Ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity and method for producing same

Abstract

The present invention provides a ruthenium catalyst for ammonia decomposition reactions that exhibits a conversion rate of nearly 100% at a reaction temperature of 550°C, a conversion rate of 93.6% or more even at 500°C, and a conversion rate of approximately 60% or more even at a low reaction temperature of 450°C, and that has high activity even in large-scale decomposition processes at relatively low temperatures, low production costs, and is economical for the ammonia decomposition process; and a method for producing the same.

Description

[Technical Field]

[0001] The present invention relates to a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity and a method for producing the same. [Background technology]

[0002] Recently, the issue of rising global temperatures due to global warming caused by the use of fossil fuels has come to the fore again. Hydrogen is attracting attention as an alternative energy source to fossil fuels because it produces only water when burned, does not produce CO2, a greenhouse gas, and does not emit air pollutants.

[0003] However, such hydrogen cannot exist alone in nature, but exists together with other elements, typically as ammonia together with nitrogen.

[0004] Furthermore, ammonia has the advantage of being an environmentally friendly hydrogen source, as only nitrogen and hydrogen are produced during decomposition. It can be mass-produced industrially, is easy to liquefy, and has advantages in terms of transportation and storage.

[0005] The ammonia decomposition reaction is an endothermic reaction in which 2 moles of ammonia are produced with 3 moles of hydrogen, as shown in Reaction Scheme 1 below.

[0006] [Reaction Scheme 1] 2NH3<->3H2+N2(reaction enthalpy=46KJ / mol)

[0007] The ammonia decomposition as described above is generally known to be carried out at high temperatures of 500 to 900°C. However, since the conversion rate of ammonia to hydrogen is low, a catalyst is used in the ammonia decomposition reaction to improve the conversion rate of hydrogen.

[0008] Catalysts for ammonia decomposition reactions use either precious or non-precious metals as the active metal, and it has been reported that ruthenium (Ru) is the most effective among precious metal catalysts, while Ni is the most effective among non-precious metal catalysts.

[0009] The above catalysts using ruthenium (Ru) or nickel as an active material use various supports in an attempt to enhance the catalytic activity in the ammonia decomposition reaction.

[0010] Known supports include γ-Al2O3, activated carbon, lanthania-CeO2 composite oxide, CeO2, Ba-modified ZrO2, graphene nanocomposite compounds, SmCeOx, and SiC.

[0011] However, even if many supports as described above are used to enhance the activity of metals such as ruthenium and nickel, problems still remain in terms of activity, cost, and mass production.

[0012] Therefore, there is an urgent need to develop a catalyst for the ammonia decomposition reaction that is highly active even in large-scale decomposition processes, has low production costs, and is economical for the ammonia decomposition process. Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention aims to provide a ruthenium catalyst for ammonia decomposition reaction that has excellent ammonia decomposition activity, is highly active even in large-scale decomposition processes, has low production costs, and is economical in the ammonia decomposition process, and a method for producing the same.

[0014] The problems to be solved by the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0015] In order to achieve the above object, the present invention provides a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity, and a method for producing the same.

[0016] Specifically, the ruthenium catalyst for ammonia decomposition reaction of the present invention, which has excellent ammonia decomposition activity, is a catalyst that contains lanthanum-doped alumina as a support and uses ruthenium as an active metal.

[0017] The lanthanum-doped alumina support includes lanthanum aluminate (LaAlO3) with a perovskite structure.

[0018] Lanthanum may be contained in an amount of 12 mol % to 19 mol % relative to lanthanum aluminate (LaAlO3) which is lanthanum-doped alumina as the support.

[0019] The ruthenium catalyst (Ru-LaAlO3) for ammonia decomposition reaction having excellent ammonia decomposition activity of the present invention uses ruthenium (Ru) as an active metal in the support of the lanthanum aluminate (LaAlO3), and the ruthenium (Ru) is contained in the lanthanum-doped alumina as the support.

[0020] The amount of ruthenium in the ruthenium catalyst (Ru / LaAlO3) for ammonia decomposition reaction having excellent ammonia decomposition activity may be 0.5 wt % to 5 wt %.

[0021] Furthermore, the BET surface area (m 2 / g) has a range of 50 to 93.

