Zn-based catalyst for catalyzing acetylation reaction of acetylene as well as preparation method and application of Zn-based catalyst

Abstract

The invention provides a Zn-based catalyst for catalyzing an acetylation reaction of acetylene as well as a preparation method and application of the Zn-based catalyst, and belongs to the technical field of catalyst preparation. The Zn-based catalyst for catalyzing the acetic acid reaction of acetylene is prepared by taking pyrophosphoric acid modified porous carbon as a carrier and Zn (OAc) 2 as an active component; according to the Zn-based catalyst, pyrophosphoric acid groups are introduced to regulate the surface characteristics of the catalyst, the adsorption effect of zinc active sites on acetylene is weakened, meanwhile, the adsorption capacity on acetic acid is enhanced, in addition, pyrophosphoric acid modification effectively inhibits formation of carbon deposition and agglomeration of active components in the reaction process, dispersion of zinc species is enhanced, and the catalytic activity of the catalyst is improved. Therefore, the activity and the stability of the catalyst are obviously improved; the preparation method of the Zn-based catalyst is simple and efficient, can be popularized in industrial application, and has good practicability.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and particularly relates to a Zn-based catalyst for catalyzing the acetylation reaction of acetylene, a preparation method thereof, and an application thereof. Background Art

[0002] Vinyl acetate (VAc) is an important organic chemical raw material, which is mainly used for producing chemical products such as polyvinyl alcohol resin, synthetic fiber, adhesive, and water-soluble coating. At present, the main production methods of vinyl acetate are the ethylene method and the acetylene method. However, the ethylene method requires abundant petroleum resources and has a high production cost, while the synthesis of vinyl acetate by the acetylene gas phase method uses coal as the raw material, and the raw material source is rich, which has high research value.

[0003] A suitable catalyst carrier can improve the performance of the catalyst such as stability, activity, and selectivity, so as to achieve a more efficient catalytic reaction. In recent years, many scholars have studied the active components, carriers, and new materials of the catalyst in the acetylation reaction of acetylene, and certain progress has been made in acetylene acetylation. Surface chemical modification mainly changes the acidity and alkalinity of the activated carbon surface, grafts or eliminates certain specific functional groups, so that it has a certain catalytic performance when used as a carrier. Therefore, the chemical properties of activated carbon depend on the type and quantity of the surface active functional groups. It is of great significance to modify the activated carbon according to the different characteristics of the adsorbate. At present, the common activated carbon modification methods mainly include: oxidation modification, reduction modification, loading modification, and plasma modification. Some scholars have prepared a series of zinc-based catalysts with rich oxygen-containing functional groups by treatment with ozone, boric acid, and cyanamide solution, but they still have the disadvantages of low conversion rate and easy deactivation. Therefore, it is necessary to develop a new zinc-based catalyst with high catalytic activity and stability for catalyzing the acetylation reaction of acetylene. Summary of the Invention

[0004] In view of some deficiencies in the prior art, the present invention provides a Zn-based catalyst for catalyzing the acetylation reaction of acetylene, a preparation method thereof, and an application thereof; in the present invention, a porous carbon modified with pyrophosphoric acid is used as the carrier, and Zn(OAc)2 is used as the active component to prepare a Zn-based catalyst for catalyzing the acetylation reaction of acetylene; the Zn-based catalyst introduces pyrophosphoric acid groups to regulate the surface characteristics of the catalyst, weakens the adsorption of acetylene by zinc active sites, and at the same time enhances the adsorption capacity for acetic acid. In addition, pyrophosphoric acid modification effectively inhibits the formation of carbon deposition and the agglomeration of active components during the reaction process, enhances the dispersion of zinc species, and thus significantly improves the activity and stability of the catalyst; the preparation method of the Zn-based catalyst is simple and efficient, can be popularized in industrial applications, and has good practicability.

[0005] In order to achieve the above technical purpose, the present invention adopts the following technical means: The present invention first provides a Zn-based catalyst for catalyzing the acetylation reaction of acetylene. The Zn-based catalyst uses anhydrous zinc acetate (Zn(OAc)2) as the active component and porous carbon modified with pyrophosphoric acid as the carrier; the loading amount of Zn atoms in the Zn-based catalyst is 9-12 wt.%.

[0006] Preferably, the porous carbon includes coconut shell activated carbon.

[0007] Preferably, the loading amount of Zn atoms in the Zn-based catalyst is 10 wt.%.

