Preparation method of 1, 1, 2, 3-tetrachloropropene

Abstract

The invention provides a preparation method of 1, 1, 2, 3-tetrachloropropene, which comprises the following steps: dehydrating a dehydrochlorination product of pentachloropropane and then isomerizing, and using cheap anhydrous ferric trichloride as a catalyst; filtering an isomerization product, adding quenching liquid, stirring, mixing and quenching; filtering, layering, washing with water, removing water, removing light components and rectifying to obtain a 1, 1, 2, 3-tetrachloropropene product; the technical scheme provided by the invention is suitable for continuous treatment operation, can solve the inherent defects of a supported catalyst, does not need to replace the catalyst or stop, and can run throughout the year; a small amount of ferric chloride in the isomerization reaction liquid with most of the catalyst filtered out is converted into flocculent ferric hydroxide through quenching liquid, a small amount of tar generated in the isomerization reaction liquid is adsorbed through the flocculation effect of aluminum hydroxide and ferric hydroxide, and the isomerization reaction liquid is further purified; no side reaction is generated in the light component removal rectification process, so that the problem that the yield is influenced due to the increase of the tar content can be thoroughly solved.

Description

Technical Field

[0001] This invention belongs to the field of fine chemicals, specifically relating to a method for preparing 1,1,2,3-tetrachloropropene. Background Technology

[0002] 1,1,2,3-Tetrachloropropene is an important chemical intermediate used in the preparation of the herbicide chlorpyrifos, as well as in the production of 2-chloro-3,3,3-trifluoropropene (CFC-1233xf), 1,3,3,3-tetrafluoro-1-propene (HFO-1234ze), 1,1,1,2,3-pentafluoropropane (HFC-245eb), 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), 2,3,3,3-tetrafluoropropene (HFO-1234yf), and 2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db). Among these, HFO-1234yf, as a new generation of environmentally friendly fluorinated refrigerant, is characterized by an ODP value of 0 and a low GWP value, and is therefore considered the most promising fourth-generation refrigerant. Its application in automotive air conditioning systems has also gained global recognition.

[0003] Currently, 1,1,2,3-tetrachloropropene mainly follows three routes depending on the raw materials: carbon tetrachloride, 1,2,3-trichloropropane, and 1,3-dichloropropene. The 1,3-dichloropropene route has a certain cost advantage because the raw material is a byproduct of the preparation of 3-chloropropene, which is cheaper.

[0004] Both patents CN116444339A and CN116194430A report the preparation of tetrachloropropene using 1,3-dichloropropene as a raw material, through two chlorination and dehydrochlorination reactions, isomerization, distillation, and separation processes. After the first chlorination and dehydrochlorination process, 1,3-dichloropropene yields mixed trichloropropene. The mixed trichloropropene undergoes a second chlorination to obtain pentachloropropane. The pentachloropropane then undergoes a second dehydrochlorination process to yield a mixture of 1,1,2,3-tetrachloropropene and 2,3,3,3-tetrachloropropene. By adding a Lewis acid catalyst for isomerization, 2,3,3,3-tetrachloropropene can be transposed to yield 1,1,2,3-tetrachloropropene.

[0005] Based on patents CN116444339A and CN116194430A, patent CN119019220A further employs an oil-water separator to dehydrate the pentachloropropane dehydrochlorination product after the secondary dehydrochlorination process, obtaining a dehydrated tetrachloropropene mixture, thereby avoiding the generation of the byproduct 2,3,3-trichloropropenal impurity. The use of a supported ferric chloride catalyst prevents the catalyst from dissolving and remaining in the system at the end of the isomerization reaction, which would otherwise lead to a continuous increase in trichloropropenal and heavy component impurities during subsequent distillation, resulting in increased tar content, significantly affecting product quality and reducing the overall yield.

[0006] Supported catalysts have inherent drawbacks. The main problem is that after the catalyst is gradually lost, it is difficult to replace, requiring a shutdown for treatment. This also increases the cost of the catalyst. Furthermore, the lost catalyst will lead to a continuous increase in heavy component impurities during subsequent distillation. This technical solution does not completely solve the problem of increased tar content affecting yield. Summary of the Invention

[0007] Based on the technical solution of patent CN119019220A, in order to completely solve the problems described in the background art, the present invention provides the following technical solution: A method for preparing 1,1,2,3-tetrachloropropene includes the following steps: S1: The dehydrochlorination product of pentachloropropane is dehydrated using a multi-stage oil-water separator to obtain a dehydrated tetrachloropropene mixture. S2: The dehydrated tetrachloropropylene mixture is sent to an isomerization reactor and isomerization reaction is carried out in the presence of anhydrous ferric chloride catalyst. S3: After filtering the isomerization product, send it to the quenching kettle, add quenching solution, stir and mix to quench, wherein the quenching solution is an aluminum hydroxide suspension; S4: Filter the quenched product, separate the oil and water, wash the oil layer with water, separate the layers again to obtain a secondary oil layer; S5: Use a multi-stage oil-water separator to remove water from the secondary oil layer to obtain a dehydrated oil layer; S6: Pump the dehydrated oil layer into the light component removal tower to remove light components, and pump the light component removal bottom liquid into the distillation tower to obtain 1,1,2,3-tetrachloropropylene product by distillation.

