Methane-reforming catalyst and method for producing same

Abstract

A method for producing a methane reforming catalyst according to one embodiment of the present application comprises the steps of: preparing a first solution including a precursor of a perovskite-based compound represented by chemical formula 1; preparing a second solution by adding a pore forming agent which is a hydrophilic oligomer or polymer to the first solution; and coating a support with the second solution and then performing a heat treatment process to produce a catalyst, wherein the viscosity of the second solution is 10 cP to 1,500 cP at 25℃.

Description

Catalyst for methane reforming and method for producing the same

[0001] This application claims the benefit of Korean Patent Application No. 10-2024-0047482, filed with the Korean Intellectual Property Office on April 8, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to a catalyst for methane reforming and a method for producing the same.

[0003] As part of efforts to reduce greenhouse gas emissions due to global warming, extensive research is underway on carbon dioxide conversion technologies. Carbon dioxide reforming, one such carbon dioxide conversion technology, involves reacting methane and carbon dioxide to produce a synthesis gas composed of hydrogen and carbon monoxide.

[0004] Syngas is a highly valuable material for development as a raw material for various downstream applications. Natural gas reforming reactions, which allow for the industrial production of synthesis gas (H2 / CO), can be broadly categorized into steam reforming, CO2 reforming, catalytic partial oxidation, autothermal reforming, and tri-reforming, as shown in Equations 1 through 5 below.

[0005] [Reaction Formula 1]

[0006] CH4+ H2O → 3H2+ CO △H = 226 kJ / mol

[0007] [Reaction Formula 2]

[0008] CH4+ CO2→ 2H2+ 2CO △H = 261 kJ / mol

[0009] [Reaction Formula 3]

[0010] CH4+ 0.5O2→ 2H2+ CO △H = -44 kJ / mol

[0011] [Reaction Formula 4]

[0012] autothermal reforming: Reaction 1 + Reaction 3

[0013] [Reaction Formula 5]

[0014] tri-reforming: Reaction 1 + Reaction 2 + Reaction 3

[0015] Meanwhile, various catalysts can be used in the above reforming process to enhance reforming activity. Among these, the use of precious metal catalysts in the reforming process offers the advantage of high hydrogen conversion efficiency from natural gas. However, the high cost of precious metal catalysts reduces economic feasibility.

[0016] Accordingly, nickel catalysts, which boast high hydrogen conversion efficiency and are relatively inexpensive, are primarily used in reforming processes. However, these catalysts face the problem of deactivation due to the carbon that inevitably forms on their surface.

[0017] Therefore, in this technical field, there is a need for the development of a catalyst that is resistant to carbon deposition and can be effectively applied to the methane reforming process.

[0018] The present application seeks to provide a catalyst for methane reforming and a method for producing the same.

[0019] One embodiment of this application is:

[0020] A step of preparing a first solution containing a precursor of a perovskite compound represented by the following chemical formula 1;

[0021] A step of preparing a second solution by adding a pore-forming agent, which is a hydrophilic oligomer or polymer, to the first solution; and

[0022] A step of manufacturing a catalyst by coating the second solution on a support and then performing a heat treatment process,

[0023] A method for producing a catalyst for methane reforming is provided, wherein the viscosity of the second solution is 10 cp to 1,500 cp at 25°C.

[0024] [Chemical Formula 1]

[0025] Sr 1-x A x Ti α B y O 3-δ

[0026] In the above chemical formula 1,

[0027] A is selected from Y, Sc, La and lanthanide series elements,

[0028] B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh,

[0029] x is a real number greater than or equal to 0 and less than 1,

[0030] y is a real number greater than or equal to 0 and less than 0.2,

[0031] δ is a real number greater than or equal to 0 and less than 1,

[0032] α is a real number greater than 0.8 and less than or equal to 1,

[0033] (x + y) > 0.

[0034] In addition, another embodiment of the present application is a catalyst for methane reforming, comprising: a support; and a coating layer provided on the support and including a perovskite compound represented by the chemical formula 1;

[0035] A methane reforming catalyst is provided, wherein the average porosity of the outermost surface layer of the methane reforming catalyst according to the following method 1 is 15% or more.

[0036] [Method 1]

[0037] At an arbitrary location on the outermost surface layer of the above methane reforming catalyst, an SEM (Scanning Electron Microscope) image is obtained at an acceleration voltage of 5 kV, a magnification of 10,000 times, and a resolution of 1,280×960 pixels, and then the porosity is calculated using the following mathematical formula 2. At this time, 20 SEM images are obtained at the arbitrary locations that do not overlap each other, and then the porosity according to each SEM image is calculated, and the average value thereof is evaluated as the average porosity (%).

[0038] [Equation 2]

[0039] Porosity (%) = (Total area of ​​pores in SEM image) / (Total area of ​​outermost surface layer in SEM image) × 100

[0040] According to one embodiment of the present application, a methane reforming catalyst can be formed in the form of a perovskite coating layer by directly coating the perovskite catalyst component represented by the chemical formula 1 onto a support without a separate binder. Accordingly, the methane reforming catalyst has the characteristic of increasing the active surface area.

