Catalyst for methane reforming and method for producing same

Abstract

The present application provides a catalyst for methane reforming and a method for manufacturing the same, the catalyst for methane reforming comprising: a porous metal support; a first coating layer formed on the porous metal support; and a second coating layer formed on the first coating layer, wherein the first coating layer comprises a perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support; and the second coating layer comprises perovskite-based catalyst particles and a perovskite-based binder, wherein the perovskite-based catalyst particles and the perovskite-based binder each independently comprise a compound represented by Chemical Formula 1.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2022-0146236, filed with the Korean Intellectual Property Office on November 4, 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 gases caused by global warming, much research is being conducted into carbon dioxide conversion technologies. Carbon dioxide reforming, one of the carbon dioxide conversion technologies, is a technology that reacts methane and carbon dioxide to produce synthesis gas consisting of hydrogen and carbon monoxide.

[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 formulas 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 them, when a noble metal catalyst is used in the reforming process, it has advantages such as relatively less carbon deposition and higher reaction efficiency compared to nickel-based catalysts, but there is a problem in that the noble metal catalyst is expensive, resulting in reduced economic efficiency.

[0006] Therefore, relatively inexpensive nickel catalysts are mainly used in the reforming process. In particular, nickel catalysts supported on a support such as alumina are widely used as conventional catalysts. However, in such cases, there is a problem that the nickel catalyst is deactivated by carbon inevitably formed on the surface of the nickel catalyst.

[0007] Therefore, there is a need in the art to develop a catalyst that is resistant to carbon deposition and can be effectively applied in methane reforming processes. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 10-2019-0076367 Summary of the Invention [Problem to be solved by the invention]

[0009] The present application aims to provide a catalyst for methane reforming and a method for producing the same. [Means for solving the problem]

[0010] One embodiment of the present application provides a catalyst for methane reforming, comprising: a porous metal support; a first coating layer provided on the porous metal support; and a second coating layer provided on the first coating layer,

[0011] the first coating layer includes a perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support; the second coating layer includes perovskite-based catalyst particles and a perovskite-based binder; The perovskite-based catalyst particles and the perovskite-based binder each independently contain a compound represented by the following Chemical Formula 1, to provide a catalyst for methane reforming.

[0012] In another embodiment of the present application, a porous metal support is first coated with a first slurry containing a perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support; and a step of second-coating the catalyst with a second slurry containing perovskite-based catalyst particles and a perovskite-based binder after the first coating step, The perovskite-based catalyst particles and the perovskite-based binder each independently contain a compound represented by the following Chemical Formula 1: [Chemical formula 1] Sr 1-x A x Ti 1-y B y O 3-δ In the above Chemical Formula 1, A is Y, La or Ba; B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh; x is 0≦x<1, y is 0≦y<0.5, δ is a value that satisfies the balance, 0≦δ<1, The x and y satisfy x+y>0. [Effects of the Invention]

[0013] A methane reforming catalyst according to one embodiment of the present application includes a perovskite-based compound having a thermal expansion coefficient of 65% or more compared to that of a porous metal support, thereby suppressing the reactivity of the porous metal support itself, which may cause side reactions or coke, and improving the adhesion of catalyst components at high temperatures.

[0014] In addition, the second coating layer may be formed in the form of perovskite nanoparticles by directly coating perovskite-based catalyst particle components onto a porous metal support without a separate binder, thereby increasing the active surface area of ​​the methane reforming catalyst.

[0015] These features increase the active surface area of ​​the methane reforming catalyst, enabling it to exhibit good activity even at high space velocities during the methane reforming reaction and enabling stable operation for long periods of time without carbon deposition or sintering. DETAILED DESCRIPTION OF THE INVENTION

[0016] This specification will be explained in more detail below.

[0017] 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 another member is present between the two members.

[0018] In this specification, when a part is said to "comprise" a certain component, this means that it may further include other components, rather than excluding other components, unless otherwise specified to the contrary.

[0019] In this specification, "p to q" means "at least p and at most q."

[0020] In this specification, the term "thermal expansion coefficient" refers to one of the lengths of a specific object stretched in three directions, i.e., the x-axis, y-axis, and z-axis, when the temperature of the object is increased by 1°C from 25°C to 800°C.

[0021] As used herein, the term "perovskite-based catalyst particles" refers to a catalyst having a perovskite structure that is in particle form and not in sol form, i.e., the catalyst is not dissolved in a separate solvent.

[0022] In this specification, the term "perovskite-based compound" refers to a compound that has a perovskite structure but does not function as a catalyst.

[0023] In this specification, the term "perovskite-based binder" refers to a substance formed from the perovskite-based catalyst sol, which is formed from a solution containing a precursor of the perovskite-based compound and a solvent.

[0024] Currently, the catalysts commonly used in reformers are generally powder catalysts and pellet-type support catalysts. Powder catalysts have excellent catalyst dispersion and performance, but their direct industrial application is difficult. For example, when a reformer is operated using a powder catalyst, the catalyst is released together with the products produced after the catalyst reaction. In this case, the powder catalyst gradually accumulates in the outlet flow tube, which can eventually clog the entire tube. Therefore, a disadvantage is that powder catalysts cannot be used in commercial reformers for industrial use.

