Metal-supported catalysts for methane combustion under wet conditions, methods for preparing the same, and their use

Abstract

The present invention relates to a method for obtaining a metal-supported catalyst, and to a metal-supported catalyst particularly suitable for methane combustion under wet conditions. The present invention also relates to the use of a metal-supported catalyst in methane combustion, preferably in methane combustion under wet conditions. Furthermore, the present invention relates to a method of methane combustion under wet conditions, involving the use of a metal-supported catalyst according to the present invention.

Description

[Technical Field]

[0001] The present invention relates to a method for obtaining a metal-supported catalyst, and to a metal-supported catalyst particularly suitable for methane combustion under wet conditions. The present invention also relates to the use of the metal-supported catalyst in methane combustion, preferably in methane combustion under wet conditions. Furthermore, the present invention relates to a method of methane combustion under wet conditions, involving the use of the metal-supported catalyst according to the present invention. [Background technology]

[0002] A significant source of methane emissions comes from large-scale stationary natural gas engines used for power production and marine applications. Furthermore, because natural gas contains over 90% methane, more conventional fossil fuels are being replaced by sustainable energy sources such as natural gas, which yields greater amounts of methane. However, methane is a powerful greenhouse gas with a global warming potential approximately 28 times higher than CO2.

[0003] Therefore, finding an efficient way to manage these methane quantities becomes absolutely necessary, and in this context, methane oxidation is particularly relevant. However, the main drawback of methane oxidation catalysts (MOCs), such as those based on platinum group metals, is their lack of stability in the flow of methane and water.

[0004] Solutions based on Pd / Al2O3 methane oxidation catalysts have gained considerable attention over time, but despite extensive research, there remains an urgent need for methane oxidation catalysts that remain stable in the presence of water. Inactivation typically stems from Pd sintering, water adsorption, hydroxyl formation, and sulfate formation when sulfur is present in the gaseous flow.

[0005] Furthermore, for catalytic applications in methane combustion to be successful, the catalytic system must exhibit high catalytic activity at low intermediate reaction temperatures (i.e., temperatures below approximately 550°C). However, known methane oxidation catalysts typically undergo severe deactivation in the presence of water, for example, when the reaction flow contains water. In this regard, methane oxidation catalytic systems are generally adversely affected by the presence of water, and it is known that catalytic performance is greatly inhibited and altered at such low intermediate reaction temperatures, as described, for example, by Hoque et al. (Korean J. Chem. Eng. 2014, 31, 1316).

[0006] On the other hand, ceria and cerium-based mixed oxides are known in the art to typically provide suitable supports for depositing platinum group metals to form metal-supported catalytic systems. Different ceria particles, either rod-shaped or cubic in form, have recently been evaluated in the literature as catalytic supports for methane combustion, although all of these studies have been conducted under dry conditions: Guo et al. (RSC Adv. 2018, 8, 38641-38647), Dong et al. (Chin. J. Catal. 2021, 42, 2234-2241), Zhou et al. (Chinese Patent Application CN113274999), and Chen et al. (ACS Catal. 2021, 11, 5666-5677). However, due to the significant influence of water on catalytic performance in methane combustion, it is impossible to extrapolate the results achieved under dry conditions, as described by Hoque et al., to those obtained under wet conditions.

[0007] Therefore, there is a need for a technological solution that can provide a novel metal-supported catalyst system that advantageously offers high catalytic activity in methane combustion reactions occurring under wet conditions, while also possessing significant resistance to deactivation under those operating conditions. [Overview of the project] [Means for solving the problem]

[0008] In a first aspect of the present invention, a method for obtaining a metal-supported catalyst is provided, the method comprising the following steps: a) Adding at least one supported transition metal (M) selected from any of Groups 5 to 11 of the periodic table of elements to a support material, wherein the support material includes at least one oxide selected from the group consisting of ceria, ceria-based mixed oxides, and any combination thereof. b) Preferably, the step of drying under homogenizing conditions, c) The solid obtained in step b) is heat-treated at a temperature of approximately 250°C to approximately 850°C, If at least one oxide is substantially present in crystalline form and determined by HRTEM, it has an average grain size of 5-20 nm, and if measured by BET method using nitrogen gas adsorption after activation under vacuum at 400°C for 3 hours, it has a grain size of 50-140 nm. 2 The specific surface area is expressed as the molar ratio of at least one supported transition metal (M) selected from any of groups 5 to 11 of the periodic table of the element (M) to the surface oxygen in the supporting material (i.e., the molar ratio of [at least one supported transition metal (M)]:[surface oxygen in supporting material], or (M / O) surf A method is provided in which the molar ratio is 0.4 to 1.4 when determined by H2 temperature programmed reduction (H2-TPR). In the context of the present invention, the H2-TPR analysis was performed on a metal-free support, where “metal-free” should be understood herein to mean the absence of at least one supported transition metal (M) throughout the patent application.

[0009] Throughout this patent application, the terms "the molar ratio of at least one supported transition metal (M) to surface oxygen in the supporting material" and "M / O surf The expressions "and" are used interchangeably. Similarly, "the molar ratio of palladium in the support material to surface oxygen" and "Pd / O surf The expression " " is used interchangeably.

[0010] Furthermore, when calculating the molar ratio of at least one supported transition metal (M) in the support material to surface oxygen, the total number of moles corresponding to the supported transition metal(s) should be taken into consideration, that is, in the method according to the first aspect of the present invention, if two or more supported transition metals are added in step a), M / O surf To calculate the value, the total number of moles of all supported transition metals should be taken into consideration.

[0011] According to a second aspect of the present invention, a metal-supported catalyst for methane combustion under wet conditions, - A support material comprising at least one oxide selected from the group consisting of ceria, ceria-based mixed oxides, and any combination thereof, - comprising at least one supported transition metal (M) selected from any of Groups 5 to 11 of the periodic table of elements, At least one oxide is substantially present in crystalline form and, when determined by HRTEM, has an average particle size of 5–20 nm, and when measured by BET method using nitrogen gas adsorption after activation under vacuum at 400°C for 3 hours, it is 50–140 nm. 2 A metal-supported catalyst exhibiting a specific surface area of ​​ / g is provided.

[0012] When used throughout this specification, the expression “methane combustion under wet conditions” should be understood to mean that methane combustion is carried out using a reaction feed having a volume percentage of water ranging from 0.5% to 30% based on the total volume of the reaction feed. In preferred embodiments, the wet conditions used during methane combustion may be understood to mean that methane combustion is carried out using a reaction feed having a volume percentage of water ranging from 5% to 15% based on the total volume of the reaction feed.

[0013] In a third aspect of the present invention, a method for burning methane under wet conditions, the method comprising the following steps: a) The step of introducing a metal-supported catalyst into a reactor, as defined by a second aspect of the present invention, b) A step of supplying a gas reaction feed to a reactor, the feed comprising methane, 5% to 15% (v / v) of water, and at least one inert gas, wherein the sum of all components in the gas reaction feed is 100% (v / v), c) A method is provided which includes the step of enabling the metal-supported catalyst to remain in contact with the gaseous reaction feed in the reactor for a sufficient time and at a sufficient temperature for methane combustion to occur.

[0014] A fourth aspect of the present invention provides the use of a metal-supported catalyst according to the second aspect of the present invention in methane combustion, preferably in methane combustion under wet conditions. [Brief explanation of the drawing]

[0015] [Figure 1] HRTEM image of a nano-sized ceria support used in a metal-supported catalyst prepared according to the present invention. [Figure 2] H2 temperature programmed reduction profile of a nano-sized ceria support used in a metal-supported catalyst prepared according to the present invention. [Figure 3] This is a light-off type experiment to evaluate the catalytic performance of the methane combustion reaction under humid conditions, using different nanoceria supports containing 3 wt% Pd, prepared according to Examples 1-4 of the present invention. [Figure 4] This was a long-term steady-state methane combustion experiment to evaluate the catalytic performance of the methane combustion reaction under humid conditions and dynamic high-temperature fluctuations (400-600°C), using different nanoceria supports containing 3 wt% Pd, prepared according to Examples 1-4 of the present invention. [Figure 5] This was a light-off type experiment to evaluate the catalytic performance of the methane combustion reaction under humid conditions, using nanoceria Ce2 as supports containing different Pd content, prepared according to Example 1 (3 wt% Pd), Example 5 (5 wt% Pd), and Example 6 (1 wt% Pd) of the present invention (see Table 1). [Figure 6]This was a long-term steady-state methane combustion experiment to evaluate the catalytic performance of the methane combustion reaction under humid conditions and dynamic high-temperature fluctuations (400-600°C), using nanoceria Ce2 as supports containing different Pd content, prepared according to Example 1 (3 wt% Pd), Example 5 (5 wt% Pd), and Example 6 (1 wt% Pd) of the present invention (see Table 1). [Figure 7] This was a long-term steady-state methane combustion experiment to evaluate the catalytic performance of the methane combustion reaction under humid conditions and dynamic high-temperature fluctuations (400-600°C), using nanoceria Cel and Ce2 as supports containing different Pd content, prepared according to Example 1 (Ce2_3 wt%Pd), Example 3 (Cel_3 wt%Pd), Example 5 (Ce2_5 wt%Pd), and Example 7 (Cel_5 wt%Pd) of the present invention (see Table 1). [Figure 8] A long-term steady-state methane combustion experiment to evaluate the catalytic performance of a methane combustion reaction under wet conditions using a bimetallic catalyst according to Example 8 of the present invention. [Figure 9] A long-term steady-state methane combustion experiment to evaluate the catalytic performance of a methane combustion reaction under wet conditions using a catalyst according to Example 9 of the present invention. [Modes for carrying out the invention]

[0016] In a first aspect of the present invention, a method for obtaining a metal-supported catalyst is provided, the method comprising the following steps: a) Adding at least one supported transition metal (M) selected from any of Groups 5 to 11 of the periodic table of elements to a support material, wherein the support material includes at least one oxide selected from the group consisting of ceria, ceria-based mixed oxides, and any combination thereof. b) Preferably, the step of drying under homogenizing conditions, c) The solid obtained in step b) is heat-treated at a temperature of approximately 250°C to approximately 850°C, When at least one oxide is substantially present in crystalline form and has an average particle size of 5 - 20 nm as determined by HRTEM, and when measured by the BET method using nitrogen gas adsorption after activation at 400 °C for 3 hours under vacuum, it exhibits a specific surface area of 50 - 140 m 2 / g, and the molar ratio (M / O surf ) of at least one supported transition metal (M) to surface oxygen in the support material is 0.4 - 1.4 as determined by H2 - TPR, and the H2 - TPR analysis was carried out on a metal - free support.

