Method for preparing N-methyldiethanolamine by micro-reaction synthesis

文档序号：1623582 发布日期：2020-01-14 浏览：18次中文

阅读说明：本技术 一种微反应合成制备n-甲基二乙醇胺的方法 (Method for preparing N-methyldiethanolamine by micro-reaction synthesis ) 是由杨绪甲毛松柏朱道平周志斌余勇宋丽陈园园于 2018-07-06 设计创作，主要内容包括：本发明公开了一种微反应合成制备N-甲基二乙醇胺的方法。主要包括：1)将甲胺、去离子水预混合,甲胺含量质量比25～35%,预混合后送入微反应合成器与环氧乙烷进行反应,压力1.0～2.5Mpa,温度40～65℃,得到含有N-甲基二乙醇胺的混合物,反应停留时间1～10分钟。2)反应后获得的混合物送入闪蒸罐进行脱胺处理,3)将闪蒸罐底部出来的混合液送入精馏塔内进行蒸馏获得含量在98.5%以上的N-甲基二乙醇胺产品。本发明在一种连续流微反应器中合成N-甲基二乙醇胺,通过强化原料混合和合成反应条件,加快反应速度,简化了工艺操作,提高了产品收率。(The invention discloses a method for preparing N-methyldiethanolamine by micro-reaction synthesis. The method mainly comprises the following steps: 1) premixing methylamine and deionized water, wherein the mass ratio of the content of methylamine is 25-35%, feeding the premixed methylamine into a micro-reaction synthesizer to react with ethylene oxide at the pressure of 1.0-2.5 Mpa and the temperature of 40-65 ℃ to obtain a mixture containing N-methyldiethanolamine, and the reaction residence time is 1-10 minutes. 2) Feeding the mixture obtained after the reaction into a flash tank for deamination, and 3) feeding the mixed solution discharged from the bottom of the flash tank into a rectifying tower for distillation to obtain an N-methyldiethanolamine product with the content of more than 98.5%. The method synthesizes the N-methyldiethanolamine in a continuous flow microreactor, accelerates the reaction speed, simplifies the process operation and improves the product yield by strengthening the reaction conditions of raw material mixing and synthesis.)

1. A method for preparing N-methyldiethanolamine by micro-reaction synthesis is characterized by comprising a raw material premixing unit, a micro-reactor synthesis unit, a flash evaporation deamination and rectification purification unit.

2. The method according to claim 1, characterized by comprising the steps of:

1) premixing raw materials: firstly, premixing raw materials of methylamine and deionized water to be used as a circulating solution required by a synthetic reaction;

2) synthesizing a micro-reactor: feeding the premixed circulating solution into a micro-reaction synthesizer, reacting with ethylene oxide fed into the micro-reaction synthesizer, controlling the reaction temperature through the feeding rate, and obtaining a mixture containing N-methyldiethanolamine after reaction;

3) flash evaporation and amine removal: sending the mixture containing the N-methyldiethanolamine obtained by the micro-reactor synthesis unit into a flash tank from a product collection tank for preliminary separation, and controlling the bottom temperature of the flash tank; methylamine steam coming out of the top of the flash tank is condensed and then sent into a raw material premixing unit for recycling;

4) rectification and purification: sending the N-methyldiethanolamine-containing concentrated solution from the bottom of the flash tank into a rectifying tower for rectification under reduced pressure and separation to obtain the N-methyldiethanolamine with the purity of over 98.5 percent.

3. The method according to claim 2, wherein the mixed solution for circulating the reaction solution has a methylamine content in the range of 25 to 35%.

4. The method of claim 2, wherein the microreactor has a synthesis pressure of 1.0 to 2.5MPa, a molar ratio of ethylene oxide to methylamine of 1.5 ~ 2.5.5, a reaction temperature of 40 to 65 ℃, and a residence time of 1 to 10 minutes.

5. The method of claim 2, wherein the micro-reaction synthesizer is modularly loaded in a tubular continuous reactor comprising, in order, a first micro-structure mixer, a first micro-structure reactor, a second micro-structure mixer, a second micro-structure reactor, and a product collection tank.

