CN113493371B - Preparation method of ethylene glycol monoether - Google Patents

Abstract

The invention provides a method for preparing ethylene glycol monoether, which comprises taking ethylene oxide and low-carbon aliphatic alcohol as raw materials and triethylamine as a catalyst, and reacting in a rectification tower to prepare the ethylene glycol monoether. The preparation method of ethylene glycol monobutyl ether according to one embodiment of the present invention has the advantages of simplicity, environmental protection and large-scale production.

Description

A kind of preparation method of ethylene glycol monoether

technical field

The invention relates to ethylene glycol monoether, in particular to a preparation method of ethylene glycol monoether.

Background technique

Ethylene glycol monoether is an important derivative of ethylene oxide. It is an environmentally friendly solvent with excellent performance and is widely used in industrial fields such as ink, paint, leather and brake fluid. Industrially, glycol ether products are mainly synthesized by ethoxylation reaction using ethylene oxide and low-carbon alcohol as raw materials under the action of a catalyst. Taking the reaction of alcohol (expressed in ROH) and 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 above ethoxylation reaction will generate a series of ethoxylated homologues with different addition numbers of ethylene oxide, but the target product needed in industry is mainly one or several adducts with low boiling point, and other adducts become by-products or low-efficiency components. Therefore, the development of reactor technology with high selectivity is the key technical problem to be solved for the production of such products.

Traditional ethylene glycol monoether production adopts a continuous tubular reaction process, and the catalysts are mostly homogeneous inorganic base catalysts. For example, the document "Chemical Reaction Engineering and Technology", February 2016, Volume 32, No. 1, reported the process of synthesizing ethylene glycol monoethyl ether in a tubular reactor. The main feature of the tubular reaction process is to achieve ideal product distribution by controlling the feed ratio of alcohol and ethylene oxide and product circulation, but increasing the selectivity of ethylene glycol monoether requires a high alcohol-to-alkane ratio, which will lead to high energy consumption for subsequent product separation.

Reactive distillation is a process intensification technology that couples chemical reaction and distillation separation in the same equipment unit. It has the advantages of improving raw material conversion rate, target product selectivity, utilizing reaction heat and reducing system energy consumption. There are public literature reports on the method of applying reactive distillation to synthesize ethylene glycol monoether, such as the document "Chemical Reaction Engineering and Technology", April 2008, Volume 24, No. 2, Catalytic Distillation to Synthesize Ethylene Glycol Monomethyl Ether; Document "Modern Chemical Industry", November 2007, Volume 27 Supplement (2), Synthesis of Ethylene Glycol Monoether by Catalytic Distillation, "Chemical Reaction Engineering and Technology", 2017 Volume 33, No. 6. Compared with the tubular reactor process, the advantages of the reactive distillation synthesis of ethylene glycol monoether process are: (1) The reaction and separation in the reactive distillation tower are carried out simultaneously, and the high-boiling target product can be separated from the reaction zone by means of rectification and separation, which can ensure the high selectivity of the target product under the condition of very low alcohol-to-alkane ratio; (2) The heat energy of the reaction is directly used, and the energy consumption of the system is lower.

Synthesis of ethylene glycol monoether by reactive distillation has many advantages, but the selection of catalyst is relatively difficult and complicated. When choosing the most widely used alkali metal catalysts in industry, such as KOH, NaOH and sodium alkoxide, there are three technical bottlenecks: (1) if the raw material contains water, the active component alcohol anion of the catalyst will easily react with water, which will lead to a serious reduction in catalyst activity, and at the same time, water will accumulate in the tower, requiring additional water removal facilities; It needs to be neutralized, and the salt in the product will affect the quality of the product.

When selecting a solid catalyst, that is, using a heterogeneous reaction distillation process, although the limitations of the homogeneous reaction process can be overcome, there are still many problems: (1) there are no mature and effective methods for forming the solid base catalyst and placing it in the tower; (2) the deactivation problem of the catalyst will cause the device to fail to operate stably for a long time; If the research on the reaction kinetics and mechanism is unclear, the reliability and safety of the scale-up design of the device cannot be guaranteed. Therefore, for the synthesis of ethylene glycol monoether by reactive distillation, the selection of catalyst is a very important and key issue.

