Monolithic catalyst for catalytic combustion of methane and method for its preparation

Abstract

The application relates to a preparation method of a monolithic catalyst for catalytic combustion of methane, which comprises the following steps: impregnating a honeycomb carrier in a titanium dioxide sol, taking out and drying and roasting to obtain a carrier with a TiO2 coating; impregnating the carrier with the TiO2 coating in an active metal salt solution, wherein 3-(trifluoroacetamido) pyrrolidine hydrochloride is added in the active metal salt solution, the active metal is a perovskite type metal composite oxide, and the general structure is ABO3; taking out, drying and roasting to obtain the monolithic catalyst. 90 The monolithic catalyst provided by the application is used for catalytic combustion of methane, has a low-temperature catalytic activity of less than 500 DEG C, and has the advantages of high low-temperature catalytic activity and good long-term use activity.

Description

Technical Field

[0001] This invention belongs to the field of waste gas treatment technology, specifically relating to an integral catalyst for methane catalytic combustion and its preparation method. Background Technology

[0002] Methane is the second largest greenhouse gas, accounting for approximately 20% of global greenhouse gas emissions and contributing about a quarter to global warming. The methane molecule has a stable tetrahedral structure and can decompose at temperatures above 1500℃. Catalytic combustion of methane is an effective alternative to traditional thermal combustion methods, and its key lies in the catalyst. Catalytic combustion catalysts for methane can be broadly classified into two categories based on their active components: noble metal catalysts and non-noble metal catalysts. While noble metal catalysts possess good low-temperature ignition activity and resistance to poisoning, their large-scale production and application are limited due to their poor high-temperature stability and high cost. Non-noble metal catalysts are mainly divided into perovskite-type metal composite oxides and hexaaluminate-type metal composite oxides (the disadvantage being relatively difficult product preparation) and other metal oxides (the disadvantage being easy sintering at high temperatures). Perovskite-type catalysts can overcome the above disadvantages, possessing characteristics such as moderate ignition temperature, simple and easy preparation process, low cost, and strong resistance to high-temperature sintering; however, their poor low-temperature activity limits their development and application.

[0003] Monolithic catalysts have a regular pore structure, making it easy to load catalytically active components. They can reduce reaction pressure, optimize operating conditions, and save operating costs, and are widely used in the research and development of methane catalytic combustion catalysts.

[0004] CN106944093A discloses a perovskite-type honeycomb monolithic methane catalytic combustion catalyst and its preparation method. The catalyst includes an active component and an inert honeycomb support. The active component contains rare earth metal elements, alkaline earth metal elements, and transition metal elements. The support is a cordierite-based honeycomb support, a mullite-based honeycomb support, or an alumina-based honeycomb support. The preparation method includes the following steps: (1) Preparation of the active component precursor solution: Prepare an aqueous solution of soluble metal salt according to the required molar ratio of metal elements of the active component, which is the active component precursor solution, wherein the total molar concentration of metal ions is 1.0-2.0 mol / L; (2) Loading of the active component: Impregnate the inert honeycomb support with the active component precursor solution. After impregnation, the inert honeycomb support is dried and calcined to obtain the perovskite-type honeycomb monolithic methane catalytic combustion catalyst. The calcination temperature is 750-850℃ and the time is 2-3h. The space velocity is 15000h. -1 Under these conditions, CH4 3.0% (v / v), T 10 >500℃, T 90 At temperatures above 650℃, the catalytic activity at low temperatures needs to be improved.

[0005] CN103831095A discloses an integral metal composite catalyst for methane catalytic combustion and its preparation method. The integral metal composite catalyst is formed by coating a porous matrix with perovskite. The general structural formula of the perovskite is ABO3. Metal element A is one or more of Group IIA or lanthanide elements, and metal element B is one or more of transition metals. The preparation method includes: (1) pretreatment of porous matrix: the porous matrix is ​​soaked in ammonia water and cerium nitrate aqueous solution in sequence, taken out, and then dried and calcined; (2) prepare pseudoboehmite aqueous solution and perovskite soluble salt solution, and mix the two to obtain precursor aqueous solution; (3) add organic complexing agent to the precursor aqueous solution, stir, and add nitric acid dropwise to obtain aluminum sol; (4) immerse the pretreated porous matrix in the aluminum sol, dry and calcine, wherein the porous matrix is ​​placed in the aluminum sol for 10-720 minutes, remove excess liquid, dry at 50-140℃ for 3-16 hours, then calcined at 300-600℃ for 2-6 hours, and finally calcined at 600-1300℃ for 2-6 hours to obtain the monolithic metal composite catalyst. This patented method involves uniformly dispersing metallic elements from perovskite in an aluminum sol, then complexing them with an organic complexing agent, and finally indirectly adsorbing them onto a porous matrix, at a space velocity of 24000 h⁻¹. -1 Under the conditions of CH4 concentration 3.5% (v / v) and T90 ≥ 520℃, the low-temperature catalytic activity needs to be further improved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a monolithic catalyst for the catalytic combustion of methane and its preparation method. The monolithic catalyst provided by this invention is used for the catalytic combustion of methane. 90 With a temperature of ≤500℃, it has the advantages of high catalytic activity at low temperatures and good activity retention over long-term use.