[0017] The H2 - TPR analysis on a metal - free ceria support enables the estimation of surface oxygen species (O surf ) present in the support material, for example, by quantifying the H2 consumption peak at 250 - 550 °C as shown in Figure 2. The theoretical value of the supported transition metal(s) deposited on the support material can be established considering that the experimentally deposited supported transition metal(s) remain in the final catalyst. In any case, the amount of the experimentally deposited supported transition metal(s) can optionally be confirmed by inductively coupled plasma (ICP) analysis.

[0018] The inventors have surprisingly found that by controlling the properties of the support material such as the available surface oxygen, especially the above - mentioned M / O surf ratio, specific surface area, and average particle size, not only can an efficient deposition of the transition group metal(s) be achieved, but also the catalytic activity and stability of the resulting metal - supported catalyst are advantageously maximized under wet reaction conditions. Specifically, it has been found that the above - mentioned M / O surf ratio is an important parameter in the catalyst synthesis method for enhancing such stability and activity of the metal - supported catalyst for the methane combustion reaction under wet conditions. Furthermore, the nano - sized metal - supported catalyst of the present invention, which can be obtained according to the first aspect of the present invention, provides improved stability during a longer time - on - stream (TOS) period and even after undergoing dynamic high - temperature fluctuations compared to other known catalysts.

[0019] The at least one supported transition metal (M) added in step a) of the method according to the first aspect of the present invention may be provided in the form of a metal salt or a metal composite, or alternatively, as a metallic alloy. The addition of the at least one supported transition metal (M) to the support material may preferably be carried out by wet impregnation, initial volume impregnation, or deposition precipitation, which are methods widely known in the art. In preferred embodiments, if multiple supported transition metals are used to produce the metal-supported catalyst of the present invention according to the first aspect, they may all be added in step a) of the method, and as a result, the subsequent steps b) and c) may need to be carried out only once on the previously formed mixture of the multiple supported transition metals to produce the metal-supported catalyst. These embodiments have been found to be particularly advantageous because they avoid longer multi-step methods known in the art, in which each supported transition metal is subjected independently to all steps a) to c) and thus requires several drying and calcination steps to produce the final catalyst.

[0020] In a preferred embodiment, at least one supported transition metal (M) is added in step a) of the method according to the first aspect of the present invention, and as a result, the total amount of supported transition metal on the support material is 2% by weight or more, based on the total weight of the resulting metal-supported catalyst. In other embodiments, at least one supported transition metal (M) is added in step a) of the method according to the first aspect of the present invention, and as a result, the total amount of supported transition metal on the support material is greater than 2% by weight, 2% to 5% by weight, 2.5% to 5% by weight, 3% to 5% by weight, or greater than 2% to 3% by weight, based on the total weight of the resulting metal-supported catalyst.

[0021] In some embodiments, the metal-supported catalyst may include, as a metallic alloy, at least one supported transition metal (M), or may provide a plurality of supported transition metals (M). In these embodiments, the metal-supported catalyst may preferably include, as a metallic alloy, at least 2% by weight or more of at least one supported transition metal (M) based on the total weight of the metal-supported catalyst, or alternatively, as a metallic alloy, at least 2% by weight, more than 2% by weight to 5% by weight, 2.5% by weight to 5% by weight, 2% by weight to 4% by weight, or more than 2% by weight to 3% by weight, based on the total weight of the metal-supported catalyst.

[0022] At least one supported transition metal (M) may be particularly selected from the group consisting of Pd, Pt, Rh, Ir, Cu, Ru, Co, Ag, Nb, and any mixtures thereof, preferably at least one supported transition metal (M) may be selected from the group consisting of Pd, Pt, Rh, Ir, Ru, and any mixtures thereof, more preferably at least one supported transition metal (M) may be selected from the group consisting of Pd, Pt, Rh, Ru, and any mixtures thereof, even more preferably at least one supported transition metal (M) may be selected from the group consisting of Pd, Pt, Ru, and any mixtures thereof, and even more preferably at least one supported transition metal (M) may be Pd or Pt. In another preferred embodiment, at least one supported transition metal (M) is Pd or consists of Pd. Examples of suitable transition metal salts or complexes include, but are not limited to, palladium propionate, palladium butyrate, tris(dibenzylideneacetone)dipalladium(0), tris(trivenzylideneacetylacetone)tripalladium(0), palladium benzoate, palladium acetylacetonate, palladium nitrate, palladium sulfate, palladium chloride, palladium acetate, acetylacetone acetate, platinum acetate, dinitrodiamine platinum nitrate, sodium chloroplatinate, sodium hexachloroplatinate, tetraamine platinum nitrate, rhodium nitrate, rhodium chloride, iridium tribromide, iridium chloride, potassium iridium chloride, ruthenium nitrate, ruthenium chloride, ammonium chlororuthenate, or potassium ruthenate.

[0023] Throughout this specification, the expression “metallic alloy” with reference to at least one supported transition metal (M) primarily refers to an alloy containing, as a major component, at least one supported transition metal element selected from any of Groups 5 through 11 of the periodic table; that is, an alloy contains at least 80% by weight (i.e., 80% by weight or more) of at least one supported transition metal element based on the total weight of the alloy. In preferred embodiments, a preferred metallic alloy contains at least 90% by weight (i.e., 90% by weight or more) of at least one supported transition metal element based on the total weight of the alloy. In some embodiments, a metallic alloy may contain two supported transition metal (M) elements, one of which is the major component. Examples of preferred metallic alloys, but not limited to, include Pd-Pt alloys, Pt-Au alloys, Pt-Ru alloys (e.g., Pt containing 5% by weight of Ru), and Pt-Rh alloys (e.g., Pt containing 10% by weight of Rh).

[0024] The support material used in the method according to the first aspect of the present invention comprises at least one oxide selected from the group consisting of ceria, ceria-based mixed oxides, and any combination thereof, wherein the at least one oxide exists substantially in a crystalline form. As used throughout this specification, the expression “substantially present in a crystalline form” means that at least 90% by weight of the at least one oxide is in a crystalline form based on the total weight of the at least one oxide (i.e., up to 10% by weight of the at least one oxide may be in an amorphous form based on its total weight). According to some embodiments, at least 95% by weight of the at least one oxide is provided in a crystalline form based on the total weight of the at least one oxide (i.e., up to 5% by weight of the at least one oxide may be in an amorphous form based on its total weight). In some other embodiments, the at least one oxide may be entirely in a crystalline form. Preferably, the support material comprises at least 95% by weight of the at least one oxide based on the total weight of the at least one oxide in a crystalline form, wherein the crystalline form is a fluoride crystalline structure. In another embodiment, the support material may contain at least one oxide based on the total weight of at least one oxide, the at least one oxide being entirely crystalline and having a fluoride crystalline structure.

[0025] It should be noted that the support material, which includes at least one ceria-based mixed oxide and is used throughout the different embodiments of the present invention, is defined by specific form, size, and / or shape characteristics and may be produced by synthesis methods known in the art, such as hydrothermal synthesis, coprecipitation, or sol-gel methods. A preferred example is cerium oxide, referred to throughout this patent application as "Ce3," which is prepared by methods known in the art and has the properties detailed in Table 1 below. Alternatively, support materials containing at least one ceria-based mixed oxide are commercially available, such as cerium oxide, reference no. AC106-011, lot no. 06-0117 (purchased from NanoScale Corporation, Cel), cerium oxide, reference no. ITQ. 3A, lot no. 0633984 (purchased from Solvay, Ce2), and cerium oxide, reference no. 544841-25G, lot no. MKCK1143 (purchased from Sigma-Aldrich, Ce4), and these commercially available ceria-based mixed oxides have the following properties summarized in Table 1:

[0026] [Table 1]

[0027] In one embodiment, the support material comprises at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide comprising at least one metal element capable of forming the ceria-based mixed oxide in less than 40 mol% (i.e., greater than 0 mol% but less than 40 mol%). The support material may also comprise at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide comprising a certain amount of at least one metal element capable of forming the ceria-based mixed oxide, the at least one metal element preferably in the range of 1 mol% to less than 40 mol%, more preferably in the range of 5 mol% to 30 mol%. The molar percentage of the at least one metal element is calculated relative to the total number of moles of the at least one ceria-based mixed oxide, meaning that if the support material to which at least one platinum group metal is added in step a) comprises multiple ceria-based mixed oxides, the molar percentage of the at least one metal element should be calculated relative to the total number of moles of the multiple ceria-based mixed oxides.

