CN110407725B - Preparation method of 2-mercaptoethanol - Google Patents
Preparation method of 2-mercaptoethanol Download PDFInfo
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- CN110407725B CN110407725B CN201910762041.7A CN201910762041A CN110407725B CN 110407725 B CN110407725 B CN 110407725B CN 201910762041 A CN201910762041 A CN 201910762041A CN 110407725 B CN110407725 B CN 110407725B
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- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C319/00—Preparation of thiols, sulfides, hydropolysulfides or polysulfides
- C07C319/02—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of thiols
Abstract
The invention belongs to the field of chemical industry, and particularly relates to a preparation method of 2-mercaptoethanol. The method adopts a microchannel reaction technology, the amount of byproducts in the reaction process is less than 0.3 percent, the content of materials in a tower kettle meets the requirement of the current market of more than or equal to 99.5 percent after the solvent and the catalyst are removed by rectification, the yield of mercaptoethanol (counted by ethylene oxide) is improved to more than 99 percent while the byproducts are reduced, the frequency of primary rectification is reduced, and the energy consumption and the cost of separation are further reduced.
Description
Technical Field
The invention belongs to the field of chemical industry, and particularly relates to a preparation method of 2-mercaptoethanol.
Background
At present, 2-mercaptoethanol is produced at home and abroad by adopting an ethylene oxide method, and the process generally comprises the steps of directly synthesizing 2-mercaptoethanol by using hydrogen sulfide and ethylene oxide in a solvent, a catalyst and a certain pressure and temperature; the production process is divided into two types, namely a normal pressure method and a pressurization method according to the reaction pressure, wherein the high pressure method is mostly used abroad, the reaction pressure is 1.0-3.5MPa, and the reaction time is 5-60 min; the domestic use is a normal pressure method, the reaction pressure is 0.1-0.5MPa, the normal pressure method has low requirements on equipment, but a large number of byproducts exist, so that the conversion rate and the yield are relatively low compared with a high-pressure method.
The prior art is as follows: at present, the synthesis method of 2-mercaptoethanol in China has been reported, for example, in the 04 th period of 2018 in Sichuan chemical industry [ the research on synthesis process for producing 2-mercaptoethanol by using desulfurization waste gas ] a liquid-phase low-pressure synthesis process is mentioned, a liquid organic alkaline compound is used as a catalyst, raw material hydrogen sulfide is absorbed by absorption liquid and then reacts with ethylene oxide in a liquid state, and the ethylene oxide is fed in a gaseous state or a liquid state. And distilling the reaction product to separate out solvent and catalyst, and returning the solvent and catalyst to the previous section for recycling. And (3) carrying out vacuum rectification on the crude product to obtain a qualified 2-mercaptoethanol product. Although the residual liquid can be further recycled to obtain the thiodiglycol product, the market of the thiodiglycol is small, and the chroma of the recycled thiodiglycol is higher, so that the value of the thiodiglycol product is greatly reduced.
The low-pressure liquid phase method has high byproduct amount, and in order to ensure that the content of the 2-mercaptoethanol is higher than 99.5%, after the solvent catalyst is removed, the 2-mercaptoethanol is subjected to secondary rectification to extract the 2-mercaptoethanol at the tower top, so that the yield of the 2-mercaptoethanol is reduced to 95% -96% again in the process, and the energy consumption is increased by the secondary rectification.
Disclosure of Invention
In order to overcome the technical defects, the invention adopts a microchannel reaction technology, the amount of byproducts in the reaction process is lower than 0.3 percent, after the solvent and the catalyst are removed by rectification, the content of the materials in a tower kettle meets the requirement of more than or equal to 99.5 percent of the current market, the yield of mercaptoethanol (calculated by ethylene oxide) is improved to more than 99 percent while the byproducts are reduced, the frequency of primary rectification is reduced, and the energy consumption and the cost of separation are further reduced.