[0025] Pellet-type support catalysts are currently widely used in industrial reformers. While their performance is lower than that of powder-type catalysts due to mass transfer rate limitations, they offer the advantage of long-term use due to the use of a support. However, γ-Al2O3 pellets, which are commonly used as pellet-type support catalysts, have the disadvantage of weak structural strength and fragility, which can lead to differential pressure within the reactor. Furthermore, pellet-type support catalysts are bulky, which can be very large when used in high-capacity reformers. Furthermore, while all reforming reactions are sensitive to reaction temperature, conventional pellet-type catalysts have the disadvantage of significantly reduced thermal conductivity, resulting in uneven heat distribution throughout the reactor.

[0026] Therefore, in this application, we have attempted to improve not only the phenomenon of clogging of flow tubes, which is a drawback of powder-type catalysts, but also the common drawback of both powder-type and pellet-type catalysts, namely, the rate of heat and mass transfer, by coating a catalyst on a porous metal support, which has a high rate of heat and mass transfer.

[0027] The porous metal support catalyst can be prepared by coating the surface of a porous metal support with a slurry prepared by mixing a catalyst precursor or catalyst powder with a binder and additives. To attach catalyst particles to the surface of the porous metal support, an organic binder and / or an inorganic binder can be added during the preparation of the slurry. The organic binder remains in the slurry until drying and calcination, contributing to reducing surface tension and stabilizing the slurry. The inorganic binder remains between catalyst particles or between the catalyst particles and the porous metal support after calcination, fixing the catalyst particles to the porous metal support. It is typically added in the form of silica, alumina sol, or colloid. Using a large amount of inorganic binder has the advantage of strengthening the bond between the catalyst particles and the porous metal support. However, the presence of a large amount of binder on the surface of the catalyst particles can reduce reaction sites, affect the catalyst, and participate in the reaction, potentially causing undesirable side reactions. Therefore, a catalyst precursor may be used directly to directly introduce a catalyst into a porous metal support without a binder, but this has the drawback of only being able to support a small amount of catalyst at a time.

[0028] Therefore, an object of the present application is to provide a methane reforming catalyst that can support a large amount of catalyst at one time and can suppress side reactions caused by the binder.

[0029] One embodiment of the present application provides a catalyst for methane reforming, comprising: a porous metal support; a first coating layer formed on the porous metal support; and a second coating layer formed on the first coating layer, wherein the first coating layer comprises a perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support, and the second coating layer comprises perovskite-based catalyst particles and a perovskite-based binder, and the perovskite-based catalyst particles and the perovskite-based binder each independently comprise a compound represented by the following Chemical Formula 1: [Chemical formula 1] Sr 1-x A x Ti 1-y B y O 3-δ In the above Chemical Formula 1, A is Y, La or Ba; B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh; x is 0≦x<1, y is 0≦y<0.5, δ is a value that satisfies the balance, and 0≦δ<1. The x and y satisfy x+y>0.

[0030] The methane reforming catalyst according to the present application contains a perovskite-based compound in the coating layer, which has a thermal expansion coefficient of 65% or more compared to that of the porous metal support. This suppresses the reactivity of the porous metal support itself, which may cause side reactions or coke, and improves the adhesion of catalyst components at high temperatures.

[0031] In addition, the second coating layer may be formed in the form of perovskite nanoparticles by directly coating perovskite-based catalyst particle components onto a porous metal support without a separate binder, thereby increasing the active surface area of ​​the methane reforming catalyst.

[0032] Due to these characteristics, the active surface area of ​​the methane reforming catalyst increases, allowing it to exhibit good activity even at high space velocities during the methane reforming reaction, and enabling stable operation for long periods of time without carbon deposition or sintering.

[0033] In one embodiment of the present application, the first coating layer may include a perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support.

[0034] In one embodiment of the present application, the thermal expansion coefficient of the perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support may satisfy the following formula 1: [Formula 1] 10.0×10 -6 K -1 ≦G1≦14.0×10 -6 K -1 In the formula 1, G1 represents the thermal expansion coefficient. In one embodiment of the present application, G1 is 10.0 × 10 -6 K -1 ≦G1≦14.0×10 -6 K -1 Preferably, it is 10.0×10 -6 K -1 ≦G1≦13.0×10 -6 K -1 may be.

[0035] In one embodiment of the present application, the content of the perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the porous metal support may be 1 wt% to 20 wt%, or 1.5 wt% to 18 wt%, based on the total weight of the methane reforming catalyst. When the content is within this range, the performance of the methane reforming catalyst according to the present application may be improved, such as suppressing the reactivity of the porous metal support itself, which may induce side reactions or coke, and improving the adhesion of catalyst components at high temperatures.

[0036] Specifically, if the content of the perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the porous metal support exceeds 20 wt%, the capacity available for coating the second coating layer (catalyst layer) may decrease, which may result in a lower catalytic activity relative to the volume of the porous metal support, which is undesirable.Furthermore, if the content of the perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the porous metal support is less than 1 wt%, the content may be so small that it may be difficult to obtain the effects of the first coating layer.

