Process for synthesizing sodium sarcosinate by using micro-channel continuous flow

Abstract

The invention relates to the technical field of organic synthesis, in particular to a process for synthesizing sodium sarcosinate by using micro-channel continuous flow, which comprises the following specific steps: S1, pretreating raw materials, preparing 30-50wt% of sodium chloroacetate aqueous solution, and filtering; drying the methylamine gas, and storing under a stable pressure; preparing 32wt%-48wt% of a sodium hydroxide aqueous solution; s2, continuous mixing and pre-reaction: pumping the sodium chloroacetate aqueous solution and the methylamine gas into a micro-channel mixer according to a molar ratio of 1: (1.25-1.6), and controlling the temperature to be 20-30 DEG C and the retention time to be 1-3 minutes to obtain a pre-reaction solution; s3, main reaction; s4, neutralizing and removing impurities; s5, concentration and crystallization; and S6, separation and drying: carrying out solid-liquid separation on the crystal suspension, and then carrying out vacuum drying to obtain a sodium sarcosinate finished product. According to the invention, a micro-channel continuous flow process is adopted, continuous operation of the whole process of sodium sarcosinate synthesis is realized, batch feeding and discharging are not needed, and the occupied area of equipment and the investment cost are greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, specifically to a process for synthesizing sodium sarcosinate using microchannel continuous flow. Background Technology

[0002] Sodium sarcosinate, as an important amino acid derivative, possesses excellent surface activity, emulsifying properties, and bactericidal effects. It is widely used in various fields such as daily chemicals, pharmaceuticals, dyes, and food additives, and is a key raw material for the production of creatine monohydrate, N-acylsarcosinate salts, and synthetic lubricants. Currently, the mainstream industrial process for synthesizing sodium sarcosinate is chemical synthesis, with the core reaction being the condensation reaction of sodium chloroacetate with methylamine, or the synthesis of methylaminoacetonitrile from hydroxyacetonitrile and methylamine, followed by alkaline hydrolysis to obtain sodium sarcosinate.

[0003] Existing production processes mostly use traditional batch reactors, which present the following technical problems: 1. The steps of raw material metering, batch feeding, reaction, and discharge are cumbersome, and the reaction time for a single batch can be as long as 2-6 hours, resulting in low production efficiency and large quality fluctuations between batches, which cannot meet the needs of large-scale continuous production. 2. The reaction system has localized excessively high concentrations and uneven temperatures, which leads to an increase in side reactions and makes it difficult to improve product purity. The purity of industrial-grade products is usually only around 98%, and pharmaceutical-grade products require additional purification processes, which significantly increases production costs. 3. Methylamine is a flammable and toxic gas. During intermittent reactions, a large amount of raw materials accumulate, which can easily lead to safety accidents such as leakage and explosive polymerization. Moreover, the COD value of the amine-containing wastewater generated during the reaction process is as high as 8000 mg / L, which puts great pressure on environmental protection treatment. 4. Batch reactors and their associated metering tanks, storage tanks and other equipment are complex, occupy a large area, and have high investment costs.

[0004] Chinese patent CN216273866U discloses a continuous production system for sodium sarcosinate, including a hydroxyacetonitrile storage tank, a methylamine storage tank, and a liquid alkali storage tank; it also includes a mixer, a microreactor, an alkaline hydrolysis reaction tower, a heater, and a finished product storage tank; the inlet of the mixer is connected to both the hydroxyacetonitrile and methylamine storage tanks; the microreactor is connected to the outlet of the mixer; the alkaline hydrolysis reaction tower is connected to both the outlet of the microreactor and the outlet of the liquid alkali storage tank; the heater is connected to the alkaline hydrolysis reaction tower for heating the tower; and the finished product storage tank is connected to the outlet of the alkaline hydrolysis reaction tower. This continuous production system for sodium sarcosinate aims to achieve continuous production and reduce equipment footprint. However, this patent only focuses on equipment structure design and does not systematically optimize core reaction process parameters, resulting in limited improvement in product yield and purity, and it does not solve problems such as material blockage within the microchannels. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems existing in the background art, and therefore provide a process for synthesizing sodium sarcosinate using microchannel continuous flow.

