed of active components, carrier materials and other parts. They are usually prepared by precipitation deposition method and impregnation method, so that the external active components are loaded on the carrier material. For example, alumina is used as a carrier material and impregnated into a Co ion solution. After drying and sintering, the active component Co will be deposited on the carrier material. The catalysts prepared by traditional methods have the following problems: (1) The particle size of the active component metal particles is relatively large, and the reaction active area is low, which makes the catalyst activity low; (2) The bonding strength between the metal particles and the carrier is low, which makes the metal particles easy to fall off under variable operating conditions; (3) During long-term operation, the metal particles are easy to agglomerate, resulting in the performance degradation of the catalyst during long-term operation.

[0004] Therefore, how to reduce the cost of ammonia cracking catalysts and improve catalytic activity and long-term stability is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides an ammonia cracking catalyst for in-situ dissolution of perovskite oxide and a preparation method thereof, wherein the ammonia cracking catalyst does not contain precious metal active components, has low cost, and has excellent catalytic activity and long-term stability.

[0006] In a first aspect, the present invention provides an ammonia cracking catalyst, which includes a non-precious metal active component, a perovskite oxide carrier and an alkaline earth metal additive, wherein the non-precious metal active component is distributed on the surface of the perovskite oxide carrier in the form of nanoparticles, the non-precious metal active component is a non-precious metal element and / or a non-precious metal alloy dissolved in situ from the perovskite oxide, the perovskite oxide carrier is a perovskite oxide after the non-precious metal active component is dissolved in situ, and the alkaline earth metal additive is loaded on the perovskite oxide carrier.

[0007] In some embodiments of the present invention, the chemical formula of the ammonia cracking catalyst is (A 1-x A' x ) z B 1-y B' y O 3-δ , wherein the A and A' elements are independently selected from one or more of La, Pr, Sr, Ca, Mg, and Ba; the B and B' elements are independently selected from one or more of Fe, Co, Ni, Mo, Cr, Cu, Mn, and Nb; 0.2≤x≤0.8, 0.2≤y≤0.8, 0.5≤z≤1; δ represents an oxygen defect.

[0008] In some embodiments of the present invention, the A and A' elements are independently selected from one or more of La, Pr, Sr and Ba.

[0009] In some embodiments of the present invention, the A element is selected from La or Pr, and the A' element is selected from Sr or Ba.

[0010] In some embodiments of the present invention, the B and B' elements are independently selected from one or more of Fe, Co and Ni.

[0011] In some embodiments of the present invention, the B element is selected from Fe or Co, and the B' element is selected from Ni or Fe.

[0012] In some embodiments of the present invention, the non-precious metal active component is one or more of Fe, Co, and Ni elements dissolved in situ from perovskite oxide, and / or an alloy containing at least two elements of Fe, Co, and Ni.

[0013] In some embodiments of the present invention, the alkaline earth metal additive includes one or more of oxides, hydroxides and carbonates of alkaline earth metals.

[0014] In some embodiments of the present invention, the alkaline earth metal additive is a carbonate of an alkaline earth metal.

[0015] In some embodiments of the present invention, the alkaline earth metal additive is strontium carbonate.

[0016] In a second aspect, the present invention provides a method for preparing the ammonia cracking catalyst according to the first aspect of the present invention, wherein the ammonia cracking catalyst is prepared by a sol-gel method or a glycine-nitrate method.

[0017] In some embodiments of the present invention, when the ammonia cracking catalyst is prepared by the sol-gel method, the following steps are included:

[0018] (1) preparing a metal salt solution according to the stoichiometric ratio of the ammonia cracking catalyst, and then mixing it with a complexing agent to obtain a metal salt complex solution;

[0019] (2) adjusting the pH of the metal salt complex solution to alkaline to obtain a precursor solution;

[0020] (3) heating, stirring and drying the precursor solution to obtain a dry gel;

[0021] (4) sintering the dry gel to obtain perovskite oxide;

[0022] (5) The perovskite oxide is placed in a reducing atmosphere for reduction treatment, so that the non-precious metal active components in the perovskite oxide are dissolved in situ to obtain an ammonia cracking catalyst.

