Palladium-based methane combustion catalyst as well as preparation method and application thereof

Abstract

The invention relates to a palladium-based methane combustion catalyst and a preparation method and application thereof.The preparation method comprises the following steps that after a titanium source, a cerium source and a complexing agent are mixed to obtain mixed sol, evaporation, drying and sintering are conducted in sequence, and a cerium-titanium carrier is obtained; dipping and mixing the cerium-titanium carrier and the palladium source, and sequentially drying and roasting to obtain the palladium-based methane combustion catalyst. The preparation method is simple to operate, the raw materials are low in price and easy to obtain, and the prepared palladium-based methane combustion catalyst is low in light-off temperature, has water resistance and can be applied to methane treatment in tail gas.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a palladium-based methane combustion catalyst and a preparation method and application thereof. Background Art

[0002] Global warming is accelerating, the climate system is more unstable, and extreme weather and climate events are becoming more frequent, strong, and widespread. Climate change has become a major challenge facing human survival and development in the 21st century. CH4 is the world's second largest greenhouse gas after carbon dioxide, and its emissions account for 16% of the world's total greenhouse gas emissions. Compared with carbon dioxide, CH4 exists in the atmosphere for a shorter time, but has a stronger ability to absorb heat. The global warming potential of methane is 27.9 times that of carbon dioxide on a 100-year scale and 81.2 times on a 20-year scale, and methane persists in the atmosphere for about 12 years. Since the beginning of the Industrial Revolution, CH4 emissions have contributed about 20% to the global greenhouse effect. Effective control of CH4 emissions has the climate benefits of slowing global temperature rise, the economic benefits of energy resource utilization, the safety benefits of reducing production accidents, and the environmental benefits of coordinated control of pollutants. Therefore, methane emission reduction has received widespread attention from the international community.

[0003] The main component of natural gas is CH4, and the S and N content is much lower than other primary energy sources (oil and coal). It also has a low carbon-to-hydrogen ratio, high calorific value, and produces less secondary pollution. It is considered to be the energy category with the least impact on the environment among fossil energy in the carbon neutral era. Compared with gasoline, natural gas has abundant reserves, low cost, is easy to mix with air, and emits less NO under high load conditions. x , CO, CH, and PM are low, and the products after complete combustion are mainly CO2 and H2O, which is beneficial to environmental protection. Therefore, it is widely used in internal combustion engine power generation and natural gas vehicles (NGVs). However, unburned CH4 in the exhaust gas will cause harm to the environment. At the same time, the CH4 emission limit for heavy-duty vehicles is 0.5g / km, which is a low emission limit. Therefore, the development of a catalyst for catalyzing methane combustion reaction to remove CH4 from the exhaust gas of natural gas vehicle engines has become a problem that needs to be solved urgently. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a palladium-based methane combustion catalyst and a preparation method and application thereof. A cerium-titanium carrier is prepared by a gel method plus a sintering treatment, and the palladium-based methane combustion catalyst is prepared by an impregnation method plus a calcination treatment. The preparation method is simple to operate, and the raw materials are cheap and easy to obtain. The prepared palladium-based methane combustion catalyst has a low ignition temperature and water resistance, and can also maintain excellent activity when used for methane treatment in tail gas.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a palladium-based methane combustion catalyst, the preparation method comprising the following steps:

[0007] (1) mixing a titanium source, a cerium source and a complexing agent to obtain a mixed sol, and then evaporating, drying and sintering in sequence to obtain a cerium-titanium carrier;

[0008] (2) impregnating and mixing the cerium-titanium carrier and the palladium source, and drying and calcining them in sequence to obtain the palladium-based methane combustion catalyst.

[0009] The invention prepares the cerium-titanium carrier by a gel method and a sintering treatment, and then prepares the palladium-based methane combustion catalyst by an impregnation method and a calcination treatment. The preparation method is simple to operate, and the raw materials are cheap and easy to obtain. The prepared palladium-based methane combustion catalyst has a low ignition temperature and certain water resistance, and also maintains excellent activity when applied to methane treatment in tail gas.

[0010] Preferably, the titanium source in step (1) comprises tetrabutyl titanate.

[0011] Preferably, the cerium source in step (1) comprises cerium nitrate.

[0012] Preferably, the complexing agent in step (1) comprises citric acid.

