Catalyst and method for measuring oxygen vacancy of catalyst

Abstract

The present invention relates to a catalyst and a method for measuring oxygen vacancy of the catalyst.

Description

Method for measuring catalyst and oxygen vacancy of catalyst

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0123515 dated September 10, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] The present invention relates to a catalyst and a method for measuring the oxygen vacancy of the catalyst.

[0004] Much research on carbon dioxide conversion technology is underway as part of greenhouse gas reduction activities caused by global warming.

[0005] Carbon dioxide reforming, one of the carbon dioxide conversion technologies, is a technology that produces synthesis gas composed of hydrogen and carbon monoxide by reacting methane with carbon dioxide.

[0006] Syngas is a material with high development value as a raw material for various downstream processes. As a method to industrially obtain synthesis gas (H2 / CO), natural gas reforming reactions can be broadly classified into steam reforming, CO2 reforming, catalytic partial oxidation, autothermal reforming, and tri-reforming, as shown in reaction equations 1 to 5 below.

[0007] [Reaction Equation 1]

[0008] CH4+ H2O → 3H2+ CO ΔH = 226 kJ / mol

[0009] [Reaction Equation 2]

[0010] CH4+ CO2→ 2H2+ 2CO ΔH = 261 kJ / mol

[0011] [Reaction Equation 3]

[0012] CH4+ 0.5O2→ 2H2+ CO ΔH = -44 kJ / mol

[0013] [Reaction Equation 4]

[0014] autothermal reforming: Equation 1 + Equation 3

[0015] [Reaction Equation 5]

[0016] tri-reforming: Equation 1 + Equation 2 + Equation 3

[0017] Meanwhile, various catalysts can be used in the above-mentioned reforming process to enhance reforming activity. Among these, using precious metal catalysts in the reforming process offers the advantage of higher reaction efficiency due to relatively less carbon deposition compared to nickel-based catalysts; however, there is a problem of reduced economic feasibility due to the high cost of precious metal catalysts.

[0018] Accordingly, catalysts using relatively inexpensive nickel and perovskite-based catalyst particles are mainly used in the reforming process, but in such cases, additional control of oxygen vacancies on the catalyst surface is required to activate oxygen mobility within the catalyst in order to reduce carbon deposition.

[0019] Therefore, in this technical field, there is a need to develop catalyst surface control technology that is resistant to carbon deposition and can be effectively applied to the methane reforming process.

[0020] The present invention aims to provide a catalyst that is resistant to carbon deposition and can be effectively applied to a methane reforming process, and to provide a method for measuring the oxygen vacancy of the catalyst related to carbon deposition.

[0021] The present invention provides a catalyst comprising perovskite-based catalyst particles including an A site, a B site, and an O site, wherein the perovskite-based catalyst particles have an oxygen vacancy degree of 4 at% or more as measured according to Method 1 below.

[0022] [Method 1]

[0023] An XPS spectrum is obtained for the surface of a perovskite-based catalyst particle comprising A site, B site, and O site; perovskite sites and non-lattice sites are distinguished from the XPS spectrum; the difference between the total content by bond (unit: at%) in the region corresponding to the entire perovskite site and the total content by bond (unit: at%) in the region corresponding to ABO3 in the perovskite site is defined as the oxygen vacancy; and within the perovskite site, the A site contains a Sr lattice and Y 3+ Assign , and for the above B site, Ti 4+ , Ni 3+ and Cr 3+ Assign , and assign O grids to the above O sites.

[0024] The above perovskite-based catalyst particles may include one or more of Sr, Y, Ti, Ni, and Cr.

[0025] The present invention provides a catalyst in which the Ti content measured by the XPS spectrum of the surface of the perovskite-based catalyst particles is 10 at% to 20 at%.

[0026] The present invention provides a catalyst in which the catalyst is a catalyst for methane reforming.

[0027] In the present invention, the non-lattice site contains Sr non-lattice, Ni, Ni 2+ , Cr 6+ , CO xProvides a catalyst that assigns CC bonds, OO, and OH bonds.

[0028] The present invention provides a catalyst in which the surface of the perovskite-based catalyst particle refers to a region with a depth of 0 nm or more and 10 nm or less in the central direction from the interface of the perovskite-based catalyst particle in contact with the atmosphere.

[0029] The present invention provides a catalyst in which the perovskite-based catalyst particles are supported on a carrier.

[0030] In addition, the present invention provides a catalyst in which the carrier is one or more selected from the group consisting of a porous metal support, alumina, and silica.

[0031] The present invention comprises the steps of: obtaining an XPS spectrum for the surface of a perovskite-based catalyst particle comprising an A site, a B site, and an O site; distinguishing perovskite sites and non-lattice sites in the XPS spectrum; and, within the perovskite sites in the XPS spectrum, the A site is a Sr lattice and Y 3+ Assign , and for the above B site, Ti 4+ , Ni 3+ and Cr 3+ A method for measuring the oxygen vacancy degree of a catalyst is provided, comprising the steps of: assigning a lattice to the O site and assigning an O lattice to the O site; and calculating the difference between the total content per bond (unit: at%) of the region corresponding to the whole of the perovskite site and the total content per bond (unit: at%) of the region corresponding to ABO3 in the perovskite site.

[0032] The present invention provides a method for measuring the oxygen vacancy of a catalyst, wherein the step of determining the difference between the total content by bond (unit: at%) of the region corresponding to the whole of the perovskite site and the total content by bond (unit: at%) of the region corresponding to ABO3 of the perovskite site is calculated by the following Equation 1:

[0033] [Equation 1]

[0034] Oxygen vacancy (at%) = {(A1 - A2) + (B1 - B2)}

[0035] In the above Equation 1,

[0036] A1 is the Sr lattice and Y at the A site of a perovskite catalyst with oxygen vacancies. 3+ A is the bonding content (at%), A2 is the content (at%) of element A in a perovskite catalyst without oxygen vacancies, and B1 is Ti at site B of a perovskite catalyst with oxygen vacancies. 4+ , Ni 3+ and Cr 3+ is the bonding content (at%), and B2 is the content (at%) of element B of the oxygen-free perovskite catalyst.

[0037] The present invention provides a method for measuring the oxygen vacancy of a catalyst, wherein the step of obtaining an XPS spectrum for the surface of a perovskite-based catalyst particle comprising the A site, B site, and O site comprises: deriving an XPS spectrum for the surface of the perovskite-based catalyst particle by X-ray Photoelectron Spectroscopy (XPS) under conditions of a vacuum atmosphere, a measurement range of 20 eV to 40 eV, and a pass energy of 50 eV; and correcting the peaks of the XPS spectrum.

[0038] The present invention provides a method for measuring the oxygen vacancy of a catalyst, wherein the step of correcting the peak of the XPS spectrum involves fixing the CC binding energy for graphite in the carbon 1s spectrum (C 1s spectrum) to a reference energy of a certain magnitude, and correcting the binding energy for the main peaks of other elements based on the energy of the certain magnitude.

[0039] The catalyst according to the present invention can exhibit good activity even at high space velocities during methane reforming reactions and enables stable operation for a long time without carbon deposition or sintering phenomena.

