A catalyst, its preparation method and application in cyclododecanone synthesis

Abstract

The application provides a catalyst, a preparation method thereof and application of the catalyst in cyclododecanone synthesis. The application uses modified Cu-Zn-Si as a catalyst, and cyclododecanol as a raw material to prepare cyclododecanone through a dehydrogenation reaction. The combination of pyridine thione compounds and fluorine pyrimidine compounds is used as a modifier of the Cu-Zn-Si catalyst, which can significantly reduce the occurrence of a side reaction of cyclododecanol dehydration to generate cyclododecene, improve the selectivity of cyclododecanone, and make the selectivity of cyclododecanone greater than or equal to 99.5%, and the content of cyclododecene in the product less than or equal to 0.3%.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation and organic synthesis, specifically relating to a catalyst, its preparation method, and its application in the synthesis of cyclododecone. Background Technology

[0002] Cyclododecanoate (CDON) is a crucial intermediate in the preparation of nylon 12. Furthermore, due to its macrocyclic structure, CDON not only possesses the typical reactivity of cyclic ketones but also exhibits unique reactivity not found in small- or medium-sized rings. As an inexpensive and readily available petrochemical product, it serves as a precursor for the synthesis of many macrocyclic compounds, such as macrocyclic lactones in pesticides and fragrances, and musk-like compounds. In addition, it can participate in numerous synthetic reactions, contributing to the synthesis of compounds with specific structures and photoactive compounds. Many CDON derivatives, for example, are receiving increasing attention due to their bioactivity.

[0003] Numerous methods exist for the synthesis of cyclododecanone. However, processes such as the dicarboxylic acid cyclization method, the dicarboxylic acid ester cyclization method, and the bromoacid cyclization and ring-condensation method are less commonly used industrially due to drawbacks such as low yields, difficulty in separating impurities, expensive raw materials, and cumbersome steps. Currently, CDON is mainly prepared from cyclododecanetriene (CDT). CN110234625A reports a synthesis process for cyclododecanone as follows: hydrogenation of cyclododecanetriene to prepare cyclododecane, oxidation of cyclododecane to prepare cyclododecyl alcohol / ketone, and dehydrogenation of cyclododecyl alcohol to prepare cyclododecanone. However, the type of catalyst used in the dehydrogenation of cyclododecyl alcohol to prepare cyclododecanone and the reaction selectivity are not specified.

[0004]

[0005] CN103055880A reports a catalyst for the dehydrogenation of cyclododecyl alcohol to ketone and its preparation method. The main catalyst is Cu-Zn, and the promoter is a transition metal element with a non-active center, selected from vanadium, chromium, manganese, zirconium, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, or yttrium. However, using this catalyst, under the conditions of a temperature of 230℃ and a space velocity (WHSV) of 0.4, the conversion rate of cyclododecyl alcohol is only 95%, and the selectivity of cyclododecone is only 98%. A large number of side reactions are still generated. The reason is that cyclododecyl alcohol is easily dehydrated at high temperature to form the byproduct cyclododecene, which affects the selectivity of the main reaction.

[0006]

[0007] In summary, existing methods for preparing cyclododecyl still suffer from problems such as low conversion rate of cyclododecyl alcohol, poor selectivity of cyclododecyl, and large quantities of low-value products such as cyclododecene. Summary of the Invention

[0008] The purpose of this invention is to provide a catalyst that can increase the selectivity of cyclododecone to over 99.5% and reduce the content of cyclododecene in the product to below 0.3%.

[0009] To achieve the above technical effects, the present invention adopts the following technical solution:

[0010] A dehydrogenation catalyst, wherein the catalyst is a Cu-Zn-Si catalyst modified with pyridine thionone compound and fluoropyrimidine compound.

[0011] In this invention, the mass ratio of Cu, Zn, Si, pyridinethione compound, and fluoropyrimidine compound is 1:(0.1-2):(0.14-4.12):(0.003-0.03):(0.0003-0.015).

