Renewable in-situ zinc-encapsulated molecular sieve catalyst, and preparation method, application and regeneration treatment method thereof

Abstract

The invention relates to the field of vinyl acetate synthesis, in particular to a reproducible in-situ zinc-encapsulated molecular sieve catalyst and a preparation method thereof, application of the reproducible in-situ zinc-encapsulated molecular sieve catalyst in a reaction for preparing vinyl acetate through acetylene acetic acid, and a regeneration treatment method of the reproducible in-situ zinc-encapsulated molecular sieve catalyst. The particle size of the molecular sieve catalyst is 50nm-100nm, the specific surface area is 300m < 2 > / g-400m < 2 > / g, and the zinc coating amount of the molecular sieve catalyst is 0.8 wt%-5wt%. The molecular sieve catalyst can anchor active components, inhibit loss of the active components and further improve the atom utilization rate of the active components, is high in catalytic activity and greatly improves the stability of a reaction for preparing vinyl acetate through acetylene acetic acid. Meanwhile, the molecular sieve catalyst can be used for removing deposited carbon through a regeneration treatment method, so that the regenerated catalyst capable of being recycled is obtained, and the molecular sieve catalyst has important application in industrial production.

Description

Technical Field

[0001] The present invention belongs to the field of vinyl acetate synthesis, and specifically relates to a regenerative in-situ zinc-encapsulated molecular sieve catalyst and a preparation method, an application of the regenerative in-situ zinc-encapsulated molecular sieve catalyst in the reaction of acetylene acetic acidification to prepare vinyl acetate, and a regeneration treatment method of the regenerative in-situ zinc-encapsulated molecular sieve catalyst. Background Art

[0002] Vinyl acetate, also known as vinyl acetate (VAc), is a new type of leading raw material in the field of organic chemical synthesis. It has extremely high technical and economic value derived from processing and production. It also occupies a place among the world's high-yield organic chemical raw materials. It itself and its derivatives are widely used in various fields.

[0003] There are two main production routes for vinyl acetate: the ethylene vapor phase process and the acetylene process. The ethylene vapor phase process is primarily concentrated in oil-rich countries like Europe and the United States, while the acetylene vapor phase process is predominant in coal-rich regions. The calcium carbide acetylene process, in particular, has garnered significant attention. The catalyst used in the acetylene process for vinyl acetate synthesis consists primarily of an active component and a support. Since the development of the acetylene process for vinyl acetate production by a German company in 1922, activated carbon-supported zinc acetate has been widely used in industry as a primary catalyst. While this catalyst offers advantages such as simple preparation, low cost, and easy availability, it also suffers from low reactivity, short catalyst life, and difficulty in regeneration. Therefore, research and development of catalyst improvements are crucial.

[0004] Patent Publication No. CN106423267A discloses a catalyst that addresses the low activity of acetylene vapor phase catalysts. It proposes using zinc acetate as the active component and activated carbon as the carrier, and adding platinum group metals palladium and rhodium, as well as alkaline earth metals beryllium and strontium, to improve the space-time yield of the product. Patent Publication No. CN107774319A addresses the inevitable high content of byproducts in the reaction. Furthermore, Patent Publication No. CN112517064A addresses the problem of high acetone content in the ethyl acetate product byproduct by using activated carbon as the carrier and adding a zinc salt of a dicarboxylic acid to the active component to reduce the acetone content in the reaction product. Patent Publication No. CN117772276A discloses a method for preparing a catalyst for synthesizing vinyl acetate from the acetylene process, which reduces the catalyst's activity decay rate from 12% to 0.4%. Patent publication number CN1903435A improves the stability of the catalyst by adding bismuth subcarbonate as a metal additive. However, most of the above patents are improvements aimed at a single problem.