[0023] In some embodiments of the present invention, the ratio of the molar amount of the complexing agent to the total molar amount of metal ions in the metal salt solution is (1-3):1.

[0024] In some embodiments of the present invention, the complexing agent comprises citric acid and / or ethylenediaminetetraacetic acid.

[0025] In some embodiments of the present invention, the alkaline pH value is 9-10.

[0026] In some embodiments of the present invention, the specific process of step (3) of the sol-gel method is: heating the precursor solution at a constant temperature and stirring to obtain a wet gel; and then vacuum drying the wet gel to obtain a dry gel.

[0027] In some embodiments of the present invention, the temperature of the constant temperature heating is 80-100° C., and the stirring time is 2-5 h.

[0028] In some embodiments of the present invention, the temperature of the vacuum drying is 160-200° C., and the pressure of the vacuum drying is -0.7 bar to -0.9 bar.

[0029] In some embodiments of the present invention, when the ammonia cracking catalyst is prepared by the glycine-nitrate method, the following steps are included:

[0030] (1) preparing a metal salt solution according to the stoichiometric ratio of the ammonia cracking catalyst, and then mixing it with glycine to obtain a precursor solution;

[0031] (2) heating and stirring the precursor solution to obtain a gel;

[0032] (3) heating the gel, causing the gel to spontaneously combust upon heating to obtain powder;

[0033] (4) sintering the powder to obtain perovskite oxide;

[0034] (5) The perovskite oxide is placed in a reducing atmosphere for reduction treatment, so that the non-precious metal active components in the perovskite oxide are dissolved in situ to obtain an ammonia cracking catalyst.

[0035] In some embodiments of the present invention, the ratio of the molar amount of glycine to the total molar amount of metal ions in the metal salt solution is (1-2.31):1.

[0036] The specific process of step (2) of the glycine-nitrate method is: the precursor solution is heated at a constant temperature of 80-100° C. and stirred for 2-5 hours to obtain a gel.

[0037] In some embodiments of the present invention, the gel is heated to 150-300°C.

[0038] In some embodiments of the present invention, the sintering temperature is 800-1000° C., and the sintering time is 2-5 hours.

[0039] In some embodiments of the present invention, the sintering temperature is 800-900° C., and the sintering time is 4-5 h.

[0040] In some embodiments of the present invention, the reduction temperature is 600-800° C., and the reduction time is 2-8 hours.

[0041] In some embodiments of the present invention, the reduction temperature is 650-750° C., and the reduction time is 2-4 h, preferably 4 h.

[0042] The third aspect of the present invention provides use of the ammonia cracking catalyst described in the first aspect of the present invention in hydrogen production by cracking ammonia.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] (1) The ammonia cracking catalyst provided by the present invention has a more uniform distribution because the non-precious metal active particles distributed on the surface of the perovskite oxide carrier are in-situ precipitated from the perovskite oxide. At the same time, the particle size is smaller than the active particles loaded by the traditional deposition method and impregnation method, the reaction active area is larger, and the catalytic activity is higher. In addition, the non-precious metal active particles of the present invention are more tightly combined with the carrier and have a higher bonding strength, thereby avoiding the problem of performance degradation caused by agglomeration of active particles during the long-term operation of the catalyst and having better stability. In addition, the perovskite oxide carrier of the present invention exhibits Lewis base characteristics, which changes the electronic structure of the active metal, thereby optimizing the catalytic activity of the material, that is, the alkaline earth metals such as Sr and other elements at the A or A' position act as additives, further improving the overall activity of the catalyst.

