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

Abstract

The present invention provides: a ruthenium catalyst for ammonia decomposition, the ruthenium catalyst having excellent ammonia decomposition activity; and a method for producing same. The ruthenium catalyst exhibits a conversion rate close to 100% at a reaction temperature of 550 °C, exhibits a conversion rate of at least 93.6% even at 500 °C, and exhibits a conversion rate of at least about 60%, even at a low reaction temperature of 450 °C, and thus has high activity, even in a large-scale decomposition process of a relatively low temperature, while having a low production cost, therefore making the ammonia decomposition process economical.

Description

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

[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.

[0002]

[0003] Recently, the issue of rising global temperatures due to global warming caused by fossil fuel use has resurfaced. Hydrogen, an alternative energy source for fossil fuels, is attracting attention because it produces only water when burned, eliminating the global warming agent CO2 and air pollutants.

[0004]

[0005] However, hydrogen cannot exist alone in nature and exists together with other elements, most notably as ammonia with nitrogen.

[0006]

[0007] Meanwhile, ammonia, which produces only nitrogen and hydrogen when decomposed and has the advantage of being an environmentally friendly hydrogen source, can be mass-produced industrially and is easy to liquefy, making it advantageous for transportation and storage.

[0008]

[0009] 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] 2NH3<-> 3H2+ N2(reaction enthalpy = 46KJ / mol)

[0013]

[0014] It is known that ammonia decomposition as described above generally takes place at high temperatures of 500 to 900°C, but the conversion rate of ammonia to hydrogen is low, so a catalyst is used in the ammonia decomposition reaction to improve the hydrogen conversion rate.

[0015] Catalysts for ammonia decomposition reactions use precious or non-precious metals as active metals. Among precious metal catalysts, ruthenium (Ru) has been reported to be the best, and among non-precious metal catalysts, Ni has been reported to be the best.

[0016]

[0017] The catalyst using the above ruthenium (Ru) or nickel as an active material uses various carriers in an attempt to increase the 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] 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.

[0020]

[0021] Therefore, there is an urgent need to develop an ammonia decomposition reaction catalyst that is highly active and has low manufacturing costs, making it economical for the ammonia decomposition process even in large-scale decomposition processes.

[0022]

[0023] The present invention provides a ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity that is highly active even in a large-scale decomposition process and has low manufacturing cost, thereby making the ammonia decomposition process economical, and a method for producing the same.

[0024]

[0025] 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.

[0026]

[0027] For the above purpose, the present invention provides a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity, and a method for producing the same.

[0028]

[0029] Specifically, the ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention is a catalyst that includes lanthanum-doped alumina as a carrier and uses ruthenium as an active metal.

[0030] The above-mentioned carrier, lanthanum-doped alumina, includes lanthanum aluminate (LaAlO3) having a perovskite structure.

[0031] In the lanthanum-doped alumina, which is the carrier, lanthanum aluminate (LaAlO3) may be contained in an amount of 12 mol% to 19 mol%.

[0032]

[0033] The ruthenium catalyst (Ru-LaAlO3) for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention uses ruthenium (Ru) as an active metal in the carrier of the above-mentioned lanthanum aluminate (LaAlO3), so that ruthenium (Ru) is included in the carrier, lanthanum-doped alumina.

[0034] 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%.

[0035] In addition, the BET surface area (m) of the ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention 2 / g) has a range of “50 to 93”.

[0036]

[0037] In addition, the method for producing a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity of the present invention is as follows:

[0038] a) a step of preparing a carrier of lanthanum-doped alumina containing lanthanum aluminate (LaAlO3) having a perovskite structure by doping lanthanum into alumina ('first step of preparing lanthanum aluminate carrier'); and

[0039] b) a step of providing ruthenium to the lanthanum aluminate support to obtain a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity, in which ruthenium is supported on the lanthanum aluminate ('second step of producing a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity');

[0040]

[0041] Specifically, the first step of manufacturing the above lanthanum aluminate carrier is:

[0042] 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');

[0043] 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

[0044] 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');

[0045]

[0046] The ratio (parts by weight) of the lanthanum precursor compound:water in the above step 1-1 may be 1:2 to 20.

[0047]

[0048] The amount of alumina used in the above step 1-2 may be 3.5 to 7 times (molar ratio) the amount of lanthanum (lanthanum, La) in the lanthanum precursor compound in the above step 1-1.

