Catalyst for methane reforming and method for producing same

Abstract

A methane reforming catalyst according to one embodiment of the present application comprises: a porous metal support; a first coating layer provided on the porous metal support and including an inorganic oxide; and a second coating layer provided on the first coating layer and including a perovskite-based compound represented by Chemical Formula 1, wherein the inorganic oxide comprises CeO2 or Al2O3.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2022-0134974, filed with the Korean Intellectual Property Office on October 19, 2022, 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. [Background technology]

[0003] As part of efforts to reduce greenhouse gas emissions caused by global warming, much research is underway into carbon dioxide conversion technologies. One of these technologies, the carbon dioxide reforming reaction, is a technique for producing synthesis gas consisting of hydrogen and carbon monoxide by reacting methane with carbon dioxide.

[0004] Syngas is a valuable substance for development as a raw material for various downstream processes. Natural gas reforming reactions, which are methods for industrially obtaining syngas (H2 / CO), can be broadly classified into steam reforming, CO2 reforming, catalytic partial oxidation, autothermal reforming, and tri-reforming, as shown in the following reaction equations 1 to 5. [Reaction Scheme 1] CH4+H2O → 3H2+CO △H=226kJ / mol [Reaction Scheme 2] CH4+CO2→ 2H2+2CO △H=261kJ / mol [Reaction Scheme 3] CH4+0.5O2→ 2H2+CO △H=-44kJ / mol [Reaction Scheme 4] Autothermal reforming: Equation 1 + Equation 3 [Reaction Scheme 5] Tri-reforming: Reaction 1 + Reaction 2 + Reaction 3

[0005] Meanwhile, various catalysts can be used in the reforming process for improving reforming activity. Among these, the use of a noble metal catalyst in the reforming process has the advantage of high efficiency in converting natural gas to hydrogen, but the high cost of the noble metal catalyst results in poor economic viability.

[0006] Therefore, nickel catalysts, which have high hydrogen conversion efficiency and are relatively inexpensive, are mainly used in the reforming process. However, in such cases, there is a problem that the nickel catalyst is deactivated by carbon that is inevitably generated on the surface of the nickel catalyst.

[0007] Therefore, there is a need in the art for the development of catalysts that are resistant to carbon deposition and can be effectively applied in methane reforming processes. Summary of the Invention [Problem to be solved by the invention]

[0008] The present application seeks to provide a catalyst for methane reforming and a method for producing the same. [Means for solving the problem]

[0009] One embodiment of the present application is porous metal support; a first coating layer provided on the porous metal support, the first coating layer comprising an inorganic oxide; and a second coating layer provided on the first coating layer and containing a perovskite-based compound represented by the following chemical formula 1, The inorganic oxide provides a catalyst for methane reforming, wherein the inorganic oxide contains CeO2 or Al2O3. [Chemical formula 1] Sr 1-x A x Ti 1-y B y O 3-δ In the above chemical formula 1, A is selected from Y, Sc, La and the lanthanide series elements; B is Cr, Mn, Fe, Co, Ni, Mo, Ru or Rh; x is a real number between 0 and 1, y is a real number greater than or equal to 0 and less than 0.5, δ is a real number between 0 and 1, (x+y)>0.

[0010] Also, another embodiment of the present application is porous metal support; a first coating layer provided on the porous metal support, the first coating layer comprising an inorganic oxide; and a second coating layer provided on the first coating layer and containing a perovskite-based compound represented by Chemical Formula 1; The present invention provides a methane reforming catalyst, wherein the first coating layer contains two or more of Al, Ce, Zr, Y, Ti and Si.

[0011] Also, another embodiment of the present application is preparing a first solution containing a precursor of an inorganic oxide; and a second solution containing a precursor of a perovskite-based compound represented by Chemical Formula 1; After coating the first solution on a porous metal support, a first heat treatment process is performed to prepare a catalyst precursor having a first coating layer; and and a step of coating the catalyst precursor having the first coating layer with the second solution and then performing a second heat treatment to prepare a catalyst having a second coating layer; The present invention provides a method for producing a methane reforming catalyst, wherein the inorganic oxide precursor is a precursor of CeO; a precursor of AlO; or a precursor of a composite oxide containing two or more of Al, Ce, Zr, Y, Ti, and Si.

[0012] Also, another embodiment of the present application is preparing a first solution containing a precursor of a first inorganic oxide; a second solution containing a precursor of a second inorganic oxide; and a second solution containing a precursor of the perovskite-based compound represented by Chemical Formula 1; a step of coating the porous metal support with the solution (1-1) and then carrying out a heat treatment (1-1) to prepare a catalyst precursor having a first inorganic oxide layer; Coating the catalyst precursor having the first inorganic oxide layer with the first solution, and then performing a first heat treatment process to prepare a catalyst precursor having a second inorganic oxide layer; and and a step of coating the catalyst precursor having the second inorganic oxide layer with the second solution, and then performing a second heat treatment to prepare a catalyst having a second coating layer; The present invention provides a method for producing a methane reforming catalyst, wherein the first inorganic oxide precursor and the second inorganic oxide precursor are different from each other and are each independently a precursor of an inorganic oxide containing one or more of Al, Ce, Zr, Y, Ti, and Si. [Effects of the Invention]

[0013] In a methane reforming catalyst according to an embodiment of the present application, a first coating layer containing an inorganic oxide is formed, which not only improves adhesion between a porous metal support and a second coating layer containing a perovskite-based compound represented by Chemical Formula 1, but also prevents side reactions of the porous metal support.

