Catalyst for preparing vinyl acetate as well as preparation method and application of catalyst

Abstract

The invention relates to a catalyst for preparing vinyl acetate and a preparation method and application thereof, and belongs to the field of chemical engineering, the composition of the catalyst meets the expression: Zn [alpha] Bi [beta] Si [gamma] B [lambda] Al [mu] P [eta] Ox / C100, in the formula, the atomic ratio alpha is 1.4-3.8, the atomic ratio beta is 0.001-0.002, the atomic ratio gamma is 1.8-3.8, the atomic ratio lambda is 0.01-0.02, the atomic ratio mu is 0.9-1.8, the atomic ratio eta is 0.9-1.8, and x is the required total oxygen atom number; the preparation method comprises the following steps: uniformly mixing superfine carbon powder, silicon carbide powder and basic zinc carbonate (contributing 10-40% of total zinc content), and carrying out equivalent-volume impregnation by using a bismuth nitrate and boric acid mixed solution; adding aluminum phosphate sol, kneading and forming; after drying, activating with water vapor containing hydrogen peroxide at 300-700 DEG C; and carrying out saturated impregnation with a zinc acetate solution and drying. The catalyst preparation cost and severity are low, and the process is simplified; the strength, the diffusion and the heat-conducting property are good, and the activity and the stability are good.

Description

Technical Field

[0001] The present invention relates to a catalyst for preparing vinyl acetate, a preparation method and application thereof, and in particular to a catalyst with a carbon-based composite carrier for preparing vinyl acetate by an acetylene process, including a preparation method and application process thereof, and belongs to the field of chemical technology. Background Art

[0002] Vinyl acetate is one of the 50 chemical products with the largest output in the world. As the raw material of vinyl acetate resin and polyvinyl alcohol, and as a comonomer with ethylene, styrene, acrylate, methacrylate, etc., it is widely used in adhesives, paints, coatings, films, laminates, fiber treatment agents and other fields. It is an important industrial material with high economic value.

[0003] In 1922, the German company Wacker pioneered a vapor-phase synthesis method using acetylene as a raw material, which was later refined by the Hochst company and put into industrial production. The catalyst used in this synthesis method, zinc acetate as the active component and activated carbon as the carrier, continues to be used today, as shown in CN1903435A. Although products using ethylene as a raw material are currently of higher quality, and new plants built abroad also primarily use ethylene as a raw material, the acetylene process remains the primary method for producing vinyl acetate in China, with several plants introduced since the 1960s. Consequently, research on the acetylene process for synthesizing vinyl acetate continues in China, with particular attention focused on adjusting the combination of active catalyst components.

[0004] In the domestic acetylene vapor phase process for synthesizing vinyl acetate, both fixed-bed and ebullating-bed processes utilize a zinc acetate / activated carbon catalyst. However, different manufacturers vary in the type of activated carbon carrier, the zinc acetate loading, and, in particular, the co-catalyst. Commonly used activated carbon carriers include coconut shell charcoal, apricot kernel charcoal, hickory charcoal, olive kernel charcoal, and coal-based charcoal. Currently, coconut shell activated carbon is the most common carrier, with only a few manufacturers using coal-based activated carbon as a catalyst carrier in fixed-bed processes.

[0005] The acetylene vapor phase catalyst currently used in China for synthesizing vinyl acetate has many disadvantages, including low activity, low yield per unit volume, poor mechanical strength, easy shedding of active components, short deactivation cycle, and so on.

[0006] To address these issues, the prior art has conducted extensive research on active components, additives, and supports. For example, the earlier patent document CN86107833A employed two zinc active components, zinc nitrate and zinc chloride, supported on a strong activated carbon support. The resulting catalyst, after calcination, improved the space-time yield. CN112517064A also discloses a catalyst with two zinc salt active components. In addition to zinc acetate, a dicarboxylic acid zinc salt was used as the second zinc salt active component, reducing the acetone content in the product.

