Catalyst for acetylene method vinyl acetate synthesis, preparation method and application thereof

Abstract

The application discloses a catalyst for synthesizing vinyl acetate by an acetylene method and a preparation method and application thereof. The catalyst comprises an active component and a carrier, and the active component comprises zinc acetate and a strontium-iron composite oxide. The catalyst has the characteristics of high space-time yield of a target product and low content of a byproduct benzene when used for synthesizing vinyl acetate by the acetylene method.

Description

Technical Field

[0001] This invention belongs to the field of vinyl acetate synthesis, specifically relating to a catalyst for the synthesis of vinyl acetate via acetylene synthesis, its preparation method, and its application. Background Technology

[0002] Vinyl acetate, or VAM for short, is an important organic chemical raw material, mainly used in the synthesis of polyvinyl alcohol, VAE emulsions, EVA resins, and vinylon. Currently, China's vinyl acetate production capacity is approximately 3.2 million tons per year. The main production processes for VAM are the ethylene process and the acetylene process. Among these, only a few manufacturers in China, such as Nanjing Celanese, Sinopec Yanshan Petrochemical, and Sinopec Shanghai Petrochemical, use the ethylene process; the remaining manufacturers use the acetylene process, which accounts for about 80% of the total domestic capacity.

[0003] The acetylene process uses a zinc acetate / activated carbon catalyst, which has advantages such as low cost, easy availability, and simple preparation. However, it also suffers from disadvantages such as low reactivity, short catalyst lifetime, and high impurity content in the product. To address these shortcomings, researchers worldwide have conducted extensive scientific research, achieving significant progress in catalyst activity and lifetime, effectively advancing the acetylene-based vinyl acetate production technology. However, the problem of high impurity levels in the VAM product remains unresolved, thus limiting the application of VAM produced by the acetylene process in high-value-added downstream product sectors. Among these, the high benzene content is a particularly significant constraint on its application in EVA and VAE.

[0004] CN1903435A discloses a catalyst for the synthesis of vinyl acetate and its preparation method. The catalyst uses activated carbon as a support, zinc acetate as the active component, and basic bismuth carbonate as a co-catalyst. Its catalyst activity and stability are significantly improved, while the content of butenal byproduct in the product is significantly reduced. However, this patent does not address reducing the content of the byproduct benzene. Summary of the Invention

[0005] One of the technical problems to be solved by the present invention is the high benzene content in the products of the prior art. The present invention provides a new catalyst for the synthesis of vinyl acetate by acetylene method, which has the characteristics of high space-time yield of target product and low benzene content of by-product when used for the synthesis of vinyl acetate by acetylene method.

[0006] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned catalyst.

[0007] The third technical problem to be solved by the present invention is to provide the application of the above-mentioned catalyst or the catalyst prepared by the above-mentioned method in the synthesis of vinyl acetate by acetylene method.

[0008] The first aspect of this invention provides a catalyst for the synthesis of vinyl acetate using the acetylene process. The catalyst comprises an active component and a support; the active component includes a zinc acetate and strontium-iron composite oxide.

[0009] According to the present invention, the carrier is activated carbon.

[0010] According to the present invention, the strontium-iron composite oxide is a strontium-ferrite crystal phase.

[0011] According to the present invention, the XRD pattern of the catalyst exhibits the characteristic XRD diffraction peaks of strontium ferrite; further, the XRD pattern of the catalyst has characteristic diffraction peaks with 2θ of 32.3±0.2° and / or 34.2±0.2°.

[0012] According to the present invention, the catalyst contains 40-80 g / L of zinc acetate (calculated as zinc); and / or 5-40 g / L of iron; and / or 0.5-8.0 g / L of strontium; and the support contains 380-450 g / L. The above contents refer to the mass content of zinc acetate, iron, or support per liter of catalyst.

[0013] According to the present invention, the mass ratio of iron to strontium in the catalyst is 5 to 10, preferably 7 to 9, and more preferably 7.5 to 7.8.

[0014] According to the present invention, as a non-limiting example, the content of zinc acetate in the catalyst, calculated as zinc, may be, but is not limited to, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L, 75 g / L, etc.

