Preparation method of reagent-grade diethyl ether

Abstract

The invention relates to the field of diethyl ether purification, and particularly discloses a preparation method of reagent-grade diethyl ether. The preparation method comprises the following steps: heating the top temperature of an extraction tower at 30-40 DEG C and the kettle temperature at 95-105 DEG C until the internal pressure of the extraction tower is 0.2-0.3 MPa by virtue of steam, introducing vapor-phase crude ether with the diethyl ether content of 90-95% into the extraction tower, adding an ethylene glycol extraction agent into the middle upper part of the extraction tower, and rectifying the vapor-phase crude ether and the ethylene glycol extraction agent by virtue of vapor-liquid mass transfer, so as to obtain the reagent-grade diethyl ether. And condensing the extracted vapor-phase component, taking 30-40% of condensate as tower top reflux, extracting the rest of condensate, further cooling to 20 + / -5 DEG C, and sealing and storing to obtain the reagent-grade diethyl ether. The preparation method of the reagent-grade diethyl ether has the advantage of purifying industrial-grade diethyl ether to reagent-grade high purity, and the purification method is simple, environment-friendly and high in reagent utilization rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of diethyl ether purification, more particularly, it relates to a preparation method of reagent-grade diethyl ether. BACKGROUND

[0002] Diethyl ether is a colorless, transparent, volatile liquid with a special odor. It belongs to the ether class of compounds, and its boiling point is relatively low at normal temperature and pressure, about 34.5°C, which makes it have strong volatility at room temperature. Diethyl ether is slightly soluble in water and can be miscible with various organic solvents such as ethanol, benzene, chloroform, etc. in any proportion. This good solubility makes it widely used as a solvent in many chemical reactions and industrial processes.

[0003] The discovery of diethyl ether can be traced back to the 16th century, but its true application value was gradually discovered in the 19th century. In the medical field, diethyl ether was initially used as an anesthetic, making it possible for surgical operations to proceed smoothly, greatly promoting the development of surgical techniques and reducing the pain and mortality of surgical patients.

[0004] In the chemical industry, with the development of organic chemistry, diethyl ether began to play an important role in various chemical reactions as an excellent solvent and organic synthesis intermediate. It participates in the synthesis of many organic compounds, such as in the preparation of some ester and ether compounds, diethyl ether can be used as a reaction solvent or participate in the reaction to form new chemical bonds, promoting the progress of organic synthesis chemistry and laying the foundation for the industrial production of numerous organic chemicals.

[0005] In existing diethyl ether preparation technology, ethanol and concentrated sulfuric acid are usually used as raw materials. Under the action of concentrated sulfuric acid, ethanol is dehydrated to form diethyl ether, while other side reactions such as the dehydration of ethanol molecules to form ethylene also occur. The occurrence of side reactions reduces the yield of diethyl ether, and the by-products generated may form azeotropes with diethyl ether, increasing the difficulty of separation and purification. SUMMARY

[0006] In order to solve the problems of insufficient purity and difficult separation and purification of diethyl ether in the prior art, the present application provides a preparation method of reagent-grade diethyl ether.

[0007] The preparation method of reagent-grade diethyl ether provided by the present application adopts the following technical scheme: A preparation method of reagent-grade diethyl ether, comprising the following steps: The top temperature of the extraction column is 30-40℃, the kettle temperature is 95-105℃, the extraction column is heated by steam to an internal pressure of 0.2-0.3MPa, the vapor-phase crude ether with an ether content of 90-95% is introduced into the extraction column, the glycol extractant is added to the upper part of the extraction column, the vapor-phase crude ether and the glycol extractant are rectified through vapor-liquid mass transfer, and after the vapor-phase components after extraction are condensed, 30-40% of the condensate is used as the column top reflux, the remaining condensate is taken out and further cooled to 20±5℃ for sealed storage to obtain reagent-grade ether.