[0013] Preferably, the molar ratio of the titanium source, cerium source and complexing agent in step (1) is (1-3):(1-3):(1-1.2), for example, it can be 1:3:1, 3:1:1, 1:1:1, 1:1:1.1 or 1:1:1.2, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] The present invention selects citric acid as the complexing agent, because citric acid is a ternary weak acid, can undergo multi-level ionization, the metal ions in the solution will coordinate with the carboxylate radicals in the citric acid, and then combine to form a three-dimensional network structure; and can promote the dispersion of various components in the raw materials to achieve molecular level or even atomic level uniformity.

[0015] There is an optimal range for the amount of complexing agent used. When the amount of complexing agent is large, it will affect the catalytic performance of the catalyst; when the amount of complexing agent is small, it will affect the dispersion of each component and thus affect the catalytic performance of the catalyst.

[0016] Preferably, the evaporation temperature in step (1) is 60-90°C, for example, 60°C, 70°C, 80°C, 85°C or 90°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] Preferably, the evaporation device in step (1) comprises a constant temperature water bath.

[0018] Preferably, after the evaporation in step (1), a mixed gel is obtained.

[0019] Preferably, the drying temperature in step (1) is 100-140°C, for example, 100°C, 110°C, 120°C, 130°C or 140°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, the drying time in step (1) is 8-16 hours, for example, 8 hours, 10 hours, 12 hours, 14 hours or 16 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the sintering in step (1) is divided into three stages.

[0022] Preferably, the temperature of the first stage sintering is 180-200°C, for example, 180°C, 185°C, 190°C, 195°C or 200°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the sintering time is 1-2 hours, for example, 1 hour, 1.2 hours, 1.5 hours, 1.8 hours or 2 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] Preferably, the temperature of the second-stage sintering is 300-400°C, for example, 300°C, 320°C, 350°C, 380°C or 400°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] Preferably, the second-stage sintering time is 1-2 hours, for example, 1 hour, 1.2 hours, 1.5 hours, 1.8 hours or 2 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0026] Preferably, the temperature of the three-stage sintering is 500-1200°C, for example, it can be 500°C, 600°C, 800°C, 1000°C, 1100°C or 1200°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] Preferably, the three-stage sintering time is 3.5-4.5 h, for example, 3.5 h, 3.8 h, 4 h, 4.2 h or 4.5 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] The present invention can not only remove the complexing agent but also obtain a uniform cerium-titanium carrier through three-stage sintering.

[0029] Preferably, based on the total mass of the cerium titanium support and the palladium source as 100%, the content of the palladium source in step (2) is 1.9-3.1%, for example, it can be 1.9%, 2.0%, 2.5%, 2.7% or 3.1%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, the palladium source in step (2) comprises palladium nitrate.

[0031] Preferably, the impregnation and mixing in step (2) includes stirring.

[0032] Preferably, the drying temperature in step (2) is 80-120°C, for example, 80°C, 90°C, 100°C, 110°C or 120°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] Preferably, the drying time in step (2) is 8-16 hours, for example, 8 hours, 10 hours, 12 hours, 14 hours or 16 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] Preferably, the calcination temperature in step (2) is 525-575°C, for example, 525°C, 535°C, 550°C, 565°C or 575°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] Preferably, the calcination time in step (2) is 2.5-3.5 h, for example, 2.5 h, 2.8 h, 3 h, 3.2 h or 3.5 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0036] As a preferred technical solution of the present invention, the preparation method of the palladium-based methane combustion catalyst comprises the following steps:

[0037] (1) mixing a titanium source, a cerium source and a complexing agent to obtain a mixed sol, evaporating the mixed sol in a constant temperature water bath to obtain a mixed gel; drying the mixed gel at 100-140° C. for 8-16 hours, firstly keeping the mixed gel at 180-200° C. for 1-2 hours, then keeping the mixed gel at 300-400° C. for 1-2 hours, and finally keeping the mixed gel at 500-1200° C. for 3.5-4.5 hours, and then completing three-stage sintering to obtain the cerium titanium carrier;

[0038] (2) After impregnating the mixed cerium titanium carrier and the palladium source, the mixture is first dried at 80-120° C. for 8-16 hours, and then calcined at 525-575° C. for 2.5-3.5 hours to obtain the palladium-based methane combustion catalyst.

