CN115108885B - Production process for co-production of chloroethanol and dichloroethane - Google Patents

Production process for co-production of chloroethanol and dichloroethane Download PDF

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CN115108885B
CN115108885B CN202210764660.1A CN202210764660A CN115108885B CN 115108885 B CN115108885 B CN 115108885B CN 202210764660 A CN202210764660 A CN 202210764660A CN 115108885 B CN115108885 B CN 115108885B
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chloroethanol
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CN115108885A (en
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吕建华
刘继东
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Hebei University of Technology
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    • C07C29/62—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by introduction of halogen; by substitution of halogen atoms by other halogen atoms
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    • C—CHEMISTRY; METALLURGY
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Abstract

The invention discloses a production process for co-production of chlorohydrin and dichloroethane, which uses ethylene glycol as a raw material, adopts a novel process technology, uses a homogeneous catalyst, and simultaneously produces chlorohydrin and dichloroethane products.

Description

Production process for co-production of chloroethanol and dichloroethane
Technical Field
The invention relates to a production process system for co-producing chlorohydrin and dichloroethane by hydrochlorination and dehydration reaction of ethylene glycol and hydrogen chloride as raw materials, which is a novel green production process, and can not only convert ethylene glycol into chlorohydrin which is a raw material of ethylene oxide, but also convert ethylene glycol into dichloroethane which is a basic chemical raw material of bulk polyvinyl chloride, thereby developing a novel method for converting ethylene glycol into polyvinyl chloride.
Background
Ethylene glycol (EG for short) is used for polyester production in more than 9 products in downstream applications. With the rapid development of the polyester industry in China, the domestic ethylene glycol demand is greatly improved. Another main application field of the industrial grade of ethylene glycol is as an antifreezing solution, an deicing agent, a heat transfer solution and the like.
The dichloroethane is mainly used as raw materials of chloroethylene, ethylene glycol, oxalic acid, ethylenediamine, tetraethyl lead, polyethylene polyamine and dibenzoyl, and also used as solvents of grease, resin and rubber, dry cleaning agent, extractant for removing the components of the pesticide such as the feverfew, caffeine, vitamins and hormone, wetting agent, penetrating agent, petroleum dewaxing and shock-proof agent, and also used as raw materials of pesticide manufacturing and medicines such as the feverfew and the piperaquine.
Chloroethanol (2-chloroethanol) is an important organic solvent and organic synthetic raw material. Chlorohydrin is used for the production of intermediates for the manufacture of ethylene oxide, synthetic rubber, dyes, medicines, pesticides and the like, and is also used as an organic solvent.
Researchers are devoting themselves to the research on the conversion of ethylene glycol into high-value chemicals, and the preparation of chloroethanol and dichloroethane by the chlorination process using ethylene glycol as a raw material is one process route. Dichloroethane is also an important raw material for the production of polyvinyl chloride, so how to more efficiently convert ethylene glycol into chloroethanol and dichloroethane is a key problem in the research.
At present, although the target products are chlorohydrin and dichloroethane, in practice, the method for preparing chlorohydrin and dichloroethane by chlorination of ethylene glycol is a complex series-connection and reversible reaction process, specifically, the hydrochlorination reaction of ethylene glycol and hydrogen chloride comprises two steps of series-connection reversible reaction, and the reaction speed of chlorohydrin in the product generated by hydrochlorination of ethylene glycol and hydrogen chloride is about 10 times that of the product generated by hydrochlorination of ethylene glycol and hydrogen chloride; in addition, in the existing preparation method, the ethylene glycol chlorination process mainly uses organic acid as a catalyst, and the catalyst consumption is large due to the characteristics of difficult recovery and difficult separation of the organic acid, and the conversion rate of the ethylene glycol is greatly influenced.
The invention takes ethylene glycol as raw material, adopts a novel process technology, uses a homogeneous catalyst, and simultaneously produces chlorohydrin and dichloroethane, and the process has the advantages of less discharge of three wastes and high product yield, is a novel green production process, and has high reaction conversion rate and more complete raw material reaction, thereby well solving the technical problems.
Disclosure of Invention
The invention aims to provide a combined production device of chlorohydrin and dichloroethane, and the production device can simultaneously obtain chlorohydrin and dichloroethane products.
A chlorohydrin and dichloroethane co-production process, it regards ethylene glycol and hydrogen chloride as raw materials, this process mainly includes the first chloridizing section, second chloridizing section and three stages of processes of rectifying separation section; and a homogeneous catalyst is used in the reaction.
