WO2000017180A1 - Procede de production continue d'une solution aqueuse d'oxyde d'ethylene - Google Patents

Procede de production continue d'une solution aqueuse d'oxyde d'ethylene Download PDF

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Publication number
WO2000017180A1
WO2000017180A1 PCT/EP1999/006942 EP9906942W WO0017180A1 WO 2000017180 A1 WO2000017180 A1 WO 2000017180A1 EP 9906942 W EP9906942 W EP 9906942W WO 0017180 A1 WO0017180 A1 WO 0017180A1
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WO
WIPO (PCT)
Prior art keywords
absorber
ethylene oxide
water
glycol
reactor
Prior art date
Application number
PCT/EP1999/006942
Other languages
German (de)
English (en)
Inventor
Till Adrian
Hans Hasse
Frans Vansant
Gerhard Theis
Original Assignee
Basf Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Basf Aktiengesellschaft filed Critical Basf Aktiengesellschaft
Priority to AU61928/99A priority Critical patent/AU6192899A/en
Publication of WO2000017180A1 publication Critical patent/WO2000017180A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/32—Separation; Purification
    • 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
    • C07C29/09—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis
    • C07C29/10—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of ethers, including cyclic ethers, e.g. oxiranes
    • C07C29/103—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of ethers, including cyclic ethers, e.g. oxiranes of cyclic ethers
    • C07C29/106—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of ethers, including cyclic ethers, e.g. oxiranes of cyclic ethers of oxiranes

