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WO2025026824A1 - Procédé de réduction de la quantité de 1,2-pentanediol à partir d'éthylène glycol - Google Patents

Procédé de réduction de la quantité de 1,2-pentanediol à partir d'éthylène glycol Download PDF

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Publication number
WO2025026824A1
WO2025026824A1 PCT/EP2024/070871 EP2024070871W WO2025026824A1 WO 2025026824 A1 WO2025026824 A1 WO 2025026824A1 EP 2024070871 W EP2024070871 W EP 2024070871W WO 2025026824 A1 WO2025026824 A1 WO 2025026824A1
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WIPO (PCT)
Prior art keywords
entrainer
column
pentanediol
ethylene glycol
process according
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Application number
PCT/EP2024/070871
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English (en)
Inventor
Davide ANSOVINI
Faezeh ESMAEILI
Benjamin Mckay
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Avantium Knowledge Centre BV
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Avantium Knowledge Centre BV
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Publication of WO2025026824A1 publication Critical patent/WO2025026824A1/fr
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
    • C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
    • C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
    • C07C29/84—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation by extractive distillation

Definitions

  • the present invention relates to a process for reducing the amount of 1,2-pentanediol from a mixture rich in ethylene glycol, and which mixture comprises a small amount of 1,2-pentanediol.
  • the process comprises extractive distillation using an entrainer in said extractive distillation having a Hansen solubility parameter 6H of between 5 and 15 and the entrainer having a boiling point at atmospheric pressure of at least 200°C.
  • WO 2016/114661 discloses a continuous process for preparation of ethylene glycol from a carbohydrate source. Said process is carried out in a stirred tank reactor (CSTR) in which a catalyst system is present. Said catalyst system comprises a tungsten compound and at least one hydrogenolysis metal. The hydrogenolysis metal is preferably present in the form of a catalyst supported on a carrier. Such heterogeneous catalyst particles can fairly easily be separated from the effluent stream and added back.
  • CSTR stirred tank reactor
  • the liquid effluent obtained is usually subjected to a series of separation steps, e.g. to separate the tungsten compound used as co-catalyst (or a tungsten compound that is formed by the process), but also to separate the various (volatile) alcohols, polyols and glycols produced.
  • the target product in the processes like the reference above and similar processes is ethylene glycol. Whilst such processes may have a selectivity for ethylene glycol of about 40 to 70%, considerable amounts of other components are also produced, mainly monopropylene glycol (MPG), but also polyols like glycerol, sorbitol and erythritol.
  • MPG monopropylene glycol
  • the mixture produced usually contains also other glycols and diols next to MEG and MPG, such as 1,2- butanediol and 1,4-butanediol.
  • glycols and diols next to MEG and MPG such as 1,2- butanediol and 1,4-butanediol.
  • 1,2-butanediol Whilst the separation of e.g. 1,2-butanediol from ethylene glycol in the context of the conversion of carbohydrates to ethylene glycol has been widely researched, less work seems to have been done on removing 1,2-pentanediol from mixtures which are rich in ethylene glycol. In the processes such as in WO 2016/114661 and similar 1,2-pentanediol is formed in amounts up to 1 to 2% (by weight, based on ethylene glycol produced).
  • the problem with removing 1,2-pentanediol from ethylene glycol to a high degree, preferably such that the ethylene glycol has sufficient purity for use in the manufacturing of polyester (in short: polyester-grade EG) is that 1,2-pentanediol forms an azeotrope with ethylene glycol.
  • polyester-grade EG polyester-grade EG
  • This azeotropic mixture is then separated by the addition of an extractant and by filtration.
  • the filtrate is a mixed solution of ethylene glycol and an extractant, and the filter cake is an azeotropic agent.
  • the entrainer can be recycled after it has been recovered.
  • the separated ethylene glycol and extractant mixture is subjected to atmospheric or vacuum distillation in a rectification column to enable efficient separation of ethylene glycol from the extractant, to obtain an ethylene glycol product, and to circulate the extractant.
  • This requires both an entrainer and an extractant, and several unit operations (and associated equipment) to operate this process. Also, this requires that all of the ethylene glycol is processed through the entrainer recovery column, which is undesired as it is a large volume and as it risks thermal damage to the ethylene glycol.
  • WO 2017/050847 discloses a process for extractive distillation to remove 1,2-butanediol from ethylene glycol, using as extractant C3-C6 sugar alcohols, e.g. glycerol.
