A method for removing odor impurities from 1,2-hexanediol

Abstract

The present invention proposes a method for removing odor impurities from 1,2-hexanediol, and belongs to the field of purification technology. The method for removing odor impurities from 1,2-hexanediol comprises the following steps: 1) mixing 1,2-hexanediol and an entrainer to obtain a mixed material; the entrainer is one or more of pure water, methanol, ethanol, n-propanol, isopropanol and n-butanol; 2) transferring the obtained mixed material to an azeotropic distillation tower for azeotropic distillation, extracting an azeotrope of the entrainer and odor impurities at the top of the tower, and obtaining the deodorized 1,2-hexanediol in the tower bottom. The method provided by the present invention does not involve chemical reactions, and has a short production process, generates less solid waste, and has a high purity of the purified 1,2-hexanediol product.

Description

Technical Field

[0001] The invention belongs to the technical field of purification, and in particular relates to a method for removing odor impurities in 1,2-hexanediol. Background Art

[0002] As an important fine chemical product, 1,2-hexanediol is widely used in high-end cosmetics, pharmaceutical preparations, and advanced inks because of its good mutual solubility, molecular stability, and good bactericidal and moisturizing properties. In recent years, with the rapid development of the high-end cosmetics market, the demand for 1,2-hexanediol has also developed rapidly, based on its characteristics of moisturizing and antiseptic properties, and its lack of irritation to human skin. At present, the 1,2-hexanediol produced domestically has a pungent smell of traditional Chinese medicine and can only be used in the field of low-end cosmetics. The 1,2-hexanediol produced in countries such as Japan and South Korea has a higher purity and lower odor, and has formed a technical monopoly in the field of high-end cosmetics. The price is about 3 times that of domestic 1,2-hexanediol. Therefore, it is of vital importance to develop a domestic low-odor hexanediol purification process to break the foreign technology monopoly.

[0003] Patent KR102038445 provides a method for producing odorless, high-purity 1,2-hexanediol. The patent removes odors through multi-stage deodorization to improve product purity. Although the product obtained by this process is odorless and high in purity, the process flow is cumbersome, and the energy consumption is high, and there are more three wastes. Patent CN112778085 A discloses a purification method, which uses metal borohydride to treat the crude product of 1,2-hexanediol, and then distills it under reduced pressure to obtain a 1,2-hexanediol product with a purity of 99.5%, which has very low odor or no Chinese medicine odor. However, this process involves chemical reduction reactions, which has a high risk factor and high equipment requirements, and the sample processing time is long and the yield is low. Summary of the invention

[0004] The invention provides a method for removing odor impurities in 1,2-hexanediol. The method provided by the invention does not involve chemical reaction, has a short production process, generates less solid waste, and the purified 1,2-hexanediol product has high purity.

[0005] In order to achieve the above object, the present invention provides a method for removing odor impurities in 1,2-hexanediol, comprising the following steps: 1) mixing 1,2-hexanediol and an azeotropic agent to obtain a mixed material; the azeotropic agent is one or more of pure water, methanol, ethanol, n-propanol, isopropanol and n-butanol; 2) The obtained mixed material is transferred to an azeotropic distillation tower for azeotropic distillation, and the azeotropic product of the entrainer and the odor impurities is extracted at the top of the tower, and the deodorized 1,2-hexanediol is obtained in the bottom of the tower; The odor impurities include butyl ethylene oxide and n-valeraldehyde.

[0006] Preferably, the azeotropic agent in step 1) is pure water, n-propanol, n-butanol, a mixture of pure water and ethanol, a mixture of pure water and isopropanol, or a mixture of pure water and n-butanol.

[0007] Preferably, the azeotropic agent in step 1) is pure water; the amount of pure water added is 0.1-2% of the mass of 1,2-hexanediol.

[0008] Preferably, the azeotropic agent in step 1) is n-propanol; the amount of n-propanol added is 0.5-0.55% of the mass of 1,2-hexanediol.

[0009] Preferably, the entrainer in step 1) is a mixture of pure water and n-butanol; the mass ratio of pure water to n-butanol is 1:1; and the added amount of the entrainer is 0.1-0.15% of the mass of 1,2-hexanediol.

[0010] Preferably, the entrainer in step 1) is a mixture of a mixture of pure water and ethanol; the mass ratio of the mixture of pure water and ethanol is 1:1; and the entrainer is 0.2-0.25% of the mass of 1,2-hexanediol.