[0008] By adopting the above technical solution, the top temperature of the extraction column is set to 30-40℃, the kettle temperature is 95-105℃, and the internal pressure is 0.2-0.3MPa. In this temperature range, the vapor-phase crude ether and the glycol extractant can maintain a suitable vapor-liquid equilibrium state, which is conducive to the effective separation of ether and other impurities through vapor-liquid mass transfer. The control of pressure also has an important influence on the mass transfer rate and separation efficiency. A suitable pressure range ensures that the difference in volatility of each component can be fully utilized, thereby improving the purification effect of ether, so that the final ether product with reagent-grade purity can be obtained. 30-40% of the condensate is used as the column top reflux, and the remaining condensate is taken out and cooled for storage. A reasonable reflux ratio can maintain stable mass transfer and energy balance in the extraction column, ensure the continuous and efficient rectification process, and continuously purify the rising vapor phase, thereby improving the purity of the ether product taken out from the top of the column, while also taking into account the production efficiency, avoiding the increase in energy consumption and the reduction in yield caused by excessive reflux.

[0009] Optionally, the flow rate of the glycol extractant in the extraction column is 120-150kg / h, and the temperature of the glycol extractant is 45-55℃.

[0010] By adopting the above technical solution, the flow rate and temperature parameters can ensure that the extractant is in full contact and mass transfer with the vapor-phase crude ether in the extraction column. A suitable flow rate ensures that there is enough extractant to absorb the impurities in the crude ether, and a suitable temperature helps to maintain the stability of the physical and chemical properties of the extractant, so that the selective separation effect of the extractant on ether and impurities is optimal, further improving the purity of ether, and also ensuring the stability and reliability of the entire rectification process.

[0011] Optionally, the vapor-phase components after extraction are successively condensed by 20-25℃ circulating water, 0-5℃ low-temperature water, and-5-0℃ condensers.

[0012] By adopting the above technical scheme, the multi-stage condensation mode can gradually reduce the vapor phase temperature, and more finely realize the condensation separation of different components according to the boiling point difference of each component. The higher temperature circulating water first condenses out the part of impurities and part of ethyl ether with higher boiling point, then the low-temperature water further condenses out the remaining most of ethyl ether, and finally the low-temperature condenser ensures that almost all the ethyl ether is condensed, reducing the loss of ethyl ether in the tail gas, improving the recovery rate and purity of the product, and at the same time helping to keep the impurities in the uncondensed tail gas as much as possible, facilitating subsequent tail gas treatment.

[0013] Optionally, the uncondensed organic tail gas in the extraction tower is subjected to tail gas absorption by ethanol.

[0014] By adopting the above technical scheme, the uncondensed organic tail gas in the extraction tower is subjected to tail gas absorption by ethanol, effectively preventing the emission of organic components such as ethyl ether into the environment, causing pollution and waste. Ethanol has good absorption capacity for organic matter such as ethyl ether in the tail gas, and part of the ethyl ether can be recovered through tail gas absorption, improving the raw material utilization rate of the entire process, while also meeting environmental protection requirements, reducing the emission of volatile organic compounds (VOCs), and reducing the impact on the environment during production.

[0015] Optionally, the components of the kettle liquid in the extraction tower include ethylene glycol and water, and the kettle liquid is subjected to vacuum distillation to separate ethylene glycol, and the separated ethylene glycol is added back to the extraction tower as an extractant.

[0016] By adopting the above technical scheme, the components of the kettle liquid in the extraction tower include ethylene glycol and water, and the kettle liquid is subjected to vacuum distillation to separate ethylene glycol, and the separated ethylene glycol is added back to the extraction tower as an extractant. This realizes the recycling of the extractant, which not only reduces the production cost and reduces the amount of fresh extractant used, but also helps to maintain the stability and repeatability of the extraction process, thereby facilitating the continuous and stable production of high-purity ethyl ether products, because the recycled ethylene glycol has already undergone mass transfer with crude ether in the previous process, and its impurity content is relatively stable and low.

