阅读说明：本技术 一种联产碳酸二甲酯、碳酸甲乙酯和乙二醇的方法 (Method for co-producing dimethyl carbonate, methyl ethyl carbonate and ethylene glycol ) 是由 宋春华 王帮应 于 2021-10-19 设计创作，主要内容包括：本发明涉及化工技术领域,具体涉及一种联产碳酸二甲酯、碳酸甲乙酯和乙二醇的方法。本发明在现有制备碳酸二甲酯的基础上,通过在塔中部设一乙醇进料处,用以加入一定比例的乙醇控制碳酸甲乙酯的选择性生成,生产效率高,副产物少且生成的碳酸二甲酯与碳酸甲乙酯的比例可控,适合工业化生产。(The invention relates to the technical field of chemical industry, in particular to a method for coproducing dimethyl carbonate, methyl ethyl carbonate and ethylene glycol. On the basis of the existing preparation of dimethyl carbonate, the invention controls the selective generation of methyl ethyl carbonate by arranging an ethanol feeding part in the middle of the tower and adding ethanol in a certain proportion, has high production efficiency and few byproducts, and is suitable for industrial production, and the proportion of the generated dimethyl carbonate and the generated methyl ethyl carbonate is controllable.)

1. The method for coproducing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol is characterized by comprising the following preparation processes:

a. putting ethylene carbonate and a catalyst into a static mixer (1), uniformly mixing the ethylene carbonate and the catalyst through the static mixer (1), then feeding the mixture into the upper side of a rectifying section of a reactive rectifying tower (3), preheating ethanol through a preheater (2), then feeding the preheated ethanol into the middle part of the reactive rectifying tower (3), and directly feeding methanol into the lower side of a stripping section of the reactive rectifying tower (3), wherein the molar ratio of the ethanol to the methanol to the ethylene carbonate is 1:2-10: 1-5;

b. the materials are subjected to catalytic reaction in the reaction rectifying tower (3), and components evaporated from the top of the reaction rectifying tower (3) enter a first rectifying tower (4) through a process pipeline; the residual components in the reaction rectifying tower (3) enter a second rectifying tower (5) through a process pipeline;

c. dimethyl carbonate is obtained by side line extraction of a rectifying section of a rectifying tower I (4), methyl ethyl carbonate is obtained by side line extraction of a rectifying section of a rectifying tower II (5), and ethylene glycol is obtained by side line extraction of the middle part of the rectifying tower (5).

2. The method for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol according to claim 1, wherein the amount of the catalyst is 1-5% of the mass of the material.

3. The method for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol according to claim 1 or 2, wherein the catalyst comprises one or more of N-containing quaternary ammonium salt ionic liquid, sodium methoxide-methanol solution, potassium tert-butoxide, potassium carbonate and sodium carbonate.

4. The method for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol according to claim 1, characterized in that the reaction temperature of the reactive distillation column (3) is 85 ± 10 ℃, and the top temperature of the reactive distillation column (3) is 62-64 ℃.

5. The process for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol as claimed in claim 4, characterized in that the operating reflux ratio at the top of the reactive distillation column (3) is 1-3: 1.

6. The method for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol according to claim 1, wherein the operation reflux ratio of the top of the rectifying tower I (4) is 0.1-1.5: 1.

7. The method for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol according to claim 1, wherein the operation reflux ratio of the top of the second (5) rectifying tower is 1-2:1, and the operation pressure is 0-10 KPa.

8. The process for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol according to claim 1, characterized in that inert or inert gas is introduced into the reactive distillation column (3) as protective atmosphere.

9. The process for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol according to claim 8, wherein the protective atmosphere is a nitrogen atmosphere.

10. The method for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol according to claim 1, wherein methanol distilled from the top of the first rectifying tower (4) and the second rectifying tower (5) are both returned to the reactive rectifying tower (3), and the bottom liquid of the second rectifying tower (5) is returned to the static mixer (1).

Technical Field

The invention relates to the technical field of chemical industry, in particular to a method for coproducing dimethyl carbonate, methyl ethyl carbonate and ethylene glycol.

Background

Dimethyl carbonate (DMC) of the formula C₃H₆O₃The derivative is a chemical raw material with low toxicity, excellent environmental protection performance and wide application, is an important organic synthesis intermediate, contains functional groups such as carbonyl, methyl, methoxyl and the like in a molecular structure, has various reaction performances, and has the characteristics of safe and convenient use, less pollution, easy transportation and the like in production. Ethyl methyl carbonate (EMC for short) with molecular formula C₄H₈O₃The lithium ion battery electrolyte is colorless and transparent liquid, is insoluble in water, can be used for organic synthesis, and is an excellent solvent for lithium ion battery electrolyte. Ethylene glycol (EG for short) with the molecular formula of (CH)₂OH)₂The polyester emulsion is colorless and odorless liquid with sweet taste, has low toxicity to animals, can be dissolved with water and acetone, has low solubility in ethers, and can be used as solvent, antifreeze and raw material for synthesizing terylene.