[0005] Regarding the problem of catalyst deactivation, the biggest challenge facing catalysts with carbon-based materials as carriers is carbon deposition on the catalysts. The carbon deposition covers the active sites, further blocking the catalyst pores and ultimately reducing the catalyst life. The simplest solution to carbon deposition is high-temperature treatment in the presence of oxygen. However, due to the limitations of the carrier, activated carbon decomposes into carbon dioxide when treated at high temperatures in air. This characteristic makes it impossible to regenerate our carbon-based carrier catalysts through simple carbon removal methods. Without an effective regeneration method, the deactivated carbon-based catalysts can only be discarded, becoming one of the "three wastes" (solid waste). The generation of large amounts of solid waste catalysts is not conducive to green environmental development and energy conservation.

[0006] Based on the above shortcomings, it is very necessary to develop a catalyst that can anchor active components to inhibit loss, and at the same time has air thermal stability, can remove carbon deposits, and is regenerable. Summary of the Invention

[0007] In order to solve the problems of easy loss of active components of the catalyst and difficult regeneration of the catalyst due to carbon deposition and deactivation in the acetylene acetic acidification reaction, the present invention proposes to prepare a regenerable in-situ zinc-encapsulated molecular sieve catalyst and apply it to the acetylene acetic acidification reaction process.

[0008] The first object of the present invention is to provide a regenerable in-situ zinc-encapsulated molecular sieve catalyst having a particle size of 50 nm to 100 nm and a specific surface area of ​​300 m 2 / g-400m 2 / g, and the zinc coating amount of the molecular sieve catalyst is 0.8wt%-5wt%.

[0009] Furthermore, the zinc incorporation form of the molecular sieve catalyst is directly synthesized in the form of in-situ coating.

[0010] The second object of the present invention is to provide a method for preparing the regenerable in-situ zinc-encapsulated molecular sieve catalyst, which specifically includes: S1, mixing a silicon source, an organic template, an aluminum source, a mineralizer and a zinc source, and stirring them evenly to form a mixed gel, wherein the expression of the mixed gel is 60SiO2·15TPAOH·5Na2O·yZnO·xAl2O3·500H2O, wherein x=0.06-1.5, y=0.5-3; S2, the mixed gel is subjected to a hydrothermal crystallization reaction, washing, drying and calcining in sequence to obtain a catalyst precursor; S3, the catalyst precursor is ion exchanged with an ammonium chloride solution, and the in-situ zinc-encapsulated molecular sieve catalyst is obtained after centrifugation, drying and calcining.

[0011] Furthermore, in step S1, at least one of the following conditions is satisfied: (1) the aluminum source is selected from one or more of aluminum nitrate, aluminum isopropoxide, and sodium aluminate; and (2) the zinc source is selected from one or more of zinc nitrate, zinc acetate, and zinc sulfate.

[0012] Furthermore, in step S2, at least one of the following conditions is satisfied: (1) the reaction temperature of the hydrothermal reaction is 150°C-200°C, and the reaction time is 24h-96h; (2) the drying temperature is 80°C-120°C, and the drying time is 12h-24h; (3) the calcination temperature is 500°C-600°C, and the calcination time is 3h-8h.

[0013] Furthermore, in step S3, calcination is carried out in a muffle furnace, including: (1) the heating rate of the calcination is 1°C / min-10°C / min, and the preferred heating rate is 1°C / min-3°C / min; (2) the initial temperature of the calcination is 20°C, and the temperature at which the heating is terminated is 500°C-600°C; (3) the calcination is kept warm for 3h-8h after the heating is terminated.

[0014] The third object of the present invention is to provide an application of a regenerable in-situ zinc-encapsulated molecular sieve catalyst, wherein the regenerable in-situ zinc-encapsulated molecular sieve catalyst is applied to the acetylene acetic acidification reaction to produce vinyl acetate.

