Ammonia decomposition catalyst and ammonia decomposition method

Abstract

The present invention relates to an ammonia decomposition catalyst and an ammonia decomposition method.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2023 - 0098840 filed on July 28, 2023, and Korean Patent Application No. 10 - 2024 - 0097992 filed on July 24, 2024, and all the contents disclosed in the documents of the Korean patent applications are included as part of this specification.

[0002] The present invention relates to an ammonia decomposition catalyst and an ammonia decomposition method.

Background Art

[0003] Recently, as interest in the environment and energy has increased, interest in the hydrogen economy has also increased.

[0004] The hydrogen economy refers to an economic and industrial structure that uses hydrogen as the main energy source. That is, it breaks away from the current energy system centered on fossil fuels, increases power generation systems, heat production systems, machines such as automobiles that utilize hydrogen as an energy source, and thus creates new industries and markets in all fields necessary for the stable production, storage, and transportation of hydrogen. It is an economic system.

[0005] In such a system, hydrogen can be produced by various means such as electrolysis of water, natural gas reforming, and biomass gasification, and can be distributed via a pipeline network or transported as a hydrogen fuel cell. However, since this involves high costs and high risks for direct transportation of hydrogen, there is increasing interest in technologies for transporting hydrogen cheaply, easily, and safely.

[0006] One method for efficiently storing and transporting hydrogen is to transport ammonia and decompose the transported ammonia to use it as a hydrogen supply source.

[0007] The reaction that decomposes ammonia into hydrogen and nitrogen is an endothermic reaction with a large energy difference, and the activation energy of the reaction is also very large. Therefore, a lot of energy is required to obtain a useful amount of hydrogen gas as a product, and thus a lot of cost is incurred in producing hydrogen.

[0008] Therefore, there is currently growing interest in research on ammonia decomposition catalysts with high ammonia decomposition efficiency. [Overview of the project] [Problems that the invention aims to solve]

[0009] This specification aims to provide an ammonia decomposition catalyst that exhibits excellent low-temperature decomposition performance at high space velocities.

[0010] Furthermore, this specification aims to provide an ammonia decomposition catalyst that prevents catalytic thermal aggregation, provides reaction process stability, and has an improved lifespan.

[0011] Furthermore, this specification aims to provide a method for decomposing ammonia using such an ammonia decomposition catalyst. [Means for solving the problem]

[0012] This specification provides an ammonia decomposition catalyst comprising a carrier and a catalytically active component supported on the carrier, wherein the catalytically active component comprises i) a first metal, namely ruthenium (Ru); ii) a second metal; and iii) a third metal; the second and third metals are each independently one or more selected from the group consisting of lanthanum (La), cerium (Ce), aluminum (Al), and zirconium (Zr), the content of the first metal, namely ruthenium, is 0.1 to 1 part by weight per 100 parts by weight of the entire catalyst, the porosity is 30 to 60%, and the median value of the pore size is 50 to 200 μm.

[0013] Specifically, the second metal and the third metal may be different from each other.

[0014] For example, the content of the first metal, ruthenium, may be about 0.1 to about 1 part by weight, or about 0.1 parts by weight or more, or about 0.2 parts by weight or more, or about 0.3 parts by weight or more, or about 0.4 parts by weight or more, per 100 parts by weight of the entire catalyst, and at the same time may be about 1 part by weight or less, or about 0.9 parts by weight or less, or about 0.8 parts by weight or less, or about 0.7 parts by weight or less, or about 0.6 parts by weight or less, or about 0.5 parts by weight or less.

[0015] For example, the ammonia decomposition catalyst may have a porosity of about 30 to about 60%, or about 10% or more, or about 20% or more, or about 30% or more, or about 40% or more, or about 50% or more, and at the same time may be about 60% or less, or about 58% or less, or about 56% or less, or about 54% or less, or about 52% or less.

[0016] For example, the median value of the pore size of the ammonia decomposition catalyst may be approximately 50 to 200 μm, or approximately 50 μm or more, or approximately 75 μm or more, or approximately 100 μm or more, or approximately 120 μm or more, or approximately 140 μm or more, or approximately 150 μm or more, and at the same time may be approximately 200 μm or less, or approximately 180 μm or less, or approximately 160 μm or less.

