JP7352487B2 - Ammonia decomposition catalyst - Google Patents

Description

The present invention relates to an ammonia decomposition catalyst that can efficiently decompose ammonia into nitrogen and hydrogen, a method for producing an ammonia decomposition catalyst, and a method for producing hydrogen and nitrogen using the ammonia decomposition catalyst.

Hydrogen easily forms covalent bonds with other atoms, the only compound produced during combustion is water, and it has a large amount of heat per mass. For this reason, hydrogen is used for desulfurization in petroleum refining and in the production of petroleum products, and in recent years, demand has been increasing as a fuel for fuel cells. Hydrogen is often supplied on-site by industrial gas companies and others by installing hydrogen production equipment at users' industrial plants. However, it is thought that the supply of hydrogen from hydrogen production sites to hydrogen stations will increase in the future.

As means of transporting hydrogen, transportation of high-pressure hydrogen gas, transportation of liquefied hydrogen gas, and transportation of organic hydride are being considered. However, high-pressure hydrogen gas and liquefied hydrogen gas are extremely dangerous in the event of an accident. Regarding the transportation of organic hydrides, for example, it is being considered to reduce toluene to obtain methylcyclohexane, transport the relatively safe methylcyclohexane, and dehydrogenate it at the point of demand to obtain hydrogen. However, this method has a problem in that, once hydrogen is produced, excess energy is required for reduction of toluene and dehydrogenation of methylcyclohexane.

Therefore, ammonia is attracting attention as a hydrogen carrier. The industrial manufacturing method for ammonia itself has been established for a long time, and ammonia can be easily liquefied even at room temperature, and its volumetric hydrogen density is about 1.5 to 2.5 times higher than that of liquefied hydrogen. has. However, there is still a need to develop technology to efficiently produce hydrogen from ammonia after transporting the ammonia.

For example, Patent Document 1 describes a method for efficiently decomposing ammonia into hydrogen and nitrogen at relatively low temperatures and high space velocities in a wide range of ammonia concentrations from low to high concentrations without using precious metals. An ammonia decomposition catalyst containing an iron group metal and a metal oxide is disclosed as a catalyst capable of obtaining pure hydrogen.

Patent Document 2 discloses that the metal particles contain an oxide of an element selected from the group consisting of rare earths, alkali metals, and alkaline earth metals, and metal particles of an element selected from the group consisting of Co, Ni, and Fe, and have improved catalytic performance. An ammonia decomposition catalyst capable of regenerating ammonia is disclosed.

Patent Document 3 discloses a catalyst that includes an element selected from nickel, cobalt, and iron, an element selected from strontium and barium, and lanthanoids excluding lanthanum and cerium, and is capable of efficiently producing hydrogen from ammonia. has been done.

Patent Document 4 discloses a catalyst that includes an element selected from nickel, cobalt, and iron, an element selected from strontium and barium, a rare earth element, and magnesium, and is capable of efficiently producing hydrogen from ammonia. .

JP2010-94668A Japanese Patent Application Publication No. 2012-254419 Japanese Patent Application Publication No. 2016-203052 JP 2019-11212 Publication

As mentioned above, various catalysts have been studied to efficiently produce hydrogen by decomposing ammonia, but as the amount of hydrogen used increases, ammonia decomposition catalysts with even higher efficiency are required. .
Therefore, an object of the present invention is to provide an ammonia decomposition catalyst that can efficiently decompose ammonia into hydrogen and nitrogen, a method for producing an ammonia decomposition catalyst, and a method for producing hydrogen and nitrogen using the ammonia decomposition catalyst. shall be.

The present inventors have conducted extensive research in order to solve the above problems. As a result, the present invention was completed by discovering that by appropriately specifying the components and their contents, an ammonia decomposition catalyst that can efficiently decompose ammonia into hydrogen and nitrogen can be obtained.
The present invention will be described below.