[0037] In one embodiment of the present application, the perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support may be represented by the following Chemical Formula 3: [Chemical formula 3] Sr 1-a Y a TiO 3-δ In the above Chemical Formula 3, a is 0≦a<1, δ is a value that satisfies the balance, and is in the range of 0≦δ≦1.

[0038] In one embodiment of the present application, the perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support may be represented by the following formula 3-1 or SrTiO3. [Chemical formula 3-1] Sr 1-a Y a TiO 3-δ In the above Chemical Formula 3-1, a is 0 <a<1であり、 δ is a value that satisfies the balance, and is 0≦δ<1.

[0039] In one embodiment of the present application, the above Chemical Formula 1 may be represented by the following Chemical Formula 2: [Chemical formula 2] Sr 1-x Y x Ti 1-y B y O 3-δ In the above Chemical Formula 2, B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh; x is 0≦x<0.3, y is 0≦y<0.2, δ is a value that satisfies the balance, 0≦δ<1, The x and y satisfy x+y>0.

[0040] In one embodiment of the present application, B in the above Chemical Formula 2 may be Ni or Ru.

[0041] In one embodiment of the present application, the porous metal support may include a material capable of maintaining thermal stability at high temperatures of 800° C. or higher. More specifically, in one embodiment of the present application, the porous metal support may be made of a material capable of maintaining thermal stability at high temperatures of 800° C. or higher.

[0042] In one embodiment of the present application, the porous metal support may include one or more selected from NiCrAlFe, NiCrAl, stainless steel, and inconel. More specifically, in one embodiment of the present application, the porous metal support may be composed of one or more selected from NiCrAlFe, NiCrAl, stainless steel, and inconel.

[0043] The porous metal support can have a variety of shapes, has a small 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%, preferably 50% to 96%. The average pore size of the porous metal support may be 150 μm to 4,000 μm, 200 μm to 3,500 μm, or 400 μm to 3,000 μm. Most preferably, it may be 700 μm to 2,000 μm. The porous metal support can be appropriately prepared by those skilled in the art using methods well known in the art, taking into consideration the material, pore size, and porosity of the porous metal support.

[0044] In one embodiment of the present application, the content of the perovskite-based catalyst particles and perovskite-based binder, based on the total weight of the methane reforming catalyst, may be 3 wt% to 40 wt%, 6 wt% to 35 wt%, or 7 wt% to 30 wt%. If the content of the perovskite-based catalyst particles and perovskite-based binder, based on the total weight of the methane reforming catalyst, is less than 3 wt%, the reactivity may be reduced due to a relatively small number of active sites on the catalyst surface, which is undesirable. Furthermore, if the content of the perovskite-based catalyst particles and perovskite-based binder exceeds 40 wt%, the amount of catalyst components contained is relatively large relative to the porous metal support, making it difficult to maintain the pore structure and to easily bond the catalyst components to the porous metal support, which may reduce the practical benefits of the methane reforming reaction.

[0045] Here, the content of the perovskite-based catalyst particles and the perovskite-based binder refers to the sum of the content of the perovskite-based catalyst particles and the content of the perovskite-based binder.

[0046] In one embodiment of the present application, at least a portion of the surface of the catalyst particle may include a protrusion shape. The protrusion shape may be, but is not limited to, a spherical shape, an oval shape, or a combination thereof. The average diameter of each of the protrusions may be 20 nm to 1 μm. The protrusions may cover the entire surface of the catalyst particle, or may cover only a portion of the surface of the catalyst particle.

[0047] In one embodiment of the present application, the perovskite-based binder may serve as an inorganic binder to fix the perovskite-based catalyst particles on the porous metal support. The perovskite-based binder may also be present in the form of protrusions on the perovskite-based catalyst particles, thereby increasing the reaction surface area of ​​the catalyst and improving the performance of the methane reforming reaction.

[0048] According to one embodiment of the present application, by additionally applying a perovskite-based binder in addition to the perovskite-based catalyst particles, the amount of catalyst supported on a porous metal support can be increased when coated once compared to when catalyst particles are applied alone. Furthermore, by applying the perovskite-based binder according to one embodiment of the present application, side reactions and catalyst phase changes that may occur when silica or other colloidal inorganic binders are applied can be prevented, thereby improving the performance of the methane reforming reaction.

[0049] 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 is not particularly limited to a methane reforming process.

[0050] One embodiment of the present application provides a method for preparing a catalyst for methane reforming, comprising: a step of primarily coating a porous metal support with a first slurry containing a perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the porous metal support; and a step of, after the first coating, secondary coating with a second slurry containing perovskite-based catalyst particles and a perovskite-based binder; wherein the perovskite-based catalyst particles and the perovskite-based binder each independently contain a compound represented by Chemical Formula 1.

[0051] As described above, the method for preparing a methane reforming catalyst according to an embodiment of the present application can suppress the reactivity of the porous metal support itself, which may cause side reactions or coke formation, and can thereby prepare a methane reforming catalyst with improved adhesion of catalytic components.

[0052] In addition, since the perovskite-based catalyst particle component can be directly coated on the porous metal support without a separate binder during the formation of the second coating layer, the perovskite-based catalyst component can be formed in the form of nanoparticles, which can increase the active surface area of ​​the methane reforming catalyst prepared by the method for preparing a methane reforming catalyst according to an embodiment of the present disclosure.

