Catalyst with composite support and method for its preparation

Abstract

The application discloses a catalyst with a composite carrier and a preparation method thereof. The catalyst comprises a composite carrier and an active component loaded on the composite carrier; the composite carrier comprises carrier A and carrier B; the carrier A is graphene-coated nanodiamond; the carrier B is at least one of inorganic oxide, diatomite and molecular sieve; and the active component is palladium element. The catalyst prepared by the composite carrier has high catalytic activity. When the catalyst prepared by the application is used in hydrogenation reaction, the conversion rate and selectivity of selective hydrogenation of acetylene to ethylene are improved.

Description

Technical Field

[0001] This invention relates to the technical field of selective hydrogenation catalysts, and more specifically, to catalysts with composite supports and methods for their preparation. Background Technology

[0002] Ethylene is one of the most important basic raw materials in the petrochemical industry, produced by cracking gaseous or liquid hydrocarbons. Ethylene produced by cracking contains trace amounts of alkynes, which are detrimental to subsequent reactions such as polymerization. For example, in the production of polyethylene, the presence of alkynes not only degrades polymer properties but can also pose an explosion hazard. Therefore, selective catalytic hydrogenation is typically used in ethylene production processes to remove alkyne concentrations to very low levels (mole fraction < 1 × 10⁻⁶). -6 This allows for the production of acetylene selective hydrogenation catalysts to meet the requirements of polymerization raw materials, while also increasing ethylene production and improving resource utilization. With advancements in production processes and the increasing demands on raw material purity in subsequent processes, the petrochemical industry is placing ever higher demands on the performance of these catalysts.

[0003] Selective hydrogenation catalysts for acetylene are mostly supported metal catalysts, generally composed of a support, a main active component, and a co-active component. Commonly used supports include alumina, silica, molecular sieves, activated carbon, magnesium oxide, titanium oxide, diatomaceous earth, etc. The main active component is a metal element with hydrogenation catalytic activity, usually a group VIII element, such as Pd, Pt, Ni, etc., with Pd being the most commonly used selective hydrogenation active component. Although the catalysts currently used in industry can meet the conversion requirements of polymerization, their selectivity still needs to be improved.

[0004] Therefore, there is a need to develop a catalyst with better performance and greater industrial applicability. Summary of the Invention

[0005] To address the problems in existing technologies, this invention proposes a catalyst with a composite support and its preparation method. The catalyst prepared by this invention using a composite support exhibits high catalytic activity. When used in hydrogenation reactions, the conversion rate and selectivity of acetylene selective hydrogenation to ethylene are both improved.

[0006] One objective of this invention is to provide a catalyst having a composite support, the catalyst comprising a composite support and an active component supported on the composite support;

[0007] The composite carrier includes carrier A and carrier B, wherein carrier A is graphene-coated nanodiamond.

[0008] The carrier B is at least one of inorganic oxides, diatomaceous earth, and molecular sieves;

[0009] The active component is palladium.

[0010] In the catalyst with a composite support described in this invention, preferably,

[0011] Based on the weight of carrier A and carrier B as 100%, the proportion of carrier A is 5-40 wt%.

[0012] Preferably, the specific surface area of ​​the composite carrier is 1-400 m². 2 / g.

[0013] In this invention, carrier B uses irregularly shaped carriers such as spheres, sheets, toothed spheres, strips, clover leaves, or four-leaf clovers.

[0014] In the catalyst with a composite support described in this invention, preferably,

[0015] The inorganic oxide is selected from at least one of Al2O3, SiO2, TiO2, and MgO.

[0016] In the catalyst with a composite support described in this invention, preferably,

[0017] The composite carrier further includes an adhesive, preferably selected from at least one of carboxymethyl cellulose, polyvinyl alcohol, and starch; and / or,

[0018] The adhesive content is 1-30 wt%, based on the total weight of carrier A and carrier B as 100%.

[0019] In the catalyst with a composite support described in this invention, preferably,

[0020] Based on the weight of the composite carrier as 100%,

[0021] The active component palladium is 0.01–1 wt% of the composite carrier weight, preferably 0.01–0.2 wt%, more preferably 0.01–0.1 wt%; and / or,

[0022] In the catalyst, the active component palladium has a particle size range of 0.1–3 nm, preferably 0.2–1 nm.