[0022] The method for producing a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity according to the present invention comprises the steps of: (a) doping alumina with lanthanum to produce a lanthanum-doped alumina support containing lanthanum aluminate (LaAlO) with a perovskite structure ("first step of producing a lanthanum aluminate support"); (b) providing ruthenium on the lanthanum aluminate support to obtain a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity, in which ruthenium is supported on lanthanum aluminate ("second step of producing a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity").

[0023] Specifically, the first step of producing the lanthanum aluminate support is: (i) preparing an aqueous solution of lanthanum containing a lanthanum precursor compound and water ("Step 1-1 of preparing an aqueous solution of lanthanum"); (ii) mixing the lanthanum aqueous solution with alumina, and then obtaining lanthanum-doped alumina by heating and removing water ("first and second steps of obtaining lanthanum-doped alumina"); (iii) drying and calcining the obtained lanthanum-doped alumina to obtain a lanthanum aluminate support ("Steps 1-3 of obtaining a lanthanum aluminate support").

[0024] The ratio (parts by weight) of the amount of lanthanum precursor compound to water used in the 1-1 step may be 1:2-20.

[0025] The amount of alumina used in the step 1-2 may be 3.5 to 7 times (molar ratio) the amount of lanthanum (La) in the lanthanum precursor compound in the step 1-1.

[0026] In the case of the above-mentioned molar ratio of alumina to lanthanum (La), the ratio of lanthanum (La) may be 12 mol % to 19 mol % based on the lanthanum aluminate support obtained in steps 1 to 3.

[0027] The heating reaction in the first and second stages may be carried out at 50°C to 100°C for 1 to 10 hours.

[0028] The removal of water in the first and second steps is carried out either (1) under reduced pressure during the heating reaction, or (2) after the heating reaction, by using a filter on the lanthanum-impregnated alumina product.

[0029] The drying in the first to third stages is carried out at 100°C to 200°C for 1 to 24 hours, and the firing may include (a) a primary firing at 150°C to 500°C for 5 to 12 hours and (b) a secondary firing at 500°C to 1200°C for 1 to 10 hours.

[0030] Specifically, the second step in the production of a ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity is as follows: (i) a step of dissolving a ruthenium precursor compound in a mixed solvent of water and alcohol to prepare a ruthenium precursor compound solution ("step 2-1 of preparing a ruthenium precursor compound solution"); (ii) mixing the lanthanum aluminate carrier prepared in steps 1-3 with the prepared solution, and then removing the solvent contained in the solution using a vacuum distiller at a certain temperature to prepare ruthenium-doped lanthanum aluminate pellets ("step 2-2 of preparing ruthenium-doped lanthanum aluminate pellets"); (iii) drying and reducing the prepared ruthenium-doped lanthanum aluminate pellets to obtain a ruthenium catalyst for ammonia decomposition reaction in which ruthenium is supported on lanthanum aluminate and has excellent ammonia decomposition activity ("Steps 2-3 of obtaining ruthenium catalyst").

[0031] The ruthenium precursor compound of the 2-1 step may be ruthenium chloride, ruthenium nitride, ruthenium acetylacetonate, or ruthenium iodide.

[0032] The volume ratio of water to alcohol in the 2-1 step is 1:0.5 to 1.5.

[0033] The alcohol in the 2-1 step may be one or more 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-pentanediol, and 1,2-hexadiol.

[0034] The amount of the mixed solution of water and alcohol used in the 2-1 step may be 50 to 200 times (by weight) per part by weight of the ruthenium precursor compound.

[0035] The dissolution in the 2-1 step is carried out at 50°C to 100°C.

[0036] The ruthenium precursor compound in the 2-1 step can be used in an amount of 1 to 40 parts by weight based on 100 parts by weight of the lanthanum aluminate support.

[0037] The amount of ruthenium in the ruthenium catalyst for ammonia decomposition reaction obtained through the use of the ruthenium precursor compound relative to the lanthanum aluminate support as described above and the drying and reduction steps 2 and 3 may be 0.5 wt % to 5 wt % based on the ruthenium catalyst for ammonia decomposition reaction.

[0038] The temperature of the vacuum distiller for removing the solvent in the 2-2 step is 50°C to 150°C, and the solvent is gradually removed over 1 to 5 hours.

[0039] The drying of the ruthenium-doped lanthanum aluminate pellets in the second and third steps is carried out in a conventional dryer at a temperature of 100°C to 200°C for 5 to 24 hours, and the reduction is carried out by loading the ruthenium-doped lanthanum aluminate pellets into a tubular furnace and treating them with hydrogen gas at 500°C to 1,500°C for 1 to 5 hours.