[0017] For example, the ammonia decomposition catalyst may have a pore volume of about 0.1 to 0.4 mL / g, or about 0.1 mL / g or more, or about 0.2 mL / g or more, or about 0.25 mL / g or more, or about 0.3 mL / g or more, or about 0.33 mL / g or more, and at the same time may be about 0.4 mL / g or less, or about 0.35 mL / g or less.

[0018] For example, the carrier may be a porous spherical structure.

[0019] According to one example, the carrier may be an inorganic oxide structure. More specifically, the carrier may be an inorganic oxide containing one or more elements selected from the group consisting of aluminum (Al), zirconium (Zr), cerium (Ce), and silicon (Si). More specifically, the carrier may be aluminum silicate (Al2SiO5).

[0020] According to one example, the content of the catalytic active component may be about 20 parts by weight or less, or about 0.1 part by weight or more, or about 0.5 part by weight or more, or about 1 part by weight or more with respect to 100 parts by weight of the whole catalyst, and at the same time may be about 20 parts by weight or less, less than about 18 parts by weight, or about 15 parts by weight or less, or about 11 parts by weight or less.

[0021] According to one example, the weight ratio of (the second metal):(the third metal) may be about 1:99 to about 30:70, or about 1:99 or more, or about 10:90 or more, or about 20:80 or more, or about 23:77 or more, and at the same time may be about 30:70 or less, or about 25:75 or less.

[0022] According to one example, the weight ratio of (the first metal):(the second metal and the third metal oxides) may be 1:99 to 10:90, or about 3:97 to 7:93.

[0023] According to one example, the ammonia decomposition catalyst may be porous and spherical.

[0024] According to one example, the median value of the diameter of the circle of the cross-section of the porous sphere may be about 1 to 10 mm, or about 1 mm or more, or about 2 mm or more, or about 3 mm or more, and at the same time may be about 10 mm or less, about 8 mm or less, about 6 mm or less, or about 4 mm or less.

[0025] Also, this specification provides an ammonia decomposition method for advancing an ammonia decomposition reaction in the presence of any one of the ammonia decomposition catalysts described above.

[0026] According to one example, the ammonia decomposition reaction is from about 400 to about 700 °C, or about 400 °C or higher, or exceeding about 400 °C, or about 420 °C or higher, and at the same time may be carried out at about 700 °C or lower, about 650 °C or lower, about 600 °C or lower, or about 550 °C or lower, or about 530 °C or lower. [[ID=I]]

[0027] In the present invention, terms such as first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from other components.

[0028] Also, the terms used in this specification are used only for the purpose of explaining exemplary embodiments and are not intended to limit the present invention.

[0029] Singular expressions include plural expressions unless the context clearly indicates otherwise. [[ID=IS]]

[0030] [[ID=IS]] In this specification, terms such as "comprising", "including" or "having" are for the purpose of explaining the implemented features, numbers, steps, components, or combinations thereof, and do not exclude the possibility of one or more other features, numbers, steps, components, combinations thereof or additions.

[0031] Also, in this specification, when it is mentioned that each layer or element is formed "on" each layer or element, it means that each layer or element is directly formed on each layer or element, or that other layers or elements can be additionally formed between the layers, on the object, or on the substrate.

[0032] The present invention can be modified in various ways and can have various forms, but specific examples are illustrated and described in detail below. However, this is not intended to limit the present invention to a specific disclosed form, and it should be understood that it includes all modifications, equivalents or alternatives included in the spirit and technical scope of the present invention.

[0033] Furthermore, in this specification, a porous sphere refers to a porous spherical shape. Here, "sphere" does not necessarily mean only mathematically precise shapes, but rather any regular or irregular shape, such as a sphere, ellipsoid, or polyhedron, where the ratio of the minor axis to the major axis is 0.5 or greater. In other words, it refers to shapes that are not long like a rod or greatly flattened. The minor axis refers to the shortest particle size measured relative to the axis passing through the geometric center point of the particle, and the major axis refers to the longest particle size measured relative to the axis passing through the geometric center point of the particle.

[0034] Furthermore, in this specification, the total weight of the catalyst refers to the combined weight of the carrier and the catalytically active component supported on the carrier.

[0035] Furthermore, in this specification, the medium value of the pore size refers to the D value in the particle size volume analysis. 50 In the same sense, the pore size at the point where the cumulative volume from smallest particle size to 50% is based on 100% of the total particle volume is called the median pore size.

