Gas decomposition catalysts and methods and purifier systems for decomposing nitrous oxide (N2O) gas using them.

Abstract

Gas decomposition catalysts and methods and purifier systems for decomposing nitrous oxide (N₂O) gas using them. The gas decomposition catalyst comprises: a perovskite-based oxide host material represented by Formula 1, wherein distinct B' and B'' elements are each doped into B sites; and one or more B' element protrusions originating from a portion or all of the B' element on the surface of the perovskite-based oxide host material, wherein the one or more B' element protrusions have a shape in which a portion of one particle is fixed within the perovskite-based oxide host material and another portion of the particle protrudes from the surface of the perovskite-based oxide host material. In Formula 1, A, B, B', B'', x, y, and z are as described herein.

Description

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Korean Patent Application No. 10-2024-0202730, filed with the Korean Intellectual Property Office on December 31, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to gas decomposition catalysts and methods for decomposing nitrous oxide gas using said gas decomposition catalysts, as well as purifier (scrubber) systems. Background Technology

[0004] Nitrous oxide (N₂O) has a very high global warming potential, approximately 310 times that of carbon dioxide (CO₂). However, nitrous oxide (N₂O) is chemically stable and is therefore minimally reduced in the troposphere, but is also decomposed in the stratosphere by ultraviolet radiation from the sun or reacts with oxygen in the air to produce nitric oxide (NO) and nitrogen dioxide (NO₂).

[0005] The decomposition of nitrous oxide (N2O) is primarily used to treat vehicle exhaust, semiconductor process gases, and display process gases. In these industries, reduction processes to decrease nitrous oxide (N2O) emissions are essential for achieving carbon neutrality. Extensive research is underway on the decomposition of nitrous oxide (N2O) to reduce emissions.

[0006] Examples of nitrous oxide (N2O) decomposition technologies include thermal decomposition technologies using high-temperature heating and direct decomposition technologies using catalysts. In thermal decomposition technologies using high-temperature heating, it is difficult to control heat and energy due to the high operating (running) temperatures of 1,000°C or higher used for nitrous oxide (N2O) decomposition.

[0007] Therefore, there is a need for gas decomposition catalysts that are thermally and chemically stable in the operating environment for nitrous oxide (N2O) decomposition and have improved nitrous oxide (N2O) decomposition performance, as well as methods and purifier systems for decomposing nitrous oxide gas using such catalysts. Summary of the Invention

[0008] A gas decomposition catalyst is provided that is thermally and chemically stable in the operating environment for nitrous oxide (N2O) decomposition and has improved nitrous oxide (N2O) decomposition performance.

[0009] A method is provided for decomposing nitrous oxide gas using the gas decomposition catalyst.

[0010] A purifier system is provided that decomposes nitrous oxide gas using the gas decomposition catalyst.

[0011] Other aspects will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the embodiments presented in this disclosure.

[0012] According to one aspect of this disclosure, the gas decomposition catalyst comprises: a perovskite-based oxide (perovskite-based oxide) host material represented by Formula 1, wherein distinct B' and B'' elements are each doped into B sites; and one or more B' element protrusions derived from a portion or all of the B' element on the surface of the perovskite-based oxide host material, wherein the one or more B' element protrusions have a shape in which a portion of one particle is fixed inside the perovskite-based oxide host material and another portion of the particle protrudes from the surface of the perovskite-based oxide host material:

[0013] Formula 1

[0014] A(B x B' y B'' z O3

[0015] In Equation 1,

[0016] A can be at least one element of strontium (Sr) or lanthanum (La).

[0017] B can be at least one metal (e.g., a transition metal) having an oxidation state of +3, +4, or +5.

[0018] B' can be the Gibbs free energy of the reduction reaction at 900°C according to the following reaction equation 1. At least one of the elements that is 0 or less.

[0019] B'' can be at least one element of zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), gadolinium (Gd), scandium (Sc), or titanium (Ti).

[0020] x, y, and z can each be a rational number greater than 0 and less than 1, and

[0021] x+y+z=1.

[0022] Reaction 1

[0023]

[0024] In reaction 1,

[0025] x1 and y1 can each be positive rational numbers.

[0026] red is restoration, and

[0027] M can be a metal.

[0028] According to another aspect of this disclosure, a method for decomposing nitrous oxide (N₂O) gas includes decomposing nitrous oxide (N₂O) gas by contacting a gas comprising nitrous oxide, such as a process gas, with a gas decomposition catalyst, wherein the gas decomposition catalyst comprises: a perovskite-based oxide host material represented by Formula 1, wherein distinct B' and B'' elements are each doped into B sites; and one or more B' element protrusions derived from a portion or all of the B' element on the surface of the perovskite-based oxide host material. The one or more B' element protrusions have a shape in which a portion of one particle is fixed within the perovskite-based oxide host material and another portion of the particle protrudes from the surface of the perovskite-based oxide host material.

[0029] Formula 1

[0030] A(B x B' y B'' z O3

[0031] In Equation 1,

[0032] A can be at least one element of strontium (Sr) or lanthanum (La).

[0033] B can be at least one metal (e.g., a transition metal) having an oxidation state of +3, +4, or +5.

[0034] B' can be the Gibbs free energy of the reduction reaction at 900°C according to the following reaction equation 1. At least one of the elements that is 0 or less.

[0035] B'' may be at least one element selected from zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), gadolinium (Gd), scandium (Sc), or titanium (Ti).

[0036] x, y, and z can each be a rational number greater than 0 and less than 1, and

[0037] x+y+z=1:

[0038] Reaction 1

[0039]

[0040] In reaction 1,

[0041] x1 and y1 can each be positive rational numbers.

[0042] red is restoration, and

[0043] M can be a metal.

[0044] According to another aspect of this disclosure, a purifier system for decomposing nitrous oxide (N2O) gas includes: a gas inlet through which process gas flows in; a purifier including a gas decomposition catalyst that decomposes nitrous oxide (N2O) gas from the process gas flowing in from the gas inlet; and a gas outlet through which gas from which nitrous oxide (N2O) gas has been removed flows out of the purifier, wherein the gas decomposition catalyst comprises: a perovskite-based oxide host material represented by Formula 1, wherein distinct B' and B'' elements are each doped into B sites; and one or more B' element protrusions derived from a portion or all of the B' element on the surface of the perovskite-based oxide host material. The one or more B' element protrusions have a shape in which a portion of one particle is fixed inside the perovskite-based oxide host material and another portion of the particle protrudes from the surface of the perovskite-based oxide host material.

[0045] Formula 1

[0046] A(B x B' y B'' z )O3.

[0047] In Equation 1,

[0048] A can be at least one element of strontium (Sr) or lanthanum (La).

[0049] B can be at least one metal (e.g., a transition metal) having an oxidation state of +3, +4, or +5.

[0050] B' can be the Gibbs free energy of the reduction reaction at 900°C according to the following reaction equation 1. At least one of the elements that is 0 or less.

[0051] B'' can be at least one element of zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), gadolinium (Gd), scandium (Sc), or titanium (Ti).

[0052] x, y, and z can each be a rational number greater than 0 and less than 1, and x + y + z = 1:

[0053] Reaction 1

[0054]

[0055] In reaction 1,

[0056] x1 and y1 can each be positive rational numbers.

