When high metal dispersion has a detrimental effect: Hydrogen peroxide direct synthesis under very mild and nonexplosive conditions catalyzed by Pd supported on silica

► Pd/SiO2 catalysts were studied in H2O2 direct synthesis under mild and nonexplosive conditions. ► The optimum Pd content is 1.5 wt.% and calcination is mandatory to preserve catalytic performance. ► Pd/SiO2 gives the highest selectivity and productivity under the adopted experimental conditions (Pd/SiO2>Pd/ZrO2/SO4=>Pd/ZrO2>Pd/CeO2/SO4=>Pd/CeO2). ► Less energetic Pd sites, where O2 chemisorbs without dissociation, are necessary to produce H2O2.