A methane catalytic combustion catalyst and a preparation method thereof

Abstract

The present application relates to a kind of methane catalytic combustion catalyst and its preparation method, comprising (1) TiO2 is ultrasonically dispersed in anhydrous ethanol, hydroxyl sulfopropyl betaine is added, and mixture is prepared;(2) the mixture of step (1) and active metal salt solution are mixed and reacted;(3) after reaction, the precipitate is separated, and TiO2@ABO3 core-shell catalyst is obtained after drying and calcination.The perovskite core-shell catalyst provided by the present application is used for the catalytic combustion of methane, T 90 ≤500 ℃, with the advantages of low-temperature catalytic activity, good stability, low cost and the like.

Description

Technical Field

[0001] This invention belongs to the field of waste gas treatment technology, specifically relating to a methane catalytic combustion catalyst 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 for methane control, and its key lies in the catalyst. Catalytic combustion catalysts for methane can be broadly classified into two categories: 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] 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. At a space velocity of 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.

[0004] CN112691702A discloses a perovskite-type methane combustion catalyst, its preparation method, and its application. The perovskite-type methane combustion catalyst includes an active component and a support. The active component is loaded onto the support, which includes a titanium silicate molecular sieve, a screening method for Bacillus cereus, and its hydrogen production performance. The active component is LaSrCo. x Ni 1-x TiO6, a titanium-silicon molecular sieve, provides titanium as the active component, and the active component is supported by titanium-oxygen bonds in the titanium-silicon molecular sieve, where x is 0.4-0.7; the specific surface area of ​​the catalyst is 200 m². 2 / g-280m 2 / g. The preparation steps are as follows: First, titanium-silicon molecular sieves are impregnated in an alkaline solution to obtain modified titanium-silicon molecular sieves. Then, the modified titanium-silicon molecular sieves are added to a metal salt aqueous solution, and citric acid is added and mixed. After heating, a precipitant is added for aging, and calcination is performed to obtain a catalyst semi-finished product. Then, the catalyst semi-finished product, alumina, binder, and extrusion aid are extruded and calcined to obtain the catalyst. The metal salts in the metal salt aqueous solution include lanthanum salt, strontium salt, cobalt salt, and nickel salt. This catalyst can convert 10% of methane at temperatures below 450℃, reaching the ignition temperature. However, the final conversion temperature for converting 90% of methane is around 625℃, and the low-temperature catalytic activity needs to be improved.

[0005] In recent years, core-shell structured materials have been widely used in the research and development of catalytic materials due to their advantages such as controllable size, regular shape, and superior catalytic effect and stability compared to general supported catalysts.

[0006] CN105562122A discloses a perovskite-type core-shell structured metal oxide, which has the advantages of large specific surface area, uniform particle size, and good stability. The general formula of the metal oxide is ABO3, where A is a rare earth element and B is a transition metal element. The metal oxide has an oxide of A as the core and an oxide of B as the shell. The catalyst is prepared by hydrothermal method, including the following steps: (1) Dissolve the salts of A and B in water according to the stoichiometric ratio of A and B in the general formula ABO3, add a surfactant, stir evenly or until transparent to obtain a mixed solution; (2) Transfer the mixed solution obtained in step (1) to a high-pressure reactor, heat for hydrothermal reaction, centrifuge and wash after the reaction to obtain a precipitate; (3) Dry and calcine the precipitate obtained in step (2) to obtain the perovskite-type core-shell structured metal oxide. It is applied in a variety of catalytic reactions, such as hydrocarbon catalytic oxidation, CO oxidation and photocatalysis. However, the catalyst is obtained by high-temperature calcination during preparation, which easily leads to a low specific surface area, thus affecting the low-temperature catalytic activity of the catalyst. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a catalyst for the catalytic combustion of methane and its preparation method. The perovskite core-shell 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, good stability, and low cost.

[0008] The method for preparing the methane catalytic combustion catalyst provided by the present invention includes the following steps:

[0009] (1) Disperse TiO2 in anhydrous ethanol by ultrasonication, and add hydroxysulfopropyl betaine to obtain a mixture;

[0010] (2) Mix the mixture from step (1) with the active metal salt solution and react them;

[0011] (3) After the reaction, the precipitate was separated, and TiO2@ABO3 core-shell catalyst was obtained by drying and calcining.

