Catalyst support, ethylene vinyl acetate catalyst and its preparation method and application

Abstract

This invention relates to the field of vinyl acetate preparation technology, and provides a catalyst support, an ethylene-based vinyl acetate catalyst, its preparation method, and its application. This invention, by grafting cyano groups onto a silica support and using the modified silica support to prepare an ethylene-based vinyl acetate catalyst, can effectively reduce the ethylene acrylate content in the crude ethylene-based vinyl acetate product, thereby reducing the energy and material consumption in the ethylene-based vinyl acetate production process.

Description

Technical Field

[0001] This invention relates to the field of vinyl acetate preparation technology, and more specifically, to a catalyst support, an ethylene-based vinyl acetate catalyst, its preparation method, and its application. Background Technology

[0002] Vinyl acetate, also known as vinyl acetate, has the molecular formula C4H6O2. It is a colorless, flammable liquid with a sweet, ether-like odor. Vinyl acetate is an important chemical raw material. Through self-polymerization or copolymerization with other monomers, it can produce derivatives such as polyvinyl alcohol (PVA), polyvinyl acetate (PVAc) emulsions, vinyl acetate-ethylene copolymer emulsions (VAE) or copolymer resins (EVA), and vinyl acetate-vinyl chloride copolymers (EVC), which are widely used in adhesives, coatings, fibers, and other fields.

[0003] There are two main production processes for vinyl acetate: the ethylene process and the acetylene process. The ethylene process is dominant due to its superior processability and economic advantages. The crude product of vinyl acetate produced by the ethylene process contains a small amount of vinyl acrylate, which can cause blockage in the first distillation column. Therefore, it is necessary to side-sample 400-500 kg of material per hour from the first distillation column to remove the vinyl acrylate before recirculating it back into the column. This avoids the risk of blockage caused by vinyl acrylate in the first distillation column. However, this measure also significantly increases the energy and material consumption of the unit. Therefore, reducing the amount of vinyl acrylate in the crude product can improve the overall energy efficiency of the unit. Summary of the Invention

[0004] The purpose of this invention is to provide a catalyst support, an ethylene-based vinyl acetate catalyst, its preparation method, and its application, in order to solve the technical problem that a small amount of vinyl acrylate exists in the crude product of ethylene-based vinyl acetate in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a catalyst support, which is a silica support grafted with cyano groups.

[0007] According to some embodiments of the present invention, the cyano group content in the catalyst support is 0.9 to 31.0 g / L.

[0008] According to some embodiments of the present invention, the silica support is spherical silica; preferably, the particle size of the silica support is 3-6 mm.

[0009] According to some embodiments of the present invention, the specific surface area of ​​the silica carrier is 100-250 m². 2 / g.

[0010] According to some embodiments of the present invention, the pore volume of the silica support is 0.6 to 0.9 mL / g.

[0011] In a second aspect, the present invention provides a method for preparing the catalyst support described in the first aspect, comprising:

[0012] The catalyst support is prepared by first acid treatment of the silica support, then reacting it with a silane crosslinking agent in a first reaction, and finally reacting it with acrylonitrile and an initiator in a solvent in a second reaction.

[0013] According to some embodiments of the present invention, the acid treatment includes treatment with a non-oxidizing strong acid solution at 50–80°C for 2–4 hours.

[0014] According to some embodiments of the present invention, the non-oxidizing strong acid solution is a hydrochloric acid solution with a mass concentration of 0.5% to 1.5%.

[0015] According to some embodiments of the present invention, the silane crosslinking agent contains an epoxy group or C=C, preferably, the silane crosslinking agent includes γ-(methacryloyloxy)propyltrimethoxysilane.

[0016] The process for preparing the catalyst support using γ-(methacryloyloxy)propyltrimethoxysilane is shown below:

[0017]

[0018] According to some embodiments of the present invention, the volume ratio of the acid-treated silica carrier to the silane crosslinking agent is 10 to 50:1, for example 30:1.