[0049] When the molar ratio of alumina and lanthanum (lanthanum, La) is used as described above, the proportion of the lanthanum (lanthanum, La) may be included at 12 mol% to 19 mol% with respect to the lanthanum aluminate carrier obtained in the above steps 1-3.

[0050] The heating reaction of the above steps 1-2 may be performed at 50°C to 100°C for 1 to 10 hours.

[0051] In addition, the removal of water in the above 1-2 steps is accomplished by ① reducing pressure in the heating reaction, or ② using a filter to filter the product, which is alumina impregnated with lanthanum, after the heating reaction.

[0052]

[0053] The drying of the above 1-3 steps is performed at 100°C to 200°C for 1 to 24 hours, and the firing may include (a) primary firing at 150°C to 500°C for 5 to 12 hours, and (b) secondary firing at 500°C to 1200°C for 1 to 10 hours.

[0054]

[0055] Specifically, the second step in the production of a ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity is:

[0056] i) a step of preparing a ruthenium precursor compound solution by dissolving the ruthenium precursor compound in a mixed solvent of water and alcohol ('Step 2-1 of preparing a ruthenium precursor compound solution');

[0057] ii) a step of mixing the lanthanum aluminate carrier prepared in steps 1-3 into the prepared solution and then removing the solvent contained in the solution using a reduced pressure distiller at a constant temperature to prepare ruthenium-doped lanthanum aluminate pellets ('step 2-2 of preparing ruthenium-doped lanthanum aluminate pellets'); and

[0058] iii) a step of drying and reducing the manufactured 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 ('step 2-3 of obtaining ruthenium catalyst');

[0059]

[0060] The ruthenium precursor compound of the above 2-1 step may be ruthenium chloride, ruthenium nitride, ruthenium acetylacetonate, or ruthenium iodide.

[0061] The volume ratio of water:alcohol in the above 2-1 step is 1:0.5 to 1.5.

[0062] The alcohol of the above 2-1 step 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.

[0063] The amount of the mixed solution of water and alcohol used in the above step 2-1 may be 50 to 200 times (weight ratio) per 1 part by weight of the ruthenium precursor compound.

[0064] The melting in the above 2-1 step is carried out at 50°C to 100°C.

[0065] The ruthenium precursor compound of the above-mentioned 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 carrier.

[0066] The amount of ruthenium precursor compound used for the lanthanum aluminate carrier as described above, and ruthenium in the ruthenium catalyst for ammonia decomposition reaction obtained through the drying and reduction of the 2nd and 3rd steps may be included in an amount of 0.5 wt% to 5 wt% with respect to the ruthenium catalyst for ammonia decomposition reaction.

[0067]

[0068] The temperature of the reduced pressure distillation unit for solvent removal in the above-mentioned step 2-2 is 50°C to 150°C, and the solvent removal is carried out slowly over 1 to 5 hours.

[0069]

[0070] The drying of the ruthenium-doped lanthanum aluminate pellets in the above 2-3 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 filling 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.

[0071] The above hydrogen gas is used diluted in an inert gas such as nitrogen at 1 to 20 vol%.

[0072]

[0073] By manufacturing the carrier in steps 1-1 to 1-3 as described above and doping the carrier with ruthenium in steps 2-1 to 2-3, a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity of the present invention is manufactured.

[0074]

[0075] According to the present invention, there is an advantage in that it is possible to develop a ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity that is highly active even in a large-scale decomposition process and has low manufacturing cost, thereby making the ammonia decomposition process economically feasible.

[0076]

[0077] Figure 1 is a schematic diagram regarding the preparation of a carrier used in the preparation of a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity of the present invention.

[0078] Figure 2 is a graph showing the hydrogen conversion rate according to the ruthenium catalyst for ammonia decomposition reaction manufactured in Examples 1 to 3 and Comparative Examples 1 to 2 according to the present invention.

[0079]

[0080] 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.

[0081]

[0082] 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.

[0083]

[0084] 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.

[0085]

[0086] The terminology used herein is merely 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 specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0087]

[0088] The present invention relates to a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity, and a method for producing the same.

[0089]

[0090] One embodiment of the present invention relates to a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity.

[0091]

[0092] Specifically, the ruthenium catalyst (Ru-LaAlO3) for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention uses ruthenium (Ru) as an active metal in a carrier of lanthanum-doped alumina, so that ruthenium (Ru) is included in the carrier, lanthanum-doped alumina.

