CHEMOSELECTIVE HYDROGENATION OF UNSATURATED CARBONYL-COMPOUNDS OVER GROUP-8 AND GROUP-9 TITANIA-SUPPORTED METAL-CATALYSTS

Chemoselective hydrogenation Of unsaturated carbonyl compounds over Groups 8 and 9 titania-supported metal catalysts was investigated in a pulse reactor. It is shown that when a conjugated aldehyde such as crotonaldehyde is hydrogenated, a high temperature reduction enchances the selectivity of the iridium and ruthenium catalysts in the formation of the unsaturated alcohol, which suggests that decoration of metal particles by titania sub-oxides generates new catalytic sites selective for carbonyl group hydrogenation. However, such behaviour is not observed for the unsaturated ketones.