[0014] Furthermore, the methane reforming catalyst according to one embodiment of the present application has a perovskite compound supported on a porous metal support having high thermal conductivity, and therefore has the advantage that it is easier to control the reaction heat compared to conventional pellet-shaped or powder-shaped catalysts.

[0015] In addition, the methane reforming catalyst according to one embodiment of the present application is characterized in that a synergistic effect exists between the first coating layer containing an inorganic oxide and the second coating layer containing a perovskite-based compound represented by Chemical Formula 1, which enables further increase in activity.

[0016] In addition, the methane reforming catalyst according to one embodiment of the present application can increase the active surface area of ​​the catalyst, thereby exhibiting high activity even at a high space velocity during the methane reforming reaction. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present specification will be explained in more detail below.

[0018] In this specification, when a member is said to be located "on" another member, this includes not only when the member is in contact with the other member, but also when there is another member between the two members.

[0019] In this specification, when a part is said to "comprise" a certain component, this means that it can further include other components, rather than excluding other components, unless otherwise specified.

[0020] Currently, catalysts widely used in the reformer field are generally powder catalysts and pellet-type support catalysts. Powder catalysts have excellent catalyst dispersion and performance, but are difficult to directly use in industrial applications. For example, when a reformer is operated using a powder catalyst, the catalyst is released along with the materials produced after the reaction. However, the powder catalyst gradually accumulates in the outlet flow tube, eventually clogging the entire tube. Therefore, a drawback is that powder catalysts cannot be used in commercial reformers for industrial use.

[0021] Pellet-type support catalysts are currently widely used in industrial reformers. While their catalytic performance is inferior to that of powder-type catalysts due to mass transfer rate limitations, the use of a support offers the advantage of long-term use. However, γ-Al2O3 pellets, which are commonly used as pellet-type support catalysts, have the disadvantage of being prone to shattering due to their weak structural strength, which can lead to differential pressure within the reactor. Furthermore, due to the characteristics of pellet-type support catalysts, their volume is large, making them quite bulky when used in high-capacity reformers. Furthermore, while all reforming reactions are sensitive to reaction temperature, existing pellet-type catalysts have the disadvantage of significantly reduced thermal conductivity, resulting in inconsistent heat distribution throughout the reactor. Furthermore, because reforming reactions are very fast, pellet-type support catalysts and extruded catalysts have a catalyst effectiveness factor of less than 0.3, resulting in reduced catalyst utilization.

[0022] Therefore, this application aims to improve not only the flow tube clogging phenomenon, which is a drawback of powder-type catalysts, but also the heat and mass transfer rate, which is a common drawback of both powder and pellet-type catalysts, by coating the catalyst on a porous metal support, which has a high heat and mass transfer rate.In addition, this application aims to provide a methane reforming catalyst that can support a large amount of catalyst at one time and suppress side reactions caused by the binder.

[0023] In addition, when using a precious metal catalyst such as Rh as a catalyst for methane reforming, the problem of coke formation can be reduced, but the rising cost makes commercialization difficult. In contrast, Ni-based catalysts not only exhibit high reactivity but are also inexpensive, but have the problem of catalyst deactivation due to coke formation. Therefore, much research is being conducted to improve the coke formation resistance.

[0024] In order to improve the coke formation resistance, the present application attempts to appropriately adjust the catalyst's characteristics. For example, in the dry reforming reaction of methane, if the catalyst's acidity is too strong, coke deposition due to methane decomposition may be accelerated, while if the catalyst's acidity is too weak, reactivity may be reduced due to reduced methane decomposition. To prevent carbon deposition, the activity of carbon dioxide must be increased to promote carbon vaporization. However, carbon dioxide, being an acidic gas, is activated by the basic sites of the catalyst.

[0025] Therefore, the present application seeks to provide a catalyst that has a good balance between methane decomposition and carbon oxidation by carbon dioxide activation.

[0026] A methane reforming catalyst according to one embodiment of the present application includes a porous metal support, a first coating layer formed on the porous metal support and including an inorganic oxide, and a second coating layer formed on the first coating layer and including a perovskite-based compound represented by Chemical Formula 1. In this case, the inorganic oxide includes CeO2 or Al2O3.

[0027] A methane reforming catalyst according to another embodiment of the present application includes a porous metal support, a first coating layer formed on the porous metal support and containing an inorganic oxide, and a second coating layer formed on the first coating layer and containing a perovskite-based compound represented by Chemical Formula 1. In this case, the first coating layer includes two or more of Al, Ce, Zr, Y, Ti, and Si.

[0028] In one embodiment of the present application, the first coating layer may be a single layer made of a composite oxide containing two or more of Al, Ce, Zr, Y, Ti, and Si. Specific examples of the composite oxide include, but are not limited to, YSZ (yttria-stabilized zirconia), Al2O3-CeO2, Al2O3-ZrO2, CeO2-ZrO2, Al2O3-TiO2, CeO2-TiO2, and CeO2-ZrO2-Al2O3.

[0029] In one embodiment of the present application, the first coating layer may have a bilayer structure including a first inorganic oxide layer containing one or more of Al, Ce, Zr, Y, Ti, and Si; and a second inorganic oxide layer containing one or more of Al, Ce, Zr, Y, Ti, and Si. In this case, the first inorganic oxide layer and the second inorganic oxide layer contain different inorganic oxides. The first inorganic oxide layer and the second inorganic oxide layer may each independently contain Al2O3, CeO2, ZrO2, TiO2, ZrO2, or SiO2. The bilayer structure of the first inorganic oxide layer / second inorganic oxide layer may be, but is not limited to, an Al2O3 / CeO2 structure, an Al2O3 / ZrO2 structure, a CeO2 / ZrO2 structure, an Al2O3 / TiO2 structure, a TiO2 / ZrO2 structure, or a CeO2 / TiO2 structure.

