Catalyst for oxidizing low-concentration gas in coal mine and preparation method of catalyst

Abstract

The invention provides a catalyst for oxidizing low-concentration gas in a coal mine and a preparation method of the catalyst. The catalyst comprises the following components in percentage by mass: 40%-60% of an active carrier, 3%-10% of an active substance and 37%-50% of a forming carrier, the active carrier is a TiO2-WO3 bimetallic oxide system, the TiO2 component accounts for 80%-90% of the total mass of the active carrier, and the WO3 component accounts for 10%-20% of the total mass of the active carrier; the active component of the active substance is Pt-V2O5-Li2SO4, Pt accounts for 5%-15% of the total mass of the active component, V2O5 accounts for 25%-35% of the total mass of the active component, and Li2SO4 accounts for 60% of the total mass of the active component. The forming carrier is a ceramic fiber board. According to the invention, a differential atmosphere roasting and layered deposition coating preparation method is adopted, and the catalyst with obvious oxidability to low-concentration gas is finally obtained. And the ecological environment problem caused by gas emission of coal mine enterprises is effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of environmental catalysis technology, specifically relating to a catalyst for the oxidation of low-concentration methane in coal mines and its preparation method. Background Technology

[0002] my country is a country rich in coal but poor in oil. Its proven coal reserves account for 13.3% of the world's total, ranking second in recoverable reserves. The coal mining process generates up to 10 billion cubic meters of methane gas annually through fugitive emissions. The main component of this gas is methane, and methane's greenhouse effect is 21 times that of carbon dioxide. The continuous accumulation of methane intensifies the greenhouse effect, leading to changes in water-related factors affecting climate, such as rising global temperatures and global warming. This, in turn, results in rising sea levels and a series of changes in the Earth's ecosystem. Studies have shown that temperatures in North China will be approximately 0.85°C warmer by 2030 than in 1995, resulting in about 0.6% more precipitation than in 1995. This explains the increased frequency of heavy rainfall and floods in recent years. Summary of the Invention

[0003] The purpose of this invention is to provide a catalyst for the oxidation of low-concentration methane in coal mines and its preparation method, which effectively solves the ecological and environmental problems caused by methane emissions from coal mining enterprises.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A catalyst for the oxidation of low-concentration methane in coal mines, comprising, by mass percentage: an active support, an active substance, and a molded support, wherein the active support comprises 40%–60% by mass, the active substance comprises 3%–10% by mass, and the molded support comprises 37%–50% by mass.

[0006] The active support is a TiO2-WO3 bimetallic oxide system, wherein the TiO2 component accounts for 80% to 90% of the total mass of the active support, and the WO3 component accounts for 10% to 20% of the total mass of the active support;

[0007] The active material is Pt-V2O5-Li2SO4, wherein Pt accounts for 5% to 15% of the total mass of the active material, V2O5 accounts for 25% to 35% of the total mass of the active material, and Li2SO4 accounts for 60% of the total mass of the active material.

[0008] The TiO2 in the active carrier is anatase TiO2, with a TiO2 content ≥98%, impurity element content ≤2%, and a specific surface area of ​​250-320 m². 2 / g, pore volume ≥0.45cc / g, sulfate impurity content ≤1.0%, chloride impurity content ≤0.5%;

[0009] The WO3 in the active carrier is obtained by thermal decomposition of ammonium tungstate, with an ammonium tungstate WO3 content ≥90%, water-insoluble matter ≤0.5%, and pH value 2.5~4.5.

[0010] Li2SO4 in the active material is a co-catalytic component, and Pt-V2O5 is the main catalytic component.

[0011] The active material contains platinum nitrate as the Pt precursor salt, ammonium metavanadate as the V2O5 precursor salt, high-purity lithium sulfate monohydrate as the Li2SO4, Na2O content ≤20ppm, and K2O content ≤10ppm.

[0012] The molding carrier is a ceramic fiber board.

[0013] The present invention relates to a method for preparing a catalyst for the oxidation of low-concentration methane in coal mines, comprising the following steps:

[0014] 1) Powder preparation: Ammonium tungstate in the formula ratio is dissolved in deionized water to form an ammonium tungstate solution. TiO2 in the formula ratio is added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry is ground for 24 hours, then dried and calcined to form mixed powder A. The drying temperature is 80℃ for 6 hours, and the calcination temperature is 260℃ for 2 hours. Li2SO4 is deposited onto mixed powder A by liquid phase deposition. Li2SO4 is dissolved in deionized water according to the formula ratio. Mixed powder A is added to the Li2SO4 solution. The temperature of the mixing system is maintained at 60-80℃ and the stirring time is 24 hours to end the liquid phase deposition step. The mixed system is filtered to remove the supernatant. The filtered mixture is dried at 120℃ for 2 hours and calcined at 550℃ to form mixed powder B.

[0015] 2) Preparation of Pt and V2O5 supported powder: The V2O5 precursor salt and Pt precursor salt in the formula ratio were dissolved in deionized water to form a mixed solution. Mixed powder B was added to the mixed solution under stirring to form a mixed slurry. The mixed slurry was heated to 60℃, and oxalic acid, a reducing agent, was added under stirring to reduce the valence state of V to +4. The reduction reaction lasted for 6h to 12h, and some Pt ​​was reduced to nanoparticles Pt. Then, the powder was filtered, and the obtained filter cake was dried and calcined under a differential atmosphere. The drying temperature was 120℃ and the drying time was 2h. Differential atmosphere calcination: The dried powder was divided into two equal parts. One part was calcined under a nitrogen atmosphere with an oxygen content of <0.5% at a calcination temperature of 400℃ and a calcination time of 2h to prepare catalyst powder CA. The other part was calcined under an air atmosphere at a calcination temperature of 550℃ and a calcination time of 2h to prepare catalyst powder CB.