[0006] 1. A process for synthesizing sodium sarcosinate using microchannel continuous flow, characterized by comprising the following steps: S1. Raw material pretreatment Prepare a 30wt%-50wt% sodium chloroacetate aqueous solution and filter it; dry the methylamine gas and store it under stable pressure; prepare a 32wt%-48wt% sodium hydroxide aqueous solution; S2, continuous mixing and pre-reaction The sodium chloroacetate aqueous solution and the methylamine gas were pumped into a microchannel mixer at a molar ratio of 1:1.25-1.6, and the temperature was controlled at 20-30℃ with a residence time of 1-3 min to obtain a pre-reaction solution. S3, the main reaction. The pre-reaction liquid is passed into a microchannel reactor, and the temperature is controlled at 30-60℃, the pressure at 0.4-0.8MPa, and the residence time at 5-15min to obtain a crude sodium sarcosinate reaction solution. S4, neutralization and impurity removal The crude sodium sarcosinate reaction solution and the sodium hydroxide aqueous solution were introduced into the neutralization microchannel at a volume flow rate ratio of 1:0.2-0.5. The neutralization temperature was controlled at 40-50℃, the residence time was 2-5 min, and the pH value was adjusted to 8.5-9.5. The reaction product was filtered to remove impurities, and the filtrate was obtained. S5, Concentration and Crystallization The filtrate was concentrated under reduced pressure to 60wt%-70wt% sodium sarcosinate, and then continuously crystallized to obtain a crystalline suspension. S6. Separation and drying After solid-liquid separation, the crystalline suspension is vacuum dried to obtain sodium sarcosinate.

[0007] As a preferred embodiment of the above technical solution, the sodium chloroacetate aqueous solution in S1 is 40 wt%, and the sodium hydroxide aqueous solution is 35 wt%.

[0008] As a preferred embodiment of the above technical solution, the molar ratio of methylamine gas to sodium chloroacetate aqueous solution in S2 is 1:1.3, the mixer temperature is 25°C, and the residence time is 2 min.

[0009] As a preferred embodiment of the above technical solution, the microchannel reactor in S3 has an inner diameter of 100-500 μm and is made of Hastelloy C-276 alloy.

[0010] As a preferred embodiment of the above technical solution, the microchannel reactor in S3 has a temperature of 45℃, a pressure of 0.6MPa, a residence time of 10min, and an inner diameter of 300μm; a spiral static mixing unit is set inside the channel, with a pitch of 2-3 times the inner diameter of the channel and a quantity of 5-8 units per meter of channel length.

[0011] As a preferred embodiment of the above technical solution, in S4, the flow ratio of the crude sodium sarcosinate reaction solution to the aqueous sodium hydroxide solution is 1:0.3, the neutralization temperature is 45℃, the residence time is preferably 3 minutes, and the filtration uses a ceramic membrane with a pore size of 50-100 nm.

[0012] As a preferred embodiment of the above technical solution, in S5, the vacuum concentration temperature is 60-80℃, the vacuum degree is -0.08~-0.09MPa; the continuous crystallization temperature is 5-15℃, the stirring rate is 50-100r / min, and the seed crystal addition amount is 0.5-1.0%.

[0013] As a preferred embodiment of the above technical solution, in S6, the solid-liquid separation adopts a horizontal screw discharge centrifuge with a rotation speed of 3000-4000 r / min; the vacuum drying temperature is 80-100℃, the vacuum degree is -0.09~-0.1MPa, and the drying time is 2-3h.

[0014] As a preferred embodiment of the above technical solution, the exhaust gas treatment step is also included: the methylamine-containing exhaust gas is absorbed countercurrently with 5-10% dilute sulfuric acid at an absorption temperature of 20-30℃ and a gas-liquid ratio of 100-200:1.

