CN113493371B - Preparation method of ethylene glycol monoether - Google Patents
Preparation method of ethylene glycol monoether Download PDFInfo
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- CN113493371B CN113493371B CN202010269815.5A CN202010269815A CN113493371B CN 113493371 B CN113493371 B CN 113493371B CN 202010269815 A CN202010269815 A CN 202010269815A CN 113493371 B CN113493371 B CN 113493371B
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- C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
- C07C41/01—Preparation of ethers
- C07C41/02—Preparation of ethers from oxiranes
- C07C41/03—Preparation of ethers from oxiranes by reaction of oxirane rings with hydroxy groups
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Abstract
The invention provides a preparation method of ethylene glycol monoether, which comprises the steps of taking ethylene oxide and low-carbon fatty alcohol as raw materials and triethylamine as a catalyst, and reacting in a rectifying tower to obtain the ethylene glycol monoether. The preparation method of the ethylene glycol monobutyl ether has the advantages of simplicity, easiness, environment friendliness and large-scale production.
Description
Technical Field
The invention relates to ethylene glycol monoethers, in particular to a preparation method of ethylene glycol monoethers.
Background
Ethylene glycol monoether is an important derivative of ethylene oxide, is an environment-friendly solvent with excellent performance, and is widely applied to the industrial fields of printing ink, paint, leather, brake fluid and the like. Industrially, glycol ether products are synthesized by ethoxylation reaction under the action of a catalyst mainly by taking ethylene oxide and low-carbon alcohol as raw materials. Taking the reaction of an alcohol (denoted ROH) with Ethylene Oxide (EO) as an example, the ethoxylation reaction can be expressed as:
ROH+EO→RO(EO) 1 H
RO(EO) 1 H+EO→RO(EO) 2 H
RO(EO) 2 H+EO→RO(EO) 3 H
······
ROH+nEO→RO(EO) n H
the ethoxylation reaction generates a series of ethoxylation homologs with different ethylene oxide addition numbers, but the target product needed in industry mainly comprises one or more adducts with low boiling points, and other adducts become byproducts or low-efficiency components, so that developing a reactor technology with high selectivity is a key technical problem to be solved for preparing the products.
The traditional ethylene glycol monoether production adopts a continuous tubular reaction process, and most of the catalyst is a homogeneous inorganic base catalyst, for example, the process for synthesizing ethylene glycol monoethyl ether by a tubular reactor is reported in the document of chemical reaction engineering and Process, volume 32, stage 1, month 2 of 2016. The main feature of the tubular reaction process is that the desired product distribution is achieved by controlling the feed ratio of alcohol and ethylene oxide and product recycle, but a very high alcohol to alkane ratio is required to increase the selectivity of ethylene glycol monoethers, which results in a high energy consumption for the subsequent product separation.
The reactive distillation is a process strengthening technology which couples chemical reaction and distillation separation in the same equipment unit, and has the advantages of improving the conversion rate of raw materials, selectivity of target products, utilizing reaction heat, reducing energy consumption of a system and the like. There are published literature reports on methods for synthesizing ethylene glycol monoether by reactive distillation, such as literature "chemical reaction engineering and Process", month 4 of 2008, 24 nd stage 2, catalytic distillation to synthesize ethylene glycol monomethyl ether; the literature of modern chemical engineering, 11 months in 2007, volume 27, journal (2), catalytic distillation to ethylene glycol monoethyl ether, chemical reaction engineering and process, volume 33, 2017, 6. Compared with the tubular reactor process, the process for synthesizing the ethylene glycol monoether by reaction and rectification has the advantages that: (1) The reaction and separation in the reactive rectifying tower are synchronously carried out, and the generated high-boiling point target product can leave the reaction zone by utilizing the rectification separation effect, so that the high selectivity of the target product can be realized under the condition of very low alcohol-alkane ratio; (2) The reaction heat energy is directly utilized, and the energy consumption of the system is lower.