[0039] In a second aspect, the present invention provides a palladium-based methane combustion catalyst, which is prepared according to the preparation method described in the first aspect.

[0040] Preferably, the support of the catalyst comprises a cerium-titanium support, and the active component of the catalyst comprises a palladium oxide compound.

[0041] Preferably, the cerium-titanium support comprises a cerium-titanium composite oxide.

[0042] Preferably, the loading amount of the palladium element is 0.75-1.25wt%, for example, it can be 0.75wt%, 0.9wt%, 1.05wt%, 1.1wt% or 1.25wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] In a third aspect, the present invention provides an application of the catalyst described in the second aspect, wherein the catalyst is applied to methane combustion catalysis.

[0044] Preferably, the catalyst is used for treating methane in tail gas.

[0045] Compared with the prior art, the present invention has at least the following beneficial effects:

[0046] (1) The present invention provides a palladium-based methane combustion catalyst and a preparation method and application thereof. A cerium-titanium carrier is prepared by a gel method and a sintering treatment, and then the palladium-based methane combustion catalyst is prepared by an impregnation method and a calcination treatment. The preparation method is simple to operate and the raw materials are cheap and easy to obtain;

[0047] (2) The palladium-based methane combustion catalyst prepared by the present invention has a low ignition temperature and a certain water resistance. When used for treating methane in tail gas, it also maintains excellent activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is the conversion rate of CH4 by the palladium-based methane combustion catalysts prepared in Examples 1 and 4-10 of the present invention;

[0049] Figure 2 It is the conversion rate of CH4 under water-containing conditions of the palladium-based methane combustion catalysts prepared in Example 1 and Examples 4-10 of the present invention. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0051] Example 1

[0052] This embodiment provides a method for preparing a palladium-based methane combustion catalyst, the preparation method comprising the following steps:

[0053] (1) Weighing 1 part of tetrabutyl titanate and 1 part of glacial acetic acid into a beaker, adding deionized water dropwise under stirring with a magnetic stirrer to obtain a transparent titanium precursor solution; then adding 1 part of cerium nitrate solution as the solute dropwise into the solution, and then adding 1.2 parts of citric acid solution as the solute to obtain a mixed solution, and evaporating the mixed solution in a constant temperature water bath at 80° C. until a mixed gel is obtained;

[0054] (2) drying the mixed gel at 120° C. for 12 h to obtain a mixed powder, and sintering the mixed powder in sequence at 200° C. for 2 h in the first stage, 400° C. for 2 h in the second stage, and 1000° C. for 4 h in the third stage to obtain a cerium-titanium carrier;

[0055] (3) Weighing a cerium titanium carrier and palladium nitrate so that the loading amount of the precious metal palladium element is 1 wt%, adding deionized water respectively and immersing and stirring to mix, after removing excess water by rotary evaporation, drying at 100° C. for 12 h, and then calcining at 550° C. for 3 h, to obtain the palladium-based methane combustion catalyst.

[0056] Example 2

[0057] This embodiment provides a method for preparing a palladium-based methane combustion catalyst, the preparation method comprising the following steps:

[0058] (1) Weighing 3 parts of tetrabutyl titanate and 1 part of glacial acetic acid into a beaker, adding deionized water dropwise under stirring with a magnetic stirrer to obtain a transparent titanium precursor solution; then adding 1 part of cerium nitrate solution as the solute dropwise into the solution, and then adding 1 part of citric acid solution as the solute to obtain a mixed solution, and evaporating the mixed solution in a constant temperature water bath at 60° C. until a mixed gel is obtained;

[0059] (2) drying the mixed gel at 100° C. for 16 h to obtain a mixed powder, and sintering the mixed powder in sequence at 180° C. for 2 h in the first stage, 300° C. for 2 h in the second stage, and 1200° C. for 3.5 h in the third stage to obtain a cerium-titanium carrier;

[0060] (3) Weighing a cerium titanium carrier and palladium nitrate so that the loading amount of the precious metal palladium element is 0.75 wt%, adding deionized water respectively and immersing and stirring to mix, after removing excess water by rotary evaporation, drying at 80° C. for 16 h, and then calcining at 525° C. for 3.5 h, to obtain the palladium-based methane combustion catalyst.

