CN116102429A - Process method for continuously synthesizing N-ethyl ethylenediamine - Google Patents
Process method for continuously synthesizing N-ethyl ethylenediamine Download PDFInfo
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Abstract
The invention belongs to the technical field of chemical industry, and relates to a process method for continuously synthesizing N-ethyl ethylenediamine by using chloroethane and ethylenediamine as raw materials. Synthesizing N-ethyl ethylenediamine by adopting a microchannel continuous flow circulation feeding mode and a continuous haloalkane ammonolysis method, and purifying and separating by a rectification mode after synthesizing to obtain high-yield and high-purity N-ethyl ethylenediamine; and simultaneously, the ethylenediamine is separated for recycling. The reaction product liquid of the invention is circularly fed in the microchannel continuous phase as the third strand after flowing out, thereby avoiding the chain reaction of N-ethyl ethylenediamine and chloroethane and improving the reaction yield. The product and the raw materials are separated and purified by using a reduced pressure distillation and rectification mode, and the ethylenediamine is recovered and reused. The invention has the advantages that the generation of byproducts can be avoided through the continuous micro-channel, the mass transfer is enhanced, the reaction yield is improved, and the energy consumption and the cost can be reduced in the post-treatment process.
Description
Technical Field
The invention belongs to the technical field of chemical industry, and relates to a process method for continuously synthesizing N-ethyl ethylenediamine by using chloroethane and ethylenediamine as raw materials.
Background
N-ethyl ethylenediamine (NEED) is mainly used for producing low-toxicity, high-efficiency and broad-spectrum antibiotic medicines such as piperacillin, cefazolin, cefoperazone and other medical intermediates, and is also widely used for synthesizing pesticides and surfactants. The continuous increase of the demand of cephalosporins also greatly stimulates the increase of the demand of N-ethyl ethylenediamine, an important intermediate thereof. The current method for synthesizing N-ethyl ethylenediamine mainly comprises an aminoethyl sulfate method, an ethanolamine method, an acetic acid method, an haloalkylamine method, an ethanol method and an acrylonitrile method. In contrast, the haloalkane ammonolysis method has the characteristics of simple and easily obtained raw materials, mild reaction conditions, less environmental pollution and suitability for industrial mass production, and is widely researched and used as an industrial synthesis route of N-ethyl ethylenediamine.
The ammonolysis of haloalkane is to introduce haloalkane into ethylenediamine with 2-5 times mole quantity, after the reaction synthesis, naOH aqueous solution is added into the reaction solution, then the organic phase is separated from the aqueous phase. The mixed phase of water and ethylenediamine in the organic phase is then separated off by azeotropic distillation. Finally rectifying to remove the N-heptane, and obtaining the qualified product N-ethyl ethylenediamine. In recent years, various national institutes and production units have improved the synthesis process. In 2012, xu Lufeng et al added ethylenediamine, methanol, sodium methoxide into a high-pressure reaction kettle, pressed ethyl chloride, and then heated to 40℃under a pressure of 0.2MPa, and kept for 4 hours. Filtering to remove sodium chloride after the reaction is finished, rectifying filtrate, and collecting the fraction at 128-130 ℃ to obtain the target product N-ethyl ethylenediamine.
Wei Wenlong and the like drop bromoethane into ethylenediamine at 25 ℃, the mol ratio of ethylenediamine to bromoethane is 5:1, the dropping time is 40min, and the temperature is kept for 2h after the dropping is finished. After the reaction was completed, naOH was added to the reaction mixture, followed by stirring for 30 minutes. Then separating out the organic layer, extracting the water layer with cyclohexane, collecting the organic layer and the extract phase, distilling at normal pressure to recover cyclohexane, and rectifying to collect the fraction at 128-130 ℃. The product yield reaches 64.6 percent. Chen Xiangjun et al modified the post-treatment by dropping ethylene bromide into ethylenediamine, stirring at room temperature for 3 hours, heating to 40℃for 3 hours, and refluxing for 2 hours. Hydrochloric acid was added after the reaction was completed, and distilled under reduced pressure at 70 ℃. The distilled distillate is mainly N-ethyl ethylenediamine, and components with the temperature of more than 106 ℃ are collected through rectification, namely the water-containing N-ethyl ethylenediamine. Then using benzene to carry out azeotropic dehydration, then adding powdery NaOH to carry out dehydration, separating an organic phase, then fractionating, and collecting a fraction at 128-132 ℃ to obtain the N-ethyl ethylenediamine. The two schemes have the defects that the water and the ethylenediamine are difficult to separate, the ethylenediamine and the water are difficult to separate by means of atmospheric distillation, a third component is required to be added for rectification, the energy consumption is high, and the production is not facilitated.
The process of the haloalkane ammonolysis reaction needs to use excessive ethylenediamine to avoid the generation of disubstituted byproducts, but more than 20% of disubstituted byproducts are generated in the reaction process, so that a preparation method with few byproducts, safety and environmental protection is needed.
