Preparation and Synergy of Supported Ru and Pd for Rapid Chlorate Reduction at pH 7.

Chlorate (ClO) is a common water pollutant due to its gigantic scale of production, wide applications in agriculture and industry, and formation as a toxic byproduct in various water treatment processes. This work reports on the facile preparation, mechanistic elucidation, and kinetic evaluation of a bimetallic catalyst for highly active ClO reduction into Cl. Under 1 atm H and 20 °C, Pd and Ru were sequentially adsorbed and reduced on a powdered activated carbon support, affording Ru-Pd/C from scratch within only 20 min. The Pd particles significantly accelerated the reductive immobilization of Ru as >55% dispersed Ru outside Pd. At pH 7, Ru-Pd/C shows a substantially higher activity of ClO reduction (initial turnover frequency >13.9 min on Ru; rate constant at 4050 L h g) than reported catalysts (e.g., Rh/C, Ir/C, Mo-Pd/C) and the monometallic Ru/C. In particular, Ru-Pd/C accomplished the reduction of concentrated 100 mM ClO (turnover number > 11,970), whereas Ru/C was quickly deactivated. In the bimetallic synergy, Ru rapidly reduces ClO while Pd scavenges the Ru-passivating ClO and restores Ru. This work demonstrates a simple and effective design for heterogeneous catalysts tailored for emerging water treatment needs.