Caprolactam synthesis method

Abstract

The invention provides a caprolactam synthesis method, and relates to the field of compound production. A caprolactam synthesis method comprises the following steps that cyclohexanone oxime serves as a raw material, a composite catalyst is added, the composite catalyst is prepared from graphene oxide and a metal salt aqueous solution, metal salt is composed of palladium chloride and titanium trichloride, a reaction is carried out under the vacuum condition, a reaction product is collected, an organic solvent is added, ultrasonic dispersion and filtering are carried out, filtrate is collected, and caprolactam is obtained. And decompressing and concentrating to remove the solvent to obtain caprolactam. According to the present invention, with the method, the target product caprolactam and cyclohexanone-oxime production conversion rate is high, the 100% conversion is achieved, the caprolactam selectivity is improved, the caprolactam purity is improved, the production efficiency and the production quality are comprehensively improved, and the reaction time is reduced. The prepared composite catalyst is high in catalytic efficiency and high in stability, the production quality of caprolactam is well guaranteed, and the regeneration performance is good.

Description

Technical Field

[0001] The invention relates to the field of compound preparation, and in particular to a method for synthesizing caprolactam. Background Art

[0002] Caprolactam is an important organic compound with the chemical formula C6H 11 NO, belongs to the lactam compounds. It is the main raw material for the synthesis of nylon-6 (Polycaprolactam), and is widely used in the fields of textiles, plastics and engineering materials. Due to its excellent physical and chemical properties, caprolactam plays an extremely important role in modern industry.

[0003] The main uses of caprolactam include: (1) Synthesis of nylon-6: The main use of caprolactam is as a precursor material for nylon-6, which is a polymer material with good mechanical properties, wear resistance and chemical stability. It is widely used in the production of fibers, plastic products and engineering parts. (2) Coatings and surface treatment agents: Caprolactam can be used as a raw material for coatings, providing excellent adhesion and durability. It is widely used in the preparation of coatings for automobiles, home appliances and industrial equipment. (3) Additives and modifiers: In certain specific applications, caprolactam can also be used as an additive to improve the performance and processability of the material. (4) Chemical synthesis: Caprolactam can be used as an intermediate for the synthesis of other chemicals, expanding its application in the field of fine chemicals.

[0004] As the global demand for high-performance materials continues to increase, the market demand for caprolactam is also increasing. Therefore, the development of efficient, economical and environmentally friendly caprolactam synthesis methods has important economic value and social significance.

[0005] At present, the synthesis methods of caprolactam mainly include cyclohexane oxidation method, ammonolysis method, etc. However, traditional synthesis methods are often accompanied by problems such as high energy consumption, low conversion rate and environmental pollution. Specifically, the production process of caprolactam often has the following problems: (1) Difficulty in controlling the production process: strong heat release and high viscosity are difficult to control; (2) Large consumption of sulfuric acid; (3) High cost and unstable quality. Therefore, there is an urgent need for novel caprolactam synthesis methods to improve production efficiency, reduce negative impacts on the environment, and promote its application in a wider range of fields. Summary of the invention

[0006] In view of this, the present invention provides a method for synthesizing caprolactam to solve the above problems.

[0007] The technical solution of the present invention is achieved in this way:

[0008] A method for synthesizing caprolactam comprises the following steps: using cyclohexanone oxime as a raw material, adding a composite catalyst, wherein the composite catalyst is prepared from graphene oxide and a metal salt aqueous solution, reacting under vacuum conditions, collecting reaction products, adding an organic solvent, ultrasonically dispersing, filtering, collecting filtrate, and concentrating under reduced pressure to remove the solvent to obtain caprolactam.

[0009] A further technical solution is that the preparation method of the composite catalyst comprises the following steps: adding graphene oxide to a metal salt aqueous solution, placing the solution in a microwave reactor, the reaction temperature being 80-120°C, the microwave power being 600-800W, the reaction time being 20-30min, collecting the product, and drying the product to obtain the composite catalyst.