[0040] The method for measuring the oxygen vacancy degree of a catalyst according to the present invention enables efficient measurement of the oxygen vacancy degree, which has a significant impact on carbon deposition.

[0041] Figure 1 is a figure to show the meaning of oxygen vacancies in the ABO3-type crystal structure of perovskite catalysts.

[0042] Figures 2 to 8 are figures of XPS spectra of an example.

[0043] The present invention is described in detail below so that those skilled in the art can easily implement it. However, the present invention may be embodied in various different forms and is not limited to the configurations described herein.

[0044] Unless otherwise defined in this specification, all technical and scientific terms are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular form includes the plural form unless the context clearly indicates otherwise.

[0045] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Specifically, in this specification, terms such as "comprising," "having," or "having" are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0046] In one embodiment of the present specification, the content per bond can be measured through a background setting using the Shirley method, an element-specific sensitivity factor, a Lorentzian / Gaussian (L / G) function, and a fitting process using FWHM (Full Width Half Maximum).

[0047] In this specification, 'a to b' means a or more and b or less.

[0048] In this specification, 'a, b, c or d' means a, or b, or c, or d.

[0049] In this specification, element symbols are described based on the periodic table.

[0050] In this specification, 'at%' means atomic percent.

[0051] In this specification, 'Oxygen Vacancy Degree' refers to the difference between the bond-specific content (unit: at%) of the region corresponding to the entire perovskite site and the bond-specific content (unit: at%) of the region corresponding to ABO3 in the perovskite site.

[0052] According to one embodiment of the present invention, a catalyst comprising perovskite-based catalyst particles having an A site, a B site, and an O site is characterized in that the oxygen vacancy of the catalyst particles is 4 at% or more.

[0053] By satisfying the above characteristics, the catalyst according to the present invention can exhibit good activity even at high space velocities during a methane reforming reaction and can operate stably for a long time without carbon deposition or sintering phenomena.

[0054] The oxygen vacancy degree of the catalyst particles is determined by Method 1 above, and since Method 1 is related to the method for measuring the oxygen vacancy degree of the catalyst particles of the present invention, I would like to describe the catalyst of the present invention after providing a detailed explanation of the method for measuring the oxygen vacancy degree of the catalyst particles of the invention.

[0055] Method for Measuring Oxygen Vacancy Degree of Catalysts

[0056] One embodiment of the present invention comprises the steps of: obtaining an XPS spectrum for the surface of a perovskite-based catalyst particle comprising an A site, a B site, and an O site; distinguishing perovskite sites and non-lattice sites in the XPS spectrum; and, within the perovskite sites in the XPS spectrum, the A site is a Sr lattice and Y 3+ Assign , and for the above B site, Ti 4+ , Ni 3+ and Cr 3+The present invention provides a method for measuring the oxygen vacancy degree of a catalyst, comprising the steps of: assigning a perovskite site and assigning an O grid to the perovskite site; and calculating the difference between the bond content (unit: at%) of the region corresponding to the whole perovskite site and the bond content (unit: at%) of the region corresponding to ABO3 in the perovskite site. The method for measuring the oxygen vacancy degree of the catalyst corresponds to Method 1. Accordingly, the description of Method 1 may also be applied to the method for measuring the oxygen vacancy degree of the catalyst of the present invention.

[0057] That is, the method for measuring the oxygen vacancy of a catalyst according to the present invention enables relative comparative analysis of oxygen vacancies even in other inorganic materials where it is difficult to directly fit the O vacancy peak.

[0058] Specifically, in addition to perovskite inorganic materials for metal modification, which is one of the uses of the catalyst of the present invention, CO x Relative comparative analysis of oxygen vacancies is possible in other inorganic materials where it is difficult to directly fit the O vacancy peak due to high (CO, C=O, OC=O, CO3 bond) content. In addition, relative comparison of TiO2 termination on the outermost surface of the catalyst is also possible.

[0059] As a result, the performance of catalysts can also be predicted for various catalysts.

[0060] In this specification, the oxygen vacancy degree is measured for the surface region (surface ~ approximately 10 nm depth) of the perovskite catalyst through X-ray photoelectron spectroscopy (XPS) analysis and may be calculated by the following Equation 1:

[0061] [Equation 1]

[0062] Oxygen vacancy (at%) = {(A1 - A2) + (B1 - B2)}

[0063] That is, the step of calculating the difference between the total content by bond (unit: at%) of the region corresponding to the whole of the perovskite site and the total content by bond (unit: at%) of the region corresponding to ABO3 of the perovskite site may be calculated using Equation 1 above.

[0064] In Equation 1 above, A1 is the Sr lattice at the A site of the perovskite catalyst having oxygen vacancies and Y 3+ A1 is the bonding content (at%), and A2 is the content (at%) of element A in the oxygen-vacancy-free perovskite catalyst. In the case of the oxygen-vacancy-free perovskite catalyst, the molar ratio of A, B, and O satisfies 1:1:3. Therefore, the content of element A in the oxygen-vacancy-free perovskite catalyst is considered to be substantially the same as the value obtained by dividing the measured content (at%) of the O lattice for the oxygen-vacancy-containing perovskite catalyst by 3. Therefore, "(A1 - A2)" is {Sr lattice bonding content (at%) + Y 3+ It can be {bonding content (at%) - O lattice content (at%) / 3}.

[0065] In addition, in Equation 1 above, B1 is Ti at the B site of the perovskite catalyst having an oxygen vacancy. 4+ , Ni 3+ and Cr 3+ It is the bonding content (at%). B2 is the content (at%) of element B in the oxygen-vacancy-free perovskite catalyst, and is considered to be substantially the same as the value obtained by dividing the content (at%) of the O lattice measured for the oxygen-vacancy-containing perovskite catalyst by 3. Therefore, the above "(B1 - B2)" is {Ti 4+ Binding content (at%) + Ni 3+ Binding content (at%) + Cr 3+It can be {bonding content (at%) - O lattice content (at%) / 3}.

[0066] In the present invention, the total content (unit: at%) of the perovskite-based catalyst having oxygen vacancies is the Sr lattice and Y at site A. 3+ Binding content (at%), Ti at site B 4+ , Ni 3+ and Cr 3+ The binding content (at%) and the oxygen lattice binding content (at%) at the O site can be measured according to the XPS analysis method below:

[0067] 10 to 100 mg of a perovskite catalyst in powder form to be analyzed is prepared, and X-ray photoelectron spectroscopy (XPS) is performed on a measurement area of ​​400 μm × 800 μm with a measurement range of 20 eV to 40 eV and a pass energy of 50 eV to obtain an XPS spectrum. For the spectrum, the binding energy of the carbon 1s peak (C 1s peak) is corrected to 284.8 eV, and the remaining measured elements are also corrected to the same peak shift value as C 1s.

[0068] When performing peak fitting to analyze the elemental bonding content from the XPS spectrum after correction, the baseline is set to the Shirley method, the Lorentzian / Gaussian (L / G) water ratio is set to 70 / 30 or 80 / 20, and the FWHM (Full Width Half Maximum) fit parameter is set to 0.5:3.5.

