Modified CeO2 supported ruthenium cluster catalyst as well as preparation method and application thereof

Abstract

The invention discloses a modified CeO2 supported ruthenium cluster catalyst and a preparation method and application thereof, the catalyst is composed of alkaline earth metal modified CeO2 and a supported ruthenium cluster, and the catalyst can be expressed as Rux / [AEy-CeO2], wherein Rux represents a ruthenium atom cluster of which the mass percent is x in the catalyst; [AEy-CeO2] represents an alkaline earth element (such as Mg, Ca, Sr or Ba) modified CeO2 carrier with the mass percent y in the catalyst. In the catalyst provided by the invention, based on the influence of the alkaline earth metal electron auxiliary agent modified CeO2, and by virtue of the strong interaction of CeO2 and the carrier-metal of the ruthenium atom cluster, the catalyst has stronger N-H bond breaking capability, and can effectively inhibit hydrogen poisoning, so that the catalyst can efficiently catalyze and promote ammonia decomposition to produce hydrogen under a low-temperature condition.

Description

Technical Field

[0001] This application belongs to the field of catalyst preparation technology, specifically relating to a modified CeO2-supported ruthenium cluster catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, as a readily available and widely used secondary energy source, can effectively absorb renewable energy, enable controllable peak shaving for the power grid, and facilitate cross-seasonal and cross-regional energy storage. Furthermore, it can accelerate the low-carbon transformation of industry, construction, and transportation, making it a key force in promoting the low-carbon energy transition. However, hydrogen energy faces numerous severe challenges in storage and transportation, such as safety hazards in high-pressure gaseous storage and transportation, and excessive energy consumption in low-temperature liquid storage and transportation. These stringent conditions significantly limit the wider application of hydrogen energy. Ammonia, with its high hydrogen content and low-temperature liquefaction properties, demonstrates significant advantages in hydrogen storage and transportation, making it a highly promising chemical hydrogen storage carrier.

[0003] Currently, ruthenium-based catalysts are commonly used catalytic materials in the field of low-temperature ammonia decomposition for hydrogen production. However, the excessively high ruthenium content in existing ruthenium-based catalysts leads to high catalyst costs, preventing their commercial application. Moreover, ruthenium-based catalysts are susceptible to hydrogen poisoning, meaning that the large amount of adsorbed hydrogen on the catalyst surface inhibits ammonia decomposition, significantly affecting the activity and stability of ruthenium-based catalysts. Summary of the Invention

[0004] This application aims to provide a modified CeO2-supported ruthenium cluster catalyst, its preparation method, and its application. Based on the effect of modifying CeO2 with alkaline earth metal electronic additives, the catalyst has a stronger NH bond breaking ability and can effectively inhibit hydrogen poisoning by leveraging the strong interaction between the support and metal of CeO2 and ruthenium clusters. This enables the catalyst to efficiently catalyze the decomposition of ammonia to produce hydrogen under low-temperature conditions.

[0005] The ability of NH to break bonds and the suppression of hydrogen poisoning enable efficient catalytic promotion of ammonia decomposition to produce hydrogen under low-temperature conditions.

[0006] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, embodiments of this application propose a method for preparing a modified CeO2-supported ruthenium cluster catalyst, the preparation method comprising: Add alkali solution to a mixed solution of cerium precursor solution and alkaline earth metal precursor solution, stir to co-precipitate, and form a suspension. The suspension was subjected to hydrothermal reaction and then filtered to obtain a solid product. The solid product was then washed, dried, and annealed to obtain alkaline earth metal modified CeO2. The modified CeO2 was immersed in an impregnation solution containing ruthenium salt and precipitant and stirred to impregnate, so that the resulting ruthenium precipitate was loaded onto the modified CeO2. The solid material obtained by impregnation was washed, dried and reduced to obtain a modified CeO2 supported ruthenium atom cluster catalyst. The cerium precursor is selected from at least one of cerium nitrate, cerium trichloride, and cerium acetate; The alkaline earth metal precursor is selected from at least one of magnesium nitrate, magnesium acetate, calcium nitrate, calcium acetate, strontium nitrate, strontium acetate, barium nitrate, and barium acetate.

[0007] Optionally, in the mixed solution, the molar ratio of the cerium precursor to the alkaline earth metal precursor is (0.05-0.80):1; The total concentration of the cerium precursor and the alkaline earth metal precursor in the mixed solution is 5wt%-20wt%.

[0008] Optionally, the hydrothermal reaction is carried out at a temperature of 100℃-120℃ for a time of 10h-16h.

[0009] Optionally, the alkaline solution is an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide; The molar ratio of sodium hydroxide or potassium hydroxide in the alkaline solution to the cerium precursor is (10-50):1.

[0010] Optionally, the annealing process is as follows: the temperature is increased to 150℃-200℃ at a heating rate of 2℃ / min-5℃ / min; The annealing process takes 2-3 hours.

[0011] Optionally, the ruthenium salt is selected from at least one of ruthenium trichloride, ruthenium nitrite, ruthenium acetate, ruthenium acetylacetone, and ruthenium dodecylcarbonyl. The concentration of the ruthenium salt in the impregnation solution is 0.5 mg / mL to 5.0 mg / mL; The mass ratio of ruthenium ions to the modified CeO2 in the impregnation solution is 0.005-0.02.

[0012] Optionally, the precipitant is urea or biuret; The concentration of the precipitant in the impregnation solution is 20 mg / mL to 100 mg / mL.

[0013] Optionally, the heating program for the reduction treatment is as follows: heating to 200℃-300℃ at a heating rate of 2℃ / min-5℃ / min; The reduction process takes 1-3 hours.

[0014] Secondly, embodiments of this application provide a modified CeO2-supported ruthenium cluster catalyst, wherein the modified CeO2-supported ruthenium cluster catalyst is prepared by the preparation method described in the first aspect; The formula for the modified CeO2-supported ruthenium cluster catalyst is Ru. x / [AE y -CeO2]; Among them, Ru x The modified CeO2-supported ruthenium cluster catalyst contains x mass percentages of ruthenium clusters; x is 0.5-2.0. [AE y [-CeO2] represents the modified CeO2 containing a mass percentage y of modified CeO2 in the modified CeO2-supported ruthenium cluster catalyst; AE represents alkaline earth metal elements; y is 5-15.

[0015] Thirdly, embodiments of this application provide an application of a modified CeO2-supported ruthenium cluster catalyst, wherein the modified CeO2-supported ruthenium cluster catalyst is prepared by the preparation method described in the first aspect; The modified CeO2-supported ruthenium cluster catalyst is used to catalyze the ammonia decomposition reaction to produce hydrogen.