[0041] In addition, the catalyst for methane reforming according to one embodiment of the present application can increase porosity by adding a pore-forming agent, which is a hydrophilic oligomer or polymer, to a first solution containing a precursor of a perovskite compound represented by the above chemical formula 1. Accordingly, the active surface area of ​​the catalyst for methane reforming can be increased, and the catalyst for methane reforming can exhibit high activity even at a high space velocity in the methane reforming reaction.

[0042] In addition, the method for manufacturing a catalyst for methane reforming according to one embodiment of the present application can increase the coating amount per time when coating the support with the second solution by ensuring that the viscosity of the second solution to which a pore-forming agent, which is a hydrophilic oligomer or polymer, is added satisfies 10 cp to 1,500 cp at 25°C.

[0043] FIG. 1 is a drawing showing a SEM (Scanning Electron Microscope) photograph of a catalyst for methane reforming according to Example 1 of the present application.

[0044] Figure 2 is a diagram showing the results of a porosity analysis of a catalyst for methane reforming according to Example 4 of the present application.

[0045] Figure 3 is a diagram showing the results of a porosity analysis of a catalyst for methane reforming according to Example 6 of the present application.

[0046] Fig. 4 is a diagram showing an SEM photograph of a catalyst for methane reforming according to Comparative Example 1 of the present application.

[0047] Figure 5 is a diagram showing the results of a porosity analysis of a catalyst for methane reforming according to Comparative Example 1 of the present application.

[0048] Fig. 6 is a diagram showing an SEM photograph of a catalyst for methane reforming according to Comparative Example 3 of the present application.

[0049] Hereinafter, the present specification will be described in more detail.

[0050] In this specification, when it is said that a member is located “on” another member, this includes not only cases where the member is in contact with the other member, but also cases where another member exists between the two members.

[0051] In this specification, when a part is said to "include" a certain component, this means that it may include other components, but not to the exclusion of other components, unless specifically stated otherwise.

[0052] Currently, catalysts widely used in the reformer field are generally powder catalysts and pellet-type support catalysts. While powder catalysts can exhibit excellent performance due to their excellent catalyst dispersion, they are difficult to directly use in industry. For example, when a reformer is operated using a powder catalyst, the catalyst exits together with the substances produced after the reaction. At this time, the powder catalyst may gradually accumulate in the outlet pipe, ultimately clogging the entire pipe. Therefore, there is a drawback in that powder catalysts cannot be used in commercial reformers used in industry.

[0053] Therefore, catalysts formed into pellets are currently used in commercial reformers. Due to limitations in mass transfer rates, their catalytic performance is inferior to that of powdered catalysts in terms of performance alone. However, they are used in an appropriately formed form, taking into account factors such as differential pressure and the flow rate within the reactor, as well as operational ease. However, in catalytic reactions, only the catalytic components on the surface that can come into contact with the reactants participate in the reaction. Therefore, pelletized catalysts have the disadvantage of making it difficult for the internal catalyst to participate in the reaction.

[0054] Accordingly, in this application, instead of the catalyst formed in the pellet form described above, a catalyst precursor was coated on a support to minimize catalyst use while achieving high performance was manufactured.

[0055] When coating a catalyst precursor onto a support, an appropriate amount of catalyst is required to optimize catalytic performance. This requires multiple repeated coatings. Because repeated coatings increase process costs, it's crucial to increase the amount per coating to reduce the number of repeated coatings.

[0056] The present inventors have confirmed that a catalyst having a specific structure with increased porosity of the coating layer can be manufactured by adding a pore-forming agent to a solution containing a precursor of a perosite compound represented by the above chemical formula 1 and coating the solution on a support. The pore-forming agent not only increases the surface area but also increases the viscosity, thereby improving the performance of the catalyst and reducing the process cost due to an increase in the amount of coating per unit.

[0057] A method for producing a catalyst for methane reforming according to one embodiment of the present application comprises the steps of: preparing a first solution containing a precursor of a perovskite compound represented by the following chemical formula 1; preparing a second solution by adding a pore-forming agent, which is a hydrophilic oligomer or polymer, to the first solution; and preparing a catalyst by coating a support with the second solution and then performing a heat treatment process, wherein the viscosity of the second solution is characterized by being 10 to 1,500 cps at 25°C.

[0058] [Chemical Formula 1]

[0059] Sr 1-x A x Ti α B y O 3-δ

[0060] In the above chemical formula 1,

[0061] A is selected from Y, Sc, La and lanthanide series elements,

[0062] B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh,

[0063] x is a real number greater than or equal to 0 and less than 1,

[0064] y is a real number greater than or equal to 0 and less than 0.2,

[0065] δ is a real number greater than or equal to 0 and less than 1,

[0066] α is a real number greater than 0.8 and less than or equal to 1,

[0067] (x + y) > 0.

[0068] In one embodiment of the present application, the support is a porous member that carries the catalyst component of the perovskite compound represented by the chemical formula 1 and has a plurality of pores on the surface. The support may include at least one selected from NiFeCrAl, NiCrAl, stainless steel, Inconel, SiC, and α-Al2O3, but is not limited thereto. In addition, the support is more preferably a metal foam containing NiCrAlFe or NiCrAl because it has high thermal conductivity.