[0012] In this invention, the TiO2 in step (1) is preferably rutile type with a particle size of 40-60 nm.

[0013] In this invention, the mass-to-volume ratio of TiO2 to anhydrous ethanol in step (1) is 1g:10-30mL, preferably 1g:10-20mL.

[0014] In this invention, the frequency of ultrasonic dispersion in step (1) is 2-4 kHz, and the ultrasonic time is 10-30 min.

[0015] In this invention, the mass ratio of hydroxysulfopropyl betaine to TiO2 added in step (1) is 1:5 to 20, preferably 1:10 to 15. After addition, ultrasonic treatment is continued at 2 to 4 kHz for 30 to 60 minutes.

[0016] 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.

[0017] In this invention, further, in step (2), hydroquinone is added to the active metal salt solution, and the mass concentration of hydroquinone in the solution after addition is 3% to 5%.

[0018] In this invention, the active metal salt solution and the mixture from step (1) are mixed at a molar ratio of TiO2 to active metal of 1:1 to 5. After mixing, the mixture is stirred at 40 to 70°C for 1 to 3 hours at a stirring rate of 200 to 500 r / min.

[0019] In this invention, step (3) uses a conventional solid-liquid separation method to separate the precipitate, preferably centrifugal separation.

[0020] In this invention, the drying temperature in step (3) is 80-120°C and the drying time is 12-24 hours.

[0021] In this invention, the roasting temperature in step (3) is 700-800℃ and the roasting time is 4-6 hours.

[0022] The methane catalytic combustion catalyst of this invention is prepared by the method described above. The prepared catalyst is a TiO2@ABO3 catalyst with a perovskite metal oxide (ABO3) shell and a TiO2 core, and the ABO3 shell thickness is 5-35 nm.

[0023] This invention also provides the application of the prepared methane catalytic combustion catalyst for the catalytic combustion of methane at low temperatures, which has the advantages of high low-temperature catalytic activity and good stability.

[0024] In this invention, the volume hourly space velocity is 10000 h⁻¹. -1 ~30000h -1 Under conditions of methane volume concentration of 1% to 3%, T 90 ≤500℃.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The inventors of this application discovered in their research that perovskite catalysts are prone to high crystallinity and small specific surface area after high-temperature calcination during preparation, resulting in poor low-temperature catalytic activity. Based on this, the inventors of this application introduced hydroxysulfopropyl betaine into the catalyst preparation process to prepare a core-shell catalyst with TiO2 as the core and perovskite metal oxide as the shell. The TiO2 support has an electrically neutral and stable structure, and the charged hydroxysulfopropyl betaine and metal salt are easily and uniformly dispersed around it. During the interaction of the three, a stable core-shell structure is formed, which has excellent low-temperature activity and stability.

[0027] (2) Introducing hydroxysulfopropyl betaine during catalyst preparation allows the A-site cation to bind with the hydroxyl anion group of hydroxysulfopropyl betaine, while the sulfonic acid anion interacts with the B-site metal, effectively connecting the support and the active metal to form a uniform and stable core-shell structure. Furthermore, the strong electronegativity of N and S in hydroxysulfopropyl betaine creates an electron-withdrawing inductive effect, optimizing the arrangement of metal oxides and contributing to the stability of the core-shell structure.

[0028] (3) Hydroquinone is introduced into the active metal salt solution. Hydroquinone has a para-hydroxyl structure. When it works together with hydroxysulfopropyl betaine, it can not only increase the concentration of metal cations on the TiO2 surface, but also help maintain the stability of the core-shell structure. Detailed Implementation

[0029] 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.

[0030] 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.

[0031] In this embodiment of the invention, T 10 T represents the methane ignition temperature at which the methane conversion rate reaches 10%. 90 This indicates the methane ignition temperature at which the methane conversion rate reaches 90%.

