Abstract: The invention relates to a continuous process to make and isolate methylal by reacting formaldehyde and methanol with an acid catalyst under at least partial formation of methylal and water, to form a mixture M2 comprising formaldehyde, methanol, methylal, and water, separating the said mixture M2 in a distillation column B into three distinct product streams, one being a distillate taken from the column head BH which is rich in methylal, one taken from the column bottom stream BB being almost pure water, and one taken from the side of the column B below the reaction zone which stream is rich in methanol, characterised in that the ratio of the amount of substance of methanol to the amount of substance of formaldehyde in the mixture M1 is at least 3 mol/mol, and to an apparatus to be used with this process.

Abstract: The invention relates to a continuous process to make and isolate methylal by reacting formaldehyde and methanol with an acid catalyst under at least partial formation of methylal and water, to form a mixture M2 comprising formaldehyde, methanol, methylal, and water, separating the said mixture M2 in a distillation column B into three distinct product streams, one being a distillate taken from the column head BH which is rich in methylal, one taken from the column bottom stream BB being almost pure water, and one taken from the side of the column B below the reaction zone which stream is rich in methanol, characterised in that the ratio of the amount of substance of methanol to the amount of substance of formaldehyde in the mixture M1 is at least 3 mol/mol, and to an apparatus to be used with this process.

Abstract: A process for preparing polyoxymethylene dialkyl ethers of the formula H2m+1CmO(CH2O)nCmH2m+1 where n=2-10, m, identically or differently,=1 or 2, in which a dialkyl ether selected from dimethyl ether, methyl ethyl ether and diethyl ether, and trioxane are fed into a reactor and reacted in the presence of an acidic catalyst, the amount of water introduced into the reaction mixture by the dialkyl ether, trioxane and/or the catalyst being <1% by weight based on the reaction mixture.

Abstract: 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.

Abstract: A process for preparing tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4) by reacting formaldehyde with methanol and subsequently working up the reaction mixture by distillation, consisting of: a) feeding aqueous formaldehyde solution and methanol into a reactor and reacting to give a mixture including formaldehyde, water, methylene glycol (MG), polyoxymethylene glycols (MGn>1), methanol, hemiformals (HF), methylal (POMDMEn=1) and polyoxymethylene glycol dimethyl ethers (POMDMEn>1); b) feeding the reaction mixture a into a first distillation column and separating into a low boiler fraction b1 and a high boiler fraction b2 including formaldehyde, water, methanol, MGn>1, HF and POMDMEn>1; c) feeding the high boiler fraction b2 into a second distillation column and separating into a low boiler fraction c1 including formaldehyde, water, MG, MGn>1, methanol, HF, di-, tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=2,3,4), and a high boiler fraction c2; d) feeding the low boile

Abstract: Processes for preparing tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4) include feeding a reaction mixture of an aqueous formaldehyde solution and methanol into a reactive evaporator and separating into a first low boiler fraction and a first high boiler fraction, recycling the first high boiler fraction into the reactor, feeding the first low boiler fraction into a first distillation column and separating into a second low boiler fraction and a second high boiler fraction, recycling the second high boiler fraction into the reactive evaporator, feeding the second low boiler fraction into a second distillation column and separating into a third low boiler fraction and a third high boiler fraction, feeding the third high boiler fraction into a phase separation apparatus and separating into an aqueous phase and an organic phase, and feeding the organic phase into a third distillation column and separating into a low and high boiler fractions.

Abstract: 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.

Abstract: A process for preparing tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4) by reacting formaldehyde with methanol and subsequently working up the reaction mixture by distillation, comprising the steps of.

Abstract: A process for preparing polyoxymethylene dialkyl ethers of the formula H2m+1CmO(CH2O)nCmH2m+1 where n=2-10, m, identically or differently,=1 or 2, in which a dialkyl ether selected from dimethyl ether, methyl ethyl ether and diethyl ether, and trioxane are fed into a reactor and reacted in the presence of an acidic catalyst, the amount of water introduced into the reaction mixture by the dialkyl ether, trioxane and/or the catalyst being <1% by weight based on the reaction mixture.

Abstract: A process for preparing tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4) by reacting formaldehyde with methanol and subsequently working up the reaction mixture by distillation, comprising the steps of: a) feeding aqueous formaldehyde solution and methanol into a reactor and reacting; b) feeding the reaction mixture a into a reactive evaporator and separating into a low boiler fraction b1 comprising formaldehyde, water, methanol, methylene glycol, polyoxymethylene glycols, hemiformals, methylal and polyoxymethylene glycol dimethyl ethers (POMDMEn>1), and a high boiler fraction b2, and recycling the high boiler fraction b2 into the reactor (step a)); c) feeding the low boiler fraction b1 into a first distillation column and separating into a low boiler fraction c1 comprising formaldehyde, water, methylene glycol, methanol, hemiformals, methylal, di-, tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=2,3,4), and a high boiler fraction c2, and recycling the high boiler fraction c2 into

Abstract: 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.

Abstract: A process for preparing polyoxymethylene dimethyl ether of the formula H3CO(CH2O)nCH3 where n=2-10, in which methylal and trioxane are fed into a reactor and reacted in the presence of an acidic catalyst, wherein the amount of water introduced into the reaction mixture by methylal, trioxane and/or the catalyst is <1% by weight based on the reaction mixture. Preferably, a fraction comprising polyoxymethylene dimethyl ether where n=3 and 4 is obtained by distillation from the reaction mixture, and methylal, trioxane and polyoxymethylene dimethyl ether where n<3 and optionally n>4 are recycled into the reaction.

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.