[0069] The metal foam containing the above NiCrAlFe or NiCrAl is a support having various shapes, and has a small heat capacity and excellent heat transfer ability, so that it can be formed into a desired shape and used. The shape, size, etc. of the metal foam are not particularly limited, and the porosity of the metal foam can be 10% to 99%, and preferably 50% to 96%. In addition, the average pore size of the metal foam can be 150 ㎛ to 3,000 ㎛, 400 ㎛ to 2,000 ㎛, and 600 ㎛ to 1,700 ㎛. The metal foam can be appropriately manufactured by a person skilled in the art using a method known in the art, taking into consideration the material, pore size, porosity, etc. of the above-described metal foam. According to one embodiment of the present application, metal foams having various materials, pore sizes, etc. can be applied, as in the examples described below.

[0070] A method for manufacturing a catalyst for methane reforming according to one embodiment of the present application includes a step of preparing a first solution containing a precursor of a perovskite compound represented by the following chemical formula 1.

[0071] In one embodiment of the present application, the first solution containing the precursor of the perovskite compound represented by the chemical formula 1 can be applied in the form of a sol or gel.

[0072] The precursor of the above perovskite compound is a precursor of a metal constituting the perovskite compound, and by controlling the content thereof, the molar ratio of the metal of the perovskite compound can be controlled. In addition, there is no particular limitation on the precursor of the metal, and ammonium salts, nitrates, carbonates, chlorides, or mixtures thereof of the metal element can be applied in combination.

[0073] In one embodiment of the present application, the chemical formula 1 may be represented by the following chemical formula 2 or 3, but is not limited thereto.

[0074] [Chemical Formula 2]

[0075] SrTi α B y O 3-δ

[0076] [Chemical Formula 3]

[0077] Sr 1-x Y x Ti α B y O 3-δ

[0078] In the above chemical formulas 2 and 3,

[0079] B is Ni, Ru or Rh,

[0080] x is a real number greater than 0 and less than 1,

[0081] y is a real number greater than 0 and less than 0.2,

[0082] δ is a real number greater than 0 and less than 1,

[0083] α is a real number greater than 0.8 and less than 1.

[0084] A method for producing a catalyst for methane reforming according to one embodiment of the present application includes a step of producing a second solution by adding a pore-forming agent, which is a hydrophilic oligomer or polymer, to the first solution.

[0085] The pore-forming agent is not limited to any hydrophilic oligomer or polymer that dissolves well in water and ethanol, which are solvents of the first solution, but must be able to form pores without residue at high temperatures. In addition, since the temperature at which the catalytic reaction is performed is 800°C or higher, it must be 100% removed at 800°C or lower. More specifically, the pore-forming agent may include at least one selected from polyethylene glycol, polyethylene oxide, polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid, but is not limited thereto.

[0086] In one embodiment of the present application, the content range of the pore-forming agent can be determined by the viscosity of the second solution after adding the pore-forming agent, and when the pore-forming agent is a surfactant, can be determined by the critical micelle concentration.

[0087] In one embodiment of the present application, the viscosity of the second solution may be 10 cp to 1,500 cp, 10 cp to 1,000 cp, or 10 cp to 500 cp at 25°C. When the viscosity of the second solution is less than 10 cp, the effect of increasing the viscosity of the catalyst is minimal, and if the viscosity is too high, the coating may clump on the surface, which is not preferable. In addition, in the case of a pore-forming agent, which is a surfactant, when the critical micelle concentration (CMC) is exceeded, the catalyst forms a spherical structure during coating, which has the disadvantage of reducing the surface area, and all of these must be taken into consideration. Therefore, in one embodiment of the present application, the amount of the pore-forming agent added may be 1 wt% to 25 wt%, or 3 wt% to 10 wt%, based on the total weight of the first solution. The amount of the pore-forming agent added may be adjusted depending on the type of the pore-forming agent, the weight average molecular weight, etc. By satisfying the range of addition amount of the above pore forming agent, an optimal catalyst layer pore structure can be formed.

[0088] A method for manufacturing a catalyst for methane reforming according to one embodiment of the present application includes a step of manufacturing a catalyst by coating the second solution on a support and then performing a heat treatment process.

[0089] The method for coating the second solution on the above support may use a method known in the art, such as dip-coating or wash-coating, but is not limited thereto.

[0090] In one embodiment of the present application, the heat treatment process may include drying and calcining steps. The drying may be performed at a temperature of 50°C to 200°C for 1 to 48 hours, or at a temperature of 60°C to 150°C for 5 to 36 hours, but is not limited thereto. In addition, the calcination may be performed at a temperature of 350°C to 1,300°C in an air atmosphere for 1 to 10 hours, or at a temperature of 500°C to 1,200°C in an air atmosphere for 1.5 to 8 hours, but is not limited thereto. When the calcination step is performed at a temperature below 350°C, the perovskite phase may not be properly formed, and when it exceeds 1,300°C, the durability of the support may be reduced, which is not preferred.

