Hydrogen production reactor using ammonia decomposition reaction

Abstract

One embodiment of the present invention relates to a hydrogen production reactor for producing hydrogen by decomposing ammonia. The hydrogen production reactor comprises: a housing; at least one reaction tube provided inside the housing and having an inlet into which a reactant containing ammonia flows in: a heating unit for providing heat to the reaction tube; a preheating unit provided in the reaction tube and extending in one direction; and a catalyst layer positioned downstream of the preheating unit and extending in one direction, wherein the preheating unit is filled with an oxide containing magnesium oxide (MgO).

Description

Hydrogen production reactor using ammonia decomposition reaction

[0001] The present invention relates to a hydrogen production reactor, and more particularly, to a hydrogen production reactor utilizing an ammonia decomposition reaction.

[0002] To address the growing demand for clean and sustainable technologies for portable, automotive, and / or stationary fuel cells, research on hydrogen storage materials is gaining traction. In particular, liquid and solid materials such as formic acid and ammonia are attracting attention as chemical hydrogen storage materials applicable to fuel cells.

[0003] H2 generated from NH3, a gas that can be liquefied under mild conditions (20°C and 0.8 MPa), does not produce CO or CO2 and can be supplied as a product to polymer electrolyte membrane fuel cells (PEMFCs), and can be applied to various fuel cell systems such as fuel cells for power generation, coupled operation, and energy storage systems. This is evaluated as a potential advantage because the system configuration is simpler than that of reforming systems that require additional processes such as water gas shift reaction or selective CO corrosion reaction to remove CO and CO2 generated during fixation.

[0004] The ammonia decomposition reaction [2NH3->N2+3H2, △H=46.2 kJ / mol] is an endothermic reaction that is completely converted into hydrogen and nitrogen under high temperature and atmospheric pressure. In the case of an endothermic reaction where heat transfer from the outside to the inside of the reactor is the main factor, metal-based supports (monolith, foam, mesh, felt) are much more effective in heat transfer than conventional pellet catalysts. However, when using metal-based supports to solve this problem, especially in the case of FeCr alloy, there is a problem of corrosion by ammonia, which makes it difficult to operate the reactor for a long time.

[0005] Furthermore, in conventional reactors, a catalyst layer that promotes the reaction of ammonia to produce hydrogen is formed within the reaction tube, and the remaining empty space is often filled with alumina balls. However, alumina balls have limitations in that their catalytic activity is reduced due to their reaction with high-temperature ammonia.

[0006] The technical problem to be solved by the present invention is to provide a clean hydrogen production reactor without carbon emissions.

[0007] In addition, the present invention provides a hydrogen production reactor having excellent heat transfer performance according to an endothermic reaction and stable reaction activity of a catalyst by having a preheating section that does not react with ammonia.

[0008] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0009] In order to achieve the above technical task, one embodiment of the present invention provides a hydrogen production reactor for producing hydrogen by decomposing ammonia, comprising: a housing; at least one reaction tube provided inside the housing and through which a reactant including ammonia flows in through an inlet; a heating unit for providing heat to the reaction tube; a preheating unit provided in the reaction tube and extending in one direction; and a catalyst layer located downstream of the preheating unit and extending in one direction, wherein the preheating unit is characterized in that it is filled with an oxide including magnesium oxide (MgO).

[0010] In an embodiment of the present invention, the preheating unit may be filled with an oxide including magnesium aluminate spinel (MAS, MgO-Al2O3).

[0011] In an embodiment of the present invention, the preheating unit may further include silicon carbide (SiC) and a metal filler.

[0012] In an embodiment of the present invention, the metal filler may be at least one selected from the group consisting of tungsten, nickel, iron, cobalt, chromium, molybdenum, manganese, aluminum, and copper.

[0013] In an embodiment of the present invention, the reaction tube may be provided as a single tube or as a double tube structure consisting of an inner tube of the reaction section and an outer tube of the reaction section surrounding the inner tube of the reaction section.

[0014] In an embodiment of the present invention, the catalyst layer includes at least one of a ceramic catalyst layer and a metal structure catalyst layer, and the ceramic catalyst layer can be disposed at the lower portion of the preheating section.

[0015] In an embodiment of the present invention, the ceramic catalyst layer and the metal structure catalyst layer are provided in the order of the ceramic catalyst layer - the metal structure catalyst layer in the direction in which the reactants are introduced, and the reactants can be introduced into the metal structure catalyst layer through the ceramic catalyst layer.

