A highly efficient preparation method of ethylene glycol butyl ether

Abstract

The application discloses a high-efficiency preparation method of ethylene glycol butyl ether and belongs to the technical field of fine chemical industry. The method uses n-butanol and ethylene oxide as raw materials, uses halogen salt as a catalyst, adds the n-butanol, the catalyst and the ethylene oxide into a reaction kettle, and carries out an addition reaction under the conditions of a temperature of 120 DEG C to 150 DEG C and a pressure of 0.1 to 4 MPa, so that the ethylene glycol butyl ether is prepared in one step. The halogen salt is selected from one or more of zinc bromide, zinc chloride, 1-butyl-3-methyl imidazole chloride, 1-butyl-3-methyl imidazole bromide and tetraethylammonium bromide. In the method, the conversion rate of the ethylene oxide is close to 100%, and the selectivity of the target product ethylene glycol butyl ether is greater than or equal to 96%. After the reaction is completed, the catalyst is separated out from the system, can be separated and recovered through filtration and directly recycled, and no post-treatment procedures such as neutralization and water washing are needed, and no three wastes are generated. The application has the advantages of simple process, high conversion rate, good selectivity, recyclable catalyst, green environmental protection and the like, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, specifically to an efficient method for preparing ethylene glycol butyl ether. Background Technology

[0002] Ethylene glycol monobutyl ether (EGBE) is a fine chemical solvent possessing both lipophilic ether bonds and hydrophilic hydroxyl groups. It features strong dissolving power, moderate evaporation rate, and excellent compatibility, making it widely used in high-end coatings, electronic cleaning, precision inks, and organic synthesis extraction. Currently, industrially, EGBE is mainly synthesized from n-butanol and ethylene oxide via a catalytic ring-opening addition reaction. This raw material route is mature and represents a core production process commonly used in the industry.

[0003] In existing technologies, the preparation of ethylene glycol butyl ether mainly employs alkaline catalysts or Lewis acid catalysts. While homogeneous alkaline catalysts such as potassium hydroxide and sodium methoxide exhibit high catalytic activity, severe chain side reactions occur during the catalytic process, easily generating multiple addition byproducts such as diethylene glycol butyl ether and triethylene glycol butyl ether, resulting in low selectivity for the target product. Furthermore, because the catalyst is uniformly dissolved in the reaction system, separation requires neutralization, washing, and distillation after the reaction, leading to a long process flow, high energy consumption, and the generation of large amounts of saline organic wastewater. To address these issues, those skilled in the art have attempted to use solid alkaline catalysts. For example, Chinese patent CN101921180B discloses a method for synthesizing ethylene glycol butyl ether using supported potassium fluoride / alumina as a solid alkaline catalyst. This catalyst is insoluble in the reaction system and easily separated by filtration; however, the highest selectivity for the target product is only about 74%, and the catalyst requires complex processes such as high-temperature calcination.

[0004] In addition, although the selectivity of the addition reaction is improved compared with that of the base catalyst when using Lewis acid catalysts such as boron trifluoride diethyl ether complex, these catalysts are highly volatile and corrosive, which places strict requirements on the reaction equipment. Furthermore, the fluorine-containing impurities introduced after decomposition are difficult to completely remove from the product, affecting the purity of the product. At the same time, the conversion rate of ethylene oxide is low, making it difficult to achieve complete conversion.

[0005] It is evident that existing methods for preparing ethylene glycol butyl ether still suffer from the following shortcomings: on the one hand, homogeneous catalysts are difficult to separate and recover, resulting in cumbersome post-processing and significant waste generation; on the other hand, while heterogeneous solid base catalysts solve the separation problem, the selectivity of the target product remains unsatisfactory, and catalyst preparation is complex. Developing a preparation method that can achieve high conversion rates of ethylene oxide while maintaining high selectivity of the target product, and that allows for easy catalyst separation and reuse, remains a pressing technical problem to be solved in this field.

[0006] In view of this, the present invention provides an efficient method for preparing ethylene glycol butyl ether. Summary of the Invention