[0091] In one embodiment of the present application, a step of measuring the weight of the perovskite-based coating layer coated on the support after the heat treatment process may be additionally included. In addition, by measuring the weight of the perovskite-based coating layer coated on the support, the step of coating the second solution described above and then performing the heat treatment process may be repeated 2 to 10 times until the desired amount of catalyst is coated on the support.

[0092] In addition, another embodiment of the present application provides a methane reforming catalyst manufactured according to the method for manufacturing the methane reforming catalyst.

[0093] In addition, another embodiment of the present application provides a catalyst for methane reforming, comprising: a support; and a coating layer provided on the support and including a perovskite compound represented by the chemical formula 1, wherein the average porosity of the outermost surface layer of the catalyst for methane reforming according to the following method 1 is 15% or more.

[0094] [Method 1]

[0095] At an arbitrary location on the outermost surface layer of the above methane reforming catalyst, an SEM (Scanning Electron Microscope) image is obtained at an acceleration voltage of 5 kV, a magnification of 10,000 times, and a pixel size of 1,280×960, and then the porosity is calculated using the following mathematical formula 2. At this time, 20 SEM images are obtained at the arbitrary locations that do not overlap each other, and then the porosity according to each SEM image is calculated, and the average value thereof is evaluated as the average porosity (%).

[0096] [Equation 2]

[0097] Porosity (%) = (Total area of ​​pores in SEM image) / (Total area of ​​outermost surface layer in SEM image) × 100

[0098] In the catalyst for methane reforming according to one embodiment of the present application, the specific details of the support and the coating layer including the perovskite compound represented by the chemical formula 1 are as described above.

[0099] In one embodiment of the present application, based on the total weight of the methane reforming catalyst, the content of the coating layer including the perovskite compound represented by the chemical formula 1 may be 3 wt% to 40 wt%, 6 wt% to 35 wt%, or 7 wt% to 30 wt%. If the content of the coating layer including the perovskite compound represented by the chemical formula 1 is less than 3 wt% based on the total weight of the methane reforming catalyst, the reactivity may be reduced due to a relatively small number of active sites on the catalyst surface, which is not preferable. In addition, if the content of the coating layer including the perovskite compound represented by the chemical formula 1 exceeds 40 wt%, a relatively large amount of catalyst component is contained compared to the support, making it difficult to maintain a pore structure, and bonding between the catalyst component and the support may not be easy, and thus the practical benefit of the methane reforming reaction may be reduced.

[0100] In one embodiment of the present application, the average porosity of the outermost surface layer of the methane reforming catalyst may be 15% or more, 15% to 40%, or 15% to 30%. When the average porosity of the outermost surface layer of the methane reforming catalyst is less than 15%, the active surface area of ​​the methane reforming catalyst cannot be increased, and thus, when the methane reforming catalyst is applied to a methane reforming reaction, it cannot exhibit high activity at high space velocity, which is undesirable.

[0101] In one embodiment of the present application, the total area of ​​the outermost surface layer and the total area of ​​the pore portion in the SEM image of the above mathematical formula 2 can be measured using image J software.

[0102] In one embodiment of the present application, the catalyst for methane reforming can be applied to a steam reforming process, a CO2 reforming process, a catalytic partial oxidation process, an autothermal reforming process, a tri-reforming process, or a mixed reforming process, and the methane reforming process is not particularly limited.

[0103] One embodiment of the present application provides a methane reforming method comprising the steps of: charging a catalyst according to the present application into a reactor; activating the catalyst; supplying a feed gas to the reactor; and applying heat and pressure to the feed gas.

[0104] In one embodiment of the present application, the methane reforming method may be a dry reforming reaction.

[0105] In one embodiment of the present application, the step of activating the catalyst may be a heat treatment at a temperature of 700°C to 900°C, preferably 750°C to 850°C, under H2 / N2 conditions. That is, the catalyst may be activated through a reduction process. The H2 / N2 conditions refer to the volume ratio of hydrogen (H2) to nitrogen (N2). More specifically, the step of activating the catalyst may be performed under H2 / N2 conditions of 5% to 15%, preferably 7% to 12%, and even more preferably 10%.

[0106] In one embodiment of the present application, the feed gas may include methane (CH4) and carbon dioxide (CO2). In addition, the feed gas may further include an inert gas. In one embodiment of the present application, the feed gas may include methane (CH4) and carbon dioxide (CO2), and further include hydrogen (H2) and / or nitrogen (N2). When the feed gas includes methane (CH4) and carbon dioxide (CO2), and further includes hydrogen (H2) and / or nitrogen (N2), the volume ratio of the feed gas may be CH4: CO2: (H2 and / or N2) = 1: (1 to 1.4) : (0.1 to 1). That is, the volume of the carbon dioxide in the supply gas may be 1 to 1.4 times the volume of the methane, and the volume of the hydrogen and / or nitrogen in the supply gas may be 0.1 to 1 times the volume of the methane.

[0107] In one embodiment of the present application, the methane (CH4) of the feed gas may be not only general methane (CH4) gas, but also CH4 derived from natural gas or biomethane.