The advantages of synthesizing ethylene glycol monoethers by reactive distillation are numerous, but the choice of catalyst is relatively difficult and complex. When selecting the most widely used alkali metal catalysts in industry, such as KOH, naOH, sodium alkoxides, etc., there are three technical bottlenecks: (1) If the raw materials contain moisture, the active component alcohol oxygen anions of the catalyst are extremely easy to react with water, so that the activity of the catalyst is seriously reduced, meanwhile, moisture can form accumulation in a tower, and a water removal facility is required to be added; (2) Because the inorganic alkali is not volatilized, the catalyst is difficult to recycle, which not only affects the economy of the device, but also can generate the environmental problem of solid waste treatment; (3) The alkaline catalyst in the product needs to be neutralized, and the salt in the product can affect the quality of the product.
When a solid catalyst is selected, i.e. a heterogeneous reactive distillation process is adopted, although the limitations of the homogeneous reactive process can be overcome, a plurality of problems still exist: (1) The solid base catalyst is formed, placed in a tower and the like without mature effective methods; (2) The deactivation problem of the catalyst will cause the device to be unable to operate stably for a long period of time; (3) The mass transfer mechanism and the reaction mechanism of the three-phase mass transfer of the vapor-liquid-solid in the reaction rectifying tower are complex, and particularly the mass transfer mechanism and the reaction mechanism caused by the surface non-uniformity and the internal diffusion problem of the solid catalyst are difficult to determine. If the research on reaction dynamics and mechanism is not clear, the reliability and safety of the device amplification design are difficult to ensure. Therefore, the selection of the catalyst is a very important and critical issue for the reactive distillation process for synthesizing ethylene glycol monoethers.
There is document J Chem Techonol Biotechnol, 7, 2000, volume 75, 7, reporting that triethylamine can be used as a catalyst for the synthesis of lower alcohol ethoxylates. A process for synthesizing glycol ether by using triethylamine as catalyst features that triethylamine is not only the catalyst of reaction, but also the Huffman elimination reaction with ethylene oxide to generate ethylene and diethyl ethanolamine, which can also react with ethylene oxide to generate 2- (2-diethylaminoethoxy) alcohol. From chemical engineering principle analysis, when the triethylamine catalyst is used for synthesizing ethylene glycol monoether, no matter a tubular reactor or a kettle reactor is used, noncondensable gas ethylene generated by the reaction has an important influence on the operation of the reactor. When a tubular reactor is used, the presence of non-condensable gases within the tube will result in a significant reduction in the heat transfer rate, which can be a significant safety concern. In addition, if the ethylene generated in the reaction process is excessive, the flow pattern of the fluid in the pipe is a gas-liquid two-phase flow, which can cause flow pattern disturbance and cause serious back mixing of the material in the pipe. Therefore, although the triethylamine catalyst is advantageous, if the reactor is not properly selected, the purpose of large-scale industrialized safe production is difficult to achieve.
Disclosure of Invention
The invention provides a preparation method of ethylene glycol monoether, which comprises the steps of reacting ethylene oxide and low-carbon fatty alcohol serving as raw materials with triethylamine serving as a catalyst in a rectifying tower to obtain the ethylene glycol monoether.
The preparation method of the ethylene glycol monobutyl ether has the advantages of simplicity, easiness, environment friendliness and large-scale production.
Drawings
Fig. 1 is a schematic structural diagram of a rectifying tower for synthesizing ethylene glycol monoethers according to an embodiment of the present invention.
Detailed Description
Exemplary embodiments that embody features and advantages of the present invention will be described in detail in the following description. It will be understood that the invention is capable of various modifications in various embodiments, all without departing from the scope of the invention, and that the description and illustrations herein are intended to be by way of illustration only and not to be construed as limiting the invention.
The invention provides a preparation method of ethylene glycol monoether, which comprises the steps of taking ethylene oxide and low-carbon fatty alcohol as raw materials and triethylamine as a catalyst, and reacting in a rectifying tower to obtain the ethylene glycol monoether.
In one embodiment, the lower aliphatic alcohol is C 1 ～C 6 Straight-chain or branched fatty alcohols of (C) are preferred 1 ～C 4 Straight or branched chain fatty alcohols of (a) such as methanol, ethanol, n-propanol, n-butanol, n-pentanol, etc.
In one embodiment, the ethylene glycol monoether may be ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether.
