Selective Partial Hydrogenation of Acrolein on Pd: A Mechanistic Study

Identifying the surface processes governing the selectivity in hydrogenation of α,β-unsaturated carbonyl compounds on late transition metals is crucial for the rational design of catalytic materials with the desired selectivity toward C═C or C═O bond hydrogenation. The partial selective hydrogenation of acrolein on a Pd(111) single crystal and Fe3O4-supported Pd nanoparticles under well-defined UHV conditions was investigated in the present study as a prototypical reaction. Molecular beam techniques were combined with infrared reflection–absorption spectroscopy (IRAS) and quadrupole mass spectrometry (QMS) in order to simultaneously monitor the evolution of surface species and the formation of the final gas-phase products under isothermal reaction conditions as a function of surface temperature. Over a Pd(111) single crystal, acrolein is hydrogenated at the C═O bond to form the desired reaction product propenol with nearly 100% selectivity in the temperature range between 250 and 300 K, while over Pd/Fe3O...