[0015] According to the present invention, as a non-limiting example, the iron content in the catalyst may be, but is not limited to, 15 g / L, 18 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 38 g / L, etc.

[0016] According to the present invention, as a non-limiting example, the content of strontium in the catalyst may be, but is not limited to, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, etc.

[0017] According to the present invention, the carrier is not particularly limited in geometry, but is preferably cylindrical; more preferably, the diameter of the base of the cylinder is 1.5–3.5 mm, and / or more preferably, the height of the cylinder is 3.0–5.0 mm. The specific surface area of ​​the carrier is 1000–2000 m². 2 / g.

[0018] A second aspect of the present invention provides a method for preparing the catalyst. The method includes the following steps:

[0019] The support was impregnated with an impregnation solution containing Sr and Fe sources, dried, and calcined to obtain a catalyst precursor; then zinc acetate was loaded to obtain the catalyst.

[0020] According to the present invention, preferably, the pH of the impregnation solution is 8-12. The pH of the impregnation solution can be adjusted using conventional pH adjusters, such as alkaline and / or acidic substances. The alkaline substance includes at least one selected from ammonia, ethanolamine, diethanolamine, and triethanolamine.

[0021] According to the present invention, the Sr source is an Sr salt, preferably at least one selected from nitrates and organic acid salts. Further, the Sr source includes at least one selected from strontium nitrate, strontium acetate, and strontium citrate. The Fe source is an Fe salt, preferably a ferric salt, more preferably at least one selected from nitrates and organic acid salts. The Fe source includes at least one selected from ferric nitrate, ferric citrate, and ferric ammonium citrate.

[0022] According to the present invention, the impregnation conditions are as follows: the volume ratio of impregnation liquid to carrier is (1-5):1; the impregnation temperature is 15-60°C; and the impregnation time is 6-24h.

[0023] According to the present invention, the drying is blower drying; and / or the drying temperature is 100-120°C; and / or the drying time is 2-6 hours.

[0024] According to the present invention, the calcination conditions are as follows: the calcination atmosphere is an inert atmosphere; the inert atmosphere is preferably a nitrogen atmosphere; the calcination temperature is 800-1500℃, preferably 900-1200℃; and the calcination time is 1-6 hours.

[0025] According to the present invention, the catalyst precursor is obtained by natural cooling after calcination. The cooling rate is 5-10 °C / min.

[0026] According to the present invention, the zinc acetate is loaded by impregnation. The impregnation conditions are: the volume ratio of impregnation solution to carrier is (1-5):1; the impregnation temperature is 60-90°C; and the impregnation time is 2-4 hours. After impregnation, drying can be performed. The drying conditions are: the drying temperature is 100-120°C; and / or, the drying time is 2-6 hours.

[0027] The third aspect of the present invention provides the application of the above-described catalyst or the catalyst prepared by the above-described preparation method in the synthesis of vinyl acetate using the acetylene method.

[0028] According to the present invention, in the aforementioned application, the feed gas undergoes a contact reaction in the presence of a catalyst to produce vinyl acetate.

[0029] According to the present invention, in the application, the feed gas includes acetic acid and acetylene. Preferably, the molar ratio of acetylene to acetic acid is 4 to 10, for example, but not limited to 5, 6, 7, 8, 9, etc.

[0030] According to the present invention, in the aforementioned application, the reaction conditions are: a reaction pressure of 0.1–0.5 atm; and / or a reaction temperature of 160–200°C; and / or a feed gas volume hourly space velocity of 250–350 h⁻¹. -1 .

[0031] According to the present invention, the reaction pressure is, for example, but not limited to, 0.15 atm, 0.2 atm, 0.25 atm, 0.3 atm, 0.35 atm, 0.4 atm, 0.45 atm, etc. All reaction pressures are gauge pressures. The reaction temperature is, for example, but not limited to, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, etc. The feed gas volume hourly space velocity is, for example, but not limited to, 260 h⁻¹. -1 270h -1 280h -1 290h -1 300h -1 310h -1 320h -1 330h -1 340h -1 Etc. The key technology of this invention is the catalyst, and those skilled in the art can reasonably select the specific process conditions used in the synthesis method to achieve good technical results.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. In the catalyst of the present invention, the catalyst comprises: an active component and a support; the active component comprises zinc acetate and strontium iron composite oxide; preferably, the strontium iron composite oxide is a strontium ferrite crystal phase. The catalyst has the characteristics of high space-time yield of the target product and low content of benzene as a byproduct in the synthesis of vinyl acetate by acetylene process.