[0007] The present invention provides a method for preparing a monolithic catalyst for the catalytic combustion of methane, comprising the following steps:

[0008] (1) The honeycomb carrier is immersed in titanium dioxide sol, then removed, dried and calcined to obtain a carrier with TiO2 coating;

[0009] (2) The support with TiO2 coating is immersed in an active metal salt solution containing 3-(trifluoroacetamido)pyrrolidine hydrochloride. The active metal is a perovskite-type metal composite oxide with the general structural formula ABO3. After removal, it is dried and calcined to obtain an integral catalyst.

[0010] In this invention, the honeycomb carrier in step (1) is a honeycomb ceramic carrier or a metal honeycomb carrier, specifically such as at least one of cordierite honeycomb ceramic, mullite honeycomb ceramic, stainless steel foil, FeCrAl, etc., with a mesh size of 300-500 mesh.

[0011] In this invention, the titanium dioxide sol described in step (1) is conventional and can be obtained commercially or in-house. Nano-sized titanium dioxide sol with a particle size of 5-50 nm is preferred. Further, the preferred preparation method is as follows: (a) Preparing solution A by mixing glacial acetic acid, anhydrous ethanol, and deionized water at room temperature, wherein the mass ratio of deionized water, glacial acetic acid, and anhydrous ethanol is 5:1-8:3-10; (b) Preparing solution B by mixing tetrabutyl titanate and anhydrous ethanol at room temperature, wherein the mass ratio of tetrabutyl titanate to anhydrous ethanol is 1:0.5-2; (c) Adding solution B dropwise to solution A under vigorous stirring, wherein the mass ratio of solution A to solution B is 1:0.5-5, the dropping rate is 10-25 mL / min, and after the addition is complete, stirring at room temperature for 1-3 h yields titanium dioxide sol at a stirring rate of 200-500 r / min.

[0012] In this invention, step (1) involves immersing the honeycomb carrier in titanium dioxide sol for 2-5 minutes.

[0013] In this invention, the drying temperature in step (1) is 80-120℃, and the drying time is 12-24h. The calcination temperature is 650-800℃, and the calcination time is 3-6h.

[0014] In this invention, the mass content of 3-(trifluoroacetamido)pyrrolidine hydrochloride in the active metal salt solution in step (2) is 1%-10%, preferably 3%-5%.

[0015] In this invention, the active metal mentioned in step (2) is a non-precious metal, specifically including two types, A and B. A is generally at least one of La, Ce, etc., and B is generally at least one of Fe, Co, Ni, Mn, etc., wherein the molar ratio of active metals A and B is 1:1. The active metal salt solution is generally one or more of its soluble metal salts, such as nitrates, chlorides, etc., and the concentration of the active metal salt solution is generally 1–3 mol / L.

[0016] In this invention, in step (2), the carrier with the TiO2 coating is immersed in an active metal salt solution for 2-5 minutes.

[0017] In this invention, the drying temperature in step (2) is 80-120℃ and the drying time is 12-24 hours; the calcination temperature is 650-800℃ and the calcination time is 3-6 hours.

[0018] The monolithic catalyst for methane catalytic combustion described in this invention is a monolithic catalyst in which perovskite metal oxide (ABO3) is supported on a honeycomb support with a TiO2 coating. The catalyst contains 0.001%-0.05% chlorine and 3%-8% active metal by mass.

[0019] This invention also provides an application of the prepared methane catalytic combustion catalyst for the catalytic combustion of methane at low temperatures, which has the advantages of high catalytic activity at low temperatures and good activity retention over long-term use.

