Ammonia decomposition catalyst composite

Abstract

The present invention relates to an ammonia decomposition catalyst composite.

Description

Ammonia decomposition catalyst complex

[0001] The present invention relates to an ammonia decomposition catalyst complex.

[0002] Recently, with the intensification of climate change, hydrogen energy is garnering attention worldwide as an eco-friendly fuel to replace fossil fuels. One method for efficiently storing and transporting hydrogen is to use ammonia as a hydrogen source. Since the process of decomposing ammonia into hydrogen and nitrogen is endothermic, energy is required to obtain the products. Various catalysts are being researched and reported to reduce the energy required for ammonia decomposition.

[0003] For example, EP 2612706 A1 relates to an ammonia oxidation / decomposition catalyst and discloses a catalyst comprising the rare metal ruthenium as an active component and lanthanum oxide and / or cerium oxide as a support. However, catalysts proposed for ammonia decomposition in this manner have significant disadvantages in terms of economics because they utilize the rare metals ruthenium, lanthanum, and cerium. Therefore, research and development of an economical ammonia decomposition catalyst is necessary to ensure catalytic efficiency while minimizing the amount of rare metals.

[0004] The present invention aims to provide an ammonia decomposition catalyst complex using a support with reduced precious metal content.

[0005] However, the technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0006] One embodiment of the present invention provides an ammonia decomposition catalyst complex comprising: a metal oxide solid solution represented by the following chemical formula 1; a composite oxide support having metal oxide particles represented by the following chemical formula 2 provided on the metal oxide solid solution; and an active metal provided on the composite oxide support.

[0007] [Chemical Formula 1]

[0008] Mg α Al (1-α) O γ

[0009] In the above chemical formula 1, α is 0.5 or more and 0.9 or less, and γ is a value of 1 to 2, and

[0010] [Chemical Formula 2]

[0011] La β Ce (1-β) O δ

[0012] β is between 0.5 and 1, and δ is between 1 and 2.

[0013] The composite oxide support in the ammonia decomposition catalyst composite according to the present invention has a surface in which plate-shaped particles intersect each other, allowing for the support of an active metal with a high degree of dispersion, and enables excellent ammonia decomposition efficiency while reducing the amount of rare metals La and / or Ce applied to the composite oxide support.

[0014] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description below.

[0015] Figure 1 shows an SEM image of a composite oxide support prepared according to Example 1.

[0016] Figure 2 shows an SEM image of a composite oxide support prepared according to Example 2.

[0017] Figure 3 shows isothermal curves according to nitrogen adsorption-desorption analysis of composite oxide supports prepared according to Examples 1 and 2.

[0018] Figure 4 shows the EDS Mapping analysis results of the composite oxide support prepared according to Example 2.

[0019] Figure 5 shows the XRD analysis results before and after calcination of the composite oxide support prepared according to Example 2.

[0020] In this specification, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0021] In this specification, when a member is described as being located "on" another member, this includes not only cases where a member is in contact with another member, but also cases where another member exists between the two members.

[0022] The inventors have completed the present invention by conducting research on a novel ammonia decomposition catalyst composite that minimizes the content of rare metals La and Ce used as carriers of the ammonia decomposition catalyst composite while simultaneously preventing a decrease in the ammonia decomposition rate. Specifically, the present invention implements an ammonia decomposition catalyst composite that can drastically reduce the content of rare metals La and Ce without a decrease in the ammonia decomposition rate by applying Mg and Al, which are inexpensive and readily available metals.

[0023] The present invention will be described in detail below.

[0024] One embodiment of the present invention provides an ammonia decomposition catalyst complex comprising: a metal oxide solid solution represented by the following chemical formula 1; a composite oxide support having metal oxide particles represented by the following chemical formula 2 provided on the metal oxide solid solution; and an active metal provided on the composite oxide support.

[0025] [Chemical Formula 1]

[0026] Mg α Al (1-α) O γ

[0027] In the above chemical formula 1, α is 0.5 or more and 0.9 or less, and γ is a value of 1 to 2, and

[0028] [Chemical Formula 2]

[0029] La β Ce (1-β) O δ

[0030] β is between 0.5 and 1, and δ is between 1 and 2.

