CN116102429A - Process method for continuously synthesizing N-ethyl ethylenediamine - Google Patents

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

A kind of process method of continuous synthesis of N-ethylethylenediamine

technical field

The invention belongs to the technical field of chemical industry and relates to a process method for continuously synthesizing N-ethylethylenediamine by taking ethyl chloride and ethylenediamine as raw materials.

Background technique

N-Ethylethylenediamine (NEED) is mainly used in the production of pharmaceutical intermediates such as low-toxicity, high-efficiency, and broad-spectrum antibiotics such as penicillin, cefrazone, and cefoperazone, and is also widely used in pesticides and surfactants Synthesis. The continuous growth of demand for cephalosporins has also greatly stimulated the growth of demand for its important intermediate N-ethylethylenediamine. At present, the methods for synthesizing N-ethylethylenediamine mainly include aminoethylsulfate method, ethanolamine method, acetic acid method, halogenated alkyl ammonolysis method, ethanol method and acrylonitrile method. Relatively speaking, the halogenated alkyl ammonolysis method has the characteristics of simple and easy-to-obtain raw materials, mild reaction conditions, less environmental pollution, and is suitable for industrial scale production. It has been widely studied and used as an industrial synthesis route for N-ethylethylenediamine.

The haloalkane ammonolysis method is mainly to pass the haloalkane into 2-5 times the molar amount of ethylenediamine, add NaOH aqueous solution to the reaction liquid after reaction synthesis, and then separate the organic phase from the water phase. Then, the mixed phase of water and ethylenediamine in the organic phase is separated by means of azeotropic distillation. Finally, the n-heptane is removed by rectification, and the qualified product N-ethylethylenediamine is obtained. In recent years, various domestic research institutes and production units have improved the synthesis process one after another. In 2012, Xu Lufeng et al. added ethylenediamine, methanol, and sodium methoxide to a high-pressure reactor, pressed in ethyl chloride, raised the temperature to 40°C, and kept the temperature at 0.2MPa for 4 hours. After the reaction is completed and the sodium chloride is removed by filtration, the filtrate is rectified and the fraction at 128-130°C is collected to obtain the target product N-ethylethylenediamine.

Wei Wenlong et al. added bromoethane dropwise into ethylenediamine at 25°C, the molar ratio of ethylenediamine to bromoethane was 5:1, the dropping time was 40min, and the temperature was kept for 2h after the dropping was completed. After the reaction was completed, NaOH was added to the reaction solution and the stirring was continued for 30 min. Then the organic layer was separated, the water layer was extracted with cyclohexane, the organic layer and the extract phase were collected, the cyclohexane was recovered by atmospheric distillation, and the fraction at 128-130° C. was collected by rectification. The product yield reaches 64.6%. Chen Xiangjun and others improved the post-treatment method. First, bromoethane was dropped into ethylenediamine, stirred at room temperature for 3 hours, then heated to 40 degrees for 3 hours, and then refluxed for 2 hours. After the reaction was completed, hydrochloric acid was added, and it was distilled under reduced pressure at 70°C. The distillate after distillation is mainly N-ethylethylenediamine, and the component >106°C is collected by rectification, that is, water-containing N-ethylethylenediamine. Then use benzene for azeotropic dehydration, then add powdered NaOH for dehydration, separate the organic phase and then fractionate, collect the fraction at 128-132°C to obtain N-ethylethylenediamine. The disadvantage of the above two solutions is that it is difficult to separate water and ethylenediamine, and it is difficult to separate ethylenediamine and water by means of atmospheric distillation. It is necessary to add a third component for rectification, which consumes a lot of energy and is not conducive to production.

The ammonolysis reaction process of haloalkanes requires the use of excess ethylenediamine to avoid the formation of disubstituted by-products, but >20% of di-substituted by-products are still generated during the reaction process, and a safe and environmentally friendly preparation method with less by-products is required.

Contents of the invention

The object of the present invention is to provide a kind of technical method of continuous synthesis N-ethylethylenediamine aiming at the shortcomings of present chlorinated alkyl ammonolysis method for synthesizing N-ethylethylenediamine.

In order to achieve the above object, the technical solution adopted by the present invention is:

A continuous process for synthesizing N-ethylethylenediamine, adopting the microchannel continuous flow circulation feeding method to continuously synthesize N-ethylethylenediamine through haloalkane ammonolysis method, after synthesis, purify and separate by rectification to obtain high-quality Yield, high-purity N-ethylethylenediamine; at the same time, the ethylenediamine is separated for recycling.

