EP1001954A1 - Method for trioxan isolation - Google Patents

Method for trioxan isolation

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Publication number
EP1001954A1
EP1001954A1 EP98939607A EP98939607A EP1001954A1 EP 1001954 A1 EP1001954 A1 EP 1001954A1 EP 98939607 A EP98939607 A EP 98939607A EP 98939607 A EP98939607 A EP 98939607A EP 1001954 A1 EP1001954 A1 EP 1001954A1
Authority
EP
European Patent Office
Prior art keywords
trioxane
mixture
formaldehyde
water
stream
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP98939607A
Other languages
German (de)
French (fr)
Inventor
Reinhard Freyhof
Stefan Bitterlich
Hugues Vandenmersch
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF SE
Original Assignee
BASF SE
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 SE filed Critical BASF SE
Publication of EP1001954A1 publication Critical patent/EP1001954A1/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
    • B01D61/362—Pervaporation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D323/00—Heterocyclic compounds containing more than two oxygen atoms as the only ring hetero atoms
    • C07D323/04—Six-membered rings
    • C07D323/06—Trioxane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S159/00—Concentrating evaporators
    • Y10S159/27—Micropores
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S159/00—Concentrating evaporators
    • Y10S159/28—Porous member

Definitions

  • the invention relates to a process for separating trioxane from an aqueous mixture which consists essentially of trioxane, formaldehyde and water.
  • trioxane creates an azeotropic mixture that consists essentially of trioxane, water and formaldehyde.
  • Trioxane is extracted from this mixture with the aid of an entrainer, e.g. chlorine-containing entraining agents such as methylene chloride or benzene are separated off.
  • an entrainer e.g. chlorine-containing entraining agents such as methylene chloride or benzene are separated off.
  • Other constituents of the mixture in minor amounts are usually formic acid, methylal and dimethoxy dimethyl ester.
  • the entrainer is recovered and returned to the extractive distillation.
  • large amounts of entraining agents have to be used and recovered with high energy expenditure. Inevitable emissions have to be disposed of, since methylene chloride and benzene are classified as dangerous pollutants.
  • EP-A 596 381 discloses a process for the separation of trioxane which removes water from the azeotropic mixture by pervaporation.
  • aqueous mixture consisting of 65% by weight of trioxane, 27.5% by weight of water and 7.5% by weight of formaldehyde is in a pervaporation unit 2 which has a membrane 3 made of polyvinyl alcohol from Sulzer Chemtech GmbH -Membrantechnik, D-66540 Neun Wegn / Saar contains, water (line 4) withdrawn.
  • the separation takes place at 90 ° C.
  • the pressure on the retentate side 5 is 1 bar, on the permeate side 6 50 mbar.
  • the permeate obtained is water and the retentate is a mixture of 84% by weight of trioxane, 10% by weight of formaldehyde and 6% by weight of water (line 7).
  • the retentate is decomposed in a rectification column 8 under normal pressure into pure trioxane (bottom product, line 9) and an azeotropic mixture of trioxane, formaldehyde and water (top product, line 10).
  • This process has the disadvantage that it does not offer complete trioxane workup. A return of the column stream 10, for example before the pervaporation, would not make sense, since formaldehyde would accumulate.
  • the object of the present invention was to provide a process for separating trioxane from this azeotropic mixture, which offers the most complete possible possible recovery of the trioxane.
  • trioxane is removed from the mixture by pervaporation and the trioxane-enriched mixture (permeate) by rectification in trioxane and an azeotropic mixture of trioxane, water and formaldehyde.
  • the process according to the invention offers the advantages of a largely quantitative work-up of the reactor discharge with the most complete possible recovery of the trioxane and formaldehyde. No other feedstocks are required.
  • Stream 1 represents the reactor discharge which is produced in the production of trioxane. As a rule, this consists essentially of 35 to 45% by weight of trioxane, 35 to 45% by weight of water and 15 to 30% by weight of formaldehyde. Stream 1 is passed into a 1st rectification column K1, in which there is a separation into 2 fractions, stream 2 containing a mixture of water and formaldehyde and stream 3 containing the azeotropic mixture.
  • the distillation is preferably carried out in a rectification column K1, which can have up to 60 trays. As a rule, the distillation is carried out under normal pressure.
  • Stream 2 is then returned to the formaldehyde concentration.
  • the azeotropic mixture (stream 3) is transferred to a vaporization unit (PV) which contains suitable membranes for organophilic pervaporation.
  • the membranes used are usually pore-free polymer membranes, in which the permeating component dissolves and diffuses through the membrane.
  • Suitable membranes are, for example, those made from polydimethylsiloxane and polyether amide block copolymers.
  • the polydimethylsiloxane membrane preferably contains a hydrophobic zeolite.
  • the thickness of the membrane is preferably from 5 to 200 ⁇ m, preferably from 50 to 150 ⁇ m.
  • Such membranes are commercially available under the trade names Pervap® 1070 from Sulzer Chemtech GmbH-Membrantechnik and PEBA 40 from GSE (Gesellschaft für Spezialfolienponent).
  • the pervaporation is preferably carried out at temperatures from 70 to 120 ° C., preferably from 80 to 90 ° C. and a pressure of 1 to 3, preferably 1 to 1.5 bar on the retentate side and 10 to 150 mbar, preferably 10 to 20 mbar on the permeate side.
  • the stream 5 depleted in trioxane (retentate) is returned to the first distillation column K 1, while the stream 6 enriched with trioxane (permeate) is fed into a second distillation column K 2, in which rectification then takes place.
  • the trioxane fraction is the product and (stream 7) is fed into a reactor in which polyoxymethylenes are produced from trioxane.
  • aqueous mixture consisting of 40% by weight of trioxane, 40% by weight of water and 20% by weight of formaldehyde was in a first distillation column (Kl, 25 stages) under normal pressure in a water / formaldehyde stream (stream 2) and separated into an azeotropic mixture (stream 3).
  • Stream 3 was passed into the pervaporation unit, which contained a membrane of polydimethylsiloxane with a hydrophobic zeolite.
  • the total thickness was 200 ⁇ m
  • the support layer consisted of polyacrylonitrile.
  • the thickness of the separating layer was 15-20 ⁇ m. (Membrane Pervap® 1070 from Sulzer Chemtech GmbH-membrane technology). The separation took place at 80 ° C.
  • the pressure on the retentate side (5) was 1 bar and on the permeate side (6) 10 mbar.
  • the stream depleted in trioxane (stream 5) was fed to the first distillation column (K1).
  • the bottom stream from this distillation column was passed on to the formaldehyde concentration.
  • trioxane 98.4% by weight of trioxane, based on 3200 kg of trioxane used - 100% by weight of formaldehyde, based on 1600 kg of formaldehyde used

