CN115108885A - Production process for co-production of chlorohydrin and dichloroethane - Google Patents
Production process for co-production of chlorohydrin and dichloroethane Download PDFInfo
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Abstract
The invention discloses a production process for co-producing chloroethanol and dichloroethane, which takes ethylene glycol as a raw material, adopts a novel process technology and uses a homogeneous catalyst to simultaneously produce chloroethanol and dichloroethane products.
Description
Technical Field
The invention relates to a production process system for co-producing chloroethanol and dichloroethane by taking ethylene glycol and hydrogen chloride as raw materials through hydrochlorination dehydration reaction, which is used as a novel green production process and can convert the ethylene glycol into chloroethanol serving as a raw material of ethylene oxide and also can convert the ethylene glycol into dichloroethane serving as a basic chemical raw material of bulk material polyvinyl chloride, thereby developing a novel method for converting the ethylene glycol into the polyvinyl chloride.
Background
Ethylene glycol (2-hydroxyethane, EG for short), and products which are more than 9 in downstream application are all used for producing polyester products. With the rapid development of the polyester industry in China, the domestic ethylene glycol requirement is greatly improved. The other main application field of the glycol industry grade is that the glycol is used as an antifreezing solution, an ice melting agent, a heat transfer fluid and the like.
Dichloroethane is mainly used as raw material of chloroethylene, glycol, ethanedioic acid, ethylenediamine, tetraethyl lead, polyethylene polyamine and bibenzoyl, also can be used as solvent of grease, resin and rubber, dry cleaning agent, extracting agent for pesticide except early chrysanthemin, caffeine, vitamins and hormone, moistening agent, penetrating agent, petroleum dewaxing and antidetonation agent, also can be used as raw material for producing pesticide and using pesticide for killing pesticide and piperazines.
Chloroethanol (2-chloroethanol) is an important organic solvent and an organic synthesis raw material. Chlorohydrin is used in the production of intermediates for ethylene oxide, synthetic rubber, dyes, pharmaceuticals and pesticides, and is also used as an organic solvent.
Researchers have been working on the conversion of ethylene glycol to high-value chemicals, and the preparation of chloroethanol and dichloroethane by chlorination using ethylene glycol as a raw material is a technological route. Dichloroethane is also an important raw material for producing polyvinyl chloride, so how to more efficiently realize the conversion of ethylene glycol to chloroethanol and dichloroethane is a key problem which has been researched all the time.
Although the target products of chloroethanol and dichloroethane are chloroethanol and dichloroethane by using ethylene glycol chlorination at present, actually, the method for preparing chloroethanol and dichloroethane by using ethylene glycol chlorination is a complicated series-connection and reversible reaction process, specifically, the hydrochlorination reaction of ethylene glycol and hydrogen chloride comprises two-step series-connection reversible reaction, and the reaction speed of chloroethanol in the product generated by the hydrochlorination reaction of ethylene glycol and hydrogen chloride is about 10 times that of dichloroethane; in addition, in the existing preparation method, the ethylene glycol chlorination process mainly uses organic acid as a catalyst, the catalyst consumption is large due to the characteristics of difficult recovery and difficult separation of the organic acid, and the conversion rate of ethylene glycol is greatly influenced.
The invention takes ethylene glycol as raw material, adopts a novel process technology and uses a homogeneous catalyst to simultaneously produce chloroethanol and dichloroethane, the process has the advantages of less three-waste discharge, high product yield, novel green production process, high reaction conversion rate and more complete reaction of raw materials, thereby well solving the technical problems.
Disclosure of Invention
The invention aims to provide a combined production device of chloroethanol and dichloroethane, which simultaneously obtains chloroethanol and dichloroethane products, adopts a reaction flow combining tubular injection and tower type, and is a novel green and environment-friendly process with high integration level, low energy consumption and high product yield.
A production process for co-producing chloroethanol and dichloroethane takes ethylene glycol and hydrogen chloride as raw materials, and mainly comprises a first chlorination section, a second chlorination section and a rectification separation section; and a homogeneous catalyst is used in the reaction.
