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

Abstract

According to an exemplary embodiment of the present application, a support is provided. The support is a support for a catalyst for ammonia decomposition, and the amount of acid of the support measured by ammonia temperature programmed desorption (NH3-TPD) analysis is 0.006 to 0.010 mmol / g. Furthermore, according to another exemplary embodiment of the present application, a method for manufacturing the support and a catalyst for ammonia decomposition comprising the support are provided.

Description

Technical Field

[0001] This invention relates to a carrier and a method for manufacturing the carrier.

[0002] Furthermore, the present invention relates to a catalyst for ammonia decomposition comprising a support. Background Technology

[0003] To overcome climate change and various environmental pollution problems, the world is striving to restructure its carbon-based energy society into a renewable energy-based energy society. However, because the distribution of renewable energy varies by region and time, the widespread use of renewable energy necessitates the establishment of trading systems between countries or continents, utilizing energy storage facilities capable of storing renewable energy at large capacities.

[0004] Hydrogen is a substance capable of storing energy in large quantities and stably over long periods. Many countries, including Europe, Japan, Saudi Arabia, and Australia, are striving to utilize hydrogen as a renewable energy storage medium to build a global renewable energy trading system. Furthermore, according to the South Korean government's hydrogen economy development roadmap, the South Korean government has set a goal to increase the domestic hydrogen supply. However, due to hydrogen's very low energy density relative to volume, research into chemical and physical hydrogen storage methods is essential for economically importing large quantities of hydrogen from overseas. To this end, various hydrogen storage materials are being actively researched, such as ammonia (NH3), liquid organic hydroxides (LOHCs), and liquid hydrogen (LH2). In particular, ammonia has attracted attention as a commercially viable hydrogen storage (renewable energy) medium due to its high hydrogen storage capacity (17.6 wt%, 108 g / L), ease of storage (8.74 kPa, 20°C), and the ability to utilize existing ammonia storage and transportation infrastructure.

[0005] Ammonia molecule consists of three hydrogen atoms and one nitrogen atom. When this molecule decomposes at high temperatures, it produces only hydrogen gas and nitrogen gas, which makes up 78% of the air. Ammonia has the advantage of being able to be directly used in existing infrastructure for large-capacity storage and long-distance transportation, and because it produces only hydrogen and nitrogen gas, it can minimize carbon dioxide emissions.

[0006] The ammonia decomposition reaction can proceed at high temperatures according to the reaction equation shown below.

[0007] 2NH3(g)→N2(g)+3H2(g) To improve the efficiency of ammonia decomposition reactions, enhancing catalyst performance is crucial. To address this, the addition of promoters such as rare earth metals has been explored. This is because promoters can improve catalyst performance by altering the electronic structure of the active metal. However, most of these promoters consist of expensive metal elements or those with limited reserves only in specific regions. Therefore, when using promoters in large-scale industrial reactors, problems arise such as difficulties in supplying the catalyst smoothly or excessively increased catalyst costs.

[0008] Therefore, there is a need to develop a technology that can improve catalyst performance without adding additives such as accelerators.

[0009] (Patent Document 1) Japanese Patent Publication No. 2023-539511 Summary of the Invention

[0010] (a) Technical problems to be solved The technical problem to be solved by the present invention is to provide a carrier that can stably load active metal particles and a method for manufacturing the same.

[0011] Another technical problem of the present invention is to provide a catalyst for ammonia decomposition comprising a support in which active metal particles are stably bound.

[0012] The technical problem addressed by this invention is not limited to the above description. Those skilled in the art will readily understand the additional technical problems of this invention from the entirety of this specification.

[0013] (II) Technical Solution According to an exemplary embodiment of the present invention, a support is provided. The support is a support for a catalyst for ammonia decomposition, and the amount of acid sites in the support, as determined by NH3-Temperature Programmed Desorption (NH3-TPD) analysis, is 0.006-0.010 mmol / g.

[0014] The carrier may include aluminum oxide.