[0020] In this invention, the volume hourly space velocity is 10000 h⁻¹. -1 ~30000h -1 Under conditions where methane volume concentration is 1%–3.5%, T 90 ≤500℃.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) To address the problem of poor low-temperature activity in perovskite catalysts, the inventors of this application introduced 3-(trifluoroacetamido)pyrrolidine hydrochloride into the active metal salt solution to prepare a monolithic perovskite metal oxide catalyst. This catalyst can establish a bridge between TiO2 and ABO3 through carbonyl groups, enhancing the electron transfer ability between them and increasing the migration rate of bulk lattice oxygen to the catalyst surface, thereby improving catalytic activity and reducing reaction temperature. Simultaneously, the halogen functional groups in 3-(trifluoroacetamido)pyrrolidine hydrochloride have good electrical conductivity, which helps to improve the redox ability of ABO3, thus enhancing low-temperature catalytic activity.

[0023] (2) The introduction of 3-(trifluoroacetamido)pyrrolidine hydrochloride enhances the strong interaction between the active metal and the support, which helps to maintain the catalyst activity.

[0024] (3) After coating and calcining, the titanium dioxide sol forms a TiO2 coating on the surface of the honeycomb carrier, which can generate electron cloud entanglement with the active component ABO3, inhibit the migration and aggregation of the active component on the carrier surface, and help to improve and maintain good low-temperature catalyst activity. Detailed Implementation

[0025] The following embodiments further illustrate the technical solution and effects of the present invention. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0026] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples can be purchased from biochemical reagent stores.

[0027] In this embodiment of the invention, T 90 This indicates the methane ignition temperature at which the methane conversion rate reaches 90%.

[0028] Example 1

[0029] (1) A 400-mesh cordierite honeycomb ceramic carrier was immersed in commercial titanium dioxide sol at room temperature for 3 min. The titanium dioxide particle size was 10 nm. After removal, it was dried at 100℃ for 12 h and calcined at 650℃ for 4 h to obtain a carrier with a TiO2 coating.

[0030] (2) Prepare an active metal salt solution with a concentration of 2.5 mol / L, wherein metal salt A is La(NO3)3·6H2O, and metal salts B are Fe(NO3)3·9H2O and Ni(NO3)2·6H2O, with a molar ratio of A to B of 1:1 and a molar ratio of Ni to Fe of 0.2:0.8. Add 3-(trifluoroacetamido)pyrrolidine hydrochloride to the active metal salt solution at a mass content of 3.5%. Immerse the carrier with TiO2 coating in the active metal salt solution for 3 min, remove it, dry it at 100℃ for 12 h, and calcine it at 700℃ for 4 h to obtain LaNi. 0.2 Fe 0.8 O3 / TiO2 monolithic catalyst. By catalyst mass, the chlorine content is 0.026%, and the active metal content is 4.8%.

[0031] The results of the catalyst activity evaluation are as follows:

[0032] With a methane volume concentration of 3.5% and a volume hourly space velocity of 25,000 h⁻¹ -1 Under the condition, T 90 The temperature was 485℃. After continuous operation at 485℃ for 100 hours, the methane removal rate was 88.6%.

[0033] Example 2

[0034] (1) A 400-mesh cordierite honeycomb ceramic carrier was immersed in commercial titanium dioxide sol at room temperature for 4 min. The titanium dioxide particle size was 20 nm. After removal, it was dried at 110℃ for 12 h and calcined at 700℃ for 4 h to obtain a carrier with a TiO2 coating.

[0035] (2) Prepare an active metal salt solution with a concentration of 3 mol / L, wherein metal salt A is La(NO3)3·6H2O, and metal salts B are Fe(NO3)3·9H2O and Ni(NO3)2·6H2O, with a molar ratio of A to B of 1:1 and a molar ratio of Ni to Fe of 0.2:0.8. Add 4% by mass of 3-(trifluoroacetamido)pyrrolidine hydrochloride to the active metal salt solution, immerse the carrier with TiO2 coating in the active metal salt solution for 4 min, remove it, dry it at 110℃ for 12 h, and calcine it at 700℃ for 4 h to obtain LaNi. 0.2 Fe 0.8 O3 / TiO2 monolithic catalyst. By catalyst mass, the chlorine content is 0.045%, and the active metal content is 5.8%.

