Palladium-based methane combustion catalyst, its preparation method and application

Abstract

The present application relates to a kind of palladium-based methane combustion catalyst and its preparation method and application, the preparation method includes the following steps: after obtaining mixed sol by mixing titanium source, cerium source and complexing agent, evaporate, dry and sinter in sequence, obtain cerium titanium carrier;The palladium-based methane combustion catalyst is obtained by impregnating mixed cerium titanium carrier and palladium source, and then drying and calcining in sequence.The preparation method of the present application is simple, and raw materials are cheap and easy to obtain.The palladium-based methane combustion catalyst prepared has low light-off temperature, and has water resistance, which can be applied to the treatment of methane in tail gas.

Description

A palladium-based methane combustion catalyst, its preparation method and application Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a palladium-based methane combustion catalyst, its preparation method, and its application. Background Technology

[0002] Global warming is accelerating, the climate system is becoming increasingly unstable, and extreme weather and climate events are becoming more frequent, intense, and widespread. Climate change has become a major challenge to human survival and development in the 21st century. CH4 is the second largest greenhouse gas globally, after carbon dioxide, accounting for 16% of total global greenhouse gas emissions. Compared to carbon dioxide, CH4 exists in the atmosphere for a shorter period but has a stronger capacity to absorb heat. On a centennial timescale, the global warming potential of methane is 27.9 times that of carbon dioxide, and on a 20-year timescale, it is 81.2 times, with methane existing in the atmosphere for approximately 12 years. Since the Industrial Revolution, CH4 emissions have contributed approximately 20% to the global greenhouse effect. Effectively controlling CH4 emissions offers climate benefits by mitigating global warming, economic benefits by utilizing energy resources effectively, safety benefits by reducing production accidents, and environmental benefits by synergistically controlling pollutants. Therefore, methane emission reduction has received widespread attention from the international community.

[0003] Natural gas is primarily composed of CH4, with significantly lower sulfur and nitrogen (S) content compared to other primary energy sources (oil and coal). It also has a low hydrocarbon ratio, high calorific value, and produces less secondary pollution, making it considered a fossil fuel with a relatively low environmental impact in the carbon-neutral era. Compared to gasoline, natural gas has abundant reserves, low cost, and is easily mixed with air. Under high-load conditions, it emits significantly less NOx. x Natural gas (N2), CO, CH4, and PM2.5 are low, and their complete combustion primarily produces CO2 and H2O, which is beneficial to environmental protection. Therefore, they are widely used in internal combustion engine power generation and natural gas vehicles (NGVs). However, unburned CH4 in the exhaust can harm the environment. Furthermore, the CH4 emission limit for heavy-duty vehicles is 0.5 g / km, which is relatively low. Therefore, developing a catalyst for the combustion of methane to remove CH4 from the exhaust of natural gas vehicle engines has become an urgent problem to be solved. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a palladium-based methane combustion catalyst, its preparation method, and its application. A cerium-titanium support is prepared via a gelation method and sintering treatment, followed by an impregnation method and calcination treatment to obtain the palladium-based methane combustion catalyst. The preparation method is simple to operate, and the raw materials are inexpensive and readily available. The prepared palladium-based methane combustion catalyst has a low ignition temperature and water resistance, and maintains excellent activity when applied to methane treatment in exhaust gas.

[0005] To achieve this objective, the present invention adopts the following technical solution:

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

[0007] (1) After mixing titanium source, cerium source and complexing agent to obtain mixed sol, the mixture is evaporated, dried and sintered in sequence to obtain cerium titanium carrier;

[0008] (2) The cerium-titanium support and palladium source are impregnated and mixed, and then dried and calcined in sequence to obtain the palladium-based methane combustion catalyst.

[0009] This invention prepares a cerium-titanium support by gelation and sintering, and then prepares the palladium-based methane combustion catalyst by impregnation and calcination. The preparation method is simple to operate and the raw materials are inexpensive and readily available. The prepared palladium-based methane combustion catalyst has a low ignition temperature and certain water resistance properties, and maintains excellent activity when applied to methane treatment in exhaust gas.

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

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

[0012] Preferably, the complexing agent in step (1) includes 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. Other unlisted values ​​within the range are also applicable.

[0014] This invention selects citric acid as a complexing agent because citric acid is a tribasic weak acid that can undergo multi-stage ionization. Metal ions in the solution will coordinate with the carboxylate ions in citric acid, thereby forming a three-dimensional network structure. Furthermore, it can promote the dispersion of various components in the raw materials, achieving molecular or even atomic-level uniformity.