[0040] The hydrogen gas is diluted with an inert gas such as nitrogen to a concentration of 1 to 20 vol % before use.

[0041] The ruthenium catalyst for ammonia decomposition reaction of the present invention, which has excellent ammonia decomposition activity, is produced by producing the support in steps 1-1 to 1-3 and doping the support with ruthenium in steps 2-1 to 2-3. [Effects of the Invention]

[0042] The present invention has the advantage of enabling the development of a ruthenium catalyst for ammonia decomposition reaction that has high activity even in large-scale decomposition processes, low production costs, and is economical for the ammonia decomposition process, and has excellent ammonia decomposition activity. [Brief explanation of the drawings]

[0043] [Figure 1] FIG. 1 is a schematic diagram showing the production of a carrier used in the production of a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity according to the present invention. [Figure 2] 1 is a graph showing the hydrogen conversion rates of the ruthenium catalysts for ammonia decomposition reaction produced in Examples 1 to 3 according to the present invention and Comparative Examples 1 and 2. BEST MODE FOR CARRYING OUT THE INVENTION

[0044] The present invention will be described below with reference to preferred embodiments and drawings so that those skilled in the art can easily implement the present invention. Furthermore, when describing the present invention, if it is determined that a detailed description of related known functions or known configurations may obscure the gist of the present invention, the detailed description will be omitted.

[0045] The present invention can be modified in various ways and can have various embodiments, and specific embodiments will be illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to the specific embodiments, but should be understood to include all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention. Furthermore, throughout the specification, when any part "comprises" a certain element, this does not mean that it excludes other elements, but that it may further include other elements, unless otherwise specified.

[0046] The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless otherwise clearly indicated. In the present invention, terms such as "comprise" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0047] The present invention relates to a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity and a method for producing the same.

[0048] One embodiment of the present invention relates to a ruthenium catalyst for ammonia decomposition reaction that has excellent ammonia decomposition activity.

[0049] Specifically, the ruthenium catalyst (Ru-LaAlO) for ammonia decomposition reaction of the present invention, which has excellent ammonia decomposition activity, uses ruthenium (Ru) as an active metal in a lanthanum-doped alumina carrier, and the lanthanum-doped alumina carrier contains ruthenium (Ru).

[0050] The lanthanum-doped alumina support includes lanthanum aluminate (LaAlO3) with a perovskite structure.

[0051] The lanthanum content of the lanthanum-doped alumina as the support may be 12 mol % to 19 mol %, preferably 13 mol % to 19 mol %, and more preferably 13 mol % to 18 mol %, relative to lanthanum aluminate (LaAlO3).

[0052] That is, the ruthenium catalyst (Ru-LaAlO3) for ammonia decomposition reaction having excellent ammonia decomposition activity of the present invention has the following features: Ruthenium (Ru) is used as an active metal for ammonia decomposition in a lanthanum aluminate (LaAlO) carrier containing 12 mol % to 19 mol %, preferably 13 mol % to 19 mol %, and more preferably 13 mol % to 18 mol % of lanthanum, and the carrier contains ruthenium (Ru).

[0053] The amount of ruthenium in the ruthenium catalyst for ammonia decomposition reaction (Ru / LaAlO3) may be 0.5% by weight to 5% by weight.

[0054] Furthermore, the BET surface area (m 2 / g) is in the range of 50 to 93, and preferably in the range of 60 to 93.

[0055] Yet another embodiment of the present invention relates to a method for producing the ruthenium catalyst for ammonia decomposition reaction of the present invention, which has excellent ammonia decomposition activity.

[0056] Specifically, the method for producing a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity of the present invention includes the steps of: (a) doping alumina with lanthanum to produce a lanthanum-doped alumina support containing lanthanum aluminate (LaAlO) with a perovskite structure ("first step of producing a lanthanum aluminate support"); (b) providing ruthenium on the lanthanum aluminate support to obtain a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity, in which ruthenium is supported on lanthanum aluminate ("second step of producing a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity").