[0015] As a preferred embodiment of the above technical solution, in S3, 0.05-0.2% of a quaternary ammonium salt-type phase transfer catalyst is added to the microchannel reactor. The quaternary ammonium salt-type phase transfer catalyst is tetrabutylammonium bromide or hexadecyltrimethylammonium bromide. It is continuously added dropwise to the inlet of the microchannel reactor by a metering pump, and the ratio of the drop rate to the flow rate of the sodium chloroacetate aqueous solution is 1:800-1200.

[0016] This invention provides a process for synthesizing sodium sarcosinate using a microchannel continuous flow method, which has the following beneficial effects: 1. This invention adopts a microchannel continuous flow process, realizing continuous operation of the entire process of sodium sarcosinate synthesis. There is no need for batch feeding and discharging. The total residence time of the material in the reactor is only 15-30 minutes, which is much shorter than the traditional batch process (2-6 hours). At the same time, the mass transfer area of ​​the microchannel reactor is greatly improved compared with the traditional reactor, the reaction rate is significantly accelerated, the production capacity per unit volume of equipment is greatly increased, and the equipment footprint and investment cost are reduced.

[0017] 2. By precisely controlling parameters such as reaction temperature, pressure, and material ratio, this invention avoids side reactions caused by excessively high local concentrations and uneven temperatures in traditional processes. The product purity can reach over 99.5%, far exceeding the 98% of traditional industrial-grade products. At the same time, continuous production ensures that the batch-to-batch quality fluctuation is ≤±0.3%, which can directly meet the purity requirements of pharmaceutical-grade products without the need for additional purification processes, thus reducing production costs.

[0018] 3. The microchannel reactor used in this invention has an extremely small liquid holding capacity (only 1 / 100-1 / 1000 of that of a traditional reactor), which greatly reduces the online amount of flammable and toxic raw materials such as methylamine, thus fundamentally reducing safety risks such as leakage and explosive polymerization; the tail gas is discharged in compliance with standards after being absorbed by dilute sulfuric acid, and the reaction liquid containing sodium sarcosinate is filtered through a ceramic membrane and continuously crystallized, which greatly reduces the amount of wastewater discharged compared with traditional processes, significantly reducing the pressure on environmental protection.

[0019] 4. In this invention, by optimizing the molar ratio of methylamine to sodium chloroacetate and the reaction parameters, the raw material conversion rate is increased to over 99%, which is 4-7 percentage points higher than that of the traditional process (92-95%). At the same time, the unreacted methylamine can be recycled after being absorbed by the tail gas, further reducing raw material consumption and production costs.

[0020] 5. This invention adopts modular microchannel equipment and automated control system, which can flexibly adjust the equipment combination according to the production capacity demand, and is easy to realize the scale-up production from small-scale trial to industrial scale-up; at the same time, the process is simple to operate, with low labor intensity, and is suitable for large-scale industrial promotion. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. A process for synthesizing sodium sarcosinate using microchannel continuous flow, the specific steps of which are as follows:

[0023] S1. Raw material pretreatment Sodium chloroacetate was dissolved in deionized water to prepare a 40% sodium chloroacetate aqueous solution, which was then filtered through a 0.22 μm filter membrane. Methylamine gas was dried in a dryer and then introduced into a buffer tank, with the pressure in the buffer tank controlled at 0.4 MPa. Sodium hydroxide was dissolved in deionized water to prepare a 35% sodium hydroxide aqueous solution.

[0024] S2, continuous mixing and pre-reaction A 40wt% sodium chloroacetate aqueous solution was pumped into a microchannel mixer at a flow rate of 100 kg / h (molar flow rate of 0.343 kmol / h) and methylamine gas at a flow rate of 13.87 kg / h (molar flow rate of 0.446 kmol / h) using a metering pump. The molar ratio of methylamine to sodium chloroacetate was 1:1.3. The temperature inside the mixer was controlled at 25℃ and the residence time was 2 min to obtain a pre-reaction solution.