[0057] red means restoration, and

[0058] M can be a metal. Attached Figure Description

[0059] The above and other aspects, features and advantages of some embodiments will become more apparent from the following description taken in conjunction with the accompanying drawings, wherein:

[0060] Figure 1 This is a schematic cross-sectional view showing a comparison between the shape of B' element particles (B' element protruding particles) that have dissolved (ex-solution) from the interior of the perovskite-based oxide host material to the surface according to an embodiment and the shape of B' particles deposited on the surface of the perovskite-based oxide host material.

[0061] Figure 2 This is a schematic flowchart of a method for preparing a gas decomposition catalyst according to an embodiment;

[0062] Figure 3A The graph shows the intensity (arbitrary units, au) versus diffraction angle (2θ, degrees) of the X-ray diffraction (XRD) analysis results of the crystal structures of the perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4 before reduction.

[0063] Figure 3B The graph shows the intensity (arbitrary units, au) of the XRD analysis results of the crystal structures of the perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4 after reduction, as a function of the diffraction angle (2θ, degrees).

[0064] Figure 4 The results of scanning electron microscopy (SEM) analysis of the surfaces of the perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 (Ti) and Examples 1 to 4 (Zr, Hf, Nb and Ta) after reduction are shown.

[0065] Figure 5 It is used for evaluation Figure 6 and 7 A schematic diagram of a nitrous oxide (N2O) gas decomposition system;

[0066] Figure 6The graph shows the conversion of nitrous oxide (N2O) (mol / s) versus temperature (°C) as a result of the gas decomposition performance of the perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4, respectively.

[0067] Figure 7 The bar graphs showing the conversion of nitrous oxide (N2O) (mol / s) at 800°C are results of the nitrous oxide (N2O) gas decomposition performance of the perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4, respectively.

[0068] Figure 8 This is a schematic diagram of a purifier system for decomposing nitrous oxide (N2O) gas according to an embodiment. Detailed Implementation

[0069] The embodiments will now be described in detail, examples of which are shown in the accompanying drawings, wherein the same reference numerals always denote the same elements. In this respect, the embodiments may take different forms and should not be construed as limited to the description set forth herein. Therefore, the embodiments are described below only by reference to the accompanying drawings to illustrate aspects. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of…” modify the entire list of elements when preceding or following it and do not modify individual elements of the list.

[0070] In the following description, since the inventive concept allows for various modifications and numerous embodiments, specific embodiments will be illustrated in the accompanying drawings and described in detail in the written description. However, this is not intended to limit the inventive concept to a particular mode of practice, and it will be understood that all modifications, equivalents, and alternatives without departing from the spirit and scope of the invention are included in the inventive concept.

[0071] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the inventive concept. Singular expressions are used to encompass plural expressions unless they have a distinct meaning in the context.

[0072] The expressions “at least one” or “one or more” used before a component (component, ingredient) in this specification are intended to supplement the list of all components (components, ingredients) and do not imply supplementation of any individual component (component, ingredient) described herein. Unless otherwise specifically stated, the term “combination” as used herein includes mixtures, alloys, reaction products, etc. It should be understood that, unless otherwise stated herein, the terms “comprising” or “including” do not exclude other elements but further include other elements. As used herein, the terms “first,” “second,” etc., are used to distinguish one component (component, ingredient) from another, without indicating order, quantity, or importance. As used herein, unless otherwise stated or clearly contradicted by the context, it should be interpreted as including both the singular and plural forms. Unless otherwise stated, the term “or” means “and / or”.

[0073] Throughout this specification, terms such as "(one) embodiment," "example embodiment," and "implementation" are included in at least one embodiment, wherein the specific elements described with respect to that embodiment are included in this specification, meaning that these elements may or may not be present in another embodiment. Furthermore, it should be understood that the described elements may be combined in any suitable manner in various embodiments.

[0074] Unless otherwise stated, all percentages, parts, ratios, etc., are by weight. Furthermore, when amounts, concentrations, or other values ​​or parameters are given as a list of desired upper and lower limits, this will be understood as specifically disclosing all ranges formed by any pair of desired upper and lower limits, regardless of whether the ranges are disclosed individually.

[0075] When describing ranges of values ​​herein, unless otherwise stated, the range is intended to include its endpoints, as well as all integers and fractions within that range. The scope of this disclosure is not intended to be limited to the specific values ​​mentioned when defining the range.

[0076] Unless otherwise stated, the unit "parts by weight" refers to the weight ratio between the corresponding components, and the unit "parts by mass" refers to the weight ratio between the corresponding components converted to solids.

[0077] As used herein, “about” includes the stated value and means within an acceptable range of deviations from the specific value, as determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the specific quantity (i.e., limitations of the measurement system). For example, “about” may mean within one or more standard deviations relative to the stated value, or within ±30%, 20%, 10%, 5%, or 3%.

[0078] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Furthermore, it will be further understood that terms, such as those defined in commonly used dictionaries, shall be interpreted as having meaning consistent with their meaning in the context of this disclosure and the relevant field, and shall not be interpreted in an idealized sense unless expressly defined herein. Moreover, the terms shall not be interpreted in an overly formal sense.

[0079] Embodiments are described herein with reference to cross-sectional views as schematic representations of idealized embodiments. Therefore, the appearance of the examples may vary, for example, as a result of manufacturing techniques and / or tolerances. Consequently, the embodiments described herein should not be construed as limited to the specific shapes of the regions shown herein, but will include, for example, deviations in shape due to manufacturing processes. For example, regions illustrated or described as flat may typically have rough and / or non-linear characteristics. Furthermore, illustrated sharp corners may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show the precise shape of the regions and are not intended to limit the scope of the claims.

[0080] In nitrous oxide (N₂O) decomposition technology, direct decomposition technology using catalysts can be used at relatively low temperatures of about 600°C to about 800°C, compared with thermal decomposition technology, and can save energy. Examples of such catalysts may include zeolite catalysts or supported catalysts in which noble metals are impregnated or co-precipitated on an alumina support.

[0081] However, conventional catalysts suffer from the following problems: low dispersibility, and the metal nanoparticles that serve as reactive sites agglomerate and become rough in the operating environment used for nitrous oxide (N2O) decomposition, or the nitrous oxide (N2O) decomposition performance deteriorates due to evaporation.

[0082] Based on this, the inventors of this disclosure will describe in more detail the gas decomposition catalyst, its preparation method, and the method and purifier system for decomposing nitrous oxide gas using the gas decomposition catalyst.

[0083] Gas decomposition catalyst

[0084] A gas splitting catalyst according to one embodiment may include: a perovskite-based oxide host material represented by Formula 1, wherein distinct B' and B'' elements are each doped into B sites; and one or more B' element protrusions on the surface of the perovskite-based oxide host material, some or all of which are derived from the B' element.

[0085] Formula 1

[0086] A(B x B' y B'' z )O3.

[0087] The perovskite-based oxide host material represented by Equation 1 can have a structure in which different B' and B'' elements are doped into the B sites of a perovskite oxide of general formula ABO3. Even when various amounts of B' and B'' elements are doped into the B sites, the perovskite-based oxide host material represented by Equation 1 can form an elastically stable host phase.

[0088] In Formula 1, A can be at least one element of strontium (Sr) or lanthanum (La), and for example, A can be strontium (Sr).

[0089] In Formula 1, B may be at least one metal (e.g., a transition metal) having an oxidation number of +3, +4 or +5, and may include, for example, elements such as titanium (Ti), aluminum (Al), cobalt (Co), iron (Fe) or nickel (Ni).

[0090] In Equation 1, B' can be the Gibbs free energy of the reduction reaction according to Equation 1 below at a temperature of 900 °C. At least one of the elements that is 0 or less.