[0030] When the first coating layer is formed as a single layer of a complex oxide, the complex oxide is not uniformly distributed during the firing process after the formation of the first coating layer, and the complex oxide separates, resulting in an effect similar to a single oxide coating in some areas. Also, when the first coating layer is formed as a double layer of a first inorganic oxide layer and a second inorganic oxide layer, the ratio can be appropriately adjusted to obtain a form in which the second inorganic oxide is uniformly distributed on the first inorganic oxide.

[0031] In particular, when the first inorganic oxide layer is formed of an inorganic oxide that can form a strong bond with the metal that is the main component of the porous metal support, the metal component of the porous metal support can be less exposed to the second inorganic oxide layer, and the properties of the second inorganic oxide can more efficiently affect the second coating layer containing a perovskite-based compound.

[0032] In one embodiment of the present application, the porous metal support may be a metal foam comprising NiCrAlFe, NiCrAl, SiC or α-Al2O3.

[0033] The porous metal support may have various shapes, has a low heat capacity, and has excellent heat transfer ability, and can be formed into a desired shape for use. The shape and size of the porous metal support are not particularly limited, and the porosity of the porous metal support may be 10% to 99%, 50% to 96%, or 85% to 96%. The pore size of the porous metal support may be 400 μm to 1,500 μm or 450 μm to 1,400 μm. Pore sizes of less than 400 μm can be difficult to coat with the precursor solution, while pore sizes exceeding 1,500 μm are undesirable because they reduce the surface area available for catalyst coating, resulting in process disadvantages. The porous metal support can be appropriately prepared by those skilled in the art using methods known in the art, taking into account the material, pore size, and porosity of the porous metal support.

[0034] In one embodiment of the present application, the first coating layer may consist solely of an inorganic oxide, and the second coating layer may consist solely of a perovskite-based compound represented by Chemical Formula 1.

[0035] In one embodiment of the present application, the total content of the first coating layer containing the inorganic oxide may be 1 wt% to 15 wt%, or 2 wt% to 13 wt%, based on the total weight of the porous metal support. If the total content of the first coating layer containing the inorganic oxide exceeds 15 wt%, the capacity available for forming the second coating layer containing the perovskite compound represented by Chemical Formula 1 may be reduced, which may result in lower catalytic activity relative to the volume of the porous metal support, which is undesirable. Furthermore, if the total content of the first coating layer containing the inorganic oxide is less than 1 wt%, the content is so insignificant that it may be difficult to obtain the effects of the first coating layer.

[0036] In one embodiment of the present application, the weight ratio of the first coating layer to the second coating layer may be 1:5 to 1:20, or 1:7 to 1:15. Any deviation from the weight ratio of the first coating layer to the second coating layer is undesirable because the activity of the catalyst may be reduced relative to the volume of the porous metal support.

[0037] In one embodiment of the present application, the content of the second coating layer containing the perovskite-based compound represented by Chemical Formula 1 may be 3 wt% to 40 wt%, 6 wt% to 35 wt%, or 7 wt% to 30 wt%, based on the total weight of the methane reforming catalyst. If the content of the second coating layer containing the perovskite-based compound represented by 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 the relatively small number of active sites on the catalyst surface, which is undesirable. Furthermore, if the content of the second coating layer containing the perovskite-based compound represented by Chemical Formula 1 exceeds 40 wt%, the amount of catalyst components contained in the second coating layer is relatively large compared to the porous metal support, making it difficult to maintain the pore structure and to bond the catalyst components to the porous metal support, which may reduce the practical benefits of the methane reforming reaction.

[0038] In one embodiment of the present application, the first coating layer can be provided on the entire surface of the porous metal support.

[0039] In one embodiment of the present application, at least a portion of the surface of the methane reforming catalyst may include protrusions, which may be, but are not limited to, spherical, elliptical, or a combination thereof.

[0040] In one embodiment of the present application, the first coating layer including the inorganic oxide may serve to fix the second coating layer including the perovskite-based compound represented by Chemical Formula 1 on the porous metal support. In addition, the second coating layer including the perovskite-based compound represented by Chemical Formula 1 may be present in the form of protrusions on the first coating layer, thereby increasing the reaction surface area of ​​the catalyst and improving the performance of the methane reforming reaction.

[0041] According to one embodiment of the present application, the total amount of catalyst supported on the porous metal support can be increased by simultaneously applying a first coating layer containing the inorganic oxide and a second coating layer containing the perovskite-based compound represented by Chemical Formula 1, compared to the case where catalyst particles are applied alone. Also, according to one embodiment of the present application, the application of the first coating layer containing the inorganic oxide can prevent the metals (Ni, Cr, etc.), which are the main components of the porous metal support, from being exposed to the surface in the form of metal oxides (NiO, Cr2O3, etc.) under long-term operating conditions at high temperatures (750°C or higher), and can prevent changes in the catalyst component ratio or catalyst phase of Chemical Formula 1, thereby improving the durability and performance of the catalyst.

[0042] In one embodiment of the present application, the methane reforming catalyst may be applied to a steam reforming process, a carbon dioxide 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.

[0043] A method for producing a methane reforming catalyst according to one embodiment of the present application includes the steps of preparing a first solution containing an inorganic oxide precursor and a second solution containing a precursor of a perovskite-based compound represented by Chemical Formula 1; coating a porous metal support with the first solution and then performing a first heat treatment to produce a catalyst precursor having a first coating layer; and coating the catalyst precursor having the first coating layer with the second solution and then performing a second heat treatment to produce a catalyst having a second coating layer. In this case, the inorganic oxide precursor is a CeO precursor, an AlO precursor, or a composite oxide precursor containing two or more of Al, Ce, Zr, Y, Ti, and Si.

