Metal supported catalyst for methane combustion under wet conditions, preparation method and application thereof

Abstract

The present invention relates to a process for obtaining metal supported catalysts, as well as the metal supported catalysts themselves, for methane combustion under wet conditions. The invention also relates to the use of said metal supported catalyst in methane combustion, preferably in methane combustion under wet conditions. Furthermore, the invention relates to a process for the combustion of methane under wet conditions, which involves the use of the metal supported catalyst according to the invention.

Description

Technical Field

[0001] This invention relates to a method for obtaining a metal-supported catalyst, and the metal-supported catalyst itself, which is particularly suitable for methane combustion under wet conditions. The invention also relates to the use of said metal-supported catalyst in methane combustion, preferably in methane combustion under wet conditions. Furthermore, the invention relates to a method for methane combustion under wet conditions, which relates to the use of a metal-supported catalyst according to the invention. Background Technology

[0002] A significant source of methane emissions comes from large stationary natural gas engines used for power generation and marine applications. Furthermore, more methane will be generated as more traditional fossil fuels are replaced by sustainable energy sources such as natural gas, which contains over 90% methane. However, methane is a potent greenhouse gas with a global warming potential approximately 28 times that of CO2.

[0003] Therefore, it is absolutely necessary to find an efficient way to manage these amounts of methane, and in this context, methane oxidation becomes particularly relevant. However, a major drawback of platinum group metal-based methane oxidation catalysts (MOCs) is their lack of stability in gas streams containing methane and water.

[0004] Pd / Al₂O₃-based methane oxidation catalyst solutions have long been a focus of attention, but despite numerous studies, there remains a pressing need for methane oxidation catalysts that remain stable in the presence of water. Deactivation is typically attributed to Pd sintering, water adsorption, hydroxyl formation, and sulfate formation when sulfur is present in the gas stream.

[0005] Furthermore, in order to be successfully applied to methane combustion catalysis, the catalytic system must operate at medium to low reaction temperatures. (Right now, High catalytic activity is observed at temperatures of approximately 550°C and below. However, known methane oxidation catalysts typically exhibit high catalytic activity in the presence of water (…). For example, When the reaction stream contains water, it undergoes severe deactivation. In this respect, it is well known that methane oxidation catalyst systems are negatively affected by the presence of water, which significantly inhibits or alters catalyst performance at such low to medium reaction temperatures, such as Hoque. Korean J. et al. Chem. Eng. 2014, 31, As stated in 1316).

[0006] On the other hand, it is known in the art that cerium dioxide and cerium-based mixed oxides typically provide suitable supports on which platinum group metals can be deposited to form metal-supported catalytic systems. Recent literature has evaluated various cerium dioxide particles with rod-like or cubic morphologies as catalyst supports for methane combustion, but all of these studies were conducted under dry conditions: Guo et al. (RSC Adv.) 2018, 8,38641-38647), Dong et al. (Chin. J. Catal. et al.) 2021, 42, 2234-2241), Zhou et al. (Chinese patent application CN113274999), and Chen et al. (ACS Catal.) 2021, 11, (5666-5677). However, it is impossible to extrapolate results obtained under dry conditions to those obtained under wet conditions because water has a significant impact on the catalytic performance of methane combustion, as discussed in the previous section on Hoque. et al. It was mentioned.

[0007] Therefore, there is a need for a new metal-supported catalytic system that can advantageously provide high catalytic activity in methane combustion reactions under wet conditions, while also exhibiting significant resistance to deactivation under those operating conditions. Summary of the Invention

[0008] In a first aspect of the invention, a method for obtaining a metal-supported catalyst is provided, wherein the method comprises the following steps:

[0009] a) Adding at least one loaded transition metal (M) selected from any of Groups 5 to 11 of the periodic table to a support material, wherein the support material comprises at least one oxide selected from the group consisting of cerium dioxide, cerium dioxide-based mixed oxides and any combination thereof;

[0010] b) Drying, preferably under homogenization conditions; and

[0011] c) Heat-treat the solid obtained in step b) at a temperature of about 250°C to about 850°C;

[0012] At least one of the oxides exists substantially in crystalline form; has an average particle size of 5 to 20 nm, as determined by HRTEM; and exhibits a particle size of 50 to 140 nm. 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours; and wherein the molar ratio of at least one supported transition metal (M) selected from any of Groups 5 to 11 of the periodic table to surface oxygen in the support material. (Right now, [At least one supported transition metal (M)]: [Surface oxygen in the carrier material] molar ratio; or (M / O) 表面 The molar ratio is 0.4 to 1.4, as determined by H2 temperature-programmed reduction (H2-TPR). In the context of this invention, H2-TPR analysis is performed on metal-free supports, wherein throughout the patent application, "metal-free" should be understood herein to mean the absence of at least one loaded transition metal (M).

[0013] Throughout this patent application, the terms "at least one molar ratio of the loaded transition metal (M) to the surface oxygen in the carrier material" and "M / O" are stated. 表面 "These can be used interchangeably. Similarly, expressions such as "the molar ratio of palladium to surface oxygen in the support material" and "Pd / O" are interchangeable." 表面 "They can be used interchangeably."

[0014] Furthermore, when calculating the molar ratio of at least one loaded transition metal (M) to surface oxygen in the carrier material, the total number of moles corresponding to the loaded transition metal should be taken into account; that is, if more than one loaded transition metal is added in step a) of the method according to the first aspect of the invention, the M / O ratio is calculated. 表面 The total number of moles of all loaded transition metals should be considered when setting the value.

[0015] According to a second aspect of the invention, a metal-supported catalyst for methane combustion under wet conditions is provided, the catalyst comprising:

[0016] - A carrier material comprising at least one oxide selected from the group consisting of cerium dioxide, cerium dioxide-based mixed oxides, and any combination thereof; and

[0017] - At least one loaded transition metal (M) selected from any of Groups 5 to 11 of the periodic table.

[0018] At least one of the oxides exists substantially in crystalline form; has an average particle size of 5 to 20 nm, as determined by HRTEM; and exhibits a particle size of 50 to 140 nm. 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours.

[0019] The phrase "methane combustion under wet conditions" as used throughout this specification should be understood to mean that the volume percentage of water in the reaction feed used for methane combustion ranges from 0.5% to 30% based on the total volume of the reaction feed. In a preferred embodiment, wet conditions used during methane combustion can be understood to mean that the volume percentage of water in the reaction feed used for methane combustion ranges from 5% to 15% based on the total volume of the reaction feed.

[0020] In a third aspect of the invention, a method for methane combustion under wet conditions is provided, the method comprising the following steps:

[0021] a) Introducing a metal-supported catalyst, as defined according to a second aspect of the invention, into the reactor;

[0022] b) Feeding the reactor with a gaseous reaction feed comprising methane, 5% to 15% (v / v) water, and at least one inert gas, wherein the sum of all components in the gaseous reaction feed is 100% (v / v); and

[0023] c) Keep the metal-supported catalyst in contact with the gaseous feed in the reactor for a time and temperature sufficient for methane combustion to occur.

[0024] In a fourth aspect of the invention, the use of a metal-supported catalyst according to the second aspect of the invention in methane combustion is provided, preferably in methane combustion under wet conditions. Attached Figure Description

[0025] Figure 1 - HRTEM image of a nanoscale cerium dioxide support used for a metal-supported catalyst prepared according to the present invention.

[0026] Figure 2 - H2 temperature-programmed reduction curve of nanoscale cerium dioxide support used for the metal-supported catalyst prepared according to the present invention.

[0027] Figure 3 - An ignition type experiment was conducted to evaluate the catalytic performance of methane combustion under wet conditions using different nano-cerium dioxide supports containing 3% Pd prepared according to Examples 1-4 of the present invention.

[0028] Figure 4 - Long-term steady-state methane combustion experiments were conducted using different nano-cerium dioxide supports containing 3% Pd prepared according to Examples 1-4 of the present invention to evaluate the catalytic performance of methane combustion under humid conditions and dynamic high temperature changes (400-600°C).

[0029] Figure 5 - An ignition type experiment was conducted to evaluate the catalytic performance of methane combustion under wet conditions using nano-cerium dioxide (Ce2) with different Pd contents prepared according to Examples 1 (3 wt% Pd), 5 (5 wt% Pd), and 6 (1 wt% Pd) of the present invention as a support (see Table 1).

[0030] Figure 6 -use

[0031] Using nano-cerium dioxide (Ce2) with different Pd contents prepared according to Examples 1 (3 wt% Pd), 5 (5 wt% Pd), and 6 (1 wt% Pd) of the present invention as supports (see Table 1), long-term steady-state methane combustion experiments were conducted to evaluate the catalytic performance of methane combustion under humid conditions and dynamic high-temperature changes (400-600°C).

[0032] Figure 7 - Long-term steady-state methane combustion experiments were conducted using nano-cerium dioxide (Cel and Ce2) with different Pd contents prepared according to Examples 1 (Ce2-3 wt% Pd), 3 (Cel-3 wt% Pd), 5 (Ce2-5 wt% Pd), and 7 (Cel-5 wt% Pd) of the present invention as supports (see Table 1) to evaluate the catalytic performance of methane combustion under humid conditions and dynamic high-temperature changes (400-600°C).

[0033] Figure 8 - A long-term steady-state methane combustion experiment was conducted to evaluate the catalytic performance of the methane combustion reaction under wet conditions using the bimetallic catalyst of Example 8 according to the present invention.