[0008] The present invention also provides a preparation method of the above Zn-based catalyst. The preparation method includes: Adding porous carbon to an aqueous solution of pyrophosphoric acid, stirring and reacting for the first time at room temperature, drying after the reaction ends, and then pyrolyzing the dried product to obtain porous carbon modified with pyrophosphoric acid; Adding the porous carbon modified with pyrophosphoric acid to an aqueous solution of anhydrous zinc acetate, stirring and reacting for the second time at room temperature, and drying after the reaction ends to obtain the Zn-based catalyst.

[0009] Preferably, the porous carbon includes coconut shell activated carbon.

[0010] Preferably, the mass ratio of pyrophosphoric acid to porous carbon is 0.007-0.05; The time of the first stirring reaction is 12 h.

[0011] Preferably, the pyrolysis conditions are: heating to 600-1000 °C and pyrolyzing for 2 h under the condition that the atmosphere is N2 and the flow rate is 50 mL / min; the heating rate during pyrolysis is 5 °C / min.

[0012] Preferably, in the aqueous solution of anhydrous zinc acetate, the dosage ratio of anhydrous zinc acetate to deionized water is 0.78 g:20 mL; the time of the second stirring reaction is 12 h; In the Zn-based catalyst, the loading amount of Zn atoms is 9-12 wt.%.

[0013] The present invention also provides the application of the above Zn-based catalyst in the catalysis of the acetylation reaction of acetylene.

[0014] Preferably, the acetylation reaction of acetylene is a gas-phase reaction, and the reaction steps are: acetylene reacts with acetic acid vapor under the catalysis of the above Zn-based catalyst to generate vinyl acetate.

[0015] The main reactions involved in the above acetylation reaction of acetylene include: Main reaction: Main side reactions: The acetylene acetylation reaction temperature is controlled between 170 and 260 °C. Preferably, the reaction temperature of the present invention is controlled at 220 °C.

[0016] The molar ratio of acetylene to acetic acid adopts the common volume ratio of 3-5:1 in the art. Preferably, the molar ratio of acetylene to acetic acid in the present invention is 3:1.

[0017] The gas-phase reaction is carried out in a fixed-bed reactor, and the Zn-based catalyst is loaded in the fixed-bed reactor. The control range of the acetylene space velocity adopts the common control range in the art, specifically 200-720 h -1 , preferably, the acetylene space velocity in the present invention is controlled at 500 h -1 .

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention prepares a Zn-based catalyst for acetylene acetylation reaction with porous carbon modified by pyrophosphoric acid as the carrier and Zn(OAc)2 as the active component; in the preparation process of the Zn-based catalyst, through pyrophosphoric acid functionalization treatment, the metal-support interaction is significantly enhanced, promoting the uniform anchoring and dispersion of the zinc active component on the surface of the carrier. The pyrophosphoric acid functionalization treatment not only improves the adsorption and activation ability of the catalyst for CH3COOH molecules, but also moderately inhibits the adsorption intensity of C2H2. In addition, the introduction of pyrophosphoric acid groups effectively regulates the surface acid distribution of the porous carbon carrier, and rich Lewis acid sites are formed based on the electronegativity difference between phosphorus and carbon elements. These characteristics work together to inhibit the formation of carbon deposition, thus significantly improving the overall performance of the catalyst.

[0019] The Zn-based catalyst of the present invention has the characteristics of high activity and good stability when applied to the acetylene acetylation reaction. The highest activity can reach 83.2%, the selectivity of ethyl acetate reaches 94%, the activity remains above 81% after reacting for 10 h, the conversion rate of acetic acid remains above 65% after reacting for 165 h, and the selectivity of ethyl acetate remains above 90%. The above has good industrial application value.

[0020] Compared with the metal catalysts for existing acetylene acetylation reactions, the active components in the Zn-based catalyst of the present invention are in a highly dispersed state, not easy to agglomerate, and at the same time activate the acetylene and acetic acid reactants, greatly improving the catalytic activity and stability of the existing metal catalysts. Description of the Drawings

[0021] Figure 1Pyridine infrared characterization diagram of Zn-based catalyst; in the figure, a is the pyridine infrared spectrum of AC and 0.01PPiAC; b is the pyridine infrared spectrum of Zn / AC and Zn / 0.01PPiAC.

[0022] Figure 2 TEM characterization diagram of Zn-based catalyst; in the figure, a is before the reaction of Zn / AC; b is after the reaction of Zn / AC; c is before the reaction of Zn / 0.01PPiAC-800; d is after the reaction of Zn / 0.01PPiAC-800.