[0011] When the entrainer in step 1) is n-butanol, the amount of n-butanol added is 0.3-0.5% of the mass of 1,2-hexanediol.

[0012] Preferably, the step 2) further comprises heating the mixed material to 40-60° C. before transferring the mixed material into the azeotropic distillation tower.

[0013] Preferably, in step 2), the bottom temperature of the tower is controlled at 100-160°C, the reflux ratio is 1-5:1, and the top distillation temperature is 30-85°C.

[0014] Preferably, in step 2), the number of plates of the azeotropic distillation tower is 2 to 15; and the operating pressure is 0.01 to 0.05 MPa.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are: The method for removing odor impurities from 1,2-hexanediol provided by the present invention selects a suitable entrainer and the odor impurities in 1,2-hexanediol to form a low azeotrope, and the impurities and the entrainer are completely extracted from the top of the distillation tower by adjusting the azeotropic distillation process. The 1,2-hexanediol after distillation purification has low odor and high product purity. In addition, the process does not involve chemical reactions, simplifies the purification processes such as distillation de-lightening and de-heaving, and has the advantages of short production process, less solid waste generation, and high product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a detection diagram of odor impurities in 1,2-hexanediol; Figure 2 This is a gas phase test result diagram of 1,2-hexanediol after deodorization in Example 6. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The present invention provides a method for removing odor impurities in 1,2-hexanediol, comprising the following steps: 1) mixing 1,2-hexanediol and an azeotropic agent to obtain a mixed material; The azeotropic agent is one or more of pure water, methanol, ethanol, n-propanol, isopropanol and n-butanol; 2) The obtained mixed material is transferred to an azeotropic distillation tower for azeotropic distillation, and the azeotropic product of the entrainer and the odor impurities is extracted at the top of the tower, and the deodorized 1,2-hexanediol is obtained in the bottom of the tower.

[0019] In the present invention, the odor impurities include butyl ethylene oxide and n-valeraldehyde, and the headspace quality analysis results are as follows: Figure 1 shown.

[0020] The present invention mixes 1,2-hexanediol and an entrainer to obtain a mixed material. In the present invention, the entrainer is one or more of pure water, methanol, ethanol, n-propanol, n-propanol, isopropanol and n-butanol, preferably pure water, n-butanol, a mixture of pure water and ethanol, a mixture of pure water and isopropanol, a mixture of pure water and n-butanol, and more preferably a mixture of pure water and n-butanol. In the present invention, when the entrainer is preferably pure water, the addition amount of the pure water is preferably 0.1-2% of the mass of 1,2-hexanediol. When the entrainer is preferably n-propanol, the addition amount of the n-propanol is preferably 0.5-0.55% of the mass of 1,2-hexanediol. When the entrainer is preferably a mixture of pure water and n-butanol, the mass ratio of the pure water to n-butanol is preferably 1:1; the addition amount of the entrainer is preferably 0.1-0.15% of the mass of 1,2-hexanediol. When the entrainer is preferably a mixture of pure water and ethanol, the mass ratio of pure water to ethanol is preferably 1:1, and the amount of the entrainer added is preferably 0.2-0.25% of the mass of 1,2-hexanediol. When the entrainer is preferably n-butanol, the amount of n-butanol added is preferably 0.3-0.5% of the mass of 1,2-hexanediol.

[0021] In the present invention, the pure water refers to ultra-clean deionized water, water with a metal ion content of less than 10 ppm.

[0022] After obtaining the mixed material, the present invention transfers the obtained mixed material into an azeotropic distillation tower for azeotropic distillation, extracts the azeotrope of the entrainer and the odor impurities at the top of the tower, and obtains the deodorized 1,2-hexanediol in the bottom of the tower. In the present invention, before transferring the mixed material into the azeotropic distillation tower, it is preferred that the mixed material is heated to 40-60°C. In the present invention, the mixed material is first stirred and heated and then transferred into the azeotropic distillation tower to better mix the materials evenly, so that the odor impurities and the entrainer form intermolecular forces, thereby improving the extraction effect of the odor impurities.

[0023] In the present invention, it is preferred to adopt a continuous feeding or intermittent feeding mode for feeding. Among them, intermittent distillation is a one-time feeding followed by distillation without continuous feeding.