[0028] At least one element capable of forming a ceria-based mixed oxide is preferably selected from the group consisting of Zr, In, Sn, La, Pr, Nd, Gd, Y, and any combination thereof. In a preferred embodiment, at least one element capable of forming a ceria-based mixed oxide is preferably selected from the group consisting of Zr, La, Y, and any combination thereof. In another preferred embodiment, at least one element capable of forming a ceria-based mixed oxide is preferably selected from the group consisting of Zr, La, and any combination thereof.

[0029] The support material may preferably contain at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide containing at least one metal element capable of forming a ceria-based mixed oxide in less than 40 mol% (i.e., greater than 0 mol% and less than 40 mol%), the at least one metal element selected from the group consisting of Zr, In, Sn, La, Pr, Nd, Gd, Y, and any combination thereof. In another preferred embodiment, the support material may contain at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide containing at least one metal element capable of forming a ceria-based mixed oxide in preferably 1 mol% to less than 40 mol%, more preferably in the range of 5 mol% to 30 mol%, the at least one metal element selected from the group consisting of Zr, La, Y, and any combination thereof. In other preferred embodiments, the support material comprises at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide comprising an amount of at least one metal element that can form a ceria-based mixed oxide in the range of preferably 1 mol% to less than 40 mol%, more preferably 5 mol% to 30 mol%, the at least one metal element being selected from the group consisting of Zr, La, and any combination thereof. In one embodiment, the support material may contain at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide containing at least one metal element capable of forming a ceria-based mixed oxide in less than 40 mol% (i.e., greater than 0 mol% to less than 40 mol%), and the at least one metal element is or consists of Zr. Preferably, in one embodiment, the support material of the metal-supported catalyst of the present invention may contain at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide containing at least one metal element capable of forming a ceria-based mixed oxide in preferably in the range of 1 mol% to less than 40 mol%, more preferably in the range of 5 mol% to 30 mol%, and the at least one metal element is or consists of Zr. The support material may contain multiple ceria-based mixed oxides, each of which can be defined independently, as already shown in any of the embodiments described above.

[0030] In the method according to the first aspect of the present invention, the support material may have a molar ratio of surface oxygen to cerium of 0.06 to 0.20, as further measured by H2-TPR. The molar ratio of surface oxygen to cerium may preferably be 0.07 to 0.15, or more preferably 0.08 to 0.14, as measured by H2-TPR.

[0031] In a method according to a first aspect of the present invention, at least one supported transition metal (M) is used, and the molar ratio (M / O) of the surface oxygen in the supporting material is used. surf The molar ratio of surface oxygen to cerium may be 0.4 to 1.4 when determined by H2-TPR, and the H2-TPR analysis is performed on a metal-free support. In one embodiment, the support material may further have a molar ratio of surface oxygen to cerium of 0.06 to 0.20 when measured by H2-TPR, and the molar ratio of at least one supported transition metal (M) to surface oxygen may be 0.4 to 1.4 when measured by H2-TPR, and the H2-TPR analysis is performed on a metal-free support.

[0032] In a preferred embodiment, at least one supported transition metal (M) and the molar ratio (M / O) of surface oxygen in the supporting material are used. surf The molar ratio (M / O) of at least one supported transition metal (M) in the supporting material to surface oxygen may be 0.4–1.2, 0.5–1.1, or 0.5–1.0, and the H2-TPR analysis is performed on a metal-free support. In some embodiments, the molar ratio (M / O) of at least one supported transition metal (M) in the supporting material to surface oxygen is surfThe molar ratio of surface oxygen to cerium may be 0.4 to 1.4, and / or the supporting material may further have a molar ratio of surface oxygen to cerium of 0.06 to 0.20, and the molar ratio of at least one supported transition metal (M) to surface oxygen, and / or surface oxygen to cerium, is determined by H2-TPR, and the H2-TPR analysis is performed on a metal-free support.

[0033] In the method according to the first aspect of the present invention, the support material is activated under vacuum at 400°C for 3 hours and then measured by the BET method using nitrogen gas adsorption, preferably 60 to 130 m. 2 / g, 65~140m 2 / g, 50-120m 2 / g, 75-125m 2 / g, 80-130m 2 / g, 100~140m 2 / g, or 100-130m 2 This can indicate the specific surface area per gram.

[0034] In the method according to the first aspect of the present invention, the support material may preferably have an average particle size of 5 to 20 nm when measured by HRTEM, or more preferably, the support material may have an average particle size of 5 to 18 nm, 5 to 15 nm, 6 to 15 nm, 8 to 15 nm, 8 to 12 nm, or 5 to 10 nm when measured by HRTEM. Alternatively, the particle size may be measured using a field emission scanning electron microscope (FESEM).

[0035] In one embodiment, the support material used in the method according to the first aspect of the present invention may have an average particle size of 5 to 20 nm when measured by HRTEM, and 60 to 130 nm when measured by BET method using nitrogen gas adsorption after activation at 400°C for 3 hours under vacuum. 2 / g, 65~140m 2 / g, 50-120m 2 / g, 75-125m 2 / g, 80-130m 2 / g, 100~140m 2 / g, or 100-130m2 It may exhibit a specific surface area of ​​ / g. In another embodiment, the support material used in the method according to the first aspect of the present invention may have an average particle size of 5 to 18 nm when measured by HRTEM, and 60 to 130 nm when measured by BET method using nitrogen gas adsorption after activation at 400°C for 3 hours under vacuum. 2 / g, 65~140m 2 / g, 50-120m 2 / g, 75-125m 2 / g, 80-130m 2 / g, 100~140m 2 / g, or 100-130m 2 It may exhibit a specific surface area of ​​ / g. In another embodiment, the support material used in the method according to the first aspect of the present invention may have an average particle size of 5 to 15 nm when measured by HRTEM, and 60 to 130 nm when measured by BET method using nitrogen gas adsorption after activation at 400°C for 3 hours under vacuum. 2 / g, 65~140m 2 / g, 50-120m 2 / g, 75-125m 2 / g, 80-130m 2 / g, 100~140m 2 / g, or 100-130m 2 It may exhibit a specific surface area of ​​ / g. In yet another embodiment, the support material used in the method according to the first aspect of the present invention may have an average particle size of 8 to 15 nm when measured by HRTEM, and 60 to 130 nm when measured by BET method using nitrogen gas adsorption after activation at 400°C for 3 hours under vacuum. 2 / g, 65~140m 2 / g, 50-120m 2 / g, 75-125m 2 / g, 80-130m 2 / g, 100~140m 2 / g, or 100-130m 2 This can indicate the specific surface area per gram.

[0036] In other embodiments, the support material used in the method according to the first aspect of the present invention may have an average particle size of 8 to 12 nm when measured by HRTEM, and 60 to 130 nm when measured by BET method using nitrogen gas adsorption after activation at 400°C under vacuum for 3 hours. 2 / g, 65~140m 2 / g, 50-120m 2 / g, 75-125m 2 / g, 80-130m 2 / g, 100~140m 2 / g, or 100-130m 2 It may exhibit a specific surface area of ​​ / g. In further embodiments, the support material used in the method according to the first aspect of the present invention may have an average particle size of 5 to 10 nm when measured by HRTEM, and 60 to 130 nm when measured by BET method using nitrogen gas adsorption after activation at 400°C for 3 hours under vacuum. 2 / g, 65~140m 2 / g, 50-120m 2 / g, 75-125m 2 / g, 80-130m 2 / g, 100~140m 2 / g, or 100-130m 2 This can indicate the specific surface area per gram.

[0037] In step b) of the method according to the first aspect of the present invention, drying is preferably carried out under homogenizing conditions. In the context of the method according to the first aspect of the present invention, “homogenizing conditions” should be understood as conditions sufficient to ensure uniform dispersion of at least one platinum group metal on the surface of the support material and / or within the lattice of the support material, more specifically in the ceria, cerium mixed oxide, or any combination thereof contained by the support material.

[0038] In a preferred embodiment, drying step b) is carried out under homogenization conditions that include stirring, such as manual stirring (e.g., using a spatula) or stirring using a magnetic stirrer, or stirring. In another embodiment, after step a) but before step b), homogenization may be carried out by stirring, preferably by stirring, for example by manual stirring (e.g., using a spatula) or stirring using a magnetic stirrer. In yet another embodiment, after step a) but before step b), and during step b), homogenization may also be carried out by stirring, preferably by stirring, for example by manual stirring (e.g., using a spatula) or stirring using a magnetic stirrer. Drying step b) of the method is preferably carried out at a temperature of 50 to 110°C, more preferably 80 to 100°C.

[0039] In step c) of the method according to the first aspect of the present invention, according to a preferred embodiment, the solid obtained in step b) may be heat-treated (i.e., calcined) at a temperature of about 300°C to about 850°C, more preferably at a temperature of about 350°C to about 800°C. In another preferred embodiment, in step c) of the method according to the first aspect of the present invention, the solid obtained in step b) may be heat-treated at a temperature of about 400°C to about 700°C.

[0040] Where used throughout this specification in reference to a preceding number, the term “about” should be understood to disclose a specific value and to specify any value within the range defined by the number ± 5%, more preferably by the number ± 2%. For example, the expression “about 1” should be interpreted as being within the range of “0.95 to 1.05,” preferably “0.98 to 1.02.”

[0041] The method according to the first aspect of the present invention optionally involves, after step b) but before step c), the dry solid obtained in step b), - An inert substrate (e.g., a monolithic substrate or monolithic structure), preferably applied within or on a honeycomb inert substrate, or - Further steps include being formed into pellets. The choice of whether the dry solid obtained in step b) is applied within or on an inert substrate, or formed into pellets, typically depends on the requirements of the application in which the metal-supported catalyst resulting from the synthesis method according to the present invention is intended. Suitable examples of inert substrates include, but are not limited to, silica, alumina, silica-alumina, silica-magnesium, silica-zirconia, silica-tria, silica-beryllia, and silica-titania. In certain embodiments, the inert substrate includes or consists of silica, alumina, silica-alumina, silica-magnesium, silica-zirconia, silica-tria, silica-beryllia, silica-titania, or any combination thereof.