6. The method of claim 2 or 5, wherein the methylamine mixed circulating solution is connected to the feed inlet of the first micro-mixer and ethylene oxide is connected to the feed inlets of the first and second micro-mixers, respectively.

7. The method according to claim 2, wherein the pressure of the flash tank is controlled within the range of 0.8 to 1.5MPa, and the temperature of the bottom of the flash tank is controlled within the range of 100 to 120 ℃.

8. The method as claimed in claim 2, wherein the pressure of the rectifying tower is in the range of-0.10 to 0.2MPa, the bottom temperature of the rectifying tower is in the range of 168 to 185 ℃, and the top temperature of the rectifying tower is controlled in the range of 163 to 168 ℃.

9. The process of claim 1, 2 or 7, wherein the flash drum has heating means at the bottom of the flash drum, and the flash drum is combined with the stripping.

Technical Field

The invention relates to the technical field of chemical synthesis, in particular to a method for preparing N-methyldiethanolamine by a micro-reaction synthesis technology.

Background

The natural gas and the raw gas (such as catalytic dry gas, coking dry gas, cracking gas, liquefied gas, etc.) of petroleum processing industry all contain a certain amount of H₂S and organic sulfur (e.g. CS)₂COS, RSH, R-S-R', etc.), must be cleaned prior to transport and processing.

N-methyldiethanolamine is a solvent widely used in desulfurization and decarburization processes and can be used for treating different H₂The acidic gas with S concentration can simultaneously remove sulfide and CO₂Also, H can be removed with high selectivity₂S, organic sulfur, and the like. Has the advantages of low energy consumption, low circulation quantity, low operation cost and the like.

The technical route for producing the N-methyldiethanolamine comprises four technical routes: (1) catalytic hydrogenation of formaldehyde and cyanoethanol; (2) reacting formaldehyde with diethanol amine; (3) catalytic hydrogenation of formaldehyde and diethanolamine; (4) methylamine is reacted with ethylene oxide.

Among the four synthesis methods, the methylamine and ethylene oxide reaction method is most commonly used, and can be divided into kettle batch synthesis and tubular continuous synthesis according to the reaction process, the reaction pressure and temperature are usually higher, as described in patent CN101265195A, the reaction pressure is 5-7 MPa, and the temperature is controlled at 133-137 ℃.

Disclosure of Invention

The invention provides a method for preparing N-methyldiethanolamine by a micro-reaction synthesis technology.

The reaction principle of the N-methyldiethanolamine is as follows:

。

the main technical scheme of the method of the invention is as follows: the method for preparing the N-methyldiethanolamine by the micro-reaction synthesis is characterized by comprising a raw material premixing unit, a micro-reactor synthesis unit, a flash evaporation deamination and rectification purification unit.

Generally, the method comprises the steps of:

1) premixing raw materials: firstly, premixing raw materials of methylamine and deionized water to be used as a circulating solution required by a synthetic reaction;

Preferably, the content of methylamine in the mixed solution of the circulating reaction solution is within the range of 25-35%.

The synthesis pressure of the microreactor is within the range of 1.0-2.5 Mpa, the molar ratio of ethylene oxide to methylamine is within the range of 1.5 ~ 2.5.5, the reaction temperature is within the range of 40-65 ℃, and the retention time is 1-10 minutes.

The micro-reaction synthesizer is filled in a tubular continuous reactor in a modularized mode and sequentially comprises a first micro-structure mixer, a first micro-structure reactor, a second micro-structure mixer, a second micro-structure reactor and a product collecting tank.

The methylamine mixed circulating solution is connected with the feed inlet of the first microstructure mixer, and the ethylene oxide is respectively connected with the feed inlets of the first microstructure mixer and the second microstructure mixer.

The pressure of the flash tank is controlled within the range of 0.8-1.5 Mpa, and the bottom temperature of the flash tank is controlled within the range of 100-120 ℃.

The pressure of the rectifying tower is in the range of-0.10-0.2 Mpa, the kettle bottom temperature of the rectifying tower is in the range of 168-185 ℃, and the tower top temperature of the rectifying tower is controlled in the range of 163-168 ℃.

