Process for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran

Abstract

The invention relates to a method for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran. The method comprises providing a first material of the mixture containing water, acetonitrile and 2-methyltetrahydrofuran, providing a fourth material of ethylene glycol, and sending the first material and the fourth material to an extractive distillation tower for treatment. The operating conditions of the extractive distillation tower are as follows: the number of plates is 60-65, the reflux ratio is 0.5-2, the tower top temperature is 55-60°C, the tower bottom temperature is 155-160°C, the tower top pressure is 50-55 kPa, the tower bottom pressure is 50-55 kPa, the first material is fed into the lower part of the extractive distillation tower, the fourth material is fed into the upper part of the extractive distillation tower, and a fifth material rich in 2-methyltetrahydrofuran is provided at the tower top of the extractive distillation tower. The method of the invention can separate a high-purity 2-methyltetrahydrofuran product from a mixture containing water, acetonitrile and 2-methyltetrahydrofuran, and the separated 2-methyltetrahydrofuran can be directly used in a drug production process, and has a high economic value.

Description

Technical Field

[0001] The present invention relates to a process for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran. Background Art

[0002] 2-Methyltetrahydrofuran is widely used in biogasoline fuel, pharmaceutical intermediates and high-end environmentally friendly solvents. At present, my country's demand for 2-methylfuran is in short supply, mainly from imports, and expensive; acetonitrile has excellent solvent properties, can dissolve a variety of organic, inorganic and gaseous substances, can undergo typical nitrile reactions, and is used to prepare many typical nitrogen-containing compounds. It is an important organic intermediate. In the pharmaceutical production industry, some drug production processes use 2-methyltetrahydrofuran and acetonitrile as solvents, thereby producing waste liquid containing 2-methyltetrahydrofuran, acetonitrile, and water. This system produces a variety of binary and ternary azeotropes, which are difficult to separate in ordinary distillation processes. Since 2-methyltetrahydrofuran and acetonitrile are of high value, if this waste liquid is directly incinerated, it will cause a lot of resource waste. Therefore, this patent recovers this waste liquid and can effectively extract the 2-methyltetrahydrofuran and acetonitrile organic solvents contained in the waste liquid. Summary of the invention

[0003] The main object of the present invention is to provide a method for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran.

[0004] In order to achieve the above object, the present invention provides a method for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran, comprising the steps of:

[0005] providing a first feed of the mixture comprising water, acetonitrile and 2-methyltetrahydrofuran, providing a fourth feed of ethylene glycol,

[0006] The first material and the fourth material are sent to an extractive distillation tower for treatment. The operating conditions of the extractive distillation tower are: the number of plates is 60-65, the reflux ratio is 0.5-2, the top temperature is 55-60°C, the bottom temperature is 155-160°C, the top pressure is 50-55kPa, the bottom pressure is 50-55kPa, the first material is fed to the lower part of the extractive distillation tower, the fourth material is fed to the upper part of the extractive distillation tower, and the top of the extractive distillation tower provides a fifth material rich in 2-methyltetrahydrofuran.

[0007] In some embodiments of the present invention, the mixture also contains heavy components, and the first material is sent to an evaporator for evaporation to remove the heavy components. The operating conditions of the evaporator are: temperature 75-80°C, pressure 101.3-110kPa. The evaporator provides a third material for removing the heavy components, and the third material contains water, acetonitrile and 2-methyltetrahydrofuran. The third material is sent to an extractive distillation tower for the treatment.

[0008] In some embodiments of the present invention, the mass percentage concentration of 2-methyltetrahydrofuran in the fifth material is ≥99.5%.

[0009] In some embodiments of the present invention, the operating conditions of the extractive distillation tower are: the number of plates is 60, the reflux ratio is 0.5, the top temperature is 58.6°C, the bottom temperature is 158.9°C, the top pressure is 50kPa, and the bottom pressure is 51kPa.

[0010] In some embodiments of the present invention, the steps are further included:

[0011] The bottom of the extractive distillation tower provides a sixth material containing ethylene glycol, acetonitrile and water.

[0012] The sixth material enters the extractant recovery tower for treatment. The operating conditions of the extractant recovery tower are: the number of plates is 40-45, the reflux ratio is 1-2, the top temperature is 40-45°C, the bottom temperature is 150-155°C, the top pressure is 25-30°C, and the bottom pressure is 25-30°C. The sixth material is fed into the middle of the extractant recovery tower, and the bottom of the extractant recovery tower provides an eighth material rich in ethylene glycol.

[0013] The eighth material is fed into an extractant storage device, and the extractant storage device provides the fourth material.

[0014] In some embodiments of the present invention, the mass percentage concentration of ethylene glycol in the eighth material is ≥99.9%.

[0015] In some embodiments of the present invention, the operating conditions of the extractant recovery tower are: the number of plates is 40, the reflux ratio is 1, the top temperature is 40.4°C, the bottom temperature is 154.1°C, the top pressure is 25°C, and the bottom pressure is 25.8°C.

[0016] In some embodiments of the present invention, the top of the extractant recovery tower provides a seventh material containing water and acetonitrile, and acetonitrile is recovered from the seventh material.