[0044] In addition, a method for producing a methane reforming catalyst according to another embodiment of the present application includes the steps of preparing a 1-1 solution containing a precursor of a first inorganic oxide; a 1-2 solution containing a precursor of a second inorganic oxide; and a second solution containing a precursor of a perovskite compound represented by Chemical Formula 1; coating a porous metal support with the 1-1 solution and then performing a 1-1 heat treatment process to produce a catalyst precursor having a first inorganic oxide layer; coating the catalyst precursor having the first inorganic oxide layer with the 1-2 solution and then performing a 1-2 heat treatment process to produce a catalyst precursor having a second inorganic oxide layer; and coating the catalyst precursor having the second inorganic oxide layer with the second solution and then performing a second heat treatment process to produce a catalyst having a second coating layer. In this case, the precursor of the first inorganic oxide and the precursor of the second inorganic oxide are different from each other and are each independently a precursor of an inorganic oxide containing one or more of Al, Ce, Zr, Y, Ti and Si.

[0045] In the method for producing a methane reforming catalyst according to one embodiment of the present application, the porous metal support, the perovskite-based compound represented by Chemical Formula 1, the inorganic oxide, etc. are the same as those described above.

[0046] In particular, the second solution containing the precursor of the perovskite-based compound represented by Chemical Formula 1 may be applied in the form of a sol or gel. Furthermore, the first solution containing the precursor of the inorganic oxide may be provided in the form of an inorganic oxide dispersion, as well as a sol, gel, or solution containing the precursor of the inorganic oxide. The solvent for the solution containing the precursor of the inorganic oxide may be water or any solvent known in the art, and is not particularly limited.

[0047] The precursor of the perovskite compound is a precursor of a metal constituting the perovskite compound, and its content can be adjusted to control the metal molar ratio of the perovskite compound. The metal precursor is not particularly limited, and may be an ammonium salt, nitrate, carbonate, chloride, lactate, hydroxide, organic acid salt, oxide, or a mixture thereof of the metal element.

[0048] The precursor of the inorganic oxide is not particularly limited, and ammonium salts, nitrates, carbonates, chlorides, lactates, hydroxides, organic acid salts, oxides of the inorganic substances, or mixtures thereof can be used in combination.

[0049] A method for producing a methane reforming catalyst according to one embodiment of the present application includes the steps of preparing a first solution containing a precursor of an inorganic oxide; and a second solution containing a precursor of a perovskite compound represented by Chemical Formula 1 above.

[0050] In addition, a method for producing a methane reforming catalyst according to another embodiment of the present application includes the steps of preparing a 1-1 solution containing a precursor of a first inorganic oxide; a 1-2 solution containing a precursor of a second inorganic oxide; and a second solution containing a precursor of a perovskite compound represented by Chemical Formula 1 above.

[0051] The first solution, the first-1 solution, the first-2 solution, and the second solution may each independently further contain a solvent, and the solvent may be any solvent known in the art and is not particularly limited. The first solution, the first-1 solution, and the second solution may each independently further contain an organic dispersant, and the organic dispersant may be any organic dispersant known in the art and is not particularly limited.

[0052] A method for producing a methane reforming catalyst according to one embodiment of the present application includes the steps of: coating a porous metal support with the first solution, and then performing a first heat treatment process to produce a catalyst precursor having a first coating layer; and coating the catalyst precursor having the first coating layer with the second solution, and then performing a second heat treatment process to produce a catalyst having a second coating layer.

[0053] In addition, a method for producing a methane reforming catalyst according to another embodiment of the present application includes the steps of: coating a porous metal support with the solution (1-1) and then performing a heat treatment (1-1) to produce a catalyst precursor having a first inorganic oxide layer; coating the catalyst precursor having the first inorganic oxide layer with the solution (1-2) and then performing a heat treatment (1-2) to produce a catalyst precursor having a second inorganic oxide layer; and coating the catalyst precursor having the second inorganic oxide layer with the second solution and then performing a second heat treatment to produce a catalyst having a second coating layer.

[0054] The coating method for the first solution, the 1-1 solution, the 1-2 solution, and the 2nd solution may be a method known in the art, such as, but not limited to, dip coating, wash coating, etc.

[0055] The first heat treatment step, the 1-1 heat treatment step, the 1-2 heat treatment step, and the 2nd heat treatment step may each independently include a drying and a calcination step. The drying may be performed at a temperature of 50°C to 150°C for 1 hour to 48 hours, or at a temperature of 60°C to 100°C for 5 hours to 36 hours, but is not limited thereto. The calcination may be performed in an air atmosphere at a temperature of 350°C to 1,100°C for 1 hour to 10 hours, or at a temperature of 500°C to 1,000°C for 1.5 hours to 8 hours, but is not limited thereto. If the calcination step is performed at a temperature below 350°C, the perovskite phase may not be properly formed, and if it exceeds 1,100°C, the durability of the porous metal support may be reduced, which is undesirable.

[0056] In one embodiment of the present application, the method may further include a step of measuring the weight of the second coating layer supported on the porous metal support after the second heat treatment step. In addition, by measuring the weight of the second coating layer supported on the porous metal support, the step of coating with the second solution and then performing the second heat treatment step may be repeated 2 to 10 times until a desired amount of catalyst is supported on the porous metal support.

