| abstract |
The invention relates to a process for preparing aldehydes by hydroformylation of olefinically unsaturated compounds with hydrogen and carbon monoxide in homogeneous phase in the presence of a catalyst system comprising organometallic complex compounds and ligands of these complex compounds in molar excess, and separating off the catalyst system from the hydroformylation reaction mixture by pressure filtration on a semipermeable membrane of an aromatic polyamide. In this process, the molar mass ratio of the ligands present in excess to the aldehydes prepared is 9-30, preferably 10-25, in particular 10-15, with the ligands present in excess not being alkylammonium or arylammonium salts of sulfonated, carboxylated or phosphonated aromatic diphosphines. By maintaining the molar mass ratio, not only are high activation and selectivity values obtained in the hydroformylation itself, but also excellent retention values for the catalyst system are obtained in the membrane filtration step. |