Is selective hydrogenation of molecular oxygen to H2O2 affected by strong metal–support interactions on Pd/TiO2 catalysts? A case study using commercially available TiO2

In this study, titania-supported Pd catalysts were prepared and their performance evaluated upon H₂O₂ direct synthesis. Typically, the materials contained different ratios of anatase and rutile phases, which gave rise to different surface properties of the supports, e.g., surface area, number of Lewis acidic and basic sites as well as different compositions of the phases, i.e. the amount of anatase phase and crystallite size. Two materials, Pd-A98 and Pd-A05 samples, respectively, apparently hint the existence of the so-called SMSI (strong metal–support interaction) phenomenon giving rise to 1080 and 683 mol_H2O2·mol_Pd⁻¹·h⁻¹ of H₂O₂ productivity and 22 and 14% of H₂O₂ selectivity, respectively. However, the best material, Pd-A82, gave rise to 949 mol_H2O2·mol_Pd⁻¹·h⁻¹ of H₂O₂ productivity and 26% of H₂O₂ selectivity.