[0016] 3) Catalyst coating preparation:

[0017] 1. Preparation of catalyst layer CA coating: Water, powdered CA and anionic surfactant are mixed and stirred to form a mixed slurry. The pH of the slurry is adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry is adjusted using alkaline substances such as ammonia or acidic substances such as nitric acid. The slurry is coated onto a molded carrier using an industrial vacuum coating machine to prepare catalyst W.

[0018] 2. Preparation of CB coating on catalyst layer: Water, powdered CB and anionic surfactant are mixed and stirred to form a mixed slurry. The pH of the slurry is adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry is adjusted using alkaline substances such as ammonia or acidic substances such as nitric acid. The slurry is coated onto the catalyst W using an industrial vacuum coating machine, and then dried and calcined. The drying temperature is 80℃ for 2 hours, and the calcination temperature is 350℃. After calcination, a double-layered catalyst is obtained, which is used for the oxidation of low-concentration methane in coal mines.

[0019] The anionic surfactant is a sulfonate surfactant.

[0020] The catalyst has a bilayer component distribution, with CB catalyst powder distributed in the outer layer and CA catalyst powder distributed in the inner layer.

[0021] The beneficial effects of this invention are:

[0022] (1) The catalyst of this invention has significant resistance to sulfur poisoning and can be applied to the catalytic oxidation treatment of high-sulfur gas. Traditional noble metal-based catalysts are either completely zero-valent catalysts or all oxide catalysts. Although they have a certain ability to resist sulfur poisoning, rapid sulfur poisoning occurs in the oxidation process of high-sulfur gas. The technical solution of this invention adopts a partial reduction technology to distribute the active noble metal Pt into a mixture of zero-valent Pt and PtO, which increases the transfer rate of active oxygen in the gas oxidation process, reduces the rate of sulfur binding with noble metal, and avoids catalyst poisoning and deactivation.

[0023] (2) The catalyst of this invention exhibits very high oxidation activity for low-concentration methane. It is well known that methane molecules have a stable structure, making catalytic oxidation difficult. Traditional methane oxidation catalysts have an activation temperature of 450°C and a T90 (the reaction temperature at which 90% of methane is completely oxidized) close to 500°C. The technical solution of this invention employs a layered coating technique. Different valence states of V oxides in different catalyst layers provide lattice oxygen for the oxidation reaction, accelerating the methane oxidation reaction rate and enhancing the catalytic activity of methane oxidation. The catalyst provided by this invention has an activation temperature of 360°C for methane oxidation and a T90 (the reaction temperature at which 90% of methane is completely oxidized) of 430°C, significantly improving catalytic performance compared to traditional methane oxidation catalysts. Furthermore, the lattice oxygen provider is a sulfur-resistant V oxide, eliminating the sulfur poisoning problem that occurs with conventional methane oxidation catalysts that use Ce oxides to provide lattice oxygen.

[0024] (3) The catalyst of the present invention has good selectivity. Traditional methane oxidation catalysts do not oxidize methane completely, producing a large amount of CO gas that pollutes the environment. The catalyst provided by the present invention has a co-catalytic Li2SO4 component that increases the catalytic activity of methane oxidation while having very high selectivity for CO2, thus eliminating the problem of incomplete methane oxidation. Detailed Implementation

[0025] Example 1:

[0026] This embodiment describes a catalyst for the oxidation of low-concentration methane in coal mines. The specific preparation method includes the following steps:

[0027] 1) Powder preparation: 0.19 kg of ammonium tungstate (WO3 accounting for 10% of the active carrier) was dissolved in 15 kg of deionized water to form an ammonium tungstate solution. 1.53 kg of TiO2 (TiO2 accounting for 90% of the active carrier) was added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry was ground for 24 h, then dried and calcined to form mixed powder A (active carrier mass percentage 50%). The drying temperature was 80℃ for 6 h, and the calcination temperature was 260℃ for 2 h. Liquid phase deposition was then used. Li2SO4 was deposited onto mixed component A. 0.204 kg of Li2SO4 (Li2SO4 accounts for 60% of the total active component) was dissolved in 15 kg of deionized water. Mixed powder A was added to the Li2SO4 solution. The temperature of the mixing system was maintained at 60-80℃ and the stirring time was 24 h to end the liquid phase deposition step. After filtering the mixing system, the supernatant was removed. The filtered mixture was dried at 120℃ for 2 h and calcined at 550℃ to form 1.904 kg of mixed powder B.

[0028] 2) Preparation of Pt and V₂O₅ loading: 0.14 kg of ammonium metavanadate (V₂O₅ accounts for 30% of the total active component) and 0.4 kg of 8.5% platinum nitrate solution (Pt accounts for 10% of the total active component) were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring to form a mixed slurry. The mixed slurry was heated to 60°C, and 0.2 kg of oxalic acid, a reducing agent, was added while stirring to reduce the valence state of V to +4. The reduction reaction continued for 6 hours, controlling the reduction of some Pt ​​to nanoparticle Pt. The mixture was then filtered, and the resulting filter cake was dried and calcined under differential atmosphere.

[0029] 1. Drying temperature 120℃, drying time 2h, 2.64Kg of dried powder obtained;

[0030] 2. Differential atmosphere calcination. 1.32 kg of dried powder was calcined in a nitrogen atmosphere with an oxygen content of <0.5%, at a calcination temperature of 400℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CA; another 1.32 kg of powder was calcined in an air atmosphere at a calcination temperature of 550℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CB.

[0031] 3) Catalyst coating preparation:

[0032] 1. Preparation of the catalyst layer CA coating: 2 kg of water, 1.02 kg of powdered CA, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. Using an industrial vacuum coating machine, the slurry was coated onto a 1.36 kg molded carrier (ceramic fiber plate) to prepare catalyst W.

