Method for improving recovery rate of recovered 1, 3-dichloropropene

Abstract

The invention relates to the technical field of chemical product preparation, and provides a method for improving the recovery rate of recovered 1, 3-dichloropropene, which comprises the following steps: S1, chlorine and propylene are subjected to a chlorination reaction to obtain a chlorination mixture I; s2, performing heavy component removal on the chlorination mixture I to obtain chloropropene and a chlorination mixture II; s3, washing the chlorination mixture II with water, and carrying out extractive distillation to obtain 1, 3-dichloropropene; an extracting agent for extractive distillation is sulfolane and / or N-methyl pyrrolidone. Through the technical scheme, the problem of low recovery rate of 1, 3-dichloropropene in related technologies is solved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical product preparation, and in particular to a method for improving the recovery rate of 1,3-dichloropropylene. Background Art

[0002] As an important chemical raw material, 1,3-dichloropropylene is widely used as a soil fumigant in the agricultural field. It can effectively prevent and control harmful organisms such as nematodes, pathogens and weed seeds in the soil, creating favorable conditions for the healthy growth of crops. In terms of organic synthesis, it is also a key intermediate for the synthesis of a variety of fine chemicals, and is used in the preparation process of many products such as medicines, pesticides, and spices.

[0003] However, the current production and use of 1,3-dichloropropene has a low recovery rate. From the production point of view, the traditional synthesis process, whether it is the high-temperature chlorination method using chloropropene as raw material, or other derivative methods, in the separation and purification stage after the reaction, 1,3-dichloropropene forms a complex mixture system with by-products, unreacted raw materials and solvents, which have similar boiling points and solubility, resulting in a low recovery rate of 1,3-dichloropropene, resulting in a waste of raw materials and increased production costs. Therefore, improving the recovery rate of 1,3-dichloropropene is a problem that needs to be solved at present. Summary of the invention

[0004] The invention provides a method for improving the recovery rate of 1,3-dichloropropylene, which solves the problem of low recovery rate of 1,3-dichloropropylene in the related art.

[0005] The technical solution of the present invention is as follows: The present invention provides a method for improving the recovery rate of 1,3-dichloropropylene, comprising the following steps: S1, subjecting chlorine gas and propylene to a chlorination reaction to obtain a chlorinated mixture I; S2, removing the weight of the chlorinated mixture I to obtain allyl chloride and chlorinated mixture II; S3, washing the chlorinated mixture II with water, extracting and rectifying to obtain 1,3-dichloropropylene; The extractant for the extractive distillation is sulfolane and / or N-methylpyrrolidone.

[0006] As a further technical solution, the extractant is sulfolane and N-methylpyrrolidone.

[0007] In the present invention, the recovery rate of 1,3-dichloropropylene is further improved by using sulfolane and N-methylpyrrolidone as the extractant.

[0008] As a further technical solution, the volume ratio of sulfolane to N-methylpyrrolidone is 5:1-3.

[0009] In the present invention, the recovery rate of 1,3-dichloropropylene is further improved by limiting the volume ratio of sulfolane to N-methylpyrrolidone to 5:1-3.

[0010] As a further technical solution, the water washing temperature is 50-60°C.

[0011] As a further technical solution, the molar ratio of chlorine to propylene is 10:2~3.

[0012] As a further technical solution, the temperature of the chlorination reaction is 450-500° C., and the time of the chlorination reaction is 5-10 seconds.

[0013] As a further technical solution, the volume ratio of the chlorinated mixture II to the extractant is 1:1~1.5.

[0014] In the present invention, the volume ratio of the chlorinated mixture II to the extractant is limited to 1:1-1.5, thereby further improving the recovery rate of 1,3-dichloropropylene.

[0015] As a further technical solution, in step S2, the chlorinated mixture I is cooled to 60-80°C to remove HCl and propylene, and then deweighted to obtain allyl chloride and chlorinated mixture II.

[0016] As a further technical solution, in step S3, the chlorinated mixture II is washed with water, extracted and distilled, and 1,2-dichloropropane is removed by distillation to obtain a mixture of 1,3-dichloropropylene and an extractant.

[0017] As a further technical solution, the distillation temperature is 95-97°C.

[0018] As a further technical solution, the mixture of 1,3-dichloropropylene and the extractant is deweighted to remove the extractant, and the 1,3-dichloropropylene is collected through a side line discharge.