[0007] Research on additives is also very active. For example, the catalyst and preparation method disclosed in CN1903435A use activated carbon as a carrier, zinc acetate as an active component, and bismuth subcarbonate as a co-catalyst to inhibit the formation of acetylene polymers in the product and reduce the poisoning effect on the catalyst, thereby improving activity and life. In CN102039180A, rare earth element modification is used to improve the single-pass conversion rate of the process.

[0008] Some organic compounds have also been used as additives, such as CN103934024A using aromatic acid esters as additives, CN103934021A using alkyl diethers and / or aromatic diethers as additives, and CN104549496A using crown ethers as additives to achieve the purpose of improving catalyst activity. In addition to improving activity, organic additives are also used to reduce the benzene content in the product to improve product quality. For example, CN104437626A uses fullerenes, CN114177939A uses cucurbiturils, CN115707512A uses acyl chloride organic compounds, and CN115228508A uses p-benzoquinone as additives to modify zinc acetate activated carbon catalysts. CN113620802A, on the other hand, simply reduces the benzene content in the product by controlling the zinc content.

[0009] In the prior art, it is common to add and replace different elements. For example, in the catalyst disclosed in CN103285878A, the carrier is activated carbon, and the loaded active components are impregnated zinc, chromium, iron, calcium, copper, potassium, zirconium, platinum and other elements, and are calcined using furnace gas from a combustion furnace. When the obtained catalyst is used to prepare vinyl acetate, it reduces the starting temperature of the reaction and obtains a good space-time yield. CN101391229A is a fixed-bed catalyst containing rare earth metals, which also reduces the starting temperature of the reaction. CN102039180A also uses cerium and scandium rare earth salts to improve the single-pass conversion rate and service life. CN105944757A uses compounds of Group V non-metallic elements to obtain a doped activated carbon carrier, and the catalyst has good activity and stability.

[0010] The Shanghai Petrochemical Research Institute has disclosed a large number of existing technologies using element modification. Based on the basic structure of an activated carbon carrier and zinc acetate active component, different elements such as platinum group elements and rare earth elements are modified to improve the activity and stability of the catalyst or reduce the benzene content in the product. For example, these technologies are described in numerous patent documents such as CN104549497A, CN105498778A, CN106423(157, 267)A, CN1077722(76, 79)A, CN107778169A, CN1077743(04, 08, 12-14, 19-24, 32, 38)A, CN1077901(81-90)A, CN114054010A, and CN115970754A, which basically cover the periodic table of elements.

[0011] In addition to focusing on element modification research, support modification of zinc acetate activated carbon catalysts has also received attention. For example, CN116870888A makes the mesopore volume of the catalyst support activated carbon larger, with more developed pore channels that allow the synthetic raw materials and product molecules to enter and exit freely, and the catalyst strength and apparent density are higher; CN105457683A uses titanium-modified activated carbon support, zinc acetate active component and potassium acetate additive to improve the catalyst activity and acetylene single-pass conversion rate; CN1 12439453A uses ionic liquid to modify the activated carbon carrier to improve the life and stability of the catalyst; CN102029193A uses hydrogen peroxide to modify the activated carbon carrier to improve the pore size distribution and surface charge distribution; CN102284304A uses oxidants such as hydrogen peroxide, sulfuric acid, potassium permanganate and ammonium persulfate to perform surface oxidation modification on the carrier activated carbon to improve its loading capacity for zinc acetate; CN108636392A improves the activation method to enhance the quality of the catalyst.

[0012] In the disclosed prior art, some physical methods have also been tried for modification. For example, CN103111325A, CN113649082A, and CN103447083A pass an electric current when the activated carbon is dried after impregnation to improve activity and life; CN102671698A uses ultrasonic impregnation technology to evenly disperse the active components and improve activity; CN108144648A uses ultrasonic impregnation and microwave drying technology to improve the activity and life of the catalyst; CN104437627A also uses microwave drying method; CN104549498A uses 60A method of irradiating an activated carbon carrier with Co-γ rays to improve the activity of the catalyst; in CN102218340A, a prepared zinc acetate solution is passed through an impregnation drying tower filled with dry activated carbon for closed impregnation, so that the zinc acetate is impregnated into the pores of the activated carbon as much as possible, and gravity is used to cause excess solution and water to flow out. Indirect heating is performed through thermal oil or hot water to evaporate the water and complete the drying process, thereby reducing the breakage of the activated carbon.

