摘要:
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.
摘要:
The invention relates to an integrated process for preparing trioxane from formaldehyde, comprising the steps of: a) a stream A1 comprising water and formaldehyde and a recycle stream B2 consisting substantially of water and formaldehyde are fed to a trioxane synthesis reactor and allowed to react to obtain a product stream A2 comprising trioxane, water and formaldehyde; b) stream A2 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 B1 enriched in trioxane and additionally comprising water and formaldehyde, and the recycle stream B2 consisting substantially of formaldehyde and water; c) stream B1 and a recycle stream D1 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 C1 comprising predominantly trioxane and additionally formaldehyde and water, and a stream C2 consisting substantially of formaldehyde and water; d) stream C1 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 D1 and a product stream D2 consisting substantially of trioxane, in which a removal of the low boilers present in streams B1 or C1 may be undertaken between steps b) and c) or c) and d).
摘要:
The invention relates to an integrated process for preparing trioxane from formaldehyde in which, in a first step, a stream A1 comprising water and formaldehyde and a recycle stream B2 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 A2 comprising trioxane, water and formaldehyde. Stream A2 and a recycle stream D1 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 B1 enriched in trioxane, and the stream B2 consisting substantially of water and formaldehyde. Stream B1 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 C2 consisting substantially of trioxane, and a stream C1 comprising trioxane, water and formaldehyde. Stream C1 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 D1 comprising trioxane, water and formaldehyde, and a stream D2 consisting substantially of water.
摘要:
The invention relates to an integrated process for preparing trioxane from formaldehyde in which a stream A1 comprising water and formaldehyde and a recycle stream B2 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 A2 comprising trioxane, water and formaldehyde; stream A2 is 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 B1 enriched in trioxane, and the stream B2 consisting substantially of water and formaldehyde; stream B1 and a recycle stream D1 comprising trioxane, water and formaldehyde are 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 C2 consisting substantially of trioxane, and a stream C1 comprising trioxane, water and formaldehyde; stream C1 is fed to a third distillation column and distilled at a pressure in the range from 0.1 to 2.5 bar to obtain the recycle stream D1 comprising trioxane, water and formaldehyde, and a stream D2 consisting substantially of water and formaldehyde.
摘要:
A process for removing trioxane from a use stream I of formaldehyde, trioxane and water, by a) providing a use stream I which comprises formaldehyde as the main component and trioxane and water as the secondary components, b) mixing the use stream I with a recycle stream VII which comprises trioxane as the main component and formaldehyde and water as the secondary components to obtain a feed stream Ia which comprises formaldehyde as the main component and trioxane and water as the secondary components, c) distilling the use stream Ia in a first distillation stage at a pressure of from 0.1 to 2.5 bar to obtain a stream II which comprises formaldehyde as the main component and water as the secondary component, and a stream III which comprises trioxane as the main component and water and formaldehyde as the secondary components, d) distilling the stream III, optionally after removing low boilers from the stream III in a low boiler removal stage, in a second distillation stage at a pressure of from 0.2 to 17.5 bar, the pressure in the second distillation stage being from 0.1 to 15 bar higher than the pressure in the first distillation stage, to obtain a stream IV which consists substantially of trioxane and a stream V which comprises trioxane as the main component and water and formaldehyde as the secondary components, e) optionally mixing the stream V with a stream IX which comprises water as the main component to obtain a stream Va having a higher water content than the stream V, the stream Va comprising trioxane as the main component and water and formaldehyde as the secondary components, f) distilling the stream V or Va in a third distillation stage at a pressure of from 1 to 10 bar to obtain a stream VI which consists substantially of water and the recycle stream VII which comprises trioxane as the main component and water and formaldehyde as the secondary components
摘要:
A process for removing trioxane from a use stream I of formaldehyde, trioxane and water, by a) providing a use stream I of formaldehyde as the main component and trioxane and water as the secondary components, b) mixing the use stream I with a recycle stream VII to obtain a feed stream Ia, c) distilling the use stream Ia in a first distillation stage to obtain a stream II of formaldehyde as the main component and water as the secondary component, and a stream III of trioxane as the main component and water and formaldehyde as the secondary components, d) distilling the stream III in a second distillation stage having a pressure higher than in the first distillation stage, to obtain a stream IV of trioxane and a stream V of trioxane as the main component and water and formaldehyde as the secondary components, e) distilling the stream V in a third distillation stage to obtain a stream VI of water and the recycle stream VII of trioxane as the main component and water and formaldehyde as the secondary components.