  • the extractive distillation is such that the ethylene glycol is extracted by the extractant: 1,2-butanediol and propylene glycol (and side products 2,3 butanediol, 1,2 pentanediol, 2,3-pentanediol, 1,2-hexanol and 1,2 heptanol) are removed at the top of the extraction distillation column, and at the bottom the mixture of ethylene glycol and extractant are obtained.
  • WO 2022/073923 discloses extractive distillation to remove 1,2-butanediol from MEG, using extractive distillation using a C3-C6 sugar alcohol or C4-C6 polyol as extractant. Similar to the previous reference W02017/050847, the desired diol (MEG) is obtained at the bottom stream together with the extractant. The diol to be removed (1,2-butanediol) is removed at the top. This case suffers from the same disadvantages as WO 2017/050847. Both WO 2017/050847 and WO 2022/073923 deal with removing 1,2-butanediol from MEG. However, there is no evidence of the methods of these two references being able to remove 1,2-pentanediol from MEG.
  • a purification process that allows reducing the amount of 1,2-pentanediol present in a mixture comprising at least 80% (preferably at least 90%) by weight of ethylene glycol and from 0.2 to 5% by weight of 1,2-pentanediol.
  • the amount of ethylene glycol that is lost in such purification process is minimized, e.g. less than 10% of the ethylene glycol of the mixture.
  • the number of unit operations required is as low as possible and that the process preferably does not have the disadvantages of the prior art.
  • the above objective(s) may be achieved, at least in part, by a process for reducing the content of 1,2-pentanediol in a mixture comprising 90-99.9% by weight ethylene glycol and 0.05-5% by weight 1,2-pentanediol by extractive distillation, using an entrainer in said extractive distillation having a Hansen solubility parameter 6H of between 5 and 15 and the entrainer having a boiling point at atmospheric pressure of at least 200°C.
  • the entrainer further has a Hansen solubility parameter 6P of between 2 and 13, preferably of between 3 and 11, more preferably between 3.7 and 10, and most preferably between 3.8 and 9.
  • said entrainer further has a Hansen solubility parameter 6D of between 15 and 20, preferably of between 15 and 18.
  • a Hansen solubility parameter 6H it is preferred that said entrainer has a Hansen solubility parameter 6H of between 5 and 15, and more preferably of between 7 and 13.
  • Suitable entrainers are preferably selected from a C6-C10 glycol ether, or a C9-C18 primary or secondary aliphatic unbranched alcohol, and mixtures thereof.
  • strainer herein encompasses pure compounds but also mixtures of compounds having the Hansen solubility parameters and boiling point claimed.
  • entrainers suitable for the purpose have in common that they have a Hansen solubility parameter 6H of between 5 and 15 (and preferably a Hansen solubility parameter 6P of between 2 and 13, and a Hansen solubility parameter 6D of between 15 and 20). Reducing the amount of 1,2-pentanediol in ethylene glycol was problematic, in particular when present in small amounts of e.g. 0.5-2%, due to formation of an azeotrope between 1,2-pentanediol and ethylene glycol. With the present method, it was found that the amount of 1,2-pentanediol present in a composition mainly comprising monoethylene glycol can be reduced to a substantial degree. For practical reasons (in view of the temperatures involved), the entrainer used in the present method has a boiling point of at least 200°C, at atmospheric pressure.
  • the entrainer for the present invention is selected from a C6-C10 glycol ether, or a C9-C18, preferably C10-C12, primary or secondary aliphatic unbranched alcohol, and mixtures thereof.
  • a "C6-C10 glycol ether” herein means a glycol ether having from 6 to 10 (including 6 and 10) carbon atoms in its formula.
  • a "C9-C18 primary or secondary aliphatic unbranched alcohol” herein means a primary or secondary aliphatic unbranched alcohol containing from 9 to 18 carbon atoms.
  • the entrainer when such is a glycol ether, such is selected from the group consisting of as appears in table 1, and mixtures thereof. Table 1 also gives the Hansen solubility parameters of the individual compounds.
  • glycol ethers in the present invention.
  • said glycol ether is preferably selected from the group consisting of triethylene glycol monoethyl ether, triethyleneglycol monobutyl ether, and mixtures thereof.
  • the entrainers may also be a C9-C18, preferably C10-C12, primary or secondary aliphatic unbranched alcohol. Following this (and the requirement that the boiling point at atmospheric conditions should be at least 200°C), it is preferred that in the process of the present invention, the entrainer, when such is a alcohol such is selected from the group consisting of as appears in table 2, and mixtures thereof.
  • a further suitable entrainer for the purpose of the invention is triethylphosphate.
  • This compound has a 6D of 16.7, a 6P of 11.4, and a 6H of 9.2.
  • the entrainer is a primary or secondary aliphatic unbranched alcohol
  • preferred alcohols for such are 1-dodecanol and 2- decanol.