[0023] In the catalyst with a composite support described in this invention, preferably, the method for preparing the graphene-coated nanodiamond includes the following steps:

[0024] The nanodiamonds prepared by detonation were calcined under a protective atmosphere to obtain the graphene-coated nanodiamonds.

[0025] Preferably, the nanodiamond is placed in a tube furnace and calcined under a protective atmosphere to obtain the graphene-coated nanodiamond.

[0026] In the catalyst with a composite support described in this invention, the nanodiamond obtained by detonation can be prepared using existing conventional methods or by purchasing existing materials. Preferably,

[0027] The graphene-coated nanodiamond has a core-shell structure with graphene as the shell and nanodiamond as the core; in the core-shell structure, the number of graphene shell layers is 1-3.

[0028] In the catalyst with a composite support described in this invention, preferably,

[0029] The nanodiamond has a particle size of 10–200 nm; and / or,

[0030] The calcination temperature is 900–1500 °C; and / or,

[0031] The roasting time is 3 to 6 hours;

[0032] Preferably,

[0033] The calcination temperature is 900–1200°C; and / or,

[0034] The roasting time is 3 to 6 hours.

[0035] A second objective of this invention is to provide a method for preparing the catalyst with a composite support as described in one objective of this invention, wherein palladium is loaded onto the composite support to obtain the catalyst;

[0036] Preferably, the catalyst is prepared by loading a palladium-containing precursor compound solution onto the composite support via impregnation or deposition precipitation, followed by post-treatment.

[0037] In the preparation method of this invention, the active component precursor can be loaded onto the support using the impregnation method employed in catalyst preparation, such as equal-volume impregnation or supersaturated impregnation. When using the supersaturated impregnation method, if the active component precursor in the impregnation solution cannot be completely adsorbed by the support, the volume of the impregnation solution and the concentration of the active component should be determined according to the adsorption ratio to ensure that the content of the active component loaded onto the support meets the predetermined requirements.

[0038] The selective hydrogenation catalyst described in this invention can be analyzed using X-ray photoelectron spectroscopy (XPS) to confirm the chemical valence state of the active component of the catalyst; the particle size and particle size distribution of the active component can be observed using transmission electron microscopy (TEM); and the distribution of the active component on the surface and cross-section of the support can be observed using scanning electron microscopy (SEM).

[0039] In the preparation method of the catalyst with a composite support according to the present invention, preferably,

[0040] In the palladium-containing precursor compound solution, the palladium-containing precursor compound is selected from palladium salts; and / or,

[0041] The amount of palladium added to the palladium-containing precursor compound solution is 0.01 to 1 wt% of the weight of the composite carrier, preferably 0.01 to 0.2 wt%, and more preferably 0.01 to 0.1 wt%.

[0042] Preferably, the palladium salt is selected from at least one of inorganic palladium salts and organic palladium salts; and / or,

[0043] The amount of palladium added to the palladium-containing precursor compound solution is 0.01 to 0.1 wt% of the weight of the composite carrier;

[0044] More preferably,

[0045] The inorganic palladium salt is selected from at least one of palladium chloride, palladium nitrate, and palladium sulfate; and / or,

[0046] The organic palladium salt is selected from at least one of palladium acetate and palladium acetylacetonate; and / or,

[0047] In the palladium-containing precursor compound solution, the concentration of palladium is 0.01-200 mg / mL.

[0048] In the preparation method of the catalyst with a composite support according to the present invention, preferably,

[0049] The solvent in the palladium-containing precursor compound solution is selected from at least one of inorganic solvents and organic solvents; and / or,

[0050] The post-processing includes washing and drying.

[0051] Preferably,

[0052] The inorganic solvent is selected from at least one of water, hydrochloric acid, and nitric acid; and / or,

[0053] The organic solvent is selected from at least one of acetic acid and ethanol; and / or,

[0054] The drying temperature in the post-treatment is 50–200°C; and / or,

[0055] The drying time in the post-treatment is 5 to 48 hours;

[0056] More preferably,

[0057] When the inorganic solvent is an aqueous solution of hydrochloric acid, the molar concentration of the aqueous solution is 0.001-0.1 mol / L; and / or,

[0058] When the inorganic solvent is an aqueous solution of nitric acid, the molar concentration of the aqueous solution of nitric acid is 0.001-0.1 mol / L; and / or,

[0059] The drying temperature in the post-treatment is 80–120°C; and / or,

[0060] The drying time in the post-treatment is 5 to 24 hours.