Definitions

  • the invention relates to a process for the continuous production of an aqueous ethylene oxide solution and to the use of the solution prepared thereafter as an entry into a glycol reactor.
  • Ethylene oxide (hereinafter referred to as EO) is produced on an industrial scale by direct oxidation of ethylene on silver oxide catalysts with molecular oxygen or with air. Such methods are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, Fifth Edition, Vol. A 10, pages 117ff. Ethylene and oxygen are then placed in a circulating gas stream which, in addition to the reactants, contains inert gases and the by-product of total ethylene oxidation, carbon dioxide.
  • the cooled reactor discharge is optionally first quenched with a NaOH solution in order to wash out organic acids, in particular formic acid and acetic acid, and also high-boiling secondary components. These components can be removed from the cycle gas system via a quench bleed.
  • the EO absorber In an EO absorber, which is operated at approx. 16 bar and approx. 30 to 40 ° C, the EO with a large wash water flow (necessary for the absorption of 1 t EO from 25 t cycle gas in approx. 35 t wash water) is almost completely washed out of the cycle gas.
  • the pressure in the absorber is predetermined by the pressure in the cycle gas system. Typically 5 to 100 ppm EO remain in the cycle gas.
  • the cycle gas After a potash wash to remove carbon dioxide, the cycle gas is again enriched with ethylene and oxygen and fed to the EO reactor.
  • the aqueous solution obtained in the absorber also contains traces of the other components contained in the cycle gas.
  • the EO is then made in an EO desorber (EO stripper) desorbed the loaded wash water.
  • the stripper vapors obtained contain approx. 50% by weight water and approx. 50% by weight EO as well as the gases contained in the loaded wash water.
  • the depleted wash water is returned to the EO desorber as cycle water. Since the EO is partially hydrolyzed to glycols in the EO desorber, these are removed from the EO desorber via the so-called glycol bleed.
  • the desorber vapors are first condensed, then the dissolved gases are stripped out of the condensate in a so-called light-end column and returned to the cycle gas system.
  • the gas-free, approximately 50% aqueous EO solution obtained in this way is partially distilled to pure EO in a distillation column or, after water has been added, converted to an aqueous glycol solution in a glycol reactor.
  • glycol A significant proportion of the worldwide ethylene oxide production is processed with increasing tendency to monoethylene glycol, hereinafter referred to as glycol.
  • glycol monoethylene glycol
  • a water / EO mixture with a water / EO mass ratio in the range of approximately 5 to 20 is assumed.
  • the high excess of water is necessary in order to suppress as much as possible the proportion of higher glycols (di-, tri-polyethylene glycols) which arise as a result of subsequent reactions in the hydrolysis.
  • Water / EO ratios above 20 are uneconomical, since then the glycol reactor discharge can no longer be dewatered in heat-integrated columns.
  • the solution is based on a process for the continuous production of an aqueous EO solution by absorption of EO from a gas mixture containing 1.5 to 4 mol%, preferably 2.5 to 3 mol%, of EO in washing water in an absorber.
  • the invention is characterized in that the absorbate drawn off directly from the absorber has a water / EO ratio of 5 to 20, preferably 10 to 15.
  • the EO concentration of the absorbate can be adjusted by suitable selection of the operating parameters of the absorber in such a way that it can be introduced directly into a glycol reactor and the subsequent dewatering can be carried out economically in heat-integrated columns.
  • the gas mixture containing EO is preferably the reaction gas from an ethylene oxidation with air or oxygen.
  • the composition of the gas mixture at the absorber inlet is determined by the procedure of the ethylene oxidation; the ethylene conversion is generally set to approximately 10%, in particular for safety reasons and reasons of selectivity. Accordingly, the gas mixture contains 1.5 to 4 mol%, preferably 2.5 to 3 mol% of ethylene oxide, furthermore in particular unreacted ethylene and oxygen, methane and ethane as diluent gases and the reaction products of the total oxidation of ethylene, carbon dioxide and water, and the inert gases argon and nitrogen.
  • the preferred operating parameters of the absorber are:
  • the gas mixture containing EO is compressed to a pressure of 15 to 30 bar, preferably 20 to 25 bar, in a coupled compressor / turbine system arranged in front of the absorber, and the gas freed from EO is then expanded again.
  • This preferred embodiment of the apparatus makes it possible to ensure the operating pressure of the absorber without changing the pressure of the circulating gas in the EO reactor, usually from 10 to 20 bar. Due to the coupled compressor / turbine system, the cycle gas is initially compressed in an almost energy-neutral manner from the EO reactor pressure to the higher absorber pressure and, after washing out the EO in the absorber, is expanded again to the EO reactor pressure. At low differential pressures, the turbine can be dispensed with to relax.
  • a quench is preferably arranged between the EO reactor and the absorber.
  • the temperature in the absorber there are various possibilities for setting the temperature in the absorber, in particular the pre-cooling of the feed streams (in the present case the gas mixture containing EO and washing water), but also heat removal, by means of internal and / or external cooling circuits.
  • the heat of solution from EO can result in temperatures that are up to 10 ° C higher than the temperature values given for the top or bottom. It is particularly advantageous to remove the heat in the lower half of the absorber.
  • the cold absorbate ie the loaded receiver phase, to cool the incoming gas mixture containing EO.
  • the wash water fed to the absorber is preferably cooled to a temperature of 10 to 40 ° C., preferably 15 to 35 ° C., particularly preferably 15 to 20 ° C.
  • the wash water used as an auxiliary for absorption can contain up to 400 ppm of secondary components, in particular up to 5 ppm of ethylene oxide. In a particularly preferred manner, all or most of the wash water comes from the dewatering of the discharge from a glycol reactor.
  • the aqueous EO solution obtained by the process according to the invention can preferably be used as an immediate entry in a glycol reactor.
  • a water / EO mixture is thus drawn off directly from the absorber, the mass ratio of which no longer has to be changed before being fed to a glycol reactor.
  • this eliminates the energy-intensive concentration of the absorbate in an EO desorber and the investment costs for the desorber. Since the EO desorber is no longer required, there is no glycol bleed flow, which requires additional apparatus to work it up in the process currently practiced.
  • the glycol bleed stream is used to remove not only glycols but also secondary components, in particular aldehydes, such as formaldehyde and acetaldehyde. It has surprisingly been found that the loss of the glycol bleed stream, i.e. the lack of removal of secondary components in front of the glycol reactor has no negative influence on the quality of the product glycol, particularly with regard to UV absorption and the concentration of secondary components which are harmful to the specification.
  • the so-called lightend column which is used in the current process for separating dissolved gases from the absorbate, can be dispensed with, since the presence of dissolved gases in the glycol reactor has no negative influence on the quality of the product glycol.
  • the separation of the dissolved gases from the absorbate upstream of the glycol reactor is technically difficult and can only be achieved with the use of several apparatuses, since the volatile EO is also expelled when the liquid is stripped.
  • safety-related problems arise since the gas phase obtained by stripping has a very high EO content. According to the invention, this process-technically difficult separation of volatile gases upstream of the glycol reactor can thus be dispensed with.
  • Dissolved gases can be separated off after the glycol reactor, which is easy to implement in terms of process technology, since the EO has now completely reacted.
  • a separation of dissolved gases regardless of whether before or after the glycol reactor, makes economic sense, since the ethylene contained in it should be fed back into the cycle gas system for reasons of educt utilization.
  • An absorber is shown schematically in FIG.
  • the actual design can have further additional devices, in particular a pre-quench for cooling the gas mixture to be supplied.
  • a pre-quench for cooling the gas mixture to be supplied.
  • the organic acids contained in the cycle gas can be bound by neutralization.
  • a raw gas containing the gas to be separated (stream 1), in the present case an EO-containing gas mixture, and at the upper end of the absorber, in countercurrent, a solvent (stream 3), in the present case washing water, is fed.
  • a solvent in the present case washing water
  • the absorbate in the present case water loaded with ethylene oxide
  • stream 2 at the top of the column that from deducted gas cleaned gas mixture
  • Example 2 shows the influence of the EO concentration in the supplied gas mixture (stream 1) on the water / EO mass ratio in the absorbate.
  • the diagram shows that the water / EO mass ratio in the absorbate increases with increasing EO concentration in stream 1 for the range of an EO concentration of 2 to 3 mol% in stream 1 from approximately 17 to approximately 11.5 falls.
  • the diagram in FIG. 3 shows the influence of the EO concentration in stream 3 (wash water) on the water / EO mass ratio in the absorbate: with increasing EO concentration in stream 3, in the range from about 2 to 20 ppm, the water / EO mass ratio slightly, with values in the range around 13.
  • the diagram in FIG. 4 illustrates the influence of the EO concentration in the stream which is discharged at the top of the absorber (stream 2) on the water / EO mass ratio in the absorbate: after a sharp drop in the water / EO mass ratio of approx. 15 to approx. 13.2 with an increase in the EO concentration in stream 2 of approx. 2 to 5 ppm, the water / EO mass ratio drops slightly from approx. 13.2 to approx. 12.8 with an increase in the EO concentration in stream 2 from 5 to 10 ppm. With a further increase in the EO concentration in stream 2 to 50 ppm, the water / EO mass ratio in the absorbate changes only slightly from approximately 12.8 to around 12.5.
  • the diagram in FIG. 5 illustrates the influence of the operating pressure on the water / EO mass ratio in the absorbate: this drops from a value of 17 to a value of approximately 12 when the pressure increases from 15 to 30 bar.
  • FIG. 7 illustrates the influence of the bottom temperature in the absorber on the water / EO mass ratio in the absorbate: this increases linearly from 11.5 to approximately 14.2 with an increase in the bottom temperature from 15 to 35 ° C.
  • the head temperature was kept constant at 20 ° C.
  • the dependence of the water / EO mass ratio on the head temperature is shown in FIG. 8, the bottom temperature being regularly set at 5 ° C. higher than the head temperature. With an increase in the head temperature from 15 to 30 ° C (and a corresponding increase in the bottom temperature), the water / EO mass ratio rose from approximately 11 to 17.5.
  • FIG. 9 illustrates the influence of the theoretical number of stages on the water / EO mass ratio in the absorbate: an upper limit of approximately 20 for the water / EO mass ratio is achieved with a minimum number of stages of 9; the ratio mentioned decreases almost exponentially with an increasing number of stages to a value of approximately 12.3 with a number of 30 stages. claims