  • Preferred glycol ethers in this invention are: triethyleneglycol monoethyl ether, triethyleneglycol monobutyl ether.
  • the entrainer is selected from triethyleneglycol monoethyl ether, triethyleneglycol monobutyl ether, 1-dodecanol and 2-decanol, and mixtures thereof.
  • the actual extractive distillation can be carried out by a process, wherein said process comprises: a) feeding said mixture to a distillation column 1, b) feeding to said distillation column 1 said entrainer, c) removing ethylene glycol from the top section of the column, d) removing from the bottom section of the distillation column 1 a mixture comprising entrainer and 1,2-pentanediol.
  • the ethylene glycol obtained in c) preferably has an amount of 1,2-pentanediol which is 2 to 20% by weight of the amount of 1,2-pentanediol of the mixture fed to distillation column 1 in a).
  • the above process has the advantage, compared to the prior art processes, that the ethylene glycol is obtained as a relatively pure component (containing less 1,2, -pentanediol that the feed) without being mixed with the entrainer. Rather, the entrainer contains the component to be removed: 1,2-pentanediol.
  • the invention further relates to a process comprising: feeding the mixture comprising entrainer and 1,2-pentanediol obtained in step d) to a column 2 yielding regenerated entrainer at the bottom section of column 2 and a mixture comprising entrainer and 1,2-pentanediol at the top section of column 2, combining said regenerated entrainer with feeding of the entrainer of b) to column 1.
  • the distillation in column 1, to which is fed the (crude) ethylene glycol to be purified (which thus contains some 1,2-pentanediol, e.g. between 0.05-5%, preferably between 0.1 and 3% by weight on the crude ethylene glycol) can be carried out in a distillation column as known in the art.
  • the feed of the stream to be purified is neither added near the top, nor near the bottom section of column 1.
  • the feed is added in the middle half of the column (between the top quarter and the bottom quarter). This is to be understood as: if column 1 has 100 theoretical stages, the feed to be purified is preferably added between stages 25 and 75 of this column. Also, it is generally preferred that the entrainer is added above the feed.
  • feeding the mixture comprising ethylene glycol and 1,2-pentanediol to column 1 in a) is at a stage N of the column and wherein the feeding of the entrainer to column 1 in b) is at a stage M of the column, wherein stage M is above stage N.
  • the entrainer is preferably to be fed at a point in the column above that of the feed of the crude ethylene glycol
  • said distillation column 1 preferably has two inlets.
  • the distillation column 1 is connected to a reboiler at the bottoms section and a condenser at the top section.
  • the weight ratio of entrainer fed to column 1 : mixture fed to column 1 is preferably from 15 : 1 to 1: 1 for a good operation, such e.g. depending on the amount of 1,2-pentanediol to be removed, and the entrainer used. More preferably, such ratio is between 12 : 1 and 2 : 1.
  • the separation process according to the present invention is preferably carried out downstream of a hydrogenolysis reactor in which carbohydrates are converted with hydrogen, in the presence of catalysts, to ethylene glycol.
  • Propylene glycol is usually a by-product, next to 1,2-pentanediol, but in larger quantities than 1,2-pentanediol.
  • prior to the now claimed separation process there are one or more other separation processes. Downstream of the reactor and prior to the now claimed separation process there is preferably first a removal of volatiles and water.
  • there is preferably also a separation of high boiling side products higher boiling than ethylene glycol and propylene glycol
  • high boiling side products higher boiling than ethylene glycol and propylene glycol
  • the mixture fed to column 1 in a) comprises less than 1 % by weight of propylene glycol.
  • the pressure of the reboiler of this column 1 is preferably between 20 and 500 mbara, more preferably at a pressure of between 40 and 250 mbara.
  • the bottom of the first column preferably has a pressure of between 20 and 500 mbara, more preferably at a pressure of between 40 and 250 mbara.
  • the condenser of this column 1 preferably operates at a temperature of between 80 and 160°C, more preferably between 100 and 140°C.
  • the top of the first column preferably has a temperature of between 80 and 160°C, more preferably between 100 and 140°C.
  • the reboiler of column 1 preferably operates at a temperature of between 160 and 220°, and more preferably between 165 and 210°C.
  • the bottom of the first column preferably has a temperature of between 160 and 220°, and more preferably between 165 and 210°C.
  • this column 1 preferably operates with a reflux ratio of between 0.5 and 3, and preferably between 0.7 and 2.4, the number of theoretical stages of this column, including condenser and reboiler, is preferably between 30 and 150, and more preferably between 40 and 120, even more preferably between 40 and 100.
  • first column such as the interior can be conventional for extractive distillation, as is known to the skilled person.