[0016] In an embodiment of the present invention, the ceramic catalyst layer may be provided outside the reaction tube, and the metal structure catalyst layer may be provided inside the reaction tube, spaced apart from the ceramic catalyst layer.

[0017] In an embodiment of the present invention, the ceramic catalyst layer may include at least one material selected from the group consisting of alumina (Al2O3), silicon carbide (SiC), cordierite, and magnesium oxide (MgO) as a carrier, and may include an active metal provided on the carrier.

[0018] In an embodiment of the present invention, the active metal may include at least one selected from the group consisting of ruthenium (Ru), nickel (Ni), iron (Fe), cobalt (Co), and rhodium (Rh).

[0019] In an embodiment of the present invention, the ceramic catalyst layer included in the catalyst layer may be included in a ratio of 5 to 15% with respect to the total volume of the catalyst layer.

[0020] According to an embodiment of the present invention, the heat transfer performance according to the endothermic reaction is excellent, and a preheating section that does not react with ammonia is provided, thereby enabling the catalyst to exhibit stable reaction performance.

[0021] The effects of the present invention are not limited to the above-described effects, and should be understood to include all effects that can be inferred from the composition of the invention described in the description or claims of the present invention.

[0022] Figure 1 is a cross-sectional view schematically illustrating the configuration and structure of a hydrogen production reactor according to one embodiment of the present invention.

[0023] Figure 2 is a schematic drawing of a reaction tube according to various embodiments of the present invention.

[0024] Figure 3 is a cross-sectional view of a reaction tube included in a hydrogen production reactor according to one embodiment of the present invention.

[0025] Figure 4 is a cross-sectional view showing the structure of a hydrogen production reactor according to another embodiment of the present invention.

[0026] Figure 5 is a cross-sectional view of a reaction tube included in a hydrogen production reactor according to another embodiment of the present invention.

[0027] FIG. 6 is a drawing illustrating the effect when the preheating section of the present invention is filled with an oxide including magnesium oxide.

[0028] Figure 7 is an image showing the corrosion pattern according to the amount of ceramic catalyst layer included in the catalyst layer.

[0029] Hereinafter, the present invention will be described with reference to the attached drawings. However, the present invention can be implemented in various different forms and is therefore not limited to the embodiments described herein. In the drawings, irrelevant parts have been omitted for clarity of description, and similar parts have been designated with similar reference numerals throughout the specification.

[0030] Throughout the specification, when a part is said to be "connected (connected, contacted, or coupled)" to another part, this includes not only cases where it is "directly connected," but also cases where it is "indirectly connected" with another part in between. Furthermore, when a part is said to "include" a component, this does not exclude other components, but rather implies that it may include other components, unless otherwise specifically stated.

[0031] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0033] The hydrogen production reactor according to the present invention comprises a ceramic catalyst layer, a metal structure catalyst layer, and a preheating section including magnesium oxide (MgO), thereby enabling hydrogen production with high efficiency without the problem of catalyst layer corrosion due to a reactant including ammonia.

[0034] Figure 1 is a cross-sectional view schematically illustrating the configuration and structure of a hydrogen production reactor according to one embodiment of the present invention. Figure 2 is a drawing schematically illustrating a reaction tube according to various embodiments of the present invention.

[0035] Referring to FIG. 1, a hydrogen production reactor (10) according to an embodiment of the present invention may include a housing (100), a reaction tube (200), a heating unit (300), a catalyst layer (400), and a preheating unit (500).

[0036] The housing (100) may include an empty space therein to accommodate the reaction tube (200). According to one embodiment of the present invention, the housing (100) may have a hole in its upper surface so that at least a portion of the reaction tube (200) may be inserted into the housing (100).

[0037] The housing (100) may have various shapes, such as a cylinder, a cube, or a rectangular parallelepiped. The size of the internal space of the housing (100) may be larger than the volume of the reaction tube (200). Specifically, the size of the internal space of the housing (100) may be provided to a size that can accommodate at least one reaction tube (200) spaced apart from each other.

