Purification method of 1, 2-hexanediol

Abstract

The invention discloses a purification method of 1, 2-hexanediol, and belongs to the technical field of product refining and purification. According to the technical scheme, the method comprises the following steps: 1) mixing a 1, 2-hexanediol crude product with water, transferring the obtained mixture into a rectifying tower, controlling the temperature in the tower to be 60-100 DEG C and the pressure at the top of the tower to be 4.5-5.5 KPa, and rectifying until water in the mixture is removed; 2) after the water in the mixture is completely removed, adjusting the temperature in the rectifying tower to be 120-130 DEG C, the tower top temperature to be 45-75 DEG C, the tower top pressure to be 0.2-0.8 KPa and the reflux ratio to be (1-6): (4-1), continuing rectifying, and collecting fractions; the invention discloses a method for purifying 1, 2-hexanediol from 1, 2-hexanediol, which comprises the following steps of: 1) purifying 1, 2-hexanediol, 2) purifying 1, 2-hexanediol, 3) mixing the fraction with activated carbon for adsorption deodorization to obtain 1, 2-hexanediol after adsorption treatment, and 4) purging the 1, 2-hexanediol after adsorption treatment with nitrogen to obtain purified 1, 2-hexanediol. The method provided by the invention can deeply, efficiently and stably remove peculiar smell impurities in 1, 2-hexanediol.

Description

Technical Field

[0001] This invention belongs to the field of product purification technology, and particularly relates to a purification method for 1,2-hexanediol. Background Technology

[0002] 1,2-Hexanediol is an important chemical raw material and cosmetic additive, widely used for its moisturizing and mild preservative properties. However, in industrial production processes, 1,2-Hexanediol products often contain residual byproducts such as aldehydes, ketones, unsaturated hydrocarbons, and small-molecule organic acids. These impurities give 1,2-Hexanediol an unpleasant odor, such as a "medicinal" smell, a "fermented" smell, or a "rubbery" smell.

[0003] In existing technologies, the purification of glycols often employs conventional distillation. However, this method may suffer from incomplete deodorization, degradation of heat-sensitive substances leading to new odors, and the risk of oxidation. Patent CN120904015A discloses a method for purifying propylene glycol, which involves adsorption with activated carbon, followed by deodorization with a deodorizing agent, and finally distillation. However, this method is not suitable for hexanediol. Adsorption of crude hexanediol with activated carbon produces a sour odor that is difficult to remove during subsequent distillation. Therefore, developing a purification method that can deeply, efficiently, and stably remove odor impurities from 1,2-hexanediol and prevent secondary contamination is of great significance for improving its product grade and application value. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a purification method for 1,2-hexanediol. The purification method provided by this invention can achieve a purity of ≥99.8% for 1,2-hexanediol products and effectively remove the odor of 1,2-hexanediol, meeting the application needs of high-end fields such as cosmetics and pharmaceuticals. It also has advantages such as stable process, simple operation, and environmental friendliness.

[0005] To address the aforementioned technical problem, this invention proposes a method for purifying 1,2-hexanediol, comprising the following steps: 1) Mix crude 1,2-hexanediol with water, and transfer the resulting mixture into a distillation column. Control the temperature inside the column at 60-100℃ and the pressure at the top of the column at 4.5-5.5 KPa for distillation until the water in the mixture is removed. 2) After the water in the mixture has been completely removed, adjust the temperature inside the distillation column to 120-130℃, the temperature at the top of the column to 45-75℃, the pressure at the top of the column to 0.2-0.8KPa, and the reflux ratio to 1-6:4-1 to continue distillation and collect the distillate; 3) The fraction is mixed with activated carbon for adsorption and deodorization to obtain 1,2-hexanediol after adsorption treatment; 4) The 1,2-hexanediol after adsorption treatment was purged with nitrogen gas to obtain purified 1,2-hexanediol; In step 2), the 38wt%-42wt% of material distilled first is taken as the fore fraction, and the remaining fraction is the main fraction. The fore fraction and the main fraction are collected separately and mixed with activated carbon for adsorption and deodorization. The amount of activated carbon added to the fore fraction is 5-8‰ of the mass of the fore fraction, and the amount of activated carbon added to the main fraction is 1-4‰ of the mass of the main fraction.

[0006] Preferably, the mass ratio of crude 1,2-hexanediol to water in step 1) is 1:1-4.