[0034] Figure 9 - A long-term steady-state methane combustion experiment was conducted to evaluate the catalytic performance of the methane combustion reaction under wet conditions using the catalyst of Example 9 according to the present invention. Detailed Implementation

[0035] In a first aspect of the invention, a method for obtaining a metal-supported catalyst is provided, wherein the method comprises the following steps:

[0036] a) Adding at least one loaded transition metal (M) selected from any of Groups 5 to 11 of the periodic table to a support material, wherein the support material comprises at least one oxide selected from the group consisting of cerium dioxide, cerium dioxide-based mixed oxides and any combination thereof;

[0037] b) Drying, preferably under homogenization conditions; and

[0038] c) Heat-treat the solid obtained in step b) at a temperature of about 250°C to about 850°C;

[0039] At least one of the oxides exists substantially in crystalline form; has an average particle size of 5 to 20 nm, as determined by HRTEM; and exhibits a particle size of 50 to 140 nm. 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours; and the molar ratio (M / O) of at least one of the supported transition metals (M) to the surface oxygen in the support material. 表面 The range is 0.4-1.4, as determined by H2-TPR; H2-TPR analysis is performed on metal-free supports.

[0040] H2-TPR analysis of metal-free cerium dioxide supports, by quantifying the H2 consumption peak between 250 and 550°C, allows for the estimation of surface oxygen (O2) present in the support material.表面 ),For example Figure 2 As shown in the figure. Considering that the experimentally deposited supported transition metal will remain in the final catalyst, a theoretical value for the supported transition metal deposited on the support material can be established. In any case, the amount of experimentally deposited supported transition metal can also optionally be confirmed using inductively coupled plasma (ICP) analysis.

[0041] The inventors unexpectedly discovered that by controlling the properties of the carrier material, such as the available surface oxygen, especially the aforementioned M / O, 表面 The specific surface area and average particle size not only enable the efficient deposition of transition metals, but also maximize the catalytic activity and stability of the resulting metal-supported catalysts under wet reaction conditions. Specifically, the above M / O ratio was found to be... 表面 The ratio is a key parameter in the catalyst synthesis process, which enhances the stability and activity of metal-supported catalysts for methane combustion under wet conditions. Furthermore, compared to other known catalysts, the nanoscale metal-supported catalysts of the present invention, obtainable according to the first aspect of the invention, offer improved stability over longer operating times (TOS) and after exposure to dynamic high-temperature variations.

[0042] The at least one supported transition metal (M) added in step a) of the method according to the first aspect of the invention may be provided in the form of a metal salt or a metal complex, or alternatively, as a metal-based alloy. The addition of at least one supported transition metal (M) to the support material can preferably be carried out by wet impregnation, initial volume impregnation, or deposition-precipitation, methods well known in the art. In a preferred embodiment, where multiple supported transition metals are used to produce the metal-supported catalyst according to the invention of the first aspect, all of them can be added in step a) of the method, such that subsequent steps b) and c) only need to be performed once on the previously formed mixture of the multiple supported transition metals to produce the metal-supported catalyst. These embodiments are found particularly advantageous because they avoid the lengthy multi-step methods known in the art, in which each supported transition metal undergoes all steps a) to c) independently, thus requiring several drying and calcination steps to produce the final catalyst.

[0043] 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 invention, such that the total amount of the transition metal supported on the support material is equal to or greater than 2% by weight 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 invention, such that the total amount of the transition metal supported 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.

[0044] In some embodiments, the metal-supported catalyst may comprise at least one supported transition metal (M) as a metal-based alloy, and a variety of supported transition metals (M) are provided. In those embodiments, the metal-supported catalyst may preferably comprise at least one supported transition metal (M) as a metal-based alloy in an amount equal to or greater than 2 wt% based on the total weight of the metal-supported catalyst, or alternatively, in an amount greater than 2 wt%, greater than 2 wt% to 5 wt%, 2.5 wt% to 5 wt%, greater than 2 wt% to 4 wt%, or greater than 2 wt% to 3 wt% based on the total weight of the metal-supported catalyst.

[0045] 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 mixture thereof; preferably, at least one supported transition metal (M) may be selected from the group consisting of Pd, Pt, Rh, Ir, Ru and any mixture thereof; more preferably, at least one supported transition metal (M) may be selected from the group consisting of Pd, Pt, Rh, Ru and any mixture thereof; even more preferably, at least one supported transition metal (M) may be selected from the group consisting of Pd, Pt, Ru and any mixture 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 is composed of Pd. Examples of suitable transition metal salts or complexes include, but are not limited to, palladium propionate, palladium butyrate, tris(dibenzylacetone)dipalladium(0), tris(benzylacetone)tripalladium(0), palladium benzoate, palladium acetylacetone, palladium nitrate, palladium sulfate, palladium chloride, palladium acetate, platinum acetylacetone, platinum acetate, dinitrodiammineplatinum nitrate, sodium chloroplatinate, sodium hexachloroplatinum, tetraammineplatinum nitrate, rhodium nitrate, rhodium chloride, iridium tribromide, iridium chloride, potassium iridium chloroesterate, ruthenium nitrate, ruthenium chloride, ammonium chlororuthenate, or potassium ruthenate.

[0046] Throughout the specification, the term "metal-based alloy" regarding at least one loaded transition metal (M) primarily refers to an alloy containing at least one loaded transition metal element selected from any of Groups 5 to 11 of the periodic table as its main component; that is, the alloy contains at least 80% by weight based on the total weight of the alloy. (Right now, At least one loaded transition metal element (equal to or greater than 80% by weight). In a preferred embodiment, a suitable metal-based alloy comprises at least 90% by weight based on the total weight of the alloy. (Right now, At least one loaded transition metal element (equal to or greater than 90% by weight). In some embodiments, the metal-based alloy may contain two loaded transition metal (M) elements, one of which is the main component. Examples of suitable metal-based alloys include, but are not limited to, Pd-Pt alloys, Pt-Au alloys, and Pt-Ru alloys. (For example, Pt with 5 wt% Ru) and Pt-Rh alloy ( For example, Pt with 10% by weight Rh).

[0047] The carrier material used in the method according to the first aspect of the invention comprises at least one oxide selected from the group consisting of cerium dioxide, cerium dioxide-based mixed oxides, and any combination thereof, and the at least one oxide is present in substantially crystalline form. The expression "present in substantially crystalline form" as used throughout the specification means that at least 90% by weight of the at least one oxide is in crystalline form based on the total weight of the at least one oxide. (Right now, Based on its total weight, up to 10% by weight of at least one oxide may be in amorphous form. According to some embodiments, based on the total weight of at least one oxide, at least 95% by weight of at least one oxide is provided in crystalline form. (Right now, Based on its total weight, at most 5% by weight of at least one oxide may be in an amorphous form. In some other embodiments, at least one oxide may be in a crystalline form. Preferably, the carrier material comprises at least 95% by weight of at least one oxide in a crystalline form, said crystalline form being a fluorite-type crystal structure, based on the total weight of at least one oxide. In another embodiment, the carrier material may comprise at least one oxide based on the total weight of at least one oxide, wherein the at least one oxide is in a crystalline form and has a fluorite-type crystal structure.

[0048] It is noteworthy that the support materials comprising at least one cerium dioxide-based mixed oxide used in different aspects of the invention are defined by specific morphological, size, and / or shape characteristics, and can be produced by synthetic methods known in the art, such as hydrothermal synthesis, co-precipitation, or sol-gel methods. A suitable example is cerium oxide referred to as "Ce3" throughout this patent application, which has been prepared by methods known in the art and has the properties detailed in Table 1 below. Alternatively, the support materials comprising at least one cerium dioxide-based mixed oxide may be commercially available: For example, Cerium oxide with reference number AC106-011 and lot number 06-0117 (purchased from NanoScale Corporation, Ce1); cerium oxide with reference number ITQ. 3A and lot number 0633984 (purchased from Solvay, Ce2); and cerium oxide with reference number 544841-25G and lot number MKCK1143 (purchased from Sigma-Aldrich, Ce4); among which the commercially available cerium dioxide-based mixed oxides have the following properties summarized in Table 1:

[0049] Table 1

[0050]

[0051] (a) Measured by N2 adsorption; (b) Measured by H2-TPR

[0052] In the embodiments, the carrier material comprises at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises less than 40 mol% (Right now, The carrier material may contain at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide contains a certain amount of at least one cerium dioxide-based mixed oxide capable of forming the cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide contains at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide preferably comprises at least 1 mol% and at least 40 mol%, more preferably in the range of 5 mol% to 30 mol%. The molar percentage of the at least one cerium dioxide-based mixed oxide is calculated relative to the total number of moles of the at least one cerium dioxide-based mixed oxide, which means that if the carrier material to which at least one platinum group metal is added in step a) comprises multiple cerium dioxide-based mixed oxides, then the molar percentage of the at least one cerium dioxide-based mixed oxide should be calculated relative to the total number of moles of the multiple cerium dioxide-based mixed oxides.

[0053] The at least one element capable of forming a cerium dioxide-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, the at least one element capable of forming a cerium dioxide-based mixed oxide is selected from the group consisting of Zr, La, Y, and any combination thereof. In another preferred embodiment, the at least one element capable of forming a cerium dioxide-based mixed oxide is selected from the group consisting of Zr, La, and any combination thereof. More preferably, the at least one element capable of forming a cerium dioxide-based mixed oxide is Zr.

