Bimetallic Pd–Au catalysts for benzaldehyde hydrogenation: Effects of preparation and of sulfur poisoning

The sulfur poisoning of carbon-supported bimetallic Pd–Au systems was investigated. Catalytic activity results for benzaldehyde hydrogenation clearly show that gold addition improves catalyst resistance to sulfur poisoning with respect to the monometallic Pd-based sample. Samples were characterized by pulse-flow CO chemisorption and XRD in order to correlate the structural properties with the resistance to sulfur poisoning. Gold addition prevents the progressive transformation of Pd in Pd4S in the presence of sulfur compounds by hindering the availability of ensembles of four Pd atoms in the correct geometrical configuration.