KR20240000215A - Catalytic reactor and preparation method for bubbler for the catalytic reactor - Google Patents

Abstract

The present invention discloses a catalytic reaction device and a method of manufacturing a bubbler for the catalytic reaction device. The catalytic reaction device of the present invention is a molten alloy catalyst reaction device, and includes a bubbler that supplies raw material gas in the form of bubbles within the molten alloy catalyst, and the bubbler is arranged in a single-layer closest packing structure. A ceramic particle array comprising spherical ceramic particles and a ceramic coating layer formed on at least one of the upper and lower sides of the ceramic particle array, and a ceramic coating layer between three adjacent ceramic particles. It is characterized by the formation of pores by.

Description

Method for manufacturing a catalytic reaction device and a bubbler for a catalytic reaction device {CATALYTIC REACTOR AND PREPARATION METHOD FOR BUBBLER FOR THE CATALYTIC REACTOR}

The present invention relates to a catalytic reaction device that effectively produces carbon and hydrogen from natural gas by injecting natural gas in the form of bubbles into a high-temperature molten metal alloy catalyst, and a method of manufacturing a bubbler that generates natural gas in the form of bubbles in the catalytic reaction device. will be.

As the demand for hydrogen increases along with the demand for a hydrogen economy, interest in hydrogen production processes that can suppress CO ₂ emissions is increasing. The demand for hydrogen from existing industries is largely met by the well-established methane reforming process. However, increasing interest in global climate change has led to the need to develop new processes that can reduce greenhouse gas emissions such as CO ₂ . In this respect, catalytic methane pyrolysis appears to be one of the promising green technologies in that the ultimate final reaction products are solid carbon and hydrogen gas.

A recent techno-economic analysis of hydrogen production methods with low _CO2 emissions found that methane pyrolysis is more economical than electrochemical water splitting using commercial renewable energy and vapor methane using carbon capture and sequestration (CCS). It has been suggested that it can also compete with reforming (SMR). The Levelized Cost of Hydrogen is estimated to be about 1.76$/kg H ₂ on average, which is not only for electrolysis (6.79??12.00$/kg H ₂ ) but also for SMR using CCS (2.09 $/kg H ₂ ) is superior.

Methane pyrolysis generally requires high temperatures (> 1200 °C) to overcome the reaction rate limitations associated with the high activation energy of C-H bond dissociation (~ 415 kJ/mol), but thermodynamically, due to the entropic contribution, above 300 °C. Spontaneous reaction is possible, and at temperatures above 1000℃, more than 97% can be converted to hydrogen and carbon. It can be converted. Therefore, if the process temperature can be lowered to an industrially accessible range of 1000°C or less without significantly sacrificing the overall conversion rate by using an appropriate catalyst with high activity and long-term stability, it can be developed as an industrial process for large-scale hydrogen production. In this regard, the recent renewed interest in liquid metal alloy catalysts suggests that molten metal, which does not dissolve carbon, can spontaneously separate from the solid by-product carbon and recycle in the molten state, providing long-term catalytic activity and stability as long as the molten phase is maintained. It looks attractive in that it exists.

In liquid metal alloy catalysts, methane bubbles (or methane bubbles) are typically filled with a molten alloy catalyst consisting of at least two components, such as a low melting point metal (e.g. Sn, Bi) and a catalytically active transition metal (e.g. Ni, Cu). pass through the pillar. Recent studies have shown that Bi-Ni based melts exhibit the best catalytic activity. The conversion of CH ₄ to H ₂ occurs when methane bubbles pass through the liquid phase at a temperature range of about 800 to 1000°C. Low melting point metals (Bi, Sn, etc.) have a limited role as catalysts, but act as efficient heat transfer media for thermal methane pyrolysis. In addition, at temperatures below 1000°C, transition metals such as Ni and Cu do not melt spontaneously, but can be dissolved in molten liquid metals such as Bi or Sn to create a homogeneous liquid alloy phase, and the liquid phase in this molten state The alloy can act as a catalyst for CH ₄ dissociation with a low activation energy barrier. In these catalytic systems, the catalytic reaction is believed to occur primarily at the gas-liquid interface between the gaseous reactants in the form of bubbles and the liquid alloy.

Typically, large surface areas and long residence times are considered to improve net conversion in a given liquid catalyst system. The vertical length of the catalyst system and the rate at which the bubbles rise determine the residence time of the bubbles, while the size and flow rate of the bubbles determine the total surface area of the liquid catalyst with which the bubbles contact. Small bubbles tend to rise at a slow rate, resulting in long residence times, and a large contact or surface area is achieved due to the increased surface-to-volume ratio. Studies investigating the effect of bubble size in molten alloy systems have not been reported much, despite the fact that they are very important in determining reaction rate parameters (or reaction rate constants), which are important for understanding the catalytic role of molten alloys.