[0054] The carrier material may preferably comprise at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises less than 40 mol% (Right now, The carrier material comprises at least one cerium dioxide-based mixed oxide (more than 0 mol% but less than 40 mol%) of at least one metallic element capable of forming a cerium dioxide-based mixed oxide, wherein the at least one metallic element is selected from the group consisting of Zr, In, Sn, La, Pr, Nd, Gd, Y, and any combination thereof. In another preferred embodiment, the carrier material comprises at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises a certain amount of at least one metallic element capable of forming a cerium dioxide-based mixed oxide, wherein the metallic element is preferably in the range of at least 1 mol% to 40 mol%, more preferably in the range of 5 mol% to 30 mol%, and wherein the at least one metallic element is selected from the group consisting of Zr, La, Y, and any combination thereof. In other preferred embodiments, the carrier material comprises at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises a certain amount of at least one metallic element capable of forming a cerium dioxide-based mixed oxide, wherein the metallic element is preferably in the range of at least 1 mol% to 40 mol%, more preferably in the range of 5 mol% to 30 mol%, and wherein the at least one metallic element is selected from the group consisting of Zr, La, and any combination thereof.

[0055] In an embodiment, the carrier material may comprise at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises less than 40 mol% (Right now, The metal-supported catalyst of the present invention contains at least one metal element capable of forming a cerium dioxide-based mixed oxide (more than 0 mol% but less than 40 mol%), wherein the at least one metal element is Zr or is composed thereof. Preferably, in an embodiment, the support material of the metal-supported catalyst of the present invention may contain at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide contains a certain amount of at least one metal element capable of forming a cerium dioxide-based mixed oxide, wherein the metal element is preferably in the range of 1 mol% to at least 40 mol%, more preferably in the range of 5 mol% to 30 mol%, and wherein the at least one metal element is Zr or is composed thereof.

[0056] The carrier material may comprise a variety of cerium dioxide-based mixed oxides, wherein each cerium dioxide-based mixed oxide may be independently defined as indicated in any of the foregoing embodiments.

[0057] In the method according to the first aspect of the invention, the carrier material may further have a surface oxygen to cerium molar ratio of 0.06 to 0.20, as determined by H2-TPR. The surface oxygen to cerium molar ratio is preferably 0.07 to 0.15, or more preferably, 0.08 to 0.14, as determined by H2-TPR.

[0058] In the method according to a first aspect of the invention, the molar ratio (M / O) of at least one loaded transition metal (M) to surface oxygen in the carrier material is... 表面 The molar ratio of surface oxygen to cerium can be from 0.4 to 1.4, as determined by H2-TPR; wherein H2-TPR analysis is performed on the metal-free support. In an embodiment, the support material may also have a surface oxygen to cerium molar ratio of 0.06 to 0.20, as determined by H2-TPR; and the molar ratio of at least one loaded transition metal (M) to surface oxygen can be from 0.4 to 1.4, as also determined by H2-TPR; wherein H2-TPR analysis is performed on the metal-free support.

[0059] In a preferred embodiment, the molar ratio (M / O) of at least one loaded transition metal (M) to surface oxygen in the support material is... 表面 The molar ratio (M / O) can be 0.4 to 1.2, 0.5 to 1.1, or 0.5 to 1.0, as determined by H2-TPR; wherein H2-TPR analysis is performed on metal-free supports. In some embodiments, the molar ratio (M / O) of at least one supported transition metal (M) to surface oxygen in the support material is... 表面 The surface oxygen to cerium molar ratio can be from 0.4 to 1.4, and / or the support material can also have a surface oxygen to cerium molar ratio of 0.06 to 0.20, wherein at least one loaded transition metal (M) and the surface oxygen and / or the surface oxygen to cerium molar ratio are each determined by H2-TPR, wherein H2-TPR analysis is performed on metal-free supports.

[0060] In the method according to the first aspect of the invention, the carrier material may preferably exhibit a thickness of 60 to 130 μm. 2 / g, 65 to 140 m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g, 80 to 130 m 2 / g, 100 to 140 m 2 / g or 100 to 130 m 2The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours.

[0061] In the method according to the first aspect of the invention, the carrier material may preferably have an average particle size of 5 to 20 nm, as determined by HRTEM, or more preferably, the carrier 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 determined by HRTEM; alternatively, the particle size may also be determined using field emission scanning electron microscopy (FESEM).

[0062] In embodiments, the carrier material used in the method according to the first aspect of the invention may have an average particle size of 5 to 20 nm, as determined by HRTEM; and exhibits a particle size of 60 to 130 μm. 2 / g, 65 to 140 m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g, 80 to 130 m 2 / g, 100 to 140 m 2 / g or 100 to 130 m 2 The specific surface area per g, as measured by BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours. In another embodiment, the support material used in the method according to the first aspect of the invention may have an average particle size of 5 to 18 nm, as determined by HRTEM; and exhibits a surface area of ​​60 to 130 μm. 2 / g, 65 to 140 m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g, 80 to 130 m 2 / g, 100 to 140 m 2 / g or 100 to 130 m 2 The specific surface area per g, as measured by BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours. In another embodiment, the support material used in the method according to the first aspect of the invention may have an average particle size of 5 to 15 nm, as determined by HRTEM; and exhibits a surface area of ​​60 to 130 μm. 2 / g, 65 to 140 m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g, 80 to 130 m 2 / g, 100 to 140 m 2 / g or 100 to 130 m 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours. In yet another embodiment, the support material used in the method according to the first aspect of the invention may have an average particle size of 8 to 15 nm, as determined by HRTEM; and exhibits a surface area of ​​60 to 130 μm. 2 / g, 65 to 140 m 2 / g, 50 to 120 m 2 / g, 75 to 125m 2 / g, 80 to 130 m 2 / g, 100 to 140 m 2 / g or 100 to 130 m 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours.

[0063] In other embodiments, the carrier material used in the method according to the first aspect of the invention may have an average particle size of 8 to 12 nm, as determined by HRTEM; and exhibit a particle size of 60 to 130 nm. 2 / g, 65 to 140 m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g, 80 to 130 m 2 / g, 100 to 140 m 2 / g or 100 to 130 m 2 The specific surface area per g, as measured by BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours. In yet another embodiment, the support material used in the method according to the first aspect of the invention may have an average particle size of 5 to 10 nm, as determined by HRTEM; and exhibits a surface area of ​​60 to 130 μm. 2 / g, 65 to 140 m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g, 80 to 130m 2 / g, 100 to 140 m 2 / g or 100 to 130 m 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours.

[0064] In step b) of the method according to the first aspect of the invention, drying is preferably carried out under homogenization conditions. In the case of the method according to the first aspect of the invention, "homogenization conditions" should be understood as conditions sufficient to ensure that at least one platinum group metal is uniformly dispersed on the surface of the carrier material and / or in the pores of the carrier material (more particularly, in the pores of cerium dioxide, cerium mixed oxides, or any combination thereof contained in the carrier material).

[0065] In a preferred embodiment, drying step b) is carried out under homogenization conditions, which include or consist of stirring, such as manual stirring. (For example, Homogenization can be performed using a scraper or a magnetic stirrer. In another embodiment, homogenization may preferably be performed by stirring after step a) but before step b). For example, Stir manually (For example, Stirring can be done using a scraper or a magnetic stirrer. In yet another embodiment, homogenization may also be performed after step a) but before step b), and during step b), preferably by stirring. For example, Stir manually (For example, The drying step b) is carried out using a scraper or a magnetic stirrer. The drying step b) is preferably carried out at a temperature of 50 to 110°C, more preferably 80 to 100°C.

[0066] In step c) of the method according to the first aspect of the invention, according to a preferred embodiment, the solid obtained in step b) may be heat-treated at a temperature of about 300°C to about 850°C, more preferably at a temperature of about 350°C to about 800°C. (Right now, (Calcination). In another preferred embodiment, in step c) of the method according to the first aspect of the invention, the solid obtained in step b) may be heat-treated at a temperature of about 400°C to about 700°C.

[0067] When the term "about" appears before and modifies a number throughout the specification, it should be understood as disclosing a specific value and specifying any value within a range defined by ±5% of that number, more preferably within a range defined by ±2% of that number. For example,

[0068] The expression “about 1” should be interpreted as “in the range of 0.95 to 1.05”, preferably “in the range of 0.98 to 1.02”.

[0069] After step b) but before step c), the method according to the first aspect of the invention may optionally further include a step in which the dried solid obtained in step b) is:

[0070] -Applied to an inert substrate (For example,(Integral substrate or integral structure), preferably in or above a honeycomb inert substrate; or

[0071] - Formed into granules.

[0072] The choice of whether to apply the dried solid obtained in step b) to or on an inert matrix, or alternatively to form it into granules, generally depends on the intended application requirements of the metal-supported catalyst produced by the synthesis method according to the invention. Examples of suitable inert substrates include, but are not limited to, silica, alumina, silica-alumina, silica-magnesium oxide, silica-zirconium oxide, silica-thorium oxide, silica-beryllium oxide, and silica-titanium oxide. In a particular embodiment, the inert substrate comprises or is composed of silica, alumina, silica-alumina, silica-magnesium oxide, silica-zirconium oxide, silica-thorium oxide, silica-beryllium oxide, silica-titanium oxide, or any combination thereof.