[0061] Example 3

[0062] This embodiment provides a method for preparing a palladium-based methane combustion catalyst, the preparation method comprising the following steps:

[0063] (1) Weighing 1 part of tetrabutyl titanate and 1 part of glacial acetic acid into a beaker, adding deionized water dropwise under stirring with a magnetic stirrer to obtain a transparent titanium precursor solution; then adding 3 parts of cerium nitrate solution as the solute dropwise into the solution, and then adding 1.2 parts of citric acid solution as the solute to obtain a mixed solution, and evaporating the mixed solution in a constant temperature water bath at 90° C. until a mixed gel is obtained;

[0064] (2) drying the mixed gel at 140° C. for 8 h to obtain a mixed powder, and sintering the mixed powder in sequence at 220° C. for 1 h in the first stage, 400° C. for 1 h in the second stage, and 500° C. for 4.5 h in the third stage to obtain a cerium-titanium carrier;

[0065] (3) Weighing a cerium titanium carrier and palladium nitrate so that the loading amount of the precious metal palladium element is 1.25 wt%, adding deionized water respectively and immersing and stirring to mix, after removing excess water by rotary evaporation, drying at 120° C. for 8 h, and then calcining at 575° C. for 2.5 h to obtain the palladium-based methane combustion catalyst.

[0066] Example 4

[0067] The only difference between this embodiment and embodiment 1 is that, except for the three-stage sintering temperature of step (2) being 500° C., the rest is the same as embodiment 1.

[0068] Example 5

[0069] The only difference between this embodiment and embodiment 1 is that, except for the three-stage sintering temperature of step (2) being 600° C., the rest is the same as embodiment 1.

[0070] Example 6

[0071] The only difference between this embodiment and embodiment 1 is that, except for the three-stage sintering temperature of step (2) being 700° C., the rest is the same as embodiment 1.

[0072] Example 7

[0073] The only difference between this embodiment and embodiment 1 is that, except for the three-stage sintering temperature of step (2) being 800° C., the rest is the same as embodiment 1.

[0074] Example 8

[0075] The only difference between this embodiment and embodiment 1 is that, except for the three-stage sintering temperature of step (2) being 900° C., the rest is the same as embodiment 1.

[0076] Example 9

[0077] The only difference between this embodiment and embodiment 1 is that, except for the three-stage sintering temperature of step (2) being 1100° C., the rest is the same as embodiment 1.

[0078] Example 10

[0079] The only difference between this embodiment and embodiment 1 is that, except for the three-stage sintering temperature of step (2) being 1200° C., the rest is the same as embodiment 1.

[0080] Figure 1 It is the conversion rate of CH4 of the palladium-based methane combustion catalyst prepared in Examples 1 and 4-10 of the present invention. It can be seen from the figure that the prepared catalyst has the highest conversion efficiency of methane at 1000°C;

[0081] Figure 2 It is the conversion rate of CH4 of the palladium-based methane combustion catalyst prepared in Examples 1 and 4-10 of the present invention under water conditions. It can be seen from the figure that the prepared catalyst has the highest conversion efficiency of methane at 1000°C under the influence of water vapor.

[0082] Embodiment 11

[0083] The difference between this embodiment and embodiment 1 is that, except for the addition of cerium nitrate solution in an amount of 3 parts of the solute in step (1), the rest is the same as embodiment 1.

[0084] Example 12

[0085] The difference between this embodiment and embodiment 1 is that, except for the addition of 3 parts of tetrabutyl titanate in step (1), the rest is the same as embodiment 1.

[0086] Example 13

[0087] The only difference between this embodiment and embodiment 1 is that, except that the citric acid solution in step (1) is replaced by ethanol, the rest is the same as embodiment 1.

[0088] Comparative Example 1

[0089] This comparative example provides a method for preparing a palladium-based methane combustion catalyst, the preparation method comprising the following steps:

[0090] (1) mixing 1 part of cerium nitrate and ethanol to obtain solution A; weighing 1 part of tetrabutyl titanate and 1 part of glacial acetic acid to obtain solution B; adding solution A dropwise to solution B at room temperature, stirring for 1 hour, and then transferring the mixed solution to a polytetrafluoroethylene liner;

[0091] (2) Add the polytetrafluoroethylene liner into a forced air drying oven, increase the temperature at 3°C / min, perform hydrothermal reaction at 160°C for 12 hours, centrifuge dry and grind when the temperature drops to room temperature, keep the temperature at 1000°C for 4 hours, and cool with the furnace;

[0092] (3) Using cerium-titanium composite oxide as a carrier, loading 1 wt% of precious metal palladium element, weighing the cerium-titanium carrier and palladium nitrate, adding deionized water respectively and immersing and stirring to mix, after rotary evaporation to remove excess water, first drying at 100° C. for 12 hours, and then calcining at 550° C. for 3 hours to obtain the palladium-based methane combustion catalyst.