[0015] There is an optimal range for the amount of complexing agent. When the amount of complexing agent is too large, it will affect the catalytic performance of the catalyst; when the amount of complexing agent is too 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, it can be 60°C, 70°C, 80°C, 85°C or 90°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

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

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

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

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

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

[0022] Preferably, the sintering temperature of the first stage is 180-200℃, for example, it can be 180℃, 185℃, 190℃, 195℃ or 200℃, but is not limited to the listed values. Other unlisted values ​​within the 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 not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the temperature of the two-stage sintering is 300-400℃, for example, it can be 300℃, 320℃, 350℃, 380℃ or 400℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the sintering time for the two stages is 1-2 hours, for example, it can be 1 hour, 1.2 hours, 1.5 hours, 1.8 hours or 2 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

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

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

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

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

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

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

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

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

[0034] Preferably, the roasting temperature in step (2) is 525-575℃, for example, it can be 525℃, 535℃, 550℃, 565℃ or 575℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the roasting time in step (2) is 2.5-3.5h, for example, it can be 2.5h, 2.8h, 3h, 3.2h or 3.5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

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

[0037] (1) After mixing titanium source, cerium source and complexing agent to obtain mixed sol, evaporate in constant temperature water bath to obtain mixed gel; dry mixed gel at 100-140℃ for 8-16h, first keep at 180-200℃ for 1-2h, then keep at 300-400℃ for 1-2h, and finally keep at 500-1200℃ for 3.5-4.5h to complete three-stage sintering to obtain the cerium-titanium carrier;

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

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

[0040] Preferably, the catalyst support 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 palladium loading is 0.75-1.25 wt%, for example, it can be 0.75 wt%, 0.9 wt%, 1.05 wt%, 1.1 wt% or 1.25 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Thirdly, the present invention provides an application of the catalyst described in the second aspect, wherein the catalyst is used in the catalysis of methane combustion.

[0044] Preferably, the catalyst is used for methane treatment in exhaust gas.

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

[0046] (1) This invention provides a palladium-based methane combustion catalyst, its preparation method and application. A cerium-titanium support is prepared by gelation and sintering, and then the palladium-based methane combustion catalyst is prepared by impregnation and calcination. The preparation method is simple to operate and the raw materials are inexpensive and easy to obtain.

[0047] (2) The palladium-based methane combustion catalyst prepared by the present invention has a low ignition temperature and certain water resistance. When applied to the treatment of methane in tail gas, it also maintains excellent activity. Attached Figure Description

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

[0049] Figure 2 shows the conversion rate of CH4 by the palladium-based methane combustion catalysts prepared in Examples 1 and 4-10 of this invention under aqueous conditions. Detailed Implementation

[0050] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely 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 is determined by the claims.

[0051] Example 1

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

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

[0054] (2) The mixed gel was dried at 120℃ for 12h to obtain mixed powder. The mixed powder was sintered sequentially at 200℃ for 2h, at 400℃ for 2h, and at 1000℃ for 4h to obtain cerium-titanium carrier.

[0055] (3) Weigh out the cerium titanium support and palladium nitrate, so that the loading of the precious metal palladium element is 1wt%, add deionized water and impregnate and stir to mix, remove excess water by rotary evaporation, dry at 100℃ for 12h, and then calcine at 550℃ for 3h 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 method comprising the following steps:

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

[0059] (2) The mixed gel was dried at 100℃ for 16h to obtain mixed powder. The mixed powder was sintered sequentially at 180℃ for 2h, at 300℃ for 2h, and at 1200℃ for 3.5h to obtain cerium-titanium carrier.

[0060] (3) Weigh out the cerium titanium support and palladium nitrate, so that the loading of the noble metal palladium element is 0.75wt%. Add deionized water to each and impregnate and stir to mix. After removing the excess water by rotary evaporation, dry at 80℃ for 16h and then calcine at 525℃ for 3.5h 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 method comprising the following steps:

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

[0064] (2) The mixed gel was dried at 140℃ for 8 hours to obtain mixed powder. The mixed powder was then sintered sequentially at 220℃ for 1 hour, at 400℃ for 1 hour, and at 500℃ for 4.5 hours to obtain cerium-titanium carrier.

[0065] (3) Weigh out the cerium titanium support and palladium nitrate, so that the loading of the noble metal palladium element is 1.25wt%. Add deionized water and impregnate and stir to mix. After removing the excess water by rotary evaporation, dry at 120℃ for 8h and then calcine at 575℃ for 2.5h to obtain the palladium-based methane combustion catalyst.

[0066] Example 4

[0067] The only difference between this embodiment and embodiment 1 is that, except that the sintering temperature of the three stages in step (2) is 500°C, everything else is the same as in embodiment 1.

