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/cm 2 hydrogen pressure. Co/TiO 2 exhibited a greater conversion (47.4%) and selectivity to cinnamyl alcohol (58%) than Co/Al 2O 3 and Co/SiO 2, which may be attributed to the presence of TiO x (x < 2) species on the catalyst surface and to the preferential adsorption of C=O on the catalyst surface. The stability of Co/TiO 2 was found to be better than Co/Al 2O 3 and Co/SiO 2. Between the various phases of titania (high surface area, anatase and rutile), the crystalline phases exhibited a better conversion and selectivity to cinnamyl alcohol, while the stability was found to be better for high surface area titania. © 2011 Springer Science+Business Media, LLC.