Specifically, the technical scheme adopted by the invention is that the preparation method of the 2-mercaptoethanol comprises the following steps:
step 1: adding a certain amount of solvent and catalyst into the autoclave, adjusting the temperature to the required temperature, introducing hydrogen sulfide gas, and continuing introducing hydrogen sulfide to increase the pressure to a certain value when the temperature of the autoclave begins to decrease;
step 2: pumping the mixed solution obtained in the step (1) into a microchannel reactor at a certain flow rate, controlling the flow rate of ethylene oxide entering the microchannel reactor according to a proportion, controlling the reaction temperature and pressure, and reacting to obtain a crude product (starting to collect the crude product after the reaction temperature is stable);
and step 3: and adding the crude product into a rectifying tower, and carrying out reduced pressure rectification to remove hydrogen sulfide, a solvent and a catalyst to obtain a product, namely the 2-mercaptoethanol.
In the step 1, the solvent is one or more of methanol, tetrahydrofuran, chloroform and water;
in the step 1, the preferable mass ratio of the solvent to the catalyst is 1-6: 1, preferably 1-4: 1, more preferably 1.5 to 2.5: 1;
the catalyst in the step 1 is triethylamine;
the temperature in the step 1 is 0-15 ℃, preferably 6-10 ℃;
in the step 1, the pressure is 0.3-1.2 Mpa, preferably 0.5-1.0 Mpa;
the mass ratio of the hydrogen sulfide absorption liquid to the ethylene oxide in the step 2 is 8-15:1, preferably 10-13: 1;
in the step 2, the preferable residence time in the microchannel reactor is 60-120 s, and the preferable residence time is 90-110 s.
In the step 2, the reaction temperature is preferably 30-70 ℃, and preferably 40-60 ℃.
The reaction pressure in the step 2 is 0.5-1.2Mpa, preferably 0.5-1.0 Mpa.
The invention is characterized in that: the catalyst is synthesized by using a microchannel reactor (the reactor is prior art and is generally available on the market, such as a corning G1 glass reactor), which is beneficial to increasing the contact probability and the mass and heat transfer performance of reactants and the catalyst and improving the reaction efficiency; the reaction temperature is 30-70 ℃, preferably 40-60 ℃, the reaction rate is increased, and the reaction time is reduced; tetrahydrofuran and methanol are used as a solvent for absorbing hydrogen sulfide (methanol is generally used as a solvent in the prior art), the mass ratio of hydrogen sulfide absorption liquid to ethylene oxide is 8-15:1, the reaction pressure is 0.5-1.2Mpa, the selectivity of mercaptoethanol is improved, the operation difficulty is reduced, the cost is reduced, the selectivity of mercaptoethanol is improved to more than 99.5% from 97-98% of that of a tubular reactor, the content of thiodiglycol is less than or equal to 0.3%, the product can meet the quality requirement without being separated from byproducts, and the separation energy consumption is reduced. In conclusion, the microchannel reaction technology is adopted, the whole reaction is improved, the content of the byproduct thiodiglycol in the reaction process is lower than 0.3%, after the solvent and the catalyst are removed by rectification, the material content in the tower kettle meets the requirement that the current market is more than or equal to 99.5%, the side reaction is reduced, the primary rectification frequency is reduced, and the separation energy consumption and the separation cost are further reduced.
Detailed Description
The present invention will be described in further detail with reference to the following examples, but it should not be construed that the scope of the above subject matter is limited to the following examples. All the technologies realized based on the above contents of the present invention belong to the scope of the present invention, and the following embodiments are all completed by adopting the conventional prior art except for the specific description.