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Heterocyclic Compounds That Contain Two Or More Ring Oxygen Atoms (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention relates to a method for trioxan isolation from an aqueous mixture basically consisting of trioxan, water and formaldehyde. The method is characterized in that trioxan is withdrawn from the mixture by pervaporation and in that the trioxan enriched mixture (permeate) is separated by trioxan rectification and an azeotropic mixture of trioxan, water and formaldehyde.

Description

Verfahren zur Abtrennung von TrioxanProcess for the separation of trioxane
Beschreibungdescription
Die Erfindung betrifft ein Verfahren zur Abtrennung von Trioxan aus einem wäßrigen Gemisch, welches im wesentlichen aus Trioxan, Formaldehyd und Wasser besteht.The invention relates to a process for separating trioxane from an aqueous mixture which consists essentially of trioxane, formaldehyde and water.
Bei der Herstellung von Trioxan entsteht ein azeotropes Gemisch, das im wesentlichen aus Trioxan, Wasser und Formaldehyd besteht. Aus diesem Gemisch wird Trioxan extraktiv mit Hilfe eines Schleppmittels, wie z.B. chlorhaltige Schleppmittel wie Methylenchlorid oder Benzol abgetrennt. Weitere Bestandteile des Gemi- sches in untergeordneten Mengen sind in der Regel Ameisensäure, Methylal und Dirnethoxydimethylester. In einer nachfolgenden Destillation wird das Schleppmittel zurückgewonnen und der Extraktivdestillation wieder zugeführt. Bei diesem Verfahren müssen große Mengen Schleppmittel eingesetzt und mit hohem Energie - aufwand zurückgewonnen werden. Zwangsweise anfallende Emissionen müssen aufwendig entsorgt werden, da Methylenchlorid und Benzol als gefährliche Schadstoffe eingestuft sind.The production of trioxane creates an azeotropic mixture that consists essentially of trioxane, water and formaldehyde. Trioxane is extracted from this mixture with the aid of an entrainer, e.g. chlorine-containing entraining agents such as methylene chloride or benzene are separated off. Other constituents of the mixture in minor amounts are usually formic acid, methylal and dimethoxy dimethyl ester. In a subsequent distillation, the entrainer is recovered and returned to the extractive distillation. In this process, large amounts of entraining agents have to be used and recovered with high energy expenditure. Inevitable emissions have to be disposed of, since methylene chloride and benzene are classified as dangerous pollutants.
Aus der EP-A 596 381 ist ein Verfahren zur Abtrennung von Trioxan bekannt, welches Wasser durch Pervaporation aus dem azeotropen Gemisch entfernt.EP-A 596 381 discloses a process for the separation of trioxane which removes water from the azeotropic mixture by pervaporation.
Das Verfahren der EP-A 596 381 sei anhand der Abbildung 1 im folgenden kurz erläutert:The process of EP-A 596 381 is briefly explained below with reference to Figure 1:
Einem wäßrigen Gemisch (Leitung 1) bestehend aus 65 Gew.-% Trioxan, 27,5 Gew.-% Wasser und 7,5 Gew.-% Formaldehyd wird in einer Pervaporationseinheit 2, die eine Membran 3 aus Polyvinylalkohol der Firma Sulzer Chemtech GmbH-Membrantechnik, D-66540 Neun- kirchen/Saar enthält, Wasser (Leitung 4) entzogen. Die Trennung erfolgt bei 90°C. Der Druck auf der Retentatseite 5 beträgt 1 bar, auf der Permeatseite 6 50 mbar. Man erhält als Permeat Wasser und als Retentat ein Gemisch aus 84 Gew.-% Trioxan, 10 Gew. -% Formaldehyd und 6 Gew.