[0034] 2. The preparation method of the catalyst of the present invention includes the following steps: impregnating a support with an impregnation solution containing Sr and Fe sources, drying and calcining to obtain a catalyst precursor; and then loading zinc acetate to obtain the catalyst. Furthermore, the present invention, by selecting a suitable iron-strontium ratio and rationally controlling the catalyst preparation conditions, especially the calcination temperature, significantly improves the catalytic performance of the catalyst prepared by this method, and also reduces the content of benzene, a key impurity, in vinyl acetate products.

[0035] 3. In the application of the catalyst of this invention, this catalyst can be used in the production of high-quality vinyl acetate by the acetylene process, and the produced vinyl acetate has higher purity and lower content of the key impurity benzene. Detailed Implementation

[0036] The present invention will now be described in detail with reference to specific embodiments. These embodiments are for illustrative purposes only and do not constitute any limitation thereof. The invention has been described with reference to exemplary embodiments, but it should be understood that the terms used are descriptive and explanatory, not limiting. Modifications and revisions can be made to the invention within the scope of the claims as specified herein, without departing from the scope and spirit of the invention. Although the invention described herein relates to specific methods, materials, and embodiments, it does not imply that the invention is limited to the specific examples disclosed herein; on the contrary, the invention can be extended to all other methods and applications with the same function.

[0037] In this invention, the contents of Zn, Sr and Fe in the catalysts in the examples and comparative examples were analyzed using a Thermo iCAP 6300 inductively coupled plasma atomic emission spectrometer (ICP-AES).

[0038] In this invention, in the examples and comparative examples, the crystal structures of the Sr, Fe, and Zn compounds in the catalyst product were characterized using a Bruker D8 ADVANCE X-ray diffractometer (XRD). Cu Kα was used as the diffraction source, with a tube voltage of 40 kV, a tube current of 30 mA, and a scanning range of 2θ = 10°–90°. XRD characterization revealed that the characteristic diffraction peaks 2θ of the strontium-iron composite oxide at 32.3 ± 0.2° and 34.2 ± 0.2° correspond to strontium ferrite (SrFe) and Zn, respectively. 12 O 19 The crystal planes (107) and (114) of ).

[0039] In this invention, the room temperature in each example is 20°C.

[0040] In this invention, the carrier activated carbon is cylindrical in each example; the diameter of the bottom surface of the cylinder is 2.5 mm; and / or the height of the cylinder is 4.0 mm.

[0041] In this invention, gas chromatography was used to analyze the content of each component in the reaction product, the space-time yield of the catalyst was calculated, and GC-MS was used to analyze the benzene content in the reaction product.

[0042] In this invention, the benzene content ppbw is by weight.

[0043]

Example 1

[0044] (I) Catalyst Preparation

[0045] (1) Take 100 mL of a mixed aqueous solution of strontium nitrate and ferric nitrate (the concentration of iron is 26.5 g / L and the concentration of strontium is 3.5 g / L, that is, the mass ratio of iron to strontium is 7.57), and adjust the pH value to 10 with ammonia water with a weight concentration of 25% to obtain Sr-Fe impregnation solution.

[0046] (2) 100 mL of activated carbon was mixed with Sr-Fe impregnation solution, allowed to stand at room temperature for 12 h, dried at 120 °C for 6 h, calcined at 1000 °C for 2 h under nitrogen atmosphere, and then naturally cooled to obtain the catalyst precursor; the natural cooling rate was 5 °C / min.

[0047] (3) Mix 100 mL of catalyst precursor with 100 mL of zinc acetate aqueous solution (60 g / L based on zinc), impregnate at 80 °C for 4 h, and dry at 120 °C for 3 h to obtain the catalyst.