[0013] The prior art has also explored different types of activated carbon. For example, CN102774834A discloses the preparation of bamboo activated carbon to replace the more expensive coconut shell activated carbon, thereby reducing the raw material cost of the catalyst; CN101402052A uses papermaking acid-precipitated lignin as raw material to prepare activated carbon as a carrier for preparing catalysts; CN101385984A uses acrylonitrile-vinylidene chloride copolymer precursor to prepare polymer-derived carbon as a carrier; CN101439302A uses resin-based derived carbon as a catalyst carrier, which has the advantages of good catalytic performance and mechanical strength, regular structure, and easy loading; in CN109382084A and CN103934030A, mesoporous carbon materials are used as carriers for zinc acetate activated carbon catalysts, which give the catalysts good catalytic activity.

[0014] For a long time, experiments to use silica gel, alumina, aluminum silicate and molecular sieves to replace activated carbon carriers have been unsuccessful. The activity of catalysts prepared by using them as carriers is much lower than that of activated carbon-supported catalysts. Activated carbon has always been difficult to be completely replaced as a catalyst carrier for the acetylene method of synthesizing vinyl acetate.

[0015] However, some technologies involving non-activated carbon carriers are also disclosed in the prior art, such as CN103962178A using zinc acetate and copper acetate as active components and silicon carbide or activated carbon as carriers to improve the activity of the catalyst; CN103769218A using only silicon carbide as a catalyst carrier; CN103934025A using carbon-deposited silicon carbide as a carrier to solve the problem of low catalyst activity; CN102600899A using carbon-coated alumina composite material as a carrier and zinc acetate as an active component, with good space-time yield, selectivity and stability; CN106268962A mainly uses carbon-coated alumina composite material as a carrier and zinc acetate as an active component, with good space-time yield, selectivity and stability. The catalyst uses nano-ceramic balls as carriers, zinc acetate as the active component, diatomaceous earth as the co-catalyst, copper chloride and nano-zinc oxide as the active components, and is prepared with the assistance of ultrasound and microwaves. The ratio of the main catalyst to the co-catalyst is 7:3, which improves the active component loading rate and catalytic activity, and the activity decreases slowly; CN109382084A uses zinc-containing mesoporous carbon materials with ordered mesoporous channels, mixes a template, an organic solvent, a carbon source, and a zinc-containing precursor, removes the organic solvent from the colloidal solution, solidifies, and calcines under an inert atmosphere to remove the template and carbonize. The zinc content is controllable, the dispersibility and activity are good, and it is simple and easy to operate. Summary of the Invention

[0016] The present invention aims to provide an improved method for preparing a catalyst for preparing vinyl acetate, as well as a catalyst and application technology. This method addresses issues such as easy zinc loss, limited loading, low activity and stability, side reaction impurities and coking, and poor strength that impact service life. The method utilizes a carbon-based composite carrier with the combined functionality of an inorganic binder to load two types of zinc active components and additives of varying properties, thereby increasing loading and activation efficiency. Furthermore, the method modifies the pore surface physicochemical properties, improving diffusion and thermal conductivity, catalytic performance, and mechanical strength. Furthermore, it reduces side reactions and carbon deposition, and reduces the severity of the preparation process.

[0017] The present invention provides a catalyst for preparing vinyl acetate and a preparation method thereof, comprising:

[0018] The catalyst composition satisfies the chemical formula: Zn α Bi β Si γ B λ Al μ P η O χ / C 100 , wherein the atomic ratio α=1.4-3.8, β=0.001-0.002, γ=1.8-3.8, λ=0.01-0.02, μ=0.9-1.8, η=0.9-1.8, and χ is the number of oxygen atoms required to satisfy the atomic valence of each element; 200-300 mesh carbon powder, silicon carbide powder, and basic zinc carbonate (wherein the zinc element accounts for 10wt%-40wt% of the total zinc content of the catalyst) are uniformly mixed, impregnated with an equal volume of a mixed solution of bismuth nitrate and boric acid, and aluminum phosphate sol is added. The mixture is kneaded for more than 40 minutes and then formed; after drying, water vapor containing 1wt%-5wt% of hydrogen peroxide is introduced at 300-700°C for activation for 1-8 hours; saturated impregnation with a zinc acetate solution is performed, and then drying is performed at 80-100°C for 1-6 hours.

