Method for the production of aldehydes

A process for preparing aldehydes or aldehydes and alcohols by hydroformylation of olefins in the presence of a catalyst complex which is homogeneously dissolved in the reaction mixture and comprises a metal of group VIIIa of the Periodic Table of the Elements and as ligand a phosphorus-free, polydentate nitrogen compound capable of complex formation, at from 50 to 200° C. and pressures of from 20 to 1000 bar, and recycling of the catalyst complex to the hydroformylation reaction, wherein

• a) the ligands used are modified polyamines which are essentially insoluble in water, are capable of complex formation, have a mean molecular weight of greater than 1000 dalton and contain at least 10 nitrogen atoms,
• b) after the hydroformylation reaction is complete and the aldehydes and alcohols have been separated or partially separated from the reaction mixture by distillation, the catalyst complex and excess ligand remaining in the distillation bottoms are completely or partially recycled to the hydroformylation and
• c) at least part of the high boilers are bled off, continuously or at least batchwise, from the bottoms from the distillation of the reaction mixture,
• where
• the catalyst and excess ligand are precipitated by means of a solvent in which the catalyst and the excess ligand are insoluble or virtually insoluble and only the precipitation product is recycled to the hydroformylation, and/or
• the catalyst and excess ligand are recovered by ultrafiltration of the bottoms from the distillation and the retentate stream which is depleted in high boilers and enriched in catalyst and ligand is recycled to the hydroformylation, and/or
• the high boilers present in the bottoms from the distillation are separated from the catalyst and excess ligand by means of steam distillation and only the distillation bottoms comprising catalyst and excess ligand from the steam distillation are recycled to the hydroformylation reaction.