[0057] Specifically, the first step in the preparation of the lanthanum aluminate (LaAlO) support is: (i) preparing an aqueous solution of lanthanum containing a lanthanum precursor compound and water ("Step 1-1 of preparing an aqueous solution of lanthanum"); (ii) mixing the lanthanum aqueous solution with alumina, and then obtaining lanthanum-doped alumina by heating and removing water ("first and second steps of obtaining lanthanum-doped alumina"); (iii) drying and calcining the obtained lanthanum-doped alumina to obtain a lanthanum aluminate support ("Steps 1-3 of obtaining a lanthanum aluminate support") (see FIG. 1).

[0058] The ratio (parts by weight) of the lanthanum precursor compound to the amount of water used in the 1-1 step may be 1:2-20, preferably 1:5-15.

[0059] The preparation of the lanthanum aqueous solution in the 1-1 step may be carried out at a temperature of 50°C to 100°C, preferably 50°C to 80°C.

[0060] The amount of alumina used in the step 1-2 may be 3.5 to 7 times (molar ratio) the amount of lanthanum (La) in the lanthanum precursor compound in the step 1-1.

[0061] The alumina may be in the form of a powder or pellets, and is preferably in the form of pellets.

[0062] In the case of the above-mentioned molar ratio of alumina and lanthanum (La), the ratio of lanthanum (La) may be 12 mol % to 19 mol % based on the lanthanum aluminate support obtained in steps 1 to 3.

[0063] The heating reaction in the first and second stages may be carried out at 50°C to 100°C for 1 to 10 hours, preferably at 50°C to 80°C for 1 to 5 hours.

[0064] The removal of water in the first and second steps may be carried out either (1) by reducing the pressure during the heating reaction, or (2) by using a filter on the lanthanum-impregnated alumina product after the heating reaction.

[0065] The reduced pressure in the first and second stages of water removal may be 1000 mbar to 40 mbar.

[0066] The drying in the first to third stages is carried out at 100°C to 200°C for 1 to 24 hours, and the firing may include (a) a primary firing at 200°C to 500°C for 5 to 12 hours and (b) a secondary firing at 500°C to 1200°C for 1 to 10 hours.

[0067] Preferably, the drying in the first to third stages is carried out at 100°C to 150°C for 5 to 15 hours, and the firing may include (a) a primary firing at 150°C to 350°C for 5 to 10 hours and (b) a secondary firing at 600°C to 1000°C for 2 to 7 hours.

[0068] Specifically, the second stage of the catalyst production comprises: (i) a step of dissolving a ruthenium precursor compound in a mixed solvent of water and alcohol to prepare a ruthenium precursor compound solution ("step 2-1 of preparing a ruthenium precursor compound solution"); (ii) mixing the lanthanum aluminate (LaAlO3) carrier prepared in steps 1-3 with the prepared solution, and then removing the solvent contained in the solution using a vacuum distiller at a certain temperature to prepare ruthenium-doped lanthanum aluminate pellets ("step 2-2 of preparing ruthenium-doped lanthanum aluminate pellets"); (iii) drying and reducing the prepared ruthenium-doped lanthanum aluminate pellets to obtain a ruthenium catalyst for ammonia decomposition (Ru-LaAlO3) in which ruthenium is supported on lanthanum aluminate and has excellent ammonia decomposition activity ("Steps 2-3 of obtaining ruthenium catalyst").

[0069] The ruthenium precursor compound of the 2-1 step may be ruthenium chloride, ruthenium nitride, ruthenium acetylacetonate, or ruthenium iodide, and preferably ruthenium chloride.

[0070] The alcohol in the 2-1 step may be one or more 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-pentanediol, and 1,2-hexadiol.

[0071] The alcohol in the 2-1 step may preferably be one or more selected from the group consisting of ethanol, propanol, ethylene glycol, and diethylene glycol.

[0072] The volume ratio of water to alcohol in the 2-1 step may be 1:0.5 to 1.5, preferably 1:1.

[0073] The amount of the mixed solution of water and alcohol used in the 2-1 step may be 50 to 200 times (weight ratio) per part by weight of the ruthenium precursor compound, and preferably 70 to 150 times (weight ratio).

[0074] By using a mixture of water and alcohol as described above, the ruthenium precursor compound can be uniformly dispersed, and the active metal ruthenium for ammonia decomposition can be uniformly dispersed and doped on the lanthanum aluminate support.

[0075] The dissolution in the 2-1 step is carried out at a temperature of 50 to 100°C, preferably 50 to 80°C.