[0033] 2. Preparation of CB Coating for Catalyst Layer: 2 kg of water, 1.02 kg of powdered CB, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry was adjusted using alkaline ammonia or acidic nitric acid. Using an industrial vacuum coating machine, the slurry was coated onto the catalyst W, followed by drying and calcination. The drying temperature was 80℃ for 2 hours, and the calcination temperature was 350℃. After calcination, a double-layered catalyst was obtained for use in low-concentration methane in coal mines.

[0034] Example 2:

[0035] This embodiment describes a catalyst for the oxidation of low-concentration methane in coal mines. The specific preparation method includes the following steps:

[0036] 1) Powder preparation: 0.092 kg of ammonium tungstate (WO3 accounting for 10% of the active carrier) was dissolved in 15 kg of deionized water to form an ammonium tungstate solution. 0.756 kg of TiO2 (TiO2 accounting for 90% of the active carrier) was added to the ammonium tungstate solution to form a mixed slurry. This mixed slurry was ground for 24 hours, then dried and calcined to form mixed powder A (active carrier mass percentage 37%). The drying temperature was 80℃ for 6 hours, and the calcination temperature was 260℃ for 2 hours. Liquid phase precipitation was used... Li2SO4 was deposited onto mixed component A by deposition. 0.042 kg of Li2SO4 (Li2SO4 accounts for 60% of the total active component) was dissolved in 15 kg of deionized water. Mixed powder A was added to the Li2SO4 solution. The temperature of the mixing system was maintained at 60-80℃ and the stirring time was 24 h to end the liquid phase deposition step. After filtering the mixing system, the supernatant was removed. The filtered mixture was dried at 120℃ for 2 h and calcined at 550℃ to form 0.88 kg of mixed powder B.

[0037] 2) Preparation of Pt and V₂O₅ loading: 0.027 kg of ammonium metavanadate (V₂O₅ accounts for 30% of the total active component) and 0.08 kg of 8.5% platinum nitrate solution (Pt accounts for 10% of the total active component) were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring to form a mixed slurry. The mixed slurry was heated to 60°C, and 0.2 kg of oxalic acid, a reducing agent, was added while stirring to reduce the valence state of V to +4. The reduction reaction continued for 6 hours, controlling the reduction of some Pt ​​to nanoparticle Pt. The mixture was then filtered, and the resulting filter cake was dried and calcined under differential atmosphere.

[0038] 1. Drying temperature 120℃, drying time 2h, to obtain 1.189Kg of dried powder;

[0039] 2. Differential atmosphere calcination. 0.594 kg of dried powder was calcined in a nitrogen atmosphere with an oxygen content of <0.5%, at a calcination temperature of 400℃ for 2 hours to obtain 0.455 kg of catalyst powder CA; another 0.594 kg of powder was calcined in an air atmosphere at a calcination temperature of 550℃ for 2 hours to obtain 0.455 kg of catalyst powder CB.

[0040] 3) Catalyst coating preparation:

[0041] 1. Preparation of the catalyst layer (CA coating): 2 kg of water, 0.455 kg of powdered CA, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. Using an industrial vacuum coating machine, the slurry was coated onto a 1.36 kg molded carrier (ceramic fiber plate) to prepare catalyst W.

[0042] 2. Preparation of CB Coating for Catalyst Layer: 2 kg of water, 0.455 kg of powdered CB, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry was adjusted using alkaline ammonia or acidic nitric acid. Using an industrial vacuum coating machine, the slurry was coated onto the catalyst W, followed by drying and calcination. The drying temperature was 80℃ for 2 hours, and the calcination temperature was 350℃. After calcination, a double-layered catalyst was obtained. This catalyst is used for the oxidation of low-concentration methane in coal mines.

[0043] Example 3:

[0044] This embodiment describes a catalyst for the oxidation of low-concentration methane in coal mines. The specific preparation method includes the following steps:

[0045] 1) Powder preparation: 0.19 kg of ammonium tungstate (WO3 accounting for 10% of the active carrier) was dissolved in 15 kg of deionized water to form an ammonium tungstate solution. 1.53 kg of TiO2 (TiO2 accounting for 90% of the active carrier) was added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry was ground for 24 h, then dried and calcined to form mixed powder A (active carrier mass percentage 50%). The drying temperature was 80℃ for 6 h, and the calcination temperature was 260℃ for 2 h. Liquid phase deposition was then used. Li2SO4 was deposited onto mixed component A. 0.204 kg of Li2SO4 (Li2SO4 accounts for 60% of the total active component) was dissolved in 15 kg of deionized water. Mixed powder A was added to the Li2SO4 solution. The temperature of the mixing system was maintained at 60-80℃ and the stirring time was 24 h to end the liquid phase deposition step. After filtering the mixing system, the supernatant was removed. The filtered mixture was dried at 120℃ for 2 h and calcined at 550℃ to form 1.904 kg of mixed powder B.

[0046] 2) Preparation of Pt and V₂O₅ loading: 0.11 kg of ammonium metavanadate (V₂O₅ accounts for 25% of the total active component) and 0.62 kg of 8.5% platinum nitrate solution (Pt accounts for 15% of the total active component) were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring to form a mixed slurry. The mixed slurry was heated to 60°C, and 0.2 kg of oxalic acid, a reducing agent, was added while stirring to reduce the valence state of V to +4. The reduction reaction continued for 6 hours, controlling the reduction of some Pt ​​to nanoparticle Pt. The mixture was then filtered, and the resulting filter cake was dried and calcined under differential atmosphere.

[0047] 1. Drying temperature 120℃, drying time 2h, 2.83Kg of dried powder obtained;

[0048] 2. Differential atmosphere calcination: 1.41 kg of dried powder was calcined in a nitrogen atmosphere with an oxygen content of <0.5%, at a calcination temperature of 400℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CA; another 1.41 kg of powder was calcined in an air atmosphere at a calcination temperature of 550℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CB.