[0007] In view of this, the present invention provides a highly efficient method for preparing ethylene glycol butyl ether using a halogen salt as a catalyst. This method not only achieves a high conversion rate of nearly 100% for ethylene oxide, but also improves the selectivity of the target product ethylene glycol butyl ether to over 96%. Moreover, the entire process does not require post-treatment steps such as neutralization and water washing, and generates no waste. It is an environmentally friendly process route with good prospects for industrial application.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A highly efficient method for preparing ethylene glycol butyl ether, the method comprising the following steps: n-Butanol and catalyst were added to a reaction vessel, sealed, and ethylene oxide was added. The pressure was increased to 0.1-4 MPa by supplementing the system with nitrogen. The reaction was heated and stirred at 120-150°C for 4-24 hours. After the reaction was completed, the mixture was cooled to room temperature and the pressure was released to obtain crude ethylene glycol butyl ether. The catalyst is a halogen salt, selected from one or more of zinc bromide, zinc chloride, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, and tetraethylammonium bromide. The amount of the catalyst used is 0.2 wt% to 1.5 wt% of the total mass of the raw materials n-butanol and ethylene oxide. The molar ratio of n-butanol to ethylene oxide is 1.2:1 to 4:1; After the reaction is complete, the catalyst precipitates from the reaction system, is filtered and separated, and is directly reused in the next batch of reaction.

[0009] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses halogen salts as catalysts, preferably zinc bromide and / or zinc chloride. Such catalysts can efficiently catalyze the ring-opening addition reaction of n-butanol and ethylene oxide, with an ethylene oxide conversion rate of over 99% and a selectivity of over 96% for the target product ethylene glycol butyl ether. This is significantly better than the catalytic performance of existing solid base catalysts (with a maximum selectivity of about 74%) and heteropolyacid catalysts (with a maximum selectivity of about 75%), and effectively inhibits the formation of multiple addition byproducts.

[0010] (2) The catalyst used in this invention can precipitate from the system after the reaction. The catalyst and reaction products can be separated by simple filtration. The separated catalyst can be directly reused in the next batch of reaction without any treatment. As shown in the embodiments of this invention, after the catalyst is reused 5 times, there is no significant decrease in the conversion rate of ethylene oxide and the selectivity of ethylene glycol butyl ether. The catalyst has good stability and greatly reduces the cost of catalyst use.

[0011] (3) This invention does not require the use of traditional alkaline catalysts, avoids cumbersome post-treatment processes such as neutralization, water washing, and desalination, significantly shortens the process flow, requires less equipment investment, has low energy consumption, and generates no salty organic wastewater during the entire reaction process, making it an environmentally friendly green process.

[0012] (4) The present invention adopts a one-step addition reaction, in which n-butanol is used as both reactant and reaction medium. No additional organic solvent is required. The reaction path is short, the operation is simple, the conditions are mild (reaction temperature 120℃~150℃, pressure 0.1~4MPa), the production safety risk is low, and it is suitable for large-scale industrial production.

[0013] (5) After the reaction of the present invention is completed, the unreacted n-butanol raw material and the target product ethylene glycol butyl ether can be recovered by vacuum distillation. Excess n-butanol can be recycled, resulting in high raw material utilization and good economic efficiency. Attached Figure Description

[0014] Figure 1 This is a graph showing the analysis results of the product using gas chromatography-mass spectrometry (GC-MS) in Example 9 of the present invention.

[0015] Figure 2 This is a graph showing the relationship between the number of catalyst recycling cycles and the conversion rate of ethylene oxide and the selectivity of ethylene glycol butyl ether in Example 10 of the present invention. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. Unless otherwise specified, all reagents or instruments used in the embodiments of the present invention are commercially available conventional products.

[0017] In this embodiment of the invention, the product was analyzed using an Agilent gas chromatography-mass spectrometry (GC-MS) instrument, and the content of each substance in the product was calculated using the internal standard method. The n-butanol and ethylene glycol butyl ether standards were purchased from Maclean's Reagent Company.

[0018] Product separation method: After the reaction is completed, the crude product is filtered to separate the solid catalyst. The obtained catalyst is directly reused in the next batch of reaction without any treatment. The filtered liquid crude product is subjected to vacuum distillation at 1000 Pa. The unreacted n-butanol fraction is collected at 60 °C and the target product ethylene glycol butyl ether fraction is collected at 100 °C.

[0019] The calculation methods for ethylene oxide conversion and ethylene glycol butyl ether selectivity are as follows: Ethylene oxide conversion rate = (number of moles of reacted ethylene oxide / total number of moles of ethylene oxide fed) × 100%; ethylene glycol butyl ether selectivity = (moles of ethylene oxide consumed in the production of ethylene glycol butyl ether / total moles of ethylene oxide that have reacted) × 100%.

[0020] Example 1 8.9 g of n-butanol and 0.1 g of 1-butyl-3-methylimidazolium chloride were placed in a reaction vessel, sealed, and 4.4 g of ethylene oxide (molar ratio of n-butanol to ethylene oxide was 2:1) were added. The mixture was stirred at 500 rpm and heated to 120 °C. After reacting for 4 h, the mixture was cooled to room temperature to obtain crude ethylene glycol butyl ether. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the conversion rate of ethylene oxide was 90.2%, and the selectivity of the target product, ethylene glycol butyl ether, was 80.5%.