[0076] The ruthenium precursor compound in the 2-1 step may be used in an amount of 1 to 40 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the lanthanum aluminate support.

[0077] The amount of ruthenium in the ruthenium catalyst for ammonia decomposition reaction obtained through the use of the ruthenium precursor compound for the lanthanum aluminate support as described above and the drying and reduction steps 2 and 3 may be 0.5 wt % to 5 wt % based on the total weight of the ruthenium catalyst for ammonia decomposition reaction.

[0078] The temperature of the vacuum distiller for removing the solvent in the 2-2 step is 50°C to 150°C, preferably 50°C to 100°C, and the solvent is gradually removed for 1 to 5 hours.

[0079] The reduced pressure in the 2-2 stage vacuum distiller may be 1000 mbar to 40 mbar.

[0080] The drying of the ruthenium-doped lanthanum aluminate pellets in the second and third steps is carried out using a conventional dryer at a temperature of 100°C to 200°C for 5 to 24 hours, and the reduction is carried out by loading the ruthenium-doped lanthanum aluminate pellets into a tubular furnace and treating them using hydrogen gas at 500°C to 1,500°C for 1 to 5 hours.

[0081] Preferably, the drying of the ruthenium-doped lanthanum aluminate pellets in the second and third steps is carried out in a conventional dryer at a temperature of 100°C to 150°C for 5 to 15 hours, and the reduction is carried out by loading the ruthenium-doped lanthanum aluminate pellets into a tubular furnace and treating them with hydrogen gas at 500°C to 1,000°C for 1 to 5 hours.

[0082] The hydrogen gas is diluted with an inert gas such as nitrogen at 1 to 20 vol %, preferably 1 to 10 vol % before use.

[0083] The ruthenium catalyst for ammonia decomposition reaction of the present invention, which has excellent ammonia decomposition activity, is produced by producing the support in steps 1-1 to 1-3 and doping the support with ruthenium in steps 2-1 to 2-3. DETAILED DESCRIPTION OF THE INVENTION

[0084] The present invention will be described below based on specific examples and comparative examples.

[0085] Example 1 A lanthanum aqueous solution was prepared by adding 29.28 g (67.6 mmol) of lanthanum nitrate hydrate to 250 ml of pure water in an upper and lower reaction vessel and dissolving the solution 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 were added to the prepared lanthanum aqueous solution, and the mixture was then placed in a vacuum distiller. The pressure was gradually reduced from 1000 mbar to 70 mbar at 70° C. for 2 hours, and the lanthanum-impregnated pellets were recovered.

[0086] 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 where they were fired stepwise at 200°C for 8 hours and at 900°C for 5 hours to obtain 48.5g of carrier (98.6% yield).

[0087] As a result of ICP analysis of the obtained carrier, the amount of lanthanum (La) impregnated in the carrier was 13.5 mol %.

[0088] In another separate reactor, 2.55 g (12.3 mmol) of ruthenium chloride was dissolved in a solution of 125 ml of pure water and 125 ml of ethanol at 60°C for 10 minutes, and then 40.4 g of the obtained support pellets was added. The mixture was then connected to a vacuum distiller and distilled at 70°C for 3 hours while gradually reducing the pressure from 1000 mbar to 40 mbar to produce ruthenium-impregnated pellets. The recovered ruthenium-impregnated pellets were dried in a general dryer at 110°C for 12 hours and then loaded into a tubular furnace and reduced using 5 vol% hydrogen gas (diluted with nitrogen) at 730°C for 2 hours to produce 40.8 g (98.0% yield) of a ruthenium catalyst for ammonia decomposition with excellent ammonia decomposition activity.

[0089] As a result of ICP analysis of the prepared catalyst, the impregnation amount of ruthenium (Ru) in the ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity was 0.97 wt %.

[0090] ICP analysis to measure the amount of lanthanum (La) impregnated in the support and the content of ruthenium (Ru) in the catalyst was performed using an inductively coupled plasma atomic emission spectrometer, iCAP7400, manufactured by Thermo Scientific Corp. For the measurement, hydrochloric acid was added to each support and catalyst in Example 1, and the catalyst was dissolved by ultrasonic waves before measurement.

[0091] In the following Examples 2 and 3 and Comparative Examples 1 and 2, the ICP analysis for measuring the amount of lanthanum (La) impregnated in the carrier and the content of ruthenium (Ru) in the catalyst was carried out by the method described above.