[0049] 3) Catalyst coating preparation:

[0050] 1. Preparation of the catalyst layer CA coating: 2 kg of water, 1.02 kg of powdered CA, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. Using an industrial vacuum coating machine, the slurry was coated onto a 1.36 kg molded carrier (ceramic fiber plate) to prepare catalyst W.

[0051] 2. Preparation of CB Coating for Catalyst Layer: 2 kg of water, 1.02 kg of powdered CB, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry was adjusted using alkaline ammonia or acidic nitric acid. Using an industrial vacuum coating machine, the slurry was coated onto the catalyst W, followed by drying and calcination. The drying temperature was 80℃ for 2 hours, and the calcination temperature was 350℃. After calcination, a double-layered catalyst was obtained, which is used as a catalyst for the oxidation of low-concentration methane in coal mines.

[0052] Example 4:

[0053] This embodiment describes a catalyst for the oxidation of low-concentration methane in coal mines. The specific preparation method includes the following steps:

[0054] 1) Powder preparation: 0.19 kg of ammonium tungstate (WO3 accounting for 10% of the active carrier) was dissolved in 15 kg of deionized water to form an ammonium tungstate solution. 1.53 kg of TiO2 (TiO2 accounting for 90% of the active carrier) was added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry was ground for 24 h, then dried and calcined to form mixed powder A (active carrier mass percentage 50%). The drying temperature was 80℃ for 6 h, and the calcination temperature was 260℃ for 2 h. Liquid phase deposition was then used. Li2SO4 was deposited onto mixed component A. 0.204 kg of Li2SO4 (Li2SO4 accounts for 60% of the total active component) was dissolved in 15 kg of deionized water. Mixed powder A was added to the Li2SO4 solution. The temperature of the mixing system was maintained at 60-80℃ and the stirring time was 24 h to end the liquid phase deposition step. After filtering the mixing system, the supernatant was removed. The filtered mixture was dried at 120℃ for 2 h and calcined at 550℃ to form 1.904 kg of mixed powder B.

[0055] 2) Preparation of Pt and V₂O₅ loading: 0.11 kg of ammonium metavanadate (V₂O₅ accounts for 25% of the total active component) and 0.62 kg of 8.5% platinum nitrate solution (Pt accounts for 15% of the total active component) were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring to form a mixed slurry. The mixed slurry was heated to 60°C, and 0.2 kg of oxalic acid, a reducing agent, was added while stirring to reduce the valence state of V to +4. The reduction reaction continued for 8 hours, controlling the reduction of some Pt ​​to nanoparticle Pt. The mixture was then filtered, and the resulting filter cake was dried and calcined under differential atmosphere.

[0056] 1. Drying temperature 120℃, drying time 2h, 2.83Kg of dried powder obtained;

[0057] 2. Differential atmosphere calcination. 1.41 kg of dried powder was calcined in a nitrogen atmosphere with an oxygen content of <0.5%, at a calcination temperature of 400℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CA; another 1.41 kg of powder was calcined in an air atmosphere at a calcination temperature of 550℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CB.

[0058] 3) Catalyst coating preparation:

[0059] 1. Preparation of the catalyst layer (CA coating): 2 kg of water, 1.02 kg of powdered CA, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. Using an industrial vacuum coating machine, the slurry was coated onto a 1.36 kg molded carrier to prepare catalyst W.

[0060] 2. Preparation of CB Coating for Catalyst Layer: 2 kg of water, 1.02 kg of powdered CB, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry was adjusted using alkaline ammonia or acidic nitric acid. Using an industrial vacuum coating machine, the slurry was coated onto the catalyst W, followed by drying and calcination. The drying temperature was 80℃ for 2 hours, and the calcination temperature was 350℃. After calcination, a double-layered catalyst was obtained for use in low-concentration methane in coal mines.

[0061] Example 5:

[0062] This embodiment describes a catalyst for the oxidation of low-concentration methane in coal mines. The specific preparation method includes the following steps:

[0063] 1) Powder preparation: 0.19 kg of ammonium tungstate (WO3 accounting for 10% of the active carrier) was dissolved in 15 kg of deionized water to form an ammonium tungstate solution. 1.53 kg of TiO2 (TiO2 accounting for 90% of the active carrier) was added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry was ground for 24 h, then dried and calcined to form mixed powder A (active carrier mass percentage 50%). The drying temperature was 80℃ for 6 h, and the calcination temperature was 260℃ for 2 h. Liquid phase deposition was then used. Li2SO4 was deposited onto mixed component A. 0.204 kg of Li2SO4 (Li2SO4 accounts for 60% of the total active component) was dissolved in 15 kg of deionized water. Mixed powder A was added to the Li2SO4 solution. The temperature of the mixing system was maintained at 60-80℃ and the stirring time was 24 h to end the liquid phase deposition step. After filtering the mixing system, the supernatant was removed. The filtered mixture was dried at 120℃ for 2 h and calcined at 550℃ to form 1.904 kg of mixed powder B.

[0064] 2) Preparation of Pt and V₂O₅ loading: 0.11 kg of ammonium metavanadate (V₂O₅ accounts for 25% of the total active component) and 0.62 kg of 8.5% platinum nitrate solution (Pt accounts for 15% of the total active component) were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring to form a mixed slurry. The mixed slurry was heated to 60℃, and 0.2 kg of oxalic acid, a reducing agent, was added while stirring to reduce the valence of V to +4. The reduction reaction continued for 12 h, controlling the reduction of some Pt ​​to nanoparticle Pt. The mixture was then filtered, and the resulting filter cake was dried and calcined under differential atmosphere.

[0065] 1. Drying temperature 120℃, drying time 2h, 2.83Kg of dried powder obtained;

[0066] 2. Differential atmosphere calcination. 1.41 kg of dried powder was calcined in a nitrogen atmosphere with an oxygen content of <0.5%, at a calcination temperature of 400℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CA; another 1.41 kg of powder was calcined in an air atmosphere at a calcination temperature of 550℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CB.

