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WO2006061167A1 - Procede en deux etapes pour produire du trioxane a partir d'une solution de formaldhehyde aqueuse tres concentree, le melange de reaction etant extrait sous forme de gaz du reacteur de synthese et dirige dans une colonne de distillation - Google Patents

Procede en deux etapes pour produire du trioxane a partir d'une solution de formaldhehyde aqueuse tres concentree, le melange de reaction etant extrait sous forme de gaz du reacteur de synthese et dirige dans une colonne de distillation Download PDF

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Publication number
WO2006061167A1
WO2006061167A1 PCT/EP2005/012999 EP2005012999W WO2006061167A1 WO 2006061167 A1 WO2006061167 A1 WO 2006061167A1 EP 2005012999 W EP2005012999 W EP 2005012999W WO 2006061167 A1 WO2006061167 A1 WO 2006061167A1
Authority
WO
WIPO (PCT)
Prior art keywords
trioxane
formaldehyde
synthesis reactor
distillation column
process step
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.)
Ceased
Application number
PCT/EP2005/012999
Other languages
German (de)
English (en)
Inventor
Neven Lang
Achim Stammer
Eckhard Stroefer
Markus Siegert
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 WO2006061167A1 publication Critical patent/WO2006061167A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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

Definitions

  • the invention relates to a process for the preparation of crude trioxane from a highly concentrated aqueous formaldehyde solution.
  • Trioxane can be prepared by reactive distillation of aqueous formaldehyde solution in the presence of acidic catalysts. The trioxane is then extracted from the distillate containing trioxane formaldehyde and water in addition to halogenated hydrocarbons, such as methylene chloride or 1,2-dichloroethane, or other water-immiscible solvents.
  • halogenated hydrocarbons such as methylene chloride or 1,2-dichloroethane, or other water-immiscible solvents.
  • DE-A 1 668 867 describes a process for the separation of trioxane from mixtures containing water, formaldehyde and trioxane by extraction with an organic solvent.
  • an extraction section consisting of two sections is fed at one end with a customary organic water-immiscible trioxane extractant, at the other end with water.
  • the distillate to be separated is fed to the trioxane synthesis.
  • An aqueous formaldehyde solution is then obtained on the side of the solvent feed and a virtually formaldehyde-free solution of trioxane in the solvent is obtained on the side of the water feed.
  • the distillate resulting from the trioxane synthesis from 40% by weight of water, 35% by weight of trioxane and 25% by weight of formaldehyde is metered into the middle part of a pulsation column, at the upper end of the column methylene chloride and at the lower end of the column Supplied with water.
  • about 25% strength by weight solution of trioxane in methylene chloride is obtained at the lower end of the column and about 30% strength by weight aqueous formaldehyde solution is obtained at the upper end of the column.
  • DE-A 197 32 291 describes a process for the separation of trioxane from an aqueous mixture consisting essentially of trioxane, water and formaldehyde, in which trioxane is removed from the mixture by pervaporation and the trioxane is added to the mixture. enriched permeate by rectification in trioxane and an azeotropic mixture of trioxane, water and formaldehyde separates.
  • an aqueous mixture consisting of 40% by weight of trioxane, 40% by weight of water and 20% by weight of formaldehyde in a first distillation column under normal pressure is introduced into a water / formaldehyde mixture and into an azeotropic trioxane / Separated water / formaldehyde mixture.
  • the azeotropic mixture is passed into a pervaporation unit containing a membrane of polydimethylsiloxane with a hydrophobic zeolite.
  • the trioxane-enriched mixture is separated in a second distillation column under normal pressure in trioxane and again in an azeotropic mixture of trioxane, water and formaldehyde. This azeotropic mixture is recycled before the pervaporation step.
  • German patent application DE 103 61 516.4 which is not prepublished, discloses a process for the distillative separation of trioxane from trioxane / formaldehyde / water mixtures, which does not require any extraction or pervaporation steps.
  • the process requires a plant with three distillation columns.
  • Paraformaldehyde (n> 10) The location of the equilibrium is far on the side of the starting material formaldehyde. In addition, a variety of side reactions take place, including the accumulation of para-formaldehyde.
  • aqueous formaldehyde solution to trioxane proceeds under homogeneous or heterogeneous acid catalysis.
  • catalysts are sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid, generally in a concentration of from 1 to 15% by weight, based on the total weight of the aqueous formaldehyde solution, or an equivalent amount of ion exchange resins or zeolites.
  • the acidic catalysts in the required high proportions by weight generally increase the problem of solid state failure by binding water molecules by dissociation. As a result, with the same formaldehyde concentration, the solubility limit is shifted in the direction of higher temperatures.