Further, the homogeneous catalyst is complex salt, which is triphenylphosphine as a complex carrier and halide 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 salt; the catalyst comprises triphenylphosphine and halide salt in a molar ratio of 1: 1-3: 1.
Further, the first chlorination section and the second chlorination section adopt a reaction mode of combining a tubular injection (reactor) and a (chlorination tower) tower type (reactor); 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 stage is: preheating and mixing ethylene glycol and circulating ethylene glycol with a catalyst, mixing the ethylene glycol and HCl gas conveyed by a circulating gas separator, carrying out mixed circulating reaction on the mixed circulating reaction and fresh HCl in various modes on raw materials through a mixed jet pump, and entering a first chlorination tower through a gas separator for continuous reaction; after the reaction of the gas separator, the gas-liquid mixture and corresponding raw materials such as HCl and the like enter different units of a chlorination tower and continue to react in the tower; after the materials are separated from the reaction tower, the unreacted HCl is returned to the mixing jet pump for reaction after circulation separation treatment and the like; the liquid after reaction realizes the circular reaction through a circulating pipe; the separator separates the liquid at the bottom to obtain the chloroethanol and the dichloroethane crude products.
The second chlorination stage is as follows: firstly, fresh HCl and ethylene glycol or chloroethanol enter an HCl jet pump to enable the ethylene glycol or chloroethanol to continuously carry out chlorination reaction, then the HCl conveyed by a circulating gas separator enters an exhaust jet pump, then enters a jet reactor, finally enters a second chlorination tower to react, a liquid-phase product obtained at the bottom of the tower is sent to a first chlorination tower, and the rest components are subjected to post-treatment emptying or VOCs treatment.
Regarding the second chlorination stage, the product yield of chloroethanol and dichloroethane can be adjusted according to production requirements, and the chloroethanol yield can be improved by feeding ethylene glycol raw material into an HCl jet pump; if the chloroethanol raw material is fed, the yield of dichloroethane is improved.
The rectification separation section comprises the steps of feeding the mixed product and a 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 tower; the material at the bottom of the azeotropic tower is pumped into a dehydrating tower by an azeotropic tower kettle liquid pump, and an azeotrope of chloroethanol and water and a chloroethanol crude product are obtained at the top of the tower; and (3) carrying out solvent post-treatment on the chloroethanol crude product to obtain the high-purity 2-chloroethanol.
Preferably, the solvent is benzene or cyclohexane; the post-treatment means comprises dehydration of the solvent with water, solvent removal and vacuum rectification.
Regarding the rectification 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 stages are specifically described below.
The chlorination reaction occurs in the chlorination stage, and the reaction formula is as follows:
the first step of reaction:
the second step of reaction:
the chlorination section adopts a reaction mode combining tubular injection and tower type, so that hydrogen chloride is better dissolved in the ethylene glycol solution, side reactions are less, the unit consumption is reduced, and the yield of chloroethanol and dichloroethane is improved.
