Catalyst for preparing vinyl acetate and preparation method therefor and use thereof

Abstract

The present invention relates to a catalyst for preparing vinyl acetate and a preparation method therefor, and the use thereof. The preparation method comprises the following steps: kneading, drying, and shaping an ultrafine silica gel powder, ultrafine diatomaceous earth, a silica sol, and a boron compound at a weight ratio of 100: (5-20): (10-60): (0.1-1), followed by calcination at 150-650ºC for 1-6 h to prepare a boron-doped composite SiO2 carrier; subjecting the carrier to incipient wetness impregnation with rolling with a solution of palladium and gold compounds at a Pd / (Au+Pd) molar ratio of 0.76-0.93 and a loading amount of 0.5%-1% relative to the carrier mass, followed by drying; treatment with an alkaline solution for 0.5-30 h, then drying, and reduction at 300-650ºC in a nitrogen-hydrogen atmosphere for 1-6 h, and washing same with water until chlorine-free, followed by drying; preparing a dilute sol by mixing copper acetate and cesium oxide at a Cu / (Re+Cu) molar ratio of 0.93-0.97 and a loading amount of 0.3%-1% with 0.5%-3% aluminum phosphate, followed by dip coating and drying; impregnating with a potassium acetate solution at a loading amount of 0.2%-7.5%, and performing a heat treatment at a negative pressure at 60-200ºC for 1-6 h, to obtain a highly stable, long-life catalyst, which has high strength and few by-products.

Description

A catalyst for preparing vinyl acetate, its preparation method and application Technical Field

[0001] This invention relates to the field of chemical technology, specifically to a catalyst for the preparation of vinyl acetate, its preparation method, and its application. More particularly, it relates to a palladium-containing silicon-supported long-life catalyst for the ethylene process of vinyl acetate preparation, its preparation method, and its application. Background Technology

[0002] Vinyl acetate is one of the world's 50 most produced chemical products. As a raw material for vinyl acetate resin and polyvinyl alcohol, and as a copolymer monomer 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] The ethylene process for producing vinyl acetate was discovered in the 1970s. This process utilizes ethylene, acetic acid, and oxygen to react together in the gas phase in the presence of a palladium / gold catalyst and an alkali metal co-catalyst to produce vinyl acetate. It has become a commonly used process, as illustrated in USP3725680 and USP3743607. The active component is typically supported on porous inorganic carrier materials such as silica (alumina), as illustrated in USP3775342 and USP3822308.

[0004] In early existing technologies, the palladium and gold active components of these catalysts were more or less uniformly distributed throughout the support (GB1333449). Due to the limited diffusion rate of reactants into the support, the contact between the large amount of palladium and gold active components inside the support and the reactants was significantly affected, resulting in a rather limited effect on the reaction. To address this problem, early technologies (GB1283737) also employed pretreatment of the porous support with an alkaline solution to control the penetration of active components into the support.

[0005] USP4048096 and USP4087622 disclose highly effective and widely used methods for preparing catalysts. These methods produce outer-layer impregnated catalysts by impregnating a support with an aqueous solution of palladium and gold compounds, precipitating the catalyst by soaking it in a solution of alkali metal silicates, converting the palladium and gold compounds to metallic palladium and gold using a reducing agent, washing with water, contacting with alkali metal acetates, and drying. This yields a high specific activity (83 gVAM / g(Pd+Au)h). -1 This eggshell-shaped catalyst is widely known and constitutes the most typical ethylene process catalyst preparation technology.

[0006] GB1500167 employs an outer layer impregnation method, where at least 90% of the palladium and gold are distributed within the support particles, specifically in the portion no more than 30% of the particle radius from the outer surface, to obtain a catalyst with the active components concentrated in the outermost layer of the support. GB1521652, on the other hand, attempts to distribute and fix the gold and palladium active components as uniformly as possible within a narrow area of ​​the support surface, aiming to obtain a vinyl acetate catalyst with high yield, good selectivity, and long lifetime. Subsequent patent documents EP565952A1, EP643214A1, EP643208A1, and EP643209A1 disclose technologies where the inner regions of the catalyst contain almost no precious metals. USP5314858 and USP5332710 also disclose highly active and particularly effective improvement methods that employ impregnation, precipitation, and reduction to uniformly fix the precious metals into a narrow area of ​​the support surface.

