Vinyl acetate catalyst as well as preparation method and application thereof

Abstract

The invention discloses a catalyst for synthesizing vinyl acetate. The catalyst comprises a carrier, and Pd, Au, Cu and alkali metal acetate which are loaded on the carrier. The vinyl acetate catalyst has the beneficial effects that by regulating and controlling the mass ratio of Au to Cu contained in the catalyst, the catalyst has higher activity and selectivity, and the selectivity of the catalyst is higher than that of a catalyst independently containing Au and Cu.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a vinyl acetate catalyst and a preparation method and application thereof. Background Art

[0002] Vinyl acetate is an important chemical raw material, widely used in the manufacture of polyvinyl alcohol, vinyl copolymer resins, adhesives, coatings, textile processing, paper coatings, etc. There are two main production process routes for vinyl acetate: the ethylene process and the acetylene process. The ethylene process occupies a dominant position due to its good processability and economy. The vinyl acetate production capacity using this process accounts for 82% of the total production capacity. The United States completed the conversion to the ethylene process in 1983. At present, most countries increase the production of vinyl acetate by renovating and expanding the original equipment and replacing the catalyst. The development trend of the ethylene process can be summarized in several aspects: (1) The scale of production equipment tends to be large-scale. For example, the scale of production equipment of USI Company in the early 1970s was 136,000-159,000 tons / year, and the scale of equipment reached 360,000 tons / year in 1990. There is also the expansion of the VAC equipment of Hoechst Company mentioned above; (2) Although the VAC process of the ethylene process is relatively mature, it is still being improved to reduce unit consumption and energy consumption; the most advanced ethylene process is Celanese's Vantage process.

[0003] At present, the industrial synthesis of VAc from ethylene by gas phase method mainly uses palladium-gold / potassium acetate / silicon dioxide as catalyst, and the palladium site on the catalyst surface is the main active site. During the reaction process, ethylene, oxygen and acetic acid are used as raw materials, and the gas phase catalytic reaction is used to produce vinyl acetate, water and carbon dioxide as a byproduct. The temperature of the reactor shell side of the reaction can be about 100-180°C, the reaction pressure is about 0.5-1.0MPa, and the gas volume space velocity is about 500-3000hr -1 .

[0004] At present, the raw materials used in the industrial synthesis of vinyl acetate by ethylene process are mainly oxygen, ethylene, acetic acid and some nitrogen, such as the patent CN101391215A of Saudi Basic Industries Corporation. The selectivity of the catalysts in these methods is low. Therefore, in order to solve the above problem, we have developed a new type of vinyl acetate catalyst to effectively solve the problem of low catalyst selectivity. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a catalyst for synthesizing vinyl acetate with higher activity and stronger selectivity, and a preparation method and application thereof.

[0006] A first aspect of the present invention provides a catalyst for synthesizing vinyl acetate, comprising a carrier, and Pd, Au, Cu and alkali metal acetate supported on the carrier.

[0007] According to some embodiments of the catalyst of the present invention, in the catalyst, the mass ratio is Au:Cu=(50-2):1 (for example: 50:1, 25:1, 20:1, 10:1, 5:1, 3:1, 2:1), preferably, Au:Cu=(30-5):1.

[0008] According to some embodiments of the catalyst of the present invention, in the catalyst, by mass ratio, Pd:(Au+Cu)=1:(0.11-1.1), for example: 1:0.11, 1:0.15, 1:0.30, 1:0.6, 1:0.88, 1:0.90, 1:1.0, 1:1.1, preferably, Pd:(Au+Cu)=1:(0.265-0.5).

[0009] According to some embodiments of the catalyst of the present invention, the mass ratio of Pd:Au:Cu in the catalyst is 1:(0.1-1.0):(0.01-0.1), (for example: 1:0.1:0.01, 1:0.2:0.05, 1:0.5:0.06, 1:0.8:0.02, 1:1.0:0.1).

[0010] According to some embodiments of the catalyst of the present invention, Pd:Au:Cu=1:(0.2-0.8):(0.015-0.08).