[0045] (2) The present invention adopts the sol-gel method or the glycine-nitrate method for preparation, and in situ precipitation of non-precious metal particles at the B or B' position of the perovskite oxide can obtain non-precious metal active components, perovskite oxide carriers and alkaline earth metal additives at one time, avoiding traditional repeated impregnation, repeated sintering and other processes, and simplifying the preparation steps.

[0046] (3) The ammonia cracking catalyst prepared by the present invention has excellent catalytic activity and stability. For example, under the conditions of a temperature of 600°C and a space velocity of 30,000 mL / (g·h), the ammonia cracking rate reaches more than 95%. Moreover, after a 100-h stability test, the ammonia cracking rate still remains above 95%, which is comparable to the performance of traditional precious metal ruthenium-based catalysts and is beneficial to reducing costs in the field of medium-temperature ammonia decomposition. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The XRD pattern of the ammonia cracking catalyst prepared in Example 4;

[0048] Figure 2 The SEM images of the perovskite oxide prepared in Example 4 before and after reduction;

[0049] Figure 3 TEM image of the ammonia cracking catalyst prepared in Example 4;

[0050] Figure 4 This is the result of a 100-hour stability test of the ammonia cracking catalyst prepared in Example 4. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below by specific examples. The raw materials, reagents or devices used in the examples can be obtained from conventional commercial sources or by prior art methods unless otherwise specified. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0052] Example 1

[0053] A La 0.6 Sr 0.4 Co 0.2 Ni 0.8 O 3-δ An ammonia cracking catalyst is prepared by a preparation method comprising the following steps:

[0054] (1) According to La 0.6 Sr 0.4 Co 0.2 Ni 0.8 O 3-δThe stoichiometric ratio of the ammonia cracking catalyst is as follows: 5.7704 g of lanthanum nitrate, 1.8802 g of strontium nitrate, 1.2928 g of cobalt nitrate and 5.1668 g of nickel nitrate are added to 200 mL of deionized water, stirred and dissolved to obtain a metal salt solution, and then 17.0682 g of citric acid and 12.9815 g of EDTA are added and stirred to obtain a metal salt complex solution;

[0055] (2) adding ammonia water dropwise to the metal salt complex solution, adjusting the pH value of the solution to 10, and stirring to obtain a precursor solution;

[0056] (3) the precursor solution was heated at 80° C. and stirred for 4 h to obtain a wet gel;

[0057] (4) placing the wet gel in a vacuum drying oven at 180°C and -0.8 bar to further dry and evaporate the water to obtain a dry gel;

[0058] (5) placing the dry gel in a muffle furnace and sintering at 850° C. for 5 h to obtain perovskite oxide;

[0059] (6) The perovskite oxide was placed in a tubular furnace in a hydrogen atmosphere and reduced at 650° C. for 2 h to obtain the ammonia cracking catalyst of this example.

[0060] Example 2

[0061] The only difference from Example 1 is that Example 2 adjusts the types and amounts of raw materials in step (1), specifically: 5.7858 g lanthanum nitrate, 1.8852 g strontium nitrate, 1.7994 g ferric nitrate, 5.1807 g nickel nitrate, 17.1138 g citric acid, and 13.0162 g EDTA; the remaining preparation steps are the same as in Example 1.

[0062] In this embodiment, La 0.6 Sr 0.4 Fe 0.2 Ni 0.8 O 3-δ Ammonia cracking catalyst.

[0063] Example 3

[0064] The only difference from Example 2 is that in Example 3, the reduction time of 2 h in step (6) is adjusted to 4 h; the remaining raw materials, amounts and preparation steps are the same as those in Example 2.

[0065] In this embodiment, La 0.6 Sr 0.4 Fe 0.2 Ni 0.8 O 3-δ Ammonia cracking catalyst.

[0066] Example 4

[0067] The only difference from Example 3 is that Example 4 adjusts the amount of raw materials in step (1), specifically: 5.1744 g lanthanum nitrate, 1.6860 g strontium nitrate, 2.0116 g ferric nitrate, 5.7915 g nickel nitrate, 17.2185 g citric acid, and 13.0958 g EDTA; the remaining preparation steps are the same as Example 3.