[0053] Due to these characteristics, the prepared methane reforming catalyst has an increased active surface area, and exhibits good activity even at high space velocities during the methane reforming reaction. It also has the advantage of being able to operate stably for a long period of time without carbon deposition or sintering.

[0054] In the method for preparing a methane reforming catalyst according to an embodiment of the present application, the porous metal support, the perovskite-based compound, the perovskite-based catalyst particles, and the perovskite-based binder may be the same as those described above.

[0055] In particular, the perovskite-based binder of the methane reforming catalyst may be formed from the perovskite-based catalyst sol.

[0056] As described above, the perovskite catalyst sol may be formed from a solution containing a precursor of a perovskite compound and a solvent. The precursor of the perovskite compound is a precursor of a metal constituting the perovskite compound, and the metal molar ratio of the perovskite compound can be adjusted by adjusting the content of the precursor. The metal precursor is not particularly limited, and ammonium salts, nitrates, carbonates, chlorides, lactates, hydroxides, organic acid salts, oxides, or mixtures thereof of the metal elements may be used. The solvent is not particularly limited, and any solvent known in the art may be used. For example, the solvent may be water, an alcohol-based solvent, or the like, but is not limited thereto.

[0057] The method for preparing a methane reforming catalyst according to an embodiment of the present application may further include preparing a first slurry containing a perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support.

[0058] In one embodiment of the present application, the first slurry may contain a perovskite-based compound in powder form, the perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support.

[0059] In one embodiment of the present application, the first slurry may not contain a binder. The binder may be an organic binder and / or an inorganic binder. That is, a binder may not be used for the purpose of directly incorporating a perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the porous metal support into the porous support.

[0060] In one embodiment of the present application, the first slurry may be mixed with an additive other than the perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the powder-form porous metal support. The additive may be a substance commonly used in the art.

[0061] In one embodiment of the present application, the content of the perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the porous metal support may be 1 wt% to 20 wt%, or 1.5 wt% to 18 wt%, based on the total weight of the first slurry. When the content is within this range, the performance of the methane reforming catalyst according to the present application is further improved, such as suppressing the reactivity of the porous metal support itself, which may induce side reactions or coke, and improving the adhesion of catalyst components at high temperatures.

[0062] As mentioned above, if the content of the perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the porous metal support exceeds 20 wt%, the capacity available for coating the second coating layer (catalyst layer) decreases, which may result in a decrease in catalytic activity relative to the volume of the porous metal support, which is undesirable. Also, if the content of the perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the porous metal support is less than 1 wt%, the amount is so small that it may be difficult to obtain the effects of the first coating layer.

[0063] The method for producing a methane reforming catalyst according to an embodiment of the present application may further include preparing the second slurry containing the perovskite-based catalyst particles and the perovskite-based binder.

[0064] In one embodiment of the present application, the second slurry may contain the perovskite-based catalyst particles in powder form. In one embodiment of the present application, the second slurry may contain a binder. The binder may be an organic binder and / or an inorganic binder.

[0065] In one embodiment of the present application, the second slurry may contain additives other than the perovskite-based catalyst particles and the perovskite-based binder. The additives may be substances commonly used in the art.

[0066] A method for preparing a methane reforming catalyst according to one embodiment of the present application includes a step of first coating a porous metal support with a first slurry including a perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support.

[0067] A method for preparing a methane reforming catalyst according to an embodiment of the present application includes, after the first coating step, a second coating step with a second slurry including perovskite-based catalyst particles and a perovskite-based binder.

[0068] In one embodiment of the present application, the step of preparing the second slurry including the perovskite-based catalyst particles and the perovskite-based binder includes the step of preparing the second slurry by mixing the perovskite-based catalyst particles and a perovskite-based catalyst sol. The above-mentioned description may be applied to the perovskite-based catalyst sol, and a solvent used in preparing the perovskite-based catalyst sol may be additionally added to adjust the concentration of the second slurry.

[0069] In the method for preparing a methane reforming catalyst according to an embodiment of the present application, the first coating with the first slurry and the second coating with the second slurry each include impregnating the porous metal support with the first slurry or the second slurry, respectively, and may further include removing excess slurry from the porous metal support.

[0070] In one embodiment of the present application, the step of first coating with the first slurry may be a step of impregnating the porous metal support with the first slurry.

[0071] In one embodiment of the present application, the second coating with the second slurry may be a step of impregnating the porous metal support with the second slurry.

[0072] In one embodiment of the present application, the concentration of the perovskite binder represented by Chemical Formula 1 may be 0.05M to 1M, preferably 0.08M to 1M, more preferably 0.1M to 1M, and most preferably 0.1M to 0.8M.

[0073] The coating methods for the first and second coating steps may be methods well known in the art, such as, but not limited to, dip-coating and wash-coating.

[0074] A method for preparing a methane reforming catalyst according to an embodiment of the present application may further include a drying and calcination step after the second coating step, i.e., after the first coating and the second coating are completed, a drying and calcination step may be further included.

[0075] In this case, the drying may be carried out 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 to these.