Disclosure of Invention
The invention aims to provide a continuous process method for synthesizing N-ethyl ethylenediamine, aiming at the defect of the synthesis of N-ethyl ethylenediamine by the existing chloroalkane ammonolysis method.
In order to achieve the above purpose, the invention adopts the technical scheme that:
a technological process for synthesizing N-ethyl ethylenediamine continuously adopts a microchannel continuous flow circulation feeding mode to synthesize N-ethyl ethylenediamine continuously by haloalkane ammonolysis, and the N-ethyl ethylenediamine is purified and separated by a rectification mode after synthesis to obtain high-yield and high-purity N-ethyl ethylenediamine; and simultaneously, the ethylenediamine is separated for recycling.
The micro-channel continuous flow reaction device for the micro-channel continuous flow circulation comprises a micro-reactor, a delay pipeline reactor, a storage tank and a back pressure valve which are sequentially connected through pipelines; and a flow dividing three-way valve is arranged on a pipeline between the delay pipeline reactor and the storage tank, and the circulating material and the outflow material form a circulating path through the flow dividing three-way valve.
The reactor is formed by connecting a dispersing channel and a continuous phase reaction channel in a cross shape; one end of the continuous phase reaction channel is a circulating liquid inlet (103) which is connected with the storage tank through a pipeline, and the other end of the continuous phase reaction channel is used as a reactor outlet (104) which is connected with the delay pipeline reactor through a pipeline; the two ends of the dispersion channel are respectively provided with feed channels (105, 106) for raw materials of chloroethane and ethylenediamine, and the two feed channels are respectively connected with a disperse phase inlet pipeline (101, 102); and the chloroethane disperse phase inlet pipeline is sequentially connected with the high-pressure buffer tank and the chloroethane storage tank through pipelines.
The size of an inlet channel and an outlet channel of the microchannel reactor is 1.5mm, the inner diameter of a dispersion hole is 0.2mm, and the number of the dispersion tube bundles is determined according to the flow velocity. The inner diameter of the delay pipeline is 2mm, and the wall thickness is 1mm.
And a chloroethane high-pressure buffer tank is arranged behind the chloroethane storage tank, and chloroethane liquid in the buffer tank is pumped into the microreactor by using a feed pump and ethylenediamine. A gas cylinder decompression meter and a mass flow controller are arranged between the chloroethane storage tank and the buffer tank to regulate pressure and flow.
The method comprises the following steps:
pumping chloroethane from a chloroethane high-pressure buffer tank and excessive anhydrous ethylenediamine into a micro-channel reactor respectively and simultaneously through two disperse phase inlet pipelines (101 and 102) for alkylation reaction by a feed pump, enabling reaction generating liquid to flow out from a reactor outlet (104) and sequentially enter a delay pipeline reactor through a pipeline, controlling the circulation ratio of the reaction generating liquid by a split-flow three-way valve, enabling the reaction generating liquid to circulate to the reactor for reaction with raw materials, enabling the circulating reaction generating liquid to enter a storage tank, and returning the circulating reaction generating liquid to the micro-reactor through a circulating liquid inlet (103) of the micro-reactor for mixing with the raw materials until the chloroethane is completely consumed, so as to obtain a mixed solution containing N-ethyl ethylenediamine and ethylenediamine;
(2) The mixed solution of N-ethyl ethylenediamine and ethylenediamine is subjected to reduced pressure distillation and rectification to separate and purify raw materials of ethylenediamine, N-ethyl ethylenediamine and di-substituted and poly-substituted byproducts; thereby obtaining high-yield and high-purity N-ethyl ethylenediamine;
(3) Adding alkali into ethylenediamine hydrochloride and N-ethyl ethylenediamine hydrochloride in the reduced pressure distillation process to obtain qualified ethylenediamine, and combining with the obtained ethylenediamine after reduced pressure distillation and rectification purification for direct application.
In the step (1), a chloroethane high-pressure buffer tank is arranged behind the chloroethane storage tank, and chloroethane liquid in the buffer tank is pumped into the microreactor by using a feed pump and ethylenediamine; a gas cylinder decompression meter and a mass flow controller are arranged between the chloroethane storage tank and the buffer tank to regulate pressure and flow; the output pressure of chloroethane in the reaction process is 0.05-0.1MPa; the haloalkane ammonolysis reaction temperature of ethylenediamine and chloroethane is 30-40 ℃; the mol ratio of the ethylenediamine to the chloroethane is 3:1-2.5:1; the circulation ratio of the returned reaction liquid circulation process is 8-10:1.
And (2) performing reduced pressure distillation and rectification to separate ethylenediamine, N-ethylethylenediamine and byproducts, and then adding an entrainer into the system for rectification to separate ethylenediamine, so that the N-ethylethylenediamine and the byproducts are purified and separated by rectification.