There is a document "J Chem Techonol Biotechnol", July 2000, volume 75, the seventh phase reports that triethylamine can be used as a catalyst for the synthesis of lower alcohol ethoxylates. One of the main features of the synthesis of glycol ethers using triethylamine catalysts is that triethylamine is not only a catalyst for the reaction, but also Hoffman elimination reactions with ethylene oxide to produce ethylene and diethylethanolamine products, and the latter can also react with oxirane to generate 2-(2-diethylaminoethoxy)ethanol. From the analysis of chemical engineering principles, when triethylamine catalyst is used to synthesize ethylene glycol monoether, whether it is a tubular reactor or a tank reactor, the non-condensable gas ethylene produced by the reaction has an important impact on the operation of the reactor. When a tubular reactor is used, the existence of non-condensable gas in the tube will lead to a serious decrease in the heat transfer rate, which will be a huge safety hazard. In addition, if too much ethylene is generated during the reaction process, the flow pattern of the fluid in the tube will be a gas-liquid two-phase flow, which will cause flow pattern disorder and cause serious back-mixing of the material in the tube. Therefore, although the use of triethylamine catalyst has its advantages, if the reactor is not properly selected, it is difficult to achieve the purpose of large-scale industrialized safe production.

Contents of the invention

A main purpose of the present invention is to provide a kind of preparation method of ethylene glycol monoether, comprising taking ethylene oxide and low-carbon aliphatic alcohol as raw material, triethylamine as catalyst, reacting in rectifying tower to prepare described ethylene glycol monoether.

The preparation method of ethylene glycol monobutyl ether according to one embodiment of the present invention has the advantages of simplicity, environmental protection and large-scale production.

Description of drawings

Fig. 1 is a structural schematic diagram of a rectification column for synthesizing ethylene glycol monoether according to an embodiment of the present invention.

Detailed ways

Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different embodiments without departing from the scope of the present invention, and that the descriptions and illustrations therein are illustrative in nature rather than limiting the present invention.

One embodiment of the present invention provides a method for preparing ethylene glycol monoether, which comprises using ethylene oxide and low-carbon aliphatic alcohol as raw materials and triethylamine as a catalyst to prepare ethylene glycol monoether through reaction in a rectification tower.

In one embodiment, the low-carbon fatty alcohol refers to C ₁ -C ₆ straight chain or branched chain fatty alcohol, preferably C ₁ -C ₄ straight chain or branched chain fatty alcohol, 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, or ethylene glycol monobutyl ether.

In one embodiment, the reaction process or reaction mechanism of low-carbon aliphatic alcohol (ROH), ethylene oxide mainly includes the following 4 steps:

(1) Formation of catalytic active components: Triethylamine first combines with ethylene oxide (EO) to form zwitterions, which can activate alcohols to obtain alcohol oxyanions (represented by RO ^- ), that is, to obtain catalytic active components 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) Generation of glycol ether homologues: the RO obtained from reaction (2) ^is the initiator of the ethoxylation reaction, through the step-by-step addition reaction of chain initiation, chain growth and proton exchange, glycol ether homologues are generated, and the reaction process can be expressed as:

Wherein, n is the addition number of EO, one addition (n=1) product ethylene glycol monoether is the target product, and the rest are by-products.

(3) Hoffman (Hoffman) elimination reaction between triethylamine and EO: triethylamine first reacts with EO in formula (1) to generate zwitterions, which can decompose one of the ethyl groups to generate ethylene, and simultaneously generate N,N-diethylethanolamine (DEEA), namely:

(C ₂ H ₅ ) ₃ N ⁺ C ₂ H ₄ O ^- →C ₆ H ₁₅ NO+C ₂ H ₄ (5)

(4) Ethoxylation reaction of DEEA: DEEA molecule contains active hydrogen, and ethoxylation reaction occurs with EO to generate 2-[2-(diethylamino)ethoxy]ethanol (DEAEE) and other homologues (the reaction process is similar to the ethoxylation of alcohol), 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 above chemical reaction principle shows that the synthesis of ethylene glycol monoether with triethylamine as a catalyst includes a series of chemical reactions, wherein ethylene glycol monoether is the target product. The formula for calculating the selectivity of ethylene glycol monoether is:

Among them, M _1EO is the molar flow rate of ethylene oxide consumed to generate ethylene glycol monoether, M _EO0 is the molar flow rate of ethylene oxide feed, and M _EO1 is the molar flow rate of remaining ethylene oxide.

