The direct synthesis of hydrogen peroxide from H₂ and O₂ using Pd-Ni/TiO₂ catalysts

The direct synthesis of hydrogen peroxide (H₂O₂) from molecular H₂ and O₂ offers an attractive, decentralized alternative to production compared to the current means of production, the anthraquinone process. Herein we evaluate the performance of a 0.5%Pd-4.5%Ni/TiO₂ catalyst in batch and flow reactor systems using water as a solvent at ambient temperature. These reaction conditions are considered challenging for the synthesis of high H₂O₂ concentrations, with the use of sub-ambient temperatures and alcohol co-solvents typical. Catalytic activity was observed to be stable to prolonged use in multiple batch experiments or in a flow system, with selectivities towards H₂O₂ of 97% and 85%, respectively. This study was carried out in the absence of halide or acid additives that are typically used to inhibit sequential H₂O₂ degradation reactions showing that this Pd-Ni catalyst has the potential to produce H₂O₂ selectively. This article is part of a discussion meeting issue 'Science to enable the circular economy'.