[0036] This specification provides an ammonia decomposition catalyst comprising a carrier and a catalytically active component supported on the carrier, wherein the catalytically active component comprises i) a first metal, ruthenium (Ru); ii) a second metal; and iii) a third metal; the second and third metals are each independently one or more selected from the group consisting of lanthanum (La), cerium (Ce), aluminum (Al), and zirconium (Zr), the content of the first metal, ruthenium, is 0.1 to 1 part by weight per 100 parts by weight of the entire catalyst, the porosity is 30 to 60%, and the median value of the pore size is 50 to 200 μm.

[0037] Specifically, the second metal and the third metal may be different from each other.

[0038] The inventors of the present invention have completed this invention by discovering that when a catalyst with a specific pore distribution is produced by coating a specific form of support with a catalytically active component, such a catalyst can achieve very high efficiency as an ammonia decomposition catalyst.

[0039] The ammonia decomposition reaction may also be represented by the following reaction equation:

[0040] [ka]

[0041] This reaction is a reversible process, yielding three molecules of hydrogen gas from two molecules of ammonia. Generally, when the reaction proceeds under high temperature and high pressure conditions in the presence of a catalyst, the forward reaction becomes dominant, and all of the ammonia is decomposed except for a small amount of undecomposed ammonia.

[0042] However, the aforementioned forward reaction is an endothermic reaction with a large difference in formation energy between the products and reactants, and the activation energy of the reaction is also very high. Therefore, the reaction is not very efficient and requires a lot of energy to be invested.

[0043] Therefore, in one embodiment of the present invention, an ammonia decomposition reaction is carried out using an ammonia decomposition catalyst comprising a carrier and a catalytically active component supported on the carrier, wherein the catalytically active component comprises i) a first metal, which is ruthenium (Ru); ii) a second metal; and iii) a third metal; and the second and third metals are each independently one or more selected from the group consisting of lanthanum (La), cerium (Ce), aluminum (Al), and zirconium (Zr), and the content of the first metal, which is ruthenium, is 0.1 to 1 part by weight per 100 parts by weight of the entire catalyst, the porosity is 30 to 60%, and the median value of the pore size is 50 to 200 μm.

[0044] Specifically, the second metal and the third metal may be different from each other.

[0045] As catalytically active components, ruthenium, as well as lanthanum (La), cerium (Ce), aluminum (Al), and zirconium (Zr), can be used in the form of composite metal oxides. Here, a composite metal oxide means a compound or mixture in which two or more of the metal elements mentioned above as catalytically active components are present at the same or different oxidation states.

[0046] In other words, ruthenium, as well as lanthanum (La), cerium (Ce), aluminum (Al), and zirconium (Zr), can be used as catalytic active components in the form of composite metal oxides. Of these, ruthenium is known to be the metal that directly mediates the reaction, while lanthanum (La), cerium (Ce), aluminum (Al), and zirconium (Zr) can play a role as a type of co-catalyst.

[0047] Specifically, the second metal may be lanthanum or cerium, and the third metal may be cerium or aluminum. More specifically, the second and third metals may be different from each other. More specifically, the second metal may be lanthanum and the third metal may be cerium, or the second metal may be lanthanum and the third metal may be aluminum, or a combination of the second metal being cerium and the third metal being aluminum.

[0048] Furthermore, the ammonia decomposition catalyst according to one aspect of the present invention is porous, with a median pore size of 50 to 200 μm. By using a porous catalyst, not only can the surface area that the catalytically active substance can come into contact with the reactants be increased, but thermal aggregation of the catalytically active substance can be prevented, thereby improving the lifespan of the catalyst.

[0049] If the median pore size is excessively small, reactants cannot flow smoothly into the catalyst pores, preventing full utilization of the active sites within the pores, which can lead to a decrease in reaction efficiency. Conversely, if the median pore size is excessively large, the specific surface area of ​​the catalyst decreases, reducing the dispersion of the active substances and decreasing the number of active sites, which can lead to a decrease in reaction performance.

[0050] More specifically, the median pore size of the ammonia decomposition catalyst may be approximately 50 μm or more, or approximately 75 μm or more, or approximately 100 μm or more, or approximately 120 μm or more, or approximately 140 μm or more, or approximately 150 μm or more, and at the same time may be approximately 200 μm or less, or approximately 180 μm or less, or approximately 160 μm or less.

[0051] Within the above range, it is possible to minimize the amount of ruthenium, a precious metal, supported while increasing the efficiency of the ammonia decomposition reaction and improving the catalyst lifespan.