[0093] The above-mentioned carrier, lanthanum-doped alumina, includes lanthanum aluminate (LaAlO3) having a perovskite structure.

[0094] In the lanthanum aluminate (LaAlO3) of the above-mentioned carrier, lanthanum may be included in an amount of 12 mol% to 19 mol%. Preferably, it is 13 mol% to 19 mol%, and more preferably, it is 13 mol% to 18 mol%.

[0095]

[0096] That is, the ruthenium catalyst (Ru-LaAlO3) for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention is,

[0097] Ruthenium (Ru) is used as an active metal for ammonia decomposition in a carrier of lanthanum aluminate (LaAlO3) containing 12 mol% to 19 mol% of the above lanthanum, preferably 13 mol% to 19 mol%, more preferably 13 mol% to 18 mol%, so that ruthenium (Ru) is contained in the carrier.

[0098]

[0099] The amount of ruthenium in the ruthenium catalyst (Ru / LaAlO3) for the above ammonia decomposition reaction may be 0.5 wt% to 5 wt%.

[0100]

[0101] In addition, the BET surface area (m) of the ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention 2 / g) has a range of “50 to 93”, preferably “60 to 93”.

[0102]

[0103] Another embodiment of the present invention relates to a method for producing a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity.

[0104]

[0105] Specifically, the method for producing a ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention is as follows:

[0106] a) a step of preparing a carrier of lanthanum-doped alumina containing lanthanum aluminate (LaAlO3) having a perovskite structure by doping lanthanum into alumina ('first step of preparing lanthanum aluminate carrier'); and

[0107] b) a step of providing ruthenium to the lanthanum aluminate support to obtain a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity, in which ruthenium is supported on the lanthanum aluminate ('second step of producing a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity');

[0108]

[0109] Specifically, the first step of manufacturing the lanthanum aluminate (LaAlO3) carrier is:

[0110] 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');

[0111] 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

[0112] 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).

[0113]

[0114] The ratio (parts by weight) of the lanthanum precursor compound:water in the above step 1-1 may be 1:2 to 20, and preferably 1:5 to 15.

[0115] The preparation of the lanthanum aqueous solution in the above step 1-1 can be performed at 50°C to 100°C, and preferably at 50°C to 80°C.

[0116]

[0117] The amount of alumina used in the above step 1-2 may be 3.5 to 7 times (molar ratio) the amount of lanthanum (lanthanum, La) in the lanthanum precursor compound in the above step 1-1.

[0118] The above alumina can be used in powder or pellet form, and is preferably in pellet form.

[0119] When the molar ratio of alumina and lanthanum (lanthanum, La) is used as described above, the proportion of lanthanum (lanthanum, La) may be included at 12 mol% to 19 mol% with respect to the lanthanum aluminate carrier obtained in the first to third steps.

[0120] The heating reaction of the above 1-2 steps may be performed at 50°C to 100°C for 1 to 10 hours, and preferably at 50°C to 80°C for 1 to 5 hours.

[0121] 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.

[0122] The pressure reduction for water removal in the above steps 1-2 may be 1000 mbar to 40 mbar.

[0123]

[0124] The drying of the above 1-3 steps is performed at 100°C to 200°C for 1 to 24 hours, and the firing may include (a) primary firing at 200°C to 500°C for 5 to 12 hours, and (b) secondary firing at 500°C to 1200°C for 1 to 10 hours.

[0125] Preferably, the drying of steps 1-3 is performed at 100°C to 150°C for 5 to 15 hours, and the firing may also 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.

[0126]

[0127] Specifically, the second step of manufacturing the catalyst is:

[0128] i) a step of preparing a ruthenium precursor compound solution by dissolving the ruthenium precursor compound in a mixed solvent of water and alcohol ('Step 2-1 of preparing a ruthenium precursor compound solution');

[0129] ii) a step of mixing the lanthanum aluminate (LaAlO3) carrier prepared in steps 1-3 into the prepared solution and then removing the solvent contained in the solution using a reduced pressure distiller at a constant temperature to prepare ruthenium-doped lanthanum aluminate pellets ('step 2-2 of preparing ruthenium-doped lanthanum aluminate pellets'); and

[0130] iii) a step of drying and reducing the ruthenium-doped lanthanum aluminate pellets manufactured above to obtain a ruthenium catalyst (Ru-LaAlO3) for ammonia decomposition reaction with excellent ammonia decomposition activity supported on lanthanum aluminate with ruthenium ('step 2-3 of obtaining ruthenium catalyst').

