Method for preparing chloroacetyl chloride by using reaction tower and rectification tower and integrated tower preparation device

Abstract

The invention belongs to the technical field of preparation processes of chemical products, and particularly relates to a method for preparing chloroacetyl chloride through a reaction tower and a rectification tower and an integrated tower preparation device. The invention relates to a method for preparing chloroacetyl chloride by a reaction tower and a rectification tower, which comprises the following steps of: metering liquid chloroacetic acid, preheating the liquid chloroacetic acid by a preheater, metering raw material thionyl chloride, gasifying the raw material thionyl chloride in a gasifier, feeding the gasified raw material thionyl chloride into the bottom of a reaction tower, and reacting the raw material thionyl chloride with the chloroacetic acid from the upper part of the reaction tower in the reaction tower, the tower bottom of the reaction tower is heated by a reboiler; and 2, cooling reaction steam from the reaction tower through a tower top condenser, enabling reflux liquid to enter the tower top of the reaction tower for total reflux, carrying out mass transfer and heat transfer on the steam in the reaction tower, extracting from a side line pipeline, and cooling through a side extraction condenser to obtain the finished product chloroacetyl chloride. According to the method for preparing chloroacetyl chloride through the reaction tower and the rectification tower, energy is saved, consumption is reduced, the product quality is stable, and the purity is high; the invention further provides an integrated tower preparation device which is low in investment and high in efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation technology of chemical products, and specifically relates to a method for preparing chloroacetyl chloride through reaction and rectification tower and an integrated tower preparation device. Background Art

[0002] Chloroacetyl chloride is currently an important organic chemical raw material and is widely used in the fields of pesticides, medicines, dyes and fragrances. However, the traditional preparation method of chloroacetyl chloride has many technical bottlenecks, which limits its large-scale and efficient industrial production.

[0003] One of the traditional methods for preparing chloroacetyl chloride is to use chlorine as a chlorinating agent, chloroacetic acid as a raw material, and sulfur as a catalyst for reaction. However, chlorine is highly reactive as a chlorinating agent and easily reacts with chloroacetic acid to form a byproduct, dichloroacetyl chloride. This byproduct is not only difficult to separate by distillation, but also seriously affects the quality and yield of the product. This not only increases the difficulty of subsequent processing, but also reduces the overall production efficiency.

[0004] In order to overcome the deficiency of chlorine as a chlorinating agent, another preparation method came into being, that is, using chloroacetic acid and thionyl chloride as reactants. Compared with chlorine, the reaction conditions of thionyl chloride as a chlorinating agent are milder, and the by-products are mainly hydrogen chloride and sulfur dioxide. Although this method reduces the generation of by-products to a certain extent, in conventional kettle reactions, more thionyl chloride will still be dissolved in the crude product. The separation of unreacted thionyl chloride and chloroacetyl chloride requires a higher distillation tower and a larger reflux ratio, which not only increases the energy consumption of distillation, but also may lead to unstable product quality. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art and provide a method for preparing chloroacetyl chloride by reaction and distillation in one tower, which saves energy and reduces consumption, has a stable production process, and has stable output product quality and high purity; the present invention also provides an integrated tower preparation device with low investment and high efficiency.

[0006] The method for preparing chloroacetyl chloride by reaction and rectification in one tower of the present invention comprises the following steps:

[0007] In the first step, liquid chloroacetic acid is preheated in a preheater after being metered, and the raw material thionyl chloride is metered and gasified in a gasifier and enters the bottom of a reaction tower, and reacts with chloroacetic acid coming down from the top of the reaction tower in the reaction tower, and the bottom of the reaction tower is heated by a reboiler, and the unreacted chloroacetic acid is returned to the liquid chloroacetic acid feed pipeline for re-metering and reaction;

[0008] In the second step, the reaction steam from the reaction tower is cooled by the top condenser, and the reaction tail gas is separated from the reflux tank and enters the tail gas absorption device. The reflux liquid enters the top of the reaction tower for total reflux. After the steam in the reaction tower undergoes mass and heat transfer, it is extracted from the side line pipeline and then cooled by the side extraction condenser to obtain the finished chloroacetyl chloride.