[0019] According to some embodiments of the present invention, the first reaction is carried out in a first reaction solvent.

[0020] According to some embodiments of the present invention, the volume ratio of the first reaction solvent to the silane crosslinking agent is 10 to 30:1, for example 1:20.

[0021] According to some embodiments of the present invention, the first reaction solvent includes toluene.

[0022] According to some embodiments of the present invention, the reaction temperature of the first reaction is 20-40°C and the reaction time is 8-12 hours.

[0023] According to some embodiments of the present invention, the initiator includes an azo initiator, such as AIBN.

[0024] According to some embodiments of the present invention, the solvent includes DMF.

[0025] According to some embodiments of the present invention, the ratio of the initiator, acrylonitrile and the carrier after the first reaction treatment is 1g:(2-20)g:(100-500)mL, preferably 1g:(2-10)g:(250-500)mL, more preferably 1g:(3-8)g:(300-400)mL, for example 1g:5g:375mL.

[0026] According to some embodiments of the present invention, the volume ratio of the carrier and solvent after the first reaction treatment is (1-5):(1-8), preferably 1:(1-2), for example 1:1, 3:4, 1:2.

[0027] According to some embodiments of the present invention, the reaction conditions for the second reaction include reacting at 60–100°C for 3–8 hours under inert gas conditions.

[0028] Thirdly, the present invention provides a vinyl acetate catalyst for the ethylene process, comprising a catalyst support as described in the first aspect or a catalyst support prepared by the preparation method described in the second aspect, a main catalytic metal, a co-catalytic metal, and potassium acetate.

[0029] According to some embodiments of the present invention, the main catalytic metal is Pd.

[0030] According to some embodiments of the present invention, the co-catalytic metal includes at least one of Au, Sn, and Cu.

[0031] According to some embodiments of the present invention, the cyano content in the catalyst is 0.8 to 30 g / L, preferably 4.1 to 30 g / L.

[0032] According to some embodiments of the present invention, the content of the main catalytic metal in the catalyst is 1.0 to 10.0 g / L, for example, it can be 1.0 g / L, 2.0 g / L, 3.0 g / L, 4.0 g / L, 5.0 g / L, 7.0 g / L, 8.0 g / L, or 10.0 g / L.

[0033] According to some embodiments of the present invention, the content of the co-catalytic metal in the catalyst is 0.1 to 10.0 g / L, for example, it can be 0.1 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 1.0 g / L, 2.0 g / L, 3.0 g / L, 5.0 g / L, 8.0 g / L, or 10.0 g / L.

[0034] According to some embodiments of the present invention, the potassium acetate content in the catalyst is 20-80 g / L.

[0035] Fourthly, the present invention provides a method for preparing the catalyst as described in the third aspect, comprising:

[0036] A mixed metal salt solution containing a main catalytic metal and a co-catalytic metal was prepared, and the catalyst support was impregnated with the mixed metal salt solution to obtain a catalyst precursor. The catalyst precursor was then subjected to alkaline solution treatment, reducing agent treatment, and potassium acetate solution impregnation treatment in sequence to obtain a vinyl acetate catalyst for the ethylene process.

[0037] According to some embodiments of the present invention, the mass ratio of the main catalytic metal to the co-catalytic metal contained in the mixed metal salt solution is 1.0:(0.01 to 10.0), preferably 1.0:(0.05 to 5.0), more preferably 1.0:(0.1 to 2.0), and even more preferably 1.0:(0.2 to 1.0).

[0038] According to some embodiments of the present invention, the alkaline solution treatment includes: mixing the catalyst precursor with a sodium silicate solution and allowing it to stand for 20 to 30 hours, followed by drying; preferably, the drying temperature is 70 to 90°C and the time is 7 to 12 hours.

[0039] According to some embodiments of the present invention, the concentration of the sodium silicate solution is 20-40 g / L.

[0040] According to some embodiments of the present invention, the volume ratio of the sodium silicate solution to the catalyst support is 1:0.8 to 1.2, for example, 1:1.1.

