Ammonia decomposition catalyst and method for producing same

Abstract

The present invention relates to an ammonia decomposition catalyst and a method for producing same. Specifically, the present invention relates to an ammonia decomposition catalyst in the form of a carrier containing lanthanum and alumina, with ruthenium as an active metal and an alkali metal as a co-active metal supported on the carrier, and a method for producing same, wherein the alkali metal is Li, Na, K, Rb, Cs, or a mixture thereof.

Description

Ammonia decomposition catalyst and method for producing the same

[0001] The present invention relates to an ammonia decomposition catalyst and a method for producing the same.

[0002] Specifically, a carrier containing lanthanum and alumina, and ruthenium (Ru) and alumina on the carrier.

[0003] The present invention relates to an ammonia decomposition catalyst in the form of a potassium metal support, and a method for producing the same.

[0004] Recently, in order to solve the problem of global warming caused by the use of fossil fuels, hydrogen, which produces only water when burned and does not produce CO2, a global warming substance, or emit air pollutants, is attracting attention as a clean energy source.

[0005] However, this hydrogen is very light in its gaseous state, so there is a problem that it must be liquefied or compressed for transportation.

[0006]

[0007] As one solution to the problem of transporting hydrogen in a gaseous state, a method of transporting ammonia, in which hydrogen exists together with nitrogen, and producing hydrogen through catalytic decomposition of ammonia has been proposed.

[0008] Ammonia, which produces only nitrogen and hydrogen when decomposed, has the advantage of being an environmentally friendly hydrogen source, and can be mass-produced industrially. It is also easy to liquefy, making it advantageous for transportation and storage.

[0009] Meanwhile, the ammonia decomposition reaction is an endothermic reaction in which 2 moles of ammonia are produced into 3 moles of hydrogen, as described in the following reaction scheme 1.

[0010]

[0011] [Reaction Formula 1]

[0012]

[0013]

[0014] Ammonia decomposition, as described above, is known to be an endothermic reaction and typically occurs at high temperatures of 500-900°C. However, due to the problems of high temperatures and the low hydrogen conversion rate of ammonia, catalysts are used in the ammonia decomposition reaction to improve the hydrogen conversion rate.

[0015]

[0016] Meanwhile, catalysts for ammonia decomposition reactions use precious or non-precious metals as active metals, and it has been reported that ruthenium (Ru) is the best among precious metal catalysts and Ni catalyst is the best among non-precious metal catalysts.

[0017] The above catalysts using ruthenium (Ru) or nickel as active materials use various carriers in an attempt to increase catalytic activity in the ammonia decomposition reaction.

[0018] Known carriers include γ-Al2O3, activated carbon, lanthanum-CeO2 composite oxide, CeO2, ZrO2 corrected with Ba, graphene nanocomposite compound, SmCeOx, SiC, etc.

[0019]

[0020] However, even if many carriers are used to increase the activity of metals such as ruthenium and nickel, there are still problems in terms of activity, cost, or mass production.

[0021] Therefore, there is an urgent need to develop an ammonia decomposition catalyst that is economically feasible for ammonia decomposition processes with high activity even in large-scale decomposition processes.

[0022] The present invention provides an ammonia decomposition catalyst having excellent ammonia decomposition activity, which is highly active even in a large-scale decomposition process and thus economical for an ammonia decomposition process, and a method for producing the same.

[0023]

[0024] The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0025] For the above purpose, the present invention provides an ammonia decomposition catalyst and a method for producing the same.

[0026]

[0027] Specifically, the ammonia decomposition catalyst of the present invention is a catalyst in which ruthenium, an active metal, and an alkali metal, a co-active metal, are supported on a carrier.

[0028]

[0029] The carrier may be alumina, alumina supported with a lanthanide element, silica, zirconia, a lanthanum-cerium composite oxide, or zirconia supported with a lanthanide element.

[0030] The alkali metal, which is the above-mentioned co-active metal, is Li, Na, K, Rb, Cs, or a mixture thereof.

[0031] The molar ratio of ruthenium (Ru), which is an active metal, to alkali metal, which is a co-active metal, in the ammonia decomposition catalyst (Ru-alkali metal / carrier) of the present invention may be 1:2.5 to 1:10.

[0032] The amount of ruthenium in the ammonia decomposition catalyst (Ru-alkali metal / carrier) of the present invention may be 0.5 to 5 wt%.

[0033] In addition, the BET surface area (m2 / g) of the ammonia decomposition catalyst (Ru-alkali metal / carrier) of the present invention has a range of “50 to 120”.

[0034]

[0035] In addition, the method for producing the ammonia decomposition catalyst of the present invention,

[0036] a) A step of obtaining an ammonia decomposition catalyst by supporting ruthenium, an active metal, and an alkali metal, a co-active metal, on a carrier;

[0037] According to the present invention, there is an advantage in that it is possible to develop an ammonia decomposition catalyst having excellent ammonia decomposition activity that is highly active even in a large-scale decomposition process and has low manufacturing costs, thereby making the ammonia decomposition process economically feasible.

[0038] Figure 1 is a schematic diagram regarding the preparation of a carrier used in the preparation of an ammonia decomposition catalyst having excellent ammonia decomposition activity of the present invention.

[0039] Figure 2 is a graph showing the hydrogen conversion rate according to the ammonia decomposition catalyst manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 according to the present invention.

[0040] Figure 3 is a graph showing the hydrogen conversion rate according to the ammonia decomposition catalyst manufactured in Examples 4 to 8 and Comparative Example 4 according to the present invention.

[0041] Figure 4 is a graph showing the hydrogen conversion rate according to the ammonia decomposition catalyst manufactured in Example 9 and Comparative Examples 5 to 6 according to the present invention.

[0042] Hereinafter, the present invention will be described with reference to preferred embodiments and drawings to facilitate implementation by those skilled in the art. Furthermore, when describing the present invention, detailed descriptions of known functions or structures will be omitted if they are deemed to unnecessarily obscure the gist of the invention.

[0043]

[0044] The present invention is susceptible to various modifications and embodiments, and thus specific embodiments are exemplified and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Furthermore, throughout the specification, when a part is said to "include" a certain component, unless specifically stated otherwise, this does not exclude other components, but rather implies the inclusion of other components.