[0016] Beneficial technical effects: In the embodiments of this application, an alkaline earth metal-modified CeO2 support was obtained, which was then loaded using a uniform precipitation method to form ultra-small ruthenium atom clusters, achieving a high degree of dispersion of ruthenium active sites. This composite structure of modified CeO2-supported ruthenium atom clusters can improve the utilization efficiency of ruthenium atoms, ensuring sufficient active sites in the catalyst while reducing the loading of the precious metal ruthenium, thus solving the problem of high cost caused by the high ruthenium content of existing catalysts.

[0017] The doping of alkaline earth metals induces a large number of oxygen vacancies in the CeO2 lattice, thereby enhancing the oxygen storage capacity and intrinsic activity of the modified CeO2 support. Simultaneously, the alkaline earth metals also make the surface of the modified CeO2 support more basic, which is more conducive to the adsorption and activation of ammonia molecules, better stabilizes reaction intermediates, and promotes the breaking of NH bonds. Furthermore, the electronic modification of this composite structure, through metal-support interactions, modulates the electronic structure of the ruthenium atom cluster, making it "electron-rich." This electronic state transition can moderately weaken the adsorption strength of hydrogen products on the ruthenium active sites, thereby alleviating the "hydrogen poisoning" phenomenon caused by excessive hydrogen species covering the active sites and improving the reaction efficiency and stability of the catalyst.

[0018] This application embodiment utilizes the synergistic effect of alkaline earth metal modified CeO2 support and active ruthenium atom cluster dispersion to reduce catalyst cost while optimizing its intrinsic catalytic performance, thus preparing a highly efficient, stable, and more economical low-temperature ammonia decomposition hydrogen production catalyst.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart of the preparation method of the modified CeO2-supported ruthenium cluster catalyst proposed in the embodiments of this application; Figure 2 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 Aberration-corrected transmission electron microscopy image of the [-CeO2] catalyst; Figure 3 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 EDS elemental comparison diagram of the [-CeO2] catalyst; Figure 4 These are the XRD phase analysis spectra of the catalysts prepared in Examples 1-4 of this application; Figure 5 This is a comparison chart of the ammonia decomposition performance of the catalysts prepared in Examples 1-4 of this application; Figure 6 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 -CeO2] catalyst, Ru1 / [Ba1] prepared in Example 5 10 -CeO2] catalyst and [Ba] prepared in Comparative Example 1 10 Comparison of the effect of reaction temperature on ammonia decomposition performance of the [-CeO2] catalyst; Figure 7 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 A comparison of the effect of reaction temperature on ammonia decomposition performance of the Ru2 / [Ba5-CeO2] catalyst, the Ru2 / [Ba5-CeO2] catalyst prepared in Example 6, and the Ru2 / [CeO2] catalyst in Comparative Example 2; Figure 8 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 Comparison of the effect of reaction pressure on ammonia decomposition performance of the [-CeO2] catalyst; Figure 9 It is the Ru2 / [Ba] prepared in Example 1 of this application.10 Comparison of the effect of reaction space velocity on ammonia decomposition performance of the [-CeO2] catalyst; Figure 10 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 Performance analysis diagram of the [-CeO2] catalyst in the long-cycle ammonia decomposition process. Detailed Implementation

[0021] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0022] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0023] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] Among related technologies, hydrogen energy is an abundant, green, low-carbon, and widely used secondary energy source. Ammonia, as a highly promising chemical hydrogen storage carrier, exhibits significant advantages in hydrogen energy storage and transportation due to its 17.7wt% hydrogen storage content and liquefaction capability at -33℃. Compared to hydrogen gas, which requires cryogenic liquefaction at -253℃, ammonia liquefaction reduces energy consumption by more than 90%, and its volumetric energy density (13.6 MJ / L) is 1.5 times that of liquid hydrogen, while its transportation cost is only 1 / 10 of that of high-pressure gaseous hydrogen storage. These characteristics make it a key solution to overcome the bottleneck problem in hydrogen energy storage and transportation. However, in reality, ammonia decomposition for hydrogen production faces bottlenecks. Typically, ammonia decomposition for hydrogen production requires high temperatures of 600℃-800℃, which can cause catalyst sintering and deactivation, as well as severe energy consumption.

[0026] Currently, ruthenium-based catalysts have shown significant advantages in the field of low-temperature ammonia decomposition for hydrogen production. However, they still suffer from low activity in the low-temperature range of ammonia decomposition and require high ruthenium dosage, failing to meet the activity and cost requirements of catalysts under ammonia decomposition conditions. Based on this, the embodiments of this application have found that: Developing composite ruthenium-based catalysts with alkaline earth metal-modified CeO2 supporting ruthenium atom clusters is a novel approach to constructing ammonia decomposition catalysts. This approach leverages the influence of alkaline earth metal electronic additives on CeO2 modification and the strong interaction between CeO2 and the ruthenium atom cluster support-metal to enhance the catalyst's low-temperature ammonia decomposition activity while effectively reducing the amount of ruthenium used in the catalyst.

[0027] This application provides a method for preparing a modified CeO2-supported ruthenium cluster catalyst. Figure 1 This is a flowchart illustrating the preparation method of the modified CeO2-supported ruthenium cluster catalyst proposed in the embodiments of this application, specifically including: Step S1: Add alkali solution to the mixed solution of cerium precursor solution and alkaline earth metal precursor solution, stir to co-precipitate, and form a suspension; In some embodiments, the cerium precursor is selected from at least one of cerium nitrate, cerium trichloride, and cerium acetate; The alkaline earth metal precursor is selected from at least one of magnesium nitrate, magnesium acetate, calcium nitrate, calcium acetate, strontium nitrate, strontium acetate, barium nitrate, and barium acetate. The above-mentioned cerium salt and alkaline earth metal salt have excellent water solubility, which enables the cerium precipitate and alkaline earth metal precipitate generated during the co-precipitation process to be uniformly mixed in the solution. At the same time, the anions of these salts (such as nitrate and acetate) are easily decomposed and volatilized during hydrothermal, drying, and annealing processes, which can avoid the poisoning of the support structure and the subsequently loaded ruthenium atom clusters by the residual harmful impurities such as chloride ions.

