Process for purifying bio-based crude ethylene glycol

Abstract

A method for purifying bio-based crude ethylene glycol, the method comprising: using the bio-based crude ethylene glycol as a raw material, diluting it with water to an ethylene glycol concentration of 1 to 95 wt %, and continuously passing the diluted aqueous ethylene glycol solution through an adsorption bed packed with one or more macroporous adsorption resins and optional ion exchange resins at a temperature of 0 to 100°C and a volumetric space velocity of 0.01 to 20 BV / hr to obtain a purified aqueous ethylene glycol solution, which is then dehydrated to obtain ethylene glycol.

Description

[Technical Field]

[0001] Technical Field The present invention provides a process for the removal of hydroxylic impurities having boiling points close to that of ethylene glycol, such as butanediol, pentanediol, hexanediol, and optionally [ka] and trace amounts of impurities that affect the ultraviolet transmittance of ethylene glycol, such as acids, ethers, aldehydes, ketones, compounds containing double bonds, and / or alcohols, and in particular, a method for purifying bio-based crude ethylene glycol. [Background technology]

[0002] Background technology Due to uncertainties in petroleum prices and growing awareness of sustainability, rapid developments have been made in technologies for producing ethylene glycol using biomass as a feedstock in recent years. However, due to different synthetic routes, the biomass-based ethylene glycol production process produces different hydroxyl-containing by-products from those produced by petroleum or coal routes, as well as impurities, such as acids, ethers, aldehydes, ketones, and / or alcohols, that affect the UV transmittance of ethylene glycol and are present in trace amounts or even below the detection limit of GC. The conventional purification method for liquid compounds is the rectification process, which separates substances based on their different boiling points. However, the boiling points of these impurities are close to that of ethylene glycol, and the impurities, such as acids, ethers, aldehydes, ketones, and / or alcohols, that affect the UV transmittance of ethylene glycol and are present in trace amounts or even below the detection limit of GC, exhibit physical properties similar to those of ethylene glycol and boiling points close to that of ethylene glycol. Therefore, separating ethylene glycol from these alcohol impurities directly by rectification can result in low ethylene glycol yields and high energy consumption. In addition, the ethylene glycol obtained by rectification still contains trace amounts of impurities, so the ultraviolet transmittance of ethylene glycol cannot meet the requirements of fiber-grade and bottle-grade polyester.

[0003] U.S. Patent Nos. 4,935,102, 4,966,658, 5,423,955, and 8,906,205 describe processes for separating ethylene glycol from butanediol by using different azeotropic agents. The azeotropic agent and ethylene glycol have an azeotropic point. Generally, the temperature of the azeotropic point is significantly lower than the boiling point of ethylene glycol. Therefore, the boiling point of the azeotropic mixture containing ethylene glycol and the azeotropic agent is significantly different from the boiling point of impurities such as butanediol. Therefore, ethylene glycol and butanediol can be economically separated by rectification.

[0004] In the biomass-based ethylene glycol production process, alcohol impurities other than butanediol that have boiling points very close to that of ethylene glycol, such as pentanediol, hexanediol, and optionally [ka] and impurities, such as acids, ethers, aldehydes, ketones, and / or alcohols, which affect the UV transmittance of ethylene glycol and are present in trace amounts or even below the detection limit of GC. The aforementioned patent application does not indicate that the process therein can effectively separate these impurities.

[0005] Chinese Patent Publication No. 106946654A describes the use of an adsorption bed containing a porous carbon adsorbent to adsorb impurities in biomass ethylene glycol to purify ethylene glycol. This technology only describes the increase in the ultraviolet transmittance of ethylene glycol, and does not mention butanediol, which has the following molecular formula: [ka] Its use to separate alcohol impurities such as pentanediol or hexanediol is not shown.

[0006] Chinese Patent Application No. 201010200038.5 describes a method for purifying ethylene glycol by using zeolite and aluminum silicate as adsorbents. However, this method only describes that the adsorbent can effectively remove 1,2-butanediol, but does not indicate that the adsorbent can improve ultraviolet transmittance or other hydroxyl impurities.