[0019] As a further technical solution, the deweighting temperature is 108-115°C.

[0020] The working principle and beneficial effects of the present invention are: In the present invention, chlorine and propylene are subjected to a chlorination reaction to obtain a chlorinated mixture I, the chlorinated mixture I is subjected to deweighting to obtain chloropropylene and a chlorinated mixture II, and the chlorinated mixture II is then subjected to water washing and extractive distillation to obtain 1,3-dichloropropylene, wherein an extractant composed of cyclopentane and / or N-methylpyrrolidone is added during the extractive distillation to improve the recovery rate of 1,3-dichloropropylene and solve the problem of low recovery rate of 1,3-dichloropropylene. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1 A method for improving the recovery rate of 1,3-dichloropropylene comprises the following steps: S1, chlorine gas and propylene in a molar ratio of 10:2 are subjected to chlorination reaction at 450° C. for 10 seconds to obtain a chlorinated mixture I; S2, cooling the chlorinated mixture I to 60°C to remove HCl and propylene, and then removing the weight to obtain chloropropylene and chlorinated mixture II; wherein the chlorinated mixture II has a 1,2-dichloropropane content of 55% and a 1,3-dichloropropylene content of 29%; S3, washing the chlorinated mixture II with water at 50°C, adding an extractant and mixing, first distilling to remove 1,2-dichloropropane at 95°C, and then rectifying to obtain 1,3-dichloropropylene; then deweighting to remove the extractant at 108°C, and then collecting 1,3-dichloropropylene through a side line; The volume ratio of the chlorinated mixture II to the extractant is 1:2; the extractant is N-methylpyrrolidone.

[0023] Example 2 A method for improving the recovery rate of 1,3-dichloropropylene comprises the following steps: S1, chlorine gas and propylene in a molar ratio of 10:2 are subjected to chlorination reaction at 480° C. for 8 seconds to obtain a chlorinated mixture I; S2, cooling the chlorinated mixture I to 70°C to remove HCl and propylene, and then removing the weight to obtain chloropropylene and chlorinated mixture II; wherein the chlorinated mixture II has a 1,2-dichloropropane content of 54% and a 1,3-dichloropropylene content of 28%; S3, washing the chlorinated mixture II with water at 55°C, adding an extractant and mixing, first distilling off 1,2-dichloropropane at 96°C, and then rectifying to obtain 1,3-dichloropropylene; then deweighting to remove the extractant at 111°C, and then collecting 1,3-dichloropropylene through a side line; The volume ratio of the chlorinated mixture II to the extractant is 1:2; the extractant is N-methylpyrrolidone.

[0024] Example 3 A method for improving the recovery rate of 1,3-dichloropropylene comprises the following steps: S1, chlorine gas and propylene in a molar ratio of 10:3 are subjected to chlorination reaction at 500° C. for 5 seconds to obtain a chlorinated mixture I; S2, cooling the chlorinated mixture I to 80°C to remove HCl and propylene, and then removing the weight to obtain chloropropylene and chlorinated mixture II; wherein the chlorinated mixture II has a 1,2-dichloropropane content of 53% and a 1,3-dichloropropylene content of 30%; S3, washing the chlorinated mixture II with water at 60°C, adding an extractant and mixing, first distilling off 1,2-dichloropropane at 97°C, and then rectifying to obtain 1,3-dichloropropylene; then deweighting to remove the extractant at 115°C, and then collecting 1,3-dichloropropylene through a side line; The volume ratio of the chlorinated mixture II to the extractant is 1:2; the extractant is N-methylpyrrolidone.

[0025] Example 4 The only difference between this embodiment and embodiment 1 is that the extractant is sulfolane.

[0026] Example 5 The only difference between this embodiment and embodiment 1 is that the extractant is sulfolane and N-methylpyrrolidone in a volume ratio of 1:1.

[0027] Example 6 The only difference between this embodiment and embodiment 5 is that the volume ratio of sulfolane to N-methylpyrrolidone is 7:1.

[0028] Example 7 The only difference between this embodiment and embodiment 5 is that the volume ratio of sulfolane to N-methylpyrrolidone is 5:1.

[0029] Example 8 The only difference between this embodiment and embodiment 5 is that the volume ratio of sulfolane to N-methylpyrrolidone is 5:3.

[0030] Example 9 The only difference between this embodiment and embodiment 7 is that the volume ratio of the chlorination mixture II to the extractant is 2:1.