[0073] In a preferred embodiment, after step b) but before step c), the method according to the first aspect of the invention may further include a step in which the dried solid obtained in step b) is applied to or over a honeycomb-shaped inert substrate. The honeycomb-shaped inert substrate may be a honeycomb corrugated substrate, preferably a metal foil substrate or a glass fiber substrate (such as a nonwoven e-glass fiber substrate), or a ceramic extrusion substrate (such as cordierite). The expression "honeycomb-shaped inert substrate" as used throughout the specification should be understood to mean an inert substrate having a honeycomb lattice structure, wherein the lattice structure may be hexagonal, square, triangular, or wavy. Preferably, the honeycomb lattice structure is hexagonal, triangular, or wavy.

[0074] In the method according to a first aspect of the invention, the heat-treated solid produced in step c) may optionally undergo a reduction step. Specifically, the heat-treated solid produced in step c) may undergo a reduction step in which it is brought into contact with a reducing agent, preferably a reducing gas. (For example, H2 or CO), hypophosphite, borohydride salts (For example, The reducing gas comprises sodium borohydride, hydrazine, formic acid, formaldehyde, citric acid, and any combination thereof. The reducing gas is preferably used at a temperature typically fixed between 100 and 600°C, and optionally also in the presence of other known reducing components to promote the formation of metal particles. Examples of such reducing components include, but are not limited to, CO, hypophosphite, borohydride salts (such as sodium borohydride), hydrazine, formic acid, formaldehyde, citric acid, or any combination thereof.

[0075] In some embodiments, after step b) but before step c), the method according to the first aspect of the invention may further include a step in which the dried solid obtained in step b) is applied to / on an inert substrate. It may also include an additional step in which the heat-treated solid produced in step c) is subjected to a reduction step, particularly using a reducing agent, preferably a reducing gas. (For example, The group consisting of H2 or CO, hypophosphite, borohydride salts, hydrazine, formic acid, formaldehyde, citric acid, and any combination thereof. In these specific embodiments, it is apparent that the application of the dried solids obtained in step b) to / on an inert substrate may be performed before, after, or simultaneously with the optional reduction step.

[0076] After step b) but before step c), the method according to the first aspect of the invention may optionally further include a step in which the dried solid obtained in step b) is shaped into granules, and may further include an additional step in which the heat-treated solid produced in step c) is subjected to a reduction step, particularly using a reducing agent, preferably a reducing gas. (For example, The group consisting of H2 or CO, hypophosphite, borohydride salts, hydrazine, formic acid, formaldehyde, citric acid, and any combination thereof. In these specific embodiments, it is apparent that the drying solids obtained in step b) can be shaped into granules before, after, or simultaneously with the optional reduction step.

[0077] According to a second aspect of the invention, a metal-supported catalyst for methane combustion under wet conditions is provided, characterized in that it comprises:

[0078] - A carrier material comprising at least one oxide selected from the group consisting of cerium dioxide, cerium dioxide-based mixed oxides, and any combination thereof; and

[0079] - At least one loaded transition metal (M) selected from any of Groups 5 to 11 of the periodic table.

[0080] At least one of the oxides exists substantially in crystalline form; has an average particle size of 5 to 20 nm, as determined by HRTEM; and exhibits a particle size of 50 to 140 nm. 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours.

[0081] The support material of the metal-supported catalyst according to the second aspect of the invention may preferably comprise at least one oxide selected from the group consisting of cerium dioxide, cerium dioxide-based mixed oxides and any combination thereof, wherein at least 90% by weight of the at least one oxide is in crystalline form based on the total weight of the at least one oxide. (Right now, Based on its total weight, at most 10% by weight of the at least one oxide may be in an amorphous form. According to another embodiment, based on the total weight of the at least one oxide, at least 95% by weight of the at least one oxide is provided in a crystalline form. (Right now, Based on its total weight, up to 5% by weight of at least one oxide may be in an amorphous form. In some other embodiments, at least one oxide is in a crystalline form overall.

[0082] The support material of the metal-supported catalyst according to the second aspect of the invention may comprise at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises less than 40 mol%. (Right now, The carrier material may contain at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide contains a certain amount of at least one cerium dioxide-based mixed oxide capable of forming the cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide contains at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide preferably ranges from 1 mol% to at least 40 mol%, more preferably from 5 mol% to 30 mol%. The molar percentage of the at least one cerium dioxide-based mixed oxide is calculated relative to the total number of moles of the at least one cerium dioxide-based mixed oxide, which means that if the carrier material contains multiple cerium dioxide-based mixed oxides, the molar percentage of the at least one cerium dioxide-based mixed oxide should be calculated relative to the total number of moles of the multiple cerium dioxide-based mixed oxides.

[0083] The at least one element capable of forming a cerium dioxide-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, the at least one element capable of forming a cerium dioxide-based mixed oxide is selected from the group consisting of Zr, La, Y, and any combination thereof. In another preferred embodiment, the at least one element capable of forming a cerium dioxide-based mixed oxide is selected from the group consisting of Zr, La, and any combination thereof. More preferably, the at least one element capable of forming a cerium dioxide-based mixed oxide is Zr.

[0084] The carrier material may preferably comprise at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises less than 40 mol% (Right now,The carrier material comprises at least one cerium dioxide-based mixed oxide (more than 0 mol% but less than 40 mol%) of at least one metallic element capable of forming a cerium dioxide-based mixed oxide, wherein the at least one metallic element is selected from the group consisting of Zr, In, Sn, La, Pr, Nd, Gd, Y, and any combination thereof. In another preferred embodiment, the carrier material comprises at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises a certain amount of at least one metallic element capable of forming a cerium dioxide-based mixed oxide, wherein the metallic element is preferably in the range of at least 1 mol% to 40 mol%, more preferably in the range of 5 mol% to 30 mol%, and wherein the at least one metallic element is selected from the group consisting of Zr, La, Y, and any combination thereof. In other preferred embodiments, the carrier material comprises at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises a certain amount of at least one metallic element capable of forming a cerium dioxide-based mixed oxide, wherein the metallic element is preferably in the range of at least 1 mol% to 40 mol%, more preferably in the range of 5 mol% to 30 mol%, and wherein the at least one metallic element is selected from the group consisting of Zr, La, and any combination thereof.

[0085] In an embodiment, the carrier material may comprise at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises less than 40 mol% (Right now, The metal-supported catalyst of the present invention contains at least one metal element capable of forming a cerium dioxide-based mixed oxide (more than 0 mol% but less than 40 mol%), wherein the at least one metal element is Zr or is composed thereof. Preferably, in an embodiment, the support material of the metal-supported catalyst of the present invention may contain at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide contains a certain amount of at least one metal element capable of forming a cerium dioxide-based mixed oxide, wherein the metal element is preferably in the range of 1 mol% to at least 40 mol%, more preferably in the range of 5 mol% to 30 mol%, and wherein the at least one metal element is Zr or is composed thereof.

[0086] In one embodiment, the support material of the metal-supported catalyst of the present invention may comprise a variety of cerium dioxide-based mixed oxides, wherein each cerium dioxide-based mixed oxide may be independently defined as indicated in any of the foregoing embodiments.

[0087] In a preferred embodiment, the support material of the metal-supported catalyst according to the second aspect of the invention can exhibit a thickness of 60 to 130 μm. 2 / g, 65 to 140 m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g, 80 to 130 m 2 / g, 100 to 140m 2 / g or 100 to 130 m 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours.

[0088] The support material of the metal-supported catalyst according to the second aspect of the invention has 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 determined by HRTEM or alternatively by FESEM.

[0089] The support material for the metal-supported catalyst according to the second aspect of the invention preferably has an average particle size in the range of 5 to 20 nm, as determined by HRTEM; and exhibits a particle size of 50 to 140 nm. 2 / g, 60 to 130 m 2 / g, 65 to 140m 2 / g, 50 to 120 m 2 / g, 75 to 125 m 2 / g or 80 to 130 m 2 The specific surface area per g, as measured by BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours. 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, as determined by HRTEM; and exhibits a surface area of ​​50 to 140 nm. 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 The specific surface area per g, as measured by BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours. 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, as determined by HRTEM; and exhibits a surface area of ​​50 to 140 nm. 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 2The specific surface area per g, as measured by BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours. 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, as determined by HRTEM; and exhibits a surface area of ​​50 to 140 nm. 2 / g, 60 to 130 m 2 / g, 65 to 140 m 2 / g, 50 to 120m 2 / g, 75 to 125 m 2 / g or 80 to 130 m 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours.

[0090] The metal-supported catalyst according to a second aspect of the invention comprises at least one supported transition metal (M), preferably selected from the group consisting of Pd, Pt, Rh, Ir, Cu, Ru, Co, Ag, Nb, and any mixture thereof. Preferably, the at least one supported transition metal (M) is selected from the group consisting of Pd, Pt, Rh, Ir, Ru, and any mixture thereof. More preferably, the at least one supported transition metal (M) is selected from the group consisting of Pd, Pt, Rh, Ru, and any mixture thereof. Even more preferably, the at least one supported transition metal (M) is selected from the group consisting of Pd, Pt, Ru, and any mixture thereof; and even more preferably, the at least one supported transition metal (M) may be Pd or Pt. In yet another embodiment, the at least one supported transition metal (M) is Pd or composed of Pd.