[0092] <Example 2> A carrier was prepared in the same manner as in Example 1, except that 30.66 g (70.8 mmol) of lanthanum nitrate hydrate was used. ICP analysis of the prepared carrier revealed that the amount of lanthanum (La) impregnated in the carrier was 16.9 mol%.

[0093] Using the carrier, a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity was produced in the same manner as in Example 1.

[0094] As a result of ICP analysis of the prepared catalyst, the impregnation amount of ruthenium (Ru) in the ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity was 1.04 wt %.

[0095] Example 3 A carrier was prepared in the same manner as in Example 1, except that 31.20 g (72.1 mmol) of lanthanum nitrate hydrate was used. ICP analysis of the prepared carrier revealed that the amount of lanthanum (La) impregnated in the carrier was 18.2 mol%.

[0096] Using the carrier, a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity was produced in the same manner as in Example 1.

[0097] As a result of ICP analysis of the prepared catalyst, the impregnation amount of ruthenium (Ru) in the ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity was 1.01 wt %.

[0098] <Comparative Example 1> A carrier was prepared in the same manner as in Example 1, except that 22.5 g (52.0 mmol) of lanthanum nitrate hydrate was used. ICP analysis of the prepared carrier revealed that the impregnation amount of lanthanum (La) in the carrier was 11.9 mol%.

[0099] Using the carrier, a ruthenium catalyst for ammonia decomposition reaction was produced in the same manner as in Example 1.

[0100] As a result of ICP analysis of the prepared catalyst, the impregnation amount of ruthenium (Ru) in the ruthenium catalyst for ammonia decomposition reaction was 0.91 wt %.

[0101] <Comparative Example 2> A carrier was prepared in the same manner as in Example 1, except that 54.5 g (125.9 mmol) of lanthanum nitrate hydrate was used. ICP analysis of the prepared carrier revealed that the amount of lanthanum (La) impregnated in the carrier was 20.4 mol%.

[0102] Using the carrier, a ruthenium catalyst for ammonia decomposition reaction was produced in the same manner as in Example 1.

[0103] As a result of ICP analysis of the prepared catalyst, the impregnation amount of ruthenium (Ru) in the ruthenium catalyst for ammonia decomposition reaction was 0.95 wt %.

[0104] BET surface area (m) of ruthenium catalyst for ammonia decomposition reaction 2 / g) and total pore volume (cm 3 / g) Features> Table 1 below shows the BET surface area (m) of the ruthenium catalysts for ammonia decomposition reaction prepared in Examples 1 to 3 and Comparative Examples 1 and 2. 2 / g) and total pore volume (cm 3 / g).

[0105] The BET surface area and total pore volume were determined by analyzing the specific surface area through the physical adsorption of nitrogen gas using a Tristar II 3020 model manufactured by Micromeritics.

[0106] For the above analysis, the catalysts prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were pretreated using VacPrep 061, vacuum type, at 150° C. for 4 hours under vacuum.

[0107] The specific surface area of ​​the catalyst was measured using the Brunauer-Emmett-Teller (BET) equation at a temperature of -196°C with liquid nitrogen (purity 99.999%), with the isothermal adsorption and desorption of nitrogen gas in the range of P / P0 = 0.005-0.995.

[0108] The total pore volume was calculated using the amount of nitrogen adsorbed at P / P0 = 0.99.

[0109] [Table 1]

[0110] As can be seen from Table 1, the BET surface area (m 2 The BET surface areas (m / g) of the ruthenium catalyst for ammonia decomposition reaction of the present invention, which has excellent ammonia decomposition activity, were 92.5, 71.3 and 64.3, respectively. 2 / g) of 50 to 93.

[0111] In contrast, the BET surface area (m) of the ruthenium catalysts for ammonia decomposition reaction according to Comparative Examples 1 and 2, which are outside the range of the lanthanum (La) content in the carrier of the present invention, was 2 The BET surface area (m / g) of the ruthenium catalyst for ammonia decomposition reaction of the present invention, which has excellent ammonia decomposition activity, was 93.5 and 46.9, respectively. 2 / g), which is outside the range of 50 to 93.

[0112] <Measurement of ammonia conversion rate> Ammonia decomposition reactions were carried out using the catalysts prepared in Examples 1 to 3 and Comparative Examples 1 and 2, and the ammonia conversion rates were measured.

