Ruthenium cluster catalyst supported on trivalent rare earth oxide, preparation method and application thereof

Abstract

The present invention belongs to the field of advanced material technologies, relates to the preparation of hydrogen production catalysts, and specifically relates to a ruthenium cluster catalyst supported on trivalent rare earth oxides, its preparation method and application. A trivalent rare earth oxide is used as a support to load ruthenium clusters, the main particle size of the ruthenium clusters is 0.5 - 2.0 nm, and the trivalent rare earth oxide is Sm<subgt;2< / subgt;O<subgt;3< / subgt;. The preparation method is as follows: dissolve a ruthenium salt in ethylene glycol, add an alkali metal hydroxide, disperse evenly, heat under reflux to obtain a Ru colloidal solution; mix the Ru colloidal solution with a dispersion of Sm<subgt;2< / subgt;O<subgt;3< / subgt> evenly, carry out aging, wash, dry and heat-treat the aged precipitate to obtain the product; wherein, the temperature of the heat treatment is 300 - 400 °C. By means of appropriate interaction between Ru and the trivalent rare earth oxide, the atomic utilization efficiency of Ru is improved in the present invention, so as to realize stable and efficient catalytic ammonia decomposition for hydrogen production.

Description

Technical Field

[0001] The present invention belongs to the technical field of advanced materials, and relates to the preparation of hydrogen production catalysts, in particular to a ruthenium cluster catalyst supported on trivalent rare earth oxides, its preparation method and application. Background Art

[0002] Disclosing the information of this background art section is only intended to increase the understanding of the overall background of the present invention, and is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Ammonia decomposition High-purity hydrogen can be prepared, and at the same time, problems such as difficulties in hydrogen storage and transportation can be effectively solved. Improving the low-temperature activity of ammonia decomposition mainly relies on the creation of efficient catalysts. According to the inventor's research and understanding, currently, among the active metals for catalyzing ammonia decomposition, Ru has the highest activity, but its price is expensive and it is difficult to be widely used. Therefore, it is necessary to develop a Ru cluster catalyst with high low-temperature activity to improve the atomic utilization rate of Ru.

[0004] However, due to the high price of Ru, the current catalyst dosage is high and the utilization rate is low. It is urgent to find a suitable carrier and preparation method to improve the atomic utilization efficiency of Ru in order to further improve the efficiency of hydrogen production by ammonia decomposition. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a catalyst of ruthenium clusters supported on trivalent rare earth oxides, its preparation method and application. The present invention uses trivalent rare earth oxides as the catalyst carrier, first prepares highly dispersed single-atom Ru species, and then constructs uniformly dispersed Ru nanoclusters in situ through the high-temperature reduction reaction conditions of ammonia decomposition. Through the appropriate interaction between Ru and trivalent rare earth oxides, the atomic utilization efficiency of Ru is improved, thereby realizing stable and efficient catalytic hydrogen production by ammonia decomposition.

[0006] In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0007] On the one hand, a ruthenium cluster catalyst supported on trivalent rare earth oxides, with trivalent rare earth oxides as the carrier to support ruthenium clusters, and the main particle size of the ruthenium clusters is 0.5 - 2.0 nm.

[0008] Rare earth elements have 4f electron orbits with an orderly change from completely empty to completely full, enabling some rare earth oxides to have unique electronic structures and physicochemical properties. The inventor developed a Ru / CeO2 catalyst in previous research, which has high catalytic activity. CeO2 exhibits unique redox properties due to the reversible conversion of Ce(III) and Ce(IV) in its crystal structure and the resulting abundant surface oxygen vacancies. Using nano-CeO2 as a carrier, due to its unique surface structure and adsorption characteristics, a stable and chemically active heterogeneous interface can be formed with the catalytically active component. Trivalent rare earth oxides (RE2O3), such as Y2O3, Sm2O3, etc., have a stable structure and generally do not undergo valence changes, presenting structural properties different from those of CeO2.

[0009] However, the present invention surprisingly discovers that a catalyst with a trivalent rare earth oxide as a carrier loading ruthenium clusters can significantly improve the conversion rate of NH3, far higher than the catalytic activity of a catalyst with alumina as a carrier loading ruthenium clusters. Its catalytic activity is basically the same as that of a catalyst with a reducible rare earth oxide CeO2 as a carrier loading Ru, and even higher than that of a catalyst with CeO2 as a carrier loading Ru. This is because it has an irregular hexagonal zigzag vacancy structure composed of three 5-coordinated rare earth atoms and three 4-coordinated oxygen atoms. The formation of this vacancy is due to the exposure of surface rare earth ions and the special atomic arrangement of its crystal, and does not depend on the valence change of rare earth ions. At the same time, this vacancy is an electrophilic center and has a moderate adsorption strength and activation ability for molecules with electron-rich cations.