[0015] The alumina may include any one of α-alumina (α-Al2O3), γ-alumina (γ-Al2O3), θ-alumina (θ-Al2O3), and combinations thereof.

[0016] The carrier can be in the form of pellets.

[0017] According to another exemplary embodiment of the present invention, a method for manufacturing a carrier is provided. The method for manufacturing the carrier includes the following steps: preparing a carrier; acid-treating the carrier with an acid solution at 85-95°C for 30-120 minutes; washing the acid-treated carrier; and drying the washed carrier followed by calcination.

[0018] The acid solution may be an aqueous solution of any one of hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), hydrofluoric acid (HF), and combinations thereof.

[0019] The molar concentration of the acid in the acid solution can be 4-7 M.

[0020] The carrier washed in the above manner can be dried at 70-90°C for 3-12 hours.

[0021] The calcination treatment of the dried carrier can be carried out at 500-800°C in a dry air atmosphere for 0.5-3 hours.

[0022] According to another exemplary embodiment of the present invention, a catalyst for ammonia decomposition is provided. The catalyst comprises: any one or more of the above-described supports; and active metal particles supported on the supports, wherein the active metal comprises any one or more of nickel (Ni) or nickel-based alloys.

[0023] (III) Beneficial Effects According to an exemplary embodiment of the present invention, the performance of the catalyst for ammonia decomposition can be improved without the need to add a separate promoter by increasing the acid centers of the support.

[0024] The various beneficial advantages and effects of the present invention are not limited to the above description, and can be more easily understood in the process of describing the specific embodiments of the present invention. Attached Figure Description

[0025] Figure 1 This is a graph showing the ammonia decomposition efficiency of the catalyst used for ammonia decomposition. Best practice

[0026] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings, but rather should be interpreted as meanings and concepts consistent with the technical concept of the present invention, based on the principle that the inventors may appropriately define the terms to best illustrate their invention.

[0027] Furthermore, when describing embodiments of the present invention with reference to the accompanying drawings, the same or corresponding constituent elements are given the same reference numerals, and repeated descriptions thereof are omitted.

[0028] In the following implementation scheme, the terms "first," "second," etc., are not limiting in meaning, but are used for the purpose of distinguishing one constituent element from another.

[0029] In the following implementation, unless the context clearly indicates otherwise, the singular expression includes the plural expression.

[0030] In the following implementation, terms such as "comprising / including" or "having" mean that the features or constituent elements described in the specification are present, without pre-excluding the possibility of adding more than one other feature or constituent element.

[0031] In the accompanying drawings, the dimensions of the constituent elements may be enlarged or reduced for ease of illustration. For example, the dimensions and thicknesses of the various components shown in the drawings are arbitrarily illustrated for ease of explanation, and therefore the invention is not necessarily limited to the contents shown in the drawings.

[0032] Where a particular implementation can be carried out in different forms, a specific process sequence can be performed in a manner different from the described sequence. For example, two processes described consecutively can be performed substantially simultaneously, or they can be performed in the reverse order of the description.

[0033] Furthermore, when describing the present invention, detailed descriptions of related known structures or functions may obscure the essential points of the invention, such descriptions are omitted.

[0034] Catalyst for ammonia decomposition According to an exemplary embodiment, the catalyst for ammonia decomposition comprises a support and active metal particles supported on the support.

[0035] According to an exemplary embodiment, the active metal particles can be any one or more of Ni or Ni-based alloys. 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 loading only Ni or Ni-based alloys.

[0036] Nickel or ruthenium can be used as the active metal particles for ammonia decomposition catalysts. Nickel is an abundant non-precious metal element and has the advantage of being cheaper than ruthenium. Catalysts using nickel as the active metal particle are inexpensive to manufacture and therefore suitable for large-scale plant facilities.

[0037] As an example, the active temperature of catalysts used for ammonia decomposition can be above 500℃.

[0038] [Carrier] According to an exemplary embodiment, the support may include alumina. More specifically, the alumina may include any one of α-alumina (α-Al₂O₃), γ-alumina (γ-Al₂O₃), θ-alumina (θ-Al₂O₃), and combinations thereof. More specifically, the support may include α-alumina.