As is clear from the above, in the vacuum distillation step in the separation and purification process, the distillate is ethylenediamine, N-ethylethylenediamine, di-substituted by-products and poly-substituted by-products, and the bottom solution of the kettle is 90-95% ethylenediamine hydrochloride and 5-10% N-ethylethylenediamine hydrochloride.
And (3) a rectification step in the separation and purification process, and separating ethylenediamine, N-ethylethylenediamine, di-substituted byproducts and poly-substituted byproducts. And adding an entrainer, separating ethylenediamine by adopting an azeotropic distillation mode, and separating out the entrainer, wherein the entrainer can be recycled. Finally, the product and the by-product are separated by using a common rectification mode.
The temperature of the reduced pressure distillation is 80-100 ℃, and the vacuum pressure of the reduced pressure distillation is 0.095-0.1 Mpa;
the number of the rectifying tower plates is 30-40, and the temperature is 128-130 ℃.
The discharge port at the top of the rectifying tower is provided with a two-phase knockout, the knockout is filled with an entrainer, and along with the occurrence of the rectifying process, the heavy component ethylenediamine is connected out from the discharge port at the lower layer, and the entrainer flows back into the tower from the upper layer.
The entrainer is n-heptane and cyclohexane, and the addition amount of the entrainer is about 1/3 of the volume of the rectification liquid; the temperature of the distilled tower tops of ethylenediamine and n-heptane, and n-heptane and cyclohexane is 86-98 ℃ and 74-80 ℃ respectively.
Adding alkali with the same molar quantity as chloroethane into ethylenediamine hydrochloride and N-ethyl ethylenediamine hydrochloride in the reduced pressure distillation process to treat, so as to obtain qualified and applicable ethylenediamine, wherein 5-10% of N-ethyl ethylenediamine is recycled along with ethylenediamine; wherein the base is a methanol solution containing 30% sodium methoxide (i.e., 30% sodium methoxide+70% methanol) or an aqueous sodium hydroxide solution.
The method for recycling the ethylenediamine from the sodium methoxide comprises the steps of neutralizing the hydrogen chloride by using 30% sodium methoxide methanol solution with the same molar quantity as the hydrogen chloride, separating sodium chloride waste residues generated in the neutralization process from a reaction solution in a filtering mode, removing most of methanol from the separated ethylenediamine-methanol mixed solution in an atmospheric distillation mode, removing the methanol in a rectification mode, and finally obtaining ethylenediamine containing a small amount of N-ethyl ethylenediamine, and completing a mechanically applied experiment.
Wherein, the methanol recovered in the normal pressure distillation and rectification process can be used for repeatedly cleaning the filtered sodium chloride waste residue once, and the ethylenediamine in the waste residue is cleaned until the washing liquid is neutral. The cleaning times are 2-3 times.
The sodium hydroxide recovery mode is to use sodium hydroxide as a neutralizer to recover ethylenediamine, and firstly, 50% sodium hydroxide aqueous solution with the same molar weight as hydrogen chloride is added to complete the neutralization reaction. The method comprises the steps of preliminary filtering and phase separation to obtain an oil phase and a water phase, wherein the water phase is sodium chloride aqueous solution, and the oil phase is ethylenediamine mixed solution containing water and sodium chloride. Gradually adding sodium hydroxide solid into the obtained oil phase to saturation, adsorbing water therein and separating out dissolved sodium chloride, continuing filtering and phase-splitting treatment, carrying out a mechanically neutralizing process on the obtained water phase, collecting distilled components in a reduced pressure distillation mode, wherein the distilled components contain water and ethylenediamine, and finally removing water by using toluene as an entrainer of azeotropic distillation to obtain qualified ethylenediamine containing a small amount of N-ethylenediamine.
Wherein, the sodium hydroxide solution obtained by secondary filtration in the sodium hydroxide recovery process can be used as a neutralizer to complete the neutralization reaction and the application process.
Wherein, the azeotropic temperature of toluene and water is 84-104 ℃, and the toluene and the water can be separated by adopting a phase separation mode; the azeotropic temperature of toluene and ethylenediamine is 104-116 ℃, and the extracted mixed solution is used as the entrainer for the next rectification.
The water content of the ethylenediamine recovered by the two recovery modes is not higher than 2%, and the methanol content is not higher than 5%, otherwise, the ethylenediamine application process is affected.
The invention has the beneficial effects that:
the invention discloses an alkylation synthesis process, a separation and purification process of products and raw materials and a recycling process of ethylenediamine; the method comprises the steps of carrying out alkylation synthesis, namely synthesizing N-ethyl ethylenediamine by adopting continuous micro-channel circulation feeding, wherein on one hand, a micro-reactor can increase mass transfer of reaction, avoid back mixing and avoid the generation of a disubstituted byproduct; on the other hand, the reaction liquid circulation feeding can also improve the reaction selectivity; the method comprises the following steps:
1. the alkylation process of the invention adopts a microchannel continuous circulation feeding method to increase mass transfer, avoid back mixing, avoid the generation of byproducts, improve the reaction yield, reduce the difficulty of post-treatment, reduce the energy consumption, reduce the three wastes and save the cost.