[0015] Furthermore, the application satisfies at least one of the following conditions: (1) the reaction temperature of the acetylene acetic acidization reaction to produce vinyl acetate is 180°C-300°C; (2) the acetylene reaction space velocity of the acetylene acetic acidization reaction to produce vinyl acetate is 100h -1 -500h -1 (3) The molar ratio of acetic acid to acetylene in the acetylene acetic acidization reaction to produce vinyl acetate is 1:3-1:12.

[0016] The fourth object of the present invention is to provide a regeneration method for a regenerable in-situ zinc-encapsulated molecular sieve catalyst, comprising: placing the molecular sieve catalyst according to claim 1 that has been deactivated after use in a muffle furnace at 500°C for 3 hours to obtain a regenerated in-situ zinc-encapsulated molecular sieve catalyst.

[0017] Compared with the prior art, the present invention has the following advantages: (1) The present invention provides a reproducible in-situ zinc-encapsulated molecular sieve catalyst. The molecular sieve catalyst anchors the active component by encapsulating metallic zinc within the molecular sieve structure. The molecular sieve framework is used to structurally restrict the active component zinc, thereby greatly inhibiting the loss of the active component, improving the atomic utilization of the active component, and achieving high catalytic activity, improved reaction stability, and reduced activity decay rate of the molecular sieve catalyst. The molecular sieve catalyst is prepared by adding a zinc precursor solution to a precursor gel for molecular sieve synthesis and synthesizing the catalyst through a one-step hydrothermal method. The preparation method is simple and more conducive to the stable binding of the active component zinc within the catalyst.

[0018] (2) The present invention also provides a regenerative in-situ zinc-encapsulated molecular sieve catalyst for use in acetylene acetic acidification, demonstrating excellent catalytic performance and stability. This is also the first time that an in-situ zinc-encapsulated molecular sieve catalyst has been used in acetylene acetic acidification. The molecular sieve catalyst is silicon-based, unlike traditional carbon-based catalysts. After use, it can be calcined and regenerated in air. Calcining the used molecular sieve catalyst at high temperature effectively removes carbon deposits from the catalyst, allowing for regeneration and reuse. This overcomes the difficulty in regenerating carbon deposits from traditional catalysts, reduces industrial production costs, and is simple to operate and has a high success rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an X-ray diffraction spectrum of the regenerable in-situ zinc-encapsulated molecular sieve catalyst prepared in Example 1 of the present invention; Figure 2 Graph showing the performance data of the molecular sieve catalyst A of Example 1 and the regenerated molecular sieve catalyst A' of Example 4 of the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Anything not described in detail in the present patent application is to be understood as common knowledge in the art.

[0021] Vinyl acetate, also known as vinyl acetate (VAc), and its derivatives are widely used in various fields. Because it can undergo self-polymerization or copolymerization with various substances to produce a variety of chemical industrial raw materials, its main polymerization products can be used as emulsifiers, stabilizers, film products, protective coatings, shoe sole adhesives, foam materials, and synthetic fiber leather processing products. It has a wide range of applications and developments in various fields such as medicine, cosmetics, coatings, textiles, packaging, rubber, chemicals, and fine chemicals, and has a significant impact on national economic development.

[0022] There are two main production processes for vinyl acetate: the ethylene vapor phase process and the acetylene process. The catalyst for vinyl acetate synthesis using the acetylene process primarily consists of an active component and a support. Since the development of the acetylene process for vinyl acetate production by a German company in 1922, activated carbon-supported zinc acetate has been widely used in industry as the primary catalyst. While this catalyst offers the advantages of simple preparation, low cost, and easy availability, it also suffers from issues such as low reactivity, short catalyst life, and difficulty in regeneration. Therefore, research and development of catalyst improvements are particularly important. Studies have shown that the introduction of a co-catalyst can significantly improve catalyst performance and reduce by-product content. To address the prominent issue of short catalyst life, researchers have found that the loss of active components and carbon deposition on the catalyst can both shorten the catalyst life.