[0025] S3, the main reaction. The pre-reaction solution was continuously fed into a microchannel reactor, and the temperature inside the reactor was controlled at 45℃, the pressure at 0.6MPa, and the residence time at 10min to obtain a crude sodium sarcosinate reaction solution.

[0026] S4, neutralization and impurity removal A 35wt% sodium hydroxide aqueous solution was simultaneously introduced into the neutralization microchannel at a flow rate of 30 kg / h (with a volume flow rate ratio of 0.3:1 to the crude sodium sarcosinate reaction solution). The neutralization temperature was controlled at 45℃, the residence time was 3 min, and the pH of the reaction solution was adjusted to 9.0. The neutralized reaction solution was then introduced into a ceramic membrane filter, and the filtration pressure was controlled at 0.15 MPa to remove solid impurities.

[0027] S5, Concentration and Crystallization The filtered reaction solution was passed into a falling film evaporator, and the evaporation temperature was controlled at 70℃ and the vacuum degree at -0.085MPa. The solution was concentrated to a sodium sarcosinate mass concentration of 65%. The concentrated solution was then passed into a continuous crystallizer, and the crystallization temperature was controlled at 10℃ and the stirring rate at 80r / min. 0.8% (relative to the mass of the concentrated solution) of sodium sarcosinate seed crystals (particle size 80μm) was added, and the crystallization time was 3h to obtain a crystalline suspension.

[0028] S6. Separation and drying The crystalline suspension was fed into a centrifuge at a speed of 3500 r / min for 8 min to obtain wet sodium sarcosinate crystals. The wet crystals were then placed in a vacuum drying oven at a temperature of 90℃ and a vacuum of -0.095 MPa for 2.5 h to obtain the finished sodium sarcosinate product.

[0029] S7. Tail gas treatment: The methylamine-containing tail gas generated by the mixer, reactor and evaporator is passed into the dilute sulfuric acid absorption tower and absorbed countercurrently with 8% dilute sulfuric acid. The absorption temperature is controlled at 25℃ and the gas-liquid ratio is 150:1. The tail gas meets the emission standards after absorption.

[0030] Product testing results: Sodium sarcosinate yield 37.3 kg / h, purity 99.7%, moisture content 0.25%, chloride residue 0.05%; raw material conversion rate 99.3%, sodium sarcosinate molar yield 97.7% (calculated as sodium chloroacetate). Example 2

[0031] A process for synthesizing sodium sarcosinate using microchannel continuous flow, the specific steps of which are as follows: S1. Raw material pretreatment Sodium chloroacetate was dissolved in deionized water to prepare a 30% sodium chloroacetate aqueous solution, which was then filtered through a 0.22 μm filter membrane. Methylamine gas was dried in a dryer and then introduced into a buffer tank, with the pressure in the buffer tank controlled at 0.3 MPa. Sodium hydroxide was dissolved in deionized water to prepare a 32% sodium hydroxide aqueous solution.

[0032] S2, continuous mixing and pre-reaction A 30wt% sodium chloroacetate aqueous solution was pumped into a microchannel mixer at a flow rate of 120 kg / h (molar flow rate of 0.309 kmol / h) and methylamine gas at a flow rate of 12.0 kg / h (molar flow rate of 0.386 kmol / h) using a metering pump. The molar ratio of methylamine to sodium chloroacetate was 1:1.25. The temperature inside the mixer was controlled at 20℃ and the residence time was 1 min to obtain a pre-reaction solution.

[0033] S3, the main reaction. The pre-reaction solution was continuously fed into a microchannel reactor, and the temperature inside the reactor was controlled at 30℃, the pressure at 0.4MPa, and the residence time at 5min to obtain a crude sodium sarcosinate reaction solution.