[0017] Optionally, the step of vacuum distillation of the kettle liquid includes: The kettle liquid is delivered to a container with an internal gas pressure of -0.09 to -0.1 MPa and a temperature of 105 to 110℃, and the kettle liquid flow rate is 10 to 20 kg / h.

[0018] By adopting the technical scheme, the vacuum distillation of the kettle liquid can realize effective separation of the glycol and water under vacuum condition according to the boiling point difference between the glycol and water. The lower pressure reduces the boiling point of the glycol, so that the glycol can be vaporized and separated at a relatively low temperature, avoiding problems such as decomposition or deterioration of the glycol caused by high temperature. Meanwhile, the appropriate flow rate of the kettle liquid ensures smooth progress of the distillation process, improves the recovery purity and recovery rate of the glycol, and makes the recovered glycol better meet the requirements of being used as an extractant for recycling, further ensuring the stability of the ether preparation process and the purity of the product.

[0019] Optionally, tail gas generated by the vacuum distillation of the kettle liquid is condensed and recovered by 0-5 DEG C low-temperature water and -5-0 DEG C condensers in sequence.

[0020] By adopting the technical scheme, the tail gas generated by the vacuum distillation of the kettle liquid is condensed and recovered by 0-5 DEG C low-temperature water and -5-0 DEG C condensers in sequence. Similar to the condensation principle of the previous vapor phase components, the multi-stage condensation can maximize the recovery of the glycol and other possible organic components in the tail gas. This not only reduces material loss and improves the economic benefit of the entire process, but also prevents the emission of these organic components into the environment. Meanwhile, the recovered materials can be returned to the process after appropriate treatment, which helps to maintain the material balance and purity stability of the entire system, further improving the resource utilization rate and environmental friendliness of the ether preparation process.

[0021] Optionally, the vapor phase components in the tail gas generated by the vacuum distillation of the kettle liquid are absorbed by ethanol.

[0022] By adopting the technical scheme, the vapor phase components in the tail gas generated by the vacuum distillation of the kettle liquid are absorbed by ethanol, which further emphasizes the treatment of the organic components in the tail gas that are not condensed. Even after the previous condensation step, there may still be a small amount of volatile organic matter in the tail gas. By absorbing the tail gas with ethanol, the emission of these organic substances can be further reduced, improving the environmental performance of the entire process. At the same time, a small amount of useful components such as ether may also be recovered. Although the amount is relatively small, from the perspective of the entire process, it helps to further improve the raw material utilization rate and product purity, perfecting the tail gas treatment link of the entire ether preparation process, and ensuring that the entire production process is more green and efficient.

[0023] In summary, the present application has the following advantages: 1. Due to the precise control of the temperature, pressure, and flow rate of the raw materials and extractants of the extraction tower in the present application, combined with the optimized vapor-liquid mass transfer rectification process and multi-stage condensation system, impurities in the vapor phase crude ether can be effectively removed, and ether products with a purity of reagent grade can be produced, meeting the requirements of high-demand application scenarios.

[0024] 2、The application realizes the recycling of ethylene glycol extractant and the recycling of useful components in the kettle liquid and tail gas, reducing the consumption of raw materials and the discharge of waste. This not only reduces the production cost, but also improves the resource utilization of the whole process, enhances the sustainability and economy of the process.

[0025] 3、The method of the application comprehensively treats the uncondensed organic tail gas, including by ethanol absorption and the like, effectively reducing the emission of volatile organic compounds (VOCs) to the environment, reducing the pollution of the production process to the atmospheric environment, meeting the requirements of modern environmental protection production, and achieving balanced development of economic benefits and environmental benefits. DETAILED DESCRIPTION

[0026] The application will be further described in detail below in conjunction with examples, and it is particularly pointed out that: in the following examples, the specific conditions are not specified, and the conventional conditions or the conditions recommended by the manufacturer are used, and the raw materials used in the following examples can be obtained from ordinary market sales unless otherwise specified. EXAMPLE

[0027] Example 1 A preparation method of reagent-grade diethyl ether: The industrial-grade diethyl ether with a content of 90-95% is heated to a vapor phase state.