[0010] A further technical solution is that the molar ratio of the graphene oxide to the metal salt is 1:1-1.1.

[0011] A further technical solution is that the metal salt is composed of palladium chloride and titanium trichloride in a mass ratio of 1:3-5, and the mass concentration of the metal salt aqueous solution is 0.2%-0.4%.

[0012] A further technical solution is that the size of the composite catalyst is 200-400 nm.

[0013] A further technical solution is that the added amount of the composite catalyst is 4%-6% of the mass of cyclohexanone oxime.

[0014] A further technical solution is that the reaction conditions are: vacuum degree 0.04-0.06MPa, reaction temperature 80-90°C, and reaction time 2-4h.

[0015] A further technical solution is that the organic solvent is prepared by mixing ethanol and ether in a volume ratio of 1:0.1-0.2.

[0016] A further technical solution is that the liquid-to-solid ratio of the organic solvent to cyclohexanone oxime is 10-20 ml: 1 g.

[0017] A further technical solution is that the temperature of the ultrasonic dispersion is 5-10°C and the time is 20-40 minutes.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The method of the present invention uses cyclohexanone oxime as a raw material and adds a composite catalyst to react under vacuum conditions to produce the target product caprolactam. The cyclohexanone oxime conversion rate is high, achieving 100% conversion, improving the caprolactam selectivity, improving the overall yield, and improving the purity of caprolactam, comprehensively improving the production efficiency and production quality, and reducing the reaction time.

[0020] (2) The composite catalyst prepared by the microwave reaction of graphene oxide and metal salt in the present invention not only has high catalytic efficiency and strong stability, which can better guarantee the production quality of caprolactam, but also has good regeneration performance.

[0021] (3) The production process of the present invention is easy to control, and the product quality is stable, the production efficiency is high, the negative impact on the environment is small, it is relatively environmentally friendly, and is conducive to wide application. DETAILED DESCRIPTION

[0022] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0023] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0024] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources.

[0025] Example 1

[0026] A method for synthesizing caprolactam comprises the following steps:

[0027] (1) The preparation method of the composite catalyst comprises the following steps: adding graphene oxide to a 0.3%wt metal salt aqueous solution, wherein the molar ratio of graphene oxide to the metal salt is 1:1, and the metal salt is composed of palladium chloride and titanium trichloride in a mass ratio of 1:4, placing the mixture in a microwave reactor, reacting at a temperature of 100°C, a microwave power of 700W, and a reaction time of 25min, collecting the product, drying it, and crushing it to prepare a composite catalyst with a particle size of 300nm.

[0028] (2) Cyclohexanone oxime is used as a raw material, and the composite catalyst prepared in step (1) is added in an amount of 5% of the mass of cyclohexanone oxime. The reaction is carried out at 85° C. for 3 h under a vacuum condition of 0.05 MPa, and the reaction product is collected. An organic solvent (prepared by mixing ethanol and ether in a volume ratio of 1:0.15) is added, and the liquid-to-solid ratio of the organic solvent to cyclohexanone oxime is 15 ml:1 g. Ultrasonic dispersion is performed at 8° C. for 30 min, and the filtrate is filtered, and the filtrate is collected. The solvent is removed by vacuum concentration to obtain a caprolactam product.

[0029] Example 2

[0030] A method for synthesizing caprolactam comprises the following steps:

[0031] (1) The preparation method of the composite catalyst comprises the following steps: adding graphene oxide to a 0.2%wt metal salt aqueous solution, wherein the molar ratio of graphene oxide to the metal salt is 1:1, and the metal salt is composed of palladium chloride and titanium trichloride in a mass ratio of 1:3, placing the mixture in a microwave reactor, reacting at a temperature of 90°C, a microwave power of 600W, and a reaction time of 20min, collecting the product, drying it, and crushing it to prepare a composite catalyst with a particle size of 300nm.