[0067] 3) Catalyst coating preparation:

[0068] 1. Preparation of the catalyst layer CA coating: 2 kg of water, 1.02 kg of powdered CA, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. Using an industrial vacuum coating machine, the slurry was coated onto a 1.36 kg molded carrier (ceramic fiber plate) to prepare catalyst W.

[0069] 2. Preparation of CB Coating for Catalyst Layer: 2 kg of water, 1.02 kg of powdered CB, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry was adjusted using alkaline ammonia or acidic nitric acid. Using an industrial vacuum coating machine, the slurry was coated onto the catalyst W, followed by drying and calcination. The drying temperature was 80℃ for 2 hours, and the calcination temperature was 350℃. After calcination, a double-layered catalyst was obtained for use in low-concentration methane in coal mines.

[0070] Comparative Example 1 (Replacing the active component V2O5 with conventional CeO2)

[0071] 1) Powder preparation: 0.19 kg of ammonium tungstate (WO3 accounting for 10% of the active carrier) was dissolved in 15 kg of deionized water to form an ammonium tungstate solution. 1.53 kg of TiO2 (TiO2 accounting for 90% of the active carrier) was added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry was ground for 24 h, then dried and calcined to form mixed powder A (active carrier mass percentage 50%). The drying temperature was 80℃ for 6 h, and the calcination temperature was 260℃ for 2 h. Liquid phase deposition was then used. Li2SO4 was deposited onto mixed component A. 0.204 kg of Li2SO4 (Li2SO4 accounts for 60% of the total active component) was dissolved in 15 kg of deionized water. Mixed powder A was added to the Li2SO4 solution. The temperature of the mixing system was maintained at 60-80℃ and the stirring time was 24 h to end the liquid phase deposition step. After filtering the mixing system, the supernatant was removed. The filtered mixture was dried at 120℃ for 2 h and calcined at 550℃ to form 1.904 kg of mixed powder B.

[0072] 2) Preparation of Pt and CeO2 loading: 0.21 kg of cerium nitrate (CeO2 accounting for 25% of the total active component) and 0.62 kg of 8.5% platinum nitrate solution (Pt accounting for 15% of the total active component) were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring to form a mixed slurry. The mixed slurry was heated to 60°C, and 0.2 kg of reducing agent oxalic acid was added while stirring. The reduction reaction continued for 6 hours, controlling the reduction of some Pt ​​to nanoparticle Pt. The mixture was then filtered, and the resulting filter cake was dried and calcined under differential atmosphere.

[0073] 1. Drying temperature 120℃, drying time 2h, 2.93Kg of dried powder obtained;

[0074] 2. Differential atmosphere calcination: 1.45 kg of dried powder was calcined in a nitrogen atmosphere with an oxygen content of <0.5%, at a calcination temperature of 400℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CA; another 1.45 kg of powder was calcined in an air atmosphere at a calcination temperature of 550℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CB.

[0075] 3) Catalyst coating preparation:

[0076] 1. Preparation of the catalyst layer (CA coating): 2 kg of water, 1.02 kg of powdered CA, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. Using an industrial vacuum coating machine, the slurry was coated onto a 1.36 kg molded carrier to prepare catalyst W.

[0077] 2. Preparation of CB Coating for Catalyst Layer: 2 kg of water, 1.02 kg of powdered CB, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry was adjusted using alkaline ammonia or acidic nitric acid. Using an industrial vacuum coating machine, the slurry was coated onto the catalyst W, followed by drying and calcination. The drying temperature was 80℃ for 2 hours, and the calcination temperature was 350℃. After calcination, a double-layered catalyst was obtained, which is used as a catalyst for the oxidation of low-concentration methane in coal mines.

[0078] Comparative Example 2 (replacing the active component Li2SO4 with conventional ZrO2)

[0079] 1) Powder preparation: 0.19 kg of ammonium tungstate (WO3 accounting for 10% of the active carrier) was dissolved in 15 kg of deionized water to form an ammonium tungstate solution. 1.53 kg of TiO2 (TiO2 accounting for 90% of the active carrier) was added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry was ground for 24 h, dried and calcined to form mixed powder A (active carrier mass percentage 50%). The drying temperature was 80℃ for 6 h, and the calcination temperature was 260℃ for 2 h. 0.204 kg of ZrO2 powder (ZrO2 accounting for 60% of the total active component) was dispersed in 15 kg of deionized water. Mixed powder A was added to the ZrO2 dispersion solution. The temperature of the mixing system was maintained at 60-80℃ and the stirring time was 24 h. After filtering the mixing system, the supernatant was removed. The filtered mixture was dried at 120℃ for 2 h and calcined at 550℃ to form 1.904 kg of mixed powder B.

[0080] 2) Preparation of Pt and V₂O₅ loading: 0.11 kg of ammonium metavanadate (V₂O₅ accounts for 25% of the total active component) and 0.62 kg of 8.5% platinum nitrate solution (Pt accounts for 15% of the total active component) were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring to form a mixed slurry. The mixed slurry was heated to 60°C, and 0.2 kg of oxalic acid, a reducing agent, was added while stirring to reduce the valence state of V to +4. The reduction reaction continued for 6 hours, controlling the reduction of some Pt ​​to nanoparticle Pt. The mixture was then filtered, and the resulting filter cake was dried and calcined under differential atmosphere.

[0081] 1. Drying temperature 120℃, drying time 2h, 2.83Kg of dried powder obtained;

[0082] 2. Differential atmosphere calcination. 1.41 kg of dried powder was calcined in a nitrogen atmosphere with an oxygen content of <0.5%, at a calcination temperature of 400℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CA; another 1.41 kg of powder was calcined in an air atmosphere at a calcination temperature of 550℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CB.