[0131]

[0132] The ruthenium precursor compound of the above 2-1 step may be ruthenium chloride, ruthenium nitride, ruthenium acetylacetonate, or ruthenium iodide, and preferably ruthenium chloride.

[0133] The alcohol of the above 2-1 step 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.

[0134] The alcohol of the above step 2-1 may preferably be at least one selected from the group consisting of ethanol, propanol, ethylene glycol, and diethylene glycol.

[0135] The volume ratio of water:alcohol in the above 2-1 step is 1:0.5 to 1.5, and preferably 1:1.

[0136] The amount of the mixed solution of water and alcohol used in the above step 2-1 may be 50 to 200 times (weight ratio) based on 1 part by weight of the ruthenium precursor compound, and preferably 70 to 150 times (weight ratio).

[0137] By mixing alcohol in water as described above, the ruthenium precursor compound can be uniformly dispersed, so that ruthenium, an active metal for ammonia decomposition, can be uniformly dispersed and doped on the carrier, lanthanum aluminate.

[0138] The dissolution in the above 2-1 step is performed at 50°C to 100°C, and preferably at 50°C to 80°C.

[0139] The ruthenium precursor compound of the above-mentioned 2-1 step can be used in an amount of 1 to 40 parts by weight, and preferably 5 to 20 parts by weight, based on 100 parts by weight of the above-mentioned lanthanum aluminate carrier.

[0140] The amount of ruthenium precursor compound used for the lanthanum aluminate carrier as described above, and ruthenium in the ruthenium catalyst for ammonia decomposition reaction obtained through the drying and reduction of the 2nd and 3rd steps may be included in an amount of 0.5 wt% to 5 wt% based on the entire ruthenium catalyst for ammonia decomposition reaction.

[0141]

[0142] The temperature of the reduced pressure distillation unit for solvent removal in the above-mentioned 2-2 step is 50°C to 150°C, preferably 50°C to 100°C, and the solvent is gradually removed over a solvent removal time of 1 to 5 hours.

[0143] The reduced pressure of the pressure reducing distillation unit of the above 2-2 step can be 1000 mbar to 40 mbar.

[0144] The drying of the ruthenium-doped lanthanum aluminate pellets in the above 2-3 steps is carried out at a temperature of 100°C to 200°C for 5 to 24 hours using a conventional dryer, and the reduction is carried out by filling 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.

[0145] Preferably, the drying of the ruthenium-doped lanthanum aluminate pellets in the second to third steps is performed in a conventional dryer at a temperature of 100°C to 150°C for 5 to 15 hours, and the reduction is performed by filling the ruthenium-doped lanthanum aluminate pellets into a tubular furnace and treating them using hydrogen gas at 500°C to 1,000°C for 1 to 5 hours.

[0146]

[0147] The above hydrogen gas is used diluted in an inert gas such as nitrogen at 1 to 20 vol%, preferably 1 to 10 vol%.

[0148]

[0149] By manufacturing the carrier in steps 1-1 to 1-3 as described above and doping the carrier with ruthenium in steps 2-1 to 2-3, a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity of the present invention is manufactured.

[0150]

[0151] Below, the present invention is described using specific examples and comparative examples.

[0152]

[0153] <Example 1>

[0154] 29.28 g (67.6 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 (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 after connecting to a reduced pressure distillation apparatus, distillation was performed at 70°C for 2 hours while gradually reducing the pressure from 1000 mbar to 70 mbar to recover the pellets impregnated with lanthanum.

[0155] The above-mentioned recovered pellets were dried in a general dryer at a temperature of 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 48.5 g of a carrier (98.6% yield).

[0156]

[0157] As a result of ICP analysis of the carrier obtained above, the impregnation amount of lanthanum (La) in the carrier was 13.5 mol%.

[0158]

[0159] Meanwhile, in another upper and lower separation 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, 40.4 g of the obtained carrier pellets 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 from 1000 mbar to 40 mbar to produce pellets impregnated with ruthenium. The ruthenium-impregnated pellets thus produced and recovered were dried in a general dryer at 110°C for 12 hours, and then charged back into a tubular furnace and reduced at 730°C for 2 hours using 5 vol% hydrogen gas (nitrogen dilution) to obtain 40.8 g (98.0% yield) of a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity.