[0028] In some embodiments, the preparation of the cerium precursor solution and the alkaline earth metal precursor solution includes: weighing the cerium precursor and the alkaline earth metal precursor respectively, dissolving them in a certain amount of deionized water, and stirring to obtain the precursor solution; The method for preparing the mixed solution includes: stirring and mixing the prepared cerium precursor solution with the alkaline earth metal precursor solution to form a mixed solution; Alternatively, weigh the cerium precursor and alkaline earth metal precursor separately, dissolve them in a certain amount of deionized water, and stir magnetically for 1-2 hours at room temperature. At the same time, a cerium precursor solution and an alkaline earth metal precursor solution are formed in the deionized water, and the two mix on their own to obtain a mixed solution. In some embodiments, the molar ratio of the cerium precursor to the alkaline earth metal precursor in the mixed solution is (0.05-0.80):1; for example, the molar ratio of the cerium precursor to the alkaline earth metal precursor is 0.05:1, 0.06:1, 0.07:1, or 0.80:1; this molar ratio range corresponds to the effective doping concentration of the alkaline earth metal in the CeO2 lattice. Within this range, a sufficient number of oxygen vacancies and basic sites can be generated to improve the carrier performance and electronic structure, avoid the segregation of alkaline earth metal oxides on the CeO2 surface or the formation of impurity phases, and prevent damage to the uniformity and stability of the carrier structure. The total concentration of the cerium precursor and the alkaline earth metal precursor in the mixed solution is 5wt%-20wt%; for example, the total concentration of the cerium precursor and the alkaline earth metal precursor in the mixed solution is 5wt%, 6wt%, 8wt%, 10wt%, 12wt%, 16wt%, 18wt%, and 20wt%. The total concentration of the cerium precursor and the alkaline earth metal precursor will affect the amount of precipitation. At this concentration, sufficient precursor precipitate can be generated to form a carrier framework with sufficient structural strength, preventing the rapid disordered aggregation of precipitates caused by ion supersaturation, and generating amorphous precursors with large particles, dense texture, and uneven mixing, so that a uniform doped crystal phase can be formed in the subsequent hydrothermal reaction.

[0029] In some embodiments, the alkaline solution can be prepared by weighing alkali according to a certain proportion, dissolving it in a certain amount of deionized water to form an alkaline solution, and then stirring it magnetically for 1-2 hours at room temperature before adding it to the mixed solution.

[0030] In some embodiments, the alkaline solution is an aqueous solution of sodium hydroxide or potassium hydroxide; sodium hydroxide or potassium hydroxide is used to provide hydroxide ions required for precipitation, ensuring that cerium and alkaline earth metal ions are co-precipitated simultaneously and completely into the corresponding hydroxides; The molar ratio of sodium hydroxide or potassium hydroxide in the alkaline solution to the cerium precursor is (10-50):1; for example, the molar ratio of sodium hydroxide to cerium precursor is 10:1, 20:1, 30:1, 40:1, or 50:1; or, the molar ratio of potassium hydroxide to cerium precursor is 15:1, 25:1, 35:1, 45:1, or 48:1; an excess of alkaline solution can prevent incomplete precipitation or component segregation. In practice, after adding alkali solution to the mixed solution, the mixture is magnetically stirred at room temperature for 2-6 hours to co-precipitate. Amorphous (non-crystalline), fine-particle, irregularly structured cerium hydroxide and alkaline earth metal precipitates will gradually form in the solution. After precipitation is complete, a suspension is formed.

[0031] Step S2: The suspension is subjected to hydrothermal reaction and then filtered to obtain a solid product. The solid product is washed, dried and annealed to obtain alkaline earth metal modified CeO2. In some embodiments, the hydrothermal reaction is carried out in a hydrothermal reactor; the temperature of the hydrothermal reaction is 100℃-120℃, and the time is 10h-16h. It should be noted that during implementation, the amorphous hydroxides in the suspension will undergo thermal dehydration, thereby transforming into more stable oxides or directly reacting to form the target product; for example, cerium hydroxide in an alkaline hydrothermal environment, Ce 3+ It is easily oxidized by oxygen to Ce 4+ CeO2 can be obtained by dehydration, or Ce2O3 can be obtained by direct dehydration, and Ce2O3 can be oxidized to produce CeO2. At the same time, under high temperature hydrothermal conditions, the ion mobility is greatly improved, and the newly generated highly active CeO2 will undergo a solid-phase reaction with Ba(OH)2 to synthesize a well-crystallized solid product. In the embodiments of this application, the mild reaction temperature and sufficient reaction time can prevent excessive crystal growth or adverse phase transformation, enabling the precursor to transform into doped CeO2 with a regular crystal form, high specific surface area, and abundant pore structure. This promotes the uniform embedding of alkaline earth metal ions into the CeO2 lattice, thereby stabilizing the formation of high-concentration oxygen vacancies and a suitable strongly alkaline surface as key active sites. Simultaneously, the suspension contains excess alkaline solution, allowing the hydrothermal reaction to proceed in a strongly alkaline environment. This promotes the recrystallization process of the amorphous precursor, guiding the cerium species to transform into the cerium oxide crystal phase with a regular morphology and good crystallinity.

[0032] In some embodiments, the washing step includes: washing the solid product obtained by vacuum filtration with deionized water and ethanol 2-3 times respectively; removing impurity ions (such as nitrate, sodium or potassium ions) and other soluble impurities that may be adsorbed during precipitation and hydrothermal process by washing, and avoiding these impurities from being solidified inside or on the surface of the carrier. The drying steps include: vacuum drying the washed solid product at 60℃-90℃ for 2h-12h, and placing the dried product in a porcelain boat.

[0033] In some embodiments, the annealing process is performed in a muffle furnace; The annealing process involves heating to 150℃-200℃ at a rate of 2℃ / min-5℃ / min; for example, heating to 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃ at rates of 2℃ / min, 3℃ / min, 4℃ / min, or 5℃ / min. Slow heating avoids thermal stress cracks or pore structure collapse inside the carrier particles due to rapid temperature changes, preserving the high specific surface area, abundant pores, and inherent oxygen vacancies constructed by the hydrothermal reaction. Under heating conditions of 150℃-200℃, water molecules adsorbed on the surface and in the pores of the solid product gain sufficient energy to desorb, thereby reducing powder agglomeration, reducing particle aggregation, and improving powder dispersibility.

[0034] The annealing process takes 2-3 hours; continuous annealing ensures that the residual adsorbed water in the carrier is fully removed, thereby stabilizing its surface chemical state and consolidating the oxygen vacancy structure induced by alkaline earth metal doping.