[0024] In the present invention, when azeotropic distillation is performed, preferably the bottom temperature is 100-160°C, the reflux ratio is 1-5:1, and the top distillation temperature is 30-85°C.

[0025] In the present invention, the number of plates of the azeotropic distillation tower is 2 to 15; and the operating pressure is 0.01 to 0.05 MPa.

[0026] The method for removing odor impurities from 1,2-hexanediol provided by the present invention selects a suitable entrainer and the odor impurities in 1,2-hexanediol to form a low azeotrope, and the impurities and the entrainer are completely extracted from the top of the distillation tower by adjusting the azeotropic distillation process. The 1,2-hexanediol after distillation purification has low odor and high product purity. In addition, the process does not involve chemical reactions, simplifies the purification processes such as distillation de-lightening and de-heaving, and has the advantages of short production process, less solid waste generation, and high product quality.

[0027] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0028] Example 1 3 g of entrainer pure water and 3000 g of 1,2-hexanediol with a purity of 99.5% were mixed and stirred evenly, and then the mixture was heated to 40°C and continuously fed from the middle section of the distillation tower (there are 10 plates, and feed from the 5th plate). The operating pressure was controlled to be 0.01Mpa, the bottom temperature to be 150°C, the reflux ratio to be 2:1, the top distillation temperature to be 50°C, the entrainer and odor impurities to be completely extracted, and the deodorized 1,2-hexanediol was finally obtained in the bottom of the tower.

[0029] Example 2 15 g of azeotropic pure water and 3000 g of 1,2-hexanediol with a purity of 99.5% were mixed and stirred evenly, and then the mixture was heated to 40°C and intermittently fed from the middle section of the distillation tower (there are 10 plates, and feed is made from the 5th plate). The operating pressure was controlled to be 0.01Mpa, the bottom temperature to be 150°C, the reflux ratio to be 5:1, and the top distillation temperature to be 50°C. The azeotropic agent and odor impurities were all extracted, and the deodorized 1,2-hexanediol was finally obtained in the bottom of the tower.

[0030] Example 3 60 g of azeotropic pure water and 3000 g of 1,2-hexanediol with a purity of 99.5% were mixed and stirred evenly, and then the mixture was heated to 60°C and continuously fed from the middle section of the distillation tower (there are 10 plates, and feed from the 7th plate). The operating pressure was controlled to be 0.05 MPa, the bottom temperature to be 150°C, the reflux ratio to be 5:1, and the top distillation temperature to be 50°C. The azeotropic agent and odor impurities were all extracted, and the deodorized 1,2-hexanediol was finally obtained in the bottom of the tower.

[0031] Example 4 15 g of entrainer n-propanol and 3000 g of 1,2-hexanediol with a purity of 99.5% were mixed and stirred evenly, and then the mixture was heated to 40°C and continuously fed from the middle section of the distillation tower (there are 10 plates, and feed from the 5th plate). The operating pressure was controlled to be 0.01Mpa, the bottom temperature to be 100°C, the reflux ratio to be 1:1, and the top distillation temperature to be 66°C. The entrainer and odor impurities were completely extracted, and the deodorized 1,2-hexanediol was finally obtained in the bottom of the tower.

[0032] Example 5 9 g of azeotroping agent n-butanol and 3000 g of 1,2-hexanediol with a purity of 99.5% were mixed and stirred evenly, and then the mixture was heated to 40°C and intermittently fed from the middle section of the distillation tower (there are 10 plates, and feed is made from the 5th plate). The operating pressure was controlled to be 0.01 MPa, the bottom temperature to be 160°C, the reflux ratio to be 2:1, the top distillation temperature to be 71°C, the azeotroping agent and odor impurities were all extracted, and the deodorized 1,2-hexanediol was finally obtained in the bottom of the tower.

[0033] Example 6 3 g of entrainer (the entrainer is a mixture of n-butanol and water, and the mass ratio of n-butanol to water is 1:1) and 3000 g of 1,2-hexanediol with a purity of 99.5% are mixed and stirred evenly, and then the mixed material is heated to 40°C, and intermittently fed from the middle section of the distillation tower (the number of plates is 10, and the feed is fed from the second plate), the operating pressure is controlled to be 0.02Mpa, the bottom temperature is 160°C, the reflux ratio is 2:1, and the top distillation temperature is 67°C. The entrainer and odor impurities are all extracted, and the deodorized 1,2-hexanediol is finally obtained in the bottom of the tower. The gas phase test results are shown in Figure 2 .