[0038] The housing (100) may further include an insulating material (600) on the wall surface. Accordingly, when a heating unit (300) is provided inside the housing (100), heat generated from the heating unit (300) can be prevented from escaping outside the housing (100). Since the reaction in which hydrogen is extracted from ammonia is an endothermic reaction, more efficient hydrogen production is possible by preventing heat loss using the insulating material (600) included in the housing (100).

[0039] A reaction tube (200) is provided inside the housing (100), and a reactant including ammonia can be introduced through the inlet. The reaction tube (200) may include an ammonia decomposition reactor tube (210) and a combustion exhaust gas discharge tube (230). A reactant including ammonia, a catalyst layer (400), and a preheating unit (500) may be provided inside the ammonia decomposition reactor tube (210). In addition, the combustion exhaust gas discharge tube (230) is arranged to surround at least a portion of the ammonia decomposition reactor tube (210), and the combustion exhaust gas can be discharged between the ammonia decomposition reactor tube (210) and the combustion exhaust gas discharge tube (230).

[0040] A conversion reaction of reactants may be performed in the reaction tube (200). At this time, the reactant may include ammonia, and the conversion reaction may be a reaction in which hydrogen is extracted from ammonia. Accordingly, an endothermic reaction in which hydrogen is extracted from ammonia may be performed while the reactant including ammonia is introduced into the reaction tube (200) and passes through the reaction tube (200). The hydrogen thus produced may be discharged to the outside along the reaction tube (200) in a gaseous form. Although not illustrated in the drawing, the hydrogen production reactor (10) may further include a separation unit for separating hydrogen gas from the product.

[0041] The reaction tube (200) may be provided adjacent to the heating unit (300) that provides reaction heat. The reaction tube (200) may be formed in multiple units. By providing multiple reaction tubes (200), the amount of ammonia decomposition per unit time increases, thereby improving hydrogen production.

[0042] The reaction tube (200) may be provided in the form of a tubular reactor. Tubular reactors offer the advantage of easier catalyst loading compared to channel reactors. However, channel reactors not only present difficulties in uniformly coating the catalyst directly within the long channels, but also present difficulties in inserting the catalyst into the channels. Furthermore, channel reactors have the problem that if the exothermic and endothermic reactions occurring on both sides of the channels are not balanced, the reaction may not occur, resulting in catalyst inactivation and reduced reactor efficiency.

[0043] Referring to FIG. 2, the reaction tube (200) of the present invention may be formed in a double-tube shape (double-tube reactor) consisting of a reaction section inner tube and a reaction section outer tube surrounding the reaction section inner tube, as shown in (a), or may be formed in a single-tube shape (single-tube reactor) as shown in (b).

[0044] The heating unit (300) can provide heat to the reaction tube (200).

[0045] The heating unit (300) may be implemented as a heating device or a burner that generates an exothermic reaction such as a combustion reaction. There is no particular limitation on the form in which the heating unit (300) is provided, but in the present embodiment, it is exemplified as being provided in the form of a burner.

[0046] The heating unit (300) is provided inside the housing (100) and can emit heat into the interior of the housing (100). There is no limitation on the position where the heating unit (300) is provided. For example, the heating unit (300) may be provided at the center of the housing (100), and a plurality of reaction tubes (200) may be provided in a form surrounding the heating unit (300). In another embodiment, the heating unit (300) may be formed to be long along the longitudinal direction of the housing (100), and the reaction tubes (200) may be provided inside the heating unit (300).

[0047] The heat provided from the heating unit (300) can be transferred to the reaction tube (200), the catalyst layer (400), and / or the preheating unit (500).

[0048] The catalyst layer (400) is located downstream of the preheating unit (500) and may be provided in a form extending in one direction. The catalyst layer (400) may receive heat provided from the heating unit (300) and promote a reaction in which hydrogen is generated from ammonia. The catalyst layer (400) may include at least one of a ceramic catalyst layer (410) and a metal structure catalyst layer (430). At least a portion of the catalyst layer (400) may be provided inside the reaction tube (200). For example, as shown in the drawing, the entire catalyst layer (400) may be provided inside the reaction tube (200), or in another embodiment, a portion of the catalyst layer (400) may be provided outside the reaction tube (200). Although the catalyst layer (400) of the present invention is preferably composed only of the ceramic catalyst layer (410), in another embodiment, it may be composed of the ceramic catalyst layer (410) and the metal structure catalyst layer (430).