[0045]

[0046] The terminology used in the present invention is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In the present invention, it should be understood that the terms "comprises" or "has" are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0047]

[0048] The present invention relates to an ammonia decomposition catalyst and a method for producing the same.

[0049]

[0050] One embodiment of the present invention relates to an ammonia decomposition catalyst having excellent ammonia decomposition activity.

[0051]

[0052] Specifically, the ammonia decomposition catalyst of the present invention is a catalyst in which ruthenium, an active metal, and an alkali metal, a co-active metal, are supported on a carrier, and is expressed as 'Ru-alkali metal / carrier'.

[0053] The alkali metal, which is the co-active metal of the ammonia decomposition catalyst of the present invention, may be Li, Na, K, Rb, Cs, or a mixture thereof, and preferably K.

[0054] The molar ratio of ruthenium (Ru), which is an active metal, to alkali metal, which is a co-active metal, in the ammonia decomposition catalyst of the present invention may be 1:2.5 to 1:10, preferably more than 1:2.5 to 1:8, and more preferably more than 1:2.5 to 1:7.

[0055] The amount of ruthenium in the total ammonia decomposition catalyst (Ru-alkali metal / carrier) of the present invention may be 0.5 to 5 wt%, preferably 1 to 5 wt%, and more preferably 1 to 3 wt%.

[0056] The carrier may be alumina, alumina supported with a lanthanide element, silica, zirconia, a lanthanum-cerium composite oxide, or zirconia supported with a lanthanide element.

[0057] Preferably, it may be alumina, or alumina supported with a lanthanide element, more preferably, it may be alumina supported with a lanthanide element. Most preferably, it may be alumina doped with lanthanum among the lanthanide elements.

[0058] The above lanthanum-doped alumina includes lanthanum aluminate (LaAlO3) having a perovskite structure.

[0059]

[0060] When the above lanthanum-doped alumina is used as a carrier, the amount of lanthanum relative to the entire ammonia decomposition catalyst (Ru-alkali metal / carrier) of the present invention may be 5 mol% to 8 mol%, preferably 5 mol% to 15 mol%, and more preferably 10 mol% to 15 mol%.

[0061]

[0062] In addition, the BET surface area (m2 / g) of the ammonia decomposition catalyst (Ru-alkali metal / carrier) of the present invention may be in the range of “50 to 120”, and preferably in the range of “50 to 85”.

[0063]

[0064] Another embodiment of the present invention relates to a method for producing an ammonia decomposition catalyst of the present invention.

[0065]

[0066] The method for producing the ammonia decomposition catalyst of the present invention is as follows:

[0067] a) A step of obtaining an ammonia decomposition catalyst by supporting ruthenium and an alkali metal on a carrier;

[0068] Specifically, the step a) of obtaining an ammonia decomposition catalyst by supporting ruthenium and an alkali metal on a carrier is specifically 'supporting ruthenium and an alkali metal on a carrier simultaneously'.

[0069]

[0070] Looking more specifically at step a) above,

[0071] a-1) A step of simultaneously dissolving both a ruthenium precursor compound and an alkali metal-containing precursor compound in a mixed solvent of water and alcohol to prepare a ruthenium-alkali metal-containing precursor compound solution ('step a-1 of preparing a ruthenium-alkali metal-containing precursor compound solution');

[0072] a-2) a step of adding a carrier to the 'solution of a ruthenium precursor compound and an alkali metal-containing precursor compound' prepared in step a-1), mixing the carrier, and then removing the solvent contained in the solution using a reduced pressure distiller at a constant temperature to prepare a carrier supported with ruthenium-alkali metal ('step a-2 of preparing a carrier supported with ruthenium-alkali metal'); and

[0073] a-3) A step of drying and reducing the carrier on which the ruthenium-alkali metal is manufactured above to obtain an ammonia decomposition catalyst (Ru-alkali metal / carrier) having excellent ammonia decomposition activity and on which the ruthenium-alkali metal is supported on the carrier ('step a-3 of obtaining a ruthenium-alkali metal / carrier catalyst').

[0074]

[0075] Specifically, the ruthenium precursor compound of step a-1) may be ruthenium chloride, ruthenium nitride, ruthenium acetylacetonate, or ruthenium iodide, and preferably ruthenium chloride.

[0076] In addition, the alkali metal-containing precursor compound of step a-1) may be a nitrate of an alkali metal, a sulfate of an alkali metal, a hydroxide of an alkali metal, or a halide of an alkali metal, and preferably may be a nitrate, sulfate, hydroxide, or halide of potassium. More preferably, it may be potassium nitrate or potassium chloride.

[0077] The alcohol of the above step a-1) may be at least one selected from the group consisting of methanol, ethanol, propanol, butanol, glycerol, glycol, ethylene glycol, diethylene glycol, triethylene glycol, butanediol, tetraethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentadiol, and 1,2-hexadiol. Preferably, it may be at least one selected from the group consisting of ethanol, propanol, ethylene glycol, and diethylene glycol.

[0078] The volume ratio of water:alcohol in the above step a-1) is 1:0.5 to 1:2, preferably 1:0.5 to 1:1.5, and more preferably 1:1.

[0079] The amount of the mixed solution of water and alcohol used in the above step a-1) may be 10 to 150 times (weight ratio) based on 1 part by weight of the total of the ruthenium precursor compound and the alkali metal-containing precursor compound, and preferably 10 to 100 times (weight ratio).

[0080]

[0081] By mixing alcohol in water as described above, the ruthenium precursor compound and the alkali metal-containing precursor compound can be uniformly dispersed, so that ruthenium, which is an active metal for ammonia decomposition, and the alkali metal, which is a co-active metal, can be uniformly dispersed and doped on the carrier.

[0082]

[0083] The dissolution in step a-1) above can be performed at 50°C to 100°C, and preferably at 50°C to 80°C.

[0084] The ruthenium precursor compound and alkali metal-containing precursor compound of step a-1) above can be used in an amount of 1 to 40 parts by weight, and preferably 5 to 30 parts by weight, based on 100 parts by weight of the carrier.

[0085]

[0086] The amount of the ruthenium precursor compound and the alkali metal-containing precursor compound for the carrier as described above, and the molar ratio of ruthenium (Ru), which is the active metal, to the alkali metal, which is the co-active metal, in the ammonia decomposition catalyst (Ru-alkali metal / carrier) obtained through drying and reduction in step a-3) may be 1:2.5 to 1:10, preferably more than 1:2.5 to 1:8, and more preferably more than 1:2.5 to 1:7.