The microchannel continuous flow reaction device adopted in the microchannel continuous flow circulation includes a microreactor, a time-delay pipeline reactor, a storage tank and a back pressure valve connected successively by pipelines; a pipe between the time-delay pipeline reactor and the storage tank A diverter three-way valve is set on the road, and the circulating material and the effluent material form a circulation path through the diverter three-way valve.

The reactor is connected by a dispersing channel and a continuous phase reaction channel in a cross; one end of the continuous phase reaction channel is a circulating liquid inlet (103) connected to the storage tank through a pipeline, and the other end is used as a reactor outlet (104) through a pipeline to extend When the pipeline reactor is connected; the two ends of the dispersion channel are respectively feed channels (105,106) of raw material ethyl chloride and ethylenediamine, and the two feed channels are respectively connected to the dispersed phase inlet pipeline (101,102); the chlorine The ethane dispersed phase inlet pipeline is connected to the high-pressure buffer tank and the ethyl chloride storage tank in sequence through the pipeline.

The size of the inlet and outlet channels of the microchannel reactor is 1.5 mm, the inner diameter of the dispersion holes is 0.2 mm, and the number of dispersion tube bundles depends on the flow rate. The delay pipe has an inner diameter of 2mm and a wall thickness of 1mm.

An ethyl chloride high-pressure buffer tank is provided behind the ethyl chloride storage tank, and the ethyl chloride liquid in the buffer tank is simultaneously pumped into the microreactor by a feed pump and ethylenediamine. A gas cylinder decompression gauge and a mass flow controller are installed between the ethyl chloride storage tank and the buffer tank to adjust the pressure and flow.

Specifically:

Through the feed pump, ethyl chloride is pumped into the microchannel reactor through the two dispersed phase inlet pipelines (101, 102) at the same time from the ethyl chloride high-pressure buffer tank and excess anhydrous ethylenediamine for alkylation Reaction, the reaction product flows out from the reactor outlet (104) and enters the delay pipeline reactor sequentially through the pipeline, and then passes through the split three-way valve to control the circulation ratio of the reaction product liquid, so that it circulates to the reactor to react with the raw materials, and then circulates The reaction product liquid enters the storage tank, and then returns to the microreactor through the circulating liquid inlet (103) of the microreactor, and mixes with the raw materials until all ethyl chloride is consumed to obtain N-ethylethylenediamine, ethylenediamine Mixed solution of amine;

(2) The above-mentioned mixed solution of N-ethylethylenediamine and ethylenediamine is subjected to vacuum distillation and rectification to carry out the raw material ethylenediamine, product N-ethylethylenediamine and disubstituted and multi-substituted Separation and purification of by-products; and then obtain high-yield, high-purity N-ethylethylenediamine;

(3) Ethylenediamine hydrochloride and N-ethylethylenediamine hydrochloride in the vacuum distillation process are added with alkali and processed to obtain quality qualified ethylenediamine, which is combined with the above-mentioned vacuum distillation and rectification purification Obtained ethylenediamine combined directly applied mechanically.

In the step (1), the ethyl chloride high-pressure buffer tank is provided behind the ethyl chloride storage tank, and the ethyl chloride liquid in the buffer tank is pumped into the microreactor simultaneously with a feed pump and ethylenediamine; Between the alkane storage tank and the buffer tank, there is a gas cylinder decompression gauge and a mass flow controller to adjust the pressure and flow; the output pressure of ethyl chloride is 0.05-0.1MPa during the reaction process; The temperature is 30-40° C.; the molar ratio of ethylenediamine and ethyl chloride is 3:1-2.5:1; the circulation ratio of the returned reaction liquid circulation process is 8-10:1.

Underpressure distillation and rectification in the described step (2) are first vacuum distillation to separate ethylenediamine, N-ethylethylenediamine and by-products, and then carry out rectification by adding an entrainer in the system, so that Ethylenediamine is separated, and then rectified to realize the purification and separation of N-ethylethylenediamine and by-products.

It can be seen from the above that in the vacuum distillation step of the separation and purification process, the distillate is ethylenediamine, N-ethylethylenediamine, disubstituted by-products and multi-substituted by-products, and the bottom liquid is 90-95% ethylenediamine Hydrochloride and 5-10% N-ethylethylenediamine hydrochloride.