[0039] Alumina exhibits excellent thermal stability and durability. By utilizing alumina as a support for ammonia decomposition catalysts, the stability of the catalysts can be maintained even under high-temperature reaction conditions. In terms of the thermal stability and durability of such catalysts, α-alumina is the most preferred support.

[0040] According to an exemplary embodiment, the support can be in spherical form. Spherical form is formed by compressing solid particles. This spherical form exhibits excellent physical durability and is easy to operate in both experimental-scale and commercial-scale reactors. Furthermore, in commercial-scale reactors, with spherical catalysts, the pressure differential applied to the catalyst layer can be lower compared to powdered catalysts. Therefore, process problems such as pressure differentials occur less frequently in various chemical reactions, resulting in superior performance. As described above, by using a spherical support, the catalyst for ammonia decomposition can be readily applied in commercial plants.

[0041] The acidity of the carrier, as determined by ammonia-programmed temperature desorption (NH3-TPD) analysis, can range from 0.006 to 0.010 mmol / g.

[0042] The lower the acid content of the support, the weaker the binding force between the active metal particles and the support. This can lead to the active metal particles easily detaching from the support and agglomerating, potentially reducing the active surface area of ​​the catalyst. To prevent these problems, the acid content of the support can be 0.006 mmol / g or higher. Increasing the acid content of the support allows the active metal particles to bind more firmly and stably to the support, and enables the loading of a wider distribution of active metal particles, thereby increasing the active surface area of ​​the ammonia decomposition catalyst. Therefore, the performance of the ammonia decomposition catalyst can be improved. However, when the acid content of the support exceeds 0.010 mmol / g, the acid centers may act as catalysts, potentially leading to undesirable side reactions. Furthermore, during the ammonia decomposition reaction, it may affect the electronic structure of the active metal particles, which could conversely reduce the catalyst's performance.

[0043] [Methods for manufacturing carriers] The method for manufacturing the carrier may include the steps of preparing the carrier, acid treating the carrier, washing the carrier, and calcining the carrier.

[0044] The preparation of the carrier can consist of calcining the precursor of the carrier.

[0045] The calcination treatment of the precursor of the support can be carried out under conventional conditions known in the art. As an example, the calcination treatment can consist of heat treating the precursor of the support at a temperature range of 400-1200°C. More specifically, the calcination treatment can consist of heat treating the precursor of the support at a temperature range of 1000-1200°C.

[0046] 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 substance that can provide a support through calcination. As an example, the precursor of the support may be alumina hydrate. More specifically, the precursor of the support may be any one or more of alumina trihydrate, alumina monohydrate, or mixtures thereof.

[0047] The alumina trihydrate can be any one or more of gibbsite, bayerite, or mixtures thereof. The alumina monohydrate is preferably boehmite, diaspore, or mixtures thereof.

[0048] According to an exemplary embodiment, the calcined support can be compressed to provide a support in granular form. In this case, the structure of the support can be stably maintained during the manufacturing process, thereby improving the quality of the final product, namely the catalyst for ammonia decomposition.

[0049] The acid treatment of the support can consist of treating the support with an acid solution under predetermined temperature and time conditions. This modifies the surface properties of the support, thereby increasing its acid content. Consequently, active metal particles can be more easily loaded onto the support surface. Ultimately, relatively small active metal particles can be uniformly distributed on the support, thus improving the performance of the ammonia decomposition catalyst. Furthermore, compared to additional treatment with a separate promoter after the manufacture of the ammonia decomposition catalyst, the impact on the active metal particles is reduced. Therefore, the stability and performance of the ammonia decomposition catalyst can be improved.

[0050] According to an exemplary embodiment, acid treatment can be performed at 85-95°C. More specifically, acid treatment can be performed at 90-95°C. When the acid treatment temperature is below 85°C, the acid content of the carrier may not increase sufficiently. When the acid treatment temperature exceeds 95°C, the solvent in the acid solution may evaporate excessively, which may prevent the acid treatment from proceeding properly. Furthermore, the excessively evaporated vapors may easily corrode surrounding metals, thus potentially increasing safety hazards.