[0061] In the preparation method of the catalyst with a composite support according to the present invention, preferably,

[0062] The composite carrier is prepared by mixing carrier A, carrier B and adhesive, and then molding to obtain the composite carrier.

[0063] Preferably, the adhesive is selected from at least one of carboxymethyl cellulose, polyvinyl alcohol, and starch; and / or,

[0064] The adhesive content is 1-30 wt%, based on the total weight of carrier A and carrier B as 100%.

[0065] In this invention, the composite carrier is formed using existing conventional molding processes, such as compression molding, extrusion molding, spray drying molding, oil molding, jet granulation molding, cooling granulation molding, and fibrous carrier molding. Molding conditions can be selected from commonly used molding parameters.

[0066] In the preparation method of the catalyst with a composite support according to the present invention, preferably,

[0067] The deposition and precipitation method includes the following steps: dispersing the composite support in water, adjusting the pH value to 9-10 to obtain a dispersion; then adjusting the pH value of the palladium-containing precursor compound solution to 6-7 and adding it dropwise to the dispersion, heating and stirring, and drying to obtain the catalyst;

[0068] More preferably, a sodium carbonate solution is used to adjust the pH value; the heating and stirring conditions are to keep the mixture at 80-100°C in an oil bath and stir for 1-2 hours.

[0069] In the preparation method of the catalyst with a composite support according to the present invention, preferably,

[0070] The impregnation method includes the following steps: mixing the vacuum-treated composite support with a palladium-containing precursor compound solution, impregnating and stirring, and drying to obtain the catalyst;

[0071] More preferably, the impregnation and stirring temperature is 35-45℃ for 3-5 hours.

[0072] A third objective of this invention is to provide the application of the catalyst described in one objective of this invention or the catalyst prepared by the preparation method of another objective of this invention in the selective hydrogenation of C2 fraction to ethylene.

[0073] In the application described in this invention, the reaction conditions can be conventional in the art, such as temperature, pressure, and space velocity. Preferably,

[0074] The molar fraction of acetylene in the C2 fraction is 0.1–8.0%; the temperature for selective hydrogenation is 20–120 °C.

[0075] The space velocity for selective hydrogenation reactions is 2000–18000 h⁻¹. -1 ;

[0076] Preferably,

[0077] The molar fraction of acetylene in the C2 fraction is 1–5%;

[0078] The temperature for selective hydrogenation reactions is 40–100 °C;

[0079] The space velocity for selective hydrogenation reactions is 4000–12000 h⁻¹. -1 .

[0080] In the application described in this invention, preferably,

[0081] (A) The above-mentioned catalyst is loaded into the reactor;

[0082] (B) Passing a fraction containing C2 into a reactor to carry out a selective hydrogenation reaction of acetylene.

[0083] In this invention, the reactor is a conventional hydrogenation reactor in the art.

[0084] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0085] Compared with the prior art, the present invention has at least the following advantages:

[0086] The catalyst prepared by the present invention through a composite support has high catalytic activity. When the catalyst prepared by the present invention is used in a hydrogenation reaction, the conversion rate and selectivity of selective hydrogenation of acetylene to ethylene are improved.

[0087] The catalyst of this invention still exhibits good catalytic performance at low temperatures, making it suitable for industrial production. Detailed Implementation

[0088] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0089] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0090] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0091] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0092] The nanodiamonds prepared by the detonation method used in this embodiment of the invention were purchased from Beijing Guoruisheng Technology Co., Ltd.

[0093] Preparation Example 1

[0094] Preparation method of graphene-coated nanodiamonds:

[0095] Nanodiamonds prepared by detonation were calcined under nitrogen at a temperature of 1200°C for 5 hours to obtain graphene-coated nanodiamonds. The graphene-coated nanodiamonds prepared by the above method have a core-shell structure with graphene as the shell and nanodiamond as the core; in the core-shell structure, the number of graphene shell layers is 1-3.