2. The N-ethyl ethylenediamine synthesis process has the characteristics of definition, comprehensiveness and systematicness, comprises an alkylation reaction process, a separation and purification process of products and raw materials and an ethylenediamine recycling process, and is a green environment-friendly process suitable for industrialization.
3. In the alkylation process and the reduced pressure distillation process, the solvent and the acid aqueous solution substances are not added, so that the separation difficulty in the refining process is reduced; meanwhile, the combination of reduced pressure distillation and azeotropic distillation reduces the energy consumption for separating raw materials and products on one hand, and provides convenience for the ethylenediamine recovery process on the other hand.
4. In the recycling process, sodium methoxide and sodium hydroxide are adopted to recycle ethylenediamine, the quality requirement of raw material liquid in the recycling process of ethylenediamine is determined, and finally, the ethylenediamine recycling experiment is completed, and the result is similar to that of fresh ethylenediamine. Meanwhile, the system recovery of ethylenediamine greatly reduces the raw material cost.
Drawings
FIG. 1 is a schematic flow diagram of an alkylation reaction process of the present invention,
FIG. 2 is a schematic view of the microreactor of FIG. 1,
figure 3 is a cross-section of the dispersion channel of the microreactor of figure 2,
wherein 1 is a micro-reactor, two disperse phase inlet pipelines (101, 102), a continuous phase inlet pipeline (103), a reactor outlet pipeline (104) and two disperse channels (105, 106), 2 is a chloroethane storage tank, 3 is a high-pressure buffer tank, 4 is a first constant flow pump, 5 is a second constant flow pump, 6 is a second constant flow pump, 7 is a delay reactor, 8 is a shunt three-way valve, and 9 is a storage tank.
Detailed Description
Compared with the report process, the full-flow process for synthesizing the N-ethyl ethylenediamine has the advantages of simple process flow, low energy consumption and high conversion rate, and ensures the product quality; the whole flow process system is safe, and provides a firm reference basis for the industrialized process.
The invention comprises the processes of synthesizing N-ethyl ethylenediamine, separating and purifying products and raw materials in the microchannel continuous alkylation synthesis process and recycling ethylenediamine; the micro-channel continuous synthesis of N-ethyl ethylenediamine can enhance mass transfer, improve reaction yield, reduce post-treatment difficulty, reduce energy consumption, reduce three wastes and save cost. Because the excess of the ethylenediamine is large, the boiling points of the ethylenediamine and the N-ethyl ethylenediamine are similar, the relative volatility is close to 1, the rectification needs a high column plate number, and the energy consumption is too high. The method of separating ethylenediamine hydrochloride by reduced pressure distillation and then azeotropic distillation is adopted, so that the cost is reduced to the greatest extent and the energy consumption is saved. And finally, neutralizing ethylenediamine hydrochloride to ethylenediamine, and completing the application, thereby realizing the full-process efficient and environment-friendly technical scheme of synthesis, post-treatment and application of N-ethyl ethylenediamine.
Example 1
As shown in fig. 1-3, the microchannel continuous flow reaction device adopted by the microchannel continuous flow circulation comprises a microreactor, a delay pipeline reactor, a storage tank and a back pressure valve which are sequentially connected through pipelines; and a flow dividing three-way valve is arranged on a pipeline between the delay pipeline reactor and the storage tank, and the circulating material and the outflow material form a circulating path through the flow dividing three-way valve.
The reactor is formed by connecting a dispersing channel and a continuous phase reaction channel in a cross shape; one end of the continuous phase reaction channel is a circulating liquid inlet (103) which is connected with the storage tank through a pipeline, and the other end of the continuous phase reaction channel is used as a reactor outlet (104) which is connected with the delay pipeline reactor through a pipeline; the two ends of the dispersion channel are respectively provided with feed channels (105, 106) for raw materials of chloroethane and ethylenediamine, and the two feed channels are respectively connected with a disperse phase inlet pipeline (101, 102); and the chloroethane disperse phase inlet pipeline is sequentially connected with the high-pressure buffer tank and the chloroethane storage tank through pipelines.
And each inlet pipeline is provided with a feed pump.
Example 2
(1) Alkylation reaction process: with the example apparatus, the ethyl chloride storage tank was connected to the high pressure buffer tank via piping, the ethyl chloride liquid was pumped by a first advection pump, and ethylenediamine was pumped by a second advection pump into the microchannel reactor via two dispersed phase inlet piping (101, 102), respectively.