[0023] Molecular sieves have excellent thermal stability and can exist stably in high-temperature air. This property allows deactivated catalysts to be regenerated. At the same time, molecular sieves, due to their regular pore structure and adjustable acidity, can provide more active sites for acetylene acetic acidization and are an ideal metal loading carrier.

[0024] In-situ coating of the active component utilizes the molecular sieve framework to encapsulate and anchor the active zinc metal. Once embedded within the molecular sieve structure, the active zinc metal is restricted in its movement, making it less likely to escape from the catalyst and allowing it to participate in the reaction longer. This significantly reduces the catalyst's activity decay, significantly enhances its usable life, and improves its stability. Therefore, molecular sieve catalysts with in-situ zinc encapsulation are being developed to address the issue of catalyst stability and regeneration difficulties in the acetylene acetoxylation reaction. Currently, no published or authorized patents exist for using molecular sieve in-situ zinc encapsulation as catalysts for the acetylene acetoxylation reaction.

[0025] The following specific embodiments provide a method for preparing a variety of molecular sieve catalysts, specifically: S1, mixing a silicon source, an organic template, an aluminum source, a mineralizer and a zinc source, and stirring them evenly to form a mixed gel, wherein the silicon source can be selected from one or more of tetraethyl silicate, liquid silica gel, and silicalite-1 seed crystals; the aluminum source can be selected from one or more of aluminum nitrate, aluminum isopropoxide, and sodium metaaluminate; the zinc source can be selected from one or more of zinc nitrate, zinc acetate, and zinc sulfate; in the specific operation, the zinc source can be dissolved in a solvent to prepare A zinc precursor aqueous solution with a concentration of 0.2M-0.3M is prepared; the silicon source: aluminum source ratio is 60:0.12-60:3; the silicon source: zinc source ratio is 60:0.5-60:3; the organic template can be tetrapropylammonium hydroxide; and the mineralizer is sodium hydroxide, which is conventionally selected in the art. The resulting mixed gel has the formula 60SiO2·15TPAOH·5Na2O·yZnO·xAl2O3·500H2O, where x = 0.06-1.5 and y = 0.5-3. The mixed gel S2 is sequentially subjected to a hydrothermal crystallization reaction (reaction temperature 150°C-200°C, reaction time 24h-96h), washing, drying (drying temperature 80°C-120°C, drying time 12h-24h), and calcination (calcination temperature 500°C-600°C, calcination time 3h-8h) to obtain a catalyst precursor. S3. The catalyst precursor is ion-exchanged with an ammonium chloride solution, followed by centrifugation, drying, and calcination to obtain an in-situ zinc-encapsulated molecular sieve catalyst. The calcination is performed in a muffle furnace at an initial temperature of 20°C, a heating rate of 1°C / min-10°C / min, a termination temperature of 500°C-600°C, and a holding period of 3-8 hours after termination. In another embodiment, the heating rate in step S3 is 1°C / min-3°C / min.

[0026] The molecular sieve catalyst prepared by the above method has a particle size of 50nm-100nm and a specific surface area of ​​300m 2 / g-400m 2 / g, the coating amount of zinc in the molecular sieve catalyst is 0.8wt%-5wt%, and the zinc is directly synthesized in the form of in-situ coating.

[0027] The molecular sieve catalyst can be used to catalyze the reaction of acetylene acetic acid to vinyl acetate. In some specific embodiments, the reaction temperature of the reaction of acetylene acetic acid to vinyl acetate is 180°C-300°C; in other specific embodiments, the reaction space velocity of acetylene is 100h -1 -500h -1 The molar ratio of acetic acid to acetylene is 1:3-1:12. The use of the molecular sieve catalyst does not limit the reaction conditions of the acetylene acetic acidification reaction to prepare vinyl acetate.

