Gas-liquid mixing method for amination reaction

Abstract

The present application relates to the field of organic chemical technology, and more particularly to a gas-liquid mixing method for amination reaction; comprising a main pipeline for conveying amination reaction raw materials into a reactor, an inert gas pipeline, a caprolactam raw material tank, a fresh amination agent supplement pipeline and a circulating amination agent pipeline connected in sequence on the main pipeline; wherein an inert gas preheater is arranged on the inert gas pipeline, the raw material in the raw material tank is gasified by the inert gas pipeline, and a gasification mixed gas containing inert gas is formed; wherein the amination agent supplemented in the fresh amination agent supplement pipeline is also preheated, mixed with the gasification mixed gas in the main pipeline, and subjected to secondary gasification; the mixed gas after secondary gasification is mixed with the amination agent in the circulating amination agent pipeline, and enters the reactor together.

Description

Technical Field

[0001] This invention relates to the field of organic chemical technology, and in particular to a gas-liquid mixing method for an amination reaction. Background Technology

[0002] According to patent CN215996614U, a magnetically stabilized reaction device is described. This device is used in the reaction of direct hydrogenation of 6-aminohexanonitrile to prepare hexamethylenediamine, which improves the reaction selectivity and reaction efficiency.

[0003] Patent CN112110832A describes a method for the efficient synthesis of a key intermediate in hexamethylenediamine. This method involves staged feeding of caprolactam with ammonia. The advantages are: in the first stage, the high molar ratio of ammonia to caprolactam improves caprolactam conversion and 6-aminohexanonitrile selectivity; the second stage increases the overall caprolactam content and ammonia utilization. This staged feeding approach improves raw material utilization and product selectivity, saves costs, and increases economic benefits.

[0004] Patent CN215540695U describes an apparatus for preparing the hexamethylenediamine intermediate 6-aminohexanonitrile by a gas-phase method. This apparatus designs the vaporizer as a Venturi tube structure, utilizing the high gas flow rate and local negative pressure zone formed by the fluid in the throat of the Venturi tube to rapidly mix and vaporize the raw materials. This avoids thermal polymerization that would occur during prolonged heating and vaporization of the raw materials, thus preventing the stability of the apparatus from being affected. The high vaporization rate of caprolactam can improve the conversion rate of the raw materials and the selectivity of the products.

[0005] Amination is an important chemical reaction, and the products prepared (such as adiponitrile and 6-aminohexanonitrile, which are intermediates in the synthesis of hexamethylenediamine) are important intermediates. This invention improves reaction selectivity and efficiency while also reducing the amount of ammonia (amine) used. Summary of the Invention

[0006] The purpose of this invention is to provide a gas-liquid mixing method for an amination reaction that improves reaction selectivity and efficiency while also reducing the amount of amination agent required.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] The present invention provides a gas-liquid mixing method for an amination reaction, comprising a main pipeline for conveying the raw materials for the amination reaction into a reactor, an inert gas pipeline connected in sequence to the main pipeline, a caprolactam raw material tank, a pipeline for replenishing fresh amination agent, and a pipeline for circulating amination agent.

[0009] The liquid raw material in the raw material tank is mixed with the amination agent during the main pipeline transportation process;

[0010] An inert gas preheater is installed on the inert gas pipeline to vaporize caprolactam in the caprolactam raw material tank and form a vaporized mixture containing inert gas.

[0011] The amination agent added to the replenishment fresh amination agent pipeline is also preheated, mixed with the vaporization mixture in the main pipeline, and subjected to secondary vaporization;

[0012] The mixed gas, after secondary gasification, is mixed with the amination agent in the circulating amination agent pipeline and then enters the reactor together.

[0013] Preferably, the amination agent is one or more of liquid ammonia, ammonia water, urea, and organic amines.

[0014] Preferably, the molar ratio of inert gas to caprolactam entering the main pipeline is 1 to 15:1.

[0015] Preferably, the ratio of the inert gas to caprolactam is 2 to 10:1.