[0052] For example, the ammonia decomposition catalyst may have a porosity of about 30 to about 60%, or about 10% or more, or about 20% or more, or about 30% or more, or about 40% or more, or about 50% or more, and at the same time may be about 60% or less, or about 58% or less, or about 56% or less, or about 54% or less, or about 52% or less.

[0053] If the porosity is excessively low, the reactants may not be able to come into contact with the catalytically active components present within the pores, potentially leading to a decrease in ammonia decomposition performance. Conversely, if the porosity is excessively high, the catalyst's strength may decrease, causing it to break down during the process of loading the reactor or during the ammonia decomposition reaction, resulting in a differential pressure within the reactor. This can lead to a decrease in catalytic performance.

[0054] For example, the carrier may be a porous spherical structure.

[0055] For example, the support may be an inorganic oxide structure. More specifically, the support may contain one or more oxides selected from the group consisting of aluminum (Al), zirconium (Zr), cerium (Ce), and silicon (Si). More specifically, the support may be aluminum silicate (Al2SiO5).

[0056] For example, the content of the first metal may be about 0.1 to about 1 part by weight, or about 0.1 parts by weight or more, or about 0.2 parts by weight or more, or about 0.3 parts by weight or more, or about 0.4 parts by weight or more, per 100 parts by weight of the entire catalyst, and at the same time may be about 1 part by weight or less, or about 0.9 parts by weight or less, or about 0.8 parts by weight or less, or about 0.7 parts by weight or less, or about 0.6 parts by weight or less, or 0.5 parts by weight or less.

[0057] If the content of the primary metal is excessively low, a problem may arise in which the efficiency of the ammonia decomposition reaction decreases. Conversely, if the content of the primary metal is excessively high, the active material may aggregate, reducing its dispersion and thus decreasing catalytic performance. Furthermore, in order to increase the content of the primary metal, the amount or number of coatings applied during the catalyst manufacturing process may become excessively high, resulting in the formation of primary metal that is not exposed on the catalyst surface, thus reducing catalytic efficiency. Going a step further, in the process of increasing the amount of coating, the pores of the structure may become clogged, hindering the smooth flow of reactants and generating differential pressure, which can reduce the specific surface area of ​​the catalyst and decrease catalytic performance. In this case, the primary metal may be ruthenium.

[0058] For example, the ammonia decomposition catalyst may have a pore volume of about 0.1 to 0.4 mL / g, or about 0.1 mL / g or more, or about 0.2 mL / g or more, or about 0.25 mL / g or more, or about 0.3 mL / g or more, or about 0.33 mL / g or more, and at the same time may be about 0.4 mL / g or less, or about 0.35 mL / g or less.

[0059] If the pore volume is excessively small, the active material may not enter the pores during the catalyst loading process, preventing the utilization of the specific surface area of ​​the structure and resulting in reduced catalytic performance. Conversely, if the pore volume is excessively large, the specific surface area becomes small, reducing the dispersion of the active material and potentially leading to reduced catalytic efficiency.

[0060] For example, the content of the catalytically active component, that is, the total amount of the first metal, the second metal, and the third metal, may be about 20 parts by weight or less, or about 0.1 parts by weight or more, or about 0.5 parts by weight or more, or about 1 part by weight or more, per 100 parts by weight of the entire catalyst, and at the same time may be about 20 parts by weight or less, less than about 18 parts by weight, or about 15 parts by weight or less, or about 11 parts by weight or less.

[0061] If the amount of catalytically active components is excessively low, a problem may arise in which the efficiency of the ammonia decomposition reaction decreases. If the amount of catalytically active components is excessively high, catalytically active substances that are not exposed on the surface may be produced, leading to a decrease in catalytic efficiency. Furthermore, problems may arise in which pores in the structure are blocked, creating a differential pressure and reducing catalytic performance.

[0062] For example, the weight ratio of (second metal):(third metal) may be approximately 1:99 to approximately 30:70, or approximately 1:99 or more, or approximately 10:90 or more, or approximately 20:80 or more, or approximately 23:77 or more, and at the same time may be approximately 30:70 or less, or approximately 25:75 or less.

[0063] For example, the weight ratio of (first metal):(second and third metal oxides) may be 1:99 to 10:90, or approximately 3:97 to 7:93. Although the compositional formula of the catalytically active component in this disclosure is shown in molar ratios according to the method of describing chemical formulas, the weight ratio will be measured and adjusted during actual catalyst production, so the weight ratio of (first metal):(second and third metal oxides) corresponding to the molar ratio of the compositional formula of the catalytically active component is as described above.