In one embodiment, the reaction process or reaction mechanism of the low carbon fatty alcohol (ROH) and the ethylene oxide mainly comprises the following 4 steps:
(1) Formation of the catalyst active ingredients: triethylamine is first combined with Ethylene Oxide (EO) to form a zwitterionic which activates the alcohol to give an oxyanion (with RO) - Indicated by a formula) to obtain the catalytic active component RO - 。
C 2 H 4 O+C 6 H 15 N→(C 2 H 5 ) 3 N + C 2 H 4 O - (1)
C 6 H 15 N + C 2 H 4 O - +ROH→C 6 H 15 N + C 2 H 4 OH+RO - (2)
(2) Glycol ether homologs are produced: RO obtained in reaction (2) - As an initiator for ethoxylation, glycol ether homologs are produced by stepwise addition reactions of chain initiation, chain extension and proton exchange, the reaction process can be expressed as:
wherein n is EO addition number, one addition (n=1) of ethylene glycol monoether is target product, and the rest is by-product.
(3) Triethylamine and EO undergo huffman (Hoffman) elimination reactions: triethylamine first reacts with EO in the formula (1) to form a zwitterion that breaks down one of the ethyl groups to produce ethylene, while N, N-Diethylethanolamine (DEEA), i.e.:
(C 2 H 5 ) 3 N + C 2 H 4 O - →C 6 H 15 NO+C 2 H 4 (5)
(4) Ethoxylation of DEEA: DEEA contains an active hydrogen and undergoes an ethoxylation reaction with EO to form the 2- [2- (diethylamino) ethoxy ] ethanol (DEAEE) equivalent (the reaction proceeds similarly to alcohol ethoxylation), which can be expressed as:
C 6 H 15 NO+nC 2 H 4 O→C 4 H 10 N(C 2 H 4 O) n+1 H (6)
the chemical reaction principle shows that the synthesis of the ethylene glycol monoether by using triethylamine as a catalyst comprises a series of chemical reactions, wherein the ethylene glycol monoether is a target product. The selectivity of ethylene glycol monoethers is calculated as:
wherein M is 1EO Molar flow of ethylene oxide consumed to form ethylene glycol monoethers, M EO0 For the molar flow of ethylene oxide, M EO1 Is the molar flow of the remaining ethylene oxide.
In one embodiment, the volatilizable triethylamine is used as a catalyst for the reaction of ethylene oxide and low-carbon fatty alcohol, so that the technical bottleneck problem of the traditional inorganic base catalyst can be solved.
In one embodiment, a rectifying tower is used as a reactor for the reaction of ethylene oxide and low-carbon fatty alcohol, so that the high selectivity of ethylene glycol monoether can be ensured.
As shown in fig. 1, a rectifying tower for the reaction of ethylene oxide and lower aliphatic alcohol according to an embodiment of the present invention includes a tower body, a first reflux path, a second reflux path, and a third reflux path.
In one embodiment, the cavity in the column may be divided into a top 11, a reaction section 12, a stripping section 13 and a bottom 14, which are connected in sequence.
In one embodiment, 9 to 15 theoretical plates may be provided in the reaction section 12, and 5 to 10 theoretical plates may be provided in the stripping section 13.
In an embodiment, the material feed ports, such as a low-carbon fatty alcohol feed port, a triethylamine feed port, and an ethylene oxide feed port, may be disposed on the side wall of the tower body, and further, the low-carbon fatty alcohol feed port, the triethylamine feed port, and the ethylene oxide feed port may be disposed on the side wall of the reaction section 12.
In one embodiment, the low-carbon fatty alcohol feed, the triethylamine feed, and the ethylene oxide feed are sequentially disposed in the direction from the top 11 to the bottom 14 of the column such that the low-carbon fatty alcohol feed is adjacent to the top 11 of the column and the ethylene oxide feed is adjacent to the stripping section 13.
In one embodiment, the lower aliphatic alcohol feed port is located at or near the top of the reaction section 12, the triethylamine feed port is located in the upper half of the reaction section 12 (more near the top of the column 11, away from the stripping section 13), and the ethylene oxide feed port is located in the lower half of the reaction section 12, such that higher boiling lower aliphatic alcohol can be fed from the top of the reaction section 12, catalyst can be fed from the upper half of the reaction section 12, and ethylene oxide can be fed from the lower half of the reaction section 12.
