Cobalt SiO2 core-shell catalysts for chemoselective hydrogenation of cinnamaldehyde

Abstract

The effect of the reduction temperature (300 °C, 400 °C, 500 °C and 600 °C) in cobalt SiO2 core-shell catalysts for chemoselective hydrogenation of cinnamaldehyde is reported. The Co-CoO@SiO2 catalysts structures were synthesized starting from a calcined Co3O4@SiO2 nanostructure obtained using a solvothermal method for the core (Co3O4) and a modified Stöber method for the porous shell (SiO2) submitted to different reduction temperatures. The initial Co3O4@SiO2 structure and the derived Co-CoO@SiO2 catalysts were characterized by AAS, TG/DTG, TPR, TEM, XRD, XPS and SBET. The increase in the metallic Co content along with the reduction temperature increased the total conversion of cinnamaldehyde in the liquid-phase hydrogenation reaction. The highest selectivity towards the unsaturated alcohol over Co-CoO@SiO2-500 °C catalyst was attributed to an optimum Co/CoO surface ratio. A large chemical and mechanical stability of the Co-CoO@SiO2 structure was evidenced after five consecutive reaction cycles, revealing the beneficial effect of the core-shell architecture towards cobalt leaching in liquid-phase reactions.