Further, the homogeneous catalyst is complex salt, which takes triphenylphosphine as a complex carrier and halogenated salt as an active component; the mass concentration of the complex salt catalyst in the reaction material is 1-10%.
Further, the active component is one or more than two mixed components of halide salts; the catalyst composition is that the mole ratio of triphenylphosphine to halide salt is 1:1-3:1.
Further, the first chlorination section and the second chlorination section adopt a reaction mode of combining tubular jet (reactor) with tower (reactor) type (chlorination tower); the top of the chlorination tower is provided with a gas-liquid separator, and the lower part of the chlorination tower is composed of a reaction tower and a circulating pipe; the rectification separation section adopts a two-tower coupling rectification process to separate and obtain high-purity chloroethanol and dichloroethane, and the two towers are an azeotropic tower and a dehydration tower.
Wherein, the first chlorination section is: after the ethylene glycol and the circulating ethylene glycol with the catalyst are preheated and mixed, the ethylene glycol and the HCl gas conveyed by a circulating gas separator are mixed, and are subjected to mixed circulating reaction of raw materials in various modes by a mixing jet pump with fresh HCl, and enter a first chlorination tower through a gas separator to continue reaction; after the reaction of the gas separator, the gas-liquid mixture and the corresponding raw materials such as HCl enter different units of a chlorination tower, and continue to react in the tower; after the materials are separated from the reaction tower, unreacted HCl returns to the mixed jet pump for reaction through cyclic separation treatment and the like; the liquid after reaction realizes the cyclic reaction through a circulating pipe; and separating the bottom liquid by a separator to obtain chloroethanol and dichloroethane crude products.
The second chlorination section is: firstly, fresh HCl and ethylene glycol or chlorohydrin enter an HCl jet pump to enable the ethylene glycol or chlorohydrin to continuously carry out chlorination reaction, then enter an exhaust jet pump together with HCl conveyed by a circulating gas separator, enter a jet reactor, finally enter a second chlorination tower to react, a liquid phase product obtained at the bottom of the tower is sent into a first chlorination tower, and the rest components are subjected to post-treatment and emptying or VOCs treatment.
Regarding the second chlorination stage, the product yield of the chlorohydrin and the dichloroethane can be adjusted according to production requirements, and the chlorohydrin yield can be improved when ethylene glycol raw material is fed into an HCl jet pump; if the chlorohydrin raw material is fed, the dichloroethane yield is improved.
The rectification separation section comprises the steps of feeding the mixed product and the crude product into an azeotropic tower, realizing reflux and separation through a tower top condenser, an azeotropic tower reflux tank, an azeotropic tower reflux pump and the like, and obtaining high-purity dichloroethane at the bottom of the EDC; pumping the material at the bottom of the azeotropic tower into a dehydration tower by an azeotropic tower kettle pump, and obtaining an azeotrope of chlorohydrin and water at the top of the tower, and a chlorohydrin crude product; and (3) carrying out solvent post-treatment on the chlorohydrin crude product to obtain the high-purity 2-chlorohydrin.
Preferably, the solvent is benzene or cyclohexane, etc.; the post-treatment means comprises dehydration with water, desolventizing and vacuum rectification of the solvent.
Regarding the rectifying separation section, the purity of the finally obtained 2-chloroethanol is more than 99 percent after treatment; the purity of dichloroethane is 99% or more, preferably 99.7% or more.
The reaction sections are specifically described below.
The chlorination reaction takes place in the chlorination section, and the reaction formula is as follows:
the first step of reaction:
Figure GDA0003811637450000031
and the second step of reaction:
Figure GDA0003811637450000032
the chlorination section adopts a reaction mode of combining tubular injection and tower type, so that hydrogen chloride is better dissolved in glycol solution, side reactions are less, unit consumption is reduced, and the yields of chloroethanol and dichloroethane are improved.
Ethylene glycol 2 is conveyed from a tank area through a pipeline, mixed with circulating ethylene glycol with a catalyst 1, then enters a primary EG preheater E1218, then enters a secondary EG preheater E1219, heated by steam 3, mixed with HCl gas conveyed from a circulating gas separator V-1204, and then enters an EG mixing jet pump EJ-1201 to be mixed and reacted with ethylene glycol; the fresh hydrogen chloride 4 and the circulating glycol conveyed by the glycol circulating pump circulation P-1201 are mixed and reacted in the HCl mixing jet pump EJ-1202, the reacted glycol continuously enters the EG mixing jet pump EJ-1201 to continuously react with the circulating HCl, then enters the gas separator V-1201, and the gas flowing out from the top of the gas separator V-1201 entrains a part of liquid to enter the bottom of the (first) chlorination tower T1201 to continuously react.
