Support, method for manufacturing support, and catalyst for ammonia decomposition containing support

Abstract

According to exemplary embodiments of the present invention, a support is provided. The support is a support of a catalyst for ammonia decomposition, and the amount of acid sites of the support, as measured by NH3-temperature programmed desorption (NH3-TPD), is 0.006-0.010 mmol / g. Also, according to other exemplary embodiments of the present invention, provided are a method for manufacturing the support, and a catalyst for ammonia decomposition, comprising the support.

Description

Support, method for producing support, and catalyst for ammonia decomposition comprising support

[0001] The present invention relates to a carrier and a method for producing a carrier.

[0002] In addition, the present invention relates to a catalyst for ammonia decomposition comprising a support.

[0003] To address climate change and various environmental pollution issues, ongoing efforts are underway worldwide to restructure carbon-based energy societies into renewable energy-based ones. However, renewable energy distribution remains skewed across regions and time periods. Therefore, to ensure widespread use, energy storage systems capable of storing large quantities of renewable energy must be utilized, enabling the establishment of inter-national and inter-continental trade systems.

[0004] Hydrogen is a substance capable of stable, large-scale, long-term energy storage. Many countries, including Europe, Japan, Saudi Arabia, and Australia, are working to establish a global renewable energy trading system using hydrogen as a renewable energy storage medium. Meanwhile, the Korean government's roadmap for revitalizing the hydrogen economy has set a goal of increasing domestic hydrogen supply. However, hydrogen has a very low energy density relative to its volume, so research on chemical and physical hydrogen storage methods is essential for economically importing large quantities from overseas. To this end, various hydrogen storage materials, including ammonia (NH3), liquid organic hydrogen compounds (LOHCs), and liquefied hydrogen (LH2), are being actively researched. Ammonia, in particular, is attracting attention as a highly commercially viable hydrogen (renewable energy) storage medium due to its high hydrogen storage capacity (17.6 wt.%, 108 g / L), ease of storage (8.74 kPa, 20°C), and ability to utilize existing ammonia storage and transportation infrastructure.

[0005] A single ammonia molecule consists of three hydrogen atoms and one nitrogen atom. When this ammonia molecule is decomposed at high temperatures, only hydrogen and nitrogen gas, which make up 78% of air, are produced. Ammonia has the advantage of being able to utilize existing infrastructure for large-scale storage and long-distance transportation. Furthermore, since only hydrogen and nitrogen are produced, carbon dioxide emissions are minimized.

[0006] Ammonia decomposition reaction can be carried out at high temperatures according to the following reaction equation.

[0007] 2NH3(g) → N2(g) + 3H2(g)

[0008] Improving catalyst performance is crucial for increasing the efficiency of ammonia decomposition reactions. Attempts have been made to improve catalyst performance by adding promoters, such as rare earth metals. This is because promoters can alter the electronic structure of catalytically active metals, thereby enhancing catalytic performance. However, most of these promoters are expensive or are made of metal elements with limited reserves in specific regions. This has led to difficulties in ensuring a smooth catalyst supply and excessively increasing the cost of the catalyst used when using promoters in large-scale industrial reactors.

[0009] Therefore, it is necessary to develop a technology that improves catalyst performance without adding additives such as accelerators.

[0010] (Patent Document 1) Japanese Patent Publication No. 2023-539511.

[0011] The technical idea of ​​the present invention is to provide a carrier capable of stably supporting active metal particles and a method for manufacturing the same.

[0012] Another object of the present invention is to provide a catalyst for decomposing ammonia comprising a support on which active metal particles are stably bound.

[0013] The objectives of the present invention are not limited to the above-described content. Those skilled in the art will have no difficulty understanding the additional objectives of the present invention from the overall description of the present invention.

[0014] According to exemplary embodiments of the present invention, a support is provided. The support is a support for an ammonia decomposition catalyst, and the acid site amount of the support, as measured by NH3-TPD analysis (NH3-Temperature Programmed Desorption), is 0.006 to 0.010 mmol / g.

[0015] The above-mentioned carrier may include alumina.

[0016] The alumina may include any one of alpha alumina (α-Al2O3), gamma alumina (γ-Al2O3), theta alumina (θ-Al2O3), and combinations thereof.

