阅读说明：本技术 一种1-氰基-2-丙烯基乙酸酯的制备方法及装置 (Preparation method and device of 1-cyano-2-propenyl acetate ) 是由 王志轩 郎咸东 杜振宇 李建军 车荣峰 陈聪 于 2020-12-31 设计创作，主要内容包括：本发明提供一种1-氰基-2-丙烯基乙酸酯的制备方法,采用液体循环真空泵作为吸收装置。本方法使用液体循环真空泵作为吸收装置,吸收效率高,本发明制备的产品1-氰基-2-丙烯基乙酸酯的一次收率(丙烯醛氰醇计算)为99-99.85%,产品纯度为98.5%以上。本方法只需要液体循环真空泵即可完成吸收反应,不需要产品后处理步骤,设备投资低。(The invention provides a preparation method of 1-cyano-2-propenyl acetate, which adopts a liquid circulation vacuum pump as an absorption device. The method uses a liquid circulation vacuum pump as an absorption device, has high absorption efficiency, and the product 1-cyano-2-propenyl acetic ester prepared by the method has the primary yield (calculated by acrolein cyanohydrin) of 99-99.85 percent and the product purity of more than 98.5 percent. The method can complete the absorption reaction only by a liquid circulating vacuum pump, does not need a product post-treatment step, and has low equipment investment.)

1. A method for preparing 1-cyano-2-propenyl acetate is characterized in that: a liquid circulation vacuum pump is adopted as an absorption device.

2. The process according to claim 1, wherein the reaction product of 1-cyano-2-propenyl acetate: introducing ketene gas into a liquid circulation vacuum pump, introducing ACA working solution into the liquid circulation vacuum pump, continuously introducing acrolein cyanohydrin into a pipeline for introducing the ACA working solution into the liquid circulation vacuum pump, uniformly mixing the acrolein cyanohydrin with the ACA working solution, and then introducing the mixture into the liquid circulation vacuum pump.

3. The process according to claim 2, wherein the reaction product of 1-cyano-2-propenyl acetate: the feeding temperature of the ketene gas is 5-25 ℃, and the absolute pressure is 0.02 MPa-0.1 MPa.

4. The process according to claim 2, wherein the reaction product of 1-cyano-2-propenyl acetate: the temperature of the ACA working solution is 5-30 ℃.

5. The process according to claim 2, wherein the reaction product of 1-cyano-2-propenyl acetate: the feeding molar ratio of the ketene gas to the acrolein cyanohydrin is 1-1.01: 1.

6. the process according to claim 2, wherein the reaction product of 1-cyano-2-propenyl acetate: the volume ratio of the acrolein cyanohydrin to the ACA working solution is 1: 20 to 150.

7. The process according to claim 1, wherein the reaction product of 1-cyano-2-propenyl acetate: the reaction temperature is 20-35 ℃, and the pressure of the liquid circulation vacuum pump is 0.02 MPa-0.1 MPa in absolute.

8. The process according to claim 2, wherein the reaction product of 1-cyano-2-propenyl acetate: and a product obtained by gas-liquid separation of the reaction liquid obtained by absorption is divided into two strands, one strand is collected as an ACA product, and the other strand is used as a working liquid after heat exchange and then is used as an ACA working liquid.

9. An apparatus for producing 1-cyano-2-propenyl acetate, characterized in that: the device

The device comprises a liquid ring vacuum pump, a gas-liquid separation tower and a heat exchanger, wherein an inlet of the liquid ring vacuum pump is connected with the heat exchanger through a pipeline, and a feed inlet of acrolein cyanohydrin is arranged on the pipeline; the outlet of the liquid ring vacuum pump is connected with a gas-liquid separation tower through a pipeline, wherein a discharge hole at the bottom of the gas-liquid separation tower is provided with a branch, one branch is used for discharging finished products, and the other branch is connected with a heat exchanger.

Technical Field

The invention relates to a preparation method of 1-cyano-2-propenyl acetate, belonging to the field of esterification synthesis.

Background

1-cyano-2-propenyl Acetate (ACA, Acrolein cyanohydran Acetate) is mainly used as an intermediate for producing glufosinate-ammonium as a pesticide.

The synthesis routes of ACA are mainly two: one is that acrolein reacts with hydrocyanic acid or cyanide solution to produce acrolein cyanohydrin, the acrolein cyanohydrin obtained reacts with organic acyl halide or acid anhydride to obtain ACA reaction liquid, then ether is used to extract organic phase from the reaction liquid, the organic phase is neutralized by sodium carbonate solution, dried by anhydrous sodium sulfate, filtered and rectified to obtain product ACA; the other is that acrolein is mixed with NaCN or NaCN aqueous solution, then mixed with acid anhydride, and reacted by a one-pot method to obtain ACA reaction liquid, and then the ACA product is obtained by post-treatment.