[0108] In one embodiment of the present application, the carbon dioxide (CO2) of the feed gas may be used not only as general carbon dioxide (CO2), but also as CO2 produced from a factory, such as a by-product gas from a steel mill.

[0109] In one embodiment of the present application, in the step of supplying feed gas to the reactor, the WHSV (Weight Hour Space Velocity) of the feed gas is 1,000 hr. -1 100,000hr -1 , preferably 1,200hr -1 50,000hr -1 It could be.

[0110] In one embodiment of the present application, the step of applying heat and pressure to the supply gas may be performed under temperature conditions of 700°C to 900°C, preferably 750°C to 850°C, and pressure conditions of 0.5 bar to 1.5 bar, preferably 0.8 bar to 1.2 bar.

[0111] In one embodiment of the present application, the step of applying heat and pressure to the supply gas may be performed for 20 hours or more.

[0112] The methane reforming method of the present application may be applied to a method commonly used in a methane reforming method or a dry reforming reaction, except that the catalyst according to the present application is used.

[0113] According to one embodiment of the present application, a methane reforming catalyst can be formed in the form of a perovskite coating layer by directly coating the perovskite catalyst component represented by the chemical formula 1 onto a support without a separate binder. Accordingly, the methane reforming catalyst has the characteristic of increasing the active surface area.

[0114] In addition, the catalyst for methane reforming according to one embodiment of the present application can increase porosity by adding a pore-forming agent, which is a hydrophilic oligomer or polymer, to a first solution containing a precursor of a perovskite compound represented by the above chemical formula 1. Accordingly, the active surface area of ​​the catalyst for methane reforming can be increased, and the catalyst for methane reforming can exhibit high activity even at a high space velocity in the methane reforming reaction.

[0115] In addition, the method for manufacturing a catalyst for methane reforming according to one embodiment of the present application can increase the coating amount per time when coating the support with the second solution by ensuring that the viscosity of the second solution to which a pore-forming agent, which is a hydrophilic oligomer or polymer, is added satisfies 10 cp to 1,500 cp at 25°C.

[0116] Hereinafter, examples will be provided to specifically explain the present application. However, the embodiments according to the present application may be modified in various ways, and the scope of the present application is not limited to the embodiments described below. The embodiments of the present application are provided to more fully explain the present application to those of average skill in the art.

[0117] <Example>

[0118] <Example 1> SrTi 0.95 Ni 0.05 O 3-δ / NiCrAl

[0119] The first solution containing the precursor of the perovskite catalyst component was prepared through the citric acid method. More specifically, strontium nitrate (Sr(NO3)3H2O) and nickel nitrate (Ni(NO3)2) were dissolved in distilled water together with citric acid and ethylene glycol to prepare the 1-1 solution. Titanium isopropoxide (Ti(OCH(CH3)2)4) was dissolved in ethanol to prepare the 1-2 solution, and the 1-1 and 1-2 solutions were mixed at 70°C to prepare the 1-1 solution. After stirring for 3 hours, the solution was cooled to room temperature and stored. At this time, the concentration of the solution was 0.1 M, and nickel was contained in an amount of 5 mol% relative to titanium.

[0120] 8 wt% PEG (Polyethylene glycol, sigma-Aldrich, weight average molecular weight: 4,000 g / mol) as a pore-forming agent was added to the first solution, and stirred for 1 hour using a magnetic stirrer to prepare a second solution mixed with PEG.

[0121] Dip coating was performed so that the second solution prepared above could be supported on the metal foam (NiCrAl, average pore size: 800 μm, Alantum), which was a support, and then dried at 70°C for 24 hours and heat-treated at 900°C in an air atmosphere for 3 hours. This process was repeated three times to finally form SrTi on the metal foam. 0.95 Ni 0.05 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0122] <Example 2> Sr 0.9 Y 0.1 Ti 0.9 Ru 0.1 O 3-δ / Al2O3ball

[0123] Except that yttrium nitrate (Y(NO3)2) was used in an amount of 10 mol% relative to strontium, ruthenium chloride (RuCl3) was used in place of nickel nitrate (Ni(NO3)2) in an amount of 10 mol% relative to titanium, and the type and amount of the pore-forming agent and the type of support described in Table 1 were applied, the same procedure as in Example 1 was performed to add Sr to the support. 0.9 Y 0.1 Ti 0.9 Ru 0.1 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0124] <Example 3> SrTi 0.9 Ru 0.1 O 3-δ / NiFeCrAl

[0125] Except that ruthenium chloride (RuCl3) was used in place of nickel nitrate (Ni(NO3)2) at 10 mol% relative to titanium, and the type and amount of pore forming agent and type of support described in Table 1 were applied, the same procedure as in Example 1 was performed to prepare SrTi as the support. 0.9 Ru 0.1 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0126] <Example 4> Sr 0.9 Y 0.1 Ti 0.85 Ni 0.15 O 3-δ / NiCrAl