[0041] According to some embodiments of the present invention, the reducing agent treatment includes: adding a catalyst precursor treated with an alkaline solution to a hydrazine hydrate solution to undergo a reduction reaction; preferably, the concentration of the hydrazine hydrate solution is 1.0 to 3.0 wt%, and / or the temperature of the reduction reaction is 25 to 35°C, and the time is 3 to 6 h.

[0042] According to some embodiments of the present invention, the potassium acetate solution impregnation treatment includes impregnating the catalyst precursor treated with a reducing agent with an aqueous potassium acetate solution; preferably, the concentration of the aqueous potassium acetate solution is 20-50 g / L, for example 30 g / L; and / or the potassium acetate treatment further includes drying the potassium acetate-treated catalyst precursor; more preferably, the drying temperature is 70-90°C and the time is 3-6 h.

[0043] Fifthly, the present invention provides the application of the catalyst described in the third aspect or the catalyst prepared by the preparation method described in the fourth aspect in the production of vinyl acetate using the ethylene process.

[0044] The beneficial effects of this invention are at least as follows:

[0045] This invention modifies silica support by grafting cyano groups and uses the modified silica support to prepare a catalyst for vinyl acetate production via the ethylene process. This effectively reduces the content of ethylene acrylate in the crude vinyl acetate product from the ethylene process, thereby reducing energy and material consumption in vinyl acetate production via the ethylene process. Attached Figure Description

[0046] Figure 1 The infrared spectrum of the vinyl acetate catalyst prepared in Example 1 is shown. Detailed Implementation

[0047] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for illustrating this patent and do not limit the scope of protection of this invention in any way.

[0048] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0049] Unless otherwise specified, all solutions in the embodiments and comparative examples are aqueous solutions.

[0050] Example 1

[0051] Catalyst support preparation

[0052] (1) Take 2000 mL of silica spherical carrier with a diameter of 5.5 mm (specific surface area 180 m²). 2 Add 2000 mL of 1.0% hydrochloric acid solution to the catalyst support (with a pore volume of 0.6 mL / g), place in a water bath at 60°C for 3 h, wash with water and dry to obtain catalyst support i;

[0053] (2) Take 1500 mL of catalyst support i and add it to 1000 mL of toluene solution containing 50 mL of γ-(methacryloyloxy)propyltrimethoxysilane. React at 30 °C for 10 h, filter, wash 3 times with acetone, each time using 800 mL of acetone, to obtain catalyst support ii.

[0054] (3) Take 1500 mL of catalyst support ii and add it to 2000 mL of DMF containing 20 g acrylonitrile and 4 g initiator AIBN. Keep the temperature at 75 °C for 5 h under nitrogen atmosphere, filter, wash with DMF 3 times (800 mL each time), wash with water 5 times (1000 mL each time), and dry at 80 °C for 3 h to obtain catalyst support.

[0055] Preparation of vinyl acetate catalysts for the ethylene process

[0056] (1) Take 1200 mL of a solution containing chloropalladic acid and chloroauric acid, wherein the palladium content in the solution is 2.75 g / L and the gold content is 0.60 g / L, and add 1100 mL of the catalyst support prepared in this example to obtain catalyst precursor I;

[0057] (2) 27.5g sodium silicate nonahydrate was prepared into 1000mL aqueous solution and added to catalyst precursor I. The mixture was mixed evenly, allowed to stand for 24h, and then dried at 80℃ for 8h to obtain catalyst precursor II.

[0058] (3) Catalyst precursor II was reduced in 1000 mL of 2.0 wt% hydrazine hydrate solution at 25 °C for 4 h to obtain catalyst precursor III;

[0059] (4) The catalyst precursor III was impregnated with an aqueous solution of potassium acetate to make the potassium acetate content 30 g / L, and dried at 80°C for 4 h to obtain the ethylene process vinyl acetate catalyst.