[0064] According to one embodiment of the invention, the catalytically active metal may be represented by the following chemical formula.

[0065] [ka]

[0066] In the above chemical formula, Ru is ruthenium, A is a second metal, B is a third metal, and O is oxygen. A and B are each independently one or more elements selected from the group consisting of lanthanum (La), cerium (Ce), aluminum (Al), and zirconium (Zr). x is between 1 and 5, more specifically, for example, 1 or more, 1.5 or more, 2 or more, or 3 or more, and at the same time 5 or less, or 4 or less, or 3.5 or less. y is between 1 and 15, more specifically, for example, 1 or more, 3 or more, 5 or more, or 10 or more, and at the same time 15 or less, 13 or less, or 11 or less. z is between 20 and 40, more specifically, for example, 20 or more, 25 or more, or 30 or more, and at the same time 40 or less, or 35 or less. u may vary depending on the oxidation state of the metal element, and may be between 50 and 90, more specifically, for example, 50 or more, or 60 or more, or 70 or more, and at the same time 90 or less, or 80 or less.

[0067] Specifically, A and B may be different from each other.

[0068] However, in an ammonia decomposition catalyst according to an example of the present invention, the composition of each element is not necessarily limited to the range described above.

[0069] For example, the ammonia decomposition catalyst may be porous spherical. A porous spherical shape is a porous spherical form, and the terms "sphere" and "sphere" here do not necessarily refer only to mathematically precise shapes, but rather to regular or irregular shapes such as spheres, ellipsoids, and polyhedra, where the ratio of the minor axis to the major axis is 0.5 or greater. In other words, it refers to shapes that are not long like a rod or greatly flattened. Furthermore, the minor axis refers to the shortest particle size measured with respect to the axis passing through the geometric center point of the particle, and the major axis refers to the longest particle size measured with respect to the axis passing through the geometric center point of the particle.

[0070] For example, the median diameter of the circle in the cross-section of the porous sphere may be approximately 1 to 10 mm, or approximately 1 mm or more, or approximately 2 mm or more, or approximately 3 mm or more, and at the same time, it may be approximately 10 mm or less, approximately 8 mm or less, approximately 6 mm or less, or approximately 4 mm or less.

[0071] If the median diameter of the circles in the cross-section of a porous sphere is excessively large, the packing density will be low, potentially causing reactants to bypass the catalyst and fail to come into contact with it, leading to a decrease in catalytic efficiency. Conversely, if the median diameter of the circles in the cross-section of a porous sphere is excessively small, the packing density will be high, creating a differential pressure, which can also lead to a decrease in reaction efficiency.

[0072] The catalyst mentioned above can be manufactured by the following method.

[0073] First, prepare an aqueous solution of ruthenium salt. Examples of ruthenium salt solutions include aqueous solutions of ruthenium fluoride, ruthenium chloride, ruthenium nitrate, ruthenium sulfate, and perruthenate ion.

[0074] Next, a second-metal-third-metal oxide powder is added to this mixture, and basic conditions are created using ammonia water or similar. This mixture is then filtered and washed, and dried in an oven at approximately 100-150°C for approximately 6-20 hours to obtain the powder.

[0075] The powder obtained here is added to distilled water, a zirconia ball is added, and the mixture is stirred with a roller to produce a slurry.

[0076] This is impregnated into a support and coated, the filtrate is removed, and then it is dried in an oven at approximately 100 to 150°C for approximately 6 to 20 hours. The weight of the dried sample is measured to confirm the amount of coated catalytic active component. The process of coating the support with the slurry solution and drying is repeated as many times as desired to obtain a supported catalyst in which the first, second, and third metals described above are supported on the support.

[0077] On the other hand, the supported catalyst produced by this method may be used as is as an ammonia decomposition catalyst, or it may be calcined or reduced and then used as an ammonia decomposition catalyst.

[0078] During calcination and reduction, the obtained catalyst can be treated with hydrogen gas at a temperature of approximately 300 to 600°C, or other calcination and reduction conditions commonly used in the technical field to which this invention belongs can be employed.

[0079] Furthermore, this specification provides a method for ammonia decomposition in which the ammonia decomposition reaction proceeds in the presence of any one of the ammonia decomposition catalysts described above.