[0007] Modifying the elemental composition of the catalyst is a common approach in catalyst improvement research. USP4668819 and USP4902823 describe a palladium-potassium-cadmium catalyst, EP0565952A1 uses a palladium-potassium-cadmium or palladium-potassium-barium catalyst, and USP5567839 uses barium salts instead of sodium silicate for precipitation, with barium remaining in the catalyst. BP's CN1076875A improves yield by controlling the weight ratio of gold to palladium and the potassium acetate content. USP5179056, USP5189004, and USP5342987 also disclose that the presence of free sodium can improve space-time yield. USP5347046 contains copper, nickel, cobalt, silver, manganese, iron, and lead in addition to palladium and gold. USP5968869 loads copper before loading other active components to reduce the byproduct carbon dioxide, but this results in some loss of activity. EP1102635B1 uses the active component Pd / Au / HfO2; USP6605739 uses MoVNbX (X selected from phosphorus, boron, hafnium, tellurium, arsenic or their compounds) to prepare VAM; USP6849243B1 describes barium and cadmium as additional promoters; and USP2006 / 0135809A1 specifically discloses neodymium, titanium, magnesium, zirconium, yttrium, praseodymium, lanthanides and rubidium and their binary compositions as additional promoters.

[0008] Besides elemental modifications, adjustments to the preparation method are also frequently used. EP0464633 discloses various non-spherical, irregularly shaped catalysts, employing hollow catalyst supports to achieve advantages such as good heating distribution and low pressure drop. However, generally speaking, spherical catalysts tend to have better performance and ease of loading and unloading. USP5274181 uses hydrazine to reduce palladium and gold active elements, while EP0637209 uses hydrogen for reduction. USP5693586 uses ethylene reduction at 150°C and modification with potassium acetate to reduce CO2 byproducts. USP5990344 discloses a method for preparing palladium on a sintered support at temperatures exceeding 500°C, which promotes significant growth of palladium metal particles, thereby suppressing the problem of excessively high initial catalyst activity. USP6022823 calcines the support impregnated with palladium and gold salts before metal reduction to enhance catalyst activity. USP6420308 considers the order of preparation steps important and cleans the catalyst before reduction to obtain higher space-time yield and product selectivity.

[0009] In addition to the technical content disclosed in the aforementioned foreign patent documents, with the implementation of China's patent system in 1985, both foreign companies like Hechester Gas Company and domestic companies like the Shanghai Petrochemical Research Institute applied for a large number of patents with the same or similar content, such as CN1068104A, CN1078199C, CN1090534C, CN1093775C, CN1104281C, CN1107538C, CN1117619C, CN1127472C, CN1129481C, CN1215353A, CN1281385A, and CN112642480B, CN114425445B, CN1084219C, and CN100336593C, which involve the same element modification content.

[0010] Despite numerous reports of improved existing technologies, the catalytic efficiency and reaction results of this type of catalyst remain unstable due to factors such as reactant diffusion limitations, the morphology and distribution of active components, and side reactions caused by excessively high initial activity. This affects the catalyst's lifespan and often results in the formation of small amounts of CO2 and high-boiling-point byproducts. The use of precious metals leads to higher catalyst costs, and the catalyst is also subject to losses due to limitations in usage intensity, preventing it from fully realizing its optimal catalytic performance.

[0011] Therefore, continuous improvements are still needed in the field of silicon-supported catalysts for the ethylene process to produce vinyl acetate, particularly in terms of activity and selectivity, stability and lifespan, in order to further improve the catalytic efficiency, especially stability and long service life, reduce by-products and improve mechanical strength. Summary of the Invention

[0012] In view of the above-mentioned problems, the present invention aims to provide an improved method for preparing a catalyst for the preparation of vinyl acetate, and to make the catalyst obtained thereby have better reaction stability, reduce by-products, and improve the strength of use.

[0013] This invention provides a method for preparing a catalyst for preparing vinyl acetate, comprising the following steps:

[0014] (1) The boron-doped composite silica carrier was prepared by mixing, drying, molding, and calcining at 150-650℃ for 1-6 hours according to the weight ratio of ultrafine silica powder: ultrafine diatomaceous earth: silica sol: boron compound 100: (5-20): (10-60): (0.1-1) on a dry basis.

[0015] (2) Using a compound solution containing palladium and gold, with a Pd / (Au+Pd) molar ratio of 0.76 to 0.93 and a carrier mass of 0.5% to 1%, the mixture is rolled and dried in equal volumes.