[0068] Example 5

[0069] The only difference between this embodiment and embodiment 1 is that, except that the sintering temperature of the three stages in step (2) is 600°C, everything else is the same as in embodiment 1.

[0070] Example 6

[0071] The only difference between this embodiment and embodiment 1 is that, except that the sintering temperature of the three stages in step (2) is 700°C, everything else is the same as in embodiment 1.

[0072] Example 7

[0073] The only difference between this embodiment and embodiment 1 is that, except that the sintering temperature of the three stages in step (2) is 800°C, everything else is the same as in embodiment 1.

[0074] Example 8

[0075] The only difference between this embodiment and embodiment 1 is that, except that the sintering temperature of the three stages in step (2) is 900°C, everything else is the same as in embodiment 1.

[0076] Example 9

[0077] The only difference between this embodiment and embodiment 1 is that, except that the sintering temperature of the three stages in step (2) is 1100℃, everything else is the same as in embodiment 1.

[0078] Example 10

[0079] The only difference between this embodiment and embodiment 1 is that, except that the sintering temperature of the three stages in step (2) is 1200℃, everything else is the same as in embodiment 1.

[0080] Figure 1 shows the conversion rate of CH4 by the palladium-based methane combustion catalysts prepared in Examples 1 and 4-10 of this invention. As can be seen from the figure, the prepared catalysts have the highest conversion efficiency for methane at 1000℃.

[0081] Figure 2 shows the conversion rate of CH4 by the palladium-based methane combustion catalysts prepared in Examples 1 and 4-10 of this invention under aqueous conditions. As can be seen from the figure, the prepared catalysts have the highest conversion efficiency for methane at 1000℃ under the influence of water vapor.

[0082] Example 11

[0083] The only difference between this embodiment and Example 1 is that, except for step (1) where 3 parts of cerium nitrate solution are added as solute, everything else is the same as in Example 1.

[0084] Example 12

[0085] The only difference between this embodiment and Example 1 is that, except for the addition of 3 parts of tetrabutyl titanate in step (1), everything else is the same as in Example 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 with ethanol, everything else is the same as in Embodiment 1.

[0088] Comparative Example 1

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

[0090] (1) Mix 1 part of cerium nitrate and ethanol to obtain solution A; weigh 1 part of tetrabutyl titanate and 1 part of glacial acetic acid to obtain solution B; at room temperature, add solution A dropwise to solution B, stir for 1 hour, and then transfer the mixed solution to a polytetrafluoroethylene liner.

[0091] (2) Add the polytetrafluoroethylene liner into the drying oven, heat it at 3℃ / min, and hydrothermally react it at 160℃ for 12h. When it drops to room temperature, centrifuge, dry and grind it, keep it at 1000℃ for 4h, and cool it with the oven.

[0092] (3) Using cerium-titanium composite oxide as a carrier, 1wt% of the noble metal palladium element is loaded. The cerium-titanium carrier and palladium nitrate are weighed, and deionized water is added to them respectively and impregnated and stirred. After removing the excess water by rotary evaporation, the mixture is first dried at 100℃ for 12h, and then calcined at 550℃ for 3h 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 method comprising the following steps:

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

[0096] (2) The mixed gel was dried at 120℃ for 12h to obtain mixed powder. The mixed powder was sintered sequentially at 200℃ for 2h, at 400℃ for 2h, and at 1000℃ for 4h to obtain cerium-titanium carrier.

[0097] (3) Using cerium-titanium composite oxide as a carrier, 1wt% of the noble metal palladium element is loaded. The cerium-titanium carrier and palladium nitrate are weighed, and deionized water is added to them respectively and impregnated and stirred. After removing the excess water by rotary evaporation, the mixture is first dried at 100℃ for 12h, and then calcined at 550℃ for 3h to obtain the palladium-based methane combustion catalyst.

[0098] Test methods

[0099] The samples obtained in Examples 1-13 and Comparative Examples 1-2 were tableted, ground, and sieved. 40-60 mesh particles were used to investigate the methane catalytic combustion activity in a fixed-bed reactor. The test conditions were: [CH4] = 0.1%, [O2] = 3.5%, N2 balance, total gas flow rate 300 mL / min, space velocity 18,000 g / (mL·h), and reaction temperature 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 obtained in Examples 1-13 and Comparative Examples 1-2 were tableted, ground, and sieved. 40-60 mesh particles were used to investigate the methane catalytic combustion activity in a fixed-bed reactor. The test conditions were: [CH4] = 0.1%, [O2] = 3.5%, [H2O] = 10%, N2 balance, total gas flow rate 300 mL / min, space velocity 18,000 g / (mL·h), and reaction temperature 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) As can be seen from Examples 1-13 and Comparative Examples 1-2, the cerium-titanium support was prepared by gelation and sintering, and the palladium-based methane combustion catalyst was prepared by impregnation and calcination. 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. When applied to the treatment of methane in tail gas, it also maintains excellent activity.