[0011] According to some embodiments of the catalyst of the present invention, in the catalyst, the mass ratio is Pd:Au:Cu=1:(0.25-0.45):(0.015-0.05).

[0012] According to some embodiments of the catalyst of the present invention, the alkali metal acetate is potassium acetate.

[0013] According to some embodiments of the catalyst of the present invention, the carrier is selected from silica and / or alumina.

[0014] According to some embodiments of the catalyst of the present invention, the content of Pd in ​​the catalyst is 1-10 g / L (for example: 1 g / L, 2 g / L, 4 g / L, 5 g / L, 7 g / L, 9 g / L, 10 g / L).

[0015] According to some embodiments of the catalyst of the present invention, the content of alkali metal acetate in the catalyst is 10-100 g / L (for example: 10 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 50 g / L, 58 g / L, 65 g / L, 70 g / L, 80 g / L, 100 g / L), preferably 20-40 g / L.

[0016] A second aspect of the present invention provides a method for preparing a catalyst for synthesizing vinyl acetate, comprising the following steps:

[0017] (a) immersing a catalyst support in a solution containing palladium, gold and copper to obtain a catalyst precursor I;

[0018] (b) contacting the catalyst precursor I with a basic compound solution to obtain a catalyst precursor II;

[0019] (c) reducing the metal ions in the catalyst precursor II to zero valence to obtain the catalyst precursor III;

[0020] (d) washing the catalyst precursor III with water and drying it to obtain a catalyst precursor IV;

[0021] (e) contacting the catalyst precursor IV with an alkali metal acetate to obtain a finished catalyst.

[0022] According to some embodiments of the preparation method of the present invention, in step (a), the mass ratio of gold element to copper element in the solution is (50-2):1, preferably (30-5):1.

[0023] According to some embodiments of the preparation method of the present invention, in the catalyst, the mass ratio is Pd:(Au+Cu)=1:(0.11-1.1).

[0024] According to some embodiments of the preparation method of the present invention, the palladium element is derived from chloropalladic acid and / or palladium nitrate hydrate.

[0025] According to some embodiments of the preparation method of the present invention, the gold element is derived from chloroauric acid and / or gold chloride trihydrate.

[0026] According to some embodiments of the preparation method of the present invention, the copper element comes from cupric chloride and / or cuprous chloride.

[0027] According to some embodiments of the preparation method of the present invention, the alkali metal acetate is selected from potassium acetate and / or sodium acetate.

[0028] According to some embodiments of the preparation method of the present invention, the alkaline compound is selected from sodium silicate aqueous solution and / or barium hydroxide aqueous solution.

[0029] The third aspect of the present invention provides a method for synthesizing vinyl acetate, comprising reacting a raw gas comprising oxygen, ethylene, nitrogen and acetic acid in the presence of the catalyst described in the first aspect of the present invention or the catalyst obtained by the preparation method described in the second aspect of the present invention to obtain vinyl acetate.

[0030] According to some embodiments of the synthesis method of the present invention, the raw gas composition is oxygen: ethylene: nitrogen: acetic acid = 1: (5-7): (4-8): (1-2) in molar ratio (for example: 1:5:4:1, 1:6:4:1, 1:7:6:2, 1:7:8:2).

[0031] According to some embodiments of the synthesis method of the present invention, the raw gas composition, in terms of molar ratio, is oxygen:ethylene:nitrogen:acetic acid=1:(5-6):(5-7):(1-2).

[0032] According to some embodiments of the synthesis method of the present invention, the reaction pressure is 0.5-0.9 MPa (0.5 MPa, 0.6 MPa, 0.68 MPa, 0.72 MPa, 0.85 MPa, 0.9 MPa).

[0033] According to some embodiments of the synthesis method of the present invention, the reaction pressure is 0.6-0.8 MPa (0.6 MPa, 0.62 MPa, 0.68 MPa, 0.72 MPa, 0.80 MPa).