[0091] Suitable metal-based alloys for use in metal-supported catalysts according to a second aspect of the invention may comprise at least 80% by weight, based on the total weight of the alloy. (Right now, At least one loaded transition metal element (equal to or greater than 80% by weight), or at least 90% by weight based on the total weight of the alloy. (Right now, At least one loaded transition metal element (equal to or greater than 90% by weight). In some embodiments, the metal-based alloy may contain two loaded transition metal elements, one of which is the main component. Examples of suitable metal-based alloys include, but are not limited to, Pd-Pt alloys, Pt-Au alloys, and Pt-Ru alloys. (For example, Pt with 5 wt% Ru) and Pt-Rh alloys (For example, Pt with 10% by weight Rh).

[0092] The metal-supported catalyst according to the second aspect of the invention can be in the form of an extrusion or granules. (Right now,(Formed into granules) is provided. Alternatively, the metal-supported catalyst may be supported on an inert substrate. Examples of suitable inert substrates include, but are not limited to, silica, alumina, silica-alumina, silica-magnesium oxide, silica-zirconium oxide, silica-thorium oxide, silica-beryllium oxide, and silica-titanium oxide. In a particular embodiment, the inert substrate comprises or is composed of silica, alumina, silica-alumina, silica-magnesium oxide, silica-zirconium oxide, silica-thorium oxide, silica-beryllium oxide, silica-titanium oxide, or any combination thereof. The metal-supported catalyst according to a second aspect of the invention may also comprise an inert substrate, preferably a honeycomb inert substrate. The honeycomb inert substrate may be a honeycomb corrugated substrate, which may preferably be a metal foil substrate or a glass fiber substrate (such as a nonwoven e-glass fiber substrate), or a ceramic extrusion substrate (such as cordierite).

[0093] The metal-supported catalyst according to the second aspect of the invention may preferably contain, based on the total weight of the metal-supported catalyst, at least 2% by weight or more of at least one supported transition metal (M), more than 2% by weight of at least one supported transition metal (M), 2% to 5% by weight of at least one supported transition metal (M), 2.5% to 5% by weight of at least one supported transition metal (M), 3% to 5% by weight of at least one supported transition metal (M), 2% to 4% by weight of at least one supported transition metal (M), or more than 2% to 3% by weight of at least one supported transition metal (M).

[0094] In some embodiments, the metal-supported catalyst according to the second aspect of the invention may comprise at least one supported transition metal (M) as a metal-based alloy, wherein providing multiple supported transition metals (M) can advantageously enhance catalytic activity at medium and low temperatures. In those embodiments, the metal-supported catalyst according to the second aspect of the invention may preferably comprise at least one supported transition metal (M) as a metal-based alloy in an amount equal to or greater than 2 wt% based on the total weight of the metal-supported catalyst, or alternatively, in an amount greater than 2 wt%, greater than 2 wt% to 5 wt%, 2.5 wt% to 5 wt%, greater than 2 wt% to 4 wt%, or greater than 2 wt% to 3 wt% based on the total weight of the metal-supported catalyst.

[0095] In a preferred embodiment of the second aspect of the invention, the metal-supported catalyst can be obtained by or through the method of the first aspect of the invention.

[0096] In a third aspect of the invention, a method for methane combustion under wet conditions is provided, the method comprising the following steps:

[0097] a) Introducing a metal-supported catalyst, as defined according to a second aspect of the invention, into the reactor;

[0098] b) Feeding the reactor with a gaseous reaction feed comprising methane, 5% to 15% (v / v) water, and at least one inert gas, wherein the sum of all components in the gaseous reaction feed is 100% (v / v); and

[0099] c) Keep the metal-supported catalyst in contact with the gaseous feed in the reactor for a time and temperature sufficient for methane combustion to occur.

[0100] In the context of this invention, the term "reaction feed" refers to the gas stream fed into the combustion reactor. The gas stream preferably consists of methane, 0.5-30% by volume of water, and a balance to 100% by volume, the balance comprising at least one inert gas (such as nitrogen) and optionally other gaseous components (such as NO, NO2, CO, CO2, and / or O2). More preferably, the gas stream may consist of methane. (For example, The composition consists of 0.01-0.2 vol% methane, corresponding to 100-2000 ppm methane, 5-15 vol% water, and a balance to 100 vol%, the balance containing at least one inert gas (such as nitrogen) and optionally other gaseous components (such as NO, NO2, CO, CO2 and / or O2).

[0101] In some embodiments, prior to step a), the method according to a third aspect of the invention may further include subjecting the metal-supported catalyst to a reduction step using a reducing agent selected from the group consisting of a reducing gas, hypophosphite, borohydride salt, hydrazine, formic acid, formaldehyde, citric acid, and any combination thereof. If the reduction step is performed, the method may optionally subsequently include an oxidation step, which may be performed before, simultaneously with, or after step a).

[0102] In a fourth aspect of the invention, the use of a metal-supported catalyst according to the second aspect of the invention in methane combustion is provided, preferably in methane combustion under wet conditions.

[0103] Throughout the specification and claims, the term "comprising / including" and its variations are not intended to exclude other technical features, components, or steps. Other advantages and features of the invention will become apparent to those skilled in the art upon review of the specification, or through practice of the invention without excessive effort.

[0104] Example

[0105] The following examples are provided by way of illustration and should not be construed as limiting the invention. Numerous variations are possible, and it should be understood that the invention may be practiced in ways other than those specifically described in the following examples, within the scope of the appended claims.

[0106] In the examples provided below, the Brunauer-Emmett-Teller (BET) values ​​of the corresponding samples were calculated from the N2 isotherm at 77 K on a volumetric Micromeritics ASAP™ 2020 analyzer after activation at 400°C and under vacuum for 3 hours. High-resolution transmission electron microscopy (HRTEM) analysis was performed using a 200 kV JEOL JEM2100F microscope.

[0107] H2-TPR spectra were obtained using an Autochem 2910 equipped with a thermal conductivity detector (TCD) under the following conditions: 50 mg of solid (particle size measured: 0.2–0.4 mm) was placed in a quartz tube and kept in Ar (50 ml / min) at room temperature for 15 min, followed by reduction to 800°C at a heating rate of 10°C / min in a 10% H2 / Ar (50 ml / min) mixed gas stream. The surface oxygen (O2) of the support material was then expressed. 表面 The H2 consumption of the first reduction peak (between 250 and 550°C) in the H2-TPR spectrum obtained from the aforementioned experiments has been defined and quantified.

[0108] Unless otherwise stated, in each of the catalytic performance tests provided below, 50 mg of granular catalyst sample was diluted with 1.5 g of granular silicon carbide before each use in a methane combustion reaction.

[0109] Furthermore, all methane combustion reactions were carried out independently in a fixed-bed quartz tube reactor with a diameter of 1.2 cm and a length of 53 cm. Air at a rate of 100 mL / min was passed through a water saturator heated to 46°C, and the resulting saturated air stream was mixed with a 3,000-ppm methane stream diluted in N2 at a rate of 50 mL / min.

[0110] In addition, unless otherwise specified, the following specific feed conditions are used in each catalytic test:

[0111] -Methane combustion reaction under dry conditions: in N2, 0.1 vol% CH4 and 14.0 vol% O2; total flow rate 150 mL / min; and GHSV = 180,000 mL / g 催化剂 h (GHSV = air space velocity);

[0112] -Methane combustion reaction under wet conditions: in N2, 0.1 vol% CH4, 14.0 vol% O2 and 6.1 vol% H2O; total flow rate 150 mL / min; and GHSV = 180,000 mL / g 催化剂 h.

[0113] Example 1 - Exemplary Ce2 ​​metal-supported catalyst (Pd / O) containing 3% by weight Pd 表面 Synthesis of (=0.56)

[0114] According to the method of the present invention, an exemplary metal-supported catalyst according to the present invention is prepared as follows, which contains 3% by weight palladium as a supported platinum group metal:

[0115] The use of commercially available cerium dioxide (see Ce2 in Table 1) to prepare this metal-supported catalyst has been considered. Ce2 is commercially available cerium dioxide (purchased from Solvay, reference number ITQ. 3A, lot number 0633984) exhibiting an average particle size of 7-9 nm (see Table 1). Figure 1 HRTEM image of Ce2 in 98 m 2 / g BET surface area and the measured molar ratio of surface oxygen to cerium of 0.087 (obtained by H2-TPR, see [reference]). Figure 2 (Ce2 in the middle).

[0116] 0.85 g of tetraamminepalladium(II) nitrate solution (10% by weight 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 Ce₂ support (pre-placed on a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The flat-bottomed porcelain crucible containing the wet solid was then 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 complete drying was achieved.

[0117] For this metal-support, Pd / O 表面 The parameter is 0.56, a value that takes into account the amount of Pd incorporated (3 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.087 (obtained from H2-TPR, see...). Figure 2 The estimate is based on both Ce2 and Ce2.

[0118] The resulting dry solids were then granulated at 4 bar using a manual hydraulic press (particle size: 0.2-0.4 mm). Subsequently, they were heat-treated using a vertical flow bed reactor. Right now(Calcination). Then, 150 mg of the granulated Ce2 material containing 3% Pd was calcined at 650°C with an air flow of 175 mL / min for 4 h (heating slope 2°C / min). Finally, the sample was cooled in an air stream. The BET surface area measured by N2 adsorption was approximately 93 m². 2 / g. The average particle size was determined to be 8-10 nm using HRTEM.

