Separation and recovery device for mixture of 2-methyltetrahydrofuran, normal hexane and water

Abstract

The utility model relates to a separation and recovery device for a mixture of 2-methyltetrahydrofuran, n-hexane and water. The separation and recovery device comprises a rectifying tower, a water washing tower and membrane separation equipment, the tower top outlet of the rectifying tower is connected with the inlet of the water scrubber, the lower-layer water phase outlet of the water scrubber is connected with the feeding hole of the rectifying tower, and the tower kettle liquid outlet of the rectifying tower is connected with the membrane separation equipment. Preliminarily separating 2-methyltetrahydrofuran and n-hexane through a rectifying tower; washing a mixed solution of 2-methyltetrahydrofuran, n-hexane and water extracted from the top of the rectifying tower through a water washing tower, and separating n-hexane from 2-methyltetrahydrofuran; and 2-methyltetrahydrofuran and water are separated through membrane separation equipment. According to the separation and recovery device, 2-methyltetrahydrofuran, normal hexane and water can be efficiently separated and recovered without introducing a third-party component; the purity is higher, and waste liquid basically does not exist.

Description

Technical Field

[0001] The utility model relates to the field of chemical separation and purification, in particular to a device for separating and recovering a mixture of 2-methyltetrahydrofuran, n-hexane and water. Background Art

[0002] 2-Methyltetrahydrofuran (2-Methyltetrahydrofuran) is an important chemical synthesis intermediate and reaction solvent. It is primarily used in the synthesis of chloroquine phosphate, primaquine phosphate, and thiamine. It can replace tetrahydrofuran in organometallic reactions such as Grignard reactions and lithiation reactions. It is a versatile solvent used in a wide range of fields, including pharmaceuticals, synthetic fibers, and petrochemicals.

[0003] n-Hexane is a common organic solvent that is insoluble in water and is widely used in chemical organic synthesis.

[0004] Currently, a large amount of mixed aqueous solution of 2-methyltetrahydrofuran and n-hexane is produced in a certain reaction process. Since 2-methyltetrahydrofuran, n-hexane and water all form azeotropes with each other, it is difficult to separate the three by conventional distillation alone, thereby obtaining high-purity 2-methyltetrahydrofuran.

[0005] Existing Chinese patent CN201310089875.9 discloses the need to introduce a third component, using an N-substituted lactam compound as an extractant, to separate tetrahydrofuran and hexane. The extractant must be recovered in a separate column. However, there is no device for efficiently separating a mixture of 2-methyltetrahydrofuran, n-hexane, and water. Summary of the Invention

[0006] The utility model aims to provide a device for separating and recovering a mixture of 2-methyltetrahydrofuran, n-hexane and water, which has the advantages of not introducing a third component and obtaining 2-methyltetrahydrofuran and n-hexane with high purity.

[0007] In order to achieve the purpose of this utility model, the technical solutions are as follows:

[0008] A device for separating and recovering a mixture of 2-methyltetrahydrofuran, n-hexane and water comprises a distillation tower, a water washing tower and a membrane separation device; the top outlet of the distillation tower is connected to the inlet of the water washing tower, the lower water phase outlet of the water washing tower is connected to the feed inlet of the distillation tower, and the bottom liquid outlet of the distillation tower is connected to the membrane separation device.

[0009] Furthermore, the number of plates of the distillation tower is 50, and the feed inlet of the distillation tower is located in the middle of the tower.

[0010] Furthermore, the operating gauge pressure of the distillation tower is 0-0.1 mPa; the extraction temperature of the top of the distillation tower is 60-70°C, the reflux ratio is 0.5-5; and the bottom temperature of the distillation tower is 80-90°C.

[0011] Furthermore, the amount of water added to the water washing tower is 0.5-1 times the amount of the azeotrope extracted from the top of the distillation tower.

[0012] Furthermore, in the membrane separation device, the membrane material used is a liquid-phase permeable membrane, selected from one or a combination of any two or any three or more of a Na molecular sieve membrane, an organic polymer membrane, a hollow fiber membrane, and a composite membrane.

[0013] Furthermore, the membrane dehydration temperature of the membrane separation equipment is 80-90° C., and the operating gauge pressure is 0.01-0.1 mPa.