[0042] In preferred embodiments, the method according to the first aspect of the present invention may further include a step after step b) but before step c), in which the dried solid obtained in step b) is applied to or onto a honeycomb inert substrate. The honeycomb inert substrate may be a honeycomb corrugated substrate, which may preferably be a metal foil substrate, a glass fiber substrate such as a nonwoven e-glass fiber substrate, or a ceramic extruded substrate such as cordierite. As used throughout this specification, the expression “honeycomb inert substrate” should be understood to mean an inert substrate having a honeycomb lattice structure, which may be hexagonal, square, triangular, or corrugated. Preferably, the honeycomb lattice structure is hexagonal, triangular, or corrugated.

[0043] In the method according to the first aspect of the present invention, the heat-treated solid obtained from step c) may optionally be subjected to a reduction step. In particular, the heat-treated solid obtained from step c) may be subjected to a reduction step in which it comes into contact with a reducing agent, which is preferably selected from the group consisting of reducing gases (e.g., H2, or CO), hypophosphites, borohydride salts (e.g., sodium borohydride), hydrazine, formic acid, formaldehyde, citric acid, and any combination thereof. The reducing gas is preferably at a fixed temperature, usually between 100 and 600°C, to facilitate the formation of metal particles, and optionally, additional well-known reducing agent components may also be used. Examples of these reducing agent components include, but are not limited to, CO, hypophosphites, borohydride salts such as sodium borohydride, hydrazine, formic acid, formaldehyde, citric acid, or any combination thereof.

[0044] In some embodiments, the method according to the first aspect of the present invention further includes, in addition to an additional step, a step in which the dry solid obtained in step b) is applied in / on an inert substrate after step b) but before step c), and the heat-treated solid resulting from step c) may be subjected to a reduction step using a reducing agent, preferably selected from the group consisting of a reducing agent gas (e.g., H2, or CO), hypophosphate, borohydride, hydrazine, formic acid, formaldehyde, citric acid, and any combination thereof. In these particular embodiments, it will become clear that the application of the dry solid obtained in step b) in / on an inert substrate may be carried out before, after, or simultaneously with an optional reduction step.

[0045] A method according to a first aspect of the present invention further includes, optionally, a step after step b) but before step c), in which the dry solid obtained in step b) is formed into pellets, in addition to an additional step in which the heat-treated solid obtained from step c) can be subjected to a reduction step using a reducing agent, preferably selected from the group consisting of a reducing agent gas (e.g., H2 or CO)q, hypophosphite, borohydride, hydrazine, formic acid, formaldehyde, citric acid, and any combination thereof. In these particular embodiments, it will become clear that the formation of the dry solid obtained in step b) into pellets can be carried out before, after, or simultaneously with the optionally selected reduction step.

[0046] According to a second aspect of the present invention, a metal-supported catalyst for methane combustion under wet conditions, - A support material comprising at least one oxide selected from the group consisting of ceria, ceria-based mixed oxides, and any combination thereof, - Characterized by comprising at least one supported transition metal (M) selected from any of Groups 5 to 11 of the periodic table of elements, At least one oxide is substantially present in crystalline form and, when measured by HRTEM, has an average particle size of 5–20 nm. When measured by BET method using nitrogen gas adsorption after activation at 400°C under vacuum for 3 hours, it has a particle size of 50–140 nm. 2 A metal-supported catalyst exhibiting a specific surface area of ​​ / g is provided.

[0047] The supporting material for the metal-supported catalyst according to this second aspect of the present invention may preferably comprise at least one oxide selected from the group consisting of ceria, ceria-based mixed oxides, and any combination thereof, wherein at least 90% by weight of the at least one oxide is in crystalline form (i.e., up to 10% by weight of the at least one oxide may be in amorphous form based on its total weight). According to another embodiment, at least 95% by weight of the at least one oxide is provided in crystalline form (i.e., up to 5% by weight of the at least one oxide may be in amorphous form based on its total weight). In some other embodiments, the at least one oxide is entirely in crystalline form.

[0048] The support material for the metal-supported catalyst according to this second aspect of the present invention may contain at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide containing at least one metal element capable of forming the ceria-based mixed oxide in less than 40 mol% (i.e., greater than 0 mol% and less than 40 mol%). The support material may contain at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide containing a certain amount of at least one metal element capable of forming the ceria-based mixed oxide, the at least one metal element preferably in the range of 1 mol% to less than 40 mol%, more preferably in the range of 5 mol% to 30 mol%. The molar percentage of the at least one metal element is calculated relative to the number of moles of the at least one ceria-based mixed oxide, meaning that if the support material contains multiple ceria-based mixed oxides, the molar percentage of the at least one metal element should be calculated relative to the number of moles of the multiple ceria-based mixed oxides.

[0049] At least one element capable of forming a ceria-based mixed oxide is preferably selected from the group consisting of Zr, In, Sn, La, Pr, Nd, Gd, Y, and any combination thereof. In a preferred embodiment, at least one element capable of forming a ceria-based mixed oxide is preferably selected from the group consisting of Zr, La, Y, and any combination thereof. In another preferred embodiment, at least one element capable of forming a ceria-based mixed oxide is preferably selected from the group consisting of Zr, La, and any combination thereof.

[0050] The support material may preferably contain at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide containing at least one metal element capable of forming a ceria-based mixed oxide in less than 40 mol% (i.e., greater than 0 mol% and less than 40 mol%), the at least one metal element selected from the group consisting of Zr, In, Sn, La, Pr, Nd, Gd, Y, and any combination thereof. In another preferred embodiment, the support material may contain at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide containing at least one metal element capable of forming a ceria-based mixed oxide in preferably 1 mol% to less than 40 mol%, more preferably in the range of 5 mol% to 30 mol%, the at least one metal element selected from the group consisting of Zr, La, Y, and any combination thereof. In other preferred embodiments, the support material comprises at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide comprising an amount of at least one metal element that can form a ceria-based mixed oxide in the range of preferably 1 mol% to less than 40 mol%, more preferably 5 mol% to 30 mol%, the at least one metal element being selected from the group consisting of Zr, La, and any combination thereof.

[0051] In one embodiment, the support material may contain at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide containing at least one metal element capable of forming a ceria-based mixed oxide in less than 40 mol% (i.e., greater than 0 mol% to less than 40 mol%), and the at least one metal element is or consists of Zr. Preferably, in one embodiment, the support material of the metal-supported catalyst of the present invention may contain at least one ceria-based mixed oxide, the at least one ceria-based mixed oxide containing at least one metal element capable of forming a ceria-based mixed oxide in preferably in the range of 1 mol% to less than 40 mol%, more preferably in the range of 5 mol% to 30 mol%, and the at least one metal element is or consists of Zr.

[0052] In one embodiment, the support material for the metal-supported catalyst of the present invention may include a plurality of ceria-based mixed oxides, each of which can be independently defined as already shown in any of the embodiments described above.

[0053] In a preferred embodiment, the support material for the metal-supported catalyst according to the second aspect of the present invention is activated under vacuum at 400°C for 3 hours, and then measured by the BET method using nitrogen gas adsorption, yielding 60-130 m 2 / g, 65~140m 2 / g, 50-120m 2 / g, 75-125m 2 / g, 80-130m 2 / g, 100~140m 2 / g, or 100-130m 2 This can indicate the specific surface area per gram.

[0054] The support material for the metal-supported catalyst according to a second aspect of the present invention may preferably have an average particle size of 5 to 20 nm, and more preferably, the support material may have an average particle size of 5 to 18 nm, 5 to 15 nm, 6 to 15 nm, 8 to 15 nm, 8 to 12 nm, or 5 to 10 nm, as measured by HRTEM or alternatively by FESEM.

[0055] The support material of the metal-supported catalyst according to the second aspect of the present invention preferably has an average particle size in the range of 5 to 20 nm when measured by HRTEM, and when measured by the BET method using nitrogen gas adsorption after activation at 400 ° C for 3 hours under vacuum, it may exhibit a specific surface area of 50 to 140 m 2 / g, 60 to 130 m 2 / g, 65 to 140 m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g, or 80 to 130 m 2 / g. In a preferred embodiment, the support material of the metal-supported catalyst may have an average particle size in the range of 5 to 18 nm when measured by HRTEM, and when measured by the BET method using nitrogen gas adsorption after activation at 400 ° C for 3 hours under vacuum, it may exhibit a specific surface area of 50 to 140 m 2 / g, 60 to 130 m 2 / g, 65 to 140 m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g, or 80 to 130 m 2 / g. In another preferred embodiment, the support material of the metal-supported catalyst may have an average particle size in the range of 8 to 15 nm when measured by HRTEM, and when measured by the BET method using nitrogen gas adsorption after activation at 400 ° C for 3 hours under vacuum, it may exhibit a specific surface area of 50 to 140 m 2 / g, 60 to 130 m 2 / g, 65 to 14 m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g, or 80 to 130 m 2 / g. In yet another preferred embodiment, the support material of the metal-supported catalyst may have an average particle size in the range of 5 to 15 nm when measured by HRTEM, and when measured by the BET method using nitrogen gas adsorption after activation at four hundred ° C for 3 hours under vacuum, it may exhibit a specific surface area of 50 to 140 m 2 / g, 60 to 130 m 2 / g, 65 to 140 m 2 / g, 50 to 120 m2 / g, 75-125m 2 / g, or 80-130m 2 This can indicate the specific surface area per gram.