[0083] 3) Catalyst coating preparation:

[0084] 1. Preparation of the catalyst layer (CA coating): 2 kg of water, 1.02 kg of powdered CA, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. Using an industrial vacuum coating machine, the slurry was coated onto a 1.36 kg molded carrier to prepare catalyst W.

[0085] 2. Preparation of CB Coating for Catalyst Layer: 2 kg of water, 1.02 kg of powdered CB, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry was adjusted using alkaline ammonia or acidic nitric acid. Using an industrial vacuum coating machine, the slurry was coated onto the catalyst W, followed by drying and calcination. The drying temperature was 80℃ for 2 hours, and the calcination temperature was 350℃. After calcination, a double-layered catalyst was obtained, which is used as a catalyst for the oxidation of low-concentration methane in coal mines.

[0086] Comparative Example 3 (no differential atmosphere roasting, all N2 atmosphere)

[0087] 1) Powder preparation: 0.19 kg of ammonium tungstate (WO3 accounting for 10% of the active carrier) was dissolved in 15 kg of deionized water to form an ammonium tungstate solution. 1.53 kg of TiO2 (TiO2 accounting for 90% of the active carrier) was added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry was ground for 24 h, then dried and calcined to form mixed powder A (active carrier mass percentage 50%). The drying temperature was 80℃ for 6 h, and the calcination temperature was 260℃ for 2 h. Liquid phase deposition was then used. Li2SO4 was deposited onto mixed component A. 0.204 kg of Li2SO4 (Li2SO4 accounts for 60% of the total active component) was dissolved in 15 kg of deionized water. Mixed powder A was added to the Li2SO4 solution. The temperature of the mixing system was maintained at 60-80℃ and the stirring time was 24 h to end the liquid phase deposition step. After filtering the mixing system, the supernatant was removed. The filtered mixture was dried at 120℃ for 2 h and calcined at 550℃ to form 1.904 kg of mixed powder B.

[0088] 2) Preparation of Pt and V₂O₅ loading: 0.11 kg of ammonium metavanadate (V₂O₅ accounts for 25% of the total active component) and 0.62 kg of 8.5% platinum nitrate solution (Pt accounts for 15% of the total active component) were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring to form a mixed slurry. The mixed slurry was heated to 60°C, and 0.2 kg of oxalic acid, a reducing agent, was added while stirring to reduce the valence state of V to +4. The reduction reaction continued for 6 hours, controlling the reduction of some Pt ​​to nanoparticle Pt. The mixture was then filtered, and the resulting filter cake was dried and calcined under differential atmosphere.

[0089] 1. Drying temperature 120℃, drying time 2h, 2.83Kg of dried powder obtained;

[0090] 2. Atmosphere calcination. 1.41 kg of dried powder was calcined in a nitrogen atmosphere with an oxygen content of <0.5%, at a calcination temperature of 400℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CA; another 1.41 kg of powder was calcined in a nitrogen atmosphere with an oxygen content of <0.5%, at a calcination temperature of 550℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CB.

[0091] 3) Catalyst coating preparation:

[0092] 1. Preparation of the catalyst layer (CA coating): 2 kg of water, 1.02 kg of powdered CA, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. Using an industrial vacuum coating machine, the slurry was coated onto a 1.36 kg molded carrier to prepare catalyst W.

[0093] 2. Preparation of CB Coating for Catalyst Layer: 2 kg of water, 1.02 kg of powdered CB, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry was adjusted using alkaline ammonia or acidic nitric acid. Using an industrial vacuum coating machine, the slurry was coated onto the catalyst W, followed by drying and calcination. The drying temperature was 80℃ for 2 hours, and the calcination temperature was 350℃. After calcination, a double-layered catalyst was obtained for use in low-concentration methane in coal mines.

[0094] Comparative Example 4 (no differential atmosphere calcination, all air atmosphere)

[0095] 1) Powder preparation: 0.19 kg of ammonium tungstate (WO3 accounting for 10% of the active carrier) was dissolved in 15 kg of deionized water to form an ammonium tungstate solution. 1.53 kg of TiO2 (TiO2 accounting for 90% of the active carrier) was added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry was ground for 24 h, then dried and calcined to form mixed powder A (active carrier mass percentage 50%). The drying temperature was 80℃ for 6 h, and the calcination temperature was 260℃ for 2 h. Liquid phase deposition was then used. Li2SO4 was deposited onto mixed component A. 0.204 kg of Li2SO4 (Li2SO4 accounts for 60% of the total active component) was dissolved in 15 kg of deionized water. Mixed powder A was added to the Li2SO4 solution. The temperature of the mixing system was maintained at 60-80℃ and the stirring time was 24 h to end the liquid phase deposition step. After filtering the mixing system, the supernatant was removed. The filtered mixture was dried at 120℃ for 2 h and calcined at 550℃ to form 1.904 kg of mixed powder B.

[0096] 2) Preparation of Pt and V₂O₅ loading: 0.11 kg of ammonium metavanadate (V₂O₅ accounts for 25% of the total active component) and 0.62 kg of 8.5% platinum nitrate solution (Pt accounts for 15% of the total active component) were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring to form a mixed slurry. The mixed slurry was heated to 60°C, and 0.2 kg of oxalic acid, a reducing agent, was added while stirring to reduce the valence state of V to +4. The reduction reaction continued for 6 hours, controlling the reduction of some Pt ​​to nanoparticle Pt. The mixture was then filtered, and the resulting filter cake was dried and calcined under differential atmosphere.

[0097] 1. Drying temperature 120℃, drying time 2h, 2.83Kg of dried powder obtained;

[0098] 2. Atmosphere calcination. 1.41 kg of dried powder was calcined in an air atmosphere at a temperature of 400℃ for 2 hours to obtain 1.02 kg of catalyst powder CA; another 1.41 kg of powder was calcined in an air atmosphere at a temperature of 550℃ for 2 hours to obtain 1.02 kg of catalyst powder CB.