[1] Contains an active ingredient,
the active ingredient comprises cobalt, yttrium, and one or more alkaline earth metals selected from strontium and barium;
The proportion of cobalt is 50% by mass or more in terms of oxide,
The proportion of yttrium is 1% by mass or more and 40% by mass or less in terms of oxide,
An ammonia decomposition catalyst characterized in that the proportion of the alkaline earth metal is 0.1% by mass or more and 10% by mass or less in terms of oxide.
[2] The ammonia decomposition catalyst according to [1] above, wherein the alkaline earth metal is barium.
[3] The ammonia decomposition catalyst according to [1] or [2] above, further containing zirconium in an amount of 0.1% by mass or more and 15% by mass or less in terms of oxide.
[4] Impregnating a cobalt compound with a solution containing yttrium and one or more alkaline earth metals selected from strontium and barium;
drying the cobalt compound impregnated with the solution, and
A method for producing an ammonia decomposition catalyst, comprising the step of calcining the dried cobalt compound.
[5] The production method according to the above [4], wherein the cobalt compound is basic cobalt carbonate.
[6] A step of subjecting the ammonia decomposition catalyst according to any one of [1] to [3] above to a reduction treatment, and
A method for producing hydrogen and nitrogen, comprising the step of decomposing ammonia into hydrogen and nitrogen by bringing a gas containing ammonia into contact with the reduced ammonia decomposition catalyst.

According to the ammonia decomposition catalyst according to the present invention, hydrogen and nitrogen can be efficiently produced from ammonia. Therefore, the present invention is industrially useful as contributing to the coming hydrogen society.

Generally, as an ammonia decomposition catalyst, a method using iron-based metals such as iron, cobalt, and nickel as an active ingredient is known, but it has low activity and insufficient durability. In contrast, the ammonia decomposition catalyst according to the present invention contains an active component containing cobalt, yttrium, and one or more alkaline earth metals selected from strontium and barium. These cobalt, yttrium, and alkaline earth metals are catalytically active components and can act synergistically with each other to efficiently decompose ammonia into hydrogen and nitrogen. In other words, by blending cobalt as the main component with yttrium and alkaline earth metals in an optimal ratio, it decomposes ammonia into nitrogen and hydrogen even at relatively low temperatures, and maintains a stable structure over a long period of time. A durable catalyst can be provided.

The proportion of cobalt in the ammonia decomposition catalyst according to the present invention (hereinafter sometimes abbreviated as "the present catalyst") is 50% by mass or more in terms of oxide. In the present disclosure, the proportion of each element is calculated as an oxide because the catalyst of the present invention is ultimately manufactured by firing in air at high temperature, and the metal elements are considered to exist as oxides. This is because the invention catalyst is subjected to a reduction treatment before use, and at that stage, whether each metal element is completely reduced, only a portion thereof, or not reduced at all depends on the reduction conditions. The above proportion of cobalt is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and is preferably 98% by mass or less, more preferably 95% by mass or less, and 92% by mass or less. % or less is even more preferable.

The proportion of yttrium in the catalyst of the present invention is 1% by mass or more and 40% by mass or less in terms of oxide. The proportion is preferably 2% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less, and 15% by mass or less. is even more preferred.

As the alkaline earth metal, strontium and barium may be used together, or strontium or barium may be used alone. The proportion of the alkaline earth metal in the catalyst of the present invention is 0.1% by mass or more and 10% by mass or less in terms of oxide. The proportion is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and preferably 8% by mass or less, more preferably 6% by mass or less, It is even more preferably 5% by mass or less. Barium is particularly preferred as the alkaline earth metal. By using barium, the ammonia decomposition performance at low temperatures is significantly improved.

In addition to the above-mentioned cobalt, yttrium and the above-mentioned alkaline earth metal, it is preferable to further add zirconium as an active ingredient. The proportion of zirconium in the catalyst of the present invention is preferably 0.1% by mass or more and 15% by mass or less in terms of oxide. The proportion is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, and preferably 10% by mass or less, more preferably 8% by mass or less, 6% by mass or less. % or less is even more preferable. By adding zirconium as an active ingredient, the effect of improving initial activity and durability performance can be obtained.

The proportion of each metal oxide in the catalyst of the present invention may be determined from the amount of metal elements contained in the raw material compound used for its production, or it may be determined by directly measuring the catalyst of the present invention using fluorescent X-rays or the like. It can also be found by adding .

The catalyst of the present invention may contain a carrier component in addition to the above catalytically active components. The carrier component is not particularly limited as long as it exhibits the above-mentioned effects, but for example, one or more carrier metal oxides selected from alumina, silica, titanium oxide, and niobium oxide can be suitably used. By incorporating a carrier component into the catalyst of the present invention, an effect of improving ammonia decomposition activity and an effect of increasing thermal stability of the catalyst component can be expected. Furthermore, when molding a catalyst, the carrier component functions as a binder and can increase mechanical strength.

From the viewpoint of improving ammonia decomposition activity, the carrier component preferably has a specific surface area of 10 m ² /g or more. The specific surface area is more preferably 20 m ² /g or more, and even more preferably 100 m ² /g or more. The upper limit of the specific surface area is not particularly limited, but may be, for example, 300 m ² /g or less.