[0007] Chinese Patent Application No. 201110047173.5 describes a method for increasing the ultraviolet transmittance of ethylene glycol by contacting ethylene glycol with an adsorbent contained in a fixed bed and retaining substances that affect the ultraviolet transmittance of ethylene glycol within the fixed bed. However, this method only describes that the adsorbent bed increases the ultraviolet transmittance, and does not show its effect on adsorbing hydroxyl-containing alcohol impurities such as butanediol, pentanediol, and hexanediol. Summary of the Invention [Problem to be solved by the invention]

[0008] Conventional direct adsorption processes that use adsorbents to produce petroleum-based or coal-based ethylene glycol cannot effectively separate the specific impurities in bio-based ethylene glycol. [Means for solving the problem]

[0009] Summary of the Invention The present invention provides a method for purifying bio-based crude ethylene glycol to cost-effectively separate it in high yield from hydroxyl-containing impurities having boiling points close to that of ethylene glycol and from trace impurities that affect the ultraviolet light transmittance of ethylene glycol, such as acids, ethers, aldehydes, ketones, compounds containing double bonds, and / or alcohols, thereby increasing the purity and ultraviolet light transmittance of the ethylene glycol.

[0010] The method for purifying bio-based crude ethylene glycol of the present invention includes using bio-based crude ethylene glycol as a raw material, diluting it with water to an ethylene glycol concentration of 1 to 95 wt%, preferably 20 to 90 wt%, and more preferably 40 to 85 wt%, and continuously passing the diluted aqueous ethylene glycol solution through an adsorption bed packed with one or more, preferably one or two, macroporous adsorption resins and optional ion exchange resins at a temperature of 0 to 100°C, preferably 10 to 80°C, and particularly preferably 10 to 50°C, and at a volumetric space velocity of 0.01 to 20 BV / h, preferably 0.01 to 10 BV / h, to obtain a purified aqueous ethylene glycol solution, which is then dehydrated to obtain ethylene glycol. The purity and ultraviolet transmittance of the dehydrated ethylene glycol meet industrial standards for high-grade polyester-grade ethylene glycol. The specifications for high-grade polyester-grade ethylene glycol in this specification refer to a purity of 99.9% or more, and an ultraviolet transmittance of 75% or more, 95% or more, and 99% or more at wavelengths of 220 nm, 275 nm, and 350 nm, respectively.

[0011] The resin may contain trace amounts of impurities that affect UV transmittance, such as acids, ethers, aldehydes, ketones, compounds containing double bonds, and / or alcohols, and hydroxyl-containing impurities that affect the purity of ethylene glycol and have boiling points close to that of ethylene glycol, such as butanediol, pentanediol, hexanediol, and optional [ka] The present invention provides a cost-effective method for separating ethylene glycol from alcohol impurities in high yields, thereby increasing the ultraviolet transmittance and purity of the ethylene glycol.

[0012] Optionally, the bio-based crude ethylene glycol undergoes an ultraviolet lamp pretreatment process, e.g., irradiating the bio-based crude ethylene glycol with ultraviolet light at wavelengths of 100 nm or greater, preferably 180 nm or greater, and more preferably 180-350 nm. In partially bio-based crude ethylene glycol feedstocks, the presence of larger amounts of impurities that affect UV transmittance leads to a decrease in UV transmittance, shortening the resin regeneration cycle and increasing regeneration and resin costs. Therefore, to extend the resin regeneration cycle and reduce resin operating costs, it is desirable to add a controllable UV lamp process before the resin adsorption process to increase the UV transmittance of the ethylene glycol. Without decomposing the ethylene glycol molecule, the controllable UV light converts impurities containing double bonds that absorb the appropriate UV light (e.g., UV light in the 180-350 nm range) into compounds that do not contain double bonds, thereby preliminarily increasing the UV transmittance of the ethylene glycol.