In the rectification step of the separation and purification process, ethylenediamine, N-ethylethylenediamine, disubstituted by-products and multi-substituted by-products are separated. Add an azeotropic agent, use azeotropic distillation to separate ethylenediamine first, and then separate the azeotrope agent. The azeotrope agent can be recycled. Finally, the products and by-products are separated by means of ordinary rectification.

The temperature of the vacuum distillation is 80-100°C, and the vacuum pressure of the vacuum distillation is 0.095--0.1Mpa;

The number of the rectifying trays is 30-40, and the temperature is 128-130°C.

The outlet at the top of the rectification tower is provided with a two-phase liquid separator. First, the liquid separator is filled with an entrainer. With the rectification process, the heavy component ethylenediamine is taken out from the discharge port of the lower layer. , the entrainer flows back into the tower from the top.

Described entrainer is normal heptane, hexanaphthene, and the add-on of entrainer is about 1/3 of rectification liquid volume; The top temperatures are 86-98°C and 74-80°C, respectively.

Ethylenediamine hydrochloride and N-ethylethylenediamine hydrochloride in the vacuum distillation process are added with an alkali in an equimolar amount with ethyl chloride for treatment to obtain qualified applicable ethylenediamine, 5- 10% N-ethylethylenediamine is reused together with ethylenediamine; wherein, the base is methanol solution containing 30% sodium methoxide (ie, 30% sodium methoxide+70% methanol) or sodium hydroxide aqueous solution.

The method for recovering ethylenediamine from sodium methoxide is to first neutralize hydrogen chloride with a methanol solution of 30% sodium methoxide in an equimolar amount to hydrogen chloride, and separate the sodium chloride waste residue generated during the neutralization process from the reaction solution by filtering, The separated ethylenediamine-methanol mixture is firstly removed most of the methanol by atmospheric distillation, and the methanol is removed by rectification, and finally ethylenediamine containing a small amount of N-ethylethylenediamine is obtained, and the mechanical experiment is completed. .

Among them, the methanol recovered in the atmospheric distillation and rectification process can be used to repeatedly clean the sodium chloride waste residue filtered once, and the ethylenediamine in the waste residue is washed until the washing liquid is neutral. The cleaning times are 2-3 times.

The sodium hydroxide recovery method is to use sodium hydroxide as a neutralizing agent to recover ethylenediamine, and first add a 50% aqueous sodium hydroxide solution with an equimolar amount of hydrogen chloride to complete the neutralization reaction. An oil phase and a water phase are obtained through preliminary filtration and phase separation, the water phase is an aqueous solution of sodium chloride, and the oil phase is a mixed solution of ethylenediamine containing water and sodium chloride. Gradually add solid sodium hydroxide to the obtained oil phase to saturation, absorb the moisture therein and separate out dissolved sodium chloride, continue to filter and phase-separate, and apply the neutralization process to the obtained water phase. The distilled components are collected by pressure distillation, and the components contain water and ethylenediamine. Finally, toluene is used as the entrainer for azeotropic distillation to remove water, and ethylenediamine containing a small amount of N-ethylethylenediamine with qualified quality is obtained. amine.

Wherein, the sodium hydroxide solution obtained by secondary filtration in the sodium hydroxide recovery process can be used as a neutralizing agent to complete the neutralization reaction and complete the mechanical application process.

Among them, the azeotropic temperature of toluene and water is 84-104°C, and the phase separation method can be used to separate toluene and water; the azeotropic temperature of toluene and ethylenediamine is 104-116°C, and the mixed solution produced Entrainer for secondary distillation.

In the ethylenediamine recovered by the two recovery methods, the water content shall not be higher than 2%, and the methanol content shall not be higher than 5%, otherwise the mechanical application process of ethylenediamine will be affected.

Beneficial effects of the present invention:

The alkylation synthesis process, the separation and purification process of products and raw materials, and the recovery and application process of ethylenediamine in the present invention; wherein, the alkylation synthesis process adopts continuous microchannel circulation feeding to synthesize N-ethylethylenediamine, on the one hand micro The reactor can increase the mass transfer of the reaction, avoid back mixing, and avoid the generation of secondary substitution by-products; on the other hand, the circulating feed of the reaction liquid can also improve the selectivity of the reaction; specifically:

1. The alkylation process of the present invention adopts the method of microchannel continuous circulation feeding to increase mass transfer, avoid reverse mixing, avoid the generation of by-products, improve reaction yield, reduce the difficulty of post-processing, reduce energy consumption, and reduce three wastes Quantity, cost saving.