[0076] The firing may be carried out in an air atmosphere at a temperature of 350°C to 1,100°C for 1 hour to 10 hours, or in an air atmosphere at a temperature of 500°C to 1,000°C for 1.5 hours to 8 hours, but is not limited to these.

[0077] In the method for preparing a methane reforming catalyst according to an embodiment of the present application, the porous metal support, the perovskite-based catalyst component, and the like are the same as those described above.

[0078] A methane reforming catalyst according to an embodiment of the present application has catalytic components supported on a porous metal support having high thermal conductivity, and therefore exhibits good activity even at high space velocities during methane reforming reactions and is characterized by being capable of stable operation for long periods of time without carbon deposition or sintering.

[0079] In one embodiment of the present application, the catalyst may be applied to steam reforming, carbon dioxide reforming, catalytic partial oxidation, autothermal reforming, tri-reforming, or mixed reforming, and is not particularly limited to methane reforming.

[0080] In one embodiment of the present application, the methane reforming process may include contacting a mixed feedstock with the catalyst of the present application. The mixed feedstock may include CH4 and CO2.

[0081] In one embodiment of the present application, the methane reforming process may include contacting a mixed feedstock with the catalyst of the present application in a reactor. The mixed feedstock may include CH4 and CO2. The reactor may be a reactor commonly used in the art.

[0082] In one embodiment of the present application, the methane reforming process may further include the steps of: filling the reactor with the catalyst according to the present application; and subjecting the reactor filled with the catalyst to H / N reducing conditions.

[0083] In one embodiment of the present application, the step of reducing the reactor filled with the catalyst with H2 / N2 may be to reduce the reactor filled with the catalyst under H2 / N2 conditions at a temperature of 700°C to 800°C for 1 hour to 2 hours.

[0084] In one embodiment of the present application, the H2 / N2 condition refers to the volume ratio of hydrogen (H2) to nitrogen (N2), and H2 / N2 may be 5% to 12%, preferably 10%.

[0085] In one embodiment of the present application, the methane reforming step may be a commonly used methane reforming step, except that the methane reforming catalyst of the present application is used. [Example]

[0086] Hereinafter, in order to specifically explain the present application, a detailed description will be given using examples. However, the examples of the present application may be modified into various other forms, and the scope of the present application should not be construed as being limited to the examples described below. The examples of the present application are provided to more completely explain the present application to those skilled in the art.

[0087] <Example> 1) Example 1 - Preparation of catalyst for methane reforming

[0088] (1) <Production Example 1> - Production of the first coating layer SrTiO3 (Sr of Formula 3 in this application) was obtained by the citric acid method. 1-a Y a TiO 3-δ A solution was prepared (where a = 0 and δ = 0). Specifically, strontium nitrate (Sr(NO3)3H2O) and yttrium(III) nitrate hexahydrate were dissolved in distilled water together with citric acid and ethylene glycol. Titanium isopropoxide (Ti(OCH(CH3)2)4) was dissolved in ethanol, and the two solutions were mixed at 70°C. After stirring for 3 hours, SrTiO3 (Sr 1-a A a TiO 3-δ where a=0 and δ=0) was prepared.

[0089] Next, the first slurry solution was dip-coated (primary coating) onto a porous metal support (NiFeCrAl) having a pore size of 800 μm, dried at 70°C for 24 hours, and then heat-treated at 300°C to 900°C in an air atmosphere for 3 hours to produce a porous metal support (NiFeCrAl) coated with SrTiO3 as a primary coating layer.

[0090] At this time, the content of SrTiO3 was 7 wt% based on the total weight of the first coating layer.

[0091] (2) <Production Example 2> - Production of the second coating layer SrTi through the citric acid method 0.90 Ni 0.1 O 3-δ Perovskite-based catalyst particles represented by the formula (Sr 1-x A x Ti 1-y B y O3-δ where B is Ni, x=0, y=0.1) and SrTi 0.97 Ni 0.03 O 3-δ Perovskite-based catalyst particles represented by the formula (Sr 1-x A x Ti 1-y B y O 3-δ where B is Ni, x=0, and y=0.03) was produced.

[0092] Specifically, the same procedure as in Preparation Example 1 was carried out, except that a certain amount of nickel nitrate (Ni(NO3)2) was added to prepare the first solution so that the nickel (Ni) content and titanium (Ti) content were 10 mol% and 3 mol% of the sum of nickel (Ni) and titanium (Ti), respectively. 0.90 Ni 0.1 O 3-δ A solution containing a perovskite compound represented by the formula SrTi 0.97 Ni 0.03 O 3-δ A solution containing a perovskite compound represented by the following formula was prepared.

[0093] SrTi produced by the above method 0.90 Ni 0.1 O 3-δ In the case of a solution containing a perovskite compound represented by the formula (I), it is dried at 70°C for 24 hours, and then heat-treated at 900°C in an air atmosphere for 3 hours to obtain SrTi 0.90 Ni 0.1 O 3-δ The perovskite-based catalyst particles represented by the formula:

[0094] In addition, SrTi produced by the above method 0.97 Ni 0.03 O 3-δ In the case of a solution containing a perovskite compound represented by SrTi 0.97 Ni 0.03 O 3-δ By adding water to the perovskite compound, the concentration of SrTi0.97 Ni 0.03 O 3-δ A perovskite binder represented by the formula:

[0095] In this case, the perovskite-based catalyst particles and the perovskite-based binder were mixed so that the content of the perovskite-based catalyst particles was 5 wt% based on the total amount of the perovskite-based catalyst particles and the perovskite-based binder, to prepare a second solution (hereinafter referred to as second slurry).