[0013] The ultraviolet lamp pretreatment process can be carried out as follows: a bio-based crude ethylene glycol feedstock is introduced into a vessel containing an ultraviolet lamp having a wavelength of 100 nm or more, preferably 180 nm or more, more preferably 180 to 350 nm, at a temperature of 0 to 170°C, preferably 10 to 120°C, more preferably 10 to 50°C, and maintained therein for 0 to 2 hours, preferably 0.1 to 1 hour. The ultraviolet lamp is preferably a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an LED lamp, a high-intensity discharge lamp, or a metal halide lamp. After its ultraviolet transmittance has been preliminarily increased, the discharged material can be further treated in a resin adsorption process.

[0014] The macroporous adsorption resin is, for example, preferably a macroporous adsorption resin containing styrene and / or divinylbenzene as a skeleton, more preferably a macroporous adsorption resin containing styrene and / or divinylbenzene as a skeleton and having a specific surface area of ​​800 m 2 / g or larger macroporous adsorption resin.

[0015] The ion exchange resin may be a weakly basic anion exchange resin, preferably a weakly basic anion exchange resin containing primary amine groups, secondary amine groups, and / or tertiary amine groups on its surface.

[0016] Bio-based crude ethylene glycol refers to ethylene glycol prepared from biomass (as used herein, biomass preferably refers to first generation edible biomass, including corn and sugarcane, and second generation non-crop biomass obtained from agricultural and forestry waste, including crop stalks, wood, and bagasse). In addition to ethylene glycol, bio-based crude ethylene glycol contains, but is not limited to, butanediol, pentanediol, and hexanediol. Optionally, bio-based crude ethylene glycol has the following molecular formula: [ka] The butanediol is preferably 1,2-butanediol, 2,3-butanediol, or 1,4-butanediol. The pentanediol is preferably 1,2-pentanediol. The hexanediol is preferably 1,2-hexanediol. More preferably, the bio-based crude ethylene glycol also contains: 88 to 100 wt% ethylene glycol, preferably 95 to 100 wt% ethylene glycol, more preferably 98 to 100 wt% ethylene glycol (excluding the 100 wt% endpoint); 0 to 5 wt %, preferably 0 to 1 wt %, more preferably 0 to 0.5 wt %, particularly preferably 0 to 0.1 wt % of butanediol (preferably 1,2-butanediol, 2,3-butanediol, and / or 1,4-butanediol, excluding the endpoint 0), 0 to 5 wt%, preferably 0 to 1 wt%, more preferably 0 to 0.5 wt%, particularly preferably 0 to 0.1 wt% of pentanediol (preferably 1,2-pentanediol, excluding the zero end point); 0 to 5 wt %, preferably 0 to 2 wt %, more preferably 0 to 1.5 wt % of hexanediol (preferably 1,2-hexanediol, excluding the zero end point); Optionally, 0 to 5 wt%, preferably 0 to 1 wt%, more preferably 0 to 0.5 wt%, particularly preferably 0 to 0.1 wt% [ka] These include, but are not limited to:

[0017] The bio-based crude ethylene glycol optionally comprises: 0 to 5 wt %, preferably 0 to 1 wt %, more preferably 0 to 0.1 wt % of 1,2-propylene glycol; 0 to 5 wt%, preferably 0 to 1 wt%, more preferably 0 to 0.1 wt% of diethylene glycol Also included.

[0018] Since bio-based crude ethylene glycol contains certain hydrophilic hydroxyl-containing impurities, dilution with water facilitates the adsorption of said impurities.

[0019] The water may be, for example, demineralized water.

[0020] Dehydration can be achieved, for example, by rectification.