[0057] In a methane reforming catalyst according to an embodiment of the present application, a first coating layer containing an inorganic oxide is formed, which not only improves adhesion between a porous metal support and a second coating layer containing a perovskite-based compound represented by Chemical Formula 1, but also prevents side reactions of the porous metal support.

[0058] Furthermore, the methane reforming catalyst according to one embodiment of the present application has a perovskite compound supported on a porous metal support having high thermal conductivity, and therefore has the advantage that it is easier to control the reaction heat compared to conventional pellet-shaped or powder-shaped catalysts.

[0059] In addition, the methane reforming catalyst according to one embodiment of the present application is characterized in that a synergistic effect exists between the first coating layer containing an inorganic oxide and the second coating layer containing a perovskite-based compound represented by Chemical Formula 1, which enables further increase in activity.

[0060] In addition, the methane reforming catalyst according to one embodiment of the present application can increase the active surface area of ​​the catalyst, thereby exhibiting high activity even at a high space velocity during the methane reforming reaction. [Example]

[0061] Hereinafter, the present application will be described in detail with reference to examples in order to specifically explain the present application. However, the examples of the present application can be modified into various different forms, and the scope of the present application is not to be construed as being limited to the examples detailed below. The examples of the present application are provided to more completely explain the present application to those skilled in the art.

[0062] <Example> Example 1 1) Preparation of the first solution An aqueous solution containing 40 wt% Ce(NO3)3·6H2O was prepared.

[0063] 2) Perovskite compounds represented by chemical formula 1 (Sr 0.92 Y 0.08 Ti 0.97 Ni 0.03 O 3-δ Preparation of the second solution containing precursors (0<δ<1) Perovskite compounds (Sr 0.92 Y 0.08 Ti 0.97 Ni 0.03 O 3-δA solution containing the precursor of ) was prepared using the citric acid method. Strontium nitrate (Sr(NO3)3·H2O) was dissolved in distilled water along with yttrium nitrate (Y(NO3)2), nickel nitrate (Ni(NO3)2), and citric acid. Titanium isopropoxide (Ti(OCH(CH3)2)4) was dissolved in ethylene glycol, and the two solutions were mixed at 70°C. After stirring for 3 hours, the solution was cooled to room temperature and stored. The concentration of the solution was 0.1M, the molar ratio of strontium:yttrium was 0.92:0.08, and the molar ratio of titanium:nickel was 0.97:0.03.

[0064] 3) Manufacturing of catalysts for methane reforming The first solution was dip-coated onto a porous metal support (NiCrAl, average pore size: 1,200 μm) (forming a first coating layer), dried at 150°C for 5 hours, and then heat-treated at 900°C in an air atmosphere for 5 hours. The dip-coating of the first solution, drying, and heat-treatment were performed once or repeatedly.

[0065] Then, the porous metal support on which the first coating layer was formed was dip-coated with the second solution (forming a second coating layer), dried at 150°C for 5 hours, and then heat-treated at 900°C in an air atmosphere for 5 hours. The dip-coating of the second solution, drying, and heat-treatment were repeated several times to finally form a first coating layer (CeO2) and a second coating layer (Sr 0.92 Y 0.08 Ti 0.97 Ni 0.03 O 3-δ , 0<δ<1). Based on the total weight of the methane reforming catalyst, the content of the first coating layer (CeO2) was 8 wt %, and the perovskite-based compound (Sr 0.92 Y 0.08 Ti 0.97 Ni 0.03 O 3-δ , 0<δ<1) was 15% by weight.

[0066] The content of the first coating layer and the content of the perovskite-based compound represented by Chemical Formula 1 can be calculated using the following Equations 1 and 2. [Number 1] Content of the first coating layer (wt%) = (total weight after forming the first coating layer - weight of the porous metal support) / (total weight of the catalyst) x 100 [Number 2] Content (wt%) of the perovskite compound represented by Chemical Formula 1 = (total weight of catalyst - total weight after forming the first coating layer) / (total weight of catalyst) × 100

[0067] <Example 2> The second solution was prepared in the same manner as in Example 1, except that precursors were used so that the molar ratio of strontium:yttrium:titanium:nickel was 0.88:0.12:0.90:0.10.

[0068] Example 3 The second solution was prepared in the same manner as in Example 2, except that precursors were used so that the molar ratio of titanium:nickel was 0.80:0.20.

[0069] Example 4 The second solution was prepared in the same manner as in Example 1, except that ruthenium chloride (RuCl3) was used instead of nickel nitrate so that the molar ratio of titanium:ruthenium was 0.85:0.15.

[0070] <Example 5> The same procedure as in Example 1 was carried out, except that when preparing the first solution, Al(NO)·9HO (25 wt%) was used instead of Ce(NO)·6HO to form the first coating layer of AlO.

[0071] Example 6 The same procedure as in Example 2 was repeated, except that when preparing the first solution, Al(NO)·9HO (25 wt%) was used instead of Ce(NO)·6HO to form the first coating layer of AlO.

[0072] Example 7 The same procedure as in Example 3 was repeated, except that when preparing the first solution, Al(NO)·9HO (25 wt%) was used instead of Ce(NO)·6HO to form the first coating layer of AlO.

[0073] Example 8 The same procedure as in Example 4 was carried out, except that when preparing the first solution, Al(NO)·9HO (25 wt%) was used instead of Ce(NO)·6HO to form the first coating layer of AlO.

[0074] Example 9 The first solution was prepared in the same manner as in Example 3, except that a 10 wt% suspension of YSZ (Yttria stabilized zirconia, Zr:Y molar ratio 0.92:0.08) dispersed in water was used instead of the 40 wt% aqueous solution of Ce(NO3)3·6H2O used in the first solution.