  • the separation by column 1 produces ethylene glycol with a reduced amount of 1,2-pentanediol, next to a stream of entrainer which contains, amongst others, 1,2-pentanediol. Apart from pentanediol, it was found that surprisingly other minor products from the hydrogenolysis of sugar (e.g. 1,2-hexanediol) are also removed with the entrainers in the process of the present invention. This is an added benefit of the present invention.
  • the entrainer loaded with 1,2-pentanediol (and optionally other diols like 1,2-hexanediol or 1,2- butanediol) will need to be regenerated for re-use.
  • This regeneration can be done in a way as known in the art for regenerating entrainers in extractive distillation using a regeneration column (column 2 in the process set out herein).
  • the reboiler of this column 2 preferably operates at a pressure of between 20 and 400 mbara, preferably being between 30 and 200 mbara
  • the condenser is preferably operating at a temperature of between 90 and 180°C, more preferably between 100 and 160°C
  • the reboiler of column 2 operating at a temperature of between 150 and 220°, preferably between 165 and 210°C
  • the a reflux ratio is preferably between 10 and 100, more preferably between 15 and 70
  • the number of theoretical stages of such column is preferably between 20 and 60, more preferably between 30 and 60.
  • regeneration column such as the interior can be conventional for a column for regenerating an entrainer in extractive distillation, as is known to the skilled person.
  • Example 1 is a laboratory screening of the relative volatility of ethylene glycol and 1,2-pentanediol, and how such is modified by the presence of an entrainer. This provides a prediction of the suitability of an entrainer for the purpose. The relative volatility is determined by gas chromatography of the headspace.
  • the entrainers tested were: Triethylene glycol monobutyl ether, Propylene glycol monophenyl ether (l-Phenoxy-2-propanol), Dodecanol, Triethylphosphate, Diethylene Glycol Monoethyl Ether Acetate, 2-Decanol, diethylene glycol monobutyl ether, Di(ethylene glycol) hexyl ether, Tripropylene glycol methyl ether, Dipropylene glycol methyl ether, Di(ethylene glycol) divinyl ether, Ethylene glycol monobenzyl ether.
  • the content of the vial was thoroughly mixed to ensure homogeneous distribution of content in the liquid phase. Subsequently, the vials were placed in a Headspace-Gas chromatography (HS-GC) autosampler where the vials were heated to 130°C. After 60 minutes, the vial's headspace which contains the gas content was sampled and analyzed by the machine. This injection resulted in a chromatogram where the separated peaks each represent one of the mixtures' components, and the area under the peak indicates their respective concentration in the gas phase.
  • HS-GC Headspace-Gas chromatography
  • a n is HS-GCMS area of component n with entrainer addition
  • a n ,o is HS-GCMS area of component n in reference sample (no entrainer addition)
  • component 1 (here: ethylene glycol)
  • the relative volatility in distillation is an indication of feasible separation of the components in a mixture. Higher relative volatility shows that the relative concentration of component 1 to 2 is higher in the gas phase than in liquid phase. Hence, in a single stage separation such as in this test for triethylene glycol monobutyl ether, the ethylene glycol is shown to be more volatile than the 1,2-pentanediol in the presence of triethylene glycol monobutyl ether. And so on for other entrainers.
  • composition of the model feed was: a mixture of 97.72 wt% ethylene glycol, 1.68 wt% 1,2-pentanediol and 0.54 wt% 1,2-hexanediol and some minor components (other impurities).
  • the ethylene glycol-containing feed mixture (at 78-85°C and ambient pressure) and triethylene glycol monobutyl ether entrainer (at 111-112°C and ambient pressure) were introduced (the entrainer higher than the ethylene glycol feed mixture) into a maximum 100 theoretical stage column where the purified propylene glycol is separated in the distillate and the impurities of the feed leave the column with the entrainer as bottom stream.
  • the column was operated at 116°C and 50 mbara condenser conditions, with a column pressure drop of 13.5-15 mbara. A reflux ratio of 2 was used throughout the experiment.
  • bottom stream refers the percentage of the stated component that is present in the bottom stream, based on the amount of said component in the EG feed stream.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention concerne un procédé d'élimination de 1,2-pentanediol à partir d'un mélange riche en éthylène glycol, ledit procédé comprenant une distillation extractive à l'aide d'un agent d'entraînement dans ladite distillation extractive ayant un paramètre de solubilité de Hansen δH compris entre 5 et 15 et l'agent d'entraînement ayant un point d'ébullition à pression atmosphérique d'au moins 200° C.
PCT/EP2024/070871 2023-08-01 2024-07-23 Procédé de réduction de la quantité de 1,2-pentanediol à partir d'éthylène glycol Pending WO2025026824A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP23189052 2023-08-01
EP23189052.6 2023-08-01