[0091] Reaction 1

[0092]

[0093] In reaction 1,

[0094] x1 and y1 can each be positive rational numbers.

[0095] red is for restoration, and

[0096] M can be a metal. For example, M can be at least one metal (e.g., a transition metal) having an oxidation state of +3, +4, or +5.

[0097] According to reaction formula 1, B' can refer to an element that undergoes a spontaneous reduction reaction at a high temperature of 900℃.

[0098] B' can be formed on the surface of a perovskite-based oxide host material as one or more protruding particles derived from a portion or all of the B' element. Specifically, the B' element protruding particles may have a shape in which a portion of one particle is fixed inside the perovskite-based oxide host material and another portion of said particle protrudes from the surface of the perovskite-based oxide host material. More specifically, the B' element protruding particles may have a shape in which a portion of one particle is embedded inside the perovskite-based oxide host material and another portion of said particle remains on the surface of the perovskite-based oxide host material.

[0099] B' element protruding particles can have spherical, ellipsoidal, toroidal, or cylindrical shapes. For example, B' element protruding particles can have a spherical or near-spherical shape.

[0100] Figure 1 This is a schematic cross-sectional view showing a comparison between the shape of B' element particles (B' element protruding particles) dissolved from the interior of the perovskite-based oxide host material to the surface of the perovskite-based oxide host material according to an embodiment and the shape of B' particles deposited on the surface of the perovskite-based oxide host material.

[0101] refer to Figure 1 The B' element protruding particles maintain a spherical shape, wherein a portion of the B' element protruding particle is embedded in the perovskite-based oxide host material, and another portion of the B' element protruding particle protrudes from the surface of the perovskite-based oxide host material. B' element protruding particles with this shape retain their number and distribution even after heat treatment at high temperatures of 800°C or higher.

[0102] In contrast, B' particles deposited on the surface of a perovskite-based oxide host material can have a shape in which a portion of it can adhere to the surface of the perovskite-based oxide. However, due to insufficient interaction with the perovskite-based oxide host material, the particles can become rough on the perovskite-based oxide host material during the growth reaction, which can degrade the performance of the gas decomposition catalyst.

[0103] Therefore, the gas decomposition catalyst including B' element protruding particles according to the embodiments can be used in industrial fields involving catalytic reactions at high temperatures of 800°C or higher, for example, in electrochemical applications (hydrogen fuel cells (SOFC), proton ceramic fuel cells, alkaline water electrolysis, etc.).

[0104] B' element-rich particles can be nanoparticles.

[0105] For example, the B' element in the protruding particles may include at least one element such as cobalt (Co), nickel (Ni), or iron (Fe). For example, the Gibbs free energy of the reduction reaction of CoO, NiO, and Fe2O3 at 900°C according to reaction formula 1. They are -33.48 kJ mol. -1 -51.58 kJ mol -1 , and -15.38 kJ mol -1 .

[0106] For example, the B' element protruding particles can have a size of about 5 nanometers (nm) to about 20 nm. The standard deviation of the size of the B' element protruding particles can be ±2 nm. The B' element protruding particles can have the size of nanoparticles and a uniform distribution.

[0107] As used herein, the B' element highlights the particle's "size" as defined based on the particle's cross-sectional shape. For example, when the particle's cross-section has a "circular shape," such as a sphere, ring, or cylinder, "size" may refer to the "diameter." For example, when the particle's cross-section has an "ellipsoidal shape," "size" may refer to the "length of the major axis."

[0108] For example, the B' element protruding particles may have a size of about 5.1 nm to about 19.9 nm, about 5.2 nm to about 19.8 nm, about 5.3 nm to about 19.7 nm, about 5.4 nm to about 19.6 nm, about 5.5 nm to about 19.5 nm, about 5.6 nm to about 19.4 nm, about 5.7 nm to about 19.3 nm, about 5.8 nm to about 19.2 nm, about 5.9 nm to about 19.1 nm, about 6.0 nm to about 19.0 nm, about 6.1 nm to about 18.9 nm, about 6.2 nm to about 18.8 nm, about 6.3 nm to 18.7 nm, about 6.4 nm to about 18.6 nm, about 6.5 nm to about 18.5 nm, about 6.6 nm to about 18.4 nm, about 6.7 nm to about 18.3 nm, about 6.8 nm to about 18.2 nm, about 6.9 nm to about 18.1 nm, or about 7.0 nm. Sizes ranging from approximately 10 nm to approximately 18.0 nm.

[0109] The size of B' element protruding particles can be measured by transmission electron microscopy (TEM) or scanning electron microscopy (SEM) images. Alternatively, it can be measured using a measuring device that utilizes grazing incidence small angle X-ray scattering (GISAXS), and data analysis can be performed to count the number of particles in each particle size range, so that the size of the B' element protruding particles can be calculated from the number of particles.

[0110] B'' can be an element that can control the size and distribution of B' element protruding particles.

[0111] B'' may be at least one element selected from zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), gadolinium (Gd), scandium (Sc), and titanium (Ti), and may be an element selected, for example, from zirconium (Zr), hafnium (Hf), niobium (Nb), or tantalum (Ta).

[0112] The B'' element can control the size and distribution of the B'' element protrusions because the B' element moves from the interior of the perovskite oxide lattice to the surface of the perovskite oxide lattice, and the B'' element controls the size and distribution of the B'' element protrusions through a reduction reaction (electron transfer), thus modulating the strain and binding energy between the B' element and oxygen ions. However, one or more embodiments are not limited to this.

[0113] B' element protruding particles can have approximately 50 / square micrometer ( / μm) on the surface of perovskite-based oxide host materials. 2 Approximately 1,000 / μm 2 The density of the B' element. The size and density of the prominent particles are supported by the SEM analysis results described below.

[0114] In an embodiment, relative to the total 100 atomic percentage (atomic %) at the B site of the gas decomposition catalyst, i.e., the total 100 atomic % of element B, element B', and element B'', element B' may occupy an amount greater than about 0 atomic % and at most about 75 atomic %, for example about 1 atomic % to about 50 atomic %, about 3 atomic % to about 30 atomic %, about 5 atomic % to about 20 atomic %, about 5 atomic % to about 15 atomic %, or about 8 atomic % to about 12 atomic %.

[0115] In an embodiment, relative to the total 100 atomic percent at the B site of the gas decomposition catalyst, that is, the total 100 atomic percent of element B, element B' and element B'', element B'' may occupy an amount greater than about 0 atomic percent and at most about 50 atomic percent, for example about 1 atomic percent to about 40 atomic percent, about 3 atomic percent to about 30 atomic percent, about 5 atomic percent to about 20 atomic percent, about 5 atomic percent to about 15 atomic percent, or about 8 atomic percent to about 12 atomic percent.

[0116] The gas decomposition catalyst according to the embodiments can be a catalyst for decomposing nitrous oxide (N2O) gas.

[0117] In the decomposition catalyst according to the embodiments, the nitrous oxide (N2O) decomposition performance can be at least about 1.5 times (e.g., about 1.6 times) higher than that of a gas decomposition catalyst comprising an A (BB'O3) based perovskite oxide host material in which only B' element is doped into the B sites, and one or more B' element protrusion particles derived from a portion or all of the B' element on the surface of the perovskite-based oxide host material. This yields Evaluation Example 3, which will be described below. Figure 7 Support.

