Patent ID: 8163963

Claim:
A process for continuously hydrogenating unsaturated compounds, in which a) particles of a first hydrogenation catalyst are suspended in a liquid phase in which an unsaturated compound is dissolved, b) the liquid phase, in the presence of a hydrogenous gas at a first partial hydrogen pressure and at a first temperature, is conducted through a packed bubble column reactor in cocurrent counter to the direction of gravity, c) the effluent from the bubble column reactor is sent to a gas-liquid separation, d) the liquid phase from step c) is sent to a crossfiltration to obtain a retentate and a filtrate, e) the retentate is recycled into step b), f) the filtrate, in the presence of a hydrogenous gas at a second partial hydrogen pressure and at a second temperature, is passed over a bed of a second hydrogenation catalyst. wherein the unsaturated compound is selected from the group consisting of cinnamaldehyde derivatives of the following formula (II) in which R 1 , R 2 , R 3 , R 4 , and R 5 are each independently hydrogen, C 1-9 -alkyl or C 1-9 -alkoxy, and R 6 is hydrogen or methyl.