In one embodiment, the triethylamine feed inlet is located on 2 to 6 plates of the rectifying column.
In one embodiment, the tower top is connected with the reaction section 12 outside the tower body to form a first reflux path, a first condenser 21 and a reflux tank 22 are arranged on the first reflux path, and the first condenser 21 is respectively connected with the tower top and the reflux tank 22; a condensate feed port is provided in the side wall of the reaction section 12, and a reflux drum 22 is connected to the condensate feed port.
In one embodiment, the reflux drum 22 includes a first inlet, an outlet, a second inlet, and a liquid outlet, which is connected to the first condenser 21 via the first inlet, and connected to the condensate inlet of the reaction section 12 via the liquid outlet.
In one embodiment, the second condenser 23 is further included, and the second condenser 23 is connected to the reflux drum 22 to form a second reflux path.
In one embodiment, the second condenser 23 includes an air inlet, an air outlet, and a liquid outlet, and the second condenser 23 is connected to the air outlet of the reflux drum 22 through the air inlet and connected to the second liquid inlet of the reflux drum 22 through the liquid outlet, so that a second reflux path is formed between the second condenser 23 and the reflux drum 22.
In one embodiment, the first condenser 21 may be cooled by circulating water, and the second condenser 23 may be cooled by a low-temperature refrigerant having a temperature of-20 to 0 ℃.
In one embodiment, a reboiler 31 is disposed outside the rectifying column adjacent to the column bottom 14, and the reboiler 31 is connected to the column bottom and the side wall of the column bottom 14, respectively, such that a third reflux path is formed between the reboiler 31 and the column body.
In one embodiment, the conversion of the feedstock and the selectivity of the ethylene glycol monoether can be increased by adjusting the process conditions such as the operating pressure, reboiling ratio, feedstock feed rate molar ratio, etc. of the rectifying column, for example, ethylene oxide can be completely converted in the column, and the selectivity of the ethylene glycol monoether is greater than 80%.
In one embodiment, the operating pressure of the rectifying column is from atmospheric pressure to 1.0MPa, for example, 0.2MPa, 0.3MPa, 0.5MPa, 0.8MPa, 0.9MPa, etc., in absolute pressure.
In one embodiment, the molar flow ratio of the lower aliphatic alcohol to the ethylene oxide is (1.0-2.0): 1, such as 1.1:1, 1.2:1, 1.3:1, 1.5:1, 1.6:1, 1.8:1, etc.
In one embodiment, the molar flow ratio of triethylamine to ethylene oxide is (0.03-0.08): 1, e.g., 0.04:1, 0.05:1, 0.06:1, 0.07:1, etc.
In one embodiment, the column operates at a reboil ratio of 7 to 12, e.g., 8, 9, 10, 11, etc.
In one embodiment, ethylene oxide and a lower aliphatic alcohol are reacted to form an ethylene glycol monoether product, while ethylene oxide and the catalyst triethylamine are subjected to Hoffman elimination to form ethylene, N-diethylethanolamine, and 2- [2- (diethylamino) ethoxy ] ethanol.
In one embodiment, 96.0-98.0% of ethylene oxide is reacted with a lower aliphatic alcohol to form a glycol ether, and 2.0-4.0% of ethylene oxide and triethylamine are subjected to Hoffman elimination to form ethylene, N-diethyl ethanolamine and 2- (2-diethylaminoethoxy) ethanol. Fresh triethylamine was continuously replenished during the reaction as the ethoxylation side reaction was consumed.
During operation, the low-carbon fatty alcohol, the triethylamine and the ethylene oxide can enter the tower body from the low-carbon fatty alcohol feed inlet, the triethylamine feed inlet and the ethylene oxide feed inlet respectively; under the action of triethylamine, the low-carbon fatty alcohol and ethylene oxide react in a reaction section 12, and the products comprise ethylene glycol monoether, diethylene glycol monoether, triethylene glycol monoether, ethylene, diethyl ethanolamine and 2- [2- (diethylamino) ethoxy ] ethanol, wherein the ethylene is non-condensable gas.