[0087] In addition, ruthenium may be included in an amount of 0.5 to 5 wt% relative to the total ammonia decomposition catalyst (Ru-alkali metal / carrier), preferably 1 to 5 wt%, and more preferably 1 to 3 wt%.

[0088]

[0089] The temperature of the reduced pressure distillation unit for solvent removal in the above step a-2) is 50 to 150°C, preferably 50 to 100°C, and the solvent is slowly removed over a solvent removal time of 1 to 5 hours.

[0090] The reduced pressure of the pressure reducing distillation unit in step a-2) above can be 1000 mbar to 40 mbar.

[0091]

[0092] The drying of the ruthenium and alkali metal doped carrier (pellet) of step a-3) above can be carried out using a conventional dryer at a temperature of 100 to 200°C for 5 to 24 hours, preferably at a temperature of 100 to 150°C for 5 to 15 hours.

[0093] The reduction in step a-3) above can be accomplished by filling a ruthenium-doped carrier (pellet) into a tubular furnace and treating it using hydrogen gas at 500 to 1,500°C for 1 to 5 hours, preferably at 500 to 1,000°C for 1 to 5 hours.

[0094] The above hydrogen gas is used diluted in an inert gas such as nitrogen at 1 to 20 vol%, preferably 1 to 10 vol%.

[0095]

[0096] Meanwhile, in the method for manufacturing an ammonia decomposition catalyst of the present invention, when the carrier is, for example, alumina doped with lanthanum, the manufacturing of the carrier is as follows:

[0097] i) a step of preparing a lanthanum precursor compound and a lanthanum aqueous solution of water ('Step 1-1 of preparing a lanthanum aqueous solution');

[0098] ii) a step of obtaining lanthanum-doped alumina by mixing the above lanthanum aqueous solution with alumina and then heating the mixture and removing water ('step 1-2 of obtaining lanthanum-doped alumina'); and

[0099] iii) a step of drying and calcining the obtained lanthanum-doped alumina to obtain a carrier of lanthanum aluminate ('step 1-3 of obtaining lanthanum aluminate carrier'); (see Fig. 1).

[0100]

[0101] The ratio (parts by weight) of the lanthanum precursor compound:water in the above step 1-1 may be 1:2 to 1:20, preferably 1:2 to 1:15, and more preferably 1:3 to 1:10.

[0102] The preparation of the lanthanum aqueous solution in the above step 1-1 can be performed at 50 to 100°C, and preferably at 50 to 80°C.

[0103] The amount of alumina used in the above step 1-2 may be 3 to 7 times (molar ratio) the amount of lanthanum (lanthanum, La) in the lanthanum precursor compound in the above step 1-1.

[0104] The above alumina can be used in powder or pellet form, and is preferably in pellet form.

[0105]

[0106] The heating reaction of the above 1-2 steps may be performed at 50 to 100°C for 1 to 10 hours, and preferably at 50 to 80°C for 1 to 5 hours.

[0107] In addition, the removal of water in the above steps 1-2 can be accomplished by ① reducing pressure in the heating reaction, or ② using a filter to produce a product of alumina impregnated with lanthanum after the heating reaction.

[0108] The pressure reduction for water removal in the above steps 1-2 may be 1000 mbar to 40 mbar.

[0109]

[0110] The drying of the above 1-3 steps is carried out at 100 to 200°C for 1 to 24 hours, and the firing may also include (a) primary firing at 200 to 500°C for 5 to 12 hours, and (b) secondary firing at 500 to 1200°C for 1 to 10 hours.

[0111] Preferably, the drying of steps 1-3 is performed at 100 to 150°C for 5 to 15 hours, and the firing may also include (a) a primary firing at 150 to 350°C for 5 to 10 hours, and (b) a secondary firing at 600 to 1000°C for 2 to 7 hours.

[0112]

[0113] In the method for manufacturing the ammonia decomposition catalyst of the present invention, when the alumina doped with lanthanum as described above is used as a carrier, the amount of lanthanum relative to the entire ammonia decomposition catalyst (Ru-alkali metal / LaAlO3) of the present invention may be 5 to 18 mol%, preferably 5 to 15 mol%, and more preferably 10 to 15 mol%.

[0114] Below, the present invention is described using specific examples and comparative examples.

[0115]

[0116] The ICP analysis of the examples and comparative examples below was performed using an inductively coupled plasma spectrometer, an iCAP 7400 instrument from Thermo Scientific. For the measurement, hydrochloric acid was added to each catalyst of the examples and comparative examples, and then dissolved using ultrasound, followed by measurement.

[0117]

[0118] The following Examples 1 to 3 and Comparative Examples 1 to 3 relate to the molar ratio of K / Ru included in the ammonia decomposition catalyst of the present invention.

[0119]

[0120] <Example 1> (K / Ru mole ratio 2.9, La 12.7 mol%)

[0121] A lanthanum aqueous solution was prepared by dissolving 38.53 g (89.0 mmol) of lanthanum nitrate in 250 ml of pure water in a vertical separation reactor and stirring at 60°C for 20 minutes. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the solution was placed in a reduced pressure distillation chamber. The solution was slowly distilled at 70°C for 2 hours under reduced pressure to recover the lanthanum-impregnated pellets. The recovered lanthanum-impregnated pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and placed in an electric furnace and calcined stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 48.8 g (94.0% yield) of the lanthanum-impregnated pellet carrier.

[0122]

[0123] In a vertical separation reactor, 3.32 g (7.2 mmol) of ruthenium chloride and 2.86 g (28.0 mmol) of potassium nitrate were dissolved in a solution containing 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 40.2 g of the carrier of the obtained lanthanum-impregnated pellets was added thereto, and after connecting to a reduced pressure distillation apparatus, the mixture was slowly distilled at 70°C for 3 hours under reduced pressure to produce pellets of the lanthanum-impregnated carrier impregnated with ruthenium and potassium. The lanthanum-impregnated carrier pellets impregnated with ruthenium and potassium manufactured above were dried in a general dryer at 110°C for 12 hours, then filled into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 41.4 g (97.3% yield) of the ammonia decomposition catalyst of the present invention having excellent ammonia decomposition activity.

