Revealing the role of tellurium in palladium-tellurium catalysts for the direct synthesis of hydrogen peroxide

Abstract

The direct synthesis of H2O2 from H2 and O2 is an atom-efficient alternative to the anthraquinone auto-oxidation process. Herein, we report high-performance alumina supported palladium-tellurium bimetallic catalysts (Pd-Te/Al2O3) for the direct H2O2 synthesis using a semi-continuous process at 283 K and 0.1 MPa. By modifying the Pd catalyst with Te, the H2O2 productivity was markedly increased from 2017 to 2824 mmol h−1gPd−1. The role of Te in H2O2 synthesis was thoroughly studied by multiple techniques including in situ spectroscopies and density functional theory (DFT) calculations. The Pd monometallic sites, especially the high-energy step sites, have demonstrated to be highly active for the dissociation of O2 and the subsequent formation of byproduct H2O. By blocking the high-energy step sites and forming Pd-Te bimetallic sites, Te plays a critical role in suppressing the side reactions and promoting H2O2 synthesis. This work provides inspiration for the rational design of bimetallic catalysts for H2O2 synthesis.