The reacted gas enters a first reflux passage from the top 11 of the tower, after being condensed by a first condenser 21, non-condensable gas containing ethylene and first condensate are formed, the first condensate reenters the tower body along the first reflux passage through a reflux tank 22 to participate in the reaction, the non-condensable gas enters a second reflux passage through the reflux tank 22, the second condensate and the non-condensable gas are further formed under the condensation action of a second condenser 23, the non-condensable gas is directly discharged from the distillation tower device from the second condenser 23, the second condensate flows back to the reflux tank 22, and the second condensate reenters the tower body along the first reflux passage together with the first condensate to participate in the reaction.
Unconverted raw materials and products generated by the reaction in the reaction section 12 are rectified and separated in the stripping section 13, raw materials and catalysts with low boiling points return to the reaction section 12 again to participate in the reaction, tower bottom products with high boiling points enter a third reflux passage from the tower bottom 14, low-boiling point materials enter the tower body again under the action of the reboiler 31, and residual liquid is extracted. The components extracted from the tower bottom comprise low-carbon fatty alcohol, triethylamine, glycol monoether, diethylene glycol monoether, triethylene glycol monoether, diethyl ethanolamine and 2- [2- (diethylamino) ethoxy ] ethanol, which can be separated and purified by a subsequent rectification separation method, wherein the low-boiling-point low-carbon alcohol and the triethylamine can be recycled to the reaction rectifying tower for continuous reaction.
In one embodiment, the ethylene noncondensable gas is withdrawn from the second condenser 23 by condensing the overhead vapor phase feed to ensure column operation stability, and the withdrawn ethylene may be converted or recovered by chemical or physical means.
In one embodiment, the selectivity of ethylene glycol monoethers is increased by using a rectification column as the reactor, and the chemical reaction and product separation in the column are synchronized, so that the reaction is enhanced by the separation.
In one embodiment, the noncondensable ethylene produced by the reaction is discharged from a second condenser 23 of the reactive rectifying tower, and a mixture of glycol ether, triethylamine, N-diethyl ethanolamine and 2- [2- (diethylamino) ethoxy ] ethanol is obtained at the tower bottom.
In one embodiment, triethylamine is used as a catalyst for synthesizing ethylene glycol monoether, the high selectivity of the ethylene glycol monoether of a target product is realized through a process strengthening means of reactive distillation, ethylene noncondensable gas is directly discharged through a method of condensing and refluxing materials at the top of a reactive distillation tower, and the catalyst is recovered and recycled through a distillation method, and meanwhile, diethyl ethanolamine and 2- (2-diethylaminoethoxy) ethanol byproducts with high added values are obtained, so that the purposes of environment-friendly technology and safe and stable operation of the device are achieved.
In one embodiment, the catalyst is recovered and recycled by a distillation/rectification process.
According to the method of the embodiment of the invention, the process strengthening means of reactive distillation is adopted, and the ethoxylation catalytic reaction and the product distillation separation are simultaneously realized in one reactive distillation tower, so that the problems of reaction and separation which can be performed only by adopting a plurality of towers or a plurality of reactors and multiple steps in the prior art are solved, the existing process flow is greatly simplified, and the production cost is reduced.
The method of the embodiment of the invention adopts triethylamine which is not suitable for a kettle type reaction process and a continuous tube type reaction process as a catalyst, and has the advantages of high safety, outstanding innovation, economic addition and the like.
According to the method of the embodiment of the invention, triethylamine is used as the catalyst, and the catalyst can be volatilized, so that the catalyst can be directly recovered and recycled through a rectification method, namely, the catalyst and raw material alcohol can be directly recycled together, thereby solving the problems of non-volatilization of sodium alkoxide catalyst, complex subsequent treatment, difficult recovery and recycling, solid waste treatment and the like.
According to the method of the embodiment of the invention, triethylamine is used as a catalyst, so that the problem of reduced water-contacting activity of the traditional alkaline catalyst can be effectively solved, raw material dehydration equipment and reaction material dehydration equipment are not considered in process design, and accordingly, the flow can be simplified, and investment cost and operation cost can be saved.