[0124]

[0125] As a result of ICP analysis of the catalyst manufactured above, the La impregnation amount was 12.7 mol%, the Ru impregnation amount at this time was 1.43 wt%, and the K impregnation amount was 1.62 wt%.

[0126]

[0127] <Example 2> (K / Ru mole ratio 6.1, La 12.7 mol%)

[0128] A lanthanum aqueous solution was prepared by dissolving 38.53 g (89.0 mmol) of lanthanum nitrate in 250 ml of pure water in a vertical separation reactor and stirring at 60°C for 20 minutes. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the solution was placed in a reduced pressure distillation chamber. The solution was slowly distilled at 70°C for 2 hours under reduced pressure to recover lanthanum-impregnated carrier pellets. The recovered lanthanum-impregnated pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and placed in an electric furnace and calcined stepwise at 200°C for 8 hours and then at 900°C for 5 hours to obtain 48.8 g (94.0% yield) of lanthanum-impregnated pellet carriers.

[0129]

[0130] In a vertical separation reactor, 3.32 g (7.20 mmol) of ruthenium chloride and 4.53 g (44.4 mmol) of potassium nitrate were dissolved in a solution containing 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 40.1 g of the obtained lanthanum-impregnated carrier pellets were added thereto, and after connecting to a reduced pressure distillation unit, distillation was conducted at 70°C for 3 hours while gradually reducing the pressure to prepare lanthanum-impregnated carrier pellets impregnated with ruthenium and potassium. The prepared pellets were dried in a general dryer at 110°C for 12 hours, and then charged into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 42.1 g (97.0% yield) of the ammonia decomposition catalyst of the present invention having excellent ammonia decomposition activity.

[0131]

[0132] The ICP analysis result of the above-mentioned catalyst showed that the La impregnation amount was 12.7 mol%, the Ru impregnation amount was 1.4 wt%, and the K impregnation amount was 3.3 wt%.

[0133]

[0134] <Example 3> (K / Ru mole ratio 7.7, La 12.7 mol%)

[0135] A lanthanum aqueous solution was prepared by dissolving 38.53 g (89.0 mmol) of lanthanum nitrate in 250 ml of pure water in a vertical separation reactor and stirring at 60°C for 20 minutes. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the solution was placed in a reduced pressure distillation chamber. The solution was slowly distilled at 70°C for 2 hours under reduced pressure to recover the lanthanum-impregnated pellets. The recovered lanthanum-impregnated pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and placed in an electric furnace, where they were calcined stepwise at 200°C for 8 hours and 900°C for 5 hours to obtain 48.8 g (94.0% yield) of the lanthanum-impregnated pellet carrier.

[0136]

[0137] In a vertical separation reactor, 3.32 g (7.20 mmol) of ruthenium chloride and 5.81 g (56.9 mmol) of potassium nitrate were dissolved in a solution containing 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 40.2 g of the obtained lanthanum-impregnated carrier pellets were added thereto, and after connecting to a reduced pressure distillation unit, the mixture was distilled at 70°C for 3 hours under gradually reduced pressure to produce lanthanum-impregnated carrier pellets impregnated with ruthenium and potassium. The manufactured pellets were dried in a general dryer at 110°C for 12 hours, and then filled into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 42.5 g (96.0% yield) of the ammonia decomposition catalyst of the present invention having excellent ammonia decomposition activity.

[0138]

[0139] As a result of ICP analysis of the catalyst manufactured above, the La impregnation amount was 12.7 mol%, the Ru impregnation amount at this time was 1.35 wt%, and the K impregnation amount was 4.0 wt%.

[0140]

[0141] <Comparative Example 1> (K 0 mol%, La 12.7 mol%)

[0142] A lanthanum aqueous solution was prepared by dissolving 38.53 g (89.0 mmol) of lanthanum nitrate in 250 ml of pure water in a vertical separation reactor and stirring at 60°C for 20 minutes. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the mixture was placed in a reduced pressure distillation chamber and distilled at 70°C for 2 hours under gradually reduced pressure to recover the lanthanum-impregnated pellets. The recovered pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and placed in an electric furnace and calcined stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 48.8 g (94.0% yield) of a lanthanum-impregnated pellet carrier.

[0143]

[0144] In another upper and lower separation reactor, 2.96 g (6.4 mmol) of ruthenium chloride was dissolved in a solution containing 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 31.8 g of the obtained carrier pellets were added thereto, and the mixture was placed in a reduced pressure distillation chamber and distilled at 70°C for 3 hours while gradually reducing the pressure to prepare ruthenium-impregnated carrier pellets. The ruthenium-impregnated carrier pellets thus prepared were dried in a general dryer at 110°C for 12 hours, then charged into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 32.3 g (99.4% yield) of a catalyst for ammonia decomposition reaction.

[0145]

[0146] The ICP analysis results of the above-mentioned manufactured catalyst showed that the La impregnation amount was 12.7 mol%, and the Ru impregnation amount at this time was 1.42 wt%.

[0147]

[0148] <Comparative Example 2> (K / Ru mole ratio 1.3, La 12.7 mol%)

[0149] A lanthanum aqueous solution was prepared by dissolving 38.53 g (89.0 mmol) of lanthanum nitrate in 250 ml of pure water in a vertical separation reactor and stirring at 60°C for 20 minutes. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the solution was placed in a reduced pressure distillation chamber, slowly distilled at 70°C for 2 hours under reduced pressure to recover the lanthanum-impregnated pellets. The recovered lanthanum-impregnated pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and placed in an electric furnace, and calcined stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 48.8 g (94.0% yield) of the lanthanum-impregnated pellet carrier.

[0150]

[0151] In another upper and lower separation reactor, 3.32 g (7.2 mmol) of ruthenium chloride and 0.85 g (8.3 mmol) of potassium nitrate were dissolved in a solution of 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 40.1 g of the obtained carrier pellets were added thereto, and the mixture was placed in a reduced pressure distillation chamber and distilled at 70°C for 3 hours while gradually reducing the pressure to prepare carrier pellets impregnated with ruthenium and potassium. The prepared carrier pellets impregnated with ruthenium and potassium were dried in a general dryer at 110°C for 12 hours, and then filled into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain a catalyst for ammonia decomposition reaction (41.0 g (99.2% yield)).

[0152]

[0153] As a result of ICP analysis of the catalyst manufactured above, the La impregnation amount was 12.7 mol%, the Ru impregnation amount at this time was 1.46 wt%, and the K impregnation amount was 0.76 wt%.