The proportion of the carrier component in the catalyst of the present invention may be adjusted as appropriate within the range in which the above-mentioned effects are exhibited, but, for example, it is preferably 30% by mass or less in terms of oxide. The proportion of the carrier component is preferably 20% by mass or less, more preferably 10% by mass or less. Although the carrier component does not need to be blended, the proportion when blended is preferably 1% by mass or more, more preferably 2% by mass or more.

The specific surface area of the catalyst of the present invention can be, for example, 1 m ² /g or more and 300 m ² /g or less. If the specific surface area is 1 m ² /g or more, gas containing ammonia can be better distributed to the catalyst layer, and if it is 300 m ² /g or less, contact between the gas containing ammonia and the catalyst can be improved. The area can be secured more reliably, and the reaction can proceed more favorably. The specific surface area is preferably 5 m ² /g or more, more preferably 18 m ² /g or more, and preferably 250 m ² /g or less, more preferably 200 m ² /g or less. The specific surface area of the catalyst of the present invention may be measured by a conventional method, for example, by using a general surface area measuring device such as a fully automatic BET surface area measuring device (“Marcsorb HM Model-1201” manufactured by Mountech Co., Ltd.). Bye.

The size of the crystals constituting the catalyst of the present invention, particularly the crystals of cobalt oxide which is an active component in the catalyst, can be 3 nm or more and 200 nm or less. The crystallite size is preferably 5 nm or more, more preferably 10 nm or more, and preferably 150 nm or less, and more preferably 100 nm or less. The above-mentioned crystallite size may be measured by a conventional method, but for example, the catalyst of the present invention is analyzed by X-ray diffraction method, the crystal structure is assigned based on the obtained analysis results, the 2θ value is determined, and the 2θ value is determined using the Scherrer equation. It can be calculated.

Although the catalyst of the present invention may be produced by a conventional method, it is preferably produced by an impregnation method. For example, a step of impregnating a cobalt compound with a solution in which a soluble salt of yttrium and a soluble salt of one or more alkaline earth metals selected from strontium and barium is dissolved in a solvent; It can be manufactured by a method including a step of drying and a step of firing the dried cobalt compound.

As the cobalt compound, solid compounds such as cobalt oxide, basic cobalt carbonate, and cobalt hydroxide can be used, and it is particularly preferable to use basic cobalt carbonate, which can increase the specific surface area of the produced catalyst. Furthermore, water is preferred as the solvent, but acidic solutions with high solubility such as nitric acid may also be used. The soluble salts of yttrium and the above-mentioned alkaline earth metals are not particularly limited as long as they can be dissolved in a solvent at an appropriate concentration, and include, for example, metal nitrates, sulfates, acetates, etc., with nitrates being preferred.
As a method for producing the catalyst of the present invention, an impregnation method is preferable, and it is particularly preferable to reduce the amount of solvent of a solution of a metal soluble salt to be impregnated and mix it with a cobalt compound to produce the catalyst in the form of a paste. Hereinafter, such an impregnation method will be referred to as a "kneading method." The solid content concentration of the paste can be 20% by mass or more and 70% by mass or less, preferably 30% by mass or more and 50% by mass or less.

Alternatively, as a coprecipitation method, sodium hydroxide or potassium hydroxide is added to a solution in which cobalt, yttrium, and the above-mentioned alkaline earth metal soluble salts are dissolved in a solvent to cause hydrolysis and co-precipitation of a composite metal compound. After filtering, the catalyst of the present invention may be obtained by drying and then calcination. However, when the coprecipitation method is used, alkaline earth metal precipitates may be distilled out by washing with water, and a catalyst having a composition that corresponds to the relative ratio of the raw material compounds used may not be obtained.

The firing conditions are not particularly limited and may be adjusted as appropriate, but for example, firing is preferably performed at 250° C. or higher and 1000° C. or lower for 1 hour or more and 10 hours or less. The firing temperature may be increased continuously or stepwise.

The shape of the catalyst of the present invention is not particularly limited, and may be, for example, granular, spherical, pellet-like, crushed, saddle-like, ring-like, honeycomb-like, monolith-like, rod-like, cylindrical, or cylindrical.