[0049] A preheating section (500) is provided in the reaction tube (200) and may be formed in a shape extending in one direction. The preheating section (500) includes a material with high thermal conductivity, so that heat supplied from the outside of the reaction tube (200) can be quickly transferred to the inside of the reaction tube (200).

[0050] The preheating unit (500) of the present invention may be filled with an oxide including magnesium oxide (MgO). Here, the oxide including magnesium oxide may be, for example, an oxide including magnesium aluminate spinel (MAS, MgO-Al2O3).

[0051] In addition, the filler filled in the preheating unit (500) may further include silicon carbide (SiC) and a metal filler. Here, the metal filler may be at least one selected from the group consisting of stainless steel (SUS), but is not limited thereto. Stainless steel may refer to a material based on iron (Fe) and chromium (Cr). The metal filler according to one embodiment of the present invention may be at least one selected from the group consisting of tungsten, nickel, iron, cobalt, chromium, molybdenum, manganese, aluminum, and copper, as a non-limiting example. In some cases, the preheating unit (500) may include Fe fibers.

[0052] As described above, the preheating section (500) must be filled with a material having excellent heat transfer characteristics, and it is preferable to fill it with a material that does not act as a catalyst.

[0053] Figure 3 is a cross-sectional view of a reaction tube included in a hydrogen production reactor according to one embodiment of the present invention. While the reaction tube according to Figure 3 is illustrated as having a double-tube structure, the reaction tube of the present invention may be formed in this double-tube structure or may be provided in a single-tube form.

[0054] A preheating section (500) and a catalyst layer (400) may be formed inside the reaction tube (200). The catalyst layer (400) may have a form extending in one direction within the reaction tube (200). Specifically, the catalyst layer (400) may be formed along the longitudinal direction of the reaction tube (200). For example, the catalyst layer (400) may fill the interior of the tubular reaction tube (200) or may be provided in a form coated on the inner wall of the reaction tube (200). Since the catalyst layer (400) is formed in a form extending in one direction, the reactant may continuously contact the catalyst layer (400) while flowing along the reaction tube (200). Accordingly, the effect of promoting the conversion reaction of the reactant by the catalyst layer (400) may be further enhanced.

[0055] The catalyst layer (400) may include at least one of a ceramic catalyst layer (410) and a metal structure catalyst layer (430). At this time, the ceramic catalyst layer (410) may be disposed adjacent to the inlet of the reaction tube (200) and below the preheating section (500). According to one embodiment of the present invention, when the catalyst layer (400) includes both the ceramic catalyst layer (410) and the metal structure catalyst layer (430), the reactant may meet the ceramic catalyst layer (410) before the metal structure catalyst layer (430).

[0056] The ceramic catalyst layer (410) may include catalyst particles supported on a ceramic support. Since the ceramic support has strong corrosion resistance, it is not corroded by ammonia included in the reactant. In the ceramic catalyst layer (410), the catalyst particles may be coated on the ceramic support or provided in a powder form. Since the ceramic catalyst layer (410) has corrosion resistance to ammonia, the catalyst layer (400) may not deteriorate even with repeated use and the catalytic effect may be maintained. The catalyst particles may include a ceramic support and an active metal. Specifically, the catalyst particles may be provided in a form in which the active metal is supported on a ceramic support. The ceramic support may be at least one selected from the group consisting of Al2O3, SiC, Cordierite, and MgO, but is not limited thereto. In addition, the ceramic is not limited to a specific structure or shape, and in one embodiment, a monolithic or foam form may be used instead of a pellet form. The active metal may be at least one selected from the group consisting of, but is not limited to, ruthenium (Ru), nickel (Ni), iron (Fe), cobalt (Co), and rhodium (Rh).

[0057] The metal structure catalyst layer (430) may include a metal structure and catalyst particles supported thereon. The metal structure has excellent heat transfer characteristics. Therefore, by including the metal structure in the metal structure catalyst layer (430), heat inside the reactor can be quickly transferred to the catalyst particles supported on the metal structure. Accordingly, the speed of the endothermic reaction promoted by the catalyst particles increases. The metal structure may be at least one selected from the group consisting of iron (Fe), chromium (Cr), nickel (Ni), manganese (Mn), and copper (Cu), but is not limited thereto. The metal structure may be in the form of a metal foam, a monolith, or the like. The catalyst particles may be supported on the metal structure. The catalyst particles may include a ceramic support and an active metal. The catalyst particles may be a composite of the ceramic support and the active metal. The ceramic support may be at least one selected from the group consisting of Al2O3, SiC, Cordierite, and MgO, but is not limited thereto. Additionally, the ceramic is not limited to a specific structure or shape, and in one embodiment, it may be in the form of a monolith or foam rather than a pellet. The active metal may be at least one selected from the group consisting of ruthenium (Ru), nickel (Ni), iron (Fe), cobalt (Co), and rhodium (Rh), but is not limited thereto.