[0016] (3) After treatment with alkaline solution for 0.5 to 30 hours, dry the product and reduce it at 300 to 650°C under a nitrogen-hydrogen atmosphere for 1 to 6 hours. Wash the product with water until it is free of chlorine and then dry it.

[0017] (4) Using copper acetate and rhenium oxide, and aluminum phosphate dilute sol accounting for 0.5% to 3% of the total catalyst weight, with a Cu / (Re+Cu) molar ratio of 0.93 to 0.97 and a Cu / (Re+Cu) molar ratio of 0.3% to 1%, mix evenly and then roll-dip coating and dry.

[0018] (5) The catalyst is prepared by impregnating it with potassium acetate solution at a ratio of 0.2% to 7.5% of the total weight of the catalyst and heat-treating it at 60 to 200°C and a negative pressure of -0.01 to -0.1 MPa for 1 to 6 hours.

[0019] In this invention, the catalyst support is composed of particles having any regular or irregular shape, such as spherical, granular, cylindrical, annular, star-shaped or other shapes, and may have a size of about 1-10 mm, such as diameter, length or width. So far, spherical shapes of about 4-8 mm are preferred, and spherical shapes of 5-7 mm are most preferred.

[0020] In this invention, the dry basis of silica sol is calculated as follows: if the silica sol contains 10% silica, its dry basis is 10% of the total weight.

[0021] In this invention, the calcination temperature in step (1) is any value or a range between any two of 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, and 650℃; and the calcination time is any value or a range between any two of 1h, 2h, 3h, 4h, 5h, and 6h.

[0022] In this invention, the boron compound in step (1) is boric acid and / or alkali metal borates; the alkali metal borates are selected from sodium tetraborate, sodium tetraborate pentahydrate, sodium tetraborate decahydrate, potassium tetraborate, potassium tetraborate pentahydrate, and potassium tetraborate decahydrate.

[0023] In this invention, in step (2), the equal volume impregnation refers to estimating the pore volume of the carrier by the water droplet method and obtaining the required volume of impregnation liquid so that the impregnation liquid can just meet the needs of completely wetting the carrier and fully adsorbing the impregnation, without leaving any remaining impregnation liquid that has not been adsorbed by the carrier. This is a conventional operation familiar to those skilled in the art.

[0024] In some specific embodiments of the present invention, the palladium and gold compound solution in step (2) is prepared by mixing palladium salt and gold salt; further, the palladium salt is selected from one or more of sodium chloropalladate, chloropalladic acid, palladium chloride, palladium acetate, sodium palladium chloride, potassium palladium chloride, palladium sulfate, and palladium nitrate solution.

[0025] In some specific embodiments of the present invention, the gold salt is selected from one or more of gold chloride, gold acetate, tetrachloroauric acid, sodium tetrachloroaurate, and potassium tetrachloroaurate solution.

[0026] In this invention, the alkaline solution treatment, water washing, drying and reduction described in step (3) are to fully precipitate and solidify the active components of palladium and gold on the carrier and reduce them to the metallic state; water washing until there is no chlorine in the washing liquid and no precipitation occurs when tested with 0.1 mol / L silver nitrate solution; drying conditions are to keep it at 20-160°C for 1-30 hours in air or nitrogen atmosphere.

[0027] In this invention, the alkaline solution is selected from inorganic and / or organic bases; wherein the inorganic base is preferably one or more of alkali metal hydroxides, aluminates, carbonates, bicarbonates, ammonium carbonate, and ammonia. Preferably, the inorganic base is selected from one or more aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, and potassium silicate.

[0028] In this invention, the aluminum phosphate dilute sol is obtained by dissolving one or more of phosphoric acid, aluminum oxide, aluminum hydroxide, boehmite, and pseudoboehmite in an equimolar ratio of phosphorus and aluminum.

[0029] In this invention, in steps (1) to (4), the drying can be carried out under air conditions or under an inert gas, and the drying temperature is 80℃ to 120℃; preferably, in steps (3) and (4), the drying is carried out under a nitrogen atmosphere at 100℃ for 4 hours.

[0030] In some specific embodiments of the present invention, the drying temperature is any value of 60°C, 70°C, 80°C, 90°C, 100°C or a range between any two; the drying time is any value of 3h, 4h, 5h, 6h, 7h, 8h or a range between any two.

