Process for the preparation of anhydrous and from impurities depleted formaldehyde

摘要

Process for the preparation of formaldehyde from aqueous formaldehyde solution, which formaldehyde is largely anhydrous and freed from impurities, characterised in that the aqueous formaldehyde solution is extracted with an alcohol, the resulting alcoholic semiacetal solution is freed from water, and the semiacetal is subsequently subjected to thermal cleavage in a subsequent solvent exchange-column in the presence of a solvent having a lower boiling point than the alcohol used in the extraction, and a mixture of formaldehyde and the solvent is stripped off as top product.