[0160]

[0161] As a result of ICP analysis of the above-mentioned manufactured catalyst, the impregnation amount of ruthenium (Ru) in the ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity was 0.97 wt%.

[0162]

[0163] ICP analysis for measuring the impregnation amount of lanthanum (La) element in the above carrier and the content of ruthenium (Ru) element in the above catalyst was performed using an inductively coupled plasma atomic emission spectrometer of the iCAP 7400 instrument from Thermo Scientific. For the above measurement, hydrochloric acid was added to each carrier and catalyst of Example 1, and then dissolved using ultrasonic waves and then measured.

[0164]

[0165] ICP analysis for measuring the impregnation amount of lanthanum (La) element in the carriers of Examples 2 to 3 and Comparative Examples 1 to 2 and the inclusion amount of ruthenium (Ru) element in the catalyst was performed using the same method as described above.

[0166]

[0167] <Example 2>

[0168] A carrier was prepared in the same manner as in Example 1, except that 30.66 g (70.8 mmol) of lanthanum nitrate was used, and the ICP analysis result of the prepared carrier showed that the amount of lanthanum (La) impregnated in the carrier was 16.9 mol%.

[0169] Using the above carrier, a ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity was prepared using the same method as the catalyst preparation method of Example 1.

[0170]

[0171] As a result of ICP analysis of the above-mentioned manufactured catalyst, the impregnation amount of ruthenium (Ru) in the ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity was 1.04 wt%.

[0172]

[0173] <Example 3>

[0174] A carrier was prepared in the same manner as in Example 1, except that 31.20 g (72.1 mmol) of lanthanum nitrate was used, and the ICP analysis result of the prepared carrier showed that the amount of lanthanum (La) impregnated in the carrier was 18.2 mol%.

[0175] Using the above carrier, a ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity was prepared using the same method as the catalyst preparation method of Example 1.

[0176]

[0177] As a result of ICP analysis of the above-mentioned manufactured catalyst, the impregnation amount of ruthenium (Ru) in the ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity was 1.01 wt%.

[0178]

[0179] <Comparative Example 1>

[0180] A carrier was prepared in the same manner as in Example 1, except that 22.5 g (52.0 mmol) of lanthanum nitrate was used, and the ICP analysis result of the prepared carrier showed that the impregnation amount of lanthanum (La) in the carrier was 11.9 mol%.

[0181] A ruthenium catalyst for ammonia decomposition reaction was prepared using the same method as the catalyst preparation method of Example 1 using the above carrier.

[0182]

[0183] As a result of ICP analysis of the above-mentioned manufactured catalyst, the impregnation amount of ruthenium (Ru) in the ruthenium catalyst for ammonia decomposition reaction was 0.91 wt%.

[0184]

[0185] <Comparative Example 2>

[0186] A carrier was prepared in the same manner as in Example 1, except that 54.5 g (125.9 mmol) of lanthanum nitrate was used, and the ICP analysis result of the prepared carrier showed that the amount of lanthanum (La) impregnated in the carrier was 20.4 mol%.

[0187] A ruthenium catalyst for ammonia decomposition reaction was prepared using the same method as the catalyst preparation method of Example 1 using the above carrier.

[0188]

[0189] As a result of ICP analysis of the above-mentioned manufactured catalyst, the impregnation amount of ruthenium (Ru) in the ruthenium catalyst for ammonia decomposition reaction was 0.95 wt%.

[0190]

[0191] <BET surface area (m) according to surface area analysis of ruthenium catalyst for ammonia decomposition reaction 2 / g), and total pore volume (cm 3 / g)Features>

[0192] Table 1 below shows the BET surface area (BET surface area, m) according to the surface area analysis of the ruthenium catalysts for ammonia decomposition reaction prepared in Examples 1 to 3 and Comparative Examples 1 to 2. 2 / g), and total pore volume (cm 3 / g) is shown.

[0193]

[0194] 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.

[0195] For the above analysis, the pretreatment of the catalysts manufactured by Examples 1 to 3 and Comparative Examples 1 to 2 was performed under vacuum at 150°C for 4 hours using VacPrep 061, vacuum type.

[0196]

[0197] 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.

[0198] The total pore volume was calculated from the adsorption amount of nitrogen at P / P0 = 0.99.

[0199]

[0200]

[0201]

[0202] As shown in Table 1 above, the BET surface area (m) of Examples 1 to 3, which are ruthenium catalysts for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention, 2 / g) are “92.5, 71.3, and 64.3” respectively, and the BET surface area (m) of the ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention 2 / g) satisfies “50 to 93”.