Example 1
Preparing 500g of methanol and triethylamine in a high-pressure kettle according to a ratio of 2:1, reducing the temperature to 10 ℃, introducing hydrogen sulfide until the pressure is stabilized to 0.3mpa, starting a temperature control module, and mixing hydrogen sulfide absorption liquid and ethylene oxide according to a ratio of 10: 1, controlling the reaction temperature at 40 ℃, the reaction pressure at 0.7mpa and the reaction residence time at 60s, and removing hydrogen sulfide, methanol and triethylamine under reduced pressure, wherein the mercaptoethanol content in the kettle liquid is 99.52 percent, the thiodiglycol content is 0.38 percent, and the mercaptoethanol yield is 99.02 percent based on ethylene oxide.
Example 2
Preparing 500g of methanol, water and triethylamine in a high-pressure kettle according to the mass ratio of 3:0.5:1, reducing the temperature to 5 ℃, introducing hydrogen sulfide until the pressure is stabilized to 0.5mpa, starting a temperature control module, and mixing the hydrogen sulfide absorption liquid and ethylene oxide according to the mass ratio of 13: 1, controlling the reaction temperature to be 50 ℃, the reaction pressure to be 0.5mpa, the reaction residence time to be 90s, and removing hydrogen sulfide, methanol, water and triethylamine under reduced pressure, wherein the mercaptoethanol content in the kettle liquid is 99.68 percent, the thiodiglycol content is 0.21 percent, and the mercaptoethanol yield is 99.21 percent based on ethylene oxide.
Example 3
Preparing 500g of methanol, chloroform and triethylamine according to the mass ratio of 3:0.5:1 in a high-pressure kettle, cooling to 5 ℃, introducing hydrogen sulfide until the pressure is stabilized to 0.7mpa, starting a temperature control module, and mixing hydrogen sulfide absorption liquid and ethylene oxide according to the mass ratio of 15:1, controlling the reaction temperature to be 60 ℃, the reaction pressure to be 0.6mpa and the reaction retention time to be 75s, and removing hydrogen sulfide, methanol, chloroform and triethylamine under reduced pressure, wherein the mercaptoethanol content in the kettle liquid is 99.5 percent, the thiodiglycol content is 0.43 percent, and the mercaptoethanol yield is 97.3 percent based on ethylene oxide.
Example 4
Preparing 500g of tetrahydrofuran and triethylamine in a high-pressure kettle according to a mass ratio of 4:1, reducing the temperature to 10 ℃, introducing hydrogen sulfide until the pressure is stabilized to 0.6mpa, starting a temperature control module, and mixing hydrogen sulfide absorption liquid and ethylene oxide according to a ratio of 10: 1, controlling the reaction temperature to be 55 ℃, the reaction pressure to be 0.7mpa and the reaction retention time to be 75s, and removing the hydrogen sulfide, the tetrahydrofuran and the triethylamine under reduced pressure, wherein the yield of mercaptoethanol in the kettle liquid is 99.69%, the content of thiodiglycol is 0.11%, and the yield of mercaptoethanol in terms of ethylene oxide is 99.34%.
Example 5
Tetrahydrofuran, water and triethylamine are added into an autoclave according to the weight ratio of 4: 0.2: 1, cooling to 5 ℃, introducing hydrogen sulfide until the pressure is stabilized to 0.5mpa, starting a temperature control module, and mixing the hydrogen sulfide absorption liquid and ethylene oxide according to the mass ratio of 13: 1, controlling the reaction temperature to be 35 ℃, the reaction pressure to be 0.7mpa, the reaction residence time to be 90s, and removing hydrogen sulfide, tetrahydrofuran, water and triethylamine under reduced pressure, wherein the mercaptoethanol content in the kettle liquid is 99.88 percent, the thiodiglycol content is 0.07 percent, and the mercaptoethanol yield is 99.42 percent based on ethylene oxide.