[0012] This invention employs a combination of pyridine thionone and fluoropyrimidine compounds as a catalyst modifier to suppress this side reaction. Both pyridine thionone and fluoropyrimidine compounds are basic, preventing the dehydration of cyclododecyl alcohol to cyclododecene under acidic conditions. Simultaneously, the hydroxyl group of cyclododecyl alcohol can coordinate with the metal atom of the pyridine thionone compound, and the fluorine atom of the fluoropyrimidine compound can form hydrogen bonds with the hydrogen atom of the cyclododecyl alcohol hydroxyl group. Both of these enhance the stability of cyclododecyl alcohol at high temperatures, preventing its dehydration to cyclododecene. Furthermore, the nitrogen atom of the fluoropyrimidine compound can coordinate with the metal atom of the pyridine thionone compound, improving the stability of both compounds. The catalyst exhibits improved stability during preparation and under high-temperature dehydrogenation conditions. Furthermore, the introduction of Si into the catalyst enhances the dispersion of Cu and Zn, increases the specific surface area, and consequently improves catalytic activity. Compared to traditional Cu-Zn-Al dehydrogenation catalysts, SiO2 is less acidic than Al2O3, further preventing the dehydration of cyclododecyl alcohol to produce cyclododecene under acidic conditions. The combined action of pyridine thione and fluoropyrimidine compounds prevents the aggregation of SiO2 in the silica sol, further improving its dispersion. This results in a larger specific surface area and higher activity for the Cu-Zn-Si catalyst.

[0013] Another object of the present invention is to provide a method for preparing a dehydrogenation catalyst.

[0014] A method for preparing a dehydrogenation catalyst, wherein the catalyst is the above-mentioned dehydrogenation catalyst, and the preparation method comprises the following steps:

[0015] S1: Dissolve copper and zinc salts in water and mix with silica sol;

[0016] S2: Add modifier, stir and mix, add alkali to precipitate metal ions in aqueous solution;

[0017] S3: Filter the precipitate, dry, calcine, and shape to obtain the modified Cu-Zn-Si catalyst.

[0018] The preparation process described above in this invention is a common preparation process for modified catalysts in the field, except that its modifier is significantly different from that of the prior art.

[0019] In this invention, the copper salt in S1 is a water-soluble copper salt, preferably one or more of copper nitrate, hydrochloride, sulfate, and phosphate, and more preferably copper nitrate.

[0020] In this invention, the zinc salt in S1 is a water-soluble zinc salt, preferably one or more of zinc nitrate, hydrochloride, sulfate, and phosphate, and more preferably zinc nitrate.

[0021] In this invention, the mass ratio of the copper salt and zinc salt in S1 is 1:0.1 to 1:2, preferably 1:0.5 to 1:1;

[0022] In this invention, the mass ratio of copper salt, water, and silica sol (calculated as SiO2) in S1 is 1:(10-50):(0.1-3), preferably 1:(20-30):(1-2).

[0023] In this invention, the pyridinethione compound in S2 is a pyridinethione salt, preferably a monovalent metal salt and / or a divalent metal salt of pyridinethione, more preferably one or more of zinc pyridinethione, copper pyridinethione, and sodium pyridinethione; preferably, the amount of pyridinethione compound used is 0.1-1 wt% of the copper salt, more preferably 0.3-0.5 wt%.

[0024] In this invention, the fluoropyrimidine compound in S2 is a pyrimidine compound containing 1-4 fluorine atoms, preferably a pyrimidine compound containing 1-3 fluorine atoms, more preferably one or more of 2-chloro-5-fluoropyrimidine, 2,4-dichloro-5-fluoropyrimidine, 5-fluoropyrimidine-4-amine, 3,5-dichloro-2,6-difluoropyrimidine, 2,4-diamino-6-fluoropyrimidine, 4-ethyl-5-fluoropyrimidine, 4-amino-2-chloro-5-fluoropyrimidine, 4-amino-2,6-difluoropyrimidine, 4-amino-2,5,6-trifluoropyrimidine, 5-amino-2-fluoropyrimidine, 4,5,6-trifluoropyrimidine, and 4-chloro-6-ethyl-5-fluoropyrimidine; preferably, the amount of the fluoropyrimidine compound is 0.01-0.5 wt% of the copper salt, more preferably 0.1-0.3 wt%.

[0025] In this invention, the alkali mentioned in S2 is an alkaline solution, preferably one or more of the following: sodium oxide, potassium hydroxide, calcium hydroxide, ammonium carbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, and ammonia aqueous solution, more preferably an aqueous solution of sodium hydroxide and / or ammonia.

[0026] In this invention, the calcination temperature in S3 is 300-500℃, preferably 350-400℃.

[0027] Another object of the present invention is to provide a method for preparing cyclododecanone by dehydrogenation.