[0034] According to some embodiments of the synthesis method of the present invention, the reaction temperature is 130-200°C (130°C, 145°C, 150°C, 158°C, 160°C, 168°C, 170°C, 176°C, 180°C, 185°C, 190°C, 200°C).

[0035] According to some embodiments of the synthesis method of the present invention, the reaction temperature is 150-180°C.

[0036] According to some embodiments of the synthesis method of the present invention, the volume space velocity of the raw gas is 1600-3000 hr -1 .

[0037] According to some embodiments of the synthesis method of the present invention, the volume space velocity of the raw gas is 2000-2500 hr -1 .

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: the vinyl acetate catalyst of the present invention has higher activity and selectivity by regulating the mass ratio of Au and Cu contained in the catalyst, and its selectivity is higher than that of catalysts containing Au alone or Cu alone. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to constitute any limitation of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present disclosure. Such structures and technologies are also described in many publications.

[0040] Example 1

[0041] 1. Catalyst preparation

[0042] (a) Take 1100 ml of spherical silica carrier (diameter 5 mm, specific surface area 175 m 2 / g, pore volume is 0.8cm 3 / g) was immersed in a mixed aqueous solution of chloropalladic acid, chloroauric acid and cupric chloride, and the solid-liquid volume ratio was calculated to be 1:1.2, wherein the content of palladium in the solution used was 1.55 g / L, the content of gold was 0.698 g / L, and the content of copper was 0.078 g / L to prepare a catalyst precursor I;

[0043] (b) adding 100 ml of sodium silicate aqueous solution (27.5 g of Na2SiO3·9H2O is prepared into 100 ml of aqueous solution), mixing well and letting stand for 24 hours, and then drying at 80°C for 8 hours to obtain catalyst precursor II;

[0044] (c) adding 60 g of 85% wt hydrazine hydrate for reduction, standing for 4 hours, then washing with deionized water, and drying at 100° C. for 6 hours to obtain catalyst precursor III;

[0045] (d) washing the catalyst precursor III with water for 12 hours, and then drying it at 80° C. for 6 hours to obtain a catalyst precursor IV;

[0046] (e) The catalyst precursor IV was impregnated with an aqueous solution of potassium acetate and dried at 80° C. for 2 h to obtain a finished catalyst, wherein the potassium acetate content in the catalyst was 30 g / L.

[0047] 2. Catalyst evaluation

[0048] The fixed bed reactor was used for evaluation, and the specific conditions were:

[0049] Catalyst filling volume: 40ml;

[0050] The composition of the reaction raw materials (by molar ratio): oxygen: ethylene: nitrogen: acetic acid = 1: 6.8: 7.2: 1.7;

[0051] Reaction raw material feed volume space velocity: 2000hr-1;

[0052] Reaction pressure: 0.7MPa;

[0053] Reaction temperature: 135°C;

[0054] Reaction time: 100hr;

[0055] The content of each component in the reaction product was analyzed by gas chromatography, and then the space-time yield and ethylene selectivity of the catalyst were calculated. The results are shown in Table 2.

[0056] Example 2

[0057] 1. Catalyst preparation

[0058] (a) Take 1100 ml of spherical silica carrier (diameter 5 mm, specific surface area 175 m 2 / g, pore volume is 0.8cm 3 / g) was immersed in a mixed aqueous solution of chloropalladic acid, chloroauric acid and cupric chloride, and the solid-liquid volume ratio was calculated as 1:1.2, wherein the content of palladium in the solution used was 1.55 g / L, the content of gold was 0.388 g / L, and the content of copper was 0.023 g / L to prepare a catalyst precursor I;

[0059] (b) adding 100 ml of sodium silicate aqueous solution (27.5 g of Na2SiO3·9H2O is prepared into 100 ml of aqueous solution), mixing well and letting stand for 24 hours, and then drying at 80°C for 8 hours to obtain catalyst precursor II;

[0060] (c) adding 60 g of 85% wt hydrazine hydrate for reduction, standing for 4 hours, then washing with deionized water, and drying at 100° C. for 6 hours to obtain catalyst precursor III;

[0061] (d) washing the catalyst precursor III with water for 12 hours, and then drying at 80° C. for 6 hours to obtain a catalyst precursor IV;

[0062] (e) The catalyst precursor IV was impregnated with an aqueous solution of potassium acetate and dried at 80° C. for 2 h to obtain a finished catalyst, wherein the potassium acetate content in the catalyst was 30 g / L.