The top of the chlorination tower is provided with a gas-liquid separator 13, and the lower part of the chlorination tower is composed of a reaction tower 14 and a circulating pipe 15. The gas and liquid mixture materials from the gas separator V-1201 enter the bottom of the chlorination tower, the raw material HCl enters the middle lower part of the reaction tower, ethylene glycol and HCl continue to react in the reaction tower to produce chlorohydrin and dichloroethane, the materials directly enter the gas-liquid separator 13 from the reaction tower, unreacted HCl carries a part of products to be discharged from the top of the gas-liquid separator 13, the unreacted HCl enters the HCl separator V-1202 after being cooled by the circulating gas cooler E-1201, the HCl separated from the top enters the circulating gas blower K-1201, and the HCl is sent to the circulating gas separator V-1204 after being pressurized and finally returns to the EG mixing jet pump EJ-1201. The liquid obtained after the reaction automatically flows into a circulating pipe 15 from the lower part of a separator 13 under the action of density difference, and the lower part of the circulating pipe is connected with a reaction tower to realize the circulating reaction of glycol and HCl; and part of materials are sent into a recovery tower T-1204 from the middle part of a circulating pipe, a mixed product 6 of chloroethanol and ethylene glycol is obtained at the top of the tower through a rectification process, unreacted ethylene glycol (circulating EG) is obtained at the bottom of the tower, and the part of circulating EG returns to a reaction part to continue the reaction. The liquid obtained at the bottom of the HCl separator V-1202 enters an EDC separating tank V-1203 to realize the layering of chlorohydrin and dichloroethane, the chlorohydrin crude product obtained at the upper part enters a recovery tower T-1204, and the dichloroethane at the lower part enters an EDC receiving tank to obtain a dichloroethane crude product 5.
To increase the yields of chlorohydrin and dichloroethane, a secondary chlorination of fresh HCl and HCl fed from recycle gas separator V-1204 was performed. Firstly, fresh HCl and ethylene glycol or chlorohydrin enter an HCl jet pump EJ-1203 to enable the ethylene glycol or chlorohydrin to continue to carry out chlorination reaction, then HCl conveyed by a circulating gas separator V-1204 enters an exhaust jet pump EJ-1204 and then enters a jet reactor VR-1201, finally enters a second chlorination tower T-1202, a liquid phase product obtained at the bottom of the tower is sent into the chlorination tower T-1201, a gas phase enters a pest removal tower T-1203, tail gas is discharged after alkali liquor absorption, and waste alkali liquor is obtained at the bottom of the tower. The yield of chlorohydrin is increased if the HCl jet pump EJ-1203 is fed with ethylene glycol feedstock, and the yield of dichloroethane is increased if the chlorohydrin feedstock is fed.
The rectifying separation section can realize that a mixed product 6 of chloroethanol and glycol and a coarse dichloroethane 5 enter an azeotropic tower T-1205, an azeotrope of dichloroethane and water is obtained at the tower top, the mixture enters an azeotropic tower reflux tank V-1211 for layering after being condensed by an azeotropic tower top condenser E1209, water at the upper layer flows back into the tower through an azeotropic tower reflux pump P-1215, the dichloroethane containing trace water at the lower layer is sent to the top of the EDC tower T-1206 through an EDC feeding pump P-1216, trace water is removed through rectification, a fine dichloroethane 10 is obtained at the tower bottom, an azeotrope of the dichloroethane and water is obtained at the tower top, the azeotrope enters the azeotropic tower top condenser E1209 for common condensation, and the mixture enters an azeotropic tower reflux tank V-12011 for continuous layered dehydration. The material at the bottom of the azeotropic tower T-1205 is sent into a dehydration tower T-1207 by an azeotropic tower bottom liquid pump P-1214, the process water from which the chloroethanol is removed is obtained at the bottom of the tower, and the azeotrope of the chloroethanol and water is obtained at the top of the tower, namely a chloroethanol crude product 11. The crude chlorohydrin is dehydrated with water by a solvent such as benzene or cyclohexane, desolventized and decompressed and rectified to obtain the 2-chlorohydrin with the content of more than 99 percent.
The catalyst adopted by the invention is complex salt, specifically triphenylphosphine is used as a complex carrier, halogenated salt is used as an active component, and the catalyst is specifically chloride salt, bromide salt and iodide salt of all metal elements, such as NaCl, naBr, naI, mgCl, mgBr2, mgI2, cuCl, cuBr, cuI, cuCl2, cuBr2, cuI2, feCl3, feBr3, feI3, znCl2, znBr2, znI2, caCl2, caBr2, caI2, alCl3, alBr3, alI3 and the like. Preferably, the active component can be one or more than two of chloride salts, and the catalyst composition is that the molar ratio of triphenylphosphine to chloride salts is 1:1-3:1. The mass concentration of the complex salt catalyst in the reaction mass is 1-10% in the production process. For example, the catalyst may be a triphenylphosphine/aluminum trichloride catalyst.