[0010] On the other hand, a preparation method of a catalyst with the above-mentioned trivalent rare earth oxide loading ruthenium clusters is to dissolve a ruthenium salt in ethylene glycol, add an alkali metal hydroxide, disperse evenly, heat under reflux to obtain a Ru colloidal solution;

[0011] Mix the Ru colloidal solution evenly with the dispersion of the trivalent rare earth oxide, carry out aging, wash and dry the aged precipitate, perform a first heat treatment under an air atmosphere condition, and then perform a second heat treatment under a reducing atmosphere condition to obtain it; wherein, the temperature of the first heat treatment is 300 - 400 °C, and the temperature of the second heat treatment is 300 - 600 °C.

[0012] In the present invention, by using a trivalent rare earth oxide as a catalyst carrier, highly dispersed single-atom Ru species are first prepared on the carrier surface by the colloidal deposition method, and then uniformly dispersed Ru nanoclusters with a main particle size of 0.5 - 2.0 nm are in-situ constructed on the carrier surface through high-temperature reducing reaction conditions, enabling stable and efficient catalytic hydrogen production by ammonia decomposition to be achieved through appropriate interactions between the Ru nanoclusters and the trivalent rare earth oxide in the prepared catalyst.

[0013] In a third aspect, there is provided an application of the above-mentioned ruthenium cluster catalyst supported on trivalent rare earth oxide in the catalytic decomposition of ammonia to produce hydrogen.

[0014] The beneficial effects of the present invention are as follows:

[0015] In the present invention, a trivalent rare earth oxide is selected as a support to load ruthenium clusters with a main particle size of 0.5 - 2.0 nm. Through the synergistic effect of the ruthenium clusters and the trivalent rare earth oxide, the composite catalyst has better catalytic activity. Research shows that the H2 production rate can reach 2000 - 2400 mmol g Ru -1 min -1 (at 450 °C, GHSV = 30,000 cm 3 g cat -1 h -1 ), which is 2 - 20 times higher than that of other existing Ru-based catalysts. At the same time, the stability results of the catalyst of ruthenium clusters supported on trivalent rare earth oxide provided by the present invention show that there is no obvious attenuation after 400 h of long-term testing and 6 cycles of testing, that is, it has very good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The attached drawings forming a part of the present specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0017] Figure 1 It is the in-situ XAFS result diagram under 10% NH3 / Ar atmosphere in the embodiment of the present invention, showing the coordination situation of Ru in the Ru / Sm2O3 catalyst;

[0018] Figure 2 It is the TEM image of the newly prepared catalyst in the embodiment of the present invention, (a) Ru / Sm2O3, (b) Ru / Y2O3, (c) Ru / Gd2O3, (d) Ru / Al2O3;

[0019] Figure 3 It is the HRTEM image and particle size distribution diagram of each catalyst after the reaction in the embodiment of the present invention, (a) HRTEM image of the Ru / Sm2O3 catalyst sample after the reaction, (b) HRTEM image of the Ru / Y2O3 catalyst sample after the reaction, (c) HRTEM image of the Ru / Gd2O3 catalyst sample after the reaction, (d) HRTEM image of the Ru / Al2O3 catalyst sample after the reaction, (e) particle size distribution of Ru clusters in the Ru / Sm2O3 catalyst sample after the reaction, (f) particle size distribution of Ru clusters in the Ru / Y2O3 catalyst sample after the reaction, (g) particle size distribution of Ru clusters in the Ru / Gd2O3 catalyst sample after the reaction, (h) particle size distribution of Ru clusters in the Ru / Al2O3 catalyst sample after the reaction;

[0020] Figure 4 This is the HAADF-STEM image of Ru / Sm2O3 after reaction in the embodiments of the present invention. (a) Low-magnification pixel HAADF-STEM image of aberration-corrected Ru / Sm2O3, (b) Medium-magnification pixel HAADF-STEM image of aberration-corrected Ru / Sm2O3, (c) High-magnification pixel HAADF-STEM image of aberration-corrected Ru / Sm2O3. Detailed implementation manners

[0021] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0022] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] In view of the currently low atomic utilization efficiency of Ru and the need to further improve the efficiency of ammonia decomposition for hydrogen production, the present invention provides a ruthenium cluster catalyst supported on trivalent rare earth oxides, its preparation method and application.