[0007] Preferably, the activated carbon in step 3) is modified activated carbon; the modified activated carbon is prepared using the following steps: a. Soak the activated carbon in an acid solution, wash it until it is neutral, and then dry it to obtain dry activated carbon; b. Activate the dry activated carbon in a nitrogen atmosphere to obtain modified activated carbon.

[0008] Preferably, the acid solution in step a is a 5-10 wt% hydrochloric acid solution, and the soaking time is 2-3 hours.

[0009] Preferably, the activation temperature in step b is 400-500℃ and the time is 2-3 hours.

[0010] Preferably, in step 3), stirring is performed during the adsorption process, and the stirring speed is 200-500 r / min.

[0011] Preferably, the adsorption temperature is 30-40℃ and the adsorption time is 2-10h.

[0012] Preferably, during purging in step 4), the purity of nitrogen is ≥99.9wt%, continuous bubbling is performed, the purging time is 2-12h, and the pressure inside the tube is maintained at 0.1-0.15MPa.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The purification method for 1,2-hexanediol provided by this invention involves sequentially adding water for distillation, activated carbon adsorption, and nitrogen purging, thereby effectively removing impurities from 1,2-hexanediol and completing odor removal to obtain purified 1,2-hexanediol. The purified 1,2-hexanediol has a purity ≥99.8% and an odor level ≤1, solving the problems of poor effect and insufficient purity of traditional single odor removal methods, and can meet the application needs of high-end fields such as cosmetics and pharmaceuticals.

[0014] The purification method provided by this invention has advantages such as stable process, simple operation, and environmental protection without pollution, and has broad prospects for industrial application. Attached Figure Description

[0015] Figure 1 The graphs show the purity of the raw materials used in the embodiments and comparative examples of this invention. Figure 2 This is a chromatogram showing the purity of the product obtained in Example 1 of the present invention; Figure 3 This is a chromatogram showing the purity of the product obtained in Comparative Example 1 of this invention. Figure 4 This is a chromatogram showing the purity of the product obtained in Comparative Example 2 of this invention. Figure 5 This is a chromatogram showing the purity of the product obtained in Comparative Example 3 of this invention. Detailed Implementation

[0016] The technical solutions in specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0017] This invention provides a method for purifying 1,2-hexanediol, comprising the following steps: 1) Mix crude 1,2-hexanediol with water, and transfer the resulting mixture into a distillation column. Control the temperature inside the column at 60-100℃ and the pressure at the top of the column at 4.5-5.5 KPa for distillation until the water in the mixture is removed. 2) After the water in the mixture has been completely removed, adjust the temperature inside the distillation column to 120-130℃, the temperature at the top of the column to 45-75℃, the pressure at the top of the column to 0.2-0.8KPa, and the reflux ratio to 1-6:4-1 to continue distillation and collect the distillate; 3) The fraction is mixed with activated carbon for adsorption and deodorization to obtain 1,2-hexanediol after adsorption treatment; 4) The 1,2-hexanediol after adsorption treatment was purged with nitrogen gas to obtain purified 1,2-hexanediol; In step 2), the 38wt%-42wt% of material distilled first is taken as the fore fraction, and the remaining fraction is the main fraction. The fore fraction and the main fraction are collected separately and mixed with activated carbon for adsorption and deodorization. The amount of activated carbon added to the fore fraction is 5-8‰ of the mass of the fore fraction, and the amount of activated carbon added to the main fraction is 1-4‰ of the mass of the main fraction.

[0018] This invention involves mixing crude 1,2-hexanediol with water, transferring the resulting mixture into a distillation column, and controlling the column temperature at 60-100°C and the top pressure at 4.5-5.5 kPa for distillation until the water is removed from the mixture. In this invention, the purity of the crude 1,2-hexanediol is preferably 90-98 wt%. In this invention, water and crude 1,2-hexanediol are mixed, and the column temperature is controlled at 60-100°C for low-temperature distillation. Water acts as both a reactant and an azeotropic agent, allowing certain impurities in the crude 1,2-hexanediol to react with the water, and low-boiling-point impurities with odors are carried away during azeotropic distillation, thus completing the primary purification. Simultaneously, controlling the column temperature at 60-100°C for low-temperature distillation helps prevent the generation of secondary odors. In this invention, the preferred mass ratio of crude 1,2-hexanediol to water is 1:1-4. If the amount of water added is too low, the purification effect will be poor and the deodorization of the raw material will be insignificant. If the amount added is too high, the dehydration process will be longer and more energy-intensive, resulting in a lower yield. Understandably, the mass ratio of crude 1,2-hexanediol to water specified in this application is within the optimal range.