[0075] Example 10 The first solution was prepared in the same manner as in Example 4, except that a 10 wt% suspension of YSZ (Yttria stabilized zirconia, Zr:Y molar ratio 0.92:0.08) dispersed in water was used instead of the 40 wt% aqueous solution of Ce(NO3)3·6H2O used in the first solution.

[0076] Example 11 The first solution was prepared in the same manner as in Example 3, except that instead of the aqueous solution containing 40 wt % Ce(NO3)3·6H2O, an aqueous solution containing the respective nitrates was used so that the molar ratio of Ce:Zr:Al in the solution was 0.45:0.45:0.1.

[0077] Example 12 The first solution was prepared in the same manner as in Example 4, except that instead of the aqueous solution containing 40 wt % Ce(NO3)3·6H2O, an aqueous solution containing the respective nitrates was used so that the molar ratio of Ce:Zr:Al in the solution was 0.45:0.45:0.1.

[0078] Example 13 The first solution was prepared in the same manner as in Example 3, except that an aqueous solution containing nitrates of Al and Ce was used so that the molar ratio of Al:Ce in the solution was 0.3:0.7.

[0079] Example 14 The first solution was prepared in the same manner as in Example 4, except that an aqueous solution containing nitrates of Al and Ce was used so that the molar ratio of Al:Ce in the solution was 0.3:0.7.

[0080] Example 15 A 40 wt% Ce(NO3)3·6H2O aqueous solution was prepared as the 1-1 solution. This solution was dip-coated onto a porous metal substrate (NiCrAl, average pore size: 1,200 μm) to form the 1-1 coating layer. The dip-coating, drying, and heat-treatment were then carried out once or several times. A 25 wt% Al(NO3)3·9H2O aqueous solution was then prepared as the 1-2 solution. This solution was dip-coated onto the porous metal substrate with the 1-1 coating layer (forming the 1-2 coating layer). The dip-coating, drying, and heat-treatment were then carried out once or several times. The dip coating of the first and second solutions, drying and heat treatment were carried out once or repeatedly several times.

[0081] Then, the porous metal support on which the first-second coating layer was formed was dip-coated with the second solution applied in Example 3 (forming a second coating layer), dried at 150°C for 5 hours, and heat-treated at 900°C in an air atmosphere for 5 hours. The dip-coating of the second solution, drying, and heat-treatment were repeated several times to finally form the first coating layer (CeO2), the first-second coating layer (Al2O3), and the second coating layer (Sr 0.88 Y 0.12 Ti 0.80 Ni 0.20 O 3-δ , 0<δ<1) were prepared.

[0082] The content of the 1-1 coating layer, the content of the 1-2 coating layer, and the content of the perovskite-based compound represented by Chemical Formula 1 can be calculated by the following Equations 3 to 5. [Number 3] Content of the 1-1st coating layer (wt%) = (total weight after forming the 1-1st coating layer - weight of the porous metal support) / (total weight of catalyst) x 100 [Number 4] Content of the 1-2 coating layer (wt%) = (total weight after forming the 1-2 coating layer - total weight after forming the 1-1 coating layer) / (total weight of catalyst) × 100 [Number 5] Content (wt%) of the perovskite compound represented by Chemical Formula 1 = (total weight of catalyst - total weight after forming the first and second coating layers) / (total weight of catalyst) × 100

[0083] Example 16 The same procedure as in Example 7 was carried out, except that NiFeCrAl (average pore size: 1,200 μm) was used as the porous metal support instead of NiCrAl.

[0084] <Comparative Example 1> Only a porous metal support (NiCrAl, average pore size: 1,200 μm) was used as Comparative Example 1.

[0085] <Comparative Example 2> The same procedure as in Example 3 was carried out, except that the step of coating only the second solution was applied without the step of coating the first solution.

[0086] <Comparative Example 3> The same procedure as in Example 1 was carried out, except that the step of coating only the first solution was applied without the step of coating the second solution.

[0087] <Comparative Example 4> The same procedure as in Example 5 was carried out, except that the step of coating only the first solution was applied without the step of coating the second solution.

[0088] <Comparative Example 5> The same procedure as in Example 9 was carried out, except that the step of coating only the first solution was applied without the step of coating the second solution.

[0089] The compositions of the porous metal supports, the first coating layer, and the second coating layer in the above Examples and Comparative Examples are shown in Table 1 below.

[0090] [Table 1]

[0091] <Experimental Example 1> Dry reforming reaction evaluation of methane To perform the dry reforming reaction of methane, a fixed-bed reaction system was introduced. Each catalyst (about 2 g) of the Examples and Comparative Examples was filled using a quartz tube reactor (inner diameter = 1 / 2 inch, length = 50 cm). First, after undergoing a reduction process at 800 °C for 2 hours under the condition of 10% H2 / N2, the catalytic reaction was allowed to proceed for 100 hours. Gas composition: CH4:CO2:N2 = 1:1.12:0.96 Flow rate: GHSV (Gas Hour Space Velocity) = 1,500 hr -1 (Based on CH4) Reaction temperature: 800 °C Reaction pressure: 1 bar

[0092] The composition of the product gas was analyzed using gas chromatography (GC), and the reaction conversion rate after 100 hours of reaction was calculated and shown in Table 2 below. <0Q00421>Conversion rate (Xi, %) = [(Fi in - Fi out ) / Fi in × 100 (Fi = flow rate of i) <GC analysis conditions> 1) GC model: Agilent 6890 2) Oven temperature: 40 °C / 7 min - 90 °C / 5 min - 180 °C / 6 min 3) Detector: TCD, 250 °C 4) Sample loop: 0.25 mL 5) Valve box temperature: 150 °C