[0099] 3) Catalyst coating preparation:

[0100] 1. Preparation of the catalyst layer (CA coating): 2 kg of water, 1.02 kg of powdered CA, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. Using an industrial vacuum coating machine, the slurry was coated onto a 1.36 kg molded carrier to prepare catalyst W.

[0101] 2. Preparation of CB Coating for Catalyst Layer: 2 kg of water, 1.02 kg of powdered CB, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry was adjusted using alkaline ammonia or acidic nitric acid. Using an industrial vacuum coating machine, the slurry was coated onto the catalyst W, followed by drying and calcination. The drying temperature was 80℃ for 2 hours, and the calcination temperature was 350℃. After calcination, a double-layered catalyst was obtained, which is used as a catalyst for the oxidation of low-concentration methane in coal mines.

[0102] Comparative Example 5: (Reduction by a strong reducing agent)

[0103] 1) Powder preparation: 0.19 kg of ammonium tungstate (WO3 accounting for 10% of the active carrier) was dissolved in 15 kg of deionized water to form an ammonium tungstate solution. 1.53 kg of TiO2 (TiO2 accounting for 90% of the active carrier) was added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry was ground for 24 h, then dried and calcined to form mixed powder A (active carrier mass percentage 50%). The drying temperature was 80℃ for 6 h, and the calcination temperature was 260℃ for 2 h. Liquid phase deposition was then used. Li2SO4 was deposited onto mixed component A. 0.204 kg of Li2SO4 (Li2SO4 accounts for 60% of the total active component) was dissolved in 15 kg of deionized water. Mixed powder A was added to the Li2SO4 solution. The temperature of the mixing system was maintained at 60-80℃ and the stirring time was 24 h to end the liquid phase deposition step. After filtering the mixing system, the supernatant was removed. The filtered mixture was dried at 120℃ for 2 h and calcined at 550℃ to form 1.904 kg of mixed powder B.

[0104] 2) Preparation of Pt and V₂O₅ loading: 0.11 kg of ammonium metavanadate (V₂O₅ accounts for 25% of the total active component) and 0.62 kg of 8.5% platinum nitrate solution (Pt accounts for 15% of the total active component) were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring to form a mixed slurry. The mixed slurry was heated to 60°C, and 0.2 kg of hydrazine hydrate, a reducing agent, was added while stirring to reduce the valence state of V to +4. The reduction reaction continued for 6 hours, reducing all Pt to nanoparticle Pt. The mixture was then filtered, and the resulting filter cake was dried and calcined under differential atmosphere.

[0105] 1. Drying temperature 120℃, drying time 2h, 2.83Kg of dried powder obtained;

[0106] 2. Differential atmosphere calcination: 1.41 kg of dried powder was calcined in a nitrogen atmosphere with an oxygen content of <0.5%, at a calcination temperature of 400℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CA; another 1.41 kg of powder was calcined in an air atmosphere at a calcination temperature of 550℃ and a calcination time of 2 h to obtain 1.02 kg of catalyst powder CB.

[0107] 3) Catalyst coating preparation:

[0108] 1. Preparation of the catalyst layer (CA coating): 2 kg of water, 1.02 kg of powdered CA, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. Using an industrial vacuum coating machine, the slurry was coated onto a 1.36 kg molded carrier to prepare catalyst W.

[0109] 2. Preparation of CB Coating for Catalyst Layer: 2 kg of water, 1.02 kg of powdered CB, and 0.05 kg of anionic surfactant (sulfonate surfactant) were mixed and stirred to form a slurry. The pH of the slurry was adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry was adjusted using alkaline ammonia or acidic nitric acid. Using an industrial vacuum coating machine, the slurry was coated onto the catalyst W, followed by drying and calcination. The drying temperature was 80℃ for 2 hours, and the calcination temperature was 350℃. After calcination, a double-layered catalyst was obtained for use in low-concentration methane in coal mines.

[0110] The catalysts prepared in the above embodiments and the catalysts prepared in the comparative examples were tested for their catalytic oxidation performance at low concentrations of methane gas, wherein:

[0111] 1. Activation temperature test conditions. The catalyst test volume hourly space velocity was 15000 h⁻¹, and the feed gas methane concentration was controlled at 8%, feed gas humidity at 15%, feed gas SO₂ concentration at 200 mg / m³, and feed gas H₂S concentration at 100 mg / m³. The reaction temperature at which the methane conversion rate is 10% is defined as the activation temperature.

[0112] 2.T 90 Temperature test conditions. The catalyst test volume hourly space velocity (VHSV) was 15000 h⁻¹, and the feed gas methane concentration was controlled at 8%, humidity at 15%, SO₂ concentration at 200 mg / m³, and H₂S concentration at 100 mg / m³. The reaction temperature at which methane conversion reaches 90% is defined as T. 90 temperature;

[0113] 3. Sulfur resistance test. The catalyst was tested at a volume hourly space velocity (VHSV) of 15000 h⁻¹, with controlled feed gas methane concentration of 8%, feed gas humidity of 15%, feed gas SO₂ concentration of 200 mg / m³, and feed gas H₂S concentration of 100 mg / m³. Sulfur resistance was determined based on the decrease in methane conversion rate after the catalyst operated under these conditions for 500 hours.

[0114] 4. Catalytic selectivity. Defined as 1-W CO / W CH4 W CO To reflect the CO mass concentration at the outlet, W CH4 The concentration of CH4 at the reaction inlet is denoted as .