[0021] Example 2 11.2 g of n-butanol and 0.2 g of 1-butyl-3-methylimidazolium bromide were placed in a reaction vessel, sealed, and 4.4 g of ethylene oxide (molar ratio of n-butanol to ethylene oxide was 2.5:1) were added. The mixture was stirred at 500 rpm and heated to 120 °C. After reacting for 4 h, it was cooled to room temperature to obtain crude ethylene glycol butyl ether. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the conversion rate of ethylene oxide was 91.3%, and the selectivity of the target product, ethylene glycol butyl ether, was 81.4%.

[0022] Example 3 11.1 g of n-butanol and 0.2 g of tetraethylammonium bromide were placed in a reaction vessel, sealed, and 4.4 g of ethylene oxide (molar ratio of n-butanol to ethylene oxide was 2.5:1) were added. Nitrogen gas was introduced to supplement the pressure to 2 MPa, and the mixture was heated to 120 °C with stirring at 500 rpm. After reacting for 4 h, the mixture was cooled to room temperature and the pressure was released to obtain crude ethylene glycol butyl ether. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the conversion rate of ethylene oxide was 86.5%, and the selectivity for the target product, ethylene glycol butyl ether, was 82.7%.

[0023] Example 4 11.1 g of n-butanol and 0.2 g of zinc bromide were placed in a reaction vessel, sealed, and 4.4 g of ethylene oxide (molar ratio of n-butanol to ethylene oxide was 2.5:1) were added. Nitrogen gas was introduced to supplement the pressure to 2 MPa, and the mixture was heated to 120 °C with stirring at 600 rpm. After reacting for 5 h, the mixture was cooled to room temperature and the pressure was released to obtain crude ethylene glycol butyl ether. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the conversion rate of ethylene oxide was 90.5%, and the selectivity of the target product, ethylene glycol butyl ether, was 98.6%.

[0024] Example 5 14.8 g of n-butanol and 0.1 g of zinc bromide were placed in a reaction vessel, sealed, and 4.4 g of ethylene oxide (molar ratio of n-butanol to ethylene oxide was 3.3:1) were added. Nitrogen gas was introduced to supplement the pressure to 3 MPa, and the mixture was heated to 130 °C with stirring at 800 rpm. After reacting for 12 h, the mixture was cooled to room temperature and the pressure was released to obtain crude ethylene glycol butyl ether. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the conversion rate of ethylene oxide was 92.6%, and the selectivity of the target product, ethylene glycol butyl ether, was 98.3%.

[0025] Example 6 14.8 g of n-butanol and 0.1 g of zinc chloride were placed in a reaction vessel, sealed, and 4.4 g of ethylene oxide (molar ratio of n-butanol to ethylene oxide was 3.3:1) were added. Nitrogen gas was introduced to supplement the pressure to 4 MPa, and the mixture was heated to 130 °C with stirring at 800 rpm. After reacting for 15 h, the mixture was cooled to room temperature and the pressure was released to obtain crude ethylene glycol butyl ether. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the conversion rate of ethylene oxide was 98.2%, and the selectivity of the target product, ethylene glycol butyl ether, was 97.1%.

[0026] Example 7 74.2 g of n-butanol and 0.2 g of zinc chloride were placed in a reaction vessel, sealed, and 11.1 g of ethylene oxide (molar ratio of n-butanol to ethylene oxide was 4:1) was added. Nitrogen gas was introduced to supplement the pressure to 2 MPa, and the mixture was heated to 140 °C with stirring at 1000 rpm. After reacting for 24 h, the mixture was cooled to room temperature and the pressure was released to obtain crude ethylene glycol butyl ether. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the conversion rate of ethylene oxide was 99.9%, and the selectivity of the target product, ethylene glycol butyl ether, was 92.6%.

[0027] Example 8 74.1 g of n-butanol and 0.3 g of zinc chloride were placed in a reaction vessel, sealed, and 11.0 g of ethylene oxide (molar ratio of n-butanol to ethylene oxide was 4:1) was added. Nitrogen gas was introduced to supplement the pressure to 1 MPa, and the mixture was heated to 150 °C with stirring at 1000 rpm. After reacting for 18 h, the mixture was cooled to room temperature and the pressure was released to obtain crude ethylene glycol butyl ether. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the conversion rate of ethylene oxide was 97.5%, and the selectivity of the target product, ethylene glycol butyl ether, was 94.4%.