In one embodiment, the use of volatile triethylamine as a catalyst for the reaction between ethylene oxide and lower aliphatic alcohols can overcome the technical bottleneck problem of traditional inorganic base catalysts.

In one embodiment, a rectification tower is used as a reactor for the reaction between ethylene oxide and low-carbon aliphatic alcohols, which can ensure high selectivity of ethylene glycol monoether.

As shown in FIG. 1 , a rectification column for the reaction of ethylene oxide and lower aliphatic alcohols according to an embodiment of the present invention includes a column body, a first reflux path, a second reflux path and a third reflux path.

In one embodiment, the cavity in the tower body can be divided into a tower top 11 , a reaction section 12 , a stripping section 13 and a tower bottom 14 which are sequentially connected.

In one embodiment, 9-15 theoretical trays can be installed in the reaction section 12, and 5-10 theoretical trays can be installed in the stripping section 13.

In one embodiment, the feed ports for materials, such as low-carbon fatty alcohol feed ports, triethylamine feed ports, and ethylene oxide feed ports, can be arranged on the side walls of the tower body.

In one embodiment, along the direction from the top 11 of the tower to the bottom 14 of the tower, the low-carbon aliphatic alcohol feed port, the triethylamine feed port, and the ethylene oxide feed port are arranged in sequence, so that the low-carbon fatty alcohol feed port is adjacent to the tower top 11, and the ethylene oxide feed port is adjacent to the stripping section 13.

In one implementation method, the low -carbon fat alcohol feed inlet is located at the top of or adjacent to the neighboring reaction section 12, and the inlet of the triamines is located in the upper half of the reaction section 12 (more adjacent to the top of the tower 11, away from the distillation section 13). In the upper half of the 12, ethylene oxide can reflect the lower half of the reactive section 12.

In one embodiment, the triethylamine feed port is located on 2 to 6 plates of the rectification column.

In one embodiment, the top of the tower and the reaction section 12 are connected outside the tower to form a first reflux path. A first condenser 21 and a reflux tank 22 are arranged on the first reflux path. The first condenser 21 is connected to the top of the tower and the reflux tank 22 respectively; a condensate feed port is provided on the side wall of the reaction section 12, and the reflux tank 22 is connected to the condensate feed port.

In one embodiment, the reflux tank 22 includes a first liquid inlet, a gas outlet, a second liquid inlet and a liquid outlet, which are connected to the first condenser 21 through the first liquid inlet, and connected to the condensate feed port of the reaction section 12 through the liquid outlet.

In one embodiment, a second condenser 23 is further included, and the second condenser 23 is connected with the reflux tank 22 to form a second reflux passage.

In one embodiment, the second condenser 23 includes an air inlet, an air outlet, and a liquid outlet. The second condenser 23 is connected to the air outlet of the reflux tank 22 through the air inlet, and is connected to the second liquid inlet of the reflux tank 22 through the liquid outlet, so that a second reflux path is formed between the second condenser 23 and the reflux tank 22.

In one embodiment, the first condenser 21 can be cooled by circulating water, and the second condenser 23 can be cooled by a low-temperature refrigerant with a temperature of -20°C to 0°C.

In one embodiment, a reboiler 31 is provided outside the rectification column adjacent to the bottom 14 of the column, and the reboiler 31 is connected to the bottom of the column and the sidewall of the bottom 14 of the column respectively, so that a third reflux passage is formed between the reboiler 31 and the column body.

In one embodiment, the conversion rate of raw materials and the selectivity of ethylene glycol monoether can be improved by adjusting the process conditions such as the operating pressure of the rectification tower, the reboil ratio, the molar ratio of the feed flow of raw materials, for example, ethylene oxide can be completely converted in the tower, and the selectivity of ethylene glycol monoether is greater than 80%.

In one embodiment, the operating pressure of the rectification column is atmospheric pressure to 1.0 MPa in absolute pressure, such as 0.2 MPa, 0.3 MPa, 0.5 MPa, 0.8 MPa, 0.9 MPa, and the like.

In one embodiment, the feed molar flow ratio of low-carbon aliphatic alcohol and 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, such as 0.04:1, 0.05:1, 0.06:1, 0.07:1, etc.

In one embodiment, the operation reboil ratio of the column is 7-12, such as 8, 9, 10, 11 and so on.

In one embodiment, ethylene oxide reacts with low-carbon aliphatic alcohols to generate ethylene glycol monoether products, and at the same time, ethylene oxide reacts with catalyst triethylamine to generate ethylene, N,N-diethylethanolamine and 2-[2-(diethylamino)ethoxy]ethanol through Hoffman elimination reaction.