[0036] The results of the catalyst activity evaluation are as follows:

[0037] With a methane volume concentration of 3.5% and a volume hourly space velocity of 25,000 h⁻¹ -1 Under the condition, T 90 The temperature was 486℃. After continuous operation at 486℃ for 100 hours, the methane removal rate was 86.7%.

[0038] Example 3

[0039] (1) A 300-mesh cordierite honeycomb ceramic carrier was immersed in commercial titanium dioxide sol at room temperature for 4 min. The titanium dioxide particle size was 20 nm. After removal, it was dried at 80℃ for 24 h and calcined at 800℃ for 3 h to obtain a carrier with a TiO2 coating.

[0040] (2) Prepare an active metal salt solution with a concentration of 1 mol / L, wherein metal salt A is La(NO3)3·6H2O, and metal salts B are Fe(NO3)3·9H2O and Ni(NO3)2·6H2O, with a molar ratio of A to B of 1:1 and a molar ratio of Ni to Fe of 0.2:0.8. Add 3-(trifluoroacetamido)pyrrolidine hydrochloride to the active metal salt solution at a mass content of 3%. Immerse the carrier with TiO2 coating in the active metal salt solution for 2 min, remove it, dry it at 80℃ for 24 h, and calcine it at 800℃ for 3 h to obtain LaNi. 0.2 Fe 0.8 O3 / TiO2 monolithic catalyst. By catalyst mass, the chlorine content is 0.019%, and the active metal content is 3.4%.

[0041] The results of the catalyst activity evaluation are as follows:

[0042] With a methane volume concentration of 3.5% and a volume hourly space velocity of 25,000 h⁻¹ -1 Under the condition, T 90The temperature was 488℃. After continuous operation at 488℃ for 100 hours, the methane removal rate was 87.8%.

[0043] Example 4

[0044] (1) A 400-mesh cordierite honeycomb ceramic carrier was immersed in commercial titanium dioxide sol at room temperature for 3 min. The titanium dioxide particle size was 10 nm. After removal, it was dried at 100℃ for 12 h and calcined at 650℃ for 4 h to obtain a carrier with a TiO2 coating.

[0045] (2) Prepare an active metal salt solution with a concentration of 2.5 mol / L, wherein metal salt A is Ce(NO3)3·6H2O, and metal salts B are Fe(NO3)3·9H2O and Ni(NO3)2·6H2O, with a molar ratio of A to B of 1:1 and a molar ratio of Ni to Fe of 0.2:0.8. Add 3-(trifluoroacetamido)pyrrolidine hydrochloride to the active metal salt solution at a mass content of 3.5%. Immerse the carrier with TiO2 coating in the active metal salt solution for 3 min, remove it, dry it at 100℃ for 12 h, and calcine it at 700℃ for 4 h to obtain CeNi. 0.2 Fe 0.8 O3 / TiO2 monolithic catalyst. By catalyst mass, the chlorine content is 0.028%, and the active metal content is 4.9%.

[0046] The results of the catalyst activity evaluation are as follows:

[0047] With a methane volume concentration of 3.5% and a volume hourly space velocity of 25,000 h⁻¹ -1 Under the condition, T 90 The temperature was 487℃. After continuous operation at 487℃ for 100 hours, the methane removal rate was 88.5%.

[0048] Example 5

[0049] (1) A 400-mesh cordierite honeycomb ceramic carrier was immersed in commercial titanium dioxide sol at room temperature for 3 min. The titanium dioxide particle size was 10 nm. After removal, it was dried at 100℃ for 12 h and calcined at 650℃ for 4 h to obtain a carrier with a TiO2 coating.

[0050] (2) Prepare an active metal salt solution with a concentration of 2.5 mol / L, wherein metal salt A is La(NO3)3·6H2O, and metal salts B are Mn(NO3)2·6H2O and Co(NO3)2·6H2O, with a molar ratio of A to B of 1:1 and a molar ratio of Co to Mn of 0.2:0.8. Add 3-(trifluoroacetamido)pyrrolidine hydrochloride to the active metal salt solution at a mass content of 3.5%. Immerse the carrier with TiO2 coating in the active metal salt solution for 3 min, remove it, dry it at 100℃ for 12 h, and calcine it at 700℃ for 4 h to obtain LaCo.0.2 Mn 0.8 O3 / TiO2 monolithic catalyst. By catalyst mass, the chlorine content is 0.03%, and the active metal content is 4.7%.