[0032] (2) Cyclohexanone oxime is used as a raw material, and the composite catalyst prepared in step (1) is added in an amount of 5% of the mass of cyclohexanone oxime. The reaction is carried out at 80° C. for 4 h under a vacuum condition of 0.05 MPa, and the reaction product is collected. An organic solvent (prepared by mixing ethanol and ether in a volume ratio of 1:0.1) is added, and the liquid-to-solid ratio of the organic solvent to cyclohexanone oxime is 15 ml:1 g. Ultrasonic dispersion is performed at 10° C. for 20 min, and the filtrate is filtered, and the filtrate is collected. The solvent is removed by vacuum concentration to obtain a caprolactam product.

[0033] Example 3

[0034] A method for synthesizing caprolactam comprises the following steps:

[0035] (1) The preparation method of the composite catalyst comprises the following steps: adding graphene oxide to a 0.4%wt metal salt aqueous solution, wherein the molar ratio of graphene oxide to the metal salt is 1:1, and the metal salt is composed of palladium chloride and titanium trichloride in a mass ratio of 1:5, placing the mixture in a microwave reactor, reacting at a temperature of 110°C, a microwave power of 800W, and a reaction time of 30min, collecting the product, drying it, and crushing it to prepare a composite catalyst with a particle size of 300nm.

[0036] (2) Cyclohexanone oxime is used as a raw material, and the composite catalyst prepared in step (1) is added in an amount of 5% of the mass of cyclohexanone oxime. The reaction is carried out at 90° C. for 2 h under a vacuum condition of 0.05 MPa, and the reaction product is collected. An organic solvent (prepared by mixing ethanol and ether in a volume ratio of 1:0.2) is added, and the liquid-to-solid ratio of the organic solvent to cyclohexanone oxime is 15 ml:1 g. Ultrasonic dispersion is performed at 5° C. for 40 min, and the filtrate is filtered, and the filtrate is collected. The solvent is removed by vacuum concentration to obtain a caprolactam product.

[0037] Comparative Example 1

[0038] The difference between this comparative example and Example 1 is that graphene oxide is not added in the preparation of the composite catalyst, but graphene is used.

[0039] The method for synthesizing caprolactam comprises the following steps:

[0040] (1) The preparation method of the composite catalyst comprises the following steps: adding graphene to a 0.3%wt metal salt aqueous solution, wherein the molar ratio of graphene to the metal salt is 1:1, and the metal salt is composed of palladium chloride and titanium trichloride in a mass ratio of 1:4, placing the graphene in a microwave reactor, the reaction temperature is 100°C, the microwave power is 700W, the reaction time is 25min, the product is collected, dried, and crushed to prepare a composite catalyst with a particle size of 300nm.

[0041] (2) Cyclohexanone oxime is used as a raw material, and the composite catalyst of step (1) is added, wherein the amount of the composite catalyst added is 5% of the mass of cyclohexanone oxime, and the reaction is carried out at 85° C. for 3 h under a vacuum condition of 0.05 MPa, and the reaction product is collected, and an organic solvent (prepared by mixing ethanol and ether in a volume ratio of 1:0.15) is added, and the liquid-to-solid ratio of the organic solvent to cyclohexanone oxime is 15 ml:1 g, and ultrasonic dispersion is carried out at 8° C. for 30 min, and the filtrate is filtered, and the filtrate is collected, and the solvent is removed by vacuum concentration to obtain a caprolactam product.

[0042] Comparative Example 2

[0043] The difference between this comparative example and Example 1 is that when preparing the composite catalyst, titanium trichloride is not added to the metal salt, but only palladium chloride is used.

[0044] The method for synthesizing caprolactam comprises the following steps:

[0045] (1) The preparation method of the composite catalyst comprises the following steps: adding graphene oxide to a 0.3%wt palladium chloride aqueous solution, wherein the molar ratio of graphene oxide to palladium chloride is 1:1, placing the graphene oxide in a microwave reactor, reacting at a temperature of 100°C, a microwave power of 700W, and a reaction time of 25min, collecting the product, drying it, and crushing it to prepare a composite catalyst with a particle size of 300nm.