[0096] Preparation Example 2

[0097] Preparation method of composite carrier:

[0098] The composite carrier was prepared by mixing carrier A (graphene-coated nanodiamond prepared in Preparation Example 1), carrier B, and binder starch, followed by cooling and granulation. The specific composition of the composite carrier is shown in Tables 1 and 3.

[0099] Example 1

[0100] Measure 200 mL of deionized water into a flask, add 0.1 M Na₂CO₃ solution to adjust the pH to 10, then weigh 4.3 g of the composite carrier and add it to the above solution. Preheat in a 100°C oil bath. Weigh 0.55 g of the composite carrier. 2+ A 0.4 mg / mL Pd(NO3)2 solution was added dropwise to the support after adjusting the pH to neutral with 0.1 M Na2CO3 solution. The mixture was stirred in an oil bath at 100 °C for 2 h. After the reaction, the mixture was cooled to room temperature, filtered, and washed with deionized water until the filtrate was neutral. The resulting catalyst was then dried in an oven at 60 °C for 12 h and labeled as catalyst A. The specific composition is shown in Table 2.

[0101] Examples 2-4

[0102] Following the method of Example 1, except that the carrier mixed with the graphene-coated nanodiamond carrier is different, the prepared catalysts are labeled as catalyst B, catalyst C, and catalyst D, respectively, and their specific compositions are shown in Table 2.

[0103] Table 1

[0104]

[0105]

[0106] Table 2

[0107]

[0108] Example 5

[0109] Place 8.6 g of the composite carrier in a rotary evaporator and evacuate under vacuum for 10 min. Measure 0.22 mL of Pd... 2+ A 0.4 mg / mL Pd(NO3)2 solution was diluted to 100 mL with deionized water. This solution was added dropwise to the support, and the mixture was impregnated and stirred at 40 °C for 5 h. After cooling to room temperature, 50 mL of C2H5OH was added to the solution, and the solvent was removed using a rotary evaporator. The resulting catalyst was dried in a 60 °C oven for 12 h and labeled as catalyst E. Its specific composition is shown in Table 4.

[0110] Examples 6-8

[0111] Following the method of Example 5, except that the carrier mixed with the graphene-coated nanodiamond carrier is different, the prepared catalysts are labeled as catalyst E, catalyst F, and catalyst G, respectively, and their specific compositions are shown in Table 4.

[0112] Table 3

[0113]

[0114] Table 4

[0115]

[0116] Example 9

[0117] It uses the same preparation method as Example 1, the only difference being the addition of 1.11 / mL Pd. 2+ A Pd(NO3)2 solution with a concentration of 0.4 mg / mL was labeled as catalyst K. The palladium content in catalyst K (based on the composite support) was 0.1 wt%, and the palladium particle size ranged from 0.4 to 3.0 nm.

[0118] Comparative Example 1

[0119] A Pd-Ag / Al2O3 catalyst was prepared as a comparative example using the traditional impregnation method. 5 mL of a 10 mg Pd / mL palladium nitrate solution was diluted with water to 70 mL and then impregnated with 100 g of a catalyst with a specific area of ​​30 m² / mL. 2 The catalyst was prepared by placing a spherical Al2O3 support at 120°C and drying it for 8 hours. Then, it was immersed in an aqueous silver nitrate solution (0.047 g of silver nitrate was prepared into 60 mL of silver nitrate solution), dried at 120°C for 8 hours, and calcined at 600°C with air for 4 hours to obtain the Pd-Ag catalyst.

[0120] Comparative Example 2

[0121] The preparation method is basically the same as that of Example 1, except that in Comparative Example 2, the Al2O3 support in Example 1 is replaced with an equal mass of graphene-coated nanodiamond support, denoted as Catalyst I.

[0122] Comparative Example 3

[0123] The preparation method is basically the same as that of Example 1, except that in Comparative Example 2, the graphene-coated nanodiamond support in Example 1 is replaced with an equal mass of Al2O3 support, which is referred to as catalyst II.

