| abstract |
A process for purifying formaldehyde in which the formaldehyde is scrubbed with alcohol in an absorption unit and in the course of this reacted virtually completely to form the hemiformal and is simultaneously separated from gaseous impurities in a first purification step. In a desorption unit, the residual impurities are then converted into a gaseous state and separated off from the liquid hemiformal, whereupon the purified hemiformal is thermally cleaved into alcohol and formaldehyde in a pyrolysis unit. The formaldehyde thus prepared is suitable, for example, for preparing oligomers, polymers, dyestuffs and fertilizers, as well as for the treatment of seeds. |