[0034] S4, neutralization and impurity removal A 32wt% sodium hydroxide aqueous solution was simultaneously introduced into the neutralization microchannel at a flow rate of 24 kg / h (with a volume flow rate ratio of 0.2:1 to the crude sodium sarcosinate reaction solution). The neutralization temperature was controlled at 40℃, the residence time was 2 min, and the pH of the reaction solution was adjusted to 8.5. The neutralized reaction solution was then passed through a ceramic membrane filter, and the filtration pressure was controlled at 0.1 MPa to remove solid impurities.

[0035] S5, Concentration and Crystallization The filtered reaction solution was passed into a falling film evaporator, and the evaporation temperature was controlled at 60℃ and the vacuum degree at -0.08MPa. The solution was concentrated to a sodium sarcosinate mass concentration of 60%. The concentrated solution was then passed into a continuous crystallizer, and the crystallization temperature was controlled at 5℃ and the stirring rate at 50r / min. 0.5% (relative to the mass of the concentrated solution) of sodium sarcosinate seed crystals (particle size 50μm) was added, and the crystallization time was 2h to obtain a crystalline suspension.

[0036] S6. Separation and drying The crystalline suspension was fed into a centrifuge at a speed of 3000 r / min for 5 min to obtain wet sodium sarcosinate crystals. The wet crystals were then placed in a vacuum drying oven at a temperature of 80℃ and a vacuum of -0.09 MPa for 2 h to obtain the finished sodium sarcosinate product.

[0037] S7, exhaust gas treatment. The methylamine-containing tail gas is passed into a dilute sulfuric acid absorption tower and absorbed countercurrently with 5% dilute sulfuric acid. The absorption temperature is controlled at 20℃ and the gas-liquid ratio is 100:1. After absorption, the tail gas meets the emission standards.

[0038] Product testing results: Sodium sarcosinate yield 33.3 kg / h, purity 99.5%, moisture content 0.30%, chloride residue 0.07%; raw material conversion rate 99.0%, sodium sarcosinate molar yield 97.2% (calculated as sodium chloroacetate). Example 3

[0039] A process for synthesizing sodium sarcosinate using microchannel continuous flow, the specific steps of which are as follows: S1. Raw material pretreatment Sodium chloroacetate was dissolved in deionized water to prepare a 50% sodium chloroacetate aqueous solution, which was then filtered through a 0.22 μm filter membrane. Methylamine gas was dried in a dryer and then introduced into a buffer tank, with the pressure in the buffer tank controlled at 0.5 MPa. Sodium hydroxide was dissolved in deionized water to prepare a 48% sodium hydroxide aqueous solution.

[0040] S2, continuous mixing and pre-reaction A 50wt% sodium chloroacetate aqueous solution was pumped into a microchannel mixer at a flow rate of 80 kg / h (molar flow rate of 0.343 kmol / h) and methylamine gas at a flow rate of 17.0 kg / h (molar flow rate of 0.547 kmol / h) using a metering pump. The molar ratio of methylamine to sodium chloroacetate was 1:1.6. The temperature inside the mixer was controlled at 30℃ and the residence time was 3 min to obtain a pre-reaction solution.

[0041] S3, the main reaction. The pre-reaction solution was continuously fed into a microchannel reactor, and the temperature inside the reactor was controlled at 60℃, the pressure at 0.8MPa, and the residence time at 15min to obtain a crude sodium sarcosinate reaction solution.

[0042] S4, neutralization and impurity removal A 48wt% sodium hydroxide aqueous solution was simultaneously introduced into the neutralization microchannel at a flow rate of 40 kg / h (with a volume flow rate ratio of 0.5:1 to the crude sodium sarcosinate reaction solution). The neutralization temperature was controlled at 50℃, the residence time at 5 min, and the pH of the reaction solution was adjusted to 9.5. The neutralized reaction solution was then passed through a ceramic membrane filter, and the filtration pressure was controlled at 0.2 MPa to remove solid impurities.