2. The N-ethylethylenediamine synthesis process of the present invention has clear, comprehensive and systematic features, including the alkylation reaction process, the separation and purification process of products and raw materials, and the recovery and application process of ethylenediamine. It is a process suitable for industrialization green environmental protection technology.

3. In the alkylation process and vacuum distillation process, the present invention does not add solvents and acidic aqueous solution substances, which reduces the difficulty of separation in the refining process; at the same time, the combination of vacuum distillation and azeotropic distillation reduces the The energy consumption of separating raw materials and products, on the other hand, also provides convenient conditions for the recovery process of ethylenediamine.

4, adopt sodium methylate and sodium hydroxide to reclaim ethylenediamine in the recycling process of the present invention, and have determined the quality requirement of reclaiming ethylenediamine process raw material liquid, finally finished the ethylenediamine application experiment, the result and fresh ethylenediamine similar. At the same time, the systematic recovery of ethylenediamine greatly reduces the cost of raw materials.

Description of drawings

Fig. 1 is a schematic diagram of the process flow of the alkylation reaction of the present invention,

Fig. 2 is the microreactor structure schematic diagram among Fig. 1,

Fig. 3 is the cross-section of microreactor dispersion channel among Fig. 2,

Wherein, 1 is a microreactor, two dispersed phase inlet pipelines (101,102), continuous phase inlet pipeline (103), reactor outlet pipeline (104) and two dispersed channels (105,106), 2 is the ethyl chloride storage tank, 3 is the high-pressure buffer tank, 4 is the first constant flow pump, 5 is the second constant flow pump, 6 is the second constant flow pump, 7 is the delay reactor, and 8 is the split three-way valve , 9 is the storage tank.

Detailed ways

Compared with the reported process, the present invention has the advantages of simple technological process, low energy consumption, and high conversion rate while ensuring product quality; the entire process is systematic and safe, and is The industrialization process provides a solid reference.

The present invention includes the process of synthesizing N-ethylethylenediamine through the continuous alkylation synthesis process of microchannels, the separation and purification of products and raw materials, and the recycling process of ethylenediamine; wherein, the continuous synthesis of N-ethylethylenediamine through microchannels It can enhance mass transfer, improve reaction yield, reduce the difficulty of post-processing, reduce energy consumption, reduce the amount of three wastes, and save costs. Since the excess of ethylenediamine is large, and ethylenediamine and N-ethylethylenediamine have similar boiling points and relative volatility close to 1, rectification requires a high number of plates and high energy consumption. The method of separating ethylenediamine hydrochloride by vacuum distillation first, and then azeotropic distillation to separate ethylenediamine can reduce the cost and save energy to the greatest extent. Finally, the ethylenediamine hydrochloride is neutralized into ethylenediamine, and the mechanical application is completed, so as to realize the high-efficiency and environment-friendly technical scheme of the whole process of synthesis, post-treatment and mechanical application of N-ethylethylenediamine.

Example 1

As shown in Figure 1-3, the microchannel continuous flow reaction device that described microchannel continuous flow circulation adopts comprises the microreactor, delay pipeline reactor, storage tank and back pressure valve that are connected successively by pipeline; A diverter three-way valve is installed on the pipeline between the reactor and the storage tank, and the circulating material and the effluent material form a circulation path through the diverter three-way valve.

The reactor is connected by a dispersing channel and a continuous phase reaction channel in a cross; one end of the continuous phase reaction channel is a circulating liquid inlet (103) connected to the storage tank through a pipeline, and the other end is used as a reactor outlet (104) through a pipeline to extend When the pipeline reactor is connected; the two ends of the dispersion channel are respectively feed channels (105,106) of raw material ethyl chloride and ethylenediamine, and the two feed channels are respectively connected to the dispersed phase inlet pipeline (101,102); the chlorine The ethane dispersed phase inlet pipeline is connected to the high-pressure buffer tank and the ethyl chloride storage tank in sequence through the pipeline.

A feeding pump is arranged on each of the above-mentioned inlet pipelines.