[0069] Y in the Y 3d and Ti 2p spectra 3+ and Ti 4+ Since only the peak is observed, separate fitting may not be performed, and the Y content is Y3+ It is the content, and the Ti content is Ti 4+ It is considered to be the content.

[0070] The Ni 2p spectrum is Ni 3+ , Ni 2+ and Ni 0 Peak fitting was performed using Satellites A, B, and C (sat_A, sat_B, sat_C), and the Ni content is Ni 3+ , Ni 2+ and Ni 0 It is the total content of, and using the following formula A, Ni 3+ , Ni 2+ and Ni 0 Calculate the content of each.

[0071] [Essence A]

[0072] [Ni 3+ or Ni 2+ or Ni 0 peak area / (Ni 3+ + Ni 2+ + Ni 0 peak area) * Ni content]

[0073] The Cr 2p spectrum is Cr 6+ , Cr 3+ Perform low peak fitting, and the Cr content is Cr 6+ and Cr 3+ It is the total content of, and Cr using the following formula B. 6+ and Cr 3+ Calculate the content for each.

[0074] [Equation B]

[0075] [Cr 6+ or Cr 3+ peak area / (Cr 6+ + Cr 3+ peak area) * Cr content]

[0076] The C 1s spectrum is the CO of C 1s x Content and CO of O 1s xTo ensure consistency in content, 5 peaks in C 1s (CC, CO x : CO, C=O, OC=O, CO3) First, perform fitting, and then adjust CO according to the C:O ratio (1:1 = CO & C=O, 1:2 = OC=O, 1:3 = CO3) in O 1s. x Fit the peak. CO according to the C:O ratio (1:1 = CO & C=O, 1:2 = OC=O, 1:3 = CO3). x The equation for fitting the peak is given by Equation C below.

[0077] [Equation C]

[0078] CO x = 1*[CO + C=O]+2*[OC=O]+3*[CO3]

[0079] The O 1s spectrum satisfies the chemical formula of the ABO3 perovskite structure (A: Sr lattice + Y, O: O lattice) and, considering the presence of oxygen vacancies, fits the Sr lattice of Sr 3d, the O lattice of O 1s, and the O-OH, OO peaks.

[0080] The Sr 3d spectrum is formed by fitting the Sr non-lattice peak of Sr 3d such that the Sr non-lattice content of Sr 3d satisfies the following Equation D. In this case, the Sr non-lattice content refers to the total content of Sr-CO3, Sr-O, and Sr-OH bonds.

[0081] [Essence D]

[0082] Sr non-lattice content ≥ C 1s CO3 content

[0083] Next, perovskites and non-lattice byproducts can be distinguished from the fitted elemental bonds. As mentioned above, in perovskites, the A site is the Sr lattice and Y 3+Assign , and for site B, Ti 4+ , Ni 3+ and Cr 3+ ... is assigned, and an O lattice is assigned to the O site. Non-lattices are the remaining bonds excluding perovskite-related bonds; since bonds other than the perovskite lattice may be formed on the catalyst surface during the preparation of perovskite catalyst particles, porous metal support catalysts, or carrier catalysts in which perovskite catalyst particles are coated on an alumina or silica support, the non-lattice includes Sr non-lattice, Ni metal, and Ni 2+ , Cr 6+ , CO x It may include one or more bonds among CC bonds, OO bonds and OH bonds.

[0084] As an example, the types of elemental bonds fitted from the XPS spectrum of the perovskite-based catalyst according to the present invention may be those shown in Table 1 below. However, the elemental bonds of the perovskite catalyst of the present invention are not limited to those shown in Table 1, and in particular, at least some of the non-lattice bonds shown in Table 1 may not be included, or other types of non-lattice bonds not shown in Table 1 may be included.

[0085]

[0086] In the same manner as above, the Sr lattice and Y at site A 3+ Binding content (at%), Ti at site B 4+ , Ni 3+ and Cr 3+ The binding content (at%) and the oxygen lattice binding content (at%) at the O site can be measured, and the oxygen vacancy can be calculated by substituting these values ​​into Equation 1 above.

[0087] In addition, in the case of the method for measuring the oxygen vacancy of the catalyst of the present invention, in addition to the metal-modifying perovskite inorganic material, COx Relative comparative analysis of oxygen vacancies is possible even in other inorganic materials where it is difficult to directly fit the O vacancy peak due to high (CO, C=O, OC=O, CO3 bond) content. That is, CO x Relative comparative analysis of oxygen vacancies is possible even in inorganic materials where the binding peak area encompasses the entire O vacancy peak area. In addition, relative comparison of TiO2 termination on the outermost surface of the catalyst is also possible.

[0088] Through this, it is also possible to predict the performance of the catalyst.

[0089] Therefore, the method for measuring the oxygen vacancy of the above catalyst requires a process of distinguishing perovskite sites and non-lattice sites in the XPS spectrum.

[0090] In the method for measuring the oxygen vacancy of the above catalyst, the bond-specific content (unit: at%) of the region corresponding to the entire perovskite site may be calculated by the following Equation 2:

[0091] [Equation 2]

[0092] A1 + B1 + O1

[0093] In Equation 2 above, A1 is the Sr lattice and Y 3+ The content of (unit: at%), and B1 is Ti 4+ , Ni 3+ and Cr 3+ The content of (unit: at%) is O, and O1 is the O lattice content (unit: at%).

[0094] In the method for measuring the oxygen vacancy of the above catalyst, the content per bond (unit: at%) of the region corresponding to ABO3 at the perovskite site may be calculated by the following Equation 3:

[0095] [Equation 3]

[0096] A2 + B2 + O1

[0097] In the above Equation 3, A2 and B2 are each one-third of the O lattice content (unit: at%), and O1 is the O lattice content (unit: at%).

[0098] That is, the above Equation 1 may mean the difference between the above Equations 2 and 3.

[0099] The description of the method for measuring the oxygen vacancy of a catalyst according to the present invention can also be applied to the catalyst according to the present invention. In particular, it can be applied to Method 1. The reverse is also true.

[0100] Catalyst

[0101] According to one embodiment of the present invention, a catalyst comprising perovskite-based catalyst particles having an A site, a B site, and an O site is characterized in that the oxygen vacancy of the catalyst particles is 4 at% or more.

[0102] The above perovskite-based catalyst particles may include one or more of Sr, Y, Ti, Ni, and Cr, preferably two or more of Sr, Y, Ti, Ni, and Cr; more specifically, they may include Sr, Ti, and Ni, and optionally include one or more of Y and Cr. Additionally, since they include O sites, the perovskite-based catalyst particles include O.

[0103] That is, the above perovskite-based catalyst particles may include (1) Sr, Ti, Ni, and O, (2) Sr, Ti, Ni, Y, and O, or (3) Sr, Ti, Ni, Y, Cr, and O, but are not limited thereto.

[0104] By satisfying the above characteristics, the catalyst according to the present invention can exhibit good activity even at high space velocities during a methane reforming reaction and can operate stably for a long time without carbon deposition or sintering phenomena.

