A method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol

Abstract

The present invention relates to the technical field of organic matter purification and discloses a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol. The method first utilizes the azeotropic properties of carbon tetrachloride to separate the ethanol and a portion of the water by distillation, then separates and recovers the carbon tetrachloride and ethanol by extraction or freeze crystallization, and finally dehydrates the 1,3-butanediol aqueous solution to recover the 1,3-butanediol. The method utilizes simple azeotropic distillation, extraction, and freeze crystallization methods to achieve simple and efficient separation and recovery of 1,3-butanediol and ethanol at high purity, thereby enabling the recycling and reuse of industrial waste liquid containing 1,3-butanediol, saving production costs and reducing the degree of environmental pollution caused by industrial waste.

Description

Technical Field

[0001] The invention relates to the technical field of organic matter purification, in particular to a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol. Background Art

[0002] 1,3-Butanediol (1,3-BDO) is a colorless, viscous liquid organic compound soluble in water, ethanol, acetone, and other chemicals. 1,3-BDO has a wide range of uses, primarily in the preparation of polyester resins, polyurethane resins, and plasticizers. It is also used as a humidifier and softener for textiles, paper, and tobacco. Consequently, the production processes of numerous industries generate large amounts of 1,3-BDO wastewater containing impurities such as ethanol. This type of industrial wastewater is not microbially friendly and, if directly discharged into biochemical systems, can affect microorganisms and increase the environmental burden. Furthermore, the presence of large amounts of 1,3-BDO and ethanol in the wastewater, without effective methods for recycling and treating it, results in significant resource waste and increased production costs.

[0003] Therefore, there is an urgent need for a method for separating and purifying 1,3-butanediol in waste liquid. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, the separation and purification method comprising:

[0005] Step 1, adding carbon tetrachloride to the mixed aqueous solution of 1,3-butanediol and ethanol to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0006] Step 2, distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1 to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and 1,3-butanediol aqueous solution;

[0007] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0008] Step 4, subjecting the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 to freeze crystallization or extraction separation to separate carbon tetrachloride and ethanol;

[0009] Step 5: Dehydrating the 1,3-butanediol aqueous solution obtained in step 2 to obtain 1,3-butanediol.

[0010] Furthermore, in step 1, the amount of carbon tetrachloride added is 0.15-0.21 times the volume of the mixed aqueous solution of 1,3-butanediol and ethanol.

[0011] Furthermore, in step 2, the distillation temperature is 63-85°C.

[0012] Furthermore, in step 4, the extraction step includes: allowing the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 to stand and then separate the layers, and obtaining an ethanol-water solution and carbon tetrachloride after separation.

[0013] Furthermore, the ethanol-water solution is dehydrated to obtain ethanol.

[0014] Furthermore, in step 4, the freezing crystallization step includes: freezing the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 to obtain carbon tetrachloride crystals and ethanol-water solution.

[0015] Furthermore, the temperature of the freezing treatment is -30 to -15°C.

[0016] Furthermore, in step 5, the dehydration method is pervaporation membrane coupled dehydration or molecular sieve dehydration.

[0017] Compared with the prior art, the beneficial effects are:

[0018] The present invention provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol. The method first utilizes the azeotropic properties of carbon tetrachloride to separate ethanol and a portion of water by distillation, then utilizes extraction or freeze crystallization to separate and recover the carbon tetrachloride and ethanol, and finally dehydrates the 1,3-butanediol aqueous solution to recover 1,3-butanediol. The present invention utilizes simple azeotropic distillation, extraction, freeze crystallization, and other methods to achieve simple and efficient separation and recovery of 1,3-butanediol and ethanol with high purity, thereby enabling the recycling and reuse of industrial waste liquid containing 1,3-butanediol, saving production costs and reducing the degree of environmental pollution caused by industrial waste. DETAILED DESCRIPTION

[0019] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0020] Example 1

[0021] This embodiment provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, comprising:

[0022] Step 1: adding carbon tetrachloride to a mixed aqueous solution containing 88% 1,3-butanediol and 9% ethanol, wherein the amount of carbon tetrachloride added is 0.18 times the volume of the waste solvent, to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0023] Step 2, distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1, specifically at a distillation temperature of 85° C., to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and a 1,3-butanediol aqueous solution;

[0024] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in Step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0025] Step 4: extracting the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3, wherein the extraction step comprises: allowing the mixed solution containing ethanol, carbon tetrachloride and water to stand, separating the layers and obtaining an ethanol-water solution and carbon tetrachloride;

[0026] Step 5: The 1,3-butanediol aqueous solution obtained in step 2 is subjected to pervaporation membrane coupled dehydration, and the flow rate of the gas phase component of the pervaporation membrane is 3m 3 / h, to obtain 1,3-butanediol.