[0017] The method of the invention can separate a high-purity 2-methyltetrahydrofuran product from a mixture containing water, acetonitrile and 2-methyltetrahydrofuran, and the separated 2-methyltetrahydrofuran can be directly used in a drug production process, and has a high economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The following is a simplified flow chart of the recovery of 2-methyltetrahydrofuran in the embodiment. In the figure, (1) to (8) are the material numbers. DETAILED DESCRIPTION

[0019] In view of the fact that some existing pharmaceutical wastewaters contain 2-methyltetrahydrofuran, acetonitrile and water components that are difficult to separate, resulting in the problem that expensive 2-methyltetrahydrofuran cannot be recovered, the present invention provides a method for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran, which mainly comprises the following steps:

[0020] providing a first feed of the mixture comprising water, acetonitrile and 2-methyltetrahydrofuran, providing a fourth feed of ethylene glycol,

[0021] The first material and the fourth material are sent to an extractive distillation tower for treatment. The operating conditions of the extractive distillation tower are: the number of plates is 60-65, the reflux ratio is 0.5-2, the top temperature is 55-60°C, the bottom temperature is 155-160°C, the top pressure is 50-55kPa, the bottom pressure is 50-55kPa, the first material is fed to the lower part of the extractive distillation tower, the fourth material is fed to the upper part of the extractive distillation tower, and the top of the extractive distillation tower provides a fifth material rich in 2-methyltetrahydrofuran.

[0022] The method of the present invention can separate 2-methyltetrahydrofuran from acetonitrile and water, thereby recovering 2-methyltetrahydrofuran with high economic value from pharmaceutical waste water containing these components. The recovered 2-methyltetrahydrofuran has high purity (mass percentage concentration ≥99.5%) and can be directly used as a raw material for drug production.

[0023] The extractive distillation tower and the extractant recovery tower in the present invention both adopt existing structures and should be understood as including not only the tower body, but also related supporting equipment and instrument systems such as pumps, pipelines, valves, control systems, etc. configured for the distillation tower body in order to achieve distillation.

[0024] The various materials in the present invention can be transported by pipelines. The structure of the pipeline is known and should be understood as: including not only the pipe body itself, but also the corresponding pumps, valves, and control systems arranged on the pipeline. The temperature of the material can be adjusted by various heaters, heat exchangers and other equipment.

[0025] The evaporation device in the present invention can adopt a known evaporation device, including but not limited to an evaporation tank, an evaporation tower, etc.

[0026] The storage device in the present invention can adopt known storage devices, including but not limited to storage tanks, storage tanks, etc.

[0027] After knowing the process steps disclosed in the invention intent of the present invention, the extractive distillation tower, extractant recovery tower, storage device, evaporation device membrane, etc. in the present invention can be designed and manufactured according to known chemical design and manufacturing methods.

[0028] Unless otherwise specified, the contents in the present invention are all in mass percentage.

[0029] When the mixture contains heavy components, the first material can be sent to an evaporator to evaporate and remove the heavy components. The operating conditions of the evaporator are: temperature 75-80°C, pressure 101.3-110kPa, and the evaporator provides a third material for removing the heavy components. The third material contains water, acetonitrile and 2-methyltetrahydrofuran. The third material is sent to an extractive distillation tower for the above treatment. Through the evaporation method, the heavy components remain in the evaporator due to their high boiling point, while 2-methyltetrahydrofuran, acetonitrile and a small amount of water in the mixture are evaporated and sent to the extractive distillation tower for extractive distillation.

[0030] The bottom of the extractive distillation tower provides a sixth material containing ethylene glycol, acetonitrile and water. The sixth material can be selected to enter the extractant recovery tower for further treatment to recover ethylene glycol used as an extractant, and this step can also generate an acetonitrile aqueous solution at the top of the tower for easy preparation of acetonitrile products. The operating conditions of the extractant recovery tower are: the number of plates is 40-45, the reflux ratio is 1-2, the top temperature is 40-45°C, the bottom temperature is 150-155°C, the top pressure is 25-30°C, and the bottom pressure is 25-30°C. The sixth material is fed in the middle of the extractant recovery tower, and the bottom of the extractant recovery tower provides an eighth material rich in ethylene glycol. The eighth material is sent to the extractant storage device, and the extractant storage device provides the fourth material. The mass percentage concentration of ethylene glycol in the eighth material is ≥99.9%.

[0031] The top of the extractant recovery tower provides a seventh material containing water and acetonitrile, and acetonitrile is recovered from the seventh material. The recovery method is a known method, including but not limited to extractive distillation, pressure swing distillation or pervaporation membrane dehydration to recover a higher concentration of acetonitrile product.

[0032] The present invention is further described below in conjunction with specific embodiments.

[0033] The separation process of this embodiment can be referred to Figure 1, the material components and flow rates can be found in Table 1.