[0028] A method for preparing cyclododecylone by dehydrogenation, the method employing the above-mentioned dehydrogenation catalyst, or a catalyst prepared by the above-mentioned catalyst preparation method, wherein cyclododecyl alcohol is used as a raw material to prepare cyclododecylone via a catalytic dehydrogenation reaction.

[0029] In this invention, the reaction temperature of the dehydrogenation method for preparing cyclododecanone is 180-300℃, preferably 200-250℃; the mass hourly space velocity (WHSV) of the reaction, based on cyclododecanol, is 0.01-2 h⁻¹. -1 Preferably 0.5-1h -1 .

[0030] Compared with the prior art, the positive effects of the present invention are as follows:

[0031] Using the method of the present invention, the selectivity of cyclododecone is ≥99.5%, and the content of cyclododecene in the product can be reduced to below 0.3%. Detailed Implementation

[0032] The present invention will be further described below with reference to the embodiments. It should be noted that the embodiments do not constitute a limitation on the scope of protection of the present invention.

[0033] (1) Reaction conversion rate analysis

[0034] Gas chromatography was used to analyze the conversion rate of cyclododecyl alcohol (CDOL), the selectivity of cyclododecone (CDON), and the content of the byproduct cyclododecene (CDE).

[0035] Instrument model: Shimadzu GC2010; Column: DB-5 (30×0.32×0.25); Column temperature: programmed temperature rise (60℃ for 5 min, then rise to 120℃ at a rate of 5℃ / min, then rise to 300℃ at a rate of 20℃ / min and hold for 5 min); Injector temperature: 250℃; FID temperature: 300℃; N2 flow rate: 1 mL / min; H2 flow rate: 40 mL / min; Septum purge (N2) flow rate: 3 mL / min; Carrier gas (N2) flow rate: 1 mL / min; Split injection, split ratio: 50; Injection volume: 0.03 μL.

[0036] (2) Catalyst Analysis

[0037] The modified Cu-Zn-Si catalyst was analyzed using a MicroActive for ASAP 2460 instrument from the United States, in accordance with the standard GB / T 19587-2004.

[0038] The main raw material manufacturers are as follows:

[0039] raw material Specification factory Cyclododecyl ≥99％ Degussa Pyridinethione compounds ≥96％ Hubei Jianchu Biomedical Co., Ltd. Fluoropyrimidine compounds ≥97％ Beijing Bailingwei Technology Co., Ltd.

[0040] The main equipment information is as follows:

[0041]

[0042] Example 1

[0043] Preparation of modified Cu-Zn-Si catalyst-A:

[0044] S1: Dissolve 10g of copper nitrate and 1g of zinc nitrate in 100g of deionized water and mix with 6.67g of silica sol with a silica content of 15wt%.

[0045] S2: Add 0.01g of zinc pyridinethione and 0.001g of 5-amino-2-fluoropyrimidine to the reaction solution and stir until well mixed; while stirring, add 5wt% sodium hydroxide aqueous solution to the mixture to adjust the pH to 11;

[0046] S3: Filter out the precipitate, dry it in an oven at 120℃ for 4 hours, then calcine it in a muffle furnace at 300℃ for 10 hours, add 0.1% of guar gum powder by weight of the precipitate and extrude it to obtain the modified Cu-Zn-Si catalyst-A.

[0047] The catalyst was characterized, and its specific surface area was 127 m². 2 / g.

[0048] Evaluation of modified Cu-Zn-Si catalyst-A:

[0049] Modified Cu-Zn-Si catalyst-A was loaded into a fixed bed, CDOL was molten and fed, and the reaction temperature was set at 180℃, the pressure at 0.1 MPa(G), and the CDOL mass hourly space velocity at 0.01 h⁻¹. -1 After the device was running stably, samples were taken for analysis. The CDOL conversion rate was 99.68%, the CDON selectivity was 99.91%, and the byproduct CDE selectivity was 0.04%.

[0050] Example 2

[0051] Preparation of modified Cu-Zn-Si catalyst-B:

[0052] S1: Dissolve 10g of copper nitrate and 20g of zinc nitrate in 500g of deionized water and mix with 75g of silica sol with a silica content of 40wt%.

[0053] S2: Add 0.1g of copper pyridinethione and 0.05g of 4-ethyl-5-fluoropyrimidine to the reaction solution and stir until well mixed; while stirring, add 25wt% ammonia water to the mixture to adjust the pH to 9;

[0054] S3: Filter out the precipitate, dry it in an oven at 200℃ for 10h, then calcine it in a muffle furnace at 500℃ for 2h, add 1.0% of guar gum powder by weight of the precipitate and extrude it to obtain the modified Cu-Zn-Si catalyst-B.