  • trioxane synthesis reactor acid catalyzed reaction of a highly concentrated aqueous formaldehyde solution in a trioxane synthesis reactor to give a trioxane / formaldehyde / water
  • trioxane / formaldehyde / water mixture is withdrawn from the trioxane synthesis reactor in process stage I in gaseous form.
  • aqueous formaldehyde solution having a formaldehyde content of at least 50% by weight, or at least 60% by weight, or else at least 64% by weight.
  • Sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid, zeolites or ion exchange resins can generally be used as acidic, homogeneous or heterogeneous catalysts, generally in an amount of from 1 to 15% by weight, based on the weight of the highly concentrated aqueous formaldehyde solution
  • a crude trioxane is a stream containing trioxane in a weight fraction of 40 to 80%, and in addition 1 to 30 wt .-% formaldehyde, water and by-products.
  • trioxane is a stream which contains at least 97.5% by weight, preferably at least 99% by weight or 99.9% by weight or else 99.99% by weight of trioxane.
  • the trioxane synthesis reactor can be, for example, a fixed-bed, suspended-bed or continuous-bed reactor, a stirred tank or an evaporator, which is preferably operated at superatmospheric pressure.
  • the trioxane synthesis reactor is preferably operated at a pressure in the range from 1 to 10 bar a, more preferably from 1 to 7 bar a.
  • the trioxane synthesis reactor is preferably operated at residence times of less than 30 minutes, more preferably less than 15 minutes.
  • the highly concentrated aqueous formaldehyde solution is fed to the trioxane synthesis reactor via a mixing device with high mixing energy, of more than 0.3 W / 1, preferably of more than 3 W / 1, particularly preferably of more than 30 W / 1.
  • a gaseous stream containing trioxane, formaldehyde and water is withdrawn from the upper region thereof.
  • the composition of the gaseous stream from the trioxane synthesis reactor generally corresponds to 1 to
  • trioxane 60 to 80% by weight of formaldehyde, the remainder being water and secondary components.
  • the gaseous stream from the trioxane synthesis reactor is, preferably via a control valve, expanded into the distillation column, in which the trioxane / formaldehyde / water mixture is separated into a top stream containing crude trioxane and a bottom stream, preferably in the Trioxane synthesis reactor is recycled.
  • This circulating stream is mixed with the freshly supplied highly concentrated formaldehyde solution either before the circulation pump or in another mixing unit, for example a reaction mixing pump of a mixing nozzle, a static mixer or in a reaction mixer.
  • a reaction mixing pump of a mixing nozzle for example a reaction mixing pump of a mixing nozzle, a static mixer or in a reaction mixer.
  • the top stream containing crude trioxane can be purified in a further distillation column to pure trioxane.
  • the process stage I is preferably carried out in the trioxane synthesis reactor at elevated pressure compared with process stage II in the distillation column
  • the pressure difference between distillation column and trioxane synthesis reactor can be compensated for as an alternative to the control valve by hydrostatic pressure.
  • the trioxane-containing reaction mixture is taken off in gaseous form from the trioxane synthesis reactor, the acids critical for the solid precipitation of para-formaldehyde remain in the trioxane synthesis reactor and are not included in the distillation column. drags.
  • more cost-effective steel grades can be used for the distillation column, which need not be acid-resistant.
  • the steel grades 1.4541, 1.4571 or 1.4539 or similar alloyed steels can be used, alternatively other materials, provided they are not more expensive than the aforementioned.
  • the distillation column for crude trioxane is generally designed without a stripping section.
  • Solubility tests with and without acid have shown that in the presence of strong pillars acids, such as the aforesaid sulfuric acid, methanesulfonic acid or para-toluenesulfonic acid, the temperature to be selected by at least 10 0 C higher compared to an operation without acid must so that no solid precipitates.
  • strong pillars acids such as the aforesaid sulfuric acid, methanesulfonic acid or para-toluenesulfonic acid
  • Figure 1 shows the schematic representation of a system according to a preferred embodiment of the invention
  • a trioxane synthesis reactor R is fed with a highly concentrated aqueous formaldehyde solution via a pump P and an evaporator V. From the gas space of the trioxane synthesis reactor, a trioxane / formaldehyde / water mixture is taken off in vapor form and depressurized via a control valve RV to the pressure in the distillation column K for crude trioxane. From the distillation column K, a top stream 3 containing crude trioxane and a bottom stream 4 is withdrawn, which is recycled via a pump P in the trioxane synthesis reactor.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Heterocyclic Compounds That Contain Two Or More Ring Oxygen Atoms (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Abstract