[0009] In the first step, it is preheated to 110-135°C in a preheater.

[0010] In the first step, gasification is performed in a gasifier to a temperature of 80-135°C.

[0011] In the first step, the feed ratio of chloroacetic acid to thionyl chloride is 1:0.9-1.2.

[0012] In the first step, the temperature is heated to 110-135°C via a reboiler.

[0013] In the second step, the extraction temperature of the distillation section of the reaction tower is controlled at 90-100°C, and the ratio of reflux to side extraction is 3:1-2.

[0014] The method for preparing chloroacetyl chloride by reaction and rectification in one tower adopts an integrated tower preparation device, comprising a gas outlet at the top of a reaction tower connected to a top condenser, the top condenser connected to a reflux tank, the reflux tank connected to the top of the reaction tower, a liquid chloroacetic acid feed pipeline arranged in the reaction tower, a bottom pipeline of the reaction tower divided into two routes, one route returns to the bottom of the reaction tower through a reboiler, and the other route is connected to the liquid chloroacetic acid feed pipeline, and a preheater is arranged on the liquid chloroacetic acid feed pipeline.

[0015] A side line pipeline is arranged on the upper part of the reaction tower, and a side extraction condenser is arranged on the side line pipeline.

[0016] The tank top of the reflux tank is connected to the tail gas absorption device.

[0017] A thionyl chloride pipeline is arranged at the lower part of the reaction tower, and a gasifier is arranged on the thionyl chloride pipeline.

[0018] Specifically, the method for preparing chloroacetyl chloride by reaction and rectification comprises the following steps:

[0019] The first step is that liquid chloroacetic acid is measured by a metering facility and then preheated to 110-135° C. by a preheater (ensuring that the chloroacetyl chloride steam coming from the reaction section is prevented from being cooled by the chloroacetic acid feed and then returned to the tower bottom above the boiling point of chloroacetyl chloride, and simultaneously avoiding reaching the decomposition temperature of thionyl chloride of 140° C.), the raw material thionyl chloride is measured by a metering facility and then gasified to 80-135° C. in a thionyl chloride vaporizer, and then enters the bottom of the reaction tower and reacts with the chloroacetic acid coming from the top in the packing of the reaction section of the reaction tower, the feed ratio of chloroacetic acid: thionyl chloride is 1:0.9-1.2 (the thionyl chloride is under-quantified, ensuring that the thionyl chloride is completely converted, and preventing the thionyl chloride from going up to the rectifying section of the upper section of the reaction tower and causing the product to be unqualified), the tower bottom is heated to 110-135° C. by a reboiler, ensuring that the bottom of the kettle is substantially free of thionyl chloride and chloroacetyl chloride, and according to the tower kettle liquid level control, the chloroacetic acid that has not been reacted is returned to the liquid chloroacetic acid feed pipeline for re-metering and feeding and reaction.

[0020] In the second step, the reaction steam (chloroacetyl chloride, hydrogen chloride, sulfur dioxide) from the reaction section of the reaction tower is cooled by the top condenser, and the reaction tail gas hydrogen chloride and sulfur dioxide are separated from the reflux tank and enter the tail gas absorption device. The reflux liquid is mainly chloroacetyl chloride (dissolved in trace hydrogen chloride and sulfur dioxide) and enters the top of the tower for total reflux. The reflux liquid is extracted from the side line pipeline after mass and heat transfer with the steam in the tower, and then cooled by the side extraction condenser to obtain qualified finished chloroacetyl chloride. The extraction temperature of the rectification section of the reaction tower is controlled at 90-100°C (at this temperature, the trace hydrogen chloride and sulfur dioxide dissolved in the chloroacetyl chloride in the top reflux tank of the tower are evaporated, and at the same time, there is enough chloroacetyl chloride in the side extraction plate to be cooled and extracted).