[0032] Example 1

[0033] (1) Take 5g of 40nm rutile TiO2 and ultrasonically disperse it in 75mL of anhydrous ethanol. The ultrasonic frequency is 2KHz and the ultrasonic time is 15min. After adding 0.375g of hydroxysulfopropyl betaine, continue to ultrasonic at 2KHz for 30min to obtain a mixture.

[0034] (2) Prepare an active metal salt solution with a concentration of 2.5 mol / L, wherein metal salt A is La(NO3)3·6H2O, metal salt B is 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; mix the mixture and the active metal salt solution according to the molar ratio of TiO2 to active metal is 1:4, and stir the reaction at 60℃ for 2.5 hours at a stirring speed of 300 r / min.

[0035] (3) After the reaction was completed, the precipitate was separated by centrifugation, dried at 100℃ for 12 hours and calcined at 750℃ for 4 hours to obtain TiO2@LaNi. 0.2 Fe 0.8 O3 core-shell catalyst, wherein the shell thickness is 23-27 nm.

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

[0037] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 465℃. After continuous operation at 465℃ for 100 hours, the methane removal rate was 88.7%.

[0038] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At a temperature of 458℃, the methane removal rate was 86.9% after 100 hours of continuous operation.

[0039] Example 2

[0040] (1) Take 10g of 40nm rutile TiO2 and ultrasonically disperse it in 100mL of anhydrous ethanol. The ultrasonic frequency is 2KHz and the ultrasonic time is 10min. After adding 1g of hydroxysulfopropyl betaine, continue to ultrasonic at 2KHz for 60min to obtain a mixture.

[0041] (2) Prepare an active metal salt solution with a concentration of 2.5 mol / L, wherein metal salt A is La(NO3)3·6H2O, metal salt B is 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; mix the mixture and the active metal salt solution according to the molar ratio of TiO2 to active metal of 1:1, stir at 70℃ for 2.5 hours, and stir at 300 r / min.

[0042] (3) After the reaction was completed, the precipitate was separated by centrifugation, dried at 80℃ for 24 hours and calcined at 800℃ for 4 hours to obtain TiO2@LaNi. 0.2 Fe 0.8 O3 core-shell catalyst, wherein the shell thickness is 25-29 nm.

[0043] The results of the catalyst activity evaluation are as follows:

[0044] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 466℃. After continuous operation at 466℃ for 100 hours, the methane removal rate was 87.7%.

[0045] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At a temperature of 462℃, the methane removal rate was 85.3% after 100 hours of continuous operation.

[0046] Example 3

[0047] (1) Take 4g of 60nm rutile TiO2 and ultrasonically disperse it in 80mL of anhydrous ethanol. The ultrasonic frequency is 3KHz and the ultrasonic time is 30min. After adding 0.3g of hydroxysulfopropyl betaine, continue to ultrasonic at a frequency of 2KHz for 30min to obtain a mixture.

[0048] (2) Prepare an active metal salt solution with a concentration of 3.0 mol / L, wherein metal salt A is La(NO3)3·6H2O, metal salt B is 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; mix the mixture and the active metal salt solution according to the molar ratio of TiO2 to active metal is 1:5, and stir the reaction at 70℃ for 2.5 hours at a stirring speed of 300 r / min.

[0049] (3) After the reaction was completed, the precipitate was separated by centrifugation, dried at 120℃ for 12 hours and calcined at 800℃ for 4 hours to obtain TiO2@LaNi. 0.2 Fe 0.8 O3 core-shell catalyst, wherein the shell thickness is 22-27 nm.

[0050] The results of the catalyst activity evaluation are as follows:

[0051] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 470℃. After continuous operation at 470℃ for 100 hours, the methane removal rate was 88.3%.

[0052] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At a temperature of 467°C, the methane removal rate was 87.1% after 100 hours of continuous operation.

[0053] Example 4

[0054] (1) Take 5g of 40nm rutile TiO2 and ultrasonically disperse it in 75mL of anhydrous ethanol. The ultrasonic frequency is 2KHz and the ultrasonic time is 15min. After adding 0.375g of hydroxysulfopropyl betaine, continue to ultrasonic at 2KHz for 30min to obtain a mixture.

