Precursor for preparing ammonia synthesis catalyst, ammonia synthesis catalyst prepared therefrom, and ammonia synthesis method using same

Abstract

A precursor for preparing an ammonia synthesis catalyst, of the present invention, is prepared according to a specific preparation method, and thus the ratio of a specific peak of 0.4 or greater can be satisfied during X-ray diffraction (XRD) analysis, and thus a quaternary catalyst exhibiting high efficiency can be prepared. The ammonia synthesis catalyst prepared from the precursor can have a high ammonia synthesis rate such that ammonia can be prepared with high efficiency even with a small amount of catalyst.

Description

Precursor for manufacturing an ammonia synthesis catalyst, an ammonia synthesis catalyst manufactured therefrom, and a method for synthesizing ammonia using the same

[0001] The present invention relates to a precursor for producing an ammonia synthesis catalyst, a method for producing the same, an ammonia synthesis catalyst produced therefrom, and a method for synthesizing ammonia using the same.

[0002] Ammonia is recognized as a crucial medium for providing a stable food supply for humanity and is considered a promising source of future energy. Currently, renewable energy via electricity is difficult to transport and store, so research is underway to convert hydrogen generated from solar and wind energy into ammonia. This method is expected to provide a renewable energy solution, enabling easy transport and storage similar to petroleum products.

[0003] In particular, ammonia has a density 1.5 times that of liquid hydrogen, making it possible to build infrastructure with relatively high density and low cost. This allows ammonia to have a relatively low manufacturing cost. Furthermore, the existing ammonia supply chain can be utilized to supply hydrogen, and it can be used directly as energy in the power generation sector without the need for dehydrogenation to extract hydrogen. Therefore, efficiently controlling ammonia synthesis and decomposition reactions can accelerate the era of carbon-free energy.

[0004] However, conventional ammonia synthesis relies on the Haber-Bosch process, which requires high temperatures and pressures, resulting in extremely high energy consumption. While new processes, such as electrochemical processes, are being proposed for lower costs and greater energy efficiency, research is needed to effectively utilize existing process equipment to improve energy efficiency. This approach involves novel catalyst-based methods for synthesizing ammonia at low temperatures (below 500°C) and pressures (1 to 100 bar). To achieve this, the development of catalysts with high production efficiency is essential.

[0005] Representative active metals known for ammonia synthesis or decomposition include iron (Fe) and ruthenium (Ru), but they have not yet produced satisfactory results. In addition, ruthenium has the problem of low commerciality due to its high cost, so there is an urgent need to develop a catalyst that is more economical and efficient than the existing one.

[0006] The purpose of the present invention to solve the conventional problems is to provide a precursor for manufacturing an ammonia synthesis catalyst comprising three or more components with excellent compatibility.

[0007] In addition, another object of the present invention is to provide a method for producing a precursor for producing an ammonia synthesis catalyst, in which the catalyst can be uniformly produced with a specific bonding structure having high efficiency.

[0008] In addition, another object of the present invention is to provide an ammonia synthesis catalyst having high ammonia synthesis efficiency and a low-temperature, low-pressure ammonia synthesis method using the same.

[0009] The present inventors have continuously conducted research to achieve the above-described purpose, and as a result, they have discovered that when specific metal precursors are added in a specific order and at a specific molar ratio in the process of manufacturing an ammonia synthesis catalyst based on nitrides of three or more components, a structure having high ammonia synthesis efficiency rather than a structure having low ammonia synthesis efficiency is uniformly formed, and this characteristic can be confirmed by X-ray diffraction (XRD) analysis results that the higher the ratio of specific peak intensities, the more uniformly a structure having high ammonia synthesis efficiency is formed, thereby completing the present invention.

[0010] The present invention contains molybdenum (Mo), cobalt (Co) and iron (Fe), and as a result of X-ray diffraction (XRD) analysis, the fourth peak intensity (I) at 2θ = 28.5 ± 0.2° 28.5° ) for the third peak intensity (I) at 2θ=26.5±0.2° 26.5° ) of the rain (I 26.5° / I 28.5° ) provides a precursor for manufacturing an ammonia synthesis catalyst having a molecular weight of 0.4 or higher.

[0011] According to one embodiment of the present invention, the precursor is (Co 1-x Fe x )Mo1O4(0 <x<1)로 표시되는 것일 수 있다.

[0012] According to one embodiment of the present invention, x may be 0.05 to 0.1.

[0013] According to one embodiment of the present invention, the precursor further comprises cesium (Cs), (Co 1-x Fe x Cs z )Mo1O4(0 <x<1, 0.01≤z≤0.1)로 표시되는 것일 수 있다.

[0014] According to one embodiment of the present invention, z / x may be 0.3 to 0.6.

[0015] According to one embodiment of the present invention, the X-ray diffraction (XRD) analysis result of the precursor for preparing the ammonia synthesis catalyst may show a first peak at 2θ=14.5±0.2°, a second peak at 2θ=25.5±0.2°, a fifth peak at 2θ=32.7±0.2°, and a sixth peak at 2θ=44.0±0.2°.

[0016] The present invention can provide an ammonia synthesis catalyst manufactured from the precursor for manufacturing the ammonia synthesis catalyst described above.

[0017] According to one embodiment of the present invention, the catalyst is (Co 1-x Fe x )Mo1N y (0 <x<1, 0.2<y<0.4)로 표시될 수 있다.

[0018] According to one embodiment of the present invention, the catalyst is (Co 1-x Fe x Cs z )Mo1N y (0 <x<1, 0.2<y<0.4, 0.01≤z≤0.1)로 표시될 수 있다.

[0019] According to one embodiment of the present invention, the X-ray diffraction (XRD) analysis result of the catalyst may show a first peak at 2θ=32.5±0.2°, a second peak at 2θ=35.5±0.2°, a third peak at 2θ=40.0±0.2°, a fourth peak at 2θ=42.5±0.2°, and a fifth peak at 2θ=47.0±0.2°.