[0127] The same procedure as Example 1 was performed except that yttrium nitrate (Y(NO3)2) was used in an amount of 10 mol% compared to strontium, the nickel content was increased to 15 mol% compared to titanium, and the type and amount of the pore forming agent and the type of support described in Table 1 were applied, and Sr was added to the support. 0.9 Y 0.1 Ti 0.85 Ni 0.15 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0128] <Example 5> SrTi 0.97 Ni 0.03 O 3-δ / NiCrAl

[0129] The nickel content was reduced to 3 mol% compared to titanium, and the type and amount of the pore forming agent and the type of support described in Table 1 were applied, and the same procedure as Example 1 was performed to apply SrTi to the support. 0.97 Ni 0.03 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0130] <Example 6> Sr 0.9 Y 0.1 Ti 0.87 Ni 0.13 O 3-δ / NiFeCrAl

[0131] The same procedure as Example 1 was performed except that yttrium nitrate (Y(NO3)2) was used in an amount of 10 mol% compared to strontium, the nickel content was increased to 13 mol% compared to titanium, and the type and amount of the pore forming agent and the type of support described in Table 1 were applied, and Sr was added to the support. 0.9 Y 0.1 Ti 0.87 Ni 0.13 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0132] <Example 7> SrTi 0.93 Ni 0.07 O 3-δ / NiCrAl

[0133] The nickel content was increased to 7 mol% compared to titanium, and the type and amount of the pore forming agent and the type of support described in Table 1 were applied, and the same procedure as Example 1 was performed to apply SrTi to the support. 0.93 Ni 0.07 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0134] <Comparative Example 1> SrTi 0.95 Ni 0.05 O 3-δ / NiCrAl

[0135] Except for the manufacturing process of the second solution adding a pore forming agent and coating the first solution on the support, the same procedure as in Example 1 was performed to prepare SrTi on the support. 0.95 Ni 0.05 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0136] <Comparative Example 2> Sr 0.9 Y 0.1 Ti 0.9 Ru 0.1 O 3-δ / Al2O3ball

[0137] Except for the manufacturing process of the second solution adding a pore forming agent and coating the first solution on the support, the same procedure as in Example 2 was performed to add Sr to the support. 0.9 Y 0.1 Ti 0.9 Ru 0.1 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0138] <Comparative Example 3> Sr 0.9 Y 0.1 Ti 0.85 Ni 0.15 O 3-δ / NiCrAl

[0139] Except that the type and amount of the pore forming agent and the type of support described in Table 1 below were applied, the same procedure as in Example 4 was performed to apply Sr to the support. 0.9 Y 0.1 Ti 0.85 Ni 0.15 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0140] <Comparative Example 4> Zr-Ce-La(75%-20%-5%) / NiCrAl

[0141] A solution containing Zr, Ce, and La salts was prepared by mixing 87.5 g of ZrOCl2·8H2O, 73.2 g of a 28.0% Ce(NO3)3·6H2O solution, 21.5 g of an 18.0% La(NO3)3 solution, and 200 g of distilled water. The solution was added dropwise to a 1 L beaker containing 700 g of a 25% NH4OH solution and stirred at 200 rpm. The formed precipitate was filtered using a Buchner filter and washed with distilled water to remove excess chloride, nitrate, and ammonium ions. Thereafter, the precipitate was dried at 150°C for 24 hours and heat-treated at 900°C in an air atmosphere for 3 hours to obtain an oxide powder. The above oxide powder was ball milled at 120 rpm for 8 hours, and then mixed with water as a solvent at a ratio of 5 wt% to prepare a coating solution.

[0142] Dip coating was performed so that the coating solution prepared above could be supported on the metal foam (NiCrAl, average pore size: 800 μm, Alantum), which was a support, and then dried at 70°C for 24 hours and heat-treated at 900°C in an air atmosphere for 3 hours.

[0143] <Comparative Example 5> Zr-Ce-La(75%-20%-5%) / NiCrAl

[0144] When preparing the coating solution, the same procedure as in Comparative Example 4 was followed, except that an 8 wt% PEG (Polyethylene glycol, sigma-Aldrich, weight average molecular weight: 4,000 g / mol) aqueous solution was used instead of water.

[0145] <Comparative Example 6> SrTi 0.97 Ni 0.03 O 3-δ / NiCrAl

[0146] Except for the manufacturing process of the second solution adding a pore forming agent and coating the first solution on the support, the same procedure as in Example 2 was performed to form SrTi on the support. 0.97 Ni 0.03 O 3-δ A catalyst coated with (0 < δ < 1) was prepared.

[0147] [Table 1]

[0148]

[0149]

[0150] PEG: Polyethylene glycol

[0151] PVA: Polyvinyl alcohol

[0152] The viscosity of the above coating solution was measured using a BROOKFIELD (model: LVDV Ⅱ) viscometer, and the spindle was selected so that the torque range was 10 to 30% at 25°C, and the resulting viscosity was recorded for approximately 5 minutes.

[0153] <Experimental Example 1> Evaluation of a catalyst for methane reforming

[0154] The catalyst coating amount, BET surface area, and average porosity of the catalysts manufactured in the above examples and comparative examples were evaluated and are shown in Table 2 below.