[0055] The catalyst was characterized, and its specific surface area was 132 m². 2 / g.

[0056] Evaluation of modified Cu-Zn-Si catalyst-B:

[0057] The modified Cu-Zn-Si catalyst-B was loaded into a fixed bed, CDOL was molten and fed, and the reaction temperature was set at 300℃, the pressure at atmospheric pressure, and the CDOL mass hourly space velocity at 2 h⁻¹. -1 After the device was running stably, samples were taken for analysis. The CDOL conversion rate was 99.74%, the CDON selectivity was 99.83%, and the byproduct CDE selectivity was 0.07%.

[0058] Example 3

[0059] Preparation of modified Cu-Zn-Si catalyst-C:

[0060] S1: Dissolve 10g of copper nitrate and 5g of zinc nitrate in 300g of deionized water and mix with 50g of silica sol with a silica content of 30wt%.

[0061] S2: Add 0.04g sodium pyridinethione and 0.02g 2,4-diamino-6-fluoropyrimidine to the reaction solution and stir until well mixed; while stirring, add 5wt% sodium hydroxide aqueous solution to the mixture to adjust the pH to 10;

[0062] S3: Filter out the precipitate, dry the precipitate in an oven at 150℃ for 8 hours, then calcine it in a muffle furnace at 400℃ for 6 hours, add 1.8% of guar gum powder by weight of the precipitate and extrude it to obtain the modified Cu-Zn-Si catalyst-C.

[0063] The catalyst was characterized, and its specific surface area was 133 m². 2 / g.

[0064] Evaluation of the modified Cu-Zn-Si catalyst-C:

[0065] The modified Cu-Zn-Si catalyst-C was loaded into a fixed bed, and CDOL was molten and fed. The reaction temperature was set at 220℃, the pressure at atmospheric pressure, and the CDOL mass hourly space velocity at 0.7 h⁻¹. -1After the device was running stably, samples were taken for analysis. The CDOL conversion rate was 99.79%, the CDON selectivity was 99.92%, and the byproduct CDE selectivity was 0.03%.

[0066] Comparative Example 1

[0067] The Cu-Zn catalyst was prepared using a method similar to that in Example 1, without the addition of silica sol, zinc pyridinium thionate, and 5-amino-2-fluoropyrimidine. The catalyst was characterized, and its specific surface area was found to be 86 m². 2 / g.

[0068] The catalyst was evaluated using a method similar to that in Example 1, and the CDOL conversion was 87.01%, the CDON selectivity was 97.11%, and the byproduct CDE selectivity was 2.46%.

[0069] Comparative Example 2

[0070] The Cu-Zn catalyst was prepared using a method similar to that in Example 1, without the addition of silica sol. The catalyst was characterized, and its specific surface area was found to be 10⁴ m². 2 / g.

[0071] The catalyst was evaluated using a method similar to that in Example 1, and the CDOL conversion was 92.13%, the CDON selectivity was 99.02%, and the byproduct CDE selectivity was 0.14%.

[0072] Comparative Example 3

[0073] A Cu-Zn-Si catalyst was prepared using a method similar to that in Example 1, without the addition of zinc pyridinethione. The catalyst was characterized, and its specific surface area was found to be 113 m². 2 / g.

[0074] The catalyst was evaluated using a method similar to that in Example 1, and the CDOL conversion was 96.17%, the CDON selectivity was 97.76%, and the byproduct CDE selectivity was 1.95%.

[0075] Comparative Example 4

[0076] A Cu-Zn-Si catalyst was prepared using a method similar to that in Example 1, without the addition of 5-amino-2-fluoropyrimidine. The catalyst was characterized, and its specific surface area was found to be 107 m². 2 / g.

[0077] The catalyst was evaluated using a method similar to that in Example 1, and the CDOL conversion was 94.43%, the CDON selectivity was 98.17%, and the byproduct CDE selectivity was 0.94%.

Claims

1. A dehydrogenation catalyst characterized by, The catalyst is a Cu-Zn-Si catalyst modified by a pyrithione compound and a fluoropyrimidine compound; The pyrithione compound is a pyrithione salt. The fluoropyrimidine compound is a pyrimidine compound containing 1-4 fluorines.