[0021] The integrated tower preparation device of the present invention, when working, starts the preheater to preheat the liquid chloroacetic acid about to enter the reaction tower to improve the reaction efficiency. Through the liquid chloroacetic acid feed pipeline, the preheated chloroacetic acid is continuously added to the middle part of the reaction tower. At the same time, through the thionyl chloride pipeline and the gasifier, the thionyl chloride is vaporized and introduced into the lower part of the reaction tower, and the chloroacetic acid and thionyl chloride are fully reacted in the gas-liquid countercurrent in the reaction section filler. In the reaction tower, chloroacetic acid and thionyl chloride undergo chlorination reaction to generate chloroacetyl chloride and sulfur dioxide and hydrogen chloride by-products. The steam (containing chloroacetyl chloride, and by-product sulfur dioxide and hydrogen chloride) produced by the reaction rises to the top of the tower. The top steam enters the top condenser and is condensed into a liquid.

[0022] The present invention combines the advantages of equipment innovation, reaction process optimization and efficient distillation mode, and overcomes the problems of difficult separation of by-products, high distillation energy consumption, unstable product quality and the like in the traditional method for preparing chloroacetyl chloride. High-purity chloroacetyl chloride can be produced stably and efficiently, and a new and competitive process scheme is provided for the industrial production of chloroacetyl chloride. In the distillation section of the reaction tower, the present invention strictly controls the feed ratio during the reaction process and relies on the advantages of the tower reactor, so that the impurities of chloroacetyl chloride are only tail gas hydrogen chloride and sulfur dioxide. By adopting the side line extraction method, high-purity chloroacetyl chloride can be effectively extracted from the tower, and tail gas hydrogen chloride and sulfur dioxide are separated from the tower top reflux tank. This distillation method can not only ensure the high purity of the product, but also is simple and efficient to operate, does not require an excessively high distillation tower and a large reflux ratio, further reduces the distillation energy consumption, and also ensures the stability of product quality.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The method for preparing chloroacetyl chloride by reaction and distillation in one tower of the present invention integrates the preparation and distillation processes of chloroacetyl chloride in one tower. Compared with the traditional separation process of preparation first and then distillation, this greatly simplifies the process flow, reduces the number of equipment used and the floor space occupied, reduces the process complexity and equipment investment cost, and at the same time, one tower completes two processes to avoid material transfer loss and energy loss between different equipment, thereby greatly reducing energy consumption and improving production efficiency and economic benefits.

[0025] (2) The method for preparing chloroacetyl chloride in one tower by reaction and rectification of the present invention selects thionyl chloride as the chlorinating agent, which has the advantage that the by-product is easier to handle than chlorine as the chlorinating agent, and strictly controls the feed ratio to ensure that the raw material chloroacetic acid is excessive, so that the thionyl chloride can be fully reacted, the unreacted thionyl chloride residue is reduced, and the problem of subsequent distillation difficulty and product quality degradation caused by the thionyl chloride residue is avoided.

[0026] (5) The integrated tower preparation device of the present invention utilizes the characteristic of low back mixing of the tower reactor to enable thionyl chloride to participate in the reaction more completely. In the tower reactor, the flow of materials is more orderly and stable, and the reaction is more complete and uniform, thereby improving the conversion rate and selectivity of the reaction, reducing the generation of by-products, and further improving the quality and yield of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the integrated tower preparation device of chloroacetyl chloride of the present invention.

[0028] In the figure: 1. Reflux tank; 2. Top condenser; 3. Reaction tower; 4. Side sampling condenser; 5. Vaporizer; 6. Preheater; 7. Reboiler; 8. Liquid chloroacetic acid feed pipeline; 9. Side line pipeline; 10. Tail gas absorption device; 11. Sulfoxide chloride pipeline. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific embodiments.