[0203]

[0204] In contrast, the BET surface area (m) of the ruthenium catalyst for ammonia decomposition reaction according to Comparative Examples 1 and 2, which was outside the range of inclusion of lanthanum (La) in the carrier of the present invention, 2 / g) are “93.5, and 46.9” respectively, which are the BET surface area (m) of the ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention. 2 / g) is going beyond “50 to 93”.

[0205]

[0206] <Measurement of ammonia conversion rate>

[0207] Each ammonia decomposition reaction was performed using the catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 2, and the ammonia conversion rate was measured.

[0208] The above measurements were taken at atmospheric pressure with an ammonia space velocity GHSV of 3,000 ml / (g cat˙ h) Ammonia decomposition ability was measured under the conditions of reaction temperatures of 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).

[0209]

[0210]

[0211]

[0212] As shown in Table 2 above, Examples 1 to 3, which correspond to the ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity of the present invention, show a conversion rate of 93.6% or more at a reaction temperature of 500°C, and even at a reaction temperature of 550°C, both Examples 1 and 2 show a conversion rate of 99.8%, which is close to 100%, and Example 3 also shows a conversion rate of 99.3%, so Examples 1 to 3 show a conversion rate exceeding 99%.

[0213]

[0214] In contrast, Comparative Example 1 shows about 99.0%, but Comparative Example 2 shows 98.6%, indicating a conversion rate of less than 99%.

[0215]

[0216] In addition, even at a reaction temperature of 450°C, Comparative Examples 1 and 2 showed conversion rates of 49.0% and 37.6%, respectively, which are lower than 50%, whereas Examples 1 to 3 showed conversion rates of 65.2%, 69.1%, and 59.0%, respectively, which are about 60% or higher.

[0217]

[0218] The scope of the present invention is not limited to the embodiments described above, but can be implemented in various forms within the scope of the appended claims. Any person skilled in the art, without departing from the spirit of the invention as claimed in the claims, may make various modifications to the invention, which are deemed to fall within the scope of the claims.

[0219]

[0220] 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.

[0221]

[0222] As described above, the catalysts of Examples 1 to 3, which are ruthenium catalysts for ammonia decomposition reaction with excellent ammonia decomposition activity of the present invention, exhibit a conversion rate close to 100% at a reaction temperature of 550°C, and also exhibit a conversion rate of 93.6% or more even at 500°C, and exhibit a conversion rate of about 60% or more even at a low reaction temperature of 450°C, and therefore 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.

Claims

1. A ruthenium catalyst (Ru / LaAlO3) for ammonia decomposition reaction comprising lanthanum aluminate (LaAlO3) of lanthanum-doped alumina as a carrier and ruthenium as an active metal, A ruthenium catalyst for ammonia decomposition reaction, characterized in that lanthanum is contained in 12 mol% to 19 mol% of lanthanum aluminate (LaAlO3), which is a lanthanum-doped alumina as the carrier.

2. In paragraph 1, A ruthenium catalyst for ammonia decomposition reaction, characterized in that the amount of ruthenium in the above ruthenium catalyst for ammonia decomposition reaction (Ru / LaAlO3) is 0.5 wt% to 5 wt%.

3. In paragraph 1, Among the ruthenium catalysts (Ru / LaAlO3) for the above ammonia decomposition reaction, the BET surface area (m) of ruthenium 2 / g) is a ruthenium catalyst for ammonia decomposition reaction, characterized in that it is in the range of "50 to 93" 4. In paragraph 1, A ruthenium catalyst for ammonia decomposition reaction, characterized in that lanthanum is contained in 13 mol% to 19 mol% of lanthanum aluminate (LaAlO3), which is a lanthanum-doped alumina as the carrier.

