Method for reducing heavy end formation and catalyst loss in a hydroformylation process

A method for reducing heavy end formation and catalyst loss in a continuous hydroformylation process, where an olefin or olefin mixture is reacted with carbon monoxide and hydrogen in a reactor assembly (1) in the presence of a rhodium complex catalyst comprising at least one organobisphosphite ligand, in order to produce an aldehyde, the method comprising:

• a) adding 0.01-1.5 wt % of an epoxide to a reaction mixture,
• b) separating an obtained aldehyde from a mixture of aldehyde, catalyst, ligand, and early heavy ends in a distillation unit (2),
• c) separating early heavy ends by feeding a part of a catalyst and ligand return flow, comprising a mixture of catalyst, ligand, early heavy ends and residual aldehyde from a lower outlet (23) of a final stage (2b) of the distillation unit (2), into a short residence time evaporator unit (3) having at least a first residual aldehyde stripper stage (3a) and at least one last early heavy ends stripper stage (3b), the evaporator unit (3) being of a falling film and/or wiped film type, the rest of the catalyst and ligand return flow being fed back to the reactor assembly (1),
• d) entering the catalyst and ligand mixture from a lower end (3b1) of the at least one last early heavy ends stripping stage (3b) into a cooling unit (4) immediately after stripping of early heavy ends.