Preparation of fatty acid esters

A process for preparing fatty acid esters by reacting olefins, aklanols and carbon monoxide in the presence of a compound of cobalt and a promoter consisting of pyridine, non-orthosubstituted alkylpyridines or mixtures thereof. The reaction output is at first treated with a gas containing oxygen in a non-damaging manner and then reprocessed in two distillation stages. The first distillation stage is operated at a higher pressure than the second. In the first distillation stage there is produced a distillate free of cobalt and a sump product containing all of the cobalt used as catalyst. In the second distillation stage the sump product of the first distillation stage is again distilled to produce another distillate free of cobalt and a cobalt concentrate as sump product. This cobalt concentrate is incorporated into pyridine, a non-orthosubstituted alkylpyridine or a mixture thereof to form a suspension. The suspension is then treated by a mixture of carbon monoxide and hydrogen at a temperature of 100 DEG to 250 DEG C. and a pressure at least 50 bars, and this treatment product is fed back into the fatty acid ester synthesis.