[0023] Figure 3 TPD curve diagram of Zn-based catalyst for reactants acetic acid and acetylene; in the figure, a uses acetic acid as the reactant; b uses acetylene as the reactant.

[0024] Figure 4 Performance of Zn-based catalyst in the acetylation reaction of acetylene; in the figure, a is the effect of different pyrolysis temperatures on the acetylation rate; b is the effect of different pyrolysis temperatures on the selectivity of vinyl acetate; c is the acetic acid conversion rate of the 165 h life test of Zn / 0.01PPiAC-800 catalyst; d is the selectivity of vinyl acetate of the 165 h life test of Zn / 0.01PPiAC-800 catalyst. Specific implementation mode

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. In the present invention, "wt.%" represents weight percentage.

[0026] In the present invention, the calculation method of the total weight of the catalyst is: m 总 =m 载体 +m 活性组分 For example: in Example 1, the calculation method of the loading amount is: m Zn / (m 载体 +m 活性组分 +)=65.38 * 0.78 / 183.48 g / (2 g + 0.78 g) = 10 wt%.

[0027] Example 1: Preparation of Zn-based catalyst (1) Preparation of pyrophosphate-modified porous carbon: Dissolve 0.07 g of pyrophosphoric acid in 40 mL of deionized water. Subsequently, add 7 g of 40-60 mesh coconut shell activated carbon and stir for 12 h, and dry at 80 °C for 18 h to obtain a dried product, denoted as 0.01PPiAC.

[0028] 0.01PPiAC was pyrolyzed at a heating rate of 5 °C / min to 800 °C for 2 h in a nitrogen atmosphere, and the pyrolyzed product was porous carbon modified with pyrophosphate, denoted as 0.01PPiAC-800.

[0029] (2) Preparation of Zn-based catalyst: 0.78 g of solid Zn(OAc)2 was dissolved in 20 mL of deionized water and stirred at room temperature for 30 min until Zn(OAc)2 was completely dissolved to obtain an aqueous solution of zinc acetate anhydrous.

[0030] 2 g of 0.01PPiAC-800 was added to the aqueous solution of zinc acetate anhydrous, and the mixture was stirred at room temperature for 12 h. After the reaction, it was dried at 80 °C for 12 h to obtain the Zn-based catalyst, denoted as Zn / 0.01PPiAC-800.

[0031] Figure 1 It is the pyridine FT-IR characterization of AC and Zn-based catalysts. In the figure, a is the pyridine FT-IR spectra of AC and 0.01PPiAC; b is the pyridine FT-IR spectra of Zn / AC and Zn / 0.01PPiAC. From Figure 1 It can be seen that the adsorption amounts of pyridine on the Lewis acid sites and total acid sites of AC and Zn-based catalysts modified with pyrophosphate increase significantly. This phenomenon is attributed to the electronegativity difference between the phosphorus atom and the carbon skeleton in the pyrophosphate group, which causes the phosphorus atom to attract electrons from the adjacent carbon atoms, thus forming abundant Lewis acid sites. It should be noted that the formation of such non-metal Lewis acid sites not only optimizes the acid distribution of the catalyst but also effectively inhibits the formation of carbon deposition during the reaction process.

[0032] Figure 2 It is the TEM comparison diagram of the catalysts Zn / AC and Zn / 0.01PPiAC-800 before and after the reaction; in the figure, (a) is before the reaction of Zn / AC; (b) is after the reaction of Zn / AC; (c) is before the reaction of Zn / 0.01PPiAC-800; (d) is after the reaction of Zn / 0.01PPiAC-800. From Figure 2 It can be seen that the pyrophosphate functionalization modification effectively inhibits the agglomeration of active components and significantly enhances the anchoring ability and dispersion degree of zinc species on the carrier surface. This modification strategy ultimately realizes the synchronous improvement of the activity and stability of the catalyst by optimizing the distribution state of active sites.

[0033] Figure 3 It is the TPD curve diagram of the catalysts Zn / AC and Zn / 0.01PPiAC-800 for reactants acetic acid and acetylene; in the figure, (a) uses acetic acid as the reactant, and (b) uses acetylene as the reactant. From Figure 3It can be seen that, compared with Zn / AC, the Zn / 0.01PPiAC-800 catalyst has a stronger TCD signal for acetic acid. It can be seen that the pyrophosphate functionalization modification significantly optimizes the adsorption characteristics of the Zn-based catalyst by regulating the electronic structure of zinc species. Specifically, the adsorption capacity of the catalyst for acetic acid molecules is significantly enhanced, while the adsorption intensity for acetylene is moderately weakened.