[0043] S5, Concentration and Crystallization The filtered reaction solution was passed into a falling film evaporator, and the evaporation temperature was controlled at 80℃ and the vacuum degree at -0.09MPa. The solution was concentrated to a sodium sarcosinate mass concentration of 70%. The concentrated solution was then passed into a continuous crystallizer, and the crystallization temperature was controlled at 15℃ and the stirring rate at 100r / min. 1.0% (relative to the mass of the concentrated solution) of sodium sarcosinate seed crystals (particle size 100μm) was added, and the crystallization time was 4h to obtain a crystalline suspension.

[0044] S6. Separation and drying The crystalline suspension was fed into a centrifuge at a speed of 4000 r / min for 10 min to obtain wet sodium sarcosinate crystals. The wet crystals were then placed in a vacuum drying oven at a temperature of 100℃ and a vacuum of -0.1 MPa for 3 h to obtain the finished sodium sarcosinate product.

[0045] S7, exhaust gas treatment. The methylamine-containing tail gas is passed into a dilute sulfuric acid absorption tower and absorbed countercurrently with 10% dilute sulfuric acid. The absorption temperature is controlled at 30℃ and the gas-liquid ratio is 200:1. After absorption, the tail gas meets the emission standards.

[0046] Product testing results: Sodium sarcosinate yield 37.4 kg / h, purity 99.8%, moisture content 0.20%, chloride residue 0.03%; raw material conversion rate 99.5%, sodium sarcosinate molar yield 98.2% (calculated as sodium chloroacetate). Example 4

[0047] This Example 4 is based on Example 1, except that in S3, 0.05-0.2% of a quaternary ammonium salt phase transfer catalyst is added to the microchannel reactor. The quaternary ammonium salt phase transfer catalyst is tetrabutylammonium bromide or hexadecyltrimethylammonium bromide. It is continuously added dropwise to the inlet of the microchannel reactor by a metering pump. The dropwise acceleration rate is 1:800-1200 to the flow rate ratio of the sodium chloroacetate aqueous solution to accelerate the condensation reaction.

[0048] Product testing results: Sodium sarcosinate yield 37.7 kg / h, purity 99.9%, moisture content 0.20%, chloride residue 0.02%; raw material conversion rate 99.8%, sodium sarcosinate molar yield 98.7% (calculated as sodium chloroacetate).

[0049] Comparative Examples 1-6 To verify the optimality of the process parameter ranges in Examples 1-3 of the present invention, multiple sets of process parameter comparison experiments were conducted using Comparative Examples 1-6. The specific data are shown in Table 1 below: Table 1. Effects of different process parameters on the yield and purity of sodium sarcosinate

[0050] As shown in Table 1 above, the process parameter range defined by this invention is not obtained through conventional experimental optimization, but rather is an optimal range verified through extensive experiments. When the process parameters exceed the range defined by this invention, the yield of sodium sarcosinate is below 96%, and the purity is below 99%. However, within the parameter range defined by this invention, the yield can be stably maintained above 97%, and the purity can reach above 99.5%, significantly better than parameters outside the range. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for synthesizing sodium sarcosinate using microchannel continuous flow, characterized in that, The specific steps are as follows: S1. Raw material pretreatment Prepare a 30wt%-50wt% sodium chloroacetate aqueous solution and filter it; dry the methylamine gas and store it under stable pressure; prepare a 32wt%-48wt% sodium hydroxide aqueous solution; S2, continuous mixing and pre-reaction The sodium chloroacetate aqueous solution and the methylamine gas were pumped into a microchannel mixer at a molar ratio of 1:1.25-1.6, and the temperature was controlled at 20-30℃ with a residence time of 1-3 min to obtain a pre-reaction solution. S3, the main reaction. The pre-reaction liquid is passed into a microchannel reactor, and the temperature is controlled at 30-60℃, the pressure at 0.4-0.8MPa, and the residence time at 5-15min to obtain a crude sodium sarcosinate reaction solution. S4, neutralization and impurity removal The crude sodium sarcosinate reaction solution and the sodium hydroxide aqueous solution were introduced into the neutralization microchannel at a volume flow rate ratio of 1:0.2-0.