[0056] A metal-supported catalyst according to a second aspect of the present invention comprises at least one supported transition metal (M), which is preferably selected from the group consisting of Pd, Pt, Rh, Ir, Cu, Ru, Co, Ag, Nb, and any mixtures thereof. Preferably, at least one supported transition metal (M) is selected from the group consisting of Pd, Pt, Rh, Ir, Ru, and any mixtures thereof. More preferably, at least one supported transition metal (M) is selected from the group consisting of Pd, Pt, Rh, Ru, and any mixtures thereof. Even more preferably, at least one supported transition metal (M) may be selected from the group consisting of Pd, Pt, Ru, and any mixtures thereof, and even more preferably, at least one supported transition metal (M) may be Pd or Pt. In yet another embodiment, at least one supported transition metal (M) is Pd or consists of Pd.

[0057] A suitable metallic alloy for a metal-supported catalyst according to a second aspect of the present invention may contain, based on the total weight of the alloy, at least 80% by weight (i.e., 80% by weight or more) of at least one supported transition metal element, or at least 90% by weight (i.e., 90% by weight or more) of at least one supported transition metal element. In some embodiments, the metallic alloy may contain two supported transition metal elements, one of which is the main component. Examples of suitable metallic alloys, but are not limited to, Pd-Pt alloys, Pt-Au alloys, Pt-Ru alloys (e.g., Pt containing 5% by weight of Ru), and Pt-Rh alloys (e.g., Pt containing 10% by weight of Rh).

[0058] A metal-supported catalyst according to a second aspect of the present invention may be provided in the form of an extruded article or pellets (i.e., molded into pellets). Alternatively, the metal-supported catalyst may be supported on an inert substrate. Suitable examples of inert substrates include, but are not limited to, silica, alumina, silica-alumina, silica-magnesium, silica-zirconia, silica-tria, silica-beryllia, and silica-titania. In certain embodiments, the inert substrate may include or consist of silica, alumina, silica-alumina, silica-magnesium, silica-zirconia, silica-tria, silica-beryllia, silica-titania, or any combination thereof. A metal-supported catalyst according to a second aspect of the present invention may further include an inert substrate, which is preferably a honeycomb inert substrate. The honeycomb inert substrate may be a honeycomb corrugated substrate, which is preferably a metal foil substrate, or a glass fiber substrate such as a nonwoven e-glass fiber substrate, or a ceramic extruded substrate such as cordierite.

[0059] A metal-supported catalyst according to a second aspect of the present invention may preferably contain, based on the total weight of the metal-supported catalyst, at least one supported transition metal (M) in 2% by weight or more, at least one supported transition metal (M) in greater than 2% by weight, at least one supported transition metal (M) in 2% to 5% by weight, at least one supported transition metal (M) in 2.5% to 5% by weight, at least one supported transition metal (M) in 3% to 5% by weight, at least one supported transition metal (M) in 2% to 4% by weight, or at least one supported transition metal (M) in greater than 2% to 3% by weight.

[0060] In some embodiments, the metal-supported catalyst according to a second aspect of the present invention may include, as a metallic alloy, at least one supported transition metal (M), and the provision of multiple supported transition metals (M) can advantageously boost catalytic activity at low intermediate temperatures. In those embodiments, the metal-supported catalyst according to a second aspect of the present invention may preferably include, as a metallic alloy, 2% by weight or more of at least one supported transition metal (M) based on the total weight of the metal-supported catalyst, or, based on the total weight of the metal-supported catalyst, at least one supported transition metal (M) in amounts of more than 2% by weight, more than 2% by weight to 5% by weight, 2.5% by weight to 5% by weight, more than 2% by weight to more than 4% by weight, or more than 2% by weight to 3% by weight.

[0061] In a preferred embodiment according to a second aspect of the present invention, the metal-supported catalyst is obtainable or acquired by the method according to the first aspect of the present invention.

[0062] In a third aspect of the present invention, a method for burning methane under wet conditions, the method comprising the following steps: a) The step of introducing a metal-supported catalyst into a reactor, as defined by a second aspect of the present invention, b) A step of supplying a gas reaction feed to a reactor, the feed comprising methane, 5% to 15% (v / v) of water, and at least one inert gas, wherein the sum of all components in the gas reaction feed is 100% (v / v), c) A method is provided which allows the metal-supported catalyst to remain in contact with the gaseous reaction feed in the reactor for a sufficient time and at a sufficient temperature for methane combustion to occur.

[0063] In the context of the present invention, the expression “reaction feed” refers to the gas flow supplied to the combustion reactor. The gas flow may preferably consist of methane, 0.5 to 30 volume percent of water, and the remaining amount added up to 100 volume percent, which includes at least one inert gas such as nitrogen, and optionally may include other gas components such as NO, NO2, CO, CO2, and / or O2. More preferably, the gas flow may consist of methane (e.g., 0.01 to 0.2 volume percent of methane corresponding to 100 to 2000 ppm of methane), 5 to 15 volume percent of water, and the remaining amount added up to 100 volume percent, which includes at least one inert gas such as nitrogen, and optionally may include other gas components such as NO, NO2, CO, CO2, and / or O2.

[0064] In some embodiments, a method according to a third aspect of the present invention may further include, prior to step a), subjecting the metal-supported catalyst to a reduction step using a reducing agent selected from the group consisting of reducing agent gases, hypophosphites, borohydride salts, hydrazine, formic acid, formaldehyde, citric acid, and any combination thereof. If the reduction step is carried out, the method may optionally subsequently include an oxidation step, which may be carried out before, simultaneously with, or after step a).

[0065] A fourth aspect of the present invention provides the use of a metal-supported catalyst according to the second aspect of the present invention in methane combustion, preferably in methane combustion under wet conditions. Throughout the description and claims, the term “including” and its variations are not intended to exclude any other technical features, components, or steps. Additional advantages and features of the present invention may become apparent to those skilled in the art in consideration of the description or may be learned through practice of the invention without undue burden. [Examples]

[0066] The following embodiments are provided for illustrative purposes only and should not be construed as limiting the invention. Numerous modifications are possible, and it should be understood that the invention may be carried out in ways other than those specifically described in the following embodiments, within the scope of the appended claims.

[0067] In the examples provided below, the Brunauer-Emmett-Teller (BET) values ​​of the corresponding samples were calculated from the N2 isotherm at 77K on a volumetric Micromeritics ASAP® 2020 analyzer after activation at 400°C under vacuum for 3 hours. High-resolution transmission electron microscopy (HRTEM) analysis was performed using a 200kV JEOL model JEM2100F microscope.

[0068] The H2-TPR profile was obtained using an Autochem 2910 equipped with a thermal conductivity detector (TCD) under the following conditions: 50 mg of solid (particle size: 0.2-0.4 mm) was placed in a quartz tube and maintained in Ar (50 ml / min) at room temperature for 15 minutes, then reduced in a flow of 10% H2 / Ar (50 ml / min) mixture to 800°C at a heating rate of 10°C / min. Surface oxygen (O) expression of the supporting material surf ) is defined and quantified from the H2-TPR profile obtained according to previous experimental considerations, taking into account the H2 consumption of the first reduction peak (250-550°C).

[0069] Unless otherwise indicated, in each of the catalyst performance tests provided below, 50 mg of pelletized catalyst sample was diluted with 1.5 g of pelletized silicon carbide before use in each methane combustion reaction.

[0070] Furthermore, all methane combustion reactions were carried out independently in fixed-bed, quartz tubular reactors with a diameter of 1.2 cm and a length of 53 cm. 100 mL / min of air was passed through a water saturator and heated to 46°C. The resulting saturated air stream was mixed with a 3,000 ppm methane stream diluted with 50 mL / min of N2.

[0071] Furthermore, unless otherwise indicated, the following specific feed conditions were used in each catalyst test case. - Methane combustion reaction under dry conditions: 0.1 vol% CH4, and 14.0 vol% O2 in N2; total flow rate 150 mL / min, and GHSV = 180,000 mL / g cat ·h (GHSV = gas hourly space velocity), - Methane combustion reaction under wet conditions: 0.1 vol% CH4, 14.0 vol% O2, and 6.1 vol% H2O in N2; total flow rate 150 mL / min, and GHSV = 180,000 mL / g cat ·h.

[0072] Example 1 - Synthesis of an exemplary 3 wt% Pd-containing Ce2 metal-supported catalyst (Pd / O surf = 0.56) An exemplary metal-supported catalyst according to the present invention containing 3 wt% palladium as the supported platinum group metal was prepared as follows according to the method of the present invention: Commercially available ceria (see Ce2 in Table 1) was considered for preparing this metal-supported catalyst. Ce2 is commercially available ceria (purchased from Solvay, reference ITQ. 3A, lot number 0633984), which has an average particle size of 7 - 9 nm (see the HRTEM image of Ce2 in Figure 1), a BET surface area of 98 m 2 / g, and a measured molar ratio of surface oxygen to cerium of 0.087 (obtained from H2-TPR, see Ce2 in Figure 2).

[0073] 0.85 g of tetraamminepalladium(II) nitrate solution (10 wt% H2O solution, purchased from Merck, CAS 13601 - 08 - 6) was mixed with 50 mg of Milli-Q water. Then, the resulting solution was dropped onto 1 g of the Ce2 support (previously deposited in a flat-bottomed porcelain crucible) using a syringe. Next, homogenization was carried out manually using a spatula. Then, the wet solid and the flat-bottomed porcelain crucible were placed on a hot plate and dried at 100 °C. During this drying process, the wet solid was continuously homogenized with a spatula every minute until it was completely dry.