The density (5000 - 9000 kg/m ³ ) of common catalytic metals and low melting point metals is generally large and the viscosity is about 0.8 - 1.2 mPa·s, so commonly used raw materials with a size of several millimeters (1 - 3 mm) When a gas inlet is used, bubbles with a large diameter of approximately 10 mm are generated. The generated bubbles tend to rise quickly (usually 30 - 50 cm/s), so when the molten metal catalyst has a height of about 10 - 20 cm, it has a short reaction residence time of less than 0.5 seconds.

In general, reducing the size of the bubbles can improve the reaction conversion rate by (1) improving the cross-sectional area of contact with the liquid catalyst and (2) lengthening the reaction residence time (reducing the rate of rise); however, by reducing the size of the gas, the reaction conversion rate can be improved. Controlling and injecting small bubbles into a high-temperature liquid catalyst is not an easy task. To create small bubbles, a material such as a bubbler with small pores can be used as a bubble generator, but in this case, the small bubbles created on the surface of the bubble stone are affected by the physical properties (high density, surface tension) of the liquid catalyst. 1) agglomeration occurs between neighboring bubbles and they grow into large bubbles, or (2) as the raw material gas passes between pores measuring tens to hundreds of μm in the blister stone, methane decomposes on the surface of the blister stone made of high-temperature ceramic material and carbon is deposited. The operation of the reactor may stop due to blocking the pores.

One purpose of the present invention is to inject natural gas in the form of bubbles into a high-temperature liquid molten alloy catalyst, 1) to form small bubbles of tens to hundreds of μm in size, and 2) to form bubbles in the bubble generation step. 3) to minimize the contact cross-sectional area between the natural gas and the ceramic bubbler during the process of generating bubbles, and 4) to prevent carbon from depositing in the pores and blocking the pores. 5) To provide a catalytic reaction device and a bubbler for the catalytic reaction device that can prevent liquid molten alloy from flowing down and blocking pores.

A catalytic reaction device for one purpose of the present invention includes a reaction chamber having an interior space and configured to control the temperature of the interior space, a molten alloy catalyst disposed in the interior space of the reaction chamber, and disposed in the interior space of the reaction chamber. , a bubbler provided at the lower end of the molten alloy catalyst to supply raw material gas into the molten alloy catalyst in the form of bubbles, and a gas injection part for injecting raw material gas into the bubbler, and the molten alloy catalyst reacts with the raw material gas to produce and a gas outlet for recovering the product, wherein the bubbler includes a ceramic particle array including spherical ceramic particles arranged in a single-layer closest packing structure, and an upper side of the ceramic particle array and It includes a ceramic coating layer formed on one or more of the lower sides, and the pores formed by the ceramic coating layer are spaced at a certain distance in the empty space between the ceramic particles having a regular arrangement in the densest stacked structure, and the size of the pores is controlled. It is characterized by being arranged in a shape.

In one embodiment, the ceramic particles and the ceramic coating layer may each be formed of one or more materials selected from the group consisting of SiO ₂ , Al ₂ O ₃ , and ZrO ₂ .

In one embodiment, the size of the ceramic particles may be 0.3 mm to 1.0 mm.

In one embodiment, the diameter of the pores may be 30 μm to 200 μm, and the spacing of the pores may be 1 mm to 10 mm.

In one embodiment, the size of the bubble may be 50 to 500 μm.

In one embodiment, the bubbler further includes a porous support, and the porous support may be provided to support the ceramic particle array and the ceramic coating layer.

In one embodiment, the gas injection unit is disposed at the lower part of the reaction chamber and includes a preheating unit capable of preheating the raw material gas injected into the bubbler, and the raw material gas is preheated at the lower part of the reaction chamber to form the bubble. It can be injected as:

In one embodiment, the gas injection unit is disposed at an upper part of the reaction chamber and includes a gas inlet pipe formed to penetrate the inside of the reaction chamber, and the raw material gas bubbles through the gas inlet pipe at the upper part of the reaction chamber. It can be injected as:

Another object of the present invention is a method of manufacturing a bubbler for a catalytic reaction device, which includes a first step of forming a ceramic particle array with a single-layer, densely packed structure using spherical ceramic particles, and the ceramic particles using a ceramic paste. A second step of forming a ceramic coating layer on at least one of the upper and lower sides of the array, wherein during the second step, a space between three adjacent ceramic balls among the ceramic particles is formed by the ceramic coating layer. It is characterized by the formation of pores.