[0020] The present invention provides a method for producing an ammonia synthesis catalyst, comprising: (A) a step of producing a precursor for producing an ammonia synthesis catalyst; and (B) an ammonolysis step of heat-treating the precursor for producing an ammonia synthesis catalyst in an ammonia atmosphere.

[0021] According to one embodiment of the present invention, the step (A) may include: (S1) a step of introducing a molybdenum precursor and a cobalt precursor; (S2) a step of introducing a C3-10 organic acid; and (S3) a step of introducing an iron precursor.

[0022] According to one embodiment of the present invention, the step (S4) of adding a polyalcohol may be further included after the step (S3).

[0023] According to one embodiment of the present invention, the molar ratio of the polyhydric alcohol to the organic acid may be 0.1 to 2.0.

[0024] According to one embodiment of the present invention, the step (S3) may be performed by a co-precipitation method.

[0025] According to one embodiment of the present invention, the step (S3-1) of introducing a cesium (Cs) precursor may be further included after the step (S3).

[0026] According to one embodiment of the present invention, the step (S3-1) can be performed by a co-precipitation method.

[0027] According to one embodiment of the present invention, the step (A) may further perform a drying and calcination step (S5) to manufacture a precursor for manufacturing an ammonia synthesis catalyst.

[0028] According to one embodiment of the present invention, the step (B) may be a step of performing an ammonolysis reaction on the precursor for preparing the ammonia synthesis catalyst at a temperature of 600 to 900°C in an ammonia atmosphere to prepare the ammonia synthesis catalyst.

[0029] The present invention can provide an ammonia synthesis method using the ammonia synthesis catalyst described above.

[0030] According to one embodiment of the present invention, the ammonia synthesis method may be performed under a temperature condition of 500°C or less.

[0031] According to one embodiment of the present invention, the ammonia synthesis method may be performed under a pressure condition of 50 bar or less.

[0032] According to one embodiment of the present invention, the ammonia synthesis rate is 10 mmol / g cat It can be more than h.

[0033] The precursor for manufacturing an ammonia synthesis catalyst of the present invention is manufactured according to a specific manufacturing method, so that the ratio of a specific peak in X-ray diffraction (XRD) analysis can be satisfied to be 0.4 or more, and thus a four-component catalyst exhibiting high efficiency can be manufactured. The ammonia synthesis catalyst manufactured from the precursor can have a fast ammonia synthesis rate, and thus ammonia can be manufactured with high efficiency even with a small amount of catalyst.

[0034] Figure 1 shows the results of X-ray diffraction (XRD) analysis of precursors manufactured according to Manufacturing Examples 1 and 3 to 7.

[0035] Figure 2 shows the results of X-ray diffraction (XRD) analysis of ammonia synthesis catalysts manufactured according to Examples 1 and 8 to 10.

[0036] Figure 3 is a schematic diagram illustrating the esterification reaction between an organic acid and a polyhydric alcohol.

[0037] The present invention will be described in more detail below through specific examples or embodiments, including the attached drawings. However, the following specific examples or embodiments are merely references for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

[0038] Additionally, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0039] Additionally, the singular forms used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly dictates otherwise.

[0040] In addition, units used in this specification without special mention are based on weight, and for example, units of % or ratio mean weight% or weight ratio, and weight% means the weight% that any one component of the entire composition occupies in the composition unless otherwise defined.

[0041] Additionally, when a part in this specification is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless specifically stated otherwise.

[0042] Additionally, the numerical ranges used herein may include lower and upper limits and all values ​​within that range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of upper and lower limits of numerical ranges defined in different shapes. Unless otherwise specifically defined in the present specification, values ​​outside the numerical range that may arise due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0043] Hereinafter, a precursor for manufacturing an ammonia synthesis catalyst according to one embodiment of the present invention and a method for manufacturing the same, and an ammonia synthesis catalyst manufactured therefrom and a method for manufacturing the same will be described in more detail.

[0044] The present invention provides a precursor for preparing an ammonia synthesis catalyst containing molybdenum (Mo), cobalt (Co), and iron (Fe). In this case, the precursor is an oxide for preparing an ammonia synthesis catalyst, which will be described later, and the precursor according to one embodiment exhibits characteristics that are different from those of the prior art in the X-ray diffraction (XRD) analysis results of the oxide. As a result of the X-ray diffraction (XRD) analysis, the precursor exhibits a fourth peak intensity (I) at 2θ=28.5±0.2°. 28.5° ) for the third peak intensity (I) at 2θ=26.5±0.2° 26.5° ) of the rain (I 26.5° / I 28.5° ) may be 0.4 or more, 0.5 or more, or 0.6 or more, and the upper limit is not particularly limited, but may be 5.0 or less. In the case of a precursor satisfying the above range, an ammonia synthesis catalyst having the properties targeted in the present invention can be manufactured. In the case of a precursor satisfying the above range, in particular, I 26.5° / I 28.5° If it is less than 0.4, it is not preferable because the properties aimed at in the present invention cannot be achieved.

[0045] According to one embodiment of the present invention, the X-ray diffraction (XRD) analysis result of the precursor, referring to FIG. 1, may exhibit a first peak at 2θ=14.5±0.2°, a second peak at 2θ=25.5±0.2°, a third peak at 2θ=26.5±0.2°, a fourth peak at 2θ=28.5±0.2°, a fifth peak at 2θ=32.7±0.2°, and a sixth peak at 2θ=44.0±0.2°.