[0105] In one embodiment of the present invention, the oxygen vacancy may be 4 at% or more, 4.5 at%, 5 at% or more, or 6 at% or more, 9 at% or less, or 8 at% or less, and may be 4 at% to 9 at%, 4 at% to 8 at%, 4.5 at% to 9 at%, 4.5 at% to 8 at%, 5 at% to 9 at%, 5 at% to 8 at%, 6 at% to 9 at%, or 6 at% to 8 at%.

[0106] If the oxygen vacancy rate is less than 4 at%, the oxygen mobility within the catalyst is insufficient, which may result in the inability to reduce carbon deposition on the catalyst during the methane reforming reaction and a problem where a large amount remains on the catalyst surface. Additionally, if the oxygen vacancy rate is 4 at% or higher, carbon deposition can be prevented because oxygen mobility within the catalyst is smooth, and if it exceeds 9 at%, carbon deposition can be prevented, but a problem may occur where the perovskite structure cannot be maintained due to the large amount of empty oxygen.

[0107] In this specification, a perovskite-based catalyst particle comprising an A site, a B site, and an O site refers to a perovskite-based catalyst having an ABO3 form.

[0108] A representative perovskite catalyst with an ABO3 structure is SrTiO3, and it is widely known in the literature that Sr is located at the A site, Ti at the B site, and O at the O site. In addition, and, in the field Y 3+ is Sr, Ni 3+ and Cr3+ It is also known that it can substitute Ti. It is also known in the literature. Therefore, at the A site present in the above perovskite catalyst, a Sr lattice and Y 3+ Assign , and for the above B site, Ti 4+ , Ni 3+ and Cr 3+ Assign , and an O grid can be assigned to the above O site.

[0109] At this time, the perovskite catalyst may include both a form in which there are empty spaces where oxygen atoms or ions have been removed from the crystal structure in the ABO3 form, and a form in which oxygen atoms or ions have not been removed from the crystal structure. At this time, the empty spaces where oxygen atoms or ions have been removed from the crystal structure, as shown in Fig. 1, are called oxygen vacancies, and the perovskite structure must be maintained even if oxygen atoms or ions are removed.

[0110] In addition, through XPS spectra, the Sr lattice assigned to the A site and Y in the ABO3-type perovskite catalyst 3+ Content by binding, Ti assigned to site B 4+ , Ni 3+ and Cr 3+ The content of each bond and the content of each bond of the O grid assigned to the O site can be quantitatively measured.

[0111] In this specification, the region corresponding to the entire perovskite site refers to a region that includes all crystal structures of the perovskite-based catalyst, without distinguishing between a form in which oxygen atoms or ions are missing and a form in which oxygen atoms or ions are not missing; and the region corresponding to ABO3 in the perovskite site refers to a region that includes only the form in which oxygen atoms or ions are not missing.

[0112] This is because, in the absence of oxygen vacancies, perovskite catalysts must have an ABO3 form. That is, in the absence of oxygen vacancies, the content ratio of A, B, and O corresponds to 1:1:3, so one-third of the bond content of the O lattice assigned to the O site becomes the bond content of atoms or ions assigned to the A site and the bond content of atoms or ions assigned to the B site in the absence of oxygen vacancies.

[0113] In other words, the difference between the total content by bond (unit: at%) of the region corresponding to the entire perovskite site and the total content by bond (unit: at%) of the region corresponding to ABO3 in the perovskite site signifies the total content by bond of only the structure in which oxygen vacancies exist, and in this specification, this is defined as the Oxygen Vacancy.

[0114] The inventors of the present invention have confirmed that when the oxygen vacancy rate measured by Method 1 satisfies the numerical range described above, the catalyst can exhibit good activity even at high space velocities during the methane reforming reaction and can operate stably for a long time without carbon deposition or sintering phenomena.

[0115] Therefore, as in Method 1 above, a process of distinguishing perovskite sites and non-lattice sites in the XPS spectrum is required.

[0116] The Cr content measured by the XPS spectrum of the surface of the above-mentioned perovskite-based catalyst particles may be 0 at% to 1.5 at%, 0.1 at% to 1.5 at%, 0.2 at% to 1.3 at%, or 0.5 at% to 1.3 at%. The above-mentioned Cr content is Cr 3+ Content and Cr 6+It refers to the sum of the contents, and if the Cr content satisfies the above range, more oxygen vacancies can be formed on the surface while maintaining the perovskite structure, thereby more effectively preventing deposition caused by coking.

[0117] In one embodiment of the present invention, the Ti content measured by the XPS spectrum of the surface of the perovskite-based catalyst particles may be 10 at% to 20 at%, 10 at% to 18 at%, or 13 at% to 18 at%.

[0118] Among the components of the surface of perovskite catalyst particles, the ratio of TiO2-termination at the outermost edge of the catalyst can affect the oxygen vacancy rate. As a result, when the Ti content satisfies the above range, more oxygen vacancies can be formed on the surface while maintaining the perovskite structure, and since this makes oxygen mobility within the catalyst more active, deposition caused by coke formation can be prevented more effectively.

[0119] In one embodiment of the present invention, the surface of the perovskite-based catalyst particle may refer to a region with a depth of 0 nm or more and 10 nm or less in the central direction from the interface of the perovskite-based catalyst particle in contact with the atmosphere.

[0120] In one embodiment of the present invention, the component of the catalyst surface may be represented by the following chemical formula 1:

[0121] [Chemical Formula 1]

[0122] SrY a Ti b Ni c Cr d O 4-δ

[0123] In the above chemical formula 1,

[0124] a is 0 ≤ a < 0.15, and

[0125] b is 0 < b < 1.5, and

[0126] c is 0 < c < 0.5, and

[0127] d is 0 ≤ d < 0.15, and e is 0 < δ < 1.

[0128] In this specification, the composition of the catalyst surface was calculated as the ratio of catalyst surface elements (atomic percent ratio) by dividing the elemental content (atomic percent) measured by XPS analysis of the catalyst surface by the measured Sr elemental content.

[0129] Specifically, 10 to 100 mg of a perovskite-based catalyst in powder form to be analyzed is prepared, and X-ray photoelectron spectroscopy (XPS) is performed on a measurement area of ​​400 μm × 800 μm with a measurement range of 20 eV to 40 eV and a pass energy of 50 eV to obtain an XPS spectrum, and the elemental content is measured from the spectrum. Subsequently, the atomic percent of the elemental content is divided by the measured Sr elemental content to calculate the atomic percent ratio of the catalyst surface elements, and the ratio of the elements is expressed by a chemical formula.

[0130] At this time, the catalyst surface refers to a region with a depth of 0 nm or more and 10 nm or less in the central direction from the interface of the perovskite catalyst particles.

[0131] Since the catalyst surface provides active sites where reactants can undergo adsorption, interaction, and chemical modification, reactions primarily occur on the catalyst surface when a catalyst is used. In other words, the elemental molar ratio on the catalyst surface significantly affects catalytic performance, and thus, this ratio is crucial for achieving excellent catalytic performance while minimizing by-products.

[0132] The above perovskite-based catalyst particles can be used as catalysts themselves, but the catalyst may be in a form in which the perovskite-based catalyst particles are supported on a carrier.