In one embodiment, the ceramic particles and the ceramic paste are each formed of one or more materials selected from the group consisting of SiO ₂ , Al ₂ O ₃ and ZrO ₂ ,

In one embodiment, the size of the ceramic particles may be 0.3 mm to 1.0 mm.

In one embodiment, during the second step, the diameter of the pores formed may be 30 μm to 200 μm, and the spacing of the pores may be 1 mm to 10 mm.

According to the present invention, the size and spacing of the pores of the bubbler are easily controlled with a ceramic coating layer, thereby preventing agglomeration between neighboring bubbles and facilitating the creation of small bubbles. Small-sized bubbles can provide a high conversion rate of raw material gas by maximizing the contact cross-sectional area of the interface between the bubbles and the liquid catalyst. In addition, the unique structure of the ceramic coating layer minimizes the cross-sectional area of contact between the raw material gas and the bubbler compared to the prior art, preventing the problem of carbon decomposed as the raw material gas passes between the pores of the bubbler being deposited on the pores of the bubbler. . Additionally, the unique structure of the ceramic coating layer and the difference in surface tension from the liquid catalyst help prevent the liquid catalyst from seeping into the pores. Therefore, the catalytic reaction device of the present invention can provide a high conversion rate and a stable reaction for a long time under the same conditions (same reactor, catalyst, amount of raw material gas, etc.) compared to the prior art.

1 and 2 are diagrams for explaining a catalytic reaction device according to an embodiment of the present invention.
Figures 3 and 4 are diagrams to explain the bubbler of the catalytic reaction device according to an embodiment of the present invention and the concept of forming bubbles using the bubbler.
Figure 5 is an image showing a portion of a bubbler and a catalytic reaction device according to an embodiment of the present invention.
Figure 6 is a graph showing the correlation between the size and rising speed of bubbles generated in a catalytic reaction device according to an embodiment of the present invention.
Figure 7 is a diagram for observing the shape of bubbles formed through a bubbler through distilled water before reacting with a high-temperature molten alloy catalyst using a catalytic reaction device according to an embodiment of the present invention. (a) shows the case of using only the quartz tube, (b) and (c) shows the case of using the bubbler according to the embodiment of the present invention, respectively. In the case of (b), the size of the pores is increased to produce large bubbles on average (~ mm ) is an example of creation, and (c) shows a case where the size of the pores was controlled to be small (< 200 um) and a large amount of bubbles with a size of 0.6 mm or less were generated.
Figure 8 shows how the time the bubbles remain in the liquid phase, the total cross-sectional area of the bubbles present in the liquid phase, and the product change when the size of the bubbles is controlled. The height of the liquid catalyst is about 12 cm, and the gas flow rate is 5 - 200 sccm. Indicates the results calculated under conditions within the range. Looking at (c), it can be seen that when the flow rate is 10 sccm and the size of the bubbles decreases from 2 mm to 0.5 mm, the product of the total surface area and residence time increases by about 100 times.
Figure 9 is a diagram evaluating the conversion rate of methane to hydrogen using a catalytic reaction device according to an embodiment of the present invention. (a) shows an example of a catalytic reaction device in which methane thermal decomposition is in progress under actual reaction conditions, and (b)-(c) show an example of a device (b) using only a quartz tube and an embodiment of the present invention, respectively. When using a device (c) including a bubbler, a graph showing the change in methane pyrolysis conversion rate over time is shown.
Figure 10 is a diagram illustrating an example when a blister stone with general porous pores is used as a bubbler. The pores of a typical porous blister stone (a) are not uniform in size, (b) the bubbles coming out of relatively large pores are clumped together, and (c) show an example of a large number of bubbles more than 10 times larger than the pore size. The drawing is an example showing the importance of controlling the size of pores and arranging them at a certain interval or more, as in the present invention. When applied to a catalytic reaction using commercially available porous blisters, there is no effect of improving the conversion rate of methane under a molten catalyst at 1000 degrees Celsius (limited to about 25% or less), and during long-term reaction, carbon is deposited in the pores and blocks the pores, making it difficult to proceed with the process. You can. Figure 10 is a diagram for comparative evaluation with an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. Since the present invention can be subject to various changes and have various forms, specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention. While describing each drawing, similar reference numerals are used for similar components.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the presence of features, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features or steps. , it should be understood that it does not exclude in advance the possibility of the existence or addition of operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless explicitly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

1 and 2 are diagrams for explaining a catalytic reaction device according to an embodiment of the present invention.