[0074] For this metal support, Pd / O surf The parameter was 0.56, which was estimated considering both the incorporated Pd amount (3 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.087 (obtained from H2-TPR; see Ce2 in Figure 2).

[0075] Next, the obtained dry solid was pelletized using a 4-bar manual hydraulic press (pellet size: 0.2-0.4 mm). Then, heat treatment (i.e., calcination) was carried out using a vertical fluidized bed reactor, and 150 mg of the obtained pelletized 3 wt% Pd-containing Ce2 material was calcined at 650°C for 4 hours with an airflow of 175 mL / min (heating gradient 2°C / min). Finally, the sample was cooled in an airflow. The BET surface area measured by N2 adsorption was approximately 93 m². 2 The particle size was / g. The average particle size of 8-10 nm was measured using HRTEM.

[0076] Example 2 - Exemplary 3 wt% Pd-containing Ce3 metal-supported catalyst (Pd / O surf Synthesis of (=0.58) An exemplary metal-supported catalyst according to the present invention, containing 3% by weight of palladium as the supported platinum group metal, was prepared according to the method of the present invention as follows: Specific cerium oxides (see Ce3 in Table 1), prepared according to methods known in the art, were considered for the preparation of this metal-supported catalyst. Ce3 had an average particle size of 6–8 nm (see HRTEM image of Ce3 in Figure 1) and 120 m 2 This represents the BET surface area per gram and the measured molar ratio of surface oxygen to cerium (obtained from H2-TPR; see Ce3 in Figure 2) of 0.083.

[0077] 0.85 g of tetraamminepalladium(II) nitrate solution (10 wt% H2O solution, purchased from Merck, CAS 13601-08-6) was mixed with 50 mg of Milli-Q water. The resulting solution was then added dropwise to 1 g of Ce3 support (previously deposited in a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The wet solid and the flat-bottomed porcelain crucible were then placed on a hot plate and dried at 100°C. During the drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0078] For this metal support, Pd / O surf The parameter was 0.58, which was estimated considering the incorporated Pd amount (3 wt% Pd) and the previously measured surface oxygen-to-cerium molar ratio of 0.083 (obtained from H2-TPR; see Ce3 in Figure 2).

[0079] Next, the obtained dry solid was pelletized using a 4-bar manual hydraulic press (pellet size: 0.2-0.4 mm). Then, heat treatment (i.e., calcination) was carried out using a vertical fluidized bed reactor. 150 mg of the resulting pelletized 3 wt% Pd-containing Ce3 material was calcined at 650°C for 4 hours with an airflow of 175 mL / min (heating gradient 2°C / min). Finally, the sample was cooled in an airflow.

[0080] Example 3 - Comparative 3 wt% Pd-containing Cel metal-supported catalyst (Pd / O surf Synthesis of (=0.35) A comparative metal-supported catalyst containing 3% by weight of palladium as the supported platinum group metal was prepared according to the method of the present invention as follows: Commercially available ceria (see Cel in Table 1) was considered for the preparation of this metal-supported catalyst. Cel is a commercially available ceria (purchased from NanoScale Corporation, reference AC106-011, lot number 06-0117) with an average particle size of 5-7 nm (see HRTEM image of Cel in Figure 1) and 73 m 2The BET surface area per gram and the measured molar ratio of surface oxygen to cerium (0.139, obtained from H2-TPR; see Cel in Figure 2) are shown.

[0081] 0.85 g of tetraamminepalladium(II) nitrate solution (10 wt% H2O solution, purchased from Merck, CAS 13601-08-6) was mixed with 50 mg of Milli-Q water. The resulting solution was then added dropwise to 1 g of Cel support (previously deposited in a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The wet solid and the flat-bottomed porcelain crucible were then placed on a hot plate and dried at 100°C. During the drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0082] For this metal support, Pd / O surf The parameter was 0.35, which was estimated considering the incorporated Pd amount (3 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.139 (obtained from H2-TPR, see Cel in Figure 2).

[0083] Next, the obtained dry solid was pelletized using a 4-bar manual hydraulic press (pellet size: 0.2-0.4 mm). Then, heat treatment (i.e., calcination) was carried out using a vertical fluidized bed reactor, and 150 mg of the obtained pelletized 3 wt% Pd-containing Cel material was calcined at 650°C for 4 hours with an airflow of 175 mL / min (heating gradient 2°C / min). Finally, the sample was cooled in an airflow.

[0084] Example 4 - Comparative 3 wt% Pd-containing Ce4 metal-supported catalyst (Pd / O surf Synthesis of (=0.86) A comparative metal-supported catalyst containing 3% by weight of palladium as the supported platinum group metal was prepared according to the method of the present invention as follows: Commercially available ceria (see Ce4 in Table 1) is considered for the preparation of this metal-supported catalyst. Ce4 is a commercially available ceria (purchased from Sigma-Aldrich, reference number 544841-25G, lot number MKCK1143) with an average particle size of 20-30 nm (see HRTEM image of Ce4 in Figure 1), and 40 m 2 The BET surface area per gram and the measured molar ratio of surface oxygen to cerium (obtained from H2-TPR; see Ce4 in Figure 2) are shown.

[0085] 0.85 g of tetraamminepalladium(II) nitrate solution (10 wt% H2O solution, purchased from Merck, CAS 13601-08-6) was mixed with 50 mg of Milli-Q water. The resulting solution was then added dropwise to 1 g of Ce4 support (previously deposited in a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The wet solid and the flat-bottomed porcelain crucible were then placed on a hot plate and dried at 100°C. During the drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0086] For this metal support, Pd / O surf The parameter was 0.86, which was estimated considering the incorporated Pd amount (3 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.056 (obtained from H2-TPR, see Ce4 in Figure 2).

[0087] Next, the obtained dry solid was pelletized using a 4-bar manual hydraulic press (pellet size: 0.2-0.4 mm). Then, heat treatment (i.e., calcination) was carried out using a vertical fluidized bed reactor, and 150 mg of the obtained pelletized 3 wt% Pd-containing Ce4 material was calcined at 650°C for 4 hours with an airflow of 175 mL / min (heating gradient 2°C / min). Finally, the sample was cooled in an airflow.

[0088] Example 5 - Exemplary 5 wt% Pd-containing Ce2 metal-supported catalyst (Pd / Osurf Synthesis of (=0.93) An exemplary metal-supported catalyst according to the present invention, containing 5% by weight of palladium as the supported platinum group metal, was prepared as follows according to the method of the present invention.

[0089] Commercially available ceria (see Ce2 in Table 1) is considered for the preparation of this metal-supported catalyst. Ce2 is a commercially available ceria (purchased from Solvay, see ITQ 3A, lot number 0633984) with an average particle size of 7-9 nm (see HRTEM image of Ce2 in Figure 1) and 98 m 2 The BET surface area per gram and the measured molar ratio of surface oxygen to cerium (obtained from H2-TPR; see Ce2 in Figure 2) are shown.

[0090] 1.4 g of tetraamminepalladium(II) nitrate solution (10 wt% H2O solution, purchased from Merck, CAS 13601-08-6) was added dropwise to 1 g of Ce2 support (previously deposited in a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The wet solid and the flat-bottomed porcelain crucible were then placed on a hot plate and dried at 100°C. During the drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0091] For this metal support, Pd / O surf The parameter was 0.93, which was estimated considering the incorporated Pd amount (5 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.087 (obtained from H2-TPR, see Ce2 in Figure 2).

[0092] Next, the obtained dry solid was pelletized using a 4-bar manual hydraulic press (pellet size: 0.2-0.4 mm). Then, heat treatment (i.e., calcination) was carried out using a vertical fluidized bed reactor, and 150 mg of the obtained pelletized 5 wt% Pd-containing Ce2 material was calcined at 650°C for 4 hours with an airflow of 175 mL / min (heating gradient 2°C / min). Finally, the sample was cooled in an airflow.

[0093] Example 6 - Comparative 1 wt% Pd-containing Ce2 metal-supported catalyst (Pd / O surf Synthesis of (=0.19) A comparative metal-supported catalyst according to the present invention, containing 5% by weight of palladium as the supported platinum group metal, was prepared according to the method of the present invention as follows: Commercially available ceria (see Ce2 in Table 1) is considered for the preparation of this metal-supported catalyst. Ce2 is a commercially available ceria (purchased from Solvay, see ITQ 3A, lot number 0633984) with an average particle size of 7-9 nm (see HRTEM image of Ce2 in Figure 1) and 98 m 2 The BET surface area per gram and the measured molar ratio of surface oxygen to cerium (obtained from H2-TPR; see Ce2 in Figure 2) are shown.

[0094] 2.28 g of tetraamminepalladium(II) nitrate solution (10 wt% solution, in H2O, purchased from Merck, CAS 13601-08-6) was mixed with 0.62 g of Milli-Q water. The resulting solution was then added dropwise to 1 g of Ce2 support (previously deposited in a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula.

[0095] Subsequently, the wet solid and a flat-bottomed porcelain crucible were placed on a hot plate and dried at 100°C. During the drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0096] For this metal support, Pd / O surfThe parameter was 0.19, which was estimated considering the incorporated Pd amount (1 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.087 (obtained from H2-TPR; see Ce2 in Figure 2).

[0097] Next, the obtained dry solid was pelletized using a 4-bar manual hydraulic press (pellet size: 0.2-0.4 mm). Then, heat treatment (i.e., calcination) was carried out using a vertical fluidized bed reactor, and 150 mg of the obtained pelletized 1 wt% Pd-containing Ce2 material was calcined at 650°C for 4 hours with an airflow of 175 mL / min (heating gradient 2°C / min). Finally, the sample was cooled in an airflow.