[0031] According to one embodiment of the present invention, α may be 0.6 or more and 0.85 or less, or 0.7 or more and 0.8 or less. Additionally, according to one embodiment of the present invention, β may be greater than 0.5 and less than or equal to 0.9, greater than or equal to 0.6 and less than or equal to 0.9, or greater than or equal to 0.7 and less than or equal to 0.9.

[0032] According to one embodiment of the present invention, the content of metal oxide particles represented by Formula 2 in the composite oxide support may be 5 mol% to 20 mol%. Specifically, the content of metal oxide particles represented by Formula 2 may be 5 mol% to 15 mol%, or 7 mol% to 12 mol%. The content of metal oxide particles represented by Formula 2 may be equal to the content of La, or the content of La and Ce, relative to the total metal elements. As described above, the composite oxide support serving as a support in the ammonia decomposition catalyst composite according to the present invention can significantly reduce the content of La, or the content of La and Ce, in the entire composite oxide support to the above range, thereby providing the advantage of easier raw material procurement and cost reduction compared to conventional ammonia decomposition catalyst composites.

[0033] According to one embodiment of the present invention, the metal oxide solid solution represented by the chemical formula 1 may be a magnesium-aluminum oxide solid solution in which aluminum is substituted within the lattice of magnesium oxide.

[0034] According to one embodiment of the present invention, β in the formula 2 is 0.5 or more and 0.9 or less, and the metal oxide particle represented by the formula 2 may be a cerium-lanthanum oxide solid solution particle in which lanthanum is substituted within the lattice of cerium oxide.

[0035] Specifically, the composite oxide support may be provided with cerium-lanthanum oxide solid solution particles on the magnesium-aluminum oxide solid solution. Furthermore, the cerium-lanthanum oxide solid solution may be 5 mol% to 20 mol%, 5 mol% to 15 mol%, or 7 mol% to 12 mol% with respect to the total composite oxide support. As described above, the composite oxide support has the advantage of significantly reducing the amount of cerium lanthanum, a rare metal, thereby ensuring economic feasibility in the manufacture of ammonia decomposition catalyst composites. Specifically, the composite oxide support reflecting this may be represented by the following chemical formula 3.

[0036] [Chemical Formula 3]

[0037] x[Mg α Al (1-α) O γ ]-y[La β Ce (1-β) O δ ]

[0038] In the above chemical formula 3, α, β, γ, and δ are each as described above, and x:y may be 9.5:0.5 to 8:2.

[0039] According to one embodiment of the present invention, the composite oxide support may have a surface having a shape in which plate-like particles intersect each other. Specifically, the composite oxide support may be a layered material that has been broken down by sintering, and may have a shape in which plate-like particles and fragments thereof are stacked. Due to these characteristics, the composite oxide support has an abundant space for the active metal to be located, and thus may have a surface and pore structure in which the active metal can be supported with a high degree of dispersion. Such a surface shape can be confirmed by the shape of the graph according to nitrogen adsorption-desorption analysis.

[0040] According to one embodiment of the present invention, the composite oxide support may have a surface with a mesoporous pore structure exhibiting the shape of an H3 hysteresis curve during nitrogen adsorption-desorption analysis. Specifically, the shape of the H3 hysteresis curve may mean that thin plate-like particles are intertwined to form a wedge-shaped mesoporous pore structure surface, which may mean that the layered structure of the Mg-Al layered double hydroxide collapses after calcination and the plate-like particles accumulate to form a mesoporous surface. Due to these morphological characteristics, the composite oxide support can support a very large amount of active metal, which can be confirmed by the high dispersibility of the active metal.

[0041] Furthermore, the active metal can be supported on the surface of La oxide particles or La-Ce oxide particles as well as on the Mg-Al metal oxide solid solution of the composite oxide support, thereby further enhancing the activity of the active metal. Specifically, the La oxide particles or La-Ce oxide particles act as co-catalysts, promoting the adsorption and decomposition of ammonia reactants injected in a gaseous state on the surface of the active metal, which is the main catalyst, thereby further improving the catalytic efficiency of the ammonia decomposition catalyst composite.

[0042] According to one embodiment of the present invention, the active metal may be Ru.