Both the two-step and one-step processes produce one molecule of acetic acid, and the prior art uses this process.

CN112094203A provides a preparation method of 1-cyano-2-propenyl acetate, which comprises the steps of preparing ketene gas by cracking acetic acid and esterifying acrolein cyanohydrin; the method adopts acrolein cyanohydrin solution to directly absorb ketene gas to prepare 1-cyano-2-propenyl acetate. According to the method, a catalyst or a solvent is not needed, the primary yield (calculated by acrolein cyanohydrin) of the obtained product 1-cyano-2-propenyl acetate can reach more than 95%, the purity of the obtained primary product can reach more than 97.5%, and no acetic acid is generated, but in industrial operation, the fact that ketene obtained by cracking acetic acid needs to enter an absorption device through a vacuum pump when entering the absorption device is discovered, the ketene has partial loss in the vacuum pump, the ketene obtained by cracking is easy to generate reverse reaction in a pipeline and the pump to be changed into dilute acetic acid or generate polymerization, and the total yield is reduced.

Disclosure of Invention

In view of the above problems, the present invention provides a method and apparatus for preparing 1-cyano-2-propenyl acetate (ACA), achieving the following objects:

1) the consumption of the ketene is reduced, and the utilization rate of the ketene is improved;

2) improves the purity of the ACA and omits the post-treatment step.

In order to solve the technical problems, the invention adopts the following technical scheme:

a method for preparing 1-cyano-2-propenyl acetate adopts a liquid circulation vacuum pump as an absorption device.

The following is a further improvement of the above technical solution:

the preparation method comprises the following steps:

1) and continuously introducing ketene gas into the gas feed pipe, conveying ACA working solution into a liquid circulation vacuum pump through a working solution inlet, adding acrolein cyanohydrin through a working solution inlet pipeline, uniformly mixing the acrolein cyanohydrin with the ACA working solution, then feeding the mixture into the liquid circulation vacuum pump, and absorbing the ketene gas to obtain 1-cyano-2-propenyl acetate reaction liquid and a very small amount of non-condensable gas.

2) Feeding the reaction liquid in the step 1) into a gas-liquid separation tower, wherein the reaction liquid is not condensed and discharged from the top of the tower, and the 1-cyano-2-propenyl acetate product is divided into two streams from a product outlet at the bottom of the tower, wherein one stream is used as a product, and the other stream is used as a working liquid and is fed into a heat exchanger;

3) and (3) after the working solution in the step 2) passes through a heat exchanger, obtaining ACA working solution and sending the ACA working solution into a liquid circulation vacuum pump.

The feeding mode of the acrolein cyanohydrin can adopt the feeding mode of a Venturi tube, so that the good mixing degree of the acrolein cyanohydrin is ensured.

The ketene gas in the step 1) is from acetic acid cracking, the feeding temperature of the ketene gas is 5-25 ℃, the absolute pressure is 0.02-0.1 MPa, preferably 5-15 ℃, and the absolute pressure is 0.02-0.05 MPa;

the working solution in the step 3) passes through a heat exchanger to obtain ACA working solution, the temperature is 5-30 ℃, and the normal pressure is realized; preferably 15 to 25 ℃;

the feeding molar ratio of the ketene gas to the acrolein cyanohydrin in the step 1) is 1-1.01: 1, the volume ratio of the acrolein cyanohydrin to the ACA working solution is 1: 20 to 150.

The reaction temperature is 20-35 ℃.

In the whole device operation process, the 1-cyano-2-propenyl acetate product in the step 2) is divided into two parts from a tower bottom product outlet, and the device stable operation is ensured by controlling the product discharge amount and the feeding amount of ketene and acrolein cyanohydrin products and maintaining the circulation amount within a certain range. Typically, the product throughput is substantially the same as the feed rates of the ketene and acrolein cyanohydrin products.

The present invention also provides an apparatus for preparing 1-cyano-2-propenyl acetate (ACA):

the device comprises a liquid ring vacuum pump, a gas-liquid separation tower and a heat exchanger, wherein an inlet of the liquid ring vacuum pump is connected with the heat exchanger through a pipeline, and a feed inlet of acrolein cyanohydrin is arranged on the pipeline; the outlet of the liquid ring vacuum pump is connected with a gas-liquid separation tower through a pipeline, wherein a discharge hole at the bottom of the gas-liquid separation tower is provided with a branch, one branch is used for discharging finished products, and the other branch is connected with a heat exchanger.