[0028] Prepare ethylene glycol with a purity of >98% as an extractant, start the steam heating system, and keep the internal pressure of the extraction tower at 0.2-0.3 MPa. Introduce the vapor-phase crude ether into the bottom of the extraction tower at a flow rate of 50 kg / h through a flow control device, so that the crude ether flows upward in the tower, and maintain the top temperature of the extraction tower at 30-40°C and the kettle temperature at 95-105°C for stable operation.

[0029] At the upper part of the extraction tower, add ethylene glycol extractant at a temperature of 50°C at a flow rate of 130 kg / h, so that the extractant and the rising vapor-phase crude ether form countercurrent contact, ensuring that the extractant can effectively interact with the impurities in the crude ether, and realizing the preliminary purification of diethyl ether by utilizing the solubility difference of various components in ethylene glycol.

[0030] The vapor-phase components after extraction rectification are discharged from the top of the extraction tower and enter the condensation system. The vapor-phase components are condensed by a circulating water condenser at 20-25°C, so that part of the impurities with higher boiling points and part of the diethyl ether are condensed into liquid, and the vapor-liquid separation is initially realized. Then, the uncondensed gas enters a low-temperature water condenser at 0-5°C, further reduces the gas temperature, and condenses more diethyl ether and part of the lower volatile impurities. Finally, the remaining gas enters a condenser at -5-0°C for deep condensation.

[0031] The condensed liquid is collected in a reflux tank, and through liquid level control and flow regulation device, 35% of the condensed liquid is sent back to the top of the extraction tower as the tower top reflux liquid at a stable flow rate, to maintain the material balance and concentration distribution in the tower.

[0032] The remaining 65% of the condensed liquid is extracted as a product and transported by pipeline to a product cooler. In the product cooler, the ether product is further cooled to 20±5°C using a refrigerant, and the extracted product is sampled and analyzed for purity, impurity content, etc. The ether meeting the purity requirements is sealed in a container, and the ether not meeting the requirements is re-heated and vaporized into the extraction tower.

[0033] During the extraction process, the kettle liquid in the extraction tower is extracted into a vacuum container, the components of the kettle liquid include ethylene glycol and water, the internal pressure of the container is maintained at -0.09--0.1 MPa, the temperature is 105-110°C, the kettle liquid flow rate is 15 kg / h, the kettle liquid is subjected to vacuum distillation to separate ethylene glycol, and the separated anhydrous ethylene glycol is re-added to the extraction tower. The uncondensed organic tail gas discharged from the condensing system contains a small amount of ether and other volatile organic compounds, which is introduced into a tail gas absorption device. In the tail gas absorption device, ethanol is used as an absorbent, the tail gas is fully contacted with the ethanol by bubbling absorption, and the ether and other organic compounds in the tail gas are absorbed by the ethanol due to its good solubility, thereby reducing the emission of organic pollutants.

[0034] Example 2 A method for preparing reagent-grade ether, which is different from example 1 in that the ethylene glycol extractant at a temperature of 50°C is uniformly added to the upper part of the extraction tower at a flow rate of 120 kg / h.

[0035] Example 3 A method for preparing reagent-grade ether, which is different from example 1 in that the ethylene glycol extractant at a temperature of 50°C is uniformly added to the upper part of the extraction tower at a flow rate of 150 kg / h.

[0036] Example 4 A method for preparing reagent-grade ether, which is different from example 1 in that the ethylene glycol extractant at a temperature of 50°C is uniformly added to the upper part of the extraction tower at a flow rate of 110 kg / h.

[0037] Example 5 A method for preparing reagent-grade ether, which is different from example 1 in that the ethylene glycol extractant at a temperature of 50°C is uniformly added to the upper part of the extraction tower at a flow rate of 160 kg / h.

[0038] Example 6 A method for preparing reagent grade diethyl ether: the difference from Example 1 is that the glycol extractant at a temperature of 30°C is added to the upper part of the extraction column.

