Tuning the properties of PdAu bimetallic nanocatalysts for selective hydrogenation reactions

Abstract

Bimetallic PdAu nanocatalysts have been prepared in a one-step synthesis using a colloidal approach, with a variety of techniques employed to determine their structure. The supported nanocatalysts show good performance in the selective hydrogenation of 2-chloronitrobenze to 2-chloroaniline and the direct formation of hydrogen peroxide. The reaction rate for 2-chloronitrobenzene hydrogenation increased with the decrease of Pd/Au ratio, while the selectivity was only slightly affected. The structure of the bimetallic nanoparticles had a significant impact, with a Pd-rich surface offering superior selectivity and reaction rates. In contrast, for hydrogen peroxide synthesis, it was found that there was an optimal quantity of gold required to ensure high productivity and this is ascribed to avoiding the formation of Au rich alloy phase and electronic effects hindering the necessary O₂ adsorption and activation.