[0060] The ethylene-based vinyl acetate catalyst prepared in this embodiment was characterized, and the characterization methods and results are as follows:

[0061] The catalyst sample was characterized using infrared chromatograph, and the results are as follows: Figure 1 As shown, the catalyst is displayed in the infrared spectrum from 1655 to 1665 cm⁻¹. -1 It exhibits the characteristic absorption peak of the cyano group.

[0062] The nitrogen content in the catalyst was determined by elemental analysis, and the nitrogen content was converted into the cyano group content. The results are shown in Table 1.

[0063] The contents of Pd, Au, and K in the catalyst were determined by XRF analysis, and the potassium acetate content was calculated based on the K content. The results are shown in Table 1.

[0064] The ethylene-based vinyl acetate catalyst prepared in this embodiment was evaluated using a fixed-bed reactor under the following conditions:

[0065] Catalyst loading volume: 900 mL;

[0066] Composition of reactant gases (in molar ratio): Oxygen: Ethylene: Nitrogen: Acetic acid = 1:6.8:7.2:1.7;

[0067] Gas hourly space velocity of reactants: 2000 h⁻¹ -1 ;

[0068] Reaction pressure: 0.7 MPa;

[0069] Reaction temperature: 140℃;

[0070] Reaction time: 100 hours;

[0071] The content of vinyl acrylate in the reaction product was analyzed by GC-MS.

[0072] Example 2

[0073] The preparation method of the catalyst support is the same as that in Example 1, except that the amount of acrylonitrile in step (3) is adjusted from 20g to 8g.

[0074] The catalyst preparation and evaluation were as described in Example 1, and the resulting analytical and evaluation data are listed in Table 1.

[0075] Example 3

[0076] The preparation method of the catalyst support is the same as that in Example 1, except that the amount of acrylonitrile in step (3) is adjusted from 20g to 80g.

[0077] The catalyst preparation and evaluation were as described in Example 1, and the resulting analytical and evaluation data are listed in Table 1.

[0078] Example 4

[0079] Catalyst support preparation

[0080] (1) Take 2000 mL of silica spherical carrier with a diameter of 5.5 mm (specific surface area 180 m²). 2 Add 2000 mL of 1.0% hydrochloric acid solution to the catalyst support (with a pore volume of 0.6 mL / g), place in a water bath at 60°C for 3 h, wash with water and dry to obtain catalyst support i;

[0081] (2) Take 1500 mL of catalyst support i and add it to 1000 mL of toluene solution containing 50 mL of γ-(methacryloyloxy)propyltrimethoxysilane. React at 30 °C for 10 h, filter, wash 3 times with acetone, each time using 800 mL of acetone, to obtain catalyst support ii.

[0082] (3) Take 1000 mL of catalyst support ii and add it to 2000 mL of DMF containing 40 g acrylonitrile and 4 g initiator AIBN. Keep the temperature at 75 °C for 5 h under nitrogen atmosphere, filter, wash with DMF 3 times (800 mL each time), wash with water 5 times (1000 mL each time), and dry at 80 °C for 3 h to obtain catalyst support.

[0083] The catalyst preparation and evaluation were as described in Example 1, and the resulting analytical and evaluation data are listed in Table 1.

[0084] Example 5

[0085] Catalyst support preparation

[0086] (1) Take 2000 mL of silica spherical carrier with a diameter of 5.5 mm (specific surface area 180 m²). 2 Add 2000 mL of 1.0% hydrochloric acid solution to the catalyst support (with a pore volume of 0.6 mL / g), place in a water bath at 60°C for 3 h, wash with water and dry to obtain catalyst support i;

[0087] (2) Take 1500 mL of catalyst support i and add it to 1000 mL of toluene solution containing 50 mL of γ-(methacryloyloxy)propyltrimethoxysilane. React at 30 °C for 10 h, filter, wash 3 times with acetone, each time using 800 mL of acetone, to obtain catalyst support ii.