[0055] (2) Prepare an active metal salt solution with a concentration of 2.5 mol / L, wherein metal salt A is Ce(NO3)3·6H2O, metal salt B is 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; mix the mixture and the active metal salt solution according to the molar ratio of TiO2 to active metal is 1:4, and stir the reaction at 60℃ for 2.5 hours at a stirring speed of 300 r / min.

[0056] (3) After the reaction was completed, the precipitate was separated by centrifugation, dried at 100℃ for 12 hours and calcined at 750℃ for 4 hours to obtain TiO2@CeNi. 0.2 Fe 0.8 O3 core-shell catalyst, wherein the shell thickness is 28-33 nm.

[0057] The results of the catalyst activity evaluation are as follows:

[0058] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 464℃. After continuous operation at 464℃ for 100 hours, the methane removal rate was 88.0%.

[0059] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At a temperature of 458℃, the methane removal rate was 86.6% after 100 hours of continuous operation.

[0060] Example 5

[0061] (1) Take 5g of 40nm rutile TiO2 and ultrasonically disperse it in 75mL of anhydrous ethanol. The ultrasonic frequency is 2KHz and the ultrasonic time is 15min. After adding 0.375g of hydroxysulfopropyl betaine, continue to ultrasonic at 2KHz for 30min to obtain a mixture.

[0062] (2) Prepare an active metal salt solution with a concentration of 2.5 mol / L, wherein metal salt A is La(NO3)3·6H2O, metal salt B is Mn(NO3)2·6H2O and Co(NO3)2·6H2O, wherein the molar ratio of A to B is 1:1, and the molar ratio of Co to Mn is 0.2:0.8; mix the mixture and the active metal salt solution according to the molar ratio of TiO2 to active metal is 1:4, and stir the reaction at 60℃ for 2.5 hours at a stirring speed of 300 r / min.

[0063] (3) After the reaction was completed, the precipitate was separated by centrifugation, dried at 100℃ for 12 hours and calcined at 750℃ for 4 hours to obtain TiO2@LaCo.0.2 Mn 0.8 O3 core-shell catalyst, wherein the shell thickness is 24-27 nm.

[0064] The results of the catalyst activity evaluation are as follows:

[0065] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 478℃. After continuous operation at 478℃ for 100 hours, the methane removal rate was 89.0%.

[0066] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At a temperature of 474℃, the methane removal rate was 87.5% after 100 hours of continuous operation.

[0067] Example 6

[0068] (1) Take 5g of 40nm rutile TiO2 and ultrasonically disperse it in 75mL of anhydrous ethanol. The ultrasonic frequency is 2KHz and the ultrasonic time is 15min. After adding 0.375g of hydroxysulfopropyl betaine, continue to ultrasonic at 2KHz for 30min to obtain a mixture.

[0069] (2) Prepare an active metal salt solution with a concentration of 2.5 mol / L, wherein metal salt A is La(NO3)3·6H2O, metal salt B is 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; add hydroquinone to the active metal salt solution, and the mass concentration of hydroquinone in the solution after the addition is 3.39%; mix the mixture and the active metal salt solution according to the molar ratio of TiO2 to active metal of 1:4, stir at 60℃ for 2.5 hours, and stir at 300 r / min.

[0070] (3) After the reaction was completed, the precipitate was separated by centrifugation, dried at 100℃ for 12 hours and calcined at 750℃ for 4 hours to obtain TiO2@LaNi. 0.2 Fe 0.8 O3 core-shell catalyst, wherein the shell thickness is 26-29 nm.

[0071] The results of the catalyst activity evaluation are as follows:

[0072] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 453℃. After continuous operation at 453℃ for 100 hours, the methane removal rate was 89.1%.

[0073] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At 450℃, the methane removal rate was 88.5% after continuous operation for 100 hours.

[0074] Example 7

[0075] (1) Take 5g of 40nm rutile TiO2 and ultrasonically disperse it in 75mL of anhydrous ethanol. The ultrasonic frequency is 2KHz and the ultrasonic time is 15min. After adding 0.375g of hydroxysulfopropyl betaine, continue to ultrasonic at 2KHz for 30min to obtain a mixture.