[0058] The metal structure catalyst layer (430) may be composed of multiple stages. The metal structures of the multiple stages may be independently replaced. Furthermore, the metal structure catalyst layer (430) may be independently added or removed from the reaction tube (200) depending on the processing capacity of the reactor.

[0059] The metal structure catalyst layer (430) may be provided below the ceramic catalyst layer (410) along the direction in which the reactants flow. Accordingly, the reactants may first pass through the ceramic catalyst layer (410) and then flow into the metal structure catalyst layer (430). Accordingly, when the reactants contain a high concentration of ammonia gas, a conversion reaction of ammonia may be performed first in the ceramic catalyst layer (430), thereby reducing the concentration of ammonia gas in the reactants. Next, since the metal structure catalyst layer (430) and the reactants meet in a state in which the concentration of ammonia gas is reduced, the metal structure catalyst layer (450) may be prevented from being corroded by ammonia.

[0060] Prior art techniques have been problematic in that long-term operation is impossible when using a metal structure that is corrosive to ammonia. It has been confirmed that the surface of the metal structure corrodes after an ammonia decomposition reaction at high temperatures. According to the present invention, the ceramic catalyst layer (410) and the metal structure catalyst layer (430) are provided in the above-described form, thereby eliminating concerns about the catalyst layer corroding during the process. Furthermore, process efficiency can be improved because the concentration of ammonia gas included in the reactant can be increased.

[0061] When the catalyst layer (400) is composed of a ceramic catalyst layer (410) and a metal structure catalyst layer (430), the ceramic catalyst layer (410) may be included in a ratio of 5% to 15% with respect to the total volume of the catalyst layer (400). When the ceramic catalyst layer (410) is included in a volume ratio of less than 5%, the reaction between the ceramic catalyst layer (410) and ammonia may not sufficiently occur. In this case, a high concentration of ammonia gas may flow into the metal structure catalyst layer (430), causing corrosion of the metal structure catalyst layer (430). In addition, when the ceramic catalyst layer (410) is included in a volume ratio of more than 15%, the amount of the metal structure catalyst layer (430) may decrease, thereby lowering the heat transfer efficiency through the metal structure. Accordingly, the efficiency of hydrogen gas production from ammonia gas may decrease.

[0062] Looking more closely at the reaction tube (200) including the above-described catalyst layer (250), the reaction tube (200) may have a double-tube structure including a reaction section inner tube (220) and a reaction section outer tube (210) surrounding the reaction section inner tube (220). By forming the reaction tube (200) with a double-tube structure, the length of the reaction tube (200) can be increased while preventing heat leakage, thereby allowing the reactants and the catalyst layer (400) to react in a wider area. In addition, a more compact hydrogen production reactor can be provided.

[0063] Figure 4 is a cross-sectional view illustrating the structure of a hydrogen production reactor according to another embodiment of the present invention. According to an embodiment such as Figure 4, the configuration of the heating unit (300) may be implemented as a structure separate from the reaction tube (200).

[0064] Referring to FIG. 4, the heating unit (300) may be provided spaced apart from the reaction tube (200), the catalyst layer (400), and the preheating unit (500). According to the present embodiment, the housing (100) may include a first housing (110), a second housing (130), and a connection unit (150). The second housing (130) may be formed at a lower height than the first housing (110), and the second housing (130) may be provided in a form in which it is located on one side of the lower portion of the first housing (110) and connected through the connection unit (150).

[0065] The heating unit (300) may be provided on the second housing (130). That is, heat provided from the heating unit (300) may be transferred through the connection unit (150) and introduced into the lower portion of the reaction tube (200).

[0066] Above, the description of the reaction tube (200), catalyst layer (300), and preheating section (500) overlaps with that described in Fig. 1, so it is omitted here.

[0067] Figure 5 is a cross-sectional view of a reaction tube included in a hydrogen production reactor according to another embodiment of the present invention.