The ethylene glycol 2 is conveyed from a tank area through a pipeline, mixed with circulating ethylene glycol with a catalyst 1, enters a first-stage EG preheater E1218, then enters a second-stage EG preheater E1219, is heated by adopting steam 3, is 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 with the ethylene glycol and react; fresh hydrogen chloride 4 and circulating glycol conveyed by a circulating P-1201 of an ethylene glycol circulating pump are mixed and reacted in an HCl mixing jet pump EJ-1202, the reacted ethylene glycol continuously enters an EG mixing jet pump EJ-1201 to continuously react with the circulating HCl and then enters a gas separator V-1201, and gas flowing out of the top of the gas separator V-1201 carries a part of liquid to enter the bottom of a (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 method comprises the following steps that a gas and liquid mixed material from a gas separator V-1201 enters the bottom of a chlorination tower, raw material HCl enters the middle lower part of a reaction tower, ethylene glycol and HCl continue to react in the reaction tower to produce chloroethanol and dichloroethane, the material directly enters a 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 materials enter an HCl separator V-1202 after being cooled by a circulating gas cooler E-1201, the HCl separated from the top enters a circulating gas blower K-1201, the HCl separated from the top is sent to a circulating gas separator V-1204 after being pressurized, and finally the HCl returns to an EG mixing jet pump EJ-1201. The liquid obtained after the reaction automatically flows into a circulating pipe 15 from the lower part of the separator 13 under the action of density difference, and the lower part of the circulating pipe is connected with a reaction tower, so that the circulating reaction of the ethylene glycol and the HCl is realized; part of the materials are sent into a recovery tower T-1204 from the middle part of the circulating pipe, a mixed product 6 of chloroethanol and ethylene glycol is obtained at the top of the tower through the rectification process, unreacted ethylene glycol (circulating EG) is obtained at the bottom of the tower, and the circulating EG is returned to the reaction part for continuous reaction. The liquid obtained from the bottom of the HCl separator V-1202 enters an EDC separation tank V-1203 to realize the layering of chloroethanol and dichloroethane, the chloroethanol crude product obtained from the upper part enters a recovery tower T-1204, and the dichloroethane obtained from the lower part enters an EDC receiving tank to obtain a dichloroethane crude product 5.
In order to improve the yield of chloroethanol and dichloroethane, fresh HCl and HCl conveyed from the circulating gas separator V-1204 are subjected to secondary chlorination reaction. Firstly, fresh HCl and ethylene glycol or chloroethanol enter an HCl jet pump EJ-1203 to enable the ethylene glycol or chloroethanol to continuously carry out chlorination reaction, then the HCl conveyed by a circulating gas separator V-1204 enters an exhaust jet pump EJ-1204, 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 conveyed into the chlorination tower T-1201, a gas phase enters a harm removing tower T-1203, after absorption by alkali liquor, tail gas is discharged, and waste alkali liquor is obtained at the bottom of the tower. The ethylene glycol feed will increase the chloroethanol yield if fed by the HCl jet pump EJ-1203, and the dichloroethane yield if fed.
The rectification separation section can realize that a mixed product 6 of chloroethanol and ethylene glycol and a dichloroethane crude product 5 enter an azeotropic tower T-1205, azeotrope of dichloroethane and water is obtained at the tower top, the mixed product and the dichloroethane crude product enter an azeotropic tower reflux tank V-1211 for layering after being condensed by an azeotropic tower top condenser E1209, water is arranged at the upper layer, the mixed product and the dichloroethane crude product flow into the azeotropic tower through an azeotropic tower reflux pump P-1215, dichloroethane containing a small amount of water is arranged at the lower layer, the lower layer is the dichloroethane containing a small amount of water and is sent to the top of an EDC tower T-1206 through an EDC feed pump P-1216, the small amount of water is removed through rectification, a dichloroethane fine product 10 is obtained at the tower bottom, azeotrope of the dichloroethane and water is obtained at the tower top, the mixed product and the dichloroethane and water enter an azeotropic tower top condenser E1209 for common condensation, and then enter an azeotropic tower reflux tank V-12011 for continuous layering and dehydration. The material at the bottom of the azeotropic tower T-1205 is sent to the dehydrating tower T-1207 by the azeotropic tower kettle liquid pump P-1214, the process water without chloroethanol is obtained at the bottom of the tower, the azeotrope of chloroethanol and water and the chloroethanol crude product 11 are obtained at the top of the tower. The 2-chloroethanol with the content of more than 99 percent is obtained after dehydration, solvent removal and decompression rectification of the chloroethanol crude product with water by using solvents such as benzene or cyclohexane and the like.
The catalyst adopted by the invention is complex salt, specifically triphenylphosphine is used as a complex carrier, halide salt is used as an active component, specifically chloride salt, bromide salt and iodide salt of all metal elements, such as NaCl, NaBr, NaI, MgCl2, 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 mixed components of chloride salt, and the catalyst component is that the molar ratio of triphenylphosphine to chloride salt is 1: 1-3: 1. The mass concentration of the complex salt catalyst in the reaction material in the production process is 1-10%. For example, the catalyst may be a triphenylphosphine/aluminium trichloride catalyst.