[0118] Methods for preparing gas decomposition catalysts

[0119] According to another embodiment, a method for preparing a gas decomposition catalyst may include: preparing a precursor material of a perovskite-based oxide host material represented by Formula 1, wherein different B' elements and B'' elements are doped into B sites; subjecting the precursor material to an oxidative heat treatment to obtain a perovskite-based oxide solid solution; and subjecting the perovskite-based oxide solid solution to a reducing heat treatment in a reducing gas atmosphere at a temperature of about 600°C to about 1,000°C to form one or more B' element protruding particles derived from a portion or all of the B' element on the surface of the perovskite-based oxide host material to prepare a gas decomposition catalyst, wherein the B' element protruding particles may have a shape in which a portion of one particle is fixed inside the perovskite-based oxide host material and another portion of said particle protrudes from the surface of the perovskite-based oxide host material.

[0120] Formula 1

[0121] A(B x B' y B'' z )O3.

[0122] In Equation 1,

[0123] A can be at least one element of strontium (Sr) or lanthanum (La).

[0124] B may be at least one metal (e.g., a transition metal) having an oxidation state of +3, +4 or +5;

[0125] B' can be the Gibbs free energy of the reduction reaction at 900°C according to the following reaction equation 1. At least one of the elements that is 0 or less.

[0126] B'' may be at least one element selected from zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), gadolinium (Gd), scandium (Sc), or titanium (Ti).

[0127] x, y, and z can each be a rational number greater than 0 and less than 1, and

[0128] x+y+z=1.

[0129] Reaction 1

[0130]

[0131] In reaction 1,

[0132] x1 and y1 can each be positive rational numbers.

[0133] red is for restoration, and

[0134] M can be a metal. For example, M can be at least one metal (e.g., a transition metal) having an oxidation state of +3, +4, or +5.

[0135] In the method for preparing a gas decomposition catalyst according to an embodiment, by using a perovskite-based oxide host material, protruding particles of the active element B' can be uniformly distributed and formed on the surface of the perovskite-based oxide host material through a single reduction heat treatment. The protruding particles of the active element B' may have a shape in which a portion of one particle is fixed inside the perovskite-based oxide host material and another portion of said particle protrudes from the surface of the perovskite-based oxide host material.

[0136] Therefore, the gas decomposition catalyst prepared by the method for preparing a gas decomposition catalyst according to the embodiment can be thermally and chemically stable in the operating environment for the decomposition of nitrous oxide (N2O), can have high durability, and can have improved nitrous oxide (N2O) decomposition performance.

[0137] Figure 2 This is a schematic flowchart of a method for preparing a gas decomposition catalyst according to an embodiment.

[0138] refer to Figure 2 Obtaining a perovskite-based oxide solid solution (perovskite (ABB'B''O3)) may include: obtaining a mixture by mixing a precursor of element A, a precursor of element B, a precursor of element B' (active element), and a precursor of element B'' (heterogeneous element), and subjecting the mixture to an oxidative heat treatment in an air atmosphere at a temperature of about 800°C to about 1500°C.

[0139] The precursors of elements A, B, B', and B" can each independently be one of the following: nitrate, sulfate, oxalate, phosphate, acetate, carbonate, citrate, phthalate, perchlorate, hydroxide, alkoxide, halide, halide oxide, oxide, and peroxide, or their hydrates.

[0140] For example, element A may be at least one of strontium (Sr) or lanthanum (La), and for example, A may be strontium (Sr).

[0141] For example, element B may be at least one metal (e.g., a transition metal) having an oxidation number of +3, +4, or +5, and may include elements such as titanium (Ti), aluminum (Al), cobalt (Co), iron (Fe), or nickel (Ni).

[0142] For example, element B' may include at least one of cobalt (Co), nickel (Ni), or iron (Fe).

[0143] For example, element B'' may be at least one of zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), gadolinium (Gd), scandium (Sc), or titanium (Ti), and may be, for example, zirconium (Zr), hafnium (Hf), niobium (Nb), or tantalum (Ta).

[0144] For example, the precursors of elements A, B, B', and B'' can each independently be one of the nitrates, acetates, carbonates, hydroxides, alkoxides, halides, and oxides of each element, or their hydrates.

[0145] Water can be used as a solvent to mix precursors of element A, element B, element B' (the active element), and element B'' (the heterogeneous element), but one or more embodiments are not limited thereto. Any solvent can be used without limitation, as long as it can dissolve and disperse the precursors of each element. For example, alcohol-based solvents such as methanol, ethanol, propanol, or butanol; acid solvents such as nitric acid, hydrochloric acid, or sulfuric acid; and organic solvents such as toluene, benzene, acetone, diethyl ether, or ethylene glycol can be used alone or in combination of two or more.

[0146] The precursors of each element can be mixed with the solvent at a temperature of about 25°C to about 300°C, and the mixture can be obtained by stirring for a specified period of time to allow the components to mix thoroughly with each other. During mixing, additives or the like can be added to remove residual solvents and byproducts.

[0147] The mixture can be subjected to an oxidative heat treatment in an air atmosphere at a temperature of about 800°C to about 1,500°C to obtain a perovskite-based oxide solid solution. The air atmosphere may include oxygen. The oxidative heat treatment can be carried out in such a temperature range for about 4 hours to about 60 hours, for example, about 5 hours to about 30 hours, to obtain the perovskite-based oxide solid solution. Through such an oxidative heat treatment process, some or all of the B' element (the active element) precursor can be transformed into a solid solution in the form of cations within the perovskite-based oxide host material.

[0148] Subsequently, when needed, the perovskite-based oxide solid solution can be ground or pulverized to obtain nanoscale powdered perovskite-based oxide solid solutions. There are no limitations on the pulverization method, but for example, a mortar and pestle can be used, or the pulverization method can be one of the following: ball milling, air jet milling, bead milling, roller milling, manual milling, high-energy ball milling, planetary milling, stirred ball milling, vibratory milling, mechanical fusion milling, shaking table milling, grinding milling, disc milling, shaping milling, nauta milling, nobilta milling, or high-speed mixing. The specific surface area of ​​the nanoscale powdered perovskite-based oxide solid solution can be increased, thereby improving the efficiency of the gas splitting catalyst.

[0149] Next, the perovskite-based oxide solid solution can be subjected to reduction heat treatment in a reducing gas atmosphere at a temperature of about 600°C to about 1,000°C to form one or more B' element protrusion particles, some or all of which are derived from the B' element, on the surface of the perovskite-based oxide host material, thereby preparing a gas decomposition catalyst.

[0150] B' element protruding particles can be reduced particles (dissolved B' metal particles) formed by dissolving from the interior to the surface of a perovskite-based oxide host material.

[0151] Some or all of the reduced particles (dissolved B' metal particles) formed by reduction heat treatment can be embedded in the perovskite-based oxide host material in approximately 50% or less, 40% or less, or 30% or less of the total volume of the perovskite oxide host material. Therefore, the gas decomposition catalyst according to the embodiments can be firmly fixed to the surface of the perovskite-based oxide host material, and thus can possess not only very high thermal and chemical stability but also excellent durability.

[0152] The reduction heat treatment can be carried out in an atmosphere of 1 to 100% H2 gas, H2 / Ar mixture, H2 / N2 mixture, or H2 / He mixture. The volume ratio of the mixed gases can be in the range of about 1 / 99 to about 99 / 1, or for example, the volume ratio of the mixed gases can be in the range of about 3 / 97 to about 97 / 3 or about 5 / 95 to 95 / 5. Within the above volume ratio range, reduced particles (dissolved B' metal particles) with a uniform and homogeneous distribution can be readily formed.