[0080] In the ammonia decomposition method according to one example of the present invention, in addition to using the catalyst according to one example of the present invention, reaction conditions commonly used in the art to which the present invention belongs can be employed.

[0081] For example, the ammonia decomposition reaction may be carried out at approximately 400 to approximately 700°C, or approximately 400°C or higher, or more than approximately 400°C, or approximately 420°C or higher, and at the same time at approximately 700°C or lower, approximately 650°C or lower, approximately 600°C or lower, approximately 550°C or lower, or approximately 530°C or lower.

[0082] In other examples, the ammonia decomposition reaction may be carried out after purging with an inactive gas or the like prior to the main reaction.

[0083] Furthermore, the form of the reactor is not particularly limited during the reaction. Any suitable reactor can be selected and used that allows ammonia gas to be blown into the catalyst of the aforementioned form, thereby bringing the catalyst and reactants into direct contact. [Effects of the Invention]

[0084] This specification can provide an ammonia decomposition catalyst that exhibits excellent low-temperature decomposition performance at high space velocities.

[0085] Furthermore, this specification provides an ammonia decomposition catalyst that prevents catalytic thermal aggregation, provides reaction process stability, and has an improved lifespan.

[0086] Furthermore, this specification can provide a method for decomposing ammonia using such an ammonia decomposition catalyst. [Brief explanation of the drawing]

[0087] [Figure 1] This figure shows a porous spherical structure used in one embodiment of the present invention. [Figure 2] This figure shows a catalyst on which the active ingredient of one embodiment of the present invention is supported. [Figure 3] This figure shows a comparative example catalyst of the present invention. [Figure 4] This figure shows a comparative example catalyst of the present invention. [Figure 5] This figure shows a pore particle size distribution graph between a porous spherical structure of one experimental example of the present invention and Example 1 on which the active ingredient is supported. [Figure 6] This figure shows a graph of the NH3 conversion rate of the catalyst of Example 1 as it changes with temperature in the catalyst layer, representing one experimental example of the present invention. [Modes for carrying out the invention]

[0088] The operation and effects of the invention will be described in more detail below through specific embodiments of the invention. However, these embodiments are presented merely as examples of the invention and do not define the scope of the invention's rights.

[0089] (Example 1) For the metal components, we used an aqueous ruthenium chloride solution and LaCeria synthesized using the coprecipitation method.

[0090] A ruthenium chloride aqueous solution was prepared considering the content of each metal element in the catalytic active component. 20g of LaCeria was added to this solution, and the pH was adjusted to 9 using ammonia water.

[0091] The aforementioned solution was stirred for 18 hours using a stirrer and a magnetic bar. After filtering, the resulting liquid was filtered and washed with water until it became neutral, and then dried in an oven at 110°C for approximately 12 hours to obtain a powdered catalyst.

[0092] A catalyst solution was prepared by adding 18 g of the aforementioned powdered catalyst and 1.8 g of Boehmite to 72 mL of distilled water. 360 g of zirconia balls with a diameter of 5 mm or less were added to this solution, and the mixture was milled at 200 rpm for approximately 6 hours to adjust the particle size in the catalyst solution. To dissolve the Boehmite and use it as a binder, the pH was adjusted to 3.5 using a 60% nitric acid solution.

[0093] Approximately 50 g of a 3.2 mm porous spherical structure (material: aluminum silicate ball; manufacturer: Saint-Gobain Norpro; product name: SA52252) was added to the catalyst solution as a support and impregnated, after which the filtrate was removed using an air gun.

[0094] I put this in an oven at about 110°C and dried it for about 6 hours.

[0095] The catalyst solution was repeatedly impregnated with a support and dried until 10 parts by weight of the coated catalyst amounted to powder catalyst. As a result, a molded catalyst was obtained in which the catalytically active component was coated on the surface of a porous spherical structure.

[0096] The active metal component in the catalyst obtained using ICP-OES was analyzed, and the presence or absence of structural changes in the support was confirmed by Hg porosity.

[0097] (Examples 2-3) The supported catalyst was obtained by proceeding in the same manner as in Example 1, except that the amount of catalytically active material supported was changed by varying the number of coating cycles.

[0098] (Example 4) The supported catalyst was obtained in the same manner as in Example 1, except that commercial LaAlOx (manufacturer: Sasol; product name: TH100 / 150 / L10) was used instead of LaCeria synthesized using the coprecipitation method.