The invention has the beneficial effects that:
(1) the invention realizes that the ethylene glycol can simultaneously prepare high-purity chloroethanol and dichloroethane (the purity can reach more than 99 percent), and compared with the addition reaction of ethylene oxide and hydrogen chloride in the traditional chloroethanol production method, the invention has the advantages of mild reaction conditions, low toxicity of reaction raw materials, no explosion risk of ethylene oxide and realization of intrinsic safety innovation; 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 homogeneous complex salt catalyst, the problems of separation and inactivation of active components of the catalyst do not exist in the reaction, and the catalyst can be dissolved in the ethylene glycol for recycling. Compared with the acidic catalysts such as adipic acid and the like, the method avoids the risk of catalyst deactivation caused by the esterification reaction of organic acid and alcohol, and solves the problem that the catalyst is difficult to recover and separate.
(3) The chlorination section of the invention adopts a coupling mode of a jet pipe reactor and a tower reactor, improves the reaction efficiency and the selectivity of a target product, reduces the production energy consumption, and can flexibly adjust the yield of the chloroethanol and the dichloroethane according to actual needs; for example: the chlorination section adopts a reaction mode combining tubular injection and tower type, so that hydrogen chloride is better dissolved in the ethylene glycol solution, the reaction conversion rate is high, the reaction is safe, the side reaction is less, the energy consumption is reduced, and the yield of chloroethanol and dichloroethane is improved; the system adopts a secondary chlorination tube tower coupling reactor, can adjust the product yield of chloroethanol and dichloroethane according to production needs, and specifically comprises the following steps: the chlorohydrin yield is increased if HCl jet pump is fed to the ethylene glycol feed and the dichloroethane yield is increased if the chlorohydrin feed is fed.
(4) The dichloroethane product is separated and purified by adopting a two-tower coupling rectification process, the production energy consumption of equipment is reduced, and 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 technical solutions in the prior art, the drawings needed to be used 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 can be obtained by those skilled in the art according to the drawings.
FIG. 1 is a reaction process corresponding to a first chlorination reaction stage and a second chlorination reaction stage of the present invention;
FIG. 2 shows a reaction process corresponding to the rectifying and separating section of the present invention.
Detailed Description
In order to facilitate an understanding of the invention, various exemplary embodiments of the invention will now be described in detail, which should not be construed as a specific limitation of the invention, but rather as a more detailed description of certain aspects, features and embodiments of the invention.
The embodiments of the present invention are described in detail below with reference to the accompanying drawings:
application example 1:
the process flow for implementing the invention is shown in fig. 1 and fig. 2, and the specific description is as follows:
(1) a first chlorination stage:
triphenylphosphine/aluminum trichloride catalyst is adopted, and the composition is in a molar ratio of 2: 1. As shown in figure 1, raw material ethylene glycol, a catalyst and circulating ethylene glycol are mixed and then preheated to 60 ℃ in a first-stage EG preheater E1218 to fully dissolve the catalyst and the ethylene glycol, and then heated to 80-90 ℃ in a second-stage EG preheater E1219 to be mixed with HCl gas which is delivered from a circulating gas separator V-1204 and has the temperature of 30-40 ℃ and then enters an EG mixing jet pump EJ-1201 to be mixed with the ethylene glycol to carry out chlorination reaction; fresh hydrogen chloride is mixed in an HCl mixing jet pump EJ-1202 at the temperature of 30-40 ℃ and the pressure of 300-600kPa, is subjected to chlorination reaction with circulating ethylene glycol which is conveyed by an ethylene glycol circulating pump circulating P-1201 and has the temperature of 80-90 ℃, enters an EG mixing jet pump EJ-1201 and is subjected to continuous reaction 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, and the raw material liquid is entrained to enter the bottom of a (first) chlorination tower T1201 to be subjected to continuous reaction under the action of unreacted HCl gas flow, the reaction temperature of the chlorination tower is 80-90 ℃, and the reaction pressure is 150-450 kPa.
