Replacement reaction-based synthesis of supported palladium catalysts with atomic dispersion for catalytic removal of benzene

Abstract

Increasing the dispersity of noble metals in transition metal oxides is an effective way to increase their activity and utilization for the catalytic removal of volatile organic compounds (VOCs). Herein, we report a strategy to combine the galvanic replacement reaction between copper (Cu) seeds and palladium (Pd) ions in an organic medium with a thermal treatment to produce supported Pd catalysts with atomic dispersion in CuO for the catalytic oxidation of benzene. This strategy involves the synthesis of Cu nanoseeds in oleylamine, the galvanic replacement reaction between Cu seeds and Pd²⁺ ions for forming bimetallic Cu–Pd nanoalloys, the deposition of Cu–Pd nanoalloys on γ-aluminum oxide (γ-Al₂O₃) substrates, and the subsequent thermal treatment for oxidizing the Cu component in the alloy particles. In particular, the catalytic evaluations show that after thermal treatment, the γ-Al₂O₃-supported Cu–Pd particles with a Pd/Cu ratio of 1/1 exhibit the best performance, while those with the Pd/Cu ratio of 0.2/1 have the best turnover frequency (TOF) for benzene conversion due to the interaction between Pd and CuO (formed by thermal treatment) and the high dispersity of Pd in CuO. The study in this work may provide a way to efficiently utilize the noble metals and offer a concept to design cost-effective and more active noble metal catalysts for the complete oxidation of VOCs.