5. In paragraph 1, A ruthenium catalyst for ammonia decomposition reaction, characterized in that lanthanum is contained in 13 mol% to 18 mol% of lanthanum aluminate (LaAlO3), which is a lanthanum-doped alumina as the carrier. 6.a) a step of preparing a carrier of lanthanum-doped alumina containing lanthanum aluminate (LaAlO3) having a perovskite structure by doping lanthanum into alumina ('first step of preparing lanthanum aluminate carrier'); and b) a step of providing ruthenium to the lanthanum aluminate support to obtain a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity, wherein ruthenium is supported on the lanthanum aluminate ('second step of producing a ruthenium catalyst for ammonia decomposition reaction having excellent ammonia decomposition activity'); The first step in the production of the above lanthanum aluminate carrier is: 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'); 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 iii) a step of drying and calcining the obtained lanthanum-doped alumina to obtain a carrier of lanthanum aluminate ('step 1-3 of obtaining a lanthanum aluminate carrier'); The ratio (parts by weight) of the lanthanum precursor compound:water in the above step 1-1 is 1:2 to 20, The amount of alumina used in the above step 1-2 is 3.5 to 7 times (molar ratio) the amount of lanthanum (lanthanum, La) in the lanthanum precursor compound of the above step 1-1, A method for producing a ruthenium catalyst for ammonia decomposition reaction, characterized in that when the molar ratio of alumina and lanthanum (lanthanum, La) is used as described above, the ratio of the lanthanum (lanthanum, La) is included at 12 mol% to 19 mol% with respect to the lanthanum aluminate carrier obtained in the first to third steps.

7. In paragraph 6, The heating reaction of the above steps 1-2 is at 50°C to 100°C for 1 to 10 hours, A method for producing a ruthenium catalyst for ammonia decomposition reaction, characterized in that the removal of water in the above 1-2 steps is performed 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.

8. In paragraph 6, The drying in steps 1-3 above is carried out at 100°C to 200°C for 1 to 24 hours, Also, a method for producing a ruthenium catalyst for ammonia decomposition reaction, characterized in that the calcination comprises (a) primary calcination at 150°C to 500°C for 5 to 12 hours and (b) secondary calcination at 500°C to 1200°C for 1 to 10 hours.

9. In paragraph 6, The second step of manufacturing a ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity is as follows: i) a step of preparing a ruthenium precursor compound solution by dissolving the ruthenium precursor compound in a mixed solvent of water and alcohol ('Step 2-1 of preparing a ruthenium precursor compound solution'); ii) a step of mixing the lanthanum aluminate carrier prepared in steps 1-3 into the prepared solution and then removing the solvent contained in the solution using a reduced pressure distiller at a constant temperature to prepare ruthenium-doped lanthanum aluminate pellets ('step 2-2 of preparing ruthenium-doped lanthanum aluminate pellets'); and iii) a step of drying and reducing the manufactured ruthenium-doped lanthanum aluminate pellets to obtain a ruthenium catalyst for ammonia decomposition reaction with excellent ammonia decomposition activity supported on lanthanum aluminate ('step 2-3 of obtaining ruthenium catalyst'); The ruthenium precursor compound of the above 2-1 step may be ruthenium chloride, ruthenium nitride, ruthenium acetylacetonate, or ruthenium iodide, The volume ratio of water:alcohol in the above 2-1 step is 1:0.5 to 1.5, A method for producing a ruthenium catalyst for ammonia decomposition reaction, characterized in that the alcohol of the above 2-1 step 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-pentadiol and 1,2-hexadiol.

10. In paragraph 6, The amount of the mixed solution of water and alcohol used in the above step 2-1 is 50 to 200 times (weight ratio) based on 1 part by weight of the ruthenium precursor compound, The melting of the above 2-1 step is carried out at 50℃ to 100℃, The ruthenium precursor compound of the above 2-1 step is used in an amount of 1 to 40 parts by weight based on 100 parts by weight of the lanthanum aluminate carrier, A method for producing a ruthenium catalyst for ammonia decomposition reaction, characterized in that the amount of ruthenium precursor compound for the lanthanum aluminate carrier as described above and ruthenium in the ruthenium catalyst for ammonia decomposition reaction obtained through the drying and reduction of the 2nd and 3rd steps is included in an amount of 0.5 wt% to 5 wt% based on the ruthenium catalyst for ammonia decomposition reaction.

11. In paragraph 6, The temperature of the vacuum distillation unit for solvent removal in the above 2-2 step is 50°C to 150°C, and the solvent removal is carried out slowly over 1 to 5 hours. The drying of the ruthenium-doped lanthanum aluminate pellets in the above 2-3 steps is carried out in a conventional dryer at a temperature of 100°C to 200°C for 5 to 24 hours. The above reduction is performed by filling 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. A method for producing a ruthenium catalyst for ammonia decomposition reaction, characterized in that the hydrogen gas is diluted in an inert gas such as nitrogen at 1 to 20 vol%.

Images