[0098] Example 7 - Exemplary 5 wt% Pd-containing cell metal-supported catalyst (Pd / O surf Synthesis of (=0.58) A comparative metal-supported catalyst containing 5% by weight of palladium as the supported platinum group metal was prepared according to the method of the present invention as follows: Commercially available ceria (see Cel in Table 1) was considered for the preparation of this metal-supported catalyst. Cel is a commercially available ceria (purchased from NanoScale Corporation, reference AC106-011, lot number 06-0117) with an average particle size of 5-7 nm (see HRTEM image of Cel in Figure 1) and 73 m 2 The BET surface area per gram and the measured molar ratio of surface oxygen to cerium (0.139, obtained from H2-TPR; see Cel in Figure 2) are shown.

[0099] 1.4 g of tetraamminepalladium(II) nitrate solution (10 wt% H2O solution, purchased from Merck, CAS 13601-08-6) was added dropwise to 1 g of Cel support (previously deposited in a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The wet solid and the flat-bottomed porcelain crucible were then placed on a hot plate and dried at 100°C. During the drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0100] Regarding this metal support, Pd / O surf The parameter was 0.58, which was estimated considering the incorporated Pd amount (5 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.139 (obtained from H2-TPR, see Cel in Figure 2).

[0101] Next, the obtained dry solid was pelletized using a 4-bar manual hydraulic press (pellet size: 0.2-0.4 mm). Then, heat treatment (i.e., calcination) was carried out using a vertical fluidized bed reactor, and 150 mg of the obtained pelletized 5 wt% Pd-containing Cel material was calcined at 650°C for 4 hours with an airflow of 175 mL / min (heating gradient 2°C / min). Finally, the sample was cooled in an airflow.

[0102] Example 8 - Synthesis of exemplary PdPt-containing Ce2 metal-supported catalyst (Pd / O surf Synthesis of (=0.66) An exemplary metal-supported catalyst according to the present invention, containing 3 wt% palladium and 1 wt% platinum as the supported platinum-based metal, was prepared according to the method of the present invention as follows: Commercially available ceria (see Ce2 in Table 1) is considered for the preparation of this metal-supported catalyst. Ce2 is a commercially available ceria (purchased from Solvay, see ITQ. 3A, lot number 0633984) with an average particle size of 7-9 nm (see HRTEM image of Ce2 in Figure 1) and 98 m 2 The BET surface area per gram and the measured molar ratio of surface oxygen to cerium (0.087, obtained from H2-TPR; see Ce2 in Figure 2) are shown.

[0103] 0.85 g of tetraamminepalladium(II) nitrate solution (10 wt% H2O solution, purchased from Merck, CAS 13601-08-6) and 0.02 g of tetraammineplatinum(II) nitrate (purchased from Sigma-Aldrich, CAS nr.20634-12-2) were mixed. The resulting solution was then dropped onto 1 g of Ce2 support (previously deposited in a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The wet solid and the flat-bottomed porcelain crucible were then placed on a hot plate and dried at 100°C. During the drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0104] For this metal carrier, (RdPt) / O surf The parameter was 0.66, which was estimated considering both the incorporated Pd and Pt amounts (3 wt% Pd and 1 wt% Pt), and the previously measured surface oxygen to cerium molar ratio of 0.087 (obtained from H2-TPR, see Ce2 in Figure 2).

[0105] Next, the obtained dry solid was pelletized using a 4-bar manual hydraulic press (pellet size: 0.2-0.4 mm). Subsequently, heat treatment (i.e., calcination) was carried out using a vertical fluidized bed reactor, and 150 mg of the obtained pelletized 3 wt% Pd and 1 wt% Pt-containing Ce2 material was then calcined at 650°C for 4 hours with an airflow of 175 mL / min (heating gradient 2°C / min). Finally, the sample was cooled in an airflow.

[0106] Example 9 - Exemplary 5 wt% Pd-containing CeZr metal-supported catalyst (Pd / O surf Synthesis of (=0.56) An exemplary metal-supported catalyst according to the present invention, containing 5% by weight of palladium as the supported platinum group metal, was prepared according to the method of the present invention as follows: Dissolve 66 g of ammonium hydroxide solution (NH4OH, 25% NH3 in H2O, Sigma-Aldrich) in 134 mL of Milli-Q water. Then, add 10.42 g of cerium nitrate (Ce(NO3)36H2O, Alfa-Aesar) and 1.29 g of zirconium(IV) oxynitrate (ZrONO3, Sigma-Aldrich), and stir the resulting mixture for 30 minutes. In parallel, dilute 6 g of hydrogen peroxide solution (50% by weight in H2O, Sigma-Aldrich) with 24 g of Milli-Q water. Then, add this H2O2 solution dropwise to the previous mixture, and maintain the mixture while stirring for 45 minutes. After that, wash the mixture and separate it by filtering several times with water, and then dry it overnight at 100°C. The obtained solid is introduced into 300 ml of isopropanol, and the mixture is maintained at 100°C for 5 hours under reflux and stirring conditions. The solid is recovered by filtration, washed with water, and finally calcined in a muffle at 500°C for 4 hours (heating gradient 2°C / min).

[0107] The resulting CeZr support had an average particle size of 6-10 nm and 79 m². 2 The BET surface area per gram and the measured molar ratio of surface oxygen to CeZr (0.135) are shown (obtained from H2-TPR). 4.4 g of tetraamminepalladium(II) nitrate solution (10 wt% solution in H2O, purchased from Merck, CAS 13601-08-6) was added dropwise to 1 g of CeZr support (previously deposited in a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The wet solid and the flat-bottomed porcelain crucible were then placed on a hot plate and dried at 100°C. During the drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0108] For this metal support, Pd / O surf The parameter was 0.56, which was estimated considering the incorporated amount of Pd (5 wt% Pd) and the previously measured molar ratio of surface oxygen to CeZr (obtained from H2-TPR) of 0.135.

[0109] Next, the obtained dry solid was pelletized using a 4-bar manual hydraulic press (pellet size: 0.2-0.4 mm). Then, heat treatment (i.e., calcination) was carried out using a vertical fluidized bed reactor, and 150 mg of the obtained pelletized 5 wt% Pd-containing CeZr material was calcined at 650°C for 4 hours with an airflow of 175 mL / min (heating gradient 2°C / min). Finally, the sample was cooled in an airflow.

[0110] Example 10 - Catalyst evaluation of 3 wt% Pd / nanoceria material using different nanoceria supports (Examples 1-4) The resulting 3 wt% Pd-containing nanoceria catalyst was tested for methane combustion reactions under humid conditions at different reaction temperatures according to classical light-off curve experiments (200–600°C, Figure 3). For the light-off experiment, the catalyst was first activated with air (100 ml / min) for 1 hour. Then, the feed mixture under humid conditions was fed with an overall flow rate of 150 ml / min, and the following composition (in N2, 0.1 vol. % CH4, 14.0 vol. % O2, 6 vol. % H2O, GHSV = 18000 ml / g) was used. cat The reaction was carried out in stepwise steps from 200 to 600°C. Methane combustion activity was measured at each temperature under steady-state conditions by gas chromatography (Agilent Technologies 7890B.GC system with TCD detector, using SP2100 pre-column, PLOTQ, and Molsieve 5A capillary column).

[0111] The catalysts synthesized according to Examples 1 and 2 of the present invention were found to function better for methane combustion reactions under wet conditions compared to the comparative catalysts prepared according to Examples 3 and 4 of the present invention (see Figure 3). Both catalysts had a Pd / O ratio of approximately 0.56–0.58. surf Note that the parameters and the values ​​of the particle size (6-9 nm) and BET surface area (90-120 m² / g) are shown. The catalyst prepared according to Example 3 is Pd / O surfThe parameter showed a lower value of approximately 0.35, while the catalyst prepared according to Example 4 showed a Pd / O ratio of approximately 0.35. surf The parameter shows a higher value of approximately 0.86, but its particle size is over 20 nm and its BET surface area is 50 m². 2 It is less than / g.

[0112] In addition to light-off type experiments at different temperatures, the long-term stability of these catalysts was also evaluated under dynamic high-temperature conditions (400-600°C) during time-on-stream (TOS) exposure to a wet feed. In the long steady-state TOS experiment, the catalyst was first activated with air (100 ml / min) for 1 hour, and then activated under dry conditions (150 ml / min, in N2, 0.1 vol% CH4, 14.0 vol% O2, GHSV = 180,000 ml / g). cat •h) The feed mixture was activated, and the reaction temperature was raised to 400°C using a heating lamp at approximately 14°C / min, and maintained at 400°C for 1 hour under dry conditions. At this point, the feed was prepared under wet conditions (in N2, 0.1 vol. %CH4, 14.0 vol. %O2, 6 vol. %H2O, GHSV = 180,000 ml / g). cat The reaction temperature was changed to (h) and maintained for approximately 40 hours. Subsequently, dynamic high-temperature fluctuations were studied by raising the reaction temperature to 600°C for 1 hour, then lowering it to 400°C, and maintaining it for another hour under humid conditions. Methane conversion was measured by gas chromatography (Agilent Technologies 7890B.GC system with TCD detector, using SP2100 pre-column, PLOTQ, and Molsieve 5A capillary column).

[0113] Two catalysts that function better for long steady-state TOS at 400°C under humid conditions were prepared according to Examples 1 and 2, as previously obtained in light-off experiments. Both catalysts showed virtually no change in methane conversion values ​​not only after 40 hours under humid conditions at 400°C (see Examples 1 and 2 in Section (I) of Figure 4), but also after being subjected to dynamic high-temperature fluctuations of 400–600°C (see Examples 1 and 2 in Section (III) of Figure 4). These results clearly highlight the excellent activity and stability provided by these two 3 wt% Pd-containing catalysts, and the nanoceria have a particle size of 6–9 nm and 90–120 nm. 2 BET surface area / g, and Pd / O surf I support a value of approximately 0.6.