[0028] Regeneration of the used molecular sieve catalyst yields a regenerated in-situ zinc-encapsulated molecular sieve catalyst, which can be reused to catalyze the acetylene acetylating reaction to produce vinyl acetate. The regeneration process involves treating the deactivated molecular sieve catalyst in a muffle furnace at 500°C for three hours to yield a regenerated in-situ zinc-encapsulated molecular sieve catalyst. Example 1

[0029] This embodiment provides a regenerable in-situ zinc-encapsulated molecular sieve catalyst, the preparation method of which is as follows: S1. Weigh 20.34 g of tetrapropylammonium hydroxide solution and 20.83 g of ethyl orthosilicate solution into a three-necked flask, then add an appropriate amount of deionized water, and reflux with stirring in an 80°C oil bath for 24 hours; then weigh 0.187 g of aluminum nitrate to prepare solution a and 0.666 g of sodium hydroxide to prepare solution b, and drop solution a and solution b into the three-necked flask in turn, and continue stirring for half an hour. Take 0.183 g of zinc acetate and ethylenediamine to prepare a zinc precursor aqueous solution and drop it evenly into the three-necked flask again. After stirring at 80°C for 5 hours, a mixed gel with a molar composition of 60 SiO2:15 TPAOH:5 Na2O:0.5 ZnO:0.15Al2O3:500 H2O is obtained.

[0030] S2. The mixed gel was transferred to the polytetrafluoroethylene lining of a stainless steel crystallization kettle and allowed to stand in a forced air drying oven at 170°C for crystallization for 24 hours. It was then taken out, washed with deionized water until neutral and dried, and then placed in a muffle furnace at 550°C for calcination for 6 hours to remove the template to obtain catalyst precursor A.

[0031] S3. Catalyst precursor A was ion exchanged with 0.8 M NH4Cl solution at a solid-liquid ratio of 1:20 at 80°C for three times, each for 3 hours, and then calcined at 550°C for 6 hours to obtain molecular sieve catalyst A.

[0032] The powder of the in-situ zinc-encapsulated molecular sieve catalyst A was subjected to an X-ray diffraction experiment, and the X-ray diffraction spectrum was obtained as follows: Figure 1 As shown, it shows that the molecular sieve catalyst with in-situ zinc encapsulation still has an MFI structure and no metal peak, indicating that the metal has good dispersion. Example 2

[0033] This embodiment provides a regenerable in-situ zinc-encapsulated molecular sieve catalyst. The preparation method is basically the same as that of Example 1, except that in step S1, the zinc precursor aqueous solution is prepared by configuring 0.549 g of zinc acetate and ethylenediamine to obtain a mixed gel with a molar composition of 60 SiO2:15 TPAOH:5 Na2O:1.5 ZnO:0.15Al2O3:500 H2O; the operation in step S2 is performed to obtain catalyst precursor B; in step S3, catalyst precursor B is ion-exchanged with 0.8 M NH4Cl solution at a solid-to-liquid ratio of 1:20 at 80°C three times for 3 hours each time, and then calcined at 550°C for 6 hours to obtain molecular sieve catalyst B. Example 3

[0034] This embodiment provides a regenerable in-situ zinc-encapsulated molecular sieve catalyst. The preparation method is basically the same as that of Example 1, except that in step S1, the zinc precursor aqueous solution is prepared by configuring 1.097 g of zinc acetate and ethylenediamine to obtain a mixed gel with a molar composition of 60 SiO2:15 TPAOH:5 Na2O:3 ZnO:0.15Al2O3:500 H2O; the operation in step S2 is performed to obtain catalyst precursor C; in step S3, catalyst precursor B is ion-exchanged with 0.8 M NH4Cl solution at a solid-to-liquid ratio of 1:20 at 80°C three times for 3 hours each time, and then calcined at 550°C for 6 hours to obtain molecular sieve catalyst C. Example 4

[0035] The molecular sieve catalyst A prepared in Example 1 was used as a sample and used in the reaction of acetylene acetic acidification to produce vinyl acetate. After its catalytic effect was fully exerted, the carbon-deposited inactivated molecular sieve catalyst was calcined at high temperature to allow the carbon deposits to burn into gas in the air, thereby effectively removing the carbon deposits from the molecular sieve catalyst. The specific operation was as follows: the carbon-deactivated molecular sieve catalyst A was placed in a muffle furnace and calcined at 500°C-800°C for 3-6 hours until the color changed significantly, thereby obtaining a regenerated in-situ zinc-encapsulated molecular sieve catalyst A'.