[0043] Another embodiment of the present invention provides a method for manufacturing the ammonia decomposition catalyst complex. Specifically, another embodiment of the present invention provides a method for manufacturing the ammonia decomposition catalyst complex comprising: a step of preparing a precursor solution comprising a La precursor, a Mg precursor, an Al precursor, and optionally a Ce precursor; a step of adding an anionic stabilizer and a basic precipitating agent to the precursor solution to form a complex metal aggregation nucleus; a step of hydrothermally synthesizing the precursor solution having the complex metal aggregation nucleus formed thereon to form a hydrothermally synthesized product comprising a layered double hydroxide of Mg and Al and a metal oxide precursor comprising La; a step of calcining the hydrothermally synthesized product to form a complex oxide support having metal oxide particles represented by the following chemical formula 2 provided on a metal oxide solid solution represented by the following chemical formula 1; and a step of supporting an active metal on the complex oxide support.

[0044] According to one embodiment of the present invention, the La precursor, Ce precursor, Mg precursor and Al precursor may each be an oxide, chloride, hydroxide, bromide, iodide, nitrate, sulfate, carbonate, acetate, oxalate, fluoride, isopropoxide, or organometallic complex of La, Ce, Mg, and Al.

[0045] According to one embodiment of the present invention, the precursor solution may further comprise a solvent capable of dissolving a La precursor, a Ce precursor, a Mg precursor, and an Al precursor. The solvent may be selected to be suitable for the precursors and may be a water-soluble solvent, for example, water.

[0046] The anionic stabilizer described above binds to metal cations derived from the precursor, enabling them to remain in a stable state within the solution. Specifically, the anionic stabilizer can prevent metal ions from aggregating or precipitating. An anionic stabilizer performing this role may be a compound containing inorganic or organic anions. Specifically, according to one embodiment of the present invention, the anionic stabilizer may be a compound containing anions such as carbonates, chloride salts, sulfates, carboxylate salts, etc. For example, the anionic stabilizer may include at least one selected from the group consisting of sodium carbonate, calcium carbonate, potassium carbonate, magnesium carbonate, sodium chloride, potassium chloride, calcium chloride, magnesium chloride, ammonium chloride, sodium sulfate, potassium sulfate, calcium sulfate, magnesium sulfate, sodium acetate, and potassium formate. However, it is not limited thereto, and any substance intended to stabilize metal cations within the precursor solution may be applied without limitation.

[0047] According to one embodiment of the present invention, the amount of anionic stabilizer added can be adjusted so that the molar ratio of the metal cation in the precursor solution to the anion of the anionic stabilizer is 1:1 to 2:1. When the amount of anionic stabilizer added is adjusted as described above, the interlayer spacing of the layered double hydroxide of Mg and Al formed through hydrothermal synthesis can be appropriately adjusted to ensure structural stability. Furthermore, when the amount of anionic stabilizer added is adjusted as described above, the metal oxide precursor of La, or La and Ce, can be evenly distributed on the surface of the layered double hydroxide of Mg and Al formed through hydrothermal synthesis.

[0048] The above basic precipitating agent can form a precipitate by inducing a reaction between the metal ions in the precursor solution and the hydroxyl groups of the basic precipitating agent, thereby forming complex metal aggregation nuclei of La, Ce, Mg, and Al. According to one embodiment of the present invention, the basic precipitating agent may be an aqueous solution comprising at least one selected from the group consisting of ammonia water, sodium hydroxide, potassium hydroxide, hydrazine, and sodium carbonate. Specifically, the basic substance may be ammonia water.

[0049] The basic precipitating agent may be added to the precursor solution by adding it dropwise to induce uniform growth of the metal aggregation nuclei. Specifically, the basic precipitating agent may be added until the pH of the precursor solution reaches 9 to 12. More specifically, the basic precipitating agent may be added until the pH of the precursor solution reaches 9.5 to 11 or 9.5 to 10.5. If the pH of the precursor solution is below the above range, the metal precursor may not aggregate and precipitate sufficiently. Furthermore, if the pH of the precursor solution is excessively high, or if the basic precipitating agent is continuously added after reaching the aforementioned pH, the aggregation nuclei may grow excessively, making it impossible to form layered double hydroxides of Mg and Al through subsequent hydrothermal synthesis.

[0050] The above hydrothermal synthesis can be performed using a reactor that enables hydrothermal synthesis by generating high temperature and high pressure, such as a Teflon-lined autoclave. The above hydrothermal synthesis can be performed using a precursor solution in which metal aggregation nuclei are formed, and through hydrothermal synthesis, the metal aggregation nuclei grow using metal ions remaining in the precursor solution, thereby forming a layered double hydroxide of Mg and Al. Furthermore, through the above hydrothermal synthesis, a metal oxide precursor of La, or La and Ce, can be evenly distributed on the surface of the layered double hydroxide of Mg and Al. The metal oxide precursor may be in the form of a solid precipitate, which can be converted into a metal oxide through subsequent calcination.