[0124] Example 10

[0125] The prepared catalyst was subjected to a simulated microreactor experiment for selective hydrogenation of acetylene under the following reaction conditions:

[0126] 2g of catalyst was packed into a stainless steel tube reactor with an inner diameter of 2mm. After purging with nitrogen, simulated feed gas from an ethylene production unit was introduced into the reactor. The composition (mole fraction) of the feed gas was: C2H2: 0.399%, C2H6: 6.04%, C2H4: 43.98%, H2: 0.597%, with N2 in equilibrium. The experimental space velocity was 7500 h⁻¹. -1 .

[0127] The selective hydrogenation catalytic performance of the above catalysts for acetylene was evaluated. Catalysts in Examples 1-9 and Comparative Examples 2-3 were evaluated directly, while the catalyst in Comparative Example 1 was evaluated after hydrogen reduction. The conversion rates and selectivity of acetylene hydrogenation to ethylene for each catalytic reaction at 80°C are listed in Table 5.

[0128] The conversion and selectivity of acetylene hydrogenation to ethylene are calculated as follows:

[0129]

[0130]

[0131] Table 5 shows the simulation results of the post-hydrogenation process (average value at 80℃).

[0132]

[0133] By comparing Comparative Example 1 with Examples 1-4, it can be seen that the catalyst prepared by the composite support of the present invention has higher selectivity and conversion rate in hydrogenation reaction compared with the commonly used Pd-Ag catalyst. This result fully demonstrates that the catalyst prepared by the composite support of the present invention has better performance.

[0134] Comparing Comparative Example 2 with Example 1, it can be seen that the catalyst prepared by the composite support of the present invention exhibits higher selectivity and conversion rate in the hydrogenation reaction. Comparing Comparative Example 3 with Example 1, it can be seen that the catalyst prepared by the composite support of the present invention exhibits higher selectivity and conversion rate in the hydrogenation reaction. In summary, the above results fully demonstrate that support A and support B of the present invention have a direct synergistic effect, and the catalyst corresponding to the composite support prepared by them has better performance.

[0135] Examples 11-14

[0136] The reaction conditions are basically the same as those in Example 10, except that the reaction temperatures in Example 9 are replaced with 40°C, 70°C, 100°C and 120°C in Examples 11-14. The specific results are shown in Table 6.

[0137] Table 6. Evaluation results of the post-hydrogenation reaction.

[0138]

[0139] Based on the above data, it can be seen that the catalyst of the present invention does not require a high reaction temperature, and has excellent conversion rate and selectivity even at reaction temperatures below 100°C, meeting the actual reaction conditions of the plant.

[0140] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A catalyst with a composite support, characterized in that: The catalyst comprises a composite support and an active component supported on the composite support; The composite carrier includes carrier A and carrier B, wherein carrier A is graphene-coated nanodiamond. The carrier B is at least one of inorganic oxides, diatomaceous earth, and H-ZSM-5 molecular sieve; the inorganic oxide is selected from at least one of Al2O3, SiO2, TiO2, and MgO. The active component is palladium. Based on the weight of the composite carrier (100%), the active component palladium accounts for 0.01~1 wt% of the weight of the composite carrier. Based on the total weight of carrier A and carrier B (100%), carrier A accounts for 5-40 wt%; In the catalyst, the active component palladium has a particle size range of 0.1~3 nm.

2. The catalyst with a composite support according to claim 1, characterized in that: Based on the total weight of carrier A and carrier B being 100%, the proportion of carrier A is 15-35 wt%; and / or, The specific surface area of ​​the composite carrier is 1-400 m². 2 / g.

3. The catalyst with a composite support according to claim 2, characterized in that: The specific surface area of ​​the composite carrier is 280 m². 2 / g-400m 2 / g.

4. The catalyst with a composite support according to claim 1, characterized in that: Based on the weight of the composite carrier as 100%, The active component palladium is 0.01~0.2 wt% of the composite carrier; and / or, In the catalyst, the active component palladium has a particle size range of 0.2~1 nm.

5. The catalyst with a composite support according to claim 4, characterized in that: Based on the weight of the composite carrier as 100%, The active component palladium is 0.01~0.1 wt% of the composite carrier.

6. The catalyst with a composite support according to claim 1, characterized in that, The preparation method of the graphene-coated nanodiamond includes the following steps: The nanodiamonds prepared by detonation were calcined under a protective atmosphere to obtain the graphene-coated nanodiamonds.