[0019] In the preparation method of a catalyst for preparing vinyl acetate provided by the present invention, the carbon powder is selected from wood carbon powder, bamboo carbon powder, coal-based carbon powder, fruit shell carbon powder, petroleum coke carbon powder, and resin-based carbon powder.

[0020] In the preparation method of a catalyst for preparing vinyl acetate provided by the present invention, the equal-volume impregnation of the mixed solution of bismuth nitrate and boric acid is carried out by acidifying and dissolving the mixed solution of bismuth nitrate and boric acid with nitric acid and impregnating the mixed solution with the powdered composition raw material at equal volumes at 20-100°C.

[0021] In the preparation method of a catalyst for preparing vinyl acetate provided by the present invention, the aluminum phosphate sol is prepared by dissolving a phosphoric acid solution and one or more of aluminum oxide, aluminum hydroxide, boehmite, pseudo-boehmite, aluminum isopropoxide, and aluminum isobutoxide in an equimolar ratio of phosphorus and aluminum at 40-100°C.

[0022] In the method for preparing a catalyst for preparing vinyl acetate provided by the present invention, the catalyst is formed into cylindrical, block, sheet, or strip forms suitable for fixed-bed reactions by hydraulic tableting, extrusion, or pelletizing. Spherical, granular catalysts suitable for ebullient and fluidized-bed reactions are formed by rolling in a catalyst roller. While it is generally believed that the product quality of fixed-bed processes is superior to that of ebullient-bed processes, the labor intensity of fixed-bed processes is higher than that of ebullient-bed processes.

[0023] In the preparation method of a catalyst for preparing vinyl acetate provided by the present invention, the zinc acetate solution saturation impregnation is performed by dissolving the zinc acetate solution in methanol and / or ethanol, placing the carrier composition in the zinc acetate solution with a pH value of 4 to 6 and a concentration of 20 wt% to 35 wt%, and impregnating the solution at 50 to 100° C. for 1 to 10 hours.

[0024] The present invention provides a catalyst for preparing vinyl acetate, which is prepared according to the above preparation method and steps, and is characterized in that the catalyst has an average pore diameter of ≥2nm, a pore volume of 0.4-0.6ml / g, and a surface area of 600-900m 2 / g, bulk density is 0.3~0.6g / ml.

[0025] The present invention also provides a method for preparing vinyl acetate, comprising using acetic acid and acetylene as raw materials, in the presence of the catalyst prepared by the above-mentioned method of the present invention, the molar ratio of acetylene to acetic acid is 1: (5-8), the raw material volume space velocity is 250-350h -1 , reaction temperature 170 ~ 200 ° C, reaction pressure 0.1 ~ 0.14 MPa, and obtain vinyl acetate product through synthesis reaction.

[0026] In the preparation method of a catalyst for preparing vinyl acetate provided by the present invention, the amounts of deionized water and methanol or ethanol solvents used in dilution, salt dissolution, and other processes involved in the preparation process are mainly to meet operational requirements and convenience, and have no effect on the performance of the final finished catalyst. When the convenience of operational implementation is not affected, the minimum amount of water and alcohol solvent is used for dilution and dissolution to reduce consumption.

[0027] The chemicals involved in the present invention are commonly used industrial chemical products and experimental reagents, which can be easily obtained through commercial purchase.

[0028] The chemical unit operations involved in the present invention are conventional operating techniques in the art, are well known to those skilled in the art, and are routinely used in chemical experiments and industrial production processes.

[0029] The present invention provides the following beneficial effects: the catalyst preparation method and the catalyst obtained thereby utilize widely available raw materials at low cost, reduce the harsh conditions during the preparation process, and facilitate manufacturing. When the prepared catalyst is used in the acetylene process for preparing vinyl acetate, it can exhibit improved catalytic performance, with good vinyl acetate space-time yield, selectivity, and activity stability, as well as good mechanical strength and thermal conductivity. During the reaction, harmful byproducts and carbon deposits are reduced, effectively extending the catalyst's service life, making it suitable for use in industrial production processes.