-% Wasser (Leitung 7). Das Retentat wird in einer Rektifikationskolonne 8 unter Normaldruck in reines Trioxan (Sumpfprodukt, Leitung 9) und ein azeotropes Gemisch aus Trioxan, Formaldehyd und Wasser (Kopf rodukt, Leitung 10) zerlegt. Dieses Verfahren weist den Nachteil auf, daß es keine vollständige Trioxanaufarbeitung bietet. Eine Rückführung des Kolonnenstroms 10, beispielsweise vor die Pervaporation, wäre nicht sinnvoll, da sich Formaldehyd anreichern würde.An aqueous mixture (line 1) consisting of 65% by weight of trioxane, 27.5% by weight of water and 7.5% by weight of formaldehyde is in a pervaporation unit 2 which has a membrane 3 made of polyvinyl alcohol from Sulzer Chemtech GmbH -Membrantechnik, D-66540 Neunkirchen / Saar contains, water (line 4) withdrawn. The separation takes place at 90 ° C. The pressure on the retentate side 5 is 1 bar, on the permeate side 6 50 mbar. The permeate obtained is water and the retentate is a mixture of 84% by weight of trioxane, 10% by weight of formaldehyde and 6% by weight of water (line 7). The retentate is decomposed in a rectification column 8 under normal pressure into pure trioxane (bottom product, line 9) and an azeotropic mixture of trioxane, formaldehyde and water (top product, line 10). This process has the disadvantage that it does not offer complete trioxane workup. A return of the column stream 10, for example before the pervaporation, would not make sense, since formaldehyde would accumulate.
Aufgabe der vorliegenden Erfindung war es, ein Verfahren zur Abtrennung von Trioxan aus diesem azeotropen Gemisch bereit zu stellen, welches eine möglichst vollständige Gewinnung des Tri- oxans bietet.The object of the present invention was to provide a process for separating trioxane from this azeotropic mixture, which offers the most complete possible possible recovery of the trioxane.
Demgemäß wurde ein Verfahren zur Abtrennung von Trioxan aus einem wäßrigen Gemisch, das im wesentlichen aus Trioxan, Wasser und Formaldehyd besteht, gefunden, das dadurch gekennzeichnet ist, daß man dem Gemisch Trioxan durch Pervaporation entzieht und das an Trioxan angereicherte Gemisch (Permeat) durch Rektifikation in Trioxan und ein azeotropes Gemisch aus Trioxan, Wasser und Formaldehyd trennt.Accordingly, a process for the separation of trioxane from an aqueous mixture consisting essentially of trioxane, water and formaldehyde has been found, which is characterized in that trioxane is removed from the mixture by pervaporation and the trioxane-enriched mixture (permeate) by rectification in trioxane and an azeotropic mixture of trioxane, water and formaldehyde.
Bevorzugte Ausführungsformen sind den Unteransprüchen zu ent- nehmen.Preferred embodiments can be found in the subclaims.
Das erfindungsgemäße Verfahren bietet die Vorteile einer weitgehend quantitativen Aufarbeitung des Reaktoraustrages mit einer möglichst vollständigen Rückgewinnung des Trioxans und Formalde- hyds. Es sind darüber hinaus keine weiteren Einsatzstoffe erforderlich.The process according to the invention offers the advantages of a largely quantitative work-up of the reactor discharge with the most complete possible recovery of the trioxane and formaldehyde. No other feedstocks are required.
Das erfindungsgemäße Verfahren wird im folgenden anhand der Abbildung 2 erläutert.The method according to the invention is explained below with reference to Figure 2.
Der Strom 1 stellt den Reaktoraustrag dar, der bei der Herstellung von Trioxan entsteht. Dieser besteht in der Regel im wesentlichen aus 35 bis 45 Gew. -% Trioxan, 35 bis 45 Gew.-% Wasser und 15 bis 30 Gew.-% Formaldehyd. Strom 1 wird in eine 1. Rektifika- tionskolonne Kl geleitet, in welcher eine Auftrennung in 2 Fraktionen erfolgt, wobei Strom 2 ein Gemisch aus Wasser und Formaldehyd und Strom 3 das azeotrope Gemisch enthält.Stream 1 represents the reactor discharge which is produced in the production of trioxane. As a rule, this consists essentially of 35 to 45% by weight of trioxane, 35 to 45% by weight of water and 15 to 30% by weight of formaldehyde. Stream 1 is passed into a 1st rectification column K1, in which there is a separation into 2 fractions, stream 2 containing a mixture of water and formaldehyde and stream 3 containing the azeotropic mixture.