[0035] Step S3: The modified CeO2 is immersed in an impregnation solution containing ruthenium salt and precipitant and stirred to impregnate, so that the ruthenium precipitate generated is loaded on the modified CeO2. The solid material obtained by impregnation is washed, dried and reduced to obtain the modified CeO2 supported ruthenium atom cluster catalyst. In some embodiments, ruthenium salt and precipitant are weighed in proportion and dissolved in a certain amount of deionized water to prepare an impregnation solution; The ruthenium salt is selected from at least one of ruthenium trichloride, ruthenium nitrite, ruthenium acetate, ruthenium acetylacetone, and ruthenium dodecylcarbonyl. The concentration of the ruthenium salt in the impregnation solution is 0.5 mg / mL to 5.0 mg / mL; for example, 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL. The mass ratio of ruthenium ions to modified CeO2 in the impregnation solution is 0.005-0.02; for example, the mass ratio of ruthenium ions to modified CeO2 in the impregnation solution is 0.005, 0.01, 0.015, or 0.02.

[0036] In some embodiments, the precipitant is urea or biuret; the precipitant undergoes a slow and uniform hydrolysis reaction when heated, gradually releasing hydroxide ions or ammonia molecules required for precipitation, providing a mild precipitation environment with a gentle concentration gradient in the impregnation solution, ensuring that ruthenium precipitate is deposited in a fine and uniform form on the surface defect sites of the alkaline earth metal modified CeO2 carrier. The concentration of the precipitant in the impregnation solution is 20 mg / mL to 100 mg / mL; for example, the concentration of the precipitant is 20 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, 60 mg / mL, 70 mg / mL, 80 mg / mL, 90 mg / mL, or 100 mg / mL. This concentration range allows urea or biuret to undergo continuous and sufficient hydrolysis during the heating impregnation process, generating a sufficient concentration of precipitated ions to drive the complete and stable conversion of the ruthenium precursor into hydroxide precipitate.

[0037] In some embodiments, the washing step includes: washing the solid material obtained from impregnation with ethanol and deionized water 2-3 times respectively; The drying steps include: drying the washed solid material at 60℃-90℃ for 2h-12h, and placing the resulting solid powder in a porcelain boat; In some embodiments, the reduction process is carried out in a tube furnace; The heating program for the reduction treatment is as follows: heating to 200℃-300℃ at a heating rate of 2℃ / min-5℃ / min; slow heating and appropriate temperature can effectively prevent ruthenium atoms from rapidly migrating and agglomerating to form large-sized nanoparticles due to overheating, thereby ensuring that they form a uniform and highly dispersed atomic cluster structure on the surface of the alkaline earth metal modified CeO2 support. The reduction treatment takes 1-3 hours. The reduction process works synergistically with the abundant oxygen vacancies and basic sites on the support to expose active sites to a greater extent, thereby achieving high catalytic efficiency under low ruthenium loading.

[0038] This application also provides a modified CeO2-supported ruthenium cluster catalyst, wherein the modified CeO2-supported ruthenium cluster catalyst is expressed as Ru. x / [AE y -CeO2]; Among them, Ru x The modified CeO2-supported ruthenium cluster catalyst contains x mass percentages of ruthenium clusters; x is 0.5-2.0. [AE y [-CeO2] represents the modified CeO2 containing a mass percentage y of modified CeO2 in the modified CeO2-supported ruthenium cluster catalyst; AE represents alkaline earth metal elements; y is 5-15.

[0039] The catalyst prepared in this application has an extremely low ruthenium loading, which significantly reduces production costs compared to traditional ruthenium-based catalysts. Simultaneously, this low-content ruthenium exists in a highly dispersed atom cluster form, thereby exposing abundant active sites to ensure high catalytic efficiency. Furthermore, the specific proportion of alkaline earth metal doping in the support effectively stabilizes oxygen vacancies in the CeO2 lattice and optimizes its surface alkalinity. This not only stabilizes the ruthenium atom clusters and prevents sintering through strong metal-support interactions but also modulates the electronic structure of ruthenium, placing it in a suitable electron-rich state. This alleviates the excessive adsorption and poisoning of reactive hydrogen at the active sites, achieving the key commercial requirements of high activity and high stability of the catalyst product with low amounts of precious metals.

[0040] This application also provides an application of a modified CeO2-supported ruthenium cluster catalyst, which is used to catalyze the ammonia decomposition to produce hydrogen. In some embodiments, the process of catalyzing the ammonia decomposition to produce hydrogen using the modified CeO2-supported ruthenium cluster catalyst includes: after loading the modified CeO2-supported ruthenium cluster catalyst into a fixed-bed reactor, ammonia gas is introduced to carry out the ammonia decomposition to produce hydrogen. The reaction conditions include: a reaction space velocity of 5000 mL·g for ammonia. -1 ·h -1 -60000 mL·g -1 ·h -1； The reaction temperature is 200℃-500℃; The reaction pressure range is 0.1 MPa-5.0 MPa; The concentration of ammonia involved in the ammonia decomposition to produce hydrogen is 10 vol%-100 vol.

[0041] To enable those skilled in the art to better understand this application, the following embodiments are provided to illustrate in detail a modified CeO2-supported ruthenium cluster catalyst, its preparation method, and its application.

[0042] Example 1 The preparation of a modified CeO2-supported ruthenium cluster catalyst includes the following steps: (1) Weigh 4.34g of cerium nitrate hexahydrate and 0.328g of barium nitrate respectively, dissolve them in 50mL of deionized water, and stir magnetically for 2h at room temperature to obtain a mixed solution; (2) Weigh 6.0g of sodium hydroxide, dissolve it in 30mL of deionized water, stir magnetically at room temperature for 2h, add it to the mixed solution, and continue to stir magnetically at room temperature for 6h to obtain a suspension; (3) The suspension obtained in step (2) is placed into a hydrothermal reactor and subjected to a hydrothermal reaction at 100°C for 12 hours. The resulting white suspension is filtered, and the filter cake (solid product) is washed three times with deionized water and ethanol respectively. The washed solid product is vacuum dried at 80°C for 12 hours, and the resulting solid powder is placed in a porcelain boat. (4) The solid powder obtained in step (3) is placed in a muffle furnace and heated to 200°C at a heating rate of 2°C / min for 3 hours for annealing. The resulting powder is alkaline earth metal modified cerium oxide with a specific content, denoted as [Ba 10 -CeO2]; (5) Weigh 0.041 g of ruthenium trichloride and 1.0 g of urea respectively, dissolve them in 30 mL of deionized water to form an impregnation solution, and add 1.0 g of [Ba] to the impregnation solution. 10 -CeO2] was magnetically stirred and impregnated at 80°C for 12 hours. The resulting suspension was filtered, and the filtered solid material was washed with ethanol and deionized water for 3 hours respectively. It was then vacuum dried at 80°C for 12 hours. The resulting solid powder was placed in a porcelain boat. (6) The solid powder obtained in step (5) is placed in a tube furnace and heated to 250°C at a heating rate of 5°C / min. The furnace is then subjected to a reduction treatment for 2 hours under a reducing atmosphere provided by argon. The resulting powder is a modified CeO2-supported ruthenium cluster catalyst, denoted as Ru2 / [Ba 10 -CeO2].