[0019] In this invention, after the water in the mixture has been completely removed, the temperature inside the distillation column is adjusted to 120-130℃, the top temperature to 45-75℃, the top pressure to 0.2-0.8 kPa, and the reflux ratio to 1-6:4-1 to continue distillation, and the distillate is collected. In this invention, after the water is removed, distillation continues, and 1,2-hexanediol is distilled off by adjusting the distillation parameters; the collected distillate is 1,2-hexanediol.

[0020] It should be noted that during distillation, the reboiler temperature refers to the set oil bath temperature (the temperature inside the column is controlled by adjusting the reboiler temperature), the column temperature refers to the temperature of the solution inside the reboiler, and the column top temperature is the temperature of the vapor that the material reaches after passing through the distillation column.

[0021] After collecting the distillate, the present invention mixes the distillate with activated carbon for adsorption and deodorization to obtain 1,2-hexanediol after adsorption treatment. In this invention, to save activated carbon and further reduce reaction costs, it is preferred to use the first 38wt%-42wt% of the distilled material as the fore-distillate, and the remaining distillate as the main distillate. The fore-distillate and main distillate are collected separately and mixed with activated carbon for adsorption and deodorization. The preferred amount of activated carbon added to the fore-distillate is 5-8‰ of its mass, and the preferred amount of activated carbon added to the main distillate is 1-4‰ of its mass. In this invention, to ensure more complete and rapid adsorption, stirring is preferably performed during the adsorption process, with a preferred stirring speed of 200-500 r / min. In this invention, the preferred adsorption temperature is 30-40℃, and the preferred adsorption time is 2-10 h. In this invention, adsorption with activated carbon can remove odors that were not removed during distillation.

[0022] In this invention, the activated carbon is preferably modified activated carbon. In this invention, the modified activated carbon is preferably prepared using the following steps: a. Soak the activated carbon in an acid solution, wash it until it is neutral, and then dry it to obtain dry activated carbon; b. Activate the dry activated carbon in a nitrogen atmosphere to obtain modified activated carbon.

[0023] In this invention, the activated carbon is preferably pulverized to 20-40 mesh before soaking to ensure thorough soaking. In this invention, the acid solution in step a is preferably a 5-10 wt% hydrochloric acid solution, and the soaking time is preferably 2-3 hours. The drying temperature is preferably 110-120℃, and the drying time is preferably 4-6 hours. This invention does not specifically limit the type or source of the activated carbon; commercially available products in the art are acceptable. In this embodiment, coconut shell activated carbon is used. In this invention, the activation temperature in step b is preferably 400-500℃, and the activation time is preferably 2-3 hours.

[0024] This invention modifies activated carbon with acid and then activates it, which not only increases the specific surface area and improves the adsorption efficiency, but also improves the adsorption stability.

[0025] After obtaining the adsorption-treated 1,2-hexanediol, the present invention uses nitrogen gas to purge the adsorption-treated 1,2-hexanediol to obtain purified 1,2-hexanediol. In this invention, during purging, the purity of the nitrogen gas is preferably ≥99.9 wt%, continuous bubbling is performed, the purging time is preferably 2-12 hours, and the pressure inside the tube is preferably maintained at 0.1-0.15 MPa. In this invention, using nitrogen gas for purging can entrain trace amounts of light components and prevent the product from absorbing moisture / oxidizing, ensuring storage stability.

[0026] The purification method for 1,2-hexanediol provided by this invention involves sequentially adding water for primary distillation, secondary distillation, activated carbon adsorption, and nitrogen purging, thereby effectively removing impurities from 1,2-hexanediol and eliminating odor, thus obtaining purified 1,2-hexanediol. The purified 1,2-hexanediol has a purity ≥99.8% and an odor level ≤1.

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

[0028] Example 1 Take crude 1,2-hexanediol with a purity of 91.2 wt% (liquid chromatogram as shown in figure). Figure 1Add 500 g of water to the mixture (as shown), and then perform vacuum distillation (temperature controlled at 60-100℃, top pressure at 5 kPa) to remove water. This water removal removes some low-boiling-point odorous substances. After water removal, maintain the reactor temperature at 120-125℃, the top temperature at 65-75℃, the top pressure at 0.8 kPa, and the reflux ratio at 4:1. Collect 150 g of the fore-distillate and 340 g of the main distillate.