[0088] (3) Take 2000 mL of catalyst support ii and add it to 2000 mL of DMF containing 40 g acrylonitrile and 4 g initiator AIBN. Keep the temperature at 75 °C for 5 h under nitrogen atmosphere, filter, wash with DMF 3 times (800 mL each time), wash with water 5 times (1000 mL each time), and dry at 80 °C for 3 h to obtain the catalyst support.

[0089] The catalyst preparation and evaluation were as described in Example 1, and the resulting analytical and evaluation data are listed in Table 1.

[0090] Example 6

[0091] Catalyst support preparation

[0092] (1) Take 2000 mL of silica spherical carrier with a diameter of 5.5 mm (specific surface area 180 m²). 2 Add 2000 mL of 1.0% hydrochloric acid solution to the catalyst support (with a pore volume of 0.6 mL / g), place in a water bath at 60°C for 3 h, wash with water and dry to obtain catalyst support i;

[0093] (2) Take 1500 mL of catalyst support i and add it to 1000 mL of toluene solution containing 50 mL of γ-(methacryloyloxy)propyltrimethoxysilane. React at 20 °C for 8 h, filter, wash 3 times with acetone, each time using 800 mL of acetone, to obtain catalyst support ii.

[0094] (3) Take 1500 mL of catalyst support ii and add it to 2000 mL of DMF containing 8 g acrylonitrile and 4 g initiator AIBN. Keep the temperature at 60 °C for 8 h under nitrogen atmosphere, filter, wash with DMF 3 times (800 mL each time), wash with water 5 times (1000 mL each time), and dry at 80 °C for 3 h to obtain catalyst support.

[0095] The catalyst preparation and evaluation were as described in Example 1, and the resulting analytical and evaluation data are listed in Table 1.

[0096] Example 7

[0097] Catalyst support preparation

[0098] (1) Take 2000 mL of silica spherical carrier with a diameter of 5.5 mm (specific surface area 180 m²). 2 Add 2000 mL of 1.0% hydrochloric acid solution to the catalyst support (with a pore volume of 0.6 mL / g), place in a water bath at 60°C for 3 h, wash with water and dry to obtain catalyst support i;

[0099] (2) Take 1500 mL of catalyst support i and add it to 1000 mL of toluene solution containing 50 mL of γ-(methacryloyloxy)propyltrimethoxysilane. React at 40 °C for 12 h, filter, wash 3 times with acetone, each time using 800 mL of acetone, to obtain catalyst support ii.

[0100] (3) Take 1500 mL of catalyst support ii and add it to 2000 mL of DMF containing 8 g acrylonitrile and 4 g initiator AIBN. Keep the temperature at 100 °C for 3 h under nitrogen atmosphere, filter, wash with DMF 3 times (800 mL each time), wash with water 5 times (1000 mL each time), and dry at 80 °C for 3 h to obtain the catalyst support.

[0101] The catalyst preparation and evaluation were as described in Example 1, and the resulting analytical and evaluation data are listed in Table 1.

[0102] Example 8

[0103] Preparation of vinyl acetate catalysts for the ethylene process

[0104] (1) Take 1200 mL of a solution containing chloropalladic acid and chloroauric acid, wherein the palladium content in the solution is 0.92 g / L and the gold content is 0.51 g / L, and add 1100 mL of the catalyst support prepared in Example 1 to obtain catalyst precursor I;

[0105] (2) 27.5g sodium silicate nonahydrate was prepared into 1000mL aqueous solution and added to catalyst precursor I. The mixture was mixed evenly, allowed to stand for 24h, and then dried at 80℃ for 8h to obtain catalyst precursor II.

[0106] (3) Catalyst precursor II was reduced in 1000 mL of 2.0 wt% hydrazine hydrate solution at 25 °C for 4 h to obtain catalyst precursor III;

[0107] (4) The catalyst precursor III was impregnated with an aqueous solution of potassium acetate to make the potassium acetate content 30 g / L, and dried at 80°C for 4 h to obtain the ethylene process vinyl acetate catalyst.