According to the method of the embodiment of the invention, triethylamine is used as a catalyst, the method belongs to homogeneous catalytic reaction, the problem of catalyst deactivation does not exist, the problems of non-uniform surface and inner diffusion of a heterogeneous catalyst do not exist, the method is not influenced by inner diffusion in a tower, and the reliability and the safety of the amplification design of the device can be ensured.
The method of one embodiment of the invention can directly utilize the condensation reflux function of the rectifying tower to discharge the ethylene noncondensable gas and make the ethylene react and convert or absorb by a chemical or physical method, and is characterized in that other ethoxylation processes are not provided, such as the liquid flow in the tube of the tube reactor is not allowed to exist, and the kettle reactor has no condensation reflux function.
In addition to the ethylene glycol monoether and the homologs thereof, the process also produces DEEA and DEAEE as byproducts, and the DEEA and DEAEE have wide application, can be used as medical intermediates, softeners, curing agents and the like, and have high added values.
The method for producing ethylene glycol monoethers according to an embodiment of the present invention will be further described below with reference to the accompanying drawings and specific examples. Wherein, the raw materials used are all commercially available.
Example 1
N-butanol is used as low-carbon fatty alcohol participating in the reaction, a rectifying tower shown in fig. 1 is used as a reactor, and structural parameters of the rectifying tower are as follows: the catalytic rectifying tower is provided with 17 theoretical plates, the feed inlets of n-butanol and triethylamine are respectively arranged on the 2 nd plate, and the ethylene oxide feed inlet 5 is arranged on the 12 th plate.
Operating conditions of the catalytic rectification column: the operating pressure was 0.2MPa, the ethylene oxide feed rate was 2.27kmol/h, the feed molar flow ratio of n-butanol to ethylene oxide was 1.3:1, the feed molar flow ratio of triethylamine to ethylene oxide was 0.04:1, the liquid hold-up was 70L, and the reboiling ratio was 9.
In the reaction process, noncondensable gas is discharged through the second condenser 23, the tower top is not extracted, and the liquid phase product extracted from the tower bottom is cooled and then analyzed by using a chromatograph.
The molar composition of the tower kettle product is as follows: 30.19% of N-butanol, 62.13% of ethylene glycol monobutyl ether, 4.11% of diethylene glycol monobutyl ether, 0.3% of triethylene glycol monobutyl ether, 2.20% of N, N-diethyl ethanolamine and 0.31% of 2- [2- (diethylamino) ethoxy ] ethanol.
The ethylene oxide conversion was calculated to be 99.96% and the selectivity of ethylene glycol monobutyl ether was calculated to be 83.21%.
Example 2
Ethanol was used as a low-carbon fatty alcohol to be reacted, and the same rectifying tower as in example 1 was used for the reaction.
Wherein, the operation condition of the catalytic rectifying tower: the operating pressure was 0.3MPa, the ethylene oxide feed rate was 2.27kmol/h, the feed molar flow ratio of ethanol to ethylene oxide was 1.1:1, the feed molar flow ratio of triethylamine to ethylene oxide was 0.04:1, the liquid hold-up was 70L, and the reboil ratio was 8.
In the reaction process, noncondensable gas is discharged through the second condenser 23, the tower top is not extracted, and the liquid phase product extracted from the tower bottom is cooled and then analyzed by using a chromatograph.
The molar composition of the tower kettle product is as follows: 18.71% of ethanol, 72.80% of ethylene glycol monoethyl ether, 5.41% of diethylene glycol monoethyl ether, 0.62% of triethylene glycol monoethyl ether, 1.91% of N, N-diethyl ethanolamine and 0.59% of 2- [2- (diethylamino) ethoxy ] ethanol.
The ethylene oxide conversion was calculated to be 99.99% and the selectivity of ethylene glycol monoethyl ether was calculated to be 81.71%.
Example 3
The reaction was carried out using methanol as the lower aliphatic alcohol involved in the reaction using the same rectifying column as in example 1.
Wherein, the operation condition of the catalytic rectifying tower: the operating pressure was 0.4MPa, the ethylene oxide feed rate was 2.27kmol/h, the feed molar flow ratio of n-butanol to ethylene oxide was 1.1:1, the feed molar flow ratio of triethylamine to ethylene oxide was 0.03:1, the liquid hold-up was 50L, and the reboiling ratio was 10.
