Selective hydrogenation of α,β-unsaturated aldehydes and other C=O and C=C bonds containing compounds

Advances in developing new heterogeneous catalysts which hydrogenate preferentially the C=O group of alpha,beta-unsaturated aldehydes to obtain the desired products, namely unsaturated alcohols, will be reviewed by considering the parameters which control the intramolecular selectivity: support material, nature and particle size of the individual metals, selective poisoning, presence of a second metal, preparation method or catalyst precursor, temperature of reduction, host-guest interactions in zeolites, substituents on the C=C bond and pressure effects. Recent attempts with bimetallic and silver catalysts to hydrogenate only the C=O group of other polyfunctional organic compounds in the gas phase without simultaneous hydrogenation of aromatic or furan rings will be shown.