The invention has the beneficial effects that:
(1) The invention realizes the innovation of simultaneously preparing high-purity chlorohydrin and dichloroethane (the purity can reach more than 99 percent) from ethylene glycol, and compared with the traditional chlorohydrin production method, the invention has the advantages of mild reaction condition, low toxicity of reaction raw materials and no explosion risk of the chlorohydrin, and realizes intrinsic safety; compared with the traditional ethylene oxychlorination method for producing dichloroethane, no oxygen participates in the reaction, and no explosion risk exists.
(2) The invention adopts the homogeneous complex salt catalyst, the problems of separation and inactivation of the active components of the catalyst do not exist in the reaction, and the catalyst can be dissolved in glycol for recycling. Compared with acid catalysts such as adipic acid, the method avoids the risk of catalyst deactivation caused by esterification reaction of organic acid and alcohol, and solves the problem that the catalyst is not easy to recover and separate.
(3) The chlorination section adopts a coupling mode of the jet pipe reactor and the tower reactor, so that the reaction efficiency and the selectivity of target products are improved, the production energy consumption is reduced, and the yields of chlorohydrin and dichloroethane can be flexibly adjusted according to actual requirements; for example: the chlorination section adopts a reaction mode of combining tubular injection and tower type, so that hydrogen chloride is better dissolved in glycol solution, the reaction conversion rate is high, the reaction is safe, the side reaction is less, the energy consumption is reduced, and the yields of chloroethanol and dichloroethane are improved; the system adopts a secondary chlorination tube tower coupling reactor, and can adjust the product yield of chlorohydrin and dichloroethane according to production requirements, and the system specifically comprises: the yield of chlorohydrin is increased if the HCl jet pump is fed to the ethylene glycol feedstock, and the yield of dichloroethane is increased if the chlorohydrin feedstock is fed.
(4) And the dichloroethane products are separated and purified by adopting a two-tower coupling rectification process, so that the production energy consumption of equipment is reduced, and the high-purity 2-chloroethanol and dichloroethane are finally obtained after treatment.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and other drawings may be obtained according to these drawings for a person having ordinary skill in the art.
FIG. 1 shows the reaction process corresponding to the first chlorination stage and the second chlorination stage of the present disclosure;
FIG. 2 shows the corresponding reaction process of the rectification separation section of the present invention.
Detailed Description
For the purposes of promoting an understanding of the invention, reference will now be made in detail to various exemplary embodiments of the invention, which should not be considered as limiting the invention in any way, but rather as describing in more detail certain aspects, features and embodiments of the invention.
Specific embodiments of the present invention are described in detail below with reference to the accompanying drawings:
application example 1:
fig. 1 and 2 show a process flow for implementing the invention, which is specifically described as follows:
(1) A first chlorination section:
triphenylphosphine/aluminum trichloride catalyst is adopted, and the composition is that the molar ratio is 2:1. As shown in fig. 1, the raw material glycol, catalyst and recycle glycol are preheated to 60 ℃ in a primary EG preheater E1218 after being mixed, so that the catalyst and glycol are fully dissolved, then heated to 80-90 ℃ in a secondary EG preheater E1219, and mixed with HCl gas with the temperature of 30-40 ℃ conveyed from a recycle gas separator V-1204, and then fed into an EG mixing jet pump EJ-1201 to be mixed with glycol for chlorination reaction; the fresh hydrogen chloride is at 30-40 ℃ and the pressure is 300-600kPa, the fresh hydrogen chloride and the circulating ethylene glycol which is conveyed by an ethylene glycol circulating pump and has the temperature of 80-90 ℃ are mixed in an HCl mixing jet pump EJ-1202 to generate chlorination reaction, then the mixture enters an EG mixing jet pump EJ-1201 to continuously react with circulating HCl, and finally enters a gas separator V-1201, the temperature of gas flowing out of the top of the gas separator V-1201 is 80-90 ℃, the pressure is 250-550kPa, the entrained raw material liquid enters the bottom of a (first) chlorination tower T1201 to continuously react under the action of unreacted HCl gas flow, and the reaction temperature of the chlorination tower is 80-90 ℃ and the reaction pressure is 150-450kPa.