[0017] The above carrier may be in the form of a pellet.

[0018] According to other exemplary embodiments of the present invention, a method for manufacturing a carrier is provided. The method for manufacturing the carrier comprises the steps of: preparing a carrier; treating the carrier with an acid solution at 85 to 95°C for 30 to 120 minutes; washing the acid-treated carrier; and drying and calcining the washed carrier.

[0019] The above acid solution may be an aqueous solution of any one of hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), hydrofluoric acid (HF), and a combination thereof.

[0020] The molar concentration of the acid in the above acid solution can be 4 to 7 M.

[0021] Drying of the above washed carrier can be performed at 70 to 90°C for 3 to 12 hours.

[0022] The calcination treatment of the above dried carrier can be performed in a dry air atmosphere at 500 to 800°C for 0.5 to 3 hours.

[0023] According to further exemplary embodiments of the present invention, a catalyst for decomposing ammonia is provided. The catalyst for decomposing ammonia comprises at least one of the above-described supports, active metal particles supported on the support, and the active metal comprises at least one of nickel (Ni) and nickel-based alloys.

[0024] According to exemplary embodiments of the present invention, the performance of a catalyst for ammonia decomposition can be improved without adding a separate promoter by increasing the acidity of the support.

[0025] The various advantageous and beneficial effects of the present invention are not limited to the above-described contents, and will be more easily understood in the course of explaining specific embodiments of the present invention.

[0026] Figure 1 is a graph showing the ammonia decomposition efficiency of a catalyst for ammonia decomposition.

[0027] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concepts of terms to best explain his or her invention, they should be interpreted in a way that aligns with the technical spirit of the present invention.

[0028] In addition, when describing embodiments of the present invention with reference to drawings, identical or corresponding components are given the same drawing reference numerals and redundant descriptions thereof are omitted.

[0029] In the examples below, the terms first, second, etc. are not used in a limiting sense, but are used for the purpose of distinguishing one component from another.

[0030] In the examples below, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0031] In the following examples, terms such as “include” or “have” mean that a feature or component described in the specification is present, and do not preclude the possibility that one or more other features or components may be added.

[0032] For convenience of explanation, the sizes of components in the drawings may be exaggerated or reduced. For example, the sizes and thicknesses of each component shown in the drawings are arbitrarily indicated for convenience of explanation, and thus the present invention is not necessarily limited to what is shown.

[0033] In some embodiments, where implementations are otherwise feasible, specific process sequences may be performed in a different order than described. For example, two processes described in succession may be performed substantially simultaneously, or in a reverse order from the described order.

[0034] In addition, when describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description is omitted.

[0035]

[0036] [Catalyst for ammonia decomposition]

[0037] According to exemplary embodiments, a catalyst for ammonia decomposition comprises a support and active metal particles supported on the support.

[0038]

[0039] According to exemplary embodiments, the active metal particles may be one or more of Ni or a Ni-based alloy. However, it should be noted that the active metal particles are not necessarily limited to Ni, and the carrier described below is not necessarily limited to supporting only Ni or a Ni-based alloy.

[0040] Nickel or ruthenium can be used as the active metal particles in ammonia decomposition catalysts. Among these, nickel, a non-precious metal with abundant reserves, has the advantage of being cheaper than ruthenium. Catalysts using nickel as the active metal particles are inexpensive to manufacture, making them suitable for use in large-scale plant facilities.

[0041]

[0042] As an example, the activation temperature of a catalyst for ammonia decomposition may be 500°C or higher.

[0043]

[0044] [Carrier]

[0045] According to exemplary embodiments, the support may include alumina. More specifically, the alumina may include any one of alpha alumina (α-Al2O3), gamma alumina (γ-Al2O3), theta alumina (θ-Al2O3), and combinations thereof. More specifically, the support may include alpha alumina.

[0046] Alumina possesses excellent thermal stability and durability. By utilizing alumina as a support for ammonia decomposition catalysts, the stability of the catalyst can be maintained even under high-temperature reaction conditions. Alpha alumina is most desirable in terms of catalyst thermal stability and durability.