[0021] Trace impurities that affect the UV transmittance of ethylene glycol, such as acids, ethers, aldehydes, ketones, compounds containing double bonds, and / or alcohols, can absorb UV light even at trace levels, making these impurities undetectable by instrumental or chemical methods, such as gas chromatography or liquid chromatography. Therefore, their content in the feedstock can only be expressed by UV transmittance. In this application, due to the presence of the aforementioned impurities, the UV transmittance at 220 nm, 275 nm, and 350 nm of the bio-based crude ethylene glycol feedstock cannot meet at least one of the requirements specified for high-grade polyester-grade ethylene glycol products. Such transmittances can be expressed, for example, as follows: UV transmittance at 220 nm of less than 75%, preferably less than 40%, more preferably less than 10%; UV transmittance at 275 nm of less than 95%, preferably less than 70%, more preferably less than 30%; and / or UV transmittance at 350 nm of less than 99%, preferably less than 97%, more preferably less than 96%.

[0022] By using the method of the present invention, the purity of ethylene glycol can be increased to 99.9% or more with a high ethylene glycol recovery rate of 99.9% or more, and the ultraviolet transmittance at 220 nm, 275 nm, and 350 nm can be increased to 75% or more, 95% or more, and 99% or more, respectively. In addition, the cost of the present invention is significantly lower than that of conventional rectification methods. [Brief explanation of the drawings]

[0023] DESCRIPTION OF THE DRAWINGS [Figure 1] 1 is a process flowchart of Example 1. [Figure 2a] 1 is a curve showing the change in ultraviolet transmittance of the ethylene glycol product according to Example 1. [Figure 2b] 1 is a curve showing the change in ethylene glycol content according to Example 1. [Figure 3] 1 is a process flow chart of Example 2. [Figure 4a] 1 is a curve showing the change in ultraviolet transmittance of the ethylene glycol product according to Example 2. [Figure 4b] 1 is a curve showing the change in ethylene glycol content according to Example 2. [Figure 5] 1 is a process flow chart of Example 3. [Figure 6a] 1 is a curve showing the change in ultraviolet transmittance of the ethylene glycol product according to Example 3. [Figure 6b] 1 is a curve showing the change in ethylene glycol content according to Example 3. [Figure 7] 1 is a process flowchart of Comparative Example 1. [Figure 8a] 1 is a curve showing the change in ultraviolet transmittance of the ethylene glycol product according to Comparative Example 2. [Figure 8b] 1 is a curve showing the change in ethylene glycol content according to Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0024] Specific Embodiments Example The present invention will be further described with reference to the following examples, but the present invention is not limited to the following examples.

[0025] Example 1 The resin column was filled with 200 ml of XA-1G macroporous adsorption resin purchased from Xi'an Sunresin New Materials Co., Ltd. The resin skeleton was styrene-divinylbenzene, and the specific surface area was 1200 m 2 / g.

[0026] The crude ethylene glycol product obtained by hydrogenation of biomass and rectification for preliminary removal of light and heavy fractions was used as the raw material. The raw material was analyzed by using the analytical method specified in the national standard GB / T4649-2008, and the contents of various components were as follows: 99.700 wt% ethylene glycol, 0.020 wt% 1,2-pentanediol, 0.250 wt% 1,2-hexanediol, 0.010 wt% 1,2-butanediol, 0.010 wt% [ka] , and 0.010 wt% of other components. The UV transmittance of the raw material was 13.5% at 220 nm, 59.0% at 275 nm, and 96.8% at 350 nm.

[0027] According to the process flow shown in Figure 1, crude ethylene glycol feedstock and demineralized water were mixed in a mass ratio of 3:1 to obtain a crude aqueous ethylene glycol solution, which was then continuously introduced into a resin bed at 30°C and a volumetric space velocity of 0.5 BV / h, and the material discharged from the resin bed was dehydrated using a fractionator. Figures 2a and 2b show the results of the ultraviolet transmittance and purity of the ethylene glycol product obtained after the adsorption and dehydration treatments.

[0028] After 14 hours, the ultraviolet transmittance at 275 nm had fallen to a level lower than the requirement specified for premium-grade product, indicating the adsorbent was ineffective. A total of 1524.6 g of crude aqueous ethylene glycol solution containing 1140.0 g of ethylene glycol was processed; 1139.7 g of acceptable ethylene glycol product was ultimately obtained. Thus, the yield of purified acceptable ethylene glycol was 99.97%.