In the chlorination tower, the densities of fluids in the reaction tower 14 and the circulating pipe 15 are different, the gas-liquid mixed flow is arranged in the reaction tower, and the liquid-phase flow is arranged in the circulating pipe, so that density difference is generated, raw materials circularly flow in the reaction tower, the separator and the circulating pipe, the turbulence of the materials is improved, and the diffusion rate is improved, so that the reaction rate is improved. Specifically, HCl gas and liquid mixture materials with the temperature of 80-90 ℃ and the pressure of 250-550kPa, which are from a gas separator V-1201, enter from the bottom of a chlorination tower to form primary gas-liquid mixed flow in the tower; the temperature is 30-40 ℃ and the pressure is 300-600kPa, the raw material HCl enters the middle lower part of the reaction tower, a secondary gas-liquid mixed flow is formed in the reaction tower, the density in the reaction tower is further reduced, the liquid flow speed is accelerated, and the ethylene glycol and the HCl further react rapidly to generate chlorohydrin and dichloroethane. The reacted materials at 80-90 ℃ directly enter a separator 13 from a reaction tower, a part of products (mainly dichloroethane, chloroethanol and water) are discharged from the top of the gas-liquid separator 13 under the carrying action of unreacted HCl, cooled to 30-40 ℃ in a circulating gas cooler E-1201, enter an HCl separator V-1202 to realize gas-liquid separation, and the HCl separated from the top enters a circulating gas blower K-1201 to be pressurized to 350-650kPa and then is sent into a circulating gas separator V-1204. The liquid at the lower part of the gas-liquid separator 13 automatically flows into the circulating pipe 15 from the lower part of the separator 13 under the action of the density difference between the reaction tower and the circulating pipe. The product is extracted from the middle part of the circulating pipe and is sent to a recovery tower T-1204, the tower is a negative pressure rectifying tower, the tower top pressure is 5-25kPa, the tower top temperature is 40-75 ℃, the tower bottom temperature is 140-165 ℃, the mixed product 6 of chloroethylene and ethylene glycol is distilled off from the tower top, the unreacted ethylene glycol (circulating EG) is recovered from the tower bottom, and the circulating EG is boosted to 600-800kPa by a tower bottom pump P-1211 and returned to the reaction part. The product liquid obtained by the separation of the HCl separator V-1202 enters an EDC separating tank V-1203, the separation of the chloroethanol and the dichloroethane is realized by the density difference of the dichloroethane and the chloroethanol, the chloroethanol crude product obtained at the upper part enters a recovery tower T-1204 for recovering the chloroethanol, and the dichloroethane at the lower part enters an EDC receiving tank to obtain the dichloroethane crude product 5.
(2) A second chlorination section:
the yield improvement of the chlorohydrin or dichloroethane single product can be realized by adopting a secondary chlorination process. I.e. fresh HCl and HCl fed from the recycle gas separator V-1204, are subjected to a secondary chlorination reaction. As shown in figure 1, firstly fresh HCl and glycol or chloroethanol preheated to 80-90 ℃ enter an HCl jet pump EJ-1203 for chlorination reaction, then HCl conveyed by a circulating gas separator V-1204 enters an exhaust jet pump EJ-1204 for chlorination reaction again, then deep chlorination reaction is carried out in a jet reactor VR-1201, finally the mixture enters a second chlorination tower T-1202, the top pressure of the second chlorination tower is kept at 300-600kPa for complete chlorination reaction, liquid phase products obtained at the bottom of the second chlorination tower are sent to the chlorination tower T-1201 for recycling products, gas phase enters a pest elimination tower T-1203, after alkali liquid absorption, tail gas is discharged, waste alkali liquid is obtained at the bottom of the tower, and the operation temperature of the pest elimination tower is 40-80 ℃ and the operation pressure of the pest elimination tower is 100-120kPa. During the secondary chlorination, chlorohydrin product is produced more if the HCl jet pump EJ-1203 is ethylene glycol feed and dichloroethane is produced more if it is chlorohydrin feed.