[0154]

[0155] <Comparative Example 3> (K / Ru mole ratio 2.2, La 12.7 mol%)

[0156] A lanthanum aqueous solution was prepared by dissolving 38.53 g (89.0 mmol) of lanthanum nitrate in 250 ml of pure water in a vertical separation reactor and stirring at 60°C for 20 minutes. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the mixture was placed in a reduced pressure distillation chamber and distilled at 70°C for 2 hours under gradually reduced pressure to recover the lanthanum-impregnated pellets. The recovered pellets were dried in a general dryer at 110°C for 12 hours, transferred to a crucible, and placed in an electric furnace and calcined stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 48.8 g (94.0% yield) of a lanthanum-impregnated pellet carrier.

[0157] 2.96 g (6.4 mmol) of ruthenium chloride and 1.53 g (15.0 mmol) of potassium nitrate were dissolved in a solution of 125 ml of pure water and 125 ml of ethanol in a vertical separation reactor at 60°C for 10 minutes, and then 31.8 g of the obtained carrier pellets were added thereto, and the mixture was slowly distilled at 70°C for 3 hours under reduced pressure, thereby producing carrier pellets impregnated with ruthenium and potassium. The carrier pellets impregnated with ruthenium and potassium thus produced were dried in a general dryer at 110°C for 12 hours, and then filled into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 32.6 g (98.0% yield) of a catalyst for ammonia decomposition reaction.

[0158]

[0159] The ICP analysis result of the above-mentioned catalyst showed that the La impregnation amount was 12.7 mol%, the Ru impregnation amount was 1.38 wt%, and the K impregnation amount was 1.18 wt%.

[0160]

[0161] The K / Ru molar ratio and weight % of K and Ru impregnated in each of the ammonia decomposition catalysts of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1 below.

[0162]

[0163]

[0164]

[0165] <Measurement of ammonia conversion rate>

[0166] Each ammonia decomposition reaction was performed using the catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 3, and the ammonia conversion rate was measured.

[0167]

[0168] The above measurement was performed under the conditions of an ammonia space velocity GHSV of 3,000 ml / (gcat˙h) at atmospheric pressure and reaction temperatures of 400°C, 425°C, 450°C, 500°C, 550°C, and 600°C, and the ammonia conversion rate based on this was shown in Table 2 below (see Fig. 2).

[0169]

[0170]

[0171]

[0172] As shown in Table 2 above, Examples 1 to 3, which correspond to the ammonia decomposition catalyst of the present invention having excellent ammonia decomposition activity, show a conversion rate of 85% or more even at a low reaction temperature of 400°C, and in particular, Examples 1 and 2 show a conversion rate of 93.4% or more, and even at a reaction temperature of 425°C, both Examples 1 and 2 show a conversion rate of 96.4%, which is close to 100%, and Example 3 also shows a conversion rate of 89.7%.

[0173] Furthermore, Example 1 shows a conversion rate of 100% even at a low reaction temperature of 425°C.

[0174]

[0175] In contrast, Comparative Examples 1 to 3 exhibit conversion rates of about 75% or less at a low temperature of 400°C, and even at a reaction temperature of 425°C, Comparative Examples 1 to 3 exhibit conversion rates of 63.6%, 77.2%, and 83.1%, respectively, which are lower than 85%. Furthermore, Comparative Examples 1 to 3 exhibit conversion rates of less than 100% even at 600°C.

[0176]

[0177] As described above, the ammonia decomposition catalysts of Examples 1 to 3 of the present invention, which are excellent ammonia decomposition catalysts, exhibit a conversion rate of 85% or more, and even at a low reaction temperature of 400°C, Example 1 exhibits a conversion rate of 98.9%, which is close to 100%, and Example 1 exhibits a conversion rate of 100.0% even at a low temperature of 450°C, so that they can be applied to mass production of hydrogen by ammonia decomposition reaction even at relatively low temperatures, and thus have an excellent economic effect in the process of producing hydrogen from ammonia.

[0178]

[0179] The following relates to the molar % of La contained in the carrier of the ammonia decomposition catalyst of the present invention.

[0180]

[0181] <Example 4> (La 5.9 mol%, K / Ru mole ratio 5.6)

[0182] 18.80 g (43.4 mmol) of lanthanum nitrate was added to 250 ml of pure water in a vertical separation reactor and dissolved at 60°C for 20 minutes to prepare a lanthanum aqueous solution. 31.8 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the mixture was placed in a reduced pressure distillation chamber and distilled at 70°C for 2 hours while gradually reducing the pressure to recover the lanthanum-impregnated pellets. The recovered pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and placed in an electric furnace and calcined stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 34.6 g (91.5% yield) of the lanthanum-impregnated pellet carrier.

[0183]

[0184] In a vertical separation reactor, 2.96 g of ruthenium chloride (6.4 mmol) and 3.46 g of potassium nitrate (33.9 mmol) were dissolved in a solution containing 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 31.8 g of the carrier pellets obtained above were added, and the mixture was placed in a reduced pressure distillation chamber and distilled at 70°C for 3 hours while gradually reducing the pressure to prepare carrier pellets impregnated with ruthenium and potassium. The pellets thus prepared were dried in a general dryer at 110°C for 12 hours, and then filled into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 33.3 g (96.8% yield) of the ammonia decomposition catalyst of the present invention having excellent ammonia decomposition activity.

[0185]

[0186] As a result of ICP analysis of the catalyst manufactured above, the La impregnation amount was 5.9 mol%, the Ru impregnation amount at this time was 1.47 wt%, and the K impregnation amount was 3.2 wt%.

[0187]

[0188] <Example 5> (La 9.0 mol%, K / Ru mole ratio 4.9)

[0189] A lanthanum aqueous solution was prepared by adding 30.66 g (69.4 mmol) of lanthanum nitrate to 250 ml of pure water in a vertical separation reactor and dissolving it at 60°C for 20 minutes. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the mixture was placed in a reduced pressure distillation chamber, slowly distilled at 70°C for 2 hours under reduced pressure to recover the lanthanum-impregnated pellets. The recovered pellets were dried in a general dryer at 110°C for 12 hours, transferred to a crucible, and calcined stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 46.4 g (93.2% yield) of the lanthanum-impregnated pellet carrier.