[0047] According to exemplary embodiments, the support may be in pellet form. Pellets are formed by compressing solid particles. This pellet form offers excellent physical durability and can be conveniently handled in both laboratory-scale reactors and commercial plant-scale reactors. Additionally, the differential pressure applied to the catalyst bed in a commercial plant-scale reactor may be lower for pellet catalysts than for powder catalysts. This reduces process issues, such as differential pressure, in various chemical reactions and can result in superior performance. Thus, by using a pellet-shaped support, the ammonia decomposition catalyst can be easily applied to commercial plants.

[0048]

[0049] The acid site amount measured by NH3-TPD analysis (NH3-Temperature Programmed Desorption) of the carrier may be 0.006 to 0.010 mmol / g.

[0050] As the acid site content of the support decreases, the binding force between the active metal particles and the support deteriorates, which can easily cause the active metal particles to detach from the support, and the active metal particles can also clump together, reducing the active area of ​​the catalyst. To prevent this, the acid site content of the support may be 0.006 mmol / g or more. As the acid site content of the support increases, the active metal particles can be bound to and stably exist on the support, and a wider distribution of active metal particles can be supported, which can improve the active area of ​​the ammonia decomposition catalyst. As a result, the performance of the ammonia decomposition catalyst can be improved. However, when the acid site content of the support exceeds 0.010 mmol / g, the acid sites may act as a catalyst, causing unintended side reactions. Furthermore, during the ammonia decomposition reaction, the electronic structure of the active metal particles may be affected, which may actually lower the performance of the catalyst.

[0051]

[0052] [Method for manufacturing a carrier]

[0053] A method for manufacturing a carrier may include a step of preparing a carrier, a step of acid-treating the carrier, a step of washing the carrier, and a step of calcining the carrier.

[0054]

[0055] The step of preparing the carrier may be performed by calcining a precursor of the carrier.

[0056] The conditions for calcining the precursor of the carrier can be performed under conventional conditions known in the art. As an example, the calcination can be performed by heat-treating the precursor of the carrier at a temperature ranging from 400 to 1200°C. More specifically, the calcination can be performed by heat-treating the precursor of the carrier at a temperature ranging from 1000 to 1200°C.

[0057] As a non-limiting example, the precursor of the support may include alumina. The precursor of the support is not particularly limited as long as it is a material that can be calcined to provide the support. As one example, the precursor of the support may be alumina hydrate. More specifically, it may be at least one of alumina trihydrate, alumina monohydrate, or a mixture thereof.

[0058] The alumina trihydrate may be one or more of gibbsite, bayerite, or a mixture thereof. The alumina monohydrate may preferably be boehmite, diaspore, or a mixture thereof.

[0059] According to exemplary embodiments, the calcined carrier can be compressed to provide a pellet-shaped carrier. In this case, the structure of the carrier can be maintained stably during the manufacturing process, thereby improving the quality of the final product, the ammonia decomposition catalyst.

[0060]

[0061] The step of acid-treating the support may comprise acid-treating the support with an acid solution under predetermined temperature and time conditions. This may modify the surface properties of the support, thereby increasing its acidity. Therefore, active metal particles may be more readily supported on the surface of the support. Consequently, even relatively small active metal particles may be uniformly distributed on the support, thereby improving the performance of the ammonia decomposition catalyst. Furthermore, the active metal particles may have less of an impact on the active metal particles than would be the case if a separate promoter were additionally treated after the ammonia decomposition catalyst was manufactured. This may enhance the stability and performance of the ammonia decomposition catalyst.

[0062]

[0063] According to exemplary embodiments, the acid treatment may be performed at a temperature of 85 to 95°C. More specifically, the acid treatment may be performed at a temperature of 90 to 95°C. If the acid treatment temperature is lower than 85°C, the acid concentration of the carrier may not sufficiently increase. If the acid treatment temperature exceeds 95°C, the solvent in the acid solution may evaporate excessively, preventing the acid treatment from being performed properly. Furthermore, the excessively evaporated vapor may easily corrode surrounding metals, thereby increasing safety hazards.