In one embodiment, 96.0-98.0% of ethylene oxide neutralizes low-carbon aliphatic alcohols to generate glycol ethers, and 2.0-4.0% of ethylene oxide and triethylamine undergo Hoffman elimination reactions to generate ethylene, N,N-diethylethanolamine and 2-(2-diethylaminoethoxy)ethanol. As the side reaction of ethoxylation is consumed, fresh triethylamine is constantly replenished during the reaction.

During operation, low-carbon fatty alcohol, triethylamine, and ethylene oxide can enter the tower body from the low-carbon fatty alcohol feed port, triethylamine feed port, and ethylene oxide feed port respectively; under the action of triethylamine, low-carbon fatty alcohol and ethylene oxide react in the reaction section 12, and the products include ethylene glycol monoether, diethylene glycol monoether, triethylene glycol monoether, ethylene, diethylethanolamine and 2-[2-(diethylamino)ethoxy]ethanol, wherein ethylene is a non-condensable gas.

The reacted gas enters the first reflux passage from the tower top 11, and after being condensed by the first condenser 21, non-condensable gas and first condensate containing ethylene are formed. The first condensate re-enters the tower body through the reflux tank 22 along the first reflux passage to participate in the reaction, and the non-condensable gas enters the second reflux passage through the reflux tank 22, and is further formed under the condensation of the second condenser 23. The second condensate and non-condensable gas are further formed. Together with the first condensate, it re-enters the tower body along the first reflux path to participate in the reaction.

The unconverted raw materials and reaction products in the reaction section 12 are rectified and separated in the stripping section 13. The raw materials and catalysts with low boiling points return to the reaction section 12 to participate in the reaction, and the tower still products with high boiling points enter the third reflux channel from the bottom 14 of the tower. The components withdrawn from the tower bottom include low-carbon fatty alcohol, triethylamine, ethylene glycol monoether, diethylene glycol monoether, triethylene glycol monoether, diethylethanolamine and 2-[2-(diethylamino)ethoxy]ethanol. These components can be separated and purified by subsequent rectification separation, wherein low-boiling low-carbon alcohol and triethylamine can be recycled to the reactive distillation column to continue the reaction.

In one embodiment, the ethylene noncondensable gas is extracted from the second condenser 23 by condensing and refluxing the vapor phase material at the top of the tower, which ensures the stability of the operation of the tower. At the same time, the extracted ethylene can be converted or recovered by chemical or physical methods.

In one embodiment, by using a rectification tower as a reactor, the selectivity of ethylene glycol monoether can be improved, and the chemical reaction and product separation in the tower are carried out simultaneously, and the reaction is strengthened through the separation.

In one embodiment, the non-condensable gas ethylene produced by the reaction is discharged from the second condenser 23 of the reactive distillation column, and a mixture of glycol ether, triethylamine, N,N-diethylethanolamine and 2-[2-(diethylamino)ethoxy]ethanol is obtained from the bottom of the column.

In one embodiment, triethylamine is used as a catalyst for the synthesis of ethylene glycol monoether, and the high selectivity of the target product ethylene glycol monoether is achieved through reactive distillation process intensification means, ethylene noncondensable gas is directly discharged through the method of condensing and refluxing the top material of the reactive distillation tower, and the catalyst is recovered and reused through distillation, and diethylethanolamine and 2-(2-diethylaminoethoxy)ethanol by-products with high added value are obtained at the same time, so as to achieve the purpose of green process and safe and stable operation of the device.

In one embodiment, the catalyst is recovered and reused through a distillation/rectification process.

The method of one embodiment of the present invention adopts the process strengthening means of reactive distillation to simultaneously realize ethoxylation catalytic reaction and product distillation separation in one reactive distillation tower, which solves the problem of reaction and separation that can only be carried out by using multiple towers or multiple reactors and multiple steps in the prior art, greatly simplifies the existing process flow, and reduces production costs.

The method according to one embodiment of the present invention uses triethylamine as a catalyst which is not suitable for the tank reaction process and the continuous tubular reaction process, and has the advantages of high safety, outstanding innovation and extra points for economy.