(3) And (3) rectifying and separating section:
as shown in figure 2, the mixed product 6 of chloroethylene and glycol and the crude dichloroethane 5 are sent into an azeotropic tower T-1205, the tower top pressure is 100-150kPa, the tower top temperature is 50-56 ℃, the tower bottom temperature is 100-105 ℃, the tower top obtains an azeotrope of dichloroethane and water, the temperature after condensation of an azeotropic tower top condenser E1209 is 30-40 ℃, the operating temperature of an azeotropic tower reflux tank V-1211 is 30-40 ℃, the condensate is placed in the reflux tank for layering, the upper layer is water, the condensate is refluxed into the tower through an azeotropic tower reflux pump P-1215, the lower layer is dichloroethane containing trace water, the dichloroethane is sent into the top of an EDC tower T-1206 through an EDC feed pump P-1216, the tower top pressure is 100-150kPa, the tower top temperature is 78-87 ℃, the tower bottom temperature is 90-95 ℃, the trace water is removed through rectification, the tower bottom obtains a fine dichloroethane 10, the mass content of dichloroethane reaches more than 99.7%, the mixture of the tower top dichloroethane and the water is discharged from the azeotropic tower top condenser E1209 to be jointly condensed to 30-40 ℃, and the azeotropic tower reflux tank V-12011 is continuously dehydrated in layering mode. The material at the bottom of the azeotropic tower T-1205 is sent into a dehydration tower T-1207 by an azeotropic tower kettle liquid pump P-1214, the pressure at the top of the tower is 100-150kPa, the temperature at the top of the tower is 101-105 ℃, the temperature at the bottom of the tower is 110-130 ℃, the process water from which the chloroethanol is removed is arranged at the bottom of the tower, the azeotrope of the chloroethanol and the water is arranged at the top of the tower, the mixture is condensed to 30-40 ℃, a part of the mixture flows back, and the other part of the mixture is taken as a chloroethanol crude product 11. The crude chlorohydrin 11 is dehydrated with water by adopting solvents such as benzene or cyclohexane, desolventized and decompressed and rectified to obtain the 2-chlorohydrin with the mass content of more than 99 percent.
According to the specific reaction process described above, one specific reaction example of the present invention is as follows:
HCl feed 657.3kg/h, ethylene glycol feed 553kg/h.
(1) First chlorination reaction:
triphenylphosphine/aluminum trichloride catalyst is adopted, the composition is that the molar ratio is 2:1, the mass concentration of the catalyst in the reaction raw materials is 5.5%, the raw material ethylene glycol is mixed with 553kg/h of circulating ethylene glycol flow 689kg/h, the mixture is preheated to 60 ℃ in a primary EG preheater E1218, the mixture is heated to 80 ℃ in a secondary EG preheater E1219, the HCl gas flow at 30 ℃ conveyed from a circulating gas separator V-1204 is 1050kg/h, and the mixture enters an EG mixing jet pump EJ-1201 to be mixed with ethylene glycol; the fresh hydrogen chloride flow rate is 657.3kg/h, the temperature is 30 ℃, the pressure is 600kPa, 6500kg/h of circulating ethylene glycol which is conveyed by an ethylene glycol circulating pump circulation P-1201 and has the temperature of 80-90 ℃ is mixed in an HCl mixing jet pump EJ-1202 to carry out chlorination reaction, then the mixture enters the EG mixing jet pump EJ-1201 to continuously react with circulating HCl, and finally enters a gas separator V-1201, the temperature of gas-liquid mixed fluid flowing out from the top of the gas separator V-1201 is 80 ℃, the pressure is 550kPa, the flow rate is 2949.3kg/h, the feed liquid enters the bottom of a chlorination tower T1201 to continuously react, the reaction temperature of the chlorination tower is 80 ℃, and the reaction pressure is 450kPa.
In the chlorination tower, 2949.3kg/h of material with the flow rate from the gas separator V-1201 and the temperature of 80 ℃ and the pressure of 550kPa enter from the bottom of the chlorination tower, and a primary gas-liquid mixed flow is formed in the tower; the raw material HCl with the temperature of 30 ℃ and the pressure of 600kPa enters the middle lower part of the reaction tower, and a secondary gas-liquid mixed flow is formed in the reaction tower, so that the density of liquid in the reaction tower is further reduced, and the flow of the liquid is accelerated. The reacted material at 80 ℃ directly enters a separator 13 from a reaction tower, a part of dichloroethane, chloroethanol and water are discharged from the top of the gas-liquid separator 13 under the carrying action of HCl, cooled to 30 ℃ after passing through a circulating gas cooler E-1201, enter an HCl separator V-1202 to realize gas-liquid separation, and HCl separated from the top enters a circulating gas blower K-1201 to be pressurized to 650kPa and then is sent into a circulating gas separator V-1204, wherein the operating pressure is 600kPa. The liquid at the lower part of the gas-liquid separator 13 automatically flows into the circulating pipe 15 from the lower part of the separator 13 under the action of the density difference between the reaction tower and the circulating pipe. The product is extracted from the middle part of a circulating pipe, the extraction amount is 1606.2kg/h, the product is sent to a recovery tower T-1204, the tower is a negative pressure rectifying tower, the tower top pressure is 20kPa, the tower top temperature is 68 ℃, the tower bottom temperature is 155 ℃, the flow rate of a mixed product 6 of chloroethanol and dichloroethane distilled from the tower top is 847.2kg/h, the flow rate of the recovered unreacted glycol (circulating EG) at the tower bottom is 689kg/h, and the circulating EG is boosted to 800kPa by a tower bottom pump P-1211 and returned to the reaction part. The product liquid obtained by the separation of the HCl separator V-1202 enters an EDC separating tank V-1203, the separation of the chloroethanol and the dichloroethane is realized by the density difference of the dichloroethane and the chloroethanol, the flow rate of the chloroethanol crude product obtained at the upper part is 150kg/h, the chloroethanol is recovered by entering a recovery tower T-1204, and the flow rate of the dichloroethane at the lower part is 361.7kg/h, which is obtained by entering an EDC receiving tank.
