A preparation method and application of crude N-ethylaniline

Abstract

The present invention relates to the technical field of C07C211 / 48, specifically a method for preparing a crude N-ethylaniline product and its application, which at least comprises the following steps: (1) pumping aniline and ethanol into a mixing kettle, mixing them evenly and then atomizing them by pumping to obtain an atomized liquid; (2) heating the atomized liquid, controlling the flow rate of the atomized liquid so that it passes through a reaction container filled with a catalyst, heating the atomized liquid for an alkylation reaction to obtain a crude N-ethylaniline product. The amount of N-N-diethylaniline, a byproduct, generated in the crude N-ethylaniline product is effectively reduced, so that the provided crude N-ethylaniline product has high selectivity and high conversion rate, is conducive to subsequent purification treatment, and the method is simple, low in cost, and easy to promote and use.

Description

Technical Field

[0001] The invention relates to the technical field of C07C211 / 48, in particular to a preparation method of crude N-ethylaniline and application thereof. Background Art

[0002] N-ethylaniline is an organic amine compound, a yellow-brown transparent oily liquid with the smell of aniline. It is an important intermediate for many organic compounds and is widely used in dyes, drugs, polymers, rubber, plastics and pesticides.

[0003] At present, the traditional preparation process mainly uses aniline and ethanol as raw materials, and generates N-ethylaniline through high temperature and high pressure. The reaction conditions are harsh, the equipment requirements are high, and a large amount of N, N-diethylaniline by-products are also produced, and the selectivity and conversion rate are low. For example, a Chinese patent application (authorization announcement number is CN106008225B) specifically discloses a method for preparing a crude N-ethylaniline product with high production efficiency and zero emission. The method mainly adopts a catalyst composed of phosphorus oxychloride and copper chromium mixed in a weight ratio of 5:1-2 to achieve a selectivity of N-ethylaniline of about 75%, but the by-product NN-diethylaniline generated at the same time is as high as 5-6%. Therefore, it is of great significance for industrial production to develop a low-cost, high-selectivity, high-conversion method for synthesizing N-ethylaniline. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for preparing crude N-ethylaniline, which effectively reduces the amount of by-product NN-diethylaniline generated in the crude N-ethylaniline, so that the provided crude N-ethylaniline has high selectivity and high conversion rate, which is beneficial to subsequent purification treatment, and the method is simple, low in cost, and easy to promote and use.

[0005] The present invention provides a method for preparing crude N-ethylaniline, which comprises at least the following steps:

[0006] (1) pumping aniline and ethanol into a mixing kettle, mixing them evenly, and then atomizing them by pumping to obtain an atomized liquid;

[0007] (2) After the temperature of the atomized liquid is raised, the flow rate of the atomized liquid is controlled so that the atomized liquid passes through a reaction container filled with a catalyst, and the temperature is raised to perform an alkylation reaction to obtain a crude N-ethylaniline product.

[0008] As a preferred technical solution, the aniline is aniline with a mass content of >99%; the ethanol is ethanol with a mass content of >93%.

[0009] As a preferred technical solution, the molar ratio of aniline to ethanol is 1:(1.05-1.25).

[0010] Based on the system of the present invention, by using aniline with a purity of more than 99% and ethanol with a purity of more than 93% to react in a molar ratio of 1:(1.05-1.25), on the one hand, the raw materials can be obtained by purification and recovery, and the cost is very low. On the other hand, under the above-mentioned molar ratio condition of slightly excess ethanol, the aniline conversion rate in the system is relatively high.

[0011] As a preferred technical solution, the pressure of the pump atomization is 2.5-3.5 MPa.

[0012] As a preferred technical solution, the temperature of the atomized liquid is raised to 140-180°C.

[0013] As a preferred technical solution, the flow rate of the atomized liquid is 400-500m 3 / h.

[0014] Based on the system of the present invention, ethanol and aniline are first mixed and then atomized, and the atomized liquid is heated to 140-180°C and then heated at 400-500m 3 / h through the reaction container filled with catalyst, so that the raw material liquid has enough time to fully contact with the catalyst, ensuring the degree of alkylation reaction and improving the efficiency of subsequent alkylation reactions, which generates huge economic benefits.

[0015] As a preferred technical solution, the catalyst is cylindrical particles prepared by mixing copper nitrate, zinc nitrate and ammonium dichromate.

[0016] Based on the system of the present invention, by adopting a mixed catalyst including copper nitrate, zinc nitrate and ammonium dichromate, the catalytic activity and selectivity are high, the purity of N-ethylaniline in the crude N-ethylaniline product is significantly improved to more than 75%, and the amount of by-products generated is effectively reduced.

[0017] As a preferred technical solution, the temperature of the alkylation reaction is 220-260°C, preferably 230-240°C.