The ester exchange method is characterized in that ethylene carbonate (EC for short) and methanol (MA for short) are subjected to ester exchange reaction to produce ethylene glycol and dimethyl carbonate, the dimethyl carbonate is an important green solvent, and the ethylene glycol is an important fine chemical synthesis raw material. Meanwhile, a certain proportion of ethanol (EA for short) is added into a reaction system, the ethanol can further react with dimethyl carbonate to generate methyl ethyl carbonate, and a plurality of products can be obtained in one-step reaction, so that the method has urgent market demand on the premise of increasing environmental protection situation.

In an invention patent (CN110105174A) of a method for producing ethylene glycol from ethylene carbonate and methanol as raw materials, it is disclosed that dimethyl carbonate and ethylene glycol are produced in a reaction rectification tower from ethylene carbonate and methanol, but if further ethyl methyl carbonate is desired, a new charging reaction is required, which not only prolongs the production period but also wastes production resources, which is not appreciated today with a severe environmental protection form and a high carbon emission requirement, and therefore, there is a need to develop a method capable of co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol.

Disclosure of Invention

In order to solve the technical problems, the invention provides a method for coproducing dimethyl carbonate, methyl ethyl carbonate and ethylene glycol, which is characterized in that ethanol is added into a reaction system to regulate the alcoholysis of ethylene carbonate and methanol to generate dimethyl carbonate and simultaneously obtain methyl ethyl carbonate, a rectifying tower is adopted for reaction, the reaction process is strengthened, and the operation cost and the equipment cost are saved.

The invention provides a method for coproducing dimethyl carbonate, methyl ethyl carbonate and ethylene glycol, which comprises the following preparation processes: a. putting ethylene carbonate and a catalyst into a static mixer (1), uniformly mixing the ethylene carbonate and the catalyst through the static mixer (1), then feeding the mixture into the upper side of a rectifying section of a reactive rectifying tower (3), preheating ethanol through a preheater (2), then feeding the preheated ethanol into the middle part of the reactive rectifying tower (3), and directly feeding methanol into the lower side of a stripping section of the reactive rectifying tower (3), wherein the molar ratio of the ethanol to the methanol to the ethylene carbonate is 1:2-10: 1-5;

b. the materials are subjected to catalytic reaction in the reaction rectifying tower (3), and components evaporated from the top of the reaction rectifying tower (3) enter a first rectifying tower (4) through a process pipeline; the residual components in the reaction rectifying tower (3) enter a second rectifying tower (5) through a process pipeline;

c. dimethyl carbonate is obtained by side line extraction of a rectifying section of a rectifying tower I (4), methyl ethyl carbonate is obtained by side line extraction of a rectifying section of a rectifying tower II (5), and ethylene glycol is obtained by side line extraction of the middle part of the rectifying tower (5).

The present invention involves the following chemical reactions:

C₃H₄O₃+CH₃OH→C₃H₆O₃+(CH₂OH)₂；

C₃H₄O₃+C₂H₅OH→C₅H₁₀O₃+(CH₂OH)₂；

C₃H₆O₃+C₂H₅OH→C₄H₈O₃+CH₃OH。

in certain embodiments of the invention, the catalyst is used in an amount of 1-5% by mass of the feed.

In certain embodiments of the invention, the catalyst comprises one or more of N-containing quaternary ammonium ionic liquid, sodium methoxide-methanol solution, potassium tert-butoxide, potassium carbonate, sodium carbonate.

Preferably, the N-containing quaternary ammonium salt ionic liquid comprises a tetrafluoroborate quaternary ammonium salt ionic liquid.

More preferably, the quaternary ammonium tetrafluoroborate ionic liquid comprises methyltriethylammonium tetrafluoroborate ionic liquid, 3-methylimidazole tetrafluoroborate ionic liquid and 3-methylpyrrolidine tetrafluoroborate ionic liquid.

In certain embodiments of the invention, the reactive distillation column has a reaction temperature of 85 ± 10 ℃ and a top temperature of 62-64 ℃. For the control of the reaction temperature, the uneven heating in the kettle can be avoided by using oil bath heating.

In certain embodiments of the invention, the reactive distillation column overhead operating reflux ratio is from 1 to 3: 1.