The catalyst of the present invention is preferably subjected to a reduction treatment before the ammonia decomposition step. The ammonia decomposition activity of the catalyst of the present invention can be improved by specifically forming metallic cobalt from cobalt oxide in the reduction treatment. Examples of the reduction treatment include a method using a reducing gas such as hydrogen, hydrocarbon, or carbon monoxide; a method using a reducing agent such as hydrazine, lithium aluminum hydride, or tetramethylborohydride; however, if the gas is changed A method using a reducing gas is preferred because the subsequent ammonia decomposition step can be carried out continuously. The reducing gas may be diluted with an inert gas such as nitrogen, carbon dioxide, or argon. When diluting, the proportion of the reducing gas in the introduced gas may be adjusted as appropriate, and may be, for example, 5% by volume or more and 50% by volume or less.

The conditions for the reduction treatment are preferably adjusted so that the cobalt oxide contained in the catalyst of the present invention can be sufficiently reduced. For example, when subjecting the catalyst of the present invention to a reduction treatment using a reducing gas, the temperature is preferably adjusted to 300°C or higher and 800°C or lower, more preferably 400°C or higher and 700°C or lower. The time for the reduction treatment is preferably 0.5 hours or more and 5 hours or less. However, even if the reduction in the reduction treatment is not sufficient, hydrogen is generated by the decomposition of ammonia and the catalyst layer is in a reduced state, so it is thought that the ammonia decomposition activity of the catalyst of the present invention will gradually improve. It will be done.

Subsequently, ammonia is decomposed into hydrogen and nitrogen by bringing a gas containing ammonia into contact with the reduced catalyst of the present invention. The ammonia-containing gas may be ammonia gas or a mixed gas of ammonia and an inert gas. When using a mixed gas, the proportion of ammonia gas contained in the mixed gas can be, for example, 50% by volume or more and 95% by volume or less.

The flow rate of the ammonia-containing gas introduced into the catalyst layer containing the catalyst of the present invention may be appropriately adjusted within a range that can efficiently decompose ammonia into hydrogen and nitrogen. ,000h ^-1 or more is preferable. The space velocity is more preferably 2,000 h ^-1 or more, and even more preferably 3,000 h ^-1 or more. The upper limit of the space velocity is not particularly limited, but from the viewpoint of suppressing the amount of unreacted ammonia, it is preferably 100,000 h ^-1 or less, more preferably 50,000 h ^-1 or less, even more preferably 20,000 h ^-1 or less. preferable.

The temperature of the ammonia decomposition reaction may also be appropriately adjusted within a range that allows efficient decomposition of ammonia into hydrogen and nitrogen, and can be, for example, 250°C or higher and 800°C or lower. The temperature is preferably 300°C or higher, more preferably 400°C or higher, and preferably 700°C or lower, more preferably 600°C or lower. The reaction pressure can be 0.1 MPa or more and 20 MPa or less, preferably 0.5 MPa or more and 10 MPa or less. The reaction pressure may be adjusted using a back pressure valve or the like.

If the gas that has passed through the catalyst layer contains unreacted ammonia, the post-reaction gas is introduced into a trap such as a sulfuric acid layer to remove and recover the ammonia, and further separates hydrogen, nitrogen, and inert gas. May be purified.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the Examples below, and modifications may be made as appropriate within the scope of the spirit of the preceding and following. Of course, other implementations are also possible, and all of them are included within the technical scope of the present invention.

Example 1: 88Co9Y3Ba
An ammonia decomposition catalyst (hereinafter referred to as such) whose active components are cobalt, yttrium and barium and has a metal oxide composition consisting of 88% by mass of Co ₃ O ₄ , 9% by mass of Y ₂ O ₃ and 3% by mass of BaO. A composition (referred to as "88Co9Y3Ba") was prepared by the kneading method shown below. Yttrium nitrate n-hydrate (anhydride content: 72.3% by mass, 3.0 g) and barium nitrate (0.52 g) were dissolved in ion-exchanged water (12 g) to prepare a mixed aqueous solution. Next, basic cobalt (II) carbonate (metallic cobalt content: 49% by mass, 13.2 g) was placed in a porcelain dish, and the above mixed aqueous solution was added and mixed to form a paste. The paste-like material was appropriately mixed with a spatula on a hot water bath set at 95°C, evaporated to dryness, and further dried overnight in a dryer at 110°C. The obtained dried product was placed in a firing furnace and fired at 200°C for 2 hours and then at 600°C for 2 hours to obtain an ammonia decomposition catalyst. In order to evaluate the performance of the obtained ammonia decomposition catalyst, it was pulverized and sieved to a size of 150 μm or less, filled into a cylindrical tube, and compacted with a press to form the catalyst. The ammonia decomposition catalyst of Example 1 was prepared by sieving the press-molded product to a size of 300 to 600 μm.