[0048] The catalyst contains 60.0 g / L zinc acetate, 26.5 g / L Fe, and 3.5 g / L strontium. The mass ratio of Fe to Sr is 7.57. The support content is 400 g / L. This catalyst exhibits characteristic XRD diffraction peaks at 2θ of 32.3° and 34.2°.

[0049] The preparation conditions for the catalyst are listed in Table 1.

[0050] (II) Catalyst Performance Evaluation

[0051] The evaluation was conducted using a fixed-bed reactor, under the following conditions:

[0052] Catalyst loading volume: 40 mL;

[0053] Raw material gas composition (in molar ratio): Acetylene: Acetic acid = 5:1;

[0054] Feed gas volume hourly space velocity: 300 h⁻¹ -1 ;

[0055] Reaction pressure: 0.3 atm;

[0056] Reaction temperature: 180℃;

[0057] Reaction time: 100h.

[0058] The main reaction conditions and reaction results are listed in Table 2.

[0059]

Example 2

[0060] (I) Catalyst Preparation

[0061] (1) Take 100 mL of a mixed aqueous solution of strontium citrate and iron citrate (the concentration of iron is 26.5 g / L and the concentration of strontium is 3.5 g / L, that is, the mass ratio of iron to strontium is 7.57), and adjust the pH value to 10 with ammonia water with a weight concentration of 25% to obtain Sr-Fe impregnation solution.

[0062] (2) 100 mL of activated carbon was mixed with Sr-Fe impregnation solution, allowed to stand at room temperature for 12 h, dried at 120 °C for 6 h, calcined at 1000 °C for 2 h under nitrogen atmosphere, and then naturally cooled to obtain the catalyst precursor; the natural cooling rate was 5 °C / min.

[0063] (3) Mix 100 mL of catalyst precursor with 100 mL of zinc acetate aqueous solution (60 g / L based on zinc), impregnate at 80 °C for 4 h, and dry at 120 °C for 3 h to obtain the catalyst.

[0064] The catalyst contains 60.0 g / L zinc acetate, 26.5 g / L Fe, and 3.5 g / L strontium. The mass ratio of Fe to Sr is 7.57. The support content is 400 g / L. This catalyst exhibits characteristic XRD diffraction peaks at 2θ of 32.4° and 34.1°.

[0065] The preparation conditions for the catalyst are listed in Table 1.

[0066] (II) Catalyst Performance Evaluation

[0067] The evaluation was conducted using a fixed-bed reactor, under the following conditions:

[0068] Catalyst loading volume: 40 mL;

[0069] Raw material gas composition (in molar ratio): Acetylene: Acetic acid = 5:1;

[0070] Feed gas volume hourly space velocity: 300 h⁻¹ -1 ;

[0071] Reaction pressure: 0.3 atm;

[0072] Reaction temperature: 180℃;

[0073] Reaction time: 100h.

[0074] The main reaction conditions and reaction results are listed in Table 2.

[0075]

Example 3

[0076] (I) Catalyst Preparation

[0077] (1) Take 100 mL of a mixed aqueous solution of strontium nitrate and ferric nitrate (the concentration of iron is 26.5 g / L and the concentration of strontium is 2.65 g / L, that is, the mass ratio of iron to strontium is 10.0), and adjust the pH value to 10 with ammonia water with a weight concentration of 25% to obtain Sr-Fe impregnation solution.

[0078] (2) 100 mL of activated carbon was mixed with Sr-Fe impregnation solution, allowed to stand at room temperature for 12 h, dried at 120 °C for 6 h, calcined at 1000 °C for 2 h under nitrogen atmosphere, and then naturally cooled to obtain the catalyst precursor; the natural cooling rate was 5 °C / min.

[0079] (3) Mix 100 mL of catalyst precursor with 100 mL of zinc acetate aqueous solution (60 g / L based on zinc), impregnate at 80 °C for 4 h, and dry at 120 °C for 3 h to obtain the catalyst.