[0016] Preferably, the amount of fresh amination agent added to the replenishing fresh amination agent pipeline is not less than the amount consumed in the amination reaction, and the unreacted amination agent needs to be purified by removing water or other impurities before reuse.

[0017] Preferably, the molar ratio of the amination agent reused in the circulating amination agent pipeline and the amination agent replenished in the fresh amination agent replenishment pipeline to caprolactam is 1 to 40.

[0018] Preferably, the molar ratio is between 3 and 25.

[0019] Preferably, the amination agent replenished in the replenishment fresh amination agent pipeline is mixed with the mixed gas in the main pipeline and subjected to secondary vaporization, and the temperature after mixing is the temperature required for the reaction.

[0020] Preferably, the reaction liquid in the reactor undergoes gas-liquid separation, and the inert gas is separated by pressurization.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows: the addition of nitrogen gas increases the spacing between the components, which delays their contact to a certain extent; the reaction is a reversible reaction, and nitrogen gas helps to quickly remove the reactants and products from the catalyst, which can reduce side reactions and thus improve selectivity. While improving the reaction selectivity and reaction efficiency, it also has the advantage of reducing the amount of amination agent used. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1This is a schematic diagram of the installation of the gas-liquid mixing method for the amination reaction of the present invention.

[0024] Explanation of reference numerals in the attached diagram: 1. Inert gas preheater; a. Inert gas pipeline; 2. Raw material tank; b. Raw material pipeline; c. Fresh amination agent replenishment pipeline; d. Circulating amination agent pipeline; 3. Reactor; e. Post-reaction material pipeline. Detailed Implementation

[0025] This embodiment discloses a gas-liquid mixing method for an amination reaction, including a main pipeline for conveying the raw materials for the amination reaction into a reactor 3, an inert gas pipeline a connected in sequence to the main pipeline, a caprolactam raw material tank 2, a pipeline for replenishing fresh amination agent c, and a pipeline for circulating amination agent d.

[0026] The liquid raw material in the caprolactam raw material tank 2 is mixed with the amination agent during the main pipeline transportation process;

[0027] An inert gas preheater 1 is installed on the inert gas pipeline a, and the raw materials in the raw material tank 2 are vaporized by the inert gas pipeline a to form a vaporized mixture containing inert gas.

[0028] The amination agent added in the fresh amination agent replenishment pipeline c is also preheated, and then mixed with the vaporization mixture in the main pipeline and subjected to secondary vaporization.

[0029] The mixed gas after secondary gasification is mixed with the amination agent in the circulating amination agent pipeline d and then enters the reactor 3 together.

[0030] In this embodiment, the amination agent is one or more of liquid ammonia, ammonia water, urea, and organic amines.

[0031] In this embodiment, the molar ratio of inert gas to raw material entering the main pipeline is 1 to 15:1; wherein the ratio of inert gas to raw material is preferably 2 to 10:1, and most preferably 3 to 7:1.

[0032] In this embodiment, the amount of fresh amination agent added to the fresh amination agent replenishment pipeline c is not less than the amount consumed by the amination reaction, and the unreacted amination agent needs to be purified by removing water or other impurities before reuse.

[0033] In this embodiment, the molar ratio of the amination agent reused in the circulating amination agent pipeline d and the amination agent replenished in the fresh amination agent replenishment pipeline c to the raw material is 1 to 40; the preferred molar ratio is 3 to 25.

[0034] In this embodiment, the amination agent replenished in the fresh amination agent replenishment pipeline c is mixed with the mixed gas in the main pipeline and undergoes secondary vaporization. The temperature after mixing is the temperature required for the reaction.

[0035] In this embodiment, the reaction liquid in the reactor 3 is separated by gas-liquid separation, and the inert gas is separated by pressurization.

[0036] Example 1

[0037] like Figure 1 As shown, a gas-liquid mixing device for an amination reaction includes: 1. an inert gas preheater, a is an inert gas pipeline; 2. a raw material tank, b is a raw material pipeline; c is a pipeline for replenishing fresh amination agent; d is a pipeline for circulating amination agent; 3. a reactor; and e is a pipeline for post-reaction materials.