Referring to FIGS. 1 and 2, the catalytic reaction device 100 of the present invention includes a reaction chamber 200 having an internal space and configured to control the temperature of the internal space, and is disposed in the internal space of the reaction chamber 200. A molten alloy catalyst, a bubbler 400 disposed in the inner space of the reaction chamber 200 and provided at the lower end of the molten alloy catalyst 300 to supply raw material gas in the form of bubbles into the molten alloy catalyst 300. And a gas injection unit 500 that injects raw material gas into the bubbler 400 and a gas discharge unit 600 that recovers a product generated by the reaction between the molten alloy catalyst 300 and the raw material gas.

The catalytic reaction device 100 may include two embodiments depending on the location of the gas injection unit 500 that introduces the raw material gas into the reaction chamber 200.

Referring to FIG. 1, the catalytic reaction apparatus 100 according to an embodiment of the present invention includes a reaction chamber 200 and a gas injection unit 500 disposed below the reaction chamber 200. When the gas injection unit 500 is disposed below the reaction chamber 200, the gas injection unit 500 may include a preheating unit for preheating the raw material gas. The raw material gas may be preheated by the preheating unit and injected into the bubbler 400. Additionally, the gas injection unit 500 may further include a control unit capable of controlling the flow rate of the raw material gas.

Referring to FIG. 2, the catalytic reaction device 100 according to another embodiment of the present invention includes a reaction chamber 200 and a gas injection unit 500 disposed above the reaction chamber 200. When the gas injection unit 500 is disposed at the upper part of the reaction chamber 200, it may include a gas inlet pipe 510 formed to penetrate the inside of the reaction chamber 200. The raw material gas may be injected from the upper part of the reaction chamber 200 through the gas inlet pipe 510 into the bubbler 400 disposed at the lower end of the chamber. In this case, the raw material gas may be indirectly preheated or heated while passing through the gas inlet pipe 510 by the molten alloy catalyst 300 in the reaction chamber 200. In addition, the gas injection unit 500 may be further equipped with a flow rate control unit that controls the flow rate of the gas so that the raw material gas does not remain in the gas inlet pipe 510 for a long time and a temperature control unit that can adjust the temperature range.

The molten alloy catalyst 300 may be made of a material containing a mixture of a low melting point metal and a catalytically active transition metal. For example, the low melting point metal may be any one selected from Sn, Bi, Sb, Ga, In, etc., and the transition metal may be any one selected from Ni, Co, Fe, etc. Additionally, the molten alloy catalyst 300 may additionally include materials such as Li, K, Ca, Mg, and Zn as additives.

In one embodiment, the molten alloy catalyst 300 may include a mixture of Sn and Ni, and preferably may include a mixture in which Sn and Ni are mixed at a molar ratio of 8:2. In one embodiment, when the raw material gas contains methane (CH ₄ ) and the molten alloy catalyst contains a mixture of Sn and Ni, the raw material gas can be decomposed into carbon and hydrogen through the device of the present invention. there is.

The bubbler 400 is configured to supply raw material gas in the form of bubbles 700 into the molten alloy catalyst 300 so that it can react with the molten alloy catalyst 300, and includes pores. The raw material gas may flow into the molten alloy catalyst 300 in the form of bubbles 700 while passing through the pores.

In one embodiment, the bubbler 400 further includes a porous support, and the porous support may be provided below the ceramic particle array and the ceramic coating layer to support them. The porous support may be formed of ceramic materials such as SiO ₂ , Al ₂ O ₃ and ZrO ₂ .

A detailed description of the bubbler 400 will be provided below with reference to FIGS. 3 and 4.

The raw material gas bubble 700 is formed as the raw material gas passes through the bubbler 400, and may have a size (size of diameter) of less than several mm. Preferably, the raw material gas bubble 700 is It may be 50 to 500 μm. In the area where the diameter of the raw material gas bubble 700 is less than 1 mm, as the diameter decreases, the rising speed decreases, and the reaction time with the molten alloy catalyst 300 increases, and the reaction time for the raw material gas to decompose (melt) Due to the effect of increasing the residence time in the catalyst and the effect of increasing the total reaction cross-sectional area, the reaction rate can be increased. Above 1 mm, the increase in rising speed as the bubble size increases is limited, but the total reaction cross-sectional area decreases, which can have the effect of reducing the reaction speed. Therefore, the smaller the bubble size is in the region of 1 mm or less, the easier it is to maximize the conversion rate. However, if the bubble size is too small, the rising speed is too low and the bubble size increases due to the effect of agglomeration between bubbles during the residence time in the liquid catalyst. , the synergistic effect in terms of reaction speed due to bubble size control may be limited. Therefore, bubbles with a diameter of about 50 to 500 μm may be the optimal diameter size for maximizing the reaction rate.