[0031] In this invention, the dilution with deionized water involved in the preparation process is mainly to meet operational requirements and for convenience, and has no impact on the performance of the final catalyst. When the convenience of operation is not affected, the minimum amount of water used for dilution can be used to significantly reduce energy consumption.

[0032] The present invention also provides a catalyst for preparing vinyl acetate, which is prepared by the method described above.

[0033] In this invention, the catalyst prepared above is applied to the reaction process of preparing vinyl acetate by the ethylene method, especially in the long-life cycle operation process; preferably, during 20,000 hours of use, the unit yield is greater than 320 g / Lcat·h and the product selectivity is greater than 91%.

[0034] In this invention, the catalyst has a pore volume of 0.2–1.5 mL / g and a surface area of ​​50–300 m². 2 / g; bulk density is 0.5~0.65g / mL; compressive strength is 16~21KN / particle.

[0035] This invention provides a method for preparing vinyl acetate, wherein ethylene, acetic acid, and an oxygen-containing gas are reacted with a catalyst prepared by the method described above to obtain vinyl acetate.

[0036] In some specific embodiments of the present invention, the preparation conditions of the vinyl acetate further include: a temperature of 140–200°C, a pressure of 0.75–0.85 MPa, and a volume hourly space velocity (VHSV) of 1800–2200 h⁻¹ for the mixed gas. -1 The molar ratio of ethylene to acetic acid is 1:(0.2 to 0.3), and the oxygen content is 7% to 8% based on dry gas.

[0037] The chemicals involved in this invention are commonly used industrial chemical products and laboratory reagents, which can be easily obtained through commercial purchase.

[0038] The chemical unit operations involved in this invention are conventional operating techniques in the field, well known to those skilled in the art, and routinely used in chemical experiments and industrial production processes.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows: The catalyst preparation method and the catalyst obtained by the present invention have good space-time yield and selectivity of vinyl acetate in the reaction process for preparing vinyl acetate, enabling the expensive precious metal per unit mass to exert higher catalytic performance, especially with very good stability in catalytic reaction performance, so that it can be adapted to long life cycle, such as long-term stable operation of more than 20,000 hours, and has low carbon dioxide and high-boiling point byproducts, good mechanical strength during use, and is particularly suitable for long-life cycle industrial production processes. Detailed Implementation

[0040] The technical solution of the present invention will now be clearly and completely described. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0041] In the examples, atomic emission spectroscopy and X-ray fluorescence spectrometry were used to determine the elemental content, and gas chromatography was used to analyze the composition of raw materials and reaction products. Other analytical tests can be found in the relevant analytical methods in "National Standard for Testing Methods of Petroleum and Petroleum Products" (China Standards Press, 1989) and "Analytical Methods for Petrochemical Products (RIPP Test Methods)" (Science Press, 1990).

[0042] Materials and reagents used in this invention:

[0043] Coarse-pore silica powder: Industrial product, Qingdao Ocean Chemical Co., Ltd.

[0044] Boric acid: chemically pure, Beijing Chemical Reagent Company;

[0045] Diatomaceous earth: an industrial product, manufactured by Jilin Yuantong Mining.

[0046] Silica sol: Industrial grade, SiO2 10%, Qingdao Ocean Chemical Co., Ltd.

[0047] Sodium chloropalladium: chemically pure, Beijing Chemical Reagent Company;

[0048] Tetrachloroauric acid: chemically pure, Beijing Chemical Reagent Company;

[0049] Sodium silicate: Industrial grade, SiO2 20wt%, Sichuan Runhe Catalyst Co., Ltd.;

[0050] Phosphoric acid: chemically pure, 85%, Beijing Chemical Reagent Company;

[0051] Boehmite: Industrial product, Al2O3 70%, Shandong Aluminum Industry;

[0052] Copper acetate: chemically pure, Beijing Chemical Reagent Company;

[0053] Rhenium oxide: chemically pure, Beijing Chemical Reagent Company.

[0054] Example 1

[0055] A method for preparing a catalyst for vinyl acetate includes the following steps:

[0056] (1) Grind 1kg of coarse-pore silica powder, 150g of water-washed diatomaceous earth and 5g of boric acid in a stirring mill to 200 mesh, add 1.5L of silica sol, roll it into a spherical carrier with a diameter of 6mm on a laboratory rolling mill, air dry at 25℃ for 16h, dry in an oven at 80℃ for 4h, and then calcine in a muffle furnace at 400℃ for 3h.