[0038] According to Example 1 of Patent 202010525822.7, 500g of caprolactam amination and dehydration catalyst was prepared, and 50g of the calcined catalyst was loaded into a reactor for evaluation.

[0039] Example 2

[0040] Using the apparatus and catalyst of Example 1, without adding inert carrier gas, at a space velocity of 3h -1 Caprolactam and ammonia were mixed and passed through a catalyst bed at 395°C for amination. The ammonia / caprolactam molar ratio was 3:4, ammonia was not recycled, caprolactam conversion was 78.0%, and 6-aminohexanonitrile selectivity was 96.9%.

[0041] Example 3

[0042] Using the apparatus and catalyst of Example 1, an inert carrier gas, nitrogen, was added at a molar ratio of 15 to caprolactam, with a space velocity of 3 h⁻¹. -1 Caprolactam and ammonia were mixed and passed through a catalyst bed at 395°C for amination. The ammonia / caprolactam molar ratio was 3:4, ammonia was not recycled, caprolactam conversion was 77.7%, and 6-aminohexanonitrile selectivity was 98.0%.

[0043] Example 4

[0044] Using the apparatus and catalyst of Example 1, an inert carrier gas, nitrogen, was added at a molar ratio of 7 to caprolactam, with a space velocity of 3 h⁻¹. -1 Caprolactam and ammonia were mixed and passed through a catalyst bed at 395°C for amination. The ammonia / caprolactam molar ratio was 3:4. Ammonia was not recycled. The caprolactam conversion rate was 77.8%, and the selectivity of 6-aminohexanonitrile was 97.9%.

[0045] Example 5

[0046] Using the apparatus and catalyst of Example 1, an inert carrier gas, nitrogen, was added at a molar ratio of 3 to caprolactam, with a space velocity of 3 h⁻¹. -1Caprolactam and ammonia were mixed and passed through a catalyst bed at 395°C for amination. The ammonia / caprolactam molar ratio was 3:4. Ammonia was not recycled. The caprolactam conversion rate was 77.9%, and the selectivity of 6-aminohexanonitrile was 97.8%.

[0047] Example 6

[0048] Using the apparatus and catalyst of Example 1, an inert carrier gas, nitrogen, was added at a molar ratio of 2 to caprolactam, with a space velocity of 3 h⁻¹. -1 Caprolactam and ammonia were mixed and passed through a catalyst bed at 395°C for amination. The ammonia / caprolactam molar ratio was 3:4. Ammonia was not recycled. The caprolactam conversion rate was 77.9%, and the selectivity of 6-aminohexanonitrile was 97.3%.

[0049] Example 7

[0050] Using the apparatus and catalyst of Example 1, an inert carrier gas, nitrogen, was added at a molar ratio of 1 to caprolactam, with a space velocity of 3 h⁻¹. -1 Caprolactam and ammonia were mixed and passed through a catalyst bed at 395°C for amination. The ammonia / caprolactam molar ratio was 3:4, ammonia was not recycled, caprolactam conversion was 77.9%, and 6-aminohexanonitrile selectivity was 97.1%.

[0051] Example 8

[0052] Using the apparatus and catalyst of Example 1, an inert carrier gas, nitrogen, was added at a molar ratio of 3 to caprolactam, with a space velocity of 3 h⁻¹. -1 Caprolactam and ammonia were mixed and passed through a catalyst bed at 395°C for amination reaction. The ammonia / caprolactam molar ratio was 3:4. After separation from the inert gas, the ammonia was dehydrated and recycled. The amount of fresh ammonia replenished was consistent with the amount of ammonia consumed. The caprolactam conversion rate was 77.9%, and the selectivity of 6-aminohexanonitrile was 97.6%.

[0053] Example 9

[0054] Using the apparatus and catalyst of Example 1, an inert carrier gas, nitrogen, was added at a molar ratio of 7 to caprolactam, with a space velocity of 3 h⁻¹. -1 Caprolactam and ammonia were mixed and passed through a catalyst bed at 395℃ for amination reaction. The ammonia / caprolactam molar ratio was 3:4. After separation from the inert gas, the ammonia was dehydrated and recycled. The amount of fresh ammonia replenished was consistent with the amount of ammonia consumed. The caprolactam conversion rate was 77.7%, and the selectivity of 6-aminohexanonitrile was 97.9%.