[0155] A SEM (Scanning Electron Microscope) image of a catalyst for methane reforming according to Example 1 of the present application is shown in Figure 1 below.

[0156] The results of the porosity analysis of the catalyst for methane reforming according to Example 4 of the present application are shown in Figure 2 below.

[0157] The results of the porosity analysis of the catalyst for methane reforming according to Example 6 of the present application are shown in Figure 3 below.

[0158] An SEM photograph of a catalyst for methane reforming according to Comparative Example 1 of the present application is shown in Figure 4 below.

[0159] The results of the porosity analysis of the catalyst for methane reforming according to Comparative Example 1 of the present application are shown in Figure 5 below.

[0160] An SEM photograph of a catalyst for methane reforming according to Comparative Example 3 of the present application is shown in Figure 6 below.

[0161] The measurement method for the evaluation results listed in Table 2 below is as follows.

[0162] <Catalyst coating amount>

[0163] The above catalyst coating amount was calculated using the following mathematical formula 1.

[0164] [Mathematical Formula 1]

[0165] Catalyst coating amount (wt%) = (total catalyst weight - support weight) / (total catalyst weight) × 100

[0166] <BET 표면적>

[0167] The above BET surface area was determined by N2 adsorption / desorption isotherm at -196°C using ASAP 2020 (Micromeritics).

[0168] <Average porosity>

[0169] The average porosity of the outermost surface layer of the catalyst for methane reforming was evaluated according to the following method 1.

[0170] [Method 1]

[0171] At an arbitrary location on the outermost surface layer of the methane reforming catalyst, an SEM (Scanning Electron Microscope) image was obtained at an acceleration voltage of 5 kV, a magnification of 10,000 times, and a pixel size of 1,280 × 960, and then the porosity was calculated using the following mathematical formula 2. At this time, 20 SEM images were obtained at the arbitrary locations without overlapping each other, and then the porosity according to each SEM image was calculated, and the average value thereof was evaluated as the average porosity (%).

[0172] [Equation 2]

[0173] Porosity (%) = (Total area of ​​pores in SEM image) / (Total area of ​​outermost surface layer in SEM image) × 100

[0174] At this time, the total area of ​​the outermost surface layer and the total area of ​​the pore portion in the SEM image of the above mathematical formula 2 were measured using image J software.

[0175] [Table 2]

[0176]

[0177] As shown in the above results, it can be confirmed that the catalyst for methane reforming according to one embodiment of the present application can increase porosity by adding a pore-forming agent to the first solution containing the precursor of the perovskite compound represented by the above chemical formula 1. In particular, when Example 1 and Comparative Example 1, which have the same catalyst composition except for the presence or absence of the pore-forming agent and the same type of support, are compared with each other, or Example 2 and Comparative Example 2, it can be confirmed that in Comparative Examples 1 and 2, the number of coatings must increase in order to reach a catalyst coating amount similar to that of Examples 1 and 2. Therefore, according to one embodiment of the present application, the effect of shortening the overall process time can also be obtained.

[0178] In addition, when comparing Example 5 and Comparative Example 6, which have the same catalyst composition and the same support type except for the presence or absence of a pore-forming agent, it can be confirmed that the average porosity of Comparative Example 6 is very low even though the total number of coatings is the same as that of Example 5.

[0179] In addition, even if a pore-forming agent is added to the first solution, in Comparative Example 3, the viscosity of the coating solution is outside the range of the present application, so that the coating solution is coated on the support in a spherical shape, reducing the surface area, and reducing the area of ​​contact between the surface of the support and the catalyst coating layer, thereby weakening the interaction between the support and the catalyst coating layer, resulting in a problem of the catalyst coating layer being detached from the support.

[0180] In addition, in Comparative Examples 4 and 5, the catalyst coating layer included a conventional metal oxide rather than a perovskite compound represented by the chemical formula 1 of the present application, so that the single coating amount for the support was very small, less than 1 wt%, and the porosity was also very low regardless of the presence or absence of the addition of a pore-forming agent.

[0181] <Experimental Example 2> Evaluation of methane reforming reaction

[0182] A fixed-bed reaction system was introduced to perform the dry reforming reaction of methane. A quartz tube reactor (inner diameter = 1 / 2 inch, length = 50 cm) was used and each catalyst (approximately 2.5 g) from the examples and comparative examples was charged. First, a reduction process was performed at 800°C for 2 hours under 10% H2 / N2 conditions, followed by a catalytic reaction for 100 hours.

[0183] Gas composition: CH4: CO2: N2= 1: 1.2: 0.96

[0184] Flow rate: GHSV (Gas Hour Space Velocity) = 1,500 h -1

[0185] Reaction temperature: 800℃

[0186] Reaction pressure: 1 bar

[0187] The composition of the generated gas was analyzed using gas chromatography (GC) and the reaction conversion rate was calculated after 100 hours of reaction, which is shown in Table 3 below.