[0030] Other features and advantages of the present invention will also be described in detail in the following detailed description. DETAILED DESCRIPTION

[0031] The following examples are used to further describe the content and effects of the present invention. The examples are provided to illustrate the embodiments of the present invention, but are not intended to limit the broad interpretation of the present invention.

[0032] In the examples, atomic emission spectroscopy and X-ray fluorescence were used to determine the element contents, low-temperature nitrogen adsorption was used to determine the specific surface area and pore volume, and gas chromatography was used to analyze the composition of the raw materials and reaction products.

[0033] For other analytical tests, please refer to the relevant analytical methods in (National Standard for Test Methods for Petroleum and Petroleum Products, published by China Standards Press in 1989) and (Petrochemical Analysis Methods (RIPP Test Methods), published by Science Press in 1990).

[0034] Example 1

[0035] A solution prepared from chemically pure phosphoric acid and industrial pseudo-boehmite powder are added to deionized water, mixed in equal molar proportions at 50-60° C. with stirring, and subjected to dissolution reaction to prepare a dilute aluminum phosphate sol.

[0036] Press Zn α Bi β Si γ B λ Al μ P η O χ / C 100, α = 2.6, β = 0.0012, γ = 2.8, λ = 0.012, μ = 1.4, η = 1.4, the calculated amount of 250 mesh industrial wood carbon powder, industrial silicon carbide powder and industrial basic zinc carbonate powder were mixed uniformly, and then impregnated with a mixed solution of chemically pure reagents bismuth nitrate and boric acid at 20-40° C., and then added with the prepared aluminum phosphate dilute sol. After kneading in a laboratory small kneader for more than 1 hour, the mixture was extruded on a laboratory small extruder to form a strip carrier with a diameter of 2.4 mm and a length of 1.5 cm; dried in an oven at 105° C. for 4 hours, and activated by passing water vapor containing 1.5 wt% hydrogen peroxide at 600° C. for 4 hours in a closed tube furnace isolated from air in the laboratory; saturated impregnation with a 25 wt% zinc acetate solution with a pH value of 4.5 at 75° C. for 4 hours, and then dried at 100° C. for 6 hours to obtain the catalyst of Example 1 of the present invention.

[0037] The catalyst has an average pore diameter of 4 nm, a pore volume of 0.46 ml / g, and a surface area of 690 m 2 / g, bulk density is 0.46g / ml.

[0038] Comparative Example 1

[0039] Referring to the contents of the classic research literature on two zinc active components, zinc acetate and zinc chloride were used as active components and charcoal powder was used as a carrier; for the convenience of comparison with the present invention, the zinc component content was made similar to that of the present invention, and the catalyst of Comparative Example 1 was prepared.

[0040] Comparative Example 2

[0041] Referring to the content of the patent literature on the preparation of vinyl acetate catalyst by the classic acetylene process, zinc acetate is used as the active component, bismuth subcarbonate is used as the auxiliary agent, and commercial activated carbon (average pore diameter 2nm, pore volume 0.69ml / g, surface area 1200m 2 / g, bulk density of 0.40g / ml) as a carrier, and its preparation process requires harsh temperature conditions exceeding 900°C; for the convenience of comparison with the present invention, the contents of zinc and bismuth components are made similar to those of the present invention, and the catalyst of Comparative Example 1 is prepared for performance comparison with the catalyst of the embodiment of the present invention.

[0042] Comparative Example 3

[0043] The preparation content and steps were the same as those of Comparative Example 2, except that the industrial charcoal powder (bulk density of 0.42 g / ml) of Example 1 was used instead of commercial activated carbon to prepare the catalyst of Comparative Example 3 for performance comparison.

[0044] Comparative Example 4

[0045] The preparation content and steps are the same as those of Comparative Example 3, but the industrial silicon carbide powder (surface area of 90m2) of Example 1 is used. 2 / g, bulk density of 0.6g / ml) instead of charcoal powder to facilitate comparison with Example 1, to prepare the catalyst of Comparative Example 4, which was used for performance comparison with the catalysts of Example.