[0051] According to one embodiment of the present invention, the hydrothermal synthesis may be performed within a temperature range of 120 ℃ to 160 ℃. Specifically, the hydrothermal synthesis may be performed within a temperature range of 120 ℃ to 140 ℃, or 120 ℃ to 130 ℃. When hydrothermal synthesis is performed within the above temperature range, layered double hydroxides of Mg and Al with a stable structure may be formed. Specifically, when hydrothermal synthesis proceeds at a temperature below the above range, D 110 / D 003 As the ratio increases, layered double hydroxides of Mg and Al with thin, plate-like particle structures are formed, which may lead to problems with low physicochemical stability. Additionally, if hydrothermal synthesis proceeds at a temperature exceeding the above range, D 110 / D 003 As the ratio decreases, layered double hydroxides of Mg and Al are formed with an excessively thick and short plate-like structure, which may result in a surface morphology that makes it difficult to support active metals with a high degree of dispersion after sintering.

[0052] According to one embodiment of the present invention, the calcination may be a process for forming the layered double hydroxide of Mg and Al into a metal oxide solid solution, wherein the layered structure of the layered double hydroxide of Mg and Al collapses and may be formed in a shape in which plate-like particles are stacked. Furthermore, through the calcination, metal oxide precursors of La, or La and Ce distributed on the layered double hydroxide of Mg and Al may be converted into metal oxide particles.

[0053] According to one embodiment of the present invention, the calcination may be performed in a temperature range of 400 ℃ to 600 ℃ and under an air atmosphere. Specifically, the calcination may be performed in a temperature range of 450 ℃ to 550 ℃, or 500 ℃ to 550 ℃. If calcination is performed at a temperature below the above range, anions and water molecules present inside the layered double hydroxide of Mg and Al are not sufficiently removed, which may result in a deterioration of the physical properties of the composite oxide support. Furthermore, if calcination is performed at a temperature above the above range, a composite oxide support with a structure such as a spinel structure rather than a periclase structure may be formed, and a composite oxide support with the aforementioned physical properties may not be realized. Moreover, a problem may arise in which the metal oxide particles represented by Chemical Formula 2 may aggregate excessively, resulting in a reduced surface area and consequently lower dispersibility of the active metal.

[0054] According to one embodiment of the present invention, the step of supporting the active metal may apply any method known in the art for supporting metal particles on a carrier, including impregnation and precipitation methods, without limitation. For example, the active metal may be supported on the composite oxide carrier by dispersing the composite oxide carrier in distilled water, adding a precursor of the active metal and stirring, and then heat-treating the mixture.

[0055] According to one embodiment of the present invention, the method may further include a step of reducing the ammonia decomposition catalyst complex in an inert gas atmosphere containing at least 10 vol% hydrogen and in a temperature range of 500 ℃ to 650 ℃. The reduction treatment can remove residues such as oxygen and precursor anions attached to the active metal, thereby enabling the securing of more active sites of the active metal.

[0056] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0057] [Examples 1 to 4 and Comparative Examples 1 to 3]

[0058] A precursor solution was prepared by dissolving magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, lanthanum nitrate hexahydrate, and cerium nitrate hexahydrate in distilled water so that the molar ratios of Mg, Al, La, and Ce were as shown in Table 1 below.

[0059] A 0.5 M aqueous sodium carbonate solution and a 1 M aqueous sodium hydroxide solution were prepared such that the carbonate anions of sodium carbonate and the metal cations were in equal molar amounts (1:1 molar ratio), and these were added dropwise to the prepared precursor solution to induce precipitation of complex metal aggregation nuclei, but the addition of the sodium hydroxide solution was stopped when the pH reached 10. Then, aging was carried out at room temperature for about 1 hour.

[0060] A composite metal aggregation nucleation precipitate was introduced into a Teflon-lined autoclave and heated to a temperature of approximately 120 °C for about 3 hours to carry out a hydrothermal reaction. The hydrothermal synthesis product obtained through the hydrothermal reaction was filtered and washed with water, and then dried in an oven at approximately 60 °C. Subsequently, the hydrothermal synthesis product was calcined in an air atmosphere at a temperature of approximately 550 °C to prepare a composite oxide support.

