Abstract: Essentially monounsaturated polyalkylenes having from 30 to 700 carbon atoms are continuously hydroformylated by a process in which i) a hydroformylation-active cobalt carbonyl catalyst is prepared from a catalyst precursor dissolved in an aqueous phase in the absence of the polyalkylenes, ii) the polyalkylenes are hydroformylated by means of synthesis gas in the presence of the cobalt carbonyl catalyst in a reaction zone, iii) the cobalt carbonyl catalyst is separated from the output from the reaction zone with at least partial reformation of the catalyst precursor and the catalyst precursor is recirculated to step i).

Abstract: In a process for preparing aldehydes and/or alcohols having from 6 to 30 carbon atoms by hydroformylation of olefins by means of synthesis gas in the presence of a catalyst at from 120° C. to 210° C. and pressures of from 100 to 400 bar, a reaction mixture comprising olefins, synthesis gas and catalyst or catalyst precursor is, according to the present invention, introduced at high velocity into a high-pressure reactor (10) via a nozzle (16) having an adjustable flow cross section.