[0068] Referring to FIG. 5, the ceramic catalyst layer (410) may be provided spaced apart from the metal structure catalyst layer (430). Specifically, the ceramic catalyst layer (410) may be provided outside the reaction tube (200), and the metal structure catalyst layer (430) may be provided inside the reaction tube (200) spaced apart from the ceramic catalyst layer (410).

[0069] As described above, the ceramic catalyst layer (410) and the metal structure catalyst layer (430) may be provided spaced apart from each other. In this case, by designing the ceramic catalyst layer (410) to first encounter the reactant and then encounter the metal structure catalyst layer (430), the corrosion prevention effect described above can be obtained.

[0070] When the ceramic catalyst layer (410) and the metal structure catalyst layer (430) are provided separately, the degree of freedom in reactor design can be improved. In addition, since the ceramic catalyst layer (410) is provided outside the reaction tube (200), the ceramic catalyst layer (410) can be easily replaced.

[0071] The reaction material supplied to the ceramic catalyst layer (410) can be provided in a preheated state, so that even if the ceramic catalyst layer (410) is outside the reaction tube (200), the reaction of producing hydrogen from ammonia can be performed without a problem. In addition, since the reaction material, whose ammonia concentration is reduced by the reaction occurring in the ceramic catalyst layer (410) provided outside the reactor, is provided to the metal structure catalyst layer (430), corrosion of the metal structure catalyst layer (430) due to ammonia can be prevented.

[0072] The present invention also provides a hydrogen system comprising the hydrogen production reactor described above. The hydrogen system may further include a component for utilizing the produced hydrogen. For example, hydrogen produced using the hydrogen production reactor of the present invention in a hydrogen system can be used as fuel for fuel cells or hydrogen vehicles, and thus can be applied to hydrogen charging stations. Therefore, a hydrogen system comprising the hydrogen production reactor of the present invention can be used to generate electricity.

[0073] The configuration of a hydrogen production reactor according to one embodiment of the present invention has been described above. Below, the advantageous effects of a hydrogen production reactor according to one embodiment of the present invention will be examined through comparative experimental data.

[0074]

[0075] Experimental Example 1. Ammonia Conversion Rate Evaluation

[0076] In order to evaluate the ammonia conversion rate according to the filling material filled in the preheating section (500), a hydrogen production reaction using ammonia was performed for a preheating section filled with an oxide including magnesium oxide and a preheating section filled with alumina balls. The experiment was performed at a reaction temperature of approximately 500°C, atmospheric pressure, and GHSV of 10,000 h. -1 It was performed under the conditions. The experiment used an ammonia decomposition reactor equipped with a reaction tube with a diameter of 1 inch. And, ruthenium (Ru) was used as the catalyst particle included in the catalyst layer, and the catalyst layer filled in the reaction tube was filled to a height of about 10 mm, and the filler filled in the preheating section was filled to a height of 50 mm. Here, the oxide containing magnesium oxide used was magnesium aluminate spinel (MgAl2O4). The magnesium aluminate spinel (MgAl2O4) and alumina balls each had a diameter of about 3 mm.

[0077] FIG. 6 is a diagram illustrating the effect when the preheating section of the present invention is filled with an oxide containing magnesium oxide. In addition, below shows the ammonia conversion rate according to FIG. 6.

[0078] NH3 conversion rate (%) Reaction elapsed time 0h5h10h20h30h40h45h(a)68.571.171.371.572.072.372.4(b)67.565.563.862.561.360.660.4

[0079] In Fig. 6, (a) is a graph showing the ammonia conversion rate when the preheating section according to the present invention is filled with MG30 pellets, and (b) is a graph showing the results of an experiment using alumina balls that were filled in the existing preheating section. Referring to Fig. 6 and , the ammonia conversion rate of the alumina balls that were generally filled in the existing preheating section gradually decreased as the reaction time increased. In other words, it was confirmed that the alumina balls reacted with high-temperature ammonia.

[0080] On the other hand, when the preheating section is filled with MG30 pellets, it can be confirmed that the ammonia conversion rate does not decrease as the reaction time increases, but rather increases.