Ethylene diamine was regulated by controlling the feed flow rate: the molar ratio of the chloroethane=3:1, the feeding mass ratio of the chloroethane to the ethylenediamine is 0.36:1, the alkylation reaction is carried out, the reaction temperature is 40 ℃, the reaction generating liquid flows out from the outlet (104) of the reactor and sequentially enters the time-delay pipeline reactor through a pipeline, and the reaction generating liquid is divided into circulating materials and outflow materials according to a certain circulation ratio through a split three-way valve. The circulating materials enter a storage tank, then return to the micro-reactor through a circulating liquid inlet (103) of the micro-reactor, are mixed with raw materials, and the circulating ratio of the returned reaction liquid is controlled to be 9:1 until the chloroethane is completely consumed, and the effluent gas chromatography is used for detection: the purity of N-ethyl ethylenediamine was 92.1%, and the purity of the two disubstituted byproducts was 2.5% and 5.4%, respectively (ethylenediamine in the reaction solution was about 52.03%).
(2) The separation and purification process of the product and the raw materials comprises the following steps:
(1) reduced pressure distillation process: transferring the reaction liquid obtained in the alkylation process into an oil bath heating device, firstly setting the temperature of the oil bath to be 70-80 ℃, and simultaneously starting a vacuum device, wherein the vacuum degree is 0.095-0.1 Mpa. When the temperature of the oil bath rises to 58 ℃, distillate is distilled out from the outlet of the condenser, and the liquid outlet speed is gradually increased along with the rise of the temperature. Distilling under reduced pressure at 80deg.C for 1 hr, slowing the distillate extraction, heating to 110deg.C, evaporating residual amine without acid binding, and collecting distillate. The gas phase analysis results show that the content of ethylenediamine in the distillate is 28.9%, the content of N-ethylethylenediamine is 64.8%, and the contents of the two disubstituted byproducts are 1.8% and 4.5%, respectively. The kettle bottom liquid is acid-bound ethylenediamine and a small amount of N-ethylethylenediamine, wherein the content of ethylenediamine is 94.1%, and the content of N-ethylethylenediamine is 5.9%.
(2) Azeotropic distillation process: mixing the distillate obtained after reduced pressure distillation with an entrainer n-heptane, wherein the volume ratio of the distillate to the entrainer is 3:1. the components are separated and purified by adopting a rectification mode, ethylenediamine is separated by azeotropic rectification, N-ethyl ethylenediamine is separated by conventional rectification, specifically, N-heptane and ethylenediamine are subjected to azeotropy at 86-98 ℃ at first, ethylenediamine is separated from the lower layer according to the phenomenon that N-heptane and ethylenediamine are not mutually dissolved, and light N-heptane flows back into the tower. When the ethylenediamine is completely removed, n-heptane is continuously extracted by rectification, and the temperature is about 98 ℃. Then, N-ethyl ethylenediamine is extracted from the top of the rectifying tower at 128-130 ℃. Through gas phase detection, the purity of distilled ethylenediamine is 99.3%, the purity of the product N-ethyl ethylenediamine is 99.5%, and the yield of single-batch products is 87.3% through calculation.
(3) The recycling and application process of ethylenediamine: 360g of a methanol solution containing 30% sodium methoxide was added to the bottom liquid of the autoclave obtained in the distillation under reduced pressure to neutralize it, and the mixture was stirred at room temperature, filtered to remove solid sodium chloride, and the cake was washed 3 times with methanol. Collecting filtrate and cleaning solution, distilling under normal pressure at 85deg.C under water bath heating to remove methanol, removing methanol by common rectification method, and separating methanol component at 65deg.C at tower top by using a rectification tower with tray number of about 20. The two-step removal of methanol was about 74% and 26%. The gas chromatographic detection shows that the content of ethylenediamine in the recovery liquid is 93.9%, the content of N-ethylethylenediamine is 5.6%, the content of methanol is 0.5%, and the recovery rate of ethylenediamine is 98%.
Example 3
In this example, sodium hydroxide was used as a neutralizing agent to remove hydrogen chloride in the ethylenediamine recycling process, as in the alkylation reaction process, and the separation and purification process of the product and the raw material in example 2. First, 160g of 50% aqueous sodium hydroxide solution was added to the bottom liquid obtained in the distillation under reduced pressure, stirred at room temperature for 1 hour, and then the resultant sodium chloride was removed by filtration at room temperature, followed by preliminary separation of the aqueous phase and the oil phase. And continuously adding 80g of sodium hydroxide solid into the oil phase for drying water treatment, stirring for 30min, filtering and carrying out phase separation treatment. The obtained water phase is used as a neutralizing agent for a mechanically neutralizing process, the obtained oil phase is heated by an oil bath at 100 ℃ and distilled under reduced pressure with the vacuum degree of 0.095-0.1 Mpa to collect distillate components, the components contain water and ethylenediamine, finally toluene is used as an entrainer for azeotropic distillation to remove water, toluene and water are collected at 84-104 ℃, and the toluene and the water can be separated by adopting a phase separation mode; toluene and ethylenediamine are collected at 104-116 ℃, the obtained mixed solution is used as an entrainer for next rectification, and ethylenediamine is collected at 116 ℃. The mixed solution with 6.5 percent of N-ethyl ethylenediamine and 93.5 percent of ethylenediamine is obtained, and the recovery rate of ethylenediamine is 91.7 percent.