Bevorzugt erfolgt die Destillation in einer Rektifikationsko- lonne Kl, welche bis zu 60 Böden aufweisen kann. In der Regel erfolgt die Destillation unter Normaldruck.The distillation is preferably carried out in a rectification column K1, which can have up to 60 trays. As a rule, the distillation is carried out under normal pressure.
Der Strom 2 wird anschließend in die Formaldehydaufkonzentrierung zurückgeführt. Das azeotrope Gemisch (Strom 3) wird in eine Per- vaporationseinheit (PV) überführt, die geeignete Membranen zur organophilen Pervaporation enthält. Bei den verwendeten Membranen handelt es sich üblicherweise um porenfreie Polymermembranen, in denen sich die permeierende Komponente löst und durch die Membran hindurch diffundiert.Stream 2 is then returned to the formaldehyde concentration. The azeotropic mixture (stream 3) is transferred to a vaporization unit (PV) which contains suitable membranes for organophilic pervaporation. The membranes used are usually pore-free polymer membranes, in which the permeating component dissolves and diffuses through the membrane.
Als geeignete Membranen seien beispielsweise solche aus Polydi- methylsiloxan und Polyetheramidblockcopolymeren genannt. Die Po- lydimethylsiloxanmembran enthält vorzugsweise einen hydrophoben Zeolithen. Die Dicke der Membran beträgt vorzugsweise von 5 bis 200 μm, bevorzugt von 50 bis 150 μm. Derartige Membranen sind unter dem Handelsnamen Pervap® 1070 der Firma Sulzer Chemtech GmbH-Membrantechnik und PEBA 40 der Firma GSE (Gesellschaft für Spezialfolienentwicklung) im Handel erhältlich.Suitable membranes are, for example, those made from polydimethylsiloxane and polyether amide block copolymers. The polydimethylsiloxane membrane preferably contains a hydrophobic zeolite. The thickness of the membrane is preferably from 5 to 200 μm, preferably from 50 to 150 μm. Such membranes are commercially available under the trade names Pervap® 1070 from Sulzer Chemtech GmbH-Membrantechnik and PEBA 40 from GSE (Gesellschaft für Spezialfolienentwicklung).
Vorzugsweise erfolgt die Pervaporation bei Temperaturen von 70 bis 120°C, vorzugsweise von 80 bis 90°C und einem Druck von 1 bis 3, vorzugsweise von 1 bis 1,5 bar auf der Retentatseite und 10 bis 150 mbar, vorzugsweise von 10 bis 20 mbar auf der Permeat - seite.The pervaporation is preferably carried out at temperatures from 70 to 120 ° C., preferably from 80 to 90 ° C. and a pressure of 1 to 3, preferably 1 to 1.5 bar on the retentate side and 10 to 150 mbar, preferably 10 to 20 mbar on the permeate side.
Der an Trioxan verarmte Strom 5 (Retentat) wird in die erste De- stillationskolonne Kl zurückgeführt, während der mit Trioxan angereicherte Strom 6 (Permeat) in eine zweite Destillationskolonne K2 geführt wird, in welcher anschließend eine Rektifikation erfolgt. Hierbei erhält man eine Trioxanfraktion (Strom 7) und ein azeotropes Gemisch aus den vorstehend genannten Bestandteilen (Strom 8) . Dieses Gemisch wird wiederum vor die Pervaporations- einheit zurückgeführt (Strom 4). Die Trioxanfraktion ist das Produkt und (Strom 7) wird in einen Reaktor geleitet, in welchem aus Trioxan Polyoxymethylene hergestellt werden.The stream 5 depleted in trioxane (retentate) is returned to the first distillation column K 1, while the stream 6 enriched with trioxane (permeate) is fed into a second distillation column K 2, in which rectification then takes place. This gives a trioxane fraction (stream 7) and an azeotropic mixture of the above components (stream 8). This mixture is in turn returned to the pervaporation unit (stream 4). The trioxane fraction is the product and (stream 7) is fed into a reactor in which polyoxymethylenes are produced from trioxane.