Figures 3 and 4 are diagrams for explaining the bubbler of the catalytic reaction device and the concept of forming bubbles using the bubbler according to an embodiment of the present invention.

First, referring to FIG. 3, the bubbler 400 of the catalytic reaction device 100 of the present invention is a ceramic particle array having spherical ceramic particles arranged in a single-layer closest packing structure ( 410) and a ceramic coating layer 420 formed on at least one of the upper and lower sides of the ceramic particle array 410, and pores are formed between three adjacently arranged ceramic particles by the ceramic coating layer. (430) is characterized in that it is formed.

Referring to (a) of FIG. 3, the ceramic particle array 410 may include the most dense and dense structure among arrays in which ceramic particles can be composed of a single layer. In one embodiment, the ceramic particles may be formed of one or more materials selected from the group consisting of SiO ₂ , Al ₂ O ₃ and ZrO ₂ . The ceramic particles may have a size of 0.3 to several millimeters.

Referring to (b) of FIG. 3, the ceramic coating layer 420 may be formed on one or more of the upper side and the lower side. The ceramic coating layer 420 has minimal surface tension due to the ceramic material, thereby preventing wetting with the high-temperature molten alloy catalyst 300 having high surface tension, which causes the molten alloy catalyst 300 to act as a bubbler. (400) Provides the effect of preventing flowing down. In one embodiment, the ceramic coating layer 420 may be formed of one or more materials selected from the group consisting of SiO ₂ , Al ₂ O ₃ and ZrO ₂ .

The pores 430 may be formed by coating the space formed between three ceramic particles arranged adjacent to each other with the ceramic coating layer 420.

[Equation 1]

Referring to Equation 1 above and (b) of FIG. 3, when the radius of the ceramic particle is R, it can be seen that the radius r of the pore 430 is 0.155R. Therefore, the radius r of the pores 430 formed in the present invention can be controlled within a range of less than 0.155R. For example, when using ceramic particles with a diameter of 2 mm (R = 1 mm), the pore radius can be controlled to less than 0.155 mm depending on the thickness of the ceramic coating layer.

In one embodiment, the spacing of the pores 430 may be controlled by the size of the ceramic particle, and the radius (r) of the pore may be controlled by the thickness of the ceramic coating. The ratio of the distance (1.155R) to the size (2r) of the pores 430 can be controlled at a minimum of (1.155R/2×0.155R = 3.7), and preferably by controlling the thickness of the ceramic coating, usually 10 It can be controlled to have a value equal to or higher. In order to prevent the bubbles of the raw material gas formed by the pores 430 from clumping together, the pores 430 may have a diameter of 30 to 200 um, and the spacing between the pores 430 is 0.5 mm to 5 mm. It can be mm.

Referring to (a) of FIG. 4, the size of the pores 430 of the present invention can be easily changed by controlling the thickness of the ceramic coating layer 420. In one embodiment, the diameter of the pores 430 may be 200 μm or less, preferably 30 μm to 200 μm.

Referring to (b) of FIG. 4, the raw material gas bubble of the present invention is formed when the raw material gas passes through the pore 430. The pore 430 of the present invention is formed by the ceramic coating layer 420, so that the raw material gas bubble passes through the pore 430. Compared to the pores of the technological bubbler (400), the contact area between the raw material gas and the pores is very small, effectively preventing the problem of the raw material gas decomposing on the pore surface (ceramic material) forming bubbles and carbon being deposited in the pores. It is possible to prevent the liquid alloy from seeping into the pores by minimizing the contact cross-sectional area between the liquid molten alloy, which has high surface tension, and the pore space.

The manufacturing method of the bubbler 400 for the catalytic reaction device 100 of the present invention includes a first step of forming a ceramic particle array with a single-layer closest packing structure using spherical ceramic particles, and A second step of forming a ceramic coating layer 420 on one or more of the upper and lower sides of the ceramic particle array 410 using a ceramic paste, and during the second step, adjacent ones of the ceramic particles A pore 430 is formed between the three arranged pores by the ceramic coating layer 420.