In the reaction process, noncondensable gas is discharged through the second condenser 23, the tower top is not extracted, and the liquid phase product extracted from the tower bottom is cooled and then analyzed by using a chromatograph.
The molar composition of the tower kettle product is as follows: 18.78% of methanol, 72.51% of ethylene glycol monomethyl ether, 6.20% of diethylene glycol monomethyl ether, 0.72% of triethylene glycol monomethyl ether, 1.4% of N, N-diethyl ethanolamine and 0.41% of 2- [2- (diethylamino) ethoxy ] ethanol.
The ethylene oxide conversion was calculated to be 99.99% and the selectivity of ethylene glycol monomethyl ether was calculated to be 80.82%.
Example 4
This example is substantially identical to the reaction apparatus and process conditions used in example 1, except that: the feed inlet of n-butyl alcohol is arranged on the 2 nd plate, and the feed inlet of triethylamine is arranged on the 4 th plate.
Wherein, the molar composition of the tower kettle product is as follows: 30.23% of N-butanol, 62.05% of ethylene glycol monobutyl ether, 4.15% of diethylene glycol monobutyl ether, 0.30% of triethylene glycol monobutyl ether, 2.28% of N, N-diethyl ethanolamine and 0.36% of 2- [2- (diethylamino) ethoxy ] ethanol.
The ethylene oxide conversion was calculated to be 99.97% and the ethylene glycol monobutyl ether selectivity was calculated to be 83.10%.
Example 5
This example is substantially identical to the reaction apparatus and process conditions used in example 1, except that: the molar flow ratio of triethylamine to ethylene oxide feed was 0.06:1.
Wherein, the molar composition of the tower kettle product is as follows: n-butanol 31.02%, ethylene glycol monobutyl ether 59.90%, diethylene glycol monobutyl ether 3.90%, triethylene glycol monobutyl ether 0.28%, N, N-diethyl ethanolamine 3.47%,2- [2- (diethylamino) ethoxy ] ethanol 0.57%.
The ethylene oxide conversion was calculated to be 99.99% and the selectivity of ethylene glycol monobutyl ether was calculated to be 81.44%.
Example 6
This example is substantially identical to the reaction apparatus and process conditions used in example 1, except that: the molar flow ratio of n-butanol to ethylene oxide was 1.6:1.
Wherein, the molar composition of the tower kettle product is as follows: n-butanol 42.41%, ethylene glycol monobutyl ether 51.81%, diethylene glycol monobutyl ether 2.90%, triethylene glycol monobutyl ether 0.17%, N, N-diethyl ethanolamine 1.91%,2- [2- (diethylamino) ethoxy ] ethanol 0.26%.
The ethylene oxide conversion was calculated to be 99.95% and the selectivity of ethylene glycol monobutyl ether was calculated to be 84.97%.
Example 7
This example is substantially identical to the reaction apparatus and process conditions used in example 1, except that: the reboiling ratio was 11.
Wherein, the molar composition of the tower kettle product is as follows: n-butanol 29.56%, ethylene glycol monobutyl ether 63.33%, diethylene glycol monobutyl ether 3.59%, triethylene glycol monobutyl ether 2.14%, N, N-diethyl ethanolamine 2.33%,2- [2- (diethylamino) ethoxy ] ethanol 0.32%.
The ethylene oxide conversion was calculated to be 99.91% and the selectivity of ethylene glycol monobutyl ether was calculated to be 84.87%.
The preferred operating parameters are calculated as follows, the operating pressure of the rectifying tower is 0.1-0.2 MPa, the feeding mole flow ratio of the low-carbon fatty alcohol and the ethylene oxide is (1.3-1.6): 1, the mole flow ratio of the triethylamine and the ethylene oxide is (0.03-0.05): 1, the operating reboiling ratio of the tower is 9-11, and the selectivity range of the ethylene glycol monobutyl ether is 82.9% -85.0%.
Unless otherwise defined, all terms used herein are intended to have the meanings commonly understood by those skilled in the art.