[0027] Step 6: Place the ethanol-water solution obtained in step 4 into a liquid molecular sieve deep dehydration device for dehydration to obtain anhydrous ethanol.

[0028] Example 2

[0029] This embodiment provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, comprising:

[0030] Step 1: adding carbon tetrachloride to a mixed aqueous solution containing 85% 1,3-butanediol and 10% ethanol, wherein the amount of carbon tetrachloride added is 0.2 times the volume of the waste solvent, to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0031] Step 2: distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1 at a specific distillation temperature of 63° C. to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and a 1,3-butanediol aqueous solution;

[0032] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in Step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0033] Step 4: freezing the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 at a temperature of -15°C to obtain carbon tetrachloride crystals and an ethanol-water solution;

[0034] Step 5: Place the 1,3-butanediol aqueous solution obtained in step 2 into a liquid molecular sieve deep dehydration device for dehydration to obtain 1,3-butanediol.

[0035] Step 6: Place the ethanol-water solution obtained in step 4 into a liquid molecular sieve deep dehydration device for dehydration to obtain anhydrous ethanol.

[0036] Example 3

[0037] This embodiment provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, comprising:

[0038] Step 1: adding carbon tetrachloride to a mixed aqueous solution containing 87% 1,3-butanediol and 10% ethanol, wherein the amount of carbon tetrachloride added is 0.16 times the volume of the waste solvent, to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0039] Step 2, distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1 at a specific distillation temperature of 76° C. to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and 1,3-butanediol aqueous solution;

[0040] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in Step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0041] Step 4: freezing the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 at a temperature of -23°C to obtain carbon tetrachloride crystals and an ethanol-water solution;

[0042] Step 5: The 1,3-butanediol aqueous solution obtained in step 2 is subjected to pervaporation membrane coupling dehydration, and the flow rate of the gas phase component of the pervaporation membrane is 1m 3 / h, to obtain 1,3-butanediol.

[0043] Step 6: Place the ethanol-water solution obtained in step 4 into a liquid molecular sieve deep dehydration device for dehydration to obtain anhydrous ethanol.

[0044] Example 4

[0045] This embodiment provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, comprising:

[0046] Step 1: adding carbon tetrachloride to a mixed aqueous solution containing 88% 1,3-butanediol and 8% ethanol, wherein the amount of carbon tetrachloride added is 0.17 times the volume of the waste solvent, to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0047] Step 2, distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1 at a specific distillation temperature of 78° C. to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and 1,3-butanediol aqueous solution;

[0048] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in Step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0049] Step 4: freezing the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 at a temperature of -30°C to obtain carbon tetrachloride crystals and an ethanol-water solution;

[0050] Step 5: Place the 1,3-butanediol aqueous solution obtained in step 2 into a liquid molecular sieve deep dehydration device for dehydration to obtain 1,3-butanediol.

[0051] Step 6: Place the ethanol-water solution obtained in step 4 into a liquid molecular sieve deep dehydration device for dehydration to obtain anhydrous ethanol.

[0052] Example 5

[0053] This embodiment provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, comprising:

[0054] Step 1, adding carbon tetrachloride to a mixed aqueous solution containing 8% 4,1,3-butanediol and 6% ethanol, wherein the amount of carbon tetrachloride added is 0.21 times the volume of the waste solvent, to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0055] Step 2, distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1, specifically at a distillation temperature of 65° C., to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and a 1,3-butanediol aqueous solution;

[0056] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in Step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0057] Step 4: extracting the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3, wherein the extraction step comprises: allowing the mixed solution containing ethanol, carbon tetrachloride and water to stand, separating the layers and obtaining an ethanol-water solution and carbon tetrachloride;

[0058] Step 5: The 1,3-butanediol aqueous solution obtained in step 2 is subjected to pervaporation membrane coupling dehydration, and the flow rate of the gas phase component of the pervaporation membrane is 2m 3 / h, to obtain 1,3-butanediol.

[0059] Step 6: Place the ethanol-water solution obtained in step 4 into a liquid molecular sieve deep dehydration device for dehydration to obtain anhydrous ethanol.