[0115] The catalyst performance data of the embodiments and comparative examples of the present invention are shown below:

[0116] Catalyst type Activity activation temperature / ℃ T90 / ℃ Sulfur resistance test conversion rate decrease rate / % Selectivity / % Example 1 362 453 5.2 99.2 Example 2 370 461 5.1 99.1 Example 3 353 443 4.9 99.4 Example 4 346 436 4.1 99.7 Example 5 338 427 3.2 99.9 Comparative Example 1 350 442 10.7 99.1 Comparative Example 2 397 498 5.2 93.2 Comparative Example 3 430 482 7.7 97.4 Comparative Example 4 386 470 8.3 98.9 Comparative Example 5 409 475 6.9 97.4

[0117] The catalyst of this invention can be used for efficient and stable removal of CO from industrial flue gas, and is particularly suitable for CO removal from sintering machine flue gas in the iron and steel industry and CO removal from dry quenching vent gas in the coking industry.

Claims

1. A catalyst for the oxidation of low-concentration methane in coal mines, characterized in that, The catalyst comprises, by mass percentage: an active support, an active substance, and a molded support, wherein the active support comprises 40%–60% by mass, the active substance comprises 3%–10% by mass, and the molded support comprises 37%–50% by mass. The active support is a TiO2-WO3 bimetallic oxide system, wherein the TiO2 component accounts for 80% to 90% of the total mass of the active support, and the WO3 component accounts for 10% to 20% of the total mass of the active support; The active material is Pt-V2O5-Li2SO4, wherein Pt accounts for 5% to 15% of the total mass of the active material, V2O5 accounts for 25% to 35% of the total mass of the active material, and Li2SO4 accounts for 60% of the total mass of the active material.

2. The catalyst for low-concentration coal mine gas oxidation according to claim 1, characterized in that, The TiO2 in the active carrier is anatase TiO2, with a TiO2 content ≥98%, impurity element content ≤2%, and a specific surface area of ​​250-320 m². 2 / g, pore volume ≥0.45cc / g, sulfate impurity content ≤1.0%, chloride impurity content ≤0.5%; The WO3 in the active carrier is obtained by thermal decomposition of ammonium tungstate, with an ammonium tungstate WO3 content ≥90%, water-insoluble matter ≤0.5%, and pH value 2.5~4.

5.

3. The catalyst for low-concentration coal mine gas oxidation according to claim 1, characterized in that, Li2SO4 in the active material is a co-catalytic component, and Pt-V2O5 is the main catalytic component. The active material contains platinum nitrate as the Pt precursor salt, ammonium metavanadate as the V2O5 precursor salt, high-purity lithium sulfate monohydrate as the Li2SO4, Na2O content ≤20ppm, and K2O content ≤10ppm.

4. The catalyst for low-concentration coal mine gas oxidation according to claim 1, characterized in that, The molding carrier is a ceramic fiber board.

5. A method for preparing the catalyst for low-concentration coal mine gas oxidation as described in any one of claims 1 to 4, comprising the following steps: 1) Powder preparation: Ammonium tungstate in the specified proportion is dissolved in deionized water to form an ammonium tungstate solution. TiO2 in the specified proportion is added to the ammonium tungstate solution to form a mixed slurry. The mixed slurry is ground for 24 hours, then dried and calcined to form mixed powder A. The drying temperature is 80℃ for 6 hours, and the calcination temperature is 260℃ for 2 hours. Li2SO4 is deposited onto mixed powder A using liquid phase deposition. Li2SO4 is dissolved in deionized water according to the specified proportion. Mixed powder A is added to the Li2SO4 solution, and the temperature of the mixing system is maintained at 60-80℃ for 24 hours. The liquid phase deposition step is then completed. After filtration, the supernatant was removed from the mixture. The filtered mixture was dried at 120℃ for 2 hours and calcined at 550℃ to form mixed powder B; 2) Preparation of Pt and V2O5 loading: The V2O5 precursor salt and Pt precursor salt in the formula ratio were dissolved in deionized water to form a mixed solution. Mixed powder B was added while stirring the mixed solution to form a mixed slurry. The mixed slurry was heated to 60℃, and oxalic acid, a reducing agent, was added while stirring to reduce the valence state of V to +4. The reduction reaction lasted for 6-12 hours, controlling the reduction of some Pt ​​to nanoparticle Pt; then it was filtered, and the obtained filter cake was dried and calcined under differential atmosphere; wherein: drying temperature 1. Drying temperature 120℃, drying time 2h; Differential atmosphere calcination: The dried powder is divided into two equal parts. One part is calcined in a nitrogen atmosphere with an oxygen content of <0.5%, calcination temperature 400℃, calcination time 2h to prepare catalyst powder CA; the other part is calcined in an air atmosphere with a calcination temperature of 550℃, calcination time 2h to prepare catalyst powder CB; 3) Catalyst coating preparation:

1. Catalyst layer CA coating preparation: Water, powdered CA and anionic surfactant are mixed and stirred to form a mixed slurry. The pH of the slurry is adjusted to 4-5 to obtain a slurry with a viscosity of 300mPa·s. H. Adjusting the pH using alkaline substances like ammonia or acidic substances like nitric acid; using an industrial vacuum coating machine, the slurry is coated onto a molded carrier to prepare catalyst W; 2. Preparation of catalyst layer CB coating: Water, powdered CB, and anionic surfactant are mixed and stirred to form a mixed slurry. The pH of the slurry is adjusted to 4-5 to obtain a slurry with a viscosity of 300 mPa·s. The pH of the slurry is adjusted using alkaline substances like ammonia or acidic substances like nitric acid; using an industrial vacuum coating machine, the slurry is coated onto catalyst W, and then dried and calcined. The drying temperature is 80℃ for 2 hours, and the calcination temperature is 350℃. After calcination, a double-layered catalyst is obtained for use in the oxidation of low-concentration methane in coal mines.

6. The method for preparing the oxidation catalyst for low-concentration coal mine gas according to claim 4, characterized in that, The anionic surfactant is a sulfonate surfactant.