[0190]

[0191] In a vertical separation reactor, 2.96 g (6.4 mmol) of ruthenium chloride and 3.46 g (33.9 mmol) of potassium nitrate were dissolved in a solution containing 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 31.8 g of the obtained carrier pellets were added thereto, and after connecting to a reduced pressure distillation unit, distillation was conducted at 70°C for 3 hours while gradually reducing the pressure to prepare carrier pellets impregnated with ruthenium and potassium. The prepared carrier pellets were dried in a general dryer at 110°C for 12 hours, and then filled into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 33.24 g (96.5% yield) of the ammonia decomposition catalyst of the present invention having excellent ammonia decomposition activity.

[0192]

[0193] The ICP analysis results of the above-mentioned catalyst showed that the La impregnation amount was 9.0 mol%, the Ru impregnation amount at this time was 1.52 wt%, and the K impregnation amount was 2.9 wt%.

[0194]

[0195] <Example 6> (La 11.8 mol%, K / Ru mole ratio 5.5)

[0196] A lanthanum aqueous solution was prepared by adding 35.56 g (82.1 mmol) of lanthanum nitrate to 250 ml of pure water in a vertical separation reactor and dissolving it at 60°C for 20 minutes. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the mixture was placed in a reduced pressure distillation chamber and distilled at 70°C for 2 hours while gradually reducing the pressure to recover the lanthanum-impregnated pellets. The recovered pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and calcined in an electric furnace stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 48.2 g (94.1% yield) of the lanthanum-impregnated pellet carrier.

[0197]

[0198] In a vertical separation reactor, 2.96 g (6.4 mmol) of ruthenium chloride and 3.46 g (33.9 mmol) of potassium nitrate were dissolved in a solution containing 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 31.8 g of the carrier pellets obtained above were added, and after connecting to a reduced pressure distillation unit, distillation was conducted at 70°C for 3 hours while gradually reducing the pressure to prepare carrier pellets impregnated with ruthenium and potassium. The carrier pellets thus prepared were dried in a general dryer at 110°C for 12 hours, and then charged into a tubular furnace and reduced at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 33.4 g (97.0% yield) of the ammonia decomposition catalyst of the present invention having excellent ammonia decomposition activity.

[0199]

[0200] The ICP analysis results of the above-mentioned manufactured catalyst show that the La impregnation amount is 11.8 mol%, the Ru impregnation amount is 1.55 wt%, and the K impregnation amount is 3.3 wt%.

[0201]

[0202] <Example 7> (La 12.7 mol%, K / Ru mole ratio 5.6)

[0203] A lanthanum aqueous solution was prepared by dissolving 38.53 g (89.0 mmol) of lanthanum nitrate in 250 ml of pure water at 60°C for 20 minutes in a vertical separation reactor. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the mixture was placed in a reduced pressure distillation chamber, slowly distilled at 70°C for 2 hours under reduced pressure, to recover the lanthanum-impregnated pellets. The recovered lanthanum-impregnated pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and placed in an electric furnace, where they were calcined stepwise at 200°C for 8 hours and at 900°C for 5 hours, to obtain 48.8 g (94.0% yield) of a lanthanum-impregnated pellet carrier.

[0204]

[0205] In a vertical separation reactor, 2.96 g (6.4 mmol) of ruthenium chloride and 3.46 g (33.9 mmol) of potassium nitrate were dissolved in a solution containing 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 31.8 g of the carrier pellets obtained above were added, and after connecting to a reduced pressure distillation unit, distillation was conducted at 70°C for 3 hours while gradually reducing the pressure to prepare carrier pellets impregnated with ruthenium and potassium. The prepared carrier pellets were dried in a general dryer at 110°C for 12 hours, and then filled into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 33.3 g (97.0% yield) of the ammonia decomposition catalyst of the present invention having excellent ammonia decomposition activity.

[0206]

[0207] As a result of ICP analysis of the catalyst manufactured above, the La impregnation amount was 12.7 mol%, the Ru impregnation amount was 1.47 wt%, and the K impregnation amount was 3.2 wt%.

[0208]

[0209] <Example 8> (La 14.8 mol%, K / Ru mole ratio 5.3)

[0210] A lanthanum aqueous solution was prepared by adding 42.51 g (98.2 mmol) of lanthanum nitrate to 250 ml of pure water in a vertical separation reactor and dissolving it at 60°C for 20 minutes. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the solution was placed in a reduced pressure distillation chamber, slowly distilled at 70°C for 2 hours under reduced pressure to recover the lanthanum-impregnated pellets. The recovered lanthanum-impregnated pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and placed in an electric furnace, where they were calcined stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 50.4 g (94.4% yield) of a lanthanum-impregnated pellet carrier.

[0211]

[0212] In a vertical separation reactor, 2.96 g (6.4 mmol) of ruthenium chloride and 3.46 g (33.9 mmol) of potassium nitrate were dissolved in a solution containing 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 31.8 g of the obtained carrier pellets were added thereto, and after connecting to a reduced pressure distillation unit, distillation was conducted at 70°C for 3 hours while gradually reducing the pressure to prepare carrier pellets impregnated with ruthenium and potassium. The prepared carrier pellets were dried in a general dryer at a temperature of 110°C for 12 hours, and then charged into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 33.3 g (97.0% yield) of the ammonia decomposition catalyst of the present invention having excellent ammonia decomposition activity.

[0213]

[0214] As a result of ICP analysis of the catalyst manufactured above, the La impregnation amount was 14.8 mol%, the Ru impregnation amount at this time was 1.52 wt%, and the K impregnation amount was 3.1 wt%.

[0215]

[0216] <Comparative Example 4> (La 18.2 mol%, K / Ru mole ratio 5.7)

[0217] 57.65 g (133.1 mmol) of lanthanum nitrate was added to 250 ml of pure water in a vertical separation reactor and dissolved at 60°C for 20 minutes to prepare a lanthanum aqueous solution. 40 g of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm were added to the prepared aqueous solution, and the mixture was placed in a reduced pressure distillation chamber and distilled at 70°C for 2 hours while gradually reducing the pressure to recover the lanthanum-impregnated pellets. The recovered lanthanum-impregnated pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and placed in an electric furnace and calcined stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 53.5 g (92.1% yield) of the lanthanum-impregnated pellet carrier.