[0119] Example 2 - Exemplary Ce3 metal-supported catalyst (Pd / O3) containing 3% by weight of t Pd 表面 Synthesis of (=0.58)

[0120] According to the method of the present invention, an exemplary metal-supported catalyst according to the present invention is prepared as follows, which contains 3% by weight palladium as a supported platinum group metal:

[0121] The preparation of this metal-supported catalyst has been considered using a specific cerium oxide (see Ce3 in Table 1) prepared according to methods known in the art. Ce3 is a cerium dioxide exhibiting an average particle size of 6-8 nm (see Table 1). Figure 1 HRTEM image of Ce3 in 120 m 2 / g BET surface area and the measured molar ratio of surface oxygen to cerium of 0.083 (obtained by H2-TPR, see [reference]). Figure 2 (Ce3 in the middle).

[0122] 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 (pre-placed on a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The flat-bottomed porcelain crucible containing the wet solid was then 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 completely dry.

[0123] For this metal-support, Pd / O 表面 The parameter is 0.58, a value that takes into account the amount of Pd incorporated (3 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.083 (obtained from H2-TPR, see...). Figure 2 The value is estimated by combining Ce3 and Ce3.

[0124] The resulting dry solids were then granulated (particle size: 0.2-0.4 mm) at 4 bar using a manual hydraulic press. Subsequently, the granules were heat-treated using a vertical flow bed reactor. (Right now(Calcination). Then, 150 mg of the obtained granulated Ce3 material containing 3% Pd by weight was calcined at 650°C with an air flow of 175 mL / min for 4 h (heating slope 2°C / min). Finally, the sample was cooled in an air flow.

[0125] Example 3 - Comparative Cel metal-supported catalyst (Pd / O) containing 3% by weight Pd 表面 Synthesis of (=0.35)

[0126] According to the method of the present invention, a comparative metal-supported catalyst is prepared as follows, which contains 3 wt% palladium as a supported platinum group metal:

[0127] The use of commercially available cerium dioxide (see Cel in Table 1) to prepare this metal-supported catalyst has been considered. Cel is commercially available cerium dioxide (purchased from NanoScale Corporation, reference number AC106-011, lot number 06-0117) exhibiting an average particle size of 5-7 nm (see Table 1). Figure 1 HRTEM image of Cel), 73 m 2 / g BET surface area and the measured molar ratio of surface oxygen to cerium (obtained by H2-TPR, see [reference]). Figure 2 (Cel in the middle).

[0128] A solution of 0.85 g of tetraamminepalladium(II) nitrate (10% by weight 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 (pre-placed on a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The flat-bottomed porcelain crucible containing the wet solid was then 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 complete drying was achieved.

[0129] For this metal-support, Pd / O 表面 The parameter is 0.35, a value that takes into account the amount of Pd incorporated (3 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.139 (obtained from H2-TPR, see...). Figure 2 The estimate is based on both Cel and the others.

[0130] The resulting dry solids were then granulated (particle size: 0.2-0.4 mm) at 4 bar using a manual hydraulic press. Subsequently, the granules were heat-treated using a vertical flow bed reactor. (Right now (Calcination). Then, 150 mg of the obtained granulated Cel material containing 3% Pd by weight was calcined at 650°C with an air flow of 175 mL / min for 4 h (heating slope 2°C / min). Finally, the sample was cooled in an air flow.

[0131] Example 4 - Comparative Ce4 metal-supported catalyst (Pd / O4) containing 3% by weight Pd 表面 Synthesis of (=0.86)

[0132] According to the method of the present invention, a comparative metal-supported catalyst is prepared as follows, which contains 3 wt% palladium as a supported platinum group metal:

[0133] The use of commercially available cerium dioxide (see Ce4 in Table 1) to prepare this metal-supported catalyst has been considered. Ce4 is commercially available cerium dioxide (purchased from Sigma-Aldrich, reference number 544841-25G, lot number MKCK1143) exhibiting an average particle size of 20-30 nm (see Table 1). Figure 1 HRTEM image of Ce4 in the middle, 40 m 2 / g BET surface area and the measured molar ratio of surface oxygen to cerium (obtained by H2-TPR, see [reference]). Figure 2 (Ce4 in the middle).

[0134] 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 (pre-placed on a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The flat-bottomed porcelain crucible containing the wet solid was then 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 completely dry.

[0135] For this metal-support, Pd / O 表面 The parameter is 0.86, a value that takes into account the amount of Pd incorporated (3 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.056 (obtained from H2-TPR, see...). Figure 2 The estimate is based on both Ce4 and Ce4.

[0136] The resulting dry solids were then granulated (particle size: 0.2-0.4 mm) at 4 bar using a manual hydraulic press. Subsequently, the granules were heat-treated using a vertical flow bed reactor. (Right now (Calcination). Then, 150 mg of the obtained granulated Ce4 material containing 3% Pd by weight was calcined at 650°C with an air flow of 175 mL / min for 4 h (heating slope 2°C / min). Finally, the sample was cooled in an air flow.

[0137] Example 5 - Exemplary Ce2 ​​metal-supported catalyst (Pd / O) containing 5% by weight Pd 表面 Synthesis of (=0.93)

[0138] According to the method of the present invention, an exemplary metal-supported catalyst according to the present invention is prepared as follows, which contains 5% by weight palladium as a supported platinum group metal:

[0139] The use of commercially available cerium dioxide (see Ce2 in Table 1) for the preparation of this metal-supported catalyst has been considered. Ce2 is commercially available cerium dioxide (purchased from Solvay, reference number ITQ 3A, lot number 0633984) exhibiting an average particle size of 7–9 nm (see Table 1). Figure 1 HRTEM image of Ce2 in 98 m 2 / g BET surface area and the measured molar ratio of surface oxygen to cerium of 0.087 (obtained by H2-TPR, see [reference]). Figure 2 (Ce2 in the middle).

[0140] Using a syringe, 1.4 g of tetraamminepalladium(II) nitrate solution (10% by weight H₂O solution, purchased from Merck; CAS 13601-08-6) was added dropwise to 1 g of Ce₂ support (which had been pre-placed on a flat-bottomed porcelain crucible). Homogenization was then performed manually using a spatula. The flat-bottomed porcelain crucible containing the wet solid was then placed on top of a hot plate and dried at 100°C. During this drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0141] For this metal-support, Pd / O 表面 The parameter is 0.93, a value that takes into account the amount of Pd incorporated (5 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.087 (obtained from H2-TPR, see...). Figure 2 The estimate is based on both Ce2 and Ce2.

[0142] The resulting dry solids were then granulated (particle size: 0.2-0.4 mm) at 4 bar using a manual hydraulic press. Subsequently, the granules were heat-treated using a vertical flow bed reactor. (Right now (Calcination). Then, 150 mg of the obtained granulated Ce2 material containing 5% Pd by weight was calcined at 650°C with an air flow of 175 mL / min for 4 h (heating slope 2°C / min). Finally, the sample was cooled in an air flow.

[0143] Example 6 - Comparative Ce2 metal-supported catalyst (Pd / O2) containing 1 wt% Pd 表面 Synthesis of (=0.19)

[0144] The comparative metal-supported catalyst according to the invention is prepared as follows, comprising 5% by weight palladium as a supported platinum group metal:

[0145] The use of commercially available cerium dioxide (see Ce2 in Table 1) for the preparation of this metal-supported catalyst has been considered. Ce2 is commercially available cerium dioxide (purchased from Solvay, reference number ITQ 3A, lot number 0633984) exhibiting an average particle size of 7–9 nm (see Table 1). Figure 1 HRTEM image of Ce2 in 98 m 2 / g BET surface area and the measured molar ratio of surface oxygen to cerium of 0.087 (obtained by H2-TPR, see [reference]). Figure 2 (Ce2 in the middle).

[0146] 2.28 g of tetraamminepalladium(II) nitrate solution (10 wt% H₂O solution, 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 (which had been pre-placed on a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula.

[0147] Next, the flat-bottomed porcelain crucible containing the wet solid was placed on top of a hot plate and dried at 100°C. During this drying process, the wet solid was continuously homogenized with a scraper every minute until it was completely dry.

[0148] For this metal-support, Pd / O 表面 The parameter is 0.19, a value that takes into account the amount of Pd incorporated (1 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.087 (obtained from H2-TPR, see...). Figure 2 The estimate is based on both Ce2 and Ce2.

[0149] The resulting dry solids were then granulated (particle size: 0.2-0.4 mm) at 4 bar using a manual hydraulic press. Subsequently, the granules were heat-treated using a vertical flow bed reactor. (Right now (Calcination). Then, 150 mg of the obtained granulated Ce2 material containing 1% Pd by weight was calcined at 650°C with an air flow of 175 mL / min for 4 h (heating slope 2°C / min). Finally, the sample was cooled in an air flow.

[0150] Example 7 - Exemplary Cel metal-supported catalyst (Pd / O) containing 5% by weight Pd 表面 Synthesis of (=0.58)

[0151] According to the method of the present invention, a comparative metal-supported catalyst is prepared as follows, which contains 5 wt% palladium as a supported platinum group metal:

[0152] The use of commercially available cerium dioxide (see Cel in Table 1) to prepare this metal-supported catalyst has been considered. Cel is commercially available cerium dioxide (purchased from NanoScale Corporation, reference number AC106-011, lot number 06-0117) exhibiting an average particle size of 5-7 nm (see Table 1). Figure 1 HRTEM image of Cel), 73 m 2 / g BET surface area and the measured molar ratio of surface oxygen to cerium (obtained by H2-TPR, see [reference]). Figure 2 (Cel in the middle).