In the chlorination tower, the densities of fluids in the reaction tower 14 and the circulating pipe 15 are different, gas-liquid mixed flow is formed in the reaction tower, and liquid homogeneous phase flow is formed in the circulating pipe, so that the density difference is generated, the raw materials circularly flow in the reaction tower, the separator and the circulating pipe, the material turbulence is improved, the diffusion rate is improved, and the reaction rate is improved. Specifically, HCl gas and liquid mixed material with the temperature of 80-90 ℃ and the pressure of 250-550kPa from a gas separator V-1201 enters from the bottom of a chlorination tower to form primary gas-liquid mixed flow in the tower; the raw material HCl with the temperature of 30-40 ℃ and the pressure of 300-. The material after the reaction at the temperature of 80-90 ℃ directly enters a separator 13 from a reaction tower, under the carrying effect of unreacted HCl, a part of products (mainly dichloroethane, chlorohydrin and water) are discharged from the top of a gas-liquid separator 13, cooled to 30-40 ℃ in 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, is pressurized to 350 plus 650kPa and is sent to a circulating gas separator V-1204. The liquid in 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 sent into a recovery tower T-1204 which is a negative pressure rectifying tower, the pressure at the top of the tower is 5-25kPa, the temperature at the top of the tower is 40-75 ℃, the temperature at the bottom of the tower is 140-800 ℃, the mixed product 6 of chloroethylene and glycol is rectified at the top of the tower, unreacted glycol (circulating EG) is recovered at the bottom of the tower, and the part of the circulating EG is boosted to 600-800kPa by a tower kettle pump P-1211 and returned to the reaction part. And the product liquid obtained by separation of the HCl separator V-1202 enters an EDC separation tank V-1203, the layered separation of chloroethylene and dichloroethane is realized by means of different densities of dichloroethane and chloroethanol, the chloroethanol crude product obtained at the upper part enters a recovery tower T-1204 to recover chloroethanol, and the dichloroethane at the lower part enters an EDC receiving tank to obtain a dichloroethane crude product 5.
(2) A second chlorination stage:
the yield of the single product of the chloroethanol or the dichloroethane can be improved by adopting a secondary chlorination process. Namely, fresh HCl and HCl delivered from the recycle gas separator V-1204, are subjected to a secondary chlorination reaction. As shown in figure 1, firstly, fresh HCl and ethylene glycol or chloroethanol preheated to 80-90 ℃ enter an HCl jet pump EJ-1203 for chlorination reaction, then the 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 HCl enters a second chlorination tower T-1202, the pressure of the second chlorination tower is kept at 300-600kPa for complete chlorination reaction, a liquid phase product obtained at the bottom of the tower is conveyed to the chlorination tower T-1201 for product recovery, a gas phase enters a harm removal tower T-1203, tail gas is emptied after absorption of alkali liquor, waste alkali liquor is obtained at the bottom of the tower, the operating temperature of the harm removal tower is 40-80 ℃, and the operating pressure is 100-120 kPa. During the secondary chlorination, if the HCl jet pump EJ-1203 is fed with ethylene glycol, more chloroethanol product is produced, and if the HCl jet pump EJ-1203 is fed with chloroethanol, more dichloroethane is produced.