[0051] The results of the catalyst activity evaluation are as follows:

[0052] With a methane volume concentration of 3.5% and a volume hourly space velocity of 25,000 h⁻¹ -1 Under the condition, T 90 The temperature was 481℃. After continuous operation at 481℃ for 100 hours, the methane removal rate was 88.2%.

[0053] Example 6

[0054] (1) A 400-mesh cordierite honeycomb ceramic carrier was immersed in commercial titanium dioxide sol at room temperature for 3 min. The titanium dioxide particle size was 10 nm. After removal, it was dried at 100℃ for 12 h and calcined at 650℃ for 4 h to obtain a carrier with a TiO2 coating.

[0055] (2) Prepare an active metal salt solution with a concentration of 2.5 mol / L, wherein metal salt A is La(NO3)3·6H2O, and metal salts B are Fe(NO3)3·9H2O and Ni(NO3)2·6H2O, with a molar ratio of A to B of 1:1 and a molar ratio of Ni to Fe of 0.2:0.8. Add 1.5% (by mass) of 3-(trifluoroacetamido)pyrrolidine hydrochloride to the active metal salt solution. Immerse the carrier with TiO2 coating in the active metal salt solution for 3 min, remove it, dry it at 100℃ for 12 h, and calcine it at 700℃ for 4 h to obtain LaNi. 0.2 Fe 0.8 O3 / TiO2 monolithic catalyst. By catalyst mass, the chlorine content is 0.015%, and the active metal content is 3.2%.

[0056] The results of the catalyst activity evaluation are as follows:

[0057] With a methane volume concentration of 3.5% and a volume hourly space velocity of 25,000 h⁻¹ -1 Under the condition, T 90 The temperature was 496℃. After continuous operation at 496℃ for 100 hours, the methane removal rate was 85.7%.

[0058] Example 7

[0059] Same as Example 1, except that: the preparation method of titanium dioxide sol is as follows: (a) glacial acetic acid, anhydrous ethanol and deionized water are mixed at room temperature to obtain solution A, wherein the mass ratio of deionized water, glacial acetic acid and anhydrous ethanol is 5:6:5; (b) tetrabutyl titanate and anhydrous ethanol are mixed at room temperature to obtain solution B, wherein the mass ratio of tetrabutyl titanate to anhydrous ethanol is 1:1.5; (c) solution B is added dropwise to solution A under vigorous stirring, wherein the mass ratio of solution A to solution B is 1:2, the dropping rate is 20 mL / min, and after the dropping is completed, the mixture is stirred at room temperature for 2 h to obtain titanium dioxide sol, and the stirring rate is 300 r / min.

[0060] With a methane volume concentration of 3.5% and a volume hourly space velocity of 25,000 h⁻¹ -1 Under the condition, T 90 The temperature was 483℃. After continuous operation at 483℃ for 100 hours, the methane removal rate was 89.8%.

[0061] Example 8

[0062] Same as Example 1, except that the honeycomb carrier is an FeCrAl metal honeycomb carrier.

[0063] With a methane volume concentration of 1.5% and a volume hourly space velocity of 25,000 h⁻¹ -1 Under the condition, T 90 The temperature was 495℃. After continuous operation at 495℃ for 100 hours, the methane removal rate was 85.3%.

[0064] Comparative Example 1

[0065] Same as Example 1, except that 3-(trifluoroacetamido)pyrrolidine hydrochloride was not added in step (1). The methane volume concentration was 3.5%, and the volume hourly space velocity was 25000 h⁻¹. -1 Under the condition, T 90 The temperature was 553℃. After continuous operation at 553℃ for 100 hours, the methane removal rate was 80.7%.

[0066] Comparative Example 2

[0067] Same as Example 1, except that step (1) uses γ-Al2O3 instead of TiO2 sol. The methane volume concentration is 3.5%, and the volume hourly space velocity is 25000 h⁻¹. -1 Under the condition, T 90 The temperature was 534℃. After continuous operation at 534℃ for 100 hours, the methane removal rate was 82.7%.

[0068] Comparative Example 3

[0069] Same as Example 1, except that: in step (2), an active metal salt solution with a concentration of 2.5 mol / L is prepared, wherein metal salt A is Sr(NO3)2, and metal salts B are Fe(NO3)3·9H2O and Ni(NO3)2·6H2O, wherein the molar ratio of A to B is 1:1, and the molar ratio of Ni to Fe is 0.2:0.8. The methane volume concentration is 3.5%, and the volume hourly space velocity is 25000 h⁻¹. -1 Under the condition, T 90 The temperature was 523℃. After continuous operation at 523℃ for 100 hours, the methane removal rate was 81.6%.