[0029] Comparative Example 1 The crude ethylene glycol product described in Example 1, obtained by hydrogenation of biomass and rectification for preliminary removal of light and heavy fractions, was used as the feedstock and separated by using the conventional rectification method shown in Figure 7. The total number of theoretical plates in the rectification column was 90, the reflux ratio was 15:1, and the operating pressure was 10 kPa (absolute pressure). The feedstock was introduced into the rectification column from the 40th theoretical plate at a flow rate of 200 g / h. The ethylene glycol product was withdrawn from the top of the rectification column at a flow rate of 195 g / h. The ethylene glycol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, and [ka] The contents, in weight percentages, of ethylene glycol were 99.920%, 0.010%, 0.020%, 0.040%, and 0.010%, respectively. The ultraviolet transmittance was 20.8% at 220 nm, 63.2% at 275 nm, and 98.5% at 350 nm. The overall rectification yield of ethylene glycol was 97.7%.

[0030] The test results show that the conventional rectification process can effectively separate 1,2-hexanediol from ethylene glycol and achieve an ethylene glycol purity of 99.90% or more, but the yield of ethylene glycol is only 97.7%. In addition, the high reflux ratio results in high steam energy consumption and cannot effectively increase the ultraviolet transmittance; in contrast, the method of the present invention can increase the purity of ethylene glycol to 99.90% or more with high yield and low cost, and the ultraviolet transmittance of ethylene glycol at 220 nm, 275 nm, and 350 nm increases to more than 75%, 95%, and 99%, respectively.

[0031] Comparative Example 2 The crude ethylene glycol product described in Example 1, obtained by hydrogenation of biomass and rectification for preliminary removal of light and heavy fractions, was used as the feedstock, and the same type and volume of adsorbent as described in Example 1 was packed into a resin column.

[0032] According to the process flow shown in Figure 1, the crude ethylene glycol feedstock was continuously introduced into the resin bed without mixing with water at 30°C and a volumetric space velocity of 0.5 BV / h. Figures 8a and 8b show the results of the UV transmittance and purity of the ethylene glycol product obtained after the adsorption treatment.

[0033] The test results show that in Comparative Example 2, although the same raw materials, adsorbent and operating conditions as those described in Example 1 were used, because the bio-based crude ethylene glycol was not mixed with water, the specific impurities in the bio-based crude ethylene glycol were not effectively adsorbed by the adsorbent, and therefore the purity and ultraviolet transmittance of the discharged ethylene glycol were not increased to the levels specified in the standards for high-grade products.

[0034] Example 2 A 30 ml capacity ultraviolet lamp vessel was filled with a low-pressure mercury-vapor ultraviolet lamp with a wavelength of 254 nm and an output of 23 W. Resin column A was filled with 750 ml of D303 weakly basic anion exchange resin, which has a styrene-divinylbenzene backbone and contains primary amine groups, purchased from Xi'an Sunresin New Materials Co., Ltd. Resin column B was filled with 200 ml of L493 macroporous adsorption resin, purchased from Dow Chemical. The backbone of the macroporous adsorption resin was a macroporous styrene polymer, and its specific surface area was 1100 m. 2 / g.

[0035] The crude ethylene glycol product obtained by hydrogenation of biomass and rectification for preliminary removal of light and heavy fractions was used as the raw material. The raw material was analyzed by using the analytical method specified in the national standard GB / T4649-2008, and the contents of various components were as follows: 99.753 wt% ethylene glycol, 0.036 wt% 1,2-pentanediol, 0.146 wt% 1,2-hexanediol, 0.033 wt% 1,2-butanediol, 0.010 wt% [ka] , 0.002 wt% 1,4-butanediol, 0.010 wt% diethylene glycol, and 0.010 wt% other components. The UV transmittance of the raw material was 1.1% at 220 nm, 25.0% at 275 nm, and 95.0% at 350 nm.