[0153] The reduction heat treatment temperature can be in the range of about 600°C to about 1,000°C, for example, about 700°C to about 1,000°C. Within the above-mentioned range of reduction heat treatment temperature, reduced particles (dissolved B' metal particles) can be formed uniformly, and the crystal structure of the perovskite-based oxide host material can be maintained.

[0154] The reduction heat treatment can be carried out for approximately 1 hour to approximately 24 hours. For example, the reduction heat treatment can be carried out for approximately 1 hour to approximately 12 hours. Within such a heat treatment time range, reduced particles (dissolved B' metal particles) can be formed uniformly and easily, and the crystal structure of the perovskite-based oxide host material can be maintained.

[0155] That is, the gas decomposition catalyst according to the embodiments can maintain the crystal structure of the perovskite-based oxide host material before and after the reduction heat treatment.

[0156] The gas decomposition catalyst prepared by the method for preparing a gas decomposition catalyst according to the embodiment can be a catalyst for decomposing nitrous oxide (N2O) gas.

[0157] Methods for decomposing nitrous oxide gas

[0158] According to another embodiment, a method for decomposing nitrous oxide (N2O) gas may include decomposing nitrous oxide (N2O) gas by contacting a process gas with a gas decomposition catalyst, wherein the gas decomposition catalyst comprises: a perovskite-based oxide host material represented by Formula 1, wherein distinct B' and B'' elements are each doped into B sites; and one or more B' element protrusion particles derived from a portion or all of the B' element on the surface of the perovskite-based oxide host material, wherein the one or more B' element protrusion particles may have a shape in which a portion of one particle is fixed inside the perovskite-based oxide host material and another portion of the particle protrudes from the surface of the perovskite-based oxide host material:

[0159] Formula 1

[0160] A(B x B' y B'' z )O3.

[0161] In Equation 1,

[0162] A can be at least one element of strontium (Sr) or lanthanum (La).

[0163] B can be at least one metal (e.g., a transition metal) having an oxidation state of +3, +4, or +5.

[0164] B' can be the Gibbs free energy of the reduction reaction at 900°C according to the following reaction equation 1. At least one of the elements that is 0 or less.

[0165] B'' can be at least one element of zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), gadolinium (Gd), scandium (Sc), or titanium (Ti).

[0166] x, y, and z can each be a rational number greater than 0 and less than 1, and

[0167] x+y+z=1.

[0168] Reaction 1

[0169]

[0170] In reaction 1,

[0171] x1 and y1 can each be positive rational numbers.

[0172] red is restoration, and

[0173] M can be a metal.

[0174] Process gases may primarily include semiconductor process gases, but may also include gases emitted during display manufacturing processes and flue gas as a product of combustion in an internal combustion engine. There are no limitations on the contact method, but for example, a chamber process may be used to induce a contact reaction with a gas decomposition catalyst via a gas flow (gas stream) from a gas inlet.

[0175] The method for decomposing nitrous oxide (N2O) gas according to the embodiments can be carried out in a low-temperature operating environment, for example, even at a temperature of about 600°C to about 800°C, thereby consuming less energy and exhibiting thermal and chemical stability and improved nitrous oxide decomposition performance.

[0176] B may be chosen differently from B'' and may include at least one element of titanium (Ti), aluminum (Al), cobalt (Co), iron (Fe) or nickel (Ni).

[0177] B' may be chosen differently from B and may include at least one element of cobalt (Co), nickel (Ni), or iron (Fe).

[0178] B'' can be an element that can control the size and distribution of B' element protruding particles.

[0179] In the gas decomposition catalyst according to the embodiment, when a reduction heat treatment is performed at a temperature of 900°C to form B' element protruding particles on the surface of a perovskite-based oxide host material, the content of nitrous oxide (N2O) converted by the gas decomposition catalyst according to Equation 1 below at an operating temperature of 800°C can reach approximately 6.5 × 10⁻⁶. -8 From moles per second (mol / s) to approximately 10.0 × 10⁻⁶ -8Within the range of mol / s:

[0180] Equation 1

[0181] The amount of nitrous oxide (N2O) converted (mol / s) = (the amount of N2O gas flowing into the gas mixer at an operating temperature of 800°C) – (the amount of N2O gas flowing out of the reactor at an operating temperature of 800°C).

[0182] At an operating temperature of 800°C, the gas decomposition catalyst according to the embodiments can have a nitrous oxide (N2O) gas decomposition performance that is about 1.14 to about 1.6 times higher than that of a gas decomposition catalyst in which the B' element protrudes from the surface of a perovskite-based oxide host material in which only the B' element is doped into the B sites.

[0183] air purifier system

[0184] According to another embodiment, a purifier system for decomposing nitrous oxide (N2O) gas may include: a gas inlet through which process gas flows in; a purifier including a gas decomposition catalyst that decomposes the nitrous oxide (N2O) gas from the process gas flowing in from the gas inlet; and a gas outlet through which gas from which nitrous oxide (N2O) gas has been removed flows out of the purifier, wherein the gas decomposition catalyst includes: a perovskite-based oxide host material represented by Formula 1, wherein distinct B' and B'' elements are each doped into B sites; and one or more B' element protrusions on the surface of the perovskite-based oxide host material, wherein the one or more B' element protrusions may have a shape in which a portion of one particle is fixed inside the perovskite-based oxide host material and another portion of the particle protrudes from the surface of the perovskite-based oxide host material.

[0185] Formula 1

[0186] A(B x B' y B'' z )O3.

[0187] In Equation 1,

[0188] A can be at least one element of strontium (Sr) or lanthanum (La).

[0189] B can be at least one metal (e.g., a transition metal) having an oxidation state of +3, +4, or +5.

[0190] B' can be the Gibbs free energy of the reduction reaction at 900℃ according to reaction formula 1. At least one of the elements that is 0 or less.

[0191] B'' can be at least one element of zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), gadolinium (Gd), scandium (Sc), or titanium (Ti).

[0192] x, y, and z can each be a rational number greater than 0 and less than 1, and

[0193] x+y+z=1.

[0194] Reaction 1

[0195]

[0196] In reaction 1,

[0197] x1 and y1 can each be positive rational numbers.

[0198] red is for restoration, and

[0199] M can be a metal. For example, M can be at least one metal (e.g., a transition metal) having an oxidation state of +3, +4, or +5.

[0200] The purifier system for decomposing nitrous oxide (N2O) gas according to the embodiments can be used to treat vehicle exhaust, semiconductor process gases, or process gases used in displays such as liquid crystal displays (LCDs). The purifier system provides a system for efficiently decomposing nitrous oxide (N2O) gas at a high temperature of approximately 800°C in the operating environment, thereby preventing the emission of untreated nitrous oxide (N2O) gas.

[0201] A purifier for decomposing nitrous oxide (N2O) gas according to an embodiment may include one or more reactors, each comprising: a combustion chamber in which process gas flowing in is heated; a catalyst chamber in which the heated process gas flows from the combustion chamber into the catalyst chamber and reacts with a gas decomposition catalyst to decompose nitrous oxide (N2O) gas; and a heat storage chamber in which process gas reacting with the gas decomposition catalyst flows from the catalyst chamber into the heat storage chamber.

[0202] Figure 8 This is a schematic diagram of a purifier system 100 for decomposing nitrous oxide (N2O) gas according to an embodiment.