[0055] Example 10

[0056] Using the apparatus and catalyst of Example 1, an inert carrier gas, nitrogen, was added at a molar ratio of 7 to caprolactam, with a space velocity of 3 h⁻¹. -1Caprolactam and ammonia were mixed and passed through a catalyst bed at 395℃ for amination reaction. The ammonia / caprolactam molar ratio was 25. After separation from the inert gas, the ammonia was dehydrated and recycled. The amount of fresh ammonia replenished was consistent with the amount of ammonia consumed. The caprolactam conversion rate was 77.7%, and the selectivity of 6-aminohexanonitrile was 97.8%.

[0057] Example 11

[0058] Using the apparatus and catalyst of Example 1, an inert carrier gas, nitrogen, was added at a molar ratio of 7 to caprolactam, with a space velocity of 3 h⁻¹. -1 Caprolactam and ammonia were mixed and passed through a catalyst bed at 395℃ for amination reaction. The ammonia / caprolactam molar ratio was 3. After separation from the inert gas, the ammonia was dehydrated and recycled. The amount of fresh ammonia replenished was consistent with the amount of ammonia consumed. The caprolactam conversion rate was 77.9%, and the selectivity of 6-aminohexanonitrile was 96.7%.

[0059] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0060] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A gas-liquid mixing method for an amination reaction, characterized in that: It includes a main pipeline for conveying the amination reaction raw materials into the reactor (3), a nitrogen pipeline (a) connected in sequence to the main pipeline, a caprolactam raw material tank (2), a pipeline for replenishing fresh amination agent (c), and a pipeline for circulating amination agent (d). The liquid raw material in the raw material tank (2) is mixed with the amination agent during the main pipeline transportation process; A nitrogen preheater (1) is installed on the nitrogen pipeline (a) to vaporize the raw materials in the raw material tank (2) and form a vaporized mixture containing nitrogen. The amination agent added in the replenishment fresh amination agent pipeline (c) is also preheated, mixed with the vaporization mixture in the main pipeline, and subjected to secondary vaporization; The mixed gas after secondary gasification is mixed with the amination agent in the circulating amination agent pipeline (d) and then enters the reactor (3).

2. The gas-liquid mixing method for the amination reaction according to claim 1, characterized in that: The amination agent is one or more of liquid ammonia, ammonia water, and urea.

3. The gas-liquid mixing method for the amination reaction according to claim 1, characterized in that: The molar ratio of nitrogen to raw materials entering the main pipeline is 1~15:

1.

4. The gas-liquid mixing method for the amination reaction according to claim 3, characterized in that: The molar ratio of nitrogen to raw materials is 2~10:

1.

5. The gas-liquid mixing method for the amination reaction according to claim 1, characterized in that: The amount of fresh amination agent added to the replenishing fresh amination agent pipeline (c) shall not be less than the amount consumed by the amination reaction. Unreacted amination agent shall be purified by removing water or other impurities before reuse.

6. The gas-liquid mixing method for the amination reaction according to claim 1, characterized in that: The molar ratio of the amination agent reused in the circulating amination agent pipeline (d) to the raw material in the replenishment of fresh amination agent pipeline (c) is 1~40.

7. The gas-liquid mixing method for the amination reaction according to claim 6, characterized in that: The molar ratios mentioned above are 3 to 25.

8. The gas-liquid mixing method for the amination reaction according to claim 1, characterized in that: The amination agent replenished in the replenishment fresh amination agent pipeline (c) is mixed with the mixed gas in the main pipeline and undergoes secondary vaporization. The temperature after mixing is the temperature required for the reaction.

9. The gas-liquid mixing method for the amination reaction according to claim 1, characterized in that: The reaction liquid in the reactor (3) is separated by gas-liquid separation, and nitrogen is separated by pressurization.

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