[0093] Comparative Example 2

[0094] This comparative example provides a method for preparing a palladium-based methane combustion catalyst, the preparation method comprising the following steps:

[0095] (1) Weigh 1 part of tetrabutyl titanate and 1 part of glacial acetic acid and place them in a beaker, then add 1 part of cerium nitrate solution as solute dropwise into the solution, then titrate with ammonia water until the pH of the solution is 9, let it stand for 13 hours, and then filter to obtain a precipitate;

[0096] (2) drying the mixed gel at 120° C. for 12 h to obtain a mixed powder, and sintering the mixed powder in sequence at 200° C. for 2 h in the first stage, 400° C. for 2 h in the second stage, and 1000° C. for 4 h in the third stage to obtain a cerium-titanium carrier;

[0097] (3) Using cerium-titanium composite oxide as a carrier, loading 1 wt% of precious metal palladium element, weighing the cerium-titanium carrier and palladium nitrate, adding deionized water respectively and immersing and stirring to mix, after rotary evaporation to remove excess water, first drying at 100° C. for 12 hours, and then calcining at 550° C. for 3 hours to obtain the palladium-based methane combustion catalyst.

[0098] Test Method

[0099] The samples prepared in Examples 1-13 and Comparative Examples 1-2 were tableted, crushed, and sieved, and 40-60 mesh particles were taken to investigate the methane catalytic combustion reaction activity in a fixed bed reactor. The test conditions were: [CH4] = 0.1%, [O2] = 3.5%, N2 balance, total gas flow rate of 300mL / min, space velocity of 18,000g / (mL·h), and reaction temperature of 200-600°C. CH4 and its product CO2 were measured using an infrared spectrometer (Nicolet 670) equipped with a gas cell; the test results are shown in Table 1;

[0100] The samples prepared in Examples 1-13 and Comparative Examples 1-2 were tableted, crushed, and sieved, and 40-60 mesh particles were taken to investigate the methane catalytic combustion reaction activity in a fixed bed reactor. The test conditions were: [CH4] = 0.1%, [O2] = 3.5%, [H2O] = 10%, N2 balance, total gas flow rate of 300mL / min, space velocity of 18,000g / (mL·h), and reaction temperature of 200-500°C. CH4 and its product CO2 were measured using an infrared spectrometer (Nicolet 670) equipped with a gas cell; the test results are shown in Table 1;

[0101] Table 1

[0102]

[0103]

[0104] The test results show that:

[0105] (1) It can be seen from Examples 1-13 and Comparative Examples 1-2 that the cerium-titanium carrier is prepared by a gel method plus a sintering treatment, and the palladium-based methane combustion catalyst is prepared by an impregnation method plus a calcination treatment. The preparation method is simple to operate and the raw materials are cheap and easy to obtain. The prepared palladium-based methane combustion catalyst has a low ignition temperature and has certain water resistance. When used for the treatment of methane in exhaust gas, it also maintains excellent activity.

[0106] (2) It can be seen from Examples 1 and 4-10 that the present invention can further regulate the conversion efficiency of the methane combustion catalyst by further controlling the temperature of the three-stage sintering; when the three-stage sintering temperature is within the preferred range, the catalytic performance and conversion efficiency of the methane combustion catalyst are further improved.

[0107] (3) It can be seen from Example 1 and Examples 11-12 that the present invention can further regulate the conversion efficiency of the methane combustion catalyst by further controlling the molar ratio of the titanium source and the cerium source; when the molar ratio of the titanium source and the cerium source is within the preferred range, the catalytic performance and conversion efficiency of the methane combustion catalyst are further improved.

[0108] (4) It can be seen from Example 1 and Example 13 that the methane combustion catalyst prepared by the present invention using citric acid as a complexing agent has certain water resistance and the catalyst has a high conversion efficiency.