[0099] (Example 5) The supported catalyst was obtained in the same manner as in Example 1, except that commercial CeAlOx (manufacturer: Sasol; product name: TH100 / 150 / Ce20) was used instead of LaCeria synthesized by the coprecipitation method.

[0100] (Example 6) Except for increasing the concentration of the ruthenium aqueous solution by 2.4 times to increase the Ru content in the powder catalyst by approximately 2.4 times, the number of loading cycles, loading amount, etc., were carried out in the same manner as in Example 1 to obtain the supported catalyst.

[0101] (Example 7) The supported catalyst was obtained in the same manner as in Example 1, except that a 4.8 mm porous spherical structure (material: aluminum silicate ball; manufacturer: Saint-Gobain Norpro; product name: SA52252) was used as the support, and the number of loading steps was increased to 5 in order to achieve the same loading amount as in Example 1.

[0102] (Example 8) The supported catalyst was obtained in the same manner as in Example 1, except that a 6.1 mm porous spherical structure (material: aluminum silicate ball; manufacturer: Saint-Gobain Norpro; product name: SA52252) was used as the support, and the number of loading steps was increased to six to achieve the same loading amount as in Example 1.

[0103] (Comparative Example 1) Except for changing the number of coating cycles (number of loading cycles) to 10 and thereby changing the amount of catalytically active material loaded as shown in Table 1, the process was carried out in the same manner as in Example 1 to obtain a supported catalyst.

[0104] (Comparative Examples 2 and 3) In the case of Comparative Example 2, the process proceeded in the same manner as in Examples 1, 2, and 3 and Comparative Example 1, but without further loading, the resulting powder itself was molded to produce a catalyst.

[0105] In the case of Comparative Example 3, the process was carried out in the same manner as in Examples 1, 2, 3 and Comparative Example 1, and the catalyst was supported on a cylindrical ceramic hollow cylinder with a gap in the middle (material: ceramic rings; manufacturer: Saint-Gobain NorPro; product name: SA5518) until 13 wt% of the coated catalyst became powder catalyst.

[0106] (Comparative Example 4) A supported catalyst was obtained in the same manner as in Example 1, except that 21.5 g of powdered catalyst was added during catalyst milling to increase the viscosity of the catalyst solution.

[0107] The information obtained regarding the catalyst is summarized in Table 1 below.

[0108] [Table 1]

[0109] (Analysis of stomatal properties) The pore characteristics of the catalysts produced in the above examples and comparative examples were analyzed using a mercury pressure pore distribution analyzer (manufacturer: Micromerics; model name: AutoPoreV) and mercury pore analysis (ASTM D4284).

[0110] Without any separate pretreatment process, an appropriate amount of sample was placed in a sample cell, and then pressurized to a range of 0.2 to 33,000 psi to inject mercury into the catalyst pores and measure the pore volume. The average particle size obtained from the analysis was used as the median value of the pore particle size.

[0111] The analysis results are summarized in Table 2 below.

[0112] [Table 2]

[0113] Furthermore, the results of the analysis of the porosity characteristics of the porous spherical structure used as the support and the catalyst of Example 1 on which the active ingredient was supported are shown in Table 3 and Figure 5.

[0114] The measurement method was carried out in the same manner as the mercury pore analysis method described above.

[0115] [Table 3]

[0116] The results confirmed that the pore characteristics of the support did not change significantly even when the catalyst was supported.

[0117] (Ammonia decomposition reaction) Three g each of the catalysts produced in the above examples and comparative examples were taken, packed into an OD1 / 2” reactor, heated to 350°C using nitrogen gas, and then reduced by flowing a hydrogen / nitrogen mixed gas (50% hydrogen) at that temperature for approximately one hour.

[0118] The reduced catalyst is purged in a nitrogen atmosphere at approximately 350°C for approximately 30 minutes, and 99% ammonia gas is released at a high space velocity (GHSV, Gas hourly space velocity) of 4000 hV. -1 The reaction was carried out at a certain rate to raise the temperature of the reaction meter to approximately 400°C, and the ammonia decomposition rate was analyzed by increasing the temperature in 50°C increments up to 550°C.

[0119] The analysis results are summarized in Table 4 below.

[0120] The conversion rate was calculated by analyzing the outlet gas discharged from the reactor using gas chromatography, determining the ratio (n) of the volume of NH3 to the total volume of gas discharged, and then using the formula: conversion rate = (1-n) / (1+n).

[0121] The catalytic differential pressure characteristics were determined by measuring the pressure using pressure transmitters installed before and after the reactor, and calculating the pressure difference between the before and after stages.