[0030] The devices used in the following embodiments are as follows: Figure 1 As shown, the method for preparing chloroacetyl chloride by reaction and distillation in one tower adopts an integrated tower preparation device, which includes a reaction tower 3, the gas outlet at the top of the reaction tower 3 is connected to the top condenser 2, the top condenser 2 is connected to the reflux tank 1, the reflux tank 1 is connected to the top of the reaction tower 3, a liquid chloroacetic acid feed pipeline 8 is arranged in the reaction tower 3, the bottom pipeline of the reaction tower 3 is divided into two paths, one path returns to the bottom of the reaction tower 3 through the reboiler 7, and the other path is connected to the liquid chloroacetic acid feed pipeline 8, and the liquid chloroacetic acid feed pipeline 8 is provided with a preheater 6.

[0031] A side line pipeline 9 is arranged at the upper part of the reaction tower 3 , and a side extraction condenser 4 is arranged on the side line pipeline 9 .

[0032] The tank top of the reflux tank 1 is connected to the tail gas absorption device 10 .

[0033] The lower part of the reaction tower 3 is provided with a thionyl chloride pipeline 11, and the thionyl chloride pipeline 11 is provided with a vaporizer 5. The reaction tower used in the present invention is an existing conventional reaction tower, and the internal structures such as the distillation section and the reaction section are all existing structures and are not described in detail.

[0034] Example 1

[0035] The method for preparing chloroacetyl chloride by reaction and rectification comprises the following steps:

[0036] In the first step, liquid chloroacetic acid is measured by a metering facility and preheated to 120° C. by a preheater 6. The raw material thionyl chloride is measured by a metering facility and gasified to 100° C. in a thionyl chloride gasifier 5, and then enters the bottom of a reaction tower 3 and reacts with the chloroacetic acid coming down from the top in a reaction section packing of the reaction tower 3. The feed ratio of chloroacetic acid: thionyl chloride is 1:0.9. The bottom of the tower is heated to 110° C. by a reboiler 7 to ensure that the bottom of the kettle is substantially free of thionyl chloride and chloroacetyl chloride. According to the tower kettle liquid level control, the chloroacetic acid that has not been reacted is returned to the liquid chloroacetic acid feed pipeline 8 for re-metering and reaction.

[0037] In the second step, the reaction steam (chloroacetyl chloride, hydrogen chloride, sulfur dioxide) from the reaction section of the reaction tower 3 is cooled by the tower top condenser 2, and the reaction tail gas hydrogen chloride and sulfur dioxide are separated from the reflux tank 1 and enter the tail gas absorption device 10. The reflux liquid is mainly chloroacetyl chloride (dissolved in trace amounts of hydrogen chloride and sulfur dioxide) and enters the tower top for total reflux. After mass and heat transfer, the steam in the tower is extracted in the side line pipeline 9 and cooled by the side extraction condenser 4 to obtain qualified finished chloroacetyl chloride, with a sulfur dioxide content of 0.007% and a purity of 99.94%, a dichloroacetyl chloride content of 0.015%, a side extraction temperature controlled at 90° C., a chloroacetic acid content of 0.006%, and a reflux to side extraction ratio of 3:1.

[0038] Example 2

[0039] The method for preparing chloroacetyl chloride by reaction and rectification comprises the following steps:

[0040] The first step: liquid chloroacetic acid is preheated to 125°C by a preheater 6 after being measured by a metering facility, and the raw material thionyl chloride is vaporized to 110°C in a thionyl chloride vaporizer 5 after being measured by a metering facility and enters the bottom of a reaction tower 3, and reacts with chloroacetic acid coming down from the upper part in the packing of the reaction section of the reaction tower 3, and the feed ratio of chloroacetic acid: thionyl chloride is 1:1. The bottom of the tower is heated to 120°C by a reboiler 7, and the unreacted chloroacetic acid is returned to the liquid chloroacetic acid feed pipeline 8 according to the tower kettle liquid level control for re-metering, feeding, and reaction.

[0041] Step 2: After the reaction steam is cooled by the tower top condenser 2, the tail gas is separated from the reflux tank 1 and enters the tail gas absorption device 10, the reflux liquid is fully refluxed, and the steam in the tower is extracted in the side line pipeline 9 after mass and heat transfer, and cooled by the side extraction condenser 4 to obtain the finished chloroacetyl chloride, with a purity of 99.92%, a sulfur dioxide content of 0.005%, and a dichloroacetyl chloride content of 0.018%. The side extraction temperature is controlled at 95°C, the chloroacetic acid content is 0.007%, and the reflux to side extraction ratio is 3:1.5.