[0109] (5) It can be seen from Example 1 and Comparative Examples 1-2 that when the catalyst is prepared by the citric acid method, the catalytic performance of the catalyst is excellent under dry and water vapor conditions, indicating that it has certain water resistance and the conversion efficiency of the catalyst is high.

[0110] In summary, the present invention prepares the cerium-titanium carrier through a gel method plus a sintering treatment, and then prepares the palladium-based methane combustion catalyst through an impregnation method plus a calcination treatment. The preparation method is simple to operate, and the raw materials are cheap and easy to obtain; the prepared palladium-based methane combustion catalyst has a low ignition temperature and has certain water resistance. When used for methane treatment in exhaust gas, it also maintains excellent activity.

[0111] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a palladium-based methane combustion catalyst, characterized in that: The preparation method comprises the following steps: (1) mixing a titanium source, a cerium source and a complexing agent to obtain a mixed sol, and then evaporating, drying and sintering in sequence to obtain a cerium-titanium carrier; (2) impregnating and mixing the cerium-titanium carrier and the palladium source, and drying and calcining them in sequence to obtain the palladium-based methane combustion catalyst.

2. The preparation method according to claim 1, characterized in that: The titanium source in step (1) includes tetrabutyl titanate; Preferably, the cerium source in step (1) comprises cerium nitrate; Preferably, the complexing agent in step (1) comprises citric acid; Preferably, the molar ratio of the titanium source, the cerium source and the complexing agent in step (1) is (1-3):(1-3):(1-1.2).

3. The preparation method according to claim 1 or 2, characterized in that: The evaporation temperature in step (1) is 60-90°C; Preferably, the evaporation device in step (1) comprises a constant temperature water bath; Preferably, after the evaporation in step (1), a mixed gel is obtained; Preferably, the drying temperature in step (1) is 100-140°C; Preferably, the drying time in step (1) is 8-16 hours.

4. The preparation method according to any one of claims 1 to 3, characterized in that The sintering in step (1) includes a first-stage sintering, a second-stage sintering and a third-stage sintering performed in sequence; Preferably, the temperature of the first stage sintering is 180-200°C; Preferably, the sintering time is 1-2 hours; Preferably, the temperature of the second stage sintering is 300-400°C; Preferably, the second stage sintering time is 1-2h; Preferably, the temperature of the three-stage sintering is 500-1200°C; Preferably, the three-stage sintering time is 3.5-4.5 hours.

5. The preparation method according to any one of claims 1 to 4, characterized in that: Based on the total mass of the cerium titanium support and the palladium source being 100%, the content of the palladium source in step (2) is 1.9-3.1%; Preferably, the palladium source in step (2) comprises palladium nitrate; Preferably, the impregnation and mixing method in step (2) includes stirring.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The drying temperature in step (2) is 80-120°C; Preferably, the drying time in step (2) is 8-16 hours; Preferably, the calcination temperature in step (2) is 525-575°C; Preferably, the calcination time in step (2) is 2.5-3.5 hours.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The preparation method of the palladium-based methane combustion catalyst comprises the following steps: (1) mixing a titanium source, a cerium source and a complexing agent to obtain a mixed sol, evaporating the mixed sol in a constant temperature water bath to obtain a mixed gel; drying the mixed gel at 100-140° C. for 8-16 hours, firstly keeping the mixed gel at 180-200° C. for 1-2 hours, then keeping the mixed gel at 300-400° C. for 1-2 hours, and finally keeping the mixed gel at 500-1200° C. for 3.5-4.5 hours, and then completing three-stage sintering to obtain the cerium titanium carrier; (2) After impregnating the mixed cerium titanium carrier and the palladium source, the mixture is first dried at 80-120° C. for 8-16 hours, and then calcined at 525-575° C. for 2.5-3.5 hours to obtain the palladium-based methane combustion catalyst.

8. A palladium-based methane combustion catalyst, characterized in that: The catalyst is prepared according to the preparation method according to any one of claims 1-7.

9. The catalyst according to claim 8, characterized in that The catalyst carrier includes a cerium-titanium carrier, and the active component of the catalyst includes a palladium oxide compound; Preferably, the cerium-titanium support comprises a cerium-titanium composite oxide; Preferably, the loading amount of the palladium element is 0.75-1.25 wt %.

10. Use of the catalyst as claimed in claim 8 or 9, characterized in that: The catalyst is used for methane combustion catalysis; Preferably, the catalyst is used for treating methane in tail gas.

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