[0036] According to the process flow shown in Figure 3, crude ethylene glycol feedstock was continuously introduced into an ultraviolet lamp vessel at 20°C and a flow rate of 100 ml / h. The material discharged from the ultraviolet lamp vessel was mixed with demineralized water in a 2:1 mass ratio to obtain a crude aqueous ethylene glycol solution, which was then continuously introduced into resin bed A at 20°C and a volumetric space velocity of 0.2 BV / h. The material discharged from resin bed A was continuously introduced into resin bed B at a volumetric space velocity of 0.75 BV / h, with other conditions unchanged. The material discharged from resin bed B was dehydrated using a fractionator. Figures 4a and 4b show the results of ultraviolet transmittance and purity of the ethylene glycol product obtained after the ultraviolet lamp treatment and the adsorption and dehydration treatments.

[0037] After 9.3 hours, the UV transmittance at 275 nm had fallen to a level lower than the requirement specified for premium-grade product, indicating the adsorbent was ineffective. A total of 1038.8 g of crude ethylene glycol containing 1036.2 g of ethylene glycol was processed; 1036.0 g of acceptable ethylene glycol product was ultimately obtained. Thus, the yield of purified ethylene glycol was 99.98%.

[0038] Example 3 Resin column A was packed with 40 ml of D303 weakly basic anion exchange resin, which has a styrene-divinylbenzene backbone and contains primary amine groups, purchased from Xi'an Sunresin New Materials Co., Ltd. Resin column B was packed with 200 ml of XA-1G macroporous adsorption resin, purchased from Xi'an Sunresin New Materials Co., Ltd. The macroporous adsorption resin has a styrene-divinylbenzene backbone and a specific surface area of ​​1200 m 2 / g.

[0039] The crude ethylene glycol product obtained by hydrogenation of biomass and rectification for preliminary removal of light and heavy fractions was used as the raw material. The raw material was analyzed by using the analytical method specified in the national standard GB / T4649-2008, and the contents of various components were as follows: 98.81 wt% ethylene glycol, 0.10 wt% 1,2-pentanediol, 1.05 wt% 1,2-hexanediol, 0.02 wt% 1,2-butanediol, 0.01 wt% [ka] , and 0.01 wt% of other components. The UV transmittance of the raw material was 6.6% at 220 nm, 63.0% at 275 nm, and 95.0% at 350 nm.

[0040] As shown in Figure 5, crude ethylene glycol feedstock was mixed with demineralized water in a mass ratio of 3:1 to obtain a crude ethylene glycol aqueous solution, which was then continuously introduced into resin bed A at 30°C and a volumetric space velocity of 1.0 BV / h. The material discharged from resin bed A was continuously introduced into resin bed B at a volumetric space velocity of 0.2 BV / h, with other conditions unchanged. The material discharged from resin bed B was dehydrated using a fractionator. Figures 6a and 6b show the results of ultraviolet transmittance and purity of the ethylene glycol product obtained after adsorption.

[0041] After 5 hours, the purity had fallen to a level lower than the requirements specified for premium-grade product, indicating the adsorbent was ineffective. A total of 217.8 g of crude aqueous ethylene glycol solution containing 161.41 g of ethylene glycol was processed; 161.38 g of acceptable ethylene glycol product was ultimately obtained. Thus, the yield of purified ethylene glycol was 99.98%.

[0042] From the embodiments, it can be seen that the present invention can be used to effectively separate ethylene glycol from trace impurities that affect UV transmittance, such as acids, ethers, aldehydes, ketones, compounds containing double bonds, and / or alcohols, and from hydroxyl-containing impurities that affect ethylene glycol purity and have boiling points close to that of ethylene glycol, to cost-effectively increase the UV transmittance and purity of ethylene glycol in high yield.