[0046] (2) Cyclohexanone oxime is used as a raw material, and the composite catalyst prepared in step (1) is added in an amount of 5% of the mass of cyclohexanone oxime. The reaction is carried out at 85° C. for 3 h under a vacuum condition of 0.05 MPa, and the reaction product is collected. An organic solvent (prepared by mixing ethanol and ether in a volume ratio of 1:0.15) is added, and the liquid-to-solid ratio of the organic solvent to cyclohexanone oxime is 15 ml:1 g. Ultrasonic dispersion is performed at 8° C. for 30 min, and the filtrate is filtered, and the filtrate is collected. The solvent is removed by vacuum concentration to obtain a caprolactam product.

[0047] Comparative Example 3

[0048] The difference between this comparative example and Example 1 is that when preparing the composite catalyst, no palladium chloride is added to the metal salt, but only titanium trichloride is used.

[0049] The method for synthesizing caprolactam comprises the following steps:

[0050] (1) The preparation method of the composite catalyst comprises the following steps: adding graphene oxide to a 0.3%wt titanium trichloride aqueous solution, wherein the molar ratio of graphene oxide to titanium trichloride is 1:1, placing the mixture in a microwave reactor, reacting at a temperature of 100°C, a microwave power of 700W, and a reaction time of 25min, collecting the product, drying it, and crushing it to prepare a composite catalyst with a particle size of 300nm.

[0051] (2) Cyclohexanone oxime is used as a raw material, and the composite catalyst prepared in step (1) is added in an amount of 5% of the mass of cyclohexanone oxime. The reaction is carried out at 85° C. for 3 h under a vacuum condition of 0.05 MPa, and the reaction product is collected. An organic solvent (prepared by mixing ethanol and ether in a volume ratio of 1:0.15) is added, and the liquid-to-solid ratio of the organic solvent to cyclohexanone oxime is 15 ml:1 g. Ultrasonic dispersion is performed at 8° C. for 30 min, and the filtrate is filtered, and the filtrate is collected. The solvent is removed by vacuum concentration to obtain a caprolactam product.

[0052] Comparative Example 4

[0053] The difference between this comparative example and Example 1 is that when preparing the composite catalyst, palladium chloride and titanium trichloride are not added as the metal salt, but zinc chloride is used.

[0054] The method for synthesizing caprolactam comprises the following steps:

[0055] (1) The preparation method of the composite catalyst comprises the following steps: adding graphene oxide to a 0.3%wt zinc chloride aqueous solution, wherein the molar ratio of graphene oxide to zinc chloride is 1:1, placing the graphene oxide in a microwave reactor, reacting at a temperature of 100°C, a microwave power of 700W, and a reaction time of 25min, collecting the product, drying it, and crushing it to prepare a composite catalyst with a particle size of 300nm.

[0056] (2) Cyclohexanone oxime is used as a raw material, and the composite catalyst prepared in step (1) is added in an amount of 5% of the mass of cyclohexanone oxime. The reaction is carried out at 85° C. for 3 h under a vacuum condition of 0.05 MPa, and the reaction product is collected. An organic solvent (prepared by mixing ethanol and ether in a volume ratio of 1:0.15) is added, and the liquid-to-solid ratio of the organic solvent to cyclohexanone oxime is 15 ml:1 g. Ultrasonic dispersion is performed at 8° C. for 30 min, and the filtrate is filtered, and the filtrate is collected. The solvent is removed by vacuum concentration to obtain a caprolactam product.

[0057] Comparative Example 5

[0058] The difference between this comparative example and Example 1 is that ethyl acetate is used instead of ethanol and ether as the organic solvent.