[0046] When manufacturing precursors using conventional technology, structures (Co) are formed at specific ratios rather than being synthesized according to the input ratio. 0.7 Fe 0.3Mo1O4) is formed, which has a low ammonia synthesis efficiency, so it is desirable to minimize the formation of the structure. At the same time, in order to manufacture the catalyst targeted in the present invention, it is desirable to introduce Fe while maintaining the CoMoO4 structure, so that a precursor formed at the introduced ratio can be obtained. Here, Co 0.7 Fe 0.3 The representative peak corresponding to Mo1O4 is the fourth peak, and the peak corresponding to CoMoO4 is the third peak, and therefore, Co 0.7 Fe 0.3 I which stands for Mo1O4 28.5° The lower the peak intensity, the more I indicates CoMoO4. 26.5° The higher the peak intensity, the more desirable it is. In particular, as in the present invention, the fourth peak intensity (I 28.5° ) for the third peak intensity (I 26.5° ) of the rain (I 26.5° / I 28.5° ) When a catalyst is manufactured with a precursor satisfying a specific range, the effect of significantly improving ammonia synthesis efficiency can be realized.

[0047] According to one embodiment of the present invention, the precursor is (Co 1-x Fe x )Mo1O4(0 <x<1)로 표시되는 것일 수 있다. 이때 x는 0.01 내지 2.0, 0.01 내지 1.5, 0.05 내지 0.2 또는 0.06 내지 0.12일 수 있다. 상기 만족하는 전구체로 촉매를 제조한 경우, 우수한 암모니아 합성 속도 향상의 효과를 구현할 수 있다. 또한 후술하는 전구체의 제조방법에 있어서, 상기 1-x는 투입하는 코발트 전구체의 몰비, x는 투입하는 철 전구체의 몰비와 동등유사할 수 있다.

[0048] According to one embodiment of the present invention, the precursor further comprises cesium (Cs), (Co 1-x Fe x Cs z)Mo1O4(0 <x<1, 0.01≤z≤0.1)로 표시되는 것일 수 있다. 이때, z / x는 0.1 내지 1.1, 0.2 내지 0.8, 또는 0.3 내지 0.6일 수 있다. 상기 만족하는 전구체로 촉매를 제조한 경우, 우수한 암모니아 합성 속도 향상의 효과를 구현할 수 있다. 또한 후술하는 전구체의 제조방법에 있어서, 상기 1-x는 투입하는 코발트 전구체의 몰비, x는 투입하는 철 전구체의 몰비, z는 투입하는 세슘 전구체의 몰비와 동등유사할 수 있다.

[0049] The present invention can provide an ammonia synthesis catalyst manufactured from the precursor for manufacturing the ammonia synthesis catalyst described above. The ammonia synthesis catalyst can be manufactured as a nitride-based catalyst by calcining the oxide precursor described above. The calcination method can utilize any conventional technology or known method without limitation.

[0050] According to one embodiment of the present invention, the catalyst is a nitride-based ternary quaternary catalyst containing molybdenum (Mo), cobalt (Co) and iron (Fe), (Co 1-x Fe x )Mo1N y (0 <x<1, 0.2<y<0.4)로 표시될 수 있다. 이때 x는 상술한 전구체와 동일하므로 생략한다.

[0051] According to one embodiment of the present invention, the catalyst is a nitride-based four-component catalyst containing molybdenum (Mo), cobalt (Co), iron (Fe), and cesium (Cs), (Co 1-x Fe x Cs z )Mo1N y (0 <x<1, 0.2<y<0.4, 0.01≤z≤0.1)로 표시될 수 있다. 이때 x 및 y는 상술한 세슘 함유 전구체와 동일하므로 생략한다.

[0052] According to one embodiment of the present invention, the X-ray diffraction (XRD) analysis result may show a first peak at 2θ=32.5±0.2°, a second peak at 2θ=35.5±0.2°, a third peak at 2θ=40.0±0.2°, a fourth peak at 2θ=42.5±0.2°, and a fifth peak at 2θ=47.0±0.2°. In addition, each peak represents the crystal of the catalyst, as shown in Fig. 2, the first peak at 2θ = 32.5 ± 0.2° represents (004), the second peak at 2θ = 35.5 ± 0.2° represents (133), the third peak at 2θ = 40.0 ± 0.2° represents (224), the fourth peak at 2θ = 42.5 ± 0.2° represents (115), and the fifth peak at 2θ = 47.0 ± 0.2° represents (044). In addition, when the catalyst is not formed into the desired structure, for example, Fe is Co1Mo1N 0.33 In cases where it does not co-precipitate and floats on the surface, a peak indicating (110) may be seen at 2θ=44.5±0.2°, and this may not be preferred.

[0053]

[0054] Hereinafter, the precursor for manufacturing the above-described ammonia synthesis catalyst and the method for manufacturing the ammonia synthesis catalyst using the same will be described in detail.

[0055] The present invention provides a method for preparing an ammonia synthesis catalyst, comprising: (A) a step of preparing a precursor for preparing an ammonia synthesis catalyst; and (B) an ammonolysis step of heat-treating the precursor for preparing an ammonia synthesis catalyst in an ammonia atmosphere. Here, descriptions of the precursor for preparing an ammonia synthesis catalyst and the ammonia synthesis catalyst are the same as those described above, and thus are omitted.

[0056] According to one embodiment of the present invention, the step of preparing the precursor for preparing the ammonia synthesis catalyst (A) may include a step of sequentially introducing metal precursors and drying and calcining them.

[0057] According to one embodiment of the present invention, the step (A) may include: (S1) a step of introducing a molybdenum precursor and a cobalt precursor; (S2) a step of introducing an organic acid; and (S3) a step of introducing an iron precursor.

[0058] In the above step (S1), the molybdenum precursor and the cobalt precursor can be sequentially added to the solvent, and at this time, it is preferable to add and dissolve the cobalt precursor after the molybdenum precursor is completely dissolved.

[0059] The above molybdenum precursors include, but are not limited to, Na2MoO4·H2O, (NH4)2MoO4·4H2O and (NH4)6Mo7O. 24 ·It may be at least one selected from the group consisting of 4H2O, etc.

[0060] The above cobalt precursors include, but are not limited to, CoCl2, CoCl2·6H2O, CoCl2·xH2O, [Co(NH3)6]Cl. - , Co(NO3)2·6H2O, and Co(CH3COO)2·4H2O.