[0043] The catalyst prepared in Example 1 was tested. Figure 2 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 Aberration-corrected transmission electron microscopy image of the [-CeO2] catalyst; as shown. Figure 1 As shown, the catalyst exhibits a rod-like structure, and the supported ruthenium atom clusters are highly dispersed. Figure 3 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 EDS elemental comparison diagram of the [-CeO2] catalyst; as shown Figure 3 As shown, the catalyst contains 1.96 wt.% ruthenium, 70.90 wt.% cerium, 9.96 wt.% barium, and 17.18 wt.% oxygen. Example 2 The preparation of a modified CeO2-supported ruthenium cluster catalyst includes the following steps: (1) Weigh 4.34 g of cerium nitrate hexahydrate and 0.414 g of strontium nitrate respectively, dissolve them in 50 mL of deionized water, and stir magnetically for 2 h at room temperature to obtain a mixed solution; (2) Weigh 6.0g of sodium hydroxide, dissolve it in 30mL of deionized water, stir magnetically at room temperature for 2h, add it to the mixed solution, and continue to stir magnetically at room temperature for 6h to obtain a suspension; (3) The suspension obtained in step (2) is placed into a hydrothermal reactor and subjected to a hydrothermal reaction at 100°C for 12 hours. The resulting white suspension is filtered, and the filter cake (solid product) is washed three times with deionized water and ethanol respectively. The washed solid product is vacuum dried at 80°C for 12 hours, and the resulting solid powder is placed in a porcelain boat. (4) The solid powder obtained in step (3) is placed in a muffle furnace and heated to 200°C at a heating rate of 2°C / min for 3 hours for annealing. The resulting powder is alkaline earth metal modified cerium oxide with a specific content, denoted as [Sr]. 10 -CeO2]; (5) Weigh 0.041 g of ruthenium trichloride and 1.0 g of urea respectively, dissolve them in 30 mL of deionized water to form an impregnation solution, and add 1.0 g of [Sr] to the impregnation solution. 10 -CeO2] was magnetically stirred and impregnated at 80°C for 12 hours. The resulting suspension was filtered, and the filtered solid material was washed with ethanol and deionized water for 3 hours respectively. It was then vacuum dried at 80°C for 12 hours. The resulting solid powder was placed in a porcelain boat. (6) The solid powder obtained in step (5) is placed in a tube furnace and heated to 250°C at a heating rate of 5°C / min. The furnace is then subjected to a reduction treatment for 2 hours under a reducing atmosphere provided by argon. The resulting powder is a modified CeO2-supported ruthenium cluster catalyst, denoted as Ru2 / [Sr 10 -CeO2].

[0044] Example 3 The preparation of a modified CeO2-supported ruthenium cluster catalyst includes the following steps: (1) Weigh 4.34g of cerium nitrate hexahydrate and 1.01g of calcium nitrate tetrahydrate respectively, dissolve them in 50mL of deionized water, and stir magnetically for 2h at room temperature to obtain a mixed solution; (2) Weigh 6.0g of sodium hydroxide, dissolve it in 30mL of deionized water, stir magnetically at room temperature for 2h, add it to the mixed solution, and continue to stir magnetically at room temperature for 6h to obtain a suspension; (3) The suspension obtained in step (2) is placed into a hydrothermal reactor and subjected to a hydrothermal reaction at 100°C for 12 hours. The resulting white suspension is filtered, and the filter cake (solid product) is washed three times with deionized water and ethanol respectively. The washed solid product is vacuum dried at 80°C for 12 hours, and the resulting solid powder is placed in a porcelain boat. (4) The solid powder obtained in step (3) is placed in a muffle furnace and heated to 200°C at a heating rate of 2°C / min for 3 hours for annealing. The resulting powder is alkaline earth metal modified cerium oxide with a specific content, denoted as [Ca]. 10 -CeO2]; (5) Weigh 0.041 g of ruthenium trichloride and 1.0 g of urea respectively, dissolve them in 30 mL of deionized water to form an impregnation solution, and add 1.0 g of [Ca] to the impregnation solution. 10 -CeO2] was magnetically stirred and impregnated at 80°C for 12 hours. The resulting suspension was filtered, and the filtered solid material was washed with ethanol and deionized water for 3 hours respectively. It was then vacuum dried at 80°C for 12 hours. The resulting solid powder was placed in a porcelain boat. (6) The solid powder obtained in step (5) is placed in a tube furnace and heated to 250°C at a heating rate of 5°C / min. The furnace is then subjected to a reduction treatment for 2 hours under a reducing atmosphere provided by argon. The resulting powder is a modified CeO2-supported ruthenium cluster catalyst, denoted as Ru2 / [Ca 10 -CeO2].

[0045] Example 4 The preparation of a modified CeO2-supported ruthenium cluster catalyst includes the following steps: (1) Weigh 4.34g of cerium nitrate hexahydrate and 1.83g of magnesium nitrate hexahydrate respectively, dissolve them in 50mL of deionized water, and stir magnetically for 2h at room temperature to obtain a mixed solution; (2) Weigh 6.0g of sodium hydroxide, dissolve it in 30mL of deionized water, stir magnetically at room temperature for 2h, add it to the mixed solution, and continue to stir magnetically at room temperature for 6h to obtain a suspension; (3) The suspension obtained in step (2) is placed into a hydrothermal reactor and subjected to a hydrothermal reaction at 100°C for 12 hours. The resulting white suspension is filtered, and the filter cake (solid product) is washed three times with deionized water and ethanol respectively. The washed solid product is vacuum dried at 80°C for 12 hours, and the resulting solid powder is placed in a porcelain boat. (4) The solid powder obtained in step (3) is placed in a muffle furnace and heated to 200°C at a heating rate of 2°C / min for 3 hours for annealing. The resulting powder is alkaline earth metal modified cerium oxide with a specific content, denoted as [Mg 10 -CeO2]; (5) Weigh 0.041 g of ruthenium trichloride and 1.0 g of urea respectively, dissolve them in 30 mL of deionized water to form an impregnation solution, and add 1.0 g of [Mg] to the impregnation solution. 10-CeO2] was magnetically stirred and impregnated at 80°C for 12 hours. The resulting suspension was filtered, and the filtered solid material was washed with ethanol and deionized water for 3 hours respectively. It was then vacuum dried at 80°C for 12 hours. The resulting solid powder was placed in a porcelain boat. (6) The solid powder obtained in step (5) is placed in a tube furnace and heated to 250°C at a heating rate of 5°C / min. The furnace is then subjected to a reduction treatment for 2 hours under a reducing atmosphere provided by argon. The resulting powder is a modified CeO2-supported ruthenium cluster catalyst, denoted as Ru2 / [Mg 10 -CeO2].