Since the configuration of the bubbler 400 is substantially the same as the configuration of the catalytic reaction device 100 of the present invention described above, redundant detailed descriptions thereof will be omitted, and the following will focus on the manufacturing method.

In one embodiment, the formation of the ceramic coating layer 120 in the second step may be performed by spraying ceramic paste onto the ceramic particle array 410. For example, it may be performed through a method of spraying using a nozzle at room temperature, a low-temperature spray coating method, or an ultrasonic spray coating method. In the present invention, the coating spraying method is not specifically limited, but preferably, the ceramic coating layer 120 can be formed by performing the room temperature spray coating method, and through this, smooth pores 430 can be formed. In one embodiment, ceramic coating may be performed using a colloidal liquid paste in which ceramic powder is dispersed in an organic solvent. By controlling the viscosity and injection amount of the ceramic paste, the size of the pores 430 formed between ceramic particles can be controlled. To improve the structural stability of the pores 430 and lower the surface tension, a ceramic coating layer 420 with a micrometer pattern may be formed on the top of the pores.

In one embodiment, the pores 430 formed during the second step may have a diameter of 200 μm or less, preferably 30 μm to 200 μm.

In one embodiment, after performing the second step, a third step of drying the ceramic coating layer 420 may be performed. By controlling the times of the second and third steps, the structural stability and surface characteristics of the pores 430 of the present invention can be easily controlled for application to the high-temperature liquid catalyst process.

The methane thermal decomposition catalytic reaction process using the catalytic reaction device 100 and the bubbler 400 for the catalytic reaction device 100 of the present invention has a wider contact cross-sectional area and longer residence time between the raw material gas bubbles and the liquid catalyst compared to the prior art. By providing , the conversion rate of raw material gas can be significantly increased.

Hereinafter, the methane thermal decomposition catalytic reaction process using the catalytic reaction device 100 and the bubbler 400 for the catalytic reaction device 100 of the present invention will be described in more detail through specific examples and comparative examples. However, the embodiments of the present invention are only some embodiments of the present invention, and the scope of the present invention is not limited to the following examples.

Example

Figure 5 is an image showing the core part of the bubbler 400 for the catalytic reaction device 100 manufactured according to an embodiment of the present invention.

Referring to Figure 5, (a)-(b) are examples of a bubbler manufactured with reference to the example of the bubbler 400 manufactured according to an embodiment of the present invention, and zirconia particles (1.0, 0.5 and 0.3 mm), ceramic paste was applied to the upper side of the array, and pores whose size was controlled to 200 μm or less were formed in the space between zirconia particles arranged in the most densely packed structure. Figure 5(c) is an example of the catalytic reaction device 100 of the present invention constructed according to the method of Figure 2. The quartz tube to be used as the reaction chamber has a reaction inner diameter (I.D.) of 12 mm and an outer diameter ( A quartz tube with an O.D. of 16 mm was used, and the bubbler 400 manufactured above and the flow path (quartz tube) as the raw material gas injection part 500 were used to inject raw material gas from the top of the reaction chamber. ) was prepared by combining. The quartz tube used as the gas injection unit 500 had a length of 70 cm, an inner diameter (I.D.) of 2 mm, and an outer diameter (O.D.) of 6 mm.

Experimental Example 1

Figure 6 is an experimental result of the correlation between the size and rising speed of bubbles generated in the bubbler 400 for the catalytic reaction device 100 manufactured according to an embodiment of the present invention, in distilled water at room temperature and melt at 1000°C. This is a graph showing the rising speed according to the bubble size of methane gas in each case on the catalyst.

Referring to FIG. 6, as the size of the raw material gas bubbles increases up to about 1 -2 mm, the tendency for the rising speed of the bubbles to increase has been experimentally verified, and beyond that, the rising speed is limited to bubbles of about 10 mm in size. It can be observed that it is limited at the level of 30 cm/s. In the area where the bubble size is 1 mm or less, the rising speed of the bubbles decreases as the bubble size becomes smaller. Therefore, in order to control the time for which the bubbles remain in the liquid molten alloy (residence time) so that the reaction conversion rate reaches the maximum, the bubbles must be controlled to reach the maximum. The size should be controlled to be less than about 0.5 mm. Through this experiment, the relationship between the residence time according to the actual bubble size can be experimentally obtained, and when the flow rate (mL/min) and the volume and height of the liquid molten catalyst are determined, bubbles are continuously created and destroyed in the liquid phase. The total reaction cross-sectional area (number of bubbles x bubble surface area) can be obtained from the number of bubbles maintained and the size of the bubbles. Catalytic activity can be determined depending on the composition of a given liquid catalyst, and when the catalyst activity is determined, the reaction conversion rate tends to increase in proportion to the product of the residence time and the total reaction cross-sectional area. Therefore, the reaction conversion rate can be dramatically improved by controlling the structure of the bubbler 400, which plays the role of controlling the size of bubbles and continuously supplying them to the molten catalyst.