[0153] Using a syringe, 3.4 g of tetraamminepalladium(II) nitrate solution (10% by weight H₂O solution, purchased from Merck; CAS 13601-08-6) was added dropwise to 1 g of Cel support (which had been pre-placed on a flat-bottomed porcelain crucible). Homogenization was then performed manually using a spatula. The flat-bottomed porcelain crucible containing the wet solid was then placed on top of a hot plate and dried at 100°C. During this drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0154] For this metal-support, Pd / O 表面 The parameter is 0.58, a value that takes into account the amount of Pd incorporated (5 wt% Pd) and the previously measured surface oxygen to cerium molar ratio of 0.139 (obtained from H2-TPR, see...). Figure 2 The estimate is based on both Cel and the others.

[0155] The resulting dry solids were then granulated (particle size: 0.2-0.4 mm) at 4 bar using a manual hydraulic press. Subsequently, the granules were heat-treated using a vertical flow bed reactor. (Right now (Calcination). Then, 150 mg of the obtained granulated Cel material containing 5% Pd by weight was calcined at 650°C with an air flow of 175 mL / min for 4 h (heating slope 2°C / min). Finally, the sample was cooled in an air flow.

[0156] Example 8 - Exemplary PdPt-containing Ce2 metal supported catalyst (Pd / O 表面 Synthesis of (=0.66)

[0157] According to the method of the present invention, an exemplary metal-supported catalyst according to the present invention is prepared as follows, comprising 3 wt% palladium and 1 wt% platinum as supported platinum group metals:

[0158] The use of commercially available cerium dioxide (see Ce2 in Table 1) to prepare this metal-supported catalyst has been considered. Ce2 is commercially available cerium dioxide (purchased from Solvay, reference number ITQ. 3A, lot number 0633984) exhibiting an average particle size of 7-9 nm (see Table 1). Figure 1 HRTEM image of Ce2 in 98 m 2 / g BET surface area and the measured molar ratio of surface oxygen to cerium of 0.087 (obtained by H2-TPR, see [reference]). Figure 2 (Ce2 in the middle).

[0159] A mixture of 0.85 g of tetraamminepalladium(II) nitrate solution (10% by weight H₂O solution, purchased from Merck; CAS 13601-08-6) and 0.02 g of tetraammineplatinum(II) nitrate (purchased from Sigma-Aldrich; CAS No. 20634-12-2) was prepared. The resulting solution was then added dropwise to 1 g of Ce₂ support (pre-placed on a flat-bottomed porcelain crucible) using a syringe. Homogenization was then performed manually using a spatula. The flat-bottomed porcelain crucible containing the wet solid was then 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 complete drying was achieved.

[0160] For this metal-support, (RdPt) / O 表面 The parameter is 0.66, a value that takes into account the amount of Pd and Pt incorporated (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...). Figure 2 The estimate is based on both Ce2 and Ce2.

[0161] The resulting dry solids were then granulated (particle size: 0.2-0.4 mm) at 4 bar using a manual hydraulic press. Subsequently, the granules were heat-treated using a vertical flow bed reactor. (Right now (Calcination). Then, 150 mg of the obtained granulated Ce2 material containing 3 wt% Pd and 1 wt% Pt was calcined at 650°C with an air flow of 175 mL / min for 4 h (heating slope 2°C / min). Finally, the sample was cooled in an air flow.

[0162] Example 9 - Exemplary CeZr metal-supported catalyst (Pd / O) containing 5% by weight Pd 表面 Synthesis of (=0.56)

[0163] According to the method of the present invention, an exemplary metal-supported catalyst according to the present invention is prepared as follows, which contains 5% by weight palladium as a supported platinum group metal:

[0164] 66 g of ammonium hydroxide solution (NH4OH, 25% NH3 in H2O solution, Sigma-Aldrich) was dissolved in 134 mL of MilliQ water. Then, 10.42 g of cerium nitrate (Ce(NO3)3·6H2O, Alfa-Aesar) and 1.29 g of zirconium oxynitrate (IV) (ZrONO3, Sigma-Aldrich) were added, and the resulting mixture was stirred for 30 min. Simultaneously, 6 g of hydrogen peroxide solution (50% by weight H2O solution, Sigma-Aldrich) was diluted in 24 g of MilliQ water. This H2O2 solution was then added dropwise to the previous mixture, and the mixture was stirred continuously for 45 min. Afterward, the mixture was washed several times with water and separated by filtration, then dried overnight at 100°C. The obtained solid was introduced into 300 mL of isopropanol, and the mixture was maintained at 100°C under reflux and stirring for 5 h. The solid was recovered by filtration and washed with water, and finally calcined in a muffle furnace at 500°C for 4 h (heating slope 2°C / min).

[0165] The resulting CeZr support exhibits an average particle size of 6-10 nm and a density of 79 μm. 2 The measured molar ratio of / g BET surface area and 0.135 surface oxygen to CeZr (obtained by H2-TPR).

[0166] Using a syringe, 4.4 g of tetraamminepalladium(II) nitrate solution (10% by weight H₂O solution, purchased from Merck; CAS 13601-08-6) was added dropwise to 1 g of CeZr support (which had been pre-placed on a flat-bottomed porcelain crucible). Homogenization was then performed manually using a spatula. The flat-bottomed porcelain crucible containing the wet solid was then placed on top of a hot plate and dried at 100°C. During this drying process, the wet solid was continuously homogenized with a spatula every minute until completely dry.

[0167] For this metal-support, Pd / O 表面 The parameter is 0.56, which is estimated by taking into account both the amount of Pd incorporated (5 wt% Pd) and the previously measured molar ratio of surface oxygen to CeZr of 0.135 (obtained by H2-TPR).

[0168] The resulting dry solids were then granulated (particle size: 0.2-0.4 mm) at 4 bar using a manual hydraulic press. Subsequently, the granules were heat-treated using a vertical flow bed reactor. (Right now(Calcination). Then, 150 mg of the obtained granulated CeZr material containing 5% Pd by weight was calcined at 650°C with an air flow of 175 mL / min for 4 h (heating slope 2°C / min). Finally, the sample was cooled in an air flow.

[0169] Example 10 - 3 wt% Pd / nano-cerium dioxide materials using different nano-cerium dioxide supports (Example) Catalytic evaluation of Example 4)

[0170] The obtained nano-cerium dioxide catalyst containing 3% Pd was tested under wet conditions according to the classic ignition curve experiment (200 to 600°C, see...). Figure 3 Methane combustion reaction tests were conducted at different reaction temperatures.

[0171] For the ignition experiment, the catalyst was first activated with air (100 ml / min) for 1 h. Then, the feed mixture under wet conditions was introduced at a total flow rate of 150 ml / min with the following composition (in N2, 0.1 vol% CH4, 14.0 vol% O2, 6 vol% H2O, GHSV = 18000 ml / g). 催化剂 h) The catalyst was introduced. The reaction temperature was gradually increased between 200 and 600°C. The methane combustion activity was measured at each temperature under steady-state conversion conditions by gas chromatography (Agilent Technologies 7890B.GC system, equipped with a TCD detector, using an SP2100 pre-column and PLOTQ and Molsieve 5A capillary columns).

[0172] Compared with the comparative catalysts prepared according to Examples 3 and 4 of the present invention, the catalysts synthesized according to Examples 1 and 2 of the present invention were found to perform better for the methane combustion reaction under wet conditions (see Figure 3 It is worth noting that both catalysts have a Pd / O ratio of approximately 0.56–0.58. 表面 The parameter values ​​are between 6 and 9 nm in particle size and between 90 and 120 m² / g in BET surface area. The catalyst prepared according to Example 3 exhibits a low Pd / O ratio of approximately 0.35. 表面 The parameter values, while the catalyst prepared according to Example 4 exhibits a higher Pd / O ratio of approximately 0.86. 表面 The parameter values ​​are valid, but the particle size exceeds 20 nm and the BET surface area is less than 50 m². 2 / g.

[0173] In addition to ignition type experiments at different temperatures, the long-term stability of these catalysts under dynamic high-temperature conditions (between 400 and 600°C) exposed to a wet feed for extended operating time (TOS) was evaluated. For the steady-state long TOS experiment, the catalysts were first activated with air (100 ml / min) for 1 h, and then subjected to a feed mixture under dry conditions (150 ml / min; in N2, 0.1 vol% CH4, 14.0 vol% O2; GHSV = 180000 ml / g). 催化剂 (h) Activation: The reaction temperature is increased to 400°C at a heating slope of approximately 14°C / min and maintained at 400°C for 1 h under dry conditions. At this point, the feed is changed to wet conditions (in N2, 0.1 vol% CH4, 14.0 vol% O2, 6 vol% H2O; GHSV = 180000 ml / g). 催化剂 The reaction was carried out for approximately 40 h. Later, the dynamic high-temperature changes were investigated by raising the reaction temperature to 600°C for 1 h under humid conditions, followed by lowering it to 400°C and holding it for another 1 h. Methane conversion was measured by gas chromatography (using an Agilent Technologies 7890B.GC system equipped with a TCD detector, an SP2100 pre-column, and PLOTQ and Molsieve 5A capillary columns).