In certain embodiments of the invention, the rectification column has an overhead operating reflux ratio of from 0 to 1.5: 1.

In certain embodiments of the invention, the rectification column two top operation reflux ratio is 1-2:1, and the rectification column two operation pressure is 0-10 KPa.

In certain embodiments of the present invention, an inert or inert gas is introduced into the reactive distillation column as a protective atmosphere.

In certain embodiments of the invention, the protective atmosphere is a nitrogen atmosphere.

In some embodiments of the present invention, the methanol distilled from the top of the first rectifying tower and the second rectifying tower is returned to the reactive rectifying tower, and the bottom liquid of the second rectifying tower is returned to the static mixer.

Compared with the prior art, the invention has the following advantages:

the invention provides a method for coproducing dimethyl carbonate, methyl ethyl carbonate and ethylene glycol in the same reaction rectifying tower. Wherein, ethanol is fed at a bubble point, and after being fed, the ethanol and rising gas flow (DMC + methanol) and falling catalyst generate ester exchange reaction to generate methyl ethyl carbonate; the method is a heterogeneous reaction, has sufficient mass transfer process when liquid falls and gas rises, has high production efficiency and few byproducts, generates controllable proportion of dimethyl carbonate and methyl ethyl carbonate, and is suitable for industrial production.

Drawings

FIG. 1 is a schematic diagram of the process flow for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol according to the present invention.

In the figure: 1. a static mixer; 2. a preheater; 3. a reactive distillation column; 4. a first rectifying tower; 5. and a second rectifying tower.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1, referring to the attached figure 1, the method for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol, which is provided by the invention, comprises the following preparation devices and preparation processes:

A. the preparation device comprises: the device comprises a static mixer 1, a preheater 2, a reactive distillation column 3, a first distillation column 4 and a second distillation column 5, wherein the static mixer 1 is connected to the upper side of the distillation section of the reactive distillation column 3, the preheater 2 is connected to the middle part of the reactive distillation column 3, the top of the reactive distillation column 3 is communicated with the first distillation column 4 through a process pipeline, and the bottom of the reactive distillation column 3 is communicated with the second distillation column 5 through a process pipeline;

B. the preparation process comprises the following steps:

a. putting ethylene carbonate and a catalyst into a static mixer 1 in proportion, uniformly mixing the ethylene carbonate and the catalyst through the static mixer 1, then feeding the mixture into the upper side of a rectifying section of a reaction rectifying tower 3, preheating ethanol through a preheater 2, then feeding the preheated ethanol into the middle part of the reaction rectifying tower 3, and directly feeding methanol into the lower side of a stripping section of the reaction rectifying tower 3, wherein the molar ratio of the ethanol to the methanol to the ethylene carbonate is 1:2: 1;

b. the materials are subjected to catalytic reaction in a reaction rectifying tower 3, and dimethyl carbonate and methanol azeotrope evaporated from the top of the reaction rectifying tower 3 enters a rectifying tower I4 through a process pipeline; the ethylene carbonate, the methanol and the catalyst which are left in the tower bottom and the generated ethyl methyl carbonate and the ethylene glycol enter a second rectifying tower 5 through a process pipeline;

c. the dimethyl carbonate product is extracted from the side line of the rectifying section I4 of the rectifying tower, the methyl ethyl carbonate product is extracted from the side line of the rectifying section II 5 of the rectifying tower, the ethylene glycol product is extracted from the middle side line of the rectifying section II 5 of the rectifying tower, methanol evaporated from the tops of the rectifying tower I4 and the rectifying tower II 5 returns to the reactive rectifying tower 3, and the kettle liquid of the rectifying tower II 5 returns to the static mixer 1.

The catalyst is methyl triethyl ammonium tetrafluoroborate ionic liquid, and the dosage of the catalyst is 3% of the mass of the material. The ethanol is preheated to the bubble point temperature of 80 ℃ by the preheater 2 under normal pressure and then enters the middle part of the reactive distillation column 3.

The reaction temperature of the reactive distillation column 3 is 85 ℃, and the temperature of the top of the reactive distillation column 3 is 63 ℃.

The tower top operation reflux ratio of the reaction rectifying tower 3 is 2:1, the tower top operation reflux ratio of the rectifying tower I4 is 1.5:1, and the tower top operation reflux ratio of the rectifying tower II 5 is 2: 1.

And the second rectifying tower 5 has the operation pressure of 8 KPa.

And introducing nitrogen into the reaction rectifying tower 3 as protective atmosphere.

Examples 2 to 3

The manufacturing apparatus in examples 2 to 3 was the same as in example 1 except that:

in the preparation process, the ethanol, the methanol and the ethylene carbonate enter the static mixer 1 according to the molar ratio shown in the table 1 to be uniformly mixed, the rest is the same as the example 1, and the obtained test results are filled in the table 1.