Publications (1)

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WO2025026824A1 true WO2025026824A1 (fr) 2025-02-06

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PCT/EP2024/070871 Pending WO2025026824A1 (fr) 2023-08-01 2024-07-23 Procédé de réduction de la quantité de 1,2-pentanediol à partir d'éthylène glycol

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104230658A (zh) 2014-09-26 2014-12-24 吉林化工学院 一种从玉米发酵处理液中分离乙二醇和1,2-戊二醇的新方法
CN104370696A (zh) 2014-10-21 2015-02-25 吉林化工学院 一种分离乙二醇和1,2-戊二醇的新方法
WO2016114661A1 (fr) 2015-01-13 2016-07-21 Avantium Knowledge Centre B.V. Procédé continu de préparation d'éthylène glycol à partir d'une source de glucides
WO2017050847A1 (fr) 2015-09-23 2017-03-30 Shell Internationale Research Maatschappij B.V. Procédé de séparation de glycols
WO2022073923A1 (fr) 2020-10-07 2022-04-14 Shell Internationale Research Maatschappij B.V. Procédé de production de glycols

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104230658A (zh) 2014-09-26 2014-12-24 吉林化工学院 一种从玉米发酵处理液中分离乙二醇和1,2-戊二醇的新方法
CN104370696A (zh) 2014-10-21 2015-02-25 吉林化工学院 一种分离乙二醇和1,2-戊二醇的新方法
WO2016114661A1 (fr) 2015-01-13 2016-07-21 Avantium Knowledge Centre B.V. Procédé continu de préparation d'éthylène glycol à partir d'une source de glucides
WO2017050847A1 (fr) 2015-09-23 2017-03-30 Shell Internationale Research Maatschappij B.V. Procédé de séparation de glycols
WO2022073923A1 (fr) 2020-10-07 2022-04-14 Shell Internationale Research Maatschappij B.V. Procédé de production de glycols

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