[0018] The inventors found in the process of exploration that the selectivity of the catalyst catalyzing the reaction of aniline and ethanol to generate N-ethylaniline and the aniline conversion rate are greatly affected by the alkylation reaction temperature. The inventors controlled the alkylation reaction temperature to 220-260°C, especially to carry out the alkylation reaction at 230-240°C, while ensuring a high aniline conversion rate, further improving the purity of N-ethylaniline in the crude N-ethylaniline product, so that the prepared crude N-ethylaniline product has basically no by-product N, N-diethylaniline. The inventors analyzed that the reason may be: the mixed catalyst including copper nitrate, zinc nitrate and ammonium dichromate introduced into the system has high catalytic reaction activity and selectivity for aniline and ethanol at 230-240°C, and the aniline in the system effectively generates N-ethylaniline, while the temperature is too high, and the amount of N, N-diethylaniline by-products generated in the system increases.

[0019] Another aspect of the present invention provides an application of a method for preparing crude N-ethylaniline, which is applied to the preparation of crude N-ethylaniline with a gas phase purity of 80-90% and the subsequent purification and preparation of finished N-ethylaniline with a purity greater than 99.5%.

[0020] Beneficial Effects

[0021] 1. The present invention provides a method for preparing crude N-ethylaniline, which effectively reduces the amount of by-product NN-diethylaniline generated in the crude N-ethylaniline, so that the provided crude N-ethylaniline has high selectivity and high conversion rate, which is beneficial to subsequent purification treatment, and the method is simple, low in cost, and easy to promote and use.

[0022] 2. Based on the system of the present invention, by using aniline with a purity of >99% and ethanol with a purity of >93% in a molar ratio of 1:(1.05-1.25) for reaction, on the one hand, the raw materials can be obtained by purification and recovery, and the cost is very low. On the other hand, under the above-mentioned molar ratio condition of a slight excess of ethanol, the conversion rate of aniline in the system is relatively high.

[0023] 3. Based on the system of the present invention, ethanol and aniline are first mixed and then atomized, and the atomized liquid is heated to 140-180°C and then heated at 400-500m 3 / h through the reaction container filled with catalyst, so that the raw material liquid has enough time to fully contact with the catalyst, ensuring the degree of alkylation reaction and improving the efficiency of subsequent alkylation reactions, which generates huge economic benefits.

[0024] 4. Based on the system of the present invention, by adopting a mixed catalyst including copper nitrate, zinc nitrate and ammonium dichromate, the catalytic activity and selectivity are high, the purity of N-ethylaniline in the crude N-ethylaniline product is significantly increased to more than 75%, and the amount of by-products generated is effectively reduced.

[0025] 5. Based on the system of the present invention, by controlling the temperature of the alkylation reaction to 220-260° C., especially carrying out the alkylation reaction at 230-240° C., the purity of N-ethylaniline in the crude N-ethylaniline product is further improved while ensuring a high aniline conversion rate, so that the prepared crude N-ethylaniline product is substantially free of by-product N,N-diethylaniline. DETAILED DESCRIPTION

[0026] Example 1

[0027] Embodiment 1 of the present invention provides a method for preparing crude N-ethylaniline, comprising the following steps:

[0028] (1) pumping 4618 kg of aniline and 2813 kg of ethanol into a mixing kettle, mixing them evenly, and then atomizing them by pumping to obtain an atomized liquid;

[0029] (2) After the temperature of the atomized liquid is raised, the flow rate of the atomized liquid is controlled so that it passes through a reaction container filled with 1000 g of catalyst, and the temperature is raised to carry out an alkylation reaction to obtain crude N-ethylaniline 1.

[0030] The aniline is an industrial aniline product with a purity of 99.8%; the ethanol is an industrial ethanol product with a purity of 93.5%.

[0031] The molar ratio of aniline to ethanol is 1:1.15.

[0032] The pressure of the pump atomization is 3.0 MPa.

[0033] The temperature of the atomized liquid is raised to 160°C.

[0034] The flow rate of the atomized liquid is 450m 3 / h.

[0035] The catalyst is cylindrical particles prepared by mixing copper nitrate, zinc nitrate and ammonium dichromate, with a model of XC-01, and comes from Wuxi Ruyi Oil Catalyst Chemical Plant.

[0036] The temperature of the alkylation reaction was 220°C.

[0037] Example 2

[0038] Example 2 of the present invention provides a method for preparing crude N-ethylaniline, and its specific implementation method is the same as that of Example 1, except that the temperature of the alkylation reaction is 230° C., and a crude N-ethylaniline 2 is obtained accordingly.

[0039] Example 3

[0040] Example 3 of the present invention provides a method for preparing crude N-ethylaniline, and its specific implementation method is the same as that of Example 1, except that the temperature of the alkylation reaction is 240° C., and the corresponding crude N-ethylaniline 3 is obtained.

[0041] Example 4

[0042] Example 4 of the present invention provides a method for preparing crude N-ethylaniline, and its specific implementation method is the same as that of Example 1, except that the temperature of the alkylation reaction is 250° C., and crude N-ethylaniline 4 is obtained accordingly.