[0218]

[0219] 2.96 g (6.4 mmol) of ruthenium chloride and 3.46 g (33.9 mmol) of potassium nitrate were dissolved in a solution of 125 ml of pure water and 125 ml of ethanol in a vertical separation reactor at 60°C for 10 minutes, and then 31.8 g of the obtained carrier pellets were added thereto, and after connecting to a reduced pressure distillation unit, distillation was conducted at 70°C for 3 hours while gradually reducing the pressure to prepare carrier pellets impregnated with ruthenium and potassium. The manufactured carrier pellets were dried in a general dryer at 110°C for 12 hours, and then charged into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 33.4 g (97% yield) of a catalyst for ammonia decomposition reaction.

[0220]

[0221] As a result of ICP analysis of the catalyst manufactured above, the La impregnation amount was 18.2 mol%, the Ru impregnation amount at this time was 1.5 wt%, and the K impregnation amount was 3.3 wt%.

[0222]

[0223] The molar % of La and the molar ratio of K / Ru in the carrier impregnated in each of the ammonia decomposition catalysts of Examples 4 to 8 and Comparative Example 4 are shown in Table 3 below.

[0224]

[0225]

[0226]

[0227] <Measurement of ammonia conversion rate>

[0228] Each ammonia decomposition reaction was performed using the catalysts prepared in Examples 4 to 8 and Comparative Example 4, and the ammonia conversion rate was measured.

[0229]

[0230] The above measurement was performed under the conditions of an ammonia space velocity GHSV of 5,000 ml / (gcat˙h) at atmospheric pressure and reaction temperatures of 460°C, 500°C, 550°C, and 600°C, and the ammonia conversion rate based on this was shown in Table 4 below (see Fig. 3).

[0231]

[0232]

[0233] As seen in Table 4 above, the ammonia decomposition catalysts of Examples 4 to 8 of the present invention have a conversion efficiency of about 92% or more at a low temperature of 460°C, whereas Comparative Example 4 has a conversion efficiency of 85%, which is lower. Therefore, the ammonia reaction catalysts of Examples 4 to 8 of the present invention can be applied to mass production of hydrogen through the decomposition reaction of ammonia even at low temperatures, and thus have an excellent economic effect in the process of producing hydrogen from ammonia.

[0234]

[0235] Below, an experiment according to the impregnation order of the K precursor and the Ru precursor in the method for manufacturing the ammonia decomposition catalyst of the present invention will be described.

[0236]

[0237] <Example 9> Simultaneous impregnation of K and Ru (La 15.0 mol%, K / Ru mole ratio 4.8)

[0238] A lanthanum aqueous solution was prepared by adding 38.53 g (89.0 mmol) of lanthanum nitrate to 250 ml of pure water in a vertical separation reactor and dissolving it at 60°C for 20 minutes. 40 g (392.3 mmol) of cylindrical alumina pellets with an inner diameter of 3 mm, an outer diameter of 9 mm, and a height of 12 mm to the prepared aqueous solution, connecting it to a reduced pressure distillation apparatus, and distilling it at 70°C for 2 hours while gradually reducing the pressure to recover the lanthanum-impregnated pellets. The recovered lanthanum-impregnated pellets were dried in a general dryer at 110°C for 12 hours, then transferred to a crucible and placed in an electric furnace and calcined stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 51.5 g (98.4% yield) of a lanthanum-impregnated pellet carrier.

[0239]

[0240] In a vertical separation reactor, 2.96 g (6.4 mmol) of ruthenium chloride and 3.46 g (33.9 mmol) of potassium nitrate were dissolved in a solution containing 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 31.8 g of the obtained carrier pellets were added thereto, and after connecting to a reduced pressure distillation unit, distillation was conducted at 70°C for 3 hours while gradually reducing the pressure to prepare carrier pellets impregnated with ruthenium and potassium. The prepared carrier pellets were dried in a general dryer at 110°C for 12 hours, and then charged into a tubular furnace and subjected to reduction treatment at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 33.3 g (97.0% yield) of the ammonia decomposition catalyst of the present invention having excellent ammonia decomposition activity.

[0241]

[0242] As a result of ICP analysis of the catalyst manufactured above, the impregnation amount of La was 15.0 mol%, the impregnation amount of Ru at this time was 1.3 wt%, and the impregnation amount of K was 2.4 wt%.

[0243]

[0244] <Comparative Example 5> Impregnation of Ru after impregnation of K

[0245] In the above Comparative Example 5, first, potassium was impregnated into the obtained lanthanum-impregnated carrier pellet using potassium nitrate, and then, ruthenium chloride was used on the potassium-impregnated lanthanum-impregnated carrier pellet to manufacture a lanthanum-impregnated carrier pellet impregnated with ruthenium and potassium, and the same procedure as Example 9 was performed to obtain 33.0 g (96.0% yield) of an ammonia decomposition catalyst in which ruthenium and potassium were impregnated into a lanthanum-impregnated carrier.

[0246]

[0247] <Comparative Example 6> Impregnation of K after impregnation of Ru

[0248] In the above Comparative Example 5, the lanthanum-impregnated carrier pellet obtained above was first impregnated with ruthenium using ruthenium chloride, and then potassium was impregnated using potassium nitrate, and the same procedure as in Comparative Example 5 was performed, thereby obtaining 33.03 g (96.0% yield) of an ammonia decomposition catalyst in which ruthenium and potassium were impregnated in a lanthanum-impregnated carrier.

[0249]

[0250] <Measurement of ammonia conversion rate>

[0251] Each ammonia decomposition reaction was performed using the catalysts prepared in Example 9 and Comparative Examples 5 to 6, and the ammonia conversion rate was measured.

[0252]

[0253] The above measurement was performed under the conditions of an ammonia space velocity GHSV of 5,000 ml / (gcat˙h) at atmospheric pressure and reaction temperatures of 460°C, 500°C, 550°C, and 600°C, and the ammonia conversion rate based on this was shown in Table 5 below (see Fig. 4).

[0254]

[0255]

[0256] As seen in Table 5 above, in the case of Example 9, which is the simultaneous impregnation of the Ru precursor and K precursor of the present invention in the method for manufacturing an ammonia decomposition catalyst, a high conversion rate of 98.0% is shown even at a low temperature of 460°C, whereas in the case of Comparative Examples 5 and 6, which deviate from the method for manufacturing an ammonia decomposition catalyst of the present invention, a conversion rate of less than 100% is shown even at 600°C.