[0028] Example 9 74.1 g of n-butanol and 0.4 g of zinc chloride were placed in a reaction vessel, sealed, and 11.0 g of ethylene oxide (molar ratio of n-butanol to ethylene oxide was 4:1) was added. Nitrogen gas was introduced to supplement the pressure to 4 MPa, and the mixture was heated to 140 °C with stirring at 1000 rpm. After reacting for 20 h, the mixture was cooled to room temperature and the pressure was released to obtain crude ethylene glycol butyl ether. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the conversion rate of ethylene oxide was 99.9%, and the selectivity for the target product, ethylene glycol butyl ether, was 96.5%.

[0029] The gas chromatography-mass spectrometry (GC-MS) analysis results of the product in Example 9 are as follows: Figure 1 As shown in the figure, the peaks appearing at around 1 min represent the carrier gas, diluent solvent, and unreacted n-butanol; peak 1 with a retention time of 2.285 min represents the target product ethylene glycol butyl ether; and peak 2 with a retention time of 5.163 min represents the byproduct diethylene glycol butyl ether.

[0030] Table 1. Peak area and percentage of area for peaks 1 and 2 As shown in Table 1, the peak area of ​​the target product, ethylene glycol butyl ether, accounts for as high as 96.53%, while byproducts account for only 3.47%. This clearly demonstrates that the method of the present invention effectively suppresses multiple addition side reactions while ensuring a high conversion rate of ethylene oxide, thus achieving highly selective synthesis of the target ethylene glycol butyl ether.

[0031] Example 10 Catalyst recycling performance test: Ethylene glycol butyl ether was prepared according to the method in Example 9. After the reaction, the crude product was filtered to separate the zinc chloride catalyst. The obtained catalyst was reused directly in the next batch of reaction without any treatment, and was reused 5 times. The test results of the ethylene oxide conversion rate and ethylene glycol butyl ether selectivity of each batch are as follows: Figure 2 As shown, the horizontal axis represents the number of times the catalyst is recycled (from the 1st to the 5th time), the left vertical axis represents the ethylene oxide conversion rate (orange column), and the right vertical axis represents the ethylene glycol butyl ether selectivity (cyan column). Figure 2 It is clearly evident that after five consecutive reuses, the ethylene oxide conversion rate remains above 99%, and the selectivity of ethylene glycol butyl ether remains stably around 96%, with no significant decay observed in the numerical curves. This indicates that the halogen salt catalyst (such as zinc chloride) of this invention, after precipitation and filtration separation following the reaction, can be directly reused without any regeneration treatment and exhibits extremely excellent cycle stability, significantly reducing the catalyst cost for industrial applications.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A highly efficient method for preparing ethylene glycol butyl ether, characterized in that, The method includes the following steps: n-Butanol and catalyst were added to a reaction vessel, sealed, and ethylene oxide was added. The pressure was increased to 0.1-4 MPa by supplementing the system with nitrogen. The reaction was heated and stirred at 120-150°C for 4-24 hours. After the reaction was completed, the mixture was cooled to room temperature and the pressure was released to obtain crude ethylene glycol butyl ether. The catalyst is a halogen salt, selected from one or more of zinc bromide, zinc chloride, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, and tetraethylammonium bromide. The amount of the catalyst used is 0.2 wt% to 1.5 wt% of the total mass of the raw materials n-butanol and ethylene oxide. The molar ratio of n-butanol to ethylene oxide is 1.2:1 to 4:1; After the reaction is complete, the catalyst precipitates from the reaction system, is filtered and separated, and is directly reused in the next batch of reaction.

2. The preparation method according to claim 1, characterized in that, The catalyst is zinc bromide and / or zinc chloride.

3. The preparation method according to claim 1, characterized in that, The amount of catalyst used is 0.4 wt% of the total mass of the raw materials n-butanol and ethylene oxide.

4. The preparation method according to claim 1, characterized in that, The molar ratio of n-butanol to ethylene oxide is 4:

1.

5. The preparation method according to claim 1, characterized in that, The reaction temperature is 140°C, the system pressure supplied by nitrogen is 4 MPa, and the reaction time is 20 hours.

6. The preparation method according to claim 1, characterized in that, The reaction was carried out at a stirring rate of 500-1000 rpm.

7. The preparation method according to claim 1, characterized in that, The method further includes: filtering the crude ethylene glycol butyl ether product obtained after the reaction to separate the solid catalyst, and directly reusing the obtained catalyst for the recycling of ethylene glycol butyl ether without any treatment; the filtered crude product liquid is subjected to vacuum distillation to recover unreacted n-butanol and the target product ethylene glycol butyl ether, respectively.

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