[0014] Furthermore, the mother liquor entering the distillation tower includes 75-85 wt.% of 2-methyltetrahydrofuran, 5-10 wt.% of n-hexane, and 10-15 wt.% of water.

[0015] Compared with the prior art, the present invention has the following significant advantages:

[0016] 1. Without introducing any third components, 2-methyltetrahydrofuran, n-hexane and water can be efficiently separated and recovered from the mixture solution through distillation and membrane dehydration alone;

[0017] 2. The recovered 2-methyltetrahydrofuran and n-hexane are of higher purity, with virtually no waste liquid; the removed water can also be directly discharged;

[0018] 3. This device has the characteristics of simple process, high separation efficiency, good safety and equipment stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The utility model is a schematic structural diagram of a device for separating and recovering a mixture of 2-methyltetrahydrofuran, n-hexane and water.

[0020] Among them, 1 is a distillation tower, 2 is a water washing tower, and 3 is a membrane separation equipment. DETAILED DESCRIPTION

[0021] The transportation of each material in this embodiment can be controlled by pipelines, pumps, valves, and control systems, and the temperature of the material can be adjusted by various heaters, heat exchangers, and other equipment.

[0022] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings.

[0023] A device for separating and recovering a mixture of 2-methyltetrahydrofuran, n-hexane, and water comprises: a distillation tower 1 for initially separating 2-methyltetrahydrofuran and n-hexane; a water scrubber 2 for scrubbing the mixture of 2-methyltetrahydrofuran, n-hexane, and water extracted from the top of the distillation tower to separate n-hexane from 2-methyltetrahydrofuran; and a membrane separation device 3 for separating 2-methyltetrahydrofuran and water in a liquid phase. Furthermore, the top outlet of the distillation tower 1 is connected to the inlet of the water scrubber 2, the lower aqueous phase outlet of the water scrubber is connected to the feed inlet of the distillation tower 1, and the bottom liquid outlet of the distillation tower 1 is connected to the membrane separation device 3.

[0024] The mother liquor entering the distillation tower 1 includes the following composition: 75-85 wt.% of 2-methyltetrahydrofuran, 5-10 wt.% of n-hexane, and 10-15 wt.% of water.

[0025] The distillation tower 1 has 50 theoretical plates and can be a plate tower or a packed tower. The feed inlet of the distillation tower 1 is located in the middle of the tower. As a specific embodiment, the feed inlet of the distillation tower 1 is located on the 20th tray from the bottom. The operating pressure is 0-0.1 mPa (gauge pressure); the top temperature is 60-70°C, the reflux ratio is 0.5-5, and the bottom temperature is 80-90°C.

[0026] The azeotropic mixture extracted from the top of the distillation tower 1 comprises 5-15 wt.% of 2-methyltetrahydrofuran, 80-90 wt.% of n-hexane, and 5-15 wt.% of water. The 2-methyltetrahydrofuran and water mixture extracted from the bottom of the distillation tower 1 comprises 80-90 wt.% of 2-methyltetrahydrofuran, and 10-30 wt.% of water.

[0027] In water scrubber 2, the amount of water added during the water wash is 0.5-1 times the amount of the azeotrope removed from the top of the tower. Water scrubber 2 operates at room temperature. After the water wash and stratification in water scrubber 2, the upper layer consists of n-hexane and the lower layer consists of 2-methyltetrahydrofuran and water. The upper layer comprises ≥98 wt.% n-hexane and 0.01-1 wt.% 2-methyltetrahydrofuran. The lower layer comprises 60-40 wt.% 2-methyltetrahydrofuran and 40-60 wt.% water.

[0028] The membrane material used in membrane separation device 3 is a liquid-phase permeable membrane, such as one or a combination of any two or more of a Na molecular sieve membrane, an organic polymer membrane, a hollow fiber membrane, or a composite membrane. Membrane separation device 3 uses liquid-phase dehydration to reduce energy consumption. The membrane dehydration temperature is 80-90°C and the pressure is 0.01-0.1 mPa (gauge pressure).