5. The neutralization temperature was controlled at 40-50℃, the residence time was 2-5 min, and the pH value was adjusted to 8.5-9.

5. The reaction product was filtered to remove impurities, and the filtrate was obtained. S5, Concentration and Crystallization The filtrate was concentrated under reduced pressure to 60wt%-70wt% sodium sarcosinate, and then continuously crystallized to obtain a crystalline suspension. S6. Separation and drying After solid-liquid separation, the crystalline suspension is vacuum dried to obtain sodium sarcosinate.

2. The process for synthesizing sodium sarcosinate using microchannel continuous flow according to claim 1, characterized in that: The sodium chloroacetate aqueous solution in S1 is 40 wt%, and the sodium hydroxide aqueous solution is 35 wt%.

3. The process for synthesizing sodium sarcosinate using microchannel continuous flow according to claim 2, characterized in that: In S2, the molar ratio of methylamine gas to sodium chloroacetate aqueous solution is 1:1.3, the mixer temperature is 25°C, and the residence time is 2 min.

4. The process for synthesizing sodium sarcosinate using microchannel continuous flow according to claim 3, characterized in that: The microchannel reactor described in S3 has an inner diameter of 100-500 μm and is made of Hastelloy C-276 alloy.

5. The process for synthesizing sodium sarcosinate using microchannel continuous flow according to claim 4, characterized in that: The microchannel reactor described in S3 has a temperature of 45℃, a pressure of 0.6MPa, a residence time of 10min, and an inner diameter of 300μm. The channel is equipped with a spiral static mixing unit with a pitch of 2-3 times the inner diameter of the channel and a quantity of 5-8 units per meter of channel length.

6. The process for synthesizing sodium sarcosinate using microchannel continuous flow according to claim 5, characterized in that: In step S4, the flow rate ratio of the crude sodium sarcosinate reaction solution to the aqueous sodium hydroxide solution is 1:0.3, the neutralization temperature is 45℃, the residence time is 3min, and the filtration uses a ceramic membrane with a pore size of 50-100nm.

7. The process for synthesizing sodium sarcosinate using microchannel continuous flow according to claim 6, characterized in that: In S5, the vacuum concentration temperature is 60-80℃, the vacuum degree is -0.08~-0.09MPa; the continuous crystallization temperature is 5-15℃, the stirring speed is 50-100r / min, and the seed crystal addition amount is 0.5-1.0%.

8. The process for synthesizing sodium sarcosinate using microchannel continuous flow according to claim 7, characterized in that: In S6, solid-liquid separation is performed using a horizontal screw discharge centrifuge with a rotation speed of 3000-4000 r / min; vacuum drying temperature is 80-100℃, vacuum degree is -0.09~-0.1MPa, and drying time is 2-3h.

9. A process for synthesizing sodium sarcosinate using a microchannel continuous flow according to any one of claims 1-8, characterized in that: In S3, 0.05-0.2% of a quaternary ammonium salt phase transfer catalyst, namely tetrabutylammonium bromide or hexadecyltrimethylammonium bromide, is added to the microchannel reactor. The catalyst is continuously added dropwise to the inlet of the microchannel reactor by a metering pump, and the ratio of the drop rate to the flow rate of the sodium chloroacetate aqueous solution is 1:800-1200.

10. A process for synthesizing sodium sarcosinate using a microchannel continuous flow according to any one of claims 1-8, characterized in that, It also includes exhaust gas treatment steps: methylamine-containing exhaust gas is absorbed countercurrently with 5-10% dilute sulfuric acid at an absorption temperature of 20-30℃ and a gas-liquid ratio of 100-200:1.

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