[0096] Next, the second slurry was dip-coated (second coating) onto the porous metal support (NiFeCrAl) coated with the first coating layer of SrTiO3 of Preparation Example 1, and excess slurry was removed from the porous metal support using a blower.

[0097] After that, it was dried at 70℃ for 1 hour to remove the solvent, and then heat-treated at 900℃ in an air atmosphere for 5 hours to form the first coating layer containing SrTiO3 and SrTi 0.90 Ni 0.1 O 3-δ Perovskite-based catalyst particles represented by 0.97 Ni 0.03 O 3-δ A methane reforming catalyst including a second coating layer containing a perovskite-based catalyst binder represented by the formula (I) was prepared. The catalyst coating amount per coating was 3.5 wt%, and the second coating was repeated to finally prepare the methane reforming catalyst of Example 1 (supported catalyst content: 14.8% based on the total weight of the methane reforming catalyst).

[0098] The type of porous metal support used in Example 1, the materials contained in the first coating layer and the second coating layer, and the amount of catalyst supported based on the total weight of the methane reforming catalyst are shown in Table 1 below.

[0099] 2) Examples 2 to 9 and Comparative Examples 1 to 10 The catalysts of Examples 2 to 9 and Comparative Examples 1 to 10 were prepared in the same manner as in Example 1, except that in the method for preparing a methane reforming catalyst of Example 1, a porous metal support shown in Table 1 below was used as the porous metal support, and materials shown in Table 1 below were used as materials for the first coating layer and the second coating layer to prepare catalysts having catalyst contents shown in Table 1 below.

[0100] For example, Comparative Example 4 can be interpreted as having a porous metal support (NiFeCrAl) on which neither the first nor the second coating layer is formed.

[0101] For reference, materials A and B used in the first and second coating layers in Table 1 below were prepared using the citric acid method used in Preparation Example 1 or Preparation Example 2. Specifically, solutions prepared to satisfy the respective composition ratios when applying the citric acid method were used. When yttrium (Y) was added, yttrium nitrate (Y(NO3)2) was added, and when ruthenium (Ru) was added, ruthenium chloride monohydrate (RuCl3H2O) was added.

[0102] [Table 1-1] [Table 1-2]

[0103] In Table 1, material A corresponds to a perovskite-based compound, material B corresponds to a perovskite-based catalyst particle, and binder corresponds to a perovskite-based binder.

[0104] In Table 1, content A refers to the content (%) of material A in Table 1 based on the total weight of the first coating layer, content B refers to the content (%) of material B in Table 1 based on the total amount of perovskite-based catalyst particles and perovskite-based binder (total amount of second slurry), and catalyst content refers to the content (%) of catalyst supported on the metal structure based on the total weight of the methane reforming catalyst. Specifically, supported catalyst refers to the amount of perovskite-based compound supported on the metal structure.

[0105] In addition, the pore size in Table 1 means the average pore size.

[0106] Finally, in Table 1, the loading amount (%) at one coating refers to the content (%) of the perovskite structure compound loaded on the catalyst at one coating, based on the total weight of the methane reforming catalyst, during the process of repeatedly coating the second coating layer to satisfy the catalyst content in Table 1, i.e., to satisfy the amount of the perovskite structure compound loaded on the metal structure. In this case, the amount of the perovskite structure compound loaded on the metal structure refers to the sum of the perovskite structure compound in the first coating layer, the perovskite structure compound in the perovskite structure catalyst particles included in the second coating layer, and the perovskite structure compound included in the perovskite structure binder.

[0107] Here, the perovskite structure compound means a compound that satisfies the following chemical formula A. [Chemical formula A] Sr 1-x A x Ti 1-y B y O 3-δ In the above chemical formula A, A is Y, La or Ba; B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh; x is 0≦x<1, y is 0≦y<1, δ is a value that satisfies the balance, and 0≦δ<1. The x and y satisfy x+y>0.

[0108] Therefore, in Table 1, for Comparative Examples 1, 3, and 4, which do not contain the compound represented by Chemical Formula A in either the first or second coating layer, the loading amount (%) and catalyst content at the time of first coating are not recorded. In Comparative Example 8, the compound represented by Chemical Formula A is contained in the second coating layer as catalyst particles (substance B), but due to the absence of a binder, the second coating layer does not adhere properly to the porous metal support, resulting in no loading, and therefore the loading amount (%) and catalyst content at the time of first coating are not recorded.

[0109] In the case of Comparative Example 9, in which only the binder was included in the second coating layer, it was confirmed that the loading amount (%) after one coating was very low compared to the Examples. In other words, it was confirmed that if the second coating layer contained only the binder according to the present application without the catalyst particles according to the present application, it would take a lot of time and cost to manufacture the catalyst.