[0080] The catalyst contains 60.0 g / L zinc acetate, 26.5 g / L Fe, and 2.65 g / L strontium. The mass ratio of Fe to Sr is 10.0. The support content is 400 g / L. This catalyst exhibits characteristic XRD diffraction peaks at 2θ of 32.5° and 34.4°.

[0081] The preparation conditions for the catalyst are listed in Table 1.

[0082] (II) Catalyst Performance Evaluation

[0083] The evaluation was conducted using a fixed-bed reactor, under the following conditions:

[0084] Catalyst loading volume: 40 mL;

[0085] Raw material gas composition (in molar ratio): Acetylene: Acetic acid = 5:1;

[0086] Feed gas volume hourly space velocity: 300 h⁻¹ -1 ;

[0087] Reaction pressure: 0.3 atm;

[0088] Reaction temperature: 180℃;

[0089] Reaction time: 100h.

[0090] The main reaction conditions and reaction results are listed in Table 2.

[0091]

Example 4

[0092] (I) Catalyst Preparation

[0093] (1) Take 100 mL of a mixed aqueous solution of strontium nitrate and ferric nitrate (the concentration of iron is 21.0 g / L and the concentration of strontium is 3.5 g / L, that is, the mass ratio of iron to strontium is 6.0), and adjust the pH value to 10 with ammonia water with a weight concentration of 25% to obtain Sr-Fe impregnation solution.

[0094] (2) 100 mL of activated carbon was mixed with Sr-Fe impregnation solution, allowed to stand at room temperature for 12 h, dried at 120 °C for 6 h, calcined at 1000 °C for 2 h under nitrogen atmosphere, and then naturally cooled to obtain the catalyst precursor; the natural cooling rate was 5 °C / min.

[0095] (3) Mix 100 mL of catalyst precursor with 100 mL of zinc acetate aqueous solution (60 g / L based on zinc), impregnate at 80 °C for 4 h, and dry at 120 °C for 3 h to obtain the catalyst.

[0096] The catalyst contains 60.0 g / L zinc acetate, 21.0 g / L Fe, and 3.5 g / L strontium. The mass ratio of Fe to Sr is 6.0. The support content is 400 g / L. This catalyst exhibits characteristic XRD diffraction peaks at 2θ of 32.3° and 34.0°.

[0097] The preparation conditions for the catalyst are listed in Table 1.

[0098] (II) Catalyst Performance Evaluation

[0099] The evaluation was conducted using a fixed-bed reactor, under the following conditions:

[0100] Catalyst loading volume: 40 mL;

[0101] Raw material gas composition (in molar ratio): Acetylene: Acetic acid = 5:1;

[0102] Feed gas volume hourly space velocity: 300 h⁻¹ -1 ;

[0103] Reaction pressure: 0.3 atm;

[0104] Reaction temperature: 180℃;

[0105] Reaction time: 100h.

[0106] The main reaction conditions and reaction results are listed in Table 2.

[0107]

Example 5

[0108] (I) Catalyst Preparation

[0109] (1) Take 100 mL of a mixed aqueous solution of strontium nitrate and ferric nitrate (the concentration of iron is 26.5 g / L and the concentration of strontium is 3.5 g / L, that is, the mass ratio of iron to strontium is 7.57), and adjust the pH value to 10 with ammonia water with a weight concentration of 25% to obtain Sr-Fe impregnation solution.

[0110] (2) 100 mL of activated carbon was mixed with Sr-Fe impregnation solution, allowed to stand at room temperature for 12 h, dried at 120 °C for 6 h, calcined at 1200 °C for 2 h under nitrogen atmosphere, and then naturally cooled to obtain the catalyst precursor; the natural cooling rate was 5 °C / min.

[0111] (3) Mix 100 mL of catalyst precursor with 100 mL of zinc acetate aqueous solution (80 g / L based on zinc), impregnate at 80 °C for 4 h, and dry at 120 °C for 3 h to obtain the catalyst.