[0029] like Figure 1 As shown, the process flow of the device is specifically described:

[0030] Step 1: The mother liquor is transferred to distillation tower 1 and subjected to atmospheric distillation at an operating pressure of 0-0.1 mPa (gauge pressure); the top temperature is 60-70°C, the reflux ratio is 0.5-5, and the bottom temperature is 80-90°C. The azeotrope of n-hexane, 2-methyltetrahydrofuran, and water is collected from the top of the tower and sent to water wash tank 2.

[0031] Step 2: The azeotrope of n-hexane, 2-methyltetrahydrofuran and water extracted from the top of the distillation tower 1 enters the water washing tower 2 for water washing and stratification, wherein the 2-methyltetrahydrofuran is dissolved in the lower aqueous phase and separated from the n-hexane in the upper layer; the upper layer obtains a qualified n-hexane product with a n-hexane content of ≥98wt.%, 2-methyltetrahydrofuran 0.01-1wt.%, and water 0.01-1wt.%.

[0032] Step 3: The lower aqueous phase obtained in the washing tower 2 (composed of 60-40 wt.% 2-methyltetrahydrofuran and 40-60 wt.% water) is transported to the distillation tower 1. When the n-hexane content in the overhead fraction of the distillation tower 1 is less than 0.1 wt.%, the bottom liquid of the distillation tower 1 enters the membrane separation device 3 for dehydration, separating the 2-methyltetrahydrofuran and water. The membrane separation device 3 uses a membrane to separate the 2-methyltetrahydrofuran and water, obtaining anhydrous 2-methyltetrahydrofuran product, and the water is discharged from the permeate side. The 2-methyltetrahydrofuran content obtained in the membrane separation device 3 is ≥99.9%, and the water content is ≤0.1%. The 2-methyltetrahydrofuran content in the permeate is ≤1%, and the water content is ≥99%, thereby obtaining high-purity 2-methyltetrahydrofuran.

[0033] The device can separate 2-methyltetrahydrofuran and n-hexane from water in the mother liquor, respectively, to obtain 99.9 wt.% of 2-methyltetrahydrofuran product and more than 98 wt.% of n-hexane product, and the yield of 2-methyltetrahydrofuran can reach more than 97%.

[0034] The distillation tower in this embodiment includes not only the tower body, but also related supporting equipment and instrumentation systems such as pumps, pipelines, valves, and control systems configured for the distillation tower body to achieve distillation. For example, an online meter can be installed at the top of the distillation tower to facilitate the detection of its n-hexane content.

Claims

1. A device for separating and recovering a mixture of 2-methyltetrahydrofuran, n-hexane and water, characterized in that: The separation and recovery device comprises a distillation tower (1), a water washing tower (2) and a membrane separation device (3); the top outlet of the distillation tower (1) is connected to the inlet of the water washing tower (2), the lower water phase outlet of the water washing tower is connected to the feed inlet of the distillation tower (1), and the bottom liquid outlet of the distillation tower (1) is connected to the membrane separation device (3).

2. The device for separating and recovering a mixture of 2-methyltetrahydrofuran, normal hexane and water according to claim 1, wherein: The number of plates of the distillation tower (1) is 50, and the feed inlet of the distillation tower (1) is located in the middle of the tower.

3. The device for separating and recovering a mixture of 2-methyltetrahydrofuran, normal hexane and water according to claim 1 or 2, characterized in that: The operating gauge pressure of the distillation tower (1) is 0-0.1 mPa; the top temperature of the distillation tower (1) is 60-70°C, the reflux ratio is 0.5-5; and the bottom temperature of the distillation tower (1) is 80-90°C.

4. The device for separating and recovering a mixture of 2-methyltetrahydrofuran, normal hexane and water according to claim 1, wherein: The amount of water added to the water washing tower (2) is 0.5-1 times the amount of the azeotropic product taken out from the top of the distillation tower (1).

5. The device for separating and recovering a mixture of 2-methyltetrahydrofuran, normal hexane and water according to claim 1, wherein: In the membrane separation device (3), the membrane material used is a liquid phase water permeable membrane, which is selected from one or any two or any three of a Na molecular sieve membrane, an organic polymer membrane, and a hollow fiber membrane.

6. The device for separating and recovering a mixture of 2-methyltetrahydrofuran, normal hexane and water according to claim 5, wherein: The membrane dehydration temperature of the membrane separation device (3) is 80-90°C, and the operating gauge pressure is 0.01-0.1 mPa.

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