Bei dem erfindungsgemäßen Verfahren sind keine zusätzlichen Komponenten erforderlich. Der Austrag aus dem Reaktor wird weitest - gehend quantitativ zur (Rück) gewinnung der Einsatzstoffe Formaldehyd und Trioxan aufgearbeitet.No additional components are required in the method according to the invention. The discharge from the reactor is largely processed quantitatively for the (recovery) of the starting materials formaldehyde and trioxane.
Beispielexample
Ein wäßriges Gemisch (Strom 1) bestehend aus 40 Gew.-% Trioxan, 40 Gew. -% Wasser und 20 Gew. -% Formaldehyd wurde in einer ersten Destillationskolonne (Kl, 25 Stufen) unter Normaldruck in ein Wasser/Formaldehyd Strom (Strom 2) und in ein azeotropes Gemisch (Strom 3) getrennt.An aqueous mixture (stream 1) consisting of 40% by weight of trioxane, 40% by weight of water and 20% by weight of formaldehyde was in a first distillation column (Kl, 25 stages) under normal pressure in a water / formaldehyde stream (stream 2) and separated into an azeotropic mixture (stream 3).
Strom 3 wurde in die Pervaporationseinheit geleitet, welche eine Membran aus Polydimethylsiloxan mit einem hydrophoben Zeolithen enthielt. Die Gesamtdicke betrug 200 μm, die Stützschicht bestand aus Polyacrylnitril . Die Dicke der Trennschicht betrug 15-20 μm. (Membran Pervap® 1070 der Firma Sulzer Chemtech GmbH-Membran- technik) . Die Trennung erfolgte bei 80°C. Der Druck auf der Reten- tatseite (5) betrug 1 bar, auf der Permeatseite (6) 10 mbar. Das mit Trioxan angereicherte Gemisch (Strom 6) trennte man in einer zweiten Destillationskolonne (K2 40 Stufen) unter Normaldruck in Trioxan (Strom 7) und wiederum in ein azeotropes Gemisch aus Trioxan, Wasser und Formaldehyd (Strom 8) auf. Dieses Gemisch wurde vor die Pervaporation (PV) zurückgeführt (Strom 4) .Stream 3 was passed into the pervaporation unit, which contained a membrane of polydimethylsiloxane with a hydrophobic zeolite. The total thickness was 200 μm, the support layer consisted of polyacrylonitrile. The thickness of the separating layer was 15-20 μm. (Membrane Pervap® 1070 from Sulzer Chemtech GmbH-membrane technology). The separation took place at 80 ° C. The pressure on the retentate side (5) was 1 bar and on the permeate side (6) 10 mbar. The mixture enriched with trioxane (stream 6) was separated in a second distillation column (K2 40 stages) under normal pressure into trioxane (stream 7) and again into an azeotropic mixture of trioxane, water and formaldehyde (stream 8). This mixture was recycled prior to pervaporation (PV) (stream 4).
Der an Trioxan verarmte Strom (Strom 5) wurde der ersten De- stillationskolonne (Kl) zugeführt. Der Sumpfström aus dieser Destillationskolonne wurde in die Formaldehyd-Aufkonzentrierung weitergeleitet .The stream depleted in trioxane (stream 5) was fed to the first distillation column (K1). The bottom stream from this distillation column was passed on to the formaldehyde concentration.
Die Mengen und Konzentrationen der verschiedenen Ströme sind in der folgenden Tabelle zusammengestellt.The amounts and concentrations of the different streams are summarized in the following table.
Insgesamt konntenOverall, could
98,4 Gew. -% Trioxan, bezogen auf 3200 kg eingesetztem Trioxan —100 Gew. -% Formaldehyd, bezogen auf 1600 kg eingesetztem Formaldehyd98.4% by weight of trioxane, based on 3200 kg of trioxane used - 100% by weight of formaldehyde, based on 1600 kg of formaldehyde used
zurückgewonnen werden. be recovered.