[0063] 2. Catalyst evaluation

[0064] The catalyst evaluation method was the same as in Example 1. The results are shown in Table 2.

[0065] Example 3

[0066] 1. Catalyst preparation

[0067] (a) Take 1100 ml of spherical silica carrier (diameter 5 mm, specific surface area 175 m2 / g, pore volume is 0.8cm 3 / g) was immersed in a mixed aqueous solution of chloropalladic acid, chloroauric acid and cupric chloride, and the solid-liquid volume ratio was calculated as 1:1.2, wherein the content of palladium in the solution used was 1.55 g / L, the content of gold was 0.543 g / L, and the content of copper was 0.039 g / L to prepare a catalyst precursor I;

[0068] (b) adding 100 ml of sodium silicate aqueous solution (27.5 g of Na2SiO3·9H2O is prepared into 100 ml of aqueous solution), mixing well and letting stand for 24 hours, and then drying at 80°C for 8 hours to obtain catalyst precursor II;

[0069] (c) adding 60 g of 85% wt hydrazine hydrate for reduction, standing for 4 hours, then washing with deionized water, and drying at 100° C. for 6 hours to obtain catalyst precursor III;

[0070] (d) washing the catalyst precursor III with water for 12 hours, and then drying at 80° C. for 6 hours to obtain a catalyst precursor IV;

[0071] (e) The catalyst precursor IV was impregnated with an aqueous solution of potassium acetate and dried at 80° C. for 2 h to obtain a finished catalyst, wherein the potassium acetate content in the catalyst was 30 g / L.

[0072] 2. Catalyst evaluation

[0073] The catalyst evaluation method was the same as in Example 1. The results are shown in Table 2.

[0074] Example 4

[0075] 1. Catalyst preparation

[0076] (a) Take 1100 ml of spherical silica carrier (diameter 5 mm, specific surface area 175 m 2 / g, pore volume is 0.8cm 3 / g) was immersed in a mixed aqueous solution of chloropalladic acid, chloroauric acid and cupric chloride, and the solid-liquid volume ratio was calculated as 1:1.2, wherein the content of palladium in the solution used was 1.55 g / L, the content of gold was 0.155 g / L, and the content of copper was 0.016 g / L to prepare a catalyst precursor I;

[0077] (b) adding 100 ml of sodium silicate aqueous solution (27.5 g of Na2SiO3·9H2O is prepared into 100 ml of aqueous solution), mixing well and letting stand for 24 hours, and then drying at 80°C for 8 hours to obtain catalyst precursor II;

[0078] (c) adding 60 g of 85% wt hydrazine hydrate for reduction, standing for 4 hours, then washing with deionized water, and drying at 100° C. for 6 hours to obtain catalyst precursor III;

[0079] (d) washing the catalyst precursor III with water for 12 hours, and then drying at 80° C. for 6 hours to obtain a catalyst precursor IV;

[0080] (e) The catalyst precursor IV was impregnated with an aqueous solution of potassium acetate and dried at 80° C. for 2 h to obtain a finished catalyst, wherein the potassium acetate content in the catalyst was 30 g / L.

[0081] 2. Catalyst evaluation

[0082] The catalyst evaluation method was the same as in Example 1. The results are shown in Table 2.

