Selective Hydrogenation of Cinnamaldehyde over Cobalt Supported on Alumina, Silica and Titania

The liquid phase selective hydrogenation of cinnamaldehyde has been investigated on cobalt (15 wt%) impregnated on alumina, silica and various phases of titania supports. The multiple reduction stages observed in the TPR studies suggest the presence of cobalt aluminate/silicate/titanate species, and DRIFT spectra results seem to corroborate this observation. An optimum level of conversion and selectivity to cinnamyl alcohol was observed at 120 °C and 10 kg/cm2 hydrogen pressure. Co/TiO2 exhibited a greater conversion (47.4%) and selectivity to cinnamyl alcohol (58%) than Co/Al2O3 and Co/SiO2, which may be attributed to the presence of TiO x (x   Co/SiO2 > Co/Al2O3. The hydrogenation of CMA is believed to preferentially proceed via adsorption of C=O on the surface of Co/TiO2.