Abstract:
A method for the production of highly concentrated formaldehyde solutions containing ≥ 50 wt. % CH2O from an aqueous formaldehyde solution having a lower CH2O content by evaporating part of said solution (partial evaporation), wherein the aqueous formaldehyde solution is heated to an evaporation temperature T wherein water becomes enriched in a gaseous phase in relation to the liquid phase and the formed gas phase is continuously or discontinuously removed. For the evaporation temperature T: T [ °C]
Abstract:
The invention relates to an integrated process for preparing trioxane from formaldehyde in which, in a first step, a stream A 1 comprising water and formaldehyde and a recycle stream B 2 consisting substantially of water and formaldehyde are fed to a trioxane synthesis reactor in which the formaldehyde is converted to trioxane to obtain a product stream A 2 comprising trioxane, water and formaldehyde. Stream A 2 and a recycle stream D 1 comprising trioxane, water and formaldehyde are fed to a first distillation column and distilled at a pressure in the range from 0.1 to 2.5 bar to obtain a stream B 1 enriched in trioxane, and the stream B 2 consisting substantially of water and formaldehyde. Stream B 1 is fed to a second distillation column and distilled at a pressure in the range from 0.2 to 17.5 bar to obtain a product stream C 2 consisting substantially of trioxane, and a stream C 1 comprising trioxane, water and formaldehyde. Stream C 1 is fed to a third distillation column and distilled at a pressure in the range from 1 to 10 bar to obtain the recycle stream D 1 comprising trioxane, water and formaldehyde, and a stream D 2 consisting substantially of water.
Abstract:
METHOD OF STABILIZING HIGH-CONCENTRATIONN FORMALDEHYDE SOLUTIONS HAVING A CH₂O CONTENT OF > 70% BY WEIGHT AGAINTS PRECIPITATION OF SOLIDS, WHICH COMPRISES HEATING THE HIGH-CONCENTRATION FORMALDEHYDE SOLUTION AT A HEATING RATE OF AT LEAST 5°C/MIN TO A TEMPERATURE OF FROM 80°C TO 200°C IMMEDIATELY AFTER IT HAS BEEN PREPARED AND STORING IT AT A TEMPERATURE IN THIS RANGE.
Abstract:
The invention relates to an integrated process for preparing trioxane from formaldehyde in which, in a first step, a stream A 1 comprising water and formaldehyde and a recycle stream B 2 consisting substantially of water and formaldehyde are fed to a trioxane synthesis reactor in which the formaldehyde is converted to trioxane to obtain a product stream A 2 comprising trioxane, water and formaldehyde. Stream A 2 and a recycle stream D 1 comprising trioxane, water and formaldehyde are fed to a first distillation column and distilled at a pressure in the range from 0.1 to 2.5 bar to obtain a stream B 1 enriched in trioxane, and the stream B 2 consisting substantially of water and formaldehyde. Stream B 1 is fed to a second distillation column and distilled at a pressure in the range from 0.2 to 17.5 bar to obtain a product stream C 2 consisting substantially of trioxane, and a stream C 1 comprising trioxane, water and formaldehyde. Stream C 1 is fed to a third distillation column and distilled at a pressure in the range from 1 to 10 bar to obtain the recycle stream D 1 comprising trioxane, water and formaldehyde, and a stream D 2 consisting substantially of water.
Abstract:
Method of stabilizing high-concentration formaldehyde solutions having a CH 2 O content of >70% by weight against precipitation of solids, which comprises heating the high-concentration formaldehyde solution at a heating rate of at least 5° C./min to a temperature of from 80° C. to 200° C. immediately after it has been prepared and storing it at a temperature in this range.