[0034] Example 2: Preparation of Zn-based catalyst (1)Preparation of pyrophosphate-modified porous carbon: Dissolve 0.07 g of pyrophosphoric acid in 40 mL of deionized water. Subsequently, add 7 g of coconut shell activated carbon with a particle size of 40-60 mesh and stir for 12 h, then dry at 80 °C for 18 h to obtain a dried product, denoted as 0.01PPiAC.

[0035] Heat 0.01PPiAC to 600 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and pyrolyze for 2 h. After the pyrolysis is completed, the pyrophosphate-modified porous carbon is obtained, denoted as 0.01PPiAC-600.

[0036] (2)Preparation of Zn-based catalyst: Dissolve 0.78 g of solid Zn(OAc)2 in 20 mL of deionized water, and stir at room temperature for 30 min until Zn(OAc)2 is completely dissolved to obtain an aqueous solution of zinc acetate anhydrous.

[0037] Add 2 g of 0.01PPiAC-600 to the aqueous solution of zinc acetate anhydrous, stir and react at room temperature for 12 h, and then dry at 80 °C for 12 h after the reaction to obtain the Zn-based catalyst, denoted as Zn / 0.01PPiAC-600.

[0038] Example 3: Preparation of Zn-based catalyst (1)Preparation of pyrophosphate-modified porous carbon: Dissolve 0.07 g of pyrophosphoric acid in 40 mL of deionized water. Subsequently, add 7 g of coconut shell activated carbon with a particle size of 40-60 mesh and stir for 12 h, then dry at 80 °C for 18 h to obtain a dried product, denoted as 0.01PPiAC.

[0039] Heat 0.01PPiAC to 700 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and pyrolyze for 2 h. After the pyrolysis is completed, the pyrophosphate-modified porous carbon is obtained, denoted as 0.01PPiAC-700.

[0040] (2)Preparation of Zn-based catalyst: Dissolve 0.78 g of solid Zn(OAc)₂ in 20 mL of deionized water, and stir at room temperature for 30 min until Zn(OAc)₂ is completely dissolved to obtain an aqueous solution of zinc acetate anhydrous.

[0041] Add 2 g of 0.01PPiAC-700 to the aqueous solution of zinc acetate anhydrous, stir and react at room temperature for 12 h, and dry at 80 °C for 12 h after the reaction to obtain the Zn-based catalyst, denoted as Zn / 0.01PPiAC-700.

[0042] Example 4: Preparation of Zn-based catalyst (1) Preparation of pyrophosphate-modified porous carbon: Dissolve 0.07 g of pyrophosphoric acid in 40 mL of deionized water. Subsequently, add 7 g of coconut shell activated carbon with a mesh size of 40-60 and stir for 12 h, and dry at 80 °C for 18 h to obtain a dried product, denoted as 0.01PPiAC.

[0043] Heat 0.01PPiAC to 900 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and pyrolyze for 2 h. After the pyrolysis, obtain pyrophosphate-modified porous carbon, denoted as 0.01PPiAC-900.

[0044] (2) Preparation of Zn-based catalyst: Dissolve 0.78 g of solid Zn(OAc)₂ in 20 mL of deionized water, and stir at room temperature for 30 min until Zn(OAc)₂ is completely dissolved to obtain an aqueous solution of zinc acetate anhydrous.

[0045] Add 2 g of 0.01PPiAC-900 to the aqueous solution of zinc acetate anhydrous, stir and react at room temperature for 12 h, and dry at 80 °C for 12 h after the reaction to obtain the Zn-based catalyst, denoted as Zn / 0.01PPiAC-900.

[0046] Example 5: Preparation of Zn-based catalyst (1) Preparation of pyrophosphate-modified porous carbon: Dissolve 0.07 pyrophosphoric acid in 40 mL of deionized water. Subsequently, add 7 g of coconut shell activated carbon with a mesh size of 40-60 and stir for 12 h, and dry at 80 °C for 18 h to obtain a dried product, denoted as 0.01PPiAC.

[0047] Heat 0.01PPiAC to 1000 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and pyrolyze for 2 h. After the pyrolysis, obtain pyrophosphate-modified porous carbon, denoted as 0.01PPiAC-1000.