[0031] Example 10 The only difference between this embodiment and embodiment 7 is that the volume ratio of the chlorination mixture II to the extractant is 1:1.

[0032] Embodiment 11 The only difference between this embodiment and embodiment 7 is that the volume ratio of chlorination mixture II to the extractant is 2:3.

[0033] Comparative Example 1 The only difference between this comparative example and Example 1 is that in step S3, after the chlorinated mixture II is washed with water at 60° C., 1,2-dichloropropane is firstly distilled off at 95° C., and then 1,3-dichloropropylene is collected through a side line discharge.

[0034] The recovery rates and purities of 1,3-dichloropropylene obtained in Examples 1 to 11 and Comparative Example 1 are shown in Table 1.

[0035] Table 1 Recovery and purity of 1,3-dichloropropylene

[0036] Compared with Comparative Example 1, an extractant was added in Example 1. As a result, the purity and yield of 1,3-dichloropropene in Example 1 were higher than those in Comparative Example 1, indicating that adding an extractant during the distillation process can improve the purity and yield of 1,3-dichloropropene.

[0037] Compared with Example 1, the composition of the extractant was changed in Examples 4 to 8. As a result, the purity and yield of 1,3-dichloropropene in Examples 5 to 8 were higher than those in Example 1 and Example 4, indicating that when the extractant consisted of sulfolane and N-methylpyrrolidone, the purity and yield of 1,3-dichloropropene could be further improved. By comparing Examples 5 to 8, it was found that the purity and yield of 1,3-dichloropropene in Examples 7 to 8 were higher than those in Examples 5 to 6, indicating that when the volume ratio of sulfolane and N-methylpyrrolidone was 5:1 to 3, the purity and yield of 1,3-dichloropropene could be further improved.

[0038] Compared with Example 7, Examples 9 to 11 changed the amount of the extractant added. As a result, the purity and yield of 1,3-dichloropropene in Examples 10 to 11 were higher than those in Examples 7 and 9, indicating that when the volume ratio of the chlorinated mixture II to the extractant was 1:1 to 1.5, the purity and yield of 1,3-dichloropropene could be further improved.

[0039] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for improving the recovery rate of 1,3-dichloropropylene, characterized in that: The following steps are involved: S1, subjecting chlorine gas and propylene to a chlorination reaction to obtain a chlorinated mixture I; S2, removing the weight of the chlorinated mixture I to obtain allyl chloride and chlorinated mixture II; S3, washing the chlorinated mixture II with water, extracting and rectifying to obtain 1,3-dichloropropylene; The extractant for the extractive distillation is sulfolane and / or N-methylpyrrolidone.

2. A method for improving the recovery rate of 1,3-dichloropropylene according to claim 1, characterized in that: The extracting agents are sulfolane and N-methylpyrrolidone.

3. A method for improving the recovery rate of 1,3-dichloropropylene according to claim 2, characterized in that: The volume ratio of the sulfolane to the N-methylpyrrolidone is 5:1-3.

4. The method for improving the recovery rate of 1,3-dichloropropylene according to claim 1, characterized in that: The water washing temperature is 50-60°C.

5. The method for improving the recovery rate of 1,3-dichloropropylene according to claim 1, characterized in that: The molar ratio of chlorine to propylene is 10:2-3.

6. The method for improving the recovery rate of 1,3-dichloropropylene according to claim 1, characterized in that: The temperature of the chlorination reaction is 450-500°C.

7. The method for improving the recovery rate of 1,3-dichloropropylene according to claim 1, characterized in that: The volume ratio of the chlorinated mixture II to the extractant is 1:1-1.

5.

8. The method for improving the recovery rate of 1,3-dichloropropylene according to claim 1, characterized in that: In step S2, the chlorinated mixture I is cooled to 60-80° C. to remove HCl and propylene, and then subjected to weight removal to obtain allyl chloride and chlorinated mixture II.

9. The method for improving the recovery rate of 1,3-dichloropropylene according to claim 1, characterized in that: In step S3, the chlorinated mixture II is washed with water and subjected to extractive distillation, and 1,2-dichloropropane is removed by distillation to obtain a mixture of 1,3-dichloropropylene and an extractant.

10. A method for improving the recovery rate of 1,3-dichloropropylene according to claim 9, characterized in that: The extractant is removed from the mixture of 1,3-dichloropropylene and the extractant by deweighting, and the 1,3-dichloropropylene is collected through a side line discharge.

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