(3) A rectification separation section:
as shown in figure 2, a mixed product 6 of chloroethanol and ethylene glycol and a crude dichloroethane product 5 are fed into an azeotropic tower T-1205, the pressure at the top of the tower is 100-150kPa, the temperature at the top of the tower is 50-56 ℃, the temperature at the bottom of the tower is 100-105 ℃, azeotrope of dichloroethane and water is obtained at the top of the tower, the temperature after condensation of an azeotropic tower top condenser E1209 is 30-40 ℃, the operating temperature of a reflux tank V-1211 of the azeotropic tower is 30-40 ℃, condensate is stood in the reflux tank for layering, the upper layer is water and flows back into the tower through a reflux pump P-1215 of the azeotropic tower, the lower layer is dichloroethane containing trace water and is fed into the top of an EDC tower T-1206 through an EDC feed pump P-1216, the pressure at the top of the tower is 100-150kPa, the temperature at the top of the tower is 78-87 ℃, the temperature at the bottom of the tower is 90-95 ℃, trace water is removed through rectification, and a refined dichloroethane 10 is obtained at the bottom of the EDC tower, the mass content of dichloroethane reaches more than 99.7 percent, the mixture of dichloroethane and water is removed from the tower top, enters an azeotropic tower top condenser E1209 to be condensed to 30-40 ℃, and enters an azeotropic tower reflux tank V-12011 to be continuously layered and dehydrated. The material at the bottom of the azeotropic tower T-1205 is sent to the dehydrating tower T-1207 by the azeotropic tower 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 without chloroethanol is at the bottom of the tower, the azeotrope of chloroethanol and water is at the top of the tower, the temperature is condensed to 30-40 ℃, one part of the azeotrope flows back, and the other part of the azeotrope is used as a crude chloroethanol 11. The chloroethanol crude product 11 is dehydrated with water by adopting solvents such as benzene or cyclohexane, and the like, desolventized and decompressed and rectified to obtain the 2-chloroethanol with the mass content of more than 99%.
According to the above specific reaction process, the following is a specific reaction example of the present invention:
657.3kg/h of HCl and 553kg/h of ethylene glycol.
(1) A first chlorination reaction:
adopting a triphenylphosphine/aluminum trichloride catalyst with a molar ratio of 2:1, wherein the mass concentration of the catalyst in reaction raw materials is 5.5%, the raw material ethylene glycol is fed at 553kg/h and the circulating ethylene glycol flow is 689kg/h, the mixture is preheated to 60 ℃ in a first-stage EG preheater E1218, the mixture is heated to 80 ℃ in a second-stage EG preheater E1219, the mixture and HCl gas delivered from a circulating gas separator V-1204 with the temperature of 30 ℃ are 1050kg/h, and the mixture enters an EG mixing injection pump EJ-1201 to be mixed with ethylene glycol; the flow rate of fresh hydrogen chloride is 657.3kg/h, the temperature is 30 ℃, the pressure is 600kPa, 6500kg/h of circulating ethylene glycol with the temperature of 80-90 ℃ is conveyed by an ethylene glycol circulating pump circulation P-1201, the circulating ethylene glycol is mixed and subjected to chlorination reaction in an HCl mixing injection pump EJ-1202, the mixed liquid enters an EG mixing injection pump EJ-1201 to continuously react with circulating HCl, and finally enters a gas separator V-1201, the temperature of a gas-liquid mixed fluid flowing out of the top of the gas separator V-1201 is 80 ℃, the pressure is 550kPa, the flow rate is 2949.3kg/h, the 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 450 kPa.
In the chlorination tower, materials with the flow rate of 2949.3kg/h, the temperature of 80 ℃ and the pressure of 550kPa from the gas separator V-1201 enter from the bottom of the chlorination tower to form a primary gas-liquid mixed flow 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 to form secondary gas-liquid mixed flow in the reaction tower, thereby further reducing the liquid density in the reaction tower and accelerating the liquid flow. 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 a gas-liquid separator 13 under the carrying effect of HCl, and are cooled to 30 ℃ after passing through a circulating gas cooler E-1201, the gas-liquid separation is realized in an HCl separator V-1202, the HCl separated from the top enters a circulating gas blower K-1201, the pressure is increased to 650kPa, and the HCl is sent to a circulating gas separator V-1204, and the operation pressure is 600 kPa. The liquid in 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, the extraction amount is 1606.2kg/h, the product is sent into a recovery tower T-1204 which is a negative pressure rectifying tower, the pressure of the tower top is 20kPa, the temperature of the tower top is 68 ℃, the temperature of the tower bottom is 155 ℃, the flow of the mixed product 6 of chloroethylene and dichloroethane rectified from the tower top is 847.2kg/h, the flow of the unreacted ethylene glycol (circulating EG) recovered from the tower bottom is 689kg/h, and the circulating EG is pressurized to 800kPa by a tower bottom pump P-1211 and returned to the reaction part. The product liquid obtained by separation of the HCl separator V-1202 enters an EDC separation tank V-1203, the layered separation of chloroethanol and dichloroethane is realized by means of different densities of dichloroethane and chloroethanol, the chloroethanol crude product obtained at the upper part flows 150kg/h into a recovery tower T-1204 to recover chloroethanol, and the dichloroethane at the lower part flows 361.7kg/h into an EDC receiving tank to obtain the dichloroethane crude product 5.