[0024] A typical embodiment of the present invention provides a ruthenium cluster catalyst supported on trivalent rare earth oxides, with the trivalent rare earth oxides as the carrier to support ruthenium clusters, and the main particle size of the ruthenium clusters is 0.5 - 2.0 nm.

[0025] The trivalent rare earth oxides described in the present invention include but are not limited to Sm2O3, Y2O3, Gd2O3, etc. In some embodiments, the trivalent rare earth oxide is Sm2O3. After Sm2O3 supports ruthenium clusters, its specific surface area is lower than that of CeO2 supporting ruthenium clusters. The specific surface area affects the catalytic activity of the catalyst. Generally speaking, the larger the specific surface area, the more beneficial it is to improve the catalytic activity. However, the present invention unexpectedly finds through experiments that although the specific surface area of Sm2O3 supporting ruthenium clusters is smaller than that of CeO2 supporting ruthenium clusters, its catalytic activity is higher than that of the catalyst of CeO2 supporting ruthenium clusters. Preferably, Sm2O3 is rod-shaped.

[0026] In some embodiments, the loading amount of ruthenium clusters is 0.7 - 1.1 wt.%.

[0027] In some embodiments, the particle size of the catalyst is 20 - 40 mesh.

[0028] Another embodiment of the present invention provides a method for preparing the above-mentioned ruthenium cluster catalyst supported on trivalent rare earth oxide. Dissolve ruthenium salt in ethylene glycol, add alkali metal hydroxide, disperse evenly, and heat under reflux to obtain a Ru colloidal solution.

[0029] Mix the Ru colloidal solution with the dispersion of trivalent rare earth oxide evenly, age, wash and dry the aged precipitate, and conduct the first heat treatment under an air atmosphere condition, and then conduct the second heat treatment under a reducing atmosphere condition to obtain the product. Among them, the temperature of the first heat treatment is 300 - 400 °C, and the temperature of the second heat treatment is 300 - 600 °C.

[0030] The ruthenium salt in the present invention is a compound with a trivalent ruthenium ion as the cation, such as RuCl3, etc.

[0031] The reducing atmosphere in the present invention is a gas atmosphere formed by reducing gases, and the reducing gases can be H2, CO, NH3, etc.

[0032] In some embodiments, the molar ratio of ruthenium element to alkali metal hydroxide is 1:4 - 6. Preferably 1:5.0 - 6.0, and more preferably 1:5.4 - 5.6.

[0033] In some embodiments, the temperature of heating under reflux is 150 - 180 °C.

[0034] In some embodiments, the preparation process of the dispersion of trivalent rare earth oxide is to add trivalent rare earth oxide to water and disperse it by ultrasonic wave.

[0035] In some embodiments, the aging time is 10 - 15 h.

[0036] In some embodiments, the time of the first heat treatment is 1 - 2 h.

[0037] In some embodiments, the time of the second heat treatment is 1 - 2 h.

[0038] The third embodiment of the present invention provides an application of the above-mentioned ruthenium cluster catalyst supported on trivalent rare earth oxide in the catalytic decomposition of ammonia to produce hydrogen.

[0039] Specifically, under the condition of 300 - 550 °C, use the catalyst of ruthenium cluster supported on trivalent rare earth oxide to catalyze the decomposition of NH3.

[0040] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the following will specifically describe the technical solution of the present invention with specific embodiments.

[0041] Example 1

[0042] The catalyst is prepared by the colloidal deposition method:

[0043] Synthesis method of ruthenium (Ru) colloidal solution: Dissolve 0.15 g of RuCl3 in 50 mL of ethylene glycol (C2H6O2), add 0.16 g of NaOH, continuously stir for 30 min until evenly dispersed, then place it in an oil bath at 160 °C and reflux for 3 h, and then cool to room temperature to obtain a dark brown Ru colloidal solution.