Comparative examples 1 to 2

The manufacturing apparatus in comparative examples 1-2 was the same as in example 1 except that:

in the preparation process, the ethanol, the methanol and the ethylene carbonate enter the static mixer 1 according to the molar ratio shown in the table 1 to be uniformly mixed, the rest is the same as the example 1, and the obtained test results are filled in the table 1.

TABLE 1

As can be seen from the data in Table 1, the conversion rate of ethylene carbonate in a certain range is increased along with the increase of the total mole number of methanol and ethanol, the ethylene carbonate is completely converted, and the selectivity of the ethylene carbonate to ethyl methyl carbonate is related to the proportion of ethanol in the mixed system.

Examples 4 to 5

The manufacturing apparatus in examples 4 to 5 was the same as in example 1 except that:

in the preparation process, the catalysts with the mass percentage shown in the table 2 are added, the rest are the same as the example 1, and the obtained test results are filled in the table 2.

Comparative examples 3 to 4

The manufacturing apparatus in comparative examples 3 to 4 was the same as in example 1 except that:

in the preparation process, the catalysts with the mass percentage shown in the table 2 are added, the rest are the same as the example 1, and the obtained test results are filled in the table 2.

TABLE 2

As can be seen from the data in Table 2, the concentration of the catalyst exceeding a certain range does not greatly affect the conversion of ethylene carbonate, but the concentration is too low to allow the reaction to proceed.

Examples 6 to 7

The manufacturing apparatus in examples 6 to 7 was the same as in example 1 except that:

in the preparation process, the reaction temperature of the reactive distillation column 3 is the temperature shown in table 3, the rest is the same as that of example 1, and the obtained test results are filled in table 3.

Comparative examples 5 to 6

The manufacturing apparatus in comparative examples 5 to 6 was the same as in example 1 except that:

in the preparation process, the reaction temperature of the reactive distillation column 3 is the temperature shown in table 3, the rest is the same as that of example 1, and the obtained test results are filled in table 3.

TABLE 3

As can be seen from the data in Table 3, the higher the reaction temperature of the reactive distillation column 3, the faster the methanol rise, which affects the conversion of ethylene carbonate, while the lower the temperature, the higher the selectivity of ethyl methyl carbonate.

Examples 8 to 9

The manufacturing apparatus in examples 8 to 9 was the same as in example 1 except that:

in the preparation process, the operation reflux ratio at the top of the reactive distillation column 3 is shown in table 4, the rest is the same as that of example 1, and the obtained test results are filled in table 4.

TABLE 4

As can be seen from the data in Table 4, the reflux ratio does not substantially affect the conversion rate of ethylene carbonate, the higher the reflux ratio is, the higher the selectivity of ethyl methyl carbonate is, mainly the reflux amount is increased, the contact time of the refluxed dimethyl carbonate and the ascending ethanol steam is increased, and the generation of ethyl methyl carbonate is more favorable.

It can be seen from table 1-table 4 that in the method for co-producing dimethyl carbonate, ethyl methyl carbonate and ethylene glycol, ethylene carbonate and methanol, dimethyl carbonate and ethanol are subjected to transesterification reaction under the action of catalyst, when n (ea) n (ma) n (ec) 1:2-10:1-5, the conversion rate of ethylene carbonate is increased along with the increase of the mole number of methanol and ethanol, and the selectivity for producing ethyl methyl carbonate is related to the proportion of ethanol in the system, the reaction temperature of the method is 85 ± 10 ℃, in this temperature range, the content of methanol in the gas phase composition is far greater than that of ethanol, therefore, methanol and ethylene carbonate preferentially react to produce dimethyl carbonate under the action of catalyst, and the content of dimethyl carbonate is increased along with the decrease of the content of methanol in the gas phase, forming an azeotropic composition, and then contacting with ethanol for reaction. Meanwhile, for the material ethanol, the feeding position (for example, the ethanol in the present application enters the middle part of the reactive distillation column 3 after being preheated by the preheater 2), the feeding temperature (for example, the ethanol in the present application is bubble point feeding) and the feeding amount (for example, n (ea) n (ma) n (ec) 1:2-10:1-5) need to be controlled, so that the ethanol can preferentially react with the dimethyl carbonate to mainly generate methyl ethyl carbonate.

The present invention has been further described with reference to specific embodiments, but it should be understood that the detailed description should not be construed as limiting the spirit and scope of the present invention, and various modifications made to the above-described embodiments by those of ordinary skill in the art after reading this specification are within the scope of the present invention.