[0083] Example 5

[0084] 1. Catalyst preparation

[0085] (a) Take 1100 ml of spherical silica carrier (diameter 5 mm, specific surface area 175 m 2 / g, pore volume is 0.8cm 3 / g) was immersed in a mixed aqueous solution of chloropalladic acid, chloroauric acid and cupric chloride, and the solid-liquid volume ratio was calculated as 1:1.2, wherein the content of palladium in the solution used was 1.55 g / L, the content of gold was 1.55 g / L, and the content of copper was 0.155 g / L to prepare a catalyst precursor I;

[0086] (b) adding 100 ml of sodium silicate aqueous solution (27.5 g of Na2SiO3·9H2O is prepared into 100 ml of aqueous solution), mixing well and letting stand for 24 hours, and then drying at 80°C for 8 hours to obtain catalyst precursor II;

[0087] (c) adding 60 g of 85% wt hydrazine hydrate for reduction, standing for 4 hours, then washing with deionized water, and drying at 100° C. for 6 hours to obtain catalyst precursor III;

[0088] (d) washing the catalyst precursor III with water for 12 hours, and then drying at 80° C. for 6 hours to obtain a catalyst precursor IV;

[0089] (e) The catalyst precursor IV was impregnated with an aqueous solution of potassium acetate and dried at 80° C. for 2 h to obtain a finished catalyst, wherein the potassium acetate content in the catalyst was 30 g / L.

[0090] 2. Catalyst evaluation

[0091] The catalyst evaluation method was the same as in Example 1. The results are shown in Table 2.

[0092] Comparative Example 1

[0093] 1. Catalyst preparation

[0094] (a) Take 1100 ml of spherical silica carrier (diameter 5 mm, specific surface area 175 m 2 / g, pore volume is 0.8cm 3 / g) was immersed in a mixed aqueous solution of chloropalladic acid and chloroauric acid, calculated according to a solid-liquid volume ratio of 1:1.2, wherein the content of palladium in the solution used was 1.55 g / L, and the content of gold was 0.775 g / L, to prepare a catalyst precursor I;

[0095] (b) adding 100 ml of sodium silicate aqueous solution (27.5 g of Na2SiO3·9H2O is prepared into 100 ml of aqueous solution), mixing well and letting stand for 24 hours, and then drying at 80°C for 8 hours to obtain catalyst precursor II;

[0096] (c) adding 60 g of 85% wt hydrazine hydrate for reduction, standing for 4 hours, then washing with deionized water, and drying at 100° C. for 6 hours to obtain catalyst precursor III;

[0097] (d) washing the catalyst precursor III with water for 12 hours, and then drying at 80° C. for 6 hours to obtain a catalyst precursor IV;

[0098] (e) The catalyst precursor IV was impregnated with an aqueous solution of potassium acetate and dried at 80° C. for 2 h to obtain a finished catalyst, wherein the potassium acetate content in the catalyst was 30 g / L.

[0099] 2. Catalyst evaluation

[0100] The catalyst evaluation method was the same as in Example 1. The results are shown in Table 2.

[0101] Comparative Example 2

[0102] 1. Catalyst preparation

[0103] (a) Take 1100 ml of spherical silica carrier (diameter 5 mm, specific surface area 175 m 2 / g, pore volume is 0.8cm 3 / g) was immersed in a mixed aqueous solution of chloropalladic acid and cupric chloride, calculated according to a solid-liquid volume ratio of 1:1.2, wherein the content of palladium in the solution used was 1.55 g / L, and the content of copper was 0.775 g / L, to prepare a catalyst precursor I;

[0104] (b) adding 100 ml of sodium silicate aqueous solution (27.5 g of Na2SiO3·9H2O is prepared into 100 ml of aqueous solution), mixing well and letting stand for 24 hours, and then drying at 80°C for 8 hours to obtain catalyst precursor II;

[0105] (c) adding 60 g of 85% wt hydrazine hydrate for reduction, standing for 4 hours, then washing with deionized water, and drying at 100° C. for 6 hours to obtain catalyst precursor III;

[0106] (d) washing the catalyst precursor III with water for 12 hours, and then drying at 80° C. for 6 hours to obtain a catalyst precursor IV;

[0107] (e) The catalyst precursor IV was impregnated with an aqueous solution of potassium acetate and dried at 80° C. for 2 h to obtain a finished catalyst, wherein the potassium acetate content in the catalyst was 30 g / L.

[0108] 2. Catalyst evaluation

[0109] The catalyst evaluation method was the same as in Example 1. The results are shown in Table 2.