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

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

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

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

[0110] In summary, this invention prepares a cerium-titanium support through a gelation method and sintering treatment, and then prepares the palladium-based methane combustion catalyst through an impregnation method and calcination treatment. The preparation method is simple to operate and the raw materials are inexpensive and readily available. The prepared palladium-based methane combustion catalyst has a low ignition temperature and certain water resistance properties, and maintains excellent activity when applied to methane treatment in exhaust gas.

[0111] The applicant declares that the above description is only a specific embodiment 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 conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection 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 includes the following steps: (1) After mixing titanium source, cerium source and complexing agent to obtain mixed sol, it is evaporated, dried and sintered in sequence to obtain cerium-titanium support; the molar ratio of titanium source, cerium source and complexing agent is (1-3):(1-3):(1-1.2); the sintering includes first-stage sintering, second-stage sintering and third-stage sintering in sequence; the temperature of the first-stage sintering is 180-200℃; the time of the first-stage sintering is 1-2h; the temperature of the second-stage sintering is 300-400℃; the time of the second-stage sintering is 1-2h; the temperature of the third-stage sintering is 500-1200℃; the time of the third-stage sintering is 3.5-4.5h; (2) Impregnate the cerium-titanium support and palladium source, and dry and calcine in sequence to obtain palladium-based methane combustion catalyst.

2. The preparation method according to claim 1, characterized in that, The titanium source mentioned in step (1) includes tetrabutyl titanate.

3. The preparation method according to claim 1, characterized in that, The cerium source mentioned in step (1) includes cerium nitrate.

4. The preparation method according to claim 1, characterized in that, The complexing agent mentioned in step (1) includes citric acid.

5. The preparation method according to claim 1, characterized in that, The evaporation temperature in step (1) is 60-90℃.

6. The preparation method according to claim 1, characterized in that, The evaporation apparatus includes a constant temperature water bath.

7. The preparation method according to claim 1, characterized in that, After evaporation as described in step (1), a mixed gel is obtained.

8. The preparation method according to claim 1, characterized in that, The drying temperature in step (1) is 100-140℃.

9. The preparation method according to claim 1, characterized in that, The drying time in step (1) is 8-16 hours.

10. The preparation method according to claim 1, characterized in that, With 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%.

11. The preparation method according to claim 1, characterized in that, The palladium source mentioned in step (2) includes palladium nitrate.

12. The preparation method according to claim 1, characterized in that, The impregnation and mixing method described in step (2) includes stirring.

13. The preparation method according to claim 1, characterized in that, The drying temperature in step (2) is 80-120℃.

14. The preparation method according to claim 1, characterized in that, The drying time in step (2) is 8-16 hours.

15. The preparation method according to claim 1, characterized in that, The roasting temperature in step (2) is 525-575℃.

16. The preparation method according to claim 1, characterized in that, The roasting time in step (2) is 2.5-3.5h.

17. The preparation method according to claim 1, characterized in that, The preparation method of the palladium-based methane combustion catalyst includes the following steps: (1) After mixing titanium source, cerium source and complexing agent to obtain mixed sol, evaporate in constant temperature water bath to obtain mixed gel; after drying the mixed gel at 100-140℃ for 8-16h, first keep it at 180-200℃ for 1-2h, then keep it at 300-400℃ for 1-2h, and finally keep it at 500-1200℃ for 3.5-4.5h to complete the three-stage sintering and obtain the cerium-titanium support; (2) After impregnating the mixed cerium-titanium support and palladium source, first dry at 80-120℃ for 8-16h, then calcine at 525-575℃ for 2.5-3.5h to obtain the palladium-based methane combustion catalyst.

18. A catalyst for the combustion of palladium-based methane, characterized in that, The catalyst is prepared by the preparation method according to any one of claims 1-17.

19. The catalyst according to claim 18, characterized in that, The catalyst support includes a cerium-titanium support, and the active component of the catalyst includes a palladium oxide compound.

20. The catalyst according to claim 19, characterized in that, The cerium-titanium carrier comprises cerium-titanium composite oxide.

21. The catalyst according to claim 19, characterized in that, The palladium loading is 0.75-1.25 wt%.

22. The application of the catalyst as described in any one of claims 18-21, characterized in that, The catalyst is used for methane combustion catalysis.

23. The application according to claim 22, characterized in that, The catalyst is used for methane treatment in exhaust gas.

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