[0110] Thereafter, the durability of the catalysts of the Examples and Comparative Examples in Table 1 was evaluated at 800°C, which is the reaction temperature for the dry reforming reaction of methane. As a result, no cracks were found in the catalysts of Examples 1 to 9, but some cracks were found in the catalysts of Comparative Examples 2 to 5.

[0111] In this regard, referring to Table 2 below, it was confirmed that the materials used in the catalysts of the examples in Table 1 above included a perovskite-based compound in the primary coating layer having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support.

[0112] In addition, it was confirmed that the perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support satisfies the following formula 1. [Formula 1] 10.0×10 -6 K -1 ≦G1≦14.0×10 -6 K-1 In formula 1 above, G1 represents the coefficient of thermal expansion.

[0113] That is, it was confirmed that the catalysts of Examples 1 to 9 have excellent durability at high temperatures because the difference between the coefficient of thermal expansion of the porous metal support and the coefficient of thermal expansion of the perovskite compound contained in the first coating layer is not large.

[0114]

Table 2

[0115] <Experimental Example> - Dry reforming reaction evaluation of methane To carry out the dry reforming reaction of methane, a fixed bed reaction system was introduced. Using a quartz tube reactor (inner diameter = 1 / 2 inch, length = 50 cm), about 2 g of the methane reforming catalyst shown in Table 3 below was filled.

[0116] After that, under the condition of 10% H2 / N2, after a reduction process at 800 °C for 1 to 2 hours, the catalytic reaction was carried out for 100 hours.

[0117] After that, the reaction was carried out while satisfying the following conditions to evaluate the activity characteristics of the catalyst. For reference, the following conditions were set to evaluate the activity characteristics of the catalyst at a severe space velocity in order to more clearly compare the activity differences between the catalysts. <Experimental conditions> [[ID=三十二]]Gas composition: CH4:CO2:N2 = 1:1.2:0.96 Flow rate: GHSV (Gas Hour Space Velocity) = 1,500 hr -1 (Based on CH4) Reaction temperature: 800 °C Reaction pressure: 1 bar

[0118] After that, 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 3 below. <GC analysis conditions> 1) GC model: Agilent 6890 2) Oven temperature: 40℃ / 7min - 90℃ / 5min - 180℃ / 6min 3) Detector: TCD, 250℃ 4) Sample loop: 0.25 mL 5) Valve box temperature: 150℃

[0119] [Table 3]

[0120] The conversion rates in Table 3 were calculated according to the following formula 2. [Formula 2] Conversion rate (Xi,%) = [(Fi in -Fi out ) / Fi in ]×100(%)(Fi=flow rate of i)

[0121] As can be seen from the results in Table 3, the catalysts of Examples 1 to 9 were found to have higher CH4 conversion rates (%) and CO2 conversion rates (%) than the catalysts of Comparative Examples.

[0122] In particular, compared to the catalysts of Comparative Examples 1 to 4, which do not have a second coating layer, it was confirmed that the catalysts of Examples 1 to 9 had significantly higher CH4 conversion rates (%) and CO2 conversion rates (%).

[0123] Furthermore, it was confirmed that the catalysts of Examples 1 to 9 had higher CH4 conversion rates (%) and CO2 conversion rates (%) than the catalyst of Comparative Example 5, which did not have a primary coating layer.

[0124] In Comparative Example 8, where the second coating layer contained catalyst particles according to the present application but no binder, the second coating layer did not adhere properly to the porous metal support due to the absence of a binder. As a result, the CH4 conversion rate (%) and CO2 conversion rate (%) were very low, confirming that the catalyst did not function as a methane reforming catalyst.

[0125] In addition, in Comparative Example 9, the performance of the catalyst produced may be at the same level as in the Examples. However, as mentioned above, when the second coating layer contains the binder according to the present application but does not contain the catalyst particles according to the present application, as in Comparative Example 9, the loading amount (%) at one coating is very small, which means that it takes a lot of time and costs to produce the catalyst.

[0126] In addition, the degree of coke generation was measured for Examples 1 to 7 and Comparative Examples 6, 7, and 10, which had similar reaction results, CH conversion rates (%), and CO conversion rates (%). Specifically, the degree of coke generation was calculated using the following equation 3, and the results are shown in Table 4 below.

[0127] For reference, the larger the value calculated by the following formula 3, the more coke was generated. [Formula 3] Coke generation rate (%) = [catalyst weight after reaction - catalyst weight before reaction) / catalyst weight before reaction] x 100 (%)

[0128] [Table 4]

[0129] As can be seen from the results in Table 4, the catalysts according to the present invention exhibited significantly lower coke generation rates. In particular, the coke generation rates of Comparative Examples 6 and 7, which had significantly lower Ti contents than the catalysts according to the present invention, were significantly higher. This is thought to be due to the fact that the perovskite structure was not well formed due to the very low Ti content, resulting in the Ni remaining in a bulk form.