The invention discloses a typical method for preparing N-methyldiethanolamine by micro-reaction synthesis, which comprises the following steps:

1) premixing raw materials: firstly, premixing raw materials of methylamine and deionized water, wherein the content of methylamine is 25-35% by mass, and the raw materials are used as a circulating solution for reaction;

2) sending the premixed circulating solution into a microreactor synthesis unit, adjusting the pressure to be within the range of 1.0-2.5 Mpa, introducing ethylene oxide to react, wherein the molar ratio of ethylene oxide to methylamine is within the range of 1.5 ~ 2.5.5, controlling the reaction temperature within the range of 40-65 ℃ through the feeding rate, and keeping the reaction time for 1-10 minutes to obtain a mixture containing N-methyldiethanolamine after the reaction, wherein the microreactor is filled in a tubular continuous reactor in a modularized manner and sequentially comprises a first microstructure mixer, a first microstructure reactor, a second microstructure mixer, a second microstructure reactor and a product collecting tank, the methylamine mixed circulating solution is connected with a feed inlet of the first microstructure mixer, and the ethylene oxide is respectively connected with feed inlets of the first and second microstructure mixers;

3) flash evaporation and amine removal: sending a mixture containing N-methyldiethanolamine obtained by the synthesis of the microreactor into a flash tank from a product collecting tank for preliminary separation, wherein the pressure of the flash tank is controlled within the range of 0.8-1.5 Mpa, and the temperature of the bottom of the flash tank is controlled within the range of 100-120 ℃; methylamine steam coming out of the top of the flash tank is condensed and then sent into a raw material premixing unit for recycling;

4) rectification and purification: sending the N-methyldiethanolamine-containing concentrated solution from the bottom of the flash tank into a rectifying tower for vacuum rectification separation to obtain the N-methyldiethanolamine with the purity of more than 98.5%, wherein the pressure of the rectifying tower is controlled within-0.10-0.2 Mpa, the temperature of the bottom of the rectifying tower is controlled within 168-185 ℃, and the temperature of the top of the rectifying tower is controlled within 163-168 ℃.

In the process, the pressure is controlled to be 1.0-2.5 MPa, the reaction temperature is controlled to be 40-65 ℃ by reasonably controlling the feeding of the ethylene oxide, and meanwhile, a heating device is arranged at the bottom of a flash evaporation tank, and flash evaporation and gas stripping are combined.

The method synthesizes the N-methyldiethanolamine in the continuous flow microreactor, accelerates the reaction speed, simplifies the process operation and improves the product yield by strengthening the reaction conditions of raw material mixing and synthesis.

Drawings

FIG. 1 is a schematic block flow diagram of a preparation method according to an embodiment of the present invention.

Detailed Description

The following examples were prepared as shown in FIG. 1.

Firstly, mixing methylamine and deionized water, wherein the content of methylamine in the mixed solution is 25-35%; feeding the mixed circulating solution into a reactor, adjusting the reaction pressure to 1.0-2.5 MPa through nitrogen, introducing ethylene oxide to react, wherein the ratio of ethylene oxide to methylamine is 1.5-2.5, and controlling the reaction temperature to 40-65 ℃ through reasonable flow control to obtain a mixture containing N-methyldiethanolamine; and (2) conveying the mixture containing the N-methyldiethanolamine into a flash tank with a heating device, controlling the pressure within 0.8-1.5 MPa, heating and controlling the temperature within 100-120 ℃, separating out methylamine in the mixed product by flash evaporation, and conveying the separated methylamine into a raw material preparation process for reuse through condensation and recovery. The flash tank contains a concentrate of a mixture of N-methyldiethanolamine at the bottom. And (3) sending the concentrated solution containing the mixture of the N-methyldiethanolamine obtained from the bottom of the flash evaporation tank into a rectifying tower for carrying out rectification under reduced pressure and separation to obtain the N-methyldiethanolamine, wherein the purity can reach more than 98.5%.

Example 1

The technological parameters are as follows: synthesis reaction, pressure: 1.0 MPa; temperature: -65 ℃;

b. flash evaporation deamination, pressure: 1.0 MPa; temperature: -120 ℃ of temperature;

c. rectification and purification, pressure: -0.1 MPa; the temperature of the kettle bottom: the temperature of the tower top is 185 ℃ below zero and 163 ℃ below zero.