Example 4
(1) Alkylation reaction process: with the example apparatus, the ethyl chloride storage tank was connected to the high pressure buffer tank via piping, the ethyl chloride liquid was pumped by a first advection pump, and ethylenediamine was pumped by a second advection pump into the microchannel reactor via two dispersed phase inlet piping (101, 102), respectively.
Ethylene diamine was regulated by controlling the feed flow rate: the molar ratio of the chloroethane=3:1, the feeding mass ratio of the chloroethane to the ethylenediamine is 0.36:1, the alkylation reaction is carried out, the reaction temperature is 10 ℃, the reaction generating liquid flows out from the outlet (104) of the reactor and sequentially enters the time-delay pipeline reactor through a pipeline, and the reaction generating liquid is divided into circulating materials and outflow materials according to a certain circulating ratio through a split three-way valve. The circulating materials enter the storage tank, the circulating materials entering the storage tank are returned to the micro-reactor through a circulating liquid inlet (103) of the micro-reactor and are mixed with the raw materials, the circulating ratio of the returned reaction liquid is controlled to be 12:1 until the chloroethane is completely consumed, and the effluent gas chromatography is used for detection: the purity of N-ethyl ethylenediamine was 93.0%, and the purity of the two disubstituted byproducts was 2.1% and 4.9%, respectively (ethylenediamine in the reaction solution was about 54.4%).
Example 5
(1) Alkylation reaction process: with the example apparatus, the ethyl chloride storage tank was connected to the high pressure buffer tank via a pipeline, ethyl chloride liquid was pumped by a first advection pump, and the recovered ethylenediamine (ethylenediamine content 93.9%) from example 2 was pumped by a second advection pump into the microchannel reactor via two dispersed phase inlet pipelines (101, 102), respectively.
Ethylene diamine was regulated by controlling the feed flow rate: the molar ratio of the chloroethane=3:1, the feeding mass ratio of the chloroethane to the ethylenediamine is 0.34:1, the alkylation reaction is carried out at the reaction temperature of 40 ℃, the reaction generating liquid flows out from the outlet (104) of the reactor and sequentially enters the time-delay pipeline reactor through a pipeline, and the reaction generating liquid is divided into circulating materials and outflow materials according to a certain circulating ratio through a split three-way valve. The circulating materials enter the storage tank, the circulating materials entering the storage tank are returned to the microreactor through the circulating liquid inlet (103) of the microreactor by a pipeline and are mixed with the raw materials, the circulating ratio of the returned reaction liquid is controlled to be 9:1 until the chloroethane is completely consumed, and the effluent gas chromatography is used for detection: the purity of N-ethyl ethylenediamine was 91.7%, and the purity of the two disubstituted byproducts was 2.7% and 5.6%, respectively (ethylenediamine in the reaction solution was about 51.6%).
(2) The separation and purification process of the product and the raw materials comprises the following steps:
(1) reduced pressure distillation process: the same procedure as in example 2 was followed, and the obtained alkylation reaction solution was poured into a vacuum distillation apparatus to distill off the amine which had not been bound with acid. The gas phase analysis results show that the content of ethylenediamine in the distillate is 28%, the content of N-ethylethylenediamine is 65.2%, and the contents of the two disubstituted byproducts are 2.1% and 4.7%, respectively. The kettle bottom liquid is acid-bound ethylenediamine and a small amount of N-ethylethylenediamine, wherein the content of ethylenediamine is 93.4%, and the content of N-ethylethylenediamine is 6.6%.
(2) Azeotropic distillation process: mixing the distilled liquid obtained after reduced pressure distillation with n-heptane serving as an entrainer, wherein the mixing volume ratio is 3:1. the components are separated and purified by adopting a rectification mode, ethylenediamine is separated by azeotropic rectification, N-ethyl ethylenediamine is separated by conventional rectification, specifically, N-heptane and ethylenediamine are subjected to azeotropy at 86-98 ℃ at first, ethylenediamine is separated from the lower layer according to the phenomenon that N-heptane and ethylenediamine are not mutually dissolved, and light N-heptane flows back into the tower. When the ethylenediamine is completely removed, n-heptane is continuously extracted by rectification, and the temperature is about 98 ℃. Then, N-ethyl ethylenediamine is extracted from the top of the rectifying tower at 128-130 ℃. Through gas phase detection, the purity of distilled ethylenediamine is 99.3%, the purity of the product N-ethyl ethylenediamine is 99.5%, and the yield of single-batch products is 86.8% through calculation.