[0081]

[0082] Experimental Example 2. Catalyst layer corrosion test

[0083] To determine whether the catalyst layer is corroded in the hydrogen production reaction using ammonia, the hydrogen production reaction using ammonia was performed on catalyst layers with volume ratios of 0%, 5%, 10%, and 15% of the ceramic catalyst layer. The experiment was conducted at a reaction temperature of approximately 700°C, atmospheric pressure, and GHSV of 5,000 h. -1 It was performed under the conditions of , and ruthenium (Ru) was used as the catalyst particle included in the catalyst layer.

[0084] Figure 7 is an image showing the corrosion pattern according to the amount of ceramic catalyst layer included in the catalyst layer.

[0085] Figure 7 (a) shows the appearance of the catalyst layer before the reaction, and Figures 7 (b), (c), (d), and (e) show the appearance after the reaction when the amount of the ceramic catalyst layer is 0%, 5%, 10%, and 15% by volume, respectively.

[0086] First, referring to (a) of Fig. 7, it can be confirmed that the catalyst layer exhibits a porous form before the reaction. Next, referring to (b) of Fig. 7, it can be confirmed that in cases where a ceramic catalyst layer is not provided, the form of the catalyst layer is deformed or the catalyst layer is lost from the top after the reaction due to corrosion. In contrast, in cases of (c), (d), and (e) where a ceramic catalyst layer is included at 5% to 15%, it can be confirmed that the form of the catalyst layer is relatively intact after the reaction. In particular, in the case of (e) of Fig. 7, it can be confirmed that no deformation of the catalyst layer is observed with the naked eye before or after the reaction.

[0087] Therefore, it can be seen from the comparative results in Fig. 7 that corrosion can be prevented by providing a ceramic catalyst layer.

[0088]

[0089] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single entity may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

[0090] The scope of the present invention is indicated by the claims set forth below, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims

1. In a hydrogen production reactor that produces hydrogen by decomposing ammonia, Housing and, At least one reaction tube provided inside the housing and into which a reactant containing ammonia is introduced through an inlet; A heating unit for providing heat to the above reaction tube, A preheating section is provided in the above reaction tube and is extended in one direction; It is located downstream of the above preheating section and includes a catalyst layer extending in one direction, A hydrogen production reactor, characterized in that the above preheating section is filled with an oxide including magnesium oxide (MgO).

2. In paragraph 1, The above preheating part, Magnesium aluminate spinel (MAS, MgO-Al 2 O 3 ) is filled with an oxide containing hydrogen.

3. In paragraph 1, The above preheating part, A hydrogen production reactor further comprising silicon carbide (SiC) and a metal filler.

4. In paragraph 3, A hydrogen production reactor, characterized in that the metal filler is at least one selected from the group consisting of tungsten, nickel, iron, cobalt, chromium, molybdenum, manganese, aluminum, and copper.

5. In paragraph 1, The above reaction tube, A hydrogen production reactor characterized by being provided with a single tube or a double tube structure consisting of a reaction section inner tube and a reaction section outer tube surrounding the reaction section inner tube.

6. In paragraph 1, The catalyst layer comprises at least one of a ceramic catalyst layer and a metal structure catalyst layer, A hydrogen production reactor, characterized in that the ceramic catalyst layer is arranged at the lower portion of the preheating section.

7. In paragraph 6, In the direction of inflow of the reactants, the ceramic catalyst layer and the metal structure catalyst layer are provided in the order of the ceramic catalyst layer - the metal structure catalyst layer. A hydrogen production reactor, characterized in that the reactant flows into the metal structure catalyst layer through the ceramic catalyst layer.

8. In paragraph 6, The above ceramic catalyst layer is provided outside the reaction tube, A hydrogen production reactor, characterized in that the metal structure catalyst layer is provided inside the reaction tube and spaced apart from the ceramic catalyst layer.

9. In paragraph 6, The above ceramic catalyst layer is made of alumina (Al 2 O 3 ), silicon carbide (SiC), cordierite, and magnesium oxide (MgO) as a carrier, A hydrogen production reactor characterized by comprising an active metal provided on the carrier.

10. In paragraph 9, A hydrogen production reactor, characterized in that the active metal comprises at least one selected from the group consisting of ruthenium (Ru), nickel (Ni), iron (Fe), cobalt (Co), and rhodium (Rh).

11. In paragraph 6, A hydrogen production reactor, characterized in that the ceramic catalyst layer included in the catalyst layer is included in a ratio of 5 to 15% with respect to the total volume of the catalyst layer.

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