[0064] Acid treatment can be performed for 30 to 120 minutes. If the acid treatment time is less than 30 minutes, the acid content of the carrier may not increase sufficiently. If the acid treatment time exceeds 120 minutes, the acid content may increase excessively, and the carrier may dissolve in the acid. Additionally, the physical durability of the carrier may decrease.

[0065]

[0066] The acid solution is not particularly limited as long as it can increase the acidity of the carrier by acid treatment. As a non-limiting example, the acid solution may be a strong acid solution. As one example, the acid solution may be an aqueous solution of any one of hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), hydrofluoric acid (HF), or a combination thereof. More specifically, the acid solution may be an aqueous hydrochloric acid solution.

[0067] The molar concentration of the acid in the acid solution may range from 4 to 7 M. If the molar concentration of the acid is less than 4 M, the carrier and the acid may not react sufficiently, preventing the acid sites on the carrier from increasing to the target level. If the molar concentration of the acid exceeds 7 M, the acid and the carrier may react excessively, resulting in the generation of excessive acid sites and a decrease in the physical stability of the carrier.

[0068]

[0069] The step of washing the carrier can be accomplished by washing the acid-treated carrier with distilled water. This removes impurities, such as acid solution, remaining on the surface of the carrier after the acid treatment, thereby improving the quality of the ammonia decomposition catalyst. Furthermore, side reactions that may occur during the subsequent calcination process due to impurities remaining on the surface of the carrier can be minimized.

[0070]

[0071] The step of calcining the carrier may be performed by drying the washed carrier and then heat-treating it at a predetermined temperature and time.

[0072] Drying of the carrier can be performed at a temperature range of 70 to 90°C for 3 to 12 hours.

[0073] The dried carrier can be calcined at 500-800°C for 0.5-3 hours. Failure to meet these calcination conditions may result in unstable crystal structures in the final product, and residual impurities may not be completely removed after washing. Furthermore, impurities may bind to acid sites in the carrier, reducing its acidity.

[0074] According to exemplary embodiments, the firing treatment can be performed in a dry air atmosphere.

[0075] Hereinafter, the present invention will be described in more detail through examples. However, it should be noted that the following examples are intended only to illustrate and concretize the present invention and are not intended to limit the scope of the invention. This is because the scope of the invention is determined by the matters set forth in the patent claims and matters reasonably inferred therefrom.

[0076]

[0077] Example 1

[0078] Alpha alumina pellets were used as a support. 6M hydrochloric acid solution was prepared by diluting 62.5 g of a 35% hydrochloric acid (HCl) solution in 100 g of distilled water. 10 g of the support was dispersed in the hydrochloric acid solution, and the hydrochloric acid solution was heated to 90°C and maintained at that temperature for 1 hour to acid-treat the support. The support was removed from the hydrochloric acid solution, and the residual hydrochloric acid solution on the surface of the support was removed with distilled water. The washed support was dried overnight at 80°C. The dried support was calcined at 600°C in a dry air atmosphere for 1 hour to obtain the final support.

[0079]

[0080] Comparative Example 1

[0081] A carrier was prepared in the same manner as in Example 1, except that no acid treatment was performed.

[0082]

[0083] Comparative Example 2

[0084] A carrier was prepared in the same manner as in Example 1, except that the acid treatment was performed at room temperature (approximately 25°C).

[0085]

[0086] Comparative Example 3

[0087] A carrier was prepared in the same manner as in Example 1, except that the acid treatment was performed at 80°C.

[0088]

[0089] Manufacturing Example 1

[0090] The carrier and nickel precursor according to Example 1 were mixed in distilled water and evaporated to dryness. The evaporated and dried product was dried overnight at 80°C and then reduced for 1 hour in an argon gas atmosphere containing 50 vol% H2 at 600°C. As a result, a catalyst for ammonia decomposition containing nickel was obtained.

[0091]

[0092] Comparative Manufacturing Example 1

[0093] An ammonia decomposition catalyst was manufactured in the same manner as in Manufacturing Example 1, except that the support according to Comparative Example 1 was used.