Example 2: 83Co12Y5Ba
As a catalyst, a composite oxide in which the mass % of each metal oxide was 83Co12Y5Ba was prepared by a kneading method. As metal component raw materials, yttrium nitrate n-hydrate (anhydride content: 72.3% by mass, 4.0g), barium nitrate (0.86g), and basic cobalt (II) carbonate (metallic cobalt content: 49% by mass) A catalyst was prepared in the same manner as in Example 1, except that %, 12.4 g) was used.

Comparative example 1: 88Co12Y
As a catalyst, a composite oxide in which the mass % of each metal oxide was 88Co12Y and did not contain Ba was prepared by a kneading method. Yttrium nitrate n-hydrate (anhydride content: 72.3% by mass, 4.0g) and basic cobalt (II) carbonate (metallic cobalt content: 49% by mass, 13.2g) were used as metal component raw materials. A catalyst was prepared in the same manner as in Example 1 except for the following.

Comparative example 2: 19Co77Y4Ba
A composite oxide, which is a catalyst supporting cobalt and barium using yttrium oxide as a carrier, and in which the mass % of each metal oxide is 19Co77Y4Ba, was prepared by a kneading method. Cobalt nitrate hexahydrate (6.4 g) and barium nitrate (0.63 g) were dissolved in ion exchange water (25 g). After adding yttrium oxide powder (7.0 g) to the above aqueous solution and mixing well, a dried product was obtained in the same manner as in Example 1. The dried product was calcined at 500° C. for 5 hours under air circulation to obtain a comparative catalyst. The obtained catalyst was used as an ammonia decomposition catalyst in the same manner as in Example 1.

Example 3: 87Co12Y1Ba
As a catalyst, a composite oxide in which the mass % of each metal oxide was 87Co12Y1Ba was prepared by a kneading method. As metal component raw materials, yttrium nitrate n-hydrate (anhydride content: 72.3% by mass, 4.0g), barium nitrate (0.17g), basic cobalt (II) carbonate (metallic cobalt content: 49% by mass) A catalyst was prepared in the same manner as in Example 1, except that 13.0 g of 13.0 g) was used.

Example 4: 87Co9Y1Ba3Zr
As a catalyst, a composite oxide in which the mass % of each metal oxide was 87Co9Y1Ba3Zr was prepared by a kneading method. As metal component raw materials, yttrium nitrate n-hydrate (anhydride content: 72.3% by mass, 3.0 g), barium nitrate (0.17 g), zirconyl nitrate aqueous solution ("Zircosol ZN" manufactured by Nissan Chemical Co., Ltd., zirconium oxide) A catalyst was prepared in the same manner as in Example 1, except that cobalt (metallic cobalt content: 25% by mass, 1.2g) and basic cobalt (II) carbonate (metallic cobalt content: 49% by mass, 13.0g) were used. .

Example 5: 85Co12Y3Sr
As a catalyst, a composite oxide in which the mass % of each metal oxide was 85Co12Y3Sr was prepared by a kneading method. As metal component raw materials, yttrium nitrate n-hydrate (anhydride content: 72.3% by mass, 4.0 g), strontium nitrate (0.63 g), and basic cobalt (II) carbonate (metallic cobalt content: 49 mass) A catalyst was prepared in the same manner as in Example 1, except that %, 12.8 g) was used.

Example 6: 82Co9Y3Ba6Zr
As a catalyst, a composite oxide in which the mass % of each metal oxide was 82Co9Y3Ba6Zr was prepared by a kneading method. As metal component raw materials, yttrium nitrate n-hydrate (anhydride content: 72.3% by mass, 3.0 g), barium nitrate (0.52 g), zirconyl nitrate aqueous solution ("Zircosol ZN" manufactured by Nissan Chemical Co., Ltd., zirconium oxide) A catalyst was prepared in the same manner as in Example 1, except that basic cobalt (II) carbonate (cobalt metal content: 49 mass %, 12.3 g) was used.

Comparative example 3: 73Co16Ce11Zr
According to Example 12 of JP-A No. 2010-94668, a composite oxide in which the mass % of each metal oxide was 73Co16Ce11Zr was prepared by a coprecipitation method.