Experimental Example 2

Figure 7 shows that methane gas is supplied to distilled water through the bubbler 400 before reacting with the high-temperature molten alloy catalyst 300 to verify the bubble generation characteristics of the catalytic reaction device 100 according to an embodiment of the present invention. This is a drawing for observing the bubble shape formed at this time. (a) is a case where only a quartz tube is used, and (b)-(c) is a case where a bubbler 400 manufactured according to an embodiment of the present invention is used. (b) shows a case where the bubbler 400 with relatively large pores was used, and (c) shows a case where the bubbler 400 with relatively optimized pore sizes was used.

Referring to FIG. 7, it is possible to compare experimental results of the size of bubbles generated under conditions where a constant flow rate of methane gas is actually flowed in distilled water. (a) In the case of a device that does not use the bubbler 400, it can be observed that very large bubbles (with a diameter of 6 - 10 mm) are formed, whereas (b) the size of the pores is not sufficiently controlled. In the case of a non-bubbler device, it can be observed that a large number of small-sized bubbles (1-3 mm in diameter, but not small enough) are formed. Compared to these, (c) when using the bubbler 400 manufactured according to an embodiment of the present invention, very small size (diameter 500 μm) is generated through the bubbler 400 having a pore diameter of 200 μm or less. - It can be seen that multiple bubbles (less than 600 μm) are formed. Therefore, through the embodiment of FIG. 7, it can be confirmed that the size of the bubbles can actually be controlled to 500 μm or less using the bubbler manufactured according to the embodiment of the present invention.

Experimental Example 3

Figure 8 calculates how the residence time (a), the total surface cross-sectional area (b), and the product of the residence time and surface cross-sectional area (c) of the bubbles in the molten alloy catalyst change according to the size of the bubbles when the size of the bubbles is controlled. The results are shown graphically. For the calculation, it was assumed that the height of the Sn-Ni catalyst was 12cm, the reaction conditions were 1000°C normal pressure conditions, the methane flow rate was varied in the range of about 5 - 200 sccm, and the pressure increase due to the height of the catalyst and the size of the flow rate were adjusted. Changes in bubble size according to bubble growth time and reaction conversion rate were also considered in the calculations. However, the shape of the bubble was assumed to be spherical, but in the case of bubbles larger than about 2 mm, the actual bubble shape deviates from a sphere, so the theoretical predictions may deviate from the experiment.

Referring to Figure 8, when the size of the bubble decreases from about 2 mm to about 0.5 mm, the product of the total reaction cross-sectional area and residence time can increase by about 100 times, thereby showing that the reaction rate can be improved to the thermodynamic maximum. .

Experimental Example 4

Figure 9 shows the case where the bubbler manufactured according to an embodiment of the present invention is applied to the gas injection part bubbler 400 of the catalytic reaction device 100, which is a high temperature molten alloy reaction furnace at 1000 degrees Celsius, and when it is not applied. This is a diagram evaluating the conversion rate of methane to hydrogen.

Figure 9 (a) shows an example in which the catalytic reaction device 100 including a bubbler 400 and a molten alloy catalyst injects methane gas in the form of bubbles under reaction conditions of 1000 ° C to proceed with the catalytic reaction, (b) )-(c) shows the results obtained through experiments on the change in conversion rate over time when the reaction is carried out using different bubblers (400) and compares them. In (b), the conversion rate was observed to be less than 20% in the case of the device using only the quartz tube excluding the bubbler (400), while (c) is the device of the present invention including the bubbler (400) and the quartz tube. It was observed that the conversion rate was approximately 90% or higher.

Experimental Example 5

Figure 10 does not use the bubbler 400 manufactured according to an embodiment of the present invention, but uses a general porous ceramic blister stone (with a complex structure of irregular pores of several to tens of μm in size) as the bubbler 400. This is a drawing for comparing and evaluating the bubbles created.