[0061] According to one embodiment of the present invention, 50 to 100 moles, 70 to 99 moles, or 90 to 95 moles of the cobalt precursor may be introduced for 100 moles of the molybdenum precursor.

[0062] It is preferable that the step of adding the organic acid (S2) above be performed after the cobalt precursor is completely dissolved, and in particular, if the organic acid is added after the iron precursor is added as in the past, the physical properties targeted by the present invention cannot be achieved, which is not preferable.

[0063] The organic acid may be a C3-10 organic acid or chelating agent, or a C5-7 organic acid or chelating agent, and may be at least one selected from the group consisting of, but not limited to, adipic acid, citric acid, glutaric acid, tartaric acid, malic acid, fumaric acid, adipic acid, succinic acid, sucrose, oxalic acid, ethylenediaminetetraacetic acid (EDTA), hydroxyethanediphosphonic acid (HEDP), and the like.

[0064] According to one embodiment of the present invention, the organic acid may be added in an amount of 50 to 150 moles, 70 to 120 moles, or 90 to 105 moles per 100 moles of the sum of the molybdenum precursor, the cobalt precursor, and the iron precursor.

[0065] In the step of introducing the iron precursor (S3), it is preferable to introduce the iron precursor and stir and dissolve it after completely dissolving the organic acid, which is the previous step.

[0066] The above iron precursor may be, for non-limiting examples, at least one selected from the group consisting of FeCl3, FeCl2, Fe(NO3)3·9H2O, FeCl3·6H2O, and FeCl2·4H2O.

[0067] According to one embodiment of the present invention, 0.5 to 30 moles, 1 to 15 moles, or 5 to 10 moles of iron precursor may be added per 100 moles of the molybdenum precursor.

[0068] In the above steps (S1) to (S3), the solvent may include distilled water, and the dissolution temperature may be room temperature, 10 to 50°C, or 20 to 40°C. In addition, the stirring speed (rpm) is not significantly limited as long as the mixture in the container does not overflow and the entire mixture can be properly mixed.

[0069] According to one embodiment of the present invention, the step (S3) may be performed by a conventional or known co-precipitation method. By performing up to step (S3), a solution in which a cobalt precursor, a molybdenum precursor, a citric acid, and an iron precursor are sequentially added is heated to a temperature of 60°C or higher, 60 to 180°C, or 100 to 160°C to evaporate the solvent while inducing precipitation of the above-described metal salts, thereby manufacturing a precursor for manufacturing an ammonia synthesis catalyst.

[0070] According to another embodiment of the present invention, the step (S3-1) of introducing a cesium (Cs) precursor may be further included after the step (S3). It is preferable that the step (S3-1) introduce the cesium precursor and stir and dissolve it after the iron precursor in the previous step has been completely dissolved in the solvent.

[0071] The above cesium precursor may be, for non-limiting examples, at least one selected from the group consisting of CsCl, CsNO3, and CH3COOCs.

[0072] According to one embodiment of the present invention, the cesium precursor may be introduced in an amount of 0.5 to 30 moles, 1 to 15 moles, or 5 to 10 moles per 100 moles of the molybdenum precursor. Alternatively, the cesium precursor may be introduced in an amount of 10 to 110 moles, 20 to 80 moles, or 30 to 60 moles per 100 moles of the iron precursor.

[0073] According to another embodiment of the present invention, the step (S3-1) may be performed by a co-precipitation method described in a conventional or known method. The precursor for preparing an ammonia synthesis catalyst may be prepared by using a co-precipitation method in which a solution in which a cobalt precursor, a molybdenum precursor, a citric acid, an iron precursor, and a cesium precursor are sequentially added is heated to a temperature of 60°C or higher, 60 to 180°C, or 100 to 160°C to evaporate the solvent while inducing precipitation of the above-described metal salts by performing up to step (S3-1).

[0074] According to another embodiment of the present invention, a step (S4) of introducing a polyhydric alcohol may be further included after step (S3). It is preferable to introduce the polyhydric alcohol and stir and dissolve it after the iron precursor has been completely dissolved in the solvent in step (S3). In particular, as shown in FIG. 3, when the polyhydric alcohol is heated together with the organic acid described above, the organic acid is organically linked through an esterification reaction, and the polyhydric alcohol binds between the organic acid linked to metal ions such as molybdenum, cobalt, and iron, thereby acting as a binder, thereby further enhancing the bonding strength and durability of the precursor structure in the calcination step described later. The organic acid and the polyhydric alcohol can be polymerized through an esterification reaction, and a precursor including the polymer can have significantly improved structural stability compared to the prior art. If the polyhydric alcohol is not included, the durability of the precursor in the calcination step is insufficient, making it difficult to achieve the properties desired in the present invention, and thus may not be preferred. A catalyst manufactured using the same can exhibit a remarkable effect of improving the ammonia synthesis rate.

[0075] The above polyhydric alcohols can be used without limitation as long as they have two or more or three or more hydroxyl groups, and preferably, polyhydric alcohols having two or three hydroxyl groups can be used. Non-limiting examples thereof include at least one selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,4-butenediol, 1,4-butynediol, 1,5-pentanediol, neopentyl glycol, bis(hydroxymethyl)cyclohexane, 2-methyl-1,3-propanediol, methylpentanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol, polybutylene glycol, polytetrahydrofuran, polycarbonate diol, and polycaprolactone diol.

[0076] According to one embodiment of the present invention, the molar ratio of the polyhydric alcohol of step (S4) to the organic acid of step (S2) may be 0.05 to 5.0, 0.1 to 2.0, 0.3 to 1.5, or 0.8 to 1.3, or the molar ratio may be 0.05 to 5.0, 0.1 to 2.0, 0.3 to 1.5, or 0.8 to 1.3. Alternatively, the polyhydric alcohol of step (S4) may be introduced in an amount of 1 to 100 parts by weight, 5 to 70 parts by weight, or 15 to 50 parts by weight, relative to 100 parts by weight of the organic acid of step (S2). In the case of a precursor manufactured by satisfying the above range, an ammonia synthesis catalyst having an excellent ammonia synthesis rate can be manufactured.