Example 6
(1) Alkylation reaction process: with the example apparatus, the ethyl chloride storage tank was connected to the high pressure buffer tank via a pipeline, ethyl chloride liquid was pumped by a first advection pump, and the recovered ethylenediamine (ethylenediamine content 93.5%) in example 3 was pumped by a second advection pump into the microchannel reactor via two dispersed phase inlet pipelines (101, 102), respectively.
Ethylene diamine was regulated by controlling the feed flow rate: the molar ratio of the chloroethane=3:1, the feeding mass ratio of the chloroethane to the ethylenediamine is 0.34:1, the alkylation reaction is carried out at the reaction temperature of 40 ℃, the reaction generating liquid flows out from the outlet (104) of the reactor and sequentially enters the time-delay pipeline reactor through a pipeline, and the reaction generating liquid is divided into circulating materials and outflow materials according to a certain circulating ratio through a split three-way valve. The circulating materials enter the storage tank, the circulating materials entering the storage tank are returned to the microreactor through the circulating liquid inlet (103) of the microreactor by a pipeline and are mixed with the raw materials, the circulating ratio of the returned reaction liquid is controlled to be 9:1 until the chloroethane is completely consumed, and the effluent gas chromatography is used for detection: the purity of N-ethyl ethylenediamine was 91.1%, and the purity of the two disubstituted byproducts was 2.9% and 6.0%, respectively (ethylenediamine in the reaction solution was about 52.9%).
(2) The separation and purification process of the product and the raw materials comprises the following steps:
(1) reduced pressure distillation process: the same procedure as in example 2 was followed, and the obtained alkylation reaction solution was poured into a vacuum distillation apparatus, and the amine which had not been bound with acid was distilled off to collect the distillate. The gas phase analysis results show that the content of ethylenediamine in the distillate is 28.5%, the content of N-ethylethylenediamine is 65.0%, and the contents of the two disubstituted byproducts are 2.2% and 4.3%, respectively. The kettle bottom liquid is acid-bound ethylenediamine and a small amount of N-ethylethylenediamine, wherein the content of ethylenediamine is 94.1%, and the content of N-ethylethylenediamine is 5.9%.
(2) Azeotropic distillation process: mixing the distilled liquid after reduced pressure distillation with n-heptane serving as an entrainer, wherein the mixing volume ratio is 3:1. the components are separated and purified by adopting a rectification mode, ethylenediamine is separated by azeotropic rectification, N-ethyl ethylenediamine is separated by conventional rectification, specifically, N-heptane and ethylenediamine are subjected to azeotropy at 86-98 ℃ at first, ethylenediamine is separated from the lower layer according to the phenomenon that N-heptane and ethylenediamine are not mutually dissolved, and light N-heptane flows back into the tower. When the ethylenediamine is completely removed, n-heptane is continuously extracted by rectification, and the temperature is about 98 ℃. Then, N-ethyl ethylenediamine is extracted from the top of the rectifying tower at 128-130 ℃. Through gas phase detection, the purity of distilled ethylenediamine is 99.4%, the purity of the product N-ethyl ethylenediamine is 99.5%, and the yield of single-batch products is 87.0% through calculation.
Comparative example
First, 360g of ethylenediamine was added to a reactor, and the raw material liquid was adjusted to 40℃by using a water bath heating device. The ethyl chloride flowing from the ethyl chloride storage tank is regulated by using a pressure regulating valve and a mass flow controller. And the chloroethane liquid is introduced into the reaction kettle through the feed pump, a certain feed rate is controlled, the feed time is ensured to be 1h, and ethylenediamine is regulated: the reaction mole ratio of the chloroethane is 3:1, a total of 130g of chloroethane. Then the mixture is stirred for 30min at 40 ℃ to lead the unconverted chloroethane to react completely. The conversion of chloroethane was 100% by gas chromatography, the purity of N-ethyl ethylenediamine in the resultant was 83.6%, and the purity of the two disubstituted byproducts was 5.5% and 10.9%, respectively. The yield of the single batch product after post-treatment is 74.5%.
Claims (9)
1. A process method for continuously synthesizing N-ethyl ethylenediamine is characterized in that: synthesizing N-ethyl ethylenediamine by adopting a microchannel continuous flow circulation feeding mode and a continuous haloalkane ammonolysis method, and purifying and separating by a rectification mode after synthesizing to obtain high-yield and high-purity N-ethyl ethylenediamine; and simultaneously, the ethylenediamine is separated for recycling.
2. The process for the continuous synthesis of N-ethylethylenediamine according to claim 1, wherein: the micro-channel continuous flow reaction device for the micro-channel continuous flow circulation comprises a micro-reactor, a delay pipeline reactor, a storage tank and a back pressure valve which are sequentially connected through pipelines; and a flow dividing three-way valve is arranged on a pipeline between the delay pipeline reactor and the storage tank, and the circulating material and the outflow material form a circulating path through the flow dividing three-way valve.