[0029] 5‰ of modified activated carbon was added to the forward fraction and 1‰ of modified activated carbon was added to the main fraction. The adsorption was carried out at a rotation speed of 300 r / min, an adsorption temperature of 30℃, and a time of 5 h. After adsorption, the mixture was filtered. The odor of the 1,2-hexanediol obtained after adsorption treatment was significantly reduced. The modified activated carbon was prepared by the following method: coconut shell activated carbon was pulverized to 30 mesh, soaked in 5% hydrochloric acid solution for 3 h, washed until neutral, dried at 110℃ for 6 h, and activated at 450℃ under nitrogen atmosphere for 2 h.

[0030] The adsorption-treated 1,2-hexanediol was transferred into a product container or product tank. 99.9% nitrogen gas was bubbled through the product container at a pressure of 0.12 MPa for 10 hours, ultimately yielding 385 g of purified 1,2-hexanediol. Gas chromatography was used for detection (detection chromatogram shown below). Figure 2 As shown in the figure, the purity was tested to be 99.9%, there was no odor at room temperature, the odor level was 0, which meets the standards for cosmetic-grade raw materials, and the yield of odorless products was 77%.

[0031] In each embodiment and comparative example, the odor level was determined using the following method: Nine randomly selected evaluators conducted blind tests on the samples. The evaluators gently shook the sample bottles, slowly smelled the odor at the bottle opening, and scored the samples, taking the average value and eliminating extreme values. The final average score was the odor level of the sample. The specific evaluation criteria are shown in Table 1.

[0032] Table 1

[0033] Example 2 Take 500 g of crude 1,2-hexanediol with a purity of 91.2 wt%, add 500 g of water, and subject the resulting mixture to vacuum distillation (temperature controlled at 60-100℃, top pressure at 5.5 kPa) to remove water. This water removal process carries away some low-boiling-point odorous substances. After water removal, control the reboiler temperature at 130℃, the reboiler internal temperature at 125-130℃, the top temperature at 45-55℃, the top pressure at 0.2 kPa, and the reflux ratio at 3:2. Collect 190 g of the fore-distillate and 305 g of the main distillate.

[0034] 8‰ of modified activated carbon was added to the forward fraction and 2‰ of modified activated carbon was added to the main fraction. The adsorption was carried out at a rotation speed of 200 r / min, an adsorption temperature of 40℃, and a time of 2 h. After adsorption, the mixture was filtered. The odor of the 1,2-hexanediol obtained after adsorption treatment was significantly reduced. The modified activated carbon was prepared by the following method: coconut shell activated carbon was pulverized to 30 mesh, soaked in 10% hydrochloric acid solution for 2 h, washed until neutral, dried at 120℃ for 4 h, and activated at 400℃ under nitrogen atmosphere for 3 h.

[0035] The adsorption-treated 1,2-hexanediol was transferred to a sealed container, and 99.9% nitrogen gas was introduced into the sealed container for continuous bubbling and purging at a pressure of 0.15 MPa for 2 hours. Finally, 366 g of purified 1,2-hexanediol was obtained, with a purity of 99.85%. It was odorless at room temperature, with an odor level of 1, which meets the standards for cosmetic-grade raw materials. The yield of the odorless product was 73.2%.

[0036] Example 3 Take 500 g of crude 1,2-hexanediol with a purity of 91.2%, add 500 g of water, and subject the resulting mixture to vacuum distillation (temperature controlled at 60-100℃, top pressure at 4.5 kPa) to remove water. This water removal removes some low-boiling-point odorous substances. After water removal, control the temperature inside the distillation vessel at 120-125℃, adjust the temperature inside the distillation column to 120-130℃, the top temperature to 55-65℃, and the top pressure to 0.5 kPa. The reflux ratio is 1:1. Collect 205 g of the fore-distillate and 289 g of the main distillate.

[0037] 3‰ of modified activated carbon was added to the forward fraction and 1‰ of modified activated carbon was added to the main fraction. The adsorption was carried out at a rotation speed of 500 r / min, an adsorption temperature of 30℃, and an adsorption time of 10 h. After adsorption, the mixture was filtered. The odor of the 1,2-hexanediol obtained after adsorption treatment was significantly reduced. The modified activated carbon was prepared by the following method: coconut shell activated carbon was pulverized to 30 mesh, soaked in 5% hydrochloric acid solution for 3 h, washed until neutral, dried at 110℃ for 6 h, and activated at 500℃ under nitrogen atmosphere for 2 h.