The described embodiments of the present invention are intended to be illustrative only and not to limit the scope of the invention, and various other alternatives, modifications, and improvements may be made by those skilled in the art within the scope of the invention, and therefore the invention is not limited to the above embodiments but only by the claims.
Claims (1)
1. A preparation method of ethylene glycol monoether is characterized in that,
the method comprises the steps of reacting in a rectifying tower to obtain ethylene glycol monoether;
the rectifying tower comprises a tower body, and a first reflux passage, a second reflux passage and a third reflux passage which are arranged outside the tower body; the tower body comprises a tower top, a reaction section, a stripping section and a tower bottom which are connected in sequence; the top of the tower is connected with the reaction section outside the tower body to form the first reflux passage, the second reflux passage is connected with the first reflux passage, the third reflux passage is arranged at the bottom of the tower, and a reboiler is arranged on the third reflux passage; a first condenser and a reflux tank are arranged on the first reflux passage, and the first condenser is respectively connected with the tower top and the reflux tank; a condensate liquid feed port is formed in the side wall of the reaction section, and the reflux tank is connected with the condensate liquid feed port; the second condenser is connected with the reflux tank to form a second reflux passage; the reflux tank comprises a first liquid inlet, an air outlet, a second liquid inlet and a liquid outlet; the reflux tank is connected with the first condenser through the first liquid inlet and is connected with a condensate liquid feed inlet of the reaction section through the liquid outlet; the second condenser comprises an air inlet, an air outlet and a second liquid outlet; the second condenser is connected with the air outlet of the reflux tank through the air inlet and is connected with the second liquid inlet of the reflux tank through the second liquid outlet; sequentially arranging a low-carbon fatty alcohol feed inlet, a triethylamine feed inlet and an ethylene oxide feed inlet along the direction from the top of the tower to the bottom of the tower;
the method takes ethylene oxide and low-carbon fatty alcohol as raw materials, and triethylamine as a catalyst; the low-carbon fatty alcohol, triethylamine and ethylene oxide enter the tower body from a low-carbon fatty alcohol feed inlet, a triethylamine feed inlet and an ethylene oxide feed inlet respectively, the low-carbon fatty alcohol and the ethylene oxide react in the reaction section under the catalysis of the triethylamine, and the products comprise ethylene glycol monoether, diethylene glycol monoether, triethylene glycol monoether, ethylene, diethyl ethanolamine and 2- [2- (diethylamino) ethoxy ] ethanol, wherein the ethylene is non-condensable gas; the reacted gas enters a first reflux passage from the top of the tower, after being condensed by a first condenser, non-condensable gas containing ethylene and first condensate are formed, the first condensate reenters the tower body along the first reflux passage through a reflux tank to participate in the reaction, the ethylene non-condensable gas enters a second reflux passage through the reflux tank, the second condensate and the second non-condensable gas are further formed under the condensation action of the second condenser, the second non-condensable gas is directly discharged out of the distillation tower device from the second condenser, the second condensate flows back to the reflux tank, and reenters the tower body along the first reflux passage together with the first condensate to participate in the reaction; the unconverted raw materials and the products generated by the reaction in the reaction section are rectified and separated in the stripping section, the raw materials with low boiling point and the catalyst triethylamine return to the reaction section again to participate in the reaction, the tower bottom products with high boiling point enter a third reflux passage from the bottom of the tower, the low boiling point materials enter the tower body again under the action of a reboiler, and the residual liquid is extracted; the first condenser is cooled by circulating water, and the second condenser is cooled by a low-temperature refrigerant with the temperature of-20-0 ℃;
the molar flow ratio of the catalyst to the ethylene oxide is (0.03-0.08) to 1, the molar flow ratio of the low-carbon fatty alcohol to the ethylene oxide is (1.0-2.0) to 1, the operating pressure of the rectifying tower is normal pressure-1.0 MPa, the reboiling ratio is 7-12, and the feed inlet of the triethylamine is positioned on 2-6 plates of the rectifying tower.
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| 朱明军，梁世中.第四节 精馏塔.《生物工程设备》.北京：中国轻工业出版社,2019,416-440. * |
| 袁相爱.第三章 化工原理基础实验.《化工原理基础实验》.东营:中国石油大学出版社,2018,108-112. * |
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