[0093] [Table 2]

[0094] <Experimental Example 2> Evaluation of Dry Reformation Reaction of Methane To conduct the dry reforming reaction of methane, a fixed-bed reaction system was introduced. A quartz tube reactor (inner diameter = 1 / 2 inch, length = 50 cm) was used and filled with each catalyst (about 2 g) of the examples and comparative examples. First, after undergoing a reduction process at 800 °C for 2 hours under the condition of 10% H2 / N2, the catalytic reaction proceeded for 100 hours. In order to more clearly compare the difference in coke formation between the catalysts, the activity characteristics of the catalysts were evaluated under pressurized conditions. Gas composition: CH4:CO2:N2 = 1:1.12:0.96 or 1:1.4:0.96 Flow rate: GHSV (Gas Hour Space Velocity) = 1,500 hr -1 (Based on CH4) Reaction temperature: 850 °C Reaction pressure: 4 barg

[0095] The composition of the produced gas was analyzed using gas chromatography (GC), and the reaction conversion rate after 100 hours of reaction was calculated and shown in Table 3 below. Conversion rate (Xi, %) = [(Fi in - Fi out ) / Fi in × 100 (Fi = flow rate of i) The coke generation rate was calculated using the following formula. Coke (%) = (weight of the catalyst after reaction - weight of the initial catalyst) / (weight of the catalyst after reaction) × 100 <GC Analysis Conditions> 1) GC model: Agilent 6890 2) Oven temperature: 40 °C / 7 min - 90 °C / 5 min - 180 °C / 6 min 3) Detector: TCD, 250 °C 4) Sample loop: 0.25 mL 5) Valve box temperature: 150 °C

[0096]

Table 3

[0097] As can be seen from the results in Tables 2 and 3, the methane reforming catalyst comprising a porous metal support according to an embodiment of the present application, a first coating layer comprising an inorganic oxide, and a second coating layer comprising a perovskite-based compound represented by Chemical Formula 1 above exhibited superior CH conversion and CO conversion rates, and an improved H / CO ratio, compared to the comparative example not including these components.

[0098] In particular, during catalytic reactions under pressurized conditions, a methane reforming catalyst comprising a porous metal support according to one embodiment of the present application, a first coating layer comprising an inorganic oxide, and a second coating layer comprising a perovskite-based compound represented by Chemical Formula 1 above, was found to produce significantly less coke than a comparative example that did not include such a configuration. This confirms that, in the examples of the present application, by forming a first coating layer comprising an inorganic oxide on the porous metal support, side reactions caused by the porous metal support and the second coating layer comprising a perovskite-based compound were reduced.

[0099] <Experimental Example 3> Evaluation of basic sites of catalyst A CO adsorption system (BELCAT II) was introduced to evaluate the basic sites of the catalysts. Each catalyst (approximately 0.1 g) from the examples and comparative examples was packed into a quartz cell. After undergoing a reduction process at 800°C for 2 hours under 5% H / Ar conditions, CO pulses (0.0086 cm) were applied at regular intervals at 50°C. 3 [STP] / pulse) was injected to allow adsorption to proceed. Adsorption was allowed to proceed until the area of ​​the CO2 peak that had passed through the catalyst no longer changed. Using a TCD detector, the area of ​​the CO2 peak that had passed through the catalyst without being adsorbed was used to calculate the amount of CO2 adsorbed during each pulse injection. The total amount of CO2 adsorbed during each pulse is shown in Table 4 below. CO2 adsorption amount (cm 3 [STP] / g cat)=[(A sat -A1)+(A sat -A2)+…] / A sat × 0.0086 (CO2 pulse injection volume, cm 3 [STP]) / g cat (A sat = CO2 peak area after full adsorption, A n = CO2 peak area at the injection of the nth pulse, g cat (= catalyst weight)

[0100] [Table 4]

[0101] As can be seen from the results in Table 4 above, a methane reforming catalyst comprising a porous metal support according to an embodiment of the present application, a first coating layer comprising an inorganic oxide, and a second coating layer comprising a perovskite-based compound represented by Chemical Formula 1 above, exhibits a higher CO adsorption capacity than a comparative example not including such a configuration.

[0102] Therefore, in a methane reforming catalyst according to an embodiment of the present application, by forming a first coating layer containing an inorganic oxide, it is possible to improve adhesion between a porous metal support and a second coating layer containing a perovskite-based compound represented by Chemical Formula 1, as well as to prevent side reactions of the porous metal support.

[0103] Furthermore, the methane reforming catalyst according to one embodiment of the present application has a perovskite compound supported on a porous metal support having high thermal conductivity, and therefore has the advantage that it is easier to control the reaction heat compared to conventional pellet-shaped or powder-shaped catalysts.

[0104] In addition, the methane reforming catalyst according to one embodiment of the present application is characterized in that a synergistic effect exists between the first coating layer containing an inorganic oxide and the second coating layer containing a perovskite-based compound represented by Chemical Formula 1, which enables further increase in activity.

[0105] In addition, the methane reforming catalyst according to one embodiment of the present application can increase the active surface area of ​​the catalyst, thereby exhibiting high activity even at a high space velocity during the methane reforming reaction.

Claims

1. porous metal support; a first coating layer provided on the porous metal support, the first coating layer comprising an inorganic oxide; and a second coating layer provided on the first coating layer and including a perovskite-based compound represented by the following Chemical Formula 1: The inorganic oxide is CeO ２ or Al ２ O ３ A catalyst for methane reforming comprising: [Chemical formula 1] Sr １－ｘ A ｘ Three １－ｙ B ｙ Oh ３－δ In the above Chemical Formula 1, A is selected from Y, Sc, La and the lanthanide series elements; B is Cr, Mn, Fe, Co, Ni, 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 0.5; δ is a real number greater than or equal to 0 and less than 1, (x+y)>0 is satisfied.