[0130] Therefore, compared to comparative catalysts with similar CH4 conversion rates (%) and CO2 conversion rates (%), the catalysts according to the present invention can prevent the problem of nickel catalyst deactivation due to carbon generated on the surface of the nickel catalyst during high-temperature reactions, as confirmed by the results in Table 4. This means that the catalysts according to the present invention have the advantage of being durable at high temperatures and therefore can be used for long periods of time during high-temperature reactions.

[0131] In conclusion, it was confirmed that the catalyst of the present application has excellent durability at high temperatures and high catalytic activity, as described above.

Claims

1. porous metal support; a first coating layer disposed on the porous metal support; and a second coating layer provided on the first coating layer; A catalyst for methane reforming comprising: the first coating layer includes a perovskite-based compound having a thermal expansion coefficient of 65% or more compared to the thermal expansion coefficient of the porous metal support; the second coating layer includes perovskite-based catalyst particles and a perovskite-based binder; The perovskite-based catalyst particles and the perovskite-based binder each independently comprise a compound represented by the following Chemical Formula 1: [Chemical formula 1] Sr １－ｘ A ｘ Three １－ｙ B ｙ Oh ３－δ In the above Chemical Formula 1, A is Y, La or Ba; B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh; x is 0≦x<1, y is 0≦y<0.5, δ is a value that satisfies the balance, and 0≦δ<1; The x and y satisfy x+y>0.

2. The methane reforming catalyst according to claim 1, wherein the perovskite-based compound having a thermal expansion coefficient of 65% or more of the thermal expansion coefficient of the porous metal support is represented by the following chemical formula 3: [Chemical formula 3] Sr １－ａ Y ａ TiO ３－δ In the above Chemical Formula 3, a is 0≦a<1, δ is a value that satisfies the balance, and 0≦δ≦1.

3. The methane reforming catalyst according to claim 1, wherein the formula 1 is represented by the following formula 2: [Chemical formula 2] Sr １－ｘ Y ｘ Ti １－ｙ B ｙ O ３－δ In the above Chemical Formula 2, B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh; x is 0≦x<0.3, y is 0≦y<0.2, δ is a value that satisfies the balance, and 0≦δ<1; The x and y satisfy x+y>0.

4. The methane reforming catalyst according to claim 3, wherein B in Formula 2 is Ni or Ru.

5. 2. The methane reforming catalyst according to claim 1, wherein the porous metal support comprises at least one selected from the group consisting of NiCrAlFe, NiCrAl, stainless steel, and inconel.

6. 2. The methane reforming catalyst according to claim 1, wherein the content of the perovskite catalyst particles and the perovskite binder is 3 wt % to 40 wt % based on the total weight of the methane reforming catalyst.

7. 2. The methane reforming catalyst according to claim 1, wherein the concentration of the perovskite compound binder represented by Chemical Formula 1 is 0.05M to 1M.

8. The methane reforming catalyst is suitable for steam reforming, carbon dioxide reforming, and ２ 2. The methane reforming catalyst according to claim 1, 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. a step of first coating the porous metal support with a first slurry containing a perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the porous metal support; and After the first coating step, a second coating step is performed with a second slurry containing perovskite-based catalyst particles and a perovskite-based binder; A method for producing a catalyst for methane reforming, comprising: The perovskite-based catalyst particles and the perovskite-based binder each independently contain a compound represented by the following Chemical Formula 1: [Chemical formula 1] Sr １－ｘ A ｘ Three １－ｙ B ｙ Oh ３－δ In the above Chemical Formula 1, A is Y, La or Ba; B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh; x is 0≦x<1, y is 0≦y<0.5, δ is a value that satisfies the balance, and 0≦δ<1; The x and y satisfy x+y>0.

10. 10. The method for preparing a methane reforming catalyst according to claim 9, wherein the perovskite-based compound having a thermal expansion coefficient of 65% or more relative to the thermal expansion coefficient of the porous metal support is represented by the following Chemical Formula 3: [Chemical formula 3] Sr １－ａ Y ａ TiO ３－δ In the above Chemical Formula 3, a is 0≦a<1, δ is a value that satisfies the balance, and 0≦δ≦1.

11. The method for producing a methane reforming catalyst according to claim 9, wherein the chemical formula 1 is represented by the following chemical formula 2: [Chemical formula 2] Sr １－ｘ Y ｘ Ti １－ｙ B ｙ O ３－δ In the above Chemical Formula 2, B is Ni, Co, Fe, Mn, Cr, Mo, Ru or Rh; x is 0≦x<0.3, y is 0≦y<0.2, δ is a value that satisfies the balance, and 0≦δ<1; The x and y satisfy x+y>0.

12. The method for preparing a methane reforming catalyst according to claim 11, wherein B in Formula 2 is Ni or Ru.

13. 10. The method for preparing a methane reforming catalyst according to claim 9, wherein the porous metal support comprises at least one selected from the group consisting of NiCrAlFe, NiCrAl, stainless steel, and inconel.

14. 10. The method for preparing a methane reforming catalyst according to claim 9, wherein the content of the perovskite catalyst particles and the perovskite binder is 3 wt % to 30 wt % based on the total weight of the methane reforming catalyst.

15. 10. The method for preparing a methane reforming catalyst according to claim 9, wherein the concentration of the perovskite compound binder represented by Chemical Formula 1 is 0.05M to 1M.

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