[0051] Acid treatment can be performed for 30-120 minutes. When the acid treatment time is less than 30 minutes, the acid content of the carrier may not increase sufficiently. When the acid treatment time exceeds 120 minutes, the acid content may increase excessively, and the carrier may dissolve in the acid. In addition, the physical durability of the carrier may decrease.

[0052] The acid solution is not particularly limited, as long as it is a solution in which the acid content can be increased by acid treatment of the carrier. As a non-limiting example, the acid solution can be a strong acid solution. As an example, the acid solution can be an aqueous solution of any of hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), hydrofluoric acid (HF), and combinations thereof. More specifically, the acid solution can be an aqueous solution of hydrochloric acid.

[0053] The molar concentration of acid in the acid solution can be 4-7 M. When the molar concentration of acid is less than 4 M, the support and acid may not react sufficiently, and thus the amount of acid on the support may not increase to the target level. When the molar concentration of acid exceeds 7 M, the acid and support may react excessively, potentially generating an excess of acid centers, and the physical stability of the support may decrease.

[0054] The washing step of the support can consist of washing the acid-treated support with distilled water. This removes impurities such as acid solution remaining on the support surface after acid treatment, thereby improving the quality of the catalyst for ammonia decomposition. Furthermore, during the subsequent calcination process, potential side reactions caused by impurities remaining on the support surface can be minimized.

[0055] The step of calcining the carrier can consist of drying the washed carrier and then heat-treating it at a predetermined temperature and time.

[0056] The carrier can be dried at a temperature range of 70-90℃ for 3-12 hours.

[0057] The dried support can be calcined at 500-800°C for 0.5-3 hours. If these calcination conditions are not met, the crystal structure of the final product, the support, may become unstable, and residual impurities after washing may not be completely removed. Furthermore, impurities may bind to acid sites on the support, potentially leading to a reduction in acid content.

[0058] According to an exemplary embodiment, the calcination process can be carried out in a dry air atmosphere. Detailed Implementation

[0059] The present invention will now be described in more detail through embodiments. However, it should be noted that the following embodiments are merely illustrative of the invention and do not limit the scope of the invention. This is because the scope of the invention is determined by the contents of the claims and what can be reasonably inferred therefrom.

[0060] Example 1 α-alumina in spherical form was used as the support. A 6M hydrochloric acid solution was prepared by diluting 62.5 g of 35% hydrochloric acid (HCl) aqueous solution in 100 g of distilled water. 10 g of the support was dispersed in the hydrochloric acid solution, which was then heated to 90°C and maintained at this temperature for 1 hour to acid-treat the support. The support was removed from the hydrochloric acid solution, and any residual hydrochloric acid solution on its surface was removed with distilled water. The washed support was dried overnight at 80°C. The dried support was then calcined at 600°C in a dry air atmosphere for 1 hour to obtain the final support.

[0061] Comparative Example 1 The carrier was manufactured using the same method as in Example 1, except that no acid treatment was performed.

[0062] Comparative Example 2 The carrier was manufactured using the same method as in Example 1, except that acid treatment was performed at room temperature (approximately 25°C).

[0063] Comparative Example 3 The carrier was manufactured using the same method as in Example 1, except that it was acid-treated at 80°C.

[0064] Manufacturing Example 1 The support and nickel precursor from Example 1 were mixed in distilled water and evaporated to dryness. The evaporated product was dried overnight at 80°C, and then reduced at 600°C in an argon atmosphere containing 50% H2 for 1 hour. This yielded a nickel-containing catalyst for ammonia decomposition.

[0065] Comparative Manufacturing Example 1 The catalyst for ammonia decomposition was manufactured using the same method as in Comparative Example 1, except that the support of Comparative Example 1 was used.