[0048] (2)Preparation of Zn-based catalyst: Dissolve 0.78 g of solid Zn(OAc)₂ in 20 mL of deionized water, and stir at room temperature for 30 min until Zn(OAc)₂ is completely dissolved to obtain an aqueous solution of zinc acetate anhydrous.

[0049] Add 2 g of 0.01PPiAC - 1000 to the aqueous solution of zinc acetate anhydrous, stir and react at room temperature for 12 h, and dry at 80 °C for 12 h after the reaction to obtain the Zn - based catalyst denoted as Zn / 0.01PPiAC - 1000.

[0050] Example 6: Use gas chromatography to analyze the conversion rate and selectivity of the Zn - based catalysts prepared in Examples 1 - 5 and Zn / AC prepared in the comparative example. The main components of the substances measured by gas chromatography are C₄H₆O₂ (VAC), CH₃COOH, CH₃CH=CHCHO, and CH₃COCH₃. Use the normalization method to analyze and determine the percentage content of each substance in the liquid sample. The calculation methods for the conversion rate of acetic acid ( X A ) and the selectivity of vinyl acetate ( S VAC ) are as follows: Calculation method for the conversion rate of acetic acid: X A = (n₀ - n₁) / n₀ * 100%, taking the average value of 3 measurements.

[0051] Calculation method for the selectivity of vinyl acetate: S VAC =n p / (n₀ - n₁) * 100%, taking the average value of 3 measurements.

[0052] Among them, n₀ represents the amount of CH₃COOH in the raw material before the reaction; n₁ represents the amount of CH₃COOH in the collected product after the reaction, and n p represents the amount of CH₃COOH that generates VAC. Given the substances contained in the product, the internal standard method is used. The main product is VAC, and the by - products are acetaldehyde and acetone. Since there is a small amount of water in the raw material CH₃COOH, the following chemical reaction will occur: C₂H₂ + H₂O → CH₃CHO. The test results of the acetylene acetylation reaction catalyzed by each catalyst are shown in Table 1.

[0053] Table 1. Performance of acetylene acetylation reaction catalyzed by different catalysts As can be seen from Table 1, when the mass ratio of pyrophosphoric acid to activated carbon is 0.01, the pyrolysis temperature is 800 °C, and the atmosphere is N2, the catalytic activity of the zinc-based catalyst Zn / 0.01PPiAC-800 is significantly better than that of other catalysts, and the conversion rate decreases less during the 10 h reaction process. This is because the inexpensive coconut shell activated carbon is pyrolytically activated by pyrophosphoric acid at high temperature. Due to the electronegativity difference between phosphorus atoms and carbon atoms, L acid sites can be generated. Compared with the unmodified catalyst, the catalyst treated with pyrophosphoric acid functionalization still maintains excellent catalytic performance under the condition of reducing the zinc loading amount, indicating that the L acid sites effectively regulate the catalytic environment of the active sites and significantly improve the catalytic activity. The functionalization modification of the pyrophosphoric acid group effectively regulates the surface properties of the catalyst, specifically manifested as: on the one hand, weakening the adsorption strength of the zinc active center to acetylene, and on the other hand, enhancing the adsorption capacity for acetic acid molecules. At the same time, the pyrophosphoric acid modification shows multiple advantages: (1) significantly inhibiting the carbon deposition phenomenon during the reaction process; (2) effectively preventing the agglomeration of active components; (3) promoting the uniform dispersion of zinc species. These synergistic effects work together to enable the catalyst to simultaneously obtain excellent activity and stability.

[0054] In this example, the Zn / AC prepared in Comparative Example 1 was also used as a control. By investigating the effects of the zinc-based catalysts prepared at different pyrolysis temperatures in Examples 1-5 on the acetoxylation rate and the selectivity of vinyl acetate, the performance of the zinc-based catalyst for the acetylation reaction of acetylene described in the present invention was verified. The investigation results are as Figure 4 shown.

[0055] From Figure 4 a and Figure 4 b, it can be seen that after 10 h of reaction, the acetoxylation rate generally shows an upward trend with the pyrolysis temperature (600 °C - 1000 °C) of the pyrophosphoric acid-modified porous carbon support. Among them, the acetoxylation rate of the Zn / 0.01PPiAC-800 catalyst is 83.2%, and the selectivity of vinyl acetate is 94%. It can be seen that the zinc-based catalyst Zn / 0.01PPiAC-800 is significantly better than other catalysts in terms of acetoxylation rate and vinyl acetate selectivity, and it is selected for subsequent experiments.