[0034] Comparative Example 1 The difference from Example 6 is that no entrainer is added, and the other operation methods are exactly the same as those of Example 6. The specific operations are as follows: 3000 g of 1,2-hexanediol with a purity of 99.5% was heated to 40°C and intermittently fed from the middle section of the distillation tower (there were 10 plates, and the feed was fed from the second plate). The operating pressure was controlled at 0.02 MPa, the bottom temperature was 160°C, the reflux ratio was 2:1, the top distillation temperature was 67°C, the odor impurities were extracted from the top of the tower, and the deodorized 1,2-hexanediol was finally obtained in the bottom of the tower.

[0035] Comparative Example 2 1,2-hexanediol with a purity of 99.5% was transferred from the top of the stripping tower at 0.6 kg / h, and water vapor was introduced from the bottom of the stripping tower at 0.6 kg / h for stripping. The operating pressure was controlled at 0.01 MPa, the bottom temperature was 150°C, the reflux ratio was 2:1, the top distillation temperature was 20°C, the odor impurities were extracted from the top of the tower, and the deodorized 1,2-hexanediol was finally obtained in the bottom of the tower.

[0036] Performance Testing The purity of the purified 1,2-hexanediol in Examples 1 to 6 and Comparative Examples 1 to 2 was tested by gas chromatography. The specific results are shown in Table 1.

[0037] Table 1

[0038] As can be seen from Table 1, the entrainer selected in the present application forms a low azeotrope with the odor impurities, and the impurities and the entrainer are completely extracted from the top of the tower. The purity of 1,2-hexanediol in the bottom of the tower after distillation and purification is significantly higher than that in the comparative example. Although the high-pressure steam entrainment method in Comparative Example 2 can effectively remove most of the impurities in the product, the high-pressure steam is not in sufficient contact with the odor impurities, and the impurities cannot be completely removed. The 1,2-hexanediol still has an odor, and the purity of the product obtained is lower than that of the present application.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for removing odor impurities from 1,2-hexanediol, characterized in that: The steps include: 1) mixing 1,2-hexanediol and an azeotropic agent to obtain a mixed material; The azeotropic agent is one or more of pure water, methanol, ethanol, n-propanol, isopropanol and n-butanol; 2) The obtained mixed material is transferred to an azeotropic distillation tower for azeotropic distillation, and the azeotropic product of the entrainer and the odor impurities is extracted at the top of the tower, and the deodorized 1,2-hexanediol is obtained in the bottom of the tower; The odor impurities include butyl ethylene oxide and n-valeraldehyde.

2. The method according to claim 1, characterized in that The azeotropic agent in step 1) is pure water, n-propanol, n-butanol, a mixture of pure water and ethanol, a mixture of pure water and isopropanol, and a mixture of pure water and n-butanol.

3. The method according to claim 2, characterized in that In step 1), the azeotropic agent is pure water; the amount of pure water added is 0.1-2% of the mass of 1,2-hexanediol.

4. The method according to claim 2, characterized in that: In step 1), the entrainer is n-propanol; the amount of n-propanol added is 0.5-0.55% of the mass of 1,2-hexanediol.

5. The method according to claim 2, characterized in that: In step 1), the entrainer is a mixture of pure water and n-butanol; the mass ratio of pure water to n-butanol is 1:1; and the amount of the entrainer added is 0.1-0.15% of the mass of 1,2-hexanediol.

6. The method according to claim 2, characterized in that In step 1), the entrainer is a mixture of a mixture of pure water and ethanol; the mass ratio of the mixture of pure water and ethanol is 1:1; and the entrainer is 0.2-0.25% of the mass of 1,2-hexanediol.

7. The method according to claim 2, characterized in that When the entrainer in step 1) is n-butanol, the amount of n-butanol added is 0.3-0.5% of the mass of 1,2-hexanediol.

8. The method according to claim 1, characterized in that In step 2), the mixed material is heated to 40-60° C. before being transferred into the azeotropic distillation tower.

9. The method according to claim 1, characterized in that: In step 2), the bottom temperature of the tower is controlled at 100-160°C, the reflux ratio is 1-5:1, and the top distillation temperature is 30-85°C.

10. The method according to claim 1, characterized in that In step 2), the number of plates of the azeotropic distillation tower is 2 to 15; and the operating pressure is 0.01 to 0.05 MPa.

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