[0044] Synthesis method of Ru / Sm2O3 catalyst: Take 1 g of Sm2O3 as the carrier and ultrasonically stir and disperse it in 25 mL of deionized water, then add 10 mL of Ru colloid to this mixture, and keep stirring for 48 h. After stopping stirring, let it stand for aging for 12 h, and then collect the precipitate and wash it by centrifugation. The obtained product is dried at 60 °C for 48 h, first treated at 300 °C for 1 h in an air-flowing atmosphere, and then treated at 550 °C for 1 h in a pure NH3 atmosphere to obtain Ru / Sm2O3.

[0045] Example 2

[0046] The catalyst is prepared by the colloidal deposition method:

[0047] Synthesis method of ruthenium (Ru) colloidal solution: Dissolve 0.15 g of RuCl3 in 50 mL of ethylene glycol (C2H6O2), add 0.16 g of NaOH, continuously stir for 30 min until evenly dispersed, then place it in an oil bath at 160 °C and reflux for 3 h, and then cool to room temperature to obtain a dark brown Ru colloidal solution.

[0048] Synthesis method of Ru / Y2O3 catalyst: Take 1 g of Y2O3 as the carrier and ultrasonically stir and disperse it in 25 mL of deionized water, then add 10 mL of Ru colloid to this mixture, and keep stirring for 48 h. After stopping stirring, let it stand for aging for 12 h, and then collect the precipitate and wash it by centrifugation. The obtained product is dried at 60 °C for 48 h, first treated at 300 °C for 1 h in an air-flowing atmosphere, and then treated at 550 °C for 1 h in a pure NH3 atmosphere to obtain Ru / Y2O3.

[0049] Example 3

[0050] The catalyst is prepared by the colloidal deposition method:

[0051] Synthesis method of ruthenium (Ru) colloidal solution: Dissolve 0.15 g of RuCl3 in 50 mL of ethylene glycol (C2H6O2), add 0.16 g of NaOH, continuously stir for 30 min until evenly dispersed, then place it in an oil bath at 160 °C and reflux for 3 h, and then cool to room temperature to obtain a dark brown Ru colloidal solution.

[0052] Synthesis method of Ru / Gd2O3 catalyst: 1 g of Gd2O3 was used as a carrier and ultrasonically stirred and dispersed in 25 mL of deionized water. Then, 10 mL of Ru colloid was added to the mixture, and stirring was maintained for 48 h. After stopping stirring, it was left to age for 12 h, and then the precipitate was collected and centrifuged and washed. The obtained product was dried at 60 °C for 48 h, first treated at 300 °C for 1 h in a flowing air atmosphere, and then treated at 550 °C for 1 h in a pure NH3 atmosphere to obtain Ru / Gd2O3.

[0053] Example 4

[0054] The catalyst was prepared by the colloid deposition method:

[0055] Synthesis method of ruthenium (Ru) colloid solution: 0.15 g of RuCl3 was dissolved in 50 mL of ethylene glycol (C2H6O2), 0.16 g of NaOH was added, and stirring was continued for 30 min until evenly dispersed. Then, it was placed in an oil bath at 160 °C and refluxed for 3 h and then cooled to room temperature to obtain a dark brown Ru colloid solution.

[0056] Synthesis method of Ru / CeO2 catalyst: 1 g of CeO2 was used as a carrier and ultrasonically stirred and dispersed in 25 mL of deionized water. Then, 10 mL of Ru colloid was added to the mixture, and stirring was maintained for 48 h. After stopping stirring, it was left to age for 12 h, and then the precipitate was collected and centrifuged and washed. The obtained product was dried at 60 °C for 48 h, first treated at 300 °C for 1 h in a flowing air atmosphere, and then treated at 550 °C for 1 h in a pure NH3 atmosphere to obtain Ru / CeO2.

[0057] Example 5

[0058] The catalyst was prepared by the colloid deposition method:

[0059] Synthesis method of ruthenium (Ru) colloid solution: 0.15 g of RuCl3 was dissolved in 50 mL of ethylene glycol (C2H6O2), 0.16 g of NaOH was added, and stirring was continued for 30 min until evenly dispersed. Then, it was placed in an oil bath at 160 °C and refluxed for 3 h and then cooled to room temperature to obtain a dark brown Ru colloid solution.

[0060] Synthesis method of Ru / Al2O3 catalyst: 1 g of Al2O3 was used as a carrier and ultrasonically stirred and dispersed in 25 mL of deionized water. Then, 10 mL of Ru colloid was added to the mixture, and stirring was maintained for 48 h. After stopping stirring, it was left to age for 12 h, and then the precipitate was collected and centrifuged and washed. The obtained product was dried at 60 °C for 48 h, first treated at 300 °C for 1 h in a flowing air atmosphere, and then treated at 550 °C for 1 h in a pure NH3 atmosphere to obtain Ru / Al2O3.