[0114] Example 11 - Catalyst evaluation of different metal contents in Ce2 support (Examples 1, 5, and 6) To observe the effect of metal content, different amounts of Pd (i.e., 1 wt% from Example 6, 3 wt% from Example 1, and 5 wt% from Example 5) were deposited onto a Ce2 support, followed by a simple activation treatment in air at 650°C. Pd / O surf The parameters were calculated for the three catalysts, and the following values ​​were obtained: 0.19 (1 wt% Pd, Example 6), 0.56 (3 wt% Pd, Example 1), and 0.93 (5 wt%, Example 5).

[0115] These three catalysts were first tested under humid conditions, following classical light-off type experiments (see Example 10 for details of the light-off type reaction tests).

[0116] Increasing the amount of Pd in ​​the catalyst resulted in an enhancement of the methane conversion profile (see Figure 5). Interestingly, the most significant differences were observed when these catalysts were evaluated for long TOS under wet feed and dynamic high-temperature reaction conditions (see Example 10 for experimental details regarding steady-state long TOS experiments). As shown in Figure 6, the two catalysts (with 3% and 5% Pd content) prepared according to Examples 1 and 5 showed similar catalytic performance at 400°C and under wet conditions as well as during short light-off type experiments at 400°C (see Figure 5). Furthermore, both catalysts showed methane conversion values ​​that remained almost unchanged not only after 40 hours under wet conditions at 400°C (see Section (I) in Figure 6), but also after being subjected to dynamic high-temperature fluctuations from 400 to 600°C (see Section (III) in Figure 6). The calculated turnover frequency (TOF, methane conversion normalized by metal content) values ​​calculated for both catalysts prepared according to Examples 1 and 5 of the present invention were 8.4 and 9.6 h. 1 It was found that the TOF value calculated from a long TOS experiment after 2000 minutes was low (0.4h). These results clearly highlight the excellent activity and stability provided by this nanoceria support, even when the metal loading was increased to 5 wt%. However, the 1 wt% Pd-containing nanoceria showed only slight methane conversion after being maintained for a long TOS period at 400°C in the presence of vapor (see Example 6 in Section (I) of Figure 6). In fact, the TOF value calculated for this catalyst after 2000 minutes was low (0.4h). 1 ), with an average particle size of 7-9 nm and a BET surface area of ​​97 m². 2 Even with nanoceria supports at / g, low Pd / O surf The negative role of the ratio (-0.2) was emphasized.

[0117] Example 12 - Catalyst evaluation of different metal contents in Cel support (Examples 3 and 7) To observe the effect of metal content on additional nanoceria supports having higher measured surface oxygen species, Cel (see Table 1), different amounts of Pd (i.e., 3 wt% from Example 3 and 5 wt% from Example 7) were deposited on these supports, followed by a simple activation treatment in air at 650°C. Pd / O surf The parameters were calculated for the two catalysts, and the following values ​​were obtained: 0.35 (3 wt%, Example 3) and 0.58 (5 wt%, Example 7).

[0118] As shown in Figure 7, the methane conversion achieved by the catalyst prepared according to Example 7 was particularly high compared to the catalyst prepared according to Example 3 when tested for long TOS type experiments under wet conditions and dynamic high temperature fluctuations (see details of the steady-state long TOS experiment in Example 10). For the catalyst prepared according to Example 7 of the present invention, the calculated TOF value after a reaction at 400°C for 2000 minutes and under wet conditions was approximately 7.0 h. 1 And under the same conditions, approximately 8.4 hours 1 The calculated TOF for the catalyst prepared according to Example 1 is a value close to the Pd / O value, and both catalysts have similar Pd / O surf The ratio is approximately 0.56 to 0.58. Another important conclusion from the catalytic results obtained when the catalyst prepared according to Example 7 was tested under long TOS conditions is that this catalyst exhibits excellent stability after being subjected to dynamic high-temperature fluctuations (400-600-400°C) under humid conditions (see Example 7 in section (III) of Figure 7).

[0119] Example 13 - Catalytic evaluation of PdPt in Ce2 support (Example 8) The methane conversion for long TOS type experiments under wet conditions (see experimental details of the steady-state long TOS in Example 10), achieved by the bimetallic catalyst prepared according to Example 8 of the present invention, exhibits not only excellent stability (see Figure 8) but also catalytic performance similar to that of the catalyst prepared according to Example 1 after 40 hours of reaction.

[0120] Example 14 - Catalytic evaluation of Pd in ​​a CeZr support (Example 9) Methane conversion for long TOS-type experiments under humid conditions (see experimental details for steady-state long TOS in Example 10) was achieved by preparing a CeZr catalyst containing 5 wt% Pd according to Example 9, which showed excellent stability after 40 hours of reaction (see Figure 8), and similar Pd content and Pd / O surf Ratio, it exhibits catalytic performance similar to that of the catalyst prepared according to Example 7.

Claims

1. A method for obtaining a metal-supported catalyst, wherein the method comprises the following steps: a) A step of adding at least one supported transition metal (M) selected from any of Groups 5 to 11 of the periodic table of elements to a support material, wherein the support material includes at least one oxide selected from the group consisting of ceria, ceria-based mixed oxides, and any combination thereof. b) Preferably, the step of drying under homogenizing conditions, c) The solid obtained in step b) is heat-treated at a temperature of approximately 250°C to approximately 850°C, and is characterized by comprising these steps. The at least one oxide, when substantially present in crystalline form and determined by HRTEM, has an average particle size of 5–20 nm, and when measured by BET method using nitrogen gas adsorption after activation at 400°C under vacuum for 3 hours, it has a particle size of 50–140 nm. ２ The specific surface area per g is shown. The molar ratio (M / O) of the at least one supported transition metal (M) to the surface oxygen in the supporting material ｓｕｒｆ ) but H ２ - A method where the value is 0.4 to 1.4, as determined by TPR.

2. The method according to claim 1, wherein the at least one oxide has a molar ratio of surface oxygen to cerium of 0.05 to 0.20 when measured by H2-TPR.

3. The method according to claim 2, wherein the addition of the at least one supported transition metal (M) to the support material is carried out by wet impregnation, initial volume impregnation, or deposition precipitation.

4. The method according to claim 1, wherein the at least one supported transition metal (M) is selected from the group consisting of Pd, Pt, Rh, Cu, Ru, Co, Ag, Nb, and any mixture thereof.

5. The method according to claim 1, wherein the at least one supported transition metal (M) is added in step a) in the form of a metal salt, a metal composite, or a metallic alloy.

6. The method according to claim 1, wherein the support material comprises at least one ceria-based mixed oxide, and the at least one ceria-based mixed oxide comprises at least one metal element in less than 40 mol% of a certain amount, capable of forming the ceria-based mixed oxide.

7. The method according to claim 6, wherein the at least one metal element capable of forming a ceria-based mixed oxide is selected from the group consisting of Zr, In, Sn, La, Pr, Nd, Gd, Y, and any combination thereof.

8. The above method is performed after step b), but before step c), the dried solid obtained in step b) - Inert substrate, preferably applied within or on a honeycomb inert substrate, The method according to claim 1, further comprising the step of being formed into pellets.

9. The method according to claim 1, wherein the heat-treated solid resulting from step c) is subjected to a reduction step in which it comes into contact with a reducing agent selected from the group consisting of reducing gases, hypophosphates, boron hydride, salts, hydrazine, formic acid, formaldehyde, citric acid, and any combination thereof.

10. A metal-supported catalyst for methane combustion under wet conditions, wherein: - A support material comprising at least one oxide selected from the group consisting of ceria, ceria-based mixed oxides, and any combination thereof, - Characterized by comprising at least one supported transfer metal (M) selected from any of Groups 5 to 11 of the periodic table of the aforementioned elements, The at least one oxide, when substantially present in crystalline form and determined by HRTEM, has an average particle size of 5 to 20 nm, and when measured by BET method using nitrogen gas adsorption after activation at 400°C under vacuum for 3 hours, it has a particle size of 50 to 140 nm. ２ The specific surface area per g is shown. A metal-supported catalyst comprising more than 2% by weight of the at least one supported transition metal (M) based on the total weight of the metal-supported catalyst.

11. A metal-supported catalyst according to claim 10, which can be obtained by the method described in any one of claims 1 to 9.

12. A method for burning methane under humid conditions, comprising the following steps: a) The step of introducing the metal-supported catalyst defined in claim 10 into a reactor, b) A step of supplying a gas reaction feed to a reactor, the feed comprising methane, 5% to 15% (v / v) of water, and at least one inert gas, wherein the sum of all components in the gas reaction feed is 100% (v / v), c) A method comprising the step of enabling the metal-supported catalyst to remain in contact with the gas reaction feed in the reactor for a sufficient time and at a sufficient temperature for methane combustion to occur.

13. The method according to claim 12, further comprising, before step a), subjecting the metal-supported catalyst to a reduction step using a reducing agent selected from the group consisting of reducing gases, hypophosphates, borohydride salts, hydrazine, formic acid, formaldehyde, citric acid, and any combination thereof.

14. The method according to claim 13, wherein the metal-supported catalyst is subjected to the reduction step, and then to the oxidation step, and the oxidation step is performed before step b), and before, simultaneously with, or after step a).

15. Use of a metal-supported catalyst as defined in claim 10 in methane combustion, preferably in methane combustion under wet conditions.

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