Test example 1: Ammonia decomposition reaction test (1) Reactor and catalyst filling A tube with an outer diameter of 10 mm and an inner diameter of 8 mm was used as a tubular flow reactor, the reaction temperature was adjusted using a tube furnace, and the reaction pressure was controlled by a back pressure valve. Adjusted using.
Quartz sand was added to each of the above catalyst samples (0.6 mL) and mixed so that the total volume was 1.5 mL, and the mixture was filled into a reactor as a catalyst layer. The upper part of the catalyst layer was filled with quartz sand (3.0 g) as a gas preheating layer.

(2) Hydrogen reduction of the catalyst After filling the reactor with the catalyst, the temperature of the tube furnace was set at 600°C, and a mixed gas containing 10% by volume of hydrogen and 90% by volume of nitrogen was passed through for 1 hour to reduce the catalyst to hydrogen. It was subjected to reduction treatment.

(3) Ammonia decomposition reaction After stopping the supply of hydrogen and completing the reduction pretreatment, the inside of the reactor was replaced with nitrogen gas for a short time. The supply of nitrogen gas was stopped, and the supply of 100% ammonia gas was started at a gas flow rate of 170 mL/min. After starting the ammonia gas supply, the reaction pressure was increased to 0.9 MPa using a back pressure valve. The ammonia conversion rate was measured while changing the set temperature of the tube furnace. The space velocity (hr ^-1 ) obtained by dividing the gas supply amount per hour by the catalyst amount was 17,000 h ^-1 .
The reactor outlet gas contained hydrogen, nitrogen, and unconverted ammonia, and the unconverted ammonia was removed with a sulfuric acid trap. The conversion rate was calculated by measuring the amount of decomposed gas containing hydrogen and nitrogen after removing undecomposed ammonia, and using the following formula. The results are shown in Table 1.
Ammonia conversion rate (%) = [Amount of cracked gas (hydrogen + nitrogen) (L) / Amount of ammonia gas supplied (L) x 2] x 100

As shown in Table 1, the ammonia decomposition activity of the catalyst containing cobalt and yttrium but no alkaline earth metal (Comparative Example 1) was extremely low. In addition, a catalyst that contains cobalt, yttrium, and alkaline earth metals but has a low cobalt content (Comparative Example 2), and a catalyst that contains cobalt but does not contain yttrium and alkaline earth metals (Comparative Example 3), The ammonia decomposition activity was extremely low, especially at relatively low temperatures.
On the other hand, the ammonia decomposition catalyst according to the present invention containing cobalt, yttrium, and alkaline earth metals in appropriate proportions not only has high ammonia decomposition activity, but also has a low degree of decrease in ammonia decomposition activity even at relatively low reaction temperatures. It was relatively calm.

Claims (6)

Contains active ingredients,
the active ingredient comprises cobalt, yttrium, and one or more alkaline earth metals selected from strontium and barium;
The proportion of cobalt is 50% by mass or more in terms of oxide,
The proportion of yttrium is 1% by mass or more and 40% by mass or less in terms of oxide,
An ammonia decomposition catalyst characterized in that the proportion of the alkaline earth metal is 0.1% by mass or more and 10% by mass or less in terms of oxide. The ammonia decomposition catalyst according to claim 1, wherein the alkaline earth metal is barium. The ammonia decomposition catalyst according to claim 1 or 2, further containing zirconium in an amount of 0.1% by mass or more and 15% by mass or less in terms of oxide. A method for producing an ammonia decomposition catalyst, comprising:
impregnating a cobalt compound with a solution containing yttrium and one or more alkaline earth metals selected from strontium and barium;
drying the cobalt compound impregnated with the solution, and
a step of firing the dried cobalt compound ,
The ammonia decomposition catalyst contains an active component,
the active ingredient comprises cobalt, yttrium, and one or more alkaline earth metals selected from strontium and barium;
The proportion of cobalt is 50% by mass or more in terms of oxide,
The proportion of yttrium is 1% by mass or more and 40% by mass or less in terms of oxide,
A method for producing an ammonia decomposition catalyst, characterized in that the proportion of the alkaline earth metal is 0.1% by mass or more and 10% by mass or less in terms of oxide . The manufacturing method according to claim 4, wherein the cobalt compound is basic cobalt carbonate. A step of subjecting the ammonia decomposition catalyst according to any one of claims 1 to 3 to a reduction treatment, and
A method for producing hydrogen and nitrogen, comprising the step of decomposing ammonia into hydrogen and nitrogen by bringing a gas containing ammonia into contact with the reduced ammonia decomposition catalyst.