[0076] (2) Prepare an active metal salt solution with a concentration of 2.5 mol / L, wherein metal salt A is La(NO3)3·6H2O, metal salt B is Mn(NO3)2·6H2O and Co(NO3)2·6H2O, wherein the molar ratio of A to B is 1:1, and the molar ratio of Co to Mn is 0.2:0.8; add hydroquinone to the active metal salt solution, and the mass concentration of hydroquinone in the solution after the addition is 5.0%; mix the mixture and the active metal salt solution according to the molar ratio of TiO2 to active metal of 1:4, and stir the reaction at 60℃ for 2.5 hours at a stirring speed of 300 r / min.

[0077] (3) After the reaction was completed, the precipitate was separated by centrifugation, dried at 100℃ for 12 hours and calcined at 750℃ for 4 hours to obtain TiO2@LaCo. 0.2 Mn 0.8 O3 core-shell catalyst, wherein the shell thickness is 24-28 nm.

[0078] The results of the catalyst activity evaluation are as follows:

[0079] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 469℃. After continuous operation at 469℃ for 100 hours, the methane removal rate was 89.2%.

[0080] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At a temperature of 463℃, the methane removal rate was 89.3% after 100 hours of continuous operation.

[0081] Example 8

[0082] (1) Take 5g of 40nm rutile TiO2 and ultrasonically disperse it in 75mL of anhydrous ethanol. The ultrasonic frequency is 2KHz and the ultrasonic time is 15min. After adding 0.375g of hydroxysulfopropyl betaine, continue to ultrasonic at 2KHz for 30min to obtain a mixture.

[0083] (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 salt B is Fe(NO3)3·9H2O, and the molar ratio of A to B is 1:1; add hydroquinone to the active metal salt solution, and the mass concentration of hydroquinone in the solution after the addition is 3.39%; mix the mixture and the active metal salt solution according to the molar ratio of TiO2 to active metal of 1:4, and stir the reaction at 60℃ for 2.5 hours at a stirring speed of 300 r / min.

[0084] (3) After the reaction was completed, the precipitate was separated by centrifugation, dried at 100℃ for 12 hours and calcined at 750℃ for 4 hours to obtain TiO2@LaNi. 0.2 Fe 0.8 O3 core-shell catalyst, wherein the shell thickness is 25-30 nm.

[0085] The results of the catalyst activity evaluation are as follows:

[0086] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 459℃. After continuous operation at 459℃ for 100 hours, the methane removal rate was 88.9%.

[0087] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At a temperature of 457°C, the methane removal rate was 88.8% after 100 hours of continuous operation.

[0088] Comparative Example 1

[0089] Same as Example 1, except that: hydroxysulfopropyl betaine was not added in step (1), and the final catalyst did not form a core-shell structure. The activity evaluation results of the prepared catalyst are as follows:

[0090] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 570℃. After continuous operation at 570℃ for 100 hours, the methane removal rate was 88.2%.

[0091] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90The temperature was 562℃. After continuous operation at 562℃ for 100 hours, the methane removal rate was 87.8%.

[0092] Comparative Example 2

[0093] Same as Example 1, except that in step (1), alkylamide betaine was used instead of hydroxysulfonyl betaine, and the resulting catalyst did not form a core-shell structure. The activity evaluation results of the prepared catalyst are as follows:

[0094] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 569℃. After continuous operation at 569℃ for 100 hours, the methane removal rate was 88.4%.

[0095] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At a temperature of 558℃, the methane removal rate was 86.7% after 100 hours of continuous operation.

[0096] Comparative Example 3

[0097] Similar to Example 1, except that step (1) used conventional stirring instead of ultrasonic dispersion, resulting in a non-uniform catalyst shell ranging from 13 to 37 nm. The activity evaluation results of the prepared catalyst are as follows:

[0098] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 525℃. After continuous operation at 525℃ for 100 hours, the methane removal rate was 85.8%.

[0099] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At a temperature of 515℃, the methane removal rate was 86.2% after 100 hours of continuous operation.

[0100] Comparative Example 4

[0101] Same as Example 1, except that step (1) uses γ-Al2O3 instead of TiO2 to finally obtain the catalyst. The activity evaluation results of the prepared catalyst are as follows:

[0102] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 545℃. After continuous operation at 545℃ for 100 hours, the methane removal rate was 85.6%.