[0257]

[0258] Therefore, the method for producing an ammonia reaction catalyst of the present invention in Example 9 is an ammonia decomposition catalyst production method that can be applied to mass production of hydrogen by ammonia decomposition reaction even at low temperatures, and has an advantage in economic efficiency.

[0259]

[0260] <BET surface area (m2 / g) and total pore volume (cm3 / g) characteristics based on surface area analysis of ammonia decomposition catalyst>

[0261] Table 6 below shows the BET surface area (m2 / g) and total pore volume (cm3 / g) according to surface area analysis of the ammonia decomposition catalysts manufactured in Examples 4 to 8 and Comparative Example 4.

[0262]

[0263] The above BET surface area and total pore volume are the results of analyzing the specific surface area, etc. through physical adsorption of nitrogen gas using the Tristar II 3020 model from Micromeritics.

[0264]

[0265] For the above analysis, pretreatment of the catalysts manufactured by Examples 4 to 8 and Comparative Example 4 was performed under vacuum at 150°C for 4 hours using VacPrep 061, vacuum type.

[0266]

[0267] The specific surface area of ​​the catalyst was measured using the Brunauer, Emmett, and Teller (BET) equation at a temperature of -196°C of liquid nitrogen (purity 99.999%), and the isothermal adsorption / desorption of nitrogen gas was measured within the range of P / P0 = 0.005-0.995.

[0268] The total pore volume was calculated from the adsorption amount of nitrogen at P / P0 = 0.99.

[0269]

[0270] As shown in Table 6 above, the BET surface areas (m2 / g) of Examples 4 to 8, which are ammonia decomposition catalysts of the present invention having excellent ammonia decomposition activity, are “111.9, 85.8, 77.9, 70.3, and 54.8”, respectively, which satisfy the BET surface areas (m2 / g) of “50 to 120” of ammonia decomposition catalysts of the present invention having excellent ammonia decomposition activity.

[0271]

[0272] In contrast, the BET surface area (m2 / g) of the ammonia decomposition catalyst according to Comparative Example 4, which is outside the range of inclusion of lanthanum (La) in the carrier of the present invention, is “47.5”, which is outside the range of “50 to 120”, which is the BET surface area (m2 / g) of the ammonia decomposition catalyst of the present invention, which has excellent ammonia decomposition activity.

[0273] As seen above, the ammonia decomposition catalysts of the present invention of Examples 1 to 8 and the method for producing the ammonia decomposition catalyst of Example 9 can be utilized even at relatively low temperatures of 400°C to 460°C, so they have an advantage in economic efficiency.

[0274]

[0275] While the technical concepts and specific embodiments of the present invention have been described above, it will be understood that these embodiments merely illustrate the technical concepts and principles of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods embodying the technical concepts of the present invention without departing from the scope and spirit of the invention.

Claims

1. A catalyst in which ruthenium, an active metal, and an alkali metal, a co-active metal, are supported on a carrier. The above carrier is alumina, alumina supported with a lanthanide element, silica, zirconia, a lanthanum-cerium composite oxide, or zirconia supported with a lanthanide element. An ammonia decomposition catalyst (Ru-alkali metal / carrier), characterized in that the molar ratio of the active metal ruthenium (Ru):co-active metal alkali metal is 1:2.5 to 1:

10.

2. In paragraph 1, An ammonia decomposition catalyst (Ru-alkali metal / carrier), characterized in that the amount of ruthenium in the ammonia decomposition catalyst (Ru-alkali metal / carrier) is 0.5 to 5 wt%.

3. In paragraph 1, An ammonia decomposition catalyst (Ru-alkali metal / carrier), characterized in that the alkali metal as the co-active metal is Li, Na, K, Rb, Cs, or a mixture thereof.

4. In paragraph 1, An ammonia decomposition catalyst (Ru-alkali metal / carrier), characterized in that the carrier is alumina doped with lanthanum.

5. In paragraph 4, An ammonia decomposition catalyst (Ru-alkali metal / carrier), characterized in that the amount of lanthanum doped in the carrier is 5 mol% to 18 mol% with respect to the entire ammonia decomposition catalyst (Ru-alkali metal / carrier).

6. In paragraph 1, The above ammonia decomposition catalyst (Ru-alkali metal / carrier) is characterized in that the BET surface area (m2 / g) is in the range of “50 to 120”. 7.a) A method for producing an ammonia decomposition catalyst (Ru-alkali metal / carrier), comprising the step of obtaining an ammonia decomposition catalyst (Ru-alkali metal / carrier) by supporting ruthenium and an alkali metal on a carrier, A method for producing an ammonia decomposition catalyst (Ru-alkali metal / carrier), characterized in that the above ruthenium and alkali metal are simultaneously supported on a carrier.

8. In paragraph 7, Step a) above is as follows: a-1) A step of preparing a ruthenium-alkali metal-containing precursor compound solution by dissolving both a ruthenium precursor compound and an alkali metal-containing precursor compound in a mixed solvent of water and alcohol ('step a-1 of preparing a ruthenium-alkali metal-containing precursor compound solution'); a-2) A step of adding a carrier to the 'solution of a ruthenium precursor compound and an alkali metal-containing precursor compound' prepared in step a-1), mixing the carrier, and then removing the solvent contained in the solution using a reduced pressure distiller at a constant temperature to prepare a carrier loaded with ruthenium-alkali metal ('step a-2 of preparing a carrier loaded with ruthenium-alkali metal'); and a-3) A method for producing an ammonia decomposition catalyst (Ru-alkali metal / carrier), characterized by comprising a step of drying and reducing the carrier on which the ruthenium-alkali metal is manufactured above to obtain an ammonia decomposition catalyst (Ru-alkali metal / carrier) having excellent ammonia decomposition activity, wherein the ruthenium-alkali metal is supported on the carrier (step a-3 of obtaining a ruthenium-alkali metal / carrier catalyst).

9. In paragraph 8, A method for producing an ammonia decomposition catalyst (Ru-alkali metal / carrier), characterized in that the molar ratio of ruthenium (Ru), which is an active metal, to alkali metal, which is a co-active metal, in the ammonia decomposition catalyst (Ru-alkali metal / carrier) obtained through steps a-1) to a-3) above is 1:2.5 to 1:10.

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