[0122] The temperature difference in the catalyst layer was measured by inserting a thermocouple (TC) in the middle of the catalyst layer, and was determined by the difference between the temperature of the furnace used to heat the reactor and the temperature inside the catalyst layer.

[0123] The activity per gRu was calculated as (flow rate of ammonia added) * conversion rate / 22.4 / (mass of Ru in the packed catalyst).

[0124] [Table 4]

[0125] We were able to confirm that Examples 1-8 were superior to Comparative Examples 1-3 in terms of activity per unit of gRu, that is, activity per unit of ruthenium.

[0126] In particular, in the case of Comparative Example 1, although the porosity characteristics such as pore volume and porosity were similar to those of the Examples, it was confirmed that the activity per unit of gRu was significantly worse than that of the Examples. In particular, the large increase in the median pore size was due to the fact that the amount of catalyst coating in Comparative Example 1 was greater than that of the Examples, and the small pores in the 100 μm range were blocked by the catalyst coating, leaving only the large pores. This resulted in excessive coating of the catalyst, making it impossible to utilize the pores of the support. As a result, the activity per unit of gRu deteriorated compared to the Examples.

[0127] Furthermore, the catalysts used in the examples showed a low pressure difference between the upstream and downstream stages of the reactor, i.e., a low differential pressure. In contrast, Comparative Examples 3 and 4 showed high differential pressures of 0.9 and 0.7, respectively. This indicates that the gas flow in the catalyst-filled section of the reactor was not as smooth as in the examples, resulting in a significant decrease in catalytic performance across the entire reaction flow, regardless of the activity per unit of gRu.

[0128] Furthermore, comparing Example 6 and Comparative Example 1, although the weight ratio of Ru contained in the catalyst is similar, the number of loading cycles differs (4 for Example 6 and 10 for Comparative Example 1), which explains the difference in catalytic activity. As can be seen from the median pore size of Comparative Example 1, it is thought that as the number of loading cycles increases, smaller pores become blocked, preventing the catalyst trapped in the pores from participating in the reaction.

[0129] In Comparative Example 3, a large differential pressure was generated, preventing the reaction from proceeding at 550°C, and thus the conversion rate at 550°C could not be measured.

[0130] Comparative Example 4 was carried out in the same manner as Example 1, except that 21.5 g of powdered catalyst was added during milling to increase the viscosity of the catalyst solution. As a result, the median pore size became excessively small, and the pore volume also decreased. Furthermore, as the median pore size became excessively small, the differential pressure also increased, and the catalyst performance deteriorated.

Claims

1. The carrier comprises a catalytically active component supported on the carrier, The catalytic active component comprises i) ruthenium (Ru) as the first metal; ii) the second metal; and iii) the third metal; The second metal and the third metal are each independently one or more selected from the group consisting of lanthanum (La), cerium (Ce), aluminum (Al), and zirconium (Zr). The content of the first metal, ruthenium, is 0.1 to 1 part by weight per 100 parts by weight of the entire catalyst. The porosity is 30-60%. The median value of the pore size is 50 to 200 μm. Ammonia decomposition catalyst.

2. The stomatal volume is 0.1 to 0.4 mL / g. The ammonia decomposition catalyst according to claim 1.

3. The carrier is a porous spherical structure. The ammonia decomposition catalyst according to claim 1.

4. The carrier is an inorganic oxide structure. The ammonia decomposition catalyst according to claim 1.

5. The ammonia decomposition catalyst according to claim 1, wherein the content of the catalytic active component is 20 parts by weight or less per 100 parts by weight of the entire catalyst.

6. The ammonia decomposition catalyst according to claim 1, wherein the weight ratio of (second metal):(third metal) is 1:99 to 30:

70.

7. The ammonia decomposition catalyst according to claim 1, wherein the weight ratio of (first metal):(second metal and third metal oxide) is 1:99 to 10:

90.

8. The ammonia decomposition catalyst according to claim 1, which is porous and spherical.

9. The ammonia decomposition catalyst according to claim 8, wherein the median of the diameter of the circle in the cross-section of the porous sphere is 1 to 10 mm.

10. A method for decomposing ammonia, comprising carrying out an ammonia decomposition reaction in the presence of an ammonia decomposition catalyst according to any one of claims 1 to 9.

11. The ammonia decomposition method according to claim 10, carried out at 400 to 700°C.

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