[0068] This example prepared (La 0.6 Sr 0.4 ) 0.8 Fe 0.2 Ni 0.8 O 3-δ Ammonia cracking catalyst.

[0069] Example 5

[0070] A Pr 0.5 Ba 0.5 Co 0.8 Fe 0.2 O 3-δ An ammonia cracking catalyst is prepared by a preparation method comprising the following steps:

[0071] (1) According to Pr 0.5 Ba 0.5 Co 0.8 Fe 0.2 O 3-δ The stoichiometric ratio of the ammonia cracking catalyst is as follows: 7.2502 g of praseodymium nitrate, 4.3557 g of barium nitrate, 7.7608 g of cobalt nitrate and 2.6933 g of ferric nitrate are added into 50 mL of deionized water, stirred and dissolved to obtain a metal salt solution, and then 11.55 g of glycine is added and stirred to obtain a precursor solution;

[0072] (2) the precursor solution was heated at 80° C. and stirred for 2 h to obtain a gel;

[0073] (3) heating the gel to 267° C. so that the gel spontaneously combusts when heated, and collecting the ash powder after combustion;

[0074] (4) placing the powder in a muffle furnace and sintering at 850° C. for 4 h to obtain perovskite oxide;

[0075] (5) The perovskite oxide was placed in a tubular furnace in a hydrogen atmosphere and reduced at 750° C. for 4 h to obtain the ammonia cracking catalyst of this embodiment.

[0076] Example 6

[0077] The only difference from Example 5 is that Example 6 adjusts the type and amount of metal salt in step (1), specifically: 7.2502 g praseodymium nitrate, 3.5272 g strontium nitrate, 7.7608 g cobalt nitrate, and 2.6933 g ferric nitrate; the remaining preparation steps are the same as Example 5.

[0078] In this embodiment, Pr 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ Ammonia cracking catalyst.

[0079] Example 7

[0080] The only difference from Example 5 is that Example 7 adjusts the type and amount of metal salt in step (1), specifically: 7.2168 g lanthanum nitrate, 3.5272 g strontium nitrate, 7.7608 g cobalt nitrate, and 2.6933 g ferric nitrate; the remaining preparation steps are the same as Example 5.

[0081] In this embodiment, La 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ Ammonia cracking catalyst.

[0082] Example 8

[0083] The only difference from Example 5 is that Example 8 adjusts the type and amount of the metal salt in step (1), specifically: 8.6602 g lanthanum nitrate, 2.8217 g strontium nitrate, 1.9402 g cobalt nitrate, and 10.7333 g ferric nitrate; the remaining preparation steps are the same as Example 5.

[0084] In this embodiment, La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ Ammonia cracking catalyst.

[0085] Comparative Example 1 (Non-in-situ Nickel Dissolution)

[0086] A Ni-La 0.6 Sr 0.4 CoO 3-δ The preparation steps of ammonia cracking catalyst are as follows:

[0087] (1) According to La 0.6 Sr 0.4 Co 0.2 Ni 0.8 O 3-δThe stoichiometric ratio of the ammonia cracking catalyst is as follows: 5.7662 g of lanthanum nitrate, 1.8788 g of strontium nitrate and 6.4586 g of cobalt nitrate are added to 200 mL of deionized water, and the mixture is stirred to dissolve to obtain a metal salt solution, and then 17.0561 g of citric acid and 12.9723 g of EDTA are added and stirred to obtain a metal salt complex solution;

[0088] (2) adding ammonia water dropwise to the metal salt complex solution, adjusting the pH value of the solution to 10, and stirring to obtain a precursor solution;

[0089] (3) the precursor solution was heated at 80° C. and stirred for 4 h to obtain a wet gel;

[0090] (4) placing the wet gel in a vacuum drying oven at 180°C and -0.8 bar to further dry and evaporate the water to obtain a dry gel;

