| abstract |
The present invention relates to a process for the preparation of aldehydes by hydroformylation of olefinically unsaturated compounds with hydrogen and carbon monoxide, in homogeneous phase, in the presence of a catalyst system containing complex compounds of rhodium as well as aromatic phosphines, in excess cool; and separating the catalyst system from the hydroformylation reaction mixture by means of pressure filtration on a semipermeable membrane of an aromatic polyamide. The process is characterized in that hydroformylation is carried out at a pH value of 2.5 to 4.3, with the use of a molar ratio of phosphine: rhodium of at least 60 and at a rhodium concentration of at least 10 ppm by weight, with with respect to the olefinically unsaturated compound used; and it is used as aromatic phosphines especially alkyl and / or arylammonium salts of sulfonated or carboxylated triarylphosphines; the process according to the invention results in outstanding activity and selectivity values in the hydroformylation stage itself, as well as high retention values in the membrane filtration stage. |