Abstract:
PROCESS FOR PREPARING HIGH-CONCENTRATION GASEOUS FORMALDEHYDE HAVING A MOLAR CH2O:H2O RATIO OF >= O.6 FROM AN AQUEOUS FORMALDEHYDE SOLUTION BY EVAPORATION OF AT LEAST PART OF THE SOLUTION, IN WHICH THE AQUEOUS FORMALDEHYDE SOLUTION IS HEATED TO A VAPORIZATION TEMPERATURE T AND THE GAS PHASE FORMED IS TAKEN OFF, WHEREIN THE EVAPORATION TEMPERATURE T OBEYS THE RELATIONSHIP:
Abstract:
The invention relates to an integrated process for preparing trioxane from formaldehyde, comprising the steps of: a) a stream A 1 comprising water and formaldehyde and a recycle stream B 2 consisting substantially of water and formaldehyde are fed to a trioxane synthesis reactor and allowed to react to obtain a product stream A 2 comprising trioxane, water and formaldehyde; b) stream A 2 is fed to a first low-pressure distillation column and distilled at a pressure of from 0.1 to 2.5 bar to obtain a stream B 1 enriched in trioxane and additionally comprising water and formaldehyde, and the recycle stream B 2 consisting substantially of formaldehyde and water; c) stream B 1 and a recycle stream D 1 comprising trioxane, water and formaldehyde are fed to a second low-pressure distillation column and distilled at a pressure of from 0.1 to 2.5 bar to obtain a stream C 1 comprising predominantly trioxane and additionally formaldehyde and water, and a stream C 2 consisting substantially of formaldehyde and water; d) stream C 1 is fed to a high-pressure distillation column and distilled at a pressure of from 0.2 to 17.5 bar to obtain the recycle stream D 1 and a product stream D 2 consisting substantially of trioxane, in which a removal of the low boilers present in streams B 1 or C 1 may be undertaken between steps b) and c) or c) and d).
Abstract:
A process for removing trioxane from a mixture I of formaldehyde, trioxane and water, by a) distilling the mixture I in a first distillation stage at a pressure of from 0.1 to 2 bar to obtain a stream II which comprises formaldehyde and a stream III which comprises predominantly trioxane and additionally water and formaldehyde, b) mixing the stream III with a recycle stream VII which comprises predominantly trioxane and additionally water and formaldehyde to obtain a stream IIIa which comprises predominantly trioxane and additionally water and formaldehyde, c) distilling the stream IIIa, if appropriate after removing low boilers from the stream III or IIIa in a further distillation stage, in a second distillation stage at a pressure of from 0.2 to 10 bar, the pressure in the second distillation stage being at least 0.1 bar higher than the pressure in the first distillation stage, to obtain a stream IV of trioxane and a stream V which comprises predominantly trioxane and additionally water and formaldehyde, d) distilling the stream V in a third distillation stage at a pressure of from 0.1 to 4 bar to obtain a stream VI which comprises predominantly water and additionally formaldehyde, and the recycle stream VII which comprises predominantly trioxane and additionally water and formaldehyde, e) if appropriate, distilling the stream VI in a fourth distillation stage to obtain a stream VIII which comprises predominantly water, and a stream IX which comprises predominantly formaldehyde.
Abstract:
The invention relates to a method for separating trioxane from a mixture containing formaldehyde, trioxane and water. According to said method: the mixture (1) is distilled in a first distillation stage (7) at a pressure of between 0.1 and 2 bar to obtain a stream (8) containing formaldehyde and a stream (9) containing predominantly trioxane, in addition to water and formaldehyde; the stream (9) is mixed with a recycling stream (19) containin g predominantly trioxane, in addition to water and formaldehyde to form a stre am (10) containing predominantly trioxane, in addition to water and formaldehyd e; the stream (10) is then distilled in a second distillation stage (14) at a pressure of between 0.2 and 10 bar, optionally after the separation of low- boilers from the stream (9) or (10) in an additional distillation stage (11) . The pressure in the second distillation stage (14) is at least 0.1 bar highe r than the pressure in the first distillation stage (7). Said distillation produces a stream (15) consisting of trioxane and a stream (16) containing predominantly trioxane, in addition to water and formaldehyde. The stream (1 6) is then distilled in a third distillation stage (17) at a pressure of betwee n 0.1 and 4 bar, to obtain a stream (18) containing predominantly water, in addition to formaldehyde and the recycling stream (19) containing predominantly trioxane, in addition to water and formaldehyde. The resultant stream (18) is optionally distilled in a fourth distillation stage (20), to obtain a stream (21) containing predominantly water and a stream (22) containing predominantly formaldehyde.