[0091] (5) The dry gel was placed in a muffle furnace and sintered at 850°C for 5 h to obtain the perovskite oxide La 0.6 Sr 0.4 CoO 3-δ ;

[0092] (6) Weigh 0.6 g NiO and 0.4 g perovskite oxide La obtained in step (5) 0.6 Sr 0.4 CoO 3-δ Add to the ball mill jar, and use ethanol as dispersant in a ball mill at 400 rpm for 1 h;

[0093] (7) The ball-milled material in step (6) was dried and placed in a muffle furnace for reduction at 650°C in a hydrogen atmosphere for 2 h to obtain Ni-La 0.6 Sr 0.4 CoO 3-δ Ammonia cracking catalyst.

[0094] Comparative Example 2 (Non-in-situ Nickel Dissolution)

[0095] The only difference from Comparative Example 1 is that Comparative Example 2 adjusts the NiO and perovskite oxide La in step (6) 0.6 Sr 0.4 CoO 3-δ The dosage is: 0.1g NiO and 0.9g perovskite oxide La 0.6 Sr 0.4 CoO 3-δ ; The remaining preparation steps are the same as those in Comparative Example 1.

[0096] Material characterization and performance testing

[0097] 1. Material Characterization

[0098] Figure 1 The XRD diagram of the ammonia cracking catalyst prepared in Example 4 shows that the ammonia cracking catalyst contains a layered perovskite phase, a strontium carbonate phase, and a Ni3Fe phase, indicating that the present invention can obtain a non-precious metal active component, a perovskite oxide carrier, and an alkaline earth metal additive at one time.

[0099] Figure 2 The SEM images of the perovskite oxide prepared in Example 4 before and after reduction are shown in FIG. Figure 2 As can be seen from a), the surface of the perovskite oxide before reduction is smooth; Figure 2 As can be seen from b), active nanoparticles are precipitated on the surface of the reduced perovskite oxide (ammonia cracking catalyst), proving the occurrence of in situ dissolution. The active nanoparticles are embedded in the surface of the carrier and are tightly bound.

[0100] Figure 3 The TEM image of the ammonia cracking catalyst prepared in Example 4 shows that the average particle size of the ammonia cracking catalyst particles is about 50 nm, and Ni-Fe alloy particles with an average particle size of about 20 nm are distributed on the surface. Figure 2 It is further proved that the present invention enables the B-site metal of the ABO3 type perovskite oxide to dissolve from the lattice under a reducing atmosphere and form a Ni-Fe alloy on the surface of the material.

[0101] 2. Performance Testing

[0102] Ammonia cracking performance test: 0.1g of ammonia cracking catalyst was mixed with gas phase SiO2 and fixed in a glass tube, and ammonia gas was introduced to carry out ammonia cracking performance test. For Examples 1-4 and Comparative Examples 1-2, the measurement conditions were temperature 600°C and space velocity 30000mL / (g·h); for Examples 5-8, the measurement conditions were temperature 600°C and space velocity 18000mL / (g·h). The results are shown in Table 1.

[0103] Table 1

[0104] Example 1 85.1％ Example 2 86.5％ Example 3 94.3％ Example 4 96.1％ Example 5 97.6％ Example 6 91％ Example 7 88％ Example 8 96％ Comparative Example 1 79.4％ Comparative Example 2 69.2％

[0105] As can be seen from Table 1, the ammonia cracking catalyst prepared in the embodiment of the present invention exhibits excellent ammonia cracking catalytic activity, and under the conditions of 600°C and 30000 mL / (g·h), the ammonia cracking rate of Example 4 can reach 96.1%. Compared with the results of Comparative Examples 1-2, the ammonia cracking catalyst prepared in Examples 1-8 exhibits a significantly higher ammonia cracking rate, which is due to the smaller particle size of the active metal of the ammonia cracking catalyst precipitated in situ, the larger effective active area, and the stronger interaction between the metal and the carrier.