[0046] The catalysts prepared in Examples 1-4 were tested. Figure 4 These are the XRD phase analysis spectra of the catalysts prepared in Examples 1-4 of this application; as shown Figure 4 As shown, the diffraction peaks of CeO2 (00-034-0394) and alkaline earth metal salts (MgCO3 (00-034-0394), CaCO3 (00-005-0586), SrCO3 (00-005-0418), BaCO3 (00-005-0378)) are clearly visible, indicating that alkaline earth metal modified CeO2 was successfully prepared.

[0047] Example 5 The preparation of a modified CeO2-supported ruthenium cluster catalyst includes the following steps: (1) Weigh 4.34g of cerium nitrate hexahydrate and 0.328g of barium nitrate respectively, dissolve them in 50mL of deionized water, and stir magnetically for 2h at room temperature to obtain a mixed solution; (2) Weigh 6.0g of sodium hydroxide, dissolve it in 30mL of deionized water, stir magnetically at room temperature for 2h, add it to the mixed solution, and continue to stir magnetically at room temperature for 6h to obtain a suspension; (3) The suspension obtained in step (2) is placed into a hydrothermal reactor and subjected to a hydrothermal reaction at 100°C for 12 hours. The resulting white suspension is filtered, and the filter cake (solid product) is washed three times with deionized water and ethanol respectively. The washed solid product is vacuum dried at 80°C for 12 hours, and the resulting solid powder is placed in a porcelain boat. (4) The solid powder obtained in step (3) is placed in a muffle furnace and heated to 200°C at a heating rate of 2°C / min for 3 hours for annealing. The resulting powder is alkaline earth metal modified cerium oxide with a specific content, denoted as [Ba 10 -CeO2]; (5) Weigh 0.021g of ruthenium trichloride and 1.0g of urea respectively, dissolve them in 30mL of deionized water to form an impregnation solution, and add 1.0g of [Ba] to the impregnation solution. 10-CeO2] was magnetically stirred and impregnated at 80°C for 12 hours. The resulting suspension was filtered, and the filtered solid material was washed with ethanol and deionized water for 3 hours respectively. It was then vacuum dried at 80°C for 12 hours. The resulting solid powder was placed in a porcelain boat. (6) The solid powder obtained in step (5) is placed in a tube furnace and heated to 250°C at a heating rate of 5°C / min. The furnace is then subjected to a reduction treatment for 2 hours under a reducing atmosphere provided by argon. The resulting powder is a modified CeO2-supported ruthenium cluster catalyst, denoted as Ru1 / [Ba 10 -CeO2].

[0048] Example 6 The preparation of a modified CeO2-supported ruthenium cluster catalyst includes the following steps: (1) Weigh 4.34g of cerium nitrate hexahydrate and 0.164g of calcium nitrate tetrahydrate respectively, dissolve them in 50mL of deionized water, and stir magnetically for 2h at room temperature to obtain a mixed solution; (2) Weigh 6.0g of sodium hydroxide, dissolve it in 30mL of deionized water, stir magnetically at room temperature for 2h, add it to the mixed solution, and continue to stir magnetically at room temperature for 6h to obtain a suspension; (3) The suspension obtained in step (2) is placed into a hydrothermal reactor and subjected to a hydrothermal reaction at 100°C for 12 hours. The resulting white suspension is filtered, and the filter cake (solid product) is washed three times with deionized water and ethanol respectively. The washed solid product is vacuum dried at 80°C for 12 hours, and the resulting solid powder is placed in a porcelain boat. (4) The solid powder obtained in step (3) is placed in a muffle furnace and heated to 200°C at a heating rate of 2°C / min. It is then annealed for 3 hours. The resulting powder is alkaline earth metal modified cerium oxide with a specific content, denoted as [Ba5-CeO2]. (5) Weigh 0.041 g of ruthenium trichloride and 1.0 g of urea respectively, dissolve them in 30 mL of deionized water to form an impregnation solution, add 1.0 g of [Ba5-CeO2] to the impregnation solution, and impregnate with magnetic stirring at 80 °C for 12 h. Filter the resulting suspension, wash the filtered solid material with ethanol and deionized water for 3 times respectively, and then vacuum dry at 80 °C for 12 h. Place the obtained solid powder in a porcelain boat. (6) The solid powder obtained in step (5) is placed in a tube furnace and heated to 250°C at a heating rate of 5°C / min. The reduction is carried out for 2 hours in a reducing atmosphere provided by argon. The resulting powder is a modified CeO2 supported ruthenium atom cluster catalyst, denoted as Ru2 / [Ba5-CeO2].

[0049] Comparative Examples 1-2 are set up based on Examples 1-6, as follows: Comparative Example 1 A modified CeO2 catalyst supported on ruthenium atom clusters was prepared, differing from Example 1 in that the modified CeO2 prepared in Comparative Example 1 did not support ruthenium atom clusters. The preparation included the following steps: (1) Weigh 4.34g of cerium nitrate hexahydrate and 0.328g of calcium nitrate tetrahydrate respectively, dissolve them in 50mL of deionized water, and stir magnetically for 2h at room temperature to obtain a mixed solution; (2) Weigh 6.0g of sodium hydroxide, dissolve it in 30mL of deionized water, stir magnetically at room temperature for 2h, add it to the mixed solution, and continue to stir magnetically at room temperature for 6h to obtain a suspension; (3) The suspension obtained in step (2) is placed into a hydrothermal reactor and subjected to a hydrothermal reaction at 100°C for 12 hours. The resulting white suspension is filtered, and the filter cake (solid product) is washed three times with deionized water and ethanol respectively. The washed solid product is vacuum dried at 80°C for 12 hours, and the resulting solid powder is placed in a porcelain boat. (4) The solid powder obtained in step (3) is placed in a muffle furnace and heated to 200°C at a heating rate of 2°C / min for 3 hours for annealing. The resulting powder is alkaline earth metal modified cerium oxide with a specific content, denoted as [Ba 10 -CeO2].