[0133] That is, the present invention can provide a carrier; and a catalyst in which the perovskite-based catalyst particles are supported on the carrier.

[0134] In the case of a catalyst using a carrier, in order to apply the above method 1 of the present invention, it may be additionally necessary to apply vibration to each catalyst to separate the catalyst supported on the carrier, and to remove foreign matter using a sieve to separate it into a detached powder-form catalyst (component).

[0135] The above carrier may be one or more selected from the group consisting of porous metal supports, alumina, and silica, and preferably may be a porous metal support.

[0136] The porous metal support may comprise one or more selected from NiFeCrAl, NiCrAl, stainless steel, and Inconel.

[0137] The porous metal support described above is a support having various shapes, and since it has a low heat capacity and excellent heat transfer ability, it can be molded 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%. In addition, the average pore size of the porous metal support may be 150㎛ to 3,000㎛, 400㎛ to 2,000㎛, or 600㎛ to 1,700㎛. The porous metal support may be appropriately manufactured by a person skilled in the art using methods known in the art, taking into account the material, pore size, porosity, etc. of the porous metal support described above.

[0138] In addition, the carrier may be alumina, silica, and alumina-silica. That is, the carrier may be Al2O3, SiO2 x (0 < x ≤ 2) and Al2O3 / SiO x (0 < x ≤ 2) can be.

[0139] A carrier; in the case of a catalyst in which the perovskite-based catalyst particles are supported on the carrier, the content of the perovskite-based catalyst particles may be 3% to 40% by weight, 6% to 35% by weight, or 7% to 30% by weight, based on the total weight of the catalyst. If the content of the perovskite-based catalyst particles is less than 3% by weight based on the total weight of the catalyst, it is undesirable because the reactivity may be reduced due to the relatively small number of active sites on the catalyst surface. In addition, if the content of the catalyst particles exceeds 40% by weight, a relatively large amount of catalyst particles is contained relative to the carrier, making it difficult to maintain the carrier structure and making it difficult for the catalyst particles to bond with the carrier.

[0140] A catalyst according to one embodiment of the present invention can be formed in the form of perovskite nanoparticles by directly coating perovskite-based catalyst particles onto a carrier without a separate binder.

[0141] Accordingly, there is a feature that the active surface area of ​​the catalyst can be increased.

[0142] The catalyst according to the present invention may be a catalyst for methane reforming.

[0143] More specifically, the catalyst according to the present invention may be a catalyst for methane reforming, and said catalyst for methane reforming may be applied to a steam reforming process, a CO2 reforming process, a catalytic partial oxidation process, an autothermal reforming process, a tri-reforming process, or a mixed reforming process, and the methane reforming process is not particularly limited.

[0144] The catalyst according to the present invention may have a coke generation amount calculated by the following Formula 4 of 7 wt% or less, 6.5 wt% or less, 6 wt% or less, 5.5 wt% or less, or 4 wt% or less.

[0145] [Equation 4]

[0146] Cokes content (wt%) = Mass ratio at point A - Mass ratio at point B

[0147] In the above Equation 4, the mass ratio at point A (Weight percent: wt %) refers to the maximum mass ratio around 500°C in the TGA analysis of the catalyst after the metal reforming reaction, point B refers to the temperature at which the reduction in mass ratio due to the thermal decomposition behavior of Coke ends, and the mass ratio at point B is defined as the Y-axis value at the intersection of the straight line in the mass reduction region (A~B) and the straight line in the temperature region having linearity after point B.

[0148] That is, Equation 4 above is a formula for calculating the amount of cokes produced, and the reaction of Equation 4 is carried out in the presence of the catalyst, with a gas composition of CH4:CO2:N2 = 1:1.2:0.96 and a Weight Hour Space Velocity (WHSV) of 30,000 h -1 It refers to a methane dry reforming reaction carried out for 100 hours under conditions of flow rate, reaction temperature of 800 ℃ and reaction pressure of 5 bar.

[0149] That is, as described above, the catalyst according to the present invention is characterized by having a low amount of carbon deposition when used in a methane reforming process.

[0150] The catalyst provided in the present invention can be manufactured by a method comprising the steps of: preparing a solution containing a precursor of perovskite-based catalyst particles; and drying and calcining the solution.

[0151] In addition, when a carrier is used, the catalyst provided in the present invention can be manufactured by a method comprising the steps of: preparing a solution containing a precursor of perovskite-based catalyst particles; coating a carrier with the solution containing the precursor of the perovskite-based catalyst particles; and drying and calcining the carrier.

[0152] Each step is described below. However, the specific manufacturing processes or examples described herein are not intended to limit any particular type of catalyst or method of manufacturing thereof. This specification may include any catalyst formed by any associated manufacturing method known to a person skilled in the art.

[0153] The perovskite-based catalyst particles of the present invention can be manufactured using the citric acid method, the Pechini method, the high-temperature aging method, the polymerization composite method, the freeze-drying method, etc., and preferably, they can be manufactured through the citric acid method. The citric acid method is a method of obtaining a perovskite catalyst by adding citric acid to create an amorphous metal composite in a gel state, and then drying and calcining it.

[0154] The present invention may include the step of preparing a solution containing a precursor of perovskite-based catalyst particles.

[0155] In addition, there are no special limitations on the precursor of the metal, and a combination of ammonium salts, nitrates, carbonates, chlorides, or mixtures thereof of the metal element may be applied.

[0156] More specifically, strontium nitrate (Sr(NO3)3H2O), nickel nitrate (Ni(NO3)2), yttrium nitrate (Y(NO3)2), titanium isopropoxide (Ti(OCH(CH3)2)4), etc. are precursors of metals constituting perovskite-based catalyst particles, and the metal molar ratio of perovskite-based catalyst particles can be controlled by controlling the content thereof.

[0157] The above solution may include citric acid, ethanol, ethylene glycol, distilled water, etc. Through this, an amorphous metal composite in a gel state can be prepared.

[0158] In one embodiment of the present invention, in the step of drying and calcining the solution, the drying may be performed at a temperature of 50 ℃ to 200 ℃ for 1 hour to 48 hours and at a temperature of 60 ℃ to 150 ℃ for 5 hours to 36 hours, but is not limited thereto.

[0159] The precursor solution can be prepared in the form of a sol through the above drying process.

[0160] The above calcination involves heat-treating a solution containing a precursor of perovskite-based catalyst particles. This process may be performed at a temperature of 350°C to 1,100°C for 1 to 10 hours under an air atmosphere, or at a temperature of 500°C to 1,000°C for 1 to 8 hours under an air atmosphere, but is not limited thereto. Perovskite-based catalyst particles can be obtained through the above calcination.

[0161] More specifically, the calcination may be performed at a temperature of 850 ℃ to 1,000 ℃ for 1 to 8 hours, and the heat treatment may be performed one or more times. If the heat treatment is performed two or more times, a process of cooling to room temperature may be included between the heat treatments, and in this specification, the heat treatment time refers to the total sum of the time taken to perform calcination in the temperature range, excluding the time taken to cool to room temperature. In addition, the calcination is performed in an air atmosphere, and the air flow rate may be 8 L / min or more, or 10 L / min or more, but is not limited thereto as long as the catalyst of the present invention can be manufactured.