[0188] Conversion rate (Xi, %) = [(Fi in - Fi out ) / Fi in ] × 100 (Fi = flow rate of i)

[0189] <GC 분석 조건>

[0190] 1) GC model: Agilent 6890

[0191] 2) Oven temp.: 40℃ / 7min-90℃ / 5min-180℃ / 6min

[0192] 3) Detector: TCD, 250℃

[0193] 4) Sample loop: 0.25 mL

[0194] 5) Valve box Temp.: 150℃

[0195] [Table 3]

[0196]

[0197] As shown in the above results, it can be confirmed that the methane reforming catalyst according to one embodiment of the present application can increase the active surface area of ​​the methane reforming catalyst by adding a pore-forming agent to the first solution containing the precursor of the perovskite compound represented by the above chemical formula 1, and that the methane reforming catalyst can exhibit high activity even at a high space velocity in the methane reforming reaction.

[0198] In addition, when comparing Example 5 and Comparative Example 6, which have the same catalyst composition and the same support type except for the presence or absence of a pore-forming agent, it can be confirmed that the Example of the present application improves both the CH4 conversion rate and the CO2 conversion rate when the total number of coatings of the catalyst is the same.

Claims

1. A step of preparing a first solution containing a precursor of a perovskite compound represented by the following chemical formula 1; A step of preparing a second solution by adding a pore-forming agent, which is a hydrophilic oligomer or polymer, to the first solution; and A step of manufacturing a catalyst by coating the second solution on a support and then performing a heat treatment process, A method for producing a catalyst for methane reforming, wherein the viscosity of the second solution is 10 cp to 1,500 cp at 25°C: [Chemical Formula 1] Sr 1-x A x Ti α B y The 3-δ In the above chemical formula 1, A is selected from Y, Sc, La and lanthanide series elements, B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh, x is a real number greater than or equal to 0 and less than 1, y is a real number greater than or equal to 0 and less than 0.2, δ is a real number greater than or equal to 0 and less than 1, α is a real number greater than 0.8 and less than or equal to 1, (x + y) > 0.

2. A method for producing a catalyst for methane reforming, wherein the pore-forming agent according to claim 1 comprises at least one selected from polyethylene glycol, polyethylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrylic acid.

3. A method for producing a catalyst for methane reforming according to claim 1, wherein the amount of the pore-forming agent added is 1 wt% to 25 wt% based on the total weight of the first solution.

4. A method for producing a catalyst for methane reforming according to claim 1, wherein the support comprises at least one selected from NiFeCrAl, NiCrAl, stainless steel, Inconel, SiC, and α-Al2O3.

5. A method for producing a catalyst for methane reforming, wherein the chemical formula 1 in claim 1 is represented by the following chemical formula 2 or 3: [Chemical Formula 2] SrTi α B y The 3-δ [Chemical Formula 3] Mr 1-x AND x You α B y EITHER 3-δ In the above chemical formulas 2 and 3, B is Ni, Ru or Rh, x is a real number greater than 0 and less than 1, y is a real number greater than 0 and less than 0.2, δ is a real number greater than 0 and less than 1, α is a real number greater than 0.8 and less than 1.

6. A catalyst for methane reforming comprising a support; and a coating layer provided on the support and including a perovskite compound represented by the following chemical formula 1, A methane reforming catalyst having an average porosity of 15% or more of the outermost surface layer of the methane reforming catalyst according to the following method 1: [Chemical Formula 1] Sr 1-x A x Ti α B y The 3-δ In the above chemical formula 1, A is selected from Y, Sc, La and lanthanide series elements, B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh, x is a real number greater than or equal to 0 and less than 1, y is a real number greater than or equal to 0 and less than 0.2, δ is a real number greater than or equal to 0 and less than 1, α is a real number greater than 0.8 and less than or equal to 1, (x + y) > 0, [Method 1] At an arbitrary location on the outermost surface layer of the above methane reforming catalyst, an SEM (Scanning Electron Microscope) image is obtained at an acceleration voltage of 5 kV, a magnification of 10,000 times, and a pixel size of 1,280×960, and then the porosity is calculated using the following mathematical formula 2. At this time, 20 SEM images are obtained at the arbitrary locations that do not overlap each other, and then the porosity according to each SEM image is calculated, and the average value thereof is evaluated as the average porosity (%). [Equation 2] Porosity (%) = (Total area of ​​pores in SEM image) / (Total area of ​​outermost surface layer in SEM image) × 100 7. A catalyst for methane reforming according to claim 6, wherein the support comprises at least one selected from NiFeCrAl, NiCrAl, stainless steel, Inconel, SiC, and α-Al2O3.

8. In claim 6, the chemical formula 1 is a catalyst for methane reforming represented by the following chemical formula 2 or 3: [Chemical Formula 2] SrTi α B y The 3-δ [Chemical Formula 3] Mr 1-x AND x You α B y EITHER 3-δ In the above chemical formulas 2 and 3, B is Ni, Ru or Rh, x is a real number greater than 0 and less than 1, y is a real number greater than 0 and less than 0.2, δ is a real number greater than 0 and less than 1, α is a real number greater than 0.8 and less than 1.

9. A methane reforming catalyst according to claim 6, wherein the content of the coating layer including the perovskite compound represented by the chemical formula 1 is 3 wt% to 40 wt% based on the total weight of the methane reforming catalyst.

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