[0038] The adsorption-treated 1,2-hexanediol was transferred into a product container or product tank. 99.9% nitrogen gas was introduced into the product container, and continuous bubbling and purging were performed at a pressure of 0.1 MPa for 12 hours. Finally, 351g of purified 1,2-hexanediol was obtained, with a purity of 99.78%. It was odorless at room temperature, with an odor level of 1, which meets the standards for cosmetic-grade raw materials. The yield of the odorless product was 70.2%.

[0039] Example 4 Take 500 g of crude 1,2-hexanediol with a purity of 91.2%, add 2000 g of water, and subject the resulting mixture to vacuum distillation (temperature controlled at 60-100℃, top pressure at 4.5 kPa) to remove water. This water removal removes some low-boiling-point odorous substances. After water removal, control the temperature inside the distillation vessel at 120-125℃, adjust the temperature inside the distillation column to 120-130℃, the top temperature to 55-65℃, and the top pressure to 0.5 kPa. The reflux ratio is 2:1. Collect 155 g of the fore-distillate and 332 g of the main distillate.

[0040] 3‰ of modified activated carbon was added to the forward fraction and 1‰ of modified activated carbon was added to the main fraction. The adsorption was carried out at a rotation speed of 500 r / min, an adsorption temperature of 35℃, and a time of 5 h. After adsorption, the mixture was filtered. The odor of the 1,2-hexanediol obtained after adsorption treatment was significantly reduced. The modified activated carbon was prepared by the following method: coconut shell activated carbon was pulverized to 30 mesh, soaked in 5% hydrochloric acid solution for 3 h, washed until neutral, dried at 110℃ for 6 h, and activated at 500℃ under nitrogen atmosphere for 2 h.

[0041] The adsorption-treated 1,2-hexanediol was transferred into a product container or product tank. 99.9% nitrogen gas was introduced into the product container, and continuous bubbling and purging were performed at a pressure of 0.15 MPa for 12 hours. Finally, 375g of purified 1,2-hexanediol was obtained. The purity was tested to be 99.82%. It was odorless at room temperature, with an odor level of 0, which meets the standards for cosmetic-grade raw materials. The yield of the odorless product was 75%.

[0042] Comparative Example 1 Take 500 g of crude 1,2-hexanediol with a purity of 91.2 wt% and perform vacuum distillation. Control the temperature inside the vessel at 120-125℃, the temperature at the top of the column at 65-75℃, the pressure at the top of the column at 0.8 kPa, and the reflux ratio at 4:1. Collect 217 g of the first fraction and 280 g of the main fraction.

[0043] 5‰ of modified activated carbon was added to the forward fraction and 1‰ of modified activated carbon was added to the main fraction. The adsorption was carried out at a rotation speed of 300 r / min, an adsorption temperature of 30℃, and a time of 5 h. After adsorption, the mixture was filtered. The odor of the 1,2-hexanediol obtained after adsorption treatment was significantly reduced. The modified activated carbon was prepared by the following method: coconut shell activated carbon was pulverized to 30 mesh, soaked in 5% hydrochloric acid solution for 3 h, washed until neutral, dried at 110℃ for 6 h, and activated at 450℃ under nitrogen atmosphere for 2 h.

[0044] The adsorption-treated 1,2-hexanediol was transferred into a product container or product tank. 99.9% nitrogen gas was bubbled through the product container at a pressure of 0.12 MPa for 10 hours, ultimately yielding 310 g of purified 1,2-hexanediol. Gas chromatography was used for detection (detection chromatogram shown below). Figure 3 As shown in the figure, the purity was tested to be 98.4%, the odor level was 2, with a slight odor residue, and the product yield was 62%.

[0045] Comparative Example 2 Crude 1,2-hexanediol with a purity of 91.2 wt% was added to modified activated carbon at a concentration of 5‰ of the crude 1,2-hexanediol. The adsorption was carried out at a rotation speed of 300 r / min, an adsorption temperature of 30℃, and an adsorption time of 5 h. After adsorption, the adsorption was performed by vacuum filtration. The odor of the adsorbed 1,2-hexanediol was reduced after the adsorption treatment. The modified activated carbon was prepared by the following method: coconut shell activated carbon was pulverized to 30 mesh, soaked in 5% hydrochloric acid solution for 3 h, washed until neutral, dried at 110℃ for 6 h, and activated at 450℃ under nitrogen atmosphere for 2 h.