In the method of one embodiment of the present invention, triethylamine is used as a catalyst. Since the catalyst is volatile, it can be directly recovered and reused by rectification, that is, the catalyst and the raw material alcohol can be directly recycled together, and the problems of non-volatility of the sodium alkoxide catalyst, complicated follow-up treatment, difficulty in recycling, and solid waste treatment can be overcome.

In the method of one embodiment of the present invention, using triethylamine as a catalyst can effectively overcome the problem of reduced activity of traditional alkaline catalysts when encountering water, and the process design does not consider raw material dehydration equipment and reaction material dehydration equipment, thereby simplifying the process and saving investment and operating costs.

The method of an embodiment of the present invention uses triethylamine as a catalyst, which belongs to a homogeneous catalytic reaction, and has no problems of catalyst deactivation, non-uniform surface and internal diffusion of heterogeneous catalysts, and is not affected by interphase diffusion in the tower. The reliability and safety of the scale-up design of the device can be guaranteed.

The method of one embodiment of the present invention can directly use the function of condensation and reflux of the rectification tower to discharge ethylene non-condensable gas, and react and convert or absorb ethylene through chemical or physical methods. This feature is not available in other ethoxylation processes. For example, the liquid flow in the tube of the tubular reactor does not allow the existence of non-condensable gas, and the tank reactor has no condensation and reflux function.

In the method of one embodiment of the present invention, in addition to obtaining ethylene glycol monoether and its homologues, the process also produces DEEA and DEAEE by-products. These two products have a wide range of uses and can be used as pharmaceutical intermediates, softeners, curing agents, etc., and have high added value.

Hereinafter, the preparation method of ethylene glycol monoether according to one embodiment of the present invention will be further described with reference to the accompanying drawings and specific examples. Wherein, the raw materials used are all commercially available.

Example 1

Take n-butanol as the low-carbon aliphatic alcohol participating in the reaction, adopt the rectifying tower shown in Figure 1 as the reactor, and the structural parameters of the rectifying tower: the catalytic rectifying tower is provided with 17 theoretical plates, the feed ports of n-butanol and triethylamine are all arranged on the second plate, and the ethylene oxide feed port 5 is arranged on the twelfth plate.

The operating conditions of the catalytic distillation column: the operating pressure is 0.2MPa, the feed flow rate of ethylene oxide is 2.27kmol/h, the feed molar flow ratio of n-butanol and ethylene oxide is 1.3:1, the feed molar flow ratio of triethylamine and ethylene oxide is 0.04:1, the liquid holdup is 70L, and the reboil ratio is 9.

During the reaction process, the non-condensable gas is discharged through the second condenser 23, and there is no extraction at the top of the tower, and the liquid phase product extracted from the tower reactor is cooled and then analyzed by chromatography.

The molar composition of the bottom product is: n-butanol 30.19%, ethylene glycol monobutyl ether 62.13%, diethylene glycol monobutyl ether 4.11%, triethylene glycol monobutyl ether 0.3%, N,N-diethylethanolamine 2.20%, 2-[2-(diethylamino)ethoxy]ethanol 0.31%.

After calculation, the conversion rate of ethylene oxide is 99.96%, and the selectivity of ethylene glycol monobutyl ether is 83.21%.

Example 2

Take ethanol as the low-carbon aliphatic alcohol participating in the reaction, and adopt the rectifying tower identical with embodiment 1 to carry out reaction.

Among them, the operating conditions of the catalytic rectification tower: the operating pressure is 0.3MPa, the feed flow rate of ethylene oxide is 2.27kmol/h, the feed molar flow ratio of ethanol and ethylene oxide is 1.1:1, the feed molar flow ratio of triethylamine and ethylene oxide is 0.04:1, the liquid holdup is 70L, and the reboil ratio is 8.

During the reaction process, the non-condensable gas is discharged through the second condenser 23, and there is no extraction at the top of the tower, and the liquid phase product extracted from the tower reactor is cooled and then analyzed by chromatography.

The molar composition of the tower still product is: ethanol 18.71%, ethylene glycol monoethyl ether 72.80%, diethylene glycol monoethyl ether 5.41%, triethylene glycol monoethyl ether 0.62%, N,N-diethylethanolamine 1.91%, 2-[2-(diethylamino)ethoxy]ethanol 0.59%.

After calculation, the conversion rate of ethylene oxide is 99.99%, and the selectivity of ethylene glycol monoethyl ether is 81.71%.

Example 3

Take methanol as the low-carbon aliphatic alcohol participating in the reaction, and adopt the same rectifying tower as in Example 1 to carry out the reaction.