L'invention concerne un procédé pour produire un trioxane brut comprenant les étapes suivantes : transformation catalytique acide d'une solution de formaldéhydes aqueux à forte concentration, lors de la conservation d'un mélange trioxane/formaldéhydes/eau (étape I), et distillation du mélange trioxane/formaldéhyde/eau de l'étape I, lors de la conservation du trioxane brut (étape II). Le procédé de l'invention est caractérisé en ce que le mélange trioxane/ formaldéhyde/ eau est distillé sous forme gazeuse à partir du réacteur de synthèse du trioxane (R) dans l'étape I.
PCT/EP2005/012999 2004-12-06 2005-12-05 Procede en deux etapes pour produire du trioxane a partir d'une solution de formaldhehyde aqueuse tres concentree, le melange de reaction etant extrait sous forme de gaz du reacteur de synthese et dirige dans une colonne de distillation Ceased WO2006061167A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE200410058707 DE102004058707A1 (de) 2004-12-06 2004-12-06 Verfahren zur Herstellung von Trioxan aus einer hochkonzentrierten wässrigen Formaldehydlösung
DE102004058707.8 2004-12-06

Publications (1)

Publication Number Publication Date
WO2006061167A1 true WO2006061167A1 (fr) 2006-06-15

Family

ID=35744659

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2005/012999 Ceased WO2006061167A1 (fr) 2004-12-06 2005-12-05 Procede en deux etapes pour produire du trioxane a partir d'une solution de formaldhehyde aqueuse tres concentree, le melange de reaction etant extrait sous forme de gaz du reacteur de synthese et dirige dans une colonne de distillation

Country Status (2)

Country Link
DE (1) DE102004058707A1 (fr)
WO (1) WO2006061167A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1012372A (en) * 1963-12-05 1965-12-08 Ici Ltd Improvements in the production of trioxane
DE1543340A1 (de) * 1966-03-30 1969-09-25 Basf Ag Verfahren zur Herstellung von Trioxan
DE1814197A1 (de) * 1966-12-29 1971-06-09 Basf Ag Verfahren zur Herstellung von Trioxan

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1012372A (en) * 1963-12-05 1965-12-08 Ici Ltd Improvements in the production of trioxane
DE1543340A1 (de) * 1966-03-30 1969-09-25 Basf Ag Verfahren zur Herstellung von Trioxan
DE1814197A1 (de) * 1966-12-29 1971-06-09 Basf Ag Verfahren zur Herstellung von Trioxan

Also Published As

Publication number Publication date
DE102004058707A1 (de) 2006-06-08

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