Switching Off Hydrogen Peroxide Hydrogenation in the Direct Synthesis Process

Hydrogen peroxide (H₂O₂) is an important disinfectant and bleach and is currently manufactured from an indirect process involving sequential hydrogenation/oxidation of anthaquinones. However, a direct process in which H₂ and O₂ are reacted would be preferable. Unfortunately, catalysts for the direct synthesis of H₂O₂ are also effective for its subsequent decomposition, and this has limited their development. We show that acid pretreatment of a carbon support for gold-palladium alloy catalysts switches off the decomposition of H₂O₂. This treatment decreases the size of the alloy nanoparticles, and these smaller nanoparticles presumably decorate and inhibit the sites for the decomposition reaction. Hence, when used in the direct synthesis of H₂O₂, the acid-pretreated catalysts give high yields of H₂O₂ with hydrogen selectivities greater than 95%.