[0057] (2) On a laboratory roller mill, using the equal volume impregnation method, 20g sodium chloropalladate and 6g tetrachloroauric acid were prepared into a 1L aqueous solution and rolled onto the surface of the above spherical carrier. The carrier was then dried in an oven at 100°C for 4 hours.

[0058] (3) The above-mentioned palladium and gold impregnation support was placed in a 1L solution containing 100g sodium silicate and allowed to stand at room temperature for 12h. Then, it was reduced at 450℃ for 4h with a nitrogen-hydrogen mixture containing 5v% hydrogen to completely reduce the palladium and gold compounds loaded on the support to elemental palladium and gold; then it was washed with deionized water until the eluent contained no Cl. - Until then, no precipitate was formed when tested with 0.1 mol / L silver nitrate solution, and then dried at 100℃ under a nitrogen atmosphere for 4 hours.

[0059] (4) 12g of phosphoric acid, 4g of boehmite and deionized water were reacted and stirred to form a sol; 7g of copper acetate and 0.5g of rhenium oxide were mixed to prepare a dilute sol, which was then uniformly coated and impregnated on the above-mentioned palladium and gold-containing carrier on a laboratory roller mill, and dried in an oven at 100°C under a nitrogen atmosphere for 4 hours.

[0060] (5) After cooling to room temperature, impregnate with an equal volume of aqueous solution containing 100g potassium acetate. After taking it out, keep it in a vacuum oven at 150℃ for 4h under a negative pressure of -0.09MPa to obtain the catalyst for preparing vinyl acetate, which is a catalyst with low palladium content.

[0061] Comparative Example 1

[0062] The catalyst used for comparison is a commercial ethylene-to-vinyl acetate catalyst with similar palladium, gold, and potassium content to that of Example 1 of this invention. Its active components are distributed as an eggshell-shaped structure with a silica support. Its preparation process and steps are similar to those in the classic preparation of vinyl acetate catalysts in patent document USP4048096.

[0063] Example 2

[0064] This embodiment is used to illustrate the reaction process of the catalyst of the present invention and the comparative catalyst.

[0065] The vinyl acetate catalyst prepared in Example 1 of this invention was placed in a 1-liter small side-stream experimental reactor attached to an industrial production unit of an overseas chemical plant. The catalyst of Example 1 had a pore volume of 0.65 ml / g and a surface area of ​​130 m². 2 / g, bulk density 0.59g / ml, compressive strength 21KN / particle.

[0066] Comparative Example 1, used for comparison, employed a commercial catalyst for the preparation of vinyl acetate, with a pore volume of 0.68 ml / g and a surface area of ​​160 m². 2 / g, bulk density 0.56g / ml, compressive strength >16KN / particle.

[0067] The composition of the raw gas is as follows: the ethylene content is not less than 99.9% by volume, the acetic acid content is not less than 99.5% by mass, and the oxygen content in the oxygen gas is not less than 99.7% by volume.

[0068] Process conditions: The temperature range during the reaction life is 140–200℃, with a slow temperature increase based on the unit production rate of vinyl acetate; the reaction pressure is 0.8 MPa; the steam mixture supply volume rate is 2000 h⁻¹. -1 The molar ratio of ethylene to acetic acid is 4:1, and the oxygen content is 7% based on dry gas.

[0069] Example 3

[0070] This embodiment is used to illustrate the comparison of the reaction process and results between the catalyst of the present invention and a comparative catalyst.

[0071] Evaluation tests conducted using a small-scale side-stream experimental reactor with a 2-year operating cycle showed that the vinyl acetate synthesis process was carried out under conditions where the initial reactants were not completely converted. The single-pass conversion rate of ethylene was ~8%, the conversion rate of acetic acid was ~18%, and the conversion rate of oxygen was ~45%. The content of the product vinyl acetate, by weight, was stable at ~99.90%. The unit yield was greater than 320 g / Lcat·h, and the relative rate of yield decrease was 0.9.

[0072] Regarding selectivity: the selectivity of vinyl acetate formation to ethylene is not less than 91% over its service life, with an average selectivity of 92.0%; the selectivity of vinyl acetate formation to acetic acid is 99.5%; the CO2 selectivity is ~7%; and the amount of byproducts formed does not exceed 1.0% of the amount of vinyl acetate produced.

