Chemoselective hydrogenation of alfa,beta-unsaturated ketone to alfa,beta-unsaturated alcohol on Au/CeO2 catalysts

In this communication we report the results of a study on the liquid phase hydrogenation of trans,4-phenyl,3-buten,2-one (benzalacetone) on goldsupported on ceria catalysts. The influence of the pretreatment of the catalyst and of the surface area of the support on the catalytic activity and selectivity towards the forrnation of the unsaturated alcohol has been investigated. Tuecatalysts were prepared by deposition/precipitation of gold onto the metal oxide (CeO2). Tue metal loading was 3.7 wt%/%. CeO2 at different surface area (110 m2/g - 20 m2/g) were used as support. The samples were reduced in H2 at 343K for I h under different conditions (liquid phase -LPR or gas phase -GPR). Tue catalytic experiments were carried out in a batch reactor at 333K in four, under flow of gaseous H2 (PH2 = 1 atm). Before reaction, the catalyst was added to the solvent (ethanol) and treated at 343 K for 1 h, under gaseous H2. The results obtained have shown that the reduction conditions (LPR or GPR) mainly lead to an augment of the gold particle size. Increasing the ofthe gold particle size the specific activity, per g of gold on the surface, do not significantly changes whereas the selectivity to the unsaturated alcohol (measured at conv =50%) decreases from 57% up to 45%. A dramatic lowering of the activity and the selectivìty to UA, instead, was found decreasing the surface area of the support. Characterization of the catalysts are in progress in order to identify the nature of the active sites. Keywords: gold supported ceria catalysts, selective hydrogenation, a, p unsaturated ketones.