[0077] According to another embodiment of the present invention, after the step (S4), the process may be performed by a coprecipitation method described in a conventional or known method. By performing up to the step (S4), a solution in which a cobalt precursor, a molybdenum precursor, a citric acid, an iron precursor, and a polyhydric alcohol are all sequentially added is heated to a temperature of 60°C or higher, 60 to 180°C, or 100 to 160°C to evaporate the solvent, thereby inducing precipitation of the above-described metal salts, thereby preparing a precursor for preparing an ammonia synthesis catalyst.

[0078] According to another embodiment of the present invention, the method may further include a step of introducing a cesium (Cs) precursor (S3-1) after the step (S3); and a step of introducing a polyhydric alcohol (S4). In the step (S3), it is preferable to introduce the cesium precursor, stir, and dissolve it after the iron precursor, which is the previous step, has been completely dissolved in the solvent, and then introduce the polyhydric alcohol, stir, and dissolve it after the cesium precursor has been completely dissolved in the solvent.

[0079] According to another embodiment of the present invention, after the step (S4), it can be performed by a co-precipitation method described in a conventional or known method. By performing up to step (S4), a solution in which a cobalt precursor, a molybdenum precursor, a citric acid, an iron precursor, a cesium precursor, and a polyhydric alcohol are all sequentially added is heated to a temperature of 60°C or higher, 60 to 180°C, or 100 to 160°C to evaporate the solvent, thereby inducing precipitation of the above-described metal salts, thereby preparing a precursor for preparing an ammonia synthesis catalyst.

[0080] According to one embodiment of the present invention, the step (A) may be to induce precipitation of metal salts using the co-infiltration as described above, and then further perform the drying and calcination step (S5) on the precipitate to manufacture a precursor for manufacturing an ammonia synthesis catalyst. The drying may be performed in a drying oven at a temperature of 100°C or higher, 110 to 200°C, until completely dried, for at least 1 hour, preferably 3 hours, but is not limited thereto. In addition, the calcination step may utilize a conventional or known method, and as a non-limiting example, it may be calcination at a temperature of 500 to 800°C, or 650 to 750°C, for at least 1 hour, or 2 to 4 hours.

[0081] According to one embodiment of the present invention, the step (B) may be a step of performing an ammonolysis reaction on the precursor for preparing the ammonia synthesis catalyst in an ammonia atmosphere at a temperature of 600 to 900°C, or 750 to 850°C, for 10 minutes or more, or 30 minutes to 2 hours, thereby preparing the ammonia synthesis catalyst. The ammonolysis reaction may utilize commonly used or known conditions without limitation.

[0082]

[0083] Hereinafter, a method for synthesizing ammonia using an ammonia synthesis catalyst according to one embodiment of the present invention will be described in more detail.

[0084] The present invention can provide an ammonia synthesis method using the ammonia synthesis catalyst described above. When synthesizing ammonia using the ammonia synthesis catalyst described above, the ammonia synthesis rate is significantly improved compared to the amount of catalyst used, thereby achieving the effect of high ammonia synthesis efficiency.

[0085] According to one embodiment of the present invention, the ammonia synthesis catalyst may further include a conventional or known support. The support may be any material capable of supporting or supporting an active metal, and may include, for example, one or more selected from cerium oxide, titanium oxide, vanadium oxide, zirconium oxide, zinc oxide, lanthanum oxide, magnesium oxide, silicon oxide, aluminum oxide, zeolite, and activated carbon.

[0086] According to one embodiment of the present invention, the ammonia synthesis catalyst may further include a cocatalyst, and the cocatalyst may include one or two or more of an alkali metal and an alkaline earth metal (barium, cesium, rubidium, strontium, potassium, calcium, sodium, etc.).

[0087] According to one embodiment of the present invention, the ammonia synthesis method can be performed at a lower temperature and pressure than conventional techniques, and specifically, can be performed under temperature conditions of 500°C or less, 250 to 500°C, 250 to 450°C, or 300 to 410°C, and pressure conditions of 50 bar or less, 1 to 30 bar, 1 to 20 bar, or 2 to 11 bar.

[0088] According to one embodiment of the present invention, the ammonia synthesis rate is 7 mmol / g cat .h or more, 10 mmol / g cat.h or more, 12 mmol / g cat .h or more, or the upper limit is not limited, but 100 mol / g cat It can be .h or less.

[0089] The present invention will be described in more detail based on the following examples and comparative examples. However, the following examples and comparative examples are merely illustrative examples for further explaining the present invention, and the present invention is not limited by the following examples and comparative examples.

[0090] [Physical property evaluation method]

[0091] 1) X-ray diffraction (XRD) analysis

[0092] The precursor or catalyst was analyzed under the following conditions using an XRD analysis instrument (X-ray Diffractometer) (PANalytical, EMPYREAN).

[0093] - Light source (X-ray source): Cu-Kα radiation

[0094] - Power: 40 KV x 30mA

[0095] - Mode: Continuous scan mode

[0096] - Scan angle range: 10~50°

[0097] - Scan speed: 5° / min

[0098]

[0099] [Manufacturing Example 1]

[0100] Ammonium molybdate hydrate ((NH4)6Mo7O) as a precursor in 250 mL of distilled water 24·4H2O) 3.7 g (3.0 mmol), cobalt nitrate hydrate (Co(NO3)2ㆍ6H2O) 4.7 g (16 mmol), citric acid 7.3 g (30 mmol), and iron nitrate hydrate (Fe(NO3)3ㆍ9H2O) 0.53 g (1.3 mmol) were sequentially added and stirred, and then ethylene glycol 2.0 mL (30 mmol) was added last. At this time, the molar ratio of ethylene glycol to the added citric acid satisfied 1.0.