[0046] Example 2

[0047] Press Zn α Bi β Si γ B λ Al μ P η O χ / C 100 , α = 3.3, β = 0.0011, γ = 2.1, λ = 0.015, μ = 1.1, η = 1.1 constrained molar ratio, the calculated amount of 280 mesh industrial bamboo carbon powder, industrial silicon carbide powder and industrial basic zinc carbonate powder, after mixing uniformly, with a mixed solution of chemically pure reagents bismuth nitrate and boric acid, after equal volume impregnation at 30 ℃, added with aluminum phosphate dilute sol, after kneading in a small laboratory kneader for more than 1 hour, and pressed into a columnar carrier on a small hydraulic tablet press; dried in an oven at 110 ℃ for 2 hours, in a closed tube furnace isolated from air in the laboratory, at 620 ℃, water vapor containing 2.0wt% hydrogen peroxide was passed through for 4 hours; with a 20wt% zinc acetate solution with a pH value of 4.8 at 80 ℃, saturated impregnation for 5 hours, and then dried at 95 ℃ for 6 hours to obtain the catalyst of Example 2.

[0048] The catalyst has an average pore diameter of 3.9 nm, a pore volume of 0.41 ml / g, and a surface area of 640 m 2 / g, bulk density is 0.43g / ml.

[0049] Example 3

[0050] Press Zn α Bi β Si γ B λ Al μ P η O χ / C 100, α = 3.0, β = 0.0012, γ = 1.9, λ = 0.013, μ = 1.0, η = 1.0, the calculated amount of 300 mesh industrial coal-based carbon powder, industrial silicon carbide powder and industrial basic zinc carbonate powder were mixed uniformly, and then impregnated with a mixed solution of chemically pure reagents bismuth nitrate and boric acid at 35°C in equal volumes. After kneading in a laboratory small kneader for more than 1 hour, the carrier was rolled into a spherical support on a small roller machine after drying. During the rolling process, a dilute aluminum phosphate sol was added while the carrier was rolled into a spherical support; dried in an oven at 105°C for 5 hours, and activated in a closed tube furnace in the laboratory at 650°C with water vapor containing 2.5wt% hydrogen peroxide for 6 hours; saturated impregnation with a 30wt% zinc acetate solution with a pH value of 4.3 at 95°C for 8 hours, and then dried at 90°C for 6 hours to obtain the catalyst of Example 3.

[0051] The catalyst has an average pore diameter of 3.5 nm, a pore volume of 0.38 ml / g, and a surface area of 610 m 2 / g, bulk density is 0.48g / ml.

[0052] Example 4

[0053] This example illustrates the effects of the invention by comparing the catalysts of the examples and comparative examples.

[0054] The catalyst performance was evaluated using a small laboratory fixed-bed reactor with a catalyst loading volume of 25 ml. Industrial acetylene and industrial acetic acid were used as raw materials. The composition of the reaction feed gas was: acetic acid: acetylene = 6 (in terms of molar ratio), and the volumetric space velocity of the feed gas was 260 h-1. 1 .

[0055] During the evaluation process, the reaction pressure was 0.1 MPa, the reaction temperature was 175° C., and the reaction time was 150 hours.

[0056] The contents of the components in the reaction product were analyzed by gas chromatography, and the catalyst evaluation results are shown in Table 1.

[0057] Table 1. Evaluation results of catalysts of Examples 1 to 3 and Comparative Examples 1 to 4:

[0058]

[0059] During the reaction period, the activity decay rates for Examples 1-3 were 4%-6%, for Comparative Example 2 was 8%, and for Comparative Examples 1, 3, and 4, reached 14%-18%. The catalysts exhibited abrasion resistance of 94%-95% for Examples 1-3 and the Comparative Examples, 89% for Comparative Example 2, and 65% and 67% for Comparative Examples 1 and 3, respectively. Furthermore, byproducts and carbon deposits were reduced by approximately 5%-10% for Examples 1-3 compared to Comparative Examples 1-4.