[0066] Experimental Example 1: Confirmation of the performance of catalysts for ammonia decomposition The performance of the ammonia decomposition catalysts was compared using the catalysts from Manufacturing Example 1 and Comparative Manufacturing Example 1 in pellet form. In this case, for a reactor filled with approximately 30 g of catalyst, the space velocity was controlled at 5000 h⁻¹. -1 The pressure was controlled at 8 bar (gauge pressure), and the reaction temperature was controlled at 550°C, 600°C, and 650°C to confirm the performance of the catalysts for ammonia decomposition in Manufacturing Example 1 and Comparative Manufacturing Example 1.

[0067] Figure 1 This is a graph showing the ammonia decomposition efficiency of the catalyst used for ammonia decomposition.

[0068] Reference Figure 1 It can be confirmed that the ammonia decomposition catalyst of Comparative Manufacturing Example 1 has superior efficiency. This is because the acid content of the support is increased by using an acid-treated support as the catalyst support.

[0069] Experimental Example 2: Confirmation of the increase in acidity based on temperature The acidity of the supports in Example 1 and Comparative Examples 1 to 3 was quantitatively analyzed using the NH3-TPD method. More specifically, the support samples in 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 a He gas flow; 2) 100°C for 15 minutes under a He gas flow; 3) 100°C for 30 minutes under a 10% NH3 / He gas flow; 4) 100°C for 15 minutes under a He gas flow. Pretreatment allowed NH3 to be fully adsorbed onto the Al2O3 surface. After pretreatment, the samples were heated to 610°C at a heating rate of 10°C / min under a He gas flow. The desorbed NH3 was then confirmed and quantified by mass spectrometry for NH3-TPD analysis.

[0070] The analysis results are shown in Table 1 below.

[0071] [Table 1] Referring to Table 1, it can be confirmed that the amount of acid in Example 1 increased to approximately twice that of Comparative Example 1, which did not undergo acid treatment. Furthermore, it can be confirmed that the amount of acid increases with increasing acid treatment temperature. However, when the acid treatment temperature exceeds 95°C, excessive evaporation of the solvent in the acid solution prevents normal acid treatment and causes corrosion of the surrounding metal, thus making acid treatment impossible. Therefore, a separate comparative example is not shown.

[0072] The present invention has been described in more detail above with reference to the accompanying drawings and embodiments. However, the configurations described in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not represent all the technical ideas of the present invention. Therefore, it should be understood that this application may have various equivalents and variations that can replace them.

Claims

1. A support, said support being a support for a catalyst used in ammonia decomposition. The acidity of the carrier, as determined by ammonia-programmed temperature desorption (NH3-TPD) analysis, was 0.006-0.010 mmol / g.

2. The carrier according to claim 1, wherein, The carrier includes aluminum oxide.

3. The carrier according to claim 2, wherein, The alumina includes any one of α-alumina (α-Al2O3), γ-alumina (γ-Al2O3), θ-alumina (θ-Al2O3), and combinations thereof.

4. The carrier according to claim 1, wherein, The carrier is in the form of spheres.

5. A method for manufacturing a carrier, comprising the following steps: Prepare the carrier; The carrier is acid-treated with an acid solution at 85-95°C for 30-120 minutes. The carrier treated with the acid is then washed. as well as The washed carrier is dried and then calcined.

6. The method for manufacturing a carrier according to claim 5, 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 combinations thereof.

7. The method for manufacturing a carrier according to claim 5, wherein, The molar concentration of the acid in the acid solution is 4-7 M.

8. The method for manufacturing a carrier according to claim 5, wherein, The carrier washed is dried at 70-90°C for 3-12 hours.

9. The method for manufacturing a carrier according to claim 5, wherein, The calcination treatment of the dried carrier is carried out at 500-800°C in a dry air atmosphere for 0.5-3 hours.

10. A catalyst for ammonia decomposition, comprising: The carrier according to any one of claims 1 to 4; and Active metal particles, wherein the active metal particles are loaded on the carrier. in, The active metal comprises one or more of nickel (Ni) or nickel-based alloys.

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