[0113] The measurement was performed at atmospheric pressure with an ammonia space velocity (GHSV) of 3,000 ml / (g cat The ammonia decomposition ability was measured under conditions of (h) and reaction temperatures of 450°C, 500°C, 550°C, and 600°C, and the ammonia conversion rate was shown in Table 2 below (see Figure 2).

[0114] [Table 2]

[0115] As can be seen from Table 2 above, Examples 1 to 3, which correspond to the ruthenium catalyst for ammonia decomposition reaction of the present invention having excellent ammonia decomposition activity, show a conversion rate of 93.6% or more at a reaction temperature of 500°C. Even at a reaction temperature of 550°C, Examples 1 and 2 both show a conversion rate of 99.8%, which is nearly 100%, and Example 3 shows a conversion rate of 99.3%, so Examples 1 to 3 show a conversion rate of more than 99%.

[0116] In contrast, Comparative Example 1 shows a conversion rate of about 99.0%, while Comparative Example 2 shows a conversion rate of 98.6%, both of which are below 99%.

[0117] Furthermore, even at a reaction temperature of 450°C, Comparative Examples 1 and 2 showed conversion rates of 49.0% and 37.6%, respectively, which were lower than 50%, whereas Examples 1 to 3 showed conversion rates of 65.2%, 69.1%, and 59.0%, respectively, which were approximately 60% or higher.

[0118] The scope of the present invention is not limited to the above-described embodiments, but may be embodied in various forms within the scope of the accompanying claims. Any person having ordinary skill in the art to which the invention pertains may modify the invention to a wide range without departing from the spirit of the invention as claimed in the claims.

[0119] While the present invention has been described above with reference to specific embodiments, it is understood that these embodiments are merely illustrative of the 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 concepts of the present invention without departing from the spirit and scope of the present invention. [Industrial Applicability]

[0120] As described above, the catalysts of Examples 1 to 3, which are ruthenium catalysts for ammonia decomposition reactions of the present invention with excellent ammonia decomposition activity, exhibit a conversion rate of nearly 100% at a reaction temperature of 550°C, and also exhibit a conversion rate of 93.6% or more even at 500°C, and a conversion rate of approximately 60% or more even at a low reaction temperature of 450°C.Therefore, they can be applied to the mass production of hydrogen through the decomposition reaction of ammonia even at relatively low temperatures, and have the effect of being highly economical in the process of producing hydrogen from ammonia.

Claims

1. Lanthanum doped alumina, lanthanum aluminate (LaAlO ３ ) as a support and ruthenium as an active metal. ３ ) where The support is lanthanum-doped alumina, lanthanum aluminate (LaAlO ３ 1. A ruthenium catalyst for ammonia decomposition reaction, comprising 12 mol % to 19 mol % of lanthanum relative to the total amount of ruthenium.

2. The ruthenium catalyst for ammonia decomposition reaction (Ru / LaAlO ３ 2. The ruthenium catalyst for ammonia decomposition reaction according to claim 1, wherein the amount of ruthenium in the catalyst is 0.5% by weight to 5% by weight.

3. The ruthenium catalyst for ammonia decomposition reaction (Ru / LaAlO ３ BET surface area (m) of ruthenium in ２ 2. The ruthenium catalyst for ammonia decomposition reaction according to claim 1, wherein the ruthenium content (A / g) is in the range of 50 to 93.

4. The support is lanthanum-doped alumina, lanthanum aluminate (LaAlO ３ 2. The ruthenium catalyst for ammonia decomposition reaction according to claim 1, wherein lanthanum is contained in an amount of 13 mol % to 19 mol % relative to the total amount of ruthenium.

5. The support is lanthanum-doped alumina, lanthanum aluminate (LaAlO ３ 2. The ruthenium catalyst for ammonia decomposition reaction according to claim 1, wherein lanthanum is contained in an amount of 13 mol % to 18 mol % relative to the total amount of ruthenium.