Claims

1. A method for the preparation of a monolithic catalyst for the catalytic combustion of methane, characterized in that It comprises the following steps: (1) immerse the honeycomb carrier in the titanium dioxide sol, and after taking out, dry and calcine to obtain the carrier with TiO2 coating; (2) immerse the carrier with TiO2 coating in the active metal salt solution, and after taking out, dry and calcine to obtain the monolithic catalyst; the monolithic catalyst is the perovskite metal oxide ABO3 supported on the honeycomb carrier with TiO2 coating; the mass content of 3-(trifluoroacetamido) pyrrolidine hydrochloride in the active metal salt solution is 1%-10%; the active metal is a non-noble metal, specifically including A and B, wherein A is at least one of La and Ce, and B is at least one of Fe, Co, Ni and Mn, wherein the molar ratio of the active metals A and B is 1:1; the content of chlorine element is 0.001%-0.05% and the content of active metal is 3%-8% based on the mass of the catalyst.

2. The method of claim 1, wherein: The honeycomb carrier in step (1) is a honeycomb ceramic carrier or a metal honeycomb carrier, and the mesh number is 300-500.

3. The method of claim 2, wherein: The honeycomb carrier in step (1) is at least one of a cordierite honeycomb ceramic carrier, a mullite honeycomb ceramic carrier, a stainless steel foil metal honeycomb carrier and a FeCrAl metal honeycomb carrier.

4. The method of claim 1, wherein: The titanium dioxide sol in step (1) is obtained by commercial purchase or self-preparation, and the particle size is 5-50 nm.

5. The method of claim 4, wherein: The titanium dioxide sol in step (1) is a nano titanium dioxide sol.

6. The method of claim 1 or 4, wherein: The preparation method of the titanium dioxide sol is: (a) uniformly mix glacial acetic acid, anhydrous ethanol and deionized water at room temperature to prepare solution A, wherein the mass ratio of deionized water, glacial acetic acid and anhydrous ethanol is 5:1-8:3-10; (b) uniformly mix tetrabutyl titanate and anhydrous ethanol at room temperature to prepare solution B, wherein the mass ratio of tetrabutyl titanate to anhydrous ethanol is 1:0.5-2; (c) under vigorous stirring, drop solution B into solution A, the mass ratio of solution A to solution B is 1:0.5-5, the dropping rate is 10-25 mL / min, after dropping is completed, stir at room temperature for 1-3 h to obtain the titanium dioxide sol, and the stirring rate is 200-500 r / min.

7. The method of claim 1, wherein: In step (1), the honeycomb carrier is immersed in the titanium dioxide sol, and the immersion time is 2-5 min.

8. The method of claim 1, wherein: In step (1), the drying temperature is 80-120℃, and the drying time is 12-24 h; the calcination temperature is 650-800℃, and the calcination time is 3-6 h.

9. The method of claim 1, wherein: The mass content of 3-(trifluoroacetamido) pyrrolidine hydrochloride in the active metal salt solution in step (2) is 3%-5%.

10. The method of claim 1, wherein: The active metal salt solution in step (2) is a soluble metal salt, and the concentration of the active metal salt solution is 1-3 mol / L.

11. The method of claim 10, wherein: The active metal salt in step (2) is one or more of nitrate and chloride.

12. The method of claim 1, wherein: In step (2), the carrier with TiO2 coating is immersed in the active metal salt solution, and the immersion time is 2-5 min.

13. The method of claim 1, wherein: In step (2), the drying temperature is 80-120℃, and the drying time is 12-24 h; the calcination temperature is 650-800℃, and the calcination time is 3-6 h.

14. A monolithic catalyst for the catalytic combustion of methane, characterized in that which is prepared by the process according to any one of claims 1 to 13.

15. Use of a monolithic catalyst prepared by the process according to any one of claims 1 to 13 or of a monolithic catalyst according to claim 14 for the catalytic combustion of methane.

16. The use according to claim 15, characterized in that: at a space velocity of 10000h -1 ~30000h -1 , under the condition of a methane volume concentration of 1%~3.5%, T 90 ≤500℃.