(2) And (3) second chlorination reaction:
feeding 91.7kg/h of fresh HCl and 630kg/h of chloroethanol preheated to 80 ℃ into an HCl jet pump EJ-1203 for secondary chlorination reaction, then HCl with the flow rate of 200kg/h and the pressure of 600kPa is conveyed from a circulating gas separator V-1204 to enter an exhaust gas jet pump EJ-1204 for chlorination reaction again, then, deep chlorination reaction is carried out in a jet reactor VR-1201, and finally the obtained product enters a second chlorination tower T-1202, the top pressure of the second chlorination tower T-1202 is 400kPa for complete chlorination reaction, 910kg/h of liquid-phase product obtained at the tower bottom is sent into the chlorination tower T-1201 to recover the product, gas phase enters a harm removal tower T-1203, the operation temperature of the harm removal tower is 40 ℃, the operation pressure is 120kPa, after gas is washed and absorbed by alkali liquor, the exhaust gas emptying rate is 1.7kg/h, and waste alkali liquor is obtained at the tower bottom.
(3) Rectification and separation:
847.2kg/h of mixed product 6 of chloroethanol and ethylene glycol and 361.7kg/h of crude dichloroethane product 5 are fed into an azeotropic tower T-1205, the pressure at the top of the azeotropic tower is 120kPa, the temperature at the top of the azeotropic tower is 53 ℃, the temperature at the bottom of the azeotropic tower is 103 ℃, azeotrope of dichloroethane and water is obtained at the top of the azeotropic tower, the temperature after condensation of an azeotropic tower top condenser E1209 is 30 ℃, the operating temperature of a reflux tank V-1211 of the azeotropic tower is 30 ℃, condensate is kept standing and layered in the reflux tank, the water flow of the upper layer is 19.66kg/h, the upper layer flows back into the tower through a reflux pump P-1215 of the azeotropic tower, the water flow of the lower layer is 843.6kg/h, the lower layer is fed into the top of an EDC tower T-1206 through an EDC feed pump P-1216, the pressure at the top of the EDC is 120kPa, the temperature at the top of the tower is 79 ℃, the temperature at the bottom of the tower is 93 ℃, trace moisture is removed by rectification, and the refined dichloroethane 10 flow of the bottom of the dichloroethane is 813kg/h, The mass concentration (purity) of dichloroethane is 99.72%, the mixture of dichloroethane and water is removed from the top of the tower, enters an azeotropic tower top condenser E1209 to be condensed to 30 ℃, and enters an azeotropic tower reflux tank V-12011 to be continuously layered and dehydrated. The output at the bottom of an azeotropic tower T-1205 is 396kg/h, the azeotropic tower is sent to a dehydrating tower T-1207 by an azeotropic tower kettle liquid pump P-1214, the pressure at the top of the tower is 120kPa, the temperature at the top of the tower is 101 ℃, the temperature at the bottom of the tower is 110 ℃, the process water flow for removing the chloroethanol at the bottom of the tower is 242kg/h, the azeotrope of the chloroethanol and water at the top of the tower is condensed to 30 ℃, one part of the azeotrope flows back, and the other part of the azeotrope flows as a chloroethanol crude product 11 and has 154 kg/h. The chloroethanol crude product 11 is dehydrated with water by adopting solvents such as benzene or cyclohexane, etc., and is subjected to desolventizing and reduced pressure rectification to obtain the 2-chloroethanol product with the mass concentration (purity) of 99.2%.