[0101] Afterwards, the mixture was heated in a temperature range of 60 to 90°C to evaporate the distilled water and stirred until the mixture began to swell in a sponge shape. When the mixture began to swell, the beaker was transferred to an oven and dried at 150°C for more than 6 hours. After drying was completed, the sponge-shaped dried product was ground into powder, and the temperature was increased at 5°C per minute to 700°C in an air atmosphere and then calcined for 3 hours, thereby finally producing a precursor for preparing an ammonia synthesis catalyst [(Co 1-x Fe x )Mo1O4(x=0.075)] was obtained.

[0102] The X-ray diffraction (XRD) analysis graph of the precursor for manufacturing the manufactured ammonia synthesis catalyst is shown in Fig. 1, and the peak intensity (I) at 2θ = 28.5 ± 0.2° is shown in Table 1 below. 28.5° ) for the peak intensity (I) at 2θ=26.5±0.2° 26.5° ) of the rain (I 26.5° / I 28.5° ) The calculated values ​​are recorded.

[0103] [Manufacturing Example 2]

[0104] The same procedure as in Manufacturing Example 1 was followed, except that iron nitrate hydrate was not added. The X-ray diffraction (XRD) analysis graph of the precursor for manufacturing the ammonia synthesis catalyst is shown in Figure 1, and Table 1 below shows the results. 26.5° / I 28.5° The calculated values ​​are listed.

[0105] [Manufacturing Example 3]

[0106] The same procedure as in Manufacturing Example 1 was followed, except that the order of citric acid and iron nitrate hydrate was reversed. The X-ray diffraction (XRD) analysis graph of the precursor for manufacturing the ammonia synthesis catalyst is shown in Figure 1, and Table 1 below shows the XRD pattern. 26.5° / I 28.5° The calculated values ​​are listed.

[0107] [Manufacturing Example 4]

[0108] The same procedure as in Manufacturing Example 1 was followed, except that citric acid was added first. The X-ray diffraction (XRD) analysis graph of the precursor for manufacturing the ammonia synthesis catalyst is shown in Figure 1, and Table 1 below shows the results. 26.5° / I 28.5° The calculated values ​​are listed.

[0109] [Manufacturing Example 5]

[0110] The same procedure as in Manufacturing Example 4 was followed, except that ammonium molybdate hydrate was added a second time. The X-ray diffraction (XRD) analysis graph of the precursor for preparing the ammonia synthesis catalyst is shown in Fig. 1, and Table 1 below shows the XRD pattern. 26.5° / I 28.5° The calculated values ​​are listed.

[0111] [Manufacturing Example 6]

[0112] The same procedure as in Manufacturing Example 1 was followed, except that iron nitrate hydrate was added first. The X-ray diffraction (XRD) analysis graph of the precursor for manufacturing the ammonia synthesis catalyst is shown in Figure 1, and Table 1 below shows the results. 26.5° / I 28.5° The calculated values ​​are listed.

[0113] [Manufacturing Example 7]

[0114] The same procedure as in Manufacturing Example 6 was followed, except that the order of citric acid and cobalt nitrate hydrate was reversed. The X-ray diffraction (XRD) analysis graph of the precursor for manufacturing the ammonia synthesis catalyst is shown in Figure 1, and Table 1 below shows the XRD pattern. 26.5° / I 28.5° The calculated values ​​are listed.

[0115] [Manufacturing Example 8]

[0116] The same procedure as in Manufacturing Example 1 was followed, except that 0.35 g of iron nitrate hydrate and 4.83 g of cobalt nitrate hydrate were added, to finally prepare a precursor for preparing an ammonia synthesis catalyst [(Co 1-x Fe x )Mo1O4(x=0.05)] was obtained.

[0117] [Manufacturing Example 9]

[0118] The same procedure as in Manufacturing Example 1 was followed, except that 0.71 g of iron nitrate hydrate and 4.58 g of cobalt nitrate hydrate were added, to finally prepare a precursor for preparing an ammonia synthesis catalyst [(Co 1-x Fe x )Mo1O4(x=0.1)] was obtained.

[0119] [Manufacturing Example 10]

[0120] The same procedure as in Manufacturing Example 1 was followed, except that 0.88 g of iron nitrate hydrate and 4.45 g of cobalt nitrate hydrate were added, to finally prepare a precursor for preparing an ammonia synthesis catalyst [(Co 1-x Fe x )Mo1O4(x=0.125)] was obtained.

[0121] [Manufacturing Example 11]

[0122] Ammonium molybdate hydrate ((NH4)6Mo7O) as a precursor in 250 mL of distilled water 24·4H2O) 3.69 g (3.0 mmol), cobalt nitrate hydrate (Co(NO3)2ㆍ6H2O) 4.96 g (17 mmol), citric acid 7.3 g (30 mmol), iron nitrate hydrate (Fe(NO3)3ㆍ9H2O) 0.88 g (2 mmol), and cesium nitrate (CsNO3) 0.17 g (0.9 mmol) were sequentially added and stirred, and then ethylene glycol 2.0 mL (30 mmol) was added last, and the same procedure as in Manufacturing Example 1 was performed according to the co-precipitation method, thereby finally producing a precursor for preparing an ammonia synthesis catalyst [(Co 1-x Fe x Cs z )Mo1O4(x=0.075, z=0.03)] was obtained.

[0123] [Manufacturing Example 12]

[0124] The same procedure as in Manufacturing Example 1 was followed, except that ethylene glycol was not added.

[0125] [Manufacturing Example 13]

[0126] The same procedure as in Manufacturing Example 1 was followed, except that 1.0 mL (15 mmol) of ethylene glycol was added. At this time, the molar ratio of ethylene glycol to the added citric acid satisfied 0.5.