[0008] Furthermore, the conditions for the isomerization reaction in S2 are: the catalyst is 0.2 wt% anhydrous FeCl3, and the reaction temperature is 90 °C.

[0009] Furthermore, the quenching solution described in S3 is prepared by adding solid aluminum hydroxide, 10% ammonia water and water in a mass ratio of 1:1:18 and mixing them with a high-speed shear emulsifier at a stirring speed of 15,000 rpm.

[0010] Furthermore, the amount of quenching fluid used in S3 is 3%–5% of the mass of the isomerized product after filtration.

[0011] Furthermore, in S4, the oil layer is washed with water, wherein the amount of washing water is 5% of the oil layer mass.

[0012] The beneficial effects of this invention are: This invention provides a method for preparing 1,1,2,3-tetrachloropropene. The method involves dehydrating the dehydrochlorination product of pentachloropropane using a multi-stage oil-water separator, followed by isomerization. The catalyst used is inexpensive anhydrous ferric chloride. After filtration, the isomerized product is quenched by stirring with a quenching solution. The quenched product is then filtered, resulting in oil-water separation. The oil layer is washed with water, and a second oil layer is dehydrated using a multi-stage oil-water separator. Finally, the dehydrated oil layer is pumped into a light component removal tower to remove light components, and the light component removal solution is pumped into a distillation column to obtain the 1,1,2,3-tetrachloropropene product. This invention provides a solution suitable for continuous processing, overcoming the inherent defects of supported catalysts. It eliminates the need for catalyst replacement and shutdown, allowing for year-round operation. A quenching solution converts the small amount of ferric chloride in the isomerization reaction solution (from which most of the catalyst has been filtered) into flocculent ferric hydroxide. The flocculation effect of aluminum hydroxide and ferric hydroxide further adsorbs the small amount of tar produced in the isomerization reaction solution, purifying it. Water washing removes trace amounts of water-soluble salts from the isomerization reaction solution, preventing corrosion of downstream equipment. After dehydration, light distillation yields 1,1,2,3-tetrachloropropylene. Because the isomerization reaction solution contains no catalyst or water, no side reactions occur during light distillation, thus completely resolving the problem of increased tar content affecting yield. Detailed Implementation