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

Abstract

L'invention concerne un procédé de production continue d'une solution aqueuse d'oxyde d'éthylène par absorption d'oxyde d'éthylène à partir d'un mélange gazeux contenant 1,5 à 4 % en mole, de préférence 2,5 à 3 % en mole d'oxyde d'éthylène dans l'eau de lavage d'un absorbeur. L'absorbat directement retiré de l'absorbeur a un rapport de masse eau/oxyde d'éthylène de 5 à 20, de préférence de 10 à 15. L'absorbat est particulièrement adapté à l'alimentation directe d'un réacteur consécutif destiné à la production d'alcool éthylénique.
PCT/EP1999/006942 1998-09-23 1999-09-20 Procede de production continue d'une solution aqueuse d'oxyde d'ethylene WO2000017180A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU61928/99A AU6192899A (en) 1998-09-23 1999-09-20 Method for the continuous production of an aqueous ethylene oxide solution

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843721A DE19843721A1 (de) 1998-09-23 1998-09-23 Verfahren zur kontinuierlichen Herstellung einer wässrigen Ethylenoxid-Lösung
DE19843721.8 1998-09-23

Publications (1)

Publication Number Publication Date
WO2000017180A1 true WO2000017180A1 (fr) 2000-03-30

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Application Number Title Priority Date Filing Date
PCT/EP1999/006942 WO2000017180A1 (fr) 1998-09-23 1999-09-20 Procede de production continue d'une solution aqueuse d'oxyde d'ethylene

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AU (1) AU6192899A (fr)
DE (1) DE19843721A1 (fr)
WO (1) WO2000017180A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2291363B1 (fr) 2008-02-23 2015-08-26 Brian Ozero Procédé amélioré de récupération d'oxyde d'éthylène

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8049044B2 (en) * 2002-12-23 2011-11-01 Shell Oil Company Remediation process and apparatus

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3964980A (en) * 1975-03-24 1976-06-22 Halcon International, Inc. Process for the recovery of ethylene oxide
US4469492A (en) * 1981-03-02 1984-09-04 Vincenzo Lagana Process for the isothermal absorption of ethylene oxide using film absorbers
EP0181273A1 (fr) * 1984-10-31 1986-05-14 Elf Atochem S.A. Procédé pour concentrer des solutions aqueuses diluées d'oxyde d'éthylène

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3964980A (en) * 1975-03-24 1976-06-22 Halcon International, Inc. Process for the recovery of ethylene oxide
US4469492A (en) * 1981-03-02 1984-09-04 Vincenzo Lagana Process for the isothermal absorption of ethylene oxide using film absorbers
EP0181273A1 (fr) * 1984-10-31 1986-05-14 Elf Atochem S.A. Procédé pour concentrer des solutions aqueuses diluées d'oxyde d'éthylène

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
GERHARTZ: "Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., Volume A10", 1987, VCH VERLAGSGESELLSCHAFT, WEINHEIM (D), XP002131629 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2291363B1 (fr) 2008-02-23 2015-08-26 Brian Ozero Procédé amélioré de récupération d'oxyde d'éthylène

Also Published As

Publication number Publication date
DE19843721A1 (de) 2000-03-30
AU6192899A (en) 2000-04-10

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