[0106] Figure 4The results of the 100-hour stability test of the ammonia cracking catalyst prepared in Example 4 show that, under the conditions of 600°C and 30,000 mL / (g·h), after 100-hour stability test, the ammonia cracking rate remains above 95%. The ammonia cracking catalysts prepared in the remaining examples of the present invention also exhibit similar stability to that of Example 4.

[0107] The preferred embodiments of the present invention are specifically described above, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. An ammonia cracking catalyst, characterized in that: The ammonia cracking catalyst comprises a non-precious metal active component, a perovskite oxide carrier and an alkaline earth metal additive. The non-precious metal active component is distributed on the surface of the perovskite oxide carrier in the form of nanoparticles. The non-precious metal active component is a non-precious metal element and / or a non-precious metal alloy dissolved in situ from the perovskite oxide. The perovskite oxide carrier is a perovskite oxide after the non-precious metal active component is dissolved in situ. The alkaline earth metal additive is loaded on the perovskite oxide carrier.

2. The ammonia cracking catalyst according to claim 1, characterized in that The chemical formula of the ammonia cracking catalyst is (A 1-x A' x ) z B 1-y B' y O 3-δ , wherein the A and A' elements are independently selected from one or more of La, Pr, Sr, Ca, Mg, and Ba; the B and B' elements are independently selected from one or more of Fe, Co, Ni, Mo, Cr, Cu, Mn, and Nb; 0.2≤x≤0.8, 0.2≤y≤0.8, 0.5≤z≤1; δ represents an oxygen defect.

3. The ammonia cracking catalyst according to claim 1, characterized in that The alkaline earth metal additive includes one or more of the oxides, hydroxides and carbonates of alkaline earth metals.

4. The method for preparing the ammonia cracking catalyst according to any one of claims 1 to 3, characterized in that: The ammonia cracking catalyst is prepared by a sol-gel method or a glycine-nitrate method.

5. The preparation method according to claim 4, characterized in that: When the ammonia cracking catalyst is prepared by the sol-gel method, the following steps are included: (1) preparing a metal salt solution according to the stoichiometric ratio of the ammonia cracking catalyst, and then mixing it with a complexing agent to obtain a metal salt complex solution; (2) adjusting the pH of the metal salt complex solution to alkaline to obtain a precursor solution; (3) heating, stirring and drying the precursor solution to obtain a dry gel; (4) sintering the dry gel to obtain perovskite oxide; (5) The perovskite oxide is placed in a reducing atmosphere for reduction treatment, so that the non-precious metal active components in the perovskite oxide are dissolved in situ to obtain an ammonia cracking catalyst.

6. The preparation method according to claim 5, characterized in that: The ratio of the molar amount of the complexing agent to the total molar amount of metal ions in the metal salt solution is (1-3):

1.

7. The preparation method according to claim 4, characterized in that: When the ammonia cracking catalyst is prepared by the glycine-nitrate method, the following steps are included: (1) preparing a metal salt solution according to the stoichiometric ratio of the ammonia cracking catalyst, and then mixing it with glycine to obtain a precursor solution; (2) heating and stirring the precursor solution to obtain a gel; (3) heating the gel, causing the gel to spontaneously combust upon heating to obtain powder; (4) sintering the powder to obtain perovskite oxide; (5) The perovskite oxide is placed in a reducing atmosphere for reduction treatment, so that the non-precious metal active components in the perovskite oxide are dissolved in situ to obtain an ammonia cracking catalyst.

8. The preparation method according to claim 7, characterized in that: The ratio of the molar amount of glycine to the total molar amount of metal ions in the metal salt solution is (1-2.31):

1.

9. The preparation method according to claim 5 or 7, characterized in that: The reduction temperature is 600-800° C., and the reduction time is 2-8 hours.

10. Use of the ammonia cracking catalyst according to any one of claims 1 to 3 in hydrogen production by ammonia cracking.

Images