6. (a) Lanthanum is doped into alumina to form lanthanum aluminate (LaAlO) with a perovskite structure. ３ a step of preparing a lanthanum-doped alumina support comprising: (b) providing ruthenium on the lanthanum aluminate support to obtain a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity, in which ruthenium is supported on lanthanum aluminate ("second step of producing a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity"). The first step in the preparation of the lanthanum aluminate support is to (i) preparing an aqueous lanthanum solution of a lanthanum precursor compound and water ("1-1 step of preparing an aqueous lanthanum solution"); (ii) mixing the lanthanum aqueous solution with alumina, and then obtaining lanthanum-doped alumina by heating and removing water ("first and second steps of obtaining lanthanum-doped alumina"); (iii) drying and calcining the obtained lanthanum-doped alumina to obtain a lanthanum aluminate support ("first to third steps of obtaining a lanthanum aluminate support"); The ratio (parts by weight) of the lanthanum precursor compound to water used in the step 1-1 is 1:2 to 20; The amount of alumina used in the step 1-2 is 3.5 to 7 times (molar ratio) the amount of lanthanum (La) in the lanthanum precursor compound in the step 1-1; In the case of the above-mentioned molar ratio of alumina and lanthanum (La), the ratio of lanthanum (La) is 12 mol% to 19 mol% based on the lanthanum aluminate support obtained in steps 1 to 3.

7. The heating reaction in the first and second steps is carried out at 50°C to 100°C for 1 to 10 hours; The method for producing a ruthenium catalyst for ammonia decomposition reaction according to claim 6, wherein the removal of water in the first and second steps is carried out either (1) under reduced pressure during the heating reaction, or (2) after the heating reaction, by using a filter on the lanthanum-impregnated alumina product.

8. The drying in the first to third steps is carried out at 100°C to 200°C for 1 to 24 hours, The method for producing a ruthenium catalyst for ammonia decomposition reaction according to claim 6, characterized in that the calcination comprises (a) a primary calcination at 150°C to 500°C for 5 to 12 hours, and (b) a secondary calcination at 500°C to 1200°C for 1 to 10 hours.

9. The second step of preparing the ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity is to (i) dissolving a ruthenium precursor compound in a mixed solvent of water and alcohol to prepare a ruthenium precursor compound solution ("step 2-1 of preparing a ruthenium precursor compound solution"); (ii) mixing the lanthanum aluminate carrier prepared in the steps 1-3 with the prepared solution, and then removing the solvent contained in the solution using a vacuum distiller at a certain temperature to prepare ruthenium-doped lanthanum aluminate pellets ("step 2-2 of preparing ruthenium-doped lanthanum aluminate pellets"); (iii) drying and reducing the prepared ruthenium-doped lanthanum aluminate pellets to obtain a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity, in which ruthenium is supported on lanthanum aluminate ("second and third steps of obtaining ruthenium catalyst"); The ruthenium precursor compound of the second-first step may be ruthenium chloride, ruthenium nitride, ruthenium acetylacetonate, or ruthenium iodide; The volume ratio of water to alcohol in the 2-1 step is 1:0.5 to 1.5; 7. The method for preparing a ruthenium catalyst for ammonia decomposition reaction of claim 6, wherein the alcohol in step 2-1 is 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-pentanediol, and 1,2-hexadiol.

10. The amount of the mixed solution of water and alcohol used in the step 2-1 is 50 to 200 times (by weight) per 1 part by weight of the ruthenium precursor compound; The dissolution of the second-1 step is carried out at 50°C to 100°C, The ruthenium precursor compound in the second-1 step is used in an amount of 1 to 40 parts by weight based on 100 parts by weight of the lanthanum aluminate support; 7. The method for preparing a ruthenium catalyst for ammonia decomposition reaction according to claim 6, wherein the amount of ruthenium precursor compound used for the lanthanum aluminate support and the amount of ruthenium in the ruthenium catalyst for ammonia decomposition reaction obtained through the drying and reduction steps 2 and 3 are 0.5 wt % to 5 wt % based on the ruthenium catalyst for ammonia decomposition reaction.

11. The temperature of the vacuum distiller for removing the solvent in the second-2 step is 50°C to 150°C, and the solvent removal is carried out gradually over 1 to 5 hours; The drying of the ruthenium-doped lanthanum aluminate pellets in the second and third steps is carried out in a conventional dryer at a temperature of 100°C to 200°C for 5 to 24 hours; The reduction is carried out by loading the ruthenium-doped lanthanum aluminate pellets into a tubular furnace and treating them with hydrogen gas at 500°C to 1,500°C for 1 to 5 hours; 7. The method for producing a ruthenium catalyst for an ammonia decomposition reaction according to claim 6, wherein the hydrogen gas is diluted with an inert gas such as nitrogen at 1 to 20 vol %.

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