[0042] Example 3

[0043] The method for preparing chloroacetyl chloride by reaction and rectification comprises the following steps:

[0044] The first step: liquid chloroacetic acid is preheated to 130°C by a preheater 6 after being measured by a metering facility, and the raw material thionyl chloride is gasified to 120°C in a thionyl chloride gasifier 5 after being measured by a metering facility and enters the bottom of a reaction tower 3, and reacts with chloroacetic acid coming down from the upper part in the packing of the reaction section of the reaction tower 3, and the feed ratio of chloroacetic acid: thionyl chloride is 1:1.1, and the bottom of the tower is heated to 125°C by a reboiler 7, and the unreacted chloroacetic acid is returned to the liquid chloroacetic acid feed pipeline 8 according to the tower kettle liquid level control for re-metering and reaction.

[0045] Step 2: After the reaction steam is cooled by the tower top condenser 2, the tail gas is separated from the reflux tank 1 and enters the tail gas absorption device 10. The reflux liquid is fully refluxed, and the steam in the tower is extracted in the side line pipeline 9 after mass and heat transfer. The finished product chloroacetyl chloride is cooled by the side sampling condenser 4, with a purity of 99.93%, a sulfur dioxide content of 0.002%, and a dichloroacetyl chloride content of 0.023%. The side sampling temperature is controlled at 98°C, the chloroacetic acid content is 0.009%, and the reflux to side sampling ratio is 3:2.

[0046] Comparative Example 1

[0047] This comparative example is the same as Example 1, except that the gasification temperature of the raw material thionyl chloride in the thionyl chloride gasifier 5 in the first step is changed to 60° C., and other conditions remain unchanged. The obtained finished chloroacetyl chloride has a purity of 98.5%, a thionyl chloride content of 0.3%, a sulfur dioxide content of 0.03%, a dichloroacetyl chloride content of 0.035%, and a chloroacetic acid content of 0.007%.

[0048] Comparative Example 2

[0049] This comparative example is the same as Example 1, except that the feed ratio of chloroacetic acid to thionyl chloride in the first step is changed to 1:1.3, and other conditions remain unchanged. The purity of the obtained finished chloroacetyl chloride is 98.5%, the content of sulfur dioxide is 0.025%, the content of thionyl chloride is 0.1%, the content of dichloroacetyl chloride is 0.028%, and the content of chloroacetic acid is 0.006%.

[0050] Comparative Example 3

[0051] This comparative example is the same as Example 1, except that the extraction temperature of the side line pipeline 9 in the second step is controlled at 85° C., and other conditions remain unchanged. The purity of the obtained finished chloroacetyl chloride is 98.9%, the content of sulfur dioxide is 0.1%, the content of dichloroacetyl chloride is 0.014%, and the content of chloroacetic acid is 0.007%.

[0052] Comparative Example 4

[0053] The traditional separation process of preparation followed by distillation is adopted, that is, after chloroacetic acid and thionyl chloride react in a tank reactor, the reaction product is transferred to a distillation tower for distillation. The specific operation is as follows: in a tank reactor, chloroacetic acid and thionyl chloride are added in a ratio of 1:1.05, react at a certain temperature, and after the reaction is completed, the product is transferred to a distillation tower, and chloroacetyl chloride is obtained through complex distillation operations. The purity is 98.0%, the sulfur dioxide content is 0.05%, the thionyl chloride content is 0.05%, the dichloroacetyl chloride content is 0.025%, and the chloroacetic acid content is 0.02%.

[0054] Comparative Example 5

[0055] The traditional preparation method uses chlorine as a chlorinating agent, chloroacetic acid as a raw material, and sulfur as a catalyst. The specific operation is as follows: add chloroacetic acid and sulfur into a reaction container, introduce chlorine to react, and perform post-treatment after the reaction to obtain chloroacetyl chloride. The purity is 99.3%, dichloroacetyl chloride is 0.55%, and chloroacetic acid content is 0.03%.