[0060] It is shown that the catalyst prepared by the present invention can enable the catalyst to exert better catalytic performance when preparing vinyl acetate by the acetylene process, and has good vinyl acetate space-time yield, selectivity, and activity stability; reduces harmful by-products and carbon deposits, and has good mechanical strength, thereby effectively extending the service life of the catalyst, which is of positive significance for improving stable production in industrial applications.

[0061] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a catalyst for preparing vinyl acetate, comprising: catalyst The composition satisfies the chemical formula: Zn α Bi β Si γ B λ Al μ P η O χ / C 100 , wherein the atomic ratio α=1.4-3.8, β=0.001-0.002, γ=1.8-3.8, λ=0.01-0.02, μ=0.9-1.8, η=0.9-1.8, and χ is the number of oxygen atoms required to satisfy the atomic valence of each element; 200-300 mesh carbon powder, silicon carbide powder, and basic zinc carbonate are uniformly mixed, impregnated with a mixed solution of bismuth nitrate and boric acid of equal volume, aluminum phosphate sol is added, and kneaded for more than 40 minutes before forming; after drying, water vapor containing 1wt%-5wt% hydrogen peroxide is introduced at 300-700°C for activation for 1-8 hours; saturated impregnation is performed with zinc acetate solution, and then dried at 80-100°C for 1-6 hours; wherein the zinc element in the basic zinc carbonate accounts for 10wt%-40wt% of the total zinc content of the catalyst.

2. The method for preparing a catalyst for preparing vinyl acetate according to claim 1, characterized in that The carbon powder is one or more of wood carbon powder, bamboo carbon powder, coal-based carbon powder, fruit shell carbon powder, petroleum coke carbon powder and resin-based carbon powder.

3. A method for preparing a catalyst for preparing vinyl acetate according to claim 1, characterized in that the mixed solution of bismuth nitrate and boric acid is impregnated in equal volumes, wherein the mixed solution of bismuth nitrate and boric acid acidified and dissolved with nitric acid is impregnated in equal volumes with the powdered composite raw material at 20-100°C.

4. The method for preparing a catalyst for preparing vinyl acetate according to claim 1, characterized in that The aluminum phosphate sol is prepared by dissolving phosphoric acid solution and one or more of aluminum oxide, aluminum hydroxide, boehmite, pseudo-boehmite, aluminum isopropoxide and aluminum isobutoxide in an equimolar ratio of phosphorus and aluminum at 40-100°C.

5. The method for preparing a catalyst for preparing vinyl acetate according to claim 1, wherein the molding process is performed by hydraulic tableting, extrusion, or pelletizing to prepare columnar, block, sheet, or strip catalysts suitable for fixed-bed reaction processes; and the molding process is performed by rolling the spherical granular catalysts suitable for ebullient and fluidized-bed reaction processes in a catalyst roller.

6. The method for preparing a catalyst for preparing vinyl acetate according to claim 1, wherein the saturated impregnation with zinc acetate solution is performed by dissolving the carrier composition in a zinc acetate solution having a pH of 4 to 6 and a concentration of 20 wt% to 35 wt% in methanol and / or ethanol, and impregnating the carrier composition at 50 to 100° C. for 1 to 10 hours.

7. A catalyst for preparing vinyl acetate, characterized by Obtained according to the preparation method described in claims 1 to 6.

8. A catalyst for preparing vinyl acetate according to claim 7, characterized in that the catalyst has an average pore diameter of ≥2 nm, a pore volume of 0.4-0.6 ml / g, and a surface area of 600-900 m 2 / g, bulk density is 0.3~0.6g / ml.

9. Use of the catalyst according to claim 7 or 8 in the preparation of vinyl acetate, comprising reacting acetylene and acetic acid as raw materials in the presence of the catalyst according to claims 7 to 8 and the catalyst obtained by the preparation method according to any one of claims 1 to 6 to obtain vinyl acetate.

10. The use according to claim 9, characterized in that The molar ratio of acetylene to acetic acid is 1:(5-8), and the raw material volume space velocity is 250-350h -1 , reaction temperature 170~200℃, pressure 0.1~0.14MPa.

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