Therefore, the invention can simultaneously prepare high-purity chloroethanol and dichloroethane products from the ethylene glycol by optimizing process equipment, adopting a coupling mode of an injection tubular reactor and a tower reactor and adopting a double-tower coupling rectification separation process, wherein the purity of the dichloroethane product reaches over 99.7 percent, the purity of the chloroethanol product reaches over 99 percent, the production energy consumption is reduced, and meanwhile, the yield of the chloroethanol and the dichloroethane can be flexibly adjusted according to actual requirements; meanwhile, the homogeneous complex salt catalyst is adopted, so that the problems that the catalyst is not easy to recover and separate and the like are solved, and the method has a good effect.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (10)
1. A production process for co-producing chloroethanol and dichloroethane is characterized in that: the process mainly comprises a first chlorination section, a second chlorination section and a rectification separation section; and a homogeneous catalyst is used in the reaction.
2. The co-production process of chloroethanol and dichloroethane as recited in claim 1, further comprising using a homogeneous catalyst as a complex salt, which is triphenylphosphine as a complex carrier and a halide salt as an active component; the mass concentration of the complex salt catalyst in the reaction material is 1-10%.
3. The co-production process of chloroethanol and dichloroethane as recited in claim 2, further comprising the step of mixing one or more chloride salts with the active component; the catalyst comprises triphenylphosphine and chloride salt in a molar ratio of 1: 1-3: 1.
4. A process for the co-production of chloroethanol and dichloroethane according to any one of claims 1 to 3, characterized in that: the first chlorination section and the second chlorination section adopt a reaction mode of combining a tubular spray mode and a tower type.
5. The process for co-producing chloroethanol and dichloroethane according to claim 4, further comprising: 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.
6. The co-production process of chloroethanol and dichloroethane according to any one of claims 1 to 5, wherein the rectification 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.
7. The process for co-producing chloroethanol and dichloroethane according to any one of claims 1 to 6, further comprising the first chlorination stage of: preheating and mixing ethylene glycol and circulating ethylene glycol with a catalyst, mixing the ethylene glycol and HCl gas conveyed by a circulating gas separator, carrying out mixed circulating reaction on the mixed circulating reaction and fresh HCl in various modes on raw materials through a mixed jet pump, and entering a first chlorination tower through a gas separator for continuous reaction; after the reaction of the gas separator, the gas-liquid mixture and corresponding raw materials such as HCl and the like enter different units of a chlorination tower and continue to react in the tower; after the materials are separated from the reaction tower, the unreacted HCl is returned to the mixing jet pump for reaction after cyclic separation treatment and the like; the liquid after reaction realizes the circular reaction through a circulating pipe; the separator separates the bottom liquid to obtain chloroethanol and dichloroethane crude products.
8. The process for co-producing chloroethanol and dichloroethane according to any one of claims 1 to 7, further comprising the second chlorination stage of: firstly, fresh HCl and ethylene glycol or chloroethanol enter an HCl jet pump to enable the ethylene glycol or chloroethanol to continuously carry out chlorination reaction, then the HCl conveyed by a circulating gas separator enters an exhaust jet pump, then enters a jet reactor, finally enters a second chlorination tower to react, a liquid-phase product obtained from the bottom of the tower is sent to a first chlorination tower, and the rest components are subjected to post-treatment to obtain the catalyst.
9. The co-production process of chloroethanol and dichloroethane of claim 8, further comprising feeding ethylene glycol as a feedstock to the HCl jet pump to increase the yield of chloroethanol; or HCl jet pump sends chloroethanol raw material, then improves dichloroethane yield.
10. The co-production process of chloroethanol and dichloroethane according to any one of claims 1 to 9, further comprising the step of introducing the mixed product and crude product into an azeotropic tower, and performing reflux and separation by using an overhead condenser, an azeotropic tower reflux tank, an azeotropic tower reflux pump and the like to obtain high-purity dichloroethane; the material at the bottom of the azeotropic tower is pumped into a dehydrating tower by an azeotropic tower kettle liquid pump, and an azeotrope of chloroethanol and water and a chloroethanol crude product are obtained at the top of the tower; after-treatment of the chloroethanol crude product by a solvent, obtaining high-purity 2-chloroethanol; 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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| 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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| 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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