[0039] Example 7 A method for preparing reagent grade diethyl ether: the difference from Example 1 is that the glycol extractant at a temperature of 60°C is added to the upper part of the extraction column.

[0040] Example 8 A method for preparing reagent grade diethyl ether: the difference from Example 1 is that the vapor phase component after extraction is condensed in turn by circulating water at 20-25°C and low-temperature water at 0-5°C.

[0041] Example 9 A method for preparing reagent grade diethyl ether: the difference from Example 1 is that the vapor phase component after extraction is condensed by circulating water at 20-25°C.

[0042] Comparative Example Comparative Example 1 A method for preparing reagent grade diethyl ether: the difference from Example 1 is that the condensate in the extraction column is not split, but directly output as the product.

[0043] Comparative Example 2 A method for preparing reagent grade diethyl ether: the difference from Example 1 is that the top temperature of the extraction column is 20-30°C, and the kettle temperature is 85-95°C.

[0044] Comparative Example 3 A method for preparing reagent grade diethyl ether: the difference from Example 1 is that the top temperature of the extraction column is 40-50°C, and the kettle temperature is 105-115°C.

[0045] Performance detection test Detection method The diethyl ether samples were injected into a gas chromatograph to determine the purity of the diethyl ether products prepared in the examples and comparative examples.

[0046] Table 1 detection data Purity (%) Example 1 99.84 Example 2 99.55 Example 3 99.78 Example 4 98.71 Example 5 99.54 Example 6 97.65 Example 7 98.72 Example 8 99.70 Example 9 99.51 Comparative Example 1 98.73 Comparative Example 2 97.47 Comparative Example 3 98.90 From the data in Table 1, it can be seen that the purity of the diethyl ether product obtained in Example 1 is 99.84%, and that of Comparative Example 1 is 98.73%. This shows that the splitting operation of the condensed liquid helps to improve the purity of the diethyl ether product. By recycling part of the condensed liquid, the stable mass transfer and concentration distribution in the extraction column can be maintained, the ascending vapor phase is continuously purified, and thus the purity of the product taken from the top of the column is improved. This shows that a reasonable reflux ratio design plays an important role in improving the quality of the product in the preparation process of diethyl ether.

[0047] From the data in Table 1, it can be seen that the purity of the diethyl ether product obtained in Example 1 is 99.84%, and that of Comparative Example 1 is 98.73%. This shows that the splitting operation of the condensed liquid helps to improve the purity of the diethyl ether product. By recycling part of the condensed liquid, the stable mass transfer and concentration distribution in the extraction column can be maintained, the ascending vapor phase is continuously purified, and thus the purity of the product taken from the top of the column is improved. This shows that a reasonable reflux ratio design plays an important role in improving the quality of the product in the preparation process of diethyl ether.

[0048] From the data in Table 1, it can be seen that the purity of the diethyl ether product obtained in Example 1 is 99.84%, and that of Comparative Example 1 is 98.73%. This shows that the splitting operation of the condensed liquid helps to improve the purity of the diethyl ether product. By recycling part of the condensed liquid, the stable mass transfer and concentration distribution in the extraction column can be maintained, the ascending vapor phase is continuously purified, and thus the purity of the product taken from the top of the column is improved. This shows that a reasonable reflux ratio design plays an important role in improving the quality of the product in the preparation process of diethyl ether.

[0049] As can be seen from Example 1 and Examples 6-7 and Table 1, when the temperature of the ethylene glycol extractant is low, the molecular movement is relatively inactive, and the mass transfer rate between the vapor phase crude ether and the extractant will be slow. In the vapor-liquid mass transfer process, the extractant needs to be in full contact with the crude ether to separate the impurities and purify the diethyl ether by using the difference in solubility of each component. Lower temperature makes it difficult for such a mass transfer process to proceed quickly and fully, resulting in the need for longer time or larger column space to achieve the same separation effect, increasing equipment cost and production cycle. As the temperature rises, the solubility and selectivity of ethylene glycol to diethyl ether and impurities will change. This leads to a decrease in selectivity for impurities, i.e. not only are impurities more easily dissolved in ethylene glycol, but the solubility of diethyl ether in ethylene glycol also increases, making it difficult to separate diethyl ether and impurities completely in the subsequent vapor-liquid separation and condensation process, thereby affecting the purity of diethyl ether and making it difficult to meet the requirements of reagent grade standards.