[0061] Catalyst performance test:

[0062] During the performance test, 50 mg of the catalyst (20 - 40 mesh) was mixed with 500 mg of quartz sand (20 - 40 mesh), and then loaded into a reaction tube with an inner diameter of 6 mm. The conversion test was carried out between 300 and 550 °C, and a data point was collected at intervals of 50 °C for the reactor temperature (GHSV = 30,000 cm 3 ·g cat -1 ·h -1 ). The outlet gas was analyzed by an on-line gas chromatograph (Ouhua GC 9160), and then the real-time contents of N2 and NH3 were obtained. The conversion rate of NH3 was calculated by Equation 1.

[0063]

[0064] Wherein, represents the conversion rate of NH3, represents the molar amount of N2 at the outlet, represents the molar amount of NH3 at the outlet.

[0065] The stability test of the catalyst includes long-term stability and cyclic stability tests. The long-term stability test was carried out at 450 °C (GHSV = 36,000 cm 3 ·g cat -1 ·h -1 ) for 400 h. The cyclic stability test was carried out at the same temperature range and space velocity as the activity test. After one round of testing, the temperature was reduced below 300 °C and then reheated for testing, and the cycle was repeated 6 times.

[0066] A series of Ru / RE2O3 (Ru / Sm2O3, Ru / Y2O3, Ru / Gd2O3) catalysts and the reference Ru / Al2O3 catalyst were prepared in the above examples (the Ru content was determined by ICP-MS, about 1 wt.%, Table 1). The coordination of Ru in the Ru / Sm2O3 catalyst was observed by in-situ XAFS results in a 10NH3 / Ar atmosphere, as Figure 1 shown. It was found that at room temperature, only Ru-O coordination was shown, indicating that Ru was highly dispersed in the form of single atoms at this time. As the temperature increased, the appearance of Ru-Ru coordination could be observed. The coexistence of Ru-O coordination and Ru-Ru coordination indicated that Ru was in the state of nano-clusters at this time. During the process from 300 - 500 °C, the proportion of Ru-Ru coordination increased and the proportion of Ru-O coordination decreased, which was the process of surface Ru species gradually aggregating into Ru clusters. And even when the temperature was raised to 500 °C, Ru-O coordination still existed, indicating that the Ru clusters on the Sm2O3 support in this system could exist under high-temperature conditions without deep crystallization and growth, which corroborated the feasibility and stability of the method for preparing Ru clusters by in-situ reduction of Ru single atoms.

[0067] Table 1 Ru content and S in each Ru-based catalyst BET

[0068]

[0069] Characterize the structure and morphology of the catalyst. The TEM ( Figure 2 ) images of the catalysts show that Ru / Sm2O3 and Ru / Gd2O3 have nanorod structures, while Ru / Y2O3 and Ru / Al2O3 have nanosheet and nanoparticle morphologies, respectively. The HRTEM images ( Figure 3 ) of each catalyst after reaction show the presence of very small Ru clusters on the surface of the support. According to the particle size distribution ( Figure 3 e–h), the size of Ru clusters in all catalysts is mainly 0.5–2.0 nm, and the average size is 1.2–1.9 nm. More clear results are shown in the aberration-corrected HAADF-STEM images in Figure 4 , where Ru cluster species can be observed to be uniformly distributed on the surface of the support Sm2O3.

[0070] Test the catalytic performance of the prepared Ru-based catalysts (Ru / Sm2O3, Ru / Y2O3, Ru / Gd2O3, Ru / CeO2 and Ru / Al2O3) and the corresponding pure oxide supports for ammonia decomposition reaction. First, the NH3 conversion rates of the pure oxide materials are very similar and very low, indicating that it is a non-catalytic process in the absence of Ru. For the Ru-loaded catalysts (Table 2), Ru supported on RE2O3 shows similar activity, significantly higher than that of the Ru / Al2O3 catalyst. At 450 °C, the NH3 conversion rate of the Ru / RE2O3 catalysts is 60%–72%, much higher than that of the Ru / Al2O3 catalyst (12.7%, GHSV = 30,000 cm 3 ·g cat -1 ·h -1 ). The results of activation energy tests show that the apparent activation energies (E a ) of Ru / Sm2O3 (102.2 kJ·mol -1 ), Ru / Y2O3 (123.5 kJ·mol -1 ) and Ru / Gd2O3 (105.1 kJ·mol -1 ) are lower than that of Ru / Al2O3 (136.2 kJ·mol -1 ), showing the advantage of the catalysts obtained by loading Ru on rare earth oxides in catalytic conversion of NH3. Interestingly, although the specific surface area (S BET , Table 1) of Ru / RE2O3 is only 1 / 3–1 / 2 of that of Ru / CeO2 (SBET = 106 m 2 ·g -1 ), but the catalytic activities of Ru / Sm2O3 and Ru / CeO2 are almost the same.