[0162] In addition, the amount of catalyst per single calcination may be 200g to 550g or 250g to 500g, but is not limited thereto as long as the catalyst of the present invention can be manufactured. The above drying and calcination conditions may be one of the factors affecting the crystal structure and air porosity of the perovskite-based catalyst particles.

[0163] As described above, the catalyst of the present invention may also be used in a form supported on a carrier. In this case, when a solution containing a precursor of perovskite-based catalyst particles is prepared as described above, the method may include a step of coating the solution onto the carrier.

[0164] At this time, the above coating method is not particularly limited, but, for example, dip coating, wash coating, etc. may be used. In the present invention, perovskite-based catalyst particles can be directly coated onto a carrier without a separate binder.

[0165] When the catalyst of the present invention is also used in a form supported on a carrier, the drying and calcination steps are performed after the step of coating the carrier with a solution containing a precursor of the perovskite-based catalyst component, and the specific temperature conditions are as described above.

[0166] In one embodiment of the present invention, the step of measuring the weight of the catalyst supported on the carrier after the drying and calcining step may be further included. Additionally, by measuring the weight of the catalyst supported on the carrier, the step of coating a solution containing a precursor of the perovskite-based catalyst particles on the aforementioned carrier until a desired amount of catalyst is supported on the carrier; and the drying and calcining step may be repeated 1 to 20 times.

[0167] The present invention will be explained in more detail below by way of examples. However, the scope of the present invention is not limited to these examples.

[0168] [Example 1] SrY 0.08 Ti 0.95 Ni 0.19 O 4-δ

[0169] A solution containing precursors for perovskite catalyst particles was prepared via the citric acid method. Strontium nitrate (Sr(NO3)3H2O), nickel nitrate (Ni(NO3)2), and yttrium nitrate (Y(NO3)2) were dissolved in distilled water along with citric acid and ethylene glycol. Subsequently, titanium isopropoxide (Ti(OCH(CH3)2)4) was dissolved in ethanol, and the two solutions were mixed at 70°C to prepare 50 L of precursor solution. Afterward, the solution was stirred for 3 hours, cooled to room temperature, and stored. At this time, the concentration of the solution was 0.1 M.

[0170] Heat treatment was performed at 350 ℃ in an air atmosphere for 1 hour, followed by cooling to room temperature, heat treatment at 700 ℃ in an air atmosphere for 1 hour, and after cooling to room temperature once more, heat treatment at 900 ℃ in an air atmosphere for 1 hour, for a total of 3 heat treatments, so that the catalyst surface component was SrY 0.08 Ti 0.95 Ni 0.19 O 4-δ A catalyst with (0 < δ < 1) was prepared.

[0171] [Example 2] SrY 0.12 Ti 1.08 Ni 0.25 Cr 0.08 O 4-δ

[0172] In the catalyst preparation method of Example 1, except that chromium nitrate (Cr(NO3)39H2O) is added, the catalyst is prepared in the same manner as in Example 1, and the catalyst surface component is SrY 0.12 Ti 1.08 Ni 0.25 Cr 0.08 O 4-δ A catalyst with (0 < δ < 1) was prepared.

[0173] [Example 3] SrY 0.13 Ti 1.20 Ni 0.21 Cr 0.06 O 4-δ

[0174] In the catalyst preparation method of Example 2, a catalyst was prepared in the same manner as in Example 2, except that the 0.1M concentration precursor solution was increased from 50L to 250L, and the catalyst surface component was SrY 0.13 Ti 1.20 Ni 0.21 Cr 0.06 O 4-δ A catalyst with (0 < δ < 1) was prepared.

[0175] [Example 4] SrTi 1.20 Ni 0.07 Cr 0.08 O 4-δ

[0176] Except for excluding yttrium nitrate (Y(NO3)2) from the precursor solution of Example 2, and except for preparing 50 L of a 0.1 M concentration precursor solution in the same manner as the precursor solution of Example 1, a catalyst was prepared in the same manner as Example 1, wherein the catalyst surface component was SrTi 1.20 Ni 0.07 Cr 0.08 O 4-δ A catalyst with (0 < δ < 1) was prepared.

[0177] [Example 5] SrY 0.09 Ti 0.92 Ni 0.25 Cr 0.10 O 4-δ / NiCrAl

[0178] Dip coating was performed so that the precursor solution of Example 2 could be supported on a porous metal support (NiCrAl, average pore size: 1,200 μm), then dried at 150 °C for 24 hours, and heat treated at 900 °C in an air atmosphere for 3 hours.

[0179] This process was repeated several times to finally prepare a catalyst supported on a porous metal support, and the catalyst surface component was SrY 0.09 Ti 0.92 Ni 0.25 Cr 0.10 O 4-δA catalyst of (0 < δ < 1) / NiCrAl was prepared.

[0180] [Comparative Example 1] SrY 0.11 Ti 1.05 Ni 0.11 O 4-δ

[0181] In the catalyst preparation method of Example 1, except that a total of two heat treatments are performed by heat treating at 350°C in an air-deficient atmosphere for 1 hour and 30 minutes and then heat treating at 700°C in an air-deficient atmosphere for 1 hour and 30 minutes, the catalyst surface component is SrY 0.11 Ti 1.05 Ni 0.11 O 4-δ A catalyst with (0 < δ < 1) was prepared.

[0182] [Comparative Example 2] SrY 0.10 Ti 1.10 Ni 0.19 O 4-δ

[0183] In the catalyst preparation method of Example 1, except that heat treatment is performed at 350 °C in an air atmosphere for 1 hour and 30 minutes, then the temperature is raised to 900 °C and heat treatment is performed at 900 °C in an atmosphere for 1 hour and 30 minutes, the catalyst surface component is SrY 0.10 Ti 1.10 Ni 0.19 O 4-δ A catalyst with (0 < δ < 1) was prepared.

[0184] [Comparative Example 3] SrY 0.16 Ti 1.18 Ni 0.18 Cr 0.15 O 4-δ (0 < δ < 1) / NiCrAl

[0185] In the catalyst preparation method of Example 5, except that the precursor solution was increased from 50L to 60L, the catalyst surface component is SrY 0.16 Ti 1.18 Ni0.18 Cr 0.15 O 4-δ A catalyst of (0 < δ < 1) / NiCrAl was prepared.

[0186] In Examples 1 to 5 and Comparative Examples 1 to 3, the catalyst surface components refer to the relative ratio calculated based on the Sr element for the elemental content measured by XPS analysis of the catalyst surface.

[0187] Specifically, 50 mg of a perovskite catalyst in powder form to be analyzed was prepared, and X-ray photoelectron spectroscopy (XPS) was performed on a measurement area of ​​400 μm × 800 μm with a measurement range of 20 eV to 40 eV and a pass energy of 50 eV to obtain an XPS spectrum, and the elemental content was measured from the spectrum. Subsequently, the atomic percent of the elements on the catalyst surface was calculated by dividing the measured atomic percent by the measured Sr elemental content, and the ratio of the elements was expressed by a chemical formula according to the ratio of the elements.