Among them, the operating conditions of the catalytic rectification tower: the operating pressure is 0.4MPa, the feed flow rate of ethylene oxide is 2.27kmol/h, the feed molar flow ratio of n-butanol and ethylene oxide is 1.1:1, the feed molar flow ratio of triethylamine and ethylene oxide is 0.03:1, the liquid hold-up capacity is 50L, and the reboil ratio is 10.

During the reaction process, the non-condensable gas is discharged through the second condenser 23, and there is no extraction at the top of the tower, and the liquid phase product extracted from the tower reactor is cooled and then analyzed by chromatography.

The molar composition of the tower still product is: 18.78% methanol, 72.51% ethylene glycol monomethyl ether, 6.20% diethylene glycol monomethyl ether, 0.72% triethylene glycol monomethyl ether, 1.4% N,N-diethylethanolamine, and 0.41% 2-[2-(diethylamino)ethoxy]ethanol.

After calculation, the conversion rate of ethylene oxide is 99.99%, and the selectivity of ethylene glycol monomethyl ether is 80.82%.

Example 4

The reaction device and process conditions used in this example and Example 1 are basically the same, the difference being that the feed inlet of n-butanol is arranged on the 2nd plate, and the feed inlet of triethylamine is arranged on the 4th plate.

Among them, the molar composition of the tower still product is: 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-diethylethanolamine, and 0.36% of 2-[2-(diethylamino)ethoxy]ethanol.

After calculation, the conversion rate of ethylene oxide is 99.97%, and the selectivity of ethylene glycol monobutyl ether is 83.10%.

Example 5

The reaction device and process conditions used in this example are basically the same as those in Example 1, except that the feed molar flow ratio of triethylamine and ethylene oxide is 0.06:1.

Among them, the molar composition of the bottom product is: n-butanol 31.02%, ethylene glycol monobutyl ether 59.90%, diethylene glycol monobutyl ether 3.90%, triethylene glycol monobutyl ether 0.28%, N,N-diethylethanolamine 3.47%, 2-[2-(diethylamino)ethoxy]ethanol 0.57%.

After calculation, the conversion rate of ethylene oxide is 99.99%, and the selectivity of ethylene glycol monobutyl ether is 81.44%.

Example 6

The reaction device and process conditions used in this example are basically the same as those in Example 1, except that the molar flow ratio of n-butanol and ethylene oxide is 1.6:1.

Among them, the molar composition of the bottom product is: 42.41% of n-butanol, 51.81% of ethylene glycol monobutyl ether, 2.90% of diethylene glycol monobutyl ether, 0.17% of triethylene glycol monobutyl ether, 1.91% of N,N-diethylethanolamine, and 0.26% of 2-[2-(diethylamino)ethoxy]ethanol.

After calculation, the conversion rate of ethylene oxide is 99.95%, and the selectivity of ethylene glycol monobutyl ether is 84.97%.

Example 7

The reaction device and process conditions used in this example are basically the same as those in Example 1, the difference being that the reboil ratio is 11.

Among them, the molar composition of the bottom product is: 29.56% of n-butanol, 63.33% of ethylene glycol monobutyl ether, 3.59% of diethylene glycol monobutyl ether, 2.14% of triethylene glycol monobutyl ether, 2.33% of N,N-diethylethanolamine, and 0.32% of 2-[2-(diethylamino)ethoxy]ethanol.

After calculation, the conversion rate of ethylene oxide is 99.91%, and the selectivity of ethylene glycol monobutyl ether is 84.87%.

After calculation, the preference of each operating parameter is as follows, the operating pressure of the rectification tower is 0.1-0.2MPa, the feed molar flow ratio of low-carbon aliphatic alcohol and ethylene oxide is (1.3-1.6):1, the molar flow ratio of triethylamine and ethylene oxide is (0.03-0.05):1, the operating reboil ratio of the tower is 9-11, and the selectivity range of ethylene glycol monobutyl ether is 82.9%-85.0%.

Unless otherwise defined, the terms used in the present invention have meanings commonly understood by those skilled in the art.

The embodiments described in the present invention are only for exemplary purposes, and are not intended to limit the protection scope of the present invention. Those skilled in the art can make various other replacements, changes and improvements within the scope of the present invention. Therefore, the present invention is not limited to the above-mentioned embodiments, but only defined 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.