[0094]

[0095] Experimental Example 1: Performance Verification of a Catalyst for Ammonia Decomposition

[0096] The performance of ammonia decomposition catalysts according to Manufacturing Example 1 and Comparative Manufacturing Example 1 in pellet form was compared. At this time, the space velocity for a reactor filled with about 30 g of catalyst was 5,000 h -1The pressure was controlled to 8 barg and the reaction temperature was controlled to 550, 600, and 650°C to confirm the performance of the ammonia decomposition catalyst according to Manufacturing Example 1 and Comparative Manufacturing Example 1.

[0097] Figure 1 is a graph showing the ammonia decomposition efficiency of a catalyst for ammonia decomposition.

[0098] Referring to Figure 1, it was confirmed that the ammonia decomposition catalyst according to Manufacturing Example 1 had a higher efficiency than the ammonia decomposition catalyst according to Comparative Manufacturing Example 1. This is believed to be because the acid site of the support increased by using an acid-treated support as the catalyst support.

[0099]

[0100] Experimental Example 2: Confirmation of Increase in Acidity According to Temperature

[0101] The acidity of the carriers according to Example 1 and Comparative Examples 1 to 3 was quantitatively analyzed using the NH3 TPD analysis method described above. More specifically, the carrier samples according to Example 1 and Comparative Examples 1 to 3 were pretreated. The pretreatment was performed under the following conditions: 1) 500°C for 1 hour under He flow conditions, 2) 100°C for 15 minutes under He flow conditions, 3) 100°C for 30 minutes under 10%NH3 / He flow conditions, and 4) 100°C for 15 minutes under He flow conditions. Through the pretreatment, NH3 can be sufficiently adsorbed on the Al2O3 surface. After the pretreatment, it was heated to 610°C at a heating rate of 10°C / min under He flow conditions. At this time, the NH3 that falls off was confirmed and quantified through a mass spectrometer, and NH3TPD analysis was performed.

[0102] The analysis results are shown in Table 1 below.

[0103] Distinctive point amount (mmol / g) Example 10.007 Comparative example 10.003 Comparative example 20.004 Comparative example 30.005

[0104] Referring to Table 1, it was confirmed that the acid amount increased by about two times compared to Comparative Example 1 in which acid treatment was not performed. In addition, it was confirmed that the acid amount increased as the acid treatment temperature increased. However, when the acid treatment temperature exceeded 95℃, the solvent of the acid solution evaporated excessively, so the acid treatment was not performed properly, and since the acid treatment could not be performed due to corroding the surrounding metals, a separate comparative example was not shown.

[0105] The present invention has been described in more detail through drawings and examples. However, the configurations described in the drawings or examples described in this specification are merely embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

Claims

1. As a carrier for a catalyst for ammonia decomposition, A carrier having an acid site amount of 0.006 to 0.010 mmol / g as measured by NH3-TPD analysis (NH3-Temperature Programmed Desorption) of the carrier.

2. In paragraph 1, The above-mentioned carrier is a carrier containing alumina.

3. In paragraph 2, The above alumina is a support comprising any one of alpha alumina (α-Al2O3), gamma alumina (γ-Al2O3), theta alumina (θ-Al2O3), and combinations thereof.

4. In paragraph 1, The above carrier is a carrier in the form of a pellet.

5. Step of preparing the carrier; A step of treating the above-mentioned carrier with an acid solution at 85 to 95°C for 30 to 120 minutes; A step of washing the acid-treated carrier; and A method for manufacturing a carrier, comprising: a step of drying and then calcining the washed carrier.

6. In paragraph 5, A method for producing a support, wherein the acid solution is an aqueous solution of any one of hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), hydrofluoric acid (HF), and a combination thereof.

7. In paragraph 5, A method for producing a carrier in which the molar concentration of the acid in the above acid solution is 4 to 7 M.

8. In paragraph 5, A method for manufacturing a carrier, wherein drying of the washed carrier is performed at 70 to 90°C for 3 to 12 hours.

9. In paragraph 5, A method for manufacturing a carrier, wherein the calcination treatment of the dried carrier is performed in a dry air atmosphere at 500 to 800°C for 0.5 to 3 hours.

10. A carrier according to any one of paragraphs 1 to 4; and Containing active metal particles supported on the above-mentioned carrier, An ammonia decomposition catalyst comprising at least one of nickel (Ni) or a nickel-based alloy as the active metal.

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