[0056] Of course, the above contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the embodiments of the present invention. The present invention is not limited to the above examples, and equal changes and improvements made by ordinary technicians in the technical field within the essential scope of the present invention should all fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing chloroacetyl chloride by reaction and rectification, characterized in that: The following steps are involved: In the first step, liquid chloroacetic acid is preheated by a preheater (6) after being metered, and the raw material thionyl chloride is vaporized by a vaporizer (5) after being metered and then enters the bottom of a reaction tower (3) to react with chloroacetic acid coming down from the top of the reaction tower (3) in the reaction tower (3), and the bottom of the reaction tower (3) is heated by a reboiler (7), and the unreacted chloroacetic acid is returned to a liquid chloroacetic acid feed pipeline (8) for re-metering and reaction; In the second step, the reaction steam from the reaction tower (3) is cooled by the tower top condenser (2), the reaction tail gas is separated from the reflux tank (1) and enters the tail gas absorption device, the reflux liquid enters the tower top of the reaction tower (3) for total reflux, the steam in the reaction tower (3) is subjected to mass transfer and heat transfer, and then is extracted from the side line pipeline (9), and then cooled by the side extraction condenser (4) to obtain the finished chloroacetyl chloride.

2. The method for preparing chloroacetyl chloride by reaction and rectification tower according to claim 1, characterized in that: In the first step, the mixture is preheated to 110-135°C in a preheater (6).

3. The method for preparing chloroacetyl chloride by reaction and rectification tower according to claim 1, characterized in that: In the first step, gasification is performed in a gasifier (5) to a temperature of 80-135°C.

4. The method for preparing chloroacetyl chloride by reaction and rectification tower according to claim 1, characterized in that: In the first step, the feed ratio of chloroacetic acid to thionyl chloride is 1:0.9-1.

2.

5. The method for preparing chloroacetyl chloride by reaction and rectification tower according to claim 1, characterized in that: In the first step, the mixture is heated to 110-135°C via a reboiler (7).

6. The method for preparing chloroacetyl chloride by reaction and rectification tower according to claim 1, characterized in that: In the second step, the extraction temperature of the distillation section of the reaction tower (3) is controlled at 90-100°C, and the ratio of reflux to side extraction is 3:1-2.

7. An integrated tower preparation device used in the method for preparing chloroacetyl chloride by reaction, rectification and one tower according to any one of claims 1 to 6, characterized in that: The invention comprises a reaction tower (3), wherein the gas outlet at the top of the reaction tower (3) is connected to a tower top condenser (2), the tower top condenser (2) is connected to a reflux tank (1), the reflux tank (1) is connected to the top of the reaction tower (3), a liquid chloroacetic acid feed pipeline (8) is arranged in the reaction tower (3), the bottom pipeline of the reaction tower (3) is divided into two paths, one path returns to the bottom of the reaction tower (3) through a reboiler (7), and the other path is connected to the liquid chloroacetic acid feed pipeline (8), and a preheater (6) is arranged on the liquid chloroacetic acid feed pipeline (8).

8. The integrated tower preparation device used in the method for preparing chloroacetyl chloride by reaction, rectification and one tower according to claim 7, characterized in that: A side line pipeline (9) is arranged at the upper part of the reaction tower (3), and a side extraction condenser (4) is arranged on the side line pipeline (9).

9. The integrated tower preparation device used in the method for preparing chloroacetyl chloride by reaction, rectification and one tower according to claim 7, characterized in that: The tank top of the reflux tank (1) is connected to the tail gas absorption device (10).

10. The integrated tower preparation device used in the method for preparing chloroacetyl chloride by reaction, rectification and one tower according to claim 7, characterized in that: A thionyl chloride pipeline (11) is arranged at the lower part of the reaction tower (3), and a gasifier (5) is arranged on the thionyl chloride pipeline (11).

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