[0203] refer to Figure 8According to an embodiment, a purifier system 100 for decomposing nitrous oxide (N2O) gas may include: a gas inlet through which process gas flows in; a purifier including a reactor, the reactor including a gas decomposition catalyst, the gas decomposition catalyst decomposing the nitrous oxide (N2O) gas from the process gas flowing in from the gas inlet; and a gas outlet through which gas from which nitrous oxide (N2O) gas has been removed flows out of the purifier.

[0204] The purifier system for decomposing nitrous oxide (N2O) gas according to the embodiments can be designed as follows.

[0205] Process gases can flow in from the gas inlet through a valve. Examples of process gases may include silane (SiH4) gas; hydrogen fluoride (HF) gas; hydrofluorocarbon gases such as CHF3 or CH2F2; and fluorocarbon gases such as C2F4, C2F6, C3F6, C3F8, C4F8, or C4F4. 10 The process gases include sulfur fluoride gases such as SF4 or SF6; nitrogen fluoride gases such as NF3; other gases that can form gaseous products such as HF; and nitrous oxide (N2O) gas. The process gases can pass through chemically coated valves and flow into a purifier containing a gas decomposition catalyst for decomposing nitrous oxide (N2O) gas. A valve allowing air to flow into the purifier from an air inlet can be installed on the other side of the purifier. The amount of gas flowing into the purifier can be regulated by the air inlet valve.

[0206] The burner can be positioned between the gas inlet and the air inlet, and below the purifier. Valves can be directly installed on the fuel line to regulate the burner's combustion rate. The amount of heat input can be adjusted via the valves based on the actual temperature of the combustion chamber F1. Furthermore, a valve (not shown) connected to the combustion air fan can be installed close to the burner's combustion rate regulating valve to prevent excessive combustion air input. The incoming process gas and air can be heated in the combustion chamber F1. The combustion chamber F1 can be maintained at a temperature, for example, approximately 800°C to 850°C.

[0207] The process gas heated in combustion chamber F1 can flow into catalyst chamber C2 for decomposing nitrous oxide (N2O) gas and react with the gas decomposition catalyst. The gas decomposition catalyst can have a shape such as spherical, ellipsoidal, ring-shaped, or cylindrical, or it can be molded. There are no limitations on the catalyst molding method, but for example, extrusion molding, tableting molding, rotary granulation, etc., can be used. For example, the gas decomposition catalyst can be molded into a honeycomb shape or a plate shape. Alternatively, the gas decomposition catalyst can be arranged as a bed inside catalyst chamber C2. For example, the bed on which the gas decomposition catalyst can be placed can be arranged inside catalyst chamber C2 in the form of a filled bed (or fixed bed) or a fluidized bed. The process gas flowing into catalyst chamber C2 can be heated to a temperature at which the process gas can react with the catalyst, for example, about 800°C.

[0208] A heat storage chamber H2 can be installed on the catalyst chamber C2, and the process gas reacting with the gas decomposition catalyst flows from the catalyst chamber C2 into the heat storage chamber H2. For the heat storage chamber H2, a heat sink made of ceramic materials such as alumina can be used. The heat sink can be used in quantities greater than or equal to 100% of the required heat to increase heat recovery efficiency. Alternatively, a monolithic heat sink can be used to minimize pressure loss and power consumption. The process gas flowing into the heat storage chamber H2 loses heat as it passes through the heat sink and can exit through a valve, thus removing nitrous oxide (N2O) gas.

[0209] Optionally, in the purifier system, a gas condenser (not shown) may be additionally installed on the purifier to remove untreated nitrous oxide (N2O) gas before it exits the gas stream from which nitrous oxide (N2O) gas is removed. The gas condenser condenses the vapor gas exiting the purifier to form process condensate. The process condensate can also be used as a coolant to control the temperature inside the purifier by means of a delivery pipe (not shown) passing between the gas condenser (not shown) and the purifier.

[0210] Alternatively, in the purifier system according to the embodiment, when the combustion chamber F1 is installed above the reactor of the purifier, the positions of the catalyst chamber C2 and the heat storage chamber H2 described above can be reversed.

[0211] If necessary, in the purifier system according to the embodiment, a preliminary (preparatory) heat storage chamber can be installed before installing the reactor to preheat the process gas, so that the process gas having essentially the catalyst decomposition temperature flows into the catalyst chamber C2. For example, the preliminary heat storage chamber can be installed between the catalyst chamber C2 and the combustion chamber F1. For the preliminary heat storage chamber, a radiator comprising the same ceramic material as the heat storage chamber H2 can be used. The degree of temperature rise of the incoming process gas can be adjusted according to the number of radiators used in the preliminary heat storage chamber and the initial temperature.

[0212] The purifier system according to the embodiment may have a structure in which two or more reactors are arranged in parallel.

[0213] For example, the purifier system according to the embodiment may have the following structure: a first reactor in which a first heat storage chamber and a first catalyst chamber are installed and a second reactor in which a second heat storage chamber and a second catalyst chamber are installed are arranged in parallel, and a combustion chamber on which a burner is located is provided.

[0214] The purifier system for decomposing nitrous oxide (N2O) gas according to the embodiment may have the following structure: in addition to the first and second reactors arranged in parallel as described above, a third or fourth reactor is also arranged in parallel.

[0215] Purifier systems for decomposing nitrous oxide (N2O) gas can improve the efficiency of treating nitrous oxide (N2O) gas while minimizing fuel consumption.

[0216] Hereinafter, embodiments and comparative examples will be described. However, the following embodiments are merely examples of this disclosure, and this disclosure is not limited to the following embodiments.

[0217] Example

[0218] Reference Example 1: Sr(Ti 0.9 Co 0.1 O3 gas decomposition catalyst

[0219] SrCO3, TiO2, and Co3O4 were placed in a reactor at a stoichiometric ratio of 1:0.9:0.1 and mixed for approximately 12 hours to obtain a mixture. The mixture was then subjected to an oxidative heat treatment in air at approximately 1300°C for 16 hours to obtain Sr(TiO2)O4 in which cobalt (Co) is dissolved in the perovskite oxide lattice. 0.9 Co 0.1 O3 is a perovskite-based oxide solid solution.

[0220] Use a mortar and pestle to mix Sr(Ti) 0.9 Co 0.1O3-based perovskite oxide solid solution pulverization to obtain pulverized Sr(Ti) 0.9 Co 0.1 O3 is a perovskite-based oxide solid solution (before reduction).

[0221] The crushed Sr(Ti) 0.9 Co 0.1 O3-based perovskite oxide solid solutions were subjected to reduction heat treatment at 900 °C for 10 hours in a H2 / Ar (5 / 95, volume / volume (v / v)) atmosphere to prepare a product in which cobalt (Co) elements, transformed into solid solutions within the perovskite oxide lattice, were dissolved (after reduction). In this case, Sr(Ti) was prepared from this product, in which spherical cobalt (Co) protrusions with a diameter of 13 nm were formed. 0.9 Co 0.1 O3 gas decomposition catalyst.

[0222] Example 1: Sr(Ti) 0.8 Co 0.1 Zr 0.1 O3 gas decomposition catalyst

[0223] Sr(Ti) was prepared in the same manner as in Reference Example 1, wherein spherical cobalt (Co) protrusion particles with a diameter of 14.93 nm were formed. 0.8 Co 0.1 Zr 0.1 The O3 gas decomposition catalyst, except for the following: SrCO3, TiO2, Co3O4 and ZrO2 are placed in a reactor in a stoichiometric ratio of 1:0.8:0.1:0.1 and mixed for about 12 hours to obtain a mixture, and then Sr(TiO2) with cobalt (Co) element dissolved in it is obtained. 0.8 Co 0.1 Zr 0.1 O3 is a perovskite-based oxide solid solution.