[0127] [Manufacturing Example 14]

[0128] The same procedure as in Manufacturing Example 1 was followed, except that 4 mL (60 mmol) of ethylene glycol was added. At this time, the molar ratio of ethylene glycol to citric acid added satisfied 2.0.

[0129]

[0130] [Examples and Comparative Examples]

[0131] The precursors for preparing an ammonia synthesis catalyst prepared in the above Preparation Examples 1 to 14 were heated at a rate of 10°C per minute to a temperature of 800°C in an ammonia atmosphere in a kiln and then maintained for 2 hours to prepare an ammonia synthesis catalyst ((Co) according to Examples and Comparative Examples. 1-x Fe x )Mo1N 0.33 or Co 1-x Fe x Cs z )Mo1N 0.33 (At this time, x and z are independently identical to the corresponding precursors)) were manufactured, and the results of evaluating the ammonia synthesis efficiency were recorded in Tables 1 to 3 below.

[0132] The X-ray diffraction (XRD) analysis graphs of the ammonia synthesis catalysts of Examples 1 and 8 to 10 are shown in FIG. 2.

[0133]

[0134] [Evaluation Example] Ammonia Synthesis Efficiency Evaluation

[0135] A fixed-bed reactor was charged with 0.05 g of the manufactured ammonia synthesis catalyst and 0.2 g of SiC as an inert material. To activate the catalyst surface, nitrogen and hydrogen were injected at a flow rate of 15 mL / min and 45 mL / min, respectively, and the temperature was increased from atmospheric pressure to 700°C at a rate of 5°C / min and maintained for 1 hour. Then, while maintaining the flow rates of nitrogen and hydrogen, the temperature was cooled to 400°C, and the reactor was pressurized to 10 bar to synthesize ammonia for 2 hours. The amount of synthesized ammonia was confirmed by neutralization in a 0.3 mM sulfuric acid solution, and the degree of neutralization of the sulfuric acid solution was confirmed by real-time measurement of the conductivity value of a pH meter.

[0136] Referring to non-patent literature SE Sivan et al., J. Catal. 408 (2022) 316-328, the mole fraction (MF) and synthesis rate of the produced ammonia were calculated according to Equations 1 and 2 below. In Equation 1 below, M NH3is the number of moles of synthesized ammonia, and M N2 is the number of moles of unreacted nitrogen, and M H2 is the number of moles of unreacted hydrogen.

[0137] [Formula 1]

[0138] Ammonia mole fraction (MF)(%)={M NH3 / (M NH3 +M N2 +M H2 )}Х100

[0139] [Formula 2]

[0140] Ammonia synthesis rate (mmol / g) cat .h)={ammonia mole fraction (MF) Х60 / {(1+MF)Хcatalyst mass (g) cat )Х22.08}}Х100

[0141]

[0142] Table 1 below compares the ammonia synthesis rate according to changes in the order of raw material input.

[0143] Precursor used I 26.5° / I 28.5° Ammonia synthesis rate [mmol / g cat .h]Comparative Example 1 Manufacturing Example 2-5.06Comparative Example 2 Manufacturing Example 30.215.41Comparative Example 3 Manufacturing Example 40.195.34Comparative Example 4 Manufacturing Example 50.235.64Comparative Example 5 Manufacturing Example 60.276.09Comparative Example 6 Manufacturing Example 70.326.31Example 1 Manufacturing Example 10.6610.6

[0144] As shown in Table 1 above, when the precursors are manufactured in the order of introduction in Example 1, I 26.5° / I 28.5° It was confirmed that a very excellent ammonia synthesis rate was shown as the value was 0.4 or higher, and preferably 0.6 or higher. Specifically, when manufacturing the precursor, it was not synthesized according to the input ratio, but a structure (Co) composed of a specific ratio 0.7 Fe 0.3The formation of Mo1O4) is desirable to minimize because it has the problem of low ammonia synthesis efficiency. Therefore, in one embodiment, by adopting an injection order that can solve this problem, it is possible to manufacture a precursor having a structure in which Fe is introduced while maintaining the CoMoO4 structure while suppressing the formation of a specific structure that causes low efficiency.

[0145] Referring to Figure 1, Co 0.7 Fe 0.3 I which stands for Mo1O4 28.5° The lower the peak intensity, the more I indicates CoMoO4. 26.5° The higher the peak intensity, the more desirable it is, i.e., I 26.5° / I 28.5° A precursor having a value of 0.4 or more, preferably 0.6 or more, is highly desirable because it can produce a catalyst having a high ammonia synthesis rate. In all comparative examples except Example 1, I 26.5° / I 28.5° Considering that the value is a low value of less than 0.4, it can be said that a catalyst having an excellent ammonia synthesis rate can be manufactured when the input order according to Manufacturing Example 1 is adopted.

[0146] In particular, in the case of Example 3, in which citric acid was added after all metal precursors were added, or in Examples 4 or 5, in which citric acid was added first, an ammonia synthesis rate that was significantly lower than that of other comparative examples was shown.

[0147]

[0148] In addition, the ammonia synthesis rate according to the change in the molar ratio of iron and cobalt is compared in Table 2 below.

[0149] Precursor used (Co 1-x Fe x )Mo1O4 x ammonia synthesis rate [mmol / g cat.h]Comparative Example 1 Manufacturing Example 2-5.06Embodiment 2 Manufacturing Example 80.056.34Embodiment 1 Manufacturing Example 10.07510.6Embodiment 3 Manufacturing Example 90.18.37Embodiment 4 Manufacturing Example 100.1255.84

[0150] In addition, as a result of comparing the ammonia synthesis rate according to the introduction of cesium, (Co) manufactured according to Manufacturing Example 11 1-x Fe x Cs z ) In Example 5 using the precursor of Mo1O4(x=0.075, z=0.03), the ammonia synthesis rate was 13.58 mmol / g. cat .h, indicating excellent ammonia synthesis efficiency.