Claims

Patentansprüche claims
1. Verfahren zur Abtrennung von Trioxan aus einem wäßrigen Gemisch, das im wesentlichen aus Trioxan, Wasser und Formaldehyd besteht, dadurch gekennzeichnet, daß man dem Gemisch Trioxan durch Pervaporation entzieht und das an Trioxan angereicherte Gemisch (Permeat) durch Rektifikation in Trioxan und ein azeotropes Gemisch aus Trioxan, Wasser und Form- aldehyd trennt.1. A process for the separation of trioxane from an aqueous mixture consisting essentially of trioxane, water and formaldehyde, characterized in that trioxane is removed from the mixture by pervaporation and the trioxane-enriched mixture (permeate) by rectification in trioxane and an azeotrope Mixture of trioxane, water and formaldehyde separates.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man die Pervaporation bei einer Temperatur von 70 bis 120°C durchführt .2. The method according to claim 1, characterized in that one carries out the pervaporation at a temperature of 70 to 120 ° C.
3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man die Pervaporation bei einem Druck von 1 bis 3 bar auf der Retentatseite und 10 bis 150 mbar auf der Permeatseite durchführt.3. The method according to claim 1, characterized in that one carries out the pervaporation at a pressure of 1 to 3 bar on the retentate side and 10 to 150 mbar on the permeate side.
4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man die Pervaporation mit einer Membran aus Polydimethylsiloxan oder aus einem Polyetheramidblockcopolymer durchführt.4. The method according to claim 1, characterized in that one carries out the pervaporation with a membrane made of polydimethylsiloxane or a polyether amide block copolymer.
5. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man das Gemisch aus Trioxan, Wasser und Formaldehyd nach der Rektifikation in die Pervaporation zurückführt.5. The method according to claim 1, characterized in that the mixture of trioxane, water and formaldehyde is returned to the pervaporation after the rectification.
Zeichn. Sign.
EP98939607A 1997-07-26 1998-07-02 Method for trioxan isolation Withdrawn EP1001954A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19732291A DE19732291A1 (en) 1997-07-26 1997-07-26 Process for the separation of trioxane
DE19732291 1997-07-26
PCT/EP1998/004094 WO1999005137A1 (en) 1997-07-26 1998-07-02 Method for trioxan isolation

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US (1) US6200429B1 (en)
EP (1) EP1001954A1 (en)
JP (1) JP2001510839A (en)
KR (1) KR20010022244A (en)
CN (1) CN1264374A (en)
DE (1) DE19732291A1 (en)
PL (1) PL338381A1 (en)
WO (1) WO1999005137A1 (en)

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KR20010022244A (en) 2001-03-15
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