[0061] 3 g of a composite oxide support was dispersed in 36 ml of distilled water, and then 0.1463 g of ruthenium chloride hydrate was added and stirred for about 3 hours. The stirred solution was heated to a temperature of about 45 °C in a rotary evaporator to evaporate the solution, and then dried in a vacuum oven at about 150 °C for 10 hours. The dried solid was washed with water and dried to obtain an ammonia decomposition catalyst composite in which ruthenium is supported on a composite oxide support.

[0062] Then, 0.2 g of the ammonia decomposition catalyst complex was packed into a fixed-bed reactor and subjected to reduction treatment under a hydrogen atmosphere at 600 °C for 2 hours. Subsequently, the reactant ammonia was introduced into the fixed-bed reactor in a gaseous state via a Mass Flow Controller (MFC) after a preheating step, and at 450 °C and 6,000 g cat / ml / h -1 The ammonia decomposition reaction was carried out under WHSV conditions. At this time, the ammonia decomposition conversion rate was measured using GC (Gas chromatography) and is shown in Table 1 below.

[0063] Manufacturing Method Mg : Al : La : Ce Molar Ratio Ammonia Decomposition Conversion Rate (@450℃) (%) Example 1 Co-precipitation method and hydrothermal synthesis 75 : 15 : 9 : 1 78.89 Example 2 Co-precipitation method and hydrothermal synthesis 75 : 15 : 7 : 3 70.54 Example 3 Co-precipitation method and hydrothermal synthesis 75 : 15 : 5 : 5 62.31 Example 4 Co-precipitation method and hydrothermal synthesis 75 : 15 : 10 : 0 70.10 Comparative Example 1 Co-precipitation method and hydrothermal synthesis 75 : 15 : 1 : 9 57.15 Comparative Example 2 Co-precipitation method and hydrothermal synthesis 75 : 15 : 0 : 10 59.29 Comparative Example 3 Co-precipitation method and hydrothermal synthesis 75 : 15 : 0 : 0 33.58

[0064] Figures 1 and 2 show SEM images of composite oxide supports prepared according to Example 1 and Example 2, respectively. According to Figure 1, it was confirmed that the surface of the composite oxide support prepared according to the example was formed with a mesoporous structure formed by intertwining thin plates.

[0065] Furthermore, the specific surface area, pore volume, and BJH (Barrett-Joyner-Halenda) pore size obtained through BET calculation of the composite oxide supports prepared according to Examples 1 and 2 were as shown in Table 2 below.

[0066] BET surface area(m 2 g -1 )Pore volume(cm 3 g -1 )BJH pore size(nm) Example 18 4.7 0.4 45521 Example 29 9.2 0.6 0 3938

[0067] Analysis of specific surface area and pore size was performed by pre-treating the samples at 150 °C for 6 hours under a vacuum atmosphere and then measuring them using a BELSORP-MAX instrument from MicrotracBEL. The specific surface area of ​​the samples was calculated by the Brunauer-Emmett-Teller (BET) method at a relative pressure range of 0.05 to 0.2 and a temperature of -196 °C (77 K). Pore size was determined using the Barrett-Joyner-Halenda (BJH) method, and the total pore volume was estimated from the amount of adsorbed nitrogen at P / P0 = 0.95.

[0068] According to Table 2 above, the specific surface area of ​​the composite oxide support prepared according to Examples 1 and 2 was relatively small, but the distribution of mesopores with large pore sizes was high, and accordingly, it was confirmed that conditions were provided for the even distribution of the active metal.

[0069] Furthermore, FIG. 3 shows isothermal curves based on nitrogen adsorption-desorption analysis of composite oxide supports prepared according to Examples 1 and 2. According to FIG. 3, it was confirmed that the adsorption-desorption curves of the composite oxide supports prepared according to Examples 1 and 2 exhibit the shape of an H3 hysteresis curve. The shape of the H3 hysteresis curve may indicate that the thin plate-like particles are intertwined with each other to form a surface with a wedge-shaped mesoporous pore structure.