[0050] Comparative Example 2 A modified CeO2-supported ruthenium cluster catalyst was prepared. The difference between Comparative Example 2 and Example 1 is that alkaline earth metal modification of CeO2 was not used. The preparation included the following steps: (1) Weigh 4.34 g of cerium nitrate hexahydrate, dissolve it in 50 mL of deionized water, and stir magnetically at room temperature for 2 h to obtain a cerium precursor solution; (2) Weigh 6.0g of sodium hydroxide, dissolve it in 30mL of deionized water, stir magnetically at room temperature for 2h, add it to the cerium precursor solution, and continue to stir magnetically at room temperature for 6h to obtain a suspension. (3) The suspension obtained in step (2) is placed into a hydrothermal reactor and subjected to a hydrothermal reaction at 100°C for 12 hours. The resulting white suspension is filtered, and the filter cake (solid product) is washed three times with deionized water and ethanol respectively. The washed solid product is vacuum dried at 80°C for 12 hours, and the resulting solid powder is placed in a porcelain boat. (4) The solid powder obtained in step (3) is placed in a muffle furnace and heated to 200°C at a heating rate of 2°C / min. It is then annealed for 3 hours. The resulting powder is [CeO2] without alkaline earth metal modification. (5) Weigh 0.041 g of ruthenium trichloride and 1.0 g of urea respectively, dissolve them in 30 mL of deionized water to form an impregnation solution, add 1.0 g of [CeO2] to the impregnation solution, and impregnate with magnetic stirring at 80 °C for 12 h. Filter the resulting suspension, wash the filtered solid material with ethanol and deionized water for 3 times respectively, and then vacuum dry at 80 °C for 12 h. Place the obtained solid powder in a porcelain boat. (6) The solid powder obtained in step (5) is placed in a tube furnace and heated to 250°C at a heating rate of 5°C / min. The reduction is carried out for 2 hours in a reducing atmosphere provided by argon. The resulting powder is a modified CeO2 supported ruthenium atom cluster catalyst, denoted as Ru2 / [CeO2].

[0051] Performance testing The catalysts prepared in Examples 1-6 and Comparative Examples 1-2 were tested for their hydrogen production performance from ammonia decomposition. The testing process included: Ammonia decomposition for hydrogen production was carried out in a fixed-bed tubular reactor loaded with a catalyst. Nitrogen gas was introduced at a rate of 50 mL / min at room temperature, and the temperature was increased to 500 °C at a rate of 5 °C / min. After stabilization at 500 °C for 1 hour, the ammonia decomposition performance was tested by introducing a reaction gas. Ammonia in the product gas was absorbed with dilute sulfuric acid and then detected by ion chromatography. The reaction space velocity was 5000 mL·g⁻¹. -1 ·h -1 -60000 mL·g -1 ·h -1 The reaction temperature is 200-500℃, the reaction pressure is 0.1-1.0MPa, and the ammonia concentration ranges from 10-100 vol.

[0052] (1) The ammonia decomposition performance of the catalysts prepared in Examples 1-4 was tested under the following reaction conditions: The reaction temperature was 400℃, the reaction pressure was 0.1 MPa, the ammonia concentration was 10 vol%, and the reaction space velocity was 30000 mL·g. -1 ·h -1 .

[0053] Figure 5 This is a comparison chart of the ammonia decomposition performance of the catalysts prepared in Examples 1-4 of this application, as shown. Figure 5 As shown, the ammonia conversion rates of the catalysts prepared in Examples 1-4 are all no less than 97%. This demonstrates that the catalysts prepared by the methods in this application have high activity and can efficiently catalyze the decomposition of ammonia to produce hydrogen under low-temperature conditions.

[0054] (2) The effect of reaction temperature on the catalysts prepared in Example 1, Example 5 and Comparative Example 1 in ammonia decomposition was tested. The reaction conditions included: The reaction temperature was 200℃-500℃, the reaction pressure was 0.1MPa, the ammonia concentration was 10 vol%, and the reaction space velocity was 30000 mL·g. -1 ·h -1 .

[0055] Figure 6 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 -CeO2] catalyst, Ru1 / [Ba1] prepared in Example 5 10 -CeO2] catalyst and [Ba] prepared in Comparative Example 1 10 A comparison of the effect of reaction temperature on ammonia decomposition performance of the [-CeO2] catalyst, as shown in the figure. Figure 6 As shown in the comparison between Example 1 and Comparative Example 1, it is evident that ruthenium clusters in the catalyst are also essential in the ammonia decomposition reaction, and the ammonia decomposition performance of the catalyst improves with increasing ruthenium content. This indicates that appropriately increasing the density of ruthenium clusters can effectively increase the number of active sites, thereby enhancing the overall catalytic efficiency.

[0056] (3) The effect of reaction temperature on the catalysts prepared in Example 1, Example 6 and Comparative Example 2 in ammonia decomposition was tested. The reaction conditions included: The reaction temperature was 200℃-500℃, the reaction pressure was 0.1MPa, the ammonia concentration was 10 vol%, and the reaction space velocity was 30000 mL·g. -1 ·h -1 .

[0057] Figure 7 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 A comparison of the effect of reaction temperature on ammonia decomposition performance of the Ru2 / [Ba5-CeO2] catalyst prepared in Example 6 and the Ru2 / [CeO2] catalyst in Comparative Example 2, as shown in the figure. Figure 7 As shown in the comparison between Example 1 and Comparative Example 2, it can be seen that the modification of the ruthenium atom cluster composite catalyst by the alkaline earth metal in the catalyst can effectively improve the ammonia decomposition activity. This is mainly due to the fact that the catalyst has a higher NH bond breaking ability and a higher resistance to hydrogen poisoning by means of its electronic auxiliary agent.

[0058] (4) The effect of reaction pressure on the catalyst prepared in Example 1 during ammonia decomposition was tested. The reaction conditions included: The reaction temperature was 400℃, the reaction pressure was 0.1 MPa, 0.3 MPa, 0.6 MPa, and 1.0 MPa, the ammonia concentration was 10 vol%, and the reaction space velocity was 30000 mL·g. -1 ·h -1 .

[0059] Figure 8It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 A comparison of the effect of reaction pressure on ammonia decomposition performance of the [-CeO2] catalyst is shown in the figure. Figure 8 As shown, the ammonia conversion rates at ammonia decomposition reaction pressures of 0.1 MPa, 0.3 MPa, 0.6 MPa, and 1.0 MPa were 99.7%, 98.9%, 97.7%, and 96.3%, respectively. Although the catalyst prepared in this application showed a gradual decrease in activity as the reaction pressure increased, the conversion rate was still as high as 96.3% when the pressure rose to 1.0 MPa, fully demonstrating the strong adaptability of its active sites to reaction conditions and its structural stability.

[0060] (5) The effect of reaction space velocity on the catalyst prepared in Example 1 in ammonia decomposition was tested. The reaction conditions included: The reaction temperature was 400℃, the reaction pressure was 0.1 MPa, the ammonia concentration was 10 vol%, and the reaction space velocity was 12000 mL·g. -1 ·h -1 18000mL·g -1 ·h -1 30000mL·g -1 ·h -1 48000mL·g -1 ·h -1 60000mL·g -1 ·h -1 .