[0224] Example 2: Sr(Ti) 0.8 Co 0.1 Hf 0.1 O3 gas decomposition catalyst

[0225] The Sr(Ti0.8Co0.1Hf0.1)O3 gas decomposition catalyst in which spherical cobalt (Co) element protrusions with a diameter of 13.19 nm are formed was prepared in the same manner as in Reference Example 1, except that SrCO3, TiO2, Co3O4 and HfO2 were placed in the reactor in a stoichiometric ratio of 1:0.8:0.1:0.1.

[0226] Example 3: Sr(Ti) 0.8 Co0.1 Nb 0.1 O3 gas decomposition catalyst

[0227] Sr(Ti) was prepared in the same manner as in Reference Example 1, wherein spherical cobalt (Co) protrusion particles with a diameter of 7.9 nm were formed. 0.8 Co 0.1 Nb 0.1 The O3 gas decomposition catalyst, except that SrCO3, TiO2, Co3O4 and Nb2O5 are placed in the reactor in a stoichiometric ratio of 1:0.8:0.1:0.1.

[0228] Example 4: Sr(Ti) 0.8 Co 0.1 Ta 0.1 O3 gas decomposition catalyst

[0229] Sr(Ti) was prepared in the same manner as in Reference Example 1, wherein spherical cobalt (Co) element protrusions with a diameter of 8.5 nm were formed. 0.8 Co 0.1 Ta 0.1 The O3 gas decomposition catalyst, except as follows: SrCO3, TiO2, Co3O4 and Ta2O5 are placed in the reactor in a stoichiometric ratio of 1:0.8:0.1:0.1.

[0230] Evaluation Example 1: XRD Spectroscopy Experiment - Crystal Structure

[0231] To confirm the crystal structures of the perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4 before and after reduction, X-ray diffraction (XRD) spectroscopy experiments using CuKα rays were performed. The results are shown below. Figure 3A and 3B middle.

[0232] XRD spectroscopy experiments were performed at diffraction angles 2θ ranging from 20° to 80° at a rate of 1 degree per minute (° / min). The results are shown in... Figure 3A (Before reduction and before dissolution) and Figure 3B (After reduction and after dissolution)

[0233] refer to Figure 3A and 3B In all the perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4, the crystal structure remained unchanged before and after reduction.

[0234] Therefore, it can be confirmed that the perovskite-based oxide gas decomposition catalysts prepared in Examples 1 to 4 are thermally and chemically stable.

[0235] Evaluation Example 2: SEM Analysis - Particle Size and Density

[0236] To confirm the surface condition of the perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4 after reduction, SEM analysis was performed. The results are shown in... Figure 4 middle.

[0237] The SEM used for SEM analysis was a SU-9000 manufactured by Hitachi High-Tech Corporation.

[0238] refer to Figure 4 It can be confirmed that, after reduction, particles dissolved on the respective surfaces of the perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4.

[0239] In particular, the particles dissolved on the surface of the perovskite-based oxide gas decomposition catalyst prepared in Reference Example 1 and Examples 1 to 4 have a shape close to that of a sphere, such as a sphere or an ellipsoid.

[0240] It can be confirmed that, compared with the perovskite-based oxide gas decomposition catalyst prepared in Reference Example 1, the size of the particles dissolved on the surface of the perovskite-based oxide gas decomposition catalysts prepared in Examples 1 to 4 gradually decreases and the particles are more uniformly distributed.

[0241] It has been confirmed that the diameter of the particles dissolved from the surface of the perovskite-based oxide gas decomposition catalysts prepared in Examples 1 to 4 is in the range of about 5 nm to about 20 nm, and their density is about 50 μm. 2 Approximately 1,000 / μm 2 Within the range.

[0242] Evaluation Example 3: Experiment on the content of converted nitrous oxide (N2O) – Evaluation of N2O decomposition performance

[0243] To evaluate the temperature-dependent performance of the perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4, the following perovskite-based catalysts were manufactured according to... Figure 5 A system for the decomposition of nitrous oxide (N₂O) gas. The results show... Figure 6 In, and the results at an operating temperature of 800℃ are shown Figure 7 middle.

[0244] In particular, according to Figure 5 The decomposition system of nitrous oxide (N2O) gas is as follows.

[0245] The perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4 are each arranged as beds inside the reactor. A gas mixer, a second thermocouple TC2 for measuring the temperature of the gas decomposition catalyst bed, and a first pressure gauge PG1 for measuring pressure are connected to the upper part of the reactor. The gas mixer includes three mass flow controllers (MFCs). A N2O / He mixture containing 3,000 parts per million (ppm) of N2O at 100 standard cubic centimeters per minute (sccm), N2 gas, and O2 gas flow into the three mass flow controllers (MFCs), respectively. Two furnaces for heating the reactor are arranged on both sides of the reactor, and the first thermocouple TC1 is connected to one side of them. The second pressure gauge PG2 for measuring pressure and a gas concentration meter (FT-IR manufactured by MIDAC Cooperation) for measuring the concentration of each gas flowing from the inside of the reactor to the outside are connected to the lower part of the reactor.

[0246] By using according to Figure 5 The nitrous oxide (N2O) gas decomposition system was evaluated by substituting the nitrous oxide (N2O) content converted according to temperature into Equation 1 and calculating to evaluate the N2O decomposition performance of each perovskite-based oxide gas decomposition catalyst.

[0247] Equation 1

[0248] The amount of nitrous oxide (N2O) converted (mol / s) = (N2O gas content flowing into the gas mixer at an operating temperature of 800°C) – (N2O gas content flowing out of the reactor at an operating temperature of 800°C)

[0249] refer to Figure 6 It can be confirmed that in all perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4, the content of converted nitrous oxide (N2O) increases with increasing temperature from 300°C to 800°C.

[0250] Therefore, it can be confirmed that the N2O decomposition performance of all perovskite-based oxide gas decomposition catalysts prepared in Reference Example 1 and Examples 1 to 4 increases with increasing temperature.

[0251] Among them, the Sr(Ti) prepared in Example 2 0.8 Co 0.1 Hf 0.1 The N2O decomposition performance of the O3 gas decomposition catalyst is significantly improved with increasing temperature.

[0252] refer to Figure 7It can be confirmed that, compared with the perovskite-based oxide gas decomposition catalyst prepared in Reference Example 1, the perovskite-based oxide gas decomposition catalysts prepared in Examples 1 to 4 at a temperature of 800°C have a higher content of converted nitrous oxide (N2O) and relatively superior N2O decomposition performance.

[0253] Among them, the Sr(Ti) prepared in Example 2 0.8 Co 0.1 Hf 0.1 In the O3 gas decomposition catalyst, the content of converted nitrous oxide (N2O) is about 1.6 times higher than that of the perovskite-based oxide gas decomposition catalyst prepared in Reference Example 1.

[0254] Therefore, it can be confirmed that the Sr(Ti) prepared in Example 2... 0.8 Co 0.1 Hf 0.1 The N2O decomposition performance of O3 gas decomposition catalysts is relatively excellent.

[0255] A gas decomposition catalyst according to one aspect may include: a perovskite-based oxide host material represented by Formula 1, wherein distinct B' and B'' elements are each doped into B sites; and one or more B' element protrusion particles, some or all of which are derived from the B' element, on the surface of the perovskite-based oxide host material. The B' element protrusion particles may have a shape in which a portion of one particle is fixed within the perovskite-based oxide host material and another portion of said particle protrudes from the surface of the perovskite-based oxide host material. The gas decomposition catalyst may be thermally and chemically stable in the operating environment for nitrous oxide (N2O) decomposition and may have improved nitrous oxide (N2O) decomposition performance.