[0060] Example 6

[0061] This embodiment provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, comprising:

[0062] Step 1: adding carbon tetrachloride to a mixed aqueous solution containing 86% 1,3-butanediol and 9% ethanol, wherein the amount of carbon tetrachloride added is 0.15 times the volume of the waste solvent, to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0063] Step 2, distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1, specifically at a distillation temperature of 82° C., to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and a 1,3-butanediol aqueous solution;

[0064] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in Step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0065] Step 4: extracting the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3, wherein the extraction step comprises: allowing the mixed solution containing ethanol, carbon tetrachloride and water to stand, separating the layers and obtaining an ethanol-water solution and carbon tetrachloride;

[0066] Step 5: Place the 1,3-butanediol aqueous solution obtained in step 2 into a liquid molecular sieve deep dehydration device for dehydration to obtain 1,3-butanediol.

[0067] Step 6: Place the ethanol-water solution obtained in step 4 into a liquid molecular sieve deep dehydration device for dehydration to obtain anhydrous ethanol.

[0068] Comparative Example 1

[0069] This embodiment provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, comprising:

[0070] Step 1: adding carbon tetrachloride to a mixed aqueous solution containing 86% 1,3-butanediol and 9% ethanol, wherein the amount of carbon tetrachloride added is 0.15 times the volume of the waste solvent, to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0071] Step 2, distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1, specifically at a distillation temperature of 90° C., to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and a 1,3-butanediol aqueous solution;

[0072] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in Step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0073] Step 4: freezing the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 at a temperature of -5°C to obtain carbon tetrachloride crystals and an ethanol-water solution;

[0074] Step 5: The 1,3-butanediol aqueous solution obtained in step 2 is subjected to pervaporation membrane coupled dehydration, and the flow rate of the gas phase component of the pervaporation membrane is 0.1m 3 / h, to obtain 1,3-butanediol.

[0075] Step 6: Place the ethanol-water solution obtained in step 4 into a liquid molecular sieve deep dehydration device for dehydration to obtain anhydrous ethanol.

[0076] Comparative Example 2

[0077] This embodiment provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, comprising:

[0078] Step 1: adding carbon tetrachloride to a mixed aqueous solution containing 88% 1,3-butanediol and 9% ethanol, wherein the amount of carbon tetrachloride added is 0.18 times the volume of the waste solvent, to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0079] Step 2: distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1 at a specific distillation temperature of 100° C. to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and a 1,3-butanediol aqueous solution;

[0080] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in Step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0081] Step 4: extracting the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3, wherein the extraction step comprises: allowing the mixed solution containing ethanol, carbon tetrachloride and water to stand, separating the layers and obtaining an ethanol-water solution and carbon tetrachloride;

[0082] Step 5: The 1,3-butanediol aqueous solution obtained in step 2 is subjected to pervaporation membrane coupling dehydration, and the flow rate of the gas phase component of the pervaporation membrane is 0.5m 3 / h, to obtain 1,3-butanediol.

[0083] Step 6: Place the ethanol-water solution obtained in step 4 into a liquid molecular sieve deep dehydration device for dehydration to obtain anhydrous ethanol.

[0084] Comparative Example 3

[0085] This embodiment provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, comprising:

[0086] Step 1: adding carbon tetrachloride to a mixed aqueous solution containing 85% 1,3-butanediol and 10% ethanol, wherein the amount of carbon tetrachloride added is 0.2 times the volume of the waste solvent, to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0087] Step 2, distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1, specifically at a distillation temperature of 55° C., to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and a 1,3-butanediol aqueous solution;

[0088] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in Step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0089] Step 4: freezing the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 at a temperature of 0° C. to obtain carbon tetrachloride crystals and an ethanol-water solution;

[0090] Step 5: The 1,3-butanediol aqueous solution obtained in step 2 is subjected to pervaporation membrane coupled dehydration, and the flow rate of the gas phase component of the pervaporation membrane is 3m 3 / h, to obtain 1,3-butanediol.

[0091] Step 6: Place the ethanol-water solution obtained in step 4 into a liquid molecular sieve deep dehydration device for dehydration to obtain anhydrous ethanol.