[0174] As observed in previous ignition experiments, the two catalysts found to exhibit superior steady-state long TOS performance under 400°C wet conditions are based on...

[0175] The catalysts prepared in Examples 1 and 2 exhibited properties that were not only effective at 400°C under humid conditions for 40 h (see Example 2). Figure 4 Part (I) Examples 1 and 2), and after being subjected to dynamic high temperature changes between 400 and 600°C (see Figure 4 In Part (III) of Examples 1 and 2), the methane conversion values ​​remained almost unchanged. These results clearly highlight the high activity and stability provided by these two catalysts containing 3% Pd by weight, wherein the nano-cerium dioxide support exhibits a particle size between 6-9 nm and 90-120 nm. 2 The BET surface area between / g and approximately 0.6 Pd / O 表面 value.

[0176] Example 11 - Catalytic evaluation of Ce2 support with different metal contents (Examples 1, 5, and 6)

[0177] To observe the effect of metal content, different amounts of Pd were deposited on a Ce2 support. (Right now,The catalysts were 1% by weight (1% by weight of Example 6, 3% by weight of Example 1, and 5% by weight of Example 5), and then subjected to a simple activation treatment in air at 650°C. The Pd / O ratios of the three catalysts were calculated. 表面 The parameters yielded the following values: 0.19 (1 wt% Pd, Example 6), 0.56 (3 wt% Pd, Example 1), and 0.93 (5 wt%, Example 5).

[0178] These three catalysts were first tested under wet conditions according to classic ignition type experiments (details of the ignition type reaction tests are provided in Example 10). Increasing the amount of Pd in ​​the catalyst led to an improvement in the methane conversion curve (see...). Figure 5 Interestingly, the most significant differences were observed when evaluating the long TOS of these catalysts under wet feed and dynamic high-temperature reaction conditions (see Example 10 for experimental details on steady-state long TOS experiments). Figure 6 As shown, the two catalysts prepared according to Examples 1 and 5 (with Pd contents of 3% and 5% respectively) exhibited similar catalytic performance at 400°C and under wet conditions to the results obtained during the short-start type experiment at 400°C (see Figure 5 In addition, both catalysts showed performance not only at 400°C under humid conditions for 40 h (see...) Figure 6 Part (I)), and after being subjected to dynamic high-temperature changes between 400 and 600°C (see Part (I)). Figure 6 In part (III)), the methane conversion value remained almost unchanged. The calculated turnover frequency (TOF, methane conversion normalized to metal content) of the two catalysts prepared according to Examples 1 and 5 of the present invention was found to be 8.4 and 9.6 h, respectively. 1 (Calculated from long TOS experiments after 2000 min). These results clearly highlight the high activity and stability provided by the nano-cerium dioxide support, even when the metal loading is increased to 5 wt%. However, after maintaining a long TOS time at 400°C in the presence of vapor, nano-cerium dioxide containing 1 wt% Pd clearly showed a lower methane conversion (see...). Figure 6 (Example 6 in Part (I)). In fact, the calculated TOF value of this catalyst was low after 2000 min (0.4 h). 1 The low Pd / O ratio is highlighted. 表面 The negative effect of (-0.2) is less than that of the nano-cerium dioxide support used in the catalyst, even though the nano-particle size is between 7 and 9 and the particle size is 97 μm. 2 / g of BET surface area.

[0179] Example 12 - Catalytic evaluation of different metal contents in Cel support (Examples 3 and 7)

[0180] To observe the effect of metal content on another nano-cerium dioxide support, Cel, which has a higher measured surface oxygen content (see Table 1), different amounts of Pd were deposited on this support. (Right now, The catalysts were used in Example 3 (3 wt%) and Example 7 (5 wt%), followed by a simple activation treatment in air at 650°C. The Pd / O ratios of the two catalysts were calculated. 表面 The parameters yielded the following values: 0.35 (3 wt% Pd, Example 3) and 0.58 (5 wt%, Example 7).

[0181] like Figure 7 As shown, when testing long TOS-type experiments under humid conditions and dynamic high-temperature variations (see experimental details of steady-state long TOS in Example 10), the catalyst prepared according to Example 7 achieved a significantly higher methane conversion rate compared to the catalyst prepared according to Example 3. For the catalyst prepared according to Example 7 of the present invention, the TOF value calculated under humid conditions and at 400°C for 2000 min was approximately 7.0 h. 1 This value is close to the calculated TOF value (approximately 8.4 h) of the catalyst prepared under the same conditions according to Example 1. 1 The two catalysts exhibit similar Pd / O ratios. 表面 The ratio (approximately 0.56 to 0.58). Another important conclusion from the catalytic results obtained when testing the catalyst prepared according to Example 7 under long TOS conditions was that the catalyst exhibited excellent stability after being subjected to dynamic high-temperature variations (400-600-400°C) under wet conditions (see...). Figure 7 Example 7 in Part (III).

[0182] Example 13 - Catalytic evaluation of PdPt in Ce2 support (Example 8)

[0183] The methane conversion achieved by the bimetallic catalyst prepared according to Example 8 of the present invention in a long TOS-type experiment under wet conditions (see experimental details of steady-state long TOS in Example 10) shows excellent stability not only after 40 hours of reaction (see... Figure 8 It also exhibits similar catalytic performance to the catalyst prepared according to Example 1.

[0184] Example 14 - Catalytic evaluation of Pd in ​​CeZr support (Example 9)

[0185] The methane conversion achieved under wet conditions in a long TOS-type experiment using the CeZr catalyst containing 5 wt% Pd prepared according to Example 9 (see Experimental Details of Steady-State Long TOS in Example 10) exhibited excellent stability after 40 hours of reaction (see...). Figure 8 ), and has a similar Pd content and Pd / O ratio as prepared according to Example 7. 表面 The catalyst exhibits similar catalytic performance to the one mentioned above.

Claims

1. A method for obtaining a metal-supported catalyst, wherein the method is characterized by comprising the following steps: a) Adding at least one loaded transition metal (M) selected from any of Groups 5 to 11 of the periodic table to a support material, wherein the support material comprises at least one oxide selected from the group consisting of cerium dioxide, cerium dioxide-based mixed oxides and any combination thereof; b) Drying, preferably under homogenization conditions; and c) Heat-treat the solid obtained in step b) at a temperature of about 250°C to about 850°C; The at least one oxide therein exists substantially in crystalline form; has an average particle size of 5 to 20 nm, as determined by HRTEM; and exhibits a particle size of 50 to 140 nm. 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours; and The molar ratio (M / O) of the at least one loaded transition metal (M) to the surface oxygen in the carrier material is... 表面 The value is 0.4-1.4, as determined by H2-TPR.

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

3. The method according to claim 2, wherein the at least one loaded transition metal (M) is added to the carrier material by wet impregnation, initial volume impregnation, or deposition-precipitation.

4. The method according to any one of claims 1-3, wherein the at least one loaded 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 any one of claims 1-4, wherein the at least one loaded transition metal (M) is added in step a) in the form of a metal salt or a metal complex or as a metal-based alloy.

6. The method according to any one of claims 1-5, wherein the carrier material comprises at least one cerium dioxide-based mixed oxide, wherein the at least one cerium dioxide-based mixed oxide comprises less than 40 mol% of at least one metallic element capable of forming the cerium dioxide-based mixed oxide.

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

8. The method according to any one of claims 1-7, wherein after step b) but before step c), the method further comprises a step in which the dried solid obtained in step b) is: - Applied to or on an inert substrate, preferably a honeycomb inert substrate; or - Formed into granules.

9. The method according to any one of claims 1-8, wherein the heat-treated solid produced in step c) is subjected to a reduction step, in which the solid is contacted with a reducing agent selected from the group consisting of: reducing gas, hypophosphite, borohydride salt, hydrazine, formic acid, formaldehyde, citric acid and any combination thereof.

10. A metal-supported catalyst for methane combustion under wet conditions, characterized in that... Include: - A carrier material comprising at least one oxide selected from the group consisting of cerium dioxide, cerium dioxide-based mixed oxides, and any combination thereof; and - At least one loaded transition metal (M) selected from any of Groups 5 to 11 of the periodic table. The at least one oxide therein exists substantially in crystalline form; has an average particle size of 5 to 20 nm, as determined by HRTEM; and exhibits a particle size of 50 to 140 nm. 2 The specific surface area per g, as measured by the BET method using nitrogen adsorption after activation at 400°C under vacuum for 3 hours; and The metal-supported catalyst comprises 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. The metal-supported catalyst according to claim 10, which can be obtained by the method according to any one of claims 1-9.

12. A method for methane combustion under wet conditions, characterized in that... Includes the following steps: a) Introducing a metal-supported catalyst as defined in any one of claims 10-11 into the reactor; b) Feeding the reactor with a gaseous reaction feed comprising methane, 5% to 15% (v / v) water, and at least one inert gas, wherein the sum of all components in the gaseous reaction feed is 100% (v / v); and c) Keep the metal-supported catalyst in contact with the gaseous reaction feed in the reactor for a time and temperature sufficient to allow methane combustion to occur.

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

14. The method of claim 13, wherein the metal-supported catalyst undergoes an oxidation step after the reduction step, and wherein the oxidation step is performed before step b), before step a), simultaneously with step a), or after step a).

15. Use of the metal-supported catalyst as defined in any one of claims 10-11 in methane combustion, preferably in methane combustion under wet conditions.

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