[0110] Table 1

[0111]

[0112]

[0113] Table 2

[0114] <![CDATA[STY(t / m 3 .d)]]> Selectivity Example 1 9.52 94.7％ Example 2 9.50 94.6％ Example 3 9.53 94.8％ Example 4 9.44 93.7％ Example 5 9.41 93.6％ Comparative Example 1 9.31 93.4％ Comparative Example 2 9.26 93.2％

[0115] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A catalyst for synthesizing vinyl acetate, comprising a carrier, and Pd, Au, Cu and alkali metal acetate loaded on the carrier.

2. The catalyst according to claim 1, characterized in that In the catalyst, the mass ratio is Au:Cu=(50-2):1, preferably, Au:Cu=(30-5):1; and / or In the catalyst, the mass ratio is Pd:(Au+Cu)=1:(0.11-1.1), preferably, Pd:(Au+Cu)=1:(0.265-0.5); and / or In the catalyst, the mass ratio of Pd:Au:Cu=1:(0.1-1.0):(0.01-0.1), preferably, Pd:Au:Cu=1:(0.2-0.8):(0.015-0.08); more preferably, in the catalyst, the mass ratio of Pd:Au:Cu=1:(0.25-0.45):(0.015-0.05).

3. The catalyst according to claim 1 or 2, characterized in that The alkali metal acetate is potassium acetate; and / or the carrier is selected from silicon dioxide and / or aluminum oxide.

4. The catalyst according to any one of claims 1 to 3, characterized in that The content of Pd in ​​the catalyst is 1-10 g / L; and / or the content of alkali metal acetate in the catalyst is 10-100 g / L, preferably 20-40 g / L.

5. A method for preparing a catalyst for synthesizing vinyl acetate, comprising the following steps: (a) immersing a catalyst support in a solution containing palladium, gold and copper to obtain a catalyst precursor I; (b) contacting the catalyst precursor I with a basic compound solution to obtain a catalyst precursor II; (c) reducing the metal ions in the catalyst precursor II to zero valence to obtain the catalyst precursor III; (d) washing the catalyst precursor III with water and drying it to obtain a catalyst precursor IV; (e) contacting the catalyst precursor IV with an alkali metal acetate.

6. The preparation method according to claim 5, characterized in that: In step (a), in the solution, the mass ratio of gold element to copper element is (50-2):1, preferably (30-5):1; Preferably, in the catalyst, the mass ratio is Pd:(Au+Cu)=1:(0.11-1.1); Preferably, the palladium element is derived from chloropalladic acid and / or palladium nitrate hydrate; Preferably, the gold element is derived from chloroauric acid and / or gold chloride trihydrate; Preferably, the copper element is derived from cupric chloride and / or cuprous chloride; Preferably, the alkali metal acetate is selected from potassium acetate and / or sodium acetate; Preferably, the alkaline compound is selected from an aqueous sodium silicate solution and / or an aqueous barium hydroxide solution.

7. A method for synthesizing vinyl acetate, comprising reacting a raw material gas comprising oxygen, ethylene, nitrogen and acetic acid in the presence of the catalyst according to any one of claims 1 to 4 or the catalyst obtained by the preparation method according to claim 5 or 6 to obtain vinyl acetate.

8. The synthesis method according to claim 7, characterized in that In terms of molar ratio, the raw gas composition is oxygen:ethylene:nitrogen:acetic acid=1:(5-7):(4-8):(1-2); Preferably, the raw gas composition is oxygen:ethylene:nitrogen:acetic acid=1:(5-6):(5-7):(1-2) in molar ratio.

9. The synthesis method according to claim 7 or 8, characterized in that: The reaction pressure is 0.5-0.9 MPa, preferably 0.6-0.8 MPa; and / or the reaction temperature is 130-200°C, preferably 150-180°C.

10. The synthesis method according to any one of claims 7 to 9, characterized in that: The volume space velocity of the feed gas is 1600-3000hr -1 , preferably 2000-2500hr -1 .

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