[0013] To make the technical means, features and effects of the present invention easier to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with specific implementation methods and embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0014] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0015] Example 1 The preparation method of 1,1,2,3-tetrachloropropene includes the following steps: S1: The dehydrochlorination product of pentachloropropane is dehydrated using a multi-stage oil-water separator to obtain a dehydrated tetrachloropropene mixture. The contents of the dehydrochlorination products of pentachloropropane were as follows: trichloropropene mass concentration 0.1%, 2,3,3,3-tetrachloropropene mass concentration 39.3%, 1,1,2,3-tetrachloropropene mass concentration 59.0%, 1,2,3,3-tetrachloropropene mass concentration 0.2%, trichloropropenaldehyde not detected, pentachloropropene mass concentration 0.6%, heavy component mass concentration 0.3%, and water mass concentration 0.5%. The composition of the tetrachloropropene mixture after dehydration was as follows: trichloropropene mass concentration 0.1%, 2,3,3,3-tetrachloropropene mass concentration 39.5%, 1,1,2,3-tetrachloropropene mass concentration 59.3%, 1,2,3,3-tetrachloropropene mass concentration 0.2%, trichloropropenaldehyde not detected, pentachloropropene mass concentration 0.6%, heavy component mass concentration 0.3%, and water mass concentration 19 ppm. S2: The dehydrated tetrachloropropylene mixture is sent to an isomerization reactor and an isomerization reaction is carried out in the presence of anhydrous ferric chloride catalyst. The amount of catalyst used is 0.2 wt%, and the reaction temperature is 90°C. The isomerization reaction yielded a crude tetrachloropropene product with the following composition: trichloropropene mass concentration 0.1%, 2,3,3,3-tetrachloropropene mass concentration 0.01%, 1,1,2,3-tetrachloropropene mass concentration 98.2%, 1,2,3,3-tetrachloropropene mass concentration 0.2%, trichloropropenal 0.01%, pentachloropropene mass concentration 0.6%, heavy component mass concentration 0.7%, water mass concentration 5 ppm, iron ion mass concentration 0.12%, with an inversion reaction conversion rate of 99.9% and a selectivity of 99.0%. S3: After filtering the isomerization product, send it to the quenching kettle, add quenching solution, stir and mix to quench, wherein the quenching solution is an aluminum hydroxide suspension; The quenching solution is prepared as follows: solid aluminum hydroxide, 10% ammonia water, and water are added in a mass ratio of 1:1:18, and mixed using a high-speed shear emulsifier at a stirring speed of 15,000 rpm; the amount of quenching solution used is 3%–5% of the mass of the isomerization product after filtration. S4: Filter the quenched product, separate the oil and water, wash the oil layer with water, separate the layers again to obtain a secondary oil layer; The solid obtained by filtration is a brown product obtained by flocculation, which contains ferric hydroxide, aluminum hydroxide, water, tar adsorbed by flocculation, and a small amount of other organic matter. The amount of washing water used is 5% of the oil layer mass; the water layers are merged and sent to the wastewater section; The secondary oil layer consisted of 0.06% trichloropropene, no detectable 2,3,3,3-tetrachloropropene, 98.94% 1,1,2,3-tetrachloropropene, 0.1% 1,2,3,3-tetrachloropropene, no detectable trichloropropenal, 0.34% pentachloropropene, 0.06% heavy components, 0.5% water, and no detectable iron ions. S5: Use a multi-stage oil-water separator to remove water from the secondary oil layer to obtain a dehydrated oil layer; The composition of the dehydrated oil layer was 0.06% trichloropropene, 2,3,3,3-tetrachloropropene was not detected, 1,1,2,3-tetrachloropropene had a mass concentration of 99.44%, 1,2,3,3-tetrachloropropene had a mass concentration of 0.1%, pentachloropropene had a mass concentration of 0.34%, heavy components had a mass concentration of 0.06%, and water had a mass concentration of 20 ppm. S6: Pump the dehydrated oil layer into the light component removal tower to remove light components, and pump the light component removal bottom liquid into the distillation tower to obtain 1,1,2,3-tetrachloropropylene product by distillation; The light component removal tower had 50 theoretical plates. The absolute pressure at the top of the light component removal tower was controlled at 5 kPa, and the reflux ratio was 25. The composition of the light component at the top of the tower was as follows: trichloropropene mass concentration 4.2%, 2,3,3,3-tetrachloropropene mass concentration 0.2%, 1,1,2,3-tetrachloropropene mass concentration 87.02%, 1,2,3,3-tetrachloropropene mass concentration 8.5%, trichloropropenaldehyde was not detected, pentachloropropene was not detected, heavy components were not detected, and water mass concentration was 0.08%. The liquid from the light residue removal vessel was pumped into a distillation column with 35 theoretical plates. The absolute pressure at the top of the distillation column was controlled at 5 kPa, and the reflux ratio was 3. The product collected from the top of the column was 1,1,2,3-tetrachloropropene, with the following composition: trichloropropene mass concentration 4 ppm, 2,3,3,3-tetrachloropropene mass concentration 6 ppm, 1,1,2,3-tetrachloropropene mass concentration 99.97%, 1,2,3,3-tetrachloropropene mass concentration 30 ppm, trichloropropenaldehyde not detected, pentachloropropene mass concentration 10 ppm, heavy components not detected, water mass concentration 4 ppm, and the total yield of the product was 97.7%.

[0016] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing 1,1,2,3-tetrachloropropene, characterized in that, Includes the following steps: S1: The dehydrochlorination product of pentachloropropane is dehydrated using a multi-stage oil-water separator to obtain a dehydrated tetrachloropropene mixture. S2: The dehydrated tetrachloropropylene mixture is sent to an isomerization reactor and isomerization reaction is carried out in the presence of anhydrous ferric chloride catalyst. S3: After filtering the isomerization product, send it to the quenching kettle, add quenching solution, stir and mix to quench, wherein the quenching solution is an aluminum hydroxide suspension; S4: Filter the quenched product, separate the oil and water, wash the oil layer with water, separate the layers again to obtain a secondary oil layer; S5: Use a multi-stage oil-water separator to remove water from the secondary oil layer to obtain a dehydrated oil layer; S6: Pump the dehydrated oil layer into the light component removal tower to remove light components, and pump the light component removal bottom liquid into the distillation tower to obtain 1,1,2,3-tetrachloropropylene product by distillation.

2. The method for preparing 1,1,2,3-tetrachloropropene as described in claim 1, characterized in that, The conditions for the isomerization reaction in S2 are: 0.2 wt% anhydrous FeCl3 as catalyst and 90 °C as reaction temperature.

3. The method for preparing 1,1,2,3-tetrachloropropene as described in claim 1, characterized in that, The quenching solution described in S3 is prepared by adding solid aluminum hydroxide, 10% ammonia water and water in a mass ratio of 1:1:18 and mixing them with a high-speed shear emulsifier at a stirring speed of 15,000 rpm.

4. The method for preparing 1,1,2,3-tetrachloropropene as described in claim 1, characterized in that, The amount of quenching fluid used in S3 is 3%–5% of the mass of the isomerized product after filtration.

5. The method for preparing 1,1,2,3-tetrachloropropene as described in claim 1, characterized in that, In S4, the oil layer is washed with water, and the amount of water used for washing is 5% of the oil layer mass.