[0034] Table 1 Material composition and flow table

[0035]

[0036] Table 2 Specifications and operating parameters of each main device

[0037]

[0038] Combination Figure 1 , Table 1 and Table 2, the first material enters the evaporator for evaporation treatment, the first material is from external pharmaceutical wastewater, and its components are 2-methyltetrahydrofuran, acetonitrile, water and a small amount of heavy components. 2-methyltetrahydrofuran, acetonitrile and water in the pharmaceutical wastewater are evaporated to form a third material in the form of steam, and the heavy components are discharged from the bottom of the evaporator and disposed as hazardous waste. The extractant ethylene glycol in the extractant tank is used as the fourth material and is sent to the extractive distillation tower together with the third material for extractive distillation, wherein the feeding position of the fourth material is located at the upper part of the extractive distillation tower, and the feeding position of the third material is located at the lower part of the extractive distillation tower. In the extractive distillation tower, ethylene glycol transfers mass with the third material during the descending process, and the water and acetonitrile in the third material are absorbed by ethylene glycol and remain in the tower kettle. 2-methyltetrahydrofuran is discharged from the top of the extractive distillation tower as the fifth material, and the mass percentage concentration of 2-methyltetrahydrofuran in the fifth material is 99.9%. The ethylene glycol absorbs acetonitrile and water and is sent from the bottom of the extractive distillation tower as the sixth material to the middle of the extractant recovery tower. The top of the extractant recovery tower is the seventh material of acetonitrile and water, and the bottom of the tower is ethylene glycol with a mass percentage concentration of 99.9%, which is refluxed into the extractant tank as the eighth material and recycled as the extractant. The seventh material containing acetonitrile and water can be dehydrated by, for example, a pervaporation membrane to form a high-purity acetonitrile product.

[0039] Thus, through the above steps, 2-methyltetrahydrofuran and acetonitrile products with high economic value and high purity are obtained. In the whole process, ethylene glycol used as an extractant can be recovered and recycled, which effectively reduces the processing cost.

[0040] The embodiments of the present invention are only used to illustrate the present invention and do not constitute a limitation on the scope of the claims. Other substantially equivalent substitutes that can be thought of by those skilled in the art are all within the protection scope of the present invention.

Claims

1. A method for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran, characterized in that Includes steps: providing a first feed of the mixture comprising water, acetonitrile and 2-methyltetrahydrofuran, providing a fourth feed of ethylene glycol, The first material and the fourth material are sent to an extractive distillation tower for treatment. The operating conditions of the extractive distillation tower are: the number of plates is 60-65, the reflux ratio is 0.5-2, the top temperature is 55-60°C, the bottom temperature is 155-160°C, the top pressure is 50-55kPa, the bottom pressure is 50-55kPa, the first material is fed to the lower part of the extractive distillation tower, the fourth material is fed to the upper part of the extractive distillation tower, and the top of the extractive distillation tower provides a fifth material rich in 2-methyltetrahydrofuran.

2. The process for treating a mixture of water, acetonitrile and 2-methyltetrahydrofuran as claimed in claim 1, characterized in that The mixture also contains heavy components. The first material is sent to an evaporator for evaporation to remove the heavy components. The operating conditions of the evaporator are: temperature 75-80°C, pressure 101.3-110kPa. The evaporator provides a third material for removing the heavy components. The third material contains water, acetonitrile and 2-methyltetrahydrofuran. The third material is sent to an extractive distillation tower for the treatment.

3. The process for treating a mixture of water, acetonitrile and 2-methyltetrahydrofuran as claimed in claim 1, characterized in that The mass percentage concentration of 2-methyltetrahydrofuran in the fifth material is ≥99.5%.

4. The method for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran as claimed in claim 1, characterized in that The operating conditions of the extractive distillation tower are: the number of plates is 60, the reflux ratio is 0.5, the top temperature is 58.6°C, the bottom temperature is 158.9°C, the top pressure is 50kPa, and the bottom pressure is 51kPa.

5. The method for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran as claimed in claim 1, characterized in that Also includes the steps: The bottom of the extractive distillation tower provides a sixth material containing ethylene glycol, acetonitrile and water. The sixth material enters the extractant recovery tower for treatment. The operating conditions of the extractant recovery tower are: the number of plates is 40-50, the reflux ratio is 1-2, the top temperature is 40-45°C, the bottom temperature is 150-155°C, the top pressure is 25-30°C, and the bottom pressure is 25-30°C. The sixth material is fed into the middle of the extractant recovery tower, and the bottom of the extractant recovery tower provides an eighth material rich in ethylene glycol. The eighth material is fed into an extractant storage device, and the extractant storage device provides the fourth material.

6. The method for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran as claimed in claim 5, characterized in that The mass percentage concentration of ethylene glycol in the eighth material is ≥99.9%.

7. The method for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran as claimed in claim 5, characterized in that The operating conditions of the extractant recovery tower are: the number of plates is 40, the reflux ratio is 1, the top temperature is 40.4°C, the bottom temperature is 154.1°C, the top pressure is 25°C, and the bottom pressure is 25.8°C.

8. The method for treating a mixture containing water, acetonitrile and 2-methyltetrahydrofuran as claimed in claim 5, characterized in that The top of the extractant recovery tower provides a seventh material containing water and acetonitrile, and acetonitrile is recovered from the seventh material.

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