[0050] As can be seen from Example 1 and Examples 8-9 and Table 1, the vapor phase components after extraction in Example 1 are sequentially condensed by 20-25℃ circulating water, 0-5℃ low-temperature water, and -5-0℃ condenser, the vapor phase components in Example 6 are sequentially condensed by 20-25℃ circulating water and 0-5℃ low-temperature water, and the vapor phase components in Example 7 are only condensed by 20-25℃ circulating water. The corresponding product purity is Example 1 (99.84%), Example 6 (99.30%), and Example 7 (98.91%). This shows that the degree of perfection of the condensation step has an impact on the purity of diethyl ether. The multi-stage condensation and stepwise reduction of condensation temperature can more finely achieve the condensation and separation of different components according to the boiling point difference of each component, reduce the residual impurities in the diethyl ether product, and improve the product purity.

[0051] The specific embodiments are merely illustrative of the present application, and are not intended to limit the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, and such modifications are within the scope of the present application as long as they are within the scope of the claims of the present application.

Claims

1. A process for the preparation of reagent grade diethyl ether, characterized in that, The method comprises the following steps: The top temperature of the extraction tower is 30-40℃, and the kettle temperature is 95-105℃. The extraction tower is heated by steam to an internal pressure of 0.2-0.3 MPa. Vapor-phase crude ether with an ether content of 90-95% is introduced into the extraction tower. Ethylene glycol extractant is added to the upper part of the extraction tower. The vapor-phase crude ether and the ethylene glycol extractant are rectified through vapor-liquid mass transfer. After extraction, the vapor-phase components are condensed. 30-40% of the condensate is used as the tower top reflux. The remaining condensate is collected and further cooled to 20±5℃ for sealed storage to obtain reagent-grade ether.

2. The process for the preparation of reagent grade diethyl ether as claimed in claim 1, wherein: The flow rate of the ethylene glycol extractant in the extraction tower is 120-150 kg / h, and the temperature of the ethylene glycol extractant is 45-55℃.

3. The process for the preparation of reagent grade diethyl ether as claimed in claim 1 wherein: The vapor-phase components after extraction are sequentially condensed by 20-25℃ circulating water, 0-5℃ low-temperature water, and a -5-0℃ condenser.

4. The process for the preparation of reagent grade diethyl ether as claimed in claim 3, wherein: The organic tail gas in the extraction tower that is not condensed is absorbed by ethanol.

5. The process for the preparation of reagent grade diethyl ether as claimed in claim 1 wherein: The components of the kettle liquid in the extraction tower include ethylene glycol and water. The kettle liquid is subjected to vacuum distillation to separate the ethylene glycol. The separated ethylene glycol is added back to the extraction tower as an extractant.

6. The process for the preparation of reagent grade diethyl ether as claimed in claim 5, wherein: The step of vacuum distillation of the kettle liquid comprises: The kettle liquid is delivered to a container with an internal gas pressure of -0.09--0.1 MPa and a temperature of 105-110℃. The flow rate of the kettle liquid is 10-20 kg / h.

7. The process for the preparation of reagent grade diethyl ether as claimed in claim 5 wherein: The tail gas generated by the vacuum distillation of the kettle liquid is sequentially condensed and recovered by 0-5℃ low-temperature water and a -5-0℃ condenser.

8. The process for the preparation of reagent grade diethyl ether as claimed in claim 7, wherein: The vapor-phase components of the tail gas generated by the vacuum distillation of the kettle liquid that are not condensed are absorbed by ethanol.