[0188] For example, in Example 1, when the ratio of Sr, Y, Ti, and Ni elements in the XPS spectrum obtained through XPS analysis of the catalyst surface is 1:0.08:0.95:0.19, it can be represented as shown in the following chemical formula A.

[0189] [Chemical Formula A]

[0190] SrY 0.08 Ti 0.95 Ni 0.19 O 4-δ

[0191] [Experimental Example 1] - Measurement of Oxygen Vapority and Ti Content

[0192] Oxygen vacancy and Ti content were measured for the catalysts of Examples 1 to 5 and Comparative Examples 1 to 3 using Method 1. Among these, since the catalysts of Example 5 and Comparative Example 3 have catalyst components supported on a porous metal support, vibration was applied to each of the catalysts of Example 5 and Comparative Example 3 to separate the supported catalyst from the porous metal support, and foreign matter was removed using a sieve to separate the catalyst into a detached powder form.

[0193] Afterwards, 50 mg of the catalyst of Example 1 in powder form was prepared, and X-ray Photoelectron Spectroscopy (XPS) was performed on the 50 mg of the catalyst using an XPS analyzer (model name / manufacturer: Nexsa / Thermoscientific) with a measurement area of ​​400 μm × 800 μm, a measurement range of 20 eV to 40 eV, and a pass energy condition of 50 eV to obtain an XPS spectrum.

[0194] For the above spectrum, the binding energy of the carbon 1s peak (C 1s peak) was corrected to 284.8 eV, and the remaining measured elements were also corrected to the same peak shift value as C 1s.

[0195] Next, the content of Ti, Cr, etc. was measured using the XPS elemental spectra measured above.

[0196] Specifically, in the Y spectrum of Fig. 2, Y content = Y 3+ The content of Y was measured through the content relationship. In addition, from the Ti spectrum in Fig. 3, the Ti content = Ti 4+ The Ti content was measured through the content relationship. In the case of the Y 3d and Ti 2p spectra, Y 3+ and Ti 4+ Since only the peak is observed (Y 3d 5 / 2Binding Energy Range: 157.0–158.0 eV, Ti 2p 3 / 2 Y in the peak binding energy range 3+ , Ti 4+ Judgment), no separate fitting was performed.

[0197] In addition, the Ni 2p spectrum Ni 3+ , Ni 2+ and Ni 0 , peak fitting was performed using Satellites A, B, and C (sat_A, sat_B, sat_C) to derive the Ni 2p spectrum of Fig. 4, and in the Ni 2p spectrum of Fig. 4, Ni content = Ni 3+ Content + Ni 2+ Content + Ni 0 The Ni content was measured through the content relationship and the following formula A.

[0198] [Essence A]

[0199] [Ni 3+ or Ni 2+ or Ni 0 peak area / (Ni 3+ + Ni 2+ + Ni 0 peak area) * Ni content]

[0200] Additionally, the Cr 2p spectrum is Cr 6+ , Cr 3+ The Cr 2p spectrum of Fig. 5 was derived by performing peak fitting, and in the Cr 2p spectrum of Fig. 5, Cr content = Cr 6+ + Cr 3+ Using the content relationship and the following formula B, Cr 6+ and Cr 3+ The content was measured.

[0201] [Equation B]

[0202] [Cr 6+ or Cr 3+ peak area / (Cr 6+ + Cr3+ peak area) * Cr content]

[0203] Next, the C 1s spectrum of C 1s CO x Content and CO of O 1s x To ensure consistency in content, 5 peaks in C 1s (CC, CO x : CO, C=O, OC=O, CO3) First, perform fitting, and then adjust CO according to the C:O ratio (1:1 = CO & C=O, 1:2 = OC=O, 1:3 = CO3) in O 1s. x The C 1s spectrum of Fig. 6 was derived by fitting the peaks, and the content of CO3, CC, and other carbon (C) was measured from the C 1s spectrum of Fig. 6. At this time, CO3 was adjusted according to the C:O ratio (1:1 = CO & C=O, 1:2 = OC=O, 1:3 = CO3). x The peak was fitted using the following equation C.

[0204] [Equation C]

[0205] CO x = 1*[CO + C=O]+2*[OC=O]+3*[CO3]

[0206] In addition, considering the chemical formula of the ABO3 perovskite structure (A: Sr lattice + Y, O: O lattice) and the presence of oxygen vacancies, the O 1s spectrum shown in Fig. 7 was derived by fitting the Sr lattice of Sr 3d, the O lattice of O 1s, and the O-OH and O-OO peaks. In the O 1s spectrum of Fig. 7, the content of the O lattice, O-OH, and O-OO peaks and CO x The O content of (CO, C=O, OC=O, CO3) was measured for each.

[0207] Finally, the Sr 3d spectrum of Fig. 8 was derived by fitting the Sr non-lattice peak of Sr 3d such that the Sr non-lattice content of Sr 3d satisfies Equation D below. In this case, the Sr non-lattice content refers to the total content of Sr-CO3, Sr-O, and Sr-OH bonds. The amounts of Sr lattice and Sr non-lattice were measured, respectively, in the spectrum of Fig. 8.

[0208] [Essence D]

[0209] Sr non-lattice content ≥ C 1s CO3 content

[0210] Next, an elemental XPS spectrum was obtained for the surface of each catalyst, and perovskite sites and non-lattice sites were distinguished from the XPS spectrum.

[0211] Subsequently, within the perovskite site in the above XPS spectrum, the A site is a Sr lattice and Y 3+ Assign , and for the above B site, Ti 4+ , Ni 3+ and Cr 3+ Assigned, and assigned an O grid to the above O site.

[0212] Afterwards, the difference between the content of each bond in the region corresponding to the whole of the perovskite site (unit: at%) and the content of each bond in the region corresponding to ABO3 of the perovskite site (unit: at%) was calculated and the value was listed in Table 2 below.

[0213] The above value corresponds to the oxygen vacancy of the catalyst.

[0214] For the catalysts of Examples 2 to 5 and Comparative Examples 1 to 3 in powder form, the oxygen vacancy of the catalyst was determined using the same method as for the catalyst of Example 1, and the results are listed in Table 2 below.

[0215] Additionally, the measured Ti and Cr content is also listed in Table 2 below.

[0216] [Experimental Example 2] Evaluation of Methane Reforming Reaction

[0217] A fixed-bed reaction system was introduced to carry out the dry reforming reaction of methane. A quartz tube reactor (inner diameter = 1 / 2 inch, length = 50 cm) was used and filled with the catalyst of Example 1 (approx. 2.5 g). First, a reduction process was carried out at 800 °C for 2 hours under 10% H2 / N2 conditions, followed by a catalytic reaction for 100 hours.

[0218] Gas composition: CH4: CO2: N2 = 1 : 1.2 : 0.96

[0219] Flow rate: Weight Hour Space Velocity (WHSV) = 30,000 h -1

[0220] Reaction temperature: 800 ℃

[0221] Reaction pressure: 5 bar

[0222] The composition of the generated gas was analyzed using gas chromatography (GC), and the CH4 conversion rate (XCH4) and CO2 conversion rate (XCO2) were calculated after 100 hours of reaction, respectively, and are shown in Table 2 below.