[0151]

[0152] Additionally, the ammonia synthesis rate according to the change in ethylene glycol content was compared in Table 3 below.

[0153] Molal ratio of ammonia synthesis rate of ethylene glycol to citric acid as precursor [mmol / g] cat .h]Example 6 Manufacturing Example 120.06.66Example 7 Manufacturing Example 130.58.98Example 1 Manufacturing Example 11.010.6Example 8 Manufacturing Example 142.05.46

[0154] As shown in Table 3 above, it was confirmed that ammonia synthesis rate was superior when the molar ratio of ethylene glycol to citric acid satisfied a specific value. In particular, Examples 1 and 7, in which the molar ratio of ethylene glycol to citric acid was 0.5 to 1.5, exhibited superior values.

[0155] As described above, the present invention has been described through specific matters and limited examples, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on this description.

[0156] Therefore, the idea of ​​the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the claims described below as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

Claims

1. Contains molybdenum (Mo), cobalt (Co) and iron (Fe). As a result of X-ray diffraction (XRD) analysis, the fourth peak intensity (I) at 2θ = 28.5 ± 0.2 ° 28.5° ) for the third peak intensity (I) at 2θ=26.5±0.2° 26.5° ) of the ratio (I 26.5° / I 28.5° ) A precursor for producing an ammonia synthesis catalyst having a molecular weight of 0.4 or higher.

2. In paragraph 1, The above precursor is (Co 1-x Fe x )Mo1O4(0 <x<1)로 표시되는 것인 암모니아 합성 촉매 제조용 전구체.

3. In paragraph 2, A precursor for producing an ammonia synthesis catalyst, wherein the above x is 0.05 to 0.

1.

4. In paragraph 1, The above precursor further includes cesium (Cs), (Co 1-x Fe x Cs z )Mo1O4(0 <x<1, 0.01≤z≤0.1)로 표시되는 것인 암모니아 합성 촉매 제조용 전구체.

5. In paragraph 4, A precursor for preparing an ammonia synthesis catalyst wherein z / x is 0.3 to 0.

6.

6. In paragraph 1, A precursor for producing an ammonia synthesis catalyst, which exhibits a first peak at 2θ=14.5±0.2°, a second peak at 2θ=25.5±0.2°, a fifth peak at 2θ=32.7±0.2°, and a sixth peak at 2θ=44.0±0.2° as a result of X-ray diffraction (XRD) analysis.

7. An ammonia synthesis catalyst manufactured from a precursor for manufacturing an ammonia synthesis catalyst selected from any one of claims 1 to 6.

8. In paragraph 7, The above catalyst is (Co 1-x Fe x )Mo1N y(0 <x<1, 0.2<y<0.4)로 표시되는 암모니아 합성 촉매.

9. In paragraph 7, The above catalyst is (Co 1-x Fe x Cs z )Mo1N y (0 <x<1, 0.2<y<0.4, 0.01≤z≤0.1)로 표시되는 것인 암모니아 합성 촉매.

10. In paragraph 7, An ammonia synthesis catalyst, which, as shown in the results of X-ray diffraction (XRD) analysis, exhibits a first peak at 2θ=32.5±0.2°, a second peak at 2θ=35.5±0.2°, a third peak at 2θ=40.0±0.2°, a fourth peak at 2θ=42.5±0.2°, and a fifth peak at 2θ=47.0±0.2°. 11.(A) A step for preparing a precursor for preparing an ammonia synthesis catalyst; and (B) A method for producing an ammonia synthesis catalyst, comprising an ammonolysis step of heat-treating a precursor for producing the ammonia synthesis catalyst in an ammonia atmosphere.

12. In paragraph 11, The above step (A) (S1) a step of introducing a molybdenum precursor and a cobalt precursor; (S2) Step of adding organic acid of C3-10; and (S3) A method for producing an ammonia synthesis catalyst, comprising: a step of introducing an iron precursor.

13. In paragraph 12, A method for producing an ammonia synthesis catalyst, wherein the molar ratio of the iron precursor to the total moles of the iron precursor and cobalt precursor is 0.05 to 0.

1.

14. In paragraph 12, A method for producing an ammonia synthesis catalyst, further comprising a step of adding a polyhydric alcohol (S4) after the step (S3).

15. In paragraph 14, A method for producing an ammonia synthesis catalyst, wherein the molar ratio of polyhydric alcohol to the organic acid is 0.1 to 2.

0.

16. In paragraph 12, The above step (S3) is a method for producing an ammonia synthesis catalyst performed by a co-precipitation method.

17. In paragraph 12, A method for producing an ammonia synthesis catalyst, further comprising a step of introducing a cesium (Cs) precursor (S3-1) after the step (S3).

18. In paragraph 17, A method for producing an ammonia synthesis catalyst, wherein the molar ratio of the cesium precursor to the total moles of the iron precursor and the cesium precursor is 0.05 to 0.

1.

19. In paragraph 17, The above step (S3-1) is a method for producing an ammonia synthesis catalyst performed by a co-precipitation method.

20. In paragraph 11, A method for producing an ammonia synthesis catalyst, wherein the step (A) is further performed by performing a drying and calcination step (S5) at the end to produce a precursor for producing an ammonia synthesis catalyst.

21. In paragraph 11, The above step (B) is a method for producing an ammonia synthesis catalyst, wherein the step comprises performing an ammonolysis reaction on the precursor for producing the ammonia synthesis catalyst in an ammonia atmosphere at a temperature of 600 to 900°C to produce an ammonia synthesis catalyst.

22. A method for synthesizing ammonia using the ammonia synthesis catalyst of Article 7.

23. In paragraph 22, A method for synthesizing ammonia, which is performed under temperature conditions of 500℃ or less.

24. In paragraph 22, A method for synthesizing ammonia, which is performed under pressure conditions of 50 bar or less.

25. In paragraph 22, Ammonia synthesis rate is 10 mmol / g cat A method for synthesizing ammonia having a molecular weight of h or higher.

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