Claims

1. A method for purifying bio-based crude ethylene glycol, comprising: using bio-based crude ethylene glycol as a raw material, diluting it with water to an ethylene glycol concentration of 1 to 95 wt %, preferably 20 to 90 wt %, more preferably 40 to 85 wt %; continuously passing the diluted aqueous ethylene glycol solution through an adsorption bed packed with one or more, preferably one or two, macroporous adsorption resins and optional ion exchange resins at a temperature of 0 to 100°C, preferably 10 to 80°C, particularly preferably 10 to 50°C, and a volumetric space velocity of 0.01 to 20 BV / h, preferably 0.01 to 10 BV / h, to obtain a purified aqueous ethylene glycol solution, which is then dehydrated to obtain ethylene glycol; The method, wherein the macroporous adsorption resin comprises a macroporous adsorption resin containing styrene and / or divinylbenzene as a backbone.

2. 10. The method of claim 1, wherein the bio-based crude ethylene glycol is subjected to an ultraviolet lamp pretreatment process, for example, the bio-based crude ethylene glycol is irradiated with ultraviolet light having a wavelength of 100 nm or greater, preferably 180 nm or greater, more preferably 180-350 nm.

3. 3. The method of claim 2, wherein the ultraviolet lamp pretreatment process is carried out in the following manner: the bio-based crude ethylene glycol is introduced as a feedstock into a vessel containing an ultraviolet lamp having a wavelength of 100 nm or more, preferably 180 nm or more, more preferably 180-350 nm, at a temperature of 0-170°C, preferably 10-120°C, more preferably 10-50°C, and kept therein for more than 0 to 2 hours, preferably 0.1 to 1 hour.

4. The macroporous adsorption resin is 800 m ２ The method according to any one of claims 1 to 3, wherein the sintered body has a specific surface area of ​​greater than 1 / g.

5. 5. The method according to claim 1, wherein the ion exchange resin is a weakly basic anion exchange resin, preferably a weakly basic anion exchange resin containing primary amine groups, secondary amine groups, and / or tertiary amine groups on its surface.

6. The bio-based crude ethylene glycol is ethylene glycol prepared from biomass and contains, in addition to ethylene glycol, butanediol, pentanediol, and hexanediol, and optionally the bio-based crude ethylene glycol is 【Chemical 1】 wherein the butanediol is preferably 1,2-butanediol, 2,3-butanediol, 1,4-butanediol, the pentanediol is preferably 1,2-pentanediol, and the hexanediol is preferably 1,2-hexanediol.

7. the bio-based crude ethylene glycol 88 to 100 wt % ethylene glycol, preferably 95 to 100 wt % ethylene glycol, more preferably 98 to 100 wt % ethylene glycol (excluding the 100 wt % endpoint); 0 to 5 wt %, preferably 0 to 1 wt %, more preferably 0 to 0.5 wt %, and particularly preferably 0 to 0.1 wt % of butanediol (preferably 1,2-butanediol, 2,3-butanediol, and / or 1,4-butanediol, the zero endpoint being excluded); 0 to 5 wt %, preferably 0 to 1 wt %, more preferably 0 to 0.5 wt %, and particularly preferably 0 to 0.1 wt % of pentanediol (preferably 1,2-pentanediol; the zero end point is excluded); 0 to 5 wt %, preferably 0 to 2 wt %, more preferably 0 to 1.5 wt % of hexanediol (preferably 1,2-hexanediol; the zero endpoint is excluded); Optionally, 0 to 5 wt %, preferably 0 to 1 wt %, more preferably 0 to 0.5 wt %, particularly preferably 0 to 0.1 wt % 【Chemistry 2】 The method according to any one of claims 1 to 6, comprising:

8. The bio-based crude ethylene glycol further optionally comprises: 0 to 5 wt %, preferably 0 to 1 wt %, more preferably 0 to 0.1 wt % of 1,2-propylene glycol; 0 to 5 wt %, preferably 0 to 1 wt %, more preferably 0 to 0.1 wt % diethylene glycol; The method according to any one of claims 1 to 7, comprising:

9. 9. The method of any one of claims 1 to 8, wherein the dehydration is achieved by rectification.

10. 10. The method of any one of claims 1 to 9, wherein the ultraviolet transmittance at 220 nm, 275 nm, and 350 nm of the bio-based crude ethylene glycol feedstock fails to meet at least one requirement specified for premium grade production of polyester-grade ethylene glycol.

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