[0073] Compared to the commercial catalyst over the same lifespan, it outperforms the comparative catalyst by 3 to 10 percentage points in terms of activity and selectivity, relative yield reduction, and yield of carbon dioxide and byproducts.

[0074] The catalyst prepared by the method of the present invention exhibits better space-time yield and selectivity of vinyl acetate in the reaction process of preparing vinyl acetate, as well as stability in catalytic reaction performance. It also has low carbon dioxide and high-boiling-point byproducts, good mechanical strength during use, and is more suitable for long-life industrial production processes.

[0075] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for producing a catalyst for producing vinyl acetate, characterized by, Includes the following steps: (1) The boron-doped composite silica carrier was prepared by mixing, drying, molding, and calcining at 150-650℃ for 1-6 hours according to the weight ratio of ultrafine silica powder: ultrafine diatomaceous earth: silica sol: boron compound 100: (5-20): (10-60): (0.1-1) on a dry basis. (2) Using a compound solution containing palladium and gold, with a Pd / (Au+Pd) molar ratio of 0.76 to 0.93 and a carrier mass of 0.5% to 1%, the mixture is rolled and dried in equal volumes. (3) After treatment with alkaline solution for 0.5 to 30 hours, dry the product and reduce it at 300 to 650°C under a nitrogen-hydrogen atmosphere for 1 to 6 hours. Wash the product with water until it is free of chlorine and then dry it. (4) Using copper acetate and rhenium oxide, and aluminum phosphate dilute sol accounting for 0.5% to 3% of the total catalyst weight, with a Cu / (Re+Cu) molar ratio of 0.93 to 0.97 and a Cu / (Re+Cu) molar ratio of 0.3% to 1%, mix evenly and then roll-dip coating and dry. (5) The catalyst is prepared by impregnating it with potassium acetate solution at a ratio of 0.2% to 7.5% of the total weight of the catalyst and heat-treating it at 60 to 200°C and a negative pressure of -0.01 to -0.1 MPa for 1 to 6 hours.

2. The production method according to claim 1, characterized by, The boron compound is boric acid and / or alkali metal borates.

3. The preparation method according to claim 1, characterized in that, The palladium and gold compound solution in step (2) is prepared by mixing palladium salt and gold salt; further, the palladium salt is selected from one or more of sodium chloropalladium, chloropalladium acid, palladium chloride, palladium acetate, sodium palladium chloride, potassium palladium chloride, palladium sulfate, and palladium nitrate solution.

4. The production method according to claim 1, characterized by, The gold salt is selected from one or more of gold chloride, gold acetate, tetrachloroauric acid, sodium tetrachloroaurate, and potassium tetrachloroaurate solution.

5. The method of claim 1, wherein, The alkaline solution is selected from inorganic bases and / or organic bases; further, the alkaline solution is an inorganic base; Furthermore, the inorganic base is selected from one or more aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, and potassium silicate.

6. The method of claim 1, wherein, The aluminum phosphate dilute sol is obtained by dissolving one or more of phosphoric acid, aluminum oxide, aluminum hydroxide, boehmite, and pseudoboehmite in an equimolar ratio of phosphorus and aluminum.

7. A catalyst for the production of vinyl acetate, characterized in that, It is prepared by the method described in any of claims 1 to 6.

8. The catalyst of claim 7, wherein The catalyst has a pore volume of 0.2–1.5 mL / g; a surface area of 50-300 m 2 / g; a bulk density of 0.5-0.65 g / mL; a compressive strength of 16-21 KN / acre; a vinyl acetate selectivity of greater than 91% and a unit productivity of greater than 320 g / Lcat-h during 20,000 hours of use.

9. A process for the preparation of vinyl acetate, characterized in that, Ethylene, acetic acid, and oxygen-containing gas are reacted with a catalyst prepared by any of the methods described in claims 1 to 6 to obtain vinyl acetate.

10. The method of claim 9, wherein, The preparation conditions of the vinyl acetate further include: temperature 140-200℃, pressure 0.75-0.85MPa, volume space velocity of mixed gas 1800-2200h -1 , molar ratio of ethylene to acetic acid 1:(0.2-0.3), oxygen content 7%-8% in terms of dry gas.