[0108] Catalyst analysis and activity evaluation were consistent with those described in Example 1, and the data are listed in Table 1.

[0109] Example 9

[0110] Preparation of vinyl acetate catalysts for the ethylene process

[0111] (1) Take 1200 mL of a solution containing chloropalladic acid and chloroauric acid, wherein the palladium content in the solution is 9.2 g / L and the gold content is 10.2 g / L, and add 1100 mL of the catalyst support prepared in Example 1 to obtain catalyst precursor I;

[0112] (2) 27.5g sodium silicate nonahydrate was prepared into 1000mL aqueous solution and added to catalyst precursor I. The mixture was mixed evenly, allowed to stand for 24h, and then dried at 80℃ for 8h to obtain catalyst precursor II.

[0113] (3) Catalyst precursor II was reduced in 1000 mL of 2.0 wt% hydrazine hydrate solution at 25 °C for 4 h to obtain catalyst precursor III;

[0114] (4) The catalyst precursor III was impregnated with an aqueous solution of potassium acetate to make the potassium acetate content 30 g / L, and dried at 80°C for 4 h to obtain the ethylene process vinyl acetate catalyst.

[0115] Catalyst analysis and activity evaluation were consistent with those described in Example 1, and the data are listed in Table 1.

[0116] Comparative Example 1

[0117] Catalyst preparation

[0118] (1) Take 1200 mL of a solution containing chloropalladic acid and chloroauric acid, wherein the palladium content in the solution is 2.75 g / L and the gold content is 0.60 g / L, and add 1100 mL of silica support (diameter 5.5 mm, specific surface area 180 m²) 2 / g, with a pore volume of 0.6mL / g), catalyst precursor I was obtained;

[0119] (2) 27.5g sodium silicate nonahydrate was prepared into 1000mL aqueous solution and added to catalyst precursor I. The mixture was mixed evenly, allowed to stand for 24h, and then dried at 80℃ for 8h to obtain catalyst precursor II.

[0120] (3) Catalyst precursor II was reduced in 1000 mL of 2.0 wt% hydrazine hydrate solution at 25 °C for 4 h to obtain catalyst precursor III;

[0121] (4) The catalyst precursor III was impregnated with potassium acetate aqueous solution to make the potassium acetate content 30g / L, and dried at 80℃ for 4h to obtain the finished catalyst.

[0122] The catalyst prepared in this embodiment was characterized, and the characterization methods and results are as follows:

[0123] Using infrared chromatograph, the catalyst sample did not appear in the 1655–1665 cm⁻¹ region on the infrared chromatogram. -1 The characteristic absorption peak of the cyano group.

[0124] Elemental analysis was used to characterize the nitrogen content in the catalyst, and no nitrogen was detected.

[0125] The contents of Pd, Au, and K in the catalyst were determined by XRF analysis, and the potassium acetate content was calculated based on the K content. The results are shown in Table 1.

[0126] The vinyl acetate catalyst prepared in this embodiment was evaluated using a fixed-bed reactor under the same conditions as in Example 1. The content of vinyl acrylate in the reaction product was analyzed by GC-MS.

[0127] Table 1 Results of vinyl acrylate content determination

[0128]

[0129]

[0130] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A catalyst for vinyl acetate production via the ethylene process, characterized in that, It includes a catalyst support, a main catalytic metal, a co-catalytic metal, and potassium acetate; the catalyst support is a silica support grafted with cyano groups; the cyano group content in the catalyst support is 0.9~31.0 g / L.

2. The catalyst according to claim 1, characterized in that, The method for preparing the catalyst support includes: The catalyst support is prepared by first acid treatment of the silica support, then reacting it with a silane crosslinking agent in a first reaction, and finally reacting it with acrylonitrile and an initiator in a solvent in a second reaction.

3. The catalyst according to claim 2, characterized in that, The acid treatment includes treatment with a non-oxidizing strong acid solution at 50-80°C for 2-4 hours.