[0061] Figure 9 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 A comparison of the effect of reaction space velocity on ammonia decomposition performance of the [-CeO2] catalyst is shown in the figure. Figure 9 As shown, the reaction space velocity is 12000 mL·g. -1 ·h -1 18000mL·g -1 ·h -1 30000mL·g -1 ·h -1 48000mL·g -1 ·h -1 60000mL·g -1 ·h -1 The corresponding ammonia conversion rates were 99.9%, 99.8%, 99.7%, 98.2%, and 95.1%, respectively. This result demonstrates that the catalyst possesses a rapid intrinsic reaction rate and stronger resistance to mass transfer limitation, maintaining stable and efficient catalytic performance even under high space velocity conditions.

[0062] (6) The performance of the catalyst prepared in Example 1 was tested in a long-cycle ammonia decomposition process. The reaction conditions included: The reaction temperature was 400℃, the reaction pressure was 0.1 MPa, the ammonia concentration was 10 vol%, and the reaction space velocity was 30000 mL·g. -1 ·h -1 .

[0063] Figure 10 It is the Ru2 / [Ba] prepared in Example 1 of this application. 10 Performance analysis of the [-CeO2] catalyst in the long-cycle ammonia decomposition process, as shown in the figure. Figure 10 As shown, in a 100-hour long-cycle ammonia decomposition performance test, Ru2 / [Ba 10 The ammonia conversion rate of [-CeO2] remained above 99%. This result fully demonstrates the excellent anti-sintering ability and structural durability of the catalyst. The strong interaction between the ruthenium atom cluster and the alkaline earth metal modified CeO2 support effectively prevents the migration, aggregation, or deactivation of the active components during long-term reaction. At the same time, the catalyst also exhibits good resistance to carbon deposition and hydrogen poisoning, and can continuously maintain sufficient active sites for the adsorption and dissociation of ammonia molecules.

[0064] In summary, the ruthenium cluster composite catalyst provided in this application uses alkaline earth metal elements to modify a carbon support to support a low-content ruthenium cluster composite catalytic material Ru. x / [RE y [-CeO2] exhibits excellent ammonia decomposition activity, achieving an ammonia decomposition conversion rate of no less than 95% at temperatures of 400℃-500℃ and pressures of 0.1MPa-1MPa, demonstrating broad prospects for practical applications.

[0065] Other configurations of the embodiments of this application, such as ... and ..., and operations, are known to those skilled in the art and will not be described in detail here.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing a modified CeO2-supported ruthenium cluster catalyst, characterized in that, The preparation method includes: Add alkali solution to a mixed solution of cerium precursor solution and alkaline earth metal precursor solution, stir to co-precipitate, and form a suspension. The suspension was subjected to hydrothermal reaction and then filtered to obtain a solid product. The solid product was then washed, dried, and annealed to obtain alkaline earth metal modified CeO2. The modified CeO2 was immersed in an impregnation solution containing ruthenium salt and precipitant and stirred to impregnate, so that the resulting ruthenium precipitate was loaded onto the modified CeO2. The solid material obtained by impregnation was washed, dried and reduced to obtain a modified CeO2 supported ruthenium atom cluster catalyst. The cerium precursor is selected from at least one of cerium nitrate, cerium trichloride, and cerium acetate; The alkaline earth metal precursor is selected from at least one of magnesium nitrate, magnesium acetate, calcium nitrate, calcium acetate, strontium nitrate, strontium acetate, barium nitrate, and barium acetate.

2. The method for preparing the modified CeO2-supported ruthenium cluster catalyst according to claim 1, characterized in that, In the mixed solution, the molar ratio of the cerium precursor to the alkaline earth metal precursor is (0.05-0.80):1; The total concentration of the cerium precursor and the alkaline earth metal precursor in the mixed solution is 5wt%-20wt%.

3. The method for preparing the modified CeO2-supported ruthenium cluster catalyst according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 100℃-120℃ for a duration of 10h-16h.

4. The method for preparing the modified CeO2-supported ruthenium cluster catalyst according to claim 1, characterized in that, The alkaline solution is an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide; The molar ratio of sodium hydroxide or potassium hydroxide in the alkaline solution to the cerium precursor is (10-50):

1.

5. The method for preparing the modified CeO2-supported ruthenium cluster catalyst according to claim 1, characterized in that, The annealing process involves heating to 150°C-200°C at a rate of 2°C / min-5°C / min. The annealing process takes 2-3 hours.

6. The method for preparing the modified CeO2-supported ruthenium cluster catalyst according to claim 1, characterized in that, The ruthenium salt is selected from at least one of ruthenium trichloride, ruthenium nitrite, ruthenium acetate, ruthenium acetylacetone, and ruthenium dodecylcarbonyl. The concentration of the ruthenium salt in the impregnation solution is 0.5 mg / mL to 5.0 mg / mL; The mass ratio of ruthenium ions to the modified CeO2 in the impregnation solution is 0.005-0.

02.

7. The method for preparing the modified CeO2-supported ruthenium cluster catalyst according to claim 1, characterized in that, The precipitant is urea or biuret; The concentration of the precipitant in the impregnation solution is 20 mg / mL to 100 mg / mL.

8. The method for preparing the modified CeO2-supported ruthenium cluster catalyst according to claim 1, characterized in that, The temperature rise program for the reduction treatment is as follows: the temperature is increased to 200℃-300℃ at a rising rate of 2℃ / min-5℃ / min. The reduction process takes 1-3 hours.

9. A modified CeO2-supported ruthenium cluster catalyst, characterized in that, The modified CeO2-supported ruthenium cluster catalyst is prepared by the preparation method according to any one of claims 1-8; The formula for the modified CeO2-supported ruthenium cluster catalyst is Ru. x / [AE y -CeO2]; Among them, Ru x The modified CeO2-supported ruthenium cluster catalyst contains x mass percentages of ruthenium clusters; x is 0.5-2.

0. [AE y [-CeO2] represents the modified CeO2 containing a mass percentage y of modified CeO2 in the modified CeO2-supported ruthenium cluster catalyst; AE represents alkaline earth metal elements; y is 5-15.

10. The application of a modified CeO2-supported ruthenium cluster catalyst, characterized in that, The modified CeO2-supported ruthenium cluster catalyst is prepared by the preparation method according to any one of claims 1-8; The modified CeO2-supported ruthenium cluster catalyst is used to catalyze the ammonia decomposition reaction to produce hydrogen.

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