(2) Second chlorination reaction:
91.7kg/h of fresh HCl and 630kg/h of chlorohydrin preheated to 80 ℃ enter an HCl jet pump EJ-1203 for secondary chlorination reaction, then 200kg/h of HCl with the flow rate of 600kPa is conveyed from a circulating gas separator V-1204, enters an exhaust jet pump EJ-1204 for secondary chlorination reaction, then deep chlorination reaction is carried out in a jet reactor VR-1201, finally the mixture enters a second chlorination tower T-1202, the top pressure of the second chlorination tower is 400kPa, complete chlorination reaction is carried out, 910kg/h of liquid phase product obtained at the bottom of the tower is conveyed into the chlorination tower T-1201 for recycling product, gas phase enters a pest removal tower T-1203, the operating temperature of the pest removal tower is 40 ℃, the operating pressure is 120kPa, the tail gas is discharged to 1.7kg/h after the gas is absorbed by alkali liquor washing, and waste alkali liquor is obtained at the bottom of the tower.
(3) And (3) rectifying and separating:
847.2kg/h of a mixed product 6 of chloroethylene and ethylene glycol and 361.7kg/h of a dichloroethane crude product 5 are fed into an azeotropic column T-1205, the pressure at the top of the column is 120kPa, the temperature at the top of the column is 53 ℃, the temperature at the bottom of the column is 103 ℃, an azeotrope of dichloroethane and water is obtained at the top of the column, an azeotropic column condenser E1209 is 30 ℃ after condensation, the operating temperature of an azeotropic column reflux tank V-1211 is 30 ℃, the condensate is placed in the reflux tank for layering, the water flow rate of the upper layer is 19.66kg/h, the condensate flows back into the column through an azeotropic column reflux pump P-1215, the dichloroethane flow rate of the lower layer containing trace water is 843.6kg/h, the pressure at the top of the column is 120kPa, the temperature at the top of the column is 79 ℃, the temperature at the bottom of the column is 93 ℃, trace water is removed through rectification, the top of the column is obtained, the fine 10 flow rate of dichloroethane is 813kg/h, the mass concentration (purity) of the dichloroethane is 99.72%, and the mixture of the dichloroethane and water removed from the top of the column is fed into the azeotropic column condenser E1209 to be jointly condensed to 30 ℃, and the azeotropic column reflux tank V-12011 for layering dehydration. The extraction amount at the bottom of the azeotropic tower T-1205 is 396kg/h, the azeotropic tower is fed into a dehydration tower T-1207 by an azeotropic tower bottom liquid pump P-1214, the tower top pressure is 120kPa, the tower top temperature is 101 ℃, the tower bottom temperature is 110 ℃, the process water flow for removing chloroethanol is 242kg/h, the tower top is an azeotrope of chloroethanol and water, the chloroethanol is condensed to 30 ℃, a part of the chloroethanol is refluxed, and the flow of the chloroethanol crude product 11 is 154kg/h. The crude product 11 of the chlorohydrin is dehydrated with water by adopting solvents such as benzene or cyclohexane, desolventized and decompressed and rectified to obtain the 2-chlorohydrin product with the mass concentration (purity) of 99.2 percent.