[0070] In addition, Figure 4 shows the EDS Mapping analysis results of the composite oxide support prepared according to Example 2. According to Figure 4, it was found that the Mg and Al elements were distributed at the same locations to form a solid solution. In addition, it was found that the La and Ce elements were also distributed at the same locations and formed a uniform distribution of composite metal oxide particles.

[0071] Figure 5 shows the XRD analysis results of the composite oxide support prepared according to Example 2 before and after calcination. According to Figure 5, it was confirmed that crystal peaks of the double hydroxide interlayer structure were observed in the composite oxide support before calcination, while crystal peaks of the double hydroxide interlayer structure were not found in the composite oxide support after calcination. Furthermore, in the composite oxide support after calcination, peaks attributable to magnesium oxide and cerium oxide were observed, which are attributed to the periclase structure, while peaks corresponding to aluminum and lanthanum were not observed. Through this, it was found that through calcination, magnesium-aluminum oxide solid solution particles in which aluminum is substituted within the magnesium oxide lattice and cerium-lanthanum oxide solid solution particles in which lanthanum is substituted within the cerium oxide lattice were formed.

[0072] Furthermore, when considering the results according to Fig. 5 together with the surface image and pore characteristics of the composite oxide support examined earlier, it can be confirmed that the plate-like shape of the composite oxide support is maintained by firing, while the interlayer structure collapses.

[0073] Referring to Table 1, Comparative Example 3, prepared using only a Mg-Al oxide solid solution without metal oxide particles, exhibited the lowest ammonia decomposition conversion rate. Furthermore, it was confirmed that the ammonia decomposition conversion rate was very low when La was absent or contained only in trace amounts in the metal oxide particles provided on the Mg-Al oxide solid solution (i.e., Comparative Examples 1 and 2). Through this, it can be inferred that La in the metal oxide particles provides an appropriate electron density to the surface of the Ru metal, which is the main catalyst during ammonia decomposition, thereby enhancing catalytic activity.

[0074] Furthermore, referring to Example 3, it was confirmed that the content of La among the metal elements in the metal oxide particles must be 50 mol% or more to achieve an ammonia decomposition conversion rate of 60% or more. Also, in the case of Example 4, where all metal elements in the metal oxide particles were La, it was confirmed that a lower ammonia decomposition conversion rate was exhibited compared to Example 1, which contained a trace amount of Ce. Through this, it can be inferred that Ce plays a role in highly dispersing La, thereby significantly enhancing the role of La as a co-catalyst. In other words, it was confirmed that the best ammonia decomposition conversion rate can be achieved when both La and Ce are included in the metal oxide particles of the composite oxide support, but the content of La is higher than the content of Ce.

Claims

1. A metal oxide solid solution represented by the following chemical formula 1, and a composite oxide support having metal oxide particles represented by the following chemical formula 2 provided on the metal oxide solid solution; and Ammonia decomposition catalyst complex comprising an active metal provided on the above-mentioned composite oxide support: [Chemical Formula 1] Mg α Al (1-α) O γ In the above chemical formula 1, α is 0.5 or more and 0.9 or less, and γ is a value of 1 to 2, and [Chemical Formula 2] to β What (1-β) A δ β is between 0.5 and 1, and δ is between 1 and 2.

2. In Claim 1, An ammonia decomposition catalyst composite having a content of metal oxide particles represented by Chemical Formula 2 in the composite oxide support of the above, ranging from 5 mol% to 20 mol%.

3. In Claim 1, An ammonia decomposition catalyst complex in which the metal oxide solid solution represented by the above chemical formula 1 is a magnesium-aluminum oxide solid solution in which aluminum is substituted within the lattice of magnesium oxide.

4. In Claim 1, An ammonia decomposition catalyst complex in which β in Chemical Formula 2 above is 0.5 or more and 0.9 or less.

5. In Claim 4, An ammonia decomposition catalyst complex in which the metal oxide particles represented by the above chemical formula 2 are cerium-lanthanum oxide solid solution particles in which lanthanum is substituted within the lattice of cerium oxide.

6. In Claim 1, The above composite oxide support is an ammonia decomposition catalyst composite having a mesoporous pore structure that exhibits the shape of an H3 hysteresis curve during nitrogen adsorption-desorption analysis.

7. In Claim 1, The above-mentioned composite oxide support is an ammonia decomposition catalyst composite having a surface in which plate-shaped particles intersect each other.

8. In Claim 1, Ammonia decomposition catalyst complex in which the active metal is Ru.

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