Example 2

(1) Alkylation reaction process: using the embodiment device, the ethyl chloride storage tank is connected to the high-pressure buffer tank through the pipeline, the ethyl chloride liquid is passed through the first advection pump, and the ethylenediamine is passed through the second advection pump respectively. The two dispersed-phase inlet pipes (101, 102) are pumped into the microchannel reactor.

Regulate ethylenediamine by controlling the feed flow rate: chloroethane molar ratio=3:1, the feed mass ratio of chloroethane and ethylenediamine is 0.36:1, carry out alkylation reaction, reaction temperature is 40 ℃, reaction produces The liquid flows out from the reactor outlet (104) through the pipeline and enters the delay pipeline reactor sequentially, and then passes through the split three-way valve to divide the reaction liquid into a circulating material and an effluent material according to a certain circulation ratio. The circulating material enters the storage tank, returns to the microreactor through the circulating liquid inlet (103) of the microreactor, mixes with the raw material, and controls the circulation ratio of the returned reaction liquid to be 9:1 until all the ethyl chloride is consumed and flows out Material gas chromatography detection: the purity of N-ethylethylenediamine is 92.1%, and the purity of two kinds of disubstituted by-products are respectively 2.5% and 5.4% (ethylenediamine accounts for about 52.03% in the reaction liquid).

(2) Separation and purification process of products and raw materials:

①Vacuum distillation process: transfer the reaction liquid obtained in the alkylation process to an oil bath heating device, first set the oil bath temperature to 70-80°C, and at the same time turn on the vacuum device, the vacuum degree is 0.095--0.1Mpa. When the temperature of the oil bath rises to 58°C, distillate begins to distill out from the outlet of the condenser, and as the temperature rises, the speed of the liquid gradually increases. Distill under reduced pressure in an oil bath at 80°C for 1 hour, the extraction rate of the distillate slows down, raise the temperature of the oil bath to 110°C, distill out the remaining unbound amine as much as possible, and collect the distillate. As determined by gas phase analysis, the content of ethylenediamine in the distillate is 28.9%, the content of N-ethylethylenediamine is 64.8%, and the contents of two disubstituted by-products are 1.8% and 4.5% respectively. The 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%.

②Azeotropic distillation process: Mix the above-mentioned distillate after vacuum distillation with the entrainer n-heptane, wherein the volume ratio of the distillate to the entrainer is 3:1. The components are separated and purified by rectification, ethylenediamine is separated by azeotropic rectification, and N-ethylethylenediamine is separated by conventional rectification. Specifically, n-heptane and ethylenediamine azeotrope first, The boiling point is 86-98°C. According to the immiscibility of n-heptane and ethylenediamine, the lower layer separates ethylenediamine, and the light component n-heptane flows back into the tower. When all ethylenediamine is removed, continue to extract n-heptane by rectification, the temperature is about 98°C. Subsequently, the product N-ethylethylenediamine is extracted at a temperature of 128-130° C. at the top of the rectification tower. Through gas phase detection, the purity of the distilled ethylenediamine is 99.3%, the purity of the product N-ethylethylenediamine is 99.5%, and the calculated single batch product yield is 87.3%.

(3) Ethylenediamine recovery process: add 360g methanol solution containing 30% sodium methoxide to the bottom liquid obtained in the vacuum distillation process for neutralization, filter and remove solid sodium chloride after stirring at normal temperature, and use methanol Wash the filter cake 3 times. Collect the filtrate and cleaning solution, first distill methanol under atmospheric pressure under heating in a water bath at 85°C, and then use ordinary rectification to remove methanol, use a rectification tower with about 20 plates, and the temperature at the top of the separation tower is 65°C Methanol component. The proportion of methanol removed by two steps is about 74% and 26%. Through gas chromatography detection, it can be seen that the content of ethylenediamine in the recovered liquid is 93.9%, that of N-ethylethylenediamine is 5.6%, that of methanol is 0.5%, and the recovery rate of ethylenediamine is 98%.