[0036] Furthermore, the stability test of the molecular sieve catalyst A prepared in Example 1 and the corresponding regenerated molecular sieve catalyst A' was performed, and the results were as follows: Figure 2 The performance data graph shown is from Figure 2 It can be seen that the molecular sieve catalyst can basically recover to its initial performance after regeneration.

[0037] Comparative Example 1 Weigh 2 grams of activated carbon powder and 0.08 grams of zinc acetate solid in 50 mL of deionized water. Stir at room temperature for 12 hours, then dry the catalyst at 80°C. Place the dried catalyst in a tube furnace and, under a nitrogen atmosphere, heat the temperature at a rate of 5°C / min to 550°C. Maintain the temperature for 6 hours. Cool naturally to room temperature to obtain supported zinc catalyst A.

[0038] Test Example 1 The catalysts prepared in Examples 1-3 and Comparative Example 1 were taken as samples and labeled. Each sample was used in the acetylene acetic acidification reaction to produce vinyl acetate to verify its catalytic performance. The specific operation was as follows: 0.6 g of catalyst was weighed and loaded into a fixed bed reactor. Nitrogen was introduced and the temperature was raised to 180°C. Acetic acid was introduced for activation for 0.5 hours, and then acetylene was introduced. At 260°C and an acetylene volume space velocity of 200 h -1 The reaction was carried out under the conditions of acetic acid and acetylene having a volume ratio of 1:3. The obtained products were analyzed by gas chromatography GC-2014.

[0039] The deactivated catalyst was removed and treated in a muffle furnace at 500°C for 3 hours to obtain regenerated molecular sieve catalysts A', B', and C'. 0.6 g of the regenerated molecular sieve catalyst was loaded into the fixed-bed reactor and reacted again according to the above steps. The resulting product was analyzed by gas chromatography-mass spectrometry (GC-2014).

[0040] The catalytic performance of the molecular sieve catalyst and the regenerated molecular sieve catalyst was measured by gas chromatography GC-2014. The results are shown in Table 1.

[0041] Table 1 Catalytic performance of acetylene acetylating reaction with different catalysts Silicon-zinc ratio Maximum acetic acid conversion rate (%) 72-hour activity decay rate (%) Conversion rate after regeneration (%) Vinyl acetate selectivity (%) Example 1 60：0.5 77.56 17 77.28 88 Example 2 60：1.5 75.08 20 73.93 86 Example 3 60：3 74.73 20 73.87 86 Comparative Example 1 / 50.53 28 Non-renewable 81 As can be seen from the data in Table 1, with the same content of active component zinc, the molecular sieve catalyst prepared by the technical solution of the present invention has better catalytic performance and lower activity decay rate. In addition, compared with the supported zinc catalyst prepared in Comparative Example 1, the molecular sieve catalyst prepared by the technical solution of the present invention can be regenerated, while the traditional carbon-based supported zinc catalyst cannot be regenerated after deactivation. As the silicon-zinc ratio decreases, the vinyl acetate conversion rate decreases slightly. A silicon-zinc ratio of 60:0.5 has a better catalytic effect on the acetylene acetoxylation reaction. In addition, the catalysts prepared by the technical solution of the present invention can all be regenerated.

[0042] The molecular sieve catalyst in situ encapsulates the zinc component in the molecular sieve structure in a one-step process, anchoring the active component to prevent migration, significantly enhancing the interaction between the molecular sieve and the active metal, inhibiting the loss of active components, and thus lowering the catalyst activity decay rate. At the same time, its excellent thermal stability enables the catalyst to remain stable and unchanged during high-temperature treatment of carbon deposits in air, giving the catalyst the ability to regenerate.