4. The catalyst according to claim 3, characterized in that, The non-oxidizing strong acid solution is a hydrochloric acid solution with a mass concentration of 0.5~1.5%.

5. The catalyst according to claim 2, characterized in that, The silane crosslinking agent contains epoxy groups or C=C; And / or, the volume ratio of acid-treated silica support to silane crosslinking agent is 10~50:1; And / or, the reaction temperature of the first reaction is 20~40℃, and the reaction time is 8~12h.

6. The catalyst according to claim 2, characterized in that, The silane crosslinking agent includes γ-(methacryloyloxy)propyltrimethoxysilane.

7. The catalyst according to claim 2, characterized in that, The initiator includes an azo initiator; And / or, the solvent includes DMF; And / or, the ratio of the initiator, acrylonitrile, and the carrier after the first reaction treatment is 1 g : (2~20) g : (100~500) mL; And / or, the volume ratio of the carrier and solvent after the first reaction treatment is (1~5):(1~8); And / or, the reaction conditions for the second reaction include: under inert gas conditions, reacting at 60~100℃ for 3~8h.

8. The catalyst according to claim 7, characterized in that, The initiator is AIBN; And / or, the ratio of the initiator, acrylonitrile, and the carrier after the first reaction treatment is 1 g : (2~10) g : (250~500) mL; And / or, the volume ratio of the carrier and solvent after the first reaction treatment is 1:(1~2).

9. The catalyst according to any one of claims 1-8, characterized in that, The main catalytic metal is Pd; And / or, the co-catalytic metal includes at least one of Au, Sn, and Cu; And / or, the cyano group content in the catalyst is 0.8~30 g / L; And / or, the content of the main catalytic metal in the catalyst is 1.0~10.0 g / L; And / or, the content of the co-catalytic metal in the catalyst is 0.1~10.0 g / L; And / or, the potassium acetate content in the catalyst is 20~80 g / L.

10. The method for preparing the catalyst according to any one of claims 1-9, characterized in that, include: A mixed metal salt solution containing a main catalytic metal and a co-catalytic metal was prepared, and the catalyst support was impregnated with the mixed metal salt solution to obtain a catalyst precursor. The catalyst precursor was then subjected to alkaline solution treatment, reducing agent treatment, and potassium acetate solution impregnation treatment in sequence to obtain a vinyl acetate catalyst for the ethylene process.

11. The method for preparing the catalyst according to claim 10, characterized in that, The mass ratio of the main catalytic metal to the co-catalytic metal in the mixed metal salt solution is 1.0:(0.01~10.0). And / or, the alkaline solution treatment includes: mixing the catalyst precursor with a sodium silicate solution, allowing it to stand for 20-30 hours, and then drying; And / or, the reducing agent treatment includes: adding a catalyst precursor treated with an alkaline solution to a hydrazine hydrate solution to undergo a reduction reaction; And / or, the potassium acetate solution impregnation treatment includes impregnating the catalyst precursor treated with a reducing agent with an aqueous potassium acetate solution.

12. The method for preparing the catalyst according to claim 11, characterized in that, The drying temperature in the alkaline solution treatment is 70~90℃, and the time is 7~12h; And / or, the concentration of the hydrazine hydrate solution is 1.0~3.0 wt%; And / or, the reduction reaction is carried out at a temperature of 25~35℃ for 3~6 hours; And / or, the concentration of the potassium acetate aqueous solution is 20~50 g / L; And / or, the potassium acetate solution impregnation treatment further includes drying the potassium acetate-treated catalyst precursor.

13. The method for preparing the catalyst according to claim 12, characterized in that, The drying temperature for the catalyst precursor treated with potassium acetate is 70-90°C, and the drying time is 3-6 hours.

14. The application of the catalyst according to any one of claims 1-9 or the catalyst prepared by any one of claims 10-13 in the production of vinyl acetate by the ethylene process.

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