[0071] Table 2 Catalytic Activity of Each Ru-Based Catalyst for Ammonia Decomposition Reaction at Different Temperatures

[0072]

[0073] The durability of the Ru / Sm2O3 catalyst was evaluated. The results showed that during the 400 h test, the NH3 conversion rate of the Ru / Sm2O3 catalyst decreased by only 4% (GHSV = 36,000 cm 3 ·g cat -1 ·h -1 ). At the same time, after six cyclic stability tests of the ammonia decomposition reaction, the catalyst could still maintain the same NH3 conversion rate at different temperatures, which also verified its excellent stability.

[0074] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a ruthenium cluster catalyst supported on trivalent rare earth oxide, characterized in that, A trivalent rare earth oxide is used as a carrier to support ruthenium clusters, and the main particle size of the ruthenium clusters is 0.5 - 2.0 nm; The trivalent rare earth oxide is Sm2O3, Y2O3 or Gd2O3; The loading amount of the ruthenium clusters is 0.7 - 1.1 wt.%; Dissolve the ruthenium salt in ethylene glycol, add alkali metal hydroxide, disperse evenly, heat under reflux to obtain a Ru colloidal solution; the molar ratio of ruthenium element to alkali metal hydroxide is 1:4 - 6; the temperature of heating under reflux is 150 - 180 °C; Mix the Ru colloidal solution and the dispersion of the trivalent rare earth oxide evenly, carry out aging, wash and dry the aged precipitate, carry out the first heat treatment under an air atmosphere condition, and then carry out the second heat treatment under a reducing atmosphere condition to obtain; wherein, the temperature of the first heat treatment is 300 - 400 °C, and the temperature of the second heat treatment is 300 - 600 °C.

2. The preparation method of the ruthenium cluster catalyst supported on trivalent rare earth oxide according to claim 1, characterized in that, The trivalent rare earth oxide described is Sm2O3.

3. The preparation method of the ruthenium cluster catalyst supported on trivalent rare earth oxide according to claim 2, characterized in that, Sm2O3 is rod-shaped.

4. The preparation method of the ruthenium cluster catalyst supported on trivalent rare earth oxide according to claim 1, characterized in that, The particle size of the catalyst is 20 - 40 mesh.

5. The preparation method of the ruthenium cluster catalyst supported on trivalent rare earth oxide according to claim 1, characterized in that, The molar ratio of ruthenium element to alkali metal hydroxide is 1:5.0 - 6.

0.

6. The preparation method of the ruthenium cluster catalyst supported on trivalent rare earth oxide according to claim 5, characterized in that, The molar ratio of ruthenium element to alkali metal hydroxide is 1:5.4 - 5.

6.

7. The preparation method of the ruthenium cluster catalyst supported on trivalent rare earth oxide according to claim 1, characterized in that, The aging time is 10 - 15 h.

8. The preparation method of the ruthenium cluster catalyst supported on trivalent rare earth oxide according to claim 1, characterized in that, The first heat treatment time is 1 - 2 h.

9. The preparation method of the ruthenium cluster catalyst supported on trivalent rare earth oxide according to claim 1, characterized in that, The second heat treatment time is 1 - 2 h.

10. Application of a catalyst prepared by the preparation method of the trivalent rare earth oxide-supported ruthenium cluster catalyst according to any one of claims 1 - 9 in catalytic ammonia decomposition to produce hydrogen.

11. Use of the trivalent rare earth oxide supported ruthenium cluster catalyst according to claim 10 in catalytic ammonia decomposition for hydrogen production, characterized in that, Under the condition of 300 - 550 °C, use the trivalent rare earth oxide-supported ruthenium cluster catalyst to catalyze the decomposition of NH3.

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