2. porous metal support; a first coating layer provided on the porous metal support, the first coating layer comprising an inorganic oxide; and a second coating layer provided on the first coating layer and including a perovskite-based compound represented by the following Chemical Formula 1: The first coating layer contains two or more of Al, Ce, Zr, Y, Ti and Si. [Chemical formula 1] Sr １－ｘ A ｘ Three １－ｙ B ｙ Oh ３－δ In the above Chemical Formula 1, A is selected from Y, Sc, La and the lanthanide series elements; B is Cr, Mn, Fe, Co, Ni, 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 0.5; δ is a real number greater than or equal to 0 and less than 1, (x+y)>0 is satisfied.

3. 3. The methane reforming catalyst according to claim 2, wherein the first coating layer is a single layer made of a composite oxide containing two or more of Al, Ce, Zr, Y, Ti, and Si.

4. The composite oxide is YSZ (Yttria-stabilized zirconia), Al ２ O ３ -CeO ２ , Al ２ O ３ -ZrO ２ , CeO ２ -ZrO ２ , Al ２ O ３ -TiO ２ , CeO ２ -TiO ２ or CeO ２ -ZrO ２ -Al ２ O ３ The methane reforming catalyst according to claim 3, wherein

5. the first coating layer has a double layer structure consisting of a first inorganic oxide layer containing one or more of Al, Ce, Zr, Y, Ti, and Si; and a second inorganic oxide layer containing one or more of Al, Ce, Zr, Y, Ti, and Si, 3. The methane reforming catalyst according to claim 2, wherein the first inorganic oxide layer and the second inorganic oxide layer contain different inorganic oxides.

6. The porous metal support is made of NiCrAlFe, NiCrAl, SiC or α-Al. ２ O ３ 3. The methane reforming catalyst according to claim 1, wherein the catalyst is a metal foam comprising:

7. 3. The methane reforming catalyst according to claim 1, wherein a content of the second coating layer containing the perovskite-based compound represented by Chemical Formula 1 is 3 wt % to 40 wt %, based on a total weight of the methane reforming catalyst.

8. Steam reforming, carbon dioxide reforming 2 3. The methane reforming catalyst according to claim 1 or 2, which is applied to a methane reforming process, a catalytic partial oxidation process, an autothermal reforming process, a tri-reforming process or a mixed reforming process.

9. The method comprises the steps of preparing a first solution containing a precursor of an inorganic oxide and a second solution containing a precursor of a perovskite-based compound represented by the following Chemical Formula 1: After coating the first solution on a porous metal support, a first heat treatment process is performed to prepare a catalyst precursor having a first coating layer; and and a step of coating the catalyst precursor having the first coating layer with the second solution and then performing a second heat treatment to prepare a catalyst having a second coating layer; The precursor of the inorganic oxide is CeO ２ Precursor of Al ２ O ３ or a precursor of a composite oxide containing two or more of Al, Ce, Zr, Y, Ti, and Si: [Chemical formula 1] Sr １－ｘ A ｘ Three １－ｙ B ｙ Oh ３－δ In the above Chemical Formula 1, A is selected from Y, Sc, La and the lanthanide series elements; B is Cr, Mn, Fe, Co, Ni, 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 0.5; δ is a real number greater than or equal to 0 and less than 1, (x+y)>0 is satisfied.

10. A step of preparing a 1-1 solution containing a precursor of a first inorganic oxide; a 1-2 solution containing a precursor of a second inorganic oxide; and a second solution containing a precursor of a perovskite-based compound represented by the following chemical formula 1: a step of coating the first solution on a porous metal support and then carrying out a first heat treatment process to prepare a catalyst precursor having a first inorganic oxide layer; coating the catalyst precursor having the first inorganic oxide layer with the first-2 solution, and then performing a first-2 heat treatment process to prepare a catalyst precursor having a second inorganic oxide layer; and and a step of coating the catalyst precursor having the second inorganic oxide layer with the second solution and then performing a second heat treatment to prepare a catalyst having a second coating layer; a method for producing a methane reforming catalyst, wherein the precursor of the first inorganic oxide and the precursor of the second inorganic oxide are different from each other and each independently is a precursor of an inorganic oxide containing one or more of Al, Ce, Zr, Y, Ti, and Si; [Chemical formula 1] Sr １－ｘ A ｘ Three １－ｙ B ｙ Oh ３－δ In the above Chemical Formula 1, A is selected from Y, Sc, La and the lanthanide series elements; B is Cr, Mn, Fe, Co, Ni, 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 0.5; δ is a real number greater than or equal to 0 and less than 1, (x+y)>0 is satisfied.

11. The porous metal support is made of NiCrAlFe, NiCrAl, SiC or α-Al. ２ O ３ 11. The method for producing a methane reforming catalyst according to claim 9 or 10, wherein the catalyst is a metal foam comprising:

12. The first coating layer is made of CeO ２ ; Al ２ O ３ or a composite oxide containing two or more of Al, Ce, Zr, Y, Ti and Si. [Request 13] The composite oxide is YSZ (Yttria-stabilized zirconia), Al ２ O ３ -CeO ２ , Al ２ O ３ -ZrO ２ , CeO ２ -ZrO ２ , Al ２ O ３ -TiO ２ , CeO ２ -TiO ２ or CeO ２ -ZrO ２ -Al ２ O ３ The method for producing a methane reforming catalyst according to claim 12,

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