[0223] Conversion Rate (Xi, %) = [(Fi in - Fi out ) / Fi in ] × 100 (Fi = flow rate of i)

[0224] <GC 분석 조건>

[0225] 1) GC model: Agilent 6890

[0226] 2) Oven temp.: 40℃ / 7min-90℃ / 5min-180℃ / 6min

[0227] 3) Detector: TCD, 250℃

[0228] 4) Sample loop: 0.25 mL

[0229] 5) Valve box Temp.: 150℃

[0230] In addition, after the dry reforming reaction of methane, the content of coke formed on the catalyst surface was measured through TGA analysis.

[0231] <TGA 분석 조건>

[0232] Analysis Equipment: Mettler Toledo TGA2

[0233] Temperature range: 50 ~ 1000 ℃

[0234] Heating rate: 10 ℃ / min

[0235] Purge gas: Air 50 ml / min

[0236] <Cokes 함량을 구하는 식>

[0237] Cokes content (wt%) = Mass ratio at point A - Mass ratio at point B

[0238] In the formula for calculating the above Coke content, the mass ratio at point A (Weight percent: wt %) refers to the maximum mass ratio around 500 ℃ in the TGA analysis of the catalyst after the metal reforming reaction, and

[0239] Point B represents the temperature at which the decrease in mass ratio due to the thermal decomposition behavior of Coke ends, and

[0240] The mass ratio at point B is defined as the Y-axis value at the intersection of the straight line in the mass reduction region (A–B) and the straight line in the temperature region with linearity after point B.

[0241] For the catalysts of Examples 2 to 5 and Comparative Examples 1 to 3, the dry reforming reaction of methane was carried out in the same manner as the catalyst of Example 1, and the results are listed in Table 2 below.

[0242]

[0243] As can be seen from the results in Table 2 above, the catalysts of Examples 1 to 5 satisfying the oxygen vacancy range according to the present invention can exhibit good activity even at high space velocities during the methane reforming reaction compared to the catalysts of Comparative Examples 1 to 3, and it was confirmed that less carbon deposition occurs.

[0244] In other words, it was confirmed that the catalyst according to the present invention exhibits excellent effects, such as good activity even at high space velocities during methane reforming reactions, and stable operation for a long time without sintering phenomena due to minimal carbon deposition.

[0245] Furthermore, this result implies that the method for measuring the oxygen vacancy of a catalyst according to the present invention enables efficient measurement of oxygen vacancy, which has a significant impact on carbon deposition.

Claims

1. A catalyst composed of perovskite-based catalyst particles including A sites, B sites and O sites, The above perovskite-based catalyst particles have an oxygen vacancy degree of 4 at% or more as measured according to Method 1 below, catalyst: [Method 1] An XPS spectrum was obtained for the surface of perovskite catalyst particles containing A sites, B sites, and O sites, and Distinguish perovskite sites and non-lattice sites in the above XPS spectrum, The difference between the total content by bond (unit: at%) in the region corresponding to the entire perovskite site and the total content by bond (unit: at%) in the region corresponding to ABO3 in the perovskite site is defined as the oxygen vacancy rate. Within the above perovskite site At the above A site, there is an Sr lattice and Y 3+ Assign and At the above B site, Ti 4+ , Ni 3+ and Cr 3+ Assign, An O grid is assigned to the above O site.

2. In Paragraph 1, The above perovskite-based catalyst particles comprise one or more of Sr, Y, Ti, Ni, and Cr, catalyst.

3. In Paragraph 1, The Ti content measured by the XPS spectrum of the surface of the above perovskite-based catalyst particles is 10 at% to 20 at%, catalyst.

4. In Paragraph 1, The above catalyst is a catalyst for methane reforming, catalyst.

5. In Paragraph 1, The above non-lattice sites include Sr non-lattice, Ni, Ni 2+ , Cr 6+ , CO x and assigning CC bonds, OO, and OH bonds, catalyst.

6. In Paragraph 1, The surface of the above-mentioned perovskite-based catalyst particle refers to a region with a depth of 0 nm or more and 10 nm or less, extending in the central direction from the interface of the perovskite-based catalyst particle in contact with the atmosphere. catalyst.

7. In Paragraph 1, The above-mentioned perovskite-based catalyst particles are in a form supported on a carrier, catalyst.

8. In Paragraph 6, The above carrier is one or more selected from the group consisting of porous metal supports, alumina, and silica, catalyst.

9. A step of obtaining an XPS spectrum for the surface of a perovskite-based catalyst particle including A site, B site and O site; A step of distinguishing perovskite sites and non-lattice sites in the above XPS spectrum; In the above XPS spectrum, within the perovskite site, the A site is a Sr lattice and Y 3+ Assign , and for the above B site, Ti 4+ , Ni 3+ and Cr 3+ A step of assigning and assigning an O grid to the O site; and A method comprising the step of calculating the difference between the total content by bond (unit: at%) of the region corresponding to the entire perovskite site and the total content by bond (unit: at%) of the region corresponding to ABO3 in the perovskite site. Method for measuring the oxygen vacancy degree of a catalyst.

10. In Paragraph 9, The step of calculating the difference between the total content by bond (unit: at%) of the region corresponding to the whole of the perovskite site and the total content by bond (unit: at%) of the region corresponding to ABO3 in the perovskite site is calculated by the following Equation 1. Method for measuring oxygen vacancy in catalysts: [Equation 1] Oxygen vacancy (at%) = {(A1 - A2) + (B1 - B2)} In the above Equation 1, A1 is the Sr lattice and Y at the A site of a perovskite catalyst with oxygen vacancies. 3+ It is the binding content (at%) of, and A2 is the content (at%) of element A in a perovskite catalyst without oxygen vacancies, and B1 is Ti at the B site of a perovskite catalyst with an oxygen vacancy. 4+ , Ni 3+ and Cr 3+ It is the binding content (at%) of, and B2 is the content (at%) of element B in oxygen-free perovskite catalysts.

11. In Paragraph 9, The above non-lattice sites include Sr non-lattice, Ni, Ni 2+ , Cr 6+ , CO x and assigning CC bonds, OO, and OH bonds, Method for measuring oxygen vacancy of a catalyst.

12. In Paragraph 9, The step of obtaining an XPS spectrum for the surface of the perovskite-based catalyst particles including the above A site, B site, and O site is A step of deriving an XPS spectrum of the surface of the perovskite-based catalyst particles using X-ray Photoelectron Spectroscopy (XPS) under conditions of a vacuum atmosphere, a measurement range of 20 eV to 40 eV, and a pass energy of 50 eV; and The method includes a step of correcting the peak of the XPS spectrum. Method for measuring oxygen vacancy of a catalyst.

13. In Paragraph 12, The step of correcting the peak of the XPS spectrum above Fixing the CC binding energy for graphite in the carbon 1s spectrum to a reference energy of a certain magnitude, and correcting the binding energy for the main peaks of other elements based on said certain magnitude energy, Method for measuring oxygen vacancy of a catalyst.

Images