Therefore, the invention adopts the coupling mode of the jet pipe reactor and the tower reactor through optimizing the process equipment, and can simultaneously prepare the chlorohydrin and dichloroethane products with high purity from the ethylene glycol through the double-tower coupling rectification separation process, the purity of the dichloroethane products reaches more than 99.7%, the purity of the chlorohydrin products reaches more than 99%, the production energy consumption is reduced, and the chlorohydrin and dichloroethane yield can be flexibly adjusted according to actual needs; meanwhile, the homogeneous complex salt catalyst is adopted, so that the problems of difficult recovery and separation of the catalyst and the like are solved, and the catalyst has a good effect.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (9)

1. A production process for the co-production of chloroethanol and dichloroethane is characterized by comprising the following steps of: the process mainly comprises a first chlorination section, a second chlorination section and a rectifying separation section; and a homogeneous catalyst is used in the reaction;
wherein the homogeneous catalyst is complex salt, which takes triphenylphosphine as complex carrier and halogenated salt as active component; the mass concentration of the complex salt catalyst in the reaction material is 1-10%.
2. The production process of co-production of chloroethanol and dichloroethane according to claim 1, further wherein the active component is a mixed component of one or more of chloride salts; the catalyst composition is that the mole ratio of triphenylphosphine to chloride salt is 1:1-3:1.
3. The process for the co-production of chloroethanol and dichloroethane according to claim 1, wherein: the first chlorination section and the second chlorination section adopt a reaction mode of combining tubular injection and tower type.
4. A process for the co-production of chloroethanol and dichloroethane according to claim 3, further characterized by: the top of the chlorination tower is provided with a gas-liquid separator, and the lower part of the chlorination tower is composed of a reaction tower and a circulating pipe.
5. The process for producing chloroethanol and dichloroethane according to any one of claims 1 to 4, wherein the separation section adopts a two-tower coupling rectification process to separate high-purity chloroethanol and dichloroethane, and the two towers are an azeotropic tower and a dehydration tower.
6. The process for the co-production of chloroethanol and dichloroethane according to any one of claims 1 to 4, further comprising the step of: after the ethylene glycol and the circulating ethylene glycol with the catalyst are preheated and mixed, the ethylene glycol and the HCl gas conveyed by a circulating gas separator are mixed, and are subjected to mixed circulating reaction of raw materials in various modes by a mixing jet pump with fresh HCl, and enter a first chlorination tower through a gas separator to continue reaction; after the reaction of the gas separator, the gas-liquid mixture and the corresponding raw materials such as HCl enter different units of a chlorination tower, and continue to react in the tower; after the materials are separated from the reaction tower, unreacted HCl returns to the mixed jet pump for reaction through cyclic separation treatment and the like; the liquid after reaction realizes the cyclic reaction through a circulating pipe; and separating the bottom liquid by a separator to obtain chloroethanol and dichloroethane crude products.
7. The process for the co-production of chloroethanol and dichloroethane according to any one of claims 1 to 4, further comprising the step of: firstly, fresh HCl and ethylene glycol or chlorohydrin enter an HCl jet pump to enable the ethylene glycol or chlorohydrin to continuously carry out chlorination reaction, then enter an exhaust jet pump together with HCl conveyed by a circulating gas separator, enter a jet reactor, finally enter a second chlorination tower to react, a liquid phase product obtained at the bottom of the tower is sent into a first chlorination tower, and the rest components are subjected to post treatment to obtain the catalyst.
8. The process for co-production of chlorohydrin and dichloroethane according to claim 7, further comprising feeding ethylene glycol feedstock to the HCl jet pump to increase chlorohydrin yield; or HCl jet pump is used for feeding chlorohydrin raw material, so that the dichloroethane yield is improved.
9. The production process for co-production of chloroethanol and dichloroethane according to any one of claims 1 to 4, further comprising the step of feeding the mixed product and the crude product into an azeotropic column, and performing reflux and separation by a top condenser, an azeotropic column reflux tank, an azeotropic column reflux pump, etc., to obtain high-purity dichloroethane; pumping the material at the bottom of the azeotropic tower into a dehydration tower by an azeotropic tower kettle pump, and obtaining an azeotrope of chlorohydrin and water at the top of the tower, and a chlorohydrin crude product; the chlorohydrin crude product is subjected to solvent post-treatment to obtain high-purity 2-chlorohydrin; the purity of the finally obtained 2-chloroethanol is more than 99 percent; the purity of dichloroethane is more than 99%.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110922299A (en) * 2019-11-07 2020-03-27 无锡市银杏塑业科技有限公司 Continuous preparation method of high-content 2-chloroethanol
CN113233955A (en) * 2021-05-10 2021-08-10 河北工业大学 Method for producing chloroethanol and dichloroethane by ethylene glycol chlorination

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110922299A (en) * 2019-11-07 2020-03-27 无锡市银杏塑业科技有限公司 Continuous preparation method of high-content 2-chloroethanol
CN113233955A (en) * 2021-05-10 2021-08-10 河北工业大学 Method for producing chloroethanol and dichloroethane by ethylene glycol chlorination

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