3. The process for the continuous synthesis of N-ethylethylenediamine according to claim 2, wherein: the reactor is formed by connecting a dispersing channel and a continuous phase reaction channel in a cross shape; one end of the continuous phase reaction channel is a circulating liquid inlet (103) which is connected with the storage tank through a pipeline, and the other end of the continuous phase reaction channel is used as a reactor outlet (104) which is connected with the delay pipeline reactor through a pipeline; the two ends of the dispersion channel are respectively provided with feed channels (105, 106) for raw materials of chloroethane and ethylenediamine, and the two feed channels are respectively connected with a disperse phase inlet pipeline (101, 102); and the chloroethane disperse phase inlet pipeline is sequentially connected with the high-pressure buffer tank and the chloroethane storage tank through pipelines.
4. A process for the continuous synthesis of N-ethylethylenediamine according to any of claims 1 to 3, characterized in that:
(1) Pumping chloroethane from a chloroethane high-pressure buffer tank and excessive anhydrous ethylenediamine into a micro-channel reactor respectively and simultaneously through two disperse phase inlet pipelines (101 and 102) for alkylation reaction by a feed pump, enabling reaction generating liquid to flow out from a reactor outlet (104) and sequentially enter a delay pipeline reactor through a pipeline, controlling the circulation ratio of the reaction generating liquid by a split-flow three-way valve, enabling the reaction generating liquid to circulate to the reactor for reaction with raw materials, enabling the circulating reaction generating liquid to enter a storage tank, and returning the circulating reaction generating liquid to the micro-reactor through a circulating liquid inlet (103) of the micro-reactor for mixing with the raw materials until the chloroethane is completely consumed, so as to obtain a mixed solution containing N-ethyl ethylenediamine and ethylenediamine;
(2) The mixed solution of N-ethyl ethylenediamine and ethylenediamine is subjected to reduced pressure distillation and rectification to separate and purify raw materials of ethylenediamine, N-ethyl ethylenediamine and di-substituted and poly-substituted byproducts; thereby obtaining high-yield and high-purity N-ethyl ethylenediamine;
(3) Adding alkali into ethylenediamine hydrochloride and N-ethyl ethylenediamine hydrochloride in the reduced pressure distillation process to obtain qualified ethylenediamine, and combining with the obtained ethylenediamine after reduced pressure distillation and rectification purification for direct application.
5. The process for the continuous synthesis of N-ethylethylenediamine according to claim 4, wherein: in the step (1), a chloroethane high-pressure buffer tank is arranged behind the chloroethane storage tank, and chloroethane liquid in the buffer tank is pumped into the microreactor by using a feed pump and ethylenediamine; a gas cylinder decompression meter and a mass flow controller are arranged between the chloroethane storage tank and the buffer tank to regulate pressure and flow; the output pressure of chloroethane in the reaction process is 0.05-0.1MPa; the haloalkane ammonolysis reaction temperature of ethylenediamine and chloroethane is 30-40 ℃; the mol ratio of the ethylenediamine to the chloroethane is 3:1-2.5:1; the circulation ratio of the returned reaction liquid circulation process is 8-10:1.
6. The process for the continuous synthesis of N-ethylethylenediamine according to claim 4, wherein: and (2) performing reduced pressure distillation and rectification to separate ethylenediamine, N-ethylethylenediamine and byproducts, and then adding an entrainer into the system for rectification to separate ethylenediamine, so that the N-ethylethylenediamine and the byproducts are purified and separated by rectification.
7. The process for continuously synthesizing N-ethylethylenediamine according to claim 6, wherein: the temperature of the reduced pressure distillation is 80-100 ℃, and the vacuum pressure of the reduced pressure distillation is 0.095-0.1 Mpa; the number of the rectifying tower plates is 30-40, and the temperature is 128-130 ℃.
8. The process for the continuous synthesis of N-ethylethylenediamine according to claim 7, wherein: the entrainer is n-heptane and cyclohexane, and the addition amount of the entrainer is about 1/3 of the volume of the rectification liquid; the temperature of the distilled tower tops of ethylenediamine and n-heptane, and n-heptane and cyclohexane is 86-98 ℃ and 74-80 ℃ respectively.
9. The process for the continuous synthesis of N-ethylethylenediamine according to claim 4, wherein: adding alkali with the same molar quantity as chloroethane into ethylenediamine hydrochloride and N-ethyl ethylenediamine hydrochloride in the reduced pressure distillation process to treat, so as to obtain qualified and applicable ethylenediamine, wherein 5-10% of N-ethyl ethylenediamine is recycled along with ethylenediamine; wherein the alkali is methanol solution or sodium hydroxide aqueous solution containing 30% sodium methoxide.
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