[0059] The method for synthesizing caprolactam comprises the following steps:

[0060] (1) The preparation method of the composite catalyst comprises the following steps: adding graphene oxide to a 0.3%wt metal salt aqueous solution, wherein the molar ratio of graphene oxide to the metal salt is 1:1, and the metal salt is composed of palladium chloride and titanium trichloride in a mass ratio of 1:4, placing the mixture in a microwave reactor, reacting at a temperature of 100°C, a microwave power of 700W, and a reaction time of 25min, collecting the product, drying it, and crushing it to prepare a composite catalyst with a particle size of 300nm.

[0061] (2) Cyclohexanone oxime is used as a raw material, and the composite catalyst prepared in step (1) is added in an amount of 5% of the mass of cyclohexanone oxime. The reaction is carried out at 85° C. for 3 h under a vacuum condition of 0.05 MPa, and the reaction product is collected. Ethyl acetate is added, and the liquid-to-solid ratio of ethyl acetate to cyclohexanone oxime is 15 ml:1 g. Ultrasonic dispersion is carried out at 8° C. for 30 min, and the filtrate is filtered, and the filtrate is collected. The solvent is removed by concentration under reduced pressure to obtain a caprolactam product.

[0062] Caprolactam was prepared according to the methods of Examples 1-3 and Comparative Examples 1-5, the cyclohexanone oxime conversion rate and caprolactam selectivity were calculated, and the purity of the final caprolactam product was tested. The statistical results are shown in Table 1 below:

[0063]

[0064] The above results show that, compared with Comparative Examples 1-5, the method of Example 1 of the present invention produces the target product caprolactam, has a high conversion rate of cyclohexanone oxime, achieves 100% conversion, improves the caprolactam selectivity, and improves the purity of caprolactam, comprehensively improves the production efficiency and production quality, and secondly, the methods of Examples 2-3 are also relatively good choices.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for synthesizing caprolactam, characterized in that: The following steps are involved: Cyclohexanone oxime is used as a raw material, a composite catalyst is added, the composite catalyst is prepared from graphene oxide and a metal salt aqueous solution, the metal salt is composed of palladium chloride and titanium trichloride, the reaction is carried out under vacuum conditions, the reaction product is collected, an organic solvent is added, ultrasonic dispersion is performed, filtering is performed, the filtrate is collected, and the solvent is removed by decompression concentration to obtain caprolactam.

2. The method for synthesizing caprolactam according to claim 1, characterized in that: The preparation method of the composite catalyst comprises the following steps: adding graphene oxide to a metal salt aqueous solution, placing the mixture in a microwave reactor, reacting at a temperature of 80-120° C., a microwave power of 600-800 W, and a reaction time of 20-30 min, collecting the product, and drying the product to obtain the composite catalyst.

3. The method for synthesizing caprolactam according to claim 2, characterized in that: The molar ratio of the graphene oxide to the metal salt is 1:1-1.

1.

4. The method for synthesizing caprolactam according to claim 2, characterized in that: The metal salt is composed of palladium chloride and titanium trichloride in a mass ratio of 1:3-5, and the mass concentration of the metal salt aqueous solution is 0.2%-0.4%.

5. The method for synthesizing caprolactam according to claim 1, characterized in that: The particle size of the composite catalyst is 200-400nm.

6. The method for synthesizing caprolactam according to claim 1, characterized in that: The added amount of the composite catalyst is 4%-6% of the mass of cyclohexanone oxime.

7. The method for synthesizing caprolactam according to claim 1, characterized in that: The reaction conditions are as follows: vacuum degree 0.04-0.06 MPa, reaction temperature 80-90° C., and reaction time 2-4 h.

8. The method for synthesizing caprolactam according to claim 1, characterized in that: The organic solvent is prepared by mixing ethanol and ether in a volume ratio of 1:0.1-0.

2.

9. The method for synthesizing caprolactam according to claim 1 or 8, characterized in that: The liquid-to-solid ratio of the organic solvent to cyclohexanone oxime is 10-20 ml: 1 g.

10. The method for synthesizing caprolactam according to claim 1, characterized in that: The temperature of the ultrasonic dispersion is 5-10°C and the time is 20-40 minutes.

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