[0046] Detection was performed using gas chromatography (detection chromatogram as shown). Figure 4 As shown in the figure, the purity of 1,2-hexanediol after adsorption treatment is 97.8%, and the odor level is grade 3, with a residual irritating odor.

[0047] Comparative Example 3 500 g of crude 1,2-hexanediol with a purity of 91.2 wt% was taken, and 5‰ of the crude 1,2-hexanediol was added to modified activated carbon. The adsorption was carried out at a rotation speed of 300 r / min, an adsorption temperature of 30℃, and an adsorption time of 5 h. After adsorption, the adsorption was performed by vacuum filtration. The odor of the adsorbed 1,2-hexanediol was reduced after the adsorption treatment. The modified activated carbon was prepared by the following method: coconut shell activated carbon was pulverized to 30 mesh, soaked in 5% hydrochloric acid solution for 3 h, washed until neutral, dried at 110℃ for 6 h, and activated at 450℃ under nitrogen atmosphere for 2 h.

[0048] Add 500 g of water to the 1,2-hexanediol after adsorption treatment, and subject the resulting mixture to vacuum distillation (temperature controlled at 60-100℃, top pressure at 5 kPa) to remove water. This water removal removes some low-boiling-point odor substances. After water removal, maintain the reactor temperature at 120-125℃, the top temperature at 65-75℃, the top pressure at 0.8 kPa, and the reflux ratio at 4:1, collecting 302 g of distillate.

[0049] The fraction was transferred to a product container or product tank. 99.9% nitrogen gas was bubbled through the product container, and continuous purging was performed at a pressure of 0.12 MPa for 10 hours. This yielded 301 g of purified 1,2-hexanediol, which was then analyzed by gas chromatography (detection chromatogram shown below). Figure 5 As shown in the figure, the purity was tested to be 99.68%, there was an odor at room temperature, the odor level was 2, and the product yield was 60.2%.

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for purifying 1,2-hexanediol, characterized in that, Includes the following steps: 1) Mix crude 1,2-hexanediol with water, and transfer the resulting mixture into a distillation column. Control the temperature inside the column at 60-100℃ and the pressure at the top of the column at 4.5-5.5 KPa for distillation until the water in the mixture is removed. 2) After the water in the mixture has been completely removed, adjust the temperature inside the distillation column to 120-130℃, the temperature at the top of the column to 45-75℃, the pressure at the top of the column to 0.2-0.8KPa, and the reflux ratio to 1-6:4-1 to continue distillation and collect the distillate; 3) The fraction is mixed with activated carbon for adsorption and deodorization to obtain 1,2-hexanediol after adsorption treatment; 4) The 1,2-hexanediol after adsorption treatment was purged with nitrogen gas to obtain purified 1,2-hexanediol; In step 2), the 38wt%-42wt% of material distilled first is taken as the fore fraction, and the remaining fraction is the main fraction. The fore fraction and the main fraction are collected separately and mixed with activated carbon for adsorption and deodorization. The amount of activated carbon added to the fore fraction is 5-8‰ of the mass of the fore fraction, and the amount of activated carbon added to the main fraction is 1-4‰ of the mass of the main fraction.

2. The purification method according to claim 1, characterized in that, The mass ratio of crude 1,2-hexanediol to water in step 1) is 1:1-4.

3. The purification method according to claim 1, characterized in that, In step 3), the activated carbon is modified activated carbon; Modified activated carbon was prepared using the following steps: a. Soak activated carbon in an acid solution, wash until neutral, and then dry to obtain dry activated carbon; b. Activate the dry activated carbon in a nitrogen atmosphere to obtain modified activated carbon.

4. The purification method according to claim 3, characterized in that, The acid solution mentioned in step a is a 5-10 wt% hydrochloric acid solution, and the soaking time is 2-3 hours.

5. The purification method according to claim 3, characterized in that, The activation temperature in step b is 400-500℃, and the time is 2-3 hours.

6. The purification method according to claim 1, characterized in that, In step 3), stirring is performed during the adsorption process, and the stirring speed is 200-500 r / min.

7. The purification method according to claim 1, characterized in that, In step 3), the adsorption temperature is 30-40℃ and the adsorption time is 2-10h.

8. The purification method according to claim 1, characterized in that, During the purging process in step 4), the purity of nitrogen should be ≥99.9wt%, and continuous bubbling should be performed for 2-12 hours, while maintaining the pressure inside the tube at 0.1-0.15MPa.

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