摘要:
A process for preparing trioxane from trioxymethylene glycol dimethyl ether (POMDMEn=3) by converting trioxymethylene glycol dimethyl ether in the presence of an acidic catalyst and subsequent distillative workup of the reaction mixture, comprising the steps of: a) feeding trioxymethylene glycol dimethyl ether (POMDMEn=3) or a mixture comprising trioxymethylene glycol dimethyl ether into a reactor and converting it in the presence of an acidic catalyst to a mixture a comprising trioxane, formaldehyde, water, methylene glycol (MG), polyoxymethylene glycols (MGn>1), methanol, hemiformals (HF), methylal (POMDMEn=1) and polyoxymethylene glycol dimethyl ethers (POMDMEn>1); b) distillatively separating the reaction mixture a into a low boiler fraction b1 comprising trioxane, formaldehyde, water, methylene glycol, methanol, hemiformal (HFn=1), methylal and dioxymethylene glycol dimethyl ether (POMDMEn=2), and a high boiler fraction b2 comprising polyoxymethylene glycols (MGn>1), hemiformals (HFn>1) and polyoxymethylene glycol dimethyl ethers (POMDMEn>2); c) distillatively separating the low boiler fraction b1 into a low boiler fraction c1 comprising formaldehyde, water, methylene glycol, methanol, hemiformal (HFn=1), methylal and dioxymethylene glycol dimethyl ether (POMDMEn=2), and a high boiler fraction c2 comprising trioxane.
摘要:
A process for preparing trioxane from trioxymethylene glycol dimethyl ether (POMDMEn=3) by converting trioxymethylene glycol dimethyl ether in the presence of an acidic catalyst and subsequent distillative workup of the reaction mixture, comprising the steps of: a) feeding trioxymethylene glycol dimethyl ether (POMDMEn=3) or a mixture comprising trioxymethylene glycol dimethyl ether into a reactor and converting it in the presence of an acidic catalyst to a mixture a comprising trioxane, formaldehyde, water, methylene glycol (MG), polyoxymethylene glycols (MGn>1), methanol, hemiformals (HF), methylal (POMDMEn=1) and polyoxymethylene glycol dimethyl ethers (POMDMEn>1); b) distillatively separating the reaction mixture a into a low boiler fraction b1 comprising formaldehyde, water, methylene glycol, methanol, hemiformal (HFn=1), methylal and dioxymethylene glycol dimethyl ether (POMDMEn=2), and a high boiler fraction b2 comprising trioxane, polyoxymethylene glycols (MGn>1), hemiformals (HFn>1) and polyoxymethylene glycol dimethyl ethers (POMDMEn>2); c) distillatively separating the high boiler fraction b2 into a low boiler fraction c1 comprising trioxane, and a high boiler fraction c2 comprising polyoxymethylene glycols (MGn>1), hemiformals (HFn>1) and polyoxymethylene glycol dimethyl ethers (POMDMEn>2).
摘要:
Process for preparing high-concentration gaseous formaldehyde having a molar CH2O:H2O ratio of ≧0.6 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: T[° C.]≧T′min[° C.] where T′min(c)=A+B×(c/100)+C×(c/100)2+D×(c/100)3 and A=+68.759, B=+124.77, C=−12.851, D=−10.095, where c is the instantaneous CH2O content of the aqueous formaldehyde solution during the evaporation in percent by weight and is from 20 to 99% by weight.
摘要:
Process for preparing high-concentration formaldehyde solutions having a CH2O content of ≧50% by weight from an aqueous formaldehyde solution having a lower CH2O content by evaporation of part of this solution (partial evaporation), in which the aqueous formaldehyde solution is heated to an evaporation temperature T at which the gas phase becomes enriched in water relative to the liquid phase and the gas phase formed is taken off continuously or discontinuously, wherein the evaporation temperature T obeys the relationship: T[° C.]