[0256] It should be understood that the embodiments described herein are to be considered in a descriptive sense only and are not intended for limiting purposes. The descriptions of features or aspects in each embodiment should typically be considered applicable to other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope defined by the appended claims.

Claims

1. Gas decomposition catalysts, including: The perovskite-based oxide host material represented by Equation 1, wherein distinct B' and B'' elements are each doped into B sites, and One or more B' element protruding particles, some or all of the B' element, on the surface of the perovskite-based oxide host material. The one or more B' element protruding particles have a shape in which a portion of one particle is fixed inside the perovskite-based oxide host material and another portion of the particle protrudes from the surface of the perovskite-based oxide host material. Formula 1 A(B x B' y B'' z )O3 In Equation 1, A is at least one element, either strontium or lanthanum. B is at least one of a metal having an oxidation state of +3, +4, or +5. B' is the Gibbs free energy of the reduction reaction according to reaction 1 at 900℃. At least one element that is 0 or less. B'' is at least one of zirconium, hafnium, niobium, tantalum, gadolinium, scandium, or titanium. x, y, and z are each rational numbers greater than 0 and less than 1, and x+y+z=1: Reaction 1 In reaction 1, x1 and y1 are both positive rational numbers. red is restoration, and M is a metal.

2. The gas decomposition catalyst according to claim 1, wherein B and B'' are selected differently and include at least one element of titanium, aluminum, cobalt, iron or nickel.

3. The gas decomposition catalyst according to claim 1, wherein B' is selected differently from B and includes at least one element of cobalt, nickel or iron.

4. The gas decomposition catalyst according to claim 1, wherein the one or more B' element protruding particles have a spherical shape, an ellipsoidal shape, a ring shape, or a cylindrical shape.

5. The gas decomposition catalyst according to claim 1, wherein the one or more B' element protruding particles are nanoparticles.

6. The gas decomposition catalyst according to claim 1, wherein the one or more B' element protruding particles have a size of 5 nanometers to 20 nanometers.

7. The gas decomposition catalyst according to claim 1, The B'' element can control the size and distribution of the one or more B' element protruding particles.

8. The gas decomposition catalyst according to claim 1, wherein the one or more B' element protruding particles have a density of 50 / μm² to 1,000 / μm² on the surface of the perovskite-based oxide host material.

9. The gas decomposition catalyst of claim 1, wherein the B' element occupies an amount greater than 0 atomic percentage and at most 75 atomic percentage relative to a total of 100 atomic percentages at the B site, and The B'' element occupies an amount greater than 0 atomic percentage and at most 50 atomic percentage relative to the total 100 atomic percentage at the B site.

10. The gas decomposition catalyst according to claim 1, wherein the gas decomposition catalyst decomposes nitrous oxide gas.

11. A method for decomposing nitrous oxide gas, said method comprising contacting a gas stream comprising nitrous oxide gas with a gas decomposition catalyst. The gas decomposition catalyst includes: The perovskite-based oxide host material represented by Equation 1, wherein distinct B' and B'' elements are each doped into B sites; and One or more B' element protruding particles, some or all of the B' element, on the surface of the perovskite-based oxide host material. The one or more B' element protruding particles have a shape in which a portion of one particle is fixed inside the perovskite-based oxide host material and another portion of the particle protrudes from the surface of the perovskite-based oxide host material. Formula 1 A(B x B' y B'' z )O3 In Equation 1, A is at least one element, either strontium or lanthanum. B is at least one of a metal having an oxidation state of +3, +4, or +5. B' is the Gibbs free energy of the reduction reaction according to reaction 1 at 900℃. At least one of the elements that is 0 or less. B'' is at least one of zirconium, hafnium, niobium, tantalum, gadolinium, scandium, or titanium. x, y, and z are each rational numbers greater than 0 and less than 1, and x+y+z=1: Reaction 1 In reaction 1, x1 and y1 are both positive rational numbers. red is restoration, and M is a metal.

12. The method of claim 11, wherein B comprises at least one element of titanium, aluminum, cobalt, iron, or nickel.

13. The method of claim 11, wherein B' comprises at least one element of cobalt, nickel, or iron.

14. The method of claim 11, wherein the one or more B' element protruding particles are reduced particles formed to dissolve from the interior of the perovskite-based oxide host material to the surface of the perovskite-based oxide host material.

15. The method of claim 11, wherein the B'' element is capable of controlling the size and distribution of the one or more B' element protruding particles.

16. The method according to claim 11, wherein, When the gas decomposition catalyst is configured to be subjected to a reduction heat treatment at 900°C to form one or more B' element protruding particles on the surface of the perovskite-based oxide host material, the content of nitrous oxide converted by the gas decomposition catalyst according to Equation 1 at an operating temperature of 800°C is 6.5 × 10⁻⁶. -8 moles per second to 10.0 × 10 -8 Within the range of moles per second: Equation 1 The amount of nitrous oxide converted (mol / s) = (the amount of nitrous oxide gas flowing into the gas mixer at an operating temperature of 800°C) – (the amount of nitrous oxide gas flowing out of the reactor at an operating temperature of 800°C).

17. A purifier system for decomposing nitrous oxide gas, said purifier system comprising: Gas inlet, through which process gas flows in; A purifier comprising a gas decomposition catalyst that decomposes nitrous oxide gas from the process gas flowing in from the gas inlet; and The gas outlet from which the nitrous oxide gas has been removed flows out of the purifier. The gas decomposition catalyst comprises: a perovskite-based oxide host material represented by Formula 1, wherein distinct B' and B'' elements are each doped into B sites; and One or more B' element protruding particles, some or all of the B' element, on the surface of the perovskite-based oxide host material. The one or more B' element protruding particles have a shape in which a portion of one particle is fixed inside the perovskite-based oxide host material and another portion of the particle protrudes from the surface of the perovskite-based oxide host material. Formula 1 A(B x B' y B'' z )O3 In Equation 1, A is at least one element, either strontium or lanthanum. B is at least one of a metal having an oxidation state of +3, +4, or +5. B' is the Gibbs free energy of the reduction reaction according to reaction 1 at 900℃. At least one of the elements that is 0 or less. B'' is at least one of zirconium, hafnium, niobium, tantalum, gadolinium, scandium, or titanium. x, y, and z are each rational numbers greater than 0 and less than 1, and x+y+z=1: Reaction 1 In reaction 1, x1 and y1 are both positive rational numbers, and M is a metal.

18. The purifier system of claim 17, wherein the purifier comprises one or more reactors, the one or more reactors comprising: The combustion chamber in which the incoming process gas is heated; Catalyst chamber, in which the heated process gas flows from the combustion chamber into the catalyst chamber and reacts with the gas decomposition catalyst to decompose the nitrous oxide gas; and The process gas that reacts with the gas decomposition catalyst flows from the catalyst chamber into the heat storage chamber.

19. The purifier system of claim 18, wherein the gas decomposition catalyst itself has a shape, or the gas decomposition catalyst is molded or disposed as a bed inside the catalyst chamber. The shape is described as spherical, ellipsoidal, annular, or cylindrical.

20. The purifier system of claim 18, wherein the one or more reactors comprise two or more reactors arranged in parallel.

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