Referring to FIG. 10, (a) small droplets can be expected due to the smaller pore size in ordinary blister stones, but (b) in reality, the bubbles created on the surface of blister stones merge with each other, and the final bubble size is several mm in size. It can be confirmed experimentally that it is created in (c), and it can be seen that larger bubbles are created as the flow rate increases. Therefore, only by controlling both the irregular size and pore spacing and implementing it as a ceramic material can the size of bubbles be selectively created and the reaction conversion rate at the gas-liquid interface of a high-temperature liquid melt catalyst can be maximized. In the case of the catalytic reaction device 100 constructed using the bubbler 400 having the bubble generation characteristics shown in (b)-(c), a reactor of the same size as the embodiment of FIG. 9 and reaction conditions (normal pressure, When methane was reacted using the same molten alloy (SnNi) at 1000℃, a conversion rate of about 25% was obtained, which is due to limited control of bubble size (on average, bubbles with a size of several mm or more are mainly generated). There is. In addition, as methane passes through the complex maze-like pore structure, carbon is deposited inside the pores, resulting in pores becoming clogged within 10 to 20 hours. Therefore, this experimental result shows that the technology of spraying methane gas by controlling the size of the bubbles within the molten alloy catalyst by controlling the pore size and gap structure is a key element in enabling a high methane decomposition conversion rate and stable process operation for a long time. am.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art can make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the following patent claims. You will understand that it is possible.

100 Catalytic reaction device
200 reaction chamber
300 Molten alloy catalyst
400 bubbler
410 ceramic particle array
420 ceramic coating layer
430 Qigong
500 gas inlet
510 gas inlet pipe
600 gas outlet
700 raw material gas bubbles

Claims (12)

A reaction chamber having an internal space and configured to control the temperature of the internal space;
A molten alloy catalyst disposed in the inner space of the reaction chamber;
A bubbler disposed in the inner space of the reaction chamber and provided at a lower end of the molten alloy catalyst to supply raw material gas in the form of bubbles into the molten alloy catalyst; and
It includes a gas injection unit for injecting raw material gas into the bubbler and a gas discharge unit for recovering a product generated by the reaction of the molten alloy catalyst and the raw material gas,
The bubbler includes a ceramic particle array including spherical ceramic particles arranged in a single-layer, closest packing structure, and a ceramic coating layer formed on at least one of the upper and lower sides of the ceramic particle array. And, characterized in that pores are formed by the ceramic coating layer between three adjacently arranged ceramic particles.
Catalytic reaction device. According to paragraph 1,
The ceramic particles and the ceramic coating layer are each formed of one or more materials selected from the group consisting of SiO ₂ , Al ₂ O ₃ and ZrO ₂ ,
Catalytic reaction device. According to paragraph 1,
The size of the ceramic particles is 0.3 mm to 1.0 mm,
Catalytic reaction device. According to paragraph 1,
The diameter of the pore is 30 μm to 200 μm,
The spacing of the pores is 1 mm to 10 mm,
Catalytic reaction device. According to paragraph 1,
The size of the bubble is 50 to 500 μm,
Catalytic reaction device. According to paragraph 1,
The bubbler further includes a porous support,
The porous support is provided to support the ceramic particle array and the ceramic coating layer,
Catalytic reaction device. According to paragraph 1,
The gas injection unit is disposed at a lower portion of the reaction chamber and includes a preheating unit capable of preheating the raw material gas injected into the bubbler,
Characterized in that the raw material gas is preheated at the bottom of the reaction chamber and injected into the bubbler.
Catalytic reaction device. According to paragraph 1,
The gas injection unit is disposed at an upper part of the reaction chamber and includes a gas inlet pipe formed to penetrate the inside of the reaction chamber,
Characterized in that the raw material gas is injected into the bubbler through a gas inlet pipe at the top of the reaction chamber.
Catalytic reaction device. A first step of forming a ceramic particle array having a single-layer closest packing structure using spherical ceramic particles and at least one of the upper and lower sides of the ceramic particle array using ceramic paste. It includes a second step of forming a ceramic coating layer,
During the second step, pores are formed by the ceramic coating layer between three adjacent ceramic balls among the ceramic particles.
Method for manufacturing a bubbler for a catalytic reaction device. According to clause 9,
The ceramic particles and the ceramic paste are each formed of one or more materials selected from the group consisting of SiO ₂ , Al ₂ O ₃ and ZrO ₂ ,
Method for manufacturing a bubbler for a catalytic reaction device. According to clause 9,
The size of the ceramic particles is 0.3 mm to 1.0 mm,
Method for manufacturing a bubbler for a catalytic reaction device. According to clause 9,
During the second step, the diameter of the pores formed is 30 μm to 200 μm, and the spacing of the pores is 1 mm to 10 mm,
Method for manufacturing a bubbler for a catalytic reaction device.