[0112] The catalyst contains 80.0 g / L zinc acetate, 26.5 g / L Fe, and 3.5 g / L strontium. The mass ratio of Fe to Sr is 7.57. The support content is 400 g / L. This catalyst exhibits characteristic XRD diffraction peaks at 2θ of 32.1° and 34.2°. The preparation conditions of the catalyst are listed in Table 1.

[0113] (II) Catalyst Performance Evaluation

[0114] The evaluation was conducted using a fixed-bed reactor, under the following conditions:

[0115] Catalyst loading volume: 40 mL;

[0116] Raw material gas composition (in molar ratio): Acetylene: Acetic acid = 4:1;

[0117] Feed gas volume hourly space velocity: 250 h⁻¹ -1 ;

[0118] Reaction pressure: 0.1 atm;

[0119] Reaction temperature: 160℃;

[0120] Reaction time: 100h.

[0121] The main reaction conditions and reaction results are listed in Table 2.

[0122]

Example 6

[0123] (I) Catalyst Preparation

[0124] (1) Take 100 mL of a mixed aqueous solution of strontium nitrate and ferric nitrate (the concentration of iron is 26.5 g / L and the concentration of strontium is 3.5 g / L, that is, the mass ratio of iron to strontium is 7.57), and adjust the pH value to 10 with ammonia water with a weight concentration of 25% to obtain Sr-Fe impregnation solution.

[0125] (2) 100 mL of activated carbon was mixed with Sr-Fe impregnation solution, allowed to stand at room temperature for 12 h, dried at 120 °C for 6 h, calcined at 900 °C for 2 h under nitrogen atmosphere, and then naturally cooled to obtain the catalyst precursor; the natural cooling rate was 5 °C / min.

[0126] (3) Mix 100 mL of catalyst precursor with 100 mL of zinc acetate aqueous solution (40 g / L based on zinc), impregnate at 80 °C for 4 h, and dry at 120 °C for 3 h to obtain the catalyst.

[0127] The catalyst contains 40.0 g / L zinc acetate, 26.5 g / L Fe, and 3.5 g / L strontium. The mass ratio of Fe to Sr is 7.57. The support content is 400 g / L. This catalyst exhibits characteristic XRD diffraction peaks at 2θ of 32.2° and 34.1°.

[0128] The preparation conditions for the catalyst are listed in Table 1.

[0129] (II) Catalyst Performance Evaluation

[0130] The evaluation was conducted using a fixed-bed reactor, under the following conditions:

[0131] Catalyst loading volume: 40 mL;

[0132] Raw material gas composition (in molar ratio): Acetylene: Acetic acid = 10:1;

[0133] Feed gas volume hourly space velocity: 350 h⁻¹ -1 ;

[0134] Reaction pressure: 0.5 atm;

[0135] Reaction temperature: 200℃;

[0136] Reaction time: 100h.

[0137] The main reaction conditions and reaction results are listed in Table 2.

[0138]

Comparative Example 1

[0139] (I) Catalyst Preparation

[0140] 100 mL of activated carbon was impregnated in 100 mL of zinc acetate solution (60 g / L based on zinc) at 80 °C for 4 h, and then dried at 120 °C for 3 h to obtain the catalyst product. The catalyst product contained 60.0 g / L of zinc acetate and 400 g / L of support.

[0141] The preparation conditions for the catalyst are listed in Table 1.

[0142] (II) Catalyst Performance Evaluation

[0143] The evaluation was conducted using a fixed-bed reactor, under the following conditions:

[0144] Catalyst loading volume: 40 mL;

[0145] Raw material gas composition (in molar ratio): Acetylene: Acetic acid = 5:1;

[0146] Feed gas volume hourly space velocity: 300 h⁻¹ -1 ;

[0147] Reaction pressure: 0.3 atm;

[0148] Reaction temperature: 180℃;

[0149] Reaction time: 100h.

[0150] The main reaction conditions and reaction results are listed in Table 2.