The invention realizes the absorption of the ketene in the liquid ring vacuum pump, and the vacuum degree of the ketene leaving the cracking device can be maintained in the liquid ring vacuum pump, thereby avoiding the occurrence of reverse reaction. And the time of the gas in the pipeline is effectively reduced, the gas directly enters the vacuum pump for internal circulation, the loss is reduced, the absorption reaction is easier to occur, and the product is obtained. Meanwhile, the product is used as working solution, acrolein and cyanohydrin absorption liquid is fed into a pipeline of the working solution, and the absorption solution can be well dispersed by the working solution, so that the absorption efficiency is improved.

Compared with the prior art, the invention has the beneficial effects that:

1) the method uses the liquid circulation vacuum pump as the absorption device, has high absorption efficiency,

the product 1-cyano-2-propenyl acetic ester prepared by the invention has the primary yield (calculated by acrolein cyanohydrin) of 99-99.85% and the product purity of more than 98.5%.

2) The method can complete the absorption reaction only by a liquid circulating vacuum pump, does not need a product post-treatment step, and has low equipment investment.

3) The ketene gas directly enters the liquid circulation vacuum pump for circulation reaction, so that the loss is reduced, and the utilization rate of the ketene is more than 99%.

Drawings

FIG. 1 is a flow chart of the preparation of 1-cyano-2-propenyl acetate.

In the figure:

a-liquid circulating vacuum pump; b, a gas-liquid separation tower; c, a heat exchanger;

1-ketene gas; 2-propenal cyanohydrin; 3-ACA working solution

4-reaction liquid; 5-ACA products; 6-tail gas.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.

Example 1

765kg/h of ACA working solution 3 at 25 ℃ is fed into a liquid circulating vacuum pump A (absolute pressure is 0.02 Mpa) through a working solution inlet;

cooling ketene gas 1 subjected to high-temperature cracking of acetic acid to the temperature of 15 ℃, discharging the ketene gas from a cooler at the absolute pressure of 0.02Mpa at the rate of 17.57kg/h, and sending the ketene gas into a liquid circulating vacuum pump A;

acrolein cyanohydrin 2 is added through a working solution inlet pipeline at 31.05kg/h, is uniformly mixed with ACA working solution 3 and then enters a liquid circulation vacuum pump A, after ketene gas 1 is absorbed, reaction liquid 4 enters a gas-liquid separation tower B at 813.6kg/h, ACA product 5 is discharged from the bottom of the tower at 812.38kg/h, 765kg/h of the reaction liquid is used as working solution and sent to a heat exchanger C, and the ACA working solution 3 is obtained.

The reaction temperature was 35 ℃.

Based on acrolein cyanohydrin, the ACA product content is 98.55%, and the yield is 99.85% (based on acrolein cyanohydrin).

The invention has less ketene loss and the ketene utilization rate is 99.2 percent.

Example 2

Delivering the ACA working solution 3 with the temperature of 20 ℃ into a liquid circulation vacuum pump A (the absolute pressure is 0.04 Mpa) through a working solution inlet at 1759 kg/h;

the ketene gas 1 after the high-temperature cracking of the acetic acid is cooled to the temperature of 5 ℃, the absolute pressure is 0.04Mpa, and the ketene gas is discharged from a cooler 19.77kg/h and sent into a liquid circulating vacuum pump A.

Acrolein cyanohydrin 2 of 35.26kg/h is added through a working solution inlet pipeline, is uniformly mixed with ACA working solution 3 and then enters a liquid circulation vacuum pump A, after ketene gas 1 is absorbed, reaction liquid 4 enters a gas-liquid separation tower B at 1814kg/h, ACA products 5 are discharged from the bottom of the tower at 1812.3kg/h, wherein 1759kg/h is taken as the working solution and sent to a heat exchanger C, and the ACA working solution 3 is obtained.

The reaction temperature was 25 ℃.

Calculated by acrolein cyanohydrin, the content of the ACA product is 98.63 percent, and the yield is 99 percent. The invention has less ketene loss and the ketene utilization rate is 99.3 percent.

The ketene contents of the ketene gases 1 of examples 1 and 2 were ≧ 90%.

Comparative example 1

Ketene gas (the content of ketene is not less than 90%) obtained by high-temperature cracking of acetic acid is cooled, 202.91kg/h enters an absorption tower from the bottom of the tower through a vacuum pump, the feeding temperature is 5 ℃, the pressure is normal, acrolein cyanohydrin is filled in the absorption tower through a spraying device E, the flow rate is 318.5kg/h, the liquid-gas ratio of the acrolein cyanohydrin to the ketene gas is 0.99, the reaction temperature is 25 ℃, the retention time is 3s, ACA product 5 obtained by reaction enters the bottom of the tower, 478.51kg/h enters an ACA storage tank T3, and waste gas enters a waste gas treatment system through gas-liquid separation. The obtained ACA product 5 has ACA content of 96.1% and yield of 95.7% (calculated as acrolein cyanohydrin). Ketene utilization was 84.56%.