[0103] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹-1 Under the condition, T 90 At a temperature of 532℃, the methane removal rate was 84.3% after 100 hours of continuous operation.

[0104] Comparative Example 5

[0105] Similar to Example 1, except that in step (1), 75% ethanol was used instead of anhydrous ethanol, resulting in a catalyst with an uneven shell thickness ranging from 12 nm to 41 nm. The activity evaluation results of the prepared catalyst are as follows:

[0106] With a methane volume concentration of 1% and a volume hourly space velocity of 30,000 h⁻¹ -1 Under the condition, T 90 The temperature was 520℃. After continuous operation at 520℃ for 100 hours, the methane removal rate was 85.1%.

[0107] With a methane volume concentration of 3% and a volume hourly space velocity of 10,000 h⁻¹ -1 Under the condition, T 90 At a temperature of 516℃, the methane removal rate was 85.4% after continuous operation at 515℃ for 100 hours.

Claims

1. A process for the preparation of a methane catalytic combustion catalyst, characterized in that It comprises the following steps: (1) dispersing TiO2 in anhydrous ethanol by ultrasonic, adding hydroxyl sulfopropyl betaine to prepare a mixture; the mass ratio of the added hydroxyl sulfopropyl betaine to TiO2 is 1:5-20; (2) mixing and reacting the mixture in step (1) with a solution of active metal salt; the active metal is a non-noble metal, and specifically comprises two kinds of 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, and the molar ratio of the active metals A and B is 1:1; the solution of active metal salt is mixed with the mixture in step (1) according to the molar ratio of TiO2 to active metal of 1:1-5; (3) separating the precipitate after the reaction, drying and calcining to obtain a TiO2@ABO3 core-shell catalyst.

2. The method of claim 1, wherein: In step (1), the TiO2 is rutile type, and the particle size is 40-60 nm.

3. The method of claim 1, wherein: In step (1), the mass-volume ratio of TiO2 to anhydrous ethanol is 1g:10-30 mL.

4. The method of claim 3, wherein: In step (1), the mass-volume ratio of TiO2 to anhydrous ethanol is 1g:10-20 mL.

5. The method of claim 1, wherein: In step (1), the frequency of ultrasonic dispersion is 2-4 KHz, and the ultrasonic time is 10-30 min.

6. The method of claim 1, wherein: In step (1), the mass ratio of the added hydroxyl sulfopropyl betaine to TiO2 is 1:10-15.

7. The method of claim 1 or 5, wherein: After the addition of the hydroxyl sulfopropyl betaine in step (1), the ultrasonic treatment is continued at 2-4 KHz for 30-60 min.

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

9. The method of claim 8, wherein: In step (2), the solution of active metal salt is one or more of nitrate and chloride.

10. The method of claim 1, wherein: In step (2), hydroquinone is added to the solution of active metal salt, and the mass concentration of hydroquinone in the solution after the addition is 3%-5%.

11. The method of claim 1, wherein: In step (2), after the mixing, the stirring reaction is carried out at 40-70°C for 1-3 hours, and the stirring rate is 200-500 r / min.

12. The method of claim 1, wherein: In step (3), the drying temperature is 80-120°C, and the drying time is 12-24 hours.

13. The method of claim 1, wherein: In step (3), the calcining temperature is 700-800°C, and the calcining time is 4-6 hours.

14. A methane catalytic combustion catalyst characterized by It is prepared by the method in any one of claims 1-13.

15. The catalyst of claim 14, wherein: The prepared catalyst is a catalyst with a perovskite metal oxide ABO3 as a shell layer and TiO2 as a core, and the shell layer has a thickness of 5-35 nm.

16. A methane catalytic combustion catalyst prepared by the method in any one of claims 1-13 or the application of the methane catalytic combustion catalyst in any one of claims 14-15 to the catalytic combustion of methane at low temperature.

17. Use according to claim 16, characterized in that: at a space velocity of 10000h -1 ~30000h -1 , under the condition of a methane volume concentration of 1%~3%, T 90 ≤500℃.