[0151] [Comparative Example 2]

[0152] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 uses only strontium nitrate, specifically:

[0153] (I) Catalyst Preparation

[0154] (1) Take 100 mL of strontium nitrate aqueous solution (the concentration of strontium element is 30 g / L), and adjust the pH value to 10 with ammonia water with a weight concentration of 25% to obtain Sr impregnation solution;

[0155] (2) 100 mL of activated carbon was mixed with Sr impregnation solution, allowed to stand at room temperature for 12 h, dried at 120 °C for 6 h, calcined at 1000 °C for 2 h under nitrogen atmosphere, and then naturally cooled to obtain the catalyst precursor; the natural cooling rate was 5 °C / min.

[0156] (3) Mix 100 mL of catalyst precursor with 100 mL of zinc acetate aqueous solution (60 g / L based on zinc), impregnate at 80 °C for 4 h, and dry at 120 °C for 3 h to obtain the catalyst product. The catalyst product contains 60.0 g / L of zinc acetate and 30 g / L of Sr.

[0157] The preparation conditions for the catalyst are listed in Table 1.

[0158] (II) Catalyst Performance Evaluation

[0159] The evaluation was conducted using a fixed-bed reactor, under the following conditions:

[0160] Catalyst loading volume: 40 mL;

[0161] Raw material gas composition (in molar ratio): Acetylene: Acetic acid = 5:1;

[0162] Feed gas volume hourly space velocity: 300 h⁻¹ -1 ;

[0163] Reaction pressure: 0.3 atm;

[0164] Reaction temperature: 180℃;

[0165] Reaction time: 100h.

[0166] The main reaction conditions and reaction results are listed in Table 2.

[0167] [Comparative Example 3]

[0168] The difference from Example 1 is that Comparative Example 3 uses only ferric nitrate, specifically:

[0169] (I) Catalyst Preparation

[0170] (1) Take 100 mL of ferric nitrate aqueous solution (the concentration of iron element is 30 g / L), and adjust the pH value to 10 with ammonia water with a weight concentration of 25% to obtain Fe impregnation solution;

[0171] (2) 100 mL of activated carbon was mixed with Fe impregnation solution, allowed to stand at room temperature for 12 h, dried at 120 °C for 6 h, calcined at 1000 °C for 2 h under nitrogen atmosphere, and then naturally cooled to obtain catalyst precursor.

[0172] (3) Mix 100 mL of catalyst precursor with 100 mL of zinc acetate aqueous solution (60 g / L based on zinc), impregnate at 80 °C for 4 h, and dry at 120 °C for 3 h to obtain the catalyst product. The catalyst product contains 60.0 g / L of zinc acetate and 30 g / L of Fe.

[0173] The preparation conditions for the catalyst are listed in Table 1.

[0174] (II) Catalyst Performance Evaluation

[0175] The evaluation was conducted using a fixed-bed reactor, under the following conditions:

[0176] Catalyst loading volume: 40 mL;

[0177] Raw material gas composition (in molar ratio): Acetylene: Acetic acid = 5:1;

[0178] Feed gas volume hourly space velocity: 300 h⁻¹ -1 ;

[0179] Reaction pressure: 0.3 atm;

[0180] Reaction temperature: 180℃;

[0181] Reaction time: 100h.

[0182] The main reaction conditions and reaction results are listed in Table 2.

[0183] Comparative Example 4

[0184] Except for the calcination temperature of 600℃ during the preparation of the catalyst precursor, the other process conditions are the same as in Example 1, specifically:

[0185] (I) Catalyst Preparation

[0186] (1) Take 100 mL of a mixed aqueous solution of strontium nitrate and ferric nitrate (the concentration of iron is 26.5 / L and the concentration of strontium is 3.5 / L, that is, the mass ratio of iron to strontium is 7.57), and adjust the pH value to 10 with ammonia water with a weight concentration of 25% to obtain Sr-Fe impregnation solution.

[0187] (2) 100 mL of activated carbon was mixed with Sr-Fe impregnation solution, allowed to stand at room temperature for 12 h, dried at 120 °C for 6 h, calcined at 600 °C for 2 h under nitrogen atmosphere, and then naturally cooled to obtain the catalyst precursor; the natural cooling rate was 5 °C / min.