7. The catalyst with a composite support according to claim 6, characterized in that: The graphene-coated nanodiamond has a core-shell structure with graphene as the shell and nanodiamond as the core; in the core-shell structure, the number of graphene shell layers is 1-3.

8. The catalyst with a composite support according to claim 6, characterized in that: The nanodiamond has a particle size of 10~200 nm; and / or, The calcination temperature is 900~1500℃; and / or, The roasting time is 3-6 hours.

9. The catalyst with a composite support according to claim 8, characterized in that: The calcination temperature is 900~1200℃; and / or, The roasting time is 3 to 6 hours.

10. The method for preparing the catalyst according to any one of claims 1-9, characterized in that, Includes the following steps: The catalyst is prepared by loading palladium onto a composite support; the catalyst is also prepared by loading a palladium-containing precursor compound solution onto the composite support via impregnation or deposition precipitation, followed by post-treatment.

11. The preparation method according to claim 10, characterized in that: In the palladium-containing precursor compound solution, the palladium-containing precursor compound is selected from palladium salts; and / or, The amount of palladium added to the palladium-containing precursor compound solution is 0.01~0.2 wt% of the weight of the composite carrier.

12. The preparation method according to claim 11, characterized in that: The palladium salt is selected from at least one of inorganic palladium salts and organic palladium salts; and / or, The amount of palladium added to the palladium-containing precursor compound solution is 0.01~0.1 wt% of the weight of the composite carrier.

13. The preparation method according to claim 12, characterized in that: The inorganic palladium salt is selected from at least one of palladium chloride, palladium nitrate, and palladium sulfate; and / or, The organic palladium salt is selected from at least one of palladium acetate and palladium acetylacetonate; and / or, In the palladium-containing precursor compound solution, the concentration of palladium is 0.01-200 mg / mL.

14. The preparation method according to claim 10, characterized in that: The solvent in the palladium-containing precursor compound solution is selected from at least one of inorganic solvents and organic solvents; and / or, The post-processing includes washing and drying.

15. The preparation method according to claim 14, characterized in that: The inorganic solvent is selected from at least one of water, hydrochloric acid, and nitric acid; and / or, The organic solvent is selected from at least one of acetic acid and ethanol; and / or, The drying temperature in the post-treatment is 50~200℃; and / or, The drying time in the post-treatment is 5 to 48 hours.

16. The preparation method according to claim 15, characterized in that: The drying temperature in the post-treatment is 80~120℃; and / or, The drying time in the post-treatment is 5 to 24 hours.

17. The preparation method according to claim 10, characterized in that: The composite carrier is prepared by mixing carrier A, carrier B and adhesive, and then molding the mixture to obtain the composite carrier.

18. The preparation method according to claim 17, characterized in that: The adhesive is selected from at least one of carboxymethyl cellulose, polyvinyl alcohol, and starch; and / or, The content of the adhesive is 1 to 30 wt%, based on the total weight of carrier A and carrier B as 100%.

19. The preparation method according to claim 10, characterized in that: The deposition and precipitation method includes the following steps: dispersing the composite support in water, adjusting the pH value to 9-10 to obtain a dispersion; then adjusting the pH value of the palladium-containing precursor compound solution to 6-7 and adding it dropwise to the dispersion, heating and stirring, and drying to obtain the catalyst.

20. The preparation method according to claim 10, characterized in that: The impregnation method includes the following steps: mixing the vacuum-treated composite support with a palladium-containing precursor compound solution, impregnating and stirring, and drying to obtain the catalyst.

21. The use of the catalyst according to any one of claims 1-9 in the selective hydrogenation of C2 fraction to ethylene.

22. The application according to claim 21, characterized in that: The molar fraction of acetylene in the C2 fraction is 0.1%–8.0%; The temperature for selective hydrogenation is 40~100℃; The space velocity for selective hydrogenation reactions is 2000–18000 h⁻¹. -1 .

23. The application according to claim 22, characterized in that: The molar fraction of acetylene in the C2 fraction is 1-5%; The space velocity for selective hydrogenation reactions is 4000–12000 h⁻¹. -1 .

24. The application according to claim 23, characterized in that: (A) The above-mentioned catalyst is loaded into the reactor; (B) Passing a fraction containing C2 into a reactor to carry out a selective hydrogenation reaction of acetylene.

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