Comparative example 1
Preparing 500g of methanol and triethylamine in a high-pressure kettle according to the mass ratio of 2:1, reducing the temperature to 5 ℃, introducing hydrogen sulfide until the pressure is stabilized to 0.6mpa, starting a temperature control module, and mixing hydrogen sulfide absorption liquid and ethylene oxide according to the weight ratio of 15:1, controlling the reaction temperature to be 40 ℃, the reaction pressure to be 0.5mpa and the reaction retention time to be 160s, and removing hydrogen sulfide, methanol and triethylamine under reduced pressure, wherein the mercaptoethanol content in the kettle liquid is 97.02 percent, the thiodiglycol content is 2.94 percent, and the mercaptoethanol yield is 95.11 percent based on ethylene oxide.
Comparative example 2
Preparing 500g of methanol and triethylamine in a high-pressure kettle according to a mass ratio of 4:1, reducing the temperature to 5 ℃, introducing hydrogen sulfide until the pressure is stabilized to 0.6mpa, starting a temperature control module, and mixing hydrogen sulfide absorption liquid and ethylene oxide according to a ratio of 10: 1, controlling the reaction temperature to be 50 ℃, the reaction pressure to be 1.0mpa and the reaction residence time to be 160s, and removing the hydrogen sulfide, the methanol and the triethylamine under reduced pressure, wherein the mercaptoethanol content in the kettle liquid is 97.43 percent, the thiodiglycol content is 2.38 percent, and the mercaptoethanol yield is 95.8 percent based on the ethylene oxide.
Claims (7)
1. The preparation method of the 2-mercaptoethanol is characterized by comprising the following specific steps:
step 1: adding a solvent and a catalyst into the high-pressure kettle, adjusting the temperature to the required temperature, introducing hydrogen sulfide gas, and continuing introducing the hydrogen sulfide gas to the high-pressure kettle to increase the pressure to a certain value when the temperature of the high-pressure kettle begins to decrease;
step 2: pumping the mixed solution obtained in the step (1) into a microchannel reactor, feeding ethylene oxide into the microchannel reactor, controlling the reaction temperature and pressure, and reacting to obtain a crude product;
and step 3: carrying out reduced pressure rectification on the crude product, and removing hydrogen sulfide, a solvent and a catalyst to obtain a kettle liquid, namely a 2-mercaptoethanol product;
the mass ratio of the hydrogen sulfide absorption liquid to the ethylene oxide in the step 2 is 8-15: 1;
in the step 2, the residence time in the microchannel reactor is 60-120 s; the reaction temperature is 30-70 ℃;
in the step 2, the reaction pressure is 0.5-1.2 MPa.
2. The method for preparing 2-mercaptoethanol according to claim 1, wherein the solvent in step 1 is one or more of methanol, tetrahydrofuran, chloroform, and water.
3. The preparation method of 2-mercaptoethanol according to claim 1, wherein the mass ratio of the solvent to the catalyst in step 1 is 1-6: 1; the catalyst in the step 1 is triethylamine.
4. The preparation method of 2-mercaptoethanol according to claim 3, wherein the mass ratio of the solvent to the catalyst in step 1 is 1-4: 1.
5. the method of claim 1, wherein the temperature in step 1 is 0-15 ℃; in the step 1, the pressure is 0.3-1.2 MPa.
6. The method for preparing 2-mercaptoethanol according to claim 1, wherein the mass ratio of the solvent to the catalyst in step 1 is 1.5-2.5: 1; the temperature is 6-10 ℃; the pressure is 0.5-1.0 MPa.
7. The preparation method of 2-mercaptoethanol according to claim 1, wherein the mass ratio of the hydrogen sulfide absorption liquid to the ethylene oxide in the step 2 is 10-13: 1; the residence time in the microchannel reactor is 90-110 s; the reaction temperature is 40-60 ℃; the reaction pressure is 0.5-1.0 MPa.
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Address after: 256500 Boxing Economic Development Zone, Shandong, Binzhou Patentee after: Yifeng New Material Co.,Ltd. Address before: 256500 Boxing Economic Development Zone, Shandong, Binzhou Patentee before: SHANDONG EFIRM BIOCHEMISTRY AND ENVIRONMENTAL PROTECTION Co.,Ltd. |
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