[0043] Example 5

[0044] Example 5 of the present invention provides a method for preparing crude N-ethylaniline, and its specific implementation method is the same as that of Example 1, except that the temperature of the alkylation reaction is 260° C., and the corresponding crude N-ethylaniline 5 is obtained.

[0045] Example 6

[0046] Embodiment 6 of the present invention provides a method for preparing crude N-ethylaniline, and its specific implementation manner is the same as that of Embodiment 2, except that the method for preparing crude N-ethylaniline comprises the following steps:

[0047] (1) pumping 4781 kg of aniline and 2650 kg of ethanol into a mixing kettle, mixing them evenly, and then atomizing them by pumping to obtain an atomized liquid;

[0048] (2) After the temperature of the atomized liquid is raised, the flow rate of the atomized liquid is controlled so that it passes through a reaction vessel filled with 1000 g of catalyst, and the temperature is raised to carry out an alkylation reaction to obtain a crude N-ethylaniline product 6.

[0049] The molar ratio of aniline to ethanol is 1:1.05.

[0050] Example 7

[0051] Embodiment 7 of the present invention provides a method for preparing crude N-ethylaniline, and its specific implementation manner is the same as that of Embodiment 2, except that the method for preparing crude N-ethylaniline comprises the following steps:

[0052] (1) pumping 4477 kg of aniline and 2954 kg of ethanol into a mixing kettle, mixing them evenly, and then atomizing them by pumping to obtain an atomized liquid;

[0053] (2) After the temperature of the atomized liquid is raised, the flow rate of the atomized liquid is controlled so that it passes through a reaction container filled with 1000 g of catalyst, and the temperature is raised to carry out an alkylation reaction to obtain crude N-ethylaniline 7.

[0054] The molar ratio of aniline to ethanol is 1:1.25.

[0055] Comparative Example 1

[0056] Comparative Example 1 of the present invention provides a method for preparing a crude N-ethylaniline product. 462 g of 99.8% aniline, 281 g of 93.5% ethanol, and 23 g of 99% phosphorus oxychloride are added to a 1L high-pressure reactor, the temperature is slowly raised to 230°C, the pressure is controlled at 3.0 MPa, the temperature is maintained and the pressure is maintained for 8 hours, and the crude product 8 is obtained by cooling.

[0057] Comparative Example 2

[0058] Comparative Example 2 of the present invention provides a method for preparing a crude N-ethylaniline product. 462 g of 99.8% aniline, 281 g of 93.5% ethanol, and 20.6 g of 99% phosphorus trichloride are added to a 1L high-pressure reactor, the temperature is slowly raised to 230°C, the pressure is controlled at 3.0 MPa, the temperature is maintained and the pressure is maintained for 8 hours, and the crude product 9 is obtained by cooling.

[0059] Performance Testing Methods

[0060] The crude N-ethylaniline prepared by the method for preparing the crude N-ethylaniline provided in the embodiment was subjected to a purity test by gas chromatography, wherein the gas chromatography detection conditions were as follows: chromatographic column: SE-54 column; injection volume: 0.5ul; detector temperature 250°C, injector temperature 250°C; split ratio 30:1; carrier gas: 99.999% nitrogen; column box: initial temperature 100°C, maintained for 5 minutes, raised to 180°C at a rate of 10°C / min, maintained for 15 minutes; conversion rate was calculated based on aniline, and the results are shown in Table 1.

[0061] in:

[0062]

[0063] Table 1

[0064]

[0065]

Claims

1. A method for preparing crude N-ethylaniline, characterized in that: At least the following steps are included: (1) Aniline and ethanol are pumped into a mixing kettle, mixed evenly, and then atomized by pumping to obtain an atomized liquid; (2) After the temperature of the atomized liquid is raised, the flow rate of the atomized liquid is controlled so that it passes through a reaction container filled with a catalyst, and the temperature is raised to perform an alkylation reaction to obtain a crude N-ethylaniline product; the aniline is aniline with a mass content of more than 99%; the ethanol is ethanol with a mass content of more than 93%; the molar ratio of the aniline to the ethanol is 1:(1.05-1.25); the pressure of the pump pressure atomization is 2.5-3.5 MPa; the temperature of the atomized liquid is 140-180°C; the flow rate of the atomized liquid is 400-500 m / s; 3 / h; the catalyst is a cylindrical particle prepared by mixing copper nitrate, zinc nitrate and ammonium dichromate, model XC-01, which comes from Wuxi Ruyi Oil Catalyst Chemical Plant; the temperature of the alkylation reaction is 230-240°C.

2. An application of the method for preparing a crude N-ethylaniline according to claim 1, characterized in that: The method is applied to the preparation of crude N-ethylaniline with a gas phase purity of 80-90% and the subsequent purification and preparation of finished N-ethylaniline with a purity of more than 99.5%.

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