[0092] Comparative Example 4

[0093] This embodiment provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, comprising:

[0094] Step 1, adding carbon tetrachloride to a mixed aqueous solution containing 8% 8 1,3-butanediol and 8% ethanol, wherein the amount of carbon tetrachloride added is 0.17 times the volume of the waste solvent, to obtain a mixed aqueous solution containing butanediol, ethanol and carbon tetrachloride;

[0095] Step 2, distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1, specifically at a distillation temperature of 45° C., to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water carbon tetrachloride azeotropic steam and a 1,3-butanediol aqueous solution;

[0096] Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water carbon tetrachloride azeotropic steam obtained in Step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water;

[0097] Step 4: extracting the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3, wherein the extraction step comprises: allowing the mixed solution containing ethanol, carbon tetrachloride and water to stand, separating the layers and obtaining an ethanol-water solution and carbon tetrachloride;

[0098] Step 5: The 1,3-butanediol aqueous solution obtained in step 2 is subjected to pervaporation membrane coupling dehydration, and the flow rate of the gas phase component of the pervaporation membrane is 1m 3 / h, to obtain 1,3-butanediol.

[0099] Step 6: Place the ethanol-water solution obtained in step 4 into a liquid molecular sieve deep dehydration device for dehydration to obtain anhydrous ethanol.

[0100] The technical indicators of the industrial grade 1,3-butanediol after purification in Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 1:

[0101] Table 1

[0102] name 1,3-Butanediol, (wt%) Moisture (wt%) Lead content, (wt%) Industrial-grade standards ≥99.0 ≤0.5 ≤0.0002 Example 1 99.5 0.2 0 Example 2 99.6 0.4 0 Example 3 99.5 0.5 0 Example 4 99.4 0.6 0 Example 5 99.4 0.6 0 Example 6 99.6 0.4 0 Comparative Example 1 98.1 1.9 0 Comparative Example 2 97.9 2.1 0 Comparative Example 3 97.5 2.5 0 Comparative Example 4 97.2 2.8 0

[0103] The technical indicators of the purified industrial-grade anhydrous ethanol of Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 2:

[0104] Table 2

[0105]

[0106]

[0107] In summary, the embodiment of the present invention provides a method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol. The method first utilizes the azeotropic properties of carbon tetrachloride to distill and separate ethanol and part of the water. Then, the carbon tetrachloride and ethanol are separated and recovered by extraction or freeze crystallization. Finally, the 1,3-butanediol aqueous solution is dehydrated to recover 1,3-butanediol.

[0108] The present invention utilizes simple azeotropic distillation, extraction, freezing crystallization and other methods to achieve simple and efficient separation and recovery of 1,3-butanediol and ethanol with high purity, realizes the recycling and reuse of industrial waste liquid containing 1,3-butanediol, saves production costs, and reduces the degree of environmental pollution caused by industrial waste.

[0109] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the solutions disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method section.

[0110] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for separating and purifying a mixed aqueous solution of 1,3-butanediol and ethanol, characterized in that: The separation and purification method comprises: Step 1, adding carbon tetrachloride to the mixed aqueous solution of 1,3-butanediol and ethanol to obtain a mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride; Step 2, distilling the mixed aqueous solution containing 1,3-butanediol, ethanol and carbon tetrachloride obtained in step 1 to obtain ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, ethanol-water-carbon tetrachloride azeotropic steam and 1,3-butanediol aqueous solution; Step 3, condensing the ethanol-carbon tetrachloride azeotropic steam, water-carbon tetrachloride azeotropic steam, and ethanol-water-carbon tetrachloride azeotropic steam obtained in step 2 to obtain a mixed solution containing ethanol, carbon tetrachloride and water; Step 4, subjecting the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 to freeze crystallization or extraction separation to separate carbon tetrachloride and ethanol; Step 5: dehydrating the 1,3-butanediol aqueous solution obtained in step 2 to obtain 1,3-butanediol; The amount of carbon tetrachloride added is 0.15-0.21 times the volume of the mixed aqueous solution of 1,3-butanediol and ethanol; The distillation temperature is 63-85°C; In step 4, the freeze crystallization step comprises: freezing the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 to obtain carbon tetrachloride crystals and an ethanol-water solution; The freezing temperature is -30 to -15°C; The dehydration method is pervaporation membrane coupled dehydration or molecular sieve dehydration; The flow rate of the gas phase component of the pervaporation membrane coupled dehydration is 1m 3 / h or 2m 3 / h or 3m 3 / h.

2. The separation and purification method according to claim 1, wherein In step 4, the extraction step comprises: allowing the mixed solution containing ethanol, carbon tetrachloride and water obtained in step 3 to stand and then separating the layers, and obtaining an ethanol-water solution and carbon tetrachloride after separation.

3. The separation and purification method according to claim 2, wherein The ethanol-water solution is dehydrated to obtain ethanol.

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