2. The dehydrogenation catalyst according to claim 1, characterized in that, The mass ratio of Cu, Zn, Si, the pyrithione compound, the fluoropyrimidine compound is 1:(0.1-2):(0.14-4.12):(0.003-0.03):(0.0003-0.015).

3. A process for the preparation of a dehydrogenation catalyst, said catalyst being the dehydrogenation catalyst according to claim 1, characterized in that, The preparation method comprises the following steps: S1: dissolving copper and zinc salts in water and mixing with silica sol; S2: adding a modifier, stirring and mixing, adding a base, and precipitating metal ions in the aqueous solution; S3: filtering the precipitate, drying, calcining, and shaping to obtain the modified Cu-Zn-Si catalyst.

4. The production method according to claim 3, characterized by, The copper salt in S1 is a water-soluble copper salt; The zinc salt in S1 is a water-soluble zinc salt; The mass ratio of the copper salt and the zinc salt in S1 is 1:0.1-1:2; The mass ratio of the copper salt, water, and silica sol (calculated as SiO2) in S1 is 1:(10-50):(0.1-3).

5. The preparation method according to claim 4, characterized in that, The copper salt in S1 is one or more of nitrate, hydrochloride, sulfate, and phosphate; The zinc salt in S1 is one or more of nitrate, hydrochloride, sulfate, and phosphate; The mass ratio of the copper salt and the zinc salt in S1 is 1:0.5-1:1; The mass ratio of the copper salt, water, and silica sol (calculated as SiO2) in S1 is 1:(20-30):(1-2).

6. The production method according to claim 5, wherein The copper salt in S1 is copper nitrate; The zinc salt in S1 is zinc nitrate.

7. The preparation method according to claim 3, characterized in that, The pyrithione compound in S2 is a pyrithione monovalent metal salt and / or a pyrithione divalent metal salt; The fluoropyrimidine compound in S2 is a pyrimidine compound containing 1-3 fluorines; The base in S2 is a lye.

8. The production method according to claim 7, characterized by, The pyrithione compound in S2 is one or more of pyrithione zinc, pyrithione copper, and pyrithione sodium; The amount of the pyrithione compound in S2 is 0.1-1 wt% of the copper salt; The fluoropyrimidine compound in S2 is one or more of 2-chloro-5-fluoropyrimidine, 2,4-dichloro-5-fluoropyrimidine, 5-fluoropyrimidine-4-amine, 3,5-dichloro-2,6-difluoropyrimidine, 2,4-diamino-6-fluoropyrimidine, 4-ethyl-5-fluoropyrimidine, 4-amino-2-chloro-5-fluoropyrimidine, 4-amino-2,6-difluoropyrimidine, 4-amino-2,5,6-trifluoropyrimidine, 5-amino-2-fluoropyrimidine, 4,5,6-trifluoropyrimidine, and 4-chloro-6-ethyl-5-fluoropyrimidine; The amount of the fluoropyrimidine compound in S2 is 0.01-0.5 wt% of the copper salt; The base in S2 is one or more of aqueous solutions of sodium oxide, potassium hydroxide, calcium hydroxide, ammonium carbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, and ammonia.

9. The production method according to claim 8, characterized by, The amount of the pyrithione compound in S2 is 0.3-0.5 wt% of the copper salt; The amount of the fluoropyrimidine compound in S2 is 0.1-0.3 wt% of the copper salt; The base in S2 is an aqueous solution of sodium hydroxide and / or ammonia.

10. The method of claim 3, wherein, S3 the calcination temperature is 300-500℃.

11. The method of claim 10, wherein, S3 the calcination temperature is 350-400℃.

12. A method for preparing cyclododecanone by dehydrogenation, which uses the dehydrogenation catalyst of claim 1 or 2, or a catalyst prepared by the preparation method of the catalyst of any one of claims 3-11, and which uses cyclododecanol as a raw material to prepare cyclododecanone by catalytic dehydrogenation reaction.

13. The method of claim 12, wherein the method is carried out at a temperature of from 50 °C to 70 °C. The reaction temperature of the method is 180-300℃; the mass space velocity of the reaction is 0.01-2h -1 .

14. The method of claim 13, wherein the method is carried out at a temperature of from 50 °C to 70 °C. The reaction temperature of the method is 200-250℃; the mass space velocity of the reaction is 0.5-1h -1 .

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