[0188] (3) Mix 100 mL of catalyst precursor with 100 mL of zinc acetate aqueous solution (60 g / L based on zinc), impregnate at 80 °C for 4 h, and dry at 120 °C for 3 h to obtain the finished catalyst. The finished catalyst contains 60.0 g / L of zinc acetate, 26.5 g / L of Fe, and 3.5 g / L of strontium. The mass ratio of Fe to Sr is 7.57.

[0189] (II) Catalyst Performance Evaluation

[0190] The evaluation was conducted using a fixed-bed reactor, under the following conditions:

[0191] Catalyst loading volume: 40 mL;

[0192] Raw material gas composition (in molar ratio): Acetylene: Acetic acid = 5:1;

[0193] Feed gas volume hourly space velocity: 300 h⁻¹ -1 ;

[0194] Reaction pressure: 0.3 atm;

[0195] Reaction temperature: 180℃;

[0196] Reaction time: 100h.

[0197] The main reaction conditions and reaction results are listed in Table 2.

[0198] The catalyst of Example 1 has XRD characteristic diffraction peaks with 2θ of 32.3° and 34.2°, while the catalysts of Comparative Examples 1 to 4 do not have these XRD characteristic diffraction peaks.

[0199] Table 1

[0200]

[0201]

[0202] Table 2

[0203]

[0204] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A catalyst for the synthesis of vinyl acetate via the acetylene process, characterized in that, The catalyst comprises: an active component and a support; the active component comprises zinc acetate and strontium iron composite oxide; the strontium iron composite oxide is a strontium ferrite crystal phase; The zinc acetate content, calculated as zinc, is 40~80 g / L; the iron content is 5~40 g / L; and the strontium content is 0.5~8.0 g / L. The XRD pattern of the catalyst has characteristic diffraction peaks with 2θ values ​​of 32.3±0.2° and 34.2±0.2°.

2. The catalyst according to claim 1, characterized in that, The carrier content is 380~450g / L.

3. The catalyst according to claim 1, characterized in that, The mass ratio of iron to strontium is 5 to 10.

4. The catalyst according to claim 1, characterized in that, The mass ratio of iron to strontium is 7 to 9.

5. The catalyst according to claim 1, characterized in that, The mass ratio of iron to strontium is 7.5 to 7.

8.

6. A method for preparing the catalyst according to any one of claims 1 to 5, comprising the following steps: The support was impregnated with an impregnation solution containing Sr and Fe sources, dried, and calcined to obtain a catalyst precursor; then zinc acetate was loaded to obtain the catalyst. The roasting temperature is 800~1500℃.

7. The preparation method according to claim 6, characterized in that, The calcination conditions are as follows: the calcination atmosphere is an inert atmosphere; and / or, the calcination temperature is 900~1200℃; and / or, the calcination time is 1~6 h.

8. The preparation method according to claim 7, characterized in that, The inert atmosphere is nitrogen.

9. The preparation method according to claim 6, characterized in that, The pH of the impregnation solution is 8-12.

10. The preparation method according to claim 6, characterized in that, The Sr source is an Sr salt; and / or, the Fe source is an Fe salt.

11. The preparation method according to claim 6, characterized in that, The Sr source is at least one of nitrate and organic acid salt; and / or, the Fe source is a ferric salt.

12. The preparation method according to claim 6, characterized in that, The Sr source includes at least one of strontium nitrate, strontium acetate, and strontium citrate; and / or, the Fe source is at least one of nitrate and organic acid salt.

13. The preparation method according to claim 12, characterized in that, The Fe source includes at least one of ferric nitrate, ferric citrate, and ammonium ferric citrate.

14. The application of the catalyst according to any one of claims 1 to 5 or the catalyst prepared by any one of claims 6 to 13 in the synthesis of vinyl acetate using the acetylene method.

15. The application according to claim 14, characterized in that, The raw materials include acetic acid and acetylene; And / or, the reaction conditions for the application are: a reaction pressure of 0.1~0.5 atm; and / or, a reaction temperature of 160~200℃; and / or, a feed gas volume hourly space velocity of 250~350 h⁻¹. -1 .

16. The application according to claim 15, characterized in that, In the feed gas, the molar ratio of acetylene to acetic acid is 4~10.

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