[0043] The above description is based on the ideal embodiment of the present invention. Based on the above description, relevant personnel can make various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the content of the specification and must be determined according to the scope of the claims.

Claims

1. A regenerable in-situ zinc-encapsulated molecular sieve catalyst, characterized in that: The particle size of the molecular sieve catalyst is 50nm-100nm and the specific surface area is 300m 2 / g-400m 2 / g, and the zinc coating amount of the molecular sieve catalyst is 0.8wt%-5wt%.

2. The molecular sieve catalyst according to claim 1, characterized in that The zinc incorporation form of the molecular sieve catalyst is directly synthesized in the form of in-situ coating.

3. A method for preparing a regenerable in-situ zinc-encapsulated molecular sieve catalyst, characterized in that: include: S1, mixing a silicon source, an organic template, an aluminum source, a mineralizer, and a zinc source, and stirring them uniformly to form a mixed gel, wherein the expression of the mixed gel is 60SiO2·15TPAOH·5Na2O·yZnO·xAl2O3·500H2O, wherein x=0.06-1.5, y=0.5-3; S2, the mixed gel is subjected to a hydrothermal crystallization reaction, washed, dried and calcined in sequence to obtain a catalyst precursor; S3. The catalyst precursor is subjected to ion exchange with an ammonium chloride solution, and the in-situ zinc-encapsulated molecular sieve catalyst is obtained after centrifugation, drying, and calcination.

4. The preparation method according to claim 3, characterized in that In step S1, at least one of the following conditions is met: (1) The aluminum source is selected from one or more of aluminum nitrate, aluminum isopropoxide, and sodium metaaluminate; (2) The zinc source is selected from one or more of zinc nitrate, zinc acetate, and zinc sulfate.

5. The preparation method according to claim 3, characterized in that In step S2, at least one of the following conditions is met: (1) The reaction temperature of the hydrothermal reaction is 150°C-200°C, and the reaction time is 24h-96h; (2) The drying temperature is 80°C-120°C and the drying time is 12h-24h; (3) The calcination temperature is 500°C-600°C and the calcination time is 3h-8h.

6. The preparation method according to claim 3, characterized in that In step S3, calcination is carried out in a muffle furnace, comprising: (1) The heating rate of the calcination is 1°C / min-10°C / min, and the preferred heating rate is 1°C / min-3°C / min; (2) The initial temperature of the calcination is 20°C and the temperature at which the temperature rise is terminated is 500°C-600°C; (3) After the calcination is terminated and the temperature is raised, the temperature is kept at this temperature for 3 hours to 8 hours.

7. Application of a regenerable in-situ zinc-encapsulated molecular sieve catalyst, characterized in that: The regenerable in-situ zinc-encapsulated molecular sieve catalyst is applied to the reaction of acetylene acetic acidification to prepare vinyl acetate.

8. The use according to claim 7, characterized in that The application of the regenerable in-situ zinc-encapsulated molecular sieve catalyst satisfies at least one of the following: (1) The reaction temperature of the acetylene acetic acidification reaction to produce vinyl acetate is 180°C-300°C; (2) The acetylene reaction space velocity of the acetylene acetic acidification reaction to produce vinyl acetate is 100h -1 -500h -1 ; (3) The molar ratio of acetic acid to acetylene in the acetylene acetic acidization reaction to produce vinyl acetate is 1:3-1:

12.

9. A regeneration method for a regenerable in-situ zinc-encapsulated molecular sieve catalyst, characterized in that: include: The molecular sieve catalyst according to claim 1 that is deactivated after use is placed in a muffle furnace at 500° C. for treatment for 3 hours to obtain a regenerated in-situ zinc-encapsulated molecular sieve catalyst.

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