[0056] In this example, a 165 h life test was also carried out on Zn / 0.01PPiAC-800 to investigate its effects on the acetoxylation rate and the selectivity of vinyl acetate. The investigation results are as Figure 4 c and Figure 4 d shown. It can be seen from the figure that compared with Zn / AC, Zn / 0.01PPiAC-800 still has a relatively high acetoxylation rate and vinyl acetate selectivity. The acetoxylation rate remains above 65%, and the selectivity of ethyl acetate remains above 90%.

[0057] Comparative Example 1: Preparation of Zn / AC Dissolve 0.78 g of solid Zn(OAc)₂ in 20 mL of deionized water, and stir at room temperature for 30 min until Zn(OAc)₂ is completely dissolved to obtain an aqueous solution of zinc acetate anhydrous.

[0058] Add 2 g of AC to the aqueous solution of zinc acetate anhydrous, stir and react at room temperature for 12 h, and dry at 80 °C for 12 h after the reaction to obtain a catalyst, denoted as Zn / AC.

[0059] In summary, in the present invention, a porous carbon modified with pyrophosphoric acid is used as the carrier, and Zn(OAc)₂ is used as the active component to prepare a Zn-based catalyst for the acetylation reaction of acetylene; the pyrophosphoric acid group is introduced into the Zn-based catalyst to regulate the surface properties of the catalyst, weaken the adsorption of acetylene by the zinc active sites, and at the same time enhance the adsorption capacity for acetic acid. In addition, the pyrophosphoric acid modification effectively inhibits the formation of carbon deposition and the agglomeration of active components during the reaction, enhances the dispersion of zinc species, and thus significantly improves the activity and stability of the catalyst; the preparation method of the Zn-based catalyst is simple and efficient, can be popularized in industrial applications, and has good practicability.

[0060] The above embodiments are the preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Without departing from the essence of the present invention, any obvious improvements, substitutions or modifications that those skilled in the art can make all belong to the protection scope of the present invention.

Claims

1. A Zn-based catalyst for catalyzing acetylene acetic acidification reaction, characterized in that: The Zn-based catalyst uses anhydrous zinc acetate (Zn(OAc)2) as an active component and pyrophosphate-modified porous carbon as a carrier; the loading amount of Zn atoms in the Zn-based catalyst is 9-12 wt.%.

2. The Zn-based catalyst for catalyzing acetylene acetic acidification reaction according to claim 1, characterized in that: The porous carbon includes coconut shell activated carbon.

3. The Zn-based catalyst for catalyzing acetylene acetic acidification reaction according to claim 1, characterized in that: The loading amount of Zn atoms in the Zn-based catalyst is 10 wt.%.

4. The method for preparing a Zn-based catalyst according to any one of claims 1 to 3, characterized in that: The preparation method comprises: Adding porous carbon to an aqueous solution of pyrophosphoric acid, stirring for the first reaction at room temperature, drying after the reaction, and then pyrolyzing the dried product to obtain pyrophosphoric acid-modified porous carbon; The porous carbon modified with pyrophosphate is added to the aqueous solution of anhydrous zinc acetate, and the mixture is stirred for a second reaction at room temperature. After the reaction is completed, the mixture is dried to obtain the Zn-based catalyst.

5. The preparation method according to claim 4, characterized in that: The porous carbon includes coconut shell activated carbon.

6. The preparation method according to claim 4, characterized in that: The mass ratio of pyrophosphoric acid to porous carbon is 0.007~0.05; The first stirring reaction time is 12 h.

7. The preparation method according to claim 4, characterized in that: The pyrolysis conditions are as follows: heating to 600-1000°C for 2 h under a N2 atmosphere and a flow rate of 50 mL / min; the heating rate during pyrolysis is 5°C / min.

8. The preparation method according to claim 4, characterized in that: In the aqueous solution of anhydrous zinc acetate, the dosage ratio of anhydrous zinc acetate to deionized water is 0.78 g: 20 mL; the second stirring reaction time is 12 h; In the Zn-based catalyst, the loading amount of Zn atoms is 9-12 wt.%.

9. Use of the Zn-based catalyst according to claim 1 in catalyzing acetylene acetic acidification reaction.

10. The use according to claim 9, characterized in that: The acetylene acetic acidification reaction is a gas phase reaction, and the reaction steps are: acetylene and acetic acid vapor react under the catalysis of the Zn-based catalyst described in claim 1 to generate vinyl acetate.

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