Palladium Bromide–Palladium Composite for Direct Synthesis of Hydrogen Peroxide

Abstract

Direct synthesis of hydrogen peroxide (H₂O₂, DSHP) from hydrogen (H₂) and oxygen (O₂) is considered the most promising preparation method due to its atomic economy and compliance with the requirements of green chemistry. However, the poor H₂O₂ yield and selectivity still greatly limit its practical application. Herein, we synthesized a series of oxidized palladium and metal palladium composites (Pd²⁺–Pd) using a controlled decomposition method, to develop efficient catalysts for DSHP. The optimized 4% PdBr₂–Pd/C-250-2 catalyst exhibited the excellent catalytic performance for DSHP, with H₂O₂ selectivity of 99.2%, H₂O₂ yield of 346.53 mol·\({\text{kg}}_{{{\text{cat}}{\text{.}}}}^{{ - 1}}\)·h^− 1, and H₂ conversion of 50.7%. The finding indicates that the enhanced catalytic performance of 4% PdBr₂–Pd/C-250-2 is due to the coexistence of PdBr₂, PdO, and Pd, which not only effectively activates H₂ and O₂, but also effectively inhibits the breaking of O–O bonds, greatly reducing the decomposition and hydrogenation activity of H₂O₂, thereby achieving high H₂O₂ yield and selectivity. This article provides important ideas for the development of efficient DSHP catalysts and will promote their industrial applications.