Example 3

The same as the alkylation reaction process and the separation and purification process of products and raw materials in Example 2, this example uses sodium hydroxide as a neutralizing agent to remove hydrogen chloride during the recovery and application of ethylenediamine. First, add 160g of 50% sodium hydroxide aqueous solution to the still bottom liquid obtained in the vacuum distillation process, stir at normal temperature for 1h, then filter at normal temperature to remove the sodium chloride generated, and then preliminarily separate the water phase and the oil phase. Continue to add 80 g of solid sodium hydroxide to the oil phase for dry water treatment, stir for 30 min, filter and perform phase separation. The obtained water phase is used as a neutralizing agent to carry out the neutralization process. The obtained oil phase is heated in an oil bath at 100°C and the vacuum degree is 0.095--0.1Mpa to collect the distilled components. The components contain water and ethyl alcohol. Diamine, finally use toluene as the entrainer for azeotropic distillation to remove water, collect toluene and water at 84-104°C, and separate toluene and water by phase separation; collect toluene and ethylene glycol at 104-116°C Amine, the mined mixed solution is used as the entrainer for the next rectification, and ethylenediamine is collected at 116°C. A mixed liquid containing 6.5% of N-ethylethylenediamine and 93.5% of ethylenediamine was obtained, and the recovery rate of ethylenediamine was 91.7%.

Example 4

(1) Alkylation reaction process: using the embodiment device, the ethyl chloride storage tank is connected to the high-pressure buffer tank through the pipeline, the ethyl chloride liquid is passed through the first advection pump, and the ethylenediamine is passed through the second advection pump respectively. The two dispersed-phase inlet pipes (101, 102) are pumped into the microchannel reactor.

Regulate ethylenediamine by controlling the feed flow rate: chloroethane molar ratio=3:1, the feed mass ratio of chloroethane and ethylenediamine is 0.36:1, carry out alkylation reaction, reaction temperature is 10 ℃, reaction produces The liquid flows out from the reactor outlet (104) through the pipeline and enters the delay pipeline reactor sequentially, and then passes through the split three-way valve to divide the reaction liquid into a circulating material and an effluent material according to a certain circulation ratio. The circulating material enters the storage tank, and the circulating material entering the storage tank returns to the microreactor through the circulating liquid inlet (103) of the microreactor, mixes with the raw material, and controls the circulation ratio of the returned reaction solution to be 12:1 until the ethyl chloride Alkanes are all consumed, and the effluent gas chromatography detection: the purity of N-ethylethylenediamine is 93.0%, and the purity of two kinds of disubstituted by-products are respectively 2.1% and 4.9% (ethylenediamine accounts for about 54.4% in the reaction solution) .

Example 5

(1) Alkylation reaction process: using the embodiment device, the ethyl chloride storage tank is connected to the high-pressure buffer tank through a pipeline, and the ethyl chloride liquid is recovered by the second advection pump in Example 2 through the first advection pump. Ethylenediamine (with an ethylenediamine content of 93.9%) is pumped into the microchannel reactor through two dispersed-phase inlet pipelines (101, 102) respectively.

Regulate ethylenediamine by controlling the feed flow rate: chloroethane molar ratio=3:1, the feed mass ratio of chloroethane and ethylenediamine is 0.34:1, carry out alkylation reaction, reaction temperature is 40 ℃, reaction produces The liquid flows out from the reactor outlet (104) through the pipeline and enters the delay pipeline reactor sequentially, and then passes through the split three-way valve to divide the reaction liquid into a circulating material and an effluent material according to a certain circulation ratio. The circulating material enters the storage tank, and the circulating material entering the storage tank returns to the microreactor through the pipeline through the circulating liquid inlet (103) of the microreactor, mixes with the raw material, and controls the circulation ratio of the returned reaction solution to be 9:1. Until ethyl chloride is all consumed, gas chromatography detection of the effluent material: the purity of N-ethylethylenediamine is 91.7%, and the purity of two kinds of disubstituted by-products are respectively 2.7% and 5.6% (ethylenediamine accounts for about 51.6%).

(2) Separation and purification process of products and raw materials:

① Vacuum distillation process: Same as the process of Example 2, the obtained alkylation reaction liquid is poured into a vacuum distillation device, and the unbound acid amine is distilled out. As determined by gas phase analysis, the content of ethylenediamine in the distillate is 28%, the content of N-ethylethylenediamine is 65.2%, and the contents of two disubstituted by-products are 2.1% and 4.7%, respectively. The 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%.

②Azeotropic distillation process: The distillate obtained above under vacuum distillation is mixed with the entrainer n-heptane, and the mixing volume ratio is 3:1. The components are separated and purified by rectification, ethylenediamine is separated by azeotropic rectification, and N-ethylethylenediamine is separated by conventional rectification. Specifically, n-heptane and ethylenediamine azeotrope first, The boiling point is 86-98°C. According to the immiscibility of n-heptane and ethylenediamine, the lower layer separates ethylenediamine, and the light component n-heptane flows back into the tower. When all ethylenediamine is removed, continue to extract n-heptane by rectification, the temperature is about 98°C. Subsequently, the product N-ethylethylenediamine is extracted at a temperature of 128-130° C. at the top of the rectification tower. Through gas phase detection, the purity of the distilled ethylenediamine is 99.3%, the purity of the product N-ethylethylenediamine is 99.5%, and the calculated single batch product yield is 86.8%.

Example 6

(1) Alkylation reaction process: using the embodiment device, the ethyl chloride storage tank is connected to the high-pressure buffer tank through a pipeline, and the ethyl chloride liquid is recovered by the second advection pump in Example 3 through the first advection pump. Ethylenediamine (the content of ethylenediamine is 93.5%) is pumped into the microchannel reactor through two dispersed-phase inlet pipelines (101, 102) respectively.

Regulate ethylenediamine by controlling the feed flow rate: chloroethane molar ratio=3:1, the feed mass ratio of chloroethane and ethylenediamine is 0.34:1, carry out alkylation reaction, reaction temperature is 40 ℃, reaction produces The liquid flows out from the reactor outlet (104) through the pipeline and enters the delay pipeline reactor sequentially, and then passes through the split three-way valve to divide the reaction liquid into a circulating material and an effluent material according to a certain circulation ratio. The circulating material enters the storage tank, and the circulating material entering the storage tank returns to the microreactor through the pipeline through the circulating liquid inlet (103) of the microreactor, mixes with the raw material, and controls the circulation ratio of the returned reaction solution to be 9:1. Until ethyl chloride is all consumed, the effluent gas chromatography detection: the purity of N-ethylethylenediamine is 91.1%, and the purity of two kinds of disubstituted by-products are respectively 2.9% and 6.0% (ethylenediamine accounts for about 52.9%).

(2) Separation and purification process of products and raw materials:

① Vacuum distillation process: Same as the process of Example 2, pour the obtained alkylation reaction liquid into a vacuum distillation device, distill the unbound acid-bound amine, and collect the distillate. As determined by gas phase analysis, the content of ethylenediamine in the distillate is 28.5%, the content of N-ethylethylenediamine is 65.0%, and the contents of two disubstituted by-products are 2.2% and 4.3% respectively. The 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%.

②Azeotropic distillation process: the distillate after vacuum distillation is mixed with the entrainer n-heptane, and the mixing volume ratio is 3:1. The components are separated and purified by rectification, ethylenediamine is separated by azeotropic rectification, and N-ethylethylenediamine is separated by conventional rectification. Specifically, n-heptane and ethylenediamine azeotrope first, The boiling point is 86-98°C. According to the immiscibility of n-heptane and ethylenediamine, the lower layer separates ethylenediamine, and the light component n-heptane flows back into the tower. When all ethylenediamine is removed, continue to extract n-heptane by rectification, the temperature is about 98°C. Subsequently, the product N-ethylethylenediamine is extracted at a temperature of 128-130° C. at the top of the rectification tower. Through gas phase detection, the purity of the distilled ethylenediamine is 99.4%, the purity of the product N-ethylethylenediamine is 99.5%, and the calculated single batch product yield is 87.0%.

comparative example

First, 360 g of ethylenediamine was added into the reaction kettle, and the raw material liquid was adjusted to 40° C. using a water bath heating device. Use a pressure regulating valve and a mass flow controller to regulate the outflow of ethyl chloride from the ethyl chloride storage tank. And pass the ethyl chloride liquid into the reaction kettle through the feed pump, control a certain feeding speed, ensure the feeding time is 1h, adjust the reaction molar ratio of ethylenediamine: ethyl chloride to 3:1, ethyl chloride A total of 130g was introduced. Then keep stirring at 40°C for 30 minutes to completely react the unconverted ethyl chloride. The conversion rate of ethyl